Showing papers by "Saint Louis University published in 1992"

DNA diversity among clinical isolates of Helicobacter pylori detected by PCR-based RAPD fingerprinting

Abstract: The RAPD (or AP-PCR) DNA fingerprinting method was used to distinguish among clinical isolates of Helicobacter pylori, a bacterium whose long term carriage is associated with gastritis, peptic ulcers and gastric carcinomas. This method uses arbitrarily chosen oligonucleotides to prime DNA synthesis from genomic sites to which they are fortuitously matched, or almost matched. Most 10-nt primers with > or = 60% G + C yielded strain-specific arrays of up to 15 prominent fragments, as did most longer (> or = 17-nt) primers, whereas most 10-nt primers with 50% G+C did not. Each of 64 independent H. pylori isolates, 60 of which were from patients in the same hospital, was distinguishable with a single RAPD primer, which suggests a high level of DNA sequence diversity within this species. In contrast, isolates from initial and followup biopsies were indistinguishable in each of three cases tested.

An early India-Asia contact: Paleomagnetic constraints from Ninetyeast Ridge, ODP Leg 121

Abstract: New paleomagnetic results from sedimentary rock and basement of the Ninetyeast Ridge (Ocean Drilling Program Leg 121, Sites 756-758) detail the northward movement of the Indian plate for the past 80 m.y. Analysis of the combined paleolatitude-age profile indicates a distinct reduction in India9s northward movement rate at 55+ Ma, interpreted as completion of suturing of Greater India and Asia. India9s northward motion slowed from 18-19.5 cm/yr to 4.5 cm/yr for the location of Site 758. Comparison of this profile with paleomagnetic data from the wider Himalayan region indicates that initial contact between northwestern Greater India and southern Asia was already established by Cretaceous-Tertiary time. This supports a possible causal link between the India-Asia convergence and the Deccan Traps extrusion.

Release of ATP from human erythrocytes in response to a brief period of hypoxia and hypercapnia

Abstract: Objective: The aims were, first, to detect and quantify the release of ATP from human erythrocytes in response to a brief exposure to a hypoxic/hypercapnic environment, similar to that found in vigorously exercising skeletal or cardiac muscle; and second, to explore the mechanism of ATP release in response to hypoxia. Methods: Washed human erythrocytes suspended in Krebs-Henseleit solution were exposed for 50 s to an atmosphere of ∼ 8.0 kPa Pco2 and 2.7 kPa Po2; ATP released into the suspension was assayed using the firefly luminescence technique. Samples of human blood were obtained by venepuncture of the median cubital vein from male and female volunteers ranging in age from 21 to 74 years. Anticoagulation was with EDTA. Results: A background of 0.49 × 106 (SEM 0.037 × 106) ATP molecules·cell−1 was attributed to spontaneous haemolysis of 1% of the cell population, as estimated by levels of haemoglobin measured in the suspension fluid. When the erythrocytes were exposed to the hypoxic/hypercapnic gas mixture at 37°C the ATP concentration in the suspension fluid rose to 2.67 × 106 (0.27 × 106) molecules·cell−1. An efflux rate of 276(37) molecules·μ−2·s−1 was calculated. The hypoxia induced ATP release was blocked in three different ways: first, by application of 50 μM of the specific band 3 anion channel blocking agents niflumic acid (a translocation inhibitor), DIDS (a transport site inhibitor), or dipyridamole (a channel blocker); secondly, by replacement of extracellular chloride and bicarbonate with the impermeant anion methanesulphonate; and thirdly, by application of 5 nM of the nucleoside transport blocker nitrobenzylthioinosine. None of these blocking techniques affected the background levels of ATP attributed to haemolysis. Conclusions: A situation of hypoxia/hypercapnia, such as would be found in exercising muscle, induces release of ATP from the erythrocyte via the plasma membrane protein moiety known as band 4.5 (a nucleoside transporter) and electrical balance across the erythrocyte membrane is maintained by the simultaneous influx of extracellular chloride and/or bicarbonate via the plasma membrane protein known as band 3 (anion channel). The circulation of erythrocytes into a region of hypoxia in vivo could promote an increase in local blood flow through release of endothelium dependent relaxing factor in response to released ATP.

The heterochromatin-associated protein HP-1 is an essential protein in Drosophila with dosage-dependent effects on position-effect variegation.

