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Biomedical subjects

M Williamson

Publications and source records attributed to M Williamson.

At least 73 records · Page 4Linked to original sources
PubMed1995

Occupational injuries in a poor inner-city population.

This study aims to characterize occupational injuries in a defined poor inner-city population in terms of demographic features, types, and circumstances of injuries, and medical and financial consequences. It is a case series drawn from a larger population-based injury registry in emergency departments that serve 17 poor census tracts in Philadelphia. Of 335 patients from the study area who had been treated at the emergency departments under study for occupational injuries, 107 could be contacted by telephone 2 to 3 years after their injuries. Interviews sought information on the patients, their employment, their injuries, and the consequences. Respondents were almost all African-American, approximately 50% male, and had a median age of 32. Approximately one third were employed in the health care industry, one fourth in the service sector (including conventional service firms, restaurants, and hotels), and the remainder in construction, retail and wholesale trade, education, transportation, and manufacturing. Major causes of injuries included overexertion, contact with sharp objects, and falls. Major types on injuries included sprain/strains and lacerations. Approximately half the respondents had missed more than 3 days of work, with 15% missing more than 1 month. Almost 40% of respondents reported persistent health problems after their injuries. Only about one quarter had received workers' compensation. We conclude that poor and minority workers are at risk of a wide range of occupational injuries, which may result in considerable lost work time and have serious medical and economic consequences. More, attention to the workplace risks of these relatively marginalized workers and more vigorous preventive interventions are needed.

Accidents, Occupational↗
PubMed1995

Failure of the urinary group B streptococcal antigen test as a screen for neonatal sepsis.

The accuracy of the urinary group B streptococcal antigen latex agglutination (LA) test for screening infants at risk of group B streptococcal (GBS) sepsis in the first 24 hours of life was prospectively studied in 236 infants for six months. Infection with GBS was defined by a positive blood culture while colonisation was defined by GBS cultured from any other site. The combination of infection and colonisation was used as the gold standard for the LA test. Although the LA test had a sensitivity of 90%, the specificity was only 70%, the positive predictive value 12% and the false positive rate 30%. The overall accuracy was only 71%. The LA test was unable to predict GBS sepsis in infants at risk of the disease. The false positive rate was unacceptably high and could not be potentially accounted for in 11 infants. However, a negative test was useful in excluding GBS disease.

Antigens, Bacterial↗
PubMed1994

Allelotype of human bladder cancer.

To identify common regions of deletion in human bladder tumors, we have screened 83 cases of transitional cell carcinoma for loss of heterozygosity (LOH) on all autosomal chromosome arms. Seventy-two restriction fragment length polymorphism, variable number of tandem repeats, and minisatellite markers and 18 microsatellite markers were used to obtain a minimum of 50% informative results for each chromosome arm. A mean of 29.6 informative results per patient was obtained from 39 chromosome arms studied, representing information for 76% of chromosome arms. The most frequent losses were apparent monosomies of chromosome 9 (9p, 51%; 9q, 57%). Other frequent losses were on chromosomes 11p (32%), 17p (32%), 8p (23%), 4p (22%), and 13q (15%). LOH of 4p has not been reported previously in bladder carcinoma. The frequency of LOH on all other chromosome arms was < 12%. LOH on chromosome 8p showed a significant association with both high tumor grade and stage, and LOH on 13q showed a significant association with high tumor grade. Fractional allelic loss was calculated for all tumors and had a mean of 0.125 and a median of 0.110. A significant association was found between increased fractional allelic loss and higher tumor grade. An association was also found between LOH of chromosomes 8p and 9q and values for fractional allelic loss > or = the median value. No associations were found between LOH on different pairs of chromosome arms.

Alleles↗
PubMed1994

Monitoring of cerebrospinal dynamics using continuous analysis of intracranial pressure and cerebral perfusion pressure in head injury.

Cerebrospinal dynamics has been investigated by statistical analysis of results of computerised monitoring of 80 head injured patients admitted to the Intensive Care Unit at Pinderfields General Hospital. One minute average values of intracranial pressure (ICP), systemic arterial pressure (ABP), cerebral perfusion pressure (CPP), amplitude of the fundamental component of the intracranial pressure pulse wave and the short-term moving correlation coefficient between that amplitude and mean ICP (RAP) were recorded. It was found that reduction of CPP down to 40 mmHg was more often caused by decrease in ABP than increase in ICP. Further falls in CPP below 40 mmHg were caused by substantial increases in ICP above 25 mmHg. The relationship between the ICP pulse wave amplitude and CPP showed a significant gradual increase in amplitude with CPP decreasing from 75 to 30 mmHg. For CPP below 30 mmHg there is a sharp decrease in amplitude followed by a change in the coefficient RAP from positive to negative values. This was interpreted as a sign of critical disturbance in cerebral circulation.

Blood Pressure↗
PubMed1994

Internal anal sphincter activity after restorative proctocolectomy for ulcerative colitis: a study using continuous ambulatory manometry.

