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Biomedical subjects

S S Tai

Publications and source records attributed to S S Tai.

14 recordsLinked to original sources
PubMed1997

Characterization of hemin binding activity of Streptococcus pneumoniae.

Streptococcus pneumoniae is a causative agent of bacterial pneumonia, otitis media, meningitis, and bacteremia. It causes considerable morbidity and mortality throughout the world, especially among children, the elderly, and immunocompromised individuals. We have demonstrated previously that the growth of S. pneumoniae is limited under iron-depleted conditions and can be restored by the addition of either hemin or hemoglobin. In the present study, we showed that S. pneumoniae had the ability to bind hemin and that the level of hemin binding activity was not affected by supplementation of the growth medium with iron. Approximately 70 to 80% of the hemin binding activity was mediated by proteinase-resistant components, and the remainder was mediated by proteins. Hemin binding proteins were located in both soluble extract and envelope fractions of pneumococcal cells. By batch affinity chromatography, a major hemin binding polypeptide with an apparent molecular mass of 43 kDa was identified in the cell lysate of S. pneumoniae. Polyclonal antibodies against this polypeptide were raised. By immunoblot analysis, this hemin binding polypeptide was localized in the envelope and did not exhibit any variation in molecular weight among all serotypes tested. The subcellular distribution of hemin binding activity may have functional implications.

Carrier Proteins↗
PubMed1996

Monitoring psychosis in general practice: a controlled trial.

BACKGROUND: This trial evaluated the feasibility, acceptability and effectiveness of a structured approach to the management of schizophrenia in general practice. METHOD: All patients with non-affective psychosis (mainly schizophrenia) in four inner-city general practices were recruited. A check-list and a set of outcome measures were used by the general practitioner and the practice nurses. Information on attendances at the general practice and psychiatric out-patient departments was also collected. RESULTS: Two practices took part in the intervention and two served as control practices. Sixty-seven patients with non-affective psychosis were identified. Thirty-three (81%) of the 41 patients in the two intervention practices attended the initial assessment by the doctor and nurse, but only 13 (32%) attended the first review assessment. The attendance for the second review, after six months, was six out of 15 (40%) in one practice, but rose to 16 out of 18 (89%) in the other practice. Significant improvements were recorded in the intervention group on the Global Assessment Scale (GAS) and the Behaviour, Speech and Other Syndromes (BSO) subscore of the Present State Examination (PSE). The absolute risk reduction and relative risk reduction as a result of the intervention, as measured by the GAS scores, was 29% (95% CI 4% to 54%) and 36% (95% CI 5% to 66%), respectively, and in the case of the BSO subscores of the PSE, this was 23% (95% CI-1.8% to 47.2%) and 28% (95% CI-2.2% to 57%), respectively. For one patient to show an improvement in GAS and BSO scores 3.5 patients (95% CI 1.85 to 25) and 4.3 patients (95% CI-55 to 2.1), respectively, would need to receive the intervention. There was a significant increase in consultation rates for patients in the intervention practices. CONCLUSIONS: Health surveillance of patients with non-affective psychosis is possible in general practice.

Adult↗
PubMed1995

Cloning of a Corynebacterium diphtheriae iron-repressible gene that shares sequence homology with the AhpC subunit of alkyl hydroperoxide reductase of Salmonella typhimurium.

To understand how Corynebacterium diphtheriae responds to iron limitation, we compared the sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) protein profiles of both wild-type cells and iron uptake mutants grown in either high- or low-iron medium. The removal of iron by ethylene diamine di-(o-hydroxy-phenyl acetic acid) from the growth medium of wild-type cells resulted in induction of at least 14 polypeptides. DirA, a major iron-repressible polypeptide, was purified from wild-type cells by preparative SDS-PAGE, and the dirA structural gene was isolated from a genomic library of nontoxigenic C. diphtheriae. The nucleotide sequence of dirA was determined, and the deduced amino acid sequence of DirA revealed strong homologies with the AhpC subunit of Salmonella typhimurium alkyl hydroperoxide reductase and polypeptides of other microorganisms associated with oxidation reduction activity. Like AhpC, cloned DirA reduced the susceptibility of an Escherichia coli ahp mutant to cumene hydroperoxide, suggesting that DirA has alkyl hydroperoxide reductase activity.

