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Biomedical subjects

R Wright

Publications and source records attributed to R Wright.

At least 37 records · Page 2Linked to original sources
PubMed1999

Auricular rehabilitation with bone-anchored titanium implants.

OBJECTIVE: To evaluate the effectiveness of the bone-anchored titanium implants in auricular reconstructions. STUDY DESIGN: Six patients who received implants for an auricular reconstruction were followed prospectively. Four patients had lost their ears to cancer, and the other two had congenital aural atresia. METHODS: All patients were thoroughly evaluated by the reconstruction team, which included a surgeon, a prosthodontist, and a facial prosthetist. Three patients were evaluated audiologically for a bone-anchored hearing aid. Four patients received implants in a single-stage procedure, and two underwent a two-stage procedure. A gold bar with retaining clips was used to anchor the prosthetic ear in four patients, and magnets were used in the remaining two. RESULTS: All six patients are completely satisfied with their reconstructions. No failures, extrusions, or bony complications were encountered. One patient had recurrent dermatitis, which subsided when his gold bar was replaced with magnets. CONCLUSION: Implanted under the guidance of an appropriate prosthetic team, bone-anchored titanium implants provide patients with a safe, reliable, adhesive-free method to anchor auricular prostheses with recovery of their normal appearance.

Bone Screws↗
PubMed1999

Lice on horses.

Explore the source record for details and available documents.

Administration, Cutaneous↗
PubMed1998

A cell cycle-regulated adenine DNA methyltransferase from Caulobacter crescentus processively methylates GANTC sites on hemimethylated DNA.

The kinetic properties of an adenine DNA methyltransferase involved in cell cycle regulation of Caulobacter crescentus have been elucidated by using defined unmethylated or hemimethylated DNA (DNAHM) substrates. Catalytic efficiency is significantly enhanced with a DNAHM substrate. Biphasic kinetic behavior during methyl incorporation is observed when unmethylated or DNAHM substrates are used, indicating that a step after chemistry limits enzyme turnover and is most likely the release of enzyme from methylated DNA product. The enzyme is thermally inactivated at 30 degrees C within 20 min; this process is substantially decreased in the presence of saturating concentrations of DNAHM, suggesting that the enzyme preferentially binds DNA before S-adenosylmethionine. The activity of the enzyme shows an unusual sensitivity to salt levels, apparently dissociating more rapidly from methylated DNA product as the salt level is decreased. The enzyme acts processively during methylation of specific DNA sequences, indicating a preferred order of product release in which S-adenosylhomocysteine is released from enzyme before fully methylated DNA. The kinetic behavior and activity of the enzyme are consistent with the temporal constraints during the cell cycle-regulated methylation of newly replicated chromosomal DNA.

Caulobacter crescentus↗
PubMed1998

Behavioural factors in accidents at road junctions: the use of a genetic algorithm to extract descriptive rules from police case files.

In-depth studies of behavioural factors in road accidents using conventional methods are often inconclusive and costly. To explore an alternative approach, 200 cross-flow junction road accidents were sampled from the files of Nottinghamshire Constabulary, England, coded for computer analysis using a specially devised 'Traffic Related Action Analysis Language', and then examined using a genetic algorithm (or 'rule-finder' program). For comparison, the same analyses were carried out on 100 descriptions of safe turns, and 100 of hypothetical accident descriptions provided by experienced drivers. A number of findings emerged, distinguishing between accidents turning onto and off major roads; those of younger and older drivers; those that resulted in injury or in damage only; and so on. The study suggests that multiple case-studies based on police case files could be very promising, provided homogeneous samples of accidents are used. Genetic algorithms could play a useful role in preliminary assessment, but an 'information bottleneck' remains to be overcome in capturing enough detail from each case for analysis.

Accidents, Traffic↗
PubMed1998

Quantification of the enhanced backscatter phenomenon from an intravenous and an intra-arterial contrast agent.

The phenomenon of enhanced backscatter from myocardial contrast agents was studied using two examples, a robust thicker-walled, intra-arterial agent (AIP 201) and a smaller thinner-walled, intravenous agent (Quantison). Both agents are composed of albumin-encapsulated microbubbles. Samples of the agents were inserted into an in vitro phantom and insonated under different scanning regimes. Upon insonation, Quantison exhibited a pronounced increase in mean backscatter at medium and low concentrations, which decreased dramatically with increasing number of frames of insonation. At high concentrations, no dramatic decrease or increase in mean backscatter was observed over the period of the experiment. AIP 201 exhibited an overall decrease in mean backscatter with increasing number of frames of insonation. These results suggest that the difference in size and wall thickness of the contrast microcapsules can significantly affect the behaviour of the contrast agents in an ultrasound field.

Contrast Media↗
PubMed1998

When immigrants are not migrants: counting arrivals of the foreign born using the U.S. census.