Abstract: Chromosome rearrangements which place euchromatic genes adjacent to a heterochromatic breakpoint frequently result in gene repression (position-effect variegation). This repression is thought to reflect the spreading of a heterochromatic structure into neighboring euchromatin. Two allelic dominant suppressors of position-effect variegation were found to contain mutations within the gene encoding the heterochromatin-specific chromosomal protein HP-1. The site of mutation for each allele is given: one converts Lys169 into a nonsense (ochre) codon, while the other is a frameshift after Ser10. In flies heterozygous for one of the mutant alleles (Su(var)2-504), a truncated HP-1 protein was detectable by Western blot analysis. An HP-1 minigene, consisting of HP-1 cDNA under the control of an Hsp70 heat-inducible promoter, was transduced into flies by P element-mediated germ line transformation. Heat-shock driven expression of this minigene results in elevated HP-1 protein level and enhancement of position-effect variegation. Levels of variegating gene expression thus appear to depend upon the level of expression of a heterochromatin-specific protein. The implications of these observations for mechanism of heterochromatic position effects and heterochromatin function are discussed.

A psychosocial cognitive model of employment status choice

Abstract: A model of employment status (self-employed vs. wage-or-salary employed) choice based on psychological, sociological and cognitive variables resolves the traditional shortcomings of occupational tr...

Bilingual lexical processing: Exploring the cognate/non-cognate distinction

Abstract: Three experiments examine whether the differential sensitivity to priming found for cognate and non-cognate translations in the masked primed lexical decision task is also apparent in other tasks. Experiments 1 and 3 employed tasks which specifically require the use of lexical information (i.e. a semantic categoxisation task and a cued translation task) and both produced results complementary to those found for lexical decision. The second experiment used a repetition blindness task which does not include a linpistic component. Although it has been argued that the repetition blindness and masked priming tasks tap a similar process (Kanwisher, 1987). the repetition blindness task did not show a cognate effect. This was taken to suggest that it taps a level different from that tapped in the masked priming task.

Reversal of pathology in murine mucopolysaccharidosis type VII by somatic cell gene transfer.

Abstract: AN inherited deficiency of β-glucuronidase in humans1, mice2 and dogs3 causes mucopolysaccharidosis VII (Sly syndrome), a progressive degenerative disease that reduces lifespan (to an average of 5 months in mice2) and results from lysosomal storage of undegraded glycosaminoglycans in the spleen, liver, kidney, cornea, brain and skeletal system1–4. Bone marrow transplantation in mutant mice provides a source of normal enzyme (‘cross-correction’5), which substantially improves the clinical condition and extends the average lifespan to 18 months6. Gene therapy by transfer of a β-glucuronidase gene into mutant haematopoietic stem cells is an alternative approach7,8, but it is not known whether the low expression of vector-transferred genes in vivo9,10 would be sufficiently effective. Here we show that retroviral vector-mediated transfer of the gene to mutant stem cells results in long-term expression of low levels of β-glucuronidase which partially corrects the disease by reducing lysosomal storage in liver and spleen.

Glucocorticoids promote development of the osteoblast phenotype by selectively modulating expression of cell growth and differentiation associated genes.

