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Biomedical subjects

M Koch

Publications and source records attributed to M Koch.

At least 37 records · Page 2Linked to original sources
PubMed2005

Endoscopic treatment of gastroesophageal reflux disease.

Gastroesophageal reflux disease is a common chronic disorder which has a severe effect on the patient's quality of life. In view of the high cost of medical therapy and the limitations of surgery, a variety of endoscopic techniques have been developed for the treatment of this condition, and these have shown apparently encouraging results, at least in the short term. However, promising results have been obtained in only around two-thirds of patients over a short-term follow-up period of about 6 months. Moreover, several inconsistencies have emerged between the efficacy of this form of treatment in improving symptoms and quality of life and a lack of improvement of objective parameters, such as lower esophageal sphincter pressure and esophageal acid exposure. The authors strongly endorse the need for comprehensive evaluation of clinical evidence on this topic. After an extensive evaluation of existing literature, we suggest that controlled studies are urgently needed in order to clarify the potential of endoscopic therapy, either in terms of cost-effectiveness or in comparison with standard therapy. Meanwhile, with regard to current practice, the use of endoscopic treatment should be limited to clinical trials, which should incorporate the provision of comprehensive and unbiased information to study patients.

Catheter Ablation↗
PubMed2005

Behavioral effects in adult rats of chronic prepubertal treatment with the cannabinoid receptor agonist WIN 55,212-2.

Human and animal studies provide evidence for vulnerable periods of brain development for deleterious effects of cannabinoids. We have recently shown that pubertal chronic cannabinoid treatment leads to long-lasting behavioral deficits, whereas a comparable treatment in adult rats did not affect the animals' behavior. In the present study we examined the effects of an identical chronic cannabinoid treatment in juvenile rats, just before the onset of puberty. Treatment with the synthetic cannabinoid agonist WIN 55,212-2 (WIN) (1.2 mg/kg) or vehicle was extended over 25 days throughout the prepubertal period (postnatal days 15-40) in juvenile rats. The rats received a total of 20 injections intraperitoneally. Adult rats were tested for object recognition memory, performance in a progressive ratio (PR) operant behavior task, locomotor activity and prepulse inhibition (PPI) of the acoustic startle response. Juvenile chronic WIN administration had no effect on object recognition memory, PR performance and locomotor activity in adulthood. However, a PPI deficit was observed in WIN-treated rats when tested as adults that could be reversed by the acute administration of the dopamine receptor antagonist haloperidol (0.1 mg/kg). Additionally, juvenile cannabinoid treatment reduced the number of rearings, as well as the time spent in the center of the open field in adult rats, suggesting increased anxiety. Juvenile chronic cannabinoid treatment induced behavioral disturbances in adult rats that are less severe than those observed after pubertal cannabinoid administration. However, based on the observations of sensorimotor gating deficits and increased anxiety, we conclude that the prepubertal developmental phase, in addition to puberty, also represents a vulnerable time period for persistent adverse effects of cannabinoids.

Aging↗
PubMed2005

Use of LifeSite port systems for hemodialysis in Germany.

AIM: Studies haveshown lower infection rates of port systems compared to established, transcutaneous cuffed-tunneled dialysis catheters. This was shown in otherwise quite healthy patients starting hemodialysis treatment. It is unclear to what extent these results can be applied to countries such as Germany where, unlike the US, central venous access systems are used mainly for patients with a high comorbidity. We investigated complications in patients with exhausted access sites and a high comorbidity. METHOD: In a retrospective, representative multicenter study, 34 patients with a high rate of comorbidity were assessed. The age was 67.5 +/- 12.5 years, the median number of failed AV fistulas or AV grafts was 4 (0-18). RESULTS: The survival rate was 84.9%, 55.2% and 55.2% after 6, 12 and 24 months, respectively. The rate of local and systemic infections was 2.83 per 1,000 patient days. Thrombotic events occurred at a rate of 2.26 per 1,000 patient days. We did not see a statistically significant effect using 0.2% sodium oxychlorosene (n = 13) or 70% isopropyl alcohol solution (n = 21) as the antimicrobial solution used before opening the valve of the port with the dialysis needle. CONCLUSIONS: We showed that complications of hemodialysis treatment using LifeSite vascular access systems in patients with very high co-morbidity in Germany seem to occur less often than those reported for cuffed-tunneled catheters and were not more frequent than those reported for other patient groups using LifeSites in the US. Technical survival rates were encouraging for up to two years. LifeSite port systems might be a good or even better central venous access than cuffed-tunneled catheters for patients in which an AV fistula or -graft is not possible.