PURPOSE: The aim of this study was to further investigate continuous ambulatory anal manometry which has recently been introduced as a method for studying anorectal activity in ambulant patients, thereby avoiding many of the potential drawbacks of static techniques. METHOD: In this study continuous ambulatory manometry was used to assess the activity of the internal anal sphincter in patients who had undergone restorative proctocolectomy, and, in particular, to compare patients who had undergone conventional mucosal proctectomy with sutured endoanal, ileoanal anastomosis with patients who had undergone restorative proctocolectomy with preservation of the entire anal canal by means of stapled, end-to-end, ileoanal anastomosis without mucosectomy. RESULTS: Evidence of basal internal sphincter activity was found in only 38 percent of patients after mucosal proctectomy with sutured endoanal anastomosis, whereas all patients after restorative proctocolectomy with stapled end-to-end anastomosis and all control individuals showed such activity of the internal sphincter. Similarly, the number of sampling episodes seen in patients after mucosal proctectomy with endoanal anastomosis was significantly less (median, 0.0/hours (0-30/hours)) than the number of sampling episodes observed in patients after end-to-end anastomosis (median, 4.5/hours (1-48/hours)) or in control individuals (median, 5.6/hours (0-31/hours)) (P < 0.001). CONCLUSIONS: These results suggest that the internal anal sphincter is damaged in the course of mucosal proctectomy and endoanal anastomosis. In contrast, after restorative proctocolectomy with stapled, end-to-end anastomosis normal function of the internal sphincter is preserved.

Adult↗
PubMed1993

Mutation of H-ras is infrequent in bladder cancer: confirmation by single-strand conformation polymorphism analysis, designed restriction fragment length polymorphisms, and direct sequencing.

A series of 152 human bladder tumors, 14 bladder tumor cell lines, and 1 immortal urothelial cell line were examined by single-strand conformation polymorphism (SSCP) and designed restriction fragment.length polymorphism analyses for mutations in exons 1 and 2 of the H-ras gene. Nine tumors (6%) contained mutations. There was complete concordance between SSCP and restriction fragment length polymorphism analyses. Six mutations in exon 1 and three in exon 2 were identified by SSCP analysis. Subsequent restriction fragment length polymorphism analysis showed that of the exon 1 mutations, four were in codon 12 and two in codon 13, and all three exon 2 mutations were in codon 61. Eight mutations were confirmed by direct sequencing. One codon 13 mutation could not be identified by direct sequencing. Distinct strand mobility shifts detected by SSCP analysis identified specific point mutations, and in all cases, strands containing different mutations migrated differently. The base substitutions identified in these bladder tumors were diverse and included four transversions (three G-->T and one A-->T) and four transitions (two G-->A and two A-->G). This pattern of base substitutions is compatible with interactions of the urothelium with more than one class of environmental agent during bladder tumor development. No correlation was found between tumor grade and/or stage and the presence of H-ras mutation. We conclude that H-ras mutation does not play a role in the development of the majority of transitional cell tumors of the bladder.

Base Sequence↗
PubMed1993

Management of synergistic bacterial gangrene in severely immunocompromised patients. Report of four cases.

We present four cases of perianal synergistic gangrene in severely immunocompromised patients. In all patients, gangrene was controlled by radical surgery, including defunctioning colostomy in three patients, backed up by appropriate antibiotic therapy. Three of the patients survived and left the hospital; the fourth died in the intensive care unit of overwhelming sepsis from an unidentified source other than the anus. We review the literature and conclude that such infections in these patients are not inevitably fatal and that radical surgery can result in a cure.

Adult↗
PubMed1993

A 5' splice site mutation in fucosidosis.

Fucosidosis is a rare, autosomal recessive, lysosomal storage disease, resulting from a deficiency of the enzyme alpha-fucosidase (EC 3.2.1.51). It is characterised clinically by progressive mental and motor deterioration, growth retardation, coarse facies, and often recurrent infections, but the course of the disease is variable. The gene encoding lysosomal alpha-fucosidase has been mapped to the short arm of chromosome 1 at position 1p34.1-36.1 and has been called FUCA1. Two mutations causing disease have been described previously, a C-->T change in exon 8 giving rise to a premature, in frame TAA stop codon, and a deletion of at least two exons from the 3' end of the gene. In this paper we present evidence that a homozygous G-->A transition in the first position of the 5' splice site of intron 5 of FUCA1 is the disease causing mutation in a 9 year old child of distantly related parents. A new banding pattern was detected in the patient by Southern blotting of genomic DNA using TaqI restriction and a cDNA FUCA1 probe. The patient was homozygous for this pattern. Three sibs with alpha-fucosidase activity below the normal reference range and both parents were heterozygous. This pattern was not detected in 26 other fucosidosis patients and has not been found in any controls. The mutation was localised by a combination of restriction mapping using different cDNA probes, single stranded conformational polymorphism analysis of exons and flanking regions amplified by the polymerase chain reaction, and by direct sequencing of the amplified sequence. A view of the nature of the mutation, its cosegregation with the disease mutation and its absence in controls, it is probable that the 5' splice site mutation causes fucosidosis in this child.

