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Biomedical subjects

R Daniel

Publications and source records attributed to R Daniel.

At least 19 recordsLinked to original sources
PubMed2000

Cryosolvents useful for protein and enzyme studies below -100 degrees C.

For the study of protein structure, dynamics, and function, at very low temperatures it is desirable to use cryosolvents that resist phase separation and crystallisation. We have examined these properties in a variety of cryosolvents. Using visual and X-ray diffraction criteria, methanol:ethanediol (70%:10%), methanol:glycerol (70%:10%), acetone:methoxy-ethanol:ethanediol (35%:35%:10%), dimethylformamide:ethanediol (70%:10%), dimethylformamide (80%), methoxyethanol (80%), and methoxyethanol:ethanediol (70%:10%) were all found to be free of phase-changes down to at least -160 degrees C. The least viscous of these, methanol:ethanediol (70%:10%), was miscible down to -125 degrees C and showed no exo or endothermic transitions when examined using DSC. It is therefore potentially particularly suitable for very low temperature cryoenzymology.

Cryoprotective Agents↗
PubMed2000

Variation in the interleukin 4-receptor alpha gene confers susceptibility to asthma and atopy in ethnically diverse populations.

After a genomewide screen in the Hutterites was completed, the IL4RA gene was examined as the 16p-linked susceptibility locus for asthma and atopy. Seven known variants and one novel variant, representing all nonsynonymous substitutions in the mature protein, were examined in the Hutterites; on the basis of studies in the Hutterites, outbred white, black, and Hispanic families were genotyped for selected markers. All population samples showed evidence of association to atopy or to asthma (P values.039-.0044 for atopy and. 029-.0000061 for asthma), but the alleles or haplotypes showing the strongest evidence differed between the groups. Overall, these data suggest that the IL4RA gene is an atopy- and asthma-susceptibility locus but that variation outside the coding region of the gene influences susceptibility.

Alleles↗
PubMed1999

Identification of the syntrophic partners in a coculture coupling anaerobic methanol oxidation to Fe(III) reduction.

From enrichments with methanol and ferric pyrophosphate a coculture was isolated which coupled methanol oxidation to carbon dioxide with the reduction of Fe(III) to Fe(II). 16S rRNA gene analysis of the isolated syntrophic partners revealed 99.5% similarity to Clostridium sphenoides and 98.5% to Shewanella putrefaciens. Formation of Fe(II) coupled to methanol oxidation was confirmed by using strains of culture collections (C. sphenoides DSM 632 and S. putrefaciens DSM 9461). The importance of this process is discussed, also with respect to the anaerobic oxidation of methane.

Anaerobiosis↗
PubMed1999

Development of a capillary electrophoresis assay based on free sulfate determination for the direct monitoring of sulfoesterase activity.

A capillary electrophoresis assay of sulfoesterase activity was developed that overcomes the main drawbacks encountered with the usual methods for sulfate determination in complex biological medium. Conditions are described allowing direct measurement of inorganic sulfate that is enzymatically produced in the reaction mixture. The main features of this method are electrokinetic sample introduction, which allows selective extraction of sulfate from the matrix into the separation capillary, counter-electroosmotic flow migration mode, indirect absorbance detection and use of an internal standard for quantitative performances. Likewise, perfect linearity was obtained for concentrations of sulfate up to 40 ppm. The limits of detection and quantification were 0.2 and 0.6 ppm, respectively. The run-to-run and day-to-day precision are 1 and 4.5%, respectively, for sulfate concentrations varying from 35 ppm down to 1 ppm. The accuracy was established for the synthetic p-nitrocatechol sulfate substrate by comparison with the classical spectrophotometric assay. The method was applied to the kinetic monitoring of the activity of a sulfoesterase extracted from the marine mollusc Pecten maximus on fucoidan, a bioactive sulfated fucose-based polysaccharide derived from brown algae. For the first time, a sulfoesterase activity was shown to be effective on such sulfated polysaccharides.

