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Biomedical subjects

S W Thompson

Publications and source records attributed to S W Thompson.

At least 55 records · Page 3Linked to original sources
PubMed1988

The anesthetic contribution of magnesium sulfate and ritodrine hydrochloride in rats.

The anesthetic effects of the tocolytic agents, magnesium sulfate and ritodrine hydrochloride, were investigated by determining their effect on the minimal alveolar anesthetic concentration (MAC) of halothane in male and in pregnant and nonpregnant female rats. Magnesium and ritodrine were administered by continuous intravenous infusion to mechanically ventilated rats anesthetized with halothane. The tail-clamp technique was used to establish the MAC of halothane before and then again during the infusion of either magnesium or ritodrine. Ritodrine produced no change in halothane MAC. Increasing magnesium dosages and magnesium plasma levels were associated with nonlinear reductions in halothane MAC that were unrelated to sex or pregnancy. The alveolar halothane MAC concentration in pregnant rats (0.85 +/- 0.02) was not significantly different from the halothane MAC in nonpregnant female or male rats. At the highest plasma magnesium concentrations (15.8 +/- 1.57 mg/dl) achieved in the pregnant rats, the alveolar halothane MAC was 0.36 +/- 0.13, a 61.6% reduction in MAC. The anesthetic effects of magnesium were not attributable to cardiovascular, respiratory, or neuromuscular depression. Major decreases in blood pressure occurred only in the pregnant rats with the highest magnesium concentrations.

Anesthesia, Inhalation↗
PubMed1987

The postnatal development of the ventral root reflex in the rat; a comparative in vivo and in vitro study.

The ventral root reflex (VRR) and its postnatal development has been studied in vivo and in an isolated spinal cord preparation from birth up to 14 days. At postnatal days 0, 7 and 14 the VRR typically consists of an early highly synchronized peak (VRR1) and a later lower amplitude peak (VRR2). In some cases, especially at day 14 in vivo, there is a longer latency asynchronous wave (VRR3). As the age of the animal increases the latencies of the first two components VRR1 and VRR2 progressively decrease mainly due to the decrease in the central delay occurring over this period. Consideration of the central delays for VRR1 and VRR2 recorded in vivo and in vitro indicates that these waves are unlikely to be elicited by C-fibre activation and a long latency C-evoked reflex discharge equivalent to that of the adult could not be reliably recorded. Up to day 7 the appearance of the VRR was similar in both preparations but diverged in the second week of life.

Aging↗
PubMed1986

Reassembly of c-myc and relaxation of c-fos nucleosomes during differentiation of human leukemic (HL-60) cells.

Human promyelocytic leukemic (HL-60) cells have amplified c-myc protooncogene sequences which lead to an elevated level of c-myc gene expression. Induction of HL-60 cells by phorbol esters to undergo monocytic differentiation results in the suppression of c-myc, but the activation of c-fos gene transcription. Chromatin structures of c-myc and c-fos were compared by measuring their sequences in nucleosome-associated DNA fragments. These nucleosomal particles were released from chromatin by micrococcal nuclease digestion and subsequently analyzed with two dimensional gel electrophoresis. C-myc related sequences were detected in nucleosomal DNA fragments of differentiated cells only, while the c-fos related sequences were found in nucleosomal DNAs of noninduced HL-60 cells. Since the enzyme preferentially digests relaxed DNAs, these results suggest that nucleosomal subunits of c-myc and c-fos chromatin are relaxed during the state of active transcription, and reassembled once their transcription is repressed.

Cell Differentiation↗
PubMed1984

Cisplatin neuropathy. Clinical, electrophysiologic, morphologic, and toxicologic studies.

Ten of 11 patients with ovarian cancer receiving cisplatin developed a distal sensory neuropathy, manifested early by decreased vibratory sensibility in toes and depressed ankle jerks and later by uncomfortable paresthesias. Eleven patients receiving cisplatin, 50 mg/m2 monthly (mean total, 580 mg/m2) were studied prospectively with monthly neurologic examinations and conduction velocity determinations of median, peroneal, and sural nerves. Early signs were decreased vibratory sensibility in toes (mean dose, 417 +/- 132 mg/m2 [SD]) and loss of ankle jerks (mean dose, 455 +/- 86 mg/m2). With continued therapy, four developed paresthesias. Strength was unaffected. Sural nerve responses abruptly disappeared in six of peripheral nerves from four patients showed axonal degeneration and secondary myelin breakdown. Platinum concentrations in three patients were similar in tumor (3.3 micrograms/g), sural nerves (3.5 micrograms/g), and spinal ganglia (3.8 micrograms/g), but lower in brain (0.17 microgram/g). This may explain the cisplatin toxicity of peripheral nerves with relative sparing of the central nervous system.

Adult↗
PubMed1984

Effect of labor on the postpartum bladder.

Urodynamic investigations were performed on 20 patients at 48 hours and at four weeks after delivery to assess the effect of modern obstetric practice on the postpartum bladder. Although there were significant differences in some values over this period, the mean urodynamic measurements on both occasions were within normal limits. It is concluded that the current management of labor does not predispose women to bladder hypotonia, the chief factors responsible being avoidance of prolonged labor and early catheterization after delivery.

Adult↗
PubMed1976

Ballistic movements of the arm in systemic lupus erythematosis.

The case of a 24-year old woman with systemic lupus erythematosis and central nervous system disease manifested by ballistic movements of the left arm is presented. She also had bilateral cerebral infarcts with pseudobulbar palsy. Ballismus is not generally known to be a manifestation of systemic lupus although there have been been reports of chorea in this disease which has responded to treatment with corticosteroids. In the present case, the ballismus disappeared when very large doses of steroids were given. This suggests that massive doses of corticosteroids may be needed for effective treatment of central nervous system lupus.

Adult↗
PubMed1973

Inhibition by thyrocalcitonin of estrogen-induced bone resorption in the mouse pubic symphysis.

A specific local erosion of the medial edges of the pubic bones is induced by administration of estradiol cyclopentylpropionate (ECP) to thyroparathyroidectomized mice. This paper presents both histochemical and biochemical evidence that porcine thyrocalcitonin (TCT) inhibits this estrogen-mediated resorption of the pubic symphysis. A marked increase in osteoclasts with a resultant increase in demonstrable sites of acid phosphatase (AcP) activity was observed in serial sections of resorbing pubic symphyses from ECP-treated animals. Bioassay of excised pubic symphyses revealed a concomitant increase in AcP activity. When mice were treated with TCT in combination with ECP, a marked decrease in osteoclasts with a resultant decrease in demonstrable sites of AcP activity and inhibition of the resorption process occurred. The mouse pubic symphysis thus appears to offer a model for exploring cellular mechanisms by which TCT regulates bone metabolism.

Acid Phosphatase↗