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Biomedical subjects

M Koch

Publications and source records attributed to M Koch.

At least 289 records · Page 16Linked to original sources
PubMed1993

Anatomical studies on the spinal cord segments of the impala (Aepyceros melampus).

The anatomy of the spinal cord segments was studied and recorded for the impala. The root attachment lengths were greatest at C3, T10 and L3 cord segment levels in the respective regions. As to the root emergence length the greatest lengths were observed at C7, T10, L5 and S1 cord segment levels respectively. The interroot interval was longest at C2, T8 and L1 segments respectively. The longest cord segments were C2, T13, L2 and S2 segments. The widest cord segments of their respective regions were C7, T1, L5 and S1 cord segments. As to segment volume C3, T13, L2 and S1 were the most voluminous cord segments in the respective cord regions. Statistical analysis revealed a high correlation among all of the study parameters suggesting a high degree of multicolinearity. Gross anatomical relationships concerning the location of the spinal cord segments with respect to the vertebrae were studied. The cord segments C1, T1-T4 and L1-L3 were within their vertebral limits. In the impala the spinal cord terminated at the midlevel of S4 vertebra.

Animals↗
PubMed1993

Serum lipids predict cardiac death in diabetic patients on maintenance hemodialysis. Results of a prospective study. The German Study Group Diabetes and Uremia.

The objective of this study was to measure cholesterol concentrations in diabetic patients at the beginning of maintenance hemodialysis treatment and to define their role as predictors of subsequent cardiac death on maintenance hemodialysis. The design of this study consisted of a prospective study of all consecutive diabetic patients newly admitted to 28 German dialysis centers between January 1985 and October 1987. The patients were examined on admission and subsequently followed for 45 months on dialysis. This study included 196 patients, 67 type I (43 male, 24 female, median age 49 years, range 22-73) and 129 type II (54 male, 75 female, aged 64 years, range 37-82). Lipids (total cholesterol, triglycerides low-density lipoprotein (LDL) cholesterol high-density lipoprotein (HDL) cholesterol apolipoprotein B and A and anthropometric indices (body mass index, triceps skinfold thickness) were measured. The outcome was death, i.e., cardiovascular (myocardial infarction, sudden death, other cardiac causes, stroke) and noncardiovascular death during a 45-month follow-up. At the start of treatment, total cholesterol, triglycerides LDL cholesterol, LDL/HDL ratio and apolipoprotein B were significantly higher in diabetics than in healthy controls or patients with standard primary renal disease starting dialysis. Only minor differences were found between males and females and type I and type II diabetics. Fourty-three percent of type I and 50% of type II diabetics died, 61% from cardiovascular causes, mostly myocardial infarction (in 40% reinfarction) and sudden death. On admission, diabetics subsequently dying from myocardial infarction had significantly higher median cholesterol than survivors, i.e., 259 versus 222 mg/dl, and higher LDL cholesterol, LDL/HDL ratio and apolipoprotein B.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

[Measuring plantar pressure in conventional shoes with the TEKSCAN sensory system].

This article describes the assessment of the TEKSCAN pressure monitoring system used in association with normal footwear. After allowing a warm-up period of 5-10 minutes inside the shoe the stability of the sensor output improved as compared with the falsely higher pressures recorded when the warm-up period was not observed. The intra-person coefficient of variation of a single sensor was < 23%, and the intersensor variation was < 31%. However, intrasensor variation was reduced to 15% by appropriate prior preparation. Neither repeated use (< 6 times) of a sensor in a single shoe, nor the use of a single sensor in several different shoes had any effect on sensor function. Active deformation of the sensor resulted in so significant signal.

Adolescent↗
PubMed1993

[Triangular or rectangular rehabilitation after myocardial infarction. Comparative study by drawing of lots evaluating performance and respiratory gas exchange].

Triangular and rectangular rehabilitation techniques were assessed by comparative exercise performance and respiratory evaluation in twenty six phase II post-myocardial infarction patients. Patients all performed a standard exercise test with measurement of VO2, before and after 40 rehabilitation sessions. Clinical, exercise and ventilatory parameters were identical in the two groups before rehabilitation (triangular--n = 13; rectangular--n = 13). Exercise capacity was increased by 18% and 19% respectively after rehabilitation. Maximum aerobic capacity nevertheless remained unchanged (27.6 +/- 7.1 before; 28.3 +/- 6.7 ml/kg/min after) in all patients. Analysis of variance failed to reveal superiority of one of the two rehabilitation techniques over the other.

Humans↗
PubMed1992

A major oligomeric fibroblast proteoglycan identified as a novel large form of type-XII collagen.

