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Biomedical subjects

J Fisher

Publications and source records attributed to J Fisher.

At least 487 records · Page 27Linked to original sources
PubMed1982

Preemption of Streptococcus mutans 10449S colonization by its mutant 805.

Oral infection of rats with Streptococcus mutans mutant 805 was used to prevent the establishment of its highly virulent wild-type progenitor NCTC 10449S. The dose of wild-type cells required to colonize 100% of the specific pathogen-free Osborne-Mendel rats (21 to 43 days old) consuming caries test diet 2000 was greater than 4 x 10(5) but less than 4 x 10(6) cells. Therefore, the latter dose was used to challenge rats which had already been colonized by an oral dose of about 6 x 10(8) cells of mutant 805. This prior infection by 805 either completely protected rats from subsequent colonization by wild-type cells or greatly delayed and diminished their emergence. Rats in which wild-type cells became established showed much lower percentages of wild-type cells in their total recoverable floras than did rats that were not first infected by the mutant. Large doses of mutant 805, however, did not displace wild-type cells from rats once it became established. There was no evidence of reversion of the mutant, which is defective in intracellular polysaccharide synthesis and hence is less virulent than wild-type cells. The data indicate that the S. mutans cell which first colonizes rats gains the strongest ecological position and is difficult to displace. Also, they suggest the possible prophylactic utility of infection by this mutant of S. mutans.

Animals↗
PubMed1982

Determinants and clinical significance of jugular venous valve competence.

We studied the function of right internal jugular vein valves during cardiac catheterization in 32 patients and external jugular vein valves in vitro from 13 dogs. Patients with normal central venous pressure had competent valves during cough-induced transvalvular pressure gradients of 52.4 +/- 8.6 mm Hg. Ten of 15 patients with elevated central venous pressure had either incompetent or absent internal jugular valves, the latter occurring only in patients with long-standing, severe tricuspid regurgitation. During coughing, competent valves were also demonstrated in the left internal jugular and in the right and left subclavian veins. The excised canine valves were competent at a static transvalvular pressure of 81.8 +/- 3.7 mm Hg. Five of six excised valves remained competent during pulsatile transvalvular pressure of 64.8 +/- 1.9 mm Hg. Thus, thoracic inlet venous valves are usually competent during sudden increases in intrathoracic pressure. These valves may play an important role in establishing the extrathoracic arteriovenous pressure gradient necessary for forward blood flow during cardiopulmonary resuscitation and other states with high intrathoracic pressure.

Adult↗
PubMed1982

Transmission electron microscope morphogram of progressive motile sperm cell fraction separated from teratozoospermic human semen.

Teratozoospermic semen specimens were separated, with the aid of a specially designed separation chamber, into an upper progressive motile sperm fraction and a lower fraction containing a high percentage of sperm cells of poor or no motility, and immature germinal cells. Analysis of the TEM morphograms of progressive motile cell fractions and original teratozoospermic semen revealed that 15 various malformations were improved significantly in the motile cell population due to the cell separation technique.

Cell Separation↗
PubMed1982

Dissociation of plasma and cerebrospinal fluid beta-endorphin-like immunoactivity levels during pregnancy and parturition.

The association between central (cerebrospinal fluid [CSF]) and peripheral (plasma) levels of beta-endorphin-like immunoactivity (beta-ELI) in nonpregnant women (n = 8) and pregnant women (a) at 16 to 20 weeks of gestation (n = 6), (b) at term (n = 21), and (c) in labor (n = 15) was investigated. Umbilical arterial (n = 11) and venous (n = 11) samples were also obtained. In agreement with previous investigations, it was found that plasma levels of beta-ELI increased during labor (mean +/- SEM: nonpregnant women, 63.5 +/- 18.2; pregnant women at term, 64.0 +/- 12.2; women in labor, 110.8 +/- 30.3 pg/ml), and that levels of umbilical arterial plasma of beta-ELI exceeded those in umbilical venous plasma (132.5 +/- 34.0 versus 68.2 +/- 22.2). However, CSF levels of beta ELI did not change over the course of pregnancy or during labor (nonpregnant women, 36.5 +/- 15.8; pregnant women at 16 to 20 weeks of gestation, 60.1 +/- 10.3; pregnant women at term, 57.5 +/- 8.4; women in labor 48.5 +/- 8.3 pg/ml). This evidence that plasma and CSF levels of beta-ELI are dissociated during labor calls into question inferences regarding behavioral changes during parturition based on plasma beta-ELI measurements.

