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Biomedical subjects

J L Rabinowitz

Publications and source records attributed to J L Rabinowitz.

At least 37 records · Page 2Linked to original sources
PubMed1987

A simple spectrophotometric assay for micromolar amounts of lanthanum in the presence of calcium and phosphate.

A sensitive spectrophotometric assay for micromolar amounts of lanthanum in the presence of calcium and phosphate (as hydroxyapatite) was developed utilizing the change in absorption (at 652 nm) when the dye arsenazo III was complexed with lanthanum. Arsenazo III was used at a level of 25 microM and the solution pH was maintained at 3.1 with 0.2 M sodium acetate. Lanthanum concentrations down to 0.5 microM could be reliably assayed. Calcium ion did not complex well with arsenazo III at pH 3.1. With calcium present at 100 microM and lanthanum at 10 microM, the assay was 115 times more sensitive for lanthanum. The assay is simple, rapid, reproducible and, unlike the assay using radioactive lanthanum, can be performed at any time.

Arsenazo III↗
PubMed1987

In vivo and in vitro studies of hypocholesterolemic effects of diosgenin in rats.

There is evidence that diosgenin when given orally or parenterally decreases cholesterol plasma levels in rat, chicken and rabbits that have had a diet-induced hypercholesterolemia. 2. The per-oral administration of [3H]diosgenin yielded 12% of the given dose distributed throughout: liver, spleen, epididymal fat, brain and carcass of the rat. 3. In everted gut sacs, [3H]diosgenin was better absorbed than cholesterol. 4. In these tests diosgenin was recovered esterified from the tissues and the recovered cholesterol showed less esterification in the presence of diosgenin than in its absence.

Administration, Oral↗
PubMed1987

A comparative study of three methods for the estimation of total plasmalogens in lingual taste epithelium and other tissues.

The total plasmalogen content of lingual and other tissues was analyzed using the iodine-addition (Method 1), the p-nitrophenylhydrazone (Method 2), and the two-dimensional thin layer chromatography procedure (Method 3). Methods 1 and 2 were simple, rapid and reproducible, yielding values usually in close agreement with each other, and values higher than those of Method 3. Method 3 exhibited poor reproducibility. All three methods were of comparable sensitivity (less than 20 nmol of total plasmalogen per sample). According to Methods 1 and 2, there was more total plasmalogen in lingual epithelium containing taste buds compared with lingual epithelium devoid of taste buds. Plasmalogen content of bovine and rat brain, heart and liver agreed with literature values.

Animals↗
PubMed1986

Alterations of lipid composition in a dystrophic muscle cell line.

The composition of neutral lipids and phospholipids was determined in normal (Cb7) and dystrophic (DyA4) cell lines, derived from cloned satellite cells from control and dystrophic C57BL/6J/dydy mice. The results obtained showed that dystrophic cells contain a higher relative distribution of phospholipids than their normal counterparts. Moreover, the distribution of individual phospholipids differs between normal and dystrophic cells, with increased percentage of acidic phospholipids and reduced proportion of phosphatidylcholine in dystrophic cells. Cholesterol was increased but free fatty acids decreased in dystrophic cells. The possible pathogenetic significance and functional consequences of these abnormalities are discussed.

Animals↗
PubMed1986

Current concepts in the treatment of rheumatoid arthritis.

The treatment of RA is complex and often frustrating. The pathologic process of RA is composed of acute inflammation, chronic immunologic phenomenon, and chronic connective tissue degradation. It is important to understand not only the pathophysiology of RA but also the mechanism of action of our therapeutic drugs so that treatment can be tailored to affect the important aspects of the process leading to end-organ damage. Despite the many drugs available, therapy is still unsatisfactory. Many drugs work in only certain patients. This could be secondary to variability in the disease state or to difference in drug metabolism. A better understanding of both disease and therapeutic agents may lead to better use of our present agents and development of new, more effective treatment modalities.

Adrenal Cortex Hormones↗
PubMed1986

Comparison of fatty acid patterns of polar and neutral lipid classes and cyclo-oxygenase activity in taste and non-taste epithelium of steer tongues.

Epithelial tissues and papilla from several regions of the steer tongue were isolated and the fatty acids from each lipid class in the polar and neutral fractions were assayed. The observed profiles indicated regional differences. Arachidonic acid and other fatty acids containing long carbon chains (greater than 22) were found in all tissues sampled, particularly in the phosphatidyls of the inositols, ethanolamines, cholines, and in the cholesterylesters. Production of prostaglandin E2 was measured through cyclo-oxygenase activity and the presence of plasmalogens was observed in the phosphatidylethanolamine and choline fractions. Higher rates of PGE2 synthesis and greater amounts of plasmologens were found in taste-related epithelial samples compared to lingual epithelial control samples not containing taste buds. The heterogeneity of patterns of lipids and fatty acids found in the epithelium of the tongue suggests possible zonal specialization to satisfy regional physiological needs.

