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Biomedical subjects

J Wolfe

Publications and source records attributed to J Wolfe.

At least 73 records · Page 4Linked to original sources
PubMed1999

Freezing, drying, and/or vitrification of membrane- solute-water systems.

Membranes are often damaged by freezing and/or dehydration, and this damage may be reduced by solutes. In many cases, these phenomena can be explained by the physical behavior of membrane-solute-water systems. Both solutes and membranes reduce the freezing temperature of water, although their effects are not simply additive. The dehydration of membranes induces large mechanical stresses in the membranes. These stresses produce a range of physical deformations and changes in the phase behavior. These membrane stresses and strains are in general reduced by osmotic effects and possibly other effects of solutes-provided of course that the solutes can approach the membrane in question. Membrane stresses may also be affected by vitrification where this occurs between membranes. Many of the differences among the effects of different solutes can be explained by the differences in the crystallization, vitrification, volumetric, partitioning, and permeability properties of the solutes.

Freeze Drying↗
PubMed1999

Cost comparison of aortic aneurysm endograft exclusion versus open surgical repair.

BACKGROUND: Shrinking health care resources impose a requirement to evaluate new technology for cost as well as clinical effectiveness. We studied an initial clinical experience with endograft treatment (EAG) of abdominal aortic aneurysm (AAA) at the beginning of an endovascular program in comparison with open surgical repair (OSR), which had been in use for decades. METHODS: From March 1997 to April 1998, the utilization of hospital resources, actual cost, clinical descriptors, and treatment outcomes were recorded for two contemporaneous groups, each having 16 consecutive patients with AAA, treated with either EAG or OSR. Subjects were not randomized; EAG treatment was based on predetermined exclusion/inclusion criteria. Statistical comparison was by either Fisher's exact test or the Wilcoxon rank sum test. RESULTS: There were no differences between OSR and EAG in age, gender, AAA size, smoking status, diabetes, ischemic heart disease, history of coronary artery bypass grafts, previous vascular surgery, or other comorbidity. There were no deaths in either group. Patients treated by EAG procedure had significantly lower length of hospital stay, length of stay in intensive care unit, time in operating room, and cost of operating room without graft (P <0.05). Cost of operating room with graft was less in OSR group (P <0.001). In-hospital imaging costs specific to the EAG procedure were $1,370.45 +/- $66.92 (range $911.58 to $1,826.76). Total costs were not significantly different between the OSR and EAG, $12,714.19 +/- $1,115.52 and $12,904.99 +/- $494.69, respectively (P = 0.26). CONCLUSIONS: Total hospital cost is not different for the two treatments studied despite differences in experience with their use. Endograft treatment utilizes significantly less hospital resources than open surgical repair. The endograft prosthesis contributes a significant cost increment that may decline with expanded use.

Age Factors↗
PubMed1999

Comparison of inhaled salmeterol and oral zafirlukast in patients with asthma.

BACKGROUND: Salmeterol, a long-acting beta2 -agonist, and zafirlukast, a leukotriene receptor antagonist, are both indicated for the treatment of asthma in adolescent and adult patients. OBJECTIVE: We sought to compare the effect of 4 weeks of treatment with inhaled salmeterol xinafoate versus oral zafirlukast in the treatment of persistent asthma. METHODS: This was a randomized, double-blind, double-dummy, parallel-group, multicenter clinical trial. Patients, over 80% of whom were on a concurrent inhaled corticosteroid regimen, were treated for 4 weeks with either inhaled salmeterol xinafoate 42 microgram twice daily administered by means of a metered-dose inhaler or oral zafirlukast 20 mg twice daily. The primary efficacy measure was morning peak expiratory flow (PEF); secondary efficacy measures included evening PEF, asthma symptom scores, supplemental albuterol use, nighttime awakenings, sleep symptoms, asthma exacerbations, and FEV1. RESULTS: Both inhaled salmeterol and oral zafirlukast resulted in within-group improvements from baseline in measures of pulmonary function, asthma symptoms, and supplemental albuterol use. Salmeterol treatment resulted in significantly greater improvements from baseline compared with zafirlukast for most efficacy measurements, including morning PEF (29.6 vs 13.0 L/min; P </= .001), percentage of symptom-free days (22.4% vs 8.8%; P </= .001), and percentage of days and nights with no supplemental albuterol use (30.5% vs 11.3%; P </= .001). There were no differences in safety profiles as assessed by adverse event monitoring. CONCLUSION: In patients with persistent asthma, most of whom were concurrently using inhaled corticosteroids, treatment with inhaled salmeterol provided significantly greater improvement than oral zafirlukast in overall asthma control over the 4-week treatment period.

