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Biomedical subjects

K Mills

Publications and source records attributed to K Mills.

At least 73 records · Page 4Linked to original sources
PubMed1996

Testing of Mycobacterium tuberculosis susceptibility to ethambutol, isoniazid, rifampin, and streptomycin by using Etest.

Etest (AB BIODISK, Solna, Sweden) is a precise MIC method and the practical method of choice for the susceptibility testing of many fastidious organisms, including rapidly growing mycobacteria. Methods recommended by the National Committee for Clinical Laboratory Standards for the susceptibility testing of Mycobacterium tuberculosis include the Bactec (Becton Dickinson, Sparks, Md.) broth and agar proportion methods. A comparison of Etest with the Bactec broth method for testing the susceptibility of M. tuberculosis to four first-line antituberculous agents demonstrated equivalent interpretive results for 100% of the isolates tested. Agreements with agar proportion MICs, within +/-2 log2 dilutions, were 90, 93, 100, and 94% for ethambutol, isoniazid, rifampin, and streptomycin, respectively. Etest MICs were easily read within 5 to 10 days of inoculation. Preparation of the inoculum with a turbidity equivalent to a McFarland 3.0 standard prepared from growth on an agar surface and with a broth with a Bactec growth index of > 999 yielded equivalent results. Clinical isolates for which the MICs were reproducible were also identified as possible quality control strains. The Etest method appears to be an alternative method for testing the susceptibility of M. tuberculosis isolates to the four most commonly used therapeutic agents.

Antibiotics, Antitubercular↗
PubMed1996

First trimester prenatal diagnosis of Smith-Lemli-Opitz syndrome (7-dehydrocholesterol reductase deficiency).

In Smith-Lemli-Opitz syndrome (SLOs), 7-dehydrocholesterol (7-DHC) accumulated because there is a block in the pathway for synthesis of cholesterol via 7-DHC. Prenatal diagnosis of SLOs has been achieved by analysis of 7-DHC in amniotic fluid obtained at 16-18 wk from pregnancies at risk. The purpose of this study was to investigate 7-DHC and cholesterol concentrations in chorionic villus (CV) samples with a view to performing first trimester prenatal diagnosis. Using a sensitive gas chromatography-mass spectrometry assay it was possible to detect 7-DHC in CV samples obtained as early as 7 wk of gestation. The ration of 7-DHC to cholesterol in placental tissue was shown to be relatively constant over the gestational period of 7-18 wk. We therefore proceeded to analyze the 7-DHC/cholesterol ration in CV samples taken at 10-12 wk of gestation from three pregnancies at risk for SLOs. The results were as follows: patient A, 1.10 x 10(-3); patient B, 1.80 x 10(-3); patient C, 0.091; control range for CVS (8-12 wk), 3.10 x 10(-4) to 1.62 x 10(-3) (mean +/- 2SD; n = 5). The fetus of patient C was diagnosed as affected by SLOs, and the parents requested termination. Analysis of cultured skin fibroblasts confirmed the diagnosis. Pregnancies A and B were diagnosed unaffected, and this was confirmed first by amniocentesis and then by the birth of normal infants at term. We conclude that synthesis of cholesterol via 7-DHC is occurring in the placenta and/or fetus at 10 wk of gestation and that prenatal diagnosis by CV biopsy is possible.

Amniocentesis↗
PubMed1996

Investigating and improving the specificity of ribozymes directed against the bcr-abl translocation.

Chronic myelogenous leukaemia (CML) is associated with a translocation between the ABL and BCR genes on chromosomes 9 and 22, t(9;22). The resulting transcription and translation products, bcr-abl mRNA and p210bcr-abl, are unique to the malignant cells and as such are ideal targets for specific chemicals or drugs. We have designed hammerhead ribozymes to cleave the two predominant forms of bcr-abl mRNA, b2a2 and b3a2. Synthetic bcr-abl RNA substrates were cleaved by the ribozymes in vitro, but so was a wild-type abl RNA sequence. bcr RNA was not cleaved in vitro and mutant ribozymes showed no cleavage activity. Ribozymes designed to cleave 9 nucleotides (nt) from either of the fusion points were non-specific for the bcr-abl substrate, but a ribozyme designed to cleave 3 nt upstream of the b3a2 fusion point was specific for b3a2 RNA. However, this ribozyme was less efficient than the others. The shortening of one of the ribozymes arms from 10 nt to 4 nt resulted in a ribozyme that was more specific without losing any efficiency. We conclude that it is possible to specifically cleave bcr-abl RNA in vitro by using hammerhead ribozymes.

