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Biomedical subjects

S West

Publications and source records attributed to S West.

At least 127 records · Page 7Linked to original sources
PubMed1989

Non-invasive diagnosis of ischemic heart disease using stress thallium scintigraphy and digital exercise 2-dimensional echocardiography.

The introduction of computer technology has overcome many of the technical difficulties in performing and interpreting echocardiograms obtained from exercising individuals and has made stress echocardiography a potentially practical examination. Additional data, however, are necessary to establish the accuracy of exercise echocardiography. The purpose of this study is to compare exercise echocardiography and planar thallium studies for accuracy in detecting coronary artery disease. The study was performed on 50 patients, 41 of whom underwent coronary angiography. For the remaining 9 patients accuracy was defined as concordance of clinical information, treadmill ECG results, thallium data and the exercise echocardiogram. If there was any discrepancy among these tests, the patient was not included in the analysis. The sensitivity of exercise 2D digital echocardiography was comparable to stress thallium (0.86 vs 0.85) and was better than treadmill test alone (0.66). There were no false positive tests with echocardiographic study, while 1 false positive thallium examination was detected. The diagnostic accuracy of stress echocardiography was 0.90, stress thallium 0.85 and treadmill test only 0.75. In conclusion, exercise echocardiography appears to give results comparable to stress planar thallium studies. In addition, the ultrasonic procedure has several advantages: it is totally non-invasive, does not require a reperfusion study 4 hours later, avoids radiation and is less expensive.

Adult↗
PubMed1988

RecA-mediated strand exchange reactions between duplex DNA molecules containing damaged bases, deletions, and insertions.

RecA protein from Escherichia coli promotes homologous pairing and strand exchange between duplex DNA molecules if one is partially single-stranded. Using linear duplexes and circles with a single-stranded gap as the substrates, this reaction generates nicked circular heteroduplex DNA and linear molecules with single-stranded ends. The completion of strand exchange can be demonstrated by the production of nicked circular heteroduplex DNA detected by gel electrophoresis and autoradiography using radiolabeled linear molecules. When the effect of ultraviolet damage to the substrate DNA was tested, strand exchange was found to pass 30 or more pyrimidine dimers in each duplex. In contrast, exchanges were blocked or severely slowed by interstrand cross-links and monoadducts produced by psoralen and 360 nm light. Deletions and insertions of from 4 to 38 base pairs in the DNA substrates had little effect on the production of nicked circular heteroduplex DNA. However, those of 120 base pairs, or greater, reduced the product yield to a level below the threshold of detection. These results contrast with those obtained in related three-stranded reactions (Bianchi, M. E., and Radding, C. M. (1984) Cell 35, 511-520), in which stable heteroduplex products with 500 or 1300 unpaired bases were obtained when the insert was located within a single-stranded circular substrate.

Base Sequence↗
PubMed1988

Community-based intervention programs for trachoma control.

Trachoma continues to be a leading cause of blindness largely confined to developing countries. Trachoma control programs have primarily been oriented to drug therapy, an approach which may be successful if it is community-based. However, the costs to ensure long-term success are substantial. Community-based health education approaches to reduce risk factors currently provide the most promising approach for long-term trachoma control.

Clinical Trials as Topic↗
PubMed1987

Recruitment in the Cooperative Study of Sickle Cell Disease (CSSCD).

The Cooperative Study of Sickle Cell Disease (CSSCD) is a multiinstitutional investigation of the natural history of clinical course of sickle cell disease from birth through adulthood. The study is not a trial; rather, it involves data collection at 23 institutions in a uniform, standardized fashion on 3800 patients. Recruitment aspects that were addressed include issues related to recruitment of different age groups, ranging from newborns to pregnant women to patients over 50 years of age; the need to include mildly affected patients to ensure that the study would not reflect only a severe hospital-based population; recruitment from rural populations; and the need to screen and enter a newborn population at birth. The recruitment goal of entering 3200 patients, including 2100 patients with SS hemoglobinopathy, over a 24-month period was accomplished after 27 months.

Age Factors↗
PubMed1987

Natural killer cell cytotoxicity and antibody-dependent cellular cytotoxicity to herpes simplex virus-infected cells in human pregnancy.

