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Percutaneous posterolateral approach for the simulation of a far-lateral disc herniation in an ovine model

TL;DR: A minimally invasive damage model for ovine lumbar discs via partial nucleotomy using a posterolateral approach allows operation on several discs within a single surgery and multiple animal surgeries within asingle day.
Abstract: This work describes a minimally invasive damage model for ovine lumbar discs via partial nucleotomy using a posterolateral approach. Two cadavers were dissected to analyze the percutaneous corridor. Subsequently, 28 ovine had their annulus fibrosus punctured via awl penetration under fluoroscopic control and nucleus pulposus tissue removed via rongeur. Efficacy was assessed by animal morbidity, ease of access to T12-S1 disc spaces, and production of a mechanical injury as verified by discography, radiography, and histology. T12-S1 were accessible with minimal nerve damage morbidity. Scar tissue sealed the disc puncture site in all animals within 6 weeks, withstanding 1 MP of intradiscal pressure. Partial nucleotomy led to a significant reduction in intervertebral disk height and an increased histological degeneration score. Inducing a reproducible injury pattern of disc degeneration required minimal time, effort, and equipment. The posterolateral approach allows operation on several discs within a single surgery and multiple animal surgeries within a single day.

Summary (3 min read)

Introduction

  • Knowledge of the fundamental mechanisms underlying intervertebral disc degeneration has improved significantly in recent years [1].
  • Depending on the severity of degeneration, various treatments have been discussed, including gene, growth factor, or cell therapies [2, 3].
  • The ovine model stands out for evaluating degradation and regeneration of the spine [4, 5], with a proven comparability to human intervertebral disc anatomy [6], intradiscal pressure [4], biomechanical stress [5], and cell physiology [7].
  • Percutaneous puncture, used in small animal models like rabbits [9], is often not described for large animal models.
  • Approach outcome is evaluated by intraoperative radiography and postoperative histology.

Animal model

  • This study, approved by the animal ethics committee of Saxony, Germany, involved 28 ovines meeting the inclusion criteria: healthy adult females (age 2–3 years) of normal weight (52–84 kg, μ = 65.7, σ = 8.87) with full mobility.
  • Each animal was pre-reviewed to verify their spine health with no preexisting conditions or damage.
  • Each animal was kept in an indoor recovery enclosure for 1 week postoperatively.
  • Subsequently, all animals were released for daytime grazing and allowed their natural rhythm of movement.

Anesthetic protocol

  • Each animal was fasted for 12 h preoperatively to prevent abdominal distension and aspiration during surgery.
  • Midazolam (0.2 mg/kg) and butorphanol (0.2 mg/kg) was injected intramuscularly for sedation.
  • After insertion of a jugular vein intravenous line, intravenous anesthesia preparation medication was introduced: xylazine (0.2 mg/kg), ketamine (10–15 mg/kg), and atropine (0.2 mg/kg) to prevent hypersalivation.
  • An endotracheal tube was inserted and anesthesia maintained by isoflurane inhalation (2–3% in oxygen) under continuous cardiac and ventilation monitoring by a Dräger Sulla 808 anesthesia tower (Dräger, Lübeck, Germany).
  • A gastral tube was inserted and all animals received perioperative intravenous antibiotics .

Surgical technique

  • All lumbar disc levels (T12/L1 to L5/L6) are accessible using the posterolateral approach.
  • Access to the L6/S1 disc can prove difficult due to obstruction from the iliac crest.
  • This procedure can be performed in under 30 min (26–60 min, μ = 36.1, σ = 8.87) with minimal blood loss and postoperative discomfort to the animal, representing quantitative advantages over previously published disc approaches.
  • Approximately, ten intra-operative images were taken per surgery (Fig. 5) to demonstrate and verify instrument positioning.
  • This X-ray dosage corresponds to a minimal level of radiation exposure.

Intraoperative imaging and discography

  • Intraoperative imaging was performed with a C-arm in anterior/posterior projection.
  • Discography of the damaged disc was performed 6 weeks postoperatively for all animals to demonstrate defect closure, resealing access to the NP.
  • For this purpose, the damaged disc was punctured with a SPROTTE® cannula (PAJUNK Medical, Germany) on the contralateral side of the initial surgery and filled with Solutrast 200 contrast agent (Bracco Imaging Deutschland GmbH, Germany) to a pressure of 1 MPa.

Postoperative management

  • Following spontaneous breathing, each animal was extubated and transferred to their holding pens.
  • Flunixin was given as the postoperative analgesic and antibiotics (veracincompositum, 3 ml/50 kg Kgw.) administered for 10 days.

Tissue removal

  • Animals were humanely euthanized during standard anesthesia by intravenous administration of 6 ml/50 kg T61 (active agents: embutramide, mebenzoniumiodide, tetracaine).
  • After confirming cardiac arrest, the lumbar spine was excised and each motion segment isolated by cutting through the midaxial planes of the vertebral bodies.
  • Dorsal and transverse processes, zygapophyseal joints, and spinal cord were removed.

