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Biomedical subjects

M Stevens

Publications and source records attributed to M Stevens.

At least 37 records · Page 2Linked to original sources
PubMed1993

Altered lipid packing identifies apoptotic thymocytes.

To test whether apoptotic thymocytes can be identified by altered packing of lipids in their plasma membranes, thymocytes were isolated from mice injected with hydrocortisone and stained with merocyanine 540 (MC540), a fluorescent probe sensitive to lipid packing. At 9-10 h after injection, a subpopulation of H2-Klo cells with increased MC540 staining was clearly discernable. When DNA degradation was assessed by staining fixed cells with propidium iodide (PI), the fraction of cells with increased MC540 staining corresponded to the fraction with reduced PI staining. In addition, enriching for the former by fluorescence-activated cell sorting enriched for the latter. These results indicate that living apoptotic thymocytes can be identified and separated on the basis of altered lipid packing and increased staining with MC540.

Animals↗
PubMed1993

The effect of genetic and environmental factors on the prevalence of allergic disorders at the age of two years.

The effect of genetic and environmental factors on the prevalence of allergic disorders in early childhood was determined in a prospective follow-up study. Information was available on 1174 children at the age of 2 years. Two-hundred and seventy-five were considered to have an allergic disorder. The prevalence varied from 3.2% for rhinitis to 10.9% for asthma. At 2 years 60 children reacted positively on skin-prick test (SPT). Multivariate logistic regression analysis was used to obtain adjusted odds ratios (95% confidence interval) for each factor. For asthma, positive family history, male sex, low birth-weight, maternal smoking and season of birth were significant risk factors. For eczema, positive family history was the only significant risk factor. For rhinitis, lower socio-economic group and autumn birth were significant. Male sex and low birth-weight were significant for skin test positivity. Positive family history and low birth-weight were significant risk factors for any allergy. Low birth-weight was also a significant risk for skin test reactivity to house dust mite. Genetic and environmental factors have a profound effect on the development of allergic disorders in the first two years of life.

Child, Preschool↗
PubMed1993

Comparison of Signal and Bactec NR-660 blood culture systems.

The Signal blood culture system was compared with the Bactec NR-660. A total of 1617 blood culture sets yielded 143 (8.8%) significant isolates; 113 (79.0%) were from positive bottles in both the Bactec and Signal systems. Twelve organisms (8.4%) were detected and isolated from the Signal system only and another 18 (12.6%) from the Bactec system only. Of these 18, five were Signal-positive but the organism was not recovered and four organisms were isolated from negative Signal bottles on terminal subculture. The time taken to detection for each system was similar; the Signal system detected 68% and the Bactec 63% of significant positives within 24 h. At 48 h Bactec detected 91% and the Signal 85%. A significantly-reduced number of bottles which gave a positive signal but were negative by microscopical and cultural methods was found, compared with previous reports. The 1 h incubation period prior to the insertion of the Signal growth indicator device was considered to be the cause of this reduction in the proportion of false positives. Fifty-five percent (42/77) of the Bactec false positives were due to delta growth value. This is when there is an increase in the growth index of > or = 15 without the positive threshold level of 30 being attained. This occurred in the anaerobic bottle on day 2 with 42 bottles. Another 40% (31/77) of the false positives had a growth value between the positive threshold of 30 and a value of 35. Eighty (4.9%) of Bactec and 65 (4.0%) of Signal sets yielded clinically non-significant isolates.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Erythromycin induces supranormal gall bladder contraction in diabetic autonomic neuropathy.

Gall bladder motor function is impaired in some patients with diabetes. It has been suggested that the abnormalities of gall bladder motility are confined to those patients with autonomic neuropathy. Erythromycin, a motilin receptor agonist, causes gall bladder contraction in both normal subjects and patients with gall stones with impaired gall bladder emptying. The effect of erythromycin on gall bladder motility in seven patients with diabetes with an autonomic neuropathy, six patients with diabetes without autonomic neuropathy, and 17 normal subjects was studied using ultrasound. There was no significant difference in gall bladder fasting volume between the three groups, but the patients with diabetes with autonomic neuropathy had impaired postprandial gall bladder emptying compared with normal subjects (percentage emptied (SEM) 40 (10.3)% v 64 (2.8)%, p < 0.01) and those with autonomic neuropathy (48 (7.7)%, NS). Erythromycin produced a dramatic reduction in gall bladder fasting volume in patients with diabetes with an autonomic neuropathy, compared with either normal subjects or patients with diabetes without autonomic neuropathy (percentage reduction 62 (4.6)% in patients with autonomic neuropathy, v 37 (17.6)% in those without autonomic neuropathy, and 26 (7.3)% in the normal subjects, (p < 0.02) and returned gall bladder emptying to normal in all patients with impaired emptying. The pronounced effect of erythromycin in diabetic autonomic neuropathy suggests denervation supersensitivity and that the action of erythromycin on the gall bladder is neurally modulated.

