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Biomedical subjects

S D Smith

Publications and source records attributed to S D Smith.

At least 127 records · Page 7Linked to original sources
PubMed1995

Homozygous deletions of the CDKN2 (MTS1/p16ink4) gene in cell lines established from children with acute lymphoblastic leukemia.

Homozygous deletions of the CDKN2 (MTS1/p16ink4) gene have been found at high frequency in cell lines derived from a variety of adult solid tumors. In order to investigate the status of the CDKN2 gene in cell lines established from childhood acute lymphoblastic leukemia (ALL), we surveyed 25 lines representing the major pediatric ALL phenotypes for the presence of this gene by Southern blot analysis. Homozygous deletions of all or part of the CDKN2 gene were detected in 21 (84%) cell lines, including 11 of 14 (79%) early-pre-B-ALL, four of five (80%) pre-B-ALL, and six of six T-ALL lines. CDN2 mRNA was detected by Northern blotting in each of the four lines containing an intact CDKN2 gene. These data suggest an important role for CDKN2 deletion in the cause and/or progression of pediatric ALL.

Blotting, Northern↗
PubMed1995

Overview of genetic auditory syndromes.

Accurate determination of the cause of hearing loss is critically important for clinicians for prognosis and management. Recognition of genetic syndromes is especially important, but this is dependent upon clear delineation of the characteristics of the syndromes. Research into underlying mechanisms of hearing loss is also much more effective if the cause of the hearing loss is known to be the same in the subjects being studied. Family studies of hearing loss can be very important in determining the phenotypic range of the condition, but it has become clear that phenotypically similar families may not actually have the same genetic cause. Molecular genetic studies are needed to determine which genes, and even which mutations within genes, are responsible for specific syndromes. This paper reviews the methodology of gene localization (linkage) studies and describes a variety of genetic conditions, syndromic and nonsyndromic, which illustrate the varying relationships between genes, phenotypes, and mechanisms of hearing loss. Knowledge of the cause of hearing loss will facilitate understanding of the auditory system and development of optimum therapy.

Chromosomes, Human, Pair 2↗
PubMed1995

Linking the professional literature to nursing practice: challenges and opportunities.

Occupational health nurses face the challenge of rapidly changing, increasingly complex work environments. To respond, they must have access to information and know how to manage it effectively to improve their clinical performance and achieve better client outcomes. Information technology has already had an impact on nursing. Many nurses routinely use computers to access laboratory reports, client records, and administrative programs. However few nurses make use of opportunities provided by information technology to access professional literature as a tool for applying new research to their practice.

Humans↗
PubMed1995

Bulimic weight-loss behaviors in military versus civilian weight-management programs.

This descriptive study evaluated the presence of bulimic weight-loss behaviors in individuals enrolled in: (1) a military weight-management program (N = 51); (2) a civilian weight-management program (N = 53); and (3) a comparison (military normal-weight) group (N = 51). A modified version of the Stanford Eating Disorders Questionnaire was administered to all subjects. The results indicated that the military weight-management program group reported that they engaged in bulimic weight-loss behaviors two to five times more often than the comparison group, and that they engaged in vomiting, strenuous exercise, or use of sauna/steam room four times as often as the civilian weight-management program group. The results suggest that bulimic weight-loss behaviors may develop in individuals who feel extreme pressure to lose weight.

Adolescent↗
PubMed1994

Quantitative trait locus for reading disability on chromosome 6.

Interval mapping of data from two independent samples of sib pairs, at least one member of whom was reading disabled, revealed evidence for a quantitative trait locus (QTL) on chromosome 6. Results obtained from analyses of reading performance from 114 sib pairs genotyped for DNA markers localized the QTL to 6p21.3. Analyses of corresponding data from an independent sample of 50 dizygotic twin pairs provided evidence for linkage to the same region. In combination, the replicate samples yielded a chi 2 value of 16.73 (P = 0.0002). Examination of twin and kindred siblings with more extreme deficits in reading performance yielded even stronger evidence for a QTL (chi 2 = 27.35, P < 0.00001). The position of the QTL was narrowly defined with a 100:1 confidence interval to a 2-centimorgan region within the human leukocyte antigen complex.