Micro‑computed tomography (µ‑CT)

  • Samples were stored at − 36 °C to prevent postmortem manipulative tissue damage or degeneration.
  • Μ-CT was performed using a phoenix nanome|x 180NF (GE, USA), an X-ray cone-beam system with a flat detector array and image amplifier, operated with increasing radiation intensity and extended integration times.
  • Resulting voxel size was 25 microns, allowing visualization of the IVD lamellar structure.
  • Average disc height was evaluated along the disc’s anteroposterior midline from µ-CT radiographs [14].
  • Statistical data analysis included one-way ANOVA along with Tukey’s test to verify the significance of mean values.

Histology and light microscopy

  • Motion segments were fixed for 7 days in 2.5% glutaraldehyde PBS buffer, re-frozen, and trisected.
  • Samples were dehydrated via ascending ethanol series and embedded in Technovit9100 resin (Heraeus Kulzer, Germany).
  • Samples were Masson–Goldner stained [15], then visually recorded using Slide ScannerZEISS Axio Scan.Z1 (Zeiss, Germany).
  • This method characterizes the level of disc degeneration on a scale of 0 to 2 for three key regions of the disc: the annulus fibrosus, AF-NP border, and NP matrix.
  • Therefore, final scores fall between 0 (no degeneration in any region) and 6 (degeneration in all regions).

Cadaver evaluation

  • Cadaver dissection revealed a safe entry point 12 cm lateral of the spinous process line (Fig. 1a).
  • A straight surgical corridor to the nucleus pulposus was identified (Fig. 1b), free of anatomical barriers like the ipsilateral transverse process, segmental facet, and segmental spinal nerve roots.
  • Figure 4 shows intradiscal positioning and puncture direction in relation to bony landmarks.

Intraoperative complications

  • None of the animals showed intraoperative pain reactions (e.g., teeth grinding) or cardiovascular abnormalities in central venous pressure, pulmonary arterial pressure, cardiac output, heart rate, oxygen saturation, or arterial blood gas.
  • One animal was excluded from the test series due to inadequate independent respiration following anesthesia.
  • Bleeding from small subcutaneous vessels occurred in some animals during surgery, but was abated by simple compression.
  • None of the operations resulted in major vessel injury, spinal cord hemorrhage, or direct nerve stimulation (limb movement).

Postoperative complications

  • Soft tissue damage along the operative corridor was minimal, resulting in fast wound healing and recovery.
  • The majority of test animals began breathing independently and consuming food 10–15 min after anesthesia ended.
  • One animal demonstrated a partial loss of motor function in the hind limbs, manifesting as delayed postoperative rising, uncertain gait, and a preference to remain lying down and inactive.
  • This animal was unable to independently join the herd after a week and was removed from the test series.

Induction of IVD degeneration

  • A second discography was performed at 6 week post-op.
  • All damaged segments were pressure stable at 1 MPa, with no pressure drop observed over a 15-min period.
  • As verified by histology (Fig. 6h), scar tissue had pressure sealed the peripheral AF following injury.
  • In comparison to the intact AF architecture of the native disc (Fig. 6e), the damaged disc’s AF shows permanent alteration of the fiber structure (Fig. 6f, arrows) and a discernible puncture duct following NP tissue removal.
  • Disc height loss after 6 weeks was substantial (Fig. 6a, b), with an average 25% reduction.

Discussion

  • Ovines are commonly used in preclinical spine research to develop implants and cell/drug therapies due to comparable anatomy to humans [16–18].
  • Due to the geometry of the awl and rongeur, the puncture corridor is discernible 6 weeks after injury by irregularities in the AF lamellar structure.
  • This is due to the fact that control discs and experimental discs were taken from the same animal and disc injury/herniation has an indirect pathological effect on the rest of the lumbar spine.
  • One animal was excluded from the test series due to inadequate independent respiration following anesthesia; the cause remains unknown.
  • The surgical risks of previously reported surgical methods are considered by the authors to be much greater, necessitating open surgery (and, therefore, retraction of major structures) or drilling through bony structures, e.g., the endplate.

Conclusions

  • The presented surgical technique is a percutaneous posterolateral approach to simulate a far-lateral disc herniation, demonstrating a minimally invasive and time efficient alternative to open anterior, anterolateral, and lateral approaches to the ovine lumbar spine.
  • Using this approach, regenerative therapies can be tested for efficacy in the context of a lumbar disc herniation.
  • The authors would like to thank W. Petzold and M. Menzel for technical assistance.
  • Compliance with ethical standards Conflict of interest.
  • All the authors declare that they have no conflict of interest.

