Showing papers by "Sunnybrook Health Sciences Centre published in 1999"

Pulse inversion Doppler: a new method for detecting nonlinear echoes from microbubble contrast agents

Abstract: A novel technique for the selective detection of ultrasound contrast agents, called pulse inversion Doppler, has been developed. In this technique, a conventional Doppler or color Doppler pulse sequence is modified by inverting every second transmit pulse. Either conventional or harmonic Doppler processing is then performed on the received echoes. In the resulting Doppler spectra, Doppler shifts from linear and nonlinear scattering are separated into two distinct regions that can be analyzed separately or combined to estimate the ratio of nonlinear to linear scattering from a region of tissue. The maximum Doppler shift that can be detected is 1/2 the normal Nyquist limit. This has the advantage over conventional harmonic Doppler that it can function over the entire bandwidth of the echo signal, thus achieving superior spatial resolution in the Doppler image. In vitro measurements comparing flowing agent and cellulose particles suggest that pulse inversion Doppler can provide 3 to 10 dB more agent to tissue contrast than harmonic imaging with similar pulses. Similar measurements suggest that broadband pulse inversion Doppler can provide up to 16 dB more contrast than broadband conventional Doppler. Nonlinear propagation effects limit the maximum contrast obtainable with both harmonic and pulse inversion Doppler techniques.

The Prognostic Significance of Altered Cyclin-Dependent Kinase Inhibitors in Human Cancer

Abstract: Progression through the cell cycle is governed by cyclin-dependent kinases (cdks), whose activity is inhibited by the cdk inhibitors. Cyclins, cdks, and cdk inhibitors are frequently deregulated in cancers. This chapter reviews the prognostic significance of alterations in cdk inhibitors. Loss of p27 protein provides independent prognostic information in breast, prostate, colon, and gastric carcinomas, and immunohistochemical (IHC) staining for p27 may eventually become part of routine histopathologic processing of cancers. Loss of IHC staining for p21 may be prognostic in certain cancers but conflicting results are reported in breast cancer. Reports on homozygous deletion of p16 and p15 genes suggest the value of larger, prospective studies with standardized treatment protocols to definitively establish the prognostic utility of p15/p16 deletions in acute leukemias. Larger trials and the development of a consensus on methods for deletion analysis, IHC staining, and tumor scoring will be needed to move these molecular assays from bench to bedside.

Glypican-3-deficient mice exhibit developmental overgrowth and some of the abnormalities typical of Simpson-Golabi-Behmel syndrome

Abstract: Glypicans are a family of heparan sulfate proteoglycans that are linked to the cell surface through a glycosyl-phosphatidylinositol anchor. One member of this family, glypican-3 ( Gpc3) , is mutated in patients with the Simpson-Golabi-Behmel syndrome (SGBS). These patients display pre- and postnatal over- growth, and a varying range of dysmorphisms. The clin- ical features of SGBS are very similar to the more ex- tensively studied Beckwith-Wiedemann syndrome (BWS). Since BWS has been associated with biallelic expression of insulin-like growth factor II (IGF-II), it has been proposed that GPC3 is a negative regulator of IGF-II. However, there is still no biochemical evidence indicating that GPC3 plays such a role. Here, we report that GPC3-deficient mice exhibit several of the clinical features observed in SGBS pa- tients, including developmental overgrowth, perinatal death, cystic and dyplastic kidneys, and abnormal lung development. A proportion of the mutant mice also dis- play mandibular hypoplasia and an imperforate vagina. In the particular case of the kidney, we demonstrate that there is an early and persistent developmental ab- normality of the ureteric bud/collecting system due to increased proliferation of cells in this tissue element. The degree of developmental overgrowth of the GPC3-deficient mice is similar to that of mice deficient in IGF receptor type 2 (IGF2R), a well characterized negative regulator of IGF-II. Unlike the IGF2R-defi- cient mice, however, the levels of IGF-II in GPC3 knockouts are similar to those of the normal litter- mates.

Signaling through beta-catenin and Lef/Tcf.