Base Sequence↗
PubMed1995

Changing p53 mutations with the evolution of chronic myeloid leukaemia from the chronic phase to blast crisis.

The frequent involvement of chromosome 17p abnormalities in the progression of chronic myeloid leukaemia (CML) led us to investigate the involvement of the p53 tumour suppressor gene located on chromosome 17p. We analysed 31 samples from four patients sequentially, and 16 patients in blast crisis only, using single stranded conformational polymorphism (SSCP) analysis of exons 5-8, followed by cloning and sequencing. The sequential samples ranged from diagnosis through to late disease. We found that 15% of our blast crisis samples had p53 abnormalities. In our sequential studies we found two of the four patients analysed in more detail had p53 mutations in the late chronic phase of disease (11 and 5 months prior to blast crisis becoming apparent). These chronic phase mutations differed from the p53 abnormalities found in the blast crisis samples from these patients. One patient also had the same chronic phase mutation at post bone marrow transplant relapse. Our results suggest that, in some cases, sequential investigations through CML disease progression of p53 mutations and other oncogenes/proto-oncogenes may provide early indications of the routes of disease progression to blast crisis.

Base Sequence↗
PubMed1995

Neutrophil-macrophage interaction: a paradigm for chronic inflammation.

Autoimmune diseases, such as rheumatoid arthritis and inflammatory bowel disease are characterized by chronic inflammatory responses resulting in tissue damage. These diseases have a number of common denominators including: abnormal cytokine expression, aberrant antigen-antibody complexes, T cell anomalies, and increased numbers of neutrophils and macrophages. We propose that the interaction between neutrophils and macrophages induces a state of chronic inflammation which contributes to the disease state. One of the central players in this scenario is myeloperoxidase (MyPo). This enzyme functions in the 'cytotoxic triad' and is involved in cell killing. Studies done by the present investigators have known that MyPo, which is released from neutrophils, induces macrophages to secrete interleukin-1, interferon alpha beta and tumor necrosis factor alpha. Furthermore, our studies have suggested a major immunoregulatory role of this enzyme. We propose that the release of MyPo from neutrophils and subsequent binding to macrophages initiates a cascade of events which enhance the production of reactive oxygen intermediates and cytokine expression resulting in the chronic inflammatory state associated with autoimmune diseases.

Animals↗
PubMed1995

Comparison of Etest and National Committee for Clinical Laboratory Standards broth macrodilution method for antifungal susceptibility testing: enhanced ability to detect amphotericin B-resistant Candida isolates.

The National Committee for Clinical Laboratory Standards (NCCLS) proposed macrobroth reference method (M27P) for susceptibility testing of yeasts is technically difficult. We evaluated Etest, a simple agar-based MIC methodology, as a possible alternative. In studies of six yeast quality control strains, Etest yielded results identical to those obtained by the NCCLS reference method for both amphotericin B and fluconazole. In studies of 91 clinical Candida isolates, agreement +/- 2 dilutions between the two methods was 95% for fluconazole with phosphate-buffered RPMI 1640 agar and 96 to 97% for amphotericin B with either MOPS (morpholinepropanesulfonic acid)-buffered RPMI 1640 agar or antibiotic medium 3 agar. While the two methods had excellent general agreement, testing of a collection of amphotericin B-resistant isolates demonstrated that, unlike the NCCLS reference method, Etest readily identified the resistant isolates and could do so with a defined medium. Etest is equivalent to the NCCLS proposed method for susceptibility testing of yeasts and superior in its ability to detect amphotericin B resistance.

Amphotericin B↗
PubMed1995

Bone mineral density in relation to medical and lifestyle risk factors for osteoporosis in premenopausal, menopausal and postmenopausal women in general practice.

