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Biomedical subjects

M Koch

Publications and source records attributed to M Koch.

At least 325 records · Page 18Linked to original sources
PubMed1991

Magnetic resonance angiography in the abdomen and pelvis.

Magnetic resonance angiography of the abdomen, pelvis, and lower extremities is still under clinical investigation. This article represents a short review of the current literature in the subject, with emphasis on newer imaging techniques such as two-dimensional and three-dimensional gradient-echo pulse sequences, their current and future clinical applications, and their practical limitations. If the preliminary results hold up, MR angiography may become a standard tool for the evaluation of vascular disorders such as portal hypertension and renal artery stenosis, particularly in conjunction with quantitative measurements of blood flow. The published results making use of MR angiography either alone or in combination with quantitative MR flow measurements in the aorta, the portal system, and in femoral and iliac artery disease are very promising indeed. However, the studies published still comprise a very limited number of patients, and there is a paucity of well-controlled clinical studies applying standardized techniques to a large number of subjects.

Abdomen↗
PubMed1991

[Computerized analysis of ST segment during exercise. Interpretation of "saw tooth" appearance].

The authors report original appearances (sinusoid or "saw tooth" aspect) of computerised analysis of the ST segment in 3 cases, corresponding to ST changes during exercise stress testing. This is due to alternating ST elevation and depression probably related to abnormal vasomotor tone given the fact that the recording was normalised by coronary vasodilator therapy.

Angina Pectoris, Variant↗
PubMed1991

[Thrombosis of mechanical heart valve prosthesis. Value of transesophageal echocardiography in the study of mitral valve prosthesis].

Forty-three consecutive patients with mechanical valve prostheses underwent transthoracic and transoesophageal echocardiography for suspected thrombolic prosthetic valve dysfunction. The results of these investigations were compared with those of cineradiography and the clinical outcome. The diagnosis of thrombosis was retained in 11 of the 43 patients (10 mitral and 1 aortic valve prostheses). The transthoracic Doppler echo was clearly abnormal in 6 of the 11 cases. Transoesophageal echo was of essential value in all cases but one, showing abnormal movement of the mobile element and/or a paraprosthetic thrombus. The cineradiography gave false negative results in 6 cases. In conclusion, these cases underline the undeniable value of transoesophageal echocardiography in occlusive or non-occlusive thrombosis of a mitral valve prosthesis. This investigation should be undertaken whenever there is the least suspicion of thrombosis of the prosthesis.

Adult↗
PubMed1991

[Brucella endocarditis of bicuspid aortic valve. Surgical treatment with successful result].

The authors report a case of Brucella Melitensis endocarditis of a bicuspid aortic valve which caused rapid progression of the hemodynamic signs of aortic stenosis, and was associated with a para-aortic abscess and a pericardial effusion. Surgery resulted in correction of the hemodynamic abnormalities and cured the infection: the results were sustained 10 months after operation. This case illustrates the precision of the Doppler, echocardiographic diagnosis of the lesions, which was confirmed at surgery so that potentially dangerous cardiac catheterisation could be avoided.

Adult↗
PubMed1990

Comparison of kinetic parameters for acetylthiocholine, soman, ketamine and fasciculin towards acetylcholinesterase in liposomes and in solution.

Purified acetylcholinesterase from bovine brain was reconstituted by a detergent depletion technique into liposomes, prepared from soybean lecithin. The kinetics for the substrate acetylthiocholine and for three inhibitors with very different binding properties was studied. The results were compared with results from corresponding experiments with solubilized enzyme in detergent solution. The reconstituted enzyme showed a higher affinity for acetylthiocholine, ketamine and fasciculin. Parameters unaffected by the reconstitution were: turnover number for the substrate; the non-competitive component in ketamine inhibition and the kinetics for the active site-directed irreversible inhibitor soman.

Acetylcholinesterase↗
PubMed1990

Clonally restricted insulin autoantibodies in a cohort of 2200 healthy blood donors.

Serum samples of 2200 blood donors were screened for anti-insulin IgG by enzyme-linked immunosorbent assay. Specificity of detected antibodies was verified by competition with an excess of insulin and observation that saturated anti-insulin IgG were no longer measurable. The upper limit of measured signal in the population was defined as the mean plus three SD. In the direct assay, 32 sera were positive. Among these, 22 (1%) contained saturable insulin antibodies (true positive) and 10 were non-saturable and considered as non-insulin-specific. The positive blood donors were requested to answer a questionnaire and according to their answers, none had ever received insulin, was a first degree relative of a Type 1 (insulin-dependent) diabetic patient or had experienced a hypoglycaemic episode. None of the 22 true positive sera detected by enzyme-immunosorbent assay bound 125-I-insulin to any significant extent. The nine sera yielding the highest signal were further characterized with regard to heavy and light chains as well as species specificity of ligand. Anti-insulin IgG from healthy blood donors contained only one heavy (gamma 1 2/9;gamma 3 7/9) and one light (kappa 8/9); lambda 1/9) chain. Three sera were human insulin specific; two were non-species-specific; the other four bound insulin in the order human = porcine greater than bovine. These results indicate that low affinity clonally restricted antibodies against insulin are present in unselected blood donors with a prevalence of 1%.