Natural killer cell (NKC) cytotoxicity and antibody-dependent cellular cytotoxicity (ADCC) represent the ability of human leukocyte effector cells to destroy target cells in the absence and presence of antibody, respectively. Since these immune systems play a pivotal role in the body's primary lines of defense against a variety of pathogens including herpes simplex virus (HSV), a study was undertaken to evaluate the influence of pregnancy on these systems. Eleven uncomplicated gravidas were followed serially through each trimester and compared to 11 nonpregnant female controls. Mononuclear cells were acquired by Ficoll-Hypaque centrifugation of heparinized blood. Chang liver cells infected with HSV-I were utilized as target cells in a 51Cr release assay. Mean NKC values in the pregnant patients were uniformly lower than in the controls. No similar decreases in ADCC activity were observed in a comparison between the two study populations. These data support previous observations suggesting that pregnancy represents a relatively immunocompromised state. Differences apparently exist between NKC and ADCC effector cell populations with regard to the influence of pregnancy. Although these physiologic alterations in immunoregulation may help support the fetoplacental allograph, detrimental conditions may exist regarding susceptibility to various pathogens such as HSV.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1986

Seroepidemiology of hepatitis B virus in the Philippines.

Hepatitis B virus markers were studied in 2,842 Philippine rural subjects from four villages in 1979-1982. The prevalence of hepatitis B surface antigen (HBsAg) and all markers for hepatitis B virus averaged 12% and 58%, respectively, in these rural populations. It is estimated that five million Filipinos are HBsAg positive. The rural age-specific HBsAg prevalence shows an "early peak" (in persons 3-4-years-old) in two communities and a "late peak" (in persons 30-40-years-old) in the other two communities. Family studies suggest that the prevalence of HBsAg and hepatitis B e antigen (HBeAg) among parents of the young children in an "early peak" and a "late peak" village cannot fully account for the difference in the patterns of prevalence of all markers, or the HBsAg marker. Horizontal intrafamilial and extrafamilial transmission may also be significant. Further research is needed on risk factors for hepatitis B virus infection.

Adolescent↗
PubMed1985

Modification of the United States' diet to effect changes in blood lipids and lipoprotein distribution.

Twenty men, 19 premenopausal and 14 postmenopausal women consumed a diet for 13 weeks that supplied 35% of the calories from fat, 50% from carbohydrate, and 15% from protein. The diet was low in cholesterol, saturated fat, and salt, and high in complex carbohydrate and fiber. The 7-day menu was composed of common well-accepted foods prepared in a simple attractive manner. Plasma total cholesterol, LDL cholesterol, and VLDL cholesterol were reduced, but triglyceride levels were not different than after self-selected diets. When 20% of the complex carbohydrate was replaced by simple carbohydrate and other diet components remained optimal, triglyceride and VLDL cholesterol levels increased in men and premenopausal women and total cholesterol increased in premenopausal women. These results suggest that beneficial effects on the blood lipids and lipoprotein distribution of men and women may be obtained by minimal modification of a typical U.S. diet.

Adult↗
PubMed1985

Effects of spelling-to-sound regularity on word identification following brief presentation in the right or left visual field.

In this experiment subjects were briefly presented with a vertically written word to either the left or right visual field. On half the critical trials the target word was irregular in its spelling-to-sound correspondence (e.g. PINT) and in the other half it was regular (e.g. LIME). With right visual field presentation substantially more regular than irregular words were reported correctly but with left visual field presentation no such effect was found. The data also showed the presence of far more "regularization" errors following right visual field presentation. The data are seen as consistent with the view that the right hemisphere is not capable of generating phonology.

Cerebral Cortex↗
PubMed1985

Double-blind treatment of seborrheic dermatitis with 2% ketoconazole cream.

Thirty-seven patients with seborrheic dermatitis were treated topically with a 2% ketoconazole cream or its vehicle control in a double-blind study. The subjects were studied for numbers of Malassezia ovalis (Pityrosporum ovale) cells in their scalp scale; changes in numbers of yeast cells and morphology of M. ovalis were tabulated along with clinical assessment of improvement. The 2% ketoconazole cream, but not the placebo cream, reduced the numbers of viable yeast cells on the scalp. The clinical effect of 2% ketoconazole cream was good (75%-95% improvement) or better in eighteen of twenty subjects; the placebo cream produced good results in only three of seventeen subjects treated. Results of this study are consistent with the view that M. ovalis plays a central role in the pathogenesis of seborrheic dermatitis.