Adolescent↗
PubMed1994

Establishment of a leukemia cell line with i(12p) from a patient with a mediastinal germ cell tumor and acute lymphoblastic leukemia.

We report the establishment of a leukemia cell line (UoC-B10) from a patient who developed leukemia several months after the diagnosis of a mediastinal yolk sac tumor. The patient's yolk sac tumor responded to combination chemotherapy, and a mature teratoma with focal areas of hematopoiesis was subsequently resected. However, 5 months after the initial diagnosis, the patient developed an acute lymphoblastic leukemia with a precursor B-cell phenotype. Cytogenetic analysis showed an i(12p) abnormality in the patient's leukemia cells and in the UoC-B10 cell line. The i(12p) was also identified retrospectively in the mediastinal tumor cells by fluorescent in situ hybridization analysis. The UoC-B10 cell line, which has been growing continuously for > 24 months in culture, was Epstein-Barr virus negative and was generally concordant with the patient's leukemia cells by analysis of immunophenotype, karyotype, and genotype. The UoC-B10 cell line possesses receptors for granulocyte-colony-stimulating factor, a cytokine which the patient received as part of his treatment protocol. This cell line may be useful in studying the relationship between i(12p) and hematological differentiation of human mediastinal germ cell tumors.

Adult↗
PubMed1994

Linkage of autosomal dominant hearing loss to the short arm of chromosome 1 in two families.

BACKGROUND: At least half of the cases of profound deafness of early onset are caused by genetic factors, but few of the genetic defects have been identified. This is particularly true of the most common hereditary forms of deafness, which occur in the absence of any associated syndrome. METHODS: We studied a large Indonesian family in which hearing loss was inherited in an autosomal dominant pattern. The hearing loss first affects the high frequencies during the teens or 20s and becomes profound within 10 years. To locate the responsible gene, we performed genetic-linkage analysis, using microsatellite markers distributed over the entire genome. We then performed linkage analyses in an American family and a Dutch family with similar patterns of hereditary hearing loss. RESULTS: In the extended Indonesian family, a gene linked to deafness mapped to chromosome 1p, with a multipoint lod score of more than 7. In the American family, deafness was linked to the same locus on chromosome 1p, with a multipoint lod score of more than 5. In the Dutch family, however, this locus was ruled out. The flanking markers D1S255 and D1S211 defined a region of 6 cM on chromosome 1p that is likely to contain the gene associated with deafness in the first two families. CONCLUSIONS: In some families with early-onset autosomal dominant hearing loss, the responsible gene is on chromosome 1p.

Adolescent↗
PubMed1994

Congenital anaemia after transplacental B19 parvovirus infection.

We report three children with congenital anaemia after intrauterine infection with B19 parvovirus. All the fetuses developed hydrops fetalis that was treated by blood transfusion. After delivery the infants had hypogammaglobulinaemia. In all three, sera lacked B19 but viral DNA was found in bone marrow. All were treated with immunoglobulin. One child died and B19 was found in various tissues. In the other two cases, virus could no longer be detected after therapy but the patients remain persistently anaemic. Persistent B19 infection should be suspected in infants with congenital red-cell aplasia.

Agammaglobulinemia↗
PubMed1994

Molecular-weight factors affecting formation of the OBDD morphology in block copolymer blends.

Block copolymers undergo self-organization when the blocks are sufficiently incompatible, and generate a variety of periodic morphologies in the limit of strong segregation. An equilibrium morphology only recently added to the diblock copolymer phase diagram is the ordered bicontinuous double-diamond (OBDD) morphology, which possess a Pn3m space group. It has been observed over a very narrow composition range (ca. 4 vol%), thereby making it difficult to obtain in pure copolymers. This obstacle can, however, be surmounted by blending a copolymer with one of the parent homopolymers. In the present study, several symmetric poly(styrene-b-isoprene) diblock copolymers varying in molecular weight (M) have been blended with homopolystyrene to produce the OBDD morphology. Transmission electron microscopy is employed here to identify the morphologies in cryosections of each blend and reveals that, at intermediate molecular weights, the OBDD morphology is indeed observed. At low M, near the order-disorder transition, however, a lamellar catenoid or disordered morphology is preferred. At the other extreme, high-M blends are frustrated by molecular entanglements and adopt a cylindrical morphology.

