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Biomedical subjects

E Dennis

Publications and source records attributed to E Dennis.

At least 19 recordsLinked to original sources
PubMed2006

Activation of peripheral 5-HT receptors attenuates colonic sensitivity to intraluminal distension.

Tegaserod is a 5-HT(4) receptor partial agonist approved for the treatment of irritable bowel syndrome in women with constipation and in both men and women with chronic constipation. The efficacy of tegaserod is based on the importance of 5-HT(4) receptors regulating intestinal peristalsis and secretion, and possibly visceral sensory pathways. Our aim was to investigate the effect of tegaserod on colorectal sensitivity using models of normal and exaggerated responsiveness to colorectal distension (CRD). The visceromotor responses (VMR) to CRD at graded pressures (0-60 mmHg) were measured by the number of reflex abdominal contractions. Acute colorectal hypersensitivity was induced by intracolonic infusion of dilute acetic acid. Chronic hypersensitivity was observed in rats following spontaneous resolution of trinitrobenzenesulfonic acid-induced colitis. Rats with normosensitive colons served as controls. Tegaserod (0.1-10 mg kg(-1)) caused dose-dependent reduction of the VMR to CRD in control rats and in those with colonic hypersensitivity. 5-HT(4) antagonists reversed the effects of tegaserod in rats with normosensitive colons, and partially inhibited effects in rats with colonic hypersensitivity. Central administration of tegaserod had no inhibitory effect. These results support the assumption that colonic hypersensitivity could be normalized by tegaserod acting, at least in part, through peripheral 5-HT(4) receptors.

Acetic Acid↗
PubMed2000

The cytotoxic plant protein, beta-purothionin, forms ion channels in lipid membranes.

Thionins are small cysteine-containing, amphipathic plant proteins found in seeds and vegetative tissues of a number of plant genera. Many of them have been shown to be toxic to microorganisms such as fungi, yeast, and bacteria and also to mammalian cells. It has been suggested that thionins are present in seeds to protect them, and the germinating seedling, from attack by phytopathogenic microorganisms, but the mechanism by which they kill cells remains unclear. Using electrophysiological measurements, we have shown that beta-purothionin from wheat flour can form cation-selective ion channels in artificial lipid bilayer membranes and in the plasmalemma of rat hippocampal neurons. We suggest that the generalized toxicity of thionins is due to their ability to generate ion channels in cell membranes, resulting in the dissipation of ion concentration gradients essential for the maintenance of cellular homeostasis.

Animals↗
PubMed1998

Ovule and embryo development, apomixis and fertilization.

Genetic analyses, particularly in Arabidopsis, have led to the identification of mutants that define different steps of ovule ontogeny, pollen stigma interaction, pollen tube growth, and fertilization. Isolation of the genes defined by these mutations promises to lead to a molecular understanding of these processes. Mutants have also been obtained in which processes that are normally triggered by fertilization, such as endosperm formation and initiation of seed development, occur without fertilization. These mutants may illuminate apomixis, a process of seed development without fertilization extant in many plants.

Arabidopsis↗
PubMed1998

Cloning and characterization of MS5 from Arabidopsis: a gene critical in male meiosis.

In this paper, we describe the cloning of the MS5 gene, a gene essential for male fertility in Arabidopsis. We previously defined the MS5 locus by characterizing an EMS-induced allele, ms5-1. We identified a new allele of MS5 (ms5-2) that was T-DNA-generated and used the T-DNA tag to clone the gene. Sequencing of mutant and wild-type alleles together with complementation of the ms5-1 mutant phenotype with a wild-type genomic clone confirmed the identity of the gene. Differences between the phenotypes of the two mutant alleles could be attributed to differences in mutant gene structure. The semi-dominant and dominant negative phenotypes of the ms5-2 mutant probably result from production of a truncated polypeptide. An unknown locus in Landsberg erecta can counteract the dominant negative phenotype of ms5-2. Mutations in MS5 cause the formation 'polyads'--tetrads with more than four pools of chromosomes after male meiosis. Similarities between the MS5 sequence and that of a number of proteins were found; two that may be significant were with a synaptonemal complex protein and with a regulatory subunit of a cyclin-dependent kinase. The MS5 gene is a member of a small gene family highly conserved amongst plant species.

Alleles↗
PubMed1997

Optical immunoassay test for group A beta-hemolytic streptococcal pharyngitis. An office-based, multicenter investigation.

