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Biomedical subjects

K Schneider

Publications and source records attributed to K Schneider.

At least 73 records · Page 4Linked to original sources
PubMed1999

Epidermal diseases in bottlenose dolphins: impacts of natural and anthropogenic factors.

Experimental studies have highlighted the potential influence of contaminants on marine mammal immune function and anthropogenic contaminants are commonly believed to influence the development of diseases observed in the wild. However, estimates of the impact of contaminants on wild populations are constrained by uncertainty over natural variation in disease patterns under different environmental conditions. We used photographic techniques to compare levels of epidermal disease in ten coastal populations of bottlenose dolphins (Tursiops truncatus) exposed to a wide range of natural and anthropogenic conditions. Epidermal lesions were common in all populations (affecting > 60% of individuals), but both the prevalence and severity of 15 lesion categories varied between populations. No relationships were found between epidermal disease and contaminant levels across the four populations for which toxicological data were available. In contrast, there were highly significant linear relationships with oceanographic variables. In particular, populations from areas of low water temperature and low salinity exhibited higher lesion prevalence and severity. Such conditions may impact on epidermal integrity or produce more general physiological stress, potentially making animals more vulnerable to natural infections or anthropogenic factors. These results show that variations in natural environmental factors must be accounted for when investigating the importance of anthropogenic impacts on disease in wild marine mammals.

Animals↗
PubMed1999

A novel set of hepatic mRNAs preferentially expressed during an acute inflammation in rat represents mostly intracellular proteins.

A cloning of hepatic cDNAs associated with the early phase of an acute, systemic inflammation was carried out by differential screening of arrayed cDNA clones from rat livers obtained at 4-8 h postchallenge with Freund's complete adjuvant. End sequencing of 174 selected clones provided three cDNA groups that coded for: (i) 23 known acute-phase proteins, (ii) 31 known proteins whose change in hepatic synthesis during an acute phase was so far unsuspected, and (iii) 36 novel proteins whose cDNAs were completely sequenced. For 16 proteins in the third group the hepatic mRNA could be detected and quantitated by Northern blot hybridization in Freund's adjuvant-challenged animals, and an extrahepatic expression in healthy animals was further investigated. Matching the open reading frames of the 36 novel proteins with general and specialized data libraries indicated the potential relationships of 16 of these proteins with known protein families/superfamilies and/or the presence of functional domains previously described in other proteins. Overall, our search for novel inflammation-associated proteins selected mostly known or as yet undescribed proteins with an intracellular or membrane location, which extends our knowledge of the proteins involved in the intracellular metabolism of hepatic cells during a systemic, acute-phase response. Finally, some of the cDNAs above allowed us to successfully identify hepatic mRNAs that are differentially expressed in acute vs chronic (polyarthritis) inflammatory conditions in rat.

Acute-Phase Proteins↗
PubMed1999

[Diagnosis and therapy of lymph node tuberculosis].

Due to an increase of lymph node tuberculosis and associated diagnostic problems the question for the easiest and most accurate diagnostic measures was asked. Furthermore, the success of surgical and pharmacologic treatment was evaluated. A total of 16 patients (nine females, seven males) treated at the medical outpatient clinic between 1977 and 1995 because of lymph node tuberculosis were evaluated retrospectively. Diagnosis had been established in all cases either by fine needle aspiration or surgical excision. The mean age was 31 years (range 17-68). In 10 patients cervical lymphomas were found. Other localisations were supraclavicular, inguinal, axillary and mediastinal. In 94% of the patients a fine needle aspiration was performed to ascertain diagnosis. Acid-fast bacilli were found in 36% and mycobacteria were cultured in 92%. Five patients (31%) had a surgical excision with acid-fast bacilli in two and positive cultures from all specimens. All patients had chemotherapy, in most cases started by a combination of three and followed by a combination of two drugs. According to our results a fine needle aspiration is justified as a first diagnostic step if lymph node tuberculosis is suspected. A positive result can be regarded as conclusive and spares surgical intervention. Since negative results do not exclude tuberculosis they justify surgical excision for final diagnosis.

Adolescent↗
PubMed1999

An integrated proteomic approach to studying glomerular nephrotoxicity.

