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Biomedical subjects

M Peters

Publications and source records attributed to M Peters.

At least 37 records · Page 2Linked to original sources
PubMed2001

Interleukin-6 expression in exo-focal neurons after striatal cerebral ischemia.

Although anatomical and biochemical properties of the rat entopeduncular nucleus (EPN) closely resemble those of the substantia nigra pars reticulata (SNr), the present study shows that, unlike in the SNr, focal cerebral ischemia does not cause trans-synaptic degeneration of EPN neurons, despite striatal infarction and a similar delayed glial activation in both nuclei. In this study, interleukin-6 (IL-6) expression was found within EPN neurons 3 and 7 days after striatal ischemia. Since it has been reported that neuroprotective properties seem to predominate IL-6 function and that distinct SNr regions which demonstrate low trans-synaptic neuronal degeneration show high IL-6 expression and vice versa, IL-6 expression within partially deafferentiated but surviving EPN neurons could represent an intrinsic neuroprotective mechanism.

Animals↗
PubMed2001

Hypertrophic pulmonary osteoarthropathy without clubbing of the digits.

Hypertrophic osteoarthropathy (HOA) typically occurs concurrently with clubbing of the digits, with isolated HOA being reported only rarely. We report two patients with intra-thoracic malignancy in whom HOA, demonstrated on bone scintigraphy, developed in the absence of clubbing. We also report the novel observation of involvement of the metatarsal and metacarpal bones by HOA.

Aged↗
PubMed2001

Lymphedema in a cohort of breast carcinoma survivors 20 years after diagnosis.

BACKGROUND: To the authors' knowledge, there are no long-term cohort studies of lymphedema, despite the substantial morbidity of arm swelling. The goal of this study was to identify prevalence of breast carcinoma-related lymphedema, time of onset, and associated predictive factors. METHODS: A cohort of 923 women consecutively treated with mastectomy and complete axillary dissection at our center between 1976 and 1978 was observed intensively for 20 years. Two hundred sixty-three study subjects (28.5%) who were alive and recurrence free constituted the cohort for the current study. A subset of 52 women (20% of study population) with contralateral mastectomy was analyzed separately. Subjects reported circumferential arm measurements taken using a validated instrument. In addition to providing analysis of clinical and treatment variables, this study is the first to the authors' knowledge to analyze possible etiologic factors in the posttreatment years, such as occupation, general physical activity, and sports/leisure activities. Univariate and multivariate analytic methods were used. RESULTS: At 20 years after treatment, 49% (128 of 263) reported the sensation of lymphedema. Arm swelling measurements were severe (> or = 2.0 in [5.08 cm]; patients reported measurement in inches) for 13% (33 of 263 women). Seventy-seven percent (98 of 128) noted onset within 3 years after the operation; the remaining percentage developed arm swelling at a rate of almost 1% per year. Of the 15 potential predictive factors analyzed, only 2 were statistically significantly associated with lymphedema: arm infection/injury and weight gain since operation (P < 0.001 and P = 0.02, respectively). CONCLUSIONS: This defined cohort, treated by axillary dissection 20 years ago, documents the high prevalence of lymphedema and its time course. Two significantly associated factors, both potentially controllable, are identified. The current study provides further support for treatments that limit lymph node dissection. The authors are prospectively evaluating patients undergoing sentinel lymph node biopsy.

Aged↗
PubMed2001

[One year of neonatal screening for sickle-cell disease in Emma Children's Hospital/Academic Medical Center in Amsterdam].

OBJECTIVE: Early detection of children with sickle cell disease, determination of carriership frequency as well as evaluation of the knowledge regarding this haemoglobinopathy in various ethnic risk groups. DESIGN: Prospective. METHODS: From 1 November 1998 through to 31 October 1999, the ethnic background was recorded for consecutive pregnant women under care of the Academic Medical Centre, Amsterdam, the Netherlands, and the presence of carriership for sickle cell disease was evaluated. Carriers were asked about their knowledge of sickle cell disease. A diagnostic blood test of cord blood was also performed using a PCR which could detect both haemoglobin S and C mutations. RESULTS: Fifty-five carriers were detected in a group of 1,016 investigated pregnant women (5.4%). The carriership frequencies in Surinam and African women were 12 and 15.7%, respectively. Knowledge of sickle cell disease, its occurrence in populations at risk, as well as the terms 'inheritance' and 'carriership', differed substantially between Surinam and African women, with awareness being lower in the latter group. In six cases informed consent was not asked. All other 49 carriers consented to a diagnostic test. Two intrauterine deaths occurred. Four children had sickle cell disease: three had HbSS, one had HbSC. Nineteen children proved to be carriers for sickle cell disease, 18 were heterozygotes for HbS, one for HbC. CONCLUSION: This targeted neonatal screening for sickle cell disease was feasible in a hospital setting. The number of children diagnosed with the disease supports the wider implementation of this method of early detection.

