Showing papers by "University of Miami published in 1977"

Diverticular Disease of the Colon

Abstract: Summary Colonic diverticulosis refers to small outpouchings from the colonic lumen due to mucosal herniation through the colonic wall at sites of vascular perforation. Abnormal colonic motility and inadequate intake of dietary fibre have been implicated in its pathogenesis. This acquired abnormality is typically found in developed countries, and its prevalence rises with age. Most patients affected will remain entirely asymptomatic; however, 10–20% of those affected can manifest clinical syndromes, mainly diverticulitis and diverticular haemorrhage. As our elderly population grows, we can anticipate a concomitant rise in the number of patients with diverticular disease. Here, we review the incidence, pathophysiology, clinical presentation, and management of diverticular disease of the colon and its complications.

Movement of spermatocytes from the basal to the adluminal compartment of the rat testis

Abstract: The progressive movement of primary spermatocytes from the basal to the adluminal compartment of the seminiferous tubule was studied after testes were fixed with standard and hypertonic solutions. In stages VI, VII and VIII of the cycle (classification of Leblond and Clermont, '52), preleptotene spermatocytes were observed within the basal compartment of the seminiferous tubule. Resting on the basal lamina, these cells were bound tightly to neighboring Sertoli cells by desmosome-like junctions. In late stage VIII and early stage IX, basal processes of Sertoli cells were observed between the newly formed leptotene cells and the basal lamina, and in stage IX, the Sertoli processes met to form a junction of the zonula adherens type. This junction formed a permeability barrier which restricted the free access of fixative into the spaces around leptotene cells. Evidence for this was found in the absence of the shrinkage artifact produced with hypertonic solutions in earlier stages. In longitudinal sections, the permeability barrier was first observed in an area of the tubule in which sperm release was also taking place. In mid-stage IX and in stage X, sertoli-Sertoli junctional specializations formed de novo below the leptotene spermatocyte, while those from the preceding stages, present above the leptotene spermatocytes, remained intact. Thus, tight junctions were in evidence for a considerable period of the time, both above and below the leptotene spermatocytes. At no time in the process of germ cell movement toward the lumen did these cells exhibit evidence of amoeboid movement or lose desmosome-like contacts with the surrounding Sertoli cells. From this study it is concluded that the Sertoli cells play an active role in the transfer of spermatocytes to the adluminal compartment. A transient intermediate compartment of the seminiferous tubule is described, one which allows for the continual maintenance of the blood-testis barrier during transit of spermatocytes from the basal to the adluminal compartment.

Speed of sound in seawater at high pressures

Abstract: The speed of sound in standard seawater (diluted with pure water and evaporated) have been measured relative to pure water with a Nusonics single‐transducer sound velocimeter as a function of salinity (5–40°/00), temperature 0°–40°C, and applied pressure (0–1000 bars). The effect of pressure on the relative speeds of sound, (UP−UPH2O) ‐UO−UOH2O), have been fitted to an equation of the form (with a standard deviation of 0.19 msec−1) (UP−UPH2O) ‐ (UO−UOH2O) =AS (°/oo)+BS (°/oo)3/2 +CS (°/oo)2, where U and UH20 are the speeds of sound in seawater and pure water, respectively; superscripts P and O are used to denote applied pressure P and O (1 atm); A, B, and C are temperature‐ and pressure‐dependent parameters; S (o/oo) is the salinity in parts per thousand. This equation has been combined with the refitted high‐pressure pure‐water sound‐speed equation of Wilson [Naval Ordnance Lab. Rep.(1959)], Chen and Millero [J. Acoust. Soc. Am. 60, 1270–1273 (1976)], and the 1‐atm seawater sound‐speed data of Millero and Kubinski [J. Acoust. Soc. Am. 57, 312–319 (1975)] to calculate the speeds of sound for seawater at various salinities, temperatures, and pressures. Our results agree with the work of Wilson on the average to 0.36 msec−1 over the range of 5 to 40o/oo salinity, 0° to 30°C, and 0 to 1000 bars. Over the oceanic range our results agree on the average with the work of Wilson to 0.3 msec−1 (maximum deviation 0.6 msec−1), and with the work of Del Grosso to 0.5 msec−1 (maximum deviation 0.9 msec−1). The better agreement of our results with those of Wilson may be fortuitous since our measurements were made relative to his pure‐water data.

