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Biomedical subjects

R Meyers

Publications and source records attributed to R Meyers.

At least 37 records · Page 2Linked to original sources
PubMed1994

Untying the elderly. 1989 to 1993 update.

Research and public policy pertaining to the use of physical restraints has advanced since Evans' and Strumpfs' 1989 review. Research better delineates the harms caused by restraints, although not finding benefits. Federal law sharply restricts the use of restraints. Legal liability weighs against the use of restraints in most instances. Nursing homes have published substantial experience with programs to reduce and eliminate the use of physical restraints.

Decision Making↗
PubMed1993

Release of elastase from monocytes adherent to a fibronectin-gelatin surface.

Fibronectin (Fn) is a circulating and extracellular matrix glycoprotein that may serve to facilitate phagocytosis because of its ability to bind many inflammatory ligands and to a monocyte receptor. Fn fragments have been shown in many systems to have augmented properties over those of native Fn. We show in this report that although Fn fragments did not cause elastase release from monocytes in suspension, fragments did cause elastase release from monocytes that were first bound to Fn-gelatin surfaces. An amino-terminal 29-Kd and a 140-Kd integrin-binding fragment were half-maximally active at 100 nmol/L, whereas the Arg-Gly-Asp-Ser integrin-recognition peptide was half-maximally active at 100 mumol/L. Fluid-phase Fn was ineffective yet blocked the activity of the Fn fragments. Complexing of Fn with gelatin or with heparin partially removed the blocking effect of Fn. Similar results were obtained with U-937 cells. Substitution of the Fn-gelatin surface with bovine articular cartilage also promoted elastase release. Therefore, in conditions in vivo in which monocytes bind to tissue surface, a high ratio of Fn fragments to native Fn may upregulate certain monocyte activities such as protease release.

Amino Acid Sequence↗
PubMed1993

Mineral balance and bone turnover in adolescents with anorexia nervosa.

We evaluated seven female adolescents with anorexia nervosa to determine whether calcium metabolism was affected by their disorder. We measured calcium absorption, urinary calcium excretion, and calcium kinetics, using a dual-tracer, stable-isotope technique during the first weeks of an inpatient nutritional rehabilitation program. Results were compared with those from a control group of seven healthy adolescent girls of similar ages. The percentage of absorption of calcium was lower in subjects with anorexia nervosa than in control subjects (16.2% +/- 6.3% vs 24.6% +/- 7.2%; p < 0.05). Urinary calcium excretion was greater in subjects with anorexia nervosa than in control subjects (6.4 +/- 2.5 vs 1.6 +/- 0.7 mg.kg-1 x day-1; p < 0.01) and was associated with bone resorption rather than calcium hyper-absorption. Calcium kinetic studies demonstrated a decreased rate of bone formation and an increased rate of bone resorption. These results suggest marked abnormalities in mineral metabolism in patients with anorexia nervosa. From these results, we hypothesize that improvement in bone mineralization during recovery from anorexia nervosa will require resolution of hormonal abnormalities, including hypercortisolism, in addition to increased calcium intake.

Absorption↗
PubMed1993

Intraarticular injection of fibronectin fragments causes severe depletion of cartilage proteoglycans in vivo.

We have reported that fibronectin fragments (Fn-f) cause cartilage damage in vitro by causing enhanced release of proteases. In order to determine whether the Fn-f can damage cartilage in vivo, we have injected native fibronectin (Fn) and Fn-f into adolescent rabbit knee joints. After 7 days, tissue was analyzed by histochemical and biochemical techniques and remaining proteoglycans quantified. Injection of 0.6 or 3 microM Fn-f caused up to a 70% loss in total cartilage proteoglycan while native Fn, rabbit serum albumin or an Arg-Gly-Asp-Ser synthetic peptide, derived from the cell-binding domain of Fn, did not cause damage. Our results suggest that this Fn-f/damage model may be useful for generating cartilage damage in vivo for other studies. Since Fn-f have been detected in synovial fluids from joints of patients with rheumatoid arthritis and osteoarthritis, our results are consistent with the notion that Fn-F mediated damage may occur in vivo.

Animals↗
PubMed1992

Fibronectin fragments cause chondrolysis of bovine articular cartilage slices in culture.