Butadienes↗
PubMed1994

Involvement of nitric oxide and cyclic GMP in rabbit urethral relaxation.

Soluble and particulate fractions from rabbit urethra converted [14C]arginine to [14C]citrulline, indicating the presence of nitric oxide synthase activity in these fractions. Both soluble and particulate nitric oxide synthase activities were NADPH dependent, and the soluble activity was Ca2+ dependent. Three nitric oxide synthase (NOS) inhibitors affected transmural nerve stimulation induced relaxation responses in the rabbit urethra and the activity of soluble nitric oxide synthase with the same rank order of potency, i.e., NG-nitro-L-arginine (NNA) > NG-methyl-L-arginine (NMA) > canavanine (CAN). The rank order of potency with respect to particulate NOS activity was CAN > NMA = NNA. The relaxation responses to electrical stimulation were accompanied by increases in cyclic GMP. These results suggest that NOS activity found in the soluble fraction of urethral homogenates produces nitric oxide that in turn increases cyclic GMP levels which mediates the relaxation responses induced by transmural nerve stimulation in the rabbit urethra.

Amino Acid Oxidoreductases↗
PubMed1994

Ion resonance electromagnetic field stimulation of fracture healing in rabbits with a fibular ostectomy.

Rabbits with a fibular ostectomy were exposed for 28 days to magnetic fields that satisfied the ion resonance conditions for calcium or magnesium. The rabbits were exposed to whole body treatment for 1/2 hour, 3 hours, or 24 hours per day. The fibulae from the experimental and control animals were removed surgically and were subjected to force-deflection testing to establish the stiffness of the healed fracture. The fibulae from the rabbits exposed to the ion resonance magnetic fields were found to be 55-299% (p < 0.01) more robust than the fibulae from the control animals.

Animals↗
PubMed1994

The role of the mucus gel layer in intestinal bacterial translocation.

The mucus gel layer is thought to be a vital component of the intestinal mucosal barrier. The purpose of this study is to determine if decreasing mucus production following ischemia and reoxygenation of the intestinal mucosa would alter bacterial translocation in an in vitro rat mucosal model. Clonidine was used to decrease mucus production associated with an ischemia/reoxygenation insult. Bacterial translocation was studied in a modified Ussing chamber using Escherichia coli K100. The quantity of mucus produced, as well as the incidence and quantity of bacteria translocating was measured. In the clonidine-treated animals, there was a significant decrease in the amount of mucus produced compared to the control animals. The clonidine animals also had a higher quantity of bacteria translocating during the reoxygenation period compared to the control animals. The mucus gel layer is protective against in vitro translocation of bacteria following an ischemia/reoxygenation insult.

Animals↗
PubMed1994

Delayed gastric emptying in neurologically impaired children with gastroesophageal reflux: the role of pyloroplasty.

The presence of delayed gastric emptying in neurologically impaired children with gastroesophageal reflux has led to controversy regarding appropriate surgical management. The authors reviewed the charts of neurologically impaired children requiring fundoplication to answer two questions: (1) is pyloroplasty needed in addition to fundoplication for delayed gastric emptying? and (2) Does delayed gastric emptying influence the morbidity associated with fundoplication? To answer the first question, 40 neurologically impaired children with delayed gastric emptying undergoing fundoplication were divided into two groups: Nissen and pyloroplasty (n = 21) and Nissen only (n = 19). The Nissen and pyloroplasty group had significantly more postoperative complications (23.8% v 5.0%) and took longer to reach full feeding (14.6 v 3.9) days. There were no differences in the incidence of recurrent symptoms, readmissions, or reoperations. To answer the second question, 58 neurologically impaired children undergoing fundoplication were grouped based on gastric emptying scan results: normal gastric emptying (> 32% in 1 hour) (n = 29) and delayed gastric emptying (n = 29). There were no differences in postoperative feeding tolerance, postoperative complications, recurrent symptoms, readmissions, or reoperations between the two groups. Delayed gastric emptying in neurologically impaired children with gastroesophageal reflux did not increase postoperative morbidity after fundoplication, and the addition of a pyloroplasty to fundoplication provided no additional benefit. The authors conclude that the procedure of choice for neurologically impaired children with gastroesophageal reflux is a fundoplication without pyloroplasty, regardless of the degree of delay in gastric emptying.

