Biomedical subjects

D Schneider

Publications and source records attributed to D Schneider.

At least 73 records · Page 4Linked to original sources

PubMed2001

Cortical representation of the vestibular system as evidenced by brain electrical activity mapping of vestibular late evoked potentials.

We examined the space and temporal distributions of the rotatory evoked brain electrical activity patterns (brain electrical activity mapping of vestibular evoked potentials [VestEP]) in humans. We performed a longitudinal scalp line analysis, transversal line analysis, and clockwise/counterclockwise rotation analysis of the VestEP principal components in 75 healthy persons aged 22 to 30 years (mean: 25.8). We found that the shortest VestEP latencies and the highest amplitudes were registered in a relatively distinct cortical area that is covered by the transversal electrode line T3-C3-Cz-C4-T4, in accordance with the 10/20 international electrode scheme. This area corresponds to the posterior part of the frontal lobe (Brodmann's area 4, the primary motor field of the isocortex) and the anterior parts of the cerebral parietal lobe (the gyrus postcentralis, which corresponds to the primary somatosensory fields, Brodmann's areas 1, 2, and 3). In this article, we discuss a method of investigation that exhibits the VestEPs, and we review one normal case and three typical cases of pathologic VestEPs.

Adult↗

PubMed2001

Comparative immunohistochemical study of endometrioid and serous papillary carcinoma of endometrium.

OBJECTIVE: The aim of this study was to determine whether immunohistochemical analysis of molecular parameters can provide an alternative method for classification of endometrial cancer cases according to their aggressiveness. METHODS: Sixty-four cases of endometrial carcinoma were assigned to three groups: group I--28 cases of endometrioid well and moderately differentiated (G1-G2) carcinoma; group II--14 cases of endometrioid poorly differentiated (G3) carcinoma; group III--22 cases of serous papillary endometrial cancer. Immunohistochemistry was used to determine the existence of estrogen receptors (ER), progesterone receptors (PR), and the expression of bcl-2, p53, HER-2/neu and Ki-67. RESULTS: There was a significant difference in the immunohistochemical profile of the studied molecular parameters comparing the three study groups. The endometrioid G1-G2 cases (group I) were characterized by increased immunoreactivity for ER and PR (85.7% and 78.6%, respectively), increased immunoreactivity for bcl-2 (42.8%) and low expression of p53 (14.3%) and HER-2/neu (14.3%). In contrast to group I cases, the serous papillary endometrial cancer cases (group III) were characterized by immunonegativity for ER, PR and bcl-2 and high immunoreactivity for p53 (81.8%) and HER-2/neu (45.4%). The endometrioid G3 cases (group II) demonstrated an intermediate immunoprofile, characterized by immunonegativity for ER, PR and HER-2/neu, low immunoreactivity for bcl-2 (7.1%) and high expression of p53 (57.1%). The expression of Ki-67 did not differ significantly comparing the different cases of endometrial cancer. CONCLUSION: This study provides evidence that the immunohistochemical analysis of endometrial carcinoma differentiates between different grades and histological types, thus being useful in the distinction of high risk cases.

Aged↗

PubMed2001

Clinical and molecular comparison between borderline serous ovarian tumors and advanced serous papillary ovarian carcinomas.

The aim of this study was to characterize the clinical and molecular markers of borderline serous ovarian tumors (BSOT), and to study their expression in the progression from benign lesions to advanced serous papillary ovarian carcinomas (SPOC). The clinical records of 20 patients with BSOT and 22 patients with SPOC were reviewed. Specimens from all these cases and from six benign ovarian serous cystadenomas were evaluated for expression of estrogen receptors (ER), progesterone receptors (PR), p53. HER-2/neu and Ki-67 by immunohistochemical techniques. The mean patient age and the age at menarche differed significantly between the compared groups of BSOT and SPOC (p=0.0006 and p=0.0014, respectively). No difference was observed comparing the other clinical parameters. The immunohistochemical analysis demonstrated a significant increase in the expression of ER (100% vs 72.7%), and a significant decrease in the immunoreactivity for p53 (0% vs 45.4%) and Ki-67 (2% vs 26.8%) in cases of BSOT compared with those of SPOC (p=0.007, p=0.0003 and p=0.012, respectively). No significant difference was demonstrated comparing the expression of PR and HER-2/neu. The immunostaining of benign ovarian serous cystadenoma specimens did not differ significantly from immunoreactivity observed in cases of BSOT. According to immunohistochemical analysis, BSOT had much more in common with benign serous tumors than with SPOC. The main difference between BSOT and SPOC was regarding the overexpression of p53 and Ki-67.