OBJECTIVE: To compare the accuracy of an optical immunoassay (OIA) for the rapid diagnosis of group A streptococcal pharyngitis with blood agar plate (BAP) culture. DESIGN: Blinded comparison with criterion standard. SETTING: A total of 6 private pediatricians' offices, 3 in Connecticut and 3 in Chicago, III. PATIENTS: A total of 2113 consecutive patients with acute pharyngitis, 983 in Connecticut and 1130 in Chicago. MAIN OUTCOME MEASURES: The sensitivities and specificities of OIA and BAP culture (both performed and interpreted in the office) were determined using a research laboratory's interpretation of a combination of BAP culture and Todd-Hewitt broth (THB) culture of transport tube pledget as criterion standard. RESULTS: Among patients in Connecticut, the sensitivities of the OIA and BAP culture were 94% and 89%, respectively (P=.004), while the specificities were 96% and 99%, respectively (P=.001). Among patients in Chicago, the sensitivities of the OIA and BAP culture were 79% and 72%, respectively (P<.001), while the specificities were 89% and 99%, respectively (P<.001). In each of the 6 pediatricians' offices, the OIA was more sensitive than the BAP culture. Combining the data from Connecticut and Chicago, the overall sensitivities of the OIA and BAP culture were 84% and 78%, respectively (P<.001), while the specificities were 93% and 99%, respectively (P<.001). CONCLUSIONS: The results of this comprehensive office-based investigation suggest that with adequately trained personnel, negative OIA test results may not always need to be routinely confirmed with BAP cultures.

Acute Disease↗
PubMed1995

Ultrastructural and morphometric features of nodal and impulse-conducting cardiac myocytes of the bat Pipistrellus pipistrellus.

Cells of the impulse-generating and conducting tissues of the insect-eating bat Pipistrellus pipistrellus were studied and evaluated using ultrastructural morphometry. Sinoatrial node cells are smaller than working atrial cells and measure about 6.5 microm in diameter. Their mitochondira and myofibril content constitute 23% and 19% of cytoplasmic volume, respectively. Corresponding values for working atrial cells are 23% and 52%. Atrioventricular node cells are 4.2 microm in diameter and contain abundant glycogen in the cytoplasm. The fractional volume of mitochondria in about 24% while that of myofibrils is 7%. Cells of the bundle of His are larger (6-8 microm diameter) and contain more cellular organelles than do nodal cells. Their mitochondria and myofibril contents are 25% and 25%, respectively. Cells in the proximal part of the right bundle branch are slender with diameters averaging 3.4 microm. Mitochondrial content is 23% while myofibrils occupy 20% of the cytoplasmic volume of these cells. Distally located bundle branch cells measure 7-10 microm in diameter with mitochondria and myofibril volumes of 30% and 33%. Subendocardial cells in the ventricular free wall are large reaching 28 microm in diameter (cf. 14-18 microm in working ventricular cells) and have mitochondira and myofibril volume fractions of 32% and 29%, respectively (35% & 40% for working ventricular cells).

Animals↗
PubMed1992

An inservice on wheels.

In our hospital nurses were unsure about products to order for ostomy patients. To address nurses' concerns, a group of representatives from the Central Supply Department and Nursing Department as well as the clinical nurse specialist and patient care specialist was formed. The group developed an inservice on wheels entitled, "Send Me One of Everything" which was rotated throughout the hospital. This article describes the setup of the cart, methods used to update skills, and evaluation of the process. The inservice on wheels was an effective way to update the staff and decrease waste.

Enterostomy↗
PubMed1989

Isolation and molecular analysis of the maize P locus.

The maize P locus is involved in the synthesis of a red flavonoid pigment in the pericarp, cob and other floral tissues. The tissue-specific pattern of expression of certain P alleles suggests that P may be a complex locus, with more than one functional unit. The P-VV allele, which specifies variegated pericarp and variegated cob, however, shows that insertion and excision of the transposable element Ac affects both pericarp and cob expression as though cob and pericarp pigmentation are controlled by a single gene. Using Ac as a transposon tag, we have isolated 34 kb of genomic DNA from the P-VV and P-RR allele. The cloned DNA contains two 5.8 kb cross-hybridizing regions, in direct orientation relative to each other, separated by 6.6 kb of intervening DNA. A sequence motif of 250 bp is repeated at three locations within the cloned region: once within each of the 5.8 kb repeats, and once outside the 5.8 kb repeats. DNA fragments flanking the Ac element detect five transcripts in RNA from wild type (P-RR) that are absent from mutant (P-VV) tissues. To localize the transcribed sequences, DNA probes spanning the 34 kb of cloned DNA were used in Northern analysis of RNA from mutant and wild-type kernels. The results suggest the presence of a single transcriptional unit located primarily within the DNA between the 5.8 kb repeats. The five RNAs transcribed from this region may be formed by alternative splicing. The size of the P gene derived from the length of the transcribed region seems much smaller than the gene size estimated from Ac-induced P-VV mutations.

