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Biomedical subjects

H White

Publications and source records attributed to H White.

At least 55 records · Page 3Linked to original sources
PubMed1998

The association of weight change in Alzheimer's disease with severity of disease and mortality: a longitudinal analysis.

OBJECTIVE: To describe weight loss in relation to the severity of Alzheimer's disease (AD), to identify confounders that might account for weight loss, and to investigate the association of weight change with mortality. METHODS: This study included 666 subjects with AD from the Consortium to Establish a Registry for Alzheimer's Disease, a longitudinal study of subjects with AD studied for < or = 6 years. Body weight was measured on entry and at annual follow-up examinations as part of standardized clinical assessments. Hierarchical linear models were used to estimate weight change per change in stage of AD, as measured by the Clinical Dementia Rating scale, and to assess the impact of possible confounders on the tendency for weight loss. Linear correlation of the trajectories of weight and CDR over time were used to determine the association between weight change and stage change. The association between weight change and mortality was modeled using the Cox proportional hazards model. RESULTS: Each change in stage of AD was associated with an estimated average weight loss of nearly 2 lb (P = .0001). The correlation between change in stage of AD and weight change was statistically significant (r = -0.09, P = .005), which indicates a greater tendency toward weight loss with progression of AD. Weight loss of > or = 5% in any year before death was a significant predictor of mortality. When weight loss in the year before death or censoring was analyzed as a continuous variable, it was a significant predictor of mortality. Additionally, the relative risk of death increased as weight loss increased. In contrast, weight gain decreased the risk of mortality. CONCLUSION: The risk of weight loss tends to increase with severity and progression of AD. Weight loss is a predictor of mortality among subjects with AD, whereas weight gain appears to have a protective effect.

Aged↗
PubMed1997

Treatment of chronic hepatitis C with consensus interferon: a multicenter, randomized, controlled trial. Consensus Interferon Study Group.

This multicenter, randomized, controlled, double-blind, phase III study in 704 patients with chronic hepatitis C infection compared treatment with consensus interferon (CIFN), a non-natural recombinant type-1 interferon, with a standard regimen of recombinant interferon alfa-2b (IFN-alpha2b). Patients were randomized to receive CIFN at doses of 3 microg or 9 microg, or 15 microg IFN-alpha2b (3 million units), subcutaneously three times weekly for 24 weeks, followed by 24 weeks of observation. Efficacy was assessed by normalization of serum alanine transaminase (ALT) concentration and decrease in serum hepatitis C virus (HCV) RNA concentration below the limit of detection by reverse-transcription polymerase chain reaction (RT-PCR) (100 copies/mL). The beneficial effect of CIFN was greater with the 9-microg dose than the 3-microg dose. The sustained ALT and HCV RNA response rates were 20.3% and 12.1%, respectively, in the 9-microg CIFN cohort and 19.6% and 11.3%, respectively, in the 15-microg IFN-alpha2b cohort. However, patients receiving 9 microg of CIFN had a greater reduction in serum HCV RNA concentrations compared with patients receiving 15 microg IFN-alpha2b over the course of treatment (P < .01). Similarly, analysis of patients infected with HCV genotype 1 showed a greater reduction in serum HCV RNA concentration over the course of treatment for the 9-microg CIFN group when compared with the 15-microg IFN-alpha2b group (P < .01). In addition, a greater percentage of patients infected with HCV genotype 1 treated with 9 microg CIFN had undetectable HCV RNA concentrations when compared with patients in the 15-microg IFN-alpha2b cohort at the end of treatment (24% vs. 15%; P = .04). Improvements in liver histology were noted in all three treatment groups; 52% to 55% of the patients in the three cohorts had at least a 2-unit improvement in the Knodell score at the end of the posttreatment period. The adverse-events profiles were characteristic of treatment with type-1 interferon, and the incidences of anti-interferon antibody formation did not significantly differ among the three treatment groups. These results show that administration of 9 microg CIFN three times weekly for 6 months is safe and is effective in reducing serum HCV RNA concentration.

Adult↗
PubMed1997

Stress in mental health nursing: findings from the Mental Health Care survey.

Organisational and administrative concerns topped the list of stressors reported by a national sample of hospital and community mental health nurses. Seven of the ten top stressors were listed by both groups. Community nurses also listed inadequate service provision and lack of time to plan treatment. Hospital nurses were most stressed by inadequacy of staffing cover in potentially dangerous situations and low morale at work. Jerome Carson et al believe the findings indicate an urgent need for change at senior NHS management and administration level.

Adult↗
PubMed1996

The chaperonin ATPase cycle: mechanism of allosteric switching and movements of substrate-binding domains in GroEL.

Chaperonin-assisted protein folding proceeds through cycles of ATP binding and hydrolysis by the large chaperonin GroEL, which undergoes major allosteric rearrangements. Interaction between the two back-to-back seven-membered rings of GroEL plays an important role in regulating binding and release of folding substrates and of the small chaperonin GroES. Using cryo-electron microscopy, we have obtained three-dimensional reconstructions to 30 A resolution for GroEL and GroEL-GroES complexes in the presence of ADP, ATP, and the nonhydrolyzable ATP analog, AMP-PNP. Nucleotide binding to the equatorial domains of GroEL causes large rotations of the apical domains, containing the GroES and substrate protein-binding sites. We propose a mechanism for allosteric switching and describe conformational changes that may be involved in critical steps of folding for substrates encapsulated by GroES.