Size limit of molecules permeating the junctional membrane channels.

Abstract: The permeability of the cell-to-cell membrane channels in salivary gland cell junction (Chironomus thummi) was probed with fluorescent-labeled amino acids and synthetic or natural peptides. Molecules up to 1200 daltons pass through the channels with velocities depending on molecular size. Molecules of 1900 daltons or greater do not pass. This passage failure seems to reflect the normal size limit for junctional channel permeation; the channels continue to be permeated by the molecules up to 1200 daltons when these are mixed with the nonpermeant molecules. From this size limit a channel diameter of 10 to 14 angstroms is estimated.

Human pancreatic carcinoma (MIA PaCa-2) in continuous culture: sensitivity to asparaginase.

Abstract: An undifferentiated human pancreatic carcinoma has been established in continuous culture and is grown in Dulbecco's modified. Eagle's medium fortified with 10% fetal calf serum and 2.5% horse serum. The established cell line (MIA PaCa-2) has a doubling time of 40 h. The cells are large with abundant cytoplasm, exhibit a high degree of aneuploidy and have a tendency to grow on top of other cells. MIA PaCa-2 grows in soft agar with a colony-forming efficiency of 19%. Both MIA PaCa-2 cells and a cell line from another pancreatic carcinoma obtained from National Cancer Institute (NCI) are sensitive to asparaginase, a property not shared by several other human tumor cell lines tested.

Treatment of thrombotic thrombocytopenic purpura with plasma.

Abstract: Thrombotic thrombocytopenic purpura, the acute form of which is usually fatal, is characterized clinically by thrombocytopenia, microangiopathic hemolytic anemia, fluctuating neurologic signs and renal dysfunction, and pathologically by diffuse thrombotic occlusions in the microcirculation, in which platelets are consumed.1 2 3 4 Since the pathogenesis of this disease is not understood, treatment has been empirical or with an assumed rationale. Among the various modes of therapy tried, four are especially advocated: splenectomy and use of antiplatelet agents, of high doses of glucocorticoids, and of exchange transfusions. The value of splenectomy remains undefined.5 Proponents of antiplatelet treatment argue that whether or not platelet adhesion . . .

Observations on rat sertoli ectoplasmic (‘junctional’) specializations in their association with germ cells of the rat testis

Abstract: The ectoplasmic ('junctional') specialization, a subsurface modification of the Sertoli cell that is often seen facing germ cells, was studied in relation to the development and maturation of these germ cells. This structure is composed of subsurface bundles of filaments and more deeply placed endoplasmic reticulum. The data indicate that these subsurface modifications of Sertoli cells are reutilized in a cyclic fashion, being transferred from their position facing late spermatids to one opposing less mature germ cells. Ectoplasmic specializations appeared to function mechanically in grasping the heads of the spermatids which are undergoing the elongation and maturation phases of spermiogenesis rather than in actually attaching Sertoli cells to these germ cells. It is postulated that the ectoplasmic specialization imparts rigidity to that area of the Sertoli cell that surrounds the head region of the germ cell, forming a recess and a mantle by which the germ cell may be moved toward the base or toward the surface of the seminiferous epithelium. The observed linkage of microtubules to the cisternae of the complex provided a morphological basis for the changes in the cytoarchietecture of the Sertoli cell, which must accompany these movements.

