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Biomedical subjects

M Lewis

Publications and source records attributed to M Lewis.

At least 91 records · Page 5Linked to original sources
PubMed1999

Direct mecA detection from blood culture bottles by branched-DNA signal amplification.

A branched-DNA (bDNA) signal amplification method was used to detect the mecA gene directly from blood culture broth growing staphylococci. BACTEC blood culture bottles with positive growth indices and containing staphylococcus-like organisms as shown by Gram stain were tested for the presence of the mecA gene. Comparison of test results was done among 225 patients (one blood culture from each patient). Compared with PCR, the sensitivity and specificity of the bDNA method are 100 and 99%, respectively. The bDNA test is carried out in a 96-well format and requires approximately 6 h to perform. Our preliminary results suggest that direct detection of the mecA gene by bDNA signal amplification is (i) sensitive enough to detect mecA directly from blood culture bottles without the requirement for subculture and (ii) as sensitive and specific as the PCR-based method.

Bacteremia↗
PubMed1999

North Staffordshire Community Beds Study: longitudinal evaluation of psychiatric in-patient units attached to community mental health centres. I: Methods, outcome and patient satisfaction.

BACKGROUND: This study evaluates two in-patient units attached to community mental health centres (CMHCs) that were designed to supplement acute in-patient care and to integrate with community-based after-care services. AIM: To examine the comparative outcome of patients with severe mental illness (SMI) admitted to the two units. METHOD: All patients with SMI admitted to the acute psychiatric wards serving the two CMHCs, those transferred to the community in-patient units and those admitted directly to these units (n = 110) were compared with patients (n = 67) admitted to acute wards serving two similar catchment areas without associated community beds. Baseline clinical and social measures were made and repeated at six and 12 months. Satisfaction with services was assessed at 12 months. RESULTS: The experimental group showed significantly better outcomes, significant reduction in unmet need and better satisfaction with services. CONCLUSIONS: The use of the community beds appears to have significant benefits for patients with SMI.

Adult↗
PubMed1999

North Staffordshire Community Beds Study: longitudinal evaluation of psychiatric in-patient units attached to community mental health centres. 2: Impact upon costs and resource use.

BACKGROUND: Innovative approaches to the provision of psychiatric care must justify their ability to improve the quality of life within the resource constraints imposed on psychiatry. AIMS: To examine the average costs per patient of the experimental and control group services. METHOD: An individual patient costing methodology that identified, measured and valued all public and private resources. RESULTS: The experimental group was more likely to remain in contact with services over a 12-month period, had fewer acute readmissions and spent less time in acute in-patient units. There were significantly different levels and patterns of resource consumption between the groups and between the two separate catchment areas. CONCLUSION: The cost analysis should be assessed in the context of the previous outcome analysis. It is likely, but not inevitable, that such units will increase the overall costs of care provision; this largely depends on the effectiveness with which such units are integrated into existing care provision.

Community Mental Health Services↗
PubMed1999

Options, outcomes, values, likelihoods decision-making guide for patients and their families.

When family caregivers are faced with making daily decisions, they may feel burdened, frustrated, and even in conflict with other family members. The OOVL Guide is a tool to help people think about the various aspects of a decision situation and combine them to make a decision. The OOVL Guide supports nurses in their advocacy role because it affirms the importance of the clients' values and preferences. The OOVL Guide provides decision-makers, both professionals and lay people, with a structure and procedure for making choices for themselves or others.

Activities of Daily Living↗
PubMed1999

Evaluation of the blue formazan spot test for screening glucose 6 phosphate dehydrogenase deficiency.

