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Biomedical subjects

S Barrett

Publications and source records attributed to S Barrett.

At least 37 records · Page 2Linked to original sources
PubMed1999

Metformin attenuates salt-induced hypertension in spontaneously hypertensive rats.

Metformin, an antihyperglycemic agent used for treatment of type 2 diabetes mellitus, lowers blood pressure in humans and experimental animals. We recently demonstrated that short-term administration of metformin may lower blood pressure by reducing sympathetic neural outflow. The present studies were initiated to determine whether long-term administration of metformin blunts salt-induced hypertension, a condition characterized by elevated sympathetic activity. Male spontaneously hypertensive rats, in which radiotelemeters had been implanted for continuous monitoring of heart rate and blood pressure, were randomly assigned to groups that received vehicle (drinking water) or metformin (500 mg/kg per day) and ate a normal 0.3% NaCl diet and to groups that received vehicle or metformin and ate a high 8.0% NaCl diet for a period of 4 weeks. Although metformin did not affect blood pressure in the animals that ate the normal-salt diet (vehicle, 130+/-3 mm Hg; metformin, 133+/-5 mm Hg; mean+/-SEM), drug treatment blunted the rise in pressure caused by a high-salt diet (vehicle, 153+/-4 mm Hg; metformin, 140+/-5 mm Hg; P<0.001). In agreement, during direct pressure recordings in anesthetized rats, the animals that ate the high-salt diet had higher pressures (136+/-13 mm Hg) than those in the control (98+/-5 mm Hg, P<0.01), metformin (100+/-7 mm Hg, P<0.01), and metformin/high-salt groups (92+/-3 mm Hg, P<0.01). Finally, metformin lowered heart rate in rats that ate the normal- and high-salt diets (310+/-3 and 305+/-4 bpm) compared with rats that ate normal- and high-salt diets given vehicle (332+/-3 and 324+/-2 bpm, P<0.01). These data indicate that the chronic depressor actions of metformin are enhanced in animals with hypertension exacerbated by a high-salt diet.

Animals↗
PubMed1999

Microtubule nucleating capacity of centrosomes in tissue sections.

We used a novel adaptation of methods for microtubule polymerization in vitro to assess the MTOC activity of centrosomes in frozen-sectioned tissues. Remarkably, centrosomes of tissue sections retain the ability to nucleate microtubules even after several years of storage as frozen tissue blocks. Adaptations of these methods allow accurate counts of microtubules from individual cells and the quantitative estimation the MTOC activity of the intact tissue. These methods can be utilized to characterize MTOC activity in normal and diseased tissues and in particular tissues at different stages of development. (J Histochem Cytochem 47:1265-1273, 1999)

Adenocarcinoma↗
PubMed1998

Attention-deficit hyperactivity disorder and the stress response.

BACKGROUND: Attention-deficit hyperactivity disorder (ADHD) is a developmental disorder whose three main symptoms are impulsiveness, inattention, and hyperactivity. Researchers have proposed that the central deficit in ADHD is one of poor response inhibition. The present studies were designed to look at the functioning of the hypothalamic-pituitary-adrenal (HPA) axis in response to mental stress in aggressive ADHD subjects participating in a longitudinal study of various psychosocial treatments. METHODS: Pretest and posttest morning salivary samples for cortisol determination were collected from subjects given a battery of tests. RESULTS: The study shows that ADHD subjects who maintained their diagnosis over the first year of the study had a blunted response to the stressor in comparison to those ADHD subjects who no longer retained the disorder 1 year later. CONCLUSIONS: The data suggest that an impaired response to stress may be a marker for the more developmentally persistent form of the disorder.

Aggression↗
PubMed1998

A close look at therapeutic touch.