Abstract: Beta-catenin plays a structural role in cell adhesion by binding to cadherins at the intracellular surface of the plasma membrane and a signaling role in the cytoplasm as the penultimate downstream mediator of the wnt signaling pathway. The ultimate mediator of this pathway is a nuclear complex of beta-catenin acting as a coactivtor with lymphoid enhancer factor/T cell factor (Lef/Tcf) transcription factors to stimulate transcription of a variety of target genes. Signaling through beta-catenin is regulated by modulating its degradation and nuclear translocation. In the absence of an activating signal, phosphorylation of beta-catenin by glycogen synthase kinase 3 (GSK3) acting in conjunction with adenomatous polyposis coli and axin/conductin causes beta-catenin to interact with the beta-transducin repeat-containing protein which results in its ubiquitination and degradation. Signaling from the wnt pathway activates dishevelled which, in an as yet undefined manner, inhibits the activity of GSK3 resulting in an increase in the cytoplasmic free pool of beta-catenin, and translocation into the nucleus. The integrin-linked kinase (ILK) pathway also activates beta-catenin-Lef/Tcf signaling. ILK phosphorylates GSK3 to inhibit its activity and translocates beta-catenin into the nucleus. In addition, ILK downregulates the expression of E-cadherin and upregulates Lef-1 expression. In the final step of the beta-catenin-Lef/Tcf signaling pathway, nuclear beta-catenin binds pontin52-TATA binding protein and displaces Groucho-related gene or CREB-binding protein corepressors from Lef/Tcf resulting in stimulation of transcription. During development, beta-catenin-Lef/Tcf signaling is involved in the formation of dorsal mesoderm and dorsal axis. Furthermore, defects in the beta-catenin-Lef/Tcf pathway are involved in the development of several types of cancers.

Utility scores for chronic conditions in a community-dwelling population.

Abstract: Objective: The objective of this study was to determine utility scores for various chronic conditions. Design and setting: This study is a descriptive analysis. Health Utilities Index (HUI) scores for 20 chronic conditions were examined from the National Population Health Survey (NPHS) from 1994 to 1995. Patients and participants: 17 626 individuals were surveyed (54.3% women). Chronic conditions included: acne (requiring medication), Alzheimer’s disease, arthritis/rheumatism, asthma, back problems excluding arthritis, chronic bronchitis or emphysema, cancer, cataracts, diabetes, epilepsy, food allergies, glaucoma, heart disease, high blood pressure, migraine headaches, other allergies, sinusitis, stroke, stomach/intestinal ulcers and urinary incontinence. Interventions: Health Utilities Index-Mark III (HUI-Mark III) scores for patients with and without a NPHS-defined chronic condition were collected. Utility scores were examined according to age, gender and comorbidity. Main outcome measures and results: 42.6% of individuals reported having no NPHS-defined chronic condition. The most commonly reported health conditions were allergies other than food (17.6%) and rheumatism/arthritis (16.5%). The mean HUI-Mark III scores for patients without a health state was 0.933 ± 0.079. Individuals with Alzheimer’s disease (0.580 ± 0.263), stroke (0.676 ± 0.230) and urinary incontinence (0.698 ± 0.230) had the lowest overall HUI-Mark III scores. Utility scores decreased as age and as the number of comorbid conditions increased. Conclusions: This study provides health economists, researchers and policymakers with a reference for health utilities of various chronic conditions, different age groups, gender and comorbidities.

The General Anesthetic Propofol Slows Deactivation and Desensitization of GABAA Receptors

Abstract: Propofol (2,6-di-isopropylphenol) has multiple actions on GABAA receptor function that act in concert to potentiate GABA-evoked currents. To understand how propofol influences inhibitory IPSCs, we examined the effects of propofol on responses to brief applications of saturating concentrations of GABA (1–30 mm). GABA was applied using a fast perfusion system to nucleated patches excised from hippocampal neurons. In this preparation, propofol (10 μm) had no detectable agonist effect but slowed the decay, increased the charge transfer (62%), and enhanced the peak amplitude (8%) of currents induced by brief pulses (3 msec) of GABA. Longer pulses (500 msec) of GABA induced responses that desensitized with fast (τf = 1.5–4.5 msec) and slow (τs = 1–3 sec) components and, after the removal of GABA, deactivated exponentially (τd = 151 msec). Propofol prolonged this deactivation (τd = 255 msec) and reduced the development of both fast and slow desensitization. Recovery from fast desensitization, assessed using pairs of brief pulses of GABA, paralleled the time course of deactivation, indicating that fast desensitization traps GABA on the receptor. With repetitive applications of pulses of GABA (0.33 Hz), the charge transfer per pulse declined exponentially (τ ≈ 15 sec) to a steady-state value equal to ∼40% of the initial response. Despite the increased charge transfer per pulse with propofol, the time course of the decline was unchanged. These experimental data were interpreted using computer simulations and a kinetic model that assumed fast and slow desensitization, as well as channel opening developed in parallel from a pre-open state. Our results suggest that propofol stabilizes the doubly liganded pre-open state without affecting the isomerization rate constants to and from the open state. Also, the rate constants for agonist dissociation and entry into the fast and slow desensitization states were reduced by propofol. The recovery rate constant from fast desensitization was slowed, whereas that from slow desensitization appeared to be unchanged. Taken together, the effects of propofol on GABAA receptors enhance channel opening, particularly under conditions that promote desensitization.