Adult↗
PubMed1993

Evaluation of Questor urine screening system for bacteriuria and pyuria.

AIMS: To evaluate the Questor automated bacteriuria and pyuria screening system; to compare its performance with that of a reference method; and to assess its usefulness in a routine clinical laboratory. METHODS: The Questor urine screening system was compared with a comprehensive regimen to detect urinary tract infection, using pour-plate viable counts to determine the numbers of bacteria present in urine samples, a wide range of other cultural methods, microscopic findings and clinical information. RESULTS: The optimal performance in detecting significant growths was a sensitivity of 93%, a specificity of 74%, a positive predictive value of 43% and a negative predictive value of 98%. The list price per test is 0.17 pounds and the capital cost of the system is 39,950 pounds. Questor can test 50 samples an hour and can be operated by one member of the laboratory staff, who is not required to make interpretative judgments--for example, a medical laboratory assistant. CONCLUSIONS: The sensitivity and specificity of the Questor was better than that obtained from other screening systems using the same protocol. The system was easy to use and is a useful addition to the methods available for screening for bacteriuria.

Bacteriuria↗
PubMed1992

The role of hypotension in septic encephalopathy following surgical procedures.

To study the risk factors for septic encephalopathy, we reviewed a consecutive series of 84 patients with septic syndrome and multiple-organ failure. Septic encephalopathy developed in 14 of these patients. Univariate analysis revealed that severe hypotension was significantly associated with the development of septic encephalopathy. In stepwise multiple logistic regression analysis, no other variable made a significant contribution in the presence of severe cardiovascular failure. Septic encephalopathy may be related to ischemic damage rather than to metabolic causes.

Adult↗
PubMed1992

Immunoquantification of cytochrome P-450 3A on rat paraffin-embedded liver tissue.

The cytochrome P-450 3A family is involved in the metabolism of several drugs, including nifedipine, cyclosporine, quinidine and erythromycin. The purpose of this study was to develop a reliable method to obtain a relative quantification of cytochrome P-450 3A apoproteins in rat liver specimens by immunocytochemistry and to correlate such quantification to erythromycin N-demethylase activity, a biochemical pathway sustained by that enzymatic system. Thirty-six male Wistar rats were treated with an injection of either saline or dexamethasone phosphate (10, 30 or 50 mg/kg), a potent inducer of cytochrome P-450 3A. Specimens taken from the same lobe were processed for immunocytochemistry and determination of erythromycin N-demethylase activity. Paraffin sections were treated with a polyclonal antiserum directed against cytochrome P-450 3A. The density of cytochrome P-450 3A immunostaining measured by an automatic image analyzer increased with the dose of dexamethasone pretreatment, and with the erythromycin N-demethylase activity, both parameters being closely correlated. Our data indicate that in rats, when cytochrome P-450 3A is concerned, there is a close correlation between the results of immunoquantitation and biochemical activity. This suggests that such a method of investigation might be used on small paraffin-embedded liver specimens obtained by needle biopsy.

Animals↗
PubMed1992

Comparison of Sentinel and Bactec blood culture systems.

AIMS: To evaluate the Sentinel automated blood culture system and to compare its performance with that of Bactec. METHODS: The Sentinel blood culture system was evaluated in three centres. The performance of the system was assessed in comparison with the routine blood culture method used in these centres, the Bactec system. RESULTS: Blood culture sets (n = 2180) consisting of Sentinel aerobic and anaerobic, and Bactec aerobic and anaerobic bottles yielded 218 (10%) clinically important isolates. One hundred and fifty five (71%) of the isolates were detected by both systems; 35 (16%) were detected by Sentinel only; and 28 (13%) by Bactec only. For the duration of the evaluation, the Sentinel system was deliberately configured so that it was impossible to detect positive results during the first 12 hours. The times to positivity after the first 12 hours were similar. Data gathered during and subsequent to the evaluation have been used by the manufacturer to refine the algorithm so that positive results can be detected at a minimum of 2.25 hours. CONCLUSIONS: After a period of familiarization the Sentinel system was considered easy to use. Sentinel is a useful addition to the methods available for the detection of bacteria in blood cultures.

