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Biomedical subjects

M Bahl

Publications and source records attributed to M Bahl.

9 recordsLinked to original sources
PubMed2004

The public health response to a case of Lassa fever in London in 2000.

OBJECTIVES: Evaluation of the Department of Health 1996 guidance, the Memorandum on the Management and Control of Viral Haemorrhagic Fevers. METHODS: Description of the public health management in 2000 of the fifth UK patient confirmed to have Lassa fever. RESULTS: Delayed risk categorisation of the patient occurred for a variety of reasons. DH Guidance was followed once infection control advice was sought. Active surveillance of 125 contacts was extremely resource intense, involving over 3000 communications. Self-monitoring by healthcare workers should be considered in future. Advice on use of ribavirin prophylaxis is not included in the Memorandum, nor advice or templates for information sheets for contacts. Information sheets are now available from the Health Protection Agency in the event of future cases. International aspects not adequately addressed include the need for reliable risk assessment to be carried out before patients are medically evacuated from the country of origin, and the steps required to repatriate UK nationals. Effective and efficient communication is required between national and international organisations involved in such incidents. CONCLUSIONS: If guidelines are unclear or impracticable they will not be followed. It is important that lessons are learned and documented and that national guidance be regularly reviewed.

Communicable Disease Control↗
PubMed2004

Outbreak of isoniazid resistant tuberculosis in north London.

BACKGROUND: A description is given of a major outbreak of isoniazid monoresistant tuberculosis (TB) chiefly in north London, including prisons. The earliest case was diagnosed in 1995 with most cases appearing after 1999. METHODS: Confirmation of a local cluster of cases was confirmed by restriction fragment length polymorphism (RFLP IS6110) typing or "rapid epidemiological typing" (RAPET). Further cases were found by retrospective analysis of existing databases, prospective screening of new isolates, and targeted epidemiological case detection including questionnaire analysis. RESULTS: By the end of 2001, 70 confirmed cases in London had been linked with a further 13 clinical cases in contacts and nine epidemiologically linked cases outside London. The epidemic curve suggests that the peak of the outbreak has not yet been reached. Cases in the outbreak largely belong to a social group of young adults of mixed ethnic backgrounds including several individuals from professional/business backgrounds. Compared with other cases of TB reported to the enhanced surveillance scheme in London during 1999-2001, the cases are more likely to be of white (26/70 (37%) v 1308/7666 (17%)) or black Caribbean ethnicity (17/70 (24%) v 312/7666 (4%)), born in the UK (41/70 (59%) v 1335/7666 (17%)), and male (52/70 (74%) v 4195/7666 (55%)). Drug misuse and/or prison detention are factors common to many cases. CONCLUSIONS: The investigation of the outbreak revealed significant problems on an individual patient and population based level including difficulties with contact tracing, compliance, and the risk of developing multidrug resistance. This incident has demonstrated the value of molecular strain typing in investigating an extensive outbreak of TB. This is the first documented outbreak involving a UK prison.

Adolescent↗
PubMed2003

Nonlinear optical effects in a two-dimensional photonic crystal containing one-dimensional Kerr defects.

The nonlinear optical effects induced by a one-dimensional (1D) line defect, made of Kerr material, in a 2D photonic crystal are studied. Comprehensive ab initio numerical simulations based on the finite-difference time-domain method show efficient third-harmonic generation in a photonic crystal waveguide consisting of the 1D defect line. The relationship between the third harmonic generation process and the nonlinear modal properties of the waveguide is discussed. We investigate optical limiting in such a device, that is, control of the transmitted power as a function of the Kerr-induced variation of the refractive index. Power dependent spectral changes in such a device and its use as a frequency selector are also examined.

Journal Article↗
PubMed1999

[Experiences with loco-regional fibrinolytic therapy of deep venous thrombosis with defined drainage management].

