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Biomedical subjects

J Shapiro

Publications and source records attributed to J Shapiro.

At least 181 records · Page 10Linked to original sources
PubMed1987

The effects of axotomy on bullfrog sympathetic neurones.

1. The effects of axotomy on the electrical properties of B cells in paravertebral sympathetic ganglia were studied using standard intracellular recording techniques. The effects were apparent after 1 week and persisted throughout the 47 days of study. 2. Action potential duration (spike width) and amplitude (spike height) were significantly increased in axotomized neurones. 3. The duration of the after-hyperpolarization which followed the action potential showed considerable scatter in control neurones (mean +/- S.E. of mean, 159.0 +/- 5.8 ms for 100 cells). Following axotomy, the duration was significantly reduced (50.9 +/- 2.3 ms for 97 cells). The amplitude of the after-hyperpolarization was also significantly smaller in axotomized neurones. 4. Changes in the characteristics of the action potential and the after-hyperpolarization in axotomized neurones were not due to alteration in resting membrane potential or input resistance which were unchanged after axotomy. Rheobase current was significantly increased. 5. There was neither a significant depression of the rate of rise or the amplitude of orthodromically evoked nicotinic e.p.s.p.s nor any obvious ultrastructural alteration following axotomy. 6. Despite the decrease in the duration of the after-hyperpolarization, the rate of discharge in response to constant current injection was little changed in axotomized neurones. 7. Although axotomy produces significant changes in several measurable electrophysiological parameters in bullfrog sympathetic ganglion cells, the present results imply that mature neurones are able to maintain relatively normal electrical activity despite injury.

Action Potentials↗
PubMed1987

Comparison of ventricular volumes in normal and post-myocardial infarction subjects.

In an effort to determine left ventricular volume changes between upright rest and exercise, 15 male late post-infarction patients (group A) and 13 normal matched volunteers (group B) were studied. Patients were at least 12 months post-cardiac event. Upright two-dimensional echocardiographic recordings were performed by the same cardiac sonographer using the apical four-chamber view at rest and immediately post-exercise after the subject reached 85% of measured maximal heart rate. Single-plane planimetry of the cross-sectional area was used for calculation of left ventricular volumes. Two subjects in each group failed to demonstrate adequate (i.e., measurable) echocardiograms and were excluded from the statistical analyses. Two-way analysis of variance for repeated measures was followed by the Newman-Kuels multiple comparison procedure to determine statistically significant differences between means (P less than 0.05). The results indicated no differences in any of the measured parameters at rest between the groups. Exercise values demonstrated a significant increase in end-diastolic volume, stroke volume, and ejection fraction with exercise only in group B. End-systolic volume did not change in either group. Cardiac output and heart rate increased in both groups. These data suggest that in the upright position, cardiac output increases in normal males due to an increase in heart rate and stroke volume (increases in end-diastolic volume) and by increases in heart rate alone in the post-infarction group.

Adult↗
PubMed1986

Axotomy affects calcium-sensitive potassium conductance in sympathetic neurones.

Following peripheral nerve section, the cell body and proximal axon undergo various physiological and morphological changes which may be associated with regrowth. We found that axotomy reduced the amplitude and duration of the afterhyperpolarization (AHP) of the action potential (AP) of bullfrog sympathetic neurones. In addition, the repolarization of the AP was slowed. The Ca2+-channel blocker, Cd2+ (200 microM) produced similar effects in normal cells by blocking the Ca2+-sensitive K+ conductances (gK, Ca) which contribute to the AHP and to AP repolarization. Although Ca2+-channel function was preserved after axotomy, Cd2+ did not affect axotomized neurones. This suggests that axotomy promotes a functional loss of gK, Ca which could reflect a regenerative response of the cell to injury.

Action Potentials↗
PubMed1986

Effect of an adolescent medicine rotation on medical students and pediatric residents.