Adult↗

PubMed2000

Interaction of genetic and environmental programming of the leptin system and of obesity disposition.

Possible adverse interactions between an usually inconspicuous genetic trait and early environmental factors favoring the development of obesity were investigated in rats heterozygous for the leptin receptor defect "fatty" (fa). Pups were exposed to early postnatal overfeeding by reducing litter size from normally 10-12 to only 4. Rearing +/+ and +/fa pups from day 3 to 21 in small litters increased fat-free dry mass and body fat, but only in the latter did a significant interaction with genotype occur. Pronounced differences in the responsiveness of +/+ and +/fa pups to "prophylactic" leptin treatment (from day 1 to 21) were observed, with +/fa females from small litters being nearly as fat and unresponsive as previously reported for normally reared fa/fa pups. Clear heterozygous differences in total hypothalamic leptin binding, but no litter size effect, paralleling the differences in leptin responsiveness, were observed. By early postnatal overfeeding an usually inconspicuous genetic trait may thus become etiologic for the development of obesity via physiological changes other than the decreased leptin binding characterizing the genetic defect.

Adipose Tissue↗

PubMed2000

Malaria parasite development in a Drosophila model.

Malaria is a devastating public health menace, killing over one million people every year and infecting about half a billion. Here it is shown that the protozoan Plasmodium gallinaceum, a close relative of the human malaria parasite Plasmodium falciparum, can develop in the fruit fly Drosophila melanogaster. Plasmodium gallinaceum ookinetes injected into the fly developed into sporozoites infectious to the vertebrate host with similar kinetics as seen in the mosquito host Aedes aegypti. In the fly, a component of the insect's innate immune system, the macrophage, can destroy Plasmodia. These experiments suggest that Drosophila can be used as a surrogate mosquito for defining the genetic pathways involved in both vector competence and part of the parasite sexual cycle.

Aedes↗

PubMed2000

Interactions between the cellular and humoral immune responses in Drosophila.

Drosophila has highly efficient defenses against infection. These include both cellular immune responses, such as the phagocytosis of invading microorganisms, and humoral immune responses, such as the secretion of antimicrobial peptides into the hemolymph [1] [2]. These defense systems are thought to interact, but the nature and extent of these interactions is not known. Here we describe a method for inhibiting phagocytosis in Drosophila blood cells (hemocytes) by injecting polystyrene beads into the body cavity. This treatment does not in itself make a fly susceptible to Escherichia coli infection. However, when performed on flies carrying the mutation immune deficiency (imd), which affects the humoral immune response [3], the treatment results in a striking decrease in resistance to infection. We therefore carried out a sensitized genetic screen to identify immunocompromised mutants by co-injecting beads and E. coli. From this screen, we identified a new gene we have named red shirt and identified the caspase Dredd as a regulator of the Drosophila immune response. The observation that mutants with defects in the humoral immune response are further immunocompromised by blocking phagocytosis, and thus inhibiting the cellular immune response, shows that the Drosophila cellular and humoral immune responses act in concert to fight infection.

Animals↗

PubMed2000

Sequence of the two operons encoding the four core subunits of the cytochrome b(6)f complex from the thermophilic Cyanobacterium synechococcus elongatus.

The genes encoding cytochrome f (petA), cytochrome b(6) (petB), the Rieske FeS-protein (petC), and subunit IV (petD) of the cytochrome b(6)f complex from the thermophilic cyanobacterium Synechococcus elongatus were cloned and sequenced. Similar to other cyanobacteria, the structural genes are arranged in two short, single-copy operons, petC/petA and petB/petD, respectively. In addition, five open reading frames with homology to known orfs from the cyanobacterium Synechocystis PCC 6803 were identified in the immediate vicinity of these two operons.

Cloning, Molecular↗

PubMed2000

A broad-host-range plasmid for isolating mobile genetic elements in gram-negative bacteria.

Plasmid pGBG1 was constructed to isolate mobile genetic elements in a wide variety of gram-negative bacteria. The mutation target, carried on a broad-host-range vector, allows positive selection for tetracycline resistance. In tests using several gram-negative bacteria we could detect transposition events of either insertion sequences or transposons. A new insertion sequence (IS) element was identified in Ralstonia eutropha.

Agrobacterium tumefaciens↗

PubMed2000

[Ultraviolet exposure in childhood and in adulthood: which life period modifies the risk of melanoma more substantially?].

