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Biomedical subjects

D Strickland

Publications and source records attributed to D Strickland.

At least 19 recordsLinked to original sources
PubMed1992

Smoking status and dietary fats.

BACKGROUND: There have been several recent reports of differences in the diet of smokers versus that of nonsmokers. This has broad implications for assessment of disease risk associated with diet or smoking. METHODS: We examined dietary fats for several categories of smoking status in a large cross-sectional data set. The annual risk factor survey of a cardiovascular disease prevention trial in three pairs of upper Midwest communities includes 3,495 subjects ranging in age from 24 to 75. Smoking was assessed by self-report and thiocyanate, and diet by the Willett questionnaire. Dietary comparisons of smokers, recent quitters, long-term (over 1 year) quitters, and never-smokers were conducted. RESULTS: Previous findings of lower polyunsaturated fat intake in smokers were confirmed and extended by finding significantly elevated polyunsaturate intake among those who had quit smoking within the last year. The source of these differences is unclear, but the differences are large enough to constitute a significant contribution to disease risk for smokers or a protective effect for recent quitters. CONCLUSIONS: Future research examining risks associated with smoking or diet should control for the interaction of the two factors. The dietary differences in recent quitters, whether caused by a conscious decision to improve diet, a change in taste perception as a result of quitting, or simply the habits of those smokers who are able to quit, need further exploration.

Adult↗
PubMed1991

The effect of cuff size on blood pressure measurement in adults.

We measured blood pressure differences by cuff size in 181 adults aged 25 to 74 years, allocated to a random sequence that involved the measurement of blood pressure using a small cuff, a large cuff, and an appropriate cuff as determined by standardized arm circumference measurement. Systolic and diastolic blood pressure were underestimated by 3-5 mm Hg in men and 1-3 mm Hg in women when the cuff was one size larger than appropriate. Systolic and diastolic blood pressure were overestimated by 2-6 mm Hg in men and 3-4 mm Hg in women when the cuff was one size smaller than appropriate. In addition, 30-40% of subjects were "misclassified" when blood pressure cutpoints were used to define hypertension.

Adult↗
PubMed1991

The characteristics of antigen define the cellular source and kinetics of histamine-releasing factor induced by human peripheral-blood mononuclear cells.

Peripheral-blood leucocytes from Dermatophagoides pteronyssinus- and/or Lolium perenne-allergic patients produce in vitro histamine-releasing factor (HRF) in an allergen-specific and concentration-dependent relationship. Maximum production of HRF occurred in cultures containing as little as 10-100 pg/ml crude allergen extract, although a second peak occurred at higher concentrations (10-100 micrograms/ml). While HRF was detectable in 1-hour cultures, maximal production required 24 h in culture. In contrast, HRF induced by streptokinase/streptodornase (SK/SD) was generally maximal after 1 h. Allergen-induced HRF production was almost exclusively associated with monocytes and B cells. In contrast, peripheral-blood T cells were the major source of induced HRF production in cultures containing SK/SD. Histamine-releasing cytokines are apparently produced by different cell populations, the activation of which may be dependent upon the characteristics of the stimulating antigen.

Allergens↗
PubMed1991

Immunoregulation of asthma: control of T-lymphocyte activation in the respiratory tract.

Allergic asthma results ultimately from inappropriate responses to non-pathogenic airborn antigens by the respiratory tract T-cell system. In order to understand how sensitization to inhaled antigens develops, it is necessary to precisely define the tissue microenvironments within which T-cells occur in the respiratory tract, and to analyse the factor(s) which regulate their local activation. This review focuses upon recent data on the distribution of T-cells and antigen presenting cells within the lung and airway tissues of man and experimental animals, and examines the available information on their responses to antigenic stimulation. We argue that in the steady state, respiratory tract T-cells are tightly regulated by a series of inherent and acquired immunosuppressive control mechanisms, which normally limit local T-cell activation to situations where antigenic exposure is accompanied by an inflammatory stimulus, such as the case with incoming pathogenic microorganisms.

Allergens↗
PubMed1990

The accuracy of portable cholesterol analyzers in public screening programs.

To determine the accuracy of portable cholesterol analyzers in public settings, four screening organizations were accompanied to cholesterol screenings where consenting participants completed the finger-stick procedure and provided a blood sample by venipuncture. The finger-stick values were compared later with the participants' blood cholesterol values obtained in a reference laboratory. The results indicated that only one of the organizations produced cholesterol measurements entirely within the acceptable range (+/- 14.2%), while the accuracy of the other three organizations ranged from 76.5% to 96.4%. Those finger-stick values that did not fall within the acceptable range tended to underestimate the laboratory cholesterol values. Additionally, classification of the persons screened based on the National Cholesterol Education Program risk categories indicated that the finger-stick values primarily tended to produce false-negative results. The variability of the results across organizations was caused partially by insufficient operator training. However, inadequate quality-control procedures for field settings and dilution of capillary blood by tissue fluid also may have contributed to the inaccurate finger-stick results.

