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Biomedical subjects

K W Smith

Publications and source records attributed to K W Smith.

At least 19 recordsLinked to original sources
PubMed1992

Osmotic stress and the yeast cytoskeleton: phenotype-specific suppression of an actin mutation.

In the yeast Saccharomyces cerevisiae, actin filaments function to direct cell growth to the emerging bud. Yeast has a single essential actin gene, ACT1. Diploid cells containing a single copy of ACT1 are osmosensitive (Osms), i.e., they fail to grow in high osmolarity media (D. Shortle, unpublished observations cited by Novick, P., and D. Botstein. 1985. Cell. 40:415-426). This phenotype suggests that an underlying physiological process involving actin is osmosensitive. Here, we demonstrate that this physiological process is a rapid and reversible change in actin filament organization in cells exposed to osmotic stress. Filamentous actin was stained using rhodamine phalloidin. Increasing external osmolarity caused a rapid loss of actin filament cables, followed by a slower redistribution of cortical actin filament patches. In the recovery phase, cables and patches were restored to their original levels and locations. Strains containing an act1-1 mutation are both Osms and temperature-sensitive (Ts) (Novick and Botstein, 1985). To identify genes whose products functionally interact with actin in cellular responses to osmotic stress, we have isolated extragenic suppressors which revert only the Osms but not the Ts phenotype of an act1-1 mutant. These suppressors identify three genes, RAH1-RAH3. Morphological and genetic properties of a dominant suppressor mutation suggest that the product of the wild-type allele, RAH3+, is an actin-binding protein that interacts with actin to allow reassembly of the cytoskeleton following osmotic stress.

Actins↗
PubMed1992

Local excision of carcinoma of the rectum for cure.

During the past 10 years, we have treated 63 patients with invasive adenocarcinoma of the rectum by full-thickness local excision. Rigid criteria were employed in patient selection. None of the tumors was pedunculated or in situ carcinoma. Of the 63 lesions, 53 were confined to the bowel wall and constitute the basis for this report. Thirty-five lesions penetrated only the submucosa and 18 invaded the muscularis propria. Twenty-four patients underwent full-dose postoperative radiotherapy with minimal complications. Follow-up ranged from 12 to 130 months, with a median of 44 months. Four tumors recurred locally (8%). Of these, two patients apparently have been salvaged by reexcision. One patient died 32 months after abdominoperineal resection of brain metastases (without local tumor). One patient who did not receive close follow-up died of local recurrence. Seven have died of unrelated causes. The 5-year corrected disease-free survival is 90%. Local excision combined with radiotherapy for selected rectal cancers yields a high rate of cure with minimal morbidity and is now our preferred mode of treatment for all patients whose tumors meet our rigid criteria.

Adenocarcinoma↗
PubMed1991

Results of 1,000 single-layer continuous polypropylene intestinal anastomoses.

Between 1979 and 1988, we created intestinal anastomoses in 1,000 patients using a single-layer, continuous suturing technique and a polypropylene suture. The technique is easily learned, flexible in its application, and incurs less cost than most other techniques. The anastomoses involved all levels of the colon and the upper (intraperitoneal and extraperitoneal) rectum. All patients were followed for a minimum of 1 year. The clinically suspected anastomotic leak rate was 1%. Other morbidity included would complications (2%), obstruction of the small intestine (2%), anastomotic stricture (1%), and death (1%). No death was due to anastomotic complications. These rates of complications are comparable with, and in many instances lower than, those reported with other techniques of intestinal anastomosis.

Adolescent↗
PubMed1991

Sociocultural factors associated with smoking behavior by Puerto Rican adolescents in Boston.

