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Biomedical subjects

D B Wilson

Publications and source records attributed to D B Wilson.

At least 235 records · Page 13Linked to original sources
PubMed1986

Growth hormone and prolactin immunoreactivity in the pituitary gland of postnatal little (lit) mice.

Homozygous little (lit/lit) mutant mice exhibit a growth lag which is manifested at approximately two weeks postnatally. Functional aspects of the development of pituitary growth hormone (GH) cells and prolactin (PRL) cells were thus analyzed by means of colloidal gold immunocytochemistry at the ultrastructural level in lit/lit mice and their normal counterparts ranging in age from 5 days postnatally to adulthood. In the adult normal and lit/lit pituitaries, secretory granules in GH cells and PRL cells showed a positive immunoreaction to their respective antisera, as did granules in both cell-types at 5 days postnatally. By 14 days some GH cells in lit/lit pituitaries appeared to be less densely populated with granules than GH cells in normal pituitaries, but a positive immunoreaction continued to occur even in sparsely granulated GH cells. PRL cells showed ultrastructural features in lit/lit pituitaries which were similar to those in normal mice, and immunoreactivity was present at all stages examined. The results indicate that since differences in granule reactivity were not evident between lit/lit and normal GH cells, despite ultrastructural morphologic differences which were present by 14 days postnatally, manifestations of the defect in lit/lit may be primarily quantitative in terms of numbers of granules and/or numbers of GH cells. With respect to PRL cells, neither morphologic nor functional aberrations could be observed; thus, a deficit in PRL hormone production might be the result of a more subtle defect than that in GH cells.

Animals↗
PubMed1986

Mineral content of foods and total diets: the Selected Minerals in Foods Survey, 1982 to 1984.

The 234 foods of the FDA's Total Diet Study were collected four times per year form mid-1982 to mid-1984 and analyzed for 11 essential minerals. Daily intakes of the minerals were estimated for eight age-sex groups of the U.S. population. Levels of calcium, magnesium, iron, zinc, copper, and manganese were low (less than 80% of the RDA or below the low end of the Estimated Safe and Adequate Daily Dietary Intake range) for some or all age-sex groups. Those most at risk of low intakes were young children, teenage girls, adult women, and older women. Non-discretionary sodium intake exceeded the upper Estimated Safe and Adequate Daily Dietary Intake range for two age-sex groups, and iodine was considerably above the RDA for all age-sex groups. Levels of potassium, phosphorus, and selenium were adequate for all groups.

Diet Surveys↗
PubMed1986

Quantitative aspects of the cell cycle in the cranial neural tube of the rhesus monkey (Macaca mulatta) during early stages of gestation.

The generation time of ventricular cells in the cranial neural tube of the rhesus monkey embryo was estimated by means of tritiated thymidine autoradiography at stages 12, 13, and 14 (25-31 d of gestation) relative to that which occurs in the mouse at corresponding stages of development. In the rhesus monkey embryo, the generation time lengthens between stages 12 and 13 of gestation, as is the case in the mouse at comparable stages. However, the generation time in rhesus monkey embryos at stage 13 appears to be longer than that in comparable mouse embryos at 10 days of gestation. Thus, it is possible that temporal differences may occur between the rhesus monkey embryo and mouse embryo in terms of the response of the cranial neuroepithelium to teratogenic insults involving the cell cycle.

Animals↗
PubMed1985

Evidence for a shared HLA-A intralocus determinant defined by monoclonal antibody 131.

We describe here a monoclonal antibody, 131, which appears to recognize a determinant shared by HLA-A locus-encoded gene products. Isoelectric focusing analysis demonstrates that 131 reacts with the products of at least seven different HLA-A alleles but none of the five HLA-B allelic products tested. Together with evidence provided by other studies, this finding indicates the existence of A-unique and B-unique determinants, which may have different biological functions. Monoclonal antibody probes, such as the one described here, specific for shared intralocus determinants, may be valuable for assessing these possible functional differences.

Antibodies, Monoclonal↗
PubMed1985

Isolation and characterization of the inositol cyclic phosphate products of polyphosphoinositide cleavage by phospholipase C. Physiological effects in permeabilized platelets and Limulus photoreceptor cells.

Cleavage of the polyphosphoinositides, catalyzed by phospholipase C purified from ram seminal vesicles, produces phosphorylated inositols containing cyclic phosphate esters (Wilson, D. B., Bross, T. E., Sherman, W. R., Berger, R. A., and Majerus, P. W. (1985) Proc. Natl. Acad. Sci. U. S. A. 82, 4013-4017). In the present study we describe the isolation and characterization of inositol 1:2-cyclic 4-bisphosphate and inositol 1:2-cyclic 4,5-trisphosphate, the two cyclic phosphate products of phospholipase C catalyzed cleavage of phosphatidylinositol 4-phosphate and phosphatidylinositol 4,5-bisphosphate, respectively. We established the structures of these two cyclic compounds through 18O labeling of phosphate moieties, phosphomonoesterase digestion, and fast atom bombardment-mass spectrometry. We examined the physiological effects of these compounds in two systems: saponin-permeabilized platelets loaded with 45Ca2+ and intact Limulus photoreceptors. Both inositol 1:2-cyclic 4,5-trisphosphate and the noncyclic inositol 1,4,5-trisphosphate, but not inositol 1:2-cyclic 4-bisphosphate, release 45Ca2+ from permeabilized platelets in a concentration-dependent manner. Injection of inositol 1:2-cyclic 4,5-trisphosphate into Limulus ventral photoreceptor cells induces both a change in membrane conductance and a transient increase in intracellular calcium ion concentration similar to those induced by light. We injected inositol 1,4,5-trisphosphate and inositol 1:2-cyclic 4,5-trisphosphate into the same photoreceptor cell and found that the cyclic compound is approximately five times more potent than the noncyclic compound in stimulating a conductance change. We speculate that inositol 1:2-cyclic 4,5-trisphosphate may function as a second messenger in stimulated cells.

Animals↗
PubMed1985

The 5-hydroxyl of myo-inositol is essential for uptake into HSDM1C1 mouse fibrosarcoma cells.

We attempted to replace the myo-inositol in cellular inositol phosphatides with 5-deoxy-myo-inositol to evaluate the role of inositol 1,4,5-trisphosphate as a second messenger. This analog, lacking a 5-hydroxyl, might be incorporated into 5-deoxyphosphatidylinositol and converted to the corresponding phosphatidylcyclitol 4-phosphate but could not be converted to phosphatidylinositol 4,5-diphosphate, the precursor of the second messenger molecule inositol 1,4,5-trisphosphate. We synthesized 5-deoxy-myo-inositol and found that this analog does not replace myo-inositol as an essential growth factor for essential fatty acid deficient HSDM1C1 mouse fibrosarcoma cells. Furthermore, [5-3H]-5-deoxy-myo-inositol was neither incorporated into the phospholipids nor accumulated in the cytoplasm of these cells. It appears that this cell line has a specific myo-inositol uptake system that excludes a potentially harmful analog of inositol.

Animals↗
PubMed1985

Phosphoinositide interconversion in thrombin-stimulated human platelets.

Stimulation of platelets and other secretory cells by agonists results in the degradation of phosphoinositides by phospholipase C. Kinetic studies suggest that hydrolysis of phosphatidylinositol 4,5-diphosphate (PI-4,5-P2) is an initial event in this process. Platelets contain much larger amounts of phosphatidylinositol (PI) than PI-4,5-P2, and approximately 50% of total phosphoinositides are degraded upon stimulation. We have investigated whether degradation of PI occurs by direct phospholipase C hydrolysis or by phosphorylation to PI-4,5-P2 followed by phospholipase C action on the latter compound. When platelets are incubated for 3 min with 32Pi prior to stimulation, the phosphoinositides are labeled to different specific activities. Under these nonequilibrium conditions, the time course of change in specific activity reflects turnover. The rise in specific activity of phosphatidylinositol 4-phosphate (PI-4-P) is similar in stimulated and unstimulated cells, indicating that there is little increase in the conversion of PI to PI-4-P during thrombin stimulation. In addition, the specific activity of the 4-phosphate in PI-4-P during thrombin stimulation is less than both the 5-phosphate of PI-4,5-P2 and the phosphate group of phosphatidic acid, indicating that the 4-phosphate moiety is not labeled to equilibrium with ATP. This finding is inconsistent with a rapid flux of PI via PI-4-P to PI-4,5-P2 during thrombin stimulation, in which case the 4-phosphate would be at maximum specific activity. We, therefore, conclude that the bulk of PI breakdown that occurs in thrombin-stimulated platelets occurs via direct phospholipase C hydrolysis of PI.

Blood Platelets↗
PubMed1985

T cell receptors for responses to Mls determinants and allo-H-2 determinants appear to be encoded on different chromosomes.

Previous studies have shown that T cell clones specific for strong Mlsa,d determinants concomitantly display apparently random reactivity to allo-H-2 determinants. One explanation for this finding is that T cell recognition of Mlsa,d and allo-H-2 determinants is controlled by separate sets of receptors. If these receptors were chromosomally unlinked, karyotypically unstable T cell hybrids with dual reactivity for Mlsa,d and particular allo-H-2 determinants would be expected, occasionally, to lose reactivity for one set of determinants, but not the other. The results presented here provide direct support for this prediction.

Animals↗
PubMed1985

Capacity of small B cell-enriched populations to stimulate mixed lymphocyte reactions: marked differences between irradiated vs. mitomycin C-treated stimulators.

To investigate whether small B cells can stimulate mixed lymphocyte reactions (MLR), highly purified populations of large vs. small B cell fractions were tested for their capacity to evoke MLR across Mls vs. H-2 barriers. Large B cell fractions stimulated high MLR to Mls and H-2 determinants, irrespective of whether the stimulators were exposed to irradiation or pretreated with mitomycin C. In accord with the findings of others, irradiated small B cell fractions proved to be very poor stimulators of MLR. Significantly, however, mitomycin C-treated small B cell fractions elicited high MLR, particularly to Mls determinants. The finding that small B cell fractions treated with irradiation are poor stimulators of T cells correlates with the known radiosensitivity of B cells. In this respect, the widely held view that small B cells do not have antigen-presenting cell (APC) function rests largely on studies with irradiated B cells. The present finding that T cells respond well to small B cells treated with mitomycin C, however, indicates that small B cell fractions do have APC function. Whether the APC function of small B cells reflects a response to resting B cells per se rather than to cells undergoing activation in vitro, however, remains to be ascertained.

Animals↗
PubMed1985

An ultrastructural analysis of abnormal otic development in exencephalic mutant mice.

Homozygous loop-tail (Lp/Lp) mice exhibit defects in the otocyst as well as extensive neural dysraphism. At 19 days of gestation, cells in the otic pit of abnormal embryos are flattened and lack the rounded luminal contours characteristic of otic cells in their normal littermates. Apical filaments also are not as prominent as in normal embryos, and there is an increase in densely stained globular material in cells at the ventral lip of the otic pit. With glutaraldehyde-tannic acid fixation, the basal lamina of the otic pit cells shows differences from that of the normal otic pit. In abnormal specimens, the lamina densa is irregular and clumped, and the adjacent less dense area is spotty and lacks the more uniformly arranged and delicate fibrils characteristic of the normal basal lamina. These defects may reflect faulty developmental interactions between the dysraphic neural tube, mesenchymal cells, and otic anlage.

Animals↗
PubMed1985

Ultrastructural analysis of basal neuroepithelial cells in dysraphic mice.

Ultrastructural aspects of the cellular pathology in the basal neuroepithelium of the hindbrain and spinal cord were analyzed in dysraphic loop-tail mice at nine days of gestation. Whereas the basal cytoplasm of the neuroepithelium in normal littermates showed a consistent electron density, the neuroepithelium in abnormal embryos was characterized by "light" and "dark" cells scattered randomly along the basal aspect of the hindbrain and spinal cord. In the abnormals, gaps occurred in the neural basal lamina, and the neuroepithelial cells often were in direct contact with cytoplasmic processes from mesenchymal cells and from notochordal cells; in normal littermates, contact was observed only between the intact and continuous neural basal lamina and mesenchymal cells and notochordal cells. Thus, it is possible that the pathological features observed ultrastructurally in the basal neuroepithelium in dysraphic embryos may represent faulty tissue interaction with adjacent notochordal and mesenchymal cells.

Animals↗
PubMed1985

Inositol cyclic phosphates are produced by cleavage of phosphatidylphosphoinositols (polyphosphoinositides) with purified sheep seminal vesicle phospholipase C enzymes.

Previous studies have shown that metabolism of phosphatidylinositol by phospholipase C produces a mixture of two water-soluble products: inositol 1-phosphate and inositol 1,2-(cyclic)phosphate. In the present study, we demonstrate that the water-soluble products of phosphatidylphosphoinositol (polyphosphoinositide) cleavage by purified ram seminal vesicle phospholipase C enzymes also contain cyclic phosphates. Inositol cyclic phosphates were detected by 18O labeling. In the presence of acid, cyclic phosphates are rapidly hydrolyzed to phosphomonoesters, and when the hydrolysis is carried out in H2 18O, the resultant phosphomonoesters will contain 18O. The 18O content of the phosphomonoesters was measured following alkaline phosphatase treatment and conversion of the inorganic phosphate to a volatile derivative for gas chromatography/mass spectrometry. Inositol cyclic phosphates were found in the phospholipase C cleavage products of all three phosphoinositides, but the ratio of cyclic to noncyclic product was found to decrease in the order phosphatidylinositol greater than phosphatidylinositol 4-phosphate greater than phosphatidylinositol 4,5-bisphosphate. The formation of myo-inositol 1,2(cyclic)-4-bisphosphate was further substantiated by anion-exchange HPLC of the water-soluble products of [32P]phosphatidylinositol 4-phosphate metabolism by phospholipase C. Two peaks were detected one of which, on acid treatment, incorporated 18O from H2 18O into phosphate groups, consistent with this peak containing the cyclic phosphate product. These results suggest that polyphosphoinositide breakdown in stimulated cells may occur via a cyclic phosphate intermediate, as has been described for phosphatidylinositol. These cyclic phosphates contain a reactive bond that may play a role in phosphoinositide-derived signal transduction.

Animals↗
PubMed1985

Chronic atrial fibrillation in the elderly: risks vs. benefits of long-term anticoagulation.

Chronic atrial fibrillation is generally thought to cause stroke by atrial thrombus formation with subsequent embolization. Rheumatic heart disease previously led to most cases of atrial fibrillation, but recent substantial declines in the incidence of rheumatic fever have changed the distribution of causes of atrial fibrillation. Elderly patients have an appreciable prevalence of chronic atrial fibrillation. The risks and potential benefits of long-term anti-coagulation for elderly patients with atrial fibrillation are discussed and the quality of the evidence assessed. It is concluded that the evidence is sufficiently incomplete and imperfect for a large, well-designed trial to be needed; however, this would be difficult and expensive.

Aged↗
PubMed1985

Ultrastructure of the neural basal lamina in loop-tail mice.

Ultrastructural features of the neural basal lamina were studied by means of the tannic acid and ruthenium red techniques in normal and abnormal dysraphic loop-tail mice at 9-11 days of gestation. With ruthenium red, the configuration of the neural basal lamina is similar in both normal and abnormal embryos at 9-11 days. However, differences were detected in the abnormal 9-day embryos processed with tannic acid, as compared with normal littermates. These include irregularities in the lamina rara externa, as well as differences in the staining pattern of the neuroepithelial cell plasma membrane. By 11 days of gestation, the lamina rara externa of the normal embryos shows features similar to those observed in the 9-day abnormal embryos.

Animals↗
PubMed1985

Histochemical analysis of the neural basal lamina in the hindbrain region of exencephalic mutant mice.

The neural basal lamina in hindbrain regions of exencephalic loop-tail (Lp/Lp) mice and of their normal (+/+; Lp/+) littermates was analyzed histochemically at the electron microscopic level by means of enzyme digestion and alcian blue staining with critical electrolyte concentrations (CEC) of MgCl2. At 9 days of gestation, the normal and abnormal embryos showed a similar pattern of alcian blue staining with a CEC of 0.00 M or 0.05 M MgCl2. However, with a CEC of 0.30 M MgCl2, the basal lamina in the abnormals stained more prominently, particularly the lamina rara externa, suggesting the presence of more sulfated glycosaminoglycans (GAG) in the abnormals. Moreover, predigestion of the tissues with Streptomyces hyaluronidase, which removes hyaluronic acid (HA), indicated that the abnormal basal lamina contained relatively less HA than in the normal embryos. By 10 days of gestation the normal basal lamina contained relatively more sulfated GAG and less HA and was thus more similar in appearance to that in the abnormal embryos. This apparently premature shift from HA predominance to sulfated GAG predominance in the abnormal basal lamina may be of significance in the etiology of dysraphism in this mutant.

Alcian Blue↗
PubMed1985

Human neuroblastoma cell lines are susceptible to lysis by natural killer cells but not by cytotoxic T lymphocytes.

The susceptibility of human neuroblastoma cells to direct cellular cytotoxicity has not been previously established. This is of particular interest because of their aggressive growth and low HLA expression. Neuroblastoma lines CHP 100 and CHP 126 were found to be excellent targets in 4-hr CML assays. Natural killer (NK) cells from fresh PBL and from an NK clone, 3.3, have high lytic activity against both cell lines. We also studied mixed lymphocyte culture-generated cytotoxic lines containing allo-specific cytotoxic T lymphocytes (CTL) directed against HLA antigens present on the neuroblastoma target cell lines. These lines did show excellent lytic activity, but cold target competition studies indicated that all of the lysis resulted from NK activity. This was verified by using inhibition studies with the use of monoclonal antibodies. OKT 3 and anti-HLA antibodies that block CTL function caused no reduction in kill. In contrast, anti-lymphocyte function antigen-1 (anti-LFA-1), which blocks both NK and CTL function, significantly inhibited lysis. These results serve as a functional confirmation of earlier findings of a very weak expression of HLA-A,B,C and beta 2-microglobulin on neuroblastoma cells.

Antibodies, Monoclonal↗
PubMed1985

Evidence for the role of class I and class II HLA antigens in the lytic function of a cloned line of human natural killer cells.

Monoclonal antibodies with specificity for HLA class I and class II antigens were generated which either inhibit or enhance the lytic activity of a cloned line of human NK cells. These antibodies were obtained from a fusion with spleen cells from mice immunized with NK clone 3.3. They affect the lytic function of that clone at the level of the killer cell; additional evidence suggests that the effect takes place during an early stage of lysis. Immunoprecipitation and cross-clearing experiments using MHC antibodies of known specificity demonstrate the reactivity of mAbs 131 and 164 with HLA class I antigens and mAbs 210 and 273 with HLA class II antigens. Binding studies indicate that these antibodies are probably recognizing nonpolymorphic MHC determinants. Although these antibodies bind to other NK effector cells tested, they have no effect on the lytic function of these bulk NK populations. Preliminary studies, however, indicate that they do affect the NK activity of a proportion of the clones within these bulk populations. To further assess the potential role of HLA gene products in the lytic function of NK3.3, several well-defined anti-MHC antibodies were tested for their effects on NK3.3 function. The anti-HLA class I and class II antibodies could each be grouped into functional categories based on their ability to enhance, inhibit, or not affect the lysis of NK-sensitive targets K562 and MOLT-4 by NK clone 3.3. These results demonstrate, for the first time, a potential involvement of MHC molecules with NK function.

Animals↗