Cultured chick embryo skin fibroblasts release a major component with a native molecular mass of about 1 MDa, which resolves into three polypeptide bands of about 300, 350 and 600 kDa upon reduction. We report here the purification of this oligomeric protein and show, by means of polyclonal and monoclonal antibodies, that its three polypeptide constituents are closely related. The 600-kDa polypeptide is likely to be a dimer of two smaller subunits which are cross-linked by non-reducible bonds. By electron microscopy, isolated oligomeric molecules exhibit a novel cruciform structure with a large central globular domain. One arm has the shape of a thin rod about 70 nm in length. The three other arms are thicker, longer (90 nm) and flexible, and carry a prominent double globule at their distal ends. Collagenase treatment of the oligomeric fibroblast protein yields two resistant fragments of about 270 kDa and 320 kDa. The intact 350-kDa and 600-kDa (but not the 300-kDa) polypeptides are chondroitinase sensitive and labeled by metabolic incorporation of [35S]sulfate; collagenase treatment does not remove any [35S] sulfate. Hence, the intact fibroblast protein has glycosaminoglycan chains attached to its non-collagenous domain. Three amino acid sequences obtained from chymotryptic fragments of the fibroblast protein correspond to sequences predicted for chick type-XII collagen from its full-length cDNA [Yamagata, M., Yamada, K. M., Yamada, S. S., Shinomura, T., Tanaka, H., Nishida, Y., Obara, M. & Kimata, K. (1991) J. Cell Biol. 115, 209-221]. However, the novel fibroblast protein described here differs significantly from previously isolated forms of type-XII collagen: its subunits are larger by one third, and it is a proteoglycan.

Amino Acid Sequence↗
PubMed1992

Na(+)-dependent HCO3- transport and Na+/H+ exchange regulate pHi in human ciliary muscle cells.

We investigated intracellular pH (pHi) regulation in cultured human ciliary muscle cells by means of the pH-sensitive absorbance of 5(and 6)-carboxy-4',5'-dimethylfluorescein (CDMF). The steady-state pHi was 7.09 +/- 0.04 (n = 12) in CO2/HCO3(-)-buffered and 6.86 +/- 0.03 (n = 12) in HEPES-buffered solution. Removal of extracellular sodium for 6 min acidified the cells by 1.11 +/- 0.06 pH units (n = 12) in the presence of CO2/HCO3- and by 0.91 +/- 0.05 pH units (n = 8) in its absence. Readdition of external sodium resulted in a rapid pHi recovery, which was almost completely amiloride-sensitive in the absence of CO2/HCO3- but only slightly influenced by amiloride in its presence. Application of DIDS under steady-state conditions significantly acidified the ciliary muscle cells by 0.25 +/- 0.02 (n = 4) in 6 min, while amiloride had no effect. The pHi recovery after an intracellular acid load was completely dependent on extracellular sodium. In HEPES-buffered solution the pHi recovery was almost completely mediated by Na+/H+ exchange, since it was blocked by amiloride (1 mmol/liter). In contrast, a marked amiloride-insensitive pHi recovery was observed in CO2/HCO3(-)-buffered solution which was mediated by chloride-independent and chloride-dependent Na+ HCO3- cotransport. This recovery, inhibited by DIDS (0.2 mmol/liter), was also observed if the cells were preincubated in chloride-free solution for 4 hr. Analysis of the sodium dependence of the pHi recovery after NH4Cl prepulse revealed Vmax = 0.57 pH units/min, Km = 39.7 mmol/liter extracellular sodium for the amiloride-sensitive component and Vmax = 0.19 pH units/min, Km = 14.3 mmol/liter extracellular sodium for the amiloride-insensitive component. We conclude that Na+/H+ exchange and chloride-independent and chloride-dependent Na(+)-HCO3- cotransport are involved in the pHi regulation of cultured human ciliary muscle cells.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1992

Chemosensitivity of human MCF-7 breast cancer cells to diastereoisomeric diaqua(1,2-diphenylethylenediamine) platinum(II) sulfates and specific platinum accumulation.

Cisplatin, raceme-diaqua[1,2-bis(4-fluorophenyl)ethylenediamine]platinu m(II) sulfate (compound I), meso-diaqua[1,2-bis(4-fluorophenyl)ethylenediamine]-platinum(II) sulfate (compound II), and meso-diaqua[1,2-bis(2,6-dichloro-4- hydroxyphenyl)ethylenediamine]platinum(II) sulfate (compound III) were compared with regard to their effect on the MCF-7 breast cancer cell line in vitro. At equimolar concentrations (5 microM), cisplatin, compound I, and compound II were equiactive after 231 h drug exposure, whereas compound III was ineffective. Although compounds I and II showed markedly greater inactivation than did cisplatin after 6 h incubation with culture medium, compound I (but not compound II) exhibited antitumor activity equivalent to that of cisplatin when cells were exposed to the drugs for 6 h. Platinum measurements by neutron-activation analysis revealed that compound I was selectively and rapidly accumulated by MCF-7 cells, resulting in a high degree of DNA platination within the first few hours of drug exposure. However, when the drug-exposure period was long enough, platinum enrichment was not reflected in an overall difference in the cytotoxicity of compound I vs cisplatin. Nevertheless, compound I should be superior to cisplatin in vivo, provided that effective plasma levels can be maintained for about 6 h.