Endorphins↗
PubMed1982

Metabolic requirements of schistosomes.

In adult Schistosoma mansoni and S. japonicum carbohydrate utilization, formation of lactic acid and ATP levels were the same under aerobic and anaerobic conditions. Therefore, these parasites exhibited no pasteur effect. When the metabolic requirements of the parasites were raised by 5-hydroxytryptamine-(5-HT)-induced stimulation of the worm's motor activity, aerobic conditions did not reduce the rate of carbohydrate utilization nor the ATP levels of the worms. Therefore, these parasites do not derive metabolic energy from respiration.

Adenosine Triphosphate↗
PubMed1982

Thyrotoxic periodic paralysis with ventricular fibrillation.

Electrocardiographic conduction disturbances and nonspecific interval changes are not uncommon during hypokalemic periodic paralysis. Although premature ventricular contractions may occur during the paretic episodes associated with hyperkalemic, normokalemic, and hypokalemic periodic paralysis, ventricular tachycardia is rare; to my knowledge, ventricular fibrillation has not been previously reported. In 1977 a 40-year-old man of Puerto Rican descent was resuscitated from ventricular fibrillation and subsequently received a diagnosis of thyrotoxic hypokalemic periodic paralysis. Following thyroid suppression the patient has been asymptomatic; ambulatory ECG monitor, maximal exercise stress test, and echocardiograms have been normal. This case documents the occurrence of ventricular fibrillation in thyrotoxic periodic paralysis.

Adult↗
PubMed1981

Inactivation of the RTEM beta-lactamase from Escherichia coli. Interaction of penam sulfones with enzyme.

The characteristics of the reaction of a number of mechanism-based inactivators of the RTEM beta-lactamase have suggested that a common mechanistic pathway may be followed by many of these compounds. These ideas have been tested by the synthesis and evaluation of some penam sulfones as beta-lactamase inactivators. The sulfones of poor beta-lactamase substrates are, as predicted, potent inactivators of the enzyme. A unique serin residue (Ser-70) is labeled by quinacillin sulfone, and it is likely that this serine acts nucleophilically in the normal hydrolytic reaction of the beta-lactamase to form an acyl-enzyme intermediate.

Amino Acids↗
PubMed1981

Severe hypertension in a child with ganglioneuroblastoma.

A 26-month-old boy with Stage III abdominal ganglioneuroblastoma had tachycardia and hypertension. The hypertension increased following the institution of chemotherapy and necessitated the use of both alpha and beta adrenergic blocking agents to control the effects of the marked catecholamine production. After excision of the residual tumor, the blood pressure and urinary catecholamine excretion returned to normal. Histologic examination of this tissue under light microscopy revealed some sections of ganglioneuroblastoma as well as large areas of ganglioneuroma. Examination by electron microscopy demonstrated a moderate number of dense core neurosecretory-type granules in the cell bodies of the ganglion-like cells and an abundance of the same type of granules in the bundles of the interwoven cytoplasmic neural processes. To data, 32 months after diagnosis and 20 months off chemotherapy, the patient remains free of tumor and is in excellent general health. We postulate that the large number of secretory granules in this tumor permitted storage and release of markedly increased quantities of norepinephrine and resulted in a clinical profile similar to that associated with pheochromocytoma.

Abdominal Neoplasms↗
PubMed1981

Reflux gastritis syndrome. Role of upper gastrointestinal microflora.