This study examined cigarette smoking among Puerto Rican adolescents in the Boston area in its sociocultural context by describing who uses cigarettes, and by identifying factors that encourage or discourage cigarette use. The study, conducted from 1986-87, used two approaches. The first was to survey 605 Puerto Rican households with adolescents 11-20 years old. Households were identified from a random sample of census blocks in five neighborhoods. In each household, interviews were completed with one adolescent and his or her female caretaker. The second approach was to conduct ethnographic interviews with 40 adolescents selected through a purposive sample of survey respondents from three of the study neighborhoods. Bivariate and multivariate statistical analyses were used to examine the relationships between smoking behavior and characteristics of the adolescents. The results of these analyses were examined in light of the ethnographic data. Overall, 13.7% reported smoking in the month preceding the interview. Smoking was most prevalent among males 17-20. Patterns of smoking were associated with teens' social networks. The Puerto Rican adolescents in this study were more likely to smoke when their friends and household members smoked, if they participated in recreational activities such as sports or unsupervised games, and if they were not in school. These effects varied according to the gender of the respondent.

Adolescent↗
PubMed1991

Reliability and physiologic correlates of the Harvard Alumni Activity Survey in a general population.

The reliability of the Harvard Alumni Activity Survey (HAAS) and its association with physiologic measures was assessed in a large sample of men and women aged 25-65 years residing in the Boston metropolitan area in 1987. Reliability was estimated by comparing HAAS energy expenditure reports (kcal/week) from two separate interviews conducted 7-12 weeks apart. The test-retest reliability coefficient was 0.58 for the entire sample, but was considerably higher (r = 0.69) for those whose activity patterns had not changed from one interview to the next. HAAS self-reports were compared to two physiologic measures known to be affected by physical activity: high density lipoprotein cholesterol (HDLC) and body mass index (BMI). The natural logarithm of weekly HAAS expenditures was positively correlated with HDLC (r = 0.14, p less than 0.01) and negatively correlated with BMI (r = 0.13, p less than 0.01) for all respondents. These statistically significant associations persisted when adjusted for other covariates influencing physiologic status. The reliability coefficients and physiologic correlations for the HAAS in this sample are comparable to those reported for physical activity instruments requiring more intensive data collection and scoring procedures.

Adult↗
PubMed1991

Comparison of tidal ventilation and high-frequency jet ventilation before and after cardiopulmonary bypass in dogs using two-dimensional transesophageal echocardiography.

This study compared the use of high-frequency jet ventilation (HFJV) and tidal ventilation (TV) in a group of dogs with induced global myocardial ischemia before and after cardiopulmonary bypass. Transesophageal echocardiography was used to determine whether HFJV with its lower airway pressures could improve cardiac performance. The surgical procedure was separated into four study periods: closed chest before bypass, open chest before bypass, open chest after bypass, and closed chest after bypass. During each of these study periods, the dogs were randomly ventilated with alternate periods of TV and HFJV to maintain the PaCO2 at 34.3 +/- 3.3 mm Hg (mean +/- SEM). Cardiac output, stroke volume, systemic mean blood pressure, left ventricular ejection fraction, left ventricular end-diastolic volume, left ventricular dP/dt, left ventricular stroke work, and expiratory volumetric flows were higher during HFJV, whereas airway pressures and pulmonary vascular resistance were lower. Increases in cardiac output and stroke volume during HFJV were due to a combination of improved left ventricular contractility indicated by increased LV dP/dt and increased left ventricular end-diastolic volume accompanying decreased airway pressures. These data indicate that HFJV with its lower airway pressure is associated with significantly less impairment of cardiovascular function than TV in dogs with induced global myocardial ischemia.

Animals↗
PubMed1991

The validity of health risk appraisals for coronary heart disease: results from a randomized field trial.