Role of cytokines in epidermal Langerhans cell migration.

Abstract: In the epidermal compartment of skin, keratinocytes (KC), Langerhans cells (LC), and their soluble products, i.e. cytokines, constitute a unique immunologic microenvironment. KC participate in cutaneous immune responses by producing various cytokines. LC, a member of the dendritic cell (DC) family, represent the professional antigen-presenting cells in the epidermis. Although it has been demonstrated that migration of LC from skin to lymph nodes is a critical step for the antigen presentation, molecular mechanisms for such an event remain unclear. Recent studies suggest that cytokines are able to modulate LC/DC migration. There is accumulating evidence that proinflammatory cytokines including interleukin (IL)-1 and tumor necrosis factor alpha promote LC emigration from the skin, whereas the anti-inflammatory cytokine IL-10 is a counter-regulator. LC/DC express chemokine receptors. Chemokines generated from lymphatic endothelial cells and lymph node cells play a role in the directional migration of LC/DC into lymph nodes. This article reviews current studies on the role of cytokines in LC/DC migration.

Circadian Variation in the Expression of Cell-Cycle Proteins in Human Oral Epithelium

Abstract: At the tissue level, there is experimental and clinical data to suggest a cytokinetic coordination of the cell cycle with a greater proportion of cycling cells entering S-phase and mitosis at specific times of the day. The association of certain cell-cycle proteins with defined events in the cell cycle is well established and may be used to study the timing of cell-cycle phases over 24 hours. In this study oral mucosal biopsies were obtained from six normal human volunteers at 4-hour intervals, six times over 24 hours. Using immunohistochemistry, the number of positive cells expressing the proteins p53, cyclin-E, cyclin-A, cyclin-B1, and Ki-67 was determined for each biopsy and expressed as the number of positive cells per mm of basement membrane. We found a statistically significant circadian variation in the nuclear expression of all of these proteins with the high point of expression for p53 at 10:56 hours, cyclin-E at 14:59 hours, cyclin-A at 16:09 hours, cyclin-B1 at 21:13 hours, and Ki-67 at 02:50 hours. The circadian variation in the nuclear expression of cyclins-E (G1/S phase), -A (G2-phase), and -B1 (M-phase) with a normal physiological progression over time suggests a statistically significant circadian variation in oral epithelial cell proliferation. The finding of a circadian variation in the nuclear expression of p53 protein corresponding to late G1 is novel. This information has clinical implications regarding the timing of chemotherapy and radiotherapy.

Handicap in stroke survivors.

Abstract: Background and purpose: As survival following stroke improves, individuals are more likely to live with the aftermath of stroke rather than immediately die from it The purpose of this study was to examine the consequences of stroke on the life activities of survivors in the social realm (stroke handicap) using the framework of the World Health Organization's International Classification of Impairments, Disabilities and Handicaps Methods: Multivariate analysis of variance was applied to cross-sectional data from a clinical study to investigate the correlates of handicap in a cohort of hemispheric stroke survivors at 3 months (n= 145) and at 1 year (n= 135) after stroke onset Handicap was assessed with the Reintegration to Normal Living Index, impairment by the Adams' Hemispheric Stroke Scale and Zung Depression Scale, and disability by the Functional Independence Measure Environmental variables in the model included marital status and receipt of rehabilitation therapy Results: Physical disability and

Normoxic and hypoxic regulation of vascular endothelial growth factor (VEGF) by astrocytoma cells is mediated by Ras.