Bacteriologic samplings of the upper gastrointestinal tract bile acids profile of the intestinal contents were performed in eight patients with reflux gastritis syndrome and three asymptomatic patients who had had gastric surgery. All symptomatic patients showed colonization of the gastric and/or intestinal samples with strains of enteric Gram-negative bacteria and Pseudomonas. However, no single specific group or species was consistently associated with reflux gastritis syndrome. The concentration of total and conjugated bile acids was significantly greater in symptomatic patients. Presence of free bile acids was correlated with heavier bacterial colonization. To evaluate the effect of antibiotic therapy on bacterial flora and symptoms, patients were studied for three separate four-week evaluation periods. Following the first evaluation period, they were assigned to receive either doxycycline or placebo in a crossover fashion during the second and third periods. Total symptom scores did not differ significantly and no specific patterns were evident in the bacterial flora. These observations support the hypothesis that microbial flora is an associated factor in reflux gastritis syndrome and may play an important role only in certain individual patients.

Adult↗
PubMed1981

Hypoxemia following pulmonary embolism: a dog model of altering regional perfusion.

We studied the role played by a shift in perfusion to hypoxic lung areas after pulmonary embolism in pst embolic hypoxemia. A tracheal divider was used to separate hypoxic (N2 ventilated) from oxygenated (100 per cent O2 ventilated) lung in anaesthetized dogs. Relative perfusion was assessed from total 133Xenon (133Xe) exhaled from each lung area after intravenous infusions. When one lung area was ventilated with N2 and the other with O2 at a normal PaCO2 to allow hypoxic pulmonary vasoconstriction (HPV), there was a significant (P less than 0.001) shift away from the hypoxic side. Starch or blood clots were then infused to produce pulmonary emboli. Starch emboli were distributed predominantly to the oxygenated lung. After blood clot embolization in normocapnic dogs, pulmonary artery pressure increased 15 torr, perfusion to the hypoxic lung increased from 14 +/- 2 to 23 +/- 1 per cent, and PaCO2 fell from 278 to 186 torr. When the degree of HPV was reduced in another group of dogs by hypocapnea, a similar increase in pulmonary artery pressure (14 torr) created by blood clot embolism did not shift perfusion or create hypoxemia. In all dogs the perfusion shift to hypoxic lung was sufficient to account for all the post embolic hypoxemia. In this dog model, post embolic hypoxemia is explained by preferential distribution of emboli to oxygenated lung followed by perfusion shift to hypoxic lung as the effect of HPV is overcome by pulmonary hypertension.

Animals↗
PubMed1981

Calibration of a Floscope peak flow meter and a Vitalography pulmonary monitor.

The performance of a Floscope peak flow meter and the Vitalography pulmonary monitor are assessed using an absolute calibration method. Both instruments have good repeatability. For peak flows greater than 150 litres/minute, the Floscope showed errors of between - 12.4% and +7.1%. For flows below 150 litres/minute the percentage errors were greater. The pulmonary monitor showed errors of between - 20% and 5.5%. Its high resistance makes it an inappropriate instrument to use for absolute measurement of peak flows. It is useful for assessing trends.

Calibration↗
PubMed1981

Incorporation of [3H]thymidine into mtDNA of ram spermatozoa.

Freshly ejaculated spermatozoa from 6 rams incorporated [3H]-thymidine only after a lag period of 4 h. The thymidine incorporation was dependent on the time after ejaculation regardless of the rate of fructolysis, which was controlled by cold shock. The DNA synthesis period lasted for 3 h followed by a degradation period of 2 h. This synchronized level of labelling of DNA with tritiated thymidine was not due to bacterial contamination, sperm cell mitosis, mitochondrial division, or DNA repair. The fact that the maximal level of the DNA synthesis was dependent upon the external pH of the seminal plasma, in a parabolic fashion with a minimum around pH 6.3, indicated that this activity was of a 'metabolic' type. The sensitivity of the sperm DNA synthesis to 10 micrograms ethidium bromide/ml indicated that it was of a mitochondrial origin.

Animals↗