Alleles↗
PubMed1985

Transcription from a plant gene promoter in animal cells.

The promoter segment of a plant gene (maize alcohol dehydrogenase 1 (Adh 1)) has been fused to two bacterial reporter genes, Ecogpt (1) and neo (2), in pSV2-derived vectors and introduced into cultured mammalian cells by DNA transfection. The pAdh1-gpt plasmids transformed the recipient cells for resistance to mycophenolic acid plus xanthine (3) and the analogous pAdh1-neo plasmid transformed cells to G418 resistance (2). S1 analysis of transient transfections of CV1 cells with various derivatives of pAdh1-gpt confirmed that production of gpt mRNA is initiated at the Adh1 promoter at and near the same site used in transcription of the intact Adh1 gene in maize. Moreover, expression of the Adh1 promoter was increased 10-20 fold if the SV40 early region enhancer sequence was included in the same molecule.

Animals↗
PubMed1985

Swamp rice farming: possible effects on endemicity of schistosomiasis mansoni and haematobia in a population in Liberia.

To obtain a better understanding of the possible influence of swamp rice farming on the patterns of Schistosoma mansoni and Schistosoma haematobium infections, the populations of two communities in rural liberia were studied. In one village, Balama (population of 435), swamp rice farms were initiated six years before the survey; in the other nearby community, Gbarta (population of 216), swamp rice farms had not yet been initiated. The prevalence of S. mansoni infection in Balama was 87% vs. 9% in Gbarta (P less than 0.01). The geometric and arithmetic mean egg counts for all infected subjects in Balama were respectively 263 and 671/g feces. in Gbarta, the geometric and arithmetic mean egg counts were 150 and 129/g feces. S. haematobium eggs were detected in 42% of subjects in Balama vs. 11% in Gbarta (P less than 0.01). Hematuria correlated with the presence of S. haematobium eggs in urine. These data indicate that there is a significantly higher prevalence and intensity of schistosomiasis mansoni and haematobia in a community where swamp rice farming has been utilized for 6 years compared to a nearby village where this water irrigation and drainage practice has not yet been implemented.

Adult↗
PubMed1983

Studies on the epidemiology of schistosomiasis in Liberia: the prevalence and intensity of schistosomal infections in Bong County and the bionomics of the snail intermediate hosts.

Urine samples from 3548 individuals residing in six of the eight districts which comprise Bong County, Liberia, the project area of the Bong County Agricultural Development Project (BCADP), and fecal specimens from 3408 of these individuals were examined for schistosome ova. A total of 164 water sites, including rice paddies, were surveyed for schistosome vector snails and monthly changes in snail population density and infection rate were determined in selected water sites. Bulinus globosus was more widely distributed than Biomphalaria pfeifferi but the latter species showed a higher infection prevalence (12.3%) than the former one (10.3%). Snail population density and infection rate fluctuated with season, being higher in the dry season and lower during periods of heavy rainfall. Dessication and/or heat stress may have contributed to the contraction of snail population size at the end of the dry season. More water sites contained infected snails during December through February than at any other time of the year. In selected water sites examined at monthly intervals, mean snail density was higher in rice paddies than in other water contact sites but the latter showed a higher prevalence of infected snails than the former. The overall prevalence of Schistosoma mansoni (24.8%) was significantly higher than that of S. haematobium (22.7%) but the difference in prevalence rates of two species in school children was not statistically significant. The intensity of S. haematobium infection (13.2 means G) was significantly higher than that of S. mansoni (6.3 means G). Mixed infections in school children did not have a significant effect on egg output. The prevalence and intensity of S. haematobium showed a dramatic decline between the age groups 0-15 and 20-50 + years old; the differences between these age groups in S. mansoni infection were unremarkable. In Zota, Jorquelle and Kokoya Districts, prevalence rates of S. haematobium were higher than those of S. mansoni; the reverse was observed in Suakoko and Panta-Kpai Districts but relative prevalence rates varied according to specific locality in each district. A south to north stratification of schistosomal infection prevalence was observed similar to the west to east gradient reported by Saladin et al. (1980). New rice paddies developed during the three year operational period of the BCADP contained little or no vector snails and schistosomal infections in farm families of these paddies reflected the characteristic of the disease in corresponding localities.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1983

The impact of schistosomiasis among rural populations in Liberia.