Africa↗
PubMed2001

Plasmid-encoded catalase KatA, the main catalase of Pseudomonas fluorescens strain Cb36.

The plasmid-state catalase gene katA of the phenol gradative Pseudomonas fluorescens isolate Cb36 has been characterized and shown to be the major catalase of this strain. The predicted amino acid sequence of KatA revealed significant similarity with the catalase sequence from Neisseria meningitidis and has probably the non-pseudomonad origin. The specific activity of catalase was investigated and elevated catalase activity was found in stationary phase cells. The consensus sequence for promoters recognized by the stationary phase sigma factor sigma(s) was found 212 bp upstream of the putative ATG start codon. The ability of KatA to detoxify a high concentration of hydrogen peroxide and protect Pseudomonas putida and Escherichia coli cells was shown.

Amino Acid Sequence↗
PubMed2001

Neospora caninum infection associated with stillbirths in captive antelopes (Tragelaphus imberbis).

Neosporosis was diagnosed in full-term stillborn twin calves of captive antelopes (Tragelaphus imberbis) in a German zoo. In both calves a multifocal non-suppurative encephalitis was present and infection with Neospora (N.) caninum was confirmed by foetal serology and PCR. N. caninum-DNA was detected in brain, heart, lung, liver and spleen of a third full-term stillborn calf. Histopathological lesions were absent in this calf and antibodies against N. caninum were not detected in pleural fluid. Immunohistochemistry failed to demonstrate N. caninum antigen in all three calves.

Animals↗
PubMed2001

Ischemic preconditioning prevents endothelial injury and systemic neutrophil activation during ischemia-reperfusion in humans in vivo.

BACKGROUND: Endothelial dysfunction leading to neutrophil infiltration of tissues has been implicated in tissue injury caused by ischemia-reperfusion (IR). Tissue injury during IR can be reduced by prior ischemic preconditioning (IPC). In humans, it is unclear whether endothelial dysfunction occurs during IR or whether IPC offers protection against endothelial dysfunction and inflammatory cell activation. We studied the effects of experimental IR on endothelial and neutrophil function in the human forearm in vivo and examined the protection afforded by IPC. METHOD AND RESULTS: The forearm was made ischemic for 20 minutes by inflating a blood pressure cuff to 200 mm Hg. We assessed endothelial function of conduit (radial artery flow-mediated dilation) and resistance vessels (blood flow responses to intra-arterial infusion of the endothelium-dependent dilator acetylcholine) in healthy volunteers before and after IR. IR reduced flow-mediated dilation of the radial artery at 15 minutes of reperfusion (7.7+/-1.5% to 3.5+/-0.9%) and the dilator response of resistance vessels to acetylcholine at 15, 30, and 60 minutes of reperfusion. IR did not reduce the dilator response of the radial artery to glyceryltrinitrate and only caused a small reduction of glyceryltrinitrate-induced dilation of resistance vessels at 60 minutes of reperfusion. IR caused an increase in neutrophil CD11b expression and platelet-neutrophil complexes in the circulating blood. IPC (three 5-minute episodes of ischemia) before IR prevented endothelial dysfunction and neutrophil activation. CONCLUSIONS: A clinically relevant period of ischemia-reperfusion causes profound and sustained endothelial dysfunction and systemic neutrophil activation. IPC attenuates both of these effects in humans.

Acetylcholine↗
PubMed2001

Up-Regulation of Bcl-2 in microvascular endothelial cells enhances intratumoral angiogenesis and accelerates tumor growth.

