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Biomedical subjects

R M Williams

Publications and source records attributed to R M Williams.

At least 127 records · Page 7Linked to original sources
PubMed1990

Specific binding of sulphated polymers to ram sperm proacrosin.

Sulphated polysaccharides and zona pellucida glycoproteins have been shown to bind non-enzymatically to proacrosin, the protein found within the acrosomal vesicle of mammalian spermatozoa. The mechanism of this interaction has been investigated using 125I-fucoidan to probe purified ram sperm proacrosin. Results show that (a) binding of 125I-fucoidan to proacrosin is inhibited only by sulphated polymers and (b) recognition is mediated by poly(sulphate) groups and is largely independent of the composition of the polymer chain. It is suggested that a similar mechanism is responsible for the interaction between proacrosin and zona pellucida glycoproteins during the early stages of fertilization in mammals and this process mediates firm binding of spermatozoa to the egg.

Acrosin↗
PubMed1990

Motivational syndromes associated with natural killer cell activity.

This article reports three studies that taken together support two hypotheses: (a) that the stressed power motivation syndrome is associated with relatively low natural killer cell activity (NKCA) and (b) that the unstressed affiliation motivation syndrome is associated with higher NKCA. In Study 1, college students who were relatively high in stressed power motivation had significantly lower NKCA than did their peers. In addition, students high in unstressed affiliation motivation had significantly greater NKCA than did those showing less evidence of this syndrome. Study 2 replicated these findings on a sample of middle-class men. In Study 3, which tested the hypotheses among adult patients from a Health Maintenance Organization, results were in the same direction but less significant. Meta-analyses clearly indicate that the combined evidence from the three studies reliably supports both hypotheses.

Adult↗
PubMed1990

Genetics of survival in mice: subregions of the major histocompatibility complex.

In this study of murine survival, 422 F1 hybrids between DBA/2J (D2) female mice and C57BL/10 (B10) background H-2 congenic male mice (11 strains), 88 F1 hybrids between B10 female mice and B10 background H-2 congenic male mice (3 strains), and 532 control mice from the 11 parental B10 background H-2 congenic mice were bred over a period of 2 yr. Toward the end of the breeding period there was documentation of Sendai infection in the mouse rooms. All analyses were done separately for the two sexes. Although it did not appear that an unusually high number of mice died during the time the colony was infected with Sendai, there was a highly significant tendency for mice who were younger at the time of the Sendai infection to have shorter survival than mice who were older at that time point. The effect of birth date on survival was approximately as significant as the effect of strain on survival. Hence all analyses of genetic effects on survival were either done within subsets of mice born in the same quarter of a particular year or else included date of birth variables in survival models. Of the 18 possible comparisons of pairs of strains which overlapped in birth dates and differed only in the D end of H-2, five were associated with highly significant survival differences. Of the 11 pairs of strains which overlapped in birth date and differed only in the K end of H-2, none was associated with significant survival differences.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1990

Angiotensin and salt appetite of BALB/c mice.

The influence of systemic or intracerebroventricular (icv) administration of angiotensin II on the intakes of NaCl solution, water, and food was investigated in BALB/c mice. Systemic administration of angiotensin II had little, if any, influence on these ingestive behaviors. On the other hand, icv infusion of angiotensin II at 70 ng/day increased (P less than 0.05) intakes of NaCl solution and water by the third day of infusion. The amount of NaCl ingested daily during the infusion was two to three times body sodium content. The mean daily water intake increased to 40-60% of body weight. The vast increase in NaCl intake was not secondary to a natriuresis caused by the icv infusion of angiotensin II. The results suggest that angiotensin II has a direct effect on neural systems involved in sodium appetite in this species.

Angiotensin II↗
PubMed1990

Effect of angiotensin-converting enzyme inhibitor on salt appetite and thirst of BALB/c mice.

The role of angiotensin II (ANG II) in Na-depletion-induced Na appetite of mice was investigated. Intraperitoneal injection of the angiotensin-converting enzyme inhibitor captopril at 1.7 mg/mouse (high dose) decreased the Na intake of the Na-depleted (furosemide-treated) mice by 80-85%. The decrease in Na intake was restored to the initial level by concurrent subcutaneous infusion of ANG II. High dose of captopril also decreased the Na intake of fluid-deprived, Na-depleted mice. High dose of captopril did not alter water intake in any of the four conditions examined, i.e., in fluid-replete, Na-depleted, water-deprived, or fluid-deprived, Na-depleted mice. Low dose of captopril (1.7 microgram/mouse) tended to or significantly enhanced Na intake of Na-depleted mice. Low dose of captopril, however, did not enhance water intake in any of the conditions examined. Both high- and low-dose captopril treatment decreased food intake in water-deprived mice, whether or not the mice were Na depleted as well. The addition of captopril (0.1 or 1.0 mg/ml) to the drinking water did not influence Na or food intake. Water intake was enhanced during treatment with the low but not with the high dose of captopril. The results are consistent with the proposition that ANG II is involved in the Na appetite of Na-depleted mice. ANG II does not appear to have a role in water intake of Na-depleted or water-deprived mice, but neural mechanisms in which angiotensin has a role may influence food intake of water-deprived mice.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1990

Decreased cerebral sodium concentration and sodium appetite in BALB/c mice.

