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Biomedical subjects

D Williams

Publications and source records attributed to D Williams.

At least 523 records · Page 29Linked to original sources
PubMed1983

Mucin synthesis. III. UDP-GlcNAc:Gal beta 1-3(GlcNAc beta 1-6)GalNAc-R (GlcNAc to Gal) beta 3-N-acetylglucosaminyltransferase, an enzyme in porcine gastric mucosa involved in the elongation of mucin-type oligosaccharides.

Pig gastric mucosa microsomes have been shown to catalyze the following reaction: UDP-GlcNAc + Gal beta 1-3(GlcNAc beta 1-6)-GalNAc-alpha-R----GlcNAc beta 1-3Gal beta 1-3 (GlcNAc beta 1-6)GalNAc-alpha-R + UDP, where R is o-nitrophenyl or benzyl. The enzyme catalyzing this reaction has been named UDP-GlcNAc:Gal beta 1-3(GlcNAc beta 1-6)GalNAc-R (GlcNAc-R (GlcNAc to Gal) beta 3-N-acetylglucosaminyltransferase. The beta 3-GlcNAc-transferase does not act on Gal beta 1-3GalNAc-alpha-o-nitrophenyl. The beta 3-GlcNAc-transferase requires Mn2+ and Triton X-100 for optimal activity. The Vmax for the microsomal enzyme is 8.7 nmol/mg protein per hour and the Km values are 1.6, 0.9, and 1.2 mM for UDP-GlcNAc and the alpha-o-nitrophenyl and alpha-benzyl derivatives of Gal beta 1-3(GlcNAc beta 1-6)GalNAc, respectively. Pig gastric mucosa microsomes catalyze the transfer of GlcNAc to lactose to form GlcNAc beta 1-3Gal beta 1-4Glc, but fail to transfer GlcNAc to lactosyl ceramide, Gal beta 1-4GlcNAc, or Gal beta 1-4GlcNAc-beta-benzyl.

Animals↗
PubMed1983

Blood flow in the ovary and adjacent structures of the non-pregnant sheep.

Blood flow of the ovary, vascular pedicle and oviduct was measured in anaesthetized non-cycling and cycling ewes by timed collection of ovarian venous blood. The degree of arterio-venous shunting across the ovary and pedicle was estimated both in vivo and in vitro by perfusing the tissues with 15 +/- 5 micrometers radioactive microspheres. The mean ovarian blood flow in non-cycling animals was 1.9 ml/min, which was 51% of blood flow in the ovarian vein. In cycling animals ovarian blood flow at midcycle was 2.9 ml/min (66% of ovarian venous flow) in non-luteal ovaries and 4.3 ml/min (79% of venous flow) in luteal ovaries. The degree of arterio-venous shunting was low in all stages of the cycle (1.0-2.6% across ovary + pedicle). The degree of shunting was also found to be very small in vitro (0.007-1.38%) in both non-luteal and luteal ovaries. A considerable number of microspheres was entrapped in the vascular pedicle of the ovary indicating the presence of an extensive capillary bed. There was an inverse relationship between blood flow in the ovary and flow in the vascular pedicle. Alterations in distribution of blood flow between the ovary and adjacent structures supplied by the ovarian artery may be of functional significance in allowing rapid changes in ovarian blood flow. The results of the present study indicate that changes in ovarian blood flow during the oestrus cycle are not caused by an action on arterio-venous shunt vessels.

Animals↗
PubMed1982

Acute lymphocytic leukemia: biological markers of clinical response.

Treatment for acute lymphocytic leukemia (ALL) has been successful in producing cures for some children with that disease. It has become increasingly important therefore to develop treatment regimens for curable All that are effective for disease control but carry minimal risks of late detrimental consequences. For other children current therapy is still inadequate and treatment failure occurs. For these children current altered treatment strategy must be developed that includes intensification of some treatment components, since improved methods of disease control are the primary consideration. In this paper the clinical and laboratory methods by which risk groups can be defined at diagnosis have been described. We have increasingly effective means by which the expected treatment outcome with current therapy can be defined at diagnosis. This assignment to a specific risk group is important to provide children with ALL with the most appropriate therapy for their expected clinical response. These studies of clinical utility also pose biological questions concerning the relationship to such things as white blood count, leukemic cell karyotype, and initial proliferative activity to the likelihood of drug resistance emerging. During the coming decade there will no doubt be an increasing emphasis on a biological characterization of leukemic cell populations. Answers must be developed to such questions as the mechanism for leukemic cell growth regulation. Biological information developed in this model tumor cell system in humans will likely produce information of value in understanding human cancer in general.