Fracture healing in rat femora as affected by functional weight bearing

Abstract: Femoral fractures were created in rats to determine whether there were differences in healing under conditions of immobilization and under conditions of immediate weight-bearing. Histological and roentgenographic differences were present by the second week after fracture and differences in mechanical properties were also present. These differences became progressively greater during the next three weeks. Functional weight-bearing was found to accelerate the rate of fracture healing and to improve significantly the strength of the healing bone.

Ultrastructure of leydig cells as revealed by secondary tissue treatment with a ferrocyanide-osmium mixture.

Abstract: Leydig cells prepared routinely (glutaraldehyde-osmium) for ultrastructural studies are generally found to be lacking in subcellular detail as a result of poor membrane preservation and a dense cytoplasmic matrix. A method modified after that of Karnovsky (1971) , utilizing a ferrocyanide-osmium mixture for posttreating glutaraldehyde fixed tissues, was found to yield routinely excellent preservation of Leydig cells. The primary advantages of this method were the enhancement of contrast within the Leydig cell and greatly improved membrane preservation. In addition, the smooth endoplasmic reticulum always appeared as an extensive network of interconnected tubules of uniform diameter; mitochondria, lysosomes, peroxisomes, multivesicular bodies, and Golgi were especially prominent. Glycogen and microfilaments, not readily seen in routine preparations, were found to be abundant in these cells. New observations on the numbers and distributions of subcellular organelles are described and are discussed in relation to their possible role in the steroidogenic process. In view of the greatly improved tissue preservation observed in this study, it is suggested that this treatment be used routinely for preservation of rat Leydig cells.

Dust Concentration in the Atmosphere of the Equatorial North Atlantic: Possible Relationship to the Sahelian Drought

Abstract: The concentration of insoluble mineral aerosol in the lower troposphere of the western equatorial North Atlantic Ocean has increased by a factor of 3 over the last decade. This increase may be related to the drought in the Sahelian zone of North Africa.

Developmental Changes in Speech Discrimination in Infants

Abstract: A visually reinforced infant speech discrimination (VRISD) paradigm is described and evaluated. Infants at two ages were tested with the new paradigm on the following speech contrasts: [sa] vs [va], [sa] vs [∫a], [sa] vs [za], [as] vs [a:z], [a:s], vs [a:z], [at] vs [a:d], [a:t] vs [a:d], [at] vs [a:t], [fa] vs [θa], and [fi] vs [θi]. The data reported are compared with data on the same speech contrasts obtained from three month olds in a high-amplitude sucking paradigm. Evidence suggesting developmental changes in speech-sound discriminatory ability is reported. Results are interpreted in light of salience of available acoustic cues and in terms of new methodological advances.

The Ocular Motor Defects in Progressive Supranuclear Palsy

Abstract: The results of quantitative infrared horizontal eye movement recordings in 8 patients with progressive supranuclear palsy are presented Some of the patients had total paralysis of vertical movements, but none had completely lost the ability to perform horizontal eye movements All patients had a defect in ocular fixation previously undescribed in this condition: the universal presence of square-wave jerks Analysis of refixation saccades demonstrated hypometria, slow velocity/amplitude relationships, and profound prolongation of duration The pursuit abnormality, characterized clinically by "cogwheel" eye movements, represented the inability to match eye velocity to target velocity The ratio of peak eye velocity to peak target velocity (pursuit gain) was 02 to 05 Defects in the vestibuloocular reflex included inability to increase the gain of the reflex (ratio of peak eye velocity to head velocity) during viewing of a visible, stationary target and failure to suppress the reflex when viewing a target rotating with the head

Distribution of axonal transport blockade by acute intraocular pressure elevation in the primate optic nerve head.