BALB/c mice were allowed free access to water, food, and 0.3 M NaCl. Intracerebroventricular infusion of 0.7 M mannitol in artificial cerebrospinal fluid (CSF) was used to reduce CSF sodium concentration. The infusion was made at 24 microliters/day, which was similar on a body weight basis to the rate that evoked a large increase in sodium appetite in sheep. Reduction of CSF sodium concentration did not increase the voluntary sodium intake of sodium-replete mice or furosemide-treated, sodium-depleted mice. Thus, in contrast to findings in sheep and cattle and similar to the findings in the laboratory rat and wild rabbits, changes in cerebral sodium concentration are apparently not involved in the sodium appetite of mice.

Animals↗
PubMed1990

Identification of zona- and fucoidan-binding proteins in guinea-pig spermatozoa and mechanism of recognition.

Binding of guinea-pig spermatozoa to the zona pellucida of homologous eggs has been reported to involve 'receptors' on the inner acrosomal membrane (Huang et al. 1981). These receptors can be blocked by sulphated polysaccharides such as fucoidan (Huang and Yanagimachi, 1984). The aims of the present investigation were to identify these putative zona receptors using 125I-fucoidan as a probe and examine their mechanism of recognition. Results show that 125I-fucoidan binds to several proteins extracted from guinea-pig spermatozoa with molecular masses of 95, 60, 48, 34, 30 and 18-20 x 10(3) (K) on SDS-PAGE. The 48K, 34K and 30K components represent proacrosin and two forms of acrosin, respectively. 125I-zona pellucida glycoproteins also bound strongly to the 48K, 34K and 30K sperm proteins. The other high and low mass binding proteins were not positively identified but cytochemical experiments with fluoresceinamine-fucoidan and FITC-soybean trypsin inhibitor indicate that they are intraacrosomal. The mechanism of binding of 125I-fucoidan to proacrosin/acrosin (and also the 95K, 60K and 18K-20K components) involves multiple sulphate groups on the polysaccharide in a specific orientation to allow them to interact with basic residues on the protein. It is suggested that guinea-pig spermatozoa retain sufficient proacrosin/acrosin bound to the inner acrosomal membrane after the acrosome reaction to mediate binding to the zona pellucida and that functionally proacrosin is analogous to sea urchin binding.

Acrosin↗
PubMed1987

Multicenter trial of sucralfate suspension for the treatment of reflux esophagitis.

The efficacy of sucralfate suspension in the treatment of reflux esophagitis was assessed in a multicenter, randomized, double-blind, placebo-controlled trial. Sixty-eight patients with symptomatic and endoscopic esophagitis received either sucralfate suspension (n = 31) or liquid placebo (n = 37) for eight weeks. The two groups were comparable at entry with the exception that despite randomization, a disproportionately high number of patients with esophageal ulcers were assigned to receive sucralfate. After four and eight weeks of treatment, both groups had reduced heartburn frequency and severity, but there was no difference in improvement between sucralfate and placebo (p greater than 0.05). Endoscopic results after eight weeks of sucralfate treatment revealed complete healing in 36 percent (placebo, 35 percent) and improvement in an additional 45 percent (placebo, 24 percent). Although neither of these differences was significant, the percent of patients in whom healing or improvement occurred with sucralfate (81 percent) was greater than with placebo (59 percent) (p = 0.07). These data fail to establish that eight weeks of treatment with sucralfate suspension improves symptoms or heals lesions in reflux esophagitis at a rate significantly greater than placebo. However, the unequal distribution of patients with ulcers and the trend toward endoscopic improvement indicate that a potential beneficial effect of sucralfate suspension for the treatment of reflux esophagitis cannot be excluded.

Clinical Trials as Topic↗
PubMed1987

T-cell mitogenesis and natural killer cell activity in colonic tumor-bearing and nontumor-bearing rats fed diets high in lipid with and without cholesterol.

