Search PubMed⌕ Search

Biomedical subjects

R Solomon

Publications and source records attributed to R Solomon.

At least 73 records · Page 4Linked to original sources
PubMed1989

Quantitation of HIV-1 RNA in blood cells of ARC and AIDS patients.

Peripheral blood mononuclear cells from HIV-1-infected persons were mixed with 5 M guanidine thiocyanate, and HIV-1-specific probes were hybridized with target RNA directly in the lysate. No RNA purification was needed. Hybrids were purified by repeated capture on superparamagnetic beads coated with oligo(dT) in a device-assisted format, a procedure termed "reversible target capture." Blood mononuclear cells from 70 ARC and AIDS patients were examined and found to have an average of 1.8 x 10(5) molecules of HIV-1 RNA per 2 x 10(6) cells.

AIDS-Related Complex↗
PubMed1989

A noise-free molecular hybridization procedure for measuring RNA in cell lysates.

A solution hybridization technique was designed to measure RNA abundance in crude cell lysates and at the same time to maximize confidence that signals resulted from true molecular hybridization. Cell lysates were prepared in 5 M guanidine thiocyanate, then RNA molecules in the lysates were hybridized with two probes, a 32P-labeled RNA "label probe" which provided signal and an oligodeoxyribonucleotide "capture probe" containing a poly(dA) tail which provided a mechanism for selective purification. Ternary hybrids were "captured" on oligo(dT)-coated superparamagnetic beads through a readily reversible interaction with the poly(dA) of the capture probe. RNA did not bind to dT beads through poly(A) under the capture conditions used. Hybrids were purified through cycles of capture on and release from dT beads, with each cycle yielding a 100- to 1000-fold reduction in noise (unhybridized label probe) and a 50-90% recovery of signal (hybridized label probe). Noise was driven below detectable limits after three cycles of capture, thereby improving the sensitivity of measuring target RNA. As few as 15,000 target molecules, 15 fg of a 3-kb RNA, was detectable in the equivalent of 2 x 10(6) cells in concentrated cell lysates (10(8) cells/ml). Since hybridization with both probes was required in order to yield a signal, hybridization specificity could be adjusted with either or both probes. The greater specificity and lack of noise increased confidence that the signal was proportional to the amount of RNA of interest.

Guanidines↗
PubMed1989

Probes for quantitating subpicogram amounts of HIV-1 RNA by molecular hybridization.

A set of probes was designed for the quantitation of HIV-1 RNA in infected cells by a molecular hybridization procedure called reversible target capture. Reversible target capture is analogous to sandwich hybridization, except that the link between hybrid complexes and the affinity support was reversible, allowing for repeated capture of hybrids on, and release from, fresh affinity support. Repeated cycles of capture resulted in a high degree of purification of hybrids from unreacted probe, thereby greatly reducing assay noise and increasing assay sensitivity. Probes against the HIV-1 pol gene were chosen because their target sequences were highly conserved among HIV-1 isolates, while being divergent enough to provide discrimination from other human T cell tropic viruses. Subpicogram quantities of HIV-1 pol gene RNA were measured with signal:noise ratios of over 10. Hybridization signal increased with increasing target RNA with a proportionality constant of 1.

Cells, Cultured↗
PubMed1989

Low background scintillation counting.

Counting radioactive samples with Beckman Instrument's Ready Caps, using a restricted energy window, LL-UL = 400-1000, resulted in machine backgrounds of under 2 cpm and efficiencies of counting relative to liquid scintillation cocktails (LSC) of 51%, 65%, 57%, 62%, and 1% for 32P, 125I, 14C, 35S and 3H, respectively. Signal-to-noise ratios from a quantitative molecular hybridization technique were increased 8-10 fold. There may be a general application for this product in experiments yielding low amounts of radioactivity in liquid samples.

Animals↗
PubMed1988

Identification of two distinct protein carboxyl methyltransferases in eucaryotic cells.

Two distinct protein carboxyl methyltransferases (PCM) were identified in the electric organ of Torpedo ocellata. They were separated from each other in the active form by means of nondenaturing gel electrophoresis and by p-(chloromercuri)benzoate-agarose chromatography, and were individually identified by specific polyclonal antibodies. The existence of at least two distinct PCMs in eucaryotic cells raises the possibility that these enzymes are involved in distinct transmethylation reactions.