Administration, Inhalation↗
PubMed1999

Gone fishing.

Explore the source record for details and available documents.

Animals↗
PubMed1999

Lens autofluorescence and light scatter in relation to the lens opacities classification system, LOCS III.

PURPOSE: To compare values of the human lens autofluorescence and back light scatter measurements with the improved Lens Opacities Classification System, LOCS III. METHODS: We measured autofluorescence and back light scatter of the lens from 122 smoking males aged 57 to 76 years who participated in a cancer prevention study. The retroillumination and slit-lamp photographs of the lenses were graded according to LOCS III by the Center for Ophthalmic Research in Boston. Lens fluorometry was carried out with a previously described technique using blue-green (495 nm/520 nm) autofluorescence range. Interzeag Lens Opacity Meter 701 was used for light scatter measurements. RESULTS: LOCS III nuclear opalescence and color grades were statistically significantly correlated with lens autofluorescence as well as with light scatter values. The lens transmission index of autofluorescence measurements showed the highest correlation with the nuclear color (r = -0.71; p < 0.0001) and the light scatter value with nuclear opalescence (r = 0.64; p < 0.0001). There was no correlation between autofluorescence measurements and LOCS III grades of cortical or posterior subcapsular cataract. A weak relation could be found between the grades of cortical cataract and light scatter values. CONCLUSIONS: The lens fluorometry provides a practical clinical technique to evaluate the yellow coloration and opalescence of the human lens nucleus. It may be a useful additional tool together with a subjective grading system in the follow-up of optical changes occurring in the nuclear region of the lens.

Aged↗
PubMed1999

Course and predictors of posttraumatic stress disorder among Gulf War veterans: a prospective analysis.

Rates and predictors of posttraumatic stress disorder (PTSD) over time are not well understood. This study is the first to look at the rates of PTSD immediately following war and 2 years later using a large cohort (N = 2,949) of Gulf War veterans. Using a cut score to indicate presumptive PTSD, 3% of participants exceeded the cutoff at Time 1 compared with 8% at Time 2. Those who exceeded the cutpoint at Time 1 were up to 20 times more likely to exceed the cutpoint at Time 2 than those who did not exceed the cutpoint at Time 1. Women and those with high levels of combat exposure were at increased risk for PTSD at both times. Being young, being single, and having previous combat experience were associated with increased risk at Time 1 only, whereas reservists and enlisted personnel were at increased risk at Time 2 only. These findings indicate that, although low initially, rates of PTSD increased substantially over time.

Adult↗
PubMed1999

Vascular surgical society of great britain and ireland: transcranial doppler ultrasonography as a predictor of haemodynamically significant carotid stenosis

BACKGROUND: Transcranial Doppler (TCD) ultrasonography can detect evidence of collateral flow across the anterior communicating artery and/or the posterior communicating artery, which occurs when there is significant alteration of 'inflow' to the brain. The aim of the study was to determine the blood flow velocity produced by a carotid stenosis which produces this haemodynamic effect on the cerebral circulation and evokes collateral circulation. METHODS: Forty-eight patients with varying degrees of carotid stenosis (10 per cent to occlusion) who underwent both carotid duplex and TCD examination were reviewed. An ATL HDI 3000 ultrasound system was used for the carotid and TCD studies. The carotid examination recorded peak-systolic velocity (PSV) and end-diastolic velocity (EDV) in the carotid systems bilaterally. TCD recorded Doppler spectra from the bilateral middle cerebral, anterior cerebral, posterior cerebral, intracranial vertebral and basilar arteries. Collateral flow was assessed in two ways: 'intracranial crossover' collateral and 'posterior to anterior' collateral. Each internal carotid artery (ICA), together with the ipsilateral hemisphere, was analysed for the presence or absence of collateral flow. Data were expressed as mean(s.e.m.). RESULTS: The PSV of the group with collateral circulation was 472(14) cm s-1 and that of the group without collateral flow was 164(3) cm s-1 (P < 0.0001, Mann-Whitney test). The respective EDVs were 158(13) and 58(7) cm s-1 (P < 0.0001). CONCLUSION: PSVs and EDVs in the ICA, in conjunction with collateral flow measured by TCD, are indicators of a haemodynamically significant carotid lesion, and provide more information than two-dimensional imaging studies. In the future, parameters set by combining carotid duplex and TCD investigations may represent the 'gold standard' for evaluation of cerebral blood flow.

Journal Article↗
PubMed1999

Cardiovascular, autonomic, and plasma catecholamine responses in unilateral and bilateral carotid artery stenosis.