The paper is devoted to the analysis of the relationship between the frequency of sunburns in childhood and adulthood, respectively, and the occurrence of malignant melanoma of the skin. The analysis is based on case-control data of 603 melanoma cases and 627 population controls from 11 participating centers in seven European countries. The results confirm the increase in melanoma risk for an increasing number of sunburns during childhood and adulthood in the same magnitude of risk elevation. The maximum OR for the highest exposure category of more than five sunburns was during the childhood 2.0 (95%-CI: 1.2-3.5) and during the adulthood 2.1 (95%-CI: 1.4-3.3), respectively. The analysis of the joint effects of sunburns during child- and adulthood on melanoma development corroborated these findings. In this joint analysis an OR of 2.1 (95%-CI: 1.3-3.5) quantifies the melanoma risk of those with three or more sunburns during child- and adulthood, respectively, compared to those without any sunburns during these periods. The study does therefore provide no supporting evidence for the presence of "critical period" during childhood in which a higher melanoma risk due to sunburns has been suggested by other studies.

Adolescent↗

PubMed2000

Duplicated gene clusters suggest an interplay of glycogen and trehalose metabolism during sequential stages of aerial mycelium development in Streptomyces coelicolor A3(2).

DNA sequencing and operon disruption experiments indicate that the genes glgBI and glgBII, which code for the two developmentally specific glycogen branching enzymes of Streptomyces coelicolor A3(2) each form part of larger duplicated operons consisting of at least four genes in the order pep1-treS-pep2-glgB. The sequences of the TreS proteins are 73% identical (93% similar) to that of an enzyme that converts maltose into trehalose in Pinmelobacter, a distantly related actinomycete; and the Pep1 proteins show relatedness to the alpha-amylase superfamily. Disruptions of each operon have spatially specific effects on the nature of glycogen deposits, as assessed by electron microscopy. Upstream of the glgBI operon, and diverging from it, is a gene (glgP) that encodes a protein resembling glycogen phosphorylase from Thermatoga maritima and a homologue in Mycobacterium tuberculosis. These three proteins form a distinctive subgroup compared with glycogen phosphorylases from most other bacteria, which more closely resemble the enzymes from eukaryotes. Diverging from the glgBII operon, and separated from the pep1 gene by two very small ORFs, is a gene (glgX) encoding a probable glycogen debranching enzyme. It is suggested that most of these gene products participate in the developmentally modulated interconversion of immobile, inert glycogen reservoirs, and diffusible forms of carbon, both metabolically active (e.g. glucose-1-phosphate generated by glycogen phosphorylase) and metabolically inert but physiologically significant (trehalose).

Amino Acid Sequence↗

PubMed2000

Phase III, randomized, double-blind study of clarithromycin extended-release and immediate-release formulations in the treatment of patients with acute exacerbation of chronic bronchitis.

BACKGROUND: Clarithromycin has an established efficacy and safety profile in the treatment of respiratory tract infections. OBJECTIVE: The purpose of this study was to compare the clinical and bacteriologic efficacy and tolerability of clarithromycin extended-release and immediate-release formulations in patients with acute exacerbation of chronic bronchitis (AECB). METHODS: In a phase III, randomized, double-blind, parallel-group, multicenter study. patients aged > or =12 years with signs and symptoms of AECB and a productive cough with purulent sputum received treatment with extended-release (two 500-mg tablets once daily) or immediate-release (one 500-mg tablet twice daily) clarithromycin for 7 days. Assessments were performed before treatment, within 48 hours after treatment, and at the test-of-cure visit (study days 19-21). Patients who took > or =1 dose of study drug were included in the safety analysis. RESULTS: Of 620 patients randomized and treated, 182 were clinically and bacteriologically assessable (100 in the extended-release group and 82 in the immediate-release group). Treatment groups were well matched with respect to demographic characteristics and medical and social history. At the test-of-cure visit, 83% (83/100) of patients in the extended-release and 82% (67/82) of patients in the immediate-release group achieved clinical cure; 86% (85/99) and 85% (70/82), respectively, demonstrated bacteriologic cure. Overall pathogen eradication rates were 86% (100/116) in the extended-release group and 88% (86/98) in the immediate-release group. The most frequently reported adverse events were diarrhea (6% in extended-release group vs 4% in immediate-release group; no significant difference), taste alterations (4% in each group), and nausea (3% in each group); no clinically meaningful changes in laboratory values or vital signs, as assessed by the investigator, were observed. CONCLUSION: This study suggests that clarithromycin extended-release and immediate-release formulations have equivalent clinical and bacteriologic efficacy and tolerability in patients with AECB.