Abstract: Vascular endothelial growth Factor (VEGF) has been identified as a key angiogenic factor involved in the growth and malignant progression of tumours. Glioblastoma multiforme (GBM) are the most common primary human brain tumours, histo-pathologically characterized by intense tumour angiogenesis. GBMs do not harbour oncogenic Ras mutations, but there is a functional up-regulation of Ras signaling through activation of receptor tyrosine kinases overexpressed by these tumours. We demonstrate that Ras pathway activation regulates VEGF secretion in astrocytoma cell lines. Ras pathway inhibition was carried out using genetic and pharmacologic techniques. Astrocytoma cells that were transfected to express the dominant inhibitory mutant H-Ras(N17) demonstrated a reduction in VEGF secretion under both normoxic and hypoxic conditions. Cells treated with the farnesyl transferase inhibitor L-744,832 demonstrated similar reductions in VEGF secretion. Furthermore, astrocytoma cells expressing a constitutively phosphorylated and truncated EGF-R common in GBMs (EGFRvIII or p140(EGF-R)) demonstrate further elevations in Ras activation, resulting in a further increase in VEGF secretion. We have previously demonstrated that activation of Ras plays a vital role in transducing mitogenic signals in human malignant astrocytoma cells. Our present results further extend the role of Ras activation in modulating tumour angiogenesis in these tumours. We propose that Ras may contribute to the angiogenic switch in astrocytomas.

Cell adhesion and proliferation mediated through the G1 domain of versican

Abstract: We have demonstrated previously that versican stimulated cell proliferation through the G3 domain. In these experiments, we show that versican mini-gene-transfected cell lines exhibited decreased cell-substratum interaction and increased cell proliferation. Exogenous addition of growth medium containing the versican gene product produced the same results. Because the G1 domain of versican is structurally similar to the G1 domain of aggrecan and to link protein, both of which play role in cell adhesion, we hypothesized that versican's proliferative effects may be a consequence of its ability to reduce cell adhesion, and may be mediated through the G1 domain. To investigate this, we expressed a G1 construct in NIH3T3 cells and showed that it reduced cell adhesion and enhanced cell proliferation. We then demonstrated that deletion of the G1 domain from versican greatly, but not completely, reversed the effects of versican: G1-deletion mutants of versican show slightly reduced amounts of cell adhesion and slightly increased rates of proliferation. We concluded that versican can stimulate cell proliferation via two mechanisms: through two EGF-like motifs in the G3 domain which play a role in stimulating cell growth, and through the G1 domain, which destabilizes cell adhesion and facilitates cell growth. We purified the G1 product with an affinity column and demonstrated that it reduced cell adhesion and enhanced cell proliferation.

Pathological laughing and crying in multiple sclerosis: a preliminary report suggesting a role for the prefrontal cortex.

Abstract: As part of a wide ranging study investigating the prevalence, demographic and disease related characteristics of pathological laughing and crying (PLC) in multiple sclerosis (MS), a putative role for the prefrontal cortex was also explored. Eleven multiple sclerosis (MS) patients with carefully defined PLC were compared to a control group of 13 MS patients without PLC on various cognitive indices known to be sensitive to frontal lobe dysfunction. Although the two groups did not differ with respect to age, sex, physical disability, disease course, duration of MS, years of education, premorbid IQ, and depression, the PLC group performed more poorly on the Stroop test and a measure of verbal fluency. They also showed a trend to make more total errors on the Wisconsin Card Sort Test. The relevance of these findings to the pathogenesis of PLC is discussed, in particular whether the syndrome is, in part, mediated by dysfunction of the prefrontal cortex.

Bilateral Dentigerous Cysts — Report of an Unusual Case and Review of the Literature

Abstract: Dentigerous cysts are the most common developmental cysts of the jaws, most frequently associated with impacted mandibular third molar teeth. Bilateral dentigerous cysts are rare and occur typically in association with a developmental syndrome. The reported occurrence of bilateral dentigerous cysts in the absence of a syndrome is rare and, to date, only 11 cases have been described. Here, we report a case of bilateral nonsyndromic, dentigerous cysts and review the literature for this unusual finding.

