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Biomedical subjects

D A Smith

Publications and source records attributed to D A Smith.

At least 181 records · Page 10Linked to original sources
PubMed1992

Epidemiology of reported sharps injuries in a tertiary care hospital.

Over a 12-month period 233 puncture wounds were reported in a 1112-bed tertiary medical care centre. Accident forms were reviewed to determine the epidemiology of puncture injuries. The nursing department accounted for the majority of all puncture injuries (68%). For nurses, medical and surgical units represented those clinical areas with the greatest number of puncture injuries. Areas with the highest incidence rates, however, included the clinical research centre, the emergency room, the surgical intensive care unit and areas where the intravenous team operated. Activities involving direct contact of a sharp instrument with a patient accounted for the majority of puncture injuries. Disposable syringes and loose needles were implicated in 50% of injuries although the incidence of injury per individual's low (3.2 out of 100,000 purchased). Recommendations include the redesigning of sharp instruments and the focusing of education programmes to target personnel for whom incidence rates are the highest.

Academic Medical Centers↗
PubMed1992

Model of the Ca2+ oscillator for shuttle streaming in Physarum polycephalum.

We propose a mechanism for the cytoplasmic Ca++ oscillator which is thought to power shuttle streaming in strands of the slime-mold Physarum polycephalum. The mechanism uses a phosphorylation-dephosphorylation cycle of myosin light chain kinase. This kinase is bistable if the kinase phosphorylation chain, through adenylate cyclase and cAMP, is activated by calcium. Relaxation oscillations can then occur if calcium is exchanged between the cytoplasm and internal vacuoles known to exist in physarum. As contractile activity in physarum myosin is inhibited by calcium, this model can give calcium oscillations 180 degrees out of phase with actin filament tension as observed. Oscillations of ATP concentration are correctly predicted to be in phase with the tension, provided the actomyosin cycling rate is comparable with ATPase rates for phosphorylation of the myosin light chain and its kinase.

Adenosine Triphosphatases↗
PubMed1992

Effect of mydriasis on visual field area in retinitis pigmentosa.

PURPOSE: The effect of mydriasis on Goldmann visual field area in patients with retinitis pigmentosa has not been suitably defined. The aim of this study is to determine whether visual field area in these patients varies with pharmacologic mydriasis. METHODS: Fifteen adult patients with retinitis pigmentosa were studied prospectively. Goldmann visual fields with II4e and V4e isopters were obtained in both eyes before and after full pharmacologic mydriasis of the right eye. The isopter areas were quantified and analyzed to determine the effect of mydriasis on visual field area. RESULTS: The difference in the right eye isopter areas was compared with the difference in the left eye isopter areas using paired t tests, where the differences were computed from areas obtained before and after dilation of the right eye. Mydriasis had no significant effect on the visual field in terms of isopter area difference (II4e, P = 0.87; V4e, P = 0.45) and percent change in isopter area (II4e, P = 0.81; V4e, P = 0.24). CONCLUSION: Pharmacologic mydriasis had no appreciable effect on the Goldmann visual field area in a selected group of patients with retinitis pigmentosa. These findings suggest that visual fields of such patients obtained in the dilated or undilated state can be meaningfully compared.

Adult↗
PubMed1992

Is admission after intravenous heroin overdose necessary?

STUDY OBJECTIVES: To investigate the time of onset and incidence of complications in patients presenting to the emergency department with an IV heroin overdose and the need for routine admission of such patients. METHODS: A retrospective chart review of hospital and emergency medical service records of 124 patient visits involving IV heroin overdose over a five-month period. We also reviewed the death certificates of 115 persons having succumbed to a narcotic overdose over a 44-month period and compared these with our hospital records. SETTING: Urban county hospital. TYPE OF PARTICIPANTS: Patients presenting to the ED with an IV heroin overdose. RESULTS: There were five deaths in the ED, 12 hospital admissions, and 107 patients who were discharged home. Neither delayed onset of pulmonary edema nor recurrence of respiratory depression was observed. Of the 115 persons having succumbed to a narcotic overdose, eight had been seen previously at our hospital for a heroin overdose. There is no evidence that any of these eight deaths would have been prevented by a 24-hour hospital observation period. CONCLUSION: Complications arising from an IV overdose of heroin are usually evident on arrival in the ED or shortly thereafter. On retrospective review we have found no evidence that admission to the hospital and 24 hours of observation are of benefit to patients who are awake, alert, and lacking evidence of pulmonary complications after an IV heroin overdose.

Adult↗
PubMed1992

Dialysis disequilibrium syndrome (DDS) in the rat: role of the "reverse urea effect".

