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Biomedical subjects

A Smith

Publications and source records attributed to A Smith.

At least 739 records · Page 41Linked to original sources
PubMed1994

Bloom syndrome and maternal uniparental disomy for chromosome 15.

Bloom syndrome (BS) is an autosomal recessive disorder characterized by increases in the frequency of sister-chromatid exchange and in the incidence of malignancy. Chromosome-transfer studies have shown the BS locus to map to chromosome 15q. This report describes a subject with features of both BS and Prader-Willi syndrome (PWS). Molecular analysis showed maternal uniparental disomy for chromosome 15. Meiotic recombination between the two disomic chromosomes 15 has resulted in heterodisomy for proximal 15q and isodisomy for distal 15q. In this individual BS is probably due to homozygosity for a gene that is telomeric to D15S95 (15q25), rather than to genetic imprinting, the mechanism responsible for the development of PWS. This report represents the first application of disomy analysis to the regional localization of a disease gene. This strategy promises to be useful in the genetic mapping of other uncommon autosomal recessive conditions.

Bloom Syndrome↗
PubMed1994

Comparison of employees' white blood cell counts in a petrochemical plant by worksite and race.

To determine if employment within a petrochemical plant's quality control (QC) laboratory had any significant effect on the hematopoietic system, and in specific, the white blood cell (WBC) counts, all employees of the QC laboratory were evaluated retrospectively. Trend analysis, linear regression, and Students t tests were performed on all employees of the QC laboratory and on a simple random sample of the rest of this Caribbean petrochemical plant's male employees. Trend analyses revealed a downward trend in 82.6% of the QC laboratory workers and 76.7% in other plant workers. Linear regression and t tests revealed no statistically significant difference by worksite but a significant difference between blacks and whites. The result of the findings of the QC laboratory workers was consistent with that expected in both plant employees and the US general population. A recommendation is made that the Occupational Safety and Health Administration (OSHA) reconsider its WBC cutoff level in the benzene standard.

Adult↗
PubMed1994

The analysis of failure or success with oral and maxillofacial implants.

Prospective and retrospective studies on oral and maxillofacial osseointegrated implants have been performed and 'success' rates are reported to be very high. A critical analysis of the literature and anecdotal discussion with surgeons and prosthodontists alike, suggests that 'failures' occur considerably more frequently than is documented. This paper does not give a practical guide to the prevention or management of complications but it discusses the concepts of 'success' and 'failure' in implantology. Improvements in definitions, terminology and study design protocols are required together with research producing scientifically analytic and reproducible results rather than the present philosophy of the importance of the percentage of the commercial market share will allow an accurate analysis of the value and role of oral and maxillofacial implants.

Dental Implants↗
PubMed1994

Chromosomal abnormalities detected after an abnormal ultrasound in pregnancy.

Improvements in ultrasound technology have resulted in an increasing number of requests for prenatal chromosome testing because of fetal abnormalities detected in utero. Between January 1990--January 1991, 388 tissue samples were referred to our laboratory for cytogenetic analysis, of which 202 were amniotic fluids samples, 157 chorionic villus biopsies and 29 fetal blood specimens. Of these 54 were referred for fetal abnormalities detected prenatally on high resolution ultrasound. Chromosomal analysis was successful in 50 cases, and included 6 (12%) chromosomally abnormal fetuses: 2 trisomy 21, 2 trisomy 18, one 45,X and one unbalanced translocation. The maternal age for three of the four cases of autosomal trisomy were below 35 years (the cut-off for amniocentesis for advanced maternal age). In contrast, 273 prenatal chromosome studies performed for advanced maternal age (AMA) produced only 4 (1.5%) chromosomally abnormal fetuses. These abnormalities detected on ultrasound indicate a significant population of fetal chromosomal aberrations which would otherwise not be detected prenatally.

Adult↗
PubMed1994

Atrioventricular conduction system in hearts with muscular ventricular septal defects in the setting of complete transposition.