OBJECTIVE: To determine impairment of baroreceptor afferent activity, which may affect cardiovascular autonomic function in patients with unilateral and bilateral carotid artery stenosis. Comparison was made with normal subjects and hypertensive patients. METHODS: A series of cardiovascular autonomic function tests along with plasma noradrenaline (norepinephrine) measurements were performed in 46 patients with carotid artery stenosis (CAS); 23 had unilateral and 23 had bilateral stenosis. Comparison was made with 21 hypertensive patients (with a similar degree of raised blood pressure), and 27 normal subjects. RESULTS: Over a third of patients with unilateral and bilateral CAS had postural hypotension. Heart rate did not rise appropriately in CAS despite the postural fall in blood pressure. Pressor responses in CAS were preserved. Heart rate responses to respiratory stimuli were attenuated. Plasma noradrenaline concentrations rose normally during head up tilt. CONCLUSION: A substantial proportion with CAS had postural hypotension and attenuated heart rate responses. This was not due to sympathetic vasoconstrictor or cardiac parasympathetic failure, thus suggesting impaired afferent baroreceptor activity, probably secondary to involvement of the carotid sinus. Cardiovascular autonomic testing and assessment of postural hypotension and factors enhancing it may be of clinical relevance in such patients, especially as the symptoms of postural hypotension overlap with those due to thromboembolism.

Aged↗
PubMed1999

Development of a brief questionnaire for screening for multiple chemical sensitivity syndrome.

The objective of this study was to identify a parsimonious set of questions that has high sensitivity and specificity for screening for individuals with multiple chemical sensitivity (MCS) syndrome. We performed a cross-sectional survey using a case-control design. Subjects were derived from patients seen at an academically based Occupational and Environmental Medicine Clinic. Cases consisted of patients who fulfilled the Cullen definition for MCS. Controls were patients who had diagnoses excluding MCS and asthma and who were matched to cases by age and sex. Cases and controls filled out a screening questionnaire that, among things, elicited responses as to whether and how subjects reacted to 122 different types of environmental exposures. Data from 44 pairs of cases and controls were available for analysis. The average age of cases was 50.2 years, and 91% was female. Among cases, the most common exposure that was purported to incite MCS was 'indoor air quality contaminants (unspecified)' (59%), followed by solvents (27.3%). After randomly excluding five cases and controls, a stepwise selection procedure for two-group discriminant analysis revealed that the main contributors to the discrimination of the remaining cases and controls were self-reported reactions to copy machine emissions, marking pens, aftershave, window cleaner, nylon fabric, pine-scented products, and rayon material. When a positive response to these factors was used as the sole method for discriminating cases from controls, only one of 41 cases was misclassified as a control while none of the controls was misclassified as a case. When the same method was applied to the five excluded cases and five excluded controls, only one of the five cases was misclassified while none of the five controls was misclassified as a case. Among patients with MCS defined by the Cullen criteria in this clinical setting, having a reaction to these seven common potential exposures comprised a parsimonious set of factors that discriminated between MCS patients and age- and sex-matched normal controls. These questions may have utility in screening for individuals with MCS in general population survey studies.

Air Pollution, Indoor↗
PubMed1999

Stability of attitudes regarding physician-assisted suicide and euthanasia among oncology patients, physicians, and the general public.

PURPOSE: Attitudes regarding the ethics of physician-assisted suicide (PAS) and euthanasia have been examined in many cross-sectional studies. Stability of these attitudes has not been studied, and this is important in informing the dialog on PAS in this country. We evaluated the stability of attitudes regarding euthanasia and PAS among three cohorts. METHODS: Subjects included 593 respondents: 111 oncology patients, 324 oncologists, and 158 members of the general public. We conducted initial and follow-up interviews separated by 6 to 12 months by telephone, regarding acceptance of PAS and euthanasia in four different clinical vignettes. RESULTS: The proportion of respondents with stable responses to vignettes ranged from 69.2% to 94.8%. In comparison to patients and the general public, physicians had less stable responses concerning the PAS pain vignette (69.1% v 80.8%; P =.001) and more stable responses for all euthanasia vignettes (P <.001) except for pain. Over time, physicians were significantly more likely to change toward opposing PAS and euthanasia in all vignettes (P <.05). Characteristics previously associated with attitudes regarding PAS and euthanasia, such as Roman Catholic religion, were not predictive of stability. CONCLUSION: Up to one third of participants changed their attitudes regarding the ethical acceptability of PAS and euthanasia in their follow-up interview. This lack of consistency mandates careful interpretation of referendums and requests for physician-assisted suicide. Furthermore, in this study, we found that physicians are becoming increasingly opposed to PAS and euthanasia. The growing disparity between physicians and patients regarding the role of these practices is large enough to suggest possible conflicts in the delivery of end-of-life care.

