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Biomedical subjects

J M Davis

Publications and source records attributed to J M Davis.

At least 127 records · Page 7Linked to original sources
PubMed1997

Surgical infections and prophylactic antibiotics: 341 consecutive cases of gallbladder surgery in the era of laparoscopic surgery.

HYPOTHESIS: This study was undertaken to assess the use of prophylactic antibiotics (PA) in laparoscopic and open cholecystectomy with respect to the postoperative infection rate and the established criteria for PA use. METHODS: A total of 341 consecutive cases for 1994 were retrospectively analyzed. PA use was deemed appropriate if the patient: was over 70 years of age, had common duct stones, jaundice, or acute cholecystitis. RESULTS: The infection rate of patients having an open cholecystectomy was significantly greater than the laparoscopic group (12.9% versus 1.8%, p < .001). In the laparoscopic group of patients who met the criteria for PA and received PA there were no infections as compared with those who had criteria for but did not receive PA (0% versus 22%, p < .05). Only 27% of all elective cholecystectomy patients received cefazolin while 73% of patients received extended spectrum antibiotics. CONCLUSIONS: In 63.2% of patients antibiotics were used with no indication for PA. In 73% of patients, an extended spectrum drug was used when a less expensive and narrower spectrum agent would have sufficed. Open cholecystectomy has a significantly higher infectious rate than closed cholecystectomy.

Antibiotic Prophylaxis↗
PubMed1997

Carbohydrate supplementation affects blood granulocyte and monocyte trafficking but not function after 2.5 h or running.

This randomized, double-blind, placebo-controlled study was designed to determine the influence of carbohydrate supplementation on the granulocyte and monocyte response to 2.5 h of high-intensity running [76.7 +/- 0.4% of maximal oxygen consumption (VO2max)]. Thirty experienced marathon runners (VO2max 53.4 +/- 1.0 mL.kg-1.min-1, age 41.5 +/- 1.4 y) were randomly assigned to carbohydrate-supplement (n = 17) and placebo (n = 13) groups. Subjects rested for 10-15 min before a blood sample was taken at 0715, and then ingested 0.75 L carbohydrate beverage or placebo. At 0730 subjects began running at 75-80% of VO2max for 2.5 h, and drank 0.25 L carbohydrate or placebo fluid every 15 min. Immediately after the 2.5-h run (1000), another blood sample was taken, followed by 1.5-h, 3-h, and 6-h recovery samples. Carbohydrate supplementation had a significant effect compared with placebo on the pattern of change in plasma glucose and cortisol, and the blood concentration of neutrophils (F[14, 112] = 5.13, P = 0.001) and monocytes (F[14, 112] = 4.78, P = 0.001), but not on blood granulocyte and monocyte phagocytosis or oxidative burst activity after 2.5 h of intensive running.

Adult↗
PubMed1997

Possible mechanisms of central nervous system fatigue during exercise.

Fatigue of voluntary muscular effort is a complex phenomenon. To date, relatively little attention has been placed on the role of the central nervous system (CNS) in fatigue during exercise despite the fact that the unwillingness to generate and maintain adequate CNS drive to the working muscle is the most likely explanation of fatigue for most people during normal activities. Several biological mechanisms have been proposed to explain CNS fatigue. Hypotheses have been developed for several neurotransmitters including serotonin (5-HT; 5-hydroxytryptamine), dopamine, and acetylcholine. The most prominent one involves an increase in 5-HT activity in various brain regions. Good evidence suggests that increases and decreases in brain 5-HT activity during prolonged exercise hasten and delay fatigue, respectively, and nutritional manipulations designed to attenuate brain 5-HT synthesis during prolonged exercise improve endurance performance. Other neuromodulators that may influence fatigue during exercise include cytokines and ammonia. Increases in several cytokines have been associated with reduced exercise tolerance associated with acute viral or bacterial infection. Accumulation of ammonia in the blood and brain during exercise could also negatively effect the CNS function and fatigue. Clearly fatigue during prolonged exercise is influenced by multiple CNS and peripheral factors. Further elucidation of how CNS influences affect fatigue is relevant for achieving optimal muscular performance in athletics as well as everyday life.

Animals↗
PubMed1997

Carbohydrate affects natural killer cell redistribution but not activity after running.