Abstract: We studied the degree of axonal transport blockade in various areas of the optic nerve head with acute intraocular pressure (IOP) elevation in 19 squirrel monkey eyes. When IOP was raised to 20 to 50 mm. Hg for 7 hr., mild axonal transport blockade occurred in each area of the disk, most prominently in nerve fiber bundles of the superior pole. With 7 hr. IOP elevations between 50 and 90 mm. Hg, a somewhat greater degree of transport blockade occurred throughout the nerve head, although again the superior and inferior poles were somewhat more affected. The distribution of short-term transport blockade over the entire nerve head corresponds to the diffuse damage of acute glaucoma, but the pattern hints at the preference for damage near the poles of the disk seen in chronic glaucoma. However, before these results can be fully evaluated, further information is needed on axonal pathways through the optic nerve head and on the relationship between transport obstruction and ganglion cell death.

Desmosome-like junctions between Sertoli and germ cells in the rat testis.

Abstract: Desmosome-like junctions between Sertoli cells and germ cells (spermatogonia, spermatocytes and non-elongate spermatids) were observed in the adult rat testis. At all levels, certain features were characteristic of this relationship, the most prominent being a densification of the subsurface aspect of the plasma membranes of each cell. The Sertoli cell counterpart demonstrated an abundance of cytoplasmic fibrils which converged on the density, but no such feature was evident in the germ cell counterpart. The width of the intercellular space was variable, ranging in some regions from approximately 3–5 nm, to other regions of approximately 14–18 nm, the latter being representative of most areas of contact. A poorly represented, and often discontinous, intermediate dense line was observed in the intercellular space. Hypertonic fixative solutions containing dextrose were utilized to provoke tissue shrinkage and exaggeration of the intercellular space within the basal compartment of the testis. Cell separation was evident over most regions of the cells, except where desmosome-like contacts were present. Forces transmitted from one cell to another at desmosome-like contacts resulted in tearing of cellular fragments, while junctional regions of both cells remained intact. These observations indicate that desmosome-like junctions are strong adhesive sites between germ cells and Sertoli cells.

Calcium ion produces graded changes in permeability of membrane channels in cell junction

Abstract: THE permeability of the membrane channels in Chironomus salivary gland cell junction depends on the cytoplasmic Ca2+ concentration ([Ca2+]i) (refs 1, 2). At the normal [Ca2+]i, < 10−7 M, the channels are highly permeable to a wide range of molecular sizes; the upper size limit for peptide molecules is about 1,200–1,900 molecular weight (MW) (refs 3,4). When the [Ca2+]i is elevated above 5×10−5 M in the junctional locale, the permeability falls drastically for all molecular species including the small inorganic ions2,5,6. With elevations ranging up to about 5×10−5 M the channel permeability is reduced for the 330-MW fluorescein molecule with little or no detectable reduction of electrical coupling7. This suggested the interesting possibility that in this range the permeability change may be selective, that is, the permeability may fall for the larger molecular species but not for the small inorganic molecules carrying the electrical current. An alternative—that a fraction of the junctional channels closed unselectively (that is, completely)—could not be excluded, however, because the sensitivities of the methods for discriminating changes in the junctional permeabilities of the large and small molecular species were not equivalent; the measurements of electrical coupling, while quite sensitive to changes in junctional permeability in the low range of electrical coupling, are relatively insensitive at high levels of coupling7. Here we investigate this point by testing junctional permeability with fluorescent molecules of various sizes. In each test we use a pair of molecular species and compare their transit times during simultaneous diffusion in the same direction across the junction. If and only if the non-selective mechanism governs the Ca2+-mediated permeability reduction, the transit for both species should be equally retarded, irrespective of size or structural differences between the probe molecules. We show that, at low [Ca2+]i elevation, the junctional permeability reduction is indeed selective and that the molecular size limit for junctional channel permeation changes in a graded manner.

The equation of state of pure water determined from sound speeds

Abstract: The equation of state of water valid over the range 0–100 °C and 0–1000 bar has been determined from the high pressure sound velocities of Wilson, which were reanalyzed by Chen and Millero. The equation of state has a maximum error of ±0.01 bar−1 in isothermal compressibility and is in the form of a secant bulk modulus: K=V0P/(V0−V) =K0+AP+BP2, where K, K0, and V, V0 are the secant bulk moduli and specific volumes at applied pressures P and 0 (1 atm), respectively; A and B are temperature dependent parameters. The good agreement (to within 20×10−6 cm3 g−1) of specific volumes calculated using the above equation with those obtained from other modifications of the Wilson sound velocity data demonstrates the reliability of the sound velocity method for determining equations of state.

