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Biomedical subjects

D Lotan

Publications and source records attributed to D Lotan.

86 records · Page 5Linked to original sources
PubMed1981

Dopamine-induced paroxysmal supraventricular tachycardia in an infant.

Dopamine is an effective inotropic agent in the management of circulatory collapse. Ventricular dysrhythmias are reported to occur during dopamine infusion. The following report describes an infant with circulatory failure who experienced an episode of paroxysmal supraventricular tachycardia while receiving dopamine. Instability or immaturity of the cardiac conduction system during early infancy may contribute to the induction of an arrhythmia of supraventricular origin.

Dopamine↗
PubMed1981

[Urolithiasis in Isreali children (author's transl)].

Sixty-eight children (ages ranging from 5 months to 16 years) with urolithiasis were treated between 1966 and 1979. There were 36 females (53%) and 32 males (47%). Sixteen children (24%) had associated urinary tract infection; 4 out of these (6%) presented with urinary tract malformation. Fifty-five calculi (89%) were found in the upper urinary tract (kidney and ureter); 24 of the chemically studied calculi (80%) were made of calcium salts. In 30 children, metabolic investigations were carried out, leading to the discovery of hypercalciuria in 17 (57%). In one patient, important vesico-ureteral reflux associated with urolithiasis led to renal failure.

Adolescent↗
PubMed1981

Sacral agenesis.

Five cases of partial or complete agenesis of the sacrum (also called the caudal regression syndrome) diagnosed at the Chaim Sheba Medical :Center are reported. Neurological dysfunction of the bladder was present in all. Two patients were diagnosed at the ages of four months and three years, and had dilated collecting systems and neurological deficits of the upper motor neuron type. In three of the patients, the malformation was recognized later, at the ages of 7 1/2, 11 and 22 years. All three had a normal urinary tract, on examination by intravenous urography, and neurological deficits of the lower motor neuron type. Although no overt reduction of renal function was noted in those of our patients in whom diagnosis was delayed, it appears that early diagnosis and treatment of the neurogenic bladder associated with the caudal regression syndrome may reduce both morbidity and discomfort.

Abnormalities, Multiple↗
PubMed1980

Water-soluble, dextran-linked retinal: preparation, vitamin A-like activity in rats, and effects on melanoma cells.

A new, water-soluble, polymer-linked form of retinal was synthesized and tested for its ability to support the growth of vitamin A-deficient noninbred Holtzman rats and to inhibit the proliferation of melanoma cells in culture. Retinal was conjugated to the hydrazide of carboxymethyldextran in the presence of alpha-and beta-cyclodextrins. The aqueous solutions of the product contained between 200 and 1,000 micrograms retinal/ml as opposed to the low water solubility (< 0.01 micrograms/ml) of retinal itself. The retinal-dextran complex, although barely resorbed from the gastrointestinal tract, supported the growth of rats fed a vitamin A-deficient diet when administered ip at 2.3 mumol of retinal equivalent/kg body weight. Retinal and the retinal-dextran complex exhibited differential cytotoxicity toward S91 melanoma cells and caused cell lysis at 10 and 500 microM (retinal residue), respectively. At noncytotoxic doses both free retinal and its dextran-linked derivative reduced the cell proliferation rate in a time- and dose-dependent fashion with median inhibitory doses of 1 and 4 microM (retinal residue), respectively. These data demonstrated that the water-soluble retinal-dextran complex retained certain biologic activities of retinal and was less cytotoxic.

Animals↗
PubMed1980

Stimulation of melanogenesis in a human melanoma cell line by retinoids.

Retinoic acid was found to be a potent stimulant of pigmentation in human Hs939 melanoma cells. Exposure to 1 microM retinoic acid for longer than four days caused both a decrease in the rate of cell proliferation and a concomitant increase in melanogenesis. These effects of retinoic acid progressed lin-early in a time-dependent and a dose-dependent fashion such that at the end of a seven-day treatment cell growth was inhibited by approximately 65%, and both melanin content and tyrosinase activity increased more than three-fold over the control. Interpolation of the dose-response curves indicated that 3 nM retinoic acid would cause half-maximal melanogenesis stimulation. No elevation in the level of cyclic adenosine 3':5'-monophosphate could be detected in the melanoma cells following various periods of exposure to retinoic acid, and the cells were unresponsive to alpha-melanocyte-stimulating hormone. In the presence of the tyrosinase inhibitor phenylthiocarbamate, retinoic acid was capable of inhibiting cell proliferation without enhancing melanin synthesis. The tumor promoter phorbol myristate acetate did not affect either the proliferation or the differentiation of the Hs939 melanoma cells. However, the enhancement of melanogenesis by 1 microM retinoic acid was inhibited by 66% in the presence of 0.1 microM phorbol myristate acetate. The tumor promoter did not reverse the growth-inhibitory effect of retinoic acid. Phorbol, a non-tumor promoter, was effective. Other retinoids, such as 13-cis-retinoic acid, retinyl acetate, nd the trimethylmethoxyphenyl analog of retinoic acid, also inhibited the proliferation and enhanced melanin production in the Hs939 cells. In contrast, retinyl palmitate, the phenyl analog of retinoic acid, and the pyridyl analog of retinoic acid were ineffective.

Cell Division↗
PubMed1980

Relationships among retinoid structure, inhibition of growth, and cellular retinoic acid-binding protein in cultured S91 melanoma cells.