Amino Acid Sequence↗
PubMed1993

Hemin utilization is related to virulence of Streptococcus pneumoniae.

Streptococcus pneumoniae is a causative agent for bacterial pneumonia, otitis media, meningitis, and bacteremia. Mechanisms for acquisition of iron by this organism under low-iron conditions were investigated. Siderophore production was not detected by either chemical or biological methods. Its utilization of iron-containing compounds found in human hosts was tested. Both hemin and hemoglobin supported the full growth of S. pneumoniae in a culture lacking other iron sources, while lactoferrin and transferrin failed to do so. A mutant defective in hemin utilization was isolated and was less virulent than wild-type S. pneumoniae in experimental animals.

Animals↗
PubMed1993

Assessment of elderly people in general practice. 4. Depression, functional ability and contact with services.

The aim of this study was to look at the interrelationship between depression, physical disability and contact with services. In a random sample of 239 people aged 75 years and over from nine general practices in north London, depression (as measured by a shortened version of the comprehensive assessment and referral evaluation schedule) was found to be significantly associated with being a woman, and inability to perform a number of activities of daily living. Consumption of three or more prescribed medicines, a home visit by the general practitioner in the previous three months and contact with health visitors and home helps were all significantly more likely among depressed patients. There were also significant associations between loss of functional abilities, measured using items from an activities of daily living scale, and use of certain services: general practitioner home visits and reduced mobility indoors and both home help and district nurse visits to those with difficulty in bathing. Multiple logistic regression analysis suggested that contact with services was principally associated with loss of mobility, although contact with home helps was independently associated with depression, when adjustment was made for functional impairment.

Aged↗
PubMed1992

Are elderly people living alone an at risk group?

OBJECTIVE: To test the hypothesis that elderly people living alone are an at risk group with a high level of morbidity that makes high demands on health and social services. DESIGN: Secondary analysis of data from a community survey of 239 people aged 75 and over, identified from general practitioners' age-sex registers. SETTING: Nine practices in the London boroughs of Brent and Islington. MAIN OUTCOME MEASURES: Scores on the mini-mental state examination; stated satisfaction with life; assessment of mobility; numbers of diagnoses of major physical problems; numbers of prescribed drugs taken; urinary incontinence; alcohol consumption; contacts with general practitioners and hospital outpatient and inpatient services; contact with community health and social services. RESULTS: There were significantly more women among those living alone (93/120 (78%) v 63/119 (53%); p < 0.0005) and the median age of elderly people living alone was higher (81 v 80; p < 0.04). Those living alone and those living with others showed no significant differences in measures of cognitive impairment, numbers of major physical diagnoses, impaired mobility, or use of general practitioner or hospital services. Stated satisfaction with life was somewhat higher in those living alone. Elderly people living alone were significantly more likely to have contact with chiropody, home help, and meals on wheels services and less likely to have someone they could contact in an emergency or at night. Living alone increased the likelihood of contact with one or more community health professionals (district nurses, health visitors, or chiropodists) considered as a group and also increased the likelihood of contact with social services as a whole. There was a tendency for more of those living alone than those living with others to have home visits from their general practitioners, but there were no significant differences in contact with hospital services between the two groups. CONCLUSIONS: Elderly people living alone do not have an excess of morbidity compared with those living with others and do not seem to be an at risk group requiring specifically targeted assessments. More help is needed to provide elderly people living alone with a point of contact in case of emergency.

Aged↗
PubMedDate not supplied

The certification of cocaine and benzoylecgonine in a human urine standard reference material.