BACKGROUND: While health risk appraisals (HRAs) are becoming increasingly popular as tools for health assessment and health education, comparatively little is known about the accuracy of these risk estimates. METHODS: A field trial among 732 randomly selected adults ages 25 to 65 years was conducted to assess the validity of the risk scores produced by four widely used HRAs. RESULTS: Self-reported HRA risk scores for cigarette smoking and relative weight were generally accurate, but correlations between physiological measurements and scores for blood pressure, cholesterol, and physical activity were always lower than .51. Correlations between epidemiologic estimates of the probability of CHD death and HRA total risk scores ranged from .13 to .75; partial correlations adjusting for age, race, and gender ranged from .12 to .47. CONCLUSIONS: The HRAs chosen for the field trial exhibited modest correlations with the CHD mortality risk predicted by the epidemiologic model. Mathematical errors made by respondents completing self-scored instruments and lack of knowledge regarding physiologic status decrease the accuracy of HRA risk estimates.

Adult↗
PubMed1991

Adolescent involvement in Kansas City gangs.

The authors present information to enlighten physicians on the subject of adolescent gang involvement. Discussion includes explanations of who gets involved in these gangs, why they get involved and why it is important to identify youths who may be involved with gangs.

Adolescent↗
PubMed1990

The validity of self-reported exercise-induced sweating as a measure of physical activity.

The validity of self-reported hours in which one engages in activities strenuous enough to produce sweating was assessed as a measure of physical activity. Respondents were 732 randomly selected adults between the ages of 25 and 65 years from the Boston, Massachusetts, metropolitan area who participated in a field trial of health risk appraisal instruments in 1987. A total of 68% of the men and 57% of the women in the sample were involved in sweat-inducing activities at least once per week. The correlation between the natural logarithm of reported sweat hours per week and energy expenditure measured by the Harvard Alumni Activity Survey was 0.39. Following a logarithmic transformation and adjustment for age and sex, sweat hours was significantly correlated with high density lipoprotein cholesterol (r = 0.11, p less than 0.05). However, these associations were not as strong as those found for the age- and sex-adjusted log of the Harvard Alumni Activity Survey score (r = 0.19 and r = -0.15 for high density lipoprotein cholesterol and body mass index (weight (kg)/height(m)2), respectively) and are considerably weaker than those reported in other studies using sweat episodes (days per week on which sweating occurred) as an indicator of physical activity. These results suggest that the utility of self-reported sweat hours may be limited to distinguishing active from inactive subjects in epidemiologic surveys.

Adult↗
PubMed1990

Perioral dermatitis with histopathologic features of granulomatous rosacea: successful treatment with isotretinoin.

A young woman with a persistent eruption of small granulomas about the mouth and chin was studied and granulomatous perioral dermatitis was diagnosed. Some authorities consider that perioral dermatitis is a circumscribed variant of rosacea; the findings in this case tend to show a relationship between the two conditions. Once conventional therapies failed to result in a response, the eruption cleared, leaving pitted, atrophic scarring after a twenty week course of isotretinoin treatment.

Administration, Oral↗
PubMed1989

Clinical evaluation of a Raman scattering multiple gas analyzer for the operating room.

A Raman spectrometer multiple gas analyzer was used to monitor inspired and expired concentrations of oxygen (O2), nitrogen (N2), carbon dioxide (CO2), nitrous oxide (N2O), halothane, and isoflurane in 10 patients. The Raman spectrometer and a dedicated mass spectrometer were connected to each patient to provide a comparison of the two instruments. Results show that readings from the Raman spectrometer are within 0.62 vol% of known gas standards for O2, N2, N2O; within 0.03 vol% for CO2; and within 0.04 vol% for halothane, enflurane and isoflurane. Clinical results show that Raman spectrometer readings are within 1.36 vol% of the mass spectrometer readings for O2, N2, N2O; within 0.01 vol% for CO2; and within 0.22 vol% for halothane and isoflurane. The clinical and laboratory results indicate the Raman spectrometer monitors airway gases and vapors as accurately as a dedicated mass spectrometer.

Anesthesiology↗
PubMed1989

The reliability of health risk appraisals: a field trial of four instruments.