Aged↗
PubMed2004

129Xe on Ir(111): NMR study of xenon on a metal single crystal surface.

NMR experiments of (129)Xe adsorbed on an iridium single crystal surface are reported. Very high nuclear polarization (P(z) approximately 0.7) makes the experiment possible. A coverage of less then one monolayer is investigated on the Ir(111) surface with an area of 0.8 cm(2). The observed resonance line shifts are very large and highly anisotropic. We find sigma(iso) = 1,032 +/- 11 ppm and sigma(an) = 291 +/- 33 ppm, which are far above the typical range of physisorption. The highly ordered substrate leads to homogeneous conditions for the xenon atoms, as seen in the narrow linewidth of 20 ppm. Chemical shifts under physisorption conditions are not large enough to totally explain the results. Knight shift can clearly be identified as the cause of the findings. This shift shows the presence of conduction electrons of the metallic substrate at the xenon nucleus and thus the mixing of metallic and atomic states at the Fermi level. Such mixing is in accordance with recent Hartree-Fock and density functional calculations of similar van der Waals adsorption systems. Quantitative comparisons, however, fail completely. The size and ratio of sigma(an) and sigma(iso) are pure ground-state properties in a structurally simple system. They are accessible to theory and provide detailed local information that can serve as a benchmark for theory.

Journal Article↗
PubMed2004

Influence of genetic polymorphisms of the renin-angiotensin system on IgA nephropathy.

BACKGROUND: We evaluated the impact of the three major genetic polymorphisms of the renin-angiotensin system [angiotensinogen (AGT) gene M235T, angiotensin-converting enzyme (ACE) gene-I/D and angiotensin II-type 1 receptor (AT1R) gene A1166C polymorphisms] as risk factors in IgA nephropathy. METHODS: The clinical course of 107 patients with biopsy proven IgA nephropathy followed up for 6.6 +/- 5.8 years was examined. The genetic polymorphisms were determined by PCR amplification. RESULTS: The allele frequencies of the polymorphisms studied were similar in patients and control subjects. AGT-M235T genotype was associated with the presence of nephrotic syndrome (p < 0.05), correlated to the number of antihypertensive drugs agents taken (p < 0.01) and influenced the rate of deterioration of renal function (p < 0.05). Combined analysis of AGT-M235T and ACE-I/D polymorphisms detected an interaction on affecting progression (p < 0.05). ACE-inhibition had a more pronounced effect in certain AGT-M235T and ACE-I/D genotypes (p < 0.05) and their combined analysis showed a synergistic effect (p < 0.01). No association between AT(1)R-A1166C polymorphism and any of the parameters studied was observed. CONCLUSIONS: Our results suggest that angiotensinogen-M235T polymorphism is an important marker of progression in IgA nephropathy in Caucasian patients, especially when analyzed in combination with ACE-I/D polymorphism.

Female↗
PubMed2004

Hematogenous tumor cell dissemination during colonoscopy for colorectal cancer.

BACKGROUND: It has long been suspected that mechanical influences may enhance the release of viable colorectal cancer cells into the circulation. The objective of this study was to determine the extent of hematogenous tumor cell spread in colorectal cancer patients during colonoscopy. METHODS: Peripheral venous blood samples were taken before and after colonoscopy from 44 patients with colorectal cancer. Blood samples were examined using a reverse-transcriptase polymerase chain reaction assay to amplify cytokeratin 20 transcripts. RESULTS: Eleven patients with colorectal cancer displayed circulating tumor cells before and after colonoscopy (25%), whereas tumor cells were detected in six of 44 patients (14%) only after the procedure (p = 0.03, McNemar's test: tumor cell detection before after colonoscopy). All control samples consistently tested negative. CONCLUSIONS: Mechanical forces may result in enhanced release of viable colorectal cancer cells into the circulation; however, the clinical significance of these results needs to be clarified.

Adenocarcinoma↗
PubMed2004

Role of the medial prefrontal cortex in N-methyl-D-aspartate receptor antagonist induced sensorimotor gating deficit in rats.

The medial prefrontal cortex (mPFC) regulates sensorimotor gating measured as prepulse inhibition (PPI) of startle. We here tested the effect of lesions of the mPFC on the PPI-disruptive effect of the non-competitive NMDA receptor antagonist dizocilpine in rats. Neurotoxic lesions of the mPFC were induced by ibotenic acid. Rats were tested for PPI after systemic injection of dizocilpine (0.15 mg/kg) and after injection of the dopamine receptor agonist apomorphine (2 mg/kg). Dizocilpine failed to disrupt PPI in rats with mPFC lesions while the PPI-disruptive effect of apomorphine was not affected. Startle response magnitude in the absence of prepulses was not affected by mPFC lesions or drugs. These data suggest that the mPFC is an important brain region within the neuronal circuit responsible for NMDA receptor antagonist induced PPI-deficits.