Adolescent↗
PubMed1990

Development of an immunoaffinity process for factor IX purification.

An immunoaffinity process based on monoclonal antibody (MAb) to factor IX (FIX) has been developed. Initially, vitamin-K-dependent proteins from cryoprecipitate-poor plasma are isolated on DEAE-Sephadex. The eluate is applied to an immunoaffinity column that utilizes a divalent metal-ion-dependent MAb directed against FIX. After washing the column with high salt in the presence of magnesium ion, the FIX is eluted using a citrate- or EDTA-containing buffer. Coagulation assays and Western blots show no detectable amounts of any contaminating proteins. Purity of the FIX product is established using reduced and nonreduced Coomassie-stained SDS-PAGE and HPLC. The N-terminal 20 amino acids of the single peak of the HPLC were shown to be identical to those reported for FIX. The process shows no detectable leakage of monoclonal antibodies (MAb), efficient utilization of MAb, and provides yields greater than 95%. The use of solvent/detergent treatment as a potential viral inactivation methods is incorporated in the process. Studies with tritiated Triton X-100 indicate that the detergent can be washed out of the MAb column so that less than 1 ppm (total) Triton X-100 coelutes with the FIX.

Amino Acid Sequence↗
PubMed1990

Selective attrition of non-recirculating T cells during normal passage through the lung vascular bed.

Transient arrest of T lymphocytes in the lung vascular bed following infusion of cells subjected to in vitro manipulations has been recognized for many years as a troublesome 'artefact', and has generally been attributed to trauma-induced changes in lymphocyte surface membranes. However, a number of laboratories have reported that the trapping process also occurs under situations where lymphocyte surface damage is minimal or absent, suggesting that the phenomenon may represent an intrinsic component of normal lymphocyte circulation. Consistent with these suggestions, recent studies from our laboratory have demonstrated the presence of large numbers of T cells in collagenase digests of normal peripheral lung tissue, which cannot be removed by broncho-alveolar lavage or perfusion of the tissue vascular bed. In the present experiments we have characterized these lung T cells in SPF rats. The properties common to this population include hydroxyurea sensitivity, high CD8:CD4 ratio and high frequency of cells recently derived from the thymus, and saturation thymidine-labelling studies indicated that greater than 90% of the lung T cells had divided within a 14-day test period. Additionally, cloning studies under conditions of limiting dilution indicate markedly reduced capacity for proliferation, relative to T cells in blood or spleen. We interpret these data to indicate that selective trapping and subsequent down-regulation of non-recirculating T cells is a normal consequence of passage through the lung vascular bed.

Animals↗
PubMed1990

Hypertension Prevention Trial (HPT): food pattern changes resulting from intervention on sodium, potassium, and energy intake. Hypertension Prevention Trial Research Group.

The Hypertension Prevention Trial (HPT) was a multicenter randomized trial designed to assess the effects of long-term dietary changes on blood pressure in a normotensive population (diastolic blood pressure greater than or equal to 78 but less than 90 mm Hg) for a period of 3 years. The dietary treatments were reduction of sodium intake, increase of potassium intake, and decrease of energy intake. Estimates of changes in food intake were made by comparing 24-hour food records of the treatment and control participants. The participants in the treatment groups reported sodium intakes that were 30% to 40% lower than those of the controls. The restriction was achieved mainly by reducing intake of salt, meats, and grain products. Meats and grain products were still a major source of total sodium intake after treatment (41% to 47%), perhaps because of continued use of processed foods. Potassium intake was reported to be 16% to 25% higher in the treatment groups than in the controls, the increase achieved largely through increased consumption of fruits, with a lesser contribution from vegetables. Participants with higher initial body weights reported smaller increases in fruit and vegetable consumption than participants of normal weight, perhaps because of concerns about weight gain. Energy intake in the weight loss groups was 8% to 11% less than that of the controls. Men reported success in restricting calories from meats, dairy products, fats, beverages, and sugars. Women were less successful in restricting calories from most food groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Pressure↗
PubMed1989

Fetal monitoring and predictions by clinicians: observations during a randomized clinical trial in very low birth weight infants.