Mechanisms of spontaneous alternation between reciprocating tachycardia and atrial flutter-fibrillation in the Wolff-Parkinson-White syndrome.

Abstract: In a group of 36 consecutive patients with the Wolff- Parkinson-White (WPW) syndrome undergoing electrophysiological studies because of paroxysms of reciprocating tachycardia (RT) and/or atrial flutter-fibrillation (AF), 7 patients (19%) had repeated episodes of spontaneous alternation between RT and AF. Electrophysiological studies demonstrated left-sided anomalous pathways (AP) in all 7 patients. Atrial vulnerability, as evidenced by the occurrence of repetitive atrial responses or a paroxysm of AF following a single atrial premature stimulus, was also noted in all. Invariably, spontaneous conversion of RT to AF (7 patients) was triggered by an atrial premature depolarization which resulted in atrial asynchrony during the atrial vulnerable phase. In contrast, spontaneous conversion of AF to RT (3 of the 7 patients) required the presence or the development of antegrade unidirectional block in the AP prior to the cessation of AF. The demonstration of atrial vulnerability in association with the phenomenon of spontaneous alternation between RT and AF provides further information pertaining to the understanding of the mechanisms of tachyarrhythmias in the WPW syndrome. It is suggested that the occurrence of this electrophysiological phenomenon may be more common than is generally appreciated, and optimal medical treatment should be directed toward controlling both RT and AF in this group of Wolff-Parkinson- White patients.

Relative sound velocities of sea salts at 25°C

Abstract: The relative sound velocities (u−u0) of aqueous HCL, LiCL, NaF, NaCL, NaBr, NaI, NaNO3, NaOH, NaHCO3, Na2SO4, KF, KCL, KBr, KI, KNO3, K2CO3, K2SO4, RbCl, CsCl, NH4Cl, NH4Br, MgCl2, CaCl2, SrCl2, BaCl2 and MgSO4 solutions were measured from 0.01 to 1.0 at 25°C. The sound velocities were fitted to a function of molality (maximum standard deviation 0.05 m sec−1) u=u0+Am+Bm(3/2)+Cm2, where u0 is the sound velocity in pure water, and A, B, and C are temperature dependent parameters. The adiabatic compressibilities βS were determined from the sound velocities and were used to calculate the adiabatic apparent molal compressibilities φK(S) of the salts. The φK and βS of seawater were estimated by using Young’s rule. The calculated values of φK and βS agree with those determined from the measurements on seawater solution to ±0.18×10−4cm3mol−1bar−1 and ±0.004×10−6bar−1. The sound speeds of seawater calculated from the values of βS estimated from Young’s rule agree on the average to ±0.02m sec−1 (maximum standard de...

Subtropical Droughts and Cross-Equatorial Energy Transports

Abstract: The spatial coherence of subtropical rainfall anomalies is documented by variance analysis. Major droughts repeatedly were felt at the same time around the globe along the arid margins of the tropical rainfall belt. The persistence of anomalies becomes apparent in precipitation time series which combine data from relatively large areas and in streamflow records. These can be used to demonstrate autocorrelations and unexpectedly long runs of wet or dry years. The latest drought episode culminated in 1972 not only in the Sahel and the Sudan, but also along the borders of the Indian desert and in Central America. It is shown to have been accompanied by relatively low temperatures in the southern subtropics and by abnormally high temperatures in the antarctic. The meridional temperature gradient and the meridional slope of the 500 mb surface were correspondingly reduced. It is suggested that this was associated with a reduced demand for energy (and zonal momentum) exports from the tropics and therefo...