Heat-source orientation and geometry dependence in proton-resonance frequency shift magnetic resonance thermometry

Abstract: The proton-resonance frequency (PRF) shift method of thermometry has become a promising tool for magnetic resonance image-guided thermal therapies. Although the PRF thermal coefficient has recently been shown to be independent of tissue type when measured ex vivo, significant discrepancy remains on its value for tissues measured in vivo under a variety of experimental conditions. The authors identify a potential source of variation in the PRF thermal coefficient that arises from temperature-induced changes in the volume magnetic susceptibility of tissue and is dependent on the orientation and geometry of the heat-delivery device and its associated heat pattern. This study demonstrates that spatial variations in the apparent PRF thermal coefficient could lead to errors of up to +/-30% in the magnetic resonance estimated temperature change if this effect is ignored.

Characteristics of Dependent and Nondependent Regular Users of Codeine

Abstract: Although codeine is a widely used medication, the problems of codeine abuse and dependence have not been well-studied. This study characterized regular codeine users (using at least 3 days per week for 6 months, excluding those using codeine for the treatment of cancer pain) through a self-completed questionnaire. Recruitment through newspaper advertisements resulted in a total of 339 eligible questionnaires. Thirty-seven percent of subjects met DSM-IV criteria for codeine dependence. Dependent subjects (mean age, 40 +/- 10 years) were using an average of 179 (+/-171) mg of codeine per day. Codeine was predominantly used in the form of combination products with acetaminophen. Dependent subjects identified specific problems causally related to their codeine use such as depression (23%), anxiety (21%), and gastrointestinal disturbances (13%). The dependent subjects reported problems with other drugs more than did nondependent users (alcohol, 57% vs. 26%; cannabis, 23% vs. 5%; sedative/hypnotics, 33% vs. 12%; and heroin, 11% vs. 2%, respectively). Most were taking codeine primarily for a chronic pain problem (81%), although the dependent subjects currently found codeine less effective for treating pain than did the nondependent subjects and were more likely to use codeine for pleasurable effects, to relax, or to prevent withdrawal symptoms. This study showed that dependence is associated with the regular use of codeine. Pain is a key issue with these users; however, they are probably not receiving optimal treatment. There is a need to identify individuals experiencing problems with their codeine use and to develop optimal prevention and treatment strategies.

Versican Enhances Locomotion of Astrocytoma Cells and Reduces Cell Adhesion through Its G1 Domain

Abstract: Versican is a large extracellular proteoglycan and is expressed in a variety of tissues including the central nervous system. A malignant astrocytoma cell line U87 with high motility expressed a higher level of versican than another malignant astrocytoma cell line U343 with lower motility. We observed that the U87 cells were less adherent to tissue culture plates than the U343 cells. To investigate the role of versican in astrocytoma cell migration, we generated recombinant products of a mini-versican construct expressed in COS-7 cells. We found that the mini-versican products enhanced astrocytoma cell migration. Furthermore, enhanced migration was promoted by the G1 domain but not the G3 domain of versican. We introduced culture medium containing products of the mini-versican, the G1, and the G3 constructs separately into the astrocytoma cell lines U87 and U343. The mini-versican and the G1 construct, but not the G3 construct, were shown to reduce astrocytoma cell adhesion. The present data suggest that versican exerts its effect on astrocytoma cell migration and adhesion through the G1 domain.

Ventral frontal contribution to self-regulation: Convergence of episodic memory and inhibition

Abstract: Ventral frontal brain damage is associated with impaired self-regulation of behaviour in unstructured situations (self-regulatory disorder; SRD). This report attempts to integrate this brain-behaviour correlation with earlier animal literature on disinhibition and recent cognitive neuroscience literature on the frontal lobes and episodic memory. Data are presented from patient ML (Levine etal., Brain 1998; 121: 1951-73), who has isolated retrograde amnesia, ventral frontal dysfunction and SRD. Impaired strategic self-regulation of behaviour was documented with psychosocial outcome questionnaires and two laboratory analogues of real-life unstructured situations: a strategy application task and a gambling task. Previous findings of deficits in anterograde episodic memory (i.e. re-experiencing) using the remember/ know distinction were replicated and extended. The role of disinhibition as a mechanism for SRD was supported by MCs severely impaired performance on object alternation, a task with docume...