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https://helda.helsinki.fi
Difference in voice problems and noise reports between
teachers of public and private schools in Upper Egypt
Abo-Hasseba, Ahmed
2017-07
Abo-Hasseba , A , Waaramaa , T , Alku , P & Geneid , A 2017 , ' Difference in voice
problems and noise reports between teachers of public and private schools in Upper Egypt '
, Journal of Voice , vol. 31 , no. 4 , UNSP 508.e11 . https://doi.org/10.1016/j.jvoice.2016.10.016
http://hdl.handle.net/10138/297837
https://doi.org/10.1016/j.jvoice.2016.10.016
publishedVersion
Downloaded from Helda, University of Helsinki institutional repository.
This is an electronic reprint of the original article.
This reprint may differ from the original in pagination and typographic detail.
Please cite the original version.

Difference in Voice Problems and Noise Reports
Between Teachers of Public and Private Schools in
Upper Egypt
*Ahmed Abo-Hasseba, Teija Waaramaa, Paavo Alku, and §Ahmed Geneid, *Minia, Egypt, and Tampere, Espoo, and
§Helsinki, Finland
Summary: Objective. This study aimed to assess teachers’ voice symptoms and noise in schools in Upper Egypt
and to study possible differences between teachers in public and private schools.
Study Design. A cross-sectional analysis via questionnaire was carried out.
Methods. Four schools were chosen randomly to represent primary and preparatory schools as well as public and
private ones. In these schools, a total of 140 teachers participated in the study. They answered a questionnaire on vocal
and throat symptoms and their effects on working and social activities, as well as levels and effects of experienced
noise.
Results. Of all teachers, 47.9% reported moderate or severe dysphonia within the last 6 months, and 21.4% reported
daily dysphonia. All teachers reported frequent feelings of being in noise, with 82.2% feeling it sometimes or always
during the working day, resulting in a need to raise their voice. Teachers in public schools experienced more noise
from nearby classes.
Conclusion. The working conditions and vocal health of teachers in Upper Egypt, especially in public schools, are
alarming.
Key Words: Egypt–Teachers–Voice–Public schools–Private schools.
INTRODUCTION
The voice is the main tool in classroom teaching. Teachers place
heavy demands on their voice, often instructing for many hours
in acoustically challenging environments without much time for
the voice to rest.
1
Voice disorders are more prevalent in teach-
ers (15%–86%) than among the general population (6%–15%).
2
Vocal problems can have a significant impact on the work ca-
pacity of school teachers, leading to important financial and
vocational costs to the community, teachers, and their families.
3
Risk factors for voice problems among teachers include female
gender,
1,4,5
more years of teaching,
1,6
and poor classroom
environment.
7,8
Other risk factors include smoking
9
and upper
airway problems.
8
In Egypt, the law requires that all children should be en-
rolled in basic education from the age of 6 until the age of 14.
The 9 years of so-called basic education are divided into 3 years
in preparatory school and then 6 years in primary school.
10
School teachers in Egypt have hardly ever been examined for
voice and throat symptoms. Average salaries of teachers in schools
in Egypt are not certain; however, current news reports point to
it being between EUR 100 and 250 per month.
11
Salaries in
schools run by the government fall into the low end of the range,
whereas teachers in private schools are in the upper range. Because
of low salaries, teachers often work after hours, giving private
tuition or doing other jobs.
The factors discussed above predict that occupational voice
disorders may be more frequent among teachers in public than
in private schools. Egypt’s unique educational system, which re-
flects the social classes of Egyptian society, motivated us to study
its effects on the voices of teachers in Egypt’s public and private
schools.
AIMS
The study aimed to assess voice symptoms among teachers in
Upper Egypt with a special emphasis on the differences between
teachers working in public vs private schools, as well as noise
perception in teacher’s working environment.
SUBJECTS AND METHODS
In the Governorate of El-Minia in Upper Egypt, primary and pre-
paratory schools were divided into four blocks. Each was either
preparatory or primary and public or private. Schools were chosen
randomly from each block. From these schools, 200 teachers were
invited to participate in the study, with 140 agreeing to partic-
ipate (nearly equal among the four schools and primary and
public; females = 85). Of the 69 participants in primary schools,
36 were in public and 33 in private schools, and for preparato-
ry schools (n = 71), the figures were 34 teachers and 37,
respectively. Answering questionnaires was carried out in the
workplaces of participating teachers, with the first author avail-
able to help in case something needed clarification.
The teachers were asked to fill a questionnaire about their sub-
jective assessment of their voice, noise, and background
information:
1. Age, years of experience, type of school, hours spent using
her/her voice in teaching and other administrative or social
Accepted for publication October 20, 2016.
Disclosure: The authors have no funding, financial relationships, or conflicts of interest
to disclose.
From the *Department of Otorhinolaryngology—Phoniatric Unit, Faculty of Medicine,
Minia University, Minia, Egypt; †School of Communication, Media and Theatre, Univer-
sity of Tampere, Tampere, Finland; ‡Department of Signal Processing and Acoustics, Aalto
University, Espoo, Finland; and the §Department of Ear, Nose and Throat—Head and Neck
Surgery, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.
Address correspondence and reprint requests to Ahmed Geneid, Department of
Otorhinolaryngology—Head and Neck Surgery, Helsinki University Central Hospital,
University of Helsinki, P.O. Box 220, Helsinki 00029, Finland. E-mail:
ahmed.geneid@hus.fi
Journal of Voice, Vol. 31, No. 4, pp. 508.e11–508.e16
0892-1997
© 2017 The Voice Foundation. Published by Elsevier Inc. All rights reserved.
http://dx.doi.org/10.1016/j.jvoice.2016.10.016