Animals↗
PubMed1988

High levels of protein carboxyl methyltransferase in well-differentiated human endometrial carcinoma.

The levels of protein carboxyl methyltransferase, an enzyme that methylates free carboxyl groups of proteins, were determined in normal human proliferative and secretory endometrium and in poorly and well-differentiated endometrial carcinoma. Protein carboxyl methyltransferase activity was 67% higher in the well-differentiated carcinoma than in the normal tissues, while similar enzyme levels were observed in the two normal tissues and in the poorly differentiated carcinoma. The results suggest that in the well-differentiated tumor there is excessive protein methylation and offer a possible biochemical probe for distinguishing between the two types of tumor.

Endometrium↗
PubMed1988

Effect of bedside needle disposal units on needle recapping frequency and needlestick injury.

Needle recapping has been shown to be one of the leading causes of needlestick injuries. Frequency of recapping has not been reported. This study was designed to determine the frequency of needle recapping by nursing personnel and the effect of bedside needle disposal units on the frequency of recapping and needlesticks. Seventy-four nurses carrying out 312 activities involving use of needles were observed. The subjects were not aware of the nature of the study. The recapping frequency was 93.9%. The study was repeated after educational programs and following installation of a hospital-wide bedside needle disposal system. Fifty-three nurses performing 151 activities with needles were observed. Frequency of recapping was 94%. There was no significant difference in the rate of recapping or needlestick injuries after installation of the new needle disposal system. Educational programs regarding recapping, a very common practice, may be ineffective. Alternate methods for preventing needlesticks may be necessary.

Accidents, Occupational↗
PubMed1988

The effect of diuretics on components of the urinary kallikrein-kininogen-kinin system in man.

The effects of acute infusions of diuretics on components of the human urinary kallikrein-kininogen-kinin system were determined. Normal human subjects were given infusions of chlorothiazide and furosemide in doses calculated to produce a comparable natriuresis and diuresis. Alterations in urine electrolyte excretion, kinins, total and intact kininogen, and total active kallikrein were determined before and after the diuretic administration. Chlorothiazide caused a significant increase in total, but not active, kallikrein and had no effect on kinins and total or intact kininogen. Furosemide did not alter total or active kallikrein, or intact kininogen, but did decrease kinin and total kininogen excretion significantly. These differences in effects were not related to urinary sodium excretion or urinary flow because both diuretics produced comparable effects on these parameters. We conclude that acute infusions of diuretics do not activate the kallikrein-kininogen-kinin system and that some of the previously described effects of diuretics on this system may be related to their site of action.

Adult↗
PubMed1988

Neural control of shark rectal gland.

Veratrum alkaloids stimulated salt secretion by the isolated perfused rectal gland of Squalus acanthias. Stimulation by veratrine was prevented by the nerve channel blockers tetrodotoxin and procaine and was not evident in a preparation of dispersed rectal gland cells. Vasoactive intestinal peptide (VIP)-like immunoreactivity was detected by histological techniques in neuronal tissue within the rectal gland. Veratrine stimulation caused the release of immunoreactive VIP into the venous effluent of perfused glands. The stimulatory action of veratrine was inhibited by somatostatin, another neuropeptide known to be present in nerves of Squalus rectal gland. These findings suggest the likelihood of neural modulation of rectal gland function.

Adenosine↗
PubMed1988

The kallikrein-kininogen-kinin system in patients with liver disease and ascites.

The urinary excretion of kininogen, kallikrein (total and active), and kinins were measured in 7 men with severe liver disease and ascites. The results were compared with a group of normal controls matched for sodium excretion. Significant reductions in kinin excretion were noted in the patients with liver disease which could not be accounted for by differences in age, plasma renin, aldosterone excretion or sodium excretion. Both active kallikrein and kininogen excretion were reduced suggesting that deficiencies of enzyme and substrate contributed to the kinin deficiency. The importance of kininogen in the physiologic regulation of kinin excretion in this clinical state is discussed.

Adult↗
PubMed1987

The relationship between disorders of K+ and Mg+ homeostasis.