Abstract: To understand the mechanisms by which glucocorticoids promote differentiation of fetal rat calvaria derived osteoblasts to produce bone-like mineralized nodules in vitro, a panel of osteoblast growth and differentiation related genes that characterize development of the osteoblast phenotype has been quantitated in glucocorticoid-treated cultures. We compared the mRNA levels of osteoblast expressed genes in control cultures of subcultivated cells where nodule formation is diminished, to cells continuously (35 days) exposed to 10(-7) M dexamethasone, a synthetic glucocorticoid, which promotes nodule formation to levels usually the extent observed in primary cultures. Tritiated thymidine labelling revealed a selective inhibition of internodule cell proliferation and promotion of proliferation and differentiation of cells forming bone nodules. Fibronectin, osteopontin, and c-fos expression were increased in the nodule forming period. Alkaline phosphatase and type I collagen expression were initially inhibited in proliferating cells, then increased after nodule formation to support further growth and mineralization of the nodule. Expression of osteocalcin was 1,000-fold elevated in glucocorticoid-differentiated cultures in relation to nodule formation. Collagenase gene expression was also greater than controls (fivefold) with the highest levels observed in mature cultures (day 35). At this time, a rise in collagen and TGF beta was also observed suggesting turnover of the matrix. Short term (48 h) effects of glucocorticoid on histone H4 (reflecting cell proliferation), alkaline phosphatase, osteopontin, and osteocalcin mRNA levels reveal both up or down regulation as a function of the developmental stage of the osteoblast phenotype. A comparison of transcriptional levels of these genes by nuclear run-on assays to mRNA levels indicates that glucocorticoids exert both transcriptional and post-transcriptional effects. Further, the presence of glucocorticoids enhances the vitamin D3 effect on gene expression. Those genes which are upregulated by 1,25(OH)2D3 are transcribed at an increased rate by dexamethasone, while those genes which are inhibited by vitamin D3 remain inhibited in the presence of dexamethasone and D3. We propose that the glucocorticoids promote changes in gene expression involved in cell-cell and cell-extracellular matrix signaling mechanisms that support the growth and differentiation of cells capable of osteoblast phenotype development and bone tissue-like organization, while inhibiting the growth of cells that cannot progress to the mature osteoblast phenotype in fetal rat calvarial cultures.

Clinical implications of jejunoileal diverticular disease.

Abstract: Congenital and acquired diverticula of the jejunum and ileum in the adult are unusual and occur in approximately 1 percent to 2 percent of the population. They are pulsion diverticula thought to be the result of intestinal dyskinesia. These lesions can produce a significant diagnostic and therapeutic dilemma. They are multiple in the jejunum and solitary distally and are characteristically found in 60- or 70-year-old males. The diagnosis may be confirmed with contrast studies of the small intestine, arteriography, or nuclear scan. Consider these disorders in patients with 1) unexplained gastrointestinal bleeding, 2) unexplained intestinal obstruction, 3) an unexpected cause of acute abdomen, 4) chronic abdominal pain, 5) anemia, or 6) malabsorption. Medical therapy is helpful in controlling diarrhea and anemia, while surgical therapy is reserved for hemorrhage, obstruction, perforation, or failure of medical management. Asymptomatic diverticula discovered on routine contrast studies need not be resected. At surgery, incidental diverticula should be removed when evidence of dilated, hypertrophied loops of small bowel with large diverticula is found. Intraoperative air distention will aid in diagnosis. Resection and primary anastomosis is the preferred treatment for non-Meckelian diverticula. Diverticulectomy is reserved for a Meckel's diverticulum without evidence of ulceration. An incidental Meckel's diverticulum should be removed in the presence of mesodiverticular bands or ectopic tissue. Removal of a Meckel's diverticulum is not advised in the patient with Crohn's disease but may be performed in the patient undergoing restorative proctocolectomy for ulcerative colitis.

A prospective evaluation of distal margins in carcinoma of the rectum.

Abstract: The controversy regarding the ideal distal margin after a "curative" anterior resection is currently unresolved. To clarify this issue, a prospective study was undertaken. Two hundred and forty-three patients who underwent "curative" anterior resection were included in this study. Patients were divided into 1 centimeter groups based upon the length of the distal margin (from 0.0 to 8.0 centimeters), and recurrence, local and distant, and survival were analyzed. There was no significant difference in local or distant recurrence or survival when each centimeter interval was studied to 1 centimeter. Patients with a distal margin of less than 0.8 centimeter (group 1) had more frequent anastomotic recurrences (30 percent) when compared with patients (group 2) with a distal margin greater than 0.8 centimeter (10.5 percent; p = 0.01). Both groups were well matched for age, gender, tumor size, length of proximal margin, number of positive lymph nodes, histologic factors, grade of differentiation, Dukes' classification, type of operation, preoperative and postoperative radiotherapy, follow-up evaluation and surgeon. Both groups had a similar pelvic area recurrence (5.0 versus 8.7 percent, p = NS) and distance recurrence rates (10.0 versus 14.2 percent, p = NS). The five year survival rate was adversely affected by a distal margin of less than 0.8 centimeter (49.3 percent in group 1 and 67.5 percent in group 2; p = 0.01). The data suggest that a distal margin of 1 centimeter in the pathologic specimen is adequate distal clearance for most carcinomas of the rectum.