Adult↗
PubMed1998

Risk factors for nuclear opalescence in a longitudinal study. LSC Group. Longitudinal Study of Cataract.

This study evaluated risk factors for increases in nuclear opacification of the lens in the Longitudinal Study of Cataract (1989-1993; Boston, Massachusetts), which included 764 participants. Baseline data on demographic, medical, and other risk factors were available from an earlier case-control study; follow-up visits were completed yearly over a 4-year period. The lens photographs taken at baseline and at each follow-up visit were graded using the Lens Opacities Classification System III protocol. Analyses evaluated which risk factors collected at baseline were related to increased nuclear opacification at follow-up. The MULCOX2 method, an extension of Cox regression for nested event-time data, was used to estimate the effects of the risk factors. This method accounted for the correlation between fellow eyes. Results showed that the risk of nuclear opacification increased with each year of age (relative risk (RR) = 1.07), white race (RR = 2.94), lower education (RR = 1.50), use of gout medications (RR = 2.32), current smoking (RR = 1.58), family history of cataract (RR = 1.39), and preexisting posterior subcapsular opacities (RR = 6.67). An association with early use of eyeglasses was also suggested (RR = 1.37). In conclusion, nuclear opacification was related to demographic and other variables, including potentially modifiable factors such as current smoking and use of gout medications. Most risk factors identified by this longitudinal study confirm those found by the original case-control study. The increased risk of nuclear opacities in whites appears to be a new finding.

Adult↗
PubMed1998

Health symptoms reported by Persian Gulf War veterans two years after return.

The role of actual or perceived events has considerable importance for individual well-being. Although the Persian Gulf War (PGW) has raised questions about the presence of hazardous environmental exposures, few, if any confirmed exposure data are available. Yet, a substantial number of PGW veterans report health problems since their return from that war. The present study was conducted to investigate possible associations between opportunities for exposure and increased rates of health symptom reporting. First, we examined descriptive data on types and rates of health symptoms reported by a cohort of Gulf War veterans. Then, using proxies for three wartime experiences, we examined associations between health symptoms reports and different Persian Gulf exposure scenarios (reported exposure to poison gas or germ warfare, being in a transportation unit, or high levels of combat exposure), adjusting for the effects of background characteristics (e.g., gender, psychological distress). Findings suggest that reported exposure to poison gas or germ warfare is related to higher symptom reporting by this cohort of New England area veterans. Limitations in the study design and the challenges involved in studying PGW veterans' illnesses are discussed.

Adult↗
PubMed1998

The effects of solutes on the freezing properties of and hydration forces in lipid lamellar phases.

Quantitative deuterium nuclear magnetic resonance is used to study the freezing behavior of the water in phosphatidylcholine lamellar phases, and the effect upon it of dimethylsulfoxide (DMSO), sorbitol, sucrose, and trehalose. When sufficient solute is present, an isotropic phase of concentrated aqueous solution may coexist with the lamellar phase at freezing temperatures. We determine the composition of both unfrozen phases as a function of temperature by using the intensity of the calibrated free induction decay signal (FID). The presence of DMSO or sorbitol increases the hydration of the lamellar phase at all freezing temperatures studied, and the size of the increase in hydration is comparable to that expected from their purely osmotic effect. Sucrose and trehalose increase the hydration of the lamellar phase, but, at concentrations of several molal, the increase is less than that which their purely osmotic effect would be expected to produce. A possible explanation is that very high volume fractions of sucrose and trehalose disrupt the water structure and thus reduce the repulsive hydration interaction between membranes. Because of their osmotic effect, all of the solutes studied reduced the intramembrane mechanical stresses produced in lamellar phases by freezing. Sucrose and trehalose at high concentrations produce a greater reduction than do the other solutes.

Biophysical Phenomena↗
PubMed1998

Antioxidant vitamins and nuclear opacities: the longitudinal study of cataract.