Animals↗
PubMed1999

A role for DNA-PK in retroviral DNA integration.

Retroviral DNA integration is catalyzed by the viral protein integrase. Here, it is shown that DNA-dependent protein kinase (DNA-PK), a host cell protein, also participates in the reaction. DNA-PK-deficient murine scid cells infected with three different retroviruses showed a substantial reduction in retroviral DNA integration and died by apoptosis. Scid cell killing was not observed after infection with an integrase-defective virus, suggesting that abortive integration is the trigger for death in these DNA repair-deficient cells. These results suggest that the initial events in retroviral integration are detected as DNA damage by the host cell and that completion of the integration process requires the DNA-PK-mediated repair pathway.

Animals↗
PubMed1999

Adeno-associated virus and development of cervical neoplasia.

Evidence from several sources has suggested that adeno-associated virus (AAV) infection might protect against cervical cancer, in part, by interfering with human papillomavirus (HPV)-induced tumorigenesis. Detection of AAV type 2 (AAV-2) DNA in cervical tissues has been reported. However, there have been few in vivo studies of women with cervical HPV infection or neoplasia, and these have reported inconsistent results. Therefore, we used polymerase chain reaction (PCR) assays targeted to the AAV-2 rep and cap genes to test tissue specimens from women in an epidemiological study of cervical neoplasia in Jamaica. We tested 105 women with low-grade cervical intraepithelial neoplasia (CIN-1), 92 women with CIN-3/carcinoma in situ or invasive cancer (CIN-3/CA), and 94 normal subjects. PCR amplification of human beta-globin DNA was found in almost all cervical specimens, indicating that these materials were adequate for PCR testing. The prevalence of HPV DNA, determined by HPV L1 consensus primer PCR was, as expected, strongly associated with presence and grade of neoplasia. Each of the AAV PCR assays detected as few as 10 copies of the virus genome. However, none of the 291 cervical specimens from Jamaican subjects tested positive for AAV DNA. Negative AAV PCR results were also obtained in tests of cervical samples from 79 university students in the United States. Exposure to AAV was assessed further by serology. Using a whole virus AAV-2 sandwich enzyme-linked immunosorbent assay, we found no relationship between AAV antibodies and presence or grade of neoplasia in either the Jamaican study subjects or women enrolled in a U.S. cervical cancer case (n = 74) -control (n = 77) study. Overall, the data provide no evidence that AAV infection plays a role in cervical tumorigenesis or that AAV commonly infects cervical epithelial cells.

Adolescent↗
PubMed1999

Investigation of leukemia cells from children with common acute lymphoblastic leukemia for genomic sequences of the primate polyomaviruses JC virus, BK virus, and simian virus 40.

BACKGROUND: An infectious etiology for childhood acute lymphoblastic leukemia (ALL) has long been suspected, although the characteristics of the putative childhood ALL-inducing agent(s) remain a mystery. We describe the testing of ALL leukemia cells for the presence of DNA sequences of the polyomavirus family: JC virus, BK virus, and simian virus 40 (SV40). PROCEDURE: Cryopreserved leukemia cells from 25 children between 2 and 5 years of age at the time of diagnosis and classified as having "common" ALL (B-precursor ALL expressing the CD19 and CD10 surface antigens) were tested for the presence of polyomavirus sequences using standard PCR methods. RESULTS: Human beta-globin gene sequences were detected in 22 of 25 leukemia specimens. However, polyomavirus sequences were not detected in any of the 22 specimens with amplifiable DNA. CONCLUSIONS: The inability to detect JC virus, BK virus, and SV40 virus DNA sequences in any of the 22 specimens with amplifiable DNA suggests that that these members of the polyomavirus family are unlikely to be causally associated with most childhood ALL. Published 1999 Wiley-Liss, Inc.