The detailed structure of a ventricular septal defect was compared in 90 hearts with complete transposition (concordant atrioventricular and discordant ventriculoarterial connections) and in 102 hearts with concordant connections at both junctions; the latter group was selected to include only cases with the septums aligned in the normal way. The interventricular communications observed in 13% of the group with complete transposition, which, in our material, had no counterpart in the hearts with concordant segmental connections, were of special interest. These defects, completely surrounded by muscle, were positioned around the midline on the right side of the septum but always lay under or partially under the septal leaflet of the tricuspid valve. The medial papillary muscle group was always to the "left hand margin" of the defect as seen by the surgeon. Because these defects lay within the boundaries set by the septal leaflet of the tricuspid valve, they would conform to the criteria for classification as inlet muscular defects but could equally be described as central or subtricuspid. It is significant that, in all those cases with histologic sectioning, the axis of atrioventricular conduction tissue ran to the surgeon's right hand margin. This position is markedly different from the pattern found in typical defects of the inlet septum, which are completely surrounded by muscle and extend to the posterior wall of the heart. In this more common situation, the conduction axis runs above the left hand margin of the defect. This finding has obvious implications for surgical treatment.

Heart Conduction System↗
PubMed1994

Trends in prostate cancer incidence and mortality in New Mexico are consistent with an increase in effective screening.

The increasing occurrence of prostate cancer in the United States has led to recommendations for routine prostate cancer screening in men aged 50 years and older. Although present methods of prostate cancer screening have not been shown to reduce mortality, screening using digital rectal examination or prostate-specific antigen does detect tumors at earlier stages. To assess whether trends in incidence and mortality rates are consistent with an increase in effective screening in New Mexico, we examined prostate cancer incidence rates calculated from data collected by the New Mexico Tumor Registry for the years 1969-1991, and mortality rates calculated from data collected by the New Mexico Bureau of Vital Statistics for the years 1958-1991. Population-based measures of prostate cancer screening frequency in New Mexico are not available for the period of this study; however, the proportion of prostate cancers detected by screening, as documented by a review of records from a random sample of prostate cancer cases, increased 3-fold, from 13% during the 1969-1972 period to 41% in the 1988-1991 period. During the period of study, age-adjusted incidence rates increased from 66.3 to 122.3/100,000 men. Stage migration from distant to earlier stages was apparent in the increase in the proportion of early stage cancers from 77.5 to 85.5%, and the decrease of distant stage cancers from 21.2 to 9.8%. Stage-specific incidence rates increased for local (87.3%) and regional stage cancers (283.0%), and decreased for distant stage cancers (16.0%).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

Case management and nursing practice.

Does adopting a case management model alter nursing practice? The authors examine the effect case management has on nurse-client relationships and nurse-colleague relationships and explore how nurses are using case management as a vehicle to achieve professionalism. The article is based on a literature review of case management for community-dwelling elderly residents and interviews with 17 community-based nurses practicing as case managers in Canada.

Canada↗
PubMed1994

Double-blind comparison of intranasal fluticasone propionate, 200 micrograms, once daily with 200 micrograms twice daily in the treatment of patients with severe seasonal allergic rhinitis to ragweed.

In a single-center, double-blind, crossover study of 90 subjects, fluticasone propionate aqueous nasal spray, 200 micrograms, once daily was compared with 200 micrograms twice daily in severe seasonal allergic rhinitis to ragweed. The mean percentage of days free of nasal itching and eye symptoms was significantly higher with twice daily fluticasone propionate (P = .004, P = .005, respectively). There were no significant differences between the two treatment groups for nasal blockage, rhinorrhea (runny nose), and sneezing. The median symptom scores for nasal itching were lower during twice daily treatment (P = .008) but there was no significant difference for the other symptoms. There were no significant differences between the groups in the use of rescue medication. Adverse events were infrequent, and similar in both groups. Most were considered unrelated to the treatment. Twice daily treatment with fluticasone propionate may be preferable for some patients with severe seasonal allergic rhinitis.

Administration, Intranasal↗
PubMed1993

Fallot's tetralogy with absent pulmonary valve and anomalous origin of the left pulmonary artery.