TNF Receptor p55 Plays a Pivotal Role in Murine Keratinocyte Apoptosis Induced by Ultraviolet B Irradiation

Abstract: Excess exposure of skin to ultraviolet B (UVB) results in the appearance of so-called sunburn cells. Although it has been demonstrated that sunburn cells represent apoptotic keratinocytes, the molecular mechanisms for UVB-induced apoptosis in keratinocytes have not been fully elucidated. The cytokine, TNF-alpha, has been shown to induce apoptosis in a variety of cell types. Since UVB induces keratinocytes to release TNF-alpha, we hypothesized that TNF-alpha is involved in UVB-induced apoptosis in keratinocytes. In order to confirm this hypothesis and to further delineate which type of TNF receptor signaling mediates the apoptosis pathway, we performed both in vivo and in vitro experiments using gene-targeted knockout mice lacking either the TNF p55 receptor or the TNF p75 receptor. In the in vivo study, wild-type and mutant mice were exposed to UVB, and apoptotic keratinocytes were detected by examining DNA fragmentation using in situ nick-end labeling. For the in vitro experiments, keratinocytes derived from the wild-type and mutant mice were irradiated with UVB, and the degree of apoptosis was determined by flow cytometry, nick-end labeling of DNA, and a DNA ladder assay. Both in vivo and in vitro studies demonstrated that the deletion of TNF receptor p55 could suppress UVB-induced apoptosis in keratinocytes. Our observations support the notion that TNF-alpha is involved in UVB-induced keratinocyte apoptosis, and demonstrate that p55 receptor signaling plays a pivotal role in this event.

Facial asymmetry: three-dimensional analysis using laser surface scanning.

Abstract: This study evaluates six different techniques with respect to their ability to quantitatively describe facial asymmetry in three dimensions. Three-dimensional facial images were acquired using a Cyberware 3030RGB laser surface scanner. Image processing was performed on a Silicon Graphics Indigo computer workstation. The following techniques for facial asymmetry analysis were developed: asymmetry in the location of anthropometric landmarks, Euclidean distance matrix analysis (EDMA), scalar measurement of the lower ciliary margin and palpebral fissure area, clearance vector mapping, and determination of the volume of asymmetry. Techniques were applied and validated in three anthropometric models: a perfectly symmetrical plastic head model and a plaster head model with and without a unilateral cheek augmentation. In each of the anthropometric test models, each analytical technique was validated by means of static anthropometric facial models and was evaluated for intraobserver and interobserver reliability. Asymmetries in the location of anthropometric landmarks can be accurately determined to within 2 mm in x, y, and z directions of the Cartesian space. EDMA is a useful technique in describing both size and shape changes of discrete areas of the face. Measurement of the lower ciliary margin and palpebral fissure area is reliable. Clearance vector mapping is especially useful in quantifying facial surface asymmetries in facial areas where anthropometric landmarks are scarce. Volume of asymmetry is potentially useful in those patients for whom the use of injections or implants of known volume may be helpful in correcting unilateral facial deficiencies.

The anesthetic record: accuracy and completeness.

Abstract: To evaluate if anesthesia training and experience influenced chart completion and accuracy. One hundred and twenty-four subjects, including medical students, anesthesia residents and community and university based clinical anesthesiologists, were given a standardized patient in a simulator environment and asked to conduct induction and maintenance of anaesthesia. Three critical events were introduced resulting in changes in BR HR, PETCO2 and SpO2. Subjects were instructed to manage the patient and the anesthetic chart, as was their customary practice. Discrepancy, calculated as the difference between the actual and charted values divided by the actual physiological value was compared by level of training with a two-way repeated measures analysis of variance (ANOVA) for all four physiological variables. The completeness of charting, defined as at least one data point recorded for each of the four physiological variables of the three critical events, was compared across level of training, age of participants and number of years in practice. The overall completeness of charting remained low (< 37%) with no relationship based on the anesthesiologist’s age, level of training or number of years in practice. There was discrepancy in charting for all physiological variables (HR, BR PETCO2 and SpO2, P < 0.0001), with a marked difference in the degree of discrepancy within each level of training. Training resulted in no differences in charting discrepancy. Charting of data to the anesthetic record remained incomplete and inaccurate in all groups based on level of training, age and number of years in practice.