encounters, and voice-related jobs or hobbies. Voice-
related medical history and frequency of upper respiratory
infections were also asked.
2. Voice and throat symptoms during the last 6 months pre-
ceding the study, frequency and severity of different
symptoms, and effects of these on work and social ac-
tivities. Severity was assessed by asking the teacher to
choose one of the four grades of none, mild, moderate,
or severe.
3. Effects, levels, and types of noise experienced during the
working day.
The study received ethical committee approval from Minia
University. It also received the approval of the undergraduate
educational authorities in Minia, Egypt.
STATISTICS
Descriptive statistics were used for the percentages and fre-
quencies of symptoms of background information, voice
symptoms, and noise reports among the teachers. Differences
in the distribution of these findings between teachers working
in public and private schools were examined using the Mann-
Whitney U test. Significance level was set at P < 0.05 in all
statistical analyses. The statistical analyses were carried out with
SPSS 22 software (IBM SPSS Statistics v. 22 for Windows,
Armonk, NY).
RESULTS
Background information and voice use
Mean age of all teachers was 35.8 years (range 21–56 years).
There was a significant difference (P < 0.00) between the mean
age of teachers in public schools in comparison to private ones,
at 40.6 and 30.9 years, respectively. When asked about differ-
ent diseases with possible effects on the voice in the 6 months
preceding this study, 10 reported having asthma, 29 gastric reflux,
39 chronic sinusitis, and 27 hearing impairment. Only eight teach-
ers were smokers.
Average years of experience teaching was also significantly
different (P < 0.001) between public school (17.9 years) and
private school (7.4 years) teachers, with a total average of 12.3
years for the two groups combined. Also, the average class size
was significantly higher in public schools (39 children; P < 0.001)
than in private schools (33 children).
On voice use, 61% of teachers reported teaching without in-
tervals, with no significant difference found between the public
and private schoolteachers. On duration of teaching, teachers
taught for 4 hours in public schools and 4.9 hours per day in
private school (nonsignificant difference). Public school teach-
ers talked with their colleagues on average for 1.9 hours per day
in comparison to 1.8 hours in private schools.
Of the 140 teachers, only 18 (12.9%) reported giving private
tuition to children after the end of the official school day. Nine
(6.4%) teachers reported having a second evening job other than
teaching and all reported having to deal with customers (eg retails
shops, sports coaching, and call centers).
None of the teachers reported nonreligious singing as a hobby,
although seven (5%) sang in church choirs. Of the teachers, 26
(18.6%) recited the Quran regularly at home or taught it to others.
Five (3.6%) gave lectures at mosques. Among public school teach-
ers, 35 (50%) had no other voice-related second job or hobby;
the same was reported by 41 teachers (58.6%) in private schools.
There were no significant differences by school type for voice-
related out-of-hours work and hobbies.
Voice and throat symptoms and their effects on
work and social activities
Almost half of teachers (47.9%) reported moderate and severe
dysphonia daily or weekly within the last 6 months. Reports of
throat pain, dryness, or clearing, as well as failing voice by the
end of the work day were also common (see
Table 1).
No significant difference in severity and frequency of voice
and throat symptoms was found between public and private school
teachers, except for the symptom “voice failing by the end of
working day, which teachers in public schools reported more
often (P = 0.03; see
Table 2).
We also examined the effects of voice and throat symptoms
on out-of-hours work and social activities (
Table 3). Needing
extra effort to complete speech was reported by almost a fifth
of teachers (17.9%). In addition, 10.7% of teachers experi-
enced increased absence from school (1–2 days in the last 6
months) or a decrease in income because of voice symptoms.
These two symptoms were more common in public than private
school teachers (
Table 4).
When asked if their voice is heard clearly by others on account
of possible voice problems, 104 teachers reported their voice being
heard clearly, 34 reported their voice being somewhat heard, and
2 reported that their voice was not heard clearly.
Effects, levels, and types of noise experienced
during the working day
Teachers reported always (34; 24.2%), sometimes (81; 57.9%),
rarely (18; 12.9%), and never (7; 5%) “feeling of being in noise,
whereas the respective figures for having to raise their voice
because of noise were 72 (51.4%), 46 (32.9%), 16 (11.4%), and
6 (4.3%). None of the teachers used amplifiers during work. A
significant but low correlation was found between presence of
hearing impairment and increase in the need to raise voice because
of noise (r = 0.23, P = 0.006).
Figure 1 shows the distribution
of reports of “feeling of being in noise” among public and private
school teachers.
Figure 2 shows the percentage of teacher reports on differ-
ent sources of noise. Noise coming from nearby classes was the
only type that showed a statistically significant difference between
teachers in public and private schools (P = 0.001).
Doors and windows in classrooms were reported to be always
(32; 22.9%), sometimes (71; 50.7%), rarely (19; 13.6%), and
never (18; 12.9%) closed. Two (0.014%) public school teach-
ers reported a broken window in their classroom. In addition,
over a third of teachers (56; 40%) reported working in class-
rooms where the door was broken, with a significant difference
(P = 0.001) between public (38; 27.1%) and private (18; 12.9%)
schools. A significantly positive but low correlation (r = 0.21,
Ahmed Abo-Hasseba, et al Voice Problems Among Teachers in Upper Egypt 508.e12