Bacteriological Techniques↗
PubMed1992

Drug screening of newborns by meconium analysis: a large-scale, prospective, epidemiologic study.

A large-scale, prospective drug screening of newborns by meconium analysis was done to determine more accurately the prevalence and epidemiologic characteristics of drug use in a high-risk urban, obstetric population. Every other neonate delivered in a perinatal center from November 1988 to September 1989 was prospectively enrolled and their meconium was analyzed by radioimmunoassay for the metabolites of three commonly abused drugs--cocaine, morphine (opiates), and cannabinoid. In 3010 subjects studied, 44% were positive for cocaine, morphine, or cannabinoid; 31% were positive for cocaine, 21% for morphine, and 12% for cannabinoid. In contrast, only 335 (11%) mothers admitted to illicit drug use: 52% of their newborns had a positive urine drug screen and 88% had a positive meconium drug screen. Prevalence of drug use among the pregnant women varied per month. A profile of the pregnant addict in the population studied was noted (P less than .001): service patient, single, multigravid (greater than 3), and little or no prenatal care. The major problems associated with drug use during pregnancy were principally noted in the group that was exposed to cocaine and opiates and in the group where the mothers admitted to the use of illicit drugs. On the other hand, a large number of neonates who have been exposed to drugs in utero, particularly those whose mothers denied the use of drugs, appear normal at birth and may not be recognized. Improved detection of these newborns at risk can be achieved with a high index of suspicion and meconium drug analysis.

Cannabis↗
PubMed1991

Falsely raised ankle/brachial pressure index: a method to determine tibial artery compressibility.

The ankle/brachial index (abPI) may be falsely raised, notably in diabetes, due to the relative incompressibility of the tibial artery. This paper presents a method of determining tibial artery compressibility by deriving abPIs with the patient supine and with legs raised in increments up to 0.55 m (ankle to heart). The effective negative hydrostatic pressure superimposed on the blood pressure at the ankle was converted to mmHg, normalised with respect to the brachial systolic pressure and then expressed as a hydrostatic pressure index (hPI). abPI was regressed on hPI and the gradient of the regression line calculated. If the arterial wall offers no significant resistance to compression the measured pressure will equal intraluminal pressure. In this case regression of the changing arterial pressure with the applied hydrostatic pressure would be expected to produce a gradient of -1. With resistance to compression the measured pressure is greater than the intraluminal pressure and a steeper gradient would be expected. The method was tested using age and sex matched groups, (A) controls (16 arteries), (B) patients with PVD and no diabetes (17 arteries), and (C) diabetics with PVD (34 arteries). There was no significant difference between the regression line gradients of groups A and B but both differ significantly from group C. The difference between the medians of groups B and C was 0.46, the 95% confidence interval for the difference being 0.66 to 0.02. Twelve of the diabetic arteries had a gradient steeper than -1.8 compared with one from group (B) and none from group (C).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1991

Cord serum IgE: an insensitive method for prediction of atopy.

Cord total serum IgE has been advocated as a screening test to detect infants at high risk of allergy who would be suitable for preventive measures. In a population based prospective study to look at the predictive capacity of cord IgE and family history of atopy 1111 one-year-old infants were followed-up. Cord IgE was measured using the EIA ultra technique (Pharmacia, Uppsala, Sweden). Atopic symptoms developed in 255 (23%) at one year, 183 (16.5%) had probable atopy (clinical disorder but negative skin prick test (SPT)) and 72 (6.5%) had definite atopy (clinical disorder with positive SPT). There was no difference in the mean cord IgE levels in infants with or without atopic manifestations. The cut-off for IgE was taken at 0.6 ku/1. The specificity of the test was 92% but the sensitivity was only 8.5%. The positive and negative predictive values were 24% and 78% respectively. Family history of atopy is far more sensitive in detecting infants at risk of atopy and little is added by knowledge of cord IgE.