From 1989 to September 1997 1184 patients with deep vein thrombosis were treated. 606 (51.2%) received a specific therapy with loco-regional lysis. The application of two cycles of 20 mg Alteplase within 8 hours prevailed in combination with 1000 IE heparin per hour. In absence or lack of therapeutical effect further cycles of 20 or 40 mg of Alteplase were given. In the time free from lysis the patients received 30,000 IE heparin/24 hours depending on the individual aPTT (1.5-2.5 times prolonged). We developed a special drainage-management using perforans-veins during the loco-regional lysis. Complete lysis resulted in nearly half of the cases and in another third there was a lysis of more than 50%. Complications were observed in 5.8% of the patients, 4% due to heparinization. Importantly no life-threatening bleeding like gastrointestinal or cerebral bleeding or pulmonary embolism occurred. According to our data we conclude that the loco-regional lytic effect tends to be better than using systemical lysis, the risks are minimized and patient monitoring and treatment is much simpler.

Aged↗
PubMed1992

Screening for Corynebacterium diphtheriae.

A throat swab from a 9 year old girl with pharyngitis yielded a non-toxigenic strain of Corynebacterium diphtheriae var mitis and Streptococcus group G. C pseudodiphtheriticum was isolated from the throats of two of her four brothers. In each case the isolate was sent to the reference laboratory before full identification. The growth was found to be mixed for one brother; the other isolate being a toxin producing C diphtheriae var gravis. The child was asymptomatic and the case proves that all colonial types on the Hoyles plate should be identified.

Child↗
PubMed1988

Analysis of the molecular specificities of anti-class II monoclonal antibodies by using L cell transfectants expressing HLA class II molecules.

Expressible HLA class II alpha- and beta-chain cDNA were used for DNA-mediated gene transfer to produce L cell transfectants expressing single types of human class II molecules. Cloned transfectants expressing nine different class II molecules were isolated: DR alpha: DR1 beta I, DR alpha: DR4 beta I, DR alpha: DR5 beta I, DR alpha: DR5 beta III (DRw52), DR alpha: DR7 beta I, DR alpha: DR4/7 beta IV (DRw53), DQ7 alpha: DQw2 beta, DQ7 alpha: DQw3 beta, and DPw4 alpha: DPw4 beta. These class II-expressing transfectants were used to analyze by flow cytometry the molecular specificities of 20 anti-class II mAb. These analyes indicate that some mAb are more broadly reactive than was previously thought based on immunochemical studies. In contrast, the narrow molecular specificities of other anti-class II mAb were confirmed by this approach. Transfectants expressing human class II molecules should be valuable reagents for studies of B cell and T cell defined epitopes on these molecules.

Animals↗
PubMed1988

A newly characterized HLA-DP beta-chain allele. Evidence for DP beta heterogeneity within the DPw4 specificity.

cDNA clones corresponding to the DPw4 alpha- and DPw4 beta-chains were isolated from a cDNA library prepared from a DPw4 homozygous cell line, their nucleotide sequences were determined, and the corresponding amino acid sequences were deduced. This DPw4 alpha-chain is identical to the conserved DP alpha-chains from DPw4 and DPw2 haplotypes, although the DPw4 beta-chain (referred to as DPw4b beta) differs from all reported DP beta-chain sequences. The DPw4b beta-chain differs from the reported DPw4 beta sequence (referred to as DPw4a beta) at three amino acid positions in the first domain (36, 55, and 56). The DPw4b beta-chain sequence differs from the DPw2 beta-chain sequence only at position 69 in the first domain, suggesting that the lysine at position 69 in DPw4b beta and the glutamic acid at position 69 in DPw2 beta contribute to the epitopes that define "DPw4-ness" and "DPw2-ness," respectively. In addition, the patterns of sequence identities and differences among the DPw4b beta-, DPw4a beta-, DPw2 beta-, and DPw3 beta-chains suggest that the DPw4b beta sequence arose via a gene conversion event or a point mutation. The I-LR1 mAb, which was previously found to bind only to DPw2, DPw3, and DR5 molecules, binds to an L cell transfectant expressing the DPw4 alpha:DPw4b beta molecule. The DPw4b beta sequence provides the first evidence for structural heterogeneity within the DPw4 specificity.

Amino Acid Sequence↗