"This paper compares characteristics of recent immigrant arrivals in the United States using two measures from the decennial U.S. census: the came-to-stay question and the migration question.... Among recent arrivals, defined as those who reported they came to stay in the quinquennium preceding the census, a large number were resident in the United States five years before the census date. Furthermore, the proportion of recent arrivals present in the United States five years before the census increased between 1975-1980 and 1985-1990.... Generally, in both the 1975-1980 and 1985-1990 cohorts, those resident in the United States five years before the census have significantly less schooling and lower incomes than those who were abroad."

Americas↗
PubMed1997

Monozygotic twins discordant for schizophrenia are discordant for N-CAM and L1 in CSF.

While schizophrenia has a genetic component, its pathogenesis is unknown. Abnormal concentrations of two cell recognition molecules (CRMs), neural-cell adhesion molecule (N-CAM) and L1 antigen have been described in the cerebrospinal fluid (CSF) of patients with schizophrenia. Studies of monozygotic twins discordant for schizophrenia may help separate genetic and environmental contributions to the disease. In the present study of monozygotic twins discordant for schizophrenia, the affected twins had increased N-CAM and decreased L1 antigen in their CSF. Non-affected twins were not different from normals. Although processes related to genetic instability cannot be entirely ruled out, these results suggest that these abnormalities are not a part of the genetic predisposition to become schizophrenic. Thus the changes in N-CAM and L1 antigen may reflect either the events which precipitated the onset of schizophrenia, or events which are associated with the experience of having the disease.

Analysis of Variance↗
PubMed1997

The CcrM DNA methyltransferase is widespread in the alpha subdivision of proteobacteria, and its essential functions are conserved in Rhizobium meliloti and Caulobacter crescentus.

The Caulobacter crescentus DNA methyltransferase CcrM (M.CcrMI) methylates the adenine residue in the sequence GANTC. The CcrM DNA methyltransferase is essential for viability, but it does not appear to be part of a DNA restriction-modification system. CcrM homologs are widespread in the alpha subdivision of gram-negative bacteria. We have amplified and sequenced a 258-bp region of the cerM gene from several of these bacteria, including Rhizobium meliloti, Brucella abortus, Agrobacterium tumefaciens, and Rhodobacter capsulatus. Alignment of the deduced amino acid sequences revealed that these proteins constitute a highly conserved DNA methyltransferase family. Isolation of the full-length ccrM genes from the aquatic bacterium C. crescentus, the soil bacterium R. meliloti, and the intracellular pathogen B. abortus showed that this sequence conservation extends over the entire protein. In at least two alpha subdivision bacteria, R. meliloti and C. crescentus, CcrM-mediated methylation has important cellular functions. In both organisms, CcrM is essential for viability. Overexpression of CcrM in either bacterium results in defects in cell division and cell morphology and in the initiation of DNA replication. Finally, the C. crescentus and R. meliloti ccrM genes are functionally interchangeable, as the complemented strains are viable and the chromosomes are methylated. Thus, in both R. meliloti and C. crescentus, CcrM methylation is an integral component of the cell cycle. We speculate that CcrM-mediated DNA methylation is likely to have similar roles among alpha subdivision bacteria.

Amino Acid Sequence↗
PubMed1997

Videofluoroscopic evaluation of dysphagia in motor neurone disease with modified barium swallow.

The role of videofluoroscopy with the modified barium swallow in the assessment and management of motor neurone disease (MND) is discussed. Nine patients (age range 40-82) with dysphagia secondary to MND were assessed over a four-year period. The examinations were carried out by a multiprofessional team of radiologist, speech and language therapist and dietitian assessing the preoral, oral and pharyngeal phases of swallowing. Preoral feeding abnormalities were present in four out of nine patients, oral phase abnormalities in eight out of nine patients, while 33% of patients demonstrated abnormality in all three phases. Where aspiration occurred (four out of nine cases), no cough reflex was noted. On the basis of these examinations management changes were introduced in all patients. Nonoral feeding was continued or introduced in three patients. Videofluoroscopic examination with the modified barium swallow may be helpful in planning suitable feeding regimes for dysphagia in MND.

Adult↗
PubMed1997

Congenital lymphocytic choriomeningitis virus syndrome: a disease that mimics congenital toxoplasmosis or Cytomegalovirus infection.

OBJECTIVE: To describe the clinical characteristics of intrauterine infection with lymphocytic choriomeningitis (LCM) virus, an uncommonly recognized cause of congenital viral infection. PATIENTS: Three infants born in the midwestern United States in 1994 and 1995 with clinical features and serologic studies consistent with congenital LCM virus infection and cases of congenital infection identified by review of the medical literature between 1955 and 1996. RESULTS: Twenty-six infants with serologically confirmed congenital LCM virus infection were identified. Twenty-two infants were products of term gestations, and birth weights ranged from 2384 to 4400 g (median, 3520 g). Ocular abnormalities, macrocephaly, or microcephaly were the most commonly identified neonatal features. Twenty-one infants (88%) had chorioretinopathy, 10 (43%) had macrocephaly (head circumference >90th percentile) at birth, and 3 (13%) were microcephalic (head circumference <10th percentile). Macrocephaly and hydrocephalus developed postnatally in one of the latter infants. Hydrocephalus or intracranial calcifications were documented in five infants by computed tomography or magnetic resonance imaging. Nine infants (35%) died, and 10 (63%) of the 16 reported survivors had severe neurologic sequelae, consisting of spastic quadriparesis, seizures, visual loss, or mental retardation. One-half of the mothers reported illnesses compatible with LCM virus infection, and 25% reported exposures to rodents during their pregnancies. CONCLUSIONS: These cases suggest that congenital LCM virus infection could be an underrecognized cause of congenital infection among infants born in the United States. Because of the clinical similarities of these congenital infections, cases of congenital LCM virus infection can be confused with infections with cytomegalovirus or Toxoplasma gondii.