Vascular endothelial growth factor (VEGF) has been shown to be a potent mediator of angiogenesis that functions as a survival factor for endothelial cells by up-regulating Bcl-2 expression. We have recently reported that human dermal microvascular endothelial cells (HDMECs) seeded in biodegradable sponges and implanted into severe combined immunodeficient (SCID) mice organize into functional human microvessels that transport mouse blood cells. In this study, we implanted sponges seeded with OSCC-3 (oral squamous cell carcinoma) or SLK (Kaposi's sarcoma) together with endothelial cells into SCID mice to generate human tumors vascularized with human microvessels. This model system was used to examine the role of both endothelial cell Bcl-2 and the proangiogenic chemokine interleukin-8 (IL-8) on tumor growth and intratumoral microvascular density. Coimplantation of HDMECs overexpressing Bcl-2 (HDMEC-Bcl-2) and tumor cells resulted in a 3-fold enhancement of tumor growth when compared with the coimplantation of control HDMECs and tumor cells. This was associated with increased intratumoral microvascular density and enhanced endothelial cell survival. To determine whether the enhanced neovascularization mediated by Bcl-2 overexpression in endothelial cells was influenced by the synthesis of endogenous mediators of angiogenesis, we screened these cells for expression of VEGF, basic fibroblast growth factor (bFGF), and IL-8 by ELISA. HDMEC-Bcl-2 cells and VEGF-treated HDMECs exhibited a 15-fold and 4-fold increase, respectively, in the expression of the proangiogenic chemokine IL-8 in vitro, whereas the expression of VEGF and bFGF remained unchanged. Transfection of antisense Bcl-2 into HDMECs blocked VEGF-mediated induction of IL-8. Conditioned media from HDMEC-Bcl-2 induced proliferation and sprouting of endothelial cells in vitro and neovascularization in rat corneas. Anti-IL-8 antibody added to HDMEC-Bcl-2 conditioned media markedly reduced the potency of these responses. SCID mice bearing VEGF-producing tumor implants that were treated with anti-lL-8 antibody exhibited a 43% reduction in microvessel density and a 50% reduction in tumor weight compared with treatment with a nonspecific antibody. These results demonstrate that the up-regulation of Bcl-2 expression in endothelial cells that constitute tumor microvessels enhances intratumoral microvascular survival and density and accelerates tumor growth. Furthermore, endothelial cells that overexpress Bcl-2 have more angiogenic potential than control cells, and IL-8-neutralizing antibodies attenuate their angiogenic activity in vitro and in vivo.

Animals↗
PubMed2001

The designer cytokine hyper-IL-6 mediates growth inhibition and GM-CSF-dependent rejection of B16 melanoma cells.

The low immunogenic B16 melanoma cell line was transfected with a mammalian expression vector containing the complementary DNA for a sIL-6R/IL-6 fusion protein, termed Hyper-IL-6 (H-IL-6), which was shown to have biological activities at 100-1000-fold lower concentrations than IL-6 in combination with sIL-6R. The secreted p84 glycoprotein was detected in the supernatant of transfected cells and was fully active on BAF3/gp130 cells, which respond to IL-6/sIL-6R but not to IL-6 alone. Administration of recombinant H-IL-6 to C57BL/6 mice resulted in a prolonged acute phase protein gene expression indicating long systemic persistence of the fusion protein. Transfected B16 cells (B16/H-IL6 cells) showed morphological alterations in combination with a dramatic growth inhibition in vitro. Subcutaneous injection in C57BL/6 mice resulted in an almost complete rejection of B16/H-IL6 cells. This effect was partially abolished in FVB/BL/6 mice transgenic for a GM-CSF receptor antagonist, indicating a GM-CSF-dependent rejection of H-IL-6 transfected B16 cells. These results demonstrate that the anti-tumor effect of cytokines like IL-6 which are secreted by transfected melanoma cells at least in part depends on GM-CSF activity.

Animals↗
PubMed2001

Multiple VH genes are used to assemble human antibodies directed toward the A3-C1 domains of factor VIII.