Aneuploidy↗
PubMed1982

The fine structure of the polymorphic spermatozoa of Fusitriton oregonensis (Mollusca: Gastropoda), with notes on the cytochemistry of the internal secretions.

The prosobranch Fusitriton oregonensis exhibits an unusual form of sperm polymorphism. The viable, eupyrene sperm are attached in groups of about fifty to worm-shaped, apyrene, carrier sperm. There is a second apyrene sperm, which is lancet-shaped and has a different internal organization than the carrier, but does not transport eupyrene sperm. The eupyrene sperm are filiform (185 microns long), with a conical acrosome, elongate nucleus and midpiece. They contain large stores of glycogen in the principal piece, together with an unusually high proportion of protein. The latter is due to a complex interconnecting system of fibres that supports the tail internally. A distinct annulus is located, characteristically, at the junction between midpiece and principal piece. The carrier sperm has a core of about 112 axonemes that arise from basal bodies in the anterior end and extend through its entire length of 36 microns. The basal bodies have unstriated rootlets that are embedded in a granular cap. Large membrane-bound "yolk bodies" are arranged along the length of the carrier sperm, on either side of the median axonemal core. Dense bodies, which may be indigestible residues formed from the degeneration of the nucleus, are excreted by exocytosis. Individual carrier sperm are capable of "corkscrew" propulsion, resembling that of spirochaetes. The lancet sperm is three times as long as the carrier. The sixteen or so axonemes, which are arranged peripherally like a cage enclosing the cytoplasm, originate from a dense centriolar plate in the anterior end. The cytoplasm is filled with secretions including small yolk granules, dense bodies (also excreted), clear vesicles, and a membranated granular secretion that resembles mucus. The possible functions of the lancet and carrier sperm are discussed.

Acrosome↗
PubMed1982

Detection of sacroiliac injury by bone scanning in fractures of the pelvis and its clinical significance.

Fifteen patients with stable pelvic fractures were investigated by technetium bone scanning of the pelvis and subsequently reviewed to study their recovery from this injury. Eleven of these patients had a significantly raised uptake of isotope over the ipsilateral sacroiliac joint suggesting a bone injury in this region, probably as a result of micro-avulsion fractures. All patients, with one exception, made a full recovery from their fractures within 4 months. We conclude from this that the region of the sacroiliac joint is frequently injured in isolated fractures of the pubic rami, but in the short term this has a good prognosis.

Adolescent↗
PubMed1982

Long-term treatment of osteoporosis with 24,25 dihydroxycholecalciferol.

Five patients with involutional osteoporosis were treated with 24,25 dihydroxycholecalciferol (24,25-(OH)2D3) for 6 months, in doses sufficient to double plasma levels at that time. Dietary calcium absorption transiently improved by nearly 2 mmol Ca per day at 2 weeks, but this effect was lost by 6 months. The calcium and phosphate balances followed the trends in calcium absorption. Only twenty-five dihydroxyvitamin D levels changed little. Histomorphometric and kinetic indices of new bone formation and bone blood flow remained stable but there was an increase in urine hydroxyproline at 6 months, which was of borderline statistical significance. Treatment at this dosage of 24,25(OH)2D3, which increased plasma levels within the physiological range, conferred no measurable long-term benefit on our patients. Larger doses, or combination therapy, may warrant further clinical evaluation in osteoporosis.

24,25-Dihydroxyvitamin D 3↗
PubMed1981

Pulmonary mast cells in cattle and ilamas at high altitude.

The density of mast cells in various anatomical locations within the lung were measured in a peruvian Andean llama, a Peruvian Andean cow and a sea-level-cow. These densities were determined separately around pulmonary arteries, pulmonary veins, pulmonary arterioles and venules, in the alveolar septa, and around bronchi. The total mast cell density did not differ significantly between the three animals and there were more periarteriolar and perivenular mast cells in the llama than in either of the two cows. These data do not support the hypothesis that the perivascular mast cell is responsible for initiating the vasopressor response to hypoxia. In fact it can be argued that they actually inhibit this response since a high mast cell density was found in the llama, and animal which does not develop pulmonary hypertension at high altitude.

Altitude↗