DDS is characterized by neurologic deterioration and cerebral edema which occurs after hemodialysis. To investigate the pathogenesis of DDDS, we studied the effects of rapid hemodialysis on plasma and brain electrolytes, urea, and osmolality in the rat. Forty-two hours after bilateral nephrectomy, nine uremic rats were hemodialyzed for 90 minutes against dialysate without urea (model of DDS), yielding a decrease in plasma urea from 72 +/- 2 mM to 34 +/- 2 mM (P less than 0.01) and an 8% (29 mOsm/kg) decrease in plasma osmolality. This group was compared to three control groups: 11 uremic animals dialyzed against a bath with urea added so that no fall in plasma urea occurred, and 15 uremic and 12 nonuremic animals that were not dialyzed. In animals dialyzed without urea, compared to uremic non-dialyzed animals, there was a 6% increase in brain water (3.89 +/- 0.04 liter/kg dry wt vs. 3.67 +/- 0.03, P less than 0.01) and an increase in the brain to plasma (urea) ratio (1.30 +/- 0.06 vs. 0.79 +/- 0.05, P less than 0.01). Comparison of these parameters in animals dialyzed without urea versus other control groups yielded similar results. In animals dialyzed without urea, the 53% decrease in plasma urea was associated with only a 13% decrease in brain urea content. Brain content of sodium and potassium was not significantly different among groups. Retention of brain urea despite the large decrease in plasma urea was able to account for the increased brain water observed in animals dialyzed without urea.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Fleroxacin pharmacokinetics in patients with liver cirrhosis.

In this open-label study, the disposition of fleroxacin in liver disease in 12 healthy male volunteers, 6 male cirrhotics without ascites (group A), and 6 male cirrhotics with ascites (group B) was evaluated. Fleroxacin (400 mg) was administered orally and intravenously to each subject in a random crossover fashion. Fleroxacin was completely absorbed and achieved similar peak concentrations in plasma in all three study groups (P greater than 0.05). The volume of distribution exceeded 1 liter/kg in healthy controls and was not affected by liver impairment (P greater than 0.05). Only group B demonstrated differences in the pharmacokinetic parameters evaluated: the systemic and renal clearances of fleroxacin and the renal clearances and clearances of the two major metabolites of fleroxacin formed, N-demethyl fleroxacin and fleroxacin N-oxide, were significantly lower and the half-lives of the parent drug and its metabolites were significantly longer in group B than in healthy controls and group A (P less than 0.05). The elimination of the two metabolites appeared to be formation rate limited in all three study groups. It was concluded from this study that a 50% reduction in the fleroxacin maintenance dose in patients with liver disease appears justified only in patients with ascites. However, no change in the fleroxacin loading dose is needed in patients with compromised liver function.

Administration, Oral↗
PubMed1992

The efficacy of ergogenic agents in athletic competition. Part I: Androgenic-anabolic steroids.

OBJECTIVE: To summarize the literature describing the epidemiology, pharmacology, efficacy, and adverse effects associated with androgenic-anabolic steroid (AAS) use among athletes. DATA SOURCES: Relevant articles were identified from a MEDLINE search using the search terms "Doping in Sports," "Anabolic Steroids (exploded)," and "Androgens (exploded)." Additional references were found in the bibliographies of these articles. STUDY SELECTION/DATA EXTRACTION: We reviewed studies of AAS use among professional athletes. Interpretation of these studies is difficult because of poor research design. The efficacy studies lacked adequate placebo control. Much of the literature describing adverse effects consists of anecdotal reports. All of this literature was considered for review. DATA SYNTHESIS: Of all ergogenic drugs, AASs are the most widely abused. Abuse of AASs among high school students is estimated at five to ten percent. AASs are hypothesized to produce ergogenic effects during periods of concomitant positive nitrogen balance via antagonism of the catabolic effect of glucocorticoids released during intense exercise. Despite years of study, the extent of the ergogenic effects associated with AASs remains unclear. This may be because most studies have failed to approximate athletes' AAS usage patterns. The primary toxic effects of AASs are divided into four areas: hepatic, reproductive, cardiovascular, and psychiatric. Athletes do not consider these effects severe enough to refrain from using these drugs. CONCLUSIONS: Athletes view AASs as an essential component for success. Without adequate intervention measures, AAS abuse is likely to continue unchecked.

Anabolic Agents↗
PubMed1992

The efficacy of ergogenic agents in athletic competition. Part II: Other performance-enhancing agents.