This randomized, double-blind, placebo-controlled study was designed to determine the influence of carbohydrate supplementation on the natural killer cell response to 2.5 h of high-intensity running (76.7 +/- 0.4% VO2max). Thirty experienced marathon runners (VO2max 53.4 +/- 1.0 mL x kg[-1] x min[-1], age 41.5 +/- 1.4 yr) were randomized into carbohydrate supplement (N = 17) and placebo (N = 13) groups. Subjects rested for 10-15 min before a blood sample at 0715, and then ingested 0.75 L of carbohydrate beverage (Gatorade) or placebo. At 0730, subjects began running at 75-80% VO2max for 2.5 h and drank 0.25 L of carbohydrate or placebo fluid every 15 min. Immediately after the 2.5 h run (1000), another blood sample was taken, followed by 1.5 h, 3 h, and 6-h recovery samples. Carbohydrate supplementation versus placebo had a significant effect on the pattern of change in glucose, cortisol, and the blood concentration of natural killer cells ([F (4,25) = 3.79, P = 0.015], but not natural killer cell activity following 2.5 h of intensive running.

Adult↗
PubMed1997

A two-phase, double-blind randomized study of three haloperidol plasma levels for acute psychosis with reassignment of initial non-responders.

To clarify the plasma level/therapeutic response relationship of haloperidol (HPDL) we used a prospective double-blind design in 95 acutely psychotic patients. After drug washout, patients were randomly assigned to a low, middle or high plasma level range for 2 weeks (phase A), and then 50% of the initial non-responders were randomly reassigned into the putative therapeutic range for an additional 2 weeks (phase B). There were no significant differences in clinical outcome between the three plasma level ranges in phase A. However, in phase B initial non-responders displayed greater improvement in the middle range than in the low or the high ranges. No further benefit was observed when plasma levels were raised to or maintained in the high range.

Acute Disease↗
PubMed1997

Vitamin C supplementation does not alter the immune response to 2.5 hours of running.

This randomized, double-blind, placebo-controlled study was designed to determine the influence of vitamin C supplementation on the immune response to 2.5 hr of high-intensity running. Twelve experienced marathon runners (VO2 max 51.6 +/- 1.5 ml.kg-1.min-1, age 40.5 +/- 2.0 years) were randomized into vitamin C (1,000 mg/day for 8 days) or placebo groups. On the test day, subjects ran at 75-80% VO2 max for 2.5 hr, with five blood samples taken before and for 6 hr after. Blood samples were analyzed for cortisol and catecholamines; leukocyte subsets; interleukin-6; natural killer cell activity; lymphocyte proliferation as induced by concanavalin A, phytohemagglutinin, and pokeweed mitogen; and granulocyte phagocytosis and activated oxidative burst. Compared with placebo, vitamin C supplementation had no significant effect on the pattern of change in any of these hormonal or immune measures following 2.5 hr of intensive running.

Adult↗
PubMed1997

Carbohydrate drinks delay fatigue during intermittent, high-intensity cycling in active men and women.

The effects of ingesting carbohydrate drinks on fatigue during intermittent, high-intensity cycling in men and women were determined. Physically active but untrained women (n = 7) and men (n = 9) completed one practice trial and two experimental sessions separated by 1 week. Sessions consisted of repeated 1-min cycling bouts on a bicycle ergometer at 120-130% VO2max separated by 3 min rest until fatigue. Carbohydrate (CHO) or placebo (P) beverages (4 ml.kg body weight-1) were ingested immediately before exercise (18% CHO) and every 20 min during exercise (6% CHO). Plasma glucose and insulin were higher, RPE for the legs was lower, and time to fatigue was longer in CHO than P. Men's and women's responses were not different for any variable measured. These data suggest a beneficial role of CHO drinks on performance of intermittent, high-intensity exercise in men and women.

Adult↗
PubMed1997

Helcococcus kunzii as sole isolate from an infected sebaceous cyst.

Helcococcus kunzii was isolated in pure culture from pus drained from an infected sebaceous cyst associated with marked cellulitis. The cyst was excised one month later after the inflammation had subsided with flucloxacillin treatment. This is the first report of the isolation of H. kunzii as the sole pathogen from an infected site.

Adult↗
PubMed1997

Recombinant human superoxide dismutase reduces lung injury caused by inhaled nitric oxide and hyperoxia.

We previously demonstrated that 48 h of 100 ppm inhaled nitric oxide (NO) and 90% O2 causes surfactant dysfunction and pulmonary inflammation in mechanically ventilated newborn piglets. Because peroxynitrite (the product of NO and superoxide) is thought to play a major role in the injury process, recombinant human superoxide dismutase (rhSOD, a scavenger of superoxide) might minimize this insult. Four groups of newborn piglets (1-3 days of age) were ventilated with 100 ppm NO and 90% O2 for 48 h. Piglets received no drug, 5 mg/kg rhSOD intratracheally at time 0, 5 mg/kg rhSOD intratracheally at 0 and 24 h, or 10 mg/kg rhSOD by nebulization at time 0. At 48 h, bronchoalveolar lavage (BAL) was performed, and lung tissue was analyzed for markers of inflammation, oxidative injury, acute lung injury, and surfactant function. There were significant differences between rhSOD-treated piglets and untreated controls with respect to BAL neutrophil chemotactic activity, cell counts, and protein concentration as well as lung tissue malondialdehyde concentrations. Minimum surface tension of BAL surfactant from all groups studied was increased, with no differences found among groups. These data suggest that rhSOD, at the doses used, mitigated the inflammatory changes, oxidative damage, and acute lung injury from exposure to 100 ppm NO and 90% O2 but did not appear to improve surfactant function. This has important clinical implications for infants treated with hyperoxia and NO for neonatal lung disorders.