Animals↗
PubMed2004

[Kausch-Whipple pancreaticoduodenectomy. Technique and results].

The Kausch-Whipple operation is the standard procedure for resection of pancreatic head cancer, distal bile duct cancer, and periampullary cancers. It is also used for some cases of chronic pancreatitis. Traditionally, this operation is associated with high perioperative morbidity and mortality. The aim of our study was to present our current technique for Kausch-Whipple pancreaticoduodenectomy and to demonstrate that acceptable perioperative and long-term outcomes can be achieved by a standardised technique in a high-volume centre.

Follow-Up Studies↗
PubMed2004

[The neurotrophic ulcer of the N. trigeminus].

Trigeminal trophic ulceration is a rare clinical entity after an injury to the sensitive root of the trigeminal nerve, mostly due to therapy for trigeminal neuralgia. Other rare causes are Wallenberg's syndrome or a history of removal of acoustic neuroma. After weeks to years, a slowly progressive ulceration develops due to autonomic dysfunction and the patient manipulation because of serious chronic paresthesia. Finally, in many cases, a significant defect of the nasal arch develops. In spite of typical clinical signs and location, diagnosis is made late in most cases. Reviewing the literature, two cases are presented and diagnostic problems and difficulties of the most effective therapeutic approach are discussed.

Adult↗
PubMed2004

Sialoscopy--initial experiences with a new endoscope.

BACKGROUND: After the introduction of mini-endoscopes for the diagnosis of swelling of the major salivary glands there has been further development of materials and techniques. A new highly flexible semirigid sialoendoscope with high quality imaging (6000 pixels), an outside diameter of 1.1 mm, a working channel of 0.4 mm, and a separate channel for irrigation has been developed and we examined its clinical value. METHODS: We used the endoscope in 22 patients for diagnosis and treatment. RESULTS: Sialoendoscopy was achieved after dilatation of the papilla in all cases. The image (both in contrast and resolution) was excellent. We found sialolithiasis in 13, stenosis in 3, and sialodochitis in 3. Through the working channel we were able to insert instruments with success in seven cases with pathological findings. One patient developed a complication.

Adult↗
PubMed2004

Role of glutamate receptors in nucleus accumbens core and shell in spatial behaviour of rats.

The nucleus accumbens (NAC) is considered to be an important neural interface between corticolimbic and motor systems of the brain. Several studies have shown that the NAC is not only involved in motivation and reward-related processes but also in spatial behavior. We here investigated the involvement of different glutamate receptor subclasses within NAC core and shell subregions on behavior in a radial-maze. Rats were first trained in a four-arm-baited eight-arm radial maze task for baseline performance. Thereafter, the effects of microinjection of the nonselective glutamate receptor antagonist kynurenic acid (4.5 microg), the NMDA receptor antagonist 2-amino-5-phosphonopentanoic acid (1 microg) and the non-NMDA receptor antagonist 6,7-dinitroquinoxaline-2,3-dione (0.75 microg) in NAC core and shell were tested on reference memory errors (RME) and working memory errors (WME). Moreover, the choice pattern of entries and duration of arm-entries were evaluated. Microinjection of all drugs increased RME. Additionally, non-NMDA receptor blockade in NAC shell but not core increased WME. After microinjection of all drugs into NAC core and shell rats preferentially choose the arms next to the previously visited arm. This work shows that glutamate receptors in both NAC subregions are important for spatial behavior. The deficits seen after glutamate receptor blockade may not be working- or reference memory-related but caused by a switch from a memory-dependent allocentric strategy to an egocentric response strategy.

2-Amino-5-phosphonovalerate↗
PubMed2004

Effects of neonatal excitotoxic lesions of the entorhinal cortex on cognitive functions in the adult rat.