Adenosine Triphosphatases↗
PubMed1996

EPR and Mössbauer spectroscopic studies on enoate reductase.

Enoate reductase (EC 1.3.1.31) is a protein isolated from Clostridium tyrobutyricum that contains iron, labile sulfide, FAD, and FMN. The enzyme reduces the alpha,beta carbon-carbon double bond of nonactivated 2-enoates and in a reversible way that of 2-enals at the expense of NADH or reduced methyl viologen. UV-visible and EPR potentiometric titrations detect a semiquinone species in redox intermediate states characterized by an isotropic EPR signal at g = 2.0 without contribution at 580 nm. EPR redox titration shows two widely spread mid-point redox potentials (-190 and -350 mV at pH 7. 0), and a nearly stoichiometric amount of this species is detected. The data suggest the semiquinone radical has an anionic nature. In the reduced form, the [Fe-S] moiety is characterized by a single rhombic EPR spectrum, observed in a wide range of temperatures (4. 2-60 K) with g values at 2.013, 1.943, and 1.860 (-180 mV at pH 7.0). The gmax value is low when compared with what has been reported for other iron-sulfur clusters. Mössbauer studies reveal the presence of a [4Fe-4S]+2/+1 center. One of the subcomponents of the spectrum shows an unusually large value of quadrupole splitting (ferrous character) in both the oxidized and reduced states. Substrate binding to the reduced enzyme induces subtle changes in the spectroscopic Mössbauer parameters. The Mössbauer data together with known kinetic information suggest the involvement of this iron-sulfur center in the enzyme mechanism.

Binding Sites↗
PubMed1996

Management of acute myocardial infarction in Auckland.

AIM: To analyse the utilisation of therapies in coronary care units for patients with acute myocardial infarction. METHODS: An evaluation form was completed prospectively by a designated nurse in each coronary care unit of the four Auckland hospitals in 1993. RESULTS: One thousand and eighty one patients who were admitted with definite or probable acute myocardial infarction had a coronary care unit stay of 63.4 (SD 49.3) hours, and hospital stay of 7.3 (5.1) days. The mortality for definite myocardial infarction was 13.7% (< 70 years 7.1%). Coronary angiography was performed on 10% of patients during their hospital admission, and 4.9% underwent revascularisation. Thrombolytic therapy was administered to 52% (495/948) of patients with definite infarction and 4% had contraindications. Patients aged > or = 70 years (47% vs 55% p = 0.02) or diabetics (46% vs 56%, p = 0.04) were less likely to receive thrombolysis. The utilisation of aspirin and oral beta-blockers was 86% and 40%, respectively, in patients with definite infarction and both were used less frequently in patients > or = 70 years. Intravenous beta-blockers were administered to < 1% of patients. Angiotensin converting enzyme (ACE) inhibitors were prescribed in 21%, intravenous or long acting nitrates in 41% and calcium antagonists in 14%; the latter two therapies were used more frequently in patients > or = 70 years. There was no evidence of gender or ethnic bias for either investigation or treatment. CONCLUSION: On the basis of results of recent clinical trials, there may be under utilisation of some treatments for acute myocardial infarction including aspirin, thrombolytic therapy, beta-blockers and ACE inhibitors, while calcium antagonists may be over used.

Adrenergic beta-Antagonists↗
PubMed1996

Angiographic and procedural outcome after coronary angioplasty in high-risk subsets using a decremental diameter (tapered) balloon catheter. Tapered Balloon Registry Investigators.

The angiographic and clinical outcomes of 115 patients (129 lesions) treated at 11 clinical centers using a decremental diameter (tapered) balloon catheter were evaluated. The presence of marked tapering of the reference vessel, lesion location involving a bifurcation or anastomosis of a saphenous vein graft, or total coronary occlusion where estimation of the distal vessel size was difficult were indications for this device. The tapered balloon was used as the initial dilatation device in 62 patients (73 narrowings), and as a secondary device in 53 patients (56 narrowings). Lesions selected for tapered balloon angioplasty were generally complex (95% had > or = 1 and 60% had > or = 2 adverse morphologic features). Vessel diameters were larger in the proximal reference segments (3.07 +/- 0.52 mm) than in distal ones (2.48 +/- 0.45 mm) (p<0.001). After tapered balloon angioplasty, the minimal lumen diameter increased from 0.85 +/- 0.34 mm to 2.13 +/- 0.50 mm (p<0.001), and the percent diameter stenosis decreased from 69 +/- 12% to 24 +/- 12% (p<0.001). Coronary dissections occurred in 20% of lesions; they were severe in 4% (National Heart, Lung, and Blood Institute grade C to F). Abrupt closure occurred in 4.3% of patients (2.6% immediate; 1.7% delayed). Procedural success was obtained in 110 patients (96%); major complications (in-hospital death, myocardial infarction, or emergency coronary bypass surgery) occurred in 3 patients (2.7%). Coronary angioplasty using the tapered balloon catheter appears to be a safe and effective technique for the treatment of complex lesion subsets, particularly those involving coronary arteries with marked segmental tapering.