Administration, Inhalation↗
PubMed1997

Carbohydrate and the cytokine response to 2.5 h of running.

This randomized, double-blind, placebo-controlled study was designed to determine the influence of 6% carbohydrate (C) vs. placebo (P) beverage ingestion on cytokine responses (5 total samples over 9 h) to 2.5 h of high-intensity running (76.7 +/- 0.4% maximal O2 uptake) by 30 experienced marathon runners. For interleukin-6 (IL-6), a difference in the pattern of change between groups was found, highlighted by a greater increase in P vs. C immediately postrun (753 vs. 421%) and 1.5 h postrun (193 vs. 86%) [F(4,112) = 3.77, P = 0.006]. For interleukin-1-receptor antagonist (IL-1ra), a difference in the pattern of change between groups was found, highlighted by a greater increase in P vs. C 1.5 h postrun (231 vs. 72%) [F(2,50) = 6.38, P = 0.003]. No significant interaction effects were seen for bioactive IL-6 or IL-1 beta. The immediate postrun plasma glucose concentrations correlated negatively with those of plasma cortisol (r = -0.67, P < 0.001); postrun plasma cortisol (r = 0.70, P < 0.001) and IL-6 levels (r = 0.54, P = 0.003) correlated positively with levels of IL-1ra. Taken together, the data indicate that carbohydrate ingestion attenuates cytokine levels in the inflammatory cascade in response to heavy exertion.

Adult↗
PubMed1997

Exercise, alveolar macrophage function, and susceptibility to respiratory infection.

The effects of exercise on susceptibility to respiratory infection were determined by using a murine model of intranasal challenge with herpes simplex type 1 virus (HSV-1). Two doses of treadmill exercise were assessed: moderate short-term (30 min) exercise and prolonged strenuous exercise to voluntary fatigue (2.5-3.5 h). Morbidity and mortality among exercised and control mice were compared after intranasal challenge with HSV-1. We also assessed the ability of alveolar macrophages to restrict HSV-1 viral replication (intrinsic resistance) among exercise and control groups of mice at several time points postexercise. Exercise to fatigue followed by exposure to viral infection resulted in greater morbidity and mortality than either no exercise or short-term moderate exercise. In addition, antiviral resistance of macrophages obtained from the lungs of both exercised groups was suppressed, albeit for a longer duration in the fatigued group. These data are particularly important in that they identify an exercise-induced decrease in antiviral resistance of a specific component of the immune system within the lungs, in conjunction with increased susceptibility to respiratory infection in vivo. The specific mechanism of decreased antiviral resistance of alveolar macrophages and its role in respiratory infection after exercise remains to be determined.

Administration, Intranasal↗
PubMed1997

Acute dietary tryptophan depletion: effects on schizophrenic positive and negative symptoms.

Because brain serotonin levels depend directly on the amounts of exogenous tryptophan (TRP) available for its synthesis, amounts of TRP in the diet may be manipulated to alter the corresponding levels of serotonin. This technique has been used for probing the role of serotonin in mediating various forms of pyschopathology. In this study, 16 patients meeting DSM III-R criteria for schizophrenia (n = 14) or schizoaffective disorder (n = 2) were assessed for the effects of acute dietary TRP depletion under controlled conditions. The hypothesis was that lowering of serotonin would result in a diminution of 'positive' and/or 'negative' symptoms of psychotic disorders. No clinically or statistically significant improvement compared to baseline occurred when TRP depletion was imposed. Indeed, there was a statistically significant deterioration on measures of negative symptoms. The results are discussed in the context of the methodological issues.

Adult↗
PubMed1997

DST studies in psychotic depression: a meta-analysis.