A 1-day-old asymptomatic neonate with a to and fro precordial murmur was diagnosed by cross sectional echocardiography to have Fallot's tetralogy with absent pulmonary valve, and origin of the left pulmonary artery from the ascending aorta. Moderate stenoses at the origin of the anomalous left pulmonary artery and of the right pulmonary artery were present, allowing definitive surgical correction to be deferred.

Aorta↗
PubMed1993

Preclinical evaluation of 67Cu-labeled intact and fragmented anti-colon carcinoma monoclonal antibody MAb35.

The anti-carcinoembryonic antigen murine monoclonal antibody MAb35 and its F(ab')2 fragment were labeled with 131I or the potential therapeutic nuclide 67Cu. In vivo distribution patterns were compared in nude mice bearing human tumor xenografts by coinjection of the 131I- and 67Cu-labeled materials, thereby minimizing variations due to xenograft and host animal. The results showed that the 67Cu-labeled intact MAb35 achieved twice the percentage of injected dose/g tumor when compared to its 131I-labeled counterpart, without significant impairment of the wholebody distribution pattern. However, this effect was not evident in the case of F(ab')2, where high uptake of 67Cu was found in the kidney without any enhancement of accumulation in the target xenografts. To investigate the underlying causes of the different distribution patterns observed, iodine labeling was also performed using a more stable linkage, and the results indicated that the observed differences cannot be explained by simple deiodination of conventionally labeled preparations. We conclude that the intact form of the 67Cu-labeled antibody may be superior to the F(ab')2 fragment for use in our intended clinical studies. Our continuing work on the processing of radiometal-labeled F(ab')2 fragments, at the systemic and cellular level, will hopefully lead to a strategy to circumvent the problem of high kidney accumulation.

Animals↗
PubMed1993

Synthesis of the K5 (group II) capsular polysaccharide in transport-deficient recombinant Escherichia coli.

The genes directing the expression of group II capsules in Escherichia coli are organized into three regions. The central region 2 is type specific and thought to determine the synthesis of the respective polysaccharide, whilst the flanking regions 1 and 3 are common to all group II gene clusters and direct the surface expression of the capsular polysaccharide. In this communication we analyze the involvement of region 1 and 3 genes in the synthesis of the capsular KS polysaccharide. Recombinant E. coli strains harboring all KS specific region 2 genes and having various combinations of region 1 and 3 genes were studied using immunoelectron microscopy. Membranes from these bacteria were incubated with UDP[14C]GlcA and UDPGlcNAc in the absence or presence of KS polysaccharide as an exogenous acceptor. It was found that recombinant strains with only gene region 2 did not produce the K5 polysaccharide. Membranes of such strains did not synthesize the polymer and did not elongate K5 polysaccharide added as an exogenous acceptor. An involvement of genes from region 1 (notably kpsC and kpsS) and from region 3 (notably kpsT) in the K5 polysaccharide synthesis was apparent and is discussed.

Antigens, Bacterial↗
PubMed1993

Novel patterns of inheritance of genetic disease are illustrated by the Angelman syndrome.

OBJECTIVE: To characterise the molecular abnormalities present in a cohort of patients with the Angelman syndrome. METHODS: DNA samples from 10 patients with the Angelman syndrome were investigated with molecular probes. Family studies were performed by means of DNA polymorphism analysis and densitometric estimation of allele copy number to determine the underlying mutation and its parental origin. RESULTS: Nine probands were shown to have molecular (DNA) deletions involving chromosome 15q11-q13. Polymorphism analyses demonstrated that all deletions were maternal in origin. Five of the nine had normal karyotypes, with deletions only detected after DNA study. One patient had inherited both chromosomes 15 from her father. This represented an example of paternal uniparental disomy of chromosome 15. CONCLUSIONS: Development of the Angelman syndrome can result from either deletion of the maternally-derived copy of chromosome 15q11-q13 or the presence of two paternally derived copies of chromosome 15, that is, uniparental disomy. DNA testing allows the identification of deletions that are not seen on cytogenetic analysis and can provide additional information regarding the parental origin of the deletion. Uniparental disomy is most readily established by DNA studies.

Adolescent↗
PubMed1993

Regulation of heme oxygenase and metallothionein gene expression by the heme analogs, cobalt-, and tin-protoporphyrin.