Adult↗
PubMed1990

Clinical evaluation of serum N-acetyl-beta-D-glucosaminidase as a liver function test.

Serum N-acetyl-beta-D-glucosaminidase has been shown to be a sensitive indicator of liver function. The enzyme activity in serum from patients with different forms of hepatic disease was found to be elevated. A comparison is also made with routine liver parameters. The frequencies of pathological serum levels of the routine measurements made are in relatively good agreement with earlier reports.

Acetylglucosaminidase↗
PubMed1990

Synthesis and biological evaluation of 14-alkoxymorphinans. 3. Extensive study on cyprodime-related compounds.

A series of cyprodime-related compounds (2, 4-12, and 26) has been synthesized and evaluated for opioid agonist and antagonist activity with the mouse vas deferens and guinea pig ileum preparations. None of the changes to cyprodime, including the introduction of a 3-OMe group, increasing and decreasing the size of or completely removing the substituent in position 4, replacing the N-cyclopropylmethyl group with an N-allyl group, or replacing the 14-OMe with an 14-OEt substituent, resulted in an improved mu antagonist profile and most were detrimental either in terms of mu selectivity and potency or increased agonist activity. Increasing the length of the substituent in position 4 resulted in a compound (6a) with a very similar profile to that of cyprodime.

Animals↗
PubMed1990

Cortical, hippocampal, and striatal mediation of schedule-induced behaviors.

The sequential occurrence of licking, locomotor activity, entries into the food magazine (panel pressing), and nonreenforced lever pressing engendered by a periodic schedule of food presentation were measured in each 60-s interreenforcement interval in normal and brain-damaged rats. The development of these responses was measured over 20 days in different groups of food-deprived rats that had received aspirations of the hippocampus, small lesions of the cortex overlying the hippocampus (hippocampal-operated control group), decortication, or 6-hydroxy-dopamine lesions of the caudate nucleus or nucleus accumbens. All lesions produced distinctive patterns of change in the measured behaviors, and dissociations as well as similarities in their effects were evident. These results are discussed with respect to dissociations in the motor and motivational effects of the various lesions and in terms of contemporary hypotheses of schedule-induced behavior.

Animals↗
PubMed1990

Follow-up of controls participating in case-control studies for cancer risk factors.

Case-control studies have been carried out in Alberta in the last seven years to investigate possible risk factors for cancer of the prostate, skin and ovary. For each study, controls were randomly selected from an age- and sex-matched population. The information obtained from each control that agreed to participate in each study (n = 1236) included name, sex, date of birth, address and date of participation as well as the specific questions for each study. A review of these controls was carried out in 1988 by checking the number of deaths through death certificate listings from Vital Statistics (n = 142) and cancer incidence through the population-based Alberta Cancer Registry (n = 134). Of the 619 controls interviewed for the prostate cancer case control study in 1982 and 1983, 25 have been diagnosed with cancer of the prostate. From the non-melanoma skin cancer study, 15 cases from the 409 controls interviewed in 1983-1984 have been diagnosed with non-melanoma skin cancer. As for the 208 controls for ovarian cancer interviewed in 1985-1986 no new cases have been diagnosed. This possible ascertainment bias should be taken under consideration when case-control study analyses are carried out.

Alberta↗
PubMed1990

Effects of treatment with estradiol and parental experience on the number and distribution of estrogen-binding neurons in the ovariectomized mouse brain.

The effects of a treatment with estradiol benzoate alone (EB, for 2 weeks) and combined with parental experience (for 5 days) on the number and regional distribution of estrogen receptor-containing cells (ER+ cells) in the brain of ovariectomized mice were studied using an immunocytochemical staining technique. Treatment with EB alone significantly reduces the average density of ER+ cells (labeled cells/mm3) in the ventromedial hypothalamic nucleus (VMH) and in the anterior hypothalamic area (AHA). Parental experience of EB-treated females (achieved by co-caring for 12 pups together with the mother for 5 days), however, leads to a significant increase in the absolute number and relative density of ER+ cells in the VMH. Moreover, ER+ cells are found in the entorhinal and piriform cortex in experienced females only. Generally, a trend of decrease in both the number and density of labeled cells is observed after EB treatment in all regions of the brain where immunostaining is observed in ovariectomized mice (amygdaloid and hypothalamic nuclei, preoptic area), whereas an increase in the above quantitative variables is found in experienced females. The hypothