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Biomedical subjects

D B Wilson

Publications and source records attributed to D B Wilson.

At least 217 records · Page 12Linked to original sources
PubMed1987

Expression of a Thermomonospora fusca Cellulase Gene in Streptomyces lividans and Bacillus subtilis.

A cellulase gene from Thermomonospora fusca coding for endocellulase E(5) was introduced into Streptomyces lividans by using shuttle plasmids that can replicate in either S. lividans or Escherichia coli. Plasmid DNA isolated from E. coli was used to transform S. lividans, selecting for thiostrepton resistance. The transformants expressed and excreted the endocellulase, but the ability to produce the endocellulase was unstable. This instability was shown to result from deletion of the endocellulase gene from the plasmid. Plasmid DNA prepared from a culture in which plasmid modification had occurred was used to transform E. coli, selecting for Amp cells, and all of the transformants were cellulase positive, showing that pBR322 and T. fusca DNA were deleted together. When a plasmid was constructed containing only T. fusca DNA in plasmid pIJ702, the transformants were more stable, and the level of endocellulase activity produced in the culture supernatant after growth on 0.2% glucose was close to the level produced by T. fusca cultures grown on 0.2% cellulose. About 50% of the total protein in the culture supernatant of the S. lividans transformant was endocellulase E(5). The enzyme produced by the S. lividans transformant was identical to pure T. fusca E(5) in its electrophoretic mobility and was completely inhibited by antiserum to E(5). Shuttle plasmids containing the E(5) gene that could replicate in Bacillus subtilis and E. coli were also constructed and used to transform B. subtilis. Again there was extensive deletion of the plasmid DNA during transformation and growth in B. subtilis. There was no evidence of E(5) activity, even in those B. subtilis transformants that retained the E(5) gene.

Journal Article↗
PubMed1987

Mineral content of market samples of fluid whole milk.

Results from the Food and Drug Administration's Total Diet Study on the nutrient element content of fluid whole cow's milk are presented and compared with previously published values. Whole milk was collected and analyzed yearly from 1975 through 1985. Yearly and overall means were similar for all elements except iron and iodine. The iron content of milk was generally low, but several samples had high levels. The distribution of iodine in whole milk was quite wide (0.002 to 0.094 mg/100 gm). The iodine content of milk is affected by the level of iodine added to cattle feed and by the use of iodophor sanitizing solutions used by the dairy industry. Overall mean levels of the elements in milligrams per 100 gm whole milk were: sodium, 42; potassium, 134; calcium, 106; phosphorus, 83; magnesium, 9.8; iron, 0.07; zinc, 0.37; copper, 0.009; manganese, 0.004; iodine, 0.034; and selenium, 0.001. Coefficients of variation were high (67% to 117%) for iron, copper, manganese, selenium, and iodine but ranged from 18% to 26% for the other elements. An 8-fl oz serving of whole milk is an excellent source of iodine, calcium, phosphorus, and potassium. It also provides some sodium, magnesium, zinc, and selenium but is not a reliable source of iron, copper, or manganese.

Adolescent↗
PubMed1986

The metabolism of phosphoinositide-derived messenger molecules.

The phosphoinositides are minor phospholipids present in all eukaryotic cells. They are storage forms for messenger molecules that transmit signals across the cell membrane and evoke responses to extracellular agonists. The phosphoinositides break down to liberate messenger molecules or precursors of messenger molecules. Many different compounds are formed, although the functions of only a few are understood. Recent studies elaborating the pathways for formation of products from phosphoinositides and the factors controlling their metabolism are summarized here.

Arachidonic Acid↗
PubMed1986

Cyclosporine-induced autoimmunity. Conditions for expressing disease, requirement for intact thymus, and potency estimates of autoimmune lymphocytes in drug-treated rats.

These studies explore the phenomenon of cyclosporine-induced autoimmunity in irradiated Lewis rats. We show that (a) the presence of a thymus is required, and autoimmune precursors develop in and exit from this organ to the peripheral lymphocyte pool within a 2-wk period after the initiation of cyclosporine treatment; (b) adoptive transfers of drug-induced autoimmunity to irradiated secondary recipients can be accomplished with relatively few cells of the Th subset, and these transfers of autoimmunity can be blocked by cotransfer of normal lymphoid cells; and (c) potency estimates, using popliteal lymph node assays in syngeneic and F1 recipients indicate similar levels of auto- and alloreactivity by cells from drug-induced autoimmune donors. These various findings indicate that this particular animal model may be useful for studies of the onset and control of autoimmunity, and they raise the possibility that the lack of autoimmunity in normal animals and its induction with cyclosporine may involve similar cellular mechanism as have been found to be operative in GVH reactions and specifically induced immunologic resistance to GVHD.

Animals↗
PubMed1986

Are geriatric units needed for elderly patients with hip fractures?

To assess the need for a multidisciplinary geriatric unit in the treatment of elderly patients with hip fractures, we reviewed the charts of all patients aged 60 years or older who were treated for hip fractures in five hospitals in Hamilton, Ont., between August 1982 and September 1983. We hypothesized that discharge to a different location from that before admission would indicate reduced functional status and classified the reasons for a change in residence as poor patient motivation, need for rehabilitation, compromised ambulation, postoperative complications and inevitable deterioration. We believed that geriatric care would be most beneficial to those in the first three groups. Of the 327 patients with hip fractures 40 (12%) died before discharge. Of the 287 surviving patients 149 (52%) had been discharged by 4 weeks, and only 29 (10%) remained in hospital by 12 weeks. Of the 287, 44 (15%) were discharged to a different location from that before admission: in 75% the cause appeared to be inevitable deterioration (57%) or postoperative complications (18%). The remaining 25% needed rehabilitation and were all sent to appropriate facilities. None of the patients with ambulation problems or poor motivation required an increased level of care. We could not show a need for geriatric care in our population; possible explanations are discussed.

Aged↗
PubMed1986

Immunogenicity and crossreactivity of specificity-associated markers on alloreactive T cells. Confirmation based on the model of tolerance abolition by adoptive transfer.

Syngeneic or parental strain T cells adoptively transferred into hybrid rats tolerant of third party alloantigens (L/DA tolerant of BN), in numbers insufficient to abolish tolerance, induce instead an active resistance to tolerance abolition with larger, usually effective dosages of donor cells. Of particular interest is the finding that immunization with T cells from one parental strain donor (e.g., DA) inhibited the tolerance-abolishing alloreactivity (anti-BN) of subsequently transferred T cells from the same (DA) and the other (L) parental strain donor. We conclude that anti-MHC receptors on T cells from different genetic backgrounds reactive to the same third party alloantigens share the same conserved immunogenic specificity-associated markers (SAM). The nonpolymorphism of anti-MHC receptors shown here in the transplantation tolerance model is a confirmation of the same conclusion drawn from earlier studies with the GVHD-resistance model, and it therefore suggests that these two models of T cell MHC interactions involve very similar mechanisms of T cell idiotypic regulation.

Animals↗
PubMed1986

Isolation and characterization of the inositol cyclic phosphate products of phosphoinositide cleavage by phospholipase C. Metabolism in cell-free extracts.

The phosphoinositides are metabolized by phospholipase C in response to hormone or agonist stimulation in many cell types to produce diglyceride and water-soluble inositol phosphates. We have recently shown that the phospholipase C reaction products include cyclic phosphate esters of inositol. One of these, inositol 1, 2-cyclic 4,5-trisphosphate, is active in promoting Ca2+ mobilization in platelets and in inducing changes in conductance in Limulus photoreceptors similar to those produced by light (Wilson, D. B., Connolly, T. M., Bross, T. E., Majerus, P. W., Sherman, W. R., Tyler, A., Rubin, L. J., and Brown, J. E. (1985) J. Biol. Chem. 260, 13496-13501. In the current study, we have examined the metabolism of the inositol phosphates. We find that both cyclic and non-cyclic inositol trisphosphates are metabolized by inositol 1,4,5-trisphosphate 5-phosphomonoesterase, to inositol 1,2-cyclic bisphosphate and inositol 1,4-bisphosphate, respectively. However, the apparent Km of the enzyme for the cyclic substrate is approximately 10-fold higher than for the non-cyclic substrate. These inositol bisphosphates are more slowly degraded to inositol 1,2-cyclic phosphate and inositol 1-phosphate, respectively. Inositol 1,2-cyclic phosphate is then hydrolyzed to inositol 1-phosphate, which in turn is degraded to inositol and inorganic phosphate by inositol 1-phosphate phosphatase. The human platelet inositol 1,2-cyclic phosphate hydrolase enzyme and a similar rat kidney hydrolase do not utilize the cyclic polyphosphate esters of inositol as substrates. These results suggest that the inositol cyclic phosphates and the non-cyclic inositol phosphates are metabolized separately by phosphatases to cyclic and non-cyclic inositol monophosphates. The cyclic monophosphate is then converted to inositol 1-phosphate by a cyclic hydrolase. We suggest that the enzymes that metabolize the inositol phosphates may serve to regulate cellular responses to these compounds.

Animals↗
PubMed1986

Ultrastructural immunocytochemistry of somatotrophs and mammotrophs in embryos of the dwarf mutant mouse.