CONTEXT: Therapeutic Touch (TT) is a widely used nursing practice rooted in mysticism but alleged to have a scientific basis. Practitioners of TT claim to treat many medical conditions by using their hands to manipulate a "human energy field" perceptible above the patient's skin. OBJECTIVE: To investigate whether TT practitioners can actually perceive a "human energy field." DESIGN: Twenty-one practitioners with TT experience for from 1 to 27 years were tested under blinded conditions to determine whether they could correctly identify which of their hands was closest to the investigator's hand. Placement of the investigator's hand was determined by flipping a coin. Fourteen practitioners were tested 10 times each, and 7 practitioners were tested 20 times each. MAIN OUTCOME MEASURE: Practitioners of TT were asked to state whether the investigator's unseen hand hovered above their right hand or their left hand. To show the validity of TT theory, the practitioners should have been able to locate the investigator's hand 100% of the time. A score of 50% would be expected through chance alone. RESULTS: Practitioners of TT identified the correct hand in only 123 (44%) of 280 trials, which is close to what would be expected for random chance. There was no significant correlation between the practitioner's score and length of experience (r=0.23). The statistical power of this experiment was sufficient to conclude that if TT practitioners could reliably detect a human energy field, the study would have demonstrated this. CONCLUSIONS: Twenty-one experienced TT practitioners were unable to detect the investigator's "energy field." Their failure to substantiate TT's most fundamental claim is unrefuted evidence that the claims of TT are groundless and that further professional use is unjustified.

Humans↗
PubMed1998

Attachment of gelatin films to tissue using argon beam coagulator.

Cross-linked gelatin films were bonded to heart muscle and to lung pleura and parenchyma using the electrical discharge of an argon beam radiofrequency coagulator. The bonds were stable in warm saline buffer for minutes to hours. Bonding was thought to partly occur through a mechanical interlock of film and tissue elements. The interdigitation of tissue and film arose during exposure to the argon beam, which denatured protein constituents of both, and created a fluidized state that rapidly coalesced.

Animals↗
PubMed1998

Psychiatric and psychological morbidity as a function of adaptive disability in preschool children with aggressive and hyperactive-impulsive-inattentive behavior.

Children with high levels of aggressive-hyperactive-impulsive-inattentive behavior (AHII; n = 154) were subdivided into those with (n = 38) and without (n = 116) adaptive disability (+AD/-AD) defined as a discrepancy between expected versus actual adaptive functioning. They were compared to each other and a control group of 47 normal children. Both AHII groups were more likely to have attention deficit hyperactivity disorder (ADHD), oppositional defiant disorder, and conduct disorder than control children; more symptoms of general psychopathology; greater social skills deficits; more parental problems; and lower levels of academic achievement skills. Compared to AHII - AD children, AHII + AD children had (1) more conduct disorder; (2) greater inattention and aggression symptoms; (3) more social problems, less academic competence, and poorer self-control at school; (4) more severe and pervasive behavior problems across multiple home and school settings; and (5) parents with poorer child management practices. Thus, adaptive disability has utility as a marker for more severe and pervasive impairments in AHII children.

Achievement↗
PubMed1998

Evaluation of PCR for diagnosis of melioidosis.

Previously published PCR-based diagnostic tests for melioidosis were evaluated for clinical usefulness. A Burkholderia pseudomallei 16S rRNA-derived primer set had a sensitivity approaching 100% for clinical samples from 22 culture-confirmed cases of melioidosis and enabled diagnosis of 3 culture-negative cases. However, samples from 10 of 30 inpatients from Royal Darwin Hospital with other diagnoses were positive by PCR, giving a specificity of 67% and a positive predictive value of only 70%. Although there are a number of intriguing possible explanations for our results, concerns of inappropriate therapy resulting from a positive result by PCR have led us to forgo the advantage of rapid PCR diagnosis for melioidosis until a better system is validated.

Humans↗
PubMed1997

Clostridium difficile colitis after aortic surgery.