A comparison of cyclophosphamide, adriamycin, 5‐fluorouracil (CAF) and cyclophosphamide, methotrexate, 5‐fluorouracil, vincristine, prednisone (CMFVP) in patients with metastatic breast cancer. A southeastern cancer study group project

Abstract: In an ongoing prospective randomized study, 113 evaluable patients have received either a three-drug combination that included cyclophosphamide, Adriamycin and 5-fluorouracil (CAF) or a five-drug combination including cyclophosphamide, methotrexate, 5-fluorouracil, vincristine and prednisone (CMFVP) given intermittently 1 week out of 4. Responses (64%), median duration of response (32 weeks), and median duration of disease control (32 weeks) achieved with CAF were superior to those achieved with CMFVP (37%, 22 weeks, 17 weeks, respectively). Morbidity secondary to CAF was significant, with nausea and vomiting, malaise, total alopecia, and granulocytopenia being the main features. Cancer 40:625–632, 1977.

Descending optic nerve degeneration in primates.

Abstract: We cut the optic nerve at the orbital apex in squirrel monkeys to study the descending degeneration of optic nerve axons and their ganglion cell bodies. We could not detect progressive disintegration of the axon from the site of injury back to the cell body. Instead, the entire length of individual axons seemed to degenerate simultaneously as early as 3 weeks and as late as 6 weeks after injury, as judged both by ultrastructural integrity and by continued slow axonal transport, a reflection of local physiologic function. We could not relate the time of degeneration to the distance of the injury from the cell body. Evidently there is a signal of injury to the cell body after axotomy, though the nature of the signal and the mechanism by which it leads to cell death are unknown.

The Three Faces of Evaluation What can be Expected to Work

Abstract: Evaluations of intervention programs have concentrated on the adequacy of research design and the specification of outcome, while tending to ignore the integrity of the programs being evaluated. This third face of evaluation, assessing program integrity, involves information as to the adequacy of the conceptualization of the treatment, the duration and intensity of the program, the quality and quantity of personnel, and the match of treatment, treater and treated. The study by Kassebaum, Ward, and Wilner (1971), which utilizes an exemplary research design and provides considerable information on program integrity, is analyzed in detail to demonstrate that the almost complete lack of program integrity rendered the drawing of conclusions about the efficacy of group counseling in the correctional setting impossible from the results reported in this research. Continued lack of attention to the question of program integrity can only lead to further, and generally unproductive, debate about "what works." It is ...

Estimates of cenozoic oceanic sedimentation rates.

Abstract: Estimation of average Cenozoic sedimentation rates for the Atlantic, Indian, and Pacific oceans indicates global synchronous fluctuations. Paleocene-early Eocene and late Eocene-early Miocene rates are only a fraction of middle Eocene and middle Miocene-Recent rates. These changes must reflect significantly different modes of continental weathering, which may be due to alternate states of atmospheric circulation marked by reduction of global precipitation.

Long-term electrophysiological abnormalities resulting from experimental myocardial infarction in cats.

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Visual prototype formation with discontinuous representation of dimensions of variability.

Abstract: The prototype-distance model (Posner, 1969) predicts that when a series of similar visual stimuli are experienced, a prototype is abstracted at the point in the multidimensional similarity structure which represents the greatest similarity to all stimuli, whether the elements of the prototype have actually been experienced or not. The attribute-frequency model (Neumann, 1974) predicts the prototype as a pattern composed of the most frequently experienced elements on each dimension of variability. In three experiments, it was determined that: (1) Under some conditions, a prototype is formed of unexperienced values, and, under other conditions, the best recognized stimuli are those incorporating the most frequent values; (2) the present form of the prototype-distance model cannot account for best recognized stimuli being other than the central tendency; and, (3) the attribute-frequency model can, in principle, account for either finding by incorporating additional assumptions about the specificity with which values on dimensions of variability are encoded.