Breast Neoplasms↗
PubMed1992

Loss of the acoustic startle response following neurotoxic lesions of the caudal pontine reticular formation: possible role of giant neurons.

The effect of the excitotoxic N-methyl-D-aspartate agonist quinolinic acid in the caudal pontine reticular formation on the acoustic startle response was investigated in rats. Bilateral injections of 90 nmol of quinolinic acid led to large lesions in the reticular formation characterized by the loss of all neurons and a marked reduction or even abolition of the acoustic startle response; 18 nmol of quinolinic acid led to smaller lesions characterized by a selective loss of giant neurons within the caudal pontine reticular formation and a reduction of the startle amplitude. The partial correlation analysis revealed that the reduction of the amplitude of the acoustic startle response can be correlated with the loss of the giant neurons (r = 0.575; d.f. = 29; P less than 0.001) but not with the reduction of the number of all neurons (r = 0.207; d.f. = 29; P greater than 0.2) in the caudal pontine reticular formation. These findings were reconciled with electrophysiological and anatomical data indicating that the giant neurons in the caudal pontine reticular formation receive acoustic input and project to motoneurons of the spinal cord. It is concluded that the caudal pontine reticular formation is an important element of the startle pathway and that the giant reticulospinal neurons constitute an important part of the sensorimotor interface mediating this response.

Acoustic Stimulation↗
PubMed1992

Glutamate receptors mediate acoustic input to the reticular brain stem.

Previous studies have shown that many neurons of the pontine reticular brain stem respond to acoustic stimulation. However, it was not clear which neurotransmitter is involved in the mediation of auditory information. As glutamate appears to be a prominent transmitter in the auditory system, we iontophoretically applied antagonists of the AMPA/kainate- and NMDA-receptors to reticular neurons. Both glutamate antagonists reduced the acoustically evoked response, with the AMPA/kainate-receptor antagonist being more efficient. As the neurons showed a short latency and a high intensity threshold to the acoustic stimuli and most of them appeared to project into the spinal cord, we conclude that glutamate receptors on reticulospinal pontine brain stem neurons probably mediate auditory short-latency behaviour, such as the startle response.

2-Amino-5-phosphonovalerate↗
PubMed1992

Microbic superinfection in relapse of inflammatory bowel disease.

To assess the association between symptomatic relapse of inflammatory bowel disease (IBD) and superinfection with enteropathogenic microorganisms, we determined prospectively the incidence of infections with enteropathogenic bacteria, protozoa, and helminths in patients with confirmed longstanding IBD. Sixty-four patients with IBD (49 with Crohn's disease [CD] and 15 with ulcerative colitis [UC]) were consecutively enrolled in the study when relapse occurred. Multiple biopsies for histological and microbiological investigations were taken from all patients who were evaluated by colonoscopy. Parallel stool specimens were investigated for the presence of enteropathogenic bacteria, protozoa, and helminths. In six patients, we detected Clostridium difficile or toxin B (five CD, one UC), in one patient Campylobacter jejuni (CD), and in another patient Salmonella typhimurium (UC). Enteropathogenic Escherichia coli were isolated from three patients. Investigation of biopsies for Mycobacteria, microscopic examination of stool samples for helminths, and immunofluorescence for chlamydia were negative in all patients. In summary, as we found enteropathogenic microorganisms so infrequently in patients with relapse of IBD, despite intensive microbiological screening by tissue sampling for detection of gut adherent bacteria, we believe that microorganisms play only a minor role in the exacerbation of IBD.

Adult↗
PubMed1992

The prevalence of cerebral damage varies with migraine type: a MRI study.