OBJECTIVE: To determine the incidence and outcome of Clostridium difficile colitis (CDC) following aortic surgery. DESIGN: Retrospective clinical study, and case-note review. PATIENTS: Of 180 patients undergoing aortic surgery for either aneurysmal or occlusive disease between 1 September 1994 and 31 August 1996 (24 months), 15 (8.4%) developed CDC. There were 12 male and three female patients of median age 65 (range 46-84). RESULTS: Two patients died from multiple organ failure in association with CDC, one of whom underwent negative relaparotomy for suspected ischaemic bowel because the diagnosis of CDC had not been entertained. Previously identified risk factors for CDC comprised: age > 65 (eight); renal impairment (four); chronic obstructive airways disease (seven); coexistent malignancy (three); admission from another hospital (four); H2 antagonist therapy (13); ITU (nine); and/or HDU care (14). Diarrhoea commenced a median of 9 (range 5-26) days, and CDC, was diagnosed a median of 14 (range 10-26) days after operation. All patients received intravenous Cefuroxime, originally prescribed as prophylaxis, for a median of 6 (range 3-16) days prior to onset of CDC. Two patients received 1 additional antibiotic; one received 2; two received 3; and one received 4 prior to onset of CDC. CONCLUSIONS: CDC is a common and potentially serious complication of vascular, and in particular, aortic surgery. Although such patients often possess several risk factors for CDC, colitis frequently follows prolonged 'prophylactic' cephalosporin administration, which should therefore be avoided.

Aged↗
PubMed1997

Toxin production by Burkholderia pseudomallei strains and correlation with severity of melioidosis.

An exotoxin lethal to cells in culture (cytolethal toxin, CLT) was identified in culture filtrates of Burkholderia pseudomallei, the causative organism of melioidosis. CLT could pass through a 10-kDa cut-off ultrafilter and its properties suggest that it is a peptide. Isolates from soil, animals and man showed differential cytolethality in vitro. The isolates were divided into low, medium and high CLT producers with soil isolates being low producers and isolates from patients with melioidosis encephalitis being high producers. CLT levels are subject to regulation, as a strain isolated from an infected goat was one of the highest producers whereas the same strain isolated from soil was a low producer. In addition to CLT, all isolates produced a protein with cell-elongating activity which was also present in culture filtrates.

Animals↗
PubMed1997

Surgical aspects of Clostridium difficile colitis.

BACKGROUND: There has been a marked increase in the number of surgical patients developing Clostridium difficile colitis. The epidemiology, pathogenesis, diagnosis and management of C. difficile infection were reviewed from a surgical perspective. METHODS: A literature review was carried out based primarily on a Medline search of all English language publications containing the term C. difficile. RESULTS: The recent dramatic increase in diagnosis of C. difficile infection amongst surgical patients results from heightened awareness of the condition, better methods of diagnosis, more widespread use of antibiotics for treatment and prophylaxis, and the increasing numbers of elderly and immunocompromised patients with malignancy, sepsis, and (multiple) organ failure being cared for within intensive therapy and high-dependency units. In addition to morbidity and mortality, the economic burden of C. difficile infection in terms of delayed discharge and other hospital costs is considerable. CONCLUSION: Appropriate use of antibiotics, isolation of affected patients and meticulous hygiene measures on the part of staff are vital if the morbidity, mortality and economic consequences of this nosocomial infection are to be minimized.

Antibiotic Prophylaxis↗
PubMed1995

With nurse practitioners, who needs house officers?

The boundaries between the work of doctors and that of nurses are changing, with nurses taking over important parts of junior hospital doctors' clinical work. In 1993 an exploratory study was carried out to identify the professional, educational, and management issues that such developments raise. Interviews were carried out with a range of stakeholders in three innovatory posts in which nurses were doing much of the clinical work of house officers. A complex picture of perceived benefits and problems for patients, junior doctors, and nurses emerged. These seemed to be associated with (a) the extent to which the contribution of professional nursing was valued in the new role and (b) the amount of clinical discretion which the postholder was allowed, this depending on the type of preparatory education provided and the management of the post. The study points to the need for strategic issues--such as the development of appropriate education and the professional recognition of these new clinical roles--to be addressed at a national and regional level.

Humans↗