The concentrations of cocaine and benzoylecgonine (BE) in Standard Reference Material (SRM) 1508, cocaine and metabolites in freeze-dried human urine, were determined at the National Institute of Standards and Technology (NIST, formerly NBS) by two independent methods. For cocaine, one method was based on gas chromatography/mass spectrometry (GC/MS); the other was based on high-performance liquid chromatography (HPLC). For BE, one method was based on GC/MS; the other was based on flow injection analysis/thermospray mass spectrometry (FIA/MS). The results for each pair of methods were statistically evaluated. Concentrations were determined in the SRM for three levels of cocaine and three levels of benzoylecgonine. Methylecgonine, although present in the material, was not determined. For cocaine, the concentrations were 90, 263, and 429 ng/mL of human urine. For BE, the concentrations were 103, 259, and 510 ng/mL of human urine.

Chromatography, High Pressure Liquid↗
PubMedDate not supplied

The certification of morphine and codeine in a human urine standard reference material.

The National Institute of Standards and Technology (NIST, formerly the National Bureau of Standards) has developed and certified a Standard Reference Material, SRM 2381, for use in testing for bias in determinations of morphine and codeine in human urine. Each unit of this SRM consists of three vials with different levels of morphine and codeine in lyophilized urine. Three different analytical methods, employing GC/MS, LC/MS, and MS/MS, were used to certify the concentrations of each analyte. Results from the three methods were in good agreement and, therefore, were statistically combined to yield certified values of 138, 293, and 578 ng/mL for morphine and 134, 283, and 591 for codeine. A round-robin study on this material among nine military laboratories demonstrated the suitability of the SRM for its intended purpose.

Chromatography, Liquid↗
PubMedDate not supplied

Certification of phencyclidine in lyophilized human urine reference materials.

The National Institute of Standards and Technology (formerly the National Bureau of Standards), in cooperation with the College of American Pathologists (CAP), has certified the concentrations of phencyclidine (PCP) in two new reference materials (RMs). One of these materials is Standard Reference Material (SRM) 1511, Multidrugs of Abuse in Freeze-dried Urine, and the other material is a CAP PCP RM. In order to minimize the possibility of undetected bias, two independent analytical methods, employing gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry, were used to certify PCP in these materials. Results from the two methods were in good agreement and were statistically combined to yield certified values of 23.8 ng/mL for PCP in SRM 1511 and 11.9, 23.4, and 49.5 ng/mL for three levels of PCP in the CAP RM. A round-robin study of SRM 1511 among five military laboratories demonstrated the suitability of the SRM for its intended purpose.

Gas Chromatography-Mass Spectrometry↗
PubMedDate not supplied

Determination of pyrantel in swine liver by flame ionization gas chromatography and confirmation by gas chromatography/mass spectrometry.

During an evaluation of the gas chromatography/mass spectrometry (GC/MS) confirmatory procedure of Lynch and Bartolucci for pyrantel residues in swine tissues, we developed a GC flame ionization method for quantitating pyrantel residues in extracts of swine liver. The method was subjected to trial principally in the laboratories of Biospherics, Inc., using control liver, fortified control liver, and incurred liver tissue samples. Although the method does not meet all of the current Food and Drug Administration criteria, it compares favorably to the official determinative method. Portions of the same extract can be used for quantitation and for GC/MS confirmation, true recoveries appear to be slightly higher, and an internal standard is not required. The precision of this method equals or exceeds that of the official determinative method.

Animals↗
PubMedDate not supplied

Determination of thiabendazole, 5-hydroxythiabendazole, fenbendazole, and oxfendazole in milk.

The liquid chromatographic determination previously developed for benzimidazoles in cattle liver has been slightly modified and applied to the determination of 4 benzimidazoles in milk. Recoveries of fenbendazole (FBZ), oxfendazole (OFZ), and thiabendazole (TBZ) from milk fortified at the 10 ppb level were 80% or greater with an intralaboratory coefficient of variation of 11% or less. Recovery of 5-hydroxythiabendazole (5-OH-TBZ) at the 30 ppb level averaged 56% with an intralaboratory coefficient of variation of 5%. Limited data on the depletion of FBZ, OFZ, TBZ, and 5-OH-TBZ in milk were also generated.

Animals↗