Aged↗
PubMed1996

Children's assignment of gender to animal characters in pictures.

In previous research (DeLoache, Cassidy, & Carpenter, 1987), mothers' descriptions of gender-neutral animal characters were influenced by subtle gender stereo-types. The present research was an investigation of children's assignment of gender to the same neutral characters. The youngest children, 4 to 5 years old, usually assigned their own gender to the characters (bears). The 7- to 8-year-old and 10- to 11-year-old children were influenced by gender stereotypes. Solitary or noninteracting bears were less likely to receive female gender labels than were bears involved in adult-child interactions. Boys in the oldest age group were most influenced by the stereotypes.

Adult↗
PubMed1996

Weight change in Alzheimer's disease.

PURPOSE: To determine the natural history of weight change and the occurrence of clinically significant weight loss in subjects with Alzheimer's disease (AD). PATIENTS AND METHODS: Subjects with AD and cognitively normal older controls were recruited from 21 U.S. university medical centers that were participating in the Consortium to Establish a Registry for Alzheimer's Disease (CERAD). Annual assessments were performed. Subjects with AD (n = 362) and controls (n = 317) with two or more weight measurements taken a year or more apart were included in this analysis. The average period of follow-up was > 2 years for both subjects with AD and controls. Four variables describing different aspects of weight change were defined: >/= 5% weigh loss, percent weight change/year, maximum percent weight loss over 1 year, and standard deviation of measurements/subject. RESULTS: Nearly twice as many subjects with AD experienced a weight loss of 5% or more when compared with controls (men P = .003 women P = .001). Surprisingly, a weight gain of 5% or more was also more common among AD cases. Overall, there was a tendency toward weight loss for both subjects with AD and controls, as measured by percent weight change/year. When other possible causes of weight loss were controlled using a multivariate model, a diagnosis of AD remained a significant predictor of >/= 5% weigh loss (P << .001), maximum percent weight loss over 1 year (P << .001), and standard deviation of measurements/subject (P << .001). A trend toward significance was noted for percent weight change/year (P = .07). Other than AD, very few of the possible confounders of this association remained significant predictors of weight change. In bivariate analysis, the severity of AD at entry correlated with percent weight change/year and standard deviation of measurements/subject. Additionally, the functional status of subjects with AD correlated with all four measures of weight change. CONCLUSION: Clinically important weight loss occurs more frequently among patients with AD than among cognitively normal control subjects. Instances of weight gain, periods of acute weight loss, and greater fluctuations in weight suggest that the natural history of weight change in AD may be characterized by dysfunction in body weight regulation. Further analysis is warranted regarding the relationship of severity of dementia, functional status, and other specific aspects of AD to weight change.

Activities of Daily Living↗
PubMed1995

Cost effectiveness of thrombolytic therapy with tissue plasminogen activator as compared with streptokinase for acute myocardial infarction.

BACKGROUND: Patients with acute myocardial infarction who were treated with accelerated tissue plasminogen activator (t-PA) (given over a period of 1 1/2 hours rather than the conventional 3 hours, and with two thirds of the dose given in the first 30 minutes) had a 30-day mortality that was 15 percent lower than that of patients treated with streptokinase in the Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries (GUSTO) study. This was equivalent to an absolute decrease of 1 percent in 30-day mortality. We sought to assess whether the use of t-PA, as compared with streptokinase, is cost effective. METHODS: Our primary, or base-case, analysis of cost effectiveness used data from the GUSTO study and life expectancy projected on the basis of the records of survivors of myocardial infarction in the Duke Cardiovascular Disease Database. In the primary analysis, we assumed that there were no additional treatment costs due to the use of t-PA after the first year and that the comparative survival benefit of t-PA was still evident one year after enrollment. RESULTS: One year after enrollment, patients who received t-PA had both higher costs ($2,845) and a higher survival rate (an increase of 1.1 percent, or 11 per 1000 patients treated) than streptokinase-treated patients. On the basis of the projected life expectancy of each treatment group, the incremental cost-effectiveness ratio--with both future costs and benefits discounted at 5 percent per year--was $32,678 per year of life saved. The use of t-PA was least cost effective in younger patients and most cost effective in older patients. At all ages, the use of t-PA in patients with anterior infarctions yielded more favorable cost-effectiveness values. In our secondary analyses, the cost-effectiveness values were most sensitive to a lowering of the projected long-term survival benefits of t-PA and to moderate or greater increases in the projected medical costs for patients in the t-PA group after the first year. In contrast, our results were not sensitive to even very unfavorable assumptions about the additional costs associated with the higher rate of disabling stroke that was noted in patients treated with t-PA in the GUSTO study. CONCLUSIONS: The cost effectiveness of treatment with accelerated t-PA rather than streptokinase compares favorably with that of other therapies whose added medical benefit for dollars spent is judged by society to be worthwhile.

Adult↗