Base Sequence↗
PubMed1992

Cloning of a cDNA encoding the ovine interleukin-2 receptor 55-kDa protein, CD25.

A 1.3-kb cDNA that encodes the entire 825-bp coding region of ovine CD25, the interleukin-2 receptor 55-kDa protein, has been isolated. Comparison of the deduced amino acid sequence with CD25 proteins from other species shows the ovine sequence to have the greatest homology with that of the bovine species.

Amino Acid Sequence↗
PubMed1991

Refined crystal structure of Cd, Zn metallothionein at 2.0 A resolution.

The crystal structure of Cd5,Zn2-metallothionein from rat liver has been refined at 2.0 A resolution of a R-value of 0.176 for all observed data. The five Cd positions in the asymmetric unit of the crystal create a pseudo-centrosymmetric constellation about a crystallographic 2-fold axis. Consequently, the distribution of anomalous differences is almost ideally centrosymmetric. Therefore, the previously reported metal positions and the protein model derived therefrom are incorrect. Direct methods were applied to the protein amplitudes to locate the Cd positions. The new positions were used to calculate a new electron density map based on the Cd anomalous scattering and partial structure to model the metal clusters and the protein. Phases calculated from this model predict the positions of three sites in a (NH4)2WS4 derivative. Single isomorphous replacement phases calculated with these tungsten sites confirm the positions of the Cd sites from the new direct methods calculations. The refined metallothionein structure has a root-mean-square deviation of 0.016 A from ideality of bonds and normal stereochemistry of phi, phi and chi torsion angles. The metallothionein crystal structure is in agreement with the structures for the alpha and beta domains in solution derived by nuclear magnetic resonance methods. The overall chain folds and all metal to cysteine bonds are the same in the two structure determinations. The handedness of a short helix in the alpha-domain (residues 41 to 45) is the same in both structures. The crystal structure provides information concerning the metal cluster geometry and cysteine solvent accessibility and side-chain stereochemistry. Short cysteine peptide sequences repeated in the structure adopt restricted conformations which favor the formation of amide to sulfur hydrogen bonds. The crystal packing reveals intimate association of molecules about the diagonal 2-fold axes and trapped ions of crystallization (modeled as phosphate and sodium). Variation in the chemical and structural environments of the metal sites is in accord with data for metal exchange reactions in metallothioneins.

Amino Acid Sequence↗
PubMed1991

Effects of mcr restriction of methylated CpG islands of the L1 transposons during packaging and plating stages of mammalian genomic library construction.

The use of optimally methylation-tolerant mcrA- mcrB- strains has been shown to produce an over tenfold increase in the plating efficiencies of mammalian genomic libraries, compared to a superior conventional phage host strain LE392 which is mcrB+. However, there is an even more significant effect of mcr restriction. Amongst the recombinants recovered with an mcrB+ host, we have found that there is an additional 30-fold reduction in the frequencies of clones containing the heavily methylated 5'-CpG island sequences of both the human and rat L1 repetitive elements. The mcrA product was also found to restrict clones of these methylated genomic segments, but not as strongly as mcrB. However, the use of packaging extracts made from mcrA+ lysogens did not result in convincing reductions in the recoveries of these dispersed methylated elements. The magnitude of mcr restriction during plating due to methylated dispersed elements is sufficient to make a significant proportion of mammalian genomes unclonable from genomic libraries constructed previously using conventional mcr+ hosts.

Animals↗
PubMed1991

AuthorBase: a database of authoring systems software.

A working prototype database of authoring system software was developed as part of a study of authoring software conducted by the National Library of Medicine. The database and development issues ranging from the scope of the database to what information to document are described. The protype demonstrates that records of reasonable integrity can be derived from vendor supplied information as long as users understand the database is only an initial starting point in searching for authoring software and a resource for becoming generally familiar with the technology.

Authorship↗
PubMed1990

Mismatch repair-induced meiotic recombination requires the pms1 gene product.

The presence of multiple heterologies in a 9-kilobase (kb) interval results in a decrease in meiotic crossovers from 26.0% to 10.1%. There is also an increase from 3.5% to 11.1% in gene conversions and ectopic recombinations between the flanking homologous MAT loci. The hypothesis that mismatch repair of heteroduplex DNA containing several heterologies would lead to a second round of recombination has now been tested by examining the effect of a mutation that reduces mismatch correction. The repair-defective pms1-1 allele restores the pattern of recombination to nearly that seen in congenic diploids without the heterologies. Mismatch repair-induced recombination causes a significant increase in MAT conversions and ectopic recombination events with as few as two heterozygosities separated by 0.3-0.7 kb, but not when the mismatches are separated by greater than 1 kb. The frequency of these events depends on both the number and position of the heterozygosities relative to the flanking homologous MAT loci used to detect the events. The creation of recombinogenic lesions by mismatch repair in yeast could be analogous to the creation of recombinogenic lesions in dam- Escherichia coli. We suggest that the repair of heteroduplex DNA containing multiple mismatches may produce chromosomal rearrangements and gamete inviability when naturally polymorphic chromosomes undergo meiotic recombination.

Alleles↗