Acute Disease↗

PubMed2000

International trends in adolescent nutrition.

This paper addresses international trends in adolescent nutrition by reviewing the literature from English-language indexed journals and online sources from around the world. Information is presented by geographic region and by nation within region. The literature shows that malnutrition remains a significant problem for adolescents, worldwide, but that the types of nutritional problems impacting this group have changed significantly over the past two decades. While undernutrition and wasting are reported, these conditions, as well as growth stunting, seem to be on the decline. In developed countries, social pressures to achieve a distorted body image are creating a malnutrition of affluence among some groups of adolescents. There appears to be an increasing prevalence of obesity among adolescents worldwide, explained by widespread nutrition transitions to lipid-rich diets and a decrease in physical activity, especially among urban adolescents. These trends are of international importance as they imply the world will see a shift towards longer life spans for this adolescent cohort, with a concomitant increase in the prevalence of chronic diseases as it ages. The epidemiologic transition that will result may be a mixed blessing. It is likely to produce a larger and healthier international workforce, but it also has the potential of becoming a serious burden as demands for health care and support services for those with chronic diseases increase. To prevent inordinate health care demands on the international economy in the future, dietary recommendations with nutritional education programs that are culturally appropriate need to become national priorities.

Adolescent↗

PubMed2000

Using Drosophila as a model insect.

The fruit fly Drosophila melanogaster has become such a popular model organism for studying human disease that it is often described as a little person with wings. This view has been strengthened with the sequencing of the Drosophila genome and the discovery that 60% of human disease genes have homologues in the fruit fly. In this review, I discuss the approach of using Drosophila not only as a model for metazoans in general but as a model insect in particular. Specifically, I discuss recent work on the use of Drosophila to study the transmission of disease by insect vectors and to investigate insecticide function and development.

Animals↗

PubMed2000

Effect of daily iron supplementation on iron status, cell-mediated immunity, and incidence of infections in 6-36 month old Togolese children.

OBJECTIVE: To assess the impact of a daily oral iron supplementation on hematological status, cell-mediated immunity and susceptibility to infections in children living in an environment where iron deficiency, malaria and other infections are frequent. DESIGN: Randomized, double-blind iron supplementation including a placebo group. SETTING: A village in Togo, West Africa. SUBJECTS: Of the 229 6-36-month-old children of both sexes recruited, 197 with hemoglobin concentration >/=80 g/l were included and 163 completed the study. INTERVENTION: Children received daily a placebo (n=79) or a dose of 2-3 mg of elemental iron per kg of body weight (n=84) for 3 months. Hematological, nutritional and immune status were assessed at the beginning and at the end of the supplementation period, and 6 months later. Morbidity was recorded throughout the study. RESULTS: Iron supplementation had a significant and positive effect on iron status of children and no impact on the incidence of infections, especially malaria. Its probable effect on immune status was masked by interference of infections and their treatment, which contributed to improve hematological and immune status in both groups. CONCLUSION: According to the negative consequences of anemia and iron deficiency on global child development, control of iron deficiency by oral iron supplementation in young children has to be conducted, associated with prophylaxis and treatment of malaria and repeated deworming. SPONSORSHIP: Program supported by IRD. European Journal of Clinical Nutrition (2000) 54, 29-35

Analysis of Variance↗

PubMed2000

Potential of rheopheresis for the treatment of acute ischemic stroke when initiated between 6 and 12 hours.

Improvement of hemorheology is one of the most important approaches in the treatment of acute ischemic stroke. We investigated the influence of extracorporal rheopheresis (ER) on cerebral blood flow in patients with acute ischemic stroke and evaluated its therapeutic effect. Thirty-three patients (rheopheresis group, 17; control group, 16; mean age 64 +/- 10 years) with acute ischemic stroke were included in our prospective randomized trial. The first treatment was started within 12 h after onset of symptoms, and treatment was repeated 3 times at an interval of 24 h. Hemorheological parameters were measured before and after each session. The cerebral blood flow was analyzed using 99mTc-ECD-SPECT. The functional and neurological outcomes were determined by follow-up investigations after 3 months. The hemorheological parameters were significantly different between the rheopheresis group (18% decrease of plasma viscosity, 55% decrease of red blood cell aggregation) and the control group (no decrease of both parameters). The single photon emission computed tomography (SPECT) analysis showed early reperfusion in 35% of the patients treated with rheopheresis and in 37% of the control group (NS). There were no differences in the neurological outcomes between the 2 groups. Extracorporal rheopheresis is practicable and safe. It rapidly and consistently improved the hemorheological parameters. Although this did not impact on cerebral perfusion or clinical outcome in patients with acute ischemic stroke in this report, we propose that ER deserves to be further evaluated by initiating the first treatment within 6 h post-insult.