Elevated fibronectin (Fn) and Fn fragment concentrations are found in the synovial fluid of osteoarthritic and rheumatoid arthritic patients. Fn has been shown to affect expression of chondrocytic matrix proteins, and Fn fragments have been shown to elevate gene expression of neutral proteinases in synoviocytes. For these reasons, we tested the effects of Fn fragments on protease release and resultant proteoglycan release from cartilage in serum-free bovine articular cartilage explant cultures. We have found that 1 microM amino-terminal 29- and 50-kDa gelatin-binding Fn fragments caused over a 50-fold enhancement of gelatinolytic and collagenolytic proteinase release with a 23-fold enhancement of proteoglycan (PG) release. Release was significant at fragment concentrations as low as 20 nM. An integrin-binding 140-kDa fragment mixture was the least active fragment, whereas native Fn had little activity. The relative activities of the fragments correlated with their relative abilities to bind to cartilage. The RGDS integrin-recognition peptide also caused release, although sequence mutants did not. PG release was blocked by actinomycin D, cycloheximide, and deoxyglucose. Fn fragment-mediated PG release was decreased in 10% serum by over 10-fold but was still 2-fold greater than in controls. In the presence of insulin-like growth factor-1, PG release was as great as without serum. We suggest that Fn fragments, as found in diseased synovial fluid, may contribute to protease-mediated damage to cartilage.

Animals↗
PubMed1992

Efficacy of preprocedural rinsing with an antiseptic in reducing viable bacteria in dental aerosols.

This double-blind, controlled, cross-over, clinical study evaluated the effect of preprocedural rinsing with an antiseptic mouthrinse on the level of recoverable viable bacteria in an aerosol generated during a typical dental procedure. Eighteen subjects participated. Following 24 hours of abstention from all oral hygiene procedures, subjects received a 10-minute ultrasonic scaling of a randomly selected one-half of their mouth which served as the unrinsed control. They were then randomly assigned either antiseptic mouthwash or a control rinse and rinsed with 20 ml for 30 seconds, after which the remaining half mouth (experimental side) was scaled ultrasonically for 10 minutes. During each 10-minute scaling period aerosolized bacteria were collected on a sterile filter using a modified vacuum air-sampling device. Microbes captured on the sterile filter were quantitated by overlaying the filters onto trypticase soy agar, incubating the filters aerobically at 37 degrees C for 24 to 72 hours, and counting the resulting colony forming units (CFU). Preliminary experiments had confirmed that neither the collection method nor residual antiseptic mouthwash in the aerosol adversely affected the number of viable bacteria recovered from the filter. Rinsing with the antiseptic mouthwash produced a 94.1% reduction in recoverable CFUs compared to the non-rinsed control, while the control rinse produced a 33.9% reduction. The difference between the mouthwash and control was statistically significant (P < .001). This study indicates that preprocedural rinsing with an antiseptic mouthwash can significantly reduce the microbial content of aerosols generated during ultrasonic scaling and may have potential in-office use as part of an infection control regimen.

Adult↗
PubMed1992

Isolation and characterization of an abundant elastase inhibitor from NaCl extracts of bovine nasal septa and articular cartilage.

Extracts of cartilage have been reported to inhibit many serine proteinases and metalloenzymes. Such inhibition may be important in protecting cartilage against degradation by chondrocytic proteinases such as collagenase, stromelysin and by leukocytic proteases, such as elastase. We report here isolation and partial characterization of a 17-kD elastase inhibitor from 0.5 M NaCl extracts of both nasal septum cartilage and articular cartilage, which inhibits elastase and represents 0.08% of the weight of nasal cartilage and 0.002% of the weight of articular cartilage. The protein was highly specific for elastase and did not inhibit cartilage metalloproteinases, suggesting that it may be mainly directed toward protecting cartilage against leukocytic proteases. The inhibitor had a blocked amino-terminus, was high in serine and glycine and lacked carbohydrate. The ease with which the inhibitor was extracted from cartilage suggests that it may function in vivo as a highly abundant elastase inhibitor which is secreted into synovial fluid from cartilage. The inhibitor was shown to be synthesized by bovine articular cartilage in explant culture and nearly all of the metabolically labeled material was secreted into the culture media. The inhibitor cross-reacted with polyclonal antibodies to bovine neck ligament alpha-elastin and antibodies to the inhibitor reacted with bovine neck ligament elastin. The properties of this inhibitor are different than those of any other reported cartilage derived inhibitor.

Amino Acids↗
PubMed1992

Amino acid gradients across the intestinal circulation in fetal lambs.