OBJECTIVE: To summarize the literature describing the epidemiology, pharmacology, efficacy, and adverse effects associated with growth hormone (GH), caffeine, aerobic metabolism facilitator (AMF), and sympathomimetic use among athletes. DATA SOURCES: Relevant articles were identified from a MEDLINE search using the search terms "Doping in Sports," "Blood," "Caffeine," "Cocaine," "Erythropoietin," "Somatotropin," and "Sympathomimetics (exploded)." Additional references were found in bibliographies of these articles. STUDY SELECTION/DATA EXTRACTION: We reviewed studies of ergogenic drug (ED) use among athletes. Interpretation of these studies is difficult because of poor research design and the paucity of information available. This necessitated the inclusion of many anecdotal or conjectural reports in our review. DATA SYNTHESIS: There are no studies documenting an ergogenic effect associated with GH use in humans or animals. It is still unknown whether GH abuse causes adverse effects in healthy adults, although GH-induced acromegaly has been suspected. Amphetamines, cocaine, and caffeine are thought to improve performance via enhanced concentration among athletes. Amphetamines and cocaine may increase aggressiveness. The ergogenic effects of other sympathomimetics including ephedrine and phenylpropanolamine are unclear. AMFs (e.g., blood doping, epoetin) enhance aerobic metabolism and endurance by increasing the oxygen-carrying capacity of the blood. Risks associated with excessive AMF use include increased blood viscosity and clotting. CONCLUSIONS: Athletes view EDs as an essential component for success. Without adequate intervention measures, ED abuse is likely to continue unchecked.

Amphetamines↗
PubMed1992

Nonneuroleptic treatment of disruptive behavior in organic mental syndromes.

OBJECTIVE: To summarize the literature describing nonneuroleptic treatments of unacceptably disruptive behavior in chronically institutionalized psychiatric patients with mental retardation, autism, organic brain syndrome, and dementia. DATA SOURCES: Relevant articles were identified from a MEDLINE search of the above diagnoses linked with "aggression" and "psychomotor agitation." Additional references were found in the bibliographies of these articles. STUDY SELECTION/DATA EXTRACTION: The studies reviewed were limited to prospective evaluations of nonneuroleptic drug therapy of these behavior disturbances. Case reports, case series, and retrospective studies were excluded. Studies of patients with schizophrenia, affective disorders, and personality disorders were also excluded. DATA SYNTHESIS: Studies of lithium, beta-blockers, carbamazepine, benzodiazepines, and buspirone were adequate for review. As a rule, these studies are hampered by poor design. The lithium studies suggest that mentally retarded patients with behavior disturbances may respond to lithium treatment. The beta-blocker studies suggest improvement in patients with mental retardation, autism, organic brain syndrome, and dementia. Neuroleptic discontinuation or a decrease in dose was possible in some patients. The carbamazepine studies were inconclusive. Carbamazepine should be reserved for patients with concomitant seizure disorders. Benzodiazepines were helpful in treating elderly demented patients. Thus far, buspirone has been evaluated in only a few, poorly designed studies and is not yet recommended for treatment of behavior disturbances. CONCLUSIONS: Legislation has restricted the use of neuroleptics in many patients receiving long-term healthcare. Despite the questionable validity of the studies reviewed, lithium, beta-blockers, carbamazepine, and benzodiazepines may be considered as alternatives to neuroleptics in selected cases.

Adrenergic beta-Antagonists↗
PubMed1992

Pharmacokinetics and metabolism of dofetilide in mouse, rat, dog and man.

1. Pharmacokinetics of dofetilide were studied in man, dog, rat and mouse after single i.v. and oral doses of dofetilide or 14C-dofetilide. 2. Dofetilide was absorbed completely in all species. Low metabolic clearance in man resulted in complete bioavailability following oral administration. Higher metabolic clearance in rodents, and to a lesser extent dogs, resulted in decreased bioavailability because of first-pass metabolism. 3. Following i.v. administration, the volume of distribution showed only moderate variation in all species (2.8-6.3 l/kg). High plasma clearance in rodents resulted in short half-life values (mouse 0.32, male rat 0.5 and female rat 1.2 h), whilst lower clearance in dog and man gave longer terminal elimination half-lives (4.6 and 7.6 h respectively). 4. After single i.v. doses of 14C-dofetilide, unchanged drug was the major component excreted in urine of all species with several metabolites also present. 5. Metabolites identified in urine from all species were formed by N-oxidation or N-dealkylation of the tertiary nitrogen atom of dofetilide. 6. After oral and i.v. administration of 14C-dofetilide to man, parent compound was the only detectable component present in plasma and represented 75% of plasma radioactivity. No single metabolite accounted for greater than 5% of plasma radioactivity.

Administration, Oral↗
PubMed1992

Role of metabolism and pharmacokinetic studies in the discovery of new drugs--present and future perspectives.

1. The impact which pharmacokinetics and drug metabolism studies have made to drug discovery programmes is reviewed with examples from the anti-infective, cardiovascular, anti-inflammatory and CNS therapeutic areas. 2. Contributions that advances in analytical technology have made to the early application of pharmacokinetics and drug metabolism are discussed. 3. Some future perspectives are given on the advances being made in basic science and technology and how this will provide the basis for further growth in the contribution to the drug discovery process.

Animals↗
PubMed1992

A comparison of four methods of estimating the body composition of male endurance athletes.