P = 0.01) was found between noise coming from nearby classes
and a broken door in the classroom.
Ad hoc analysis on difference between primary and prepara-
tory schools’ teachers was carried out as well. Teachers working
in primary schools had a mean age of 34 years whereas in pre-
paratory schools the mean age was 37.5 years (P = 0.32). Average
years of teaching experience was also significantly different
(P = 0.046) between primary school (11.3 years) and prepara-
tory school (14 years) teachers. Reports of dysphonia severity
were more common among primary school teachers, with 58%
of teachers reporting moderate or severe dysphonia in compar-
ison to 48% among teachers in preparatory schools (P = 0.017).
Reports of extra effort to complete speech were also more
common among teachers in primary school than those in pre-
paratory schools. Among teachers of primary schools, 32.6%
reported no need for extra effort in comparison to 54.9% among
teachers of preparatory schools.
DISCUSSION
Teachers in public schools experienced more voice and throat
symptoms and more often had a feeling of being in noise, with
more effects on their working and social conditions than teach-
ers in private schools.
TABLE 1.
Distribution of Severity (A) and Frequency (B) of Different Voice and Throat Symptoms Among Studied Teachers,N=140
A. Severity of Reported Symptom
Parameter
Severity of Reported Symptom
None Mild Moderate Severe
Dysphonia 26 (18.6%) 47 (33.6%) 54 (38.6%) 13 (9.3%)
Throat pain 45 (32.1%) 37 (26.4%) 43 (30.7%) 15 (10.7%)
Throat clearing 27 (19.3%) 46 (32.9%) 49 (35%) 18 (12.9%)
Throat dryness 24 (17.1%) 50 (35.7%) 49 (35%) 17 (12.1%)
Voice not coping by the end of working day 44 (31.4%) 43 (30.7%) 35 (25%) 18 (12.9%)
B. Frequency of Reported Symptom
Parameter
Frequency of Reported Symptom
Less
Recurrence
Monthly
Recurrence
Weekly
Recurrence
Daily
Recurrence
Dysphonia 54 (38.6%) 28 (20%) 28 (20%) 30 (21.4%)
Throat pain Some left this unassessed so we excluded its results.
Throat clearing 42 (30%) 19 (13.6%) 40 (28.6%) 39 (27.8%)
Throat dryness 39 (27.8%) 22 (15.7%) 37 (26.4%) 42 (30%)
Voice not coping by the end of working day Some left this unassessed so we excluded its results.
TABLE 2.
Distribution of Severity of Symptom “Voice Failing by the End of Work Day” Among Teachers of Public and Private Schools
Voice Not Coping by the End of Working Day None Mild Moderate Severe
Public schools
* 17 (24.3%) 22 (31.4%) 18 (25.7%) 13 (18.6%)
Private schools 27 (38.6%) 21 (30.0%) 17 (24.3%) 5 (7.1%)
* P = 0.03.
TABLE 3.
Distribution of Frequency Reports on the Effects of Voice and Throat Symptoms on Work and Social Activities
Parameter No Sometimes Very Often
Voice problems restrict personal and social life 103 (73.6%) 30 (21.4%) 7 (5%)
Extra effort to complete speech 64 (45.7%) 51 (36.4%) 25 (17.9%)
Feeling annoyed from questions about own voice sounding abnormal 108 (77.1%) 28 (20%) 4 (2.9%)
Parameter Never 1–2 Days >2 Days
Voice problems lead to increased absence from school and decrease
in income within the last 6 months
122 (87.2%) 15 (10.7%) 3 (2.1%)
508.e13 Journal of Voice, Vol. 31, No. 4, 2017