Predictions about perinatal outcome in very low birth weight infants were studied in a randomized clinical trial of electronic fetal monitoring and periodic auscultation to assess the effect of diagnostic monitoring information on clinicians' ability to predict perinatal outcomes. The only predictions consistently correct before monitoring information was available were those regarding infant survival (88% correct, kappa [kappa] = 0.40, P less than .001 for the electronic fetal monitoring group; 80% correct, kappa = 0.35, P less than .01 for the periodic auscultation group). After monitoring, predictions of 5-minute Apgar scores and arterial cord pH were significantly more accurate, and clinicians' confidence in their predictions increased significantly in both the electronic fetal monitoring and the auscultation groups. Predictions of 5-minute Apgar scores were significantly more accurate in the electronic fetal monitoring group (92% correct, kappa = 0.80) than in the periodic auscultation group (61% correct, kappa = 0.28) (Z difference = 3.04; P less than .01). We conclude that clinicians gain information during intrapartum monitoring that generally leads to improved predictions and increased confidence in predictions. In this study, they made more accurate predictions about 5-minute Apgar scores with electronic fetal monitoring, suggesting that electronic fetal monitoring may provide better information about neonatal well-being than does periodic auscultation. Improved information, as measured by clinical predictions, is probably highly valued by patients and clinicians and may be an important determinant of acceptance of this diagnostic technology.

Apgar Score↗
PubMed1988

The dynamic relations among interpersonal behaviors: a test of complementarity and anticomplementarity.

On the basis of the positions of behaviors relative to one another in the interpersonal circle, the principles of complementarity and anticomplementarity specify how people's behaviors influence one another in interpersonal interactions. Pairs of undergraduate women (1 subject, N = 80, and 1 confederate) collaborated for 16 min to create and agree on stories for two pictures. Confederates performed scripted roles that emphasized one of eight interpersonal behaviors. Behaviors were coded into eight categories, and the relative effect of each confederate behavior on each subject behavior was determined. Using the geometric properties of the interpersonal circle, vectors were calculated that identified the relative impact of each confederate stimulus behavior on the overall pattern of subject responses. Results were consistent with the dynamic relations among interpersonal behaviors that complementarity and anticomplementarity propose and demonstrated that how a person behaves toward another systematically and profoundly affects how the other behaves toward the person.

Adolescent↗
PubMed1987

A randomized trial of dexamethasone and acetazolamide for acute mountain sickness prophylaxis.

Forty-seven climbers participated in a double-blind, randomized trial comparing acetazolamide 250 mg, dexamethasone 4 mg, and placebo every eight hours as prophylaxis for acute mountain sickness during rapid, active ascent of Mount Rainier (elevation 4,392 m). Forty-two subjects (89.4 percent) achieved the summit in an average of 34.5 hours after leaving sea level. At the summit or high point attained above base camp, the group taking dexamethasone reported less headache, tiredness, dizziness, nausea, clumsiness, and a greater sense of feeling refreshed (p less than or equal to 0.05). In addition, they reported fewer problems of runny nose and feeling cold, symptoms unrelated to acute mountain sickness. The acetazolamide group differed significantly (p less than or equal to 0.05) from other groups at low elevations (1,300 to 1,600 m), in that they experienced more feelings of nausea and tiredness, and they were less refreshed. These drug side effects probably obscured the previously established prophylactic effects of acetazolamide for acute mountain sickness. Separate analysis of an acetazolamide subgroup that did not experience side effects at low elevations revealed a prophylactic effect of acetazolamide similar in magnitude to the dexamethasone effect but lacking the euphoric effects of dexamethasone. This study demonstrates that prophylaxis with dexamethasone can reduce the symptoms associated with acute mountain sickness during active ascent and that acetazolamide can cause side effects that may limit its effectiveness as prophylaxis against the disease.

Acetazolamide↗
PubMed1987

Status of infants at birth and risk for adverse neonatal events and long-term sequelae: a study in low birth weight infants.

We evaluated the relationship of infant status at birth to neonatal morbidity and long-term development in 246 low birth weight infants (600 to 1750 gm). Nineteen percent of infants had 1-minute Apgar scores of less than or equal to 3, and 8% had an umbilical artery pH of less than or equal to 7.2. Acidosis was associated with an increased risk of grade 3 to 4 intracranial hemorrhage (odds ratio = 3.3). Low 1-minute Apgar score was associated with an increased risk of death (odds ratio = 4.8). Grade 3 to 4 intracranial hemorrhage was a strong risk factor for cerebral palsy among survivors (odds ratio = 16.1), as was low 1-minute Apgar score (odds ratio = 2.9). Only 15% of cases of cerebral palsy in this study were associated with acidosis at birth.

Acidosis↗
PubMed1987

Health among municipal sewage and water treatment workers.

Municipal sewage treatment plant workers are potentially exposed to a multitude of industrial chemicals and pathogenic microorganisms. A questionnaire survey of working habits, lifestyle and symptoms of illness was conducted among 189 municipal sewage treatment plant workers processing between three and ten million gallons of wastewater daily in 16 plants in New York State between March and July of 1984. Water treatment plant workers in the same cities comprised the comparison group. Sewage workers reported a significantly higher frequency of headache, dizziness, sore throat, skin irritation and diarrhea within the month immediately preceding receipt of the questionnaire, after controlling for various possible confounders. Eye and skin irritation were significantly associated with exposure to mutagens. The health significance of these findings and possible sources of error in assessing risk are discussed.