BK Virus↗
PubMed1999

An extended role for the hospital optometrist.

The management of patients within shared care programmes would seem to have significant benefits in terms of individuals' convenience, addressing resource needs and expanding professional horizons. To date, these schemes have typically concentrated on the monitoring of patients with diabetes and glaucoma. At Moorfields Eye Hospital, we attempted to develop the role of the hospital optometrist by establishing a study to evaluate the clinical appraisal of new referrals in a busy out-patient clinic. The results showed a high level of diagnostic accuracy which suggests that the role of hospital optometrists may be successfully extended to include some aspects of patient evaluation not typically undertaken.

Adolescent↗
PubMed1999

Use of a hybrid capture assay of self-collected vaginal swabs in rural Uganda for detection of human papillomavirus.

A random sample of 960 women aged 15-59 years enrolled in a population-based study in rural Uganda were asked to provide self-collected vaginal swabs for human papillomavirus (HPV) testing by hybrid capture assay. The intensity of HPV infection was assessed by the relative light unit (RLU) ratio in the specimen-to-positive control (PC) ratio. In total, 898 women (93%) provided a swab and 737 provided serum for human immunodeficiency virus type 1 (HIV-1) determination. HPV prevalence was 16.7% and was highest in younger women. HIV-1 prevalence was 17.8%. HPV prevalence was 44.3% in HIV-positive and 10.2% in HIV-negative women (rate ratio, 5.36; 95% confidence interval, 3.81-7.54). The intensity of HPV infection was significantly greater among HIV-positive than HIV-negative women (54. 4 vs. 11.1 RLU/PC; P=.026); intensity of infection was highest in women aged <30 years. The higher prevalence and intensity of HPV infection in HIV-positive women could facilitate HPV transmission in this population. Self-collected vaginal swabs could be used in population-based screening to identify women at high risk of cervical neoplasia.

Adolescent↗
PubMed1999

Construction of environmental DNA libraries in Escherichia coli and screening for the presence of genes conferring utilization of 4-hydroxybutyrate.

Environmental DNA libraries from three different soil samples were constructed. The average insert size was 5 to 8 kb and the percentage of plasmids with inserts was approximately 80%. The recombinant Escherichia coli strains (approximately 930,000) were screened for 4-hydroxybutyrate utilization. Thirty-six positive E. coli clones were obtained during the initial screen, and five of them contained a recombinant plasmid (pAH1 to pAH5) which conferred a stable 4-hydroxybutyrate-positive phenotype. These E. coli clones were studied further. All five were able to grow with 4-hydroxybutyrate as sole carbon and energy source and exhibited 4-hydroxybutyrate dehydrogenase activity in crude extracts. Sequencing of pAH5 revealed a gene homologous to the gbd gene of Ralstonia eutropha, which encodes a 4-hydroxybutyrate dehydrogenase. Two other genes (orf1 and orf6) conferring utilization of 4-hydroxybutyrate were identified during subcloning and sequencing of the inserts of pAH1 and pAH3. The deduced orf1 gene product showed similarities to members of the DedA family of proteins. The sequence of the deduced orf6 gene product harbors the fingerprint pattern of enoyl-coenzyme A hydratases/isomerases. The other sequenced inserts of the plasmids recovered from the positive clones revealed no significant similarity to any other gene or gene product whose sequence is available in the National Center for Biotechnology Information databases.

Amino Acid Sequence↗
PubMed1999

Evaluation of visual outcome of cataract surgery in an Indian eye camp.