Several screening tests for glucose 6 phosphate dehydrogenase (G6PD) deficiency have been reported thus far, and a standardized method of testing was proposed by the International Council for Standardization in Hematology (ICSH). The screening test used in any particular laboratory depends upon a number of factors such as cost, time required, temperature, humidity, and availability of reagents. In this study, a direct comparison between three different G6PD screening methods has been undertaken. In 71 cases (50 hematologically normal volunteers, 9 hemizygous G6PD-deficient males, and 12 heterozygous deficient females), the blue formazan spot test (BFST) was compared with the conventional methemoglobin reduction test (HiRT) and the ICSH-recommended fluorescent spot test (FST-ICSH). In all cases, the results obtained with the three screening tests were correlated with the enzyme activity assayed spectrophotometrically. In hemizygous G6PD-deficient males, all cases were equally detected with the three methods: BFST (4.7-6.64, controls: 11.1-13.4), BMRT (score +3 in all 9 cases), and FST (no fluorescence in 9 cases). In heterozygous G6PD-deficient females, two methods detected 7 out of 12 cases (BFST: 8.71-11.75, controls: 11.1-13.4; and BMRT: score +3 in 7 cases), whereas the FST-ICSH missed all 12 cases that presented a variable degree of fluorescence. Although the sensitivity for G6PD-deficient carrier detection is the same for the BMRT and the BFST, the latter has the advantage of being semiquantitative and not merely qualitative. Unfortunately, none of the three screening tests compared here allowed the detection of the 100% heterozygote carrier state of G6PD deficiency.

Evaluation Studies as Topic↗
PubMed1999

Electrocardiography of southern elephant seal (Mirounga leonina) weanlings.

The mean values for amplitude and duration of electrocardiogram intervals, cardiac rhythm, and mean frontal plane QRS-axis were measured in 18 free-living weanling southern elephant seals (Mirounga leonina) anesthetized with tiletamine-zolazepam. Animals were 30-50 days old and had been weaned about 3 wk earlier. All animals had a normal sinus rhythm. The mean P-wave duration per animal had a range of 0.06-0.09 sec, and mean PR interval and QT interval ranges were 0.08-0.12 sec and 0.25-0.26 sec, respectively. The amplitude of the R wave was 0.22 mV in a VR and 0.5 mV in DI. The electrical axis was between -60 and +30 in 13 of the weanlings. Electrocardiograms were also obtained from five anesthetized juveniles and one adult female. The electrical axis of juveniles was between 0 and 120 , whereas the QRS vector for the adult female had an orientation of -150 . This report is the first detailed description of the southern elephant seal electrocardiogram.

Animals↗
PubMed1998

Functional identification of a fatty acid delta5 desaturase gene from Caenorhabditis elegans.

We have identified a cDNA from the nematode worm Caenorhabditis elegans that encodes a fatty acid delta5 desaturase. Saccharomyces cerevisiae expressing the full-length cDNA was able to convert di-homo-gamma-linolenic acid to arachidonic acid, thus confirming delta5 desaturation. The 1341 bp delta5 desaturase sequence contained an N-terminal cytochrome b5 domain and was located within a kilobase of the C. elegans delta6 desaturase on chromosome IV. With an amino acid identity of 45% it is possible that one of these genes arose from the other by gene duplication. This is the first example of a delta5 desaturase gene isolated from an animal.

8,11,14-Eicosatrienoic Acid↗
PubMed1998

Steroidogenic acute regulatory protein (StAR) is a sterol transfer protein.

Steroidogenic acute regulatory protein (StAR) plays a critical role in steroidogenesis by enhancing the delivery of substrate cholesterol from the outer mitochondrial membrane to the cholesterol side chain cleavage enzyme system on the inner membrane. A recombinant StAR protein lacking the first N-terminal 62 amino acid residues that includes the mitochondrial targeting sequence was shown to stimulate the transfer of cholesterol and beta-sitosterol from liposomes to heat-treated mitochondria in a dose-, time-, and temperature-dependent manner. A recombinant mutant StAR protein that cannot stimulate steroidogenesis by isolated mitochondria did not promote sterol transfer. Unlike the more promiscuous lipid transfer protein, sterol carrier protein 2 (SCP2), StAR did not stimulate phosphatidylcholine transfer in our assay system. The recombinant StAR protein increased cholesterol transfer to heat-treated microsomes as well as to heat- and trypsin-treated mitochondria. These observations demonstrate that StAR has sterol transfer activity, which may reflect an ability to enhance desorption of cholesterol from sterol-rich donor membranes. We suggest that the ability of StAR to promote sterol transfer explains its steroidogenic activity.