It has been shown that rats fed diets high in lipid and cholesterol develop more 1,2-dimethylhydrazine (DMH)-induced bowel tumors than those fed diets low in lipid or without cholesterol. To further explore the effects of these dietary regimens on immune function, rats were fed diets containing 20% safflower or coconut oil, with or without cholesterol (1%) and cholic acid (0.3%), for 35 weeks during which time they were given DMH. Only rats bearing one or more colon tumors and that showed no evidence of weight loss were utilized. Two parameters of cell-mediated immune function were assessed in tumor- and nontumor-bearing control rats: a) response to the T-cell mitogen, phytohemaglutinin (PHA), and b) natural killer cell activity (NKCA). Nearly total suppression of PHA response was observed in the polyunsaturated fat diet group compared with the saturated fat diet groups. Addition of cholesterol to either the polyunsaturated or saturated fat diets diminished PHA response and, to a lesser degree, of T-lymphocytes from rats fed these diets. NKCA, however, was unaffected by either the quality of dietary fat or cholesterol. There were no detectable effects of DMH per se 15 weeks after the last injection (or in the presence or absence of tumors) on T-lymphocyte response to PHA or on NKCA. The relationships among lipid nutrition, carcinogen-induced tumorigenesis, and immunologic events is obviously complex. These studies imply that nutritional interventions may have a selective rather than a generalized effect on various immunocompetent cell populations. Furthermore, the effects of lipid nutriture, rather than long-term effects of carcinogen administration, or the presence of bowel tumors appear to play the major role on perceived alterations in in vitro immune function. Thus the effects of these lipid nutritional interventions on DMH-induced tumorigenesis seem independent of their effects on immune phenomena with the immune probes utilized.

1,2-Dimethylhydrazine↗
PubMed1987

Financial and contractual considerations.

Emergency physicians function in a highly competitive and financially oriented environment. To remain professionally and economically viable in this situation, it is imperative that individual emergency physicians and emergency physician groups develop and maintain a thorough understanding of the aspects of emergency department finance and contractual relationships. Otherwise, emergency physicians run the considerable risk of becoming controlled and therefore being "minor players" in the burgeoning health care industry.

Accounting↗
PubMed1986

Choice reaction time performance in hospitalized schizophrenic patients and depressed patients.

The choice reaction time performances of matched groups of hospitalized patients diagnosed schizophrenic or depressed were compared with normal controls to test a hypothesis concerning thought disorder specific to schizophrenia. Both patient groups were abnormal compared to controls providing evidence inconsistent with the diagnostic specificity issue. The results are discussed in terms of cognitive dysfunction in depression, the effects of institutionalization and the problems of diagnostic heterogeneity.

Adult↗
PubMed1986

Natural killer cell activity and MMPI scores of a cohort of college students.

Natural killer (NK) cells are important in immune function and appear, in part, to be regulated by the CNS. The authors compared NK cell activity and MMPI scores of 111 healthy college students and found weak but statistically significant correlations between NK values and psychopathology for 10 of 12 scales. Students with the highest NK values had a "healthier" MMPI profile than those with the lowest. Students with high MMPI scores (T greater than 70) had NK values below the sample median. These findings support theories of interaction between mental state and immune status, but the mechanisms and direction of interaction remain largely unexplored.

Adolescent↗
PubMed1986

Influence of cisplatin on wound healing--an experimental model.

Recent clinical studies have shown that adjuvant chemotherapy may improve response rates to treatment for advanced head and neck carcinomas. Given preoperatively, some chemotherapeutic agents adversely affect wound healing. The specific purpose of this study was to evaluate the influence of cisplatin on wound healing when it is given preoperatively. Forty-four Swiss outbred mice were divided into control and treatment groups. One week before surgery, the treatment group received cisplatin (2 mg/kg body weight) by subcutaneous injections on 2 consecutive days. Each control animal was given an equal volume of normal saline. A 1.5 cm transverse incision was made in each animal, and wounds were closed with surgical staples. The mean wound-breaking strength was determined for a minimum of 5 treatment and 5 control mice on postoperative days 6, 10, 13, and 16. Serum creatinine, blood cell counts, and changes in weight were also monitored. Results showed wound strength on postoperative day 10 to be significantly reduced in mice treated with cisplatin (P less than 0.05). There was no significant difference for wound strength on any other days and all other variables were similar between both groups. In conclusion, cisplatin has an adverse effect on wound healing, the peak of which probably occurs during the proliferative stage of wound healing. Further studies are needed to determine the optimal time for surgery after preoperative chemotherapy. All new chemotherapeutic agents, particularly those being considered in a preoperative regimen, should be tested in this manner.

Analysis of Variance↗