OBJECTIVE: Although hypersecretion of cortisol has frequently been reported in psychotic depression, the findings have been mixed. The authors performed a meta-analysis of the existing studies to determine the significance of differences in nonsuppression of cortisol across studies. METHOD: Fourteen studies that compared dexamethasone suppression test (DST) results in psychotic and nonpsychotic patients were examined, and a Mantel-Haenszel meta-analysis was performed. For comparison purposes, 19 studies of the DST with respect to melancholic/nonmelancholic and inpatient/outpatient distinctions were similarly reviewed. RESULTS: This analysis indicated a highly significant probability that a greater rate of cortisol nonsuppression occurs in psychotic depression. The nonsuppression rate was substantially higher in patients with psychotic depression (64%) than in nonpsychotic patients (41%). In the 19 studies of melancholia, nonsuppression was less frequent (36%), and when inpatient/outpatient status was controlled, melancholic depression was not significantly associated with nonsuppression. In nonmelancholic outpatients with major depression, the nonsuppression rate was low (12%). CONCLUSIONS: Among patients with major depression, psychotic depression is the subtype that is most closely associated with nonsuppression of cortisol on the DST. Hypercortisolemia is usually present in psychotic depression and may be important in understanding the pathophysiology of this syndrome.

Ambulatory Care↗
PubMed1997

Engraftment and molecular monitoring of CD34+ peripheral-blood stem-cell transplants for follicular lymphoma: a pilot study.

PURPOSE: A pilot study to validate the use of CD34+ selection (Ceprate SC) of blood stem-cell collection in patients with advanced follicular lymphoma receiving myeloablative chemoradiotherapy. PATIENTS AND METHODS: Seventeen patients were entered onto the protocol. Thirteen of 17 patients have undergone transplantation; the median age is 42.5 years (range, 33 to 51), seven of 13 are stage IVB, two stage IVA, three stage IIIB, and one stage IIB. All except two patients were treated after first or subsequent relapses after receiving cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) chemotherapy to achieve a good partial (six of 13) or complete (seven of 13) response before stem-cell mobilization with cyclophosphamide 3 g/m2 and filgrastim 300 microg once daily. RESULTS: Eleven of 13 patients had a detectable t(14;18) by nested polymerase chain reaction (PCR). Median CD34+ count before selection was 2.9 x 10(6)/kg (range, 1.17 to 11.3) and after CD34+ selection was 1.54 x 10(6)/kg (range, 0.88 to 7.6) with a median CD34+ yield of 62.4% (range, 17% to 95%) and purity of 60% (range, 39.3% to 73%). Of the 11 patients known to have t(14;18), 10 had PCR-detectable contamination of stem-cell harvests that became PCR negative in six of the 10 after CD34+ selection. Engraftment was rapid with a median day to absolute neutrophil count (ANC) greater than 0.5 x 10(9)/L of 13 days (range, 11 to 21) and platelet count greater than 20 x 10(9)/L of 14 days (range, 10 to 44). With a median follow-up duration of 15 months, three patients have remained persistently PCR-positive, two of whom received PCR-positive stem cells. Two have relapsed. Of the seven patients who received PCR-negative stem cells, five have had no PCR-detectable disease in posttransplant bone marrow samples. CONCLUSION: Longer follow-up duration is required to determine the significance of these findings, but we have confirmed the feasibility of CD34+ selected cells to deplete peripheral-blood stem cells of tumor cells from patients undergoing high-dose therapy for follicular lymphoma.

Adult↗
PubMed1997

Short-term inhalation and in vitro tests as predictors of fiber pathogenicity.

A wide range of fiber types was tested in two in vitro assays: toxicity to A549 epithelial cells, as detachment from substrate, and the production of the proinflammatory cytokine tumor necrosis factor (TNF) by rat alveolar macrophages. Three of the fibers were also studied in vivo, using short-term inhalation followed by a) bronchoalveolar lavage to assess the inflammatory response and b) measurement of cell proliferation in terminal bronchioles and alveolar ducts, using incorporation of bromodeoxyuridine (BrdU). The amount of TNF produced by macrophages in vitro depended on the fiber type, with the man-made vitreous fibers, and refractory ceramic fibers being least stimulatory and silicon carbide (SiC) whiskers providing the greatest stimulation. In the epithelial detachment assay there were dose-dependent differences in the toxicity of the various fibers, with long amosite being the most toxic. However, there was no clear relationship to known chronic pathogenicity. Fibers studied by short-term inhalation produced some inflammation, but there was no clear discrimination between the responses to code 100/475 glass fibers and the more pathogenic amosite and SiC. However, measurements of BrdU uptake into lung cells showed that amosite and SiC produced a greater reaction than code 100/475, which itself caused no more proliferation than that seen in untreated lungs. These results mirror the pathogenicity ranking of the fibers in long-term experiments. In conclusion, the only test to show potential as a predictive measure of pathogenicity was that of cell proliferation in lungs after brief inhalation exposure (BrdU assay). We believe that this assay should be validated with a wider range of fibers, doses, and time points.

Administration, Inhalation↗