Human infection with Schistosoma haematobium and/or Schistosoma mansoni is known to be widespread in central Liberia, but no information is available about its clinical manifestations or its significance for public health. Details of a cross-sectional morbidity study are reported. A sample from hospital out-patients and samples from 3 villages situated in areas with different transmission patterns (lack of transmission, transmission of only S. haematobium and transmission of both S. haematobium and S. mansoni) were examined. All 184 individuals were examined by standardized case history, clinical and parasitological investigations, including a skin snip for onchocerciasis and a count of schistosomal and other intestinal worm eggs from stool and urine. A complete blood count, urine analysis, urine cultures, hepatitis-B surface antigen determination and abdominal X-rays were also carried out. Schistosomal egg counts ranged from 1 to 6200/10 ml urine for S. haematobium and from 1 to 228/g stool for S. mansoni. Difficulties for the definition of accurate morbidity indices are discussed. Except for haematuria and dysuria, the overall morbidity in the study area was not striking, neither for S. haematobium nor for S. mansoni infection. No cumulative pathology was observed in patients with mixed infection. The frequency of hypertension, hepato- and splenomegaly, ascites and bacteriuria was low and no relationship to schistosomiasis could be established. Bladder calcifications were found in 10% of people living in an area of transmission of S. haematobium. Although the intensity of infection is low for both S. haematobium and S. mansoni, long-term follow-up studies are essential for a more accurate assessment of the public health importance of these parasites.

Adolescent↗
PubMed1983

A pilot control trial of schistosomiasis in central Liberia by mass chemotherapy of target populations, combined with focal application of molluscicide.

In an area of high transmission of Schistosoma haematobium and S. mansoni in Central Liberia, populations of five villages and intermediate host snails were surveyed for two years. In three of these villages focal application of molluscicide (niclosamide) in the main transmission sites was combined with mass chemotherapy of a target population representing 76 to 90% of the contamination index. In the two other villages, which served as control, the prevalence indexes remained stable or increased a little during the period of this study. A three dose metrifonate mass treatment was applied in one village with only S. haematobium infections. The compliance was very poor for the second and third dose but the quantity of eggs eliminated by the whole population present before and after mass treatment was reduced by 50%. No snails were found after molluscicide applications but as the incidence remained unchanged it is suspected that inhabitants have been reinfected by going to their fields. Concurrent metrifonate and niridazole mass treatment in one dose was applied in another village with only S. haematobium infections. Molluscicide applications reduced the snail population by 80% but did not affect the transmission. Prevalence indexes were almost the same before and after this intervention. In the last village, praziquantel (40 mg/kg in 1 dose) was used because both S. haematobium and S. mansoni infections were present. Molluscicide applications reduced the snail population by 99% and 87% for Bulinus globosus and Biomphalaria pfeifferi, respectively. This intervention stopped the transmission of S. haematobium for at least one year and reduced the prevalence from 21% to 4.6%. On the contrary for S. mansoni infections, the incidence remained very high (50%) and the prevalence was unchanged after one year follow-up. This could be explained by lower efficacy of praziquantel against S. mansoni (cure rate: 53%) and of molluscicide application against B. pfeifferi, which are highly susceptible to S. mansoni (infection rate 44%). The importance of migration in these villages is emphasized. Prevalence indexes were largely influenced by the arrival of newcomers who played a more important role in the maintenance of transmission after target mass chemotherapy than the infected persons excluded from this treatment. The costs per capita protected were 3.33 US $ for metrifonate, 1.53 for metrifonate and niridazole combined and 1.67 US$ for praziquantel. These figures do not include costs for parasitological examinations.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1980

Preliminary epidemiological survey of schistosomiasis in central and southern Liberia.

Some basic epidemiological data on schistosomiasis in central and southern Liberia were collected. A study of snail density fluctuations was carried out in waterbodies bordering the road between Harbel and Gbarnga. Samples from schoolchildren living in ten selected villages were examined for Schistosoma spp. and other helminths. In the coastal region no snail hosts were found, the prevalence rates in schoolchildren were low and the infections were apparently imported. Inland, the intermediate host of Schistosoma haematobium Bulinus globosus was common and the prevalence of urinary schistosomiasis was high. Further inland, around Gbarnga, both Schistosma mansoni and S. haematobium were endemic. The seasonal patterns of patent cercarial infections in Bulinus globosus and Biomphalaria pfeifferi are described. Both snail densities and cercarial infection rates were markedly reduced by heavy rains. The results of the study may contribute to the planning of future integrated control strategy.

Adolescent↗