Studies on the prevalence of MRI signal abnormalities in the brains of migraineurs have yielded controversial results. In order to provide further data on this issue we reviewed the MRI scans of 38 migraine patients without current neurologic symptoms (mean age 35.8 +/- 11.9 years). In addition, we compared the findings in those 24 migraineurs under 50 years without major cerebrovascular risk factors (mean age 30.1 +/- 9.0 years) to that in 14 headache and risk factor free volunteers (mean age 37.8 +/- 5.3 years). Overall, focal areas of hyperintense signal were seen in 15 (39%) patients. They were present on both proton density and T2-weighted spin-echo sequences. Lesion prevalence varied according to the type of headache (18% in migraine without aura, 53% in migraine with typical aura, 38% in basilar migraine). The subset of migraine patients under 50 years exhibited MRI signal abnormalities more than twice as often as controls (33% vs. 14%). Punctate white matter hyperintensities were the predominant finding and were seen in 10 of 15 individuals with MRI lesions. More striking signal abnormalities consisted of symmetrical areas of hyperintensity lateral to the posterior horns in two 24 year old patients and of extensive white matter damage with lacunar infarcts in a 59 year old woman. Our findings confirm a higher prevalence of MRI lesions in a mixed group of migraineurs than in headache free individuals. Signal abnormalities are most often non-specific, however their occurrence relates to the type of migraine.

Adolescent↗
PubMed1992

The benefit of graded physical exercise in chronic heart failure.

A new program of rehabilitation is less demanding on cardiac output than standard programs. Twenty-five patients with chronic heart failure (ejection fraction [EF]: 0.26 +/- 0.10) were randomized into 2 groups: a control group with 13 patients and a rehabilitation group of 12 patients. In the control group, 2 did not complete the study (cancer, cardiac transplantation). For the 11 others, the different parameters studied were comparable at day 0 with group R and did not significantly change over 3 months outside of a spontaneous improvement in endurance performance by 22%. In the rehabilitation group (40 sessions over 90 days; specialized equipment) there were no incidents. Tolerance was excellent (heart rate during sessions less than 115 bpm) and all functional parameters improved. Training did not modify the isotopic ejection fraction. The quality of life score increased respectively by 52% (p less than 0.0001 in comparison with the control group) and by 63% (p less than 0.0001); 80% of the patients requested that training be prolonged. The functional improvement obtained by purely peripheral effect had no adverse effect on the heart.

Chronic Disease↗
PubMed1992

[Main anticancer substances of vegetable origin].

During the last thirty years, the systematic screening of thousands of vegetal extracts has led to the isolation of numerous antitumor agents which belong to various chemical series. This paper only deals with some of them which are either of current clinical use or under advanced clinical experimentation, e.g., ellipticine, homoharringtonine, camptothecine, acronycine and their derivatives. The origin, the biological activity and its mechanism, and the toxicity of each of these alkaloids are described. These examples highlight the interest of the Plant Kingdom as source of biologically active new structures and the importance of a good knowledge of the mechanism of the activity and toxicity of active components. This knowledge gives a rational basis to prepare compounds of increased activity or reduced toxicity and to use them at their best in therapeutic.

Acronine↗
PubMed1992

Efficacy of rifaximin on symptoms of uncomplicated diverticular disease of the colon. A pilot multicentre open trial. Diverticular Disease Study Group.

Diverticular disease of the colon is a common health problem in western societies. Most patients with colonic diverticula are asymptomatic; it has been estimated that only 20% of individuals harboring diverticula will develop symptoms and signs of illness and a minority will develop major complications. Although the efficacy of a high fiber diet in the management of symptomatic uncomplicated diverticular disease is still controversial, bran and bulking agents are commonly used. Antibiotics are used to treat major inflammatory complications of diverticular disease but apparently there is no rationale for the use of antibiotics in uncomplicated disease where an inflammatory component is by definition excluded. In a multicenter open trial, 217 patients with symptomatic uncomplicated diverticular disease were treated with glucomannan (110 pts) or with glucomannan plus a poorly absorbable antibiotic (rifaximin 400 mg bid for 7 days each month) (107 pts). Clinical evaluation was performed bimonthly for 12 months using a global score system for 8 clinical variables. After 12 months, patients treated with glucomannan plus rifaximin showed a 63.9% reduction of the score as compared to 47.6% in patients treated with glucomannan only (p < 0.001). Cyclic administration of rifaximin appears to be of some advantage in obtaining symptomatic relief in uncomplicated diverticular disease.

Abdominal Pain↗
PubMed1992

[Relative value of attenuation and negativation of systolic pulmonary venous flow in severe mitral insufficiency. Transesophageal echocardiographic study].

The aim of this study was to analyse the velocity profile of the systolic fraction of the pulmonary venous flow (PVF) in mitral regurgitation (MR). Three velocity profiles were identified in left superior pulmonary vein. Inversion of the systolic fraction of the PVF was specific for angiographic grade 4 MR (specificity 97%, sensitivity 100%). On the other hand, a decrease in this wave is much less specific for mild MR and depends on severe factors such as left atrial pressure, size and ejection fraction and the lack of atrial systole (as in atrial fibrillation or atrioventricular block). Therefore, inversion of PVF has a good positive predictive value for severe MR, but the interpretation of attenuation of this wave should take into consideration not only the MR but also left atrial pressure and compliance.

Blood Flow Velocity↗