Potassium and magnesium balance are frequently altered by common pathological conditions. Isolated disturbances of potassium balance do not produce secondary abnormalities in magnesium homeostasis. In contrast, primary disturbances in magnesium balance, particularly magnesium depletion, produce secondary potassium depletion. This appears to result from an inability of the cell to maintain the normally high intracellular concentration of potassium, perhaps as a result of an increase in membrane permeability to potassium and/or inhibition of Na+-K-ATPase. As a result, the cells lose potassium, which is excreted in the urine. Repletion of cell potassium requires correction of the magnesium deficit. Are such magnesium dependent alterations in potassium balance of any clinical significance? Within the context of electrolyte disturbances, magnesium replacement is often necessary before hypokalemia and potassium depletion can be satisfactorily corrected with potassium supplements. The hyponatremia often seen with chronic diuretic usage may also be related to depleted intracellular potassium stores. In a small group of patients with chronic congestive heart failure, magnesium replacement alone was sufficient to correct this hyponatremia. Finally, magnesium and potassium depletion may play an important role in the development of cardiac arrhythmias in certain select groups of patients, such as those with overt ischemic heart disease. The frequency of magnesium depletion in some clinical disease states warrants renewed interest in the relationship between magnesium and potassium homeostasis.

Animals↗
PubMed1986

Antihypertensive effects of indoramin and prazosin in combination with hydrochlorothiazide.

The safety and efficacy of indoramin and prazosin added to hydrochlorothiazide (HCTZ) were compared in a double-blind trial involving 209 patients with mild to moderately severe essential hypertension. Patients whose supine diastolic blood pressure (SDBP) did not decrease to less than or equal to 90 mm Hg after 6 weeks of HCTZ therapy had indoramin or prazosin added to their regimen. Mean SDBP during 6 months of combination therapy with either regimen decreased by approximately 10 mm Hg from that at the final evaluation during HCTZ therapy (p less than 0.001); differences between the groups were not statistically significant. Mean heart rate was unchanged, whereas mean weight increased (p less than 0.001) above final HCTZ values by approximately 2 kg in both groups. Mean weight increased significantly (p less than 0.01) from baseline values, however, only in the prazosin/HCTZ group. Approximately 95% of the patients in each group had clinically significant decreases in SDBP. Fatigue or tiredness and dizziness were the most commonly reported adverse effects, and their frequencies were not significantly different in the two groups. Cardiac arrhythmias occurred only in patients in the prazosin/HCTZ group and were significantly (p less than 0.05) more frequent than among patients in the indoramin/HCTZ group; less severe adverse experiences, i.e., dry mouth, ejaculatory problems, drowsiness, and sedation, were significantly (p less than 0.05) more frequent in the indoramin/HCTZ group. When added to HCTZ, indoramin and prazosin are equally safe and effective in the treatment of hypertension.

Blood Pressure↗
PubMed1986

Metabolic response to exercise and muscle disease.

Physical fitness through exercise is the rage of today. Almost everybody is indulging in various forms of exercise from weight lifting to marathons. These regimens presuppose a normal muscle metabolism. However, a significant number of so-called normals end up with the symptoms of cramps, fatigue, and, in advanced cases, myoglobinuria. Exercise forms the mainstay of rehabilitation of patients with neurologic disorders manifesting as paresis or paralysis, and certain rheumatologic or metabolic problems are also handled via the medium of exercise therapy. It is, thus, imperative that there should be a clear understanding of normal muscle composition and metabolic responses. We will summarize the histology, histochemistry, physiology and metabolic responses of normal muscle to exercise and put this information in perspective in the light of various muscle disorders.

Adenosine Triphosphatases↗
PubMed1985

Primary role of volume expansion in stimulation of rectal gland function.

Chloride secretion by the in vivo rectal gland of the shark is stimulated by the intravascular infusion of salt solutions of varying osmolar and sodium concentration. In a cross-perfused and denervated rectal gland, the infusion of a small amount of a hypertonic salt solution raises plasma osmolality but does not increase plasma volume in the donor fish. Under these conditions, rectal gland chloride secretion is not stimulated. A subsequent infusion of isotonic shark Ringer solution increases plasma volume 50%, decreases plasma osmolality, and produces a fourfold increase in chloride secretion and a threefold decrease in vascular resistance within the gland. Both the vasodilatory and secretory responses also follow the infusion of a hypotonic shark Ringer solution. The data further support the hypothesis that the rectal gland of the shark is involved in the regulation of intravascular volume rather than in osmoregulation.

Animals↗