This study evaluated the effects of an adolescent medicine rotation on the attitudes and skills in the care of adolescents of third-year pediatric residents and medical students. Competence, comfort, and prior training in four areas were assessed by a self-evaluation questionnaire. Ratings were made at the start of the year, prerotation, and post a four- to six-week rotation. Residents not taking the rotation were rated at the beginning and end of the year. In addition, pelvic-examination skills were assessed by the clinic nurse and by the patients during the first and last week of the rotation. There were no significant changes in those not taking the rotation. In those residents taking the rotation, there was no change from beginning of year to prerotation, but there were significant changes after the rotation. Only those residents taking the rotation indicated an increase in liking adolescents. Pelvic examination skills were rated significantly higher during the last week of the rotation by the nurse and patients. A one-year follow-up study continued to show significantly higher scores in those residents taking the rotation. An adolescent medicine elective may significantly improve medical students' and residents' self-assessed levels of competence, comfort, and training in adolescent health care and pelvic examination skills.

Adolescent↗
PubMed1986

Human brain glial cells synthesize thrombospondin.

Thrombospondin, a 450-kDa multinodular glycoprotein with lectin-type activity, is found in human platelets, endothelial cells, fibroblasts, smooth muscle cells, monocytes, and granular pneumocytes. Thrombospondin interacts with heparin, fibrinogen, fibronectin, collagen, histidine-rich glycoprotein, and plasminogen. Recently, thrombospondin synthesis by smooth muscle cells has been reported to be augmented by platelet-derived growth factor. We present evidence that thrombospondin is present within and synthesized by astrocytic neuroglial cells. Heparin-Sepharose affinity chromatography of material derived from a human brain homogenate yielded a protein that, when reduced, had an apparent size of 180 kDa and comigrated with reduced platelet thrombospondin on NaDodSO4/PAGE. Immunoblot analysis with monospecific anti-thrombospondin confirmed the presence of immunoreactive thrombospondin. Indirect immunofluorescence of cultured human glial cells indicated the presence of thrombospondin. Metabolic labeling of glial cell cultures with [35S]methionine followed by immunoprecipitation with monospecific anti-thrombospondin revealed synthesis of a 180-kDa polypeptide that comigrated with platelet thrombospondin on NaDodSO4/PAGE. Cultured human glial cells were incubated for 48 hr in serum-free medium with purified platelet-derived growth factor at concentrations up to 50 ng/ml. Aliquots taken at intervals were analyzed by a quantitative double-antibody ELISA. The growth factor stimulated the release of thrombospondin into the culture medium by as much as 10-fold over control cultures. The presence of thrombospondin within glial cells of the central nervous system and the augmentation of its synthesis by platelet-derived growth factor suggest that thrombospondin may play an important role in regulating cell-cell and cell-matrix interactions during periods of cell division and growth.

Brain↗
PubMed1986

The effects of prostaglandin E1 on the adult respiratory distress syndrome in septic primates.

The effects of prostaglandin E1 (PGE1) on the adult respiratory distress syndrome were studied in the septic primate (Macaca fascicularis). A 30-min infusion of Escherichia coli (1 X 10(10)/kg) resulted in severe septic shock and adult respiratory distress syndrome. Primates, if living, were killed 4 h after completion of the E. coli infusion. Three groups of primates were studied (n = 4 in each group). The control group (Group 1) received PGE1 at 100 ng/kg/min throughout the experiment. The septic group (Group 2) received a 30-min infusion of E. coli. The treatment group (Group 3) received a continuous PGE1 infusion (100 ng/kg/min) along with the E. coli infusion which was begun 30 min after the PGE1 infusion was started. Control primates had hemodynamic changes consistent with the vasodilatory effect of PGE1 (heart rate and cardiac output increased; blood pressure and systemic vascular resistance (SVR) decreased). All control animals survived the experiment and had no evidence of pulmonary damage. Primates given E. coli developed severe hypotension, decreased SVR, and lung injury evidenced by pulmonary edema, decreased oxygenation, and increased extravascular lung water. Primates treated with both PGE1 and E. coli developed similar cardiovascular and pulmonary changes as the septic group. There was no statistically significant difference between Group 2 and Group 3 animals with regard to mean arterial blood pressure, SVR, extravascular lung water, alveolar-arterial oxygen difference, or survival.(ABSTRACT TRUNCATED AT 250 WORDS)

Alprostadil↗
PubMed1986

Accelerated bone formation causing profound hypocalcemia in acute leukemia.