The embryonic development of somatotrophs and mammotrophs in the adenohypophysis in dwarf (dw) mutant mice was studied by means of ultrastructural immunocytochemistry. Embryos at 16-18 days of gestation were removed from litters consisting entirely of dwarf homozygotes obtained from homozygous matings of adult dwarfs in which reproductivity was induced by means of hormone supplementation and renal capsule implants of normal pituitaries. Litters from normal (+/+) matings served as controls. Pituitaries from adult normal and dwarf mice also were removed and processed with the embryonic material. Thin sections were exposed to anti-growth-hormone serum (anti-GH) or to antiprolactin serum (anti-PRL) and processed immunocytochemically with the colloidal gold procedure. In the normal pituitaries, a strong positive reaction to anti-GH occurred in the adult and in embryos as early as 16 days, whereas the reaction to anti-PRL was strong in the adults but relatively weak in the embryos. In dwarf embryonic and adult pituitaries, ambiguous cells showing combinations of features characteristic of somatotrophs and mammotrophs were present. However, neither these cells nor other granulated cells reacted to anti-GH or to anti-PRL, except for a questionable reaction to the latter at 18 days and in the adult. Thus, the dwarf pituitary shows functional as well as morphological abnormalities as early as 16 days of gestation.

Animals↗
PubMed1986

Immunocytochemical analysis of somatotrophs and mammotrophs in the pars distalis of postnatal dwarf (dw) mutant mice.

The postnatal differentiation of somatotrophs and mammotrophs in the pars distalis of normal and dwarf (dw/dw) mice was analyzed by means of immunocytochemistry at the electron-microscopic level. Thin sections of Araldite-embedded pituitaries from postnatal mice ranging in age from 2 days to 3-4 months were exposed to antigrowth hormone serum (anti-GH) or to anti-prolactin serum (anti-PRL) and were processed immunocytochemically by means of the colloidal-gold technique. In the normal adult pars distalis, somatotrophs reacted strongly with anti-GH, and mammotrophs showed a positive anti-PRL reaction. In the dwarf adult, the granulated cells were unreactive with either anti-GH or anti-PRL. However, at 6 days postnatally, some cells in the dwarf pars distalis showed a positive reaction with anti-GH, though the reaction was not as strong as in the 6-day normal pars distalis. The 6-day dwarf was only faintly reactive with anti-PRL, and by 14 days the dwarf was unreactive with anti-GH as well as anti-PRL, in contrast to the strong positive reactivity to these two antisera in the normal 14-day pars distalis.

Aging↗
PubMed1986

Cytochemical localization of acid phosphatase in the hindbrain of dysraphic mice.

The cytochemical localization of acid phosphatase (AP) was studied at the ultrastructural level in the abnormal neuroepithelium of dysraphic loop-tail (Lp/Lp) embryos between 9 and 12 days of gestation. At 9-11 days, normal and abnormal embryos showed a positive AP reaction throughout the thickness of the neuroepithelium, i.e., in apical, intermediate, and basal zones, although many cells were unreactive. The reaction is sensitive to sodium fluoride and occurs in saccules and vesicles associated with the Golgi complex, as well as in vacuoles of varying size containing flocculent and particulate material. Gap-junctional vesicles, which are known to occur in increased numbers in abnormal brains, were AP-negative. By 12 days of gestation, the reaction in normal embryos was localized in the midventral marginal layer, where some cell processes were filled with reaction product; in abnormal embryos, these AP-positive processes were not observed. The results indicate that perturbations in lysosomal activity may not be fundamentally involved in the etiology of dysraphism in this mutant.

Acid Phosphatase↗
PubMed1986

Immunocytochemistry of TSH cells during development of the dwarf mutant mouse.

The functional status of thyrotrope (TSH) cells was evaluated by means of ultrastructural immunocytochemistry in the adult, early postnatal, and prenatal pars distalis of the pituitary gland in the dwarf (dw/dw) mutant mouse. In the normal (+/+; dw/+) pars distalis, thyrotropes were immunoreactive to anti-TSH serum at all stages studied, although the reaction at 17- and 18 days of gestation was much less intense than that at 26 days postnatally and in the adult. In the dwarf, cells exhibiting ultrastructural features resembling those of thyrotropes were observed, but their secretory granules were unreactive with anti-TSH. At early postnatal stages, thyrotrope-like cells were likewise unreactive in the dwarf, as were the poorly granulated cells present prenatally. Thus, the results indicate that although cells resembling thyrotropes are present in the dwarf, they are functionally abnormal not only in the adult, but also during development.

Aging↗
PubMed1986

Pathogenesis of neural dysraphism in the mouse mutant vacuolated lens (vl).