Animals↗
PubMed1985

Traumatic chylous knee effusion.

A 47-year-old patient presented with a chylous knee effusion and traumatic infected skin lacerations. The diagnosis of septic arthritis was considered because of purulent looking joint fluid, spuriously high synovial fluid white cell count, and signs of acute knee synovitis. Synovial fluid lipid analysis showed increased total lipids due to high concentration of neutral lipids, mainly triglycerides, and repeated knee radiographs showed a small fracture of the tibial spine. Joint trauma with subchondral fracture can be associated with frank chylous effusion, which may mimic acute septic arthritis.

Arthritis, Infectious↗
PubMed1985

Acute monoarthritis associated with lipid liquid crystals.

We describe three women with unexplained acute monoarthritis and birefringent lipid spherules or lipid liquid crystals in their synovial fluid. Synovial fluid aspirated within 24 hours of onset showed leucocyte counts ranging from 10 X 10(9) to 46 X 10(9)/1 with 91-95% polymorphonuclear cells. Numerous positively birefringent 2-6 micron microspherules were seen inside and outside polymorphonuclear cells. These were dissolved in alcohol-ether but were not digested by uricase. Other non-birefringent globules of similar size that stained with Sudan black B were also seen. Transmission electron microscopy identified osmiophilic homogeneous or multilamellated material in phagocytic vacuoles. Serum lipids, lipase, and repeated joint radiographs were normal. Arthritis subsided completely after treatment with colchicine in one patient and nonsteroidal anti-inflammatory agents in two. Thus birefringent microspherules can be found in association with acute, otherwise unexplained, arthritis. It seems possible that certain lipid liquid crystals may induce synovial inflammation similar to inflammation seen in other crystal induced arthritides.

Adult↗
PubMed1985

Incorporation of glucose carbons into rat lung lipids after exposure to 0.6 ppm ozone.

Continuous exposure to low concentrations of ozone has previously been associated with proliferation of lung alveolar type II epithelial cells. In this study, 14C incorporation into tissue lipids was determined in isolated rat lungs by perfusion with [U-14C]glucose, at a time of maximal hyperplasia brought about by 3 days continuous exposure to 0.6 ppm ozone. Ozone exposed lungs exhibited increased rates of glycolytic energy production, indicated by an 89% increase in 3H2O generation on perfusion with [5-3H]glucose, from a control value of 17.5 +/- 2.1 mumol X h-1 X g-1 X dry wt-1 (+/- SE, n = 4). Ozone exposure resulted in enhanced 14C incorporations into glyceride-glycerol and fatty acid moieties of lung lipids of 95 and 180%, respectively, with a greater proportion of label being recovered in shorter chain fatty acids. Although increased labeling was observed in both neutral and phospholipids, the pattern of 14C recovery suggested a relative increased glucose carbon incorporation into lung free fatty acids, phosphatidic acid, and such membrane associated lipids as phosphatidylinositol and those containing sphingosine. These results are consistent with the needs of a dividing cell population for enhanced energy production and synthesis of new lipids.

Animals↗
PubMed1984

Lipid composition of the tissues of human knee joints. II. Synovial fluid in trauma.

Synovial fluid was aspirated from the knees of 125 patients and lipid profiles were determined. The patients had knee injuries with or without fracture of bone; these lipid profiles were compared with "controls" (synovial fluid obtained at surgery from patients that did not have a knee injury). Floating lipid droplets were observed in some of the synovial fluid from patients with fractures. These lipid droplets could be separated as a well-defined supernatant layer after a few minutes of centrifugation (100 X g). This layer was found to consist mostly of triglycerides. The synovial fluid from patients with fracture and those with only soft-tissue trauma showed increases in total lipids and triglyceride content but had lower phospholipids when compared with nontraumatized knees. Phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, sphingomyelin, cholesterol, monoglycerides, diglycerides, triglycerides, and free fatty acids were present in all synovial fluids assayed. The large amount of triglycerides in the synovial fluid in many cases may be a good indicator of marrow leakage. Because the soft tissue surrounding the knee is also rich in triglycerides, a low phospholipid level in some cases may be an even better indicator of marrow leakage.

Fatty Acids, Nonesterified↗
PubMed1983

Studies of nucleotides of growth-plate cartilage: evidence linking changes in cellular metabolism with cartilage calcification.

The objective of this study was to examine the nucleotides of chick growth-plate cartilage and to measure the concentration of adenine nucleotides in the pre-mineralizing and mineralizing zones. Nucleotides were isolated from the two regions using a rapid-freezing technique and the concentration of individual components was ascertained by HPLC. The actual values of ATP, ADP, and other nucleotides in cartilage was low. The lowest values were recorded in the mineralized zone. In this latter zone the energy charge ratio and the ATP/ADP ratio were depressed. This was probably due to 02-related inhibition of mitochondrial oxidative activity. Additionally, the percentage of octanoate, a short-chain fatty acid that accumulates when aerobic metabolism is disturbed, was found to have increased in the calcifying zone. These findings suggest that calcification of cartilage is associated with hypoxia-related modulation of chondrocyte metabolism.