The entorhinal cortex (EC) is involved in a variety of cognitive functions by virtue of its neuronal input from the neocortex and projection to the hippocampal formation and the limbic-striatal system. Neonatal lesions are increasingly considered useful models for disconnection syndromes such as schizophrenia. Therefore, we investigated the effects of neonatal EC lesions on adult rat behavior. Neonatal (postnatal day 7) lesions were inflicted by bilateral injections of ibotenate into the EC. Sham-lesioned (vehicle injection) and naive (unoperated) rats served as controls. Locomotor activity was measured in prepubertal and young adult rats. Adult rats were then tested for spatial learning in an eight-arm radial maze (reinforced delayed alternation) and for motivation (progressive ratio schedule of operant behavior). Finally, prepulse inhibition (PPI) of the acoustic startle reflex and locomotor activity were investigated with and without apomorphine (APO) challenge. Brain tissue damage was assessed using Nissl-staining. The total volume of the adult rat EC was reduced after neonatal ibotenate-injection. Neonatal EC-lesions increased perseveration only in a delayed task in the radial maze and induced a leftward-shift of breakpoints in operant responding. Lesions did not alter baseline locomotor activity, but enhanced the locomotor stimulating effect of APO. PPI was not affected by neonatal lesions of the EC with and without APO challenge. Neonatal lesions of the EC impaired the ability to hold information during delays and reduced motivation during operant behavior which reflects a state of anhedonia. Thus, they may serve as an animal model for certain aspects of schizophrenia.

Aging↗
PubMed2004

New (1-deaza)purine derivatives via efficient C-2 nitration of the (1-deaza)purine ring.

Nitration of substituted (1-deaza)purines using a mixture of tetrabutylammonium nitrate (TBAN) and trifluoracetic acid anhydride (TFAA) was applied to prepare nitrosubstituted (1-deaza)purines at low temperature. The nitro group influences the system twofold: 1) it activates other substituents towards nucleophilic aromatic substitution and 2) it can be substituted itself leading to a variety of di-substituted (1-deaza)purines, also via solid phase syntheses. Several of the molecules obtained were studied for their antiprotozoal activity and for interactions with the different human adenosine receptors.

Acetic Anhydrides↗
PubMed2004

Urinary tract infection in men.

OBJECTIVE: To explore the prevalence and microbiology of urinary tract infection (UTI) in symptomatic men in a primary care setting and to determine the appropriateness of patient management of these conditions by the general practitioners. METHODS: A cross-sectional survey was carried out matching documentation of symptoms and management with urine culture and results of susceptibility tests. All patients presenting with symptoms typical for a UTI in 36 teaching general practices in the area of Göttingen, Germany, were eligible for enrolment in the study. 15% (n = 90) of all patients were adult men. General practitioners (GPs) were instructed to manage patients as usual. Patient characteristics, dipstick tests and treatment were matched with results of urine cultures and susceptibility testing. RESULTS: Men presenting with symptoms indicative of UTI were predominantly elderly (median age 61 years) and 41% had additional risk factors. Antibiotics were prescribed for 36%, but these were not well-targeted. Urine culture revealed UTI in 60%, of which half had low colony counts (23% of all patients) or multiple bacterial growth (7%); 40% had sterile urine. Dipstick tests proved unhelpful: leukocytes and nitrite had sensitivities of 54% and 38%, specificities of 55% and 84%, positive predictive values of 65% and 78% and negative predictive values of 44% and 46%, respectively. Resistance levels were 53% for amoxicillin and cefaclor, 28% for cefixim, 22% for ciprofloxacin, 34% for both trimethoprim as individual substance and the combination with sulfamethoxazole (cotrimoxazole) and 25% for nitrofurantoin. CONCLUSION: Men with symptoms indicative of a UTI should not be treated empirically. A urine culture and antibiogram should be obtained before a treatment decision is made. A low-count UTI was common and should not be considered normal.

Adult↗
PubMed2004

Detection of disseminated tumour cells as a potential surrogate-marker for monitoring palliative chemotherapy in colorectal cancer patients.

In a pilot study the effect of palliative chemotherapy on the detection rates of circulating tumour cells in peripheral venous blood of stage IV colorectal cancer patients was investigated. The results indicate a recruitment of tumour cells during chemotherapy and suggest a poorer survival for tumour cell positive patients. Circulating tumour cells have been shown to be a potential prognostic factor in patients who undergo curative resection for colorectal cancer. The effect of chemotherapy on the detection rates of disseminated tumour cells in blood has not yet been adequately investigated. Objective of this pilot-study was to analyze circulating tumour cells in peripheral venous blood of colorectal cancer patients undergoing chemotherapy in order to evaluate its potential value as a surrogate-marker for predicting clinical outcome after chemotherapy. Our hypothesis was that chemotherapy results in a reduction of the detection rates of circulating tumour cells in colorectal cancer patients. Forty-two Stage IV patients were examined at three different time points before and during palliative chemotherapy for the presence of disseminated tumour cells, using a previously described RT-PCR-assay for cytokeratin 20. 80.1% of the patients showed disseminated tumour cells at least once. Before chemotherapy, patients with multi-organ metastases were positive in 62.5%, patients with locally limited disease in only 14.3%. After the first chemotherapy, the detection rates in the latter group increased to 62.5%, for all patients in the same time from 46.3% to 57.5%. Clinical therapy responders showed an increase in the detection rates from 28.5% before to 71.4% after chemotherapy. In contrast, chemotherapy had no effect on tumour cell detection rates of patients with progressive disease (57% before vs. 60% after therapy). Patients with detected circulating tumour cells showed a shorter overall survival than patients without circulating tumour cells (83 vs. 53 weeks). Clinical therapy responders on average lived only 3 weeks longer than non-responders. In contrast to the original hypothesis, our data suggest a recruiting of circulating tumour cells during chemotherapy in advanced colorectal cancer. Further investigations are needed to clarify the potential role of circulating tumour cells for monitoring chemotherapy in these patients.