Administration, Topical↗
PubMed1984

Effects of thalassemia and microcytosis on the hematologic and vasoocclusive severity of sickle cell anemia.

The characteristic clinical heterogeneity of sickle cell anemia (HbSS) may be, in part, a result of its interactions with alpha-thalassemia. Although alpha-thalassemia clearly affects some hematologic features of HbSS, its role in modulating the vasoocclusive severity of disease is not clear. To further explore this relationship, we examined the incidence of painful episodes, acute chest syndrome, aseptic bone necrosis, and leg ulcers in 3 patient groups with sickle cell disease: (1) 2,147 patients over age 2 yr, stratified according to mean corpuscular volume (MCV); (2) 183 patients selected on the basis of microcytosis and elevated HbA2, on whom globin biosynthesis studies were done; and (3) 125 patients who had alpha-globin genotype assigned by restriction endonuclease gene mapping. When patients were stratified by MCV, there was a reciprocal relationship between HbA2 levels and MCV, reflecting the presence of patients with beta o and alpha-thalassemia in the low MCV groups. The erythrocyte indices and HbA2 levels in patients classified as HbSS-alpha-thalassemia, by either globin synthesis studies or gene mapping, were very similar to those previously reported by others. Neither microcytosis, beta o, or alpha-thalassemia appeared to provide any clear protection from the vasoocclusive complication evaluated, and the prevalence of aseptic necrosis was increased in patients with microcytosis over age 20 yr and in groups with alpha-thalassemia. The effects of a reduced MCV and mean corpuscular hemoglobin concentration (MCHC), of possible benefit by themselves, when accompanied by a reduction in hemolysis and rise in hemoglobin concentration, as in HbSS-alpha-thalassemia, may cause sufficient rise in blood viscosity in critical vascular beds to impair blood flow and negate any amelioration of vasoocclusive complications in HbSS.

Adolescent↗
PubMed1983

Morbidity and school absence caused by asthma and wheezing illness.

A survey in the London Borough of Croydon was conducted among an entire school cohort, aged about 9 years, to describe the current morbidity from wheezing illness, its relation to social and family factors, and its effects on social and educational development. A postal screening questionnaire was sent to 5100 parents, and 11.1% of the children were reported to have had wheezing illness over the previous 12 months. A sample of 284 parents were subsequently interviewed at home about their child's illness. School absence over the past year caused by wheezing illness was reported by 58%; and in 12% of children this amounted to more than 30 school days. School absence was strongly associated with all other indicators of morbidity-- short and long term. The proportion described as having "asthma' rose from 22% in those with no absence, to 50% in those with more than 30 days absence. Compared with 92 randomly selected controls with no history of wheezing, wheezy children had more atopic conditions, recurrent headaches, and abdominal pains. School absence was associated with parental separation, non-manual occupation of the mother, more than three children in the household, poor maternal mental health, lack of access to a car, and renting of accommodation. The child's illness had substantial effects on the activities of the mother and the rest of the family, but not on the child's social and recreational activities. Children with over 6 weeks' school absence scored appreciably worse on a teacher's assessment of their social, psychological, and educational adjustment.

Absenteeism↗
PubMed1983

Medical care of asthma and wheezing illness in children: a community survey.

A survey was carried out to investigate the medical care of asthma and wheezing illness in a school population. Children with current wheezing illness were identified by a screening questionnaire to the parents of 5100 children in one school cohort from all schools in an outer London borough. Of the 89% who responded, 11.1% reported wheezing within the past 12 months. Parents of a sample of 284 wheezy children aged about 9 were interviewed at home about their child's illness and the related use of drugs and services. There was evidence of substantial underuse of services and this was not associated with social, family, or general practice factors. Considerable proportions of children were not having drug treatment, were receiving only non-antiasthmatic drugs, or were using antiasthmatic drugs incorrectly. The most important social and family factor associated with undertreatment was poor maternal mental health, and this factor appeared to explain the observed association of manual social class with undertreatment. Only about half of the most severe group were labelled as having "asthma," and those with this label were more likely to be receiving treatment and using outpatient services. The results show that the potential of modern treatment to prevent disability due to wheezing illness is not being realised despite the existence of a free and accessible health service.

Absenteeism↗