A single dose of puromycin aminonucleoside (PAN) given parenterally to rats induces ultrastructural glomerular changes and a nephrotic syndrome similar in many respects to human minimal change nephropathy. The exact aetiologies of both the human and the experimental syndromes are unknown, and are probably multifactorial. However, among the observed consequences in humans and rats is increased plasma protein excretion in urine, beginning in the latter typically 3-6 days after PAN administration. In view of this, two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) has been used to profile urinary proteins during PAN-induced nephrotoxicity and subsequent recovery in the rat. In addition, urinary high performance liquid chromatography (HPLC) profiles and high resolution proton nuclear magnetic resonance (NMR) spectroscopy has been utilised to simultaneously detect toxin-induced changes in the relative concentrations of a number of metabolites. The proteomic approach, in conjunction with these other techniques, has the potential to provide significantly more mechanistic information than is provided readily by traditional clinical chemistry.

Animals↗
PubMed1999

PCR-based cloning and segregation analysis of functional gene homologues in Beta vulgaris.

To analyse genetic factors that potentially affect sugar quality and yield in Beta vulgaris, we designed primers based on 18 homologous ESTs and conserved regions of 32 heterologous ESTs encoding gene products that act in the Calvin cycle, the oxidative pentose phosphate cycle, photorespiration, synthesis, transport and degradation of sucrose, glycolysis, the citric acid cycle, nitrogen metabolism and osmoprotection. Data on the amplification of 54 gene homologues from B. vulgaris are presented. Among these are 35 homologues for which DNA sequence information from B. vulgaris is now available for the first time. For genetic mapping a PCR-based strategy using CAPS (cleaved amplified polymorphic sequence), DFLP (DNA fragment length polymorphism), SSCP (single-strand conformation polymorphism) and HD (heteroduplex) analysis was adopted. RFLP analysis was also used in some cases. The different techniques used for the detection of polymorphisms are evaluated with respect to their sensitivity and versatility. In all, 42 functional genes have been assigned to the nine linkage groups of sugar beet.

Alleles↗
PubMed1999

Feline calicivirus capsid protein expression and capsid assembly in cultured feline cells.

The capsid protein of feline calicivirus (FCV) was expressed by using plasmids containing cytomegalovirus, simian virus 40, or T7 promoters. The strongest expression was achieved with the T7 promoter and coinfection with vaccinia virus expressing the T7 RNA polymerase (MVA/T7pol). The FCV precursor capsid protein was processed to the mature-size protein, and these proteins were assembled in to virus-like particles.

Animals↗
PubMed1999

Diet promotes beta-cell loss by apoptosis in prediabetic nonobese diabetic mice.

Diet as an environmental factor influences age of onset in models of spontaneous insulin-dependent diabetes mellitus. We reported recently that a protein-rich diet accelerated diabetes incidence in nonobese diabetic (NOD) mice. In the present study, we investigated the effect of diet on beta-cells and glucose metabolism in NOD mice before diabetes onset. Three different diets were maintained from 4 weeks on: low fat (LF; 12% fat, 21% protein, and 68% carbohydrates), high fat (HF; 39% fat, 17% protein, and 43% carbohydrate), and high fat-high protein (HFHP; 43% fat, 38% protein, and 19% carbohydrates) diet. The cumulative incidence of diabetes was 92% for HFHP (P < 0.01 vs. LF), 80% for HF (P = NS), and 65% for the LF cohort. At 20 weeks of age insulin secretion in the isolated pancreas was doubled for the HF diet and 4.4 times higher for the HFHP-fed mice compared with the LF group. Feeding HF and HFHP reduced total glucose utilization during continuous insulin infusion (1 mU/kg) by 34% (P < 0.05). HFHP, but not HF, diet elevated endogenous glucose production by 48% (P < 0.05) compared with that in the LF group. Beta-cell mass, estimated by imaging analysis, was initially high in young HFHP-fed mice, aged 10 weeks, but declined rapidly thereafter [HFHP, 1.6 +/- 0.2 (P < 0.05 vs. LF); HF, 2.4 +/- 0.4 (P = NS vs. LF); LF, 2.1 +/- 0.5 mg at 30 weeks]. A reduction of beta-cell mass was associated with HF 14% (P < 0.05 vs. LF) and HFHP 82% (P < 0.01 vs. LF) more apoptotic beta-cells at 30 weeks. Depending on age, 1.2-3.1 of 1000 beta-cells were in a stage of proliferation without significant differences among the dietary groups. In conclusion, HFHP diet was associated with impaired glucose metabolism and high insulin release followed by enhanced diabetes incidence. Diabetes was promoted by increased rate of cell death over beta-cell neogenesis.

Animals↗
PubMed1999

Growth arrest-specific gene 6 (Gas6)/adhesion related kinase (Ark) signaling promotes gonadotropin-releasing hormone neuronal survival via extracellular signal-regulated kinase (ERK) and Akt.