Animals↗
PubMed1998

The mechanism of action of steroidogenic acute regulatory protein (StAR). StAR acts on the outside of mitochondria to stimulate steroidogenesis.

Steroidogenic acute regulatory protein (StAR) plays an essential role in steroidogenesis, facilitating delivery of cholesterol to cytochrome P450scc on the inner mitochondrial membrane. StAR is synthesized in the cytoplasm and is subsequently imported by mitochondria and processed to a mature form by cleavage of the NH2-terminal mitochondrial targeting sequence. To explore the mechanism of StAR action, we produced 6-histidine-tagged N-62 StAR (His-tag StAR) constructs lacking the NH2-terminal 62 amino acids that encode the mitochondrial targeting sequence and examined their steroidogenic activity in intact cells and on isolated mitochondria. His-tag StAR proteins stimulated pregnenolone synthesis to the same extent as wild-type StAR when expressed in COS-1 cells transfected with the cholesterol side-chain cleavage system. His-tag StAR was diffusely distributed in the cytoplasm of transfected COS-1 cells whereas wild-type StAR was localized to mitochondria. There was no evidence at the light or electron microscope levels for selective localization of His-tag StAR protein to mitochondrial membranes. In vitro import assays demonstrated that wild-type StAR preprotein was imported and processed to mature protein that was protected from subsequent trypsin treatment. In contrast, His-tag StAR was not imported and protein associated with mitochondria was sensitive to trypsin. Using metabolically labeled COS-1 cells transfected with wild-type or His-tag StAR constructs, we confirmed that wild-type StAR preprotein was imported and processed by mitochondria, whereas His-tag StAR remained largely cytosolic and unprocessed. To determine whether cytosolic factors are required for StAR action, we developed an assay system using washed mitochondria isolated from bovine corpora lutea and purified recombinant His-tag StAR proteins expressed in Escherichia coli. Recombinant His-tag StAR stimulated pregnenolone production in a dose- and time-dependent manner, functioning at nanomolar concentrations. A point mutant of StAR (A218V) that causes lipoid congenital adrenal hyperplasia was incorporated into the His-tag protein. This mutant was steroidogenically inactive in COS-1 cells and on isolated mitochondria. Our observations conclusively document that StAR acts on the outside of mitochondria, independent of mitochondrial import, and in the absence of cytosol. The ability to produce bioactive recombinant StAR protein paves the way for refined structural studies of StAR and StAR mutants.

Animals↗
PubMed1998

Fas-induced proteolytic activation and intracellular redistribution of the stress-signaling kinase MEKK1.

The stress-activated protein kinase (SAPK, alternatively JNK) is activated rapidly by cell stress stimuli such as inflammatory cytokines and oxidative stress, and more slowly by the initiation of the apoptotic cell death response by events such as ligation of the Fas protein. Mitogen-activated protein kinase/Erk kinase kinase-1 (MEKK1) is an activator of SAPK, serving as a SAPK-kinase-kinase through intermediate phosphorylation of the SAPK kinase SEK1. By sequencing proteolytic cleavage products of MEKK1, we found that the proapoptotic protease caspase 3 (CPP32) cleaves MEKK1 after residue D68 both in vivo and in vitro. Cleavage of MEKK1 after D68 is blocked by viral and chemical protease inhibitors. Cleavage of MEKK1 at D68 changes the intracellular distribution of the protein from a Triton-insoluble compartment to a Triton-soluble compartment, reflected in a redistribution from a particulate to a diffuse cytoplasmic staining seen by immunofluorescence. Activation of both SAPK and MEKK1 after Fas ligation is prevented by both viral and chemical caspase 3 inhibitors, which in contrast fail to block activation of SAPK by rapidly acting cell stresses. Stress factor-induced SAPK signaling is not dependent on caspase 3 function. We propose that two mechanisms of stress signaling through MEKK1 exist. One is rapid, independent of proteases, and occurs in the particulate Triton-insoluble compartment. The other is more slowly activated and involves liberation of particulate MEKK1 by proteolytic cleavage and activation by caspase 3.