S91 melanoma cells, which are sensitive to retinoic acid and contain a cellular retinoic acid-binding protein (RABP), were used in an investigation of the possible correlation between the capacities of various retinoids to inhibit cell proliferation and to bind to the RABP. Each of 27 different retinoids was evaluated for growth-inhibitory activity by exposing S91 melanoma cells to various retinoid concentrations between 1 nM and 10 microM. Subsequently, the ability of 17 of these retinoids to compete with [3H]retinoic acid for binding to RABP was determined. The results demonstrate that in addition to retinoic acid, many retinoids are capable of inhibiting the proliferation of S91 melanoma cells, although some are considerably less active. A positive correlation was found between the abilities of retinoids possessing a free carboxyl group at carbon 15 to inhibit cell proliferation and to bind to RABP. The structure-activity relationships established with the S91 cells are compared with previous reports on the biological activities of various retinoids in other systems.

Animals↗
PubMed1977

The metabolic effects of excess noradrenaline secretion from a pheochromocytoma.

We report a 14-year-old boy with severe hypertension who was cured by surgical removal of a pheochromocytoma. The tumor was shown biochemically and morphologically to secrete predominantly noradrenaline. The metabolic effects noted in this patient were raised free fatty acid levels and depressed insulin levels, hyperreninemia, hypercalcemia, and hypercalciuria with normal parathyroid function. All these abnormalities returned to normal after removal of the tumor. It is suggested that these effects were mediated via beta-adrenergic stimulation of the excess noradrenaline.

Adolescent↗
PubMed1976

Further observations on familial hypobetaliproteinaemia.

A family with hypobetalipoproteinaemia with 10 affected members is described. In six patients low density lipoprotein cholesterol (LDL-c) concentrations were about 10 % of normal. In four LDL-c was reduced to about 50 % of normal; these four patients probably represent the "intermediate" form of hypobetalipoproteinaemia. This variation in total cholesterol concentration and LDL-c among the affected individuals of the same family could reflect differences of expression in a single aberrant gene or additive expression of a gene at a second locus.

Abetalipoproteinemia↗
PubMed1972

Bacterial conjugation: an analysis of mixed recombinant clones.

A fraction of recombinant colonies resulting from conjugation is heterogenetic for unselected markers. Constitutivity for alkaline phosphatase synthesis (phoR) is studied as the unselected marker. The frequency of phoR heterogeneity depends on the genetic distance between phoR and the selected marker. Various models are considered which explain the formation of heterogenetic colonies (mixed clones), and experiments are described which test these models. It is concluded that the Hfr fragment can replicate and participate more than once in recombination thus yielding heterogenetic colonies.

Alkaline Phosphatase↗
PubMedDate not supplied

Ultrastructural changes suggestive of focal segmental glomerulosclerosis in atypical minimal change nephrotic syndrome.

In an attempt to recognize early stages of focal segmental glomerulosclerosis (FSGS) in patients with a clinical course suggesting a diagnosis other than minimal change disease (MCD) and normal histology, or minor, nondiagnostic changes on light microscopy (LM), we used a protocol for systematic and extensive electron microscopy (EM) examination of kidney biopsies obtained from such patients. By this method ultrastructural pathology was found in 8 patients. These changes were localized, involving only portions of single glomerular segments. The findings included mild to moderate increase of the mesangial matrix, focal wrinkling of the capillary basement membrane, and early obliteration of the normal architecture of individual capillary loops, as well as electron-dense deposits in a mesangial and subendothelial distribution. Of these 8 patients, 2 are at present in remission without therapy (in 1, following therapy with cyclophosphamide); 3 are in remission on steroid therapy; 1 developed massive proteinuria during pregnancy, after a spontaneous remission lasting almost 2 years; 1 patient advanced to terminal renal failure 3 1/2 years after biopsy; and 1 died of sepsis 1 month after biopsy. We believe that the ultrastructural changes found may represent early or mild FSGS and that the protocol described can add valuable information in clinically worrisome patients in whom renal histology appears normal.

Adolescent↗
PubMedDate not supplied

Retinoic acid inhibits human melanoma tumor cell invasion.

The anticancer effects of retinoids have been recognized both in vivo and in vitro; however, little is known about their mechanism of action. Our study evaluated the effects of retinoic acid on the invasiveness of four human melanoma cell lines in vitro and showed a time-dependent inhibition of the ability of these cells to penetrate matrigel-coated filters. The possible mechanisms of action responsible for the anti-invasive effect were further investigated, and the data showed that retinoic acid-treated cells: (a) secreted lower levels of collagenolytic enzymes detected in type IV collagen-containing polyacrylamide gels compared with control cells, which was demonstrated by a decreased ability to degrade [3H]proline-labeled type IV collagen substrate; (b) showed a reduction in PA activity, primarily in the form of tPA, as demonstrated by chromogenic analysis; (c) showed a heterogeneous response with regard to c-myc, c-fos and c-jun mRNA expression, as determined by Northern blot analysis; and (d) demonstrated a decrease in B-actin levels and an increase in vimentin, as demonstrated by Northern blot analysis and SDS-PAGE transblot analysis. Collectively, these data suggest that RA causes an inhibitory effect on tumor cell invasion through a reconstituted basement basement membrane matrix by suppressing type IV collagenolytic activity and PA activity, which is probably triggered through a complex series of oncogene trans-acting factors, ultimately affecting cytoskeletal expression.

Actins↗