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Biomedical subjects

F Beck

Publications and source records attributed to F Beck.

At least 181 records · Page 10Linked to original sources
PubMed1971

Digestion of an exogenous protein by rat yolk-sac cultured in vitro.

Yolk-sacs were removed from 17.5-day pregnant rats injected 2-5h previously with (125)I-labelled bovine serum albumin. The specific activities of acid phosphatase and acid proteinase, and the specific radioactivities (trichloroacetic acid-insoluble and trichloroacetic acid-soluble) were measured in subcellular fractions prepared by homogenization and differential centrifugation. The conversion of acid-insoluble into acid-soluble radioactivity within cultured tissue was followed and the nature of the liberated products was investigated by gel chromatography. The results are consistent with the protein entering lysosomes and being digested there. The radiolabel was released chiefly as free iodotyrosine.

Acid Phosphatase↗
PubMed1969

Protein digestion in isolated lysosomes inhibited by intralysosomal trypan blue.

Control rats and rats treated with subcutaneous trypan blue were injected intravenously with denatured albumin-I(125). Lysosome-rich fractions of their livers, when incubated at 22 degrees C in osmotically protected medium (pH 7.4), retained their capacit to digest albumin-I(125). The rate of digestion was lower in suspensions pre-pared from rats treated with trypan blue than in control suspensions, but rates of lysosome breakage were not different. T'hese results and other experimental evidence suggest that trypanblue concentrated within lysosomes can inhibit intralysosomal digestion, probably by inhibition of lysosomal proteinases.

Acid Phosphatase↗
PubMed1967

Lysosomal enzyme inhibition by trypan blue: a theory of teratogenesis.

A mechanism of mammalian teratogenesis involving inhibition of embryotrophic nutrition is suggested and exemplified by the action of trypan blue on pregnant rats. There is evidence for the localization of trypan blue in heterolysosomes of the epithelium of the visceral yolk sac, and our experiments indicate that the dye is an inhibitor of a selection of hydrolytic enzymes present in lysosomal fractions from homogenates of rat visceral yolk sac. It seems likely that trypan blue inhibits the intracellular digestion of embryotroph by the visceral yolk-sac epithelium; the conceptus may therefore be deprived of essential nutrients at critical stages of development.

Abnormalities, Drug-Induced↗
PubMedDate not supplied

Transmission of ground squirrel hepatitis virus to homologous and heterologous hosts.

The infectivity and host range of ground squirrel hepatitis virus (GSHV) have been further examined by animal inoculation experiments. Although carrier squirrel sera usually harbor 10(9) to 10(10) virions per ml as determined by physical measurements, titration of one such serum revealed that squirrel infectivity was lost following dilution of the sample over 10(6)-fold. Infectivity is markedly reduced by NP40 pretreatment of infected serum. GSHV infection cannot be readily transmitted to several related ground squirrel species, but chipmunks can be experimentally infected by GSHV virions or by cloned GSHV DNA, and the resulting infection closely resembles that seen in the normal host.

Animals↗
PubMedDate not supplied

Uptake and digestion of 125I-labelled bovine serum albumin by the rat visceral yolk sac cultured in vitro as a closed vesicle.

A system for culturing the rat visceral yolk sac in vitro as a closed vesicle--the 'giant' yolk sac--has been employed to investigate the vectorial nature of the uptake and digestion of exogenous protein substrates. Uptake of 125I-labelled formaldehyde-denatured bovine serum albumin by such yolk sacs was found to be similar to that observed in yolk sacs removed directly from the mother at 17.5 days' gestation, provided that homologous serum was used as a culture medium. However, unlike the control yolk sacs, giant yolk sacs tended to accumulate substrate within the tissue with increasing culture time. The concentration of digestion products released to the inside of the closed vesicle was found to be greater than that released to the surrounding culture medium at time intervals up to five hours. Giant yolk sacs preloaded with 125I-labelled bovine serum albumin were found to release material to the culture medium or the inside of the vesicle almost entirely in the acid-soluble (digested) form. This system is a useful model for studying the polar nature of epithelia, particularly those involved in the uptake and transport of nutritional and/or informational macromolecules.

Animals↗