A field trial was conducted to evaluate the reliability of four widely used health risk appraisals (HRAs). A total of 338 randomly selected adults aged 25 to 65 years residing in the Boston metropolitan area completed an HRA on two occasions seven to 12 weeks apart. Test-retest reliability was assessed by comparing self-reported baseline risk scores to follow-up scores for heart attack risk and selected coronary heart disease risk factors. Respondents generally gave consistent reports for family history, cigarette smoking, and relative weight (test-retest r greater than .75), but self-reported scores for physiologic status (blood pressure and cholesterol) and lifestyle (diet, physical activity, and stress) were much less stable. Coefficients for heart attack risk and appraised age ranged from .43 to .87 for the four HRAs. The reliabilities of two self-scored instruments were greatly reduced by mathematical errors made by respondents when computing their heart attack risk scores. These results were not affected by the length of the follow-up period (seven to 12 weeks).

Adult↗
PubMed1989

Accuracy of perceptions of heart attack risk: what influences perceptions and can they be changed?

Using perceived risk of a heart attack, we examined the relative importance of perceived risk factors and sociodemographic variables on subjects' perception of heart attack risk, the relationship between perceived and objectively measured heart attack risk, and the effect of health risk appraisal (HRA) feedback on risk perceptions. Data derive from a random sample of 732 Greater Boston, Massachusetts area men and women ages 25-65 years, who participated in a field trial of health risk appraisal instruments. At baseline and approximately two months later, all respondents completed a questionnaire assessing their own health-related behavior, risk factors, and perception of heart attack risk. At baseline, respondents also completed one of four HRA instruments. Physiologic measures of cholesterol, blood pressure, and weight were taken at either baseline or follow-up visit. Results showed that respondents used established risk factors in estimating overall risk; that compared to objective measures of risk, a high percentage of respondents displayed an optimistic bias; and that HRA feedback had some effect on perception of heart attack risk for those at high risk. Implications of these results for health promotion are discussed.

Adult↗
PubMed1988

The single-layer continuous polypropylene colon anastomosis. A prospective assessment using water-soluble contrast enemas.

Fifty consecutive unselected patients with anastomoses to the left side of the colon were studied. Each patient had an anastomosis constructed with a single layer of continuous 4-0 polypropylene. On the seventh postoperative day, or sooner, a water-soluble contrast enema was obtained to evaluate the integrity of the anastomosis. Two patients developed radiographic and clinical evidence of anastomotic leakage, and one patient developed a late pelvic abscess and colocutaneous fistula. The documented leak rate of 6 percent attests to the safety of this method of colonic anastomosis.

Adult↗
PubMed1988

Alateen.

Explore the source record for details and available documents.

Adolescent↗
PubMed1988

The influence of oral contraceptives on hormonal and metabolic homeostasis in young adolescents.

In order to evaluate the effects of oral contraceptives on metabolic and endocrine function in teenagers, Norinyl 1/50 was begun in 46 12-17-year-old girls after a 16-hour-fasting blood sample was obtained for glucose, insulin, glucagon, growth hormone, luteinizing hormone, follicle-stimulating hormone, thyroid-stimulating hormone, prolactin, gluconeogenic substrates, total lipids, and cholesterol. Sampling was repeated at 6 and 12 months of therapy. Of the 46 patients enrolled in the study, 23 returned for follow-up after 6 months, and 13 completed the study. Blood sampling after 6 and 12 months of therapy demonstrated no significant changes (p greater than 0.05). Our results suggest that there were no changes in the metabolic or endocrine functions studied at 6 and 12 months on a medium-dose contraceptive agent.

Adolescent↗
PubMed1988

QSAR studies of hydrazone uncouplers of oxidative phosphorylation.

Semiempirical molecular orbital calculations have been performed on a series of hydrazone uncouplers of mitochondrial oxidative phosphorylation which show insecticidal activity. Regression analysis yielded significant correlations between uncoupling activity, insecticidal potency and such physicochemical or theoretically-derived parameters as lipophilicity, pKa and atom charges.

Adenosine Diphosphate↗