Amino acids, including glutamine, glutamate and asparagine are major metabolic substrates for the adult enterocyte of several species. To determine whether circulating amino acids are utilized by the fetal intestine, we studied nine fetal sheep (mean gestational age 128 +/- 5 days; term: 147 days). Catheters were inserted into the descending aorta (DA) and the mesenteric vein (MV) to allow for simultaneous blood sampling across the intestine. Fetal blood gas, haemoglobin; O2 saturation and O2 tension were measured. Ammonia was determined by an enzymatic method and HPLC analysis was used to measure the content of all amino acids in DA (descending aorta) and MV (mesenteric vein). Intestinal blood flow measurements were obtained using the radionuclide microsphere method. Intestinal blood flow (81 +/- 28 ml/min/100g) and arterial pH (7.37 +/- 0.04) were within normal range for unstressed fetal lambs. Glutamine and glutamate were the only amino acids that were significantly taken up across the fetal intestinal circulation. The fetal intestine extracted approximately 21% of the delivered glutamine (6.8 +/- 4.5 mumol/min/100g), 7% of the delivered glutamate (1.3 +/- 1.1 mumol/min/100g) and 2.7% of the delivered oxygen (43.0 +/- 19.1 mumol/min/100g). These data suggest that glutamine and glutamate are major substrates for the intestine in unstressed fetal lambs.

Alanine↗
PubMed1992

Fibronectin fragments in osteoarthritic synovial fluid.

Fibronectin is an adhesive multifunctional glycoprotein found in the extracellular matrix of most types of cells and that exerts growth factor, differentiative and chemotactic activities toward many types of cells, including those cells found in knee joint tissue. Since fibronectin levels in the synovial fluid (SF) and on the cartilage surface of patients with osteoarthritis (OA) have been shown to be greatly increased over normal levels and since protease levels are also enhanced in diseased cartilage, we have investigated the presence of fibronectin fragments in the SF of patients with OA. We report that concentrations of at least 1 microM of 100 to 200 kDa fragments were found in all OA fluids examined. Since we have recently shown that fibronectin fragments can cause cartilage to release metalloproteinases, resulting in severe proteoglycan depletion, and others have shown that fragments also enhance metalloproteinase expression in synovial fibroblasts, the presence of these fragments suggests pathologic consequences in arthritis.

Cartilage↗
PubMed1991

[Acute corticosteroid myopathy in patient with asthma].

A patient, treated by mechanical ventilation with pancuronium or atracurium and with intravenously administered corticosteroid for status asthmaticus, presented with rhabdomyolysis (severe amyotrophy and marked of creatine kinase activity) and acute flacid and areflexic quadriplegia, involving the proximal and distal muscles but sparing the cephalic musculature. After review of the investigations (biochemistry, electromyogram, muscle biopsy), the diagnostic of acute corticosteroid myopathy following status asthmaticus was suggested, and a pancuronium neuromuscular complication or a critically ill polyneuropathy excluded. The non-inflammatory rhabdomyolysis concerned all the fiber types. Predominantly distal weakness resolved six months after the insult, in spite of the laboratory recurrence of the rhabdomyolysis at the time of a new status asthmaticus briefly treated with corticosteroid.

Acute Disease↗
PubMed1989

Coombs-positive autoimmune hemolytic anemia in ulcerative colitis.

Coombs-positive autoimmune hemolytic anemia is a rare complication of ulcerative colitis, occurring in fewer than 1% of cases. We have found eight patients with autoimmune hemolytic anemia in a series of 1150 hospitalized patients with ulcerative colitis (0.7%). There was a marked preponderance of female patients F:M = 7:1, in accord with previous reports. The hemolytic anemia appeared at a mean of 10 years after the onset of colitis, apparently independent of the age of the patient. Although seven of the eight patients had active colitis at the time of diagnosis of anemia, there was no consistent relationship to the extent of the bowel disease. Seven of the eight patients survived. One patient showed a partial response to steroid therapy, two responded to splenectomy, but four required both colectomy and splenectomy. Steroids should be the first line of therapy followed by splenectomy, if necessary. For those patients who have severe colitis, which in itself would merit surgery, a total proctocolectomy combined with splenectomy seems advisable.

Adolescent↗
PubMed1988

Effects of bromocriptine and ectopic pituitary transplants on pituitary and hypothalamic nuclear androgen receptors in the male hamster.

Nuclear androgen receptors (ARN) were measured in the pituitaries and hypothalami of adult male golden hamsters which had been injected with a long-acting preparation of bromocriptine or had pituitaries from adult females transplanted under the renal capsules. Treatment with bromocriptine markedly reduced pituitary ARN and plasma prolactin levels without altering plasma testosterone levels or hypothalamic ARN. Ectopic pituitary transplants did not affect ARN in either the pituitary or the hypothalamus. These findings suggest that normal rates of prolactin synthesis and/or secretion may be required for maintenance of ARN in the pituitary of adult male hamsters.

Animals↗