AIM: To evaluate the results of cataract surgery performed in a rural Indian eye camp. METHOD: The pre- and postoperative visual acuities and surgical complications were recorded prospectively in 6383 eyes undergoing cataract extraction for age related cataract in rural eye camps held in northern India in 1993-4. The best visual acuity and cause of poor outcome were recorded on 3908 eyes seen at 6 weeks' follow up. RESULTS: Of 6383 operated eyes 94.8% had a visual acuity of less than 3/60 preoperatively, and 41% of the procedures were performed on patients who were bilaterally blind (less than 3/60 better eye). At discharge with standard aphakic spherical spectacles, 11.3% of eyes had an acuity of less than 6/60 (poor outcome), and 25.9% had an acuity of 6/18 or better. At 6 weeks' follow up 3908 eyes were examined (61.2%), of which, with best correction, 4.3% had poor outcome (acuity of less than 6/60) and 79.9% obtained 6/18 or better. Pre-existing eye pathology was responsible for poor outcome in 3.0% of eyes and surgical complications in 1.3% of eyes, of which corneal decompensation was the major cause (0.5%). In 237 eyes which received an intraocular lens implantation (IOL) in the camp, the visual acuity at discharge was 6/18 or better in 44.5% of eyes improving to 87.9% in the 157 eyes which were seen at 6 weeks' follow up. Poor outcome (less than 6/60) was seen in 5.7% of the eyes with an IOL at discharge improving to 1.9% at follow up. CONCLUSION: This evaluation suggests that it is possible to obtain acceptable results from cataract extraction with experienced ophthalmologists in well conducted Indian eye camps. Better correction of aphakia at discharge from the camp would improve the immediate visual results, which is important as a significant number of patients do not return for follow up. The use of posterior chamber IOLs in the eye camp by experienced ophthalmologists, appeared to give satisfactory results, although further evaluation with a larger series of cases and more surgeons is required before it can be recommended.

Adult↗
PubMed1999

Genome-wide screen for atopy susceptibility alleles in the Hutterites.

A genome-wide screen for loci influencing positive skin prick tests (SPT) to airborne allergens was conducted in the Hutterites, a founder population of European ancestry. Positive SPT to 14 standardized allergens was measured in 370 subjects in our primary sample and 324 subjects in a replication sample. Evidence for linkage to positive SPT was assessed using the transmission disequilibrium test (TDT) with 337 autosomal markers (average spacing 9.13 cM, SD = 7.8 cM). Three loci showed the strongest overall evidence of linkage to atopy, with at least one allele-specific and a locus-specific p< 1 x 10(-4). This study provides evidence for at least three atopy-susceptibility loci in the Hutterites on chromosomes 1, 6 and 16.

Adult↗
PubMed1998

Properties and sequence of the coenzyme B12-dependent glycerol dehydratase of Clostridium pasteurianum.

The genes encoding coenzyme B12-dependent glycerol dehydratase of Clostridium pasteurianum were subcloned and expressed in Escherichia coli. The native molecular mass of the enzyme is 190,000 Da. The enzyme converts glycerol, 1,2-propanediol and 1,2-ethanediol to 3-hydroxypropionaldehyde, propionaldehyde and acetaldehyde, respectively, but glycerol is the preferred substrate. The nucleotide sequences of the dhaBCE genes encoding the three subunits of glycerol dehydratase and of orfZ whose function is unknown were determined. The deduced products of the dhaBCE genes with calculated molecular masses of 60,813, 19,549 and 16,722 Da, respectively, revealed high similarity to amino acid sequences of subunits of coenzyme B12-dependent glycerol and diol dehydratases from other organisms.

Amino Acid Sequence↗
PubMed1998

Involvement of C-Abl tyrosine kinase in lipopolysaccharide-induced macrophage activation.

LPS endotoxin-induced macrophage activation is recognized to be important in both nonspecific immunity and endotoxin-induced sepsis when excessive macrophage stimulation occurs. In this study, we showed that reduction of c-Abl in macrophages prevented LPS-induced growth arrest, nitric oxide production and TNF-alpha secretion by ANA-1 macrophages. These cells continued to grow but later underwent apoptosis. Reduction of c-Abl in these cells led to reduced c-Abl kinase activity associated with Ran, which recently has been shown to be an LPS-responsive gene product. Our data suggest that c-Abl tyrosine kinase is one of the intermediates downstream of the initial signal transduction event related to activation of macrophages by LPS.