Private schools in Egypt are usually favored by parents on the
basis of fewer children in the classrooms. However, an average
class size of 39 children in public schools and 33 in private ones
is still alarmingly high, even for private schools. A study of 550
primary school teachers in Dublin found that 49.67% of teach-
ers reported voice problems when teaching a class size >30 pupils
in comparison to 30.26% when the class size was <30 pupils.
12
Teachers of large classes have shown three times the occur-
rence of voice disorders in comparison to teachers of smaller
classes.
13
Another interesting finding is that none of the teachers re-
ported nonreligious singing among their hobbies. This may be
attributed to the cultural background in Upper Egypt which favors
predominantly religious singing and reciting of holy books.
The finding that 61% of all teachers reported teaching without
intervals, which is quite high in terms of the teachers’ need of
voice rest, is in line with previous findings of Sala et al on the
lack of vocal rest among primary school teachers.
14
Teachers’ reports on voice and throat symptoms and their
effects on working and social activities were also striking. Only
18.6% of teachers did not have dysphonia during the last 6
months. Nearly half of teachers rated their dysphonia as mod-
erate or severe, with 21.4% reporting dysphonia on a daily basis.
High percentages of voice disorders are known to happen among
school teachers.
15
The overall lifetime occurrence of voice dis-
orders among school teachers was reported to be 68.7% among
425 teachers studied in Poland.
16
A study in Ireland reported that
80% of 243 teachers
17
had either a current or intermittent voice
problem. A study in northern Egypt found that the prevalence
of subjectively reported dysphonia was 23.2% during the time
of the study.
18
In our study, 70% of teachers reported their voice failing by
the end of the day, being more severe among public school teach-
ers. It is possible that the more crowded classrooms in public
schools, which impose more vocal loading on teachers, is one
of the reasons behind this. Nevertheless, teachers in public schools
TABLE 4.
Frequency of Two Parameters of Effects of Voice and Throat Symptoms on Work and Social Activities
Parameter School Type Never 1–2 Days >2 Days
Voice problems lead to increased absence
from school and decrease in income
Public 57 (81.4%) 11 (15.7%) 2 (2.9%)
Private
* 65 (92.9%) 4 (5.7%) 1 (1.4%)
Parameter School Type No Sometimes Very Often
Extra effort to complete speech Public 28 (40%) 24 (34.3%) 18 (25.7%)
Private
** 36 (51.4%) 27 (38.6%) 7 (10%)
* P = 0.046; ** P = 0.047.
FIGURE 1. Frequency distribution of reports of “feeling of being in noise” among public and private school teachers.
Ahmed Abo-Hasseba, et al Voice Problems Among Teachers in Upper Egypt 508.e14

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Journal ArticleDOI
TL;DR: In this article, an injectable chitosan carboxymethyl cellulose hydrogel scaffold was evaluated regarding its intraoperative handling, crosslinking kinetics, cell viability, fully-crosslinked viscoelasticity, and long-term therapeutic effects in an ovine model.
Abstract: The potential therapeutic benefit of adipose-derived stem cells (ASCs) encapsulated in an injectable hydrogel for stimulating intervertebral disc (IVD) regeneration has been assessed by a number of translational and preclinical studies. However, previous work has been primarily limited to small animal models and short-term outcomes of only a few weeks. Long-term studies in representative large animal models are crucial for translation into clinical success, especially for permanent stabilization of major defects such as disc herniation. An injectable chitosan carboxymethyl cellulose hydrogel scaffold loaded with ASCs was evaluated regarding its intraoperative handling, crosslinking kinetics, cell viability, fully-crosslinked viscoelasticity, and long-term therapeutic effects in an ovine model. Three IVDs per animal were damaged in 10 sheep. Subcutaneous adipose tissue was the source for autologous ASCs. Six weeks after IVD damage, two of the damaged IVDs were treated via ASC-loaded hydrogel injection. After 12 months following the implantation, IVD disc height and histological and cellular changes were assessed. This system was reliable and easy to handle intraoperatively. Over 12 months, IVD height was stabilized and degeneration progression significantly mitigated compared to untreated, damaged IVDs. Here we show for the first time in a large animal model that an injectable chitosan carboxymethyl cellulose hydrogel system with encapsulated ASCs is able to affect long-term stabilization of an injured IVD and significantly decrease degeneration processes as compared to controls.

8 citations

Journal ArticleDOI
TL;DR: Assessment of the long‐term progression of degeneration in the ovine lumbar spine following a minimally invasive model injury comparable to the damage of an intervertebral disc (IVD) herniation provides a useful model injury for the preclinical evaluation of IDD in large animal models.

8 citations


Cites methods from "Percutaneous posterolateral approac..."

  • ...15 cm(3), as described by Schwan et al.(17) Both steps were carried out under X‐ray control....