Asthma↗
PubMed1991

A controlled trial of colchicine to reduce the elastase load in the lungs of ex-cigarette smokers with chronic obstructive pulmonary disease.

A great deal of experimental evidence suggests that emphysema in smokers is caused by the action of neutrophil elastase on lung elastin. In order to test this hypothesis, it is necessary to find a drug that reduces the load of neutrophil elastase in the lungs of patients with emphysema. In a previous study we treated smokers with emphysema with colchicine, a drug that prevents neutrophil elastase secretion, to determine if it would reduce the elastase burden in the lungs. Colchicine was unable to reduce the elastase load while the stimulus of smoking continued. In this study we treated ex-smokers with emphysema to determine if colchicine could reduce the elastase burden in the lungs. The objective of the study was to determine if colchicine can reduce the elastase load and putative indicators of elastase load in the lungs of patients with chronic obstructive pulmonary disease. The study was a prospective, double-blind, randomized, and placebo-controlled clinical trial. The subjects were outpatients seeking treatment at the University of Texas Health Center at Tyler. We studied 16 ex-cigarette smokers between 45 and 75 yr of age with lung disease defined by FEV1 less than 70% of predicted but greater than 1.2 L whose airflow obstruction was less than 20% reversible with bronchodilators. Colchicine or placebo was taken by mouth in disguised capsules, 0.6 mg three times per day. Volunteers were placed on a baseline bronchodilator regimen of theodur by mouth and albuterol by inhalation. Blood, urine, and bronchoalveolar lavage fluids were obtained after 1 wk of stabilization.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1991

Prevalence and correlates of alcohol use in a survey of rural elementary school students: the New Hampshire study.

Alcohol use by 1190 fourth, fifth and sixth grade students was assessed in a survey of four rural New Hampshire school districts. Half the students surveyed (596) drank, but not regularly; 5 percent (59) were regular drinkers, and an additional 2 percent (19) were regular drinkers and had been drunk at least once. Reported alcohol use increased with both grade and age, and males drank more than females. The child's attitude toward drinking, perceived family attitudes towards drinking, the number of drinking friends, and self-perceived wrongdoing by the child were four factors strongly related to alcohol use. Increased alcohol use was also associated with experimental and current use of cigarettes, marijuana, and smokeless tobacco.

Adolescent↗
PubMed1991

Detection of Staphylococcus aureus in blood cultures: evaluation of a two-hour method.

Aurease--one of three tests on the RAPIDEC staph system for two-hour identification of the main clinically important staphylococci--was used for the direct detection of Staphylococcus aureus from 102 blood culture broths in which Gram-positive cocci were seen. A pellet of centrifuged blood culture broth was used as the inoculum. The method was compared with the thermonuclease test and subsequent isolates subjected to probabilistic identification based on biochemical reactions. A positive aurease test and the presence of thermonuclease were detected in 27 samples, subsequent identification showing all to be Staph. aureus. A further Staph. aureus strain was aurease negative but thermonuclease positive. None of the remaining 74 specimens was positive by the aurease test, which is rapid, sensitive and specific for detection of Staph. aureus in blood culture broths.

Bacteriological Techniques↗
PubMed1991

A rapid test to detect the most clinically significant Staphylococcus species.

A new two-hour test system (RAPIDEC staph) to detect the main staphylococci was evaluated. Of 124 reference strains tested, 83 represented species most often found in clinical specimens, the remaining 41 strains representing five species primarily of animal origin. RAPIDEC staph detected all Staph, aureus, Staph. epidermidis and seven of eight Staph. saprophyticus strains. Of the animal species, all Staphylococcus intermedius strains were assigned to the correct category, the remainder were misidentified as Staph. epidermidis. With 121 catalase-positive Gram-positive cocci isolated from urines the test system correctly detected all Staph. aureus strains, 39 of 41 Staph. epidermidis, and 34 of 36 Staph. saprophyticus. Of 25 atypical Staph. aureus strains which were either slide or tube coagulase negative the test system correctly detected all 17 slide coagulase negative strains but failed to detect eight which were tube coagulase negative. There were no false positives. RAPIDEC staph is a rapid, accurate system for the detection of the three main clinically important species of staphylococci.

Bacteriological Techniques↗