A well-known complication of factor VIII replacement therapy in patients with hemophilia A is the development of inhibitory antibodies. Several studies have demonstrated the presence of a binding site for factor VIII inhibitors in the A3 domain. Six different human monoclonal single-chain variable domain antibody fragments (scFv) directed toward the A3-C1 domains of factor VIII have been isolated, using phage display technology. Sequence analysis revealed that the V(H) domains of 2 scFv were encoded by germline gene segments from the V(H)1 gene family and 4 by germline gene segments belonging to the V(H)3 gene family. Epitope mapping of the scFv was performed, using a series of hybrid factor VIII/factor V light chain fragments. This analysis revealed that 5 of 6 scFv were directed against a region encompassing amino acid sequence Q1778-D1840 in the A3 domain, a previously identified binding site for factor VIII inhibitors. Only 2 of 5 scFv directed against amino acid sequence Q1778-D1840 inhibited the procoagulant activity of factor VIII. Our results define the properties of human antibodies directed against region Q1778-D1840 in the A3 domain. Binding of one, noninhibitory scFv was independent of the region Q1778-D1840, suggesting the presence of an additional binding site for anti-factor VIII antibodies in the A3-C1 domains of factor VIII.

Amino Acid Sequence↗
PubMed2001

Features of the replicon of plasmid pAM10.6 of Pseudomonas fluorescens.

We describe features of the basic replicon of the 10.6-kb medium-copy-number plasmid pAM10.6. pAM10.6 was able to replicate in various Pseudomonas strains but was maintained in Escherichia coli only after the p15A origin of replication was inserted. Deletion analysis suggests that the pAM10.6 origin of replication is located in a 0.5-kb region that includes inverted and direct repeats upstream of the repA gene. RepA (204 aa) has a clear homology to plasmid replication proteins of some other gram-negative bacteria. The pas (plasmid addiction system) (genes encoded in the region of 480-bp) stabilizes plasmid maintenance in P. putida cells under nonselective conditions for at least 200 generations. A 3.75-kb PstI fragment of pAM10.6 joined to a Km(r) gene was shown to be a minimal plasmid unit maintained in P. putida as a monomer. Further deletions of this 3.75-kb fragment caused a drive to form stable head-to-tail dimeric plasmids in P. putida.

Amino Acid Sequence↗
PubMed2001

"Getting Switzerland to move": evaluation of a new "Sport for All" programme.

OBJECTIVES: Even though sports participation in Switzerland appears to be quite elevated, recent research suggests that only about a third of the population are doing enough sports from a health perspective. METHODS: Against this background several Swiss health insurance companies together with the Swiss Olympic Association have recently developed a novel approach to get people to start physical exercise: Under the label of "Allez Hopl" sport clubs offer training and information courses aimed at motivating and helping previously inactive people to take on regular exercise. RESULTS: The paper presents results from an interdisciplinary evaluation of the first three years of the "Allez Hopl" campaign. Starting from an overview of the basic idea and features of the campaign it asks whether "Allez Hopl" has reached its self-declared goal of "getting Switzerland moving". Available evidence on the social background of participants and their further activities shows that by systematically avoiding any reference to conventional notions of sport and by stressing the health and fun aspect instead. "Allez Hopl" has indeed managed to mobilise an important group with under-average levels of activity (particularly middle-aged women). In addition, on average the level of physical exercise of participants appears to have increased. Yet, the number of participants is below the original target values and, contrary to the campaign's initial goal, participants are reluctant to leave the programme after one course to take up an independent activity or to join a club. CONCLUSIONS: The paper explores the achievements and problems of the campaign so far and offers an explanation of recent problems which can also serve as a basis for the implementation of similar programmes in other countries.

Attitude to Health↗
PubMed2001

[Treatment outcome of inpatient psychosomatic rehabilitation of elderly patients].

Empirical data about the different effects of a specific inpatient psychotherapeutic intervention for elderly patients (over 55 years) are presented in this study. An analysis of sub-units presented four different groups of elderly patients with different psychotherapy effects. Three of four groups showed significant reduced stress in self-rated well-being and depression, only one group had no significant effects one year after the inpatient psychotherapy. Because the patients of this group describes themselves at the beginning of the treatment as "quite normal", significant effects in outcome are hardly to be expected. For a better understanding of this group, other-rated information is necessary. Implications for changing the treatment are discussed.

Aged↗
PubMed2001

Different immune patterns in melancholic and non-melancholic major depression.