We identified Ark, the mouse homolog of the receptor tyrosine kinase Axl (Ufo, Tyro7), in a screen for novel factors involved in GnRH neuronal migration by using differential-display PCR on cell lines derived at two windows during GnRH neuronal development. Ark is expressed in Gn10 GnRH cells, developed from a tumor in the olfactory area when GnRH neurons are migrating, but not in GT1-7 cells, derived from a tumor in the forebrain when GnRH neurons are postmigratory. Since Ark (Ax1) signaling protects from programmed cell death in fibroblasts, we hypothesized that it may play an antiapoptotic role in GnRH neurons. Gn10 (Ark positive) GnRH cells were more resistant to serum withdrawal-induced apoptosis than GT1-7 (Ark negative) cells, and this effect was augmented with the addition of Gas6, the Ark (Ax1) ligand. Gas6/Ark stimulated the extracellular signal-regulated kinase, ERK, and the serine-threonine kinase, Akt, a downstream component of the phosphoinositide 3-kinase (PI3-K) pathway. To determine whether ERK or Akt activation is required for the antiapoptotic effects of Gas6/Ark in GnRH neurons, cells were serum starved in the absence or presence of Gas6, with or without inhibitors of ERK and PI3-K signaling cascades. Gas6 rescued Gn10 cells from apoptosis, and this effect was blocked by coincubation of the cells with the mitogen-activated protein/ERK kinase (MEK) inhibitor, PD98059, or wortmannin (but not rapamycin). These data support an important role for Gas6/Ark signaling via the ERK and PI3-K (via Akt) pathways in the protection of GnRH neurons from programmed cell death across neuronal migration.

Androstadienes↗
PubMed1998

Quantitative electrospray LC-MS and LC-MS/MS in biomedicine.

The use of electrospray LC-MS and LC-MS/MS for the quantitative determination of two low molecular weight (< 500 Da) organic compounds in human plasma (Lovastatin) and cell supernatants (Arachidonic acid) and medium molecular weight (> 2000 Da) endogenous peptides (Endothelins) in supernatants of human umbilical vein endothelial cell cultures is reported. These methods make use either of deuterium labelled or structurally similar molecules as internal standards for quantitation and one or more pre-purification steps previous the LC-MS analysis. Linear calibration curves and detection limits around 50 pg ml(-1) were obtained in all three cases.

Arachidonic Acid↗
PubMed1998

The ROOT HAIRLESS 1 gene encodes a nuclear protein required for root hair initiation in Arabidopsis.

The epidermis of Arabidopsis wild-type primary roots, in which some cells grow hairs and others remain hairless in a position-dependent manner, has become an established model system to study cell differentiation. Here we present a molecular analysis of the RHL1 (ROOT HAIRLESS 1) gene that, if mutated, prevents the formation of hairs on primary roots and causes a seedling lethal phenotype. We have cloned the RHL1 gene by use of a T-DNA-tagged mutant and found that it encodes a protein that appears to be plant specific. The predicted RHL1 gene product is a small hydrophilic protein (38.9 kD) containing putative nuclear localization signals and shows no significant homology to any known amino acid sequence. We demonstrate that a 78-amino-acid sequence at its amino terminus is capable of directing an RHL1-GFP fusion protein to the nucleus. The RHL1 transcript is present throughout the wild-type plant and in suspension culture cells, but in very low amounts, suggesting a regulatory function for the RHL1 protein. Structural evidence suggests a role for the RHL1 gene product in the nucleolus. We have examined the genetic relationship between RHL1 and GL2, an inhibitor of root hair initiation in non-hair cells. Our molecular and genetic data with double mutants, together with the expression analysis of a GL2 promoter-GUS reporter gene construct, indicate that the RHL1 gene acts independently of GL2.

Amino Acid Sequence↗
PubMed1998

Detection of respiratory syncytial virus RNA in blood of neonates by polymerase chain reaction.