Animals↗
PubMed1998

Treatment of acute exacerbations of chronic bronchitis: comparison of trovafloxacin and amoxicillin in a multicentre, double-blind, double-dummy study. Trovafloxacin Bronchitis Study Group.

The efficacy and safety of trovafloxacin and amoxicillin were compared in a double-blind, double-dummy multicentre trial involving 412 patients (> or = 40 years of age) with acute exacerbations of chronic bronchitis (AECBs). Patients were randomized to 5 days' oral treatment with 200 or 100 mg trovafloxacin administered once daily, or 500 mg amoxicillin given three times daily. Overall clinical efficacy at the end of therapy was similar in each treatment group, with clinical success (cure+improvement) achieved in 88% and 91% of clinically evaluable patients receiving trovafloxacin 200 mg and 100 mg, respectively, and in 89% of amoxicillin-treated patients. Corresponding rates at follow-up were 77%, 85% and 79%, respectively. Similar responses were noted at the end of treatment and end of study in the intent-to-treat patients. Although all three treatments produced similar bacteriological efficacy, there was a trend towards higher eradication rates for Haemophilus influenzae among patients (both clinically evaluable and intent-to-treat populations) treated with trovafloxacin 200 mg compared with those treated with amoxicillin. Both drugs were well tolerated, with treatment-related adverse events, of which headache and gastrointestinal disturbances were the most common, occurring in 12% and 6% of patients in the trovafloxacin 200 mg and 100 mg groups, respectively, and in 9% of amoxicillin-treated patients.

Acute Disease↗
PubMed1998

Trovafloxacin versus high-dose amoxicillin (1 g three times daily) in the treatment of community-acquired bacterial pneumonia.

Once-daily trovafloxacin 200 mg was compared with high-dose amoxicillin, 1 g three times daily, given for 7 to 10 days. At end of treatment (day 10), the response was clinically successful (cure + improvement) in 93% of 152 clinically evaluable trovafloxacin patients and in 89% of 160 amoxicillin patients. At study end (day 35), respective rates were 91% and 81% (95% confidence interval: 1.6, 17.6; P=0.01). In evaluable patients with positive baseline radiographs, 93% of trovafloxacin and 88% of amoxicillin patients demonstrated radiological resolution at end of treatment. Streptococcus pneumoniae and Haemophilus influenzae eradication rates were comparable at end of treatment in both treatment groups, but at study end Streptococcus pneumoniae eradication rates were higher in trovafloxacin patients (100% vs 81%). At study end, all four trovafloxacin patients with baseline penicillin-resistant Streptococcus pneumoniae were clinically cured with pathogen eradication, whereas two of five amoxicillin patients with baseline penicillin-resistant Streptococcus pneumoniae were clinical failures with pathogen persistence. For patients in whom no pathogen was identified, trovafloxacin was significantly more effective at end of treatment (P=0.096) and study end (P=0.013). Treatment-related adverse events were comparable; the most common were headache, vomiting and dizziness in trovafloxacin patients, and diarrhoea. headache and abdominal pain in amoxicillin patients.

Adolescent↗
PubMed1998

RK-2: a novel rabbit kidney defensin and its implications for renal host defense.

Defensins are endogenous antimicrobial peptides. We demonstrated recently the existence of RK-1, a defensin-like peptide in rabbit kidneys. Defining the renal-defensin system is an essential step toward understanding how the kidney responds to infection. Here, using a combination of high-performance liquid chromatography, matrix-assisted laser desorption time-of-flight mass spectrometry, amino acid compositional analysis, and microsequence analysis, we show that the rabbit kidney contains a novel alpha-defensin-like peptide, RK-2. This work establishes the existence of a new subfamily of alpha-defensins in the kidney.

Amino Acid Sequence↗