Child↗
PubMed1994

Nitric oxide synthase: an endogenous source of elevated nitrite in infected urine.

To further define the endogenous sources of urine nitrite in urinary tract infections, we measured urinary nitrite levels by the Griess method and assayed urinary nitric oxide (NO) synthase activity by the conversion of 14C-arginine to 14C-citrulline. Endogenous production of 14C-citrulline was confirmed by thin layer chromatography. Exogenous L-arginine increased nitrite production in whole infected urine, but not in bacteria isolated from infected urine. Urinary tract infections significantly increased NO synthase activity in soluble urine fractions, although soluble activity was less than 10% of particulate activity. Urine particulate fractions from women with non-infected urine had greater NO synthase activity than particulate fractions from men with non-infected urine, 11 +/- 2 and 0.2 +/- 0.1 picomol/min/mg protein, respectively. Urinary tract infections increased NO synthase activity in urine particulate fractions from women and men, 99 +/- 20 and 48 +/- 9 picomol/min/mg protein, respectively. The conversion of 14C-arginine to 14C-citrulline required NADPH, was calcium independent, and was inhibited to a greater extent by L-canavanine than by NG-monomethyl-L-arginine or NG-nitro-L-arginine. Human infected urine contains an isoform of NO synthase which is an endogenous source of urine nitrite.

Amino Acid Oxidoreductases↗
PubMed1994

Vasoconstriction with norepinephrine causes less forearm insulin resistance than a reflex sympathetic vasoconstriction.

We used the insulin-perfused human forearm model to assess the effects of vasoconstriction induced with norepinephrine on the extraction of glucose in the forearm in two groups of healthy young volunteers. The norepinephrine findings were compared with a previously studied group in which vasoconstriction has been caused by reflex activation of the sympathetic nervous system. The aim of the study was to determine the relative importance of hemodynamic and receptor-mediated mechanisms of insulin resistance. Plasma insulin, arterial and venous glucose samples, and forearm blood flow were measured at 10-minute intervals during a 30-minute baseline, a 60-minute intra-arterial insulin infusion, and during 30 minutes of insulin infusion plus vasoconstriction. Group 1 (n = 14) had physiological vasoconstriction induced by inflation of bilateral thigh cuffs to 40 mm Hg to cause pooling of blood in the lower extremities and reflex vasoconstriction in the forearm; group 2 (n = 8) had intra-arterial infusion of norepinephrine to achieve the same degree of vasoconstriction as seen with inflation of thigh cuffs in group 1. Subjects in group 3 (n = 7) had infusion of intra-arterial norepinephrine to achieve a twofold increase in physiological vasoconstriction. With a physiological decrease in forearm blood flow (group 1), there was a 19% decrease in forearm blood flow resulting in a 23% reduction in glucose uptake in the forearm (P < .03). The same degree of reduction in forearm blood flow with a predominantly alpha-adrenergic agonist, norepinephrine (group 2), causes much less insulin resistance (a decrease in utilization of 13%) (P < .04).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

The use of interest rate swaps in hospital capital finance.

This article describes the structure of an interest rate swap as it is commonly employed in hospital capital finance. It explores the role of the swap dealer as a facilitator of interest rate swap transactions and explains the motivation for doing so. Through the use of examples, the article details the incentives for hospitals to engage in interest rate swap transactions, including the desire to lower borrowing costs and/or to reduce exposure to interest rate risk. Finally, the article outlines the types of risks inherent in interest rate swap transactions.

Capital Financing↗