The search for immune patterns in major depression has thus far resulted in ambiguous findings, probably because patient samples are psychiatrically heterogeneous. We therefore focused on a detailed classification of subtypes of major depression, comparing patients with melancholic and non-melancholic major depression. Inpatients suffering from acute major depression were diagnosed and subclassified according to DSM IV criteria. Cell counts were determined by FACS analysis and morphology. Cytokine production (IL-2, IFN-gamma, IL-10) upon mitogen stimulation was measured by ELISA in a whole blood assay. Non-melancholic patients showed increased counts of leukocytes, lymphocytes and NK-cells in the acute stage of disease and after two and four weeks of treatment. Their lymphokine production was unchanged compared to that of healthy controls. Melancholic patients on the other hand demonstrated normal cell counts but a decreased production of IL-2, IFN-gamma and IL-10 during the acute stage of disease followed by a normalization with clinical improvement. Melancholic and non-melancholic patients showed different immune patterns. Classifying melancholic and non-melancholic patients is helpful towards the identification of immune characteristics typical for these diseases.

Adult↗
PubMed2001

On becoming neutral: effects of experimental neutralizing reconsidered.

Behaviour Research and Therapy 34 (1996) 889-898 found that writing out a negative thought produced anxiety and an urge to neutralize the thought, that instructing participants to neutralize the thought reduced anxiety/neutralization urge in the short run (i.e. within 2 min), but that in the control group 20 min without instruction was attended by the same reduction in anxiety/urge to neutralize ("natural decay"). The observations were made with pariticipants who scored high on "thought action fusion" and the experiment was set up as exerimental model of obsessions. We repeated the study with participants that were not selected on thought action fusion. All the findings reported by Behaviour Research and Therapy 34 (1996) 889-898 were replicated. Correlational analysis indicated that the strength of the effect was not related to scores on scales measuring "thought action fusion". Behaviour Research and Therapy 34 (1996) 889-898 did not assess whether non-neutralizing was followed by immediate reductions in distress. We did assess this and found that the larger part of the immediate reduction of distress after neutralization also occurs when no neutralization instruction is given. The effects of neutralization instructions in the present type of experiment are considerably less powerful than suggested earlier.

Adolescent↗
PubMed2001

Immunohistochemical and ultrastructural evidence for Neospora caninum tissue cysts in skeletal muscles of naturally infected dogs and cattle.

Protozoan stages were detected in the skeletal muscles of four dogs suffering from neosporosis and two neonatal calves with confirmed Neospora caninum- infection which could be immunohistochemically labelled by an antiserum against the bradyzoite-specific antigen BAG-5. In one calf, a tissue cyst was labelled by an antiserum against the N. caninum isolate NC-1. Ultrastructurally, a 0.3-1 microm-thick cyst wall surrounded the labelled parasites. The cysts were located within myofibres and contained varying numbers of bradyzoites each measuring 5.2(+/-0.6) x 1.6(+/-0.3) microm. The encysted stages showed typical ultrastructural features of N. caninum bradyzoites with subterminal nuclei, electron-dense rhoptries, and micronemes that were orientated perpendicular to the zoite pellicle. Immunohistochemistry and serology did not reveal any evidence for co-infection with Toxoplasma gondii. The detection of tissue cysts in skeletal muscle of N. caninum-infected intermediate hosts is of major epidemiological importance for the understanding of how definitive or intermediate carnivorous hosts become infected with N. caninum.

Animals↗
PubMed2001

Modulation of excitability as a learning and memory mechanism: a molecular genetic perspective.

Gene targeting has contributed substantially to the investigation of the neurobiological basis of mammalian learning and memory (L&M). These experiments start with an hypothesis as to a mechanism underlying L&M, then genes of interest are manipulated, and the impact on neuronal physiology and L&M is studied. Previous gene targeting studies have focussed mainly on the role of synaptic plasticity in L&M. Some of those reports provide evidence that processes other than, or additional to, long-term potentiation (LTP) are required for L&M. Accordingly, it is possible that altered neuronal excitability is an essential mechanism. The properties of ion channels determine neuronal excitability and so genetic alteration of ion channel properties is an appropriate method for testing whether the modulation of excitability affects L&M. K(v)beta 1.1-deficient mice were the first mutants used to study the role of altered excitability in mammalian L&M. K(v)beta 1.1 is a regulatory subunit with a restricted expression pattern in the brain, and it confers fast inactivation on otherwise noninactivating K(+) channel subunits. In hippocampal pyramidal neurones Kv beta 1.1-deficiency results in a reduced slow after-hyperpolarisation (sAHP), modulation of which is thought to contribute to L&M. The L&M phenotype of the mutants supports this sAHP hypothesis. It is expected that further gene targeting studies on excitability will lead to valuable insights into the processes of L&M.

Animals↗