A patient with acute monocytic leukemia and fibrosis presented with severe hypocalcemia producing tetany, myocardial failure, and ventricular tachycardia with torsades de pointes configuration. Hypophosphatemia, hypomagnesemia, an elevated alkaline phosphatase level, and osteosclerosis were also present. Bone marrow biopsy samples showed fibrosis and thickened bony trabeculae lined with large osteoblasts. Tetracycline labeling showed an increased rate of calcification. Complete remission of the leukemia and fibrosis was achieved with a single 3-week course of low-dose cytarabine and hydroxyurea, with resolution of the hypocalcemia and hypophosphatemia. Calcitriol and etidronate disodium were also administered. The calculated left ventricular ejection fraction increased from 15% to 55% with correction of the hypocalcemia. The hypocalcemia and hypophosphatemia in this patient probably resulted from accelerated bone formation stimulated by the leukemic cells. The high dose of calcitriol that this patient received may have contributed to the remission of the leukemia.

Aged↗
PubMed1986

General anesthesia during excision of a mouse tumor accelerates postsurgical growth of metastases by suppression of natural killer cell activity.

Our previous studies indicated that anesthetic drugs cause acceleration of postoperative metastasis of mouse tumors. We tested whether this augmentation could be attributed to a decrease in natural killer (NK) activity. The results indicated that two of the anesthetic drugs used during excision of the Lewis lung carcinoma (3LL) tumor, halothane and ketamine, decreased NK activity, whereas the other two, thiopental sodium and N2O, had no effect on NK activity in in vitro assays. The observed decrease in NK cell activity was reversed following treatment with polyinosinic-polycytidylic acid (poly I:C), which is an NK cell potentiator. Treatment of mice with poly I:C abolished the accelerated growth of metastases following excision of the tumor under ketamine or halothane anesthesia. On the other hand, treatment with poly I:C seemed to have no effect on acceleration of postoperative metastasis in mice anesthetized with N2O or thiopental sodium.

Anesthesia, General↗
PubMed1985

Vertebral bone mineral content in osteogenesis imperfecta.

Quantitative computed tomography of the lumbar spine was carried out in 28 patients with osteogenesis imperfecta (OI) in order to measure vertebral trabecular bone mineral concentration (BMC). The patients ranged in age from 6-73 years, and included 3 of the 4 major clinical subtypes of the disease. The findings underscore the heterogeneity of osteogenesis imperfecta even among family members with the same disease type. In addition, cross-sectional analysis of Type I OI patients suggests that BMC during young adulthood averages about 70% of normal, and subsequently falls more rapidly than in normal patients. BMC tends to be lower in the more severe forms of OI. Decreased BMC was not found in a few otherwise normal relatives with scoliosis or joint laxity.

Adolescent↗
PubMed1985

Maxillary ameloblastoma with orbital invasion. A clinicopathologic study.

A 72-year-old white man presented to Massachusetts Eye and Ear Infirmary with proptosis of the right eye. Computerized tomography (CT) scan revealed a mass which filled the right maxillary sinus and invaded the orbital and middle cranial cavities. Six years earlier, the patient had excision of an ameloblastoma of the right maxillary antrum. The tumor recurred, requiring maxillectomy, local radiotherapy and finally exenteration. Ameloblastoma is a relatively rare epithelial tumor arising from embryonal tooth elements. It is locally invasive and recurrent but rarely metastasizes and extension to the orbit is extremely unusual. The clinical features, histopathologic findings and treatment of this tumor are discussed. Differential diagnosis of jaw tumors, which may invade the orbit, is reviewed.

Aged↗