Comparison of Tzanck smear, viral culture, and DNA diagnostic methods in detection of herpes simplex and varicella-zoster infection.

Abstract: Objective. —To compare Tzanck smears, viral cultures, and DNA diagnostic methods using the polymerase chain reaction (PCR) in detection of herpes simplex virus (HSV) or varicella-zoster virus (VZV) infection in clinically suspected cases. Design. —A 12-month trial comparing PCR with viral cultures and Tzanck smears in patients with clinically suspected HSV or VZV infection. Setting. —Both ambulatory and hospitalized patients were recruited from a tertiary referral center and the Miami (Fla) Veterans Affairs Medical Center. Patients. —Convenience samples of patients clinically suspected to have HSV (n=48) or VZV (n=35). To be included in the final analysis patients needed to have a positive Tzanck smear, viral culture, or PCR result. Patients who were clinically suspected to have HSV but had VZV by viral culture or PCR were analyzed in the VZV group. Similarly, patients who were clinically suspected to have VZV, but had HSV by viral culture or PCR were analyzed in the HSV group. Seventy-seven patients were available for final analysis: HSV (n=30), VZV (n=32), and 15 control cases who did not have evidence of viral infection. Results. —For HSV, PCR detected HSV DNA sequences in 73% of stained smears and 83% of unstained smears. For VZV infection, VZV DNA sequences were detected in 88% of stained smears and 97% of unstained smears. Viral DNA sequences were not detected in the 15 control cases. Viral cultures were positive in 83% and 44% of HSV and VZV cases, respectively. The Tzanck smear was positive in 60% and 75% of HSV and VZV cases, respectively. Conclusions. —PCR is a reliable method for detecting HSV and VZV DNA sequences from single stained and unstained Tzanck smears. It is clearly superior to viral culture in identifying VZV infection and is equivalent to conventional culture techniques in identifying cases of HSV. ( JAMA . 1992;268:2541-2544)

Idiosyncratic Milieus of Entrepreneurial Research: The Need for Comprehensive Theories

Abstract: Considers one approach to the selection and adoption of new research tools and theories for topics in entrepreneurship which have proved difficult to study. Eight topics are identified as challenging to study because the person or event is difficult to find. Included in these topics are consistently entrepreneurial firms, habitual entrepreneurs, and emergence of new industries. The difficulty in finding these events or people is a result of their obscurity. This obscurity can be explained through two factors: event history of the entrepreneurial action and event privacy. An examination of other fields of study which must analyze obscure events is used to identify methods that may be useful in the study of entrepreneurship. Focus is on the field of epidemiology, but it is suggested that the fields of criminology, history, archeology, and paleontology might also be helpful. There are two types of ideas that can be adopted from these other fields: theories and methods. The adoption process can be direct, or it can be metaphorical; this analysis supports the metaphorical adoption of ideas. Five lessons from these other fields are presented: (1) need to have hypotheses waiting to be tested; (2) need to become comfortable using models and homomorphs; (3) need to have common measures; (4) need to build competing theories; and (5) need for comprehensiveness. Using the approach identified, the study of entrepreneurship can move toward theory building. (SRD)

Cellular localization and characterization of Glut 3 glucose transporter isoform in human brain.

Abstract: In the present study we examined the expression and localization of Glut 3 in human brain using peptide-specific antisera. Glut 3 was expressed at 2-3 times higher levels in cerebral cortex from adult (n = 6) compared to that from neonatal infants (n = 4; P less than 0.05). However, similar levels of immunoreactive Glut 3 were present in cerebellum from adults (n = 6) and newborns (n = 4). Cellular localization of Glut 3 in adult (n = 5) and neonatal (n = 5) infant brains was undertaken by immunohistochemical analysis. Glut 3 was visible in the adult neuropil of the cerebral cortex; in certain cellular processes within the deeper cortical layers; in intravascular white cells, including monocytes, lymphocytes and granulocytes; and in microvascular endothelial cells. Neither the premature nor the mature newborn cerebral cortex exhibited Glut 3 labeling in the neuropil or microvasculature. In the cerebellum, given the stratified nature of the cellular arrangement, Glut 3 was more clearly and definitively noted in the cellular processes at all stages of development. Double labeling studies using neuronal (neurofilament) and astrocytic (glial fibrillary acidic protein) markers indicated that Glut 3 was primarily expressed in neurons. We conclude that Glut 3 is localized in many cellular components, including white blood cells in human brain. The prominent localization of Glut 3 to mature neuronal processes suggests an essential role for this transporter in regulating fuel requirements for dendritic and axonal traffic, thereby mediating neurotransmission. Further study is required to address the possibility that another as yet undefined glucose transporter isoform is expressed in other cell-specific regions of the brain.

