PubMed Health⌕ Search

Biomedical subjects

S Forster

Publications and source records attributed to S Forster.

31 records · Page 2Linked to original sources
PubMed1985

pH-profile of cystine and glutamate transport in normal and cystinotic human fibroblasts.

In the human recessive condition cystinosis, cystine transport has been reported to be normal in the plasma membrane but defective in the lysosome membrane. A possible explanation is that the transport systems at the two cellular sites are identical and that the defect in cystinosis affects the porter's ability to operate at the low pH of the lysosome. To test this hypothesis the uptake of 3H-labelled cystine and glutamate by normal and cystinotic human skin fibroblasts has been measured in vitro at pH 5.8, 6.5, 7.0, 7.4 and 8.0. Uptake of glutamate was more rapid than that of cystine. Uptake of cystine increased with increasing pH, but uptake of glutamate showed no marked pH-dependence. Transport in cystinotic cells was similar to that in normal cells, and similarly affected by pH. This finding is incompatible with the hypothesis proposed above. It is concluded that the cystine porters of the plasma membrane and the lysosome membrane are probably genetically distinct.

Biological Transport, Active↗
PubMed1985

The role of pinocytosis in the cellular uptake of an amino acid.

Uptake of L- and D-alanine by the rat visceral yolk sac has been studied in vitro in incubations of short duration. It is concluded that much of the uptake of D-alanine is due to fluid-phase pinocytosis and that the plasma membrane L-alanine porter is more stereospecific than has hitherto been supposed.

Alanine↗
PubMed1985

Isolation and preliminary biochemical characterization of the human epidermal Langerhans cell.

A method is described for the isolation of human epidermal Langerhans cells (LC). Following the disaggregation of the epidermis by gentle trypsinization, the cell suspension is incubated with the fluorescein-conjugated monoclonal antibody OKT6. Using a fluorescence-activated cell sorter, a subpopulation is selected on the basis of positive fluorescence and low forward-scatter, the latter parameter reducing contamination by LC-keratinocyte clusters. The LC averaged 1.7% of the original epidermal preparation. The purity averages 83% as judged either by OKT6 binding or by ATPase activity. Biochemical measurements indicated that the activity of lysosomal enzymes was low with the exception of alpha-mannosidase, which was about 12-fold higher than that of the keratinocyte. The activities of 3 enzymes of intermediary metabolism suggest that the utilization of glucose by the LC is considerably greater than that of the keratinocyte.

Acid Phosphatase↗
PubMed1985

Characterization and activity of phospholipase A2 in normal human epidermis and in lesion-free epidermis of patients with psoriasis or eczema.

The kinetic properties of phospholipase A2 isolated from single large specimens of normal human epidermis and 'uninvolved' (lesion-free) psoriatic epidermis were determined. The enzymes from the two sources behaved identically with respect to changes in protein concentration, Ca2+ concentration and pH, but the enzymes responded differently to changes in substrate concentration. Furthermore, the specific activity of the enzyme derived from lesion-free psoriatic epidermis was higher than that from normal epidermis under all conditions used. Increased specific activity of the enzyme in the lesion-free epidermis was also found when biopsy specimens taken from thirty-five patients with psoriasis vulgaris at varying severity were compared with biopsies of normal epidermis from thirty-one control volunteers (P less than 0.001). Mixing experiments, in which homogenates of lesion-free psoriatic epidermis and control epidermis were combined, suggested that the relatively low activity of the enzyme in normal epidermis was due to the presence of an inhibitor. As the activity of the enzyme was not elevated in the lesion-free epidermis from twelve cases of eczema, which is also an inflammatory condition of the epidermis and superficial dermis, it is suggested that the raised phospholipase A2 activity demonstrated in the lesion-free epidermis of psoriasis may play an important role in the pathogenesis of the disease.

Adolescent↗
PubMed1984

Utilization of epidermal phospholipase A2 inhibition to monitor topical steroid action.

The effect of several steroid creams on epidermal phospholipase A2 (PLA2) activity in symptomless psoriatic and normal epidermis was studied. The magnitude of PLA2 inhibition produced by the steroids was directly proportional to the initial level of the enzyme activity. This differential inhibition resulted in PLA2 activity approaching or attaining the normal range regardless of its initial level. Clobetasol propionate 0.05% (Dermovate) produced more enzyme inhibition than betamethasone valerate 0.1% (Betnovate) but there was no difference in inhibition between this latter steroid and clobetasone butyrate 0.05% (Eumovate). All were more inhibitory than hydrocortisone I% (Efcortelan).

Administration, Topical↗
PubMed1983

Angiosarcoma of the vagina: a clinicopathologic report. A reappraisal of the radiation treatment of angiosarcomas of the female genital tract.

A first case of angiosarcoma of the vagina is described. Review of medical literature fails to show any documented cases of primary angiosarcoma of the vagina. Because of its rarity, no definite treatment could be suggested. The guideline for the management of this disease can only be drawn from several previously reported angiosarcomas of the uterus, cervix, and pelvis. It is recommended that a combined form of external irradiation and intracavitary brachytherapy be used after removal of the tumor.

Brachytherapy↗
PubMed1983

Epidermal phospholipase A2 activity is raised in the uninvolved skin of psoriasis.

In uninvolved epidermis from nine psoriatic subjects, the mean phospholipase A2 activity was significantly greater (P less than 0.01) than in nine controls. The increased activity of this enzyme could lead to an increase in the concentration of free arachidonic acid which, in turn, could lead to increased concentrations of inflammatory mediators.

Adult↗
PubMed1979

An interophthalmic communicating artery as explanation for the consensual irritative response of the rabbit eye.

An arterial connection between the two internal ophthalmic arteries in the rabbit was confirmed. The consensual response to ocular injury and its relationship to this interconnecting artery was examined by transecting the interconnecting vessel and creating a monocular injury by anterior chamber paracentesis. In the rabbits of two control groups (those undergoing sham operation without vessel ligation and those undergoing no operation) there was a rise in protein in the aqueous of the uninjured eye. In the rabbits with the communicating artery transected, no such rise in contralateral aqueous protein occurred. It is concluded that in the rabbit this vascular connection can explain the contralateral hyperemia and aqueous protein increase seen after monocular trauma.

Animals↗