Adolescent↗

PubMed2000

Orphanin FQ causes contractions via inhibiting purinergic pathway in the rat colon.

BACKGROUND & AIMS: We have previously shown that orphanin FQ (OFQ) preferentially stimulates muscle contraction in the rat colon. However, the mechanism of action of OFQ remains unclear. METHODS: We studied the effects of OFQ on muscle contractions and inhibitory junction potentials (IJPs) in rat colon. The site of action of OFQ was also investigated by in situ hybridization of OFQ receptors. RESULTS: OFQ (10(-10) to 10(-6) mol/L) caused circular muscle contractions that were blocked by tetrodotoxin (10(-7) mol/L), suggesting the contractions were nerve mediated. Suramin (a nonselective P(2)-purinoceptor antagonist; 10(-4) mol/L) and reactive blue 2 (a P(2Y)-purinoceptor antagonist; 3 x 10(-5) mol/L), but not pyridoxalphosphate-6-azophenyl-2',4' disulfonic acid (PPADS; a P(2X)-purinoceptor antagonist; 3 x 10(-5) mol/L), abolished OFQ-induced colonic contractions. Focal stimulation of interganglionic fiber tracts evoked biphasic IJPs in colonic circular muscle cells. Suramin and reactive blue 2 inhibited the peak amplitude of the IJP, whereas PPADS had no effect. Cumulative addition of OFQ (10(-10) to 10(-6 )mol/L) significantly inhibited the IJPs. In situ hybridization revealed that OFQ receptor messenger RNA was expressed in the colonic myenteric plexus but not in the smooth muscle cells, suggesting that the site of action of OFQ is neuronal. CONCLUSIONS: These results suggest that OFQ causes muscle contractions by inhibiting purinergic inhibitory motorneurons in the rat colon.

Animals↗

PubMed2000

Expression of the p53 gene and apoptosis in gestational trophoblastic disease.

In order to understand the involvement of the p53 tumour suppressor gene in the pathogenesis of gestational trophoblastic disease (GTD), we investigated its genetic status, protein expression and its role in apoptosis in samples of complete and partial hydatidiform mole as compared with those of normal placenta. Direct sequencing of polymerase chain reaction (PCR) products of the coding and non-coding regions of the p53 gene demonstrated no mutations in any of the studied samples. Immunohistochemical studies revealed increased expression of the p53 protein predominantly in the nuclei of villous cytotrophoblasts. This over-expression of p53 was found in all samples of complete mole, in 50 per cent of partial mole samples and in about 30 per cent of normal placenta cases, although no significant difference in the staining intensity and pattern was observed. An in situ detection of DNA nicking (TUNEL) staining, demonstrating apoptosis, was also detected predominantly in villous cytotrophoblasts and in stromal areas. The per centage of apoptotic cells in all studied samples, determined by flow cytometry, demonstrated a significant increase in apoptotic cells in samples of complete and partial hydatidiform mole compared with those of normal placenta (P< 0.0003 and P< 0.004, respectively). In conclusion, the current study may provide a possible explanation to the pathogenesis of GTD, probably associated with extensive p53-dependent apoptosis to modulate excessive trophoblastic proliferation.

Apoptosis↗

PubMed2000

Coenzyme Q10, vitamin E, and dihydrothioctic acid cooperatively prevent diene conjugation in isolated low-density lipoprotein.

Coenzyme Q (Q10) and alpha-tocopherol cooperatively delay the onset of diene conjugation in isolated human low density lipoprotein if supplied in water-soluble preparations to blood serum. Both copper ions and morpholino sydnonimine (in the presence of glucose; SIN-1-glucose) -driven diene conjugation is measurable as soon as both reduced Q10 and tocopherol are oxidized, where tocopherol oxidation starts after 80-90% consumption of reduced Q10. LDL-bound Q10 in turn can be rapidly reduced by dihydrolipoic acid (thioctic acid). This reaction is at least 10 times faster than reduction by ascorbic acid.

Antioxidants↗