BACKGROUND: Interest in the prevention of osteoporosis is increasing and thus there is a need for an acceptable osteoporosis prevention programme in general practice. AIM: A study was undertaken to identify a cohort of middle-aged women attending a general practice who would be eligible for a longitudinal study looking at bone mineral density, osteoporosis and the effectiveness of hormone replacement therapy. This study aimed to describe the relationship between medical and lifestyle risk factors for osteoporosis and the initial bone density measurements in this group of women. METHOD: A health visitor administered a questionnaire to women aged between 48 and 52 years registered with a Belfast general practice. The main outcome measures were menopausal status, presence of medical and lifestyle risk factors and bone mineral density measurements. RESULTS: A total of 358 women our of 472 (76%) took part in the study which was conducted in 1991 and 1992. A highly significant difference was found between the mean bone mineral density of premenopausal, menopausal and postmenopausal women within the narrow study age range, postmenopausal women having the lowest bone mineral density. A significant relationship was found between body mass index and bone mineral density, a greater bone mineral density being found among women with a higher body mass index. Risk factors such as smoking and sedentary lifestyle were common (reported by approximately one third of respondents) but a poor relationship was found between these two and all the other risk factors and bone mineral density in this age group. CONCLUSION: Risk of osteoporosis cannot be identified by the presence of risk factors in women aged between 48 and 52 years. In terms of a current prevention strategy for general practice it would be better to take a population-based approach except for those women known to be at high risk of osteoporosis: women with early menopause or those who have had an oophorectomy.

Bone Density↗
PubMed1995

Fish mapping of 250 cosmid and 26 YAC clones to chromosome 4 with special emphasis on the FSHD region at 4q35.

Facioscapulohumeral muscular dystrophy (FSHD) is located on chromosome 4q35, close to the telomere. FSHD patients carry deletions within a cluster of tandemly repeated DNA. Although expression of a functional FSHD gene will be altered in patients, the sequence itself may be unaffected by this deletion. Hence, the FSHD gene could lie outside of the deleted region. This study employs fluorescent in situ hybridization using chromosome 4-specific cosmid and YAC clones to rapidly saturate chromosome 4 with new markers. Some 250 cosmids and 26 YACs were regionally mapped, of which 5 YACs and 55 cosmids mapped to the distal portion of 4q. Only one of these clones (D4S1454) mapped telomerically to a translocation breakpoint specified by D4S187. Using two-color interphase mapping, the following marker order was obtained: Cen-D4S187-D4S1454-HSPCAL2-D4S163-D4S139-+ ++D4F35S1. Absence of additional markers mapping distal to D4F35S1 indicates that the linkage group containing the FSHD gene lies extremely close to the 4q telomere.

Cell Line↗
PubMed1994

Etest for susceptibility testing of Mycobacterium tuberculosis and Mycobacterium avium-intracellulare.

Methods currently used for susceptibility testing of Mycobacterium, including agar dilution and the Bactec radiometric method, are based on the proportion technique using a single critical concentration of antibiotic. Preliminary studies were conducted with Mycobacterium species by using the Etest method, a gradient minimum inhibitory concentration technique, well described for susceptibility testing of other fastidious and slow-growing organisms. Excellent correlation was demonstrated between Etest and agar dilution with rifampin-susceptible and -resistant isolates of M. tuberculosis and ciprofloxacin-resistant and -susceptible isolates of Mycobacterium avium-intracellulare.

Ciprofloxacin↗
PubMed1994

Comparison of four commercially available rapid enzyme immunoassays with cytotoxin assay for detection of Clostridium difficile toxin(s) from stool specimens.