Humans↗
PubMed1986

Urinary mutagens in municipal sewage workers and water treatment workers.

In view of the potential exposure of sewage treatment workers to a multitude of mutagenic substances, the frequency of urinary mutagens was measured by the Ames test among a sample of 164 sewage treatment workers employed in 14 sewage treatment plants which processed between 3 and 10 million gallons of sewage daily in New York State between March and July, 1984. The frequency was compared to that observed in 72 water treatment employees in the same municipalities. Sewage workers had a significantly higher risk for urinary mutagens after controlling for smoking, using the Ames test, both with and without the addition of the liver microsomal homogenate, S-9. More precise methods of measuring exposure in epidemiologic studies, particularly in environmental and occupational epidemiology, are in various stages of development. The application of one of these methods, the Ames test, to an occupational group (sewage workers) with potentially high exposure to mutagenic substances is described and the strengths and limitations of this application are discussed.

Adult↗
PubMed1986

Echocardiography, electrocardiography, and radiography of cats with dilatation cardiomyopathy, hypertrophic cardiomyopathy, and hyperthyroidism.

The echocardiographic, ECG, and radiographic findings of sequentially examined cats with dilatation cardiomyopathy (DCM, n = 7), hypertrophic cardiomyopathy (HCM, n = 8), and hyperthyroidism (HT, n = 20) were compared with those of healthy control cats (n = 11). Cats with DCM were easily differentiated from healthy cats by echocardiography and from cats with HCM and HT by a dilated left ventricle at end-diastole with a mean +/- SD of 2.20 +/- 0.36 cm, reduced fractional shortening (2.9% +/- 3.7%), reduced aortic amplitude (0.07 +/- 0.05 cm), reduced left ventricular wall amplitude (0.09 +/- 0.09 cm), and increased E-point septal separation (0.83 +/- 0.29 cm). The cats with HCM were most consistently recognized echocardiographically by increased left ventricular wall thickness at end-diastole (0.75 +/- 0.12 cm). Some cats with HT had abnormal echocardiograms with left ventricular wall hypertrophy. These cats could usually be differentiated from the cats with HCM because of normal or increased ventricular wall amplitude, aortic amplitude, or percentage of thickening of the left ventricular wall and interventricular septum. Left atrial enlargement (left atrial diameter greater than 1.57 cm or left atrium/aorta greater than 1.75) was commonly detected by the echocardiogram in cats with DCM, HCM, or HT. The echocardiogram was helpful in differentiating the type of cardiomyopathy (DCM, HCM, or HT) when plain thoracic radiographs indicated that cardiomegaly existed. The ECG may have indicated incorrectly that there was left ventricular enlargement in some cats with HT, and it did not indicate consistently that left ventricular enlargement existed when present in cats with DCM or HCM. The ECG was a poor indicator of left atrial enlargement in all cats.

Animals↗
PubMed1986

Repeatability of the M-mode echocardiogram and the effects of acute changes in heart rate, cardiac contractility, and preload in healthy cats sedated with ketamine hydrochloride and acepromazine.

In healthy cats sedated with a combination of ketamine hydrochloride and acepromazine, the reproducibility of sequential echocardiographic examinations was studied. The effects of experimental alteration in heart rate, contractility, and preload on the echocardiogram also were studied. Ten cats had M-mode echocardiograms recorded once weekly for 5 weeks. There were no statistically significant differences in echocardiographic measurements over time, although measurements of certain cardiac structures of an individual cat did vary from time to time. The cardiovascular system was altered by a constant infusion of isoproterenol, followed by a rapid intravenous infusion of isotonic fluid equal to 25% of the calculated blood volume, and then by a rapid withdrawal of blood equal to the amount of fluid previously given. Cardiac output using indocyanine green dilution curves were determined for each treatment and compared to the cardiac output calculated from the echocardiogram. The correlation coefficient was 0.90 for all treatments. During the infusion of isoproterenol a significant increase in the percent fractional shortening and left ventricular wall amplitude occurred compared to the control echocardiogram. After the rapid infusion of fluid, none of the mean echocardiographic measurements significantly changed from control values although the left ventricular chamber diameter at systole significantly increased, and the percent fractional shortening significantly decreased, when compared to values obtained during isoproterenol infusion. Significant changes recorded between echocardiographic measurements made after blood withdrawal compared to those made after fluid loading included an increase in left ventricular wall thickness at diastole, a decrease in left ventricular diameter at diastole, and a decrease in the present left ventricular wall thickening. Cats were terminated and the average of measurements made during the repeatability study of the septal and left ventricular wall thickness during systole, rather than during diastole, more closely approximated the postmortem measurements.

Acepromazine↗