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Biomedical subjects

B Hardy

Publications and source records attributed to B Hardy.

At least 55 records · Page 3Linked to original sources
PubMed1979

Spectrin rearrangement early in erythrocyte ghost endocytosis.

The endocytic vacuoles induced in white ghosts were found to be depleted of spectrin and therefore it was proposed that they arose from spectrin-free areas in the erythrocyte membrane. To follow changes in spectrin distribution during endocytosis, affinity-purified rabbit antispectrin antibodies were produced. Quantitative techniques were developed for the use of a highly specific 125I-F(ab')2 antispectrin, and these showed that before the appearance of vacuoles, as assessed by phase microscopy, there was a reproducible decrease in immunoreactive spectrin. To determine whether this spectrin decrease represented a local or diffuse spectrin loss or a spectrin rearrangement, morphologic studies were undertaken using transmission electron microscopy on samples treated with rabbit antispectrin and ferritin-conjugated goat anti-rabbit immunoglobulin. These studies showed that endocytosis was preceded by the creation of extensive spectrin-free areas separated by discrete spectrin-containing zones. Pretreatment of ghosts with alkaline phosphatase blocked all forms of endocytosis and prevented the creation of spectrin-free areas. Therefore, it is proposed that under the impetus of endocytosis inducers, phosphorylated spectrin is redistributed so that spectrin-free zones are created, and that endocytic vacuoles form and fuse in spectrin-free areas.

Adenosine Triphosphate↗
PubMed1979

Endocytosis in erythrocytes and their ghosts.

Study of endocytosis in human erythrocytes and their ghosts provides an opportunity for the elucidation of the steps involved in membrane invagination and fusion. The specific preparation being studied should be described with great care since circumstances that produce endocytosis may differ among the several available preparations. For example, in resealed red ghosts the addition of 0.5 to 1 mM Ca stimulates Mg-ATP-induced endocytosis, whereas in intact erythrocytes Ca addition stimulates primaquine-induced endocytosis and inhibits vinblastine-induced endocytosis. Furthermore, Ca inhibits endocytosis in white ghosts. EDTA can produce endocytosis in white ghosts but not in resealed red ghosts. In studies with white ghosts, incubation with EDTA, trypsin, or Mg-ATP produced endocytosis, whereas the prior addition of an antispectrin antibody prevented endocytosis. When the white ghost vacuoles were harvested they were found to be depleted of spectrin. These observations lead to the hypothesis that endocytic vacuoles are formed in areas of the membrane that have been substantially freed of spectrin.

Adenosine Triphosphate↗
PubMed1978

Expression of T cell suppressor activity in the immune response of newborn mice to a T-independent synthetic polypeptide.

One and two day old mice responded to the T-independent synthetic polypeptide poly (DTyr,DGlu)-poly(DPro)--poly(DLys) with high antibody production, whereas a dramatic decrease was observed in the immune response of 3 day old injected animals. The presence and expression of suppressor T cells in the 3 day old newborn mice spleens was demonstrated by transferring spleens of 3 day old mice into either thymectomized, irradiated recipients together with bone-marrow cells, or into 1--2 day old newborn recipients. In both cases a significantly lower antibody response was observed in recipients of the 3 day old newborn spleen cells as compared to recipients of the same number of adult spleen cells. No decrease in the antibody levels was detected following inoculation of 3 day old spleen cells after anti-theta-treatment, while enriched T cell populations obtained from nylon wool columns had the same suppressive effect as the whole spleen cell preparations. Thus, the cell expressing the suppressor activity in the newborn spleen is a T cell.

Animals↗
PubMed1976

In situ dissolution of ureteral calculus.

An obstructing uric acid calculus was successfully managed by dissolution in situ. The methods used are described in detail. Perhaps not applicable in all cases, the ease of the procedure makes it worth considering especially in patients at high risk for open operative intervention.

Allopurinol↗
PubMed1976

Comparison of the immune response potential of newborn mice to T-dependent and T-independent synthetic polypeptides.

Newborn mice do not, in general, produce antibodies during the 1st week of life; this inability to respond immunologically has been attributed to lack of functional macrophages and T cells. To determine whether B cells of newborn mice are functionally mature and therefore capable of producing antibodies to thymus (T) independent antigens, the response of 1-9-day-old C3H/HeJ mice injected with a thymus-independent polypeptide, poly(DTyr,DGlu)-polyDPro- -polyDLys was compared to that of their littermates injected with a thymus-dependent immunogen, poly(LTyr,LGlu)-polyLPro- -polyLLys. No antibodies were detected in 1- or 2-day-old mice immunized with the T-dependent antigen, as revealed by haemagglutination and haemolytic plaque-forming cell assays, performed 6 days after injection of the antigen. Injection of 3-day-old animals with the thymus-dependent immunogen resulted in significant immune responses which increased with age. In contrast, 1- and 2-day-old mice responded to the T-independent immunogen with high antibody levels, however, in 3-day-old injected mice, the levels were lower. When 3-day-old nude mice were injected with this antigen, no decrease in the immune response was observed. Thus, newborn mice respond immunologically to a thymus-independent antigen injected at the first 2 days after birth and the antibody levels decrease with maturation of the thymus.

Age Factors↗