The pathogenesis and expression of caudal neural dysraphism were studied by means of tritiated thymidine autoradiography in the mouse mutant vacuolated lens (vl) at 11-13 days of gestation. In homozygous litters, all of the embryos microscopically exhibited spinal cord defects, even though dysraphism could be detected grossly only in the most severely affected ones. The defects ranged from extreme eversion of widely open neural folds to a dorsally expanded neurocoel with an attenuated or distorted roof plate. Incorporation of tritiated thymidine occurred in cells in the defective roof plates, in severely distorted areas of the neural tube where cellular disaggregation occurred, and in isolated areas within the developing intermediate layer, as well as in normal sites of cellular proliferation. The frequently observed central mass of distorted but proliferating neural tissue associated with bilateral attenuations of the roof plate suggests a failure of, or defect in, the normal process of apposition and fusion of the neural folds, rather than a failure in opposition. The range in severity and the gross and microscopic manifestations of neuropathological lesions in the homozygous vl embryos indicate that this heretofore unexplored mutant has considerable potential as an experimental model for analyzing the origins and mechanisms of human neural dysraphism.

Animals↗
PubMed1986

Differentiation of embryonic mouse GH cells and ACTH cells in vitro.

The ability of cells that produce growth hormone (GH) and cells that produce adrenocorticotropic hormone (ACTH) to differentiate in various culture media was analyzed by means of ultrastructural immunocytochemistry on 13-day embryonic mouse pituitaries that were maintained in organ culture for 3-11 days. At the time of culture, relatively undifferentiated nongranulated or poorly granulated cells that were unreactive with anti-growth-hormone serum (anti-GH) and anti-adrenocorticotropic-hormone serum (anti-ACTH) were present in the pituitary. After 10-11 days in culture, immunoreactive GH cells were obtained only in media that were supplemented with cortisol, whereas ACTH cells were obtained in all media tested, including Medium 199 alone. In cortisol-supplemented media, the GH cells showed ultrastructural features typical of those that occur in vivo, and anti-GH immunoreactivity was obtained after as little as 3 days in culture, i.e., at a stage comparable to that which occurs in vivo. The results indicate that mouse GH cells are capable of differentiating in Medium 199 supplemented only with cortisol, without the addition of fetal calf serum or insulin; cortisol therefore appears to be an essential component of the embryonic milieu for the production of GH-secretory granules.

Adrenocorticotropic Hormone↗
PubMed1986

Localization of inclusion bodies in Escherichia coli overproducing beta-lactamase or alkaline phosphatase.

High-level synthesis of the periplasmic protein beta-lactamase in Escherichia coli caused the formation of insoluble protein precipitates called inclusion bodies. beta-Lactamase inclusion bodies differed from those reported previously in that they appeared to be localized in the periplasmic space, not in the cytoplasm. The inclusion bodies contained mature beta-lactamase and were solubilized more easily than has been reported for cytoplasmic inclusion bodies. In contrast, overproduction of the periplasmic protein alkaline phosphatase caused the formation of cytoplasmic inclusion bodies containing alkaline phosphatase precursor.

Alkaline Phosphatase↗
PubMed1986

Distribution of 3H-thymidine in the postnatal hypophysis of the C57BL mouse.

The distribution of cells labelled with 3H-thymidine was determined autoradiographically in the adenohypophysis and neurohypophysis of the C57BL mouse during postnatal phases ranging from the newborn to 24 days of age, as well as in the adult. In the newborn, labelled cells are scarce in the neurohypophysis but common in the adenohypophysis. The neurohypophysis shows a surge in labelling at 5-9 days, with a sharp decline thereafter. In the adenohypophysis, labelled nuclei are scarce in the pars tuberalis after 19 days, whereas the pars intermedia and pars distalis continue to show labelled cells. In the pars distalis, at all phases, label occurs in the marginal cells along the hypophysial cleft as well as in deeper-lying cells representing follicular cells. In the adult, follicular cells are more commonly labelled relative to other cells of the hypophysis.

Aging↗
PubMed1986

Ultrastructural localization of acid phosphatase in the hindbrain of the mouse embryo.

The distribution of acid phosphatase (AP) in neuroepithelial cells in the embryonic hindbrain of the C57BL mouse was determined by means of ultrastructural cytochemistry. Fixed tissues were incubated in Gomori medium containing Na-beta-glycerophosphate as substrate and were post-fixed in osmium tetroxide, routinely dehydrated, and embedded in Epon. At 8.5-11 days, the reaction occurred in apical, intermediate, and basal zones of the neuroepithelium, although many cells were unreactive. In AP-positive cells, reaction product could be seen in saccules and vesicles associated with the Golgi complex, in large ill-defined vacuoles resembling autolysosomes, and in smaller membrane-bound bodies. By 12 days, most cells were unreactive, but a densely concentrated reaction product filled some cell processes in the midventral marginal layer. In all regions studied, the AP reaction was sensitive to sodium fluoride. Treatment with saponin and Triton-X did not affect the pattern or extent of the reaction. The results indicate that a change occurs in the nature of the AP reaction coincidental with differentiation between the eleventh and twelfth day, and that ultrastructural cytochemistry provides a means for further analysis of modifications in the distribution of AP during even earlier stages of neural development.

Acid Phosphatase↗