OBJECTIVE: The association of antioxidant nutrients and risk of nuclear opacification was evaluated in the Longitudinal Study of Cataract. DESIGN: Nutritional data were collected at baseline on the 764 participants, which included assessment of dietary intake, use of vitamin supplements, and plasma levels of vitamin E. Ophthalmologic and other data were collected at baseline and at yearly follow-up visits, including lens photographs, which were graded using the Lens Opacities Classification System III protocol. MAIN OUTCOME MEASURES: Analyses examined whether the nutritional factors at baseline were related to increases in nuclear opacification at follow-up. The MULCOX2 approach, an extension of the Cox regression model, was used. Results are presented as relative risks (RRs) and 95% confidence intervals. INTERVENTION: Intervention was not applicable. RESULTS: The risk of nuclear opacification at follow-up was decreased in regular users of multivitamin supplements (RR = 0.69; 0.48-0.99), vitamin E supplements (RR = 0.43; 0.19-0.99), and in persons with higher plasma levels of vitamin E (RR = 0.58; 0.36-0.94). CONCLUSIONS: In regular users of multivitamin supplements, the risk of nuclear opacification was reduced by one third; in regular users of vitamin E supplements and persons with higher plasma levels of vitamin E, the risk was reduced by approximately half. These results are similar to those obtained in our earlier case-control study. Because these data are based on observational studies only, the results are suggestive but inconclusive. The possible effect of nutritional supplements on the lens requires confirmation by ongoing clinical trials.

Adult↗
PubMed1998

Baseball and beer: an analysis of alcohol consumption patterns among male spectators at major-league sporting events.

STUDY OBJECTIVE: Examination of alcohol consumption patterns of male spectators at two major-league baseball stadiums. METHODS: A prospective observational study was conducted at two stadiums over the course of three games at each venue. We approached 1,084 male spectators of drinking age in a consecutive fashion at two junctures: at the entrance gate and during the fifth inning inside the stadium's concourse. Of those approached, 747 (68.9%) participated. After verbal consent, participants completed a questionnaire and blew into a breath analyzer. The results were blinded and later analyzed. RESULTS: Forty-one percent of all participants tested positive for alcohol. The highest consumption occurred in the 20- to 35-year-old age group. In this age group, 50.8% had consumed some alcohol, and 10.8% had a blood alcohol level of .08% (intoxicated) or higher. Almost 5% of all participants tested during the fifth inning collection were intoxicated and claimed to be driving. CONCLUSION: Of the spectators tested, those in the 20- to 35-year-old age group were most likely to have consumed alcohol and to be legally intoxicated. A disturbing number of spectators who had blood alcohol levels of .08% or higher late in the game claimed to be driving home.

Adult↗
PubMed1998

Advances in fluorescent in situ hybridisation.

Recent advances in fluorescent in situ hybridisation included the generation of allele-specific probes, bar-coded chromosomes, and the visualisation of chromosome territories and genes within the nucleus. One major advance has been our ability to visualise and make precise and reproducible measurements from stretched DNA molecules prepared directly from human cells.

Chromosomes↗
PubMed1998

Health status of Persian Gulf War veterans: self-reported symptoms, environmental exposures and the effect of stress.

BACKGROUND: Most US troops returned home from the Persian Gulf War (PGW) by Spring 1991 and many began reporting increased health symptoms and medical problems soon after. This investigation examines the relationships between several Gulf-service environmental exposures and health symptom reporting, and the role of traumatic psychological stress on the exposure-health symptom relationships. METHODS: Stratified, random samples of two cohorts of PGW veterans, from the New England area (n = 220) and from the New Orleans area (n = 71), were selected from larger cohorts being followed longitudinally since arrival home from the Gulf. A group of PGW-era veterans deployed to Germany (n = 50) served as a comparison group. The study protocol included questionnaires, a neuropsychological test battery, an environmental interview, and psychological diagnostic interviews. This report focuses on self-reported health symptoms and exposures of participants who completed a 52-item health symptom checklist and a checklist of environmental exposures. RESULTS: The prevalence of reported symptoms was greater in both Persian Gulf-deployed cohorts compared to the Germany cohort. Analyses of the body-system symptom scores (BSS), weighted to account for sampling design, and adjusted by age, sex, and education, indicated that Persian Gulf-deployed veterans were more likely to report neurological, pulmonary, gastrointestinal, cardiac, dermatological, musculoskeletal, psychological and neuropsychological system symptoms than Germany veterans. Using a priori hypotheses about the toxicant effects of exposure to specific toxicants, the relationships between self-reported exposures and body-system symptom groupings were examined through multiple regression analyses, controlling for war-zone exposure and post-traumatic stress disorder (PTSD). Self-reported exposures to pesticides, debris from Scuds, chemical and biological warfare (CBW) agents, and smoke from tent heaters each were significantly related to increased reporting of specific predicted BSS groupings. CONCLUSIONS: Veterans deployed to the Persian Gulf have higher self-reported prevalence of health symptoms compared to PGW veterans who were deployed only as far as Germany. Several Gulf-service environmental exposures are associated with increased health symptom reporting involving predicted body-systems, after adjusting for war-zone stressor exposures and PTSD.

Adult↗