Apgar Score↗
PubMed1997

An economic analysis of the Survival and Ventricular Enlargement (SAVE) Study. Application to the United Kingdom.

Recent studies have shown that ACE inhibitors reduce morbidity and mortality after myocardial infarction (MI). While these trials have obvious clinical implications, the widespread introduction of a new treatment for a condition as common as MI also has clear cost implications. The results of the post-MI studies with ACE inhibitors suggest that restricted use of treatment-in high-risk patients-is likely to be most cost effective, whereas treatment of all MI survivors, many of whom are at low risk, will be least cost effective. An approach somewhere in between may maximise clinical benefit at an acceptable cost. Economic analysis may help in deciding how these drugs might be best used after MI. We have conducted a cost-effectiveness and cost-utility analysis of the Survival and Ventricular Enlargement (SAVE) study, which reported the benefit of ACE inhibitors in intermediate-risk patients. Assuming all MI survivors require measurement of left ventricular function before selection for treatment (the approach used in the SAVE study), the incremental cost per life-year gained (LYG), over 4 years, using prophylactic captopril is approximately 10000 pounds sterling (Pounds) [1994 to 1995 values]. The cost per quality-adjusted life-year (QALY) is similar. These incremental cost per LYG and cost per QALY ratios compare favourably with other commonly used symptomatic and prophylactic treatments, and argue for extending post-MI use of ACE inhibitors to intermediate-as well as high-risk patients.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1997

Diagnostic strategies for pulmonary arteriovenous fistula in pregnancy.

Pulmonary arteriovenous malformations (PAVMs) are a documented cause of hemoptysis, and usually necessitate pulmonary angiography for a definitive diagnosis. However, the diagnosis can become more problematic in pregnancy. We recently saw a young woman in her fifth month of pregnancy with hemoptysis, who was found to have multiple PAVMs. We report this case to highlight the various non-invasive methods of making this diagnosis.

Adult↗
PubMed1996

Molecular, functional and evolutionary characterization of the gene encoding HMG-CoA reductase in the fission yeast, Schizosaccharomyces pombe.

The synthesis of mevalonate, a molecule required for both sterol and isoprene biosynthesis in eukaryotes, is catalysed by 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase. Using a gene dosage approach, we have isolated the gene encoding HMG-CoA reductase hmgl+, from the fission yeast Schizosaccharomyces pombe (Accession Number L76979). Specifically, hmgl+ was isolated on the basis of its ability to confer resistance to lovastatin, a competitive inhibitor of HMG-CoA reductase. Gene disruption analysis showed that hmgl+ was an essential gene. This result provided evidence that, unlike Saccharomyces cerevisiae, S. pombe contained only a single functional HMG-CoA reductase gene. The presence of a single HMG-CoA reductase gene was confirmed by genomic hybridization analysis. As observed for the S. cerevisiae HMGlp, the hmgl+ protein induced membrane proliferations known as karmellae. A previously undescribed 'feed-forward' regulation was observed in which elevated levels of HMG-CoA synthase, the enzyme catalysing the synthesis of the HMG-CoA reductase substrate, induced elevated levels of hmgl+ protein in the cell and conferred partial resistance to lovastatin. The amino acid sequences of yeast and human HMG-CoA reductase were highly divergent in the membrane domains, but were extensively conserved in the catalytic domains. We tested whether the gene duplication that produced the two functional genes in S. cerevisiae occurred before or after S. pombe and S. cerevisiae diverged by comparing the log likelihoods of trees specified by these hypotheses. We found that the tree specifying post-divergence duplication had significantly higher likelihood. Moreover, phylogenetic analyses of available HMG-CoA reductase sequences also suggested that the lineages of S. pombe and S. cerevisiae diverged approximately 420 million years ago but that the duplication event that produced two HMG-CoA reductase genes in the budding yeast occurred only approximately 56 million years ago. To date, S. pombe is the only unicellular eukaryote that has been found to contain a single HMG-CoA reductase gene. Consequently, S. pombe may provide important opportunities to study aspects of the regulation of sterol biosynthesis that have been difficult to address in other organisms and serve as a test organism to identify novel therapies for modulating cholesterol synthesis.

Amino Acid Sequence↗