During the winter season of 1994/1995, nasopharyngeal aspirates and blood samples of neonates who were admitted to the Neonatal Intensive Care Unit (NICU) (group 1) and infants with respiratory tract disease (group 2) were examined prospectively for the presence of respiratory syncytial virus (RSV). Examination of nasal washes were done by antigen detection and blood samples were tested by nested reverse transcription and polymerase chain reaction (RT-PCR). The results of the 41 neonates studied were as follows: 14/41 were positive for RSV antigen in nasal washes and for RSV-RNA in blood, 5/41 were only RSV antigen positive, 13/41 neonates had negative nasal washes; 6 had positive RT-PCR results in blood. In 9/41 cases only blood samples were available. Five of these were positive by RT-PCR testing. Group 2 included 20 infants hospitalized with respiratory tract disease, e.g., pneumonia, bronchiolitis, or Upper Respiratory Tract Infection (URTI). Eleven out of twenty were positive for RSV antigen in nasal washes and 6/20 were also positive for RSV-RNA in blood. The conclusion is that viremia may be a frequent occurrence in neonates and young children.

Amino Acid Sequence↗
PubMed1998

[Effect of primary femoral plate osteosynthesis on the course of polytrauma patients with or without thoracic trauma].

Primary intramedullary nailing of femoral fractures is well known to increase the risk of pulmonary complications, especially in multiple-trauma patients with severe thoracic injuries. Aim of this study was to investigate the influence of primary plate osteosynthesis of femur fractures on major complications after trauma. This retrospective study based on the records of 325 multiple trauma patients (Injury severity score ISS > 18, no lethal brain injury, age 16-65). According to the abbreviated injury scale of the Thorax (AIS T) patients were divided in groups without (AIS T < 3, "N") or with relevant thoracic injury (AIS T > = 3, "T"). Both groups were additionally divided in subgroups without severe trauma to the extremities (AIS E < 3, "O") or primary plate-osteosynthesis of femur fractures (< 24 h, "I"). 4 groups were performed: NO (n = 39, ISS 25 +/- 1, pneumonia 10%, ARDS 5%, lethality 10%); NI (n = 55, ISS 27 +/- 1, pneumonia 4%, ARDS 5%, lethality 4%); TO(n = 137, ISS 28 +/- 1, pneumonia 21%, ARDS 15%, lethality 16%); TI (n = 94, ISS 31 +/- 1, pneumonia 21%, ARDS 17%, lethality 15%). Primary plate-osteosynthesis of femur fractures did not increase lethality or incidence of pulmonary complications in patients with or without severe thoracic injuries. Also complication rate after primary plate-osteosynthesis was less compared to published results after intramedullary nailing. For this, primary plate-osteosynthesis is recommendable in case of multiple trauma with thoracic injuries.

Adolescent↗
PubMed1998

Multijoint arm movements in cerebellar ataxia: abnormal control of movement dynamics.

In cerebellar ataxia, kinematic aberrations of multijoint movements are thought to originate from deficiencies in generating muscular torques that are adequate to control the mechanical consequences of dynamic interaction forces. At this point the exact mechanisms that lead to an abnormal control of interaction torques are not known. In principle, the generation of inadequate muscular torques may result from an impairment in generating sufficient levels of torques or from an inaccurate assessment and prediction of the mechanical consequences of movements of one limb segment on adjacent joints. We sought to differentiate the relative contribution of these two mechanisms and, therefore, analyzed intersegmental dynamics of multijoint pointing movements in healthy subjects and in patients with cerebellar degeneration. Unrestrained vertical arm movements were performed at three different target movement velocities and recorded using an optoelectronic tracking system. An inverse dynamics approach was employed to compute net joint torques, muscular torques, dynamic interaction torques and gravitational torques acting at the elbow and shoulder joint. In both groups, peak dynamic interaction forces and peak muscular forces were largest during fast movements. In contrast to normal subjects, patients produced hypermetric movements when executing fast movements. Hypermetric movements were associated with smaller peak muscular torques and smaller rates of torque change at elbow and shoulder joints. The patients' deficit in generating appropriate levels of muscular force were prominent during two different phases of the pointing movement. Peak muscular forces at the elbow were reduced during the initial phase of the movement when simultaneous shoulder joint flexion generated an extensor influence upon the elbow joint. When attempting to terminate the movement, gravitational and dynamic interaction forces caused overshooting extension at the elbow joint. In normal subjects, muscular torque patterns at shoulder and elbow joint were synchronized in that peak flexor and extensor muscular torques occurred simultaneously at both joints. This temporal pattern of muscular torque generation at shoulder and elbow joint was preserved in patients. Our data suggest that an impairment in generating sufficient levels of phasic muscular torques significantly contributes to the patients' difficulties in controlling the mechanical consequences of dynamic interaction forces during multijoint movements.

Adult↗
PubMed1998

A comparative study of impact dynamics: wobbling mass model versus rigid body models.