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  • ...1C), of approximately 0.15 cm3, as described by Schwan et al.17 Both steps were carried out under X‐ray control....

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Journal ArticleDOI
TL;DR: The use of animal models in isolation will not allow resolution of this complex issue and a paradigm shift and adoption of new methodologies is required to provide the next step forward in the determination of an effective repairative strategy for the IVD as mentioned in this paper .
Abstract: Animal models have been invaluable in the identification of molecular events occurring in and contributing to intervertebral disc (IVD) degeneration and important therapeutic targets have been identified. Some outstanding animal models (murine, ovine, chondrodystrophoid canine) have been identified with their own strengths and weaknesses. The llama/alpaca, horse and kangaroo have emerged as new large species for IVD studies, and only time will tell if they will surpass the utility of existing models. The complexity of IVD degeneration poses difficulties in the selection of the most appropriate molecular target of many potential candidates, to focus on in the formulation of strategies to effect disc repair and regeneration. It may well be that many therapeutic objectives should be targeted simultaneously to effect a favorable outcome in human IVD degeneration. Use of animal models in isolation will not allow resolution of this complex issue and a paradigm shift and adoption of new methodologies is required to provide the next step forward in the determination of an effective repairative strategy for the IVD. AI has improved the accuracy and assessment of spinal imaging supporting clinical diagnostics and research efforts to better understand IVD degeneration and its treatment. Implementation of AI in the evaluation of histology data has improved the usefulness of a popular murine IVD model and could also be used in an ovine histopathological grading scheme that has been used to quantify degenerative IVD changes and stem cell mediated regeneration. These models are also attractive candidates for the evaluation of novel anti‐oxidant compounds that counter inflammatory conditions in degenerate IVDs and promote IVD regeneration. Some of these compounds also have pain‐relieving properties. AI has facilitated development of facial recognition pain assessment in animal IVD models offering the possibility of correlating the potential pain alleviating properties of some of these compounds with IVD regeneration.

4 citations

References
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Journal ArticleDOI
TL;DR: Results suggest that there were many personal, family, or social factors that were linked to prossocial behavior, and prosocial reasoning might only contribute to a small proportion of variation in prosocial behavior among adolescents.
Abstract: This study attempted to develop a standardized instrument for assessment of prosocial reasoning in Chinese populations. The Prosocial Reasoning Objective Measure (PROM) was translated, and a two-stage study was conducted to evaluate the psychometric properties of the translated instrument. The content validity, cultural relevance, and reading level of the translated instrument were evaluated by an expert panel. Upon revisions according to the expert opinions, the Chinese PROM demonstrated good content validity, “good-to-very good test-retest” reliability, and internal consistency. However, only partial support to the convergent validity of the Chinese PROM was found. In the first stage of the study (n = 50), the PROM scores had high positive correlations with empathy and negative correlations with personal distress and fantasy. These results were consistent with theoretical expectations, although this is also a concern that empathy had a close-to-unity correlation with PROM score in the small sample study of stage 1. In the second stage of the study (n = 566), the relationship between PROM scores and prosocial behavior appeared to be weak. Results suggest that there were many personal, family, or social factors that were linked to prosocial behavior, and prosocial reasoning might only contribute to a small proportion of variation in prosocial behavior among adolescents.

648 citations

Journal ArticleDOI
TL;DR: Although animal models are invaluable to increase the understanding of disc biology, care must be taken when used to study human disc degeneration and much more effort is needed to facilitate research on human disc material.
Abstract: Intervertebral disc (IVD) degeneration is an often investigated pathophysiological condition because of its implication in causing low back pain. As human material for such studies is difficult to obtain because of ethical and government regulatory restriction, animal tissue, organs and in vivo models have often been used for this purpose. However, there are many differences in cell population, tissue composition, disc and spine anatomy, development, physiology and mechanical properties, between animal species and human. Both naturally occurring and induced degenerative changes may differ significantly from those seen in humans. This paper reviews the many animal models developed for the study of IVD degeneration aetiopathogenesis and treatments thereof. In particular, the limitations and relevance of these models to the human condition are examined, and some general consensus guidelines are presented. Although animal models are invaluable to increase our understanding of disc biology, because of the differences between species, care must be taken when used to study human disc degeneration and much more effort is needed to facilitate research on human disc material.

608 citations


"Percutaneous posterolateral approac..." refers background in this paper

  • ...Currently, mechanical overload (compressive stress) [8] and chemical injection [7] are common methods for initiating degradation or large-scale structural damage in the spine....

    [...]