Animals↗
PubMed1983

Lipid composition and de novo lipid biosynthesis of human palmar fat in Dupuytren's disease.

Seventy-two surgically obtained Dupuytren's disease palmar-fat (DDPF) specimens and 18 location-matched specimens from patients not suffering from this disease (controls) were studied for their total lipid composition and de novo lipogenic activity. Incubation of "DDPF" with 1-[14C]acetate in oxygen produced [14C]palmitate and [14C]stearate in approximately equal yields as those obtained from "controls." No [14C]octanate was formed in any of the palmar-fat preparations. The lipids and fatty acid analysis revealed differences: (a) DDPF specimens were richer in free fatty acids, methyl esters of fatty acids and free-cholesterol than specimens of controls. (b) DDPF specimens contained less phospholipids. (c) DDPF specimens showed a significantly higher content of octanoate and other short-chain fatty acids than specimens of controls. The above findings are not incompatible with the results expected if some mild hypoxia occurred in DDPF; this has been suggested in the statistical correlations observed for this disease and alcoholism with liver involvement.

Adipose Tissue↗
PubMed1983

Metabolism of C14 mevalonate by adult and fetal arteries.

The metabolism of mevalonate by the arterial wall was evaluated in fetal and adult maternal arteries of the New Zealand white rabbit. Freshly minced tissue from umbilical arteries, fetal aortas and adult maternal aortas was incubated in oxygenated Krebs Henseleit bicarbonate buffer at 37 degrees C in the presence of 5-14C-mevalonate or 5-14C-3-hydroxy-3-methylglutaryl-Coenzyme A (HMG CoA). After incubation, the arterial tissue lipids were extracted and total cholesterol and free fatty acids were purified by thin layer chromatography and assayed for 14C by liquid scintillation spectrometry and analyzed chemically. The conversion of labeled HMG CoA or mevalonate to cholesterol in fetal aorta was 15 fold greater than in maternal aorta and 5-10 fold greater than in fetal umbilical artery. In addition some 14C from HMG CoA became incorporated into palmitate, stearate and oleate while 14C from mevalonate appeared in palmitate and stearate in trace amounts. Similarly, conversion of label from both precursors to 14CO2 was greatest in fetal aorta followed by umbilical artery and maternal aorta of the term pregnant rabbit. Of particular interest was the observation of enhanced (3.5 fold) conversion of label from mevalonate to 14CO2 by maternal aortas at mid-gestation compared to aortas of late-term gestation. These results are consistent with the explanation that while mevalonate clearly serves as a precursor for cholesterol synthesis in arterial tissue, a finite degree of exclusion from the main stream sterol pathway also occurs. This "shunt" pathway may involve oxidation directly to CO2 or indirectly by way of fatty acids. The level of activity through this exclusion pathway in arterial tissue appears to be under physiologic control during pregnancy since a 3.5 fold increase in conversion to 14CO2 occurred in aortas obtained in midgestation compared to those obtained at term gestation.

Acyl Coenzyme A↗
PubMed1982

Comparative tissue absorption of oral 14C-aspirin and topical triethanolamine 14C-salicylate in human and canine knee joints.

The local, articular, and systemic absorption of oral and topical salicylates was studied in dogs and humans using radioisotope techniques. Topical triethanolamine 14C-salicylate was found capable of percutaneous absorption into the knee joint and surrounding tissues. In dogs, topical salicylate application resulted in higher salicylate concentrations than oral aspirin in a number of tissues, despite lower blood levels. In patients with rheumatoid arthritis, intraarticular 14C-salicylate levels after triethanolamine 14C-salicylate cream were 60 per cent of those obtained with oral aspirin. Four of six patients reported equal improvement in local discomfort after oral and topical salicylates. A potential role for topical salicylate cream in the treatment of localized rheumatic disorders is suggested.

Absorption↗
PubMed1982

Lipid profiles of taste and non-taste epithelial tissues from steer tongues.

Some hypotheses on taste reception have implicated lipids of taste cells as major receptor constituents. This study reports detailed lipid profiles of the taste bud-containing epidermis from circumvallate papillae and fungiform papillae as well as profiles from two non-taste bud tissues: circumvallate papillae dermis and epidermis from the lateral posterior of the tongue. Differences in levels of triglycerides and phosphatidylcholines were observed but these were not directly related to the presence of taste buds. At this level of analysis, it is evident that there are no unusual distributions of phospholipid classes in the taste bud epidermis when compared with the non-taste bud lingual epidermis.

Animals↗