Characteristics of injuries to the cervical spine and spinal cord in polytrauma patient population : experience from a regional trauma unit

Abstract: Study design: Retrospective analysis of a prospectively collected trauma database of a Level 1 (tertiary) trauma center. Objective: To define the features of the cervical spinal injuries in polytrauma population admitted to the regional trauma unit. Setting: Canada, Ontario Province, Toronto, Sunnybrook Health Sciences Center. Methods: All trauma admissions between 1987 and 1996 entered prospectively into a trauma registry database were studied for incidence, demographic and epidemiological details of cervical spine (cord and column) injuries. Results: A total of 468 patients (66% male) with cervical spinal injury (CSI) from 1198 spinal injuries admitted to the regional trauma center were identified. Seventy-five per cent of the CSI involved were aged less than 50 years; nearly 30% were in the third decade alone. Overall, the commonest spinal level injured was C2 (27%) followed by C5 (22%). Older population (above 60 years of age) had C1+2 involved more often than the young (P=0.02). Motor vehicular crashes (MVC) accounted for 71%, followed by pedestrian trauma (10%), sport injuries (7%). Spinal cord injury (SCI) was noted in 27%; complete in 16% and incomplete in 11% and more frequently at C4 or C5 level compared with C1, C2 (P<0.00001); the former level had more often a complete SCI (P=0.06). Though MVC produced 74% of SCI, only 27% had neurological deficits. Recreational trauma produced SCI in 45%, motor cycle crashes (MCC) in 37% and a rear passenger in MVC in 34% that was complete in 78%, 71% and 73% respectively. Front seat passenger and driver in MVC had a C5 level injury while a rear seat passenger had at C4 (P<0.001). The C1 level injury had high association with severe and life threatening head and neck and facial injuries compared with the more frequently injured spinal levels; either C2 (P=0.03) or C5 (P=0.004). Similarly C1 injuries had higher ISS compared with C2 (P<0.0001) and C5 (P<0.008). Conclusions: C2 was the commonest fractured spine while SCI was more frequent at C5. Older and pedestrian population had higher incidences of injuries at C1 and C2. Sport and MCC resulted in severe SCI. The level of spine injured was different between a front and a rear seat occupant in MVC.

Interleukin-6 dependent induction of the cyclin dependent kinase inhibitor p21WAF1/CIP1 is lost during progression of human malignant melanoma.

Abstract: Human melanoma cell lines derived from early stage primary tumors are particularly sensitive to growth arrest induced by interleukin-6 (IL-6). This response is lost in cell lines derived from advanced lesions, a phenomenon which may contribute to tumor aggressiveness. We sought to determine whether resistance to growth inhibition by IL-6 can be explained by oncogenic alterations in cell cycle regulators or relevant components of intracellular signaling. Our results show that IL-6 treatment of early stage melanoma cell lines caused G1 arrest, which could not be explained by changes in levels of G1 cyclins (D1, E), cdks (cdk4, cdk2) or by loss of cyclin/cdk complex formation. Instead, IL-6 caused a marked induction of the cdk inhibitor p21WAF1/CIP1 in three different IL-6 sensitive cell lines, two of which also showed a marked accumulation of the cdk inhibitor p27Kip1. In contrast, IL-6 failed to induce p21WAF1/CIP1 transcript and did not increase p21WAF1/CIP1 or p27kip1 proteins in any of the resistant lines. In fact, of five IL-6 resistant cell lines, only two expressed detectable levels of p21WAF1/CIP1 mRNA and protein, while in three other lines, p21WAF1/CIP1 was undetectable. IL-6 dependent upregulation of p21WAF1/CIP1 was associated with binding of both STAT3 and STAT1 to the p21WAF1/CIP1 promoter. Surprisingly, however, IL-6 stimulated STAT binding to this promoter in both sensitive and resistant cell lines (with one exception), suggesting that gross deregulation of this event is not the unifying cause of the defect in p21WAF1/CIP1 induction in IL-6 resistant cells. In somatic cell hybrids of IL-6 sensitive and resistant cell lines, the resistant phenotype was dominant and IL-6 failed to induce p21WAF1/CIP1. Thus, our results suggest that in early stage human melanoma cells, IL-6 induced growth inhibition involves induction of p21WAF1/CIP1 which is lost in the course of tumor progression presumably as a result of a dominant oncogenic event.