Comparisons were effected of the following four methods of estimating the percent body fat (%BF) of 12 highly trained male endurance athletes (mean +/- SD = 2.20 +/- 4.9 years, 176.8 +/- 5.9 cm 64.2 +/- 6.4 kg): underwater weighing (UWW), total body water (TBW), total body potassium (TBK) and dual-energy X-ray absorptiometry (DEXA). The DEXA mean of 6.8% BF was significantly less (P < 0.05) than those estimated via UWW: 9.7% BF; TBW: 10.6% BF (fat-free mass of FFM = 72.0% H2O); and TBK: 9.7% BF (FFM = 66.6 mmol K.kg-1). Nevertheless, the DEXA % BF correlated 0.746 and 0.737 (both P < 0.01) with those from UWW and TBW, respectively; these were the only correlation coefficients to attain statistical significance (P < or = 0.05). Despite the similar means for UWW, TBW and TBK, 12 of the 36 individual differences between these three methods ranged from 3.2 to 10.4% BF. A critical assumption of UWW, which is regarded by many as the criterion method for the estimation of % BF, is that the FFM has a density of 1.100 g.cm-3. Use of in vivo-measured TBW and bone mineral (via DEXA) for the computation of FFM densities for our subjects, while assuming that the two other components of the FFM (protein and non-bone mineral) remained constant, resulted in scores ranging from 1.09541 to 1.10246 g.cm-3 (mean +/- SD = 1.09881 +/- 0.00254 g.cm-3). FFM and % BF differences between use of a constant FFM density of 1.100 g.cm-3 and the individual values ranged from -1.02 to 0.57 kg (mean +/- SD = -0.28 +/- 0.60 kg) and from -0.9 to 1.7% BF (mean +/- SD = 0.5 +/- 0.9% BF), respectively. It may be concluded that with young male athletes: (1) use of constants based on normal male cadavers yielded similar group means for % BF determined by UWW, TBW and TBK but the DEXA % BF correlated significantly with those from UWW and TBW; and (2) in vivo measurements of individual differences in TBW and bone mineral support the use of conventional UWW for the estimation of % BF.

Absorptiometry, Photon↗
PubMed1992

Endothelin does not affect experimentally induced corneal neovascularization.

Endothelin, a potent vasoconstrictor, was found to be ineffective in the treatment of experimentally induced corneal neovascularization. Endothelin was administered topically, subconjunctivally, and intraluminally in serial concentrations ranging from 0.0005 to 5.0 micrograms/mL in New Zealand white rabbits without effect. Electron microscopy of the neovascular cornea revealed the vessels consisted only of endothelin and pericytes. Hence, the vessels were not responsive to endothelin because they lacked contractile smooth muscle.

Animals↗
PubMed1992

Atrial myocytes cultured from explanted human adult myocardium demonstrate DNA replication.

The current theory of myocardial development holds that after a limited number of divisions, the myocardiocytes of the developing heart are irreversibly withdrawn from the generation cycle. It is, therefore, considered impossible to grow adult human myocardiocytes in culture, making it necessary for studies of cardiac muscle in culture to be carried out using animal or fetal human models. Recently, we developed a method for isolating, culturing, and characterizing myocardiocytes derived from explanted adult human atrial myocardium. A highly pure fraction (93%) of one of four morphologically discrete cell populations was separated using selective attachment techniques. These cells possessed features consistent with those seen in animal and fetal myocardiocytes. Using immunoperoxidase stains, these cells stained positive for actin, myoglobin, and atrial natriuretic peptide, proving the cells are myocardial muscle cells. Electron microscopy showed numerous bundles of myofibrils with interspersed dense Z-bodies and pleomorphic mitochondria. Bromo-deoxyuridine incorporation confirmed that the cells were replicating their DNA. Thus, cell morphology, immunoperoxidase stains, electron microscopy, and cell proliferation testing showed these cells to be myocardiocytes undergoing DNA replication and mitosis. We must now reconsider our current thinking about myocardial development and investigate what factors contribute to the inhibition of myocardial cell proliferation after injury in vivo.

Bacteriological Techniques↗
PubMed1992

Pelvic muscle reeducation as a nursing treatment for incontinence.

Pelvic muscle reeducation is a safe, effective, conservative therapy for patients with UI. The success of the method depends on the proper selection of patients and the active participation of a cooperative patient. However, it is of limited use in patients with cognitive impairment. Methods exist to assist the nurse in pelvic muscle reeducation.

Exercise Therapy↗
PubMed1992

The Yankton Model Program.

Changes in medical education towards a student-centered, problem-based learning, with continuity care experience in ambulatory settings have been recommended. The University of South Dakota School of Medicine has developed such an educational model for third year medical students named the Yankton Model Program and is herein described.

Curriculum↗