Rapid (2.5- to 3.5-h) enzyme immunoassays (EIAs) for the detection of Clostridium difficile toxins have been developed. We report the results of simultaneous testing of 700 fresh stool specimens by the tissue culture cytotoxin assay and four EIAs (Bartels Prima System C. difficile Toxin A EIA, Cambridge Biotech Cytoclone A+B EIA, Meridian Diagnostics Premier C. difficile Toxin A EIA, and TechLab C. difficile Tox-A Test EIA). In cases of disagreement, culturing for toxigenic C. difficile was performed. A total of 61 (8.7%) specimens from 46 patients were positive for C. difficile toxin. The sensitivity of the cytotoxin assay was 87%, and that of culture was 93%. In comparison with the cytotoxin assay results, the sensitivity and specificity of the EIAs were as follows: Bartels, 87 and 96%; Cambridge, 89 and 99%; Meridian, 87 and 98%; and TechLab, 87 and 95%, respectively. In comparison with the cytotoxin assay plus toxigenic culture results, the sensitivity and specificity of the EIAs were as follows: Bartels, 84 and 97%; Cambridge, 85 and 99%; Meridian, 79 and 98%; and TechLab, 80 and 96%, respectively. The EIAs varied in positive predictive values (PPVs). A high PPV was seen with the Cambridge EIA (96%); lower PPVs were seen with the TechLab (64%), Bartels (72%), and Meridian (80%) EIAs because of high false-positive rates. The negative predictive values (98 to 99%) were excellent with all EIAs. Results were indeterminant with 0.3% of the samples by the Meridian EIA and 3% by all the other EIAs. Although the EIAs were less sensitive than the cytotoxin assay, they provide same-day results and may be useful in laboratories without tissue culture facilities.

Bacterial Proteins↗
PubMed1994

The South London Somatisation Study. II. Influence of stressful life events, and secondary gain.

BACKGROUND: A study of the influence of life-event stress on the onset and course of acute somatisation in primary care. METHOD: Forty-four somatisers were compared with 11 subjects who had psychiatric disorder but complained only of psychological symptoms, 39 patients who had 'mixed' conditions involving independent physical and psychiatric illness, 90 patients who had physical illness, and 123 healthy members of the general population. RESULTS: Severely threatening life events were more common among all subjects with psychiatric disorder. A novel contextual rating of the potential of stressors to produce symptoms for 'secondary gain' was developed. In the 38 weeks before symptom onset, somatisers and psychologisers were more likely to have experienced at least one event which had this potential. Somatisers were also less likely to adopt neutralising coping efforts when faced with such a crisis. CONCLUSIONS: The likelihood of adopting neutralising efforts was closely related to the presence of a joint index of parental problems in care and exposure to physical illness in the subject's childhood. In a two-year follow-up, subsequent functional illnesses were also associated with experiences which had secondary-gain potential, and subjects with childhood risk factors continued to have higher rates of crises with secondary-gain potential and to fail to adopt neutralising coping strategies.

Adaptation, Psychological↗
PubMed1994

Plague in a black-footed ferret (Mustela nigripes).

Diagnosis of sylvatic plague in a captive black-footed ferret (Mustela nigripes) was based on gross and microscopic lesions, fluorescent antibody tests, culture of Yersinia pestis, and immunohistochemistry. Gross lesions consisted of acute hemorrhage and necrosis associated with cervical and mesenteric lymph nodes, subcutaneous hemorrhages, and pulmonary edema. Acute edema, hemorrhage, and necrosis with numerous bacteria in blood vessels and sinusoids characterized microscopic lesions. Occurrence of fatal plague in a black-footed ferret potentially has significant implications for recovery of this endangered species due to the widespread distribution of plague in prairie dog colonies throughout historic black-footed ferret range.

Animals↗
PubMed1993

Progressive sensory nerve dysfunction in amyotrophic lateral sclerosis: a prospective clinical and neurophysiological study.

Sensory nerve function was determined in 19 patients with amyotrophic lateral sclerosis (ALS), using a battery of clinical and neurophysiological tests. This assessment was repeated on 12 patients after intervals of 6-18 months. Twelve controls were also studied. In the ALS group, only 2 patients had noticed mild sensory symptoms and none had sensory signs. Between successive studies the vibration thresholds increased, but not to a significant degree. ALS patients showed a significant fall in amplitude of the sensory nerve action potentials in the median, radial, and sural nerves (P < 0.04); sensory nerve conduction velocity did not alter. The median nerve somatosensory evoked potential N19 latency showed a highly significant increase (P < 0.008). Significant subclinical deterioration in sensory nerve function occurs in ALS, and parallels the progressive motor decline. Neuronal degeneration in ALS is not restricted to motor neurons.

Action Potentials↗