We demonstrate that the results of inverse dynamics depend sensitively on the model used to simulate the human body. For this reason we produce "ideal" input data of the ground reaction force and the heel acceleration for a computer simulated drop jump with a wobbling mass model. Then we determine the internal torques and forces in the knee and hip joint via inverse dynamics by employing a rigid body model. It turns out that during the impact phase the analysis with the rigid body model yields completely incorrect internal torques and forces.

Acceleration↗
PubMed1998

Aortic valve stenosis as a cause of major systemic embolism--a case report.

This is the first documented case of a patient suffering from embolic occlusion of the left brachial artery caused by a large embolus growing on a lesion of a stenosed calcified aortic valve. Supported by their own additional observations the authors suggest that severe calcified aortic valve stenosis should be considered as an indication for anticoagulation in the period before surgical valve replacement.

Acute Disease↗
PubMed1997

Comparative in-vivo and in-vitro 99Mo-time-differential-perturbed-angular-correlation studies on the nitrogenase MoFe protein and on other Mo species of different N2-fixing bacteria.

Klebsiella pneumoniae, Azotobacter vinelandii and Rhodobacter capsulatus were cultivated in media containing 99MoO4(2-) . The distribution of 99Mo in cells grown under conditions of repression and derepression of nitrogenase synthesis, was investigated by anion-exchange (DEAE-Sephacel) chromatography. Cells of K. pneumoniae took up MoO4(2-) only under conditions of derepression of nitrogenase thus serving the formation of the FeMo cofactor of the MoFe protein (Kp1) as the predominant Mo-containing species. In the case of A. vinelandii, under diazotrophic growth conditions, molybdenum was preferably incorporated into the nitrogenase MoFe protein (Av1). However, if excess amounts of molybdate were present in the medium, molybdenum was also bound to the Mo-storage protein. In the presence of 20 mM NH4+, conditions which completely repress nitrogenase formation, molybdenum accumulated in the Mo-storage protein exclusively. This protein proved to be unstable towards DEAE-Sephacel, apparently releasing all the molybdenum in form of MoO4(2-) during the fractionation procedure. R. capsulatus contained, in addition to the MoFe protein (Rc1), significant amounts of other not-yet-identified Mo species, which partially are formed under conditions of both, repression and derepression of nitrogenase. The Mo centers of all these compounds were characterized by measuring the nuclear quadrupole interaction of the process 99Mo(beta-)99Tc using time differential perturbed angular correlation spectroscopy. The quadrupole coupling constant (v(Q)) determined for the Mo center in MoFe proteins was consistently in the range 66-81 MHz. The values of the coupling constants determined with intact cells and with the isolated, partially purified, MoFe proteins were in very good agreement. For the Mo-storage protein of A. vinelandii, a quadrupole coupling constant of approximately 180 MHz was determined by measurements performed with nitrogenase-repressed cells as well as with gel-filtered cell-free extracts. Our work proves that the relevant study of hyperfine interactions allows the identification of the MoFe protein and also other Mo proteins in vivo as well as in vitro.

Azotobacter vinelandii↗
PubMed1997

Genetic testing for susceptibility to adult-onset cancer. The process and content of informed consent.

OBJECTIVE: To provide guidance on informed consent to clinicians offering cancer susceptibility testing. PARTICIPANTS: The Task Force on Informed Consent is part of the Cancer Genetics Studies Consortium (CGSC), whose members were recipients of National Institutes of Health grants to assess the implications of cancer susceptibility testing. The 10 task force members represent a range of relevant backgrounds, including various medical specialties, social science, genetic counseling, and consumer advocacy. EVIDENCE: The CGSC held 3 public meetings from 1994 to 1996. At its first meeting, the task force jointly established a list of topics. The cochairs (G.G. and J.R.B) then developed an outline and assigned each topic to an appropriate writer and reviewer. Writers summarized the literature on their topics and drafted recommendations, which were then revised by the reviewers. The cochairs compiled and edited the entire manuscript. All members were involved in writing this report. CONSENSUS PROCESS: The first draft was distributed to task force members, after which a meeting was held to discuss its content and organization. Consensus was reached by voting. A subsequent draft was presented to the entire CGSC at its third meeting, and comments were incorporated. CONCLUSIONS: The task force recommends that informed consent for cancer susceptibility testing be an ongoing process of education and counseling in which (1) providers elicit participant, family, and community values and disclose their own, (2) decision making is shared, (3) the style of information disclosure is individualized, and (4) specific content areas are discussed.

Adaptation, Psychological↗