Two heme analogs, cobalt- and tin-protoporphyrin (CoPP and SnPP, respectively) have been used to probe the heme-hemopexin interaction, hemopexin receptor binding, and the mechanism of regulation of heme oxygenase (HO) and metallothionein-1 (MT-1) gene expression by hemopexin. Both CoPP and SnPP are HO inhibitors and hemopexin binds SnPP (Morgan, W. T., Alam, J., Deaciuc, V., Muster, P., Tatum, F. M., and Smith, A. (1988) J. Biol. Chem. 263, 8226-8231) and CoPP. The association of CoPP with hemopexin produces characteristic changes in the absorbance spectrum of CoPP and quenches the intrinsic fluorescence of hemopexin. Binding of CoPP is tight (Kd ca. 3 x 10(-7) M) although of lower affinity than heme itself (Kd < pM); and CoPP binding, like heme, produces conformational changes in hemopexin shown by an increase in the molar ellipticity at 233 nm and affords protection from proteolysis of the hinge region between the two structural domains of hemopexin. The coordination of the central cobalt atom is predicted to be similar to that of heme and to involve His56 and His127 of rabbit hemopexin. Furthermore, CoPP-hemopexin, like SnPP-hemopexin, binds to the hemopexin receptor as shown by competitive inhibition studies with radioactive heme-hemopexin. The effect of free heme analogs and their hemopexin complexes on HO and MT gene regulation was investigated and compared with the extent of induction by heme and heme-hemopexin. Free CoPP is a more effective inducer of HO steady state mRNA levels than free heme and produces a 5-fold increase within 1 h compared to only a 2-fold increase with heme, but free SnPP (up to 10 microM) produces no detectable increase in HO mRNA. In contrast, by 3 h heme-hemopexin and SnPP-hemopexin increase HO mRNA levels 11- and 6-fold, respectively; but the CoPP-hemopexin complex causes no detectable change in HO mRNA levels. The complexes of hemopexin with heme or either of the two heme analogs are effective inducers of metallothionein (MT) mRNA. Induction of MT mRNA by heme-hemopexin is rapid, increasing 4-fold within 1 h and 14-fold by 3-4 h. Strikingly, an even more rapid and slightly more extensive induction of MT mRNA is seen in response to either CoPP- or SnPP-hemopexin complexes, with MT mRNA rising 8-fold within 1 h. In contrast, free heme and the free analogs are far less effective inducers, increasing MT and mRNA levels and in vitro transcription rates only 3-4-fold and declining after 2-3 h.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1993

Identification of the histidine residues of hemopexin that coordinate with heme-iron and of a receptor-binding region.

Rabbit hemopexin cDNA was cloned from a rabbit liver lambda gt11 cDNA expression library using a mixture of five monoclonal antibodies raised against rabbit hemopexin, and the entire rabbit hemopexin sequence was determined. The heme-binding domain I of rabbit hemopexin (Smith, A., and Morgan, W. T. (1984) J. Biol. Chem. 259, 12049-12053) contains only 4 histidine residues which are conserved in rabbit, human, rat, and mouse hemopexin. The 2 axial heme-iron coordinating histidine residues, identified by Edman microsequencing and amino acid analyses of chemically modified domain I and isolated fragments of domain I, are the conserved histidine residues at positions 56 and 127 of the mature rabbit protein. The epitope recognized by JEN-14 (a monoclonal antibody which specifically reacts with domain I and blocks the hemopexin-receptor interaction (Morgan, W. T., Muster, P., Tatum, F. M., McConnell, J., Conway, T. P., Hensley, P., and Smith, A. (1988) J. Biol. Chem. 263, 8220-8225) was shown to lie between residues 122 and 142 by Western blotting of protease-digested domain I and transposon-insertion mutants of domain I expressed in a plasmid vector system. The location of this epitope near the heme-binding histidine residue 127 is compatible with a transport mechanism in which the release of heme from hemopexin is accompanied by a concomitant transfer of heme to the hemopexin receptor or the membrane heme-binding protein (Smith, A., and Morgan, W. T. (1985) J. Biol. Chem. 260, 8325-8329).

Amino Acid Sequence↗