Antineoplastic Agents↗
PubMed2003

Association analysis of bone mineral density and single nucleotide polymorphisms in two candidate genes on chromosome 1p36.

Two candidate genes for bone mineral density (BMD), tumor necrosis factor alpha receptor 2 (TNFRSF1B) and lysyl hydroxylase (PLOD1), have been scanned for single nucleotide polymorphisms (SNPs) within their coding and promoter regions. These two genes, separated by about 200 kb, are located within the chromosomal interval 1p36.2-1p36.3 that has been linked to femoral neck BMD. In a patient population (n = 104) of European descent, there were four SNPs within TNFRSF1B and six SNPs within PLOD1 that occurred with greater than 5% frequency. There was significant linkage disequilibrium within both genes. Single marker analysis revealed significant association for one SNP located in intron 6 of PLOD1 and lumbar spine BMD (P = 0.01). Allelic haplotypes that encompassed the four SNPs in TNFRSF1B or the six SNPs in PLOD1 were assigned using a Bayesian algorithm as implemented in the program Haplotyper. Association of TNFRSF1B haplotypes with femoral neck BMD was statistically significant (P = 0.01). Similarly, PLOD1 haplotypes demonstrated a statistically significant association with spinal BMD (P = 0.04). These findings strengthen the potential importance of chromosome 1p36.2-1p36.3 in contributing to BMD variation, and are consistent with genetic variation in either PLOD1, TNFRSF1B or nearby genes playing a role in the phenotype.

Antigens, CD↗
PubMed2003

[Treatment of sudden hearing loss through Fibrinogen/LDL-apheresis. A prospective, randomized multicenter trial].

INTRODUCTION: Sudden sensorineural hearing loss (SSHL) is thought to be of various origins. Disturbances of microcirculation, autoimmune pathology and viral infection are among the most likely causes. Acute reduction of plasma fibrinogen and serum LDL positively influences hemorheology and endothelial function and might thus be an effective therapy for SSHL. OBJECTIVE: To test the hypothesis that fibrinogen/LDL-apheresis is as effective or superior to conventional therapy with plasma expanders and prednisolone in the treatment of SSHL. DESIGN: controlled, prospective, randomized, multicenter trial. SETTING AND PATIENTS: 201 patients were recruited from 01/2000 to 6/2001 at the University Clinics of Munich, Berlin, Hamburg and Bochum. Inclusion criteria was sudden sensorineural hearing loss of unknown origin within 6 days of onset. INTERVENTIONS: Single fibrinogen/ LDL-apheresis infusion of prednisolone (250 mg, tapered by 25 mg daily), hydroxyethyl starch (500 ml, 6%) and pentoxifylin (400 mg/day). MAIN OUTCOMES: Improvement of pure tone thresholds 48 h after onset of therapy. RESULTS: Over all improvement of pure tone thresholds in the fibrinogen/ LDL-apheresis treated patients is slightly but not significantly better than in the standard therapy group. After 48 h, 50% speech perception in the fibrinogen/ LDL-apheresis group (21.6+/-20.1 dB) is significantly (p<0.034) better than in the standard group (29.3+/-29.4 dB). Patients with plasma fibrinogen levels of more than 295 mg/dl have a substantial and significantly (p<0.005) better improvement of speech perception (15.3+/-17.3 dB) than standard treated patients (6.1+/-10.4 dB). CONCLUSIONS: Fibrinogen/LDLapheresis is at least equally effective compared to prednisolone treatment in sudden hearing loss. Selected patients with plasma fibrinogen of more than 295 mg/dl improve significantly better when treated with fibrinogen/LDLapheresis.

Adolescent↗