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F Beck

Publications and source records attributed to F Beck.

At least 145 records · Page 8Linked to original sources
PubMed1983

Maturation of the ileal epithelium in the young rat.

Normal maturation in the rat ileal epithelium (ileal 'closure') occurs between 18 and 21 days, probably by a process of cellular replacement. A single dose of cortisone acetate induced a precocious ileal 'closure' within 6 days. The morphological changes observed were similar to those seen during normal 'closure'. Morphometric measurements made of ileal villi during both normal and induced 'closure' suggest that there was a gradual change in the type of cells produced by the crypt. This was perhaps related to the duration of exposure of the cryptal cells to the 'closure' stimulus. Ten days after cortisone acetate treatment vacuolated cells were again seen on the villus in some animals. The variation in their distribution on the villus was perhaps due to differing rates at which the villi had recommenced pinocytosis because of the physiological state of the animal. A single dose of corticosterone failed to promote any morphological changes indicative of ileal 'closure' when observed at the electron microscope level.

Animals↗
PubMed1983

Growth of 9.5-day rat embryos in human serum.

Rat embryos were explanted at 9.5 days and cultured for 48 h in human serum supplemented with glucose. The embryos were anaemic and frequently malformed. The haemoglobin and DNA content of these embryos was less than those grown in pure rat serum. Addition of 10% rat serum improved the embryonic growth as well as the haemoglobin and DNA content. This suggests that rat serum provides essential growth factors required by the embryos which are not present in human serum.

Anemia↗
PubMed1983

Maturation in the ferret ileal epithelium and the effect of cortisone acetate.

Normal maturation ('closure') in the ferret ileal epithelium occurs, between 35 and 39 days after birth, by a process of cellular replacement. The administration of cortisone acetate at doses up to 1.2 mg/g body weight for 5 days failed to promote any morphological changes in the ileal epithelium in this non-rodent species, and the results suggest that the maturing effect of cortisone acetate in the rat might be peculiar to the rodents.

Aging↗
PubMed1982

Culture of 91/2-day rat embryos in human serum supplemented and unsupplemented with rat serum.

We attempted to grow explanted 91/2-day rat embryos in vitro in human serum but were unable to demonstrate normal growth as has been previously described. The embryos were consistently smaller, anaemic, and frequently deformed. These abnormalities were overcome by supplementing the human serum with 10% rat serum. The latter possibly provides yet unidentified essential growth factors required by rat embryos that are not present in human serum.

Animals↗
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↗