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Biomedical subjects

J Adler

Publications and source records attributed to J Adler.

At least 163 records · Page 9Linked to original sources
PubMed1988

Use of a computer to assay motility in bacteria.

An assay was developed to study the movement of free-swimming Escherichia coli. Cells were videotaped through a microscope, and the videotape images were then digitized and analyzed with a computer. Angular and linear speeds were measured for wild-type E. coli and for a smooth and a tumbly mutant. The average angular and linear speeds of a population were directly and inversely proportional, respectively, to the time spent tumbling. Changes in angular and linear speeds were followed during the response of wild-type E. coli to attractant or repellent.

Cell Movement↗
PubMed1988

Regulation of lipoprotein lipase activity in the sand rat: effect of nutritional state and cAMP modulation.

The sand rat (Psammomys obesus) is a desert rodent in which obesity and diabetes mellitus appeared only subsequent to feeding laboratory animal chow. To study the role of lipoprotein lipase in the development and maintenance of obesity in the sand rat, enzyme activity in various organs and in plasma of sand rats or albino rats was determined following a 20-hour fast, or 16 hours after injection of cholera toxin. Despite comparable change in body weight, an altered pattern of enzyme distribution and regulation was observed in the sand rat. Neither fasting nor cholera toxin had an effect on heart and daiphragm muscle lipoprotein lipase activity of the sand rat, but caused a 1.5- to 2-fold increase in the treated albino rats. By using an isolated perfused heart system, we were able to measure enzyme activity present in the heparin-releasable fraction that represents the functional pool of the enzyme. In both species, the heparin-releasable fraction of the heart increased twofold following fasting, though initial values were lower in sand rat. In both species, fasting and cholera toxin administration resulted in an increase in plasma and liver lipoprotein lipase activity. Adipose tissue lipoprotein lipase activity of sand rat, unlike the albino rats, was similar in the various fat regions and was not lowered by food deprivation or cholera toxin administration. After both treatments, sand rat plasma insulin levels exceeded fivefold those of albino rats. Adipose tissue lipoprotein lipase activity of fed and fasted normal and diabetic sand rats correlated negatively with plasma insulin and glucose levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗
PubMed1988

Muscarinic antagonist action of clinical doses of chloroquine in healthy volunteers.

An investigation was undertaken into possible vagolytic effects of chloroquine. A single oral dose of chloroquine was given to healthy human volunteers and its influence on vagally mediated heart rate changes studied. Chloroquine at a dose of 600 mg significantly increased lying and standing heart rates, reduced the beat-to-beat variation of the R-R interval and reduced the heart rate changes induced by deep breathing, by the Valsalva manoeuvre and by standing. Chloroquine at a dose of 225 mg did not produce significant changes of these parameters. The effects of 600 mg chloroquine resemble those obtained with atropine and are consistent with an antimuscarinic receptor effect.

Adult↗
PubMed1988

Osmotaxis in Escherichia coli.

The escape of motile organisms from high concentrations of chemicals was studied in Escherichia coli. We have found all chemicals tested to be osmorepellents. It was shown in both a spatial assay and a temporal assay that the known sensory receptors for chemotaxis are not used for osmotaxis, so a different sensory mechanism appears to be employed. According to the temporal assay, the mechanism between sensory receptors and flagella is also not used for tumbling response (at least in solutions above 0.4 osmolar).

Chemotaxis↗
PubMed1988

Otic cholesteatoma in the sand rat (Psammomys obesus).

To improve treatment of otic cholesteatoma, a model is needed for conduction of experiments. In the search for such a model, we have found cholesteatoma to occur naturally in Psammomys obesus. We present these findings and suggest the fat sand rat as a model for investigating cholesteatoma.

Animals↗
PubMed1988

Effect of antiorthostatic bed rest on hepatic blood flow in man.

Physiological changes that occur during exposure to weightlessness may induce alterations in blood flow to the liver. Estimation of hepatic blood flow (HBF) using ground-based weightlessness simulation models may provide insight into functional changes of the liver in crewmembers during flight. In the present study HBF, indirectly estimated by indocyanine green (ICG) clearance, is compared in 10 subjects during the normal ambulatory condition and antiorthostatic (-6 degrees) bed rest. Plasma clearance of ICG was determined following intravenous administration of a 0.5-mg.kg-1 dose of ICG to each subject on two separate occasions, once after being seated for 1 h and once after 24 h of head-down bed rest. After 24 h of head-down bed rest, hepatic blood flow did not change significantly from the respective control value.

Adult↗
PubMed1987

Hyperalgesia in spontaneous and experimental animal models of diabetic neuropathy.

Hyperactivity of nociceptive C-fibers has been recently described in diabetic BB/Wistar rats. This study assesses the association of hyperalgesia, using an analgesy-meter, with elevated glycosylated haemoglobin levels in three animal models of diabetic and nutritional neuropathies: Psammomys obesus (sand rat), streptozotocin-treated and galactose-fed rats. Pain threshold measurements (paw pressure test) and motor nerve conduction velocities were recorded in controls (n = 75), hyperinsulinaemic (n = 16), insulin-deficient (n = 46) und galactosaemic (n = 12) animals. The reproducibility of the paw pressure test, evaluated by a correlation coefficient, was statistically significant (p less than 0.001). When compared with their controls (396 +/- 18 g), the average pain threshold in young diabetic sand rats (309 +/- 17 g) was found to be markedly reduced and to correlate inversely (p less than 0.001) with their respective HbA1c levels (mean 4.9 versus 7.4%). Acute, subacute and chronic streptozotocin-diabetic rats displayed a reduction of pain threshold (p less than 0.001) associated with slowed motor nerve conduction velocities (p less than 0.001). Similarly, galactose-feeding over 4 weeks resulted in an elevation of glycosylated haemoglobin levels with significant (p less than 0.001) reductions of pain threshold and motor nerve conduction velocity. It is concluded that hyperalgesia is a constant feature of sensory dysfunction in spontaneous and experimental models of diabetic neuropathy.

Animals↗
PubMed1987

Pressure-sensitive ion channel in Escherichia coli.

We have used the patch-clamp electrical recording technique on giant spheroplasts of Escherichia coli and have discovered pressure-activated ion channels. The channels have the following properties: activation by slight positive or negative pressure; voltage dependence; large conductance; selectivity for anions over cations; dependence of activity on the species of permeant ions. We believe that these channels may be involved in bacterial osmoregulation and osmotaxis.

Electric Conductivity↗