Journal ArticleDOI
01 Aug 1990-Spine
TL;DR: Progressive failure of the inner anulus was seen in all sheep and occurred in the majority of discs between 4 and 12 months after the operation, suggesting that discrete tears of the outer anulus may have a role in the formation of concentric clefts and in accelerating the development of radiating clefts.
Abstract: An animal model was developed to test the hypothesis that discrete peripheral tears within the anulus lead to secondary degenerative changes in other disc components In 21 adult sheep, a cut was made in the left anterolateral anulus of three randomly selected lumbar discs The cut was parallel and adjacent to the inferior end-plate, and had a controlled depth of 5 mm This left the inner third of the anulus and the nucleus pulposus intact and closely reproduced the rim Lear lesion described by Schmorl Animals were randomly allocated to different groups in relation to the length of time interval between operation and death, varying from 1 to 18 months At death, the lumbar spine was cut into individual joint units and each disc sectioned into six parasagittal slabs After observation of the slabs under the dissecting microscope, two of the six slabs, the one containing the anulus lesion and a contralateral, were processed for histology The results of this study suggest that, despite the great care taken at operation to ensure that the inner anulus was left intact, progressive failure of the inner anulus was seen in all sheep and occurred in the majority of discs between 4 and 12 months after the operation Although the outermost anulus showed the ability to heal, the defect induced by the cut led initially to deformation and bulging of the collagen bundles, and eventually to inner extension of the tear and complete failure These findings suggest that discrete tears of the outer anulus may have a role in the formation of concentric clefts and in accelerating the development of radiating clefts Peripheral tears of the anulus fibrosus therefore may play an important role in the degeneration of the intervertebral joint complex

396 citations

Journal ArticleDOI
TL;DR: Detailed basic research on IVD cells and their niche indicates that transplanted cells are unable to survive and adapt in the avascular niche of the IVD, and therefore this therapeutic strategy to succeed needs to be better defined.
Abstract: After outlining the rationale for injecting viable cells into the degenerating intervertebral disc (IVD), Sakai and Andersson provide an overview of basic and preclinical studies as well as ongoing clinical trials of cell therapies for IVD degeneration. Consideration is also given to various barriers to the development of these therapies and possible solutions to overcome such obstacles. Intervertebral disc (IVD) degeneration is frequently associated with low back and neck pain, which accounts for disability worldwide. Despite the known outcomes of the IVD degeneration cascade, the treatment of IVD degeneration is limited in that available conservative and surgical treatments do not reverse the pathology or restore the IVD tissue. Regenerative medicine for IVD degeneration, by injection of IVD cells, chondrocytes or stem cells, has been extensively studied in the past decade in various animal models of induced IVD degeneration, and has progressed to clinical trials in the treatment of various spinal conditions. Despite preliminary results showing positive effects of cell-injection strategies for IVD regeneration, detailed basic research on IVD cells and their niche indicates that transplanted cells are unable to survive and adapt in the avascular niche of the IVD. For this therapeutic strategy to succeed, the indications for its use and the patients who would benefit need to be better defined. To surmount these obstacles, the solution will be identified only by focused research, both in the laboratory and in the clinic.

342 citations


"Percutaneous posterolateral approac..." refers background in this paper

  • ...ments have been discussed, including gene, growth factor, or cell therapies [2, 3]....

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Journal ArticleDOI
TL;DR: The purpose of this study was to investigate the characteristic anatomical dimensions of the sheep spine and to compare these with existing human data.
Abstract: Background The sheep spine is often used as a model for the human spine, although the degree to which these spines are anatomically comparable has yet to be categorically established. The purpose of this study was to investigate the characteristic anatomical dimensions of the sheep spine and to compare these with existing human data. Methods Five complete spines were measured to determine 21 dimensions from the pedicles, spinal canal, transverse and spinous processes, facets, endplates, and disc. Results The results showed that sheep and human vertebrae are most similar in the thoracic and lumbar regions, although they show substantial differences in certain dimensions. Morphological variations as a function of spine level typically were well matched in the two species. Conclusions Sheep spine may be a useful model for experiments related to the gross structure of the thoracic or lumbar spine, with certain limitations for the cervical spine. A thorough database has been provided for deciding the appropriateness of using the sheep spine as a model for the human spine. Anat. Rec. 247:542–555, 1997. © 1997 Wiley-Liss, Inc.

332 citations


"Percutaneous posterolateral approac..." refers background in this paper

  • ...The ovine model stands out for evaluating degradation and regeneration of the spine [4, 5], with a proven comparability to human intervertebral disc anatomy [6], intradiscal pressure [4], biomechanical stress [5], and cell physiology [7]....

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  • ...2 cm3 range for typical human disc sequesters [24, 29], though ovine intervertebral discs are smaller than those of humans [5, 6]....

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Frequently Asked Questions (2)
Q1. What are the contributions mentioned in the paper "Difference in voice problems and noise reports between teachers of public and private schools in upper egypt" ?

In this paper, the authors studied the effects of culture and economic situation on the voices of teachers in Egypt 's public and private schools. 

It would be beneficial to extend the study to include other regions of Egypt.