Hypercarbia during carbon dioxide pneumoperitoneum.

Abstract: Patients with cardiopulmonary insufficiency undergoing laparoscopic surgery with carbon dioxide (CO2) pneumoperitoneum may retain CO2 resulting in clinically significant respiratory acidosis. A canine model of pulmonary emphysema induced by papain inhalation was utilized to evaluate the respiratory effects of both CO2 and helium pneumoperitoneum. Prior to papain inhalation and 5 and 8 weeks after initial treatment under general anesthesia, mechanical ventilation was adjusted to maintain the end-tidal CO2 (ETCO2) at 40 mm Hg during baseline and pneumoperitoneum physiologic monitoring periods. Utilizing an analysis of variance, hemodynamic and respiratory physiologic parameters were compared. In this canine model, all dogs demonstrated consistent hypercarbia during CO2 pneumoperitoneum prior to papain treatments, but CO2 retention was significantly increased in the emphysematous state. The occurrence of hypercarbia during CO2 pneumoperitoneum may be underestimated by ETCO2 monitoring as was revealed by an increased PaCO2 (arterial carbon dioxide pressure)-ETCO2 gradient with an increasing time interval between papain exposure and period of physiologic monitoring. Irrespective of the pulmonary condition of the dog, helium pneumoperitoneum did not produce any hypercarbic or acidic changes when compared with the concomitant baseline period of dogs prior to the induction of pneumoperitoneum, thus suggesting that helium pneumoperitoneum may be a reasonable alternative in patients at risk for CO2 retention.

Maternal confidence, knowledge, and quality of mother‐toddler interactions: A preliminary study

Abstract: The purpose of this study was to examine the relationships among maternal confidence, knowledge of child development, and quality of mother-toddler interactions using self-efficacy (Bandura, 1977, 1989) as the theoretical framework. Using the Toddler Care Questionnaire, 50 mothers of toddlers were asked to estimate their confidence in their ability to parent their toddlers. Mothers also completed the Knowledge of Infant Development Questionnaire and were videotaped in their homes during a structured interaction with their toddlers. Maternal confidence was positively correlated with maternal knowledge of child development and parenting. The relationships among mother's knowledge of child development, maternal confidence, and quality of mother-toddler interactions were examined by a 2 × 3 analysis of variance with quality of interactions as the dependent variable. There were no significant main effects for maternal knowledge or confidence on quality of mother-toddler interactions, but there was a significant interaction effect. That is, the combined effects of maternal knowledge and confidence were related to quality of mother-toddler interactions. These results may explain previous inconsistencies in the literature regarding the significance of maternal confidence for mother-child interactions and are congruent with self-efficacy theory. Implications for interventions are discussed.

The mammalian glucose transporters.

Abstract: We have described the properties of glucose transporters expressed in several mammalian tissues and have summarized some of the adaptations that take place involving these molecules in various normal and abnormal states. With the exception of a few cell types, such as adipocytes and skeletal muscle, glucose transport is not a rate-limiting step in cellular glucose metabolism, and other substrates may be equally important for cellular metabolism. Nevertheless, an understanding of the mechanisms behind the regulation of glucose transport in individual tissues may facilitate an understanding of in vivo glucose utilization and clearance processes as they relate to normal and disease states. Although adult studies provide an impetus toward a mechanistic approach in preventing and treating various disease states involving derangements in glucose homeostasis, there remains a need for similar studies in the fetus and newborn. These developmental studies should help unravel the fetal/neonatal responses to normal and abnormal hormonal and substrate milieu.

Functional analysis of the rat insulin-like growth factor I gene and identification of an IGF-I gene promoter.

Abstract: Insulin-like growth factor I (IGF-I) mediates many of the systemic growth-promoting effects of growth hormone and also functions as a locally acting growth stimulator. In mammals, IGF-I ge...