Animals↗
PubMed1998

Locomotor activity differences between sympatric patas monkeys (Erythrocebus patas) and vervet monkeys (Cercopithecus aethiops): implications for the evolution of long hindlimb length in Homo.

Homo erectus is notable for its taller stature and longer lower limbs relative to earlier hominids, but the selective pressures favoring such long limbs are unclear. Among anthropoid primates, patas monkeys (Erythrocebus patas) and extant hominids share several extreme characteristics involved with foraging and movement, including the relatively longest lower limb proportions, longest daily travel distances and largest home ranges for their body or group size, occupancy of some of the driest habitats, and very efficient thermoregulatory systems. We suggest that patas monkeys are an appropriate behavioral model with which to speculate on the selective pressures that might have operated on H. erectus to increase lower limb length. Here, in a comparison of the locomotor activities of patas monkeys and sympatric, closely related vervet monkeys (Cercopithecus aethiops), we provide evidence for the hypothesis that patas use their long stride more to increase foraging efficiency while walking than to run, either from predators or otherwise.

Animals↗
PubMed1998

Effects of regenerator geometry on pulse tube refrigerator performance.

This paper gives results of the cooling performance of a double-inlet pulse tube refrigerator using various regenerators. The same pulse tube was used for all the experiments and measured 4.76 mm in diameter and 46.2 mm in length. A commercial linear compressor with a swept volume of 4 cm3 was used in these experiments. The operating conditions were held constant at a mean pressure of 2.0 MPa and a frequency of 54 Hz. Using finite difference software called REGEN3.1, developed at NIST, and recent experiment results, we optimized a series of regenerators based on dimensions, materials and screen packing. The values used for calculating the thermal conduction through stacked screens by REGEN3.1 were based on recent experimental results from NIST. The regenerator tubes were designed using 316 stainless steel and titanium materials. The regenerator matrices investigated were 400-mesh and 500-mesh stainless steel screen. The valve settings for both orifices were adjusted to minimize the no-load temperature for all regenerators. A cooling capacity curve from 0 to 3 W was also determined. The performance of the pulse tube refrigerator using the different regenerators is discussed. The experimental results from the various regenerators are evaluated and compared with their corresponding numerically calculated coefficient of performance (COP) and regenerator design as determined by REGEN3.1.

Equipment Design↗
PubMed1998

Cognitive functioning in 8- to 18-month-old drug-exposed infants.

This study examined the cognitive functioning in 236 infants at 8 and 18 months of age. Thirty-seven infants were heavily exposed to cocaine in-utero, 30 were lightly exposed, and 169 were not exposed to cocaine. Cognitive functioning was evaluated with the Bayley Scales of Infant Development (2nd ed.; N. Bayley, 1993) at both ages. Infant information processing was also assessed with an infant-controlled habituation procedure. Results indicated that (a) infants of cocaine-abusing women had higher neonatal medical and environmental risk scores; (b) at 8 months, exposure groups did not differ in Psychomotor Development Index, Mental Development Index (MDI) scores, or recovery to a novel stimulus; and (c) infants heavily exposed to cocaine or high environmental risk had a decrease in MDI scores from 8 to 18 months. These results were obtained when neonatal medical and environmental risk, as well as polydrug exposure, were controlled.

Child Development↗