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Biomedical subjects

F Beck

Publications and source records attributed to F Beck.

At least 145 records · Page 8Linked to original sources
PubMed1982

Trypan blue teratogenesis in the rat: further observations in vitro.

Explanted 9 1/2- and 10 1/2-day rat conceptuses were cultured for 24 or 48 hours and 24 hours respectively in immediately centrifuged, heat-inactivated rat serum to which trypan blue was added at concentration of 150 micrograms/ml or 300 micrograms/ml or 450 micrograms/ml. The embryos were assessed for normal growth and differentiation using the following criteria: heart beat, vitelline circulation, fusion of the allantois with the chorion, normal turning, normally closed neural tube, presence of optic vesicles, presence of forelimb buds, tail, somites, somite number, yolk sac diameter, crown-rump length, and protein content. The results indicated that trypan blue is more teratogenic when 9 1/2-day conceptuses are cultured for the first 24 hours, and that its teratogenicity decreases after 10 1/2 days. Morphological abnormalities produced included neural tube defects, turning defects, and tail defects, the tail abnormalities being manifest as fluid-filled blebs. Ten and one-half-day conceptuses cultured for 24 hours in treated serum produced predominantly tail defects. The conceptuses were cultured at 11 days, when the embryo lies completely within the yolk sac. Culture of such conceptuses in serum containing 450 micrograms/ml trypan blue produced mainly tail defects. Injection of 0.5 microliters of 0.5% dye solution into the yolk sac cavity also produced tail abnormalities; sham treatment, or the injection of sterile water or a nonteratogenic dye, azo blue, did not affect embryonic development.

Animals↗
PubMed1982

Morphometric analysis of the visceral yolk sac endoderm in the rat in vivo and in vitro.

Rat embryos together with their visceral yolk sac were grown in vitro during the early period of organogenesis from days 9.5 to 11.5 and the ultrastructural morphology od the visceral yolk sac cells was compared with that in vivo at the beginning and at the end of the culture period. Identical areas of the visceral yolk sac endodermal cells were analysed morphometrically. A measure of the functional activity was obtained by comparison of the volume density of surface density of the vacoular system. At 9.5 and 11.5 days, the values obtained were virtually identical for yolk sacs in vivo and in vitro. At 9.5 days, the volume and surface density of the endocytotic vacuoles in the embryonic endoderm was significantly lower than in the visceral yolk sac endoderm. It is concluded that the digestive function of the yolk sac is almost certainly identical in culture and in vivo and that the cells of the embryonic endoderm do not take a significant part in embryonic nutrition.

Animals↗
PubMed1982

Dose-dependent induction of embryonic abnormalities in vitro by tissue homogenates of placenta and decidua.

Homogenate preparations from normal rat placental and decidual tissue induced abnormalities when included in the culture medium of rat embryos between Day 9.5 and Day 11.5. Abnormal embryos were produced between doses of 2.5 and 4 mg/ml for the placental homogenate and between doses of 1.2 and 4 mg/ml for the decidual homogenate, but were not produced by a solution of bovine serum albumin or by a protein preparation of rat lung tissue at the same concentration. The degree to which the embryos were malformed depended on the dose and which of the two homogenates was used. The decidual homogenate preparation was more pathogenic than the placental homogenate, but both were able to produce neural-tube defects and a severe reduction in embryonic size. The possible association between these findings and some known proteins within such homogenates is discussed.

Abnormalities, Drug-Induced↗
PubMed1981

Induced cell injury and cell death as a cause of congenital malformations in rats.

Embryopathy has been produced by inhibition of histiotrophic nutrition in the rat using a number of agents which prevent this process. The experiments were carried out in vitro at various stages of development before the inception of a chorio allantoic placenta. Dose-dependent effects on the embryo were demonstrated using the acid bisazo dye Trypan Blue, which inhibits endocytosis, and an enzyme inhibitor of bacterial origin known as leupeptin which inhibits cathepsin B, H and L. Homogenates of rat kidney and placenta also produced congenital defects; the concommitant electron microscopical changes in the yolk sac suggest that these effects too are due to alterations in the availability or quality of histiotroph.

Abnormalities, Drug-Induced↗
PubMed1981

Intracellular electrolyte composition following renal ischemia.

The technique of electron microprobe analysis was used to determine the intracellular electrolyte concentrations in proximal or distal tubular cells of the rat kidney during ischemia. When the exposed kidney was maintained in air during ischemia, the composition of the surface cells differed little from control, and the electrolyte disturbances were confined to the deeper lying cells. When maintained in nitrogen, all cells underwent changes in cellular electrolyte concentrations that were uniform, indicating that the surface cells can preserve their composition during ischemia by utilizing oxygen from the air. In the proximal tubular cells, after 20 or 60 min of ischemia in nitrogen, sodium increased from 20 to 93 or 112, chloride rose from 21 to 53 or 66, potassium fell from 141 to 65 or 42, phosphate decreased from 145 to 110 or 95 mmoles.kg-1 of wet wt, and the dry wt dropped from 22.6 to 20.3 or 17.5% of wet wt, respectively. In the distal tubular cells, 20 min of ischemia in nitrogen produced little effect on cellular composition, but after 60 min, sodium increased from 11 to 77, chloride rose from 15 to 48, potassium fell from 134 to 89, phosphate decreased from 168 to 145 mmoles.kg-1 of wet wt, and the dry wt dropped from 20.8 to 18.4% of wet wt. The disturbances in sodium and potassium are caused primarily by an inhibition of the sodium/potassium pump, whereas the changes in chloride, phosphate, and dry weight content result mainly from an influx of extracellular fluid. When blood flow was reintroducing, the electrolyte disturbances were rapidly reversed in all cells, restoration being virtually complete within 60 min, but returned in some proximal cells by 18 hr of reperfusion. Thus, the disturbance in electrolyte composition increases with the duration of ischemia, is less pronounced in the distal than proximal cells and, although initially completely reversible when blood flow is restored, reappeared in the proximal cells 1 days after the initial injury.

Animals↗
PubMed1981

The effect of sodium salicylate on the rat embryo in culture: an in vitro model for the morphological assessment of teratogenicity.

The optimum teratogenic dose of subcutaneously administered sodium salicylate was determined in vivo at 9.5 days of gestation. Fetuses from rats injected with this dose at 9.5 days were examined at 11.5 days and its propensities for producing resorption as well as deformities noted. Next, maternal serum levels 3-3.5 hours and 18.5 hours after salicylate injection were determined. Having established the feasibility of determining an effect due to salicylate at 11.5 days, after injection at 9.5 days, the following experiments were performed in vitro in animals cultured between 9.5 and 11.5 days by the method of New et al. (1976a): (1) Sodium salicylate was added to the culture serum, at levels equivalent to those obtained 3-3.5 hours after maternal injection of the optimum teratogenic dose, for 24 of the 48 hours culture period. (2) Rats were cultured for the first 24 hours of the 48 hours culture period in serum taken from rats injected 3.5 hours previously with the optimum teratogenic dose. (3) Rats were cultured for 24 out of 48 hours in serum from animals which had been injected with the optimum teratogenic dose 18.5 hours before bleeding. (4) Rats were cultured for 24 out of 48 hours in serum containing salicylate added to make up levels normally associated with (3). (5) A control culture was performed. The experiment indicates great similarity between the results obtained from animals cultured in serum with salicylate added and results from culture in serum of salicylate treated rats. It appears therefore that sodium salicylate - acting directly on the feto-placental unit - is the active teratogen rather than any of its metabolites.

Abnormalities, Drug-Induced↗
PubMed1980

Electron microprobe analysis of intracellular elements in the rat kidney.

The concentrations of intracellular elements were determined by electron microprobe analysis in the nucleus and cytoplasm of freeze-dried cryosections of superficial proximal and distal tubules of the rat kidney. For the nucleus of the proximal tubular cell, the concentrations of sodium and chloride were 20 and 23 mmoles/kg of wet wt, and those of potassium and phosphorus were 144 and 150 mmoles/kg wet wt. For the nucleus of the distal tubular cell, the concentrations of sodium and chloride were significanlty lower (11 and 13 mmoles/kg wet wt), that of potassium was unchanged (143 mmoles), and that of phosphorus was significantly higher (175 mmoles). Towards the basolateral infoldings of the proximal and distal tubules and the brush border of the proximal tubules, the concentrations of sodium and chloride were higher and those of potassium and phosphorus were lower than those obtained in the nucleus, indicating the presence of extracellular compartments in these regions. Measurements performed in the centrally located cytoplasm of proximal and distal tubular cells, close to the nucleus, showed sodium and potassium concentrations to the indistinguishable from those in the nucleus, whereas chloride and phosphorus concentrations were considerably higher. These data demonstrate differences in the intracellular concentrations of phosphorus, sodium, and chloride between proximal and distal tubular cells. In neither the proximal nor the distal tubular cells, however, could a concentration difference for sodium and potassium between nucleus and cytoplasm be determined.

Animals↗
PubMed1980

Development of ferret limb buds in organ culture.

The forelimb bud explants from ferret embryos at days 20, 21, 22, 23 and 24 of gestation were cultured in a Trowell organ culture system. Satisfactory differentiation of the limb bud skeleton was achieved with limbs from embryos explanted at 22 days of gestation (up to 50 somites). Limb buds explanted at 20 and 21 days had poorly differentiated distal segments while those explanted at 23 and 24 days of pregnancy provided less information because chondrogenesis was already under way at the beginning of culture. Thus we conclude that the optimal time for culture of ferret limb buds is at 22 days of gestation. The level of differentiation corresponded to that obtained with mouse limb buds from 11 to 12 day embryos (40-43 somites). The time taken to achieve this level of differentiation in the ferret was 18 days compared with 6 days in the mouse.

Animals↗
PubMed1979

Intracellular elemental concentrations in renal tubular cells. An electron microprobe analysis.

In order to be able to examine the processes involved in transepithelial transport in tissues, which are not composed of a single cell type, methods are required, which permit analysis at a cellular level. The technique of electron microprobe analysis permits the intracellular concentrations of many elements to be determined simultaneously in various portions of the cell. The application of this method to renal cortical tissue has shown that the best estimates of the cytoplasmic concentrations are to be obtained in regions close to the nucleus, farthest from the basolateral infoldings and microvilli, which separate the intracellular environment from the extracellular space. The nuclear concentrations of Na and K do not differ from those in the surrounding cytoplasm, although those of P and Cl are somewhat higher in cytoplasm. The intracellular element concentrations in the different cell types vary somewhat, proximal tubular cells contain higher concentrations of Na and Cl and lower ones of P than distal tubular cells. Following ischaemia, a manoeuvre know to result in a disturbance of intracellular electrolytes, Na was observed to rise and K to fall only in the non-surface cells of kidneys exposed to the air, but in all cells, if the kidneys were kept air-free in an atmosphere of N2. The proximal and distal tubular cells showed a variable resistance to ischaemia, the distal tubular cells being much more resistant. Despite the severity of the electrolyte disturbance following ischaemia, the intracellular composition was completely restored one hour after re-introducing renal blood flow.

Animals↗
PubMed1979

Intracellular electrolyte concentrations in epithelial tissue during various functional states.

The scanning electron microscope together with an energy dispersive system was used to quantify intracellular elemental concentrations of transporting epithelial cells under a variety of experimental conditions. In the frog skin, the Na transport pool is comprised of the intracellular compartments of all vital cells in the different cell layers, except the mitochondria rich cells. The Na content of this transport pool exchanges easily with the epithelial (outer) bathing solution. Vasopressin increases the Na permeability of the corial cell barrier. Proximal and distal tubular cells of the rat kidney show differences in the pattern of intracellular element concentrations. The distal tubular cell is more resistant to 20 min of ischemia than the proximal cell. The changes in intracellular electrolyte concentrations following 60 min of ischemia are reversible after reperfusing the kidney with blood for 60 min. In the cells of the frog skin and rat kidney, Na and K were equally distributed between the cytoplasm and the nucleus. Differences exist for P, Cl and dry weight.

Amiloride↗
PubMed1978

The effect of trypan blue on the development of the ferret and rat.

The teratogenic effects of trypan blue given to pregnant rats and ferrets at equivalent stages of embryonic development are described. In the rat the well known teratogenicity of the dye at 8.5 days of gestation and the surprising cessation of teratogenic effect at 11.5 days (20+ somites) is confirmed. In the ferret the drug is teratogenic both at 13 and 18 days of gestation though the principal abnormalities seen are different to those described in the rat. It has been suggested that the teratogenic action of trypan blue in rats is due to an interference in the function of the yolk sac which is an organ of histiotrophic nutrition and provides the principal source of nutrition for the 8.5-day embryo that is largely replaced by a functional chorio-allantoic placenta after 11.5 days of gestation. In ferrets histiotrophic nutrition does not involve an inverted yolk sac placental system. In this species endometrial symplasma provides histiotroph which is ingested by the invading trophoblast. Histiotrophic nutrition is still of great importance at 18 days and morphological evidence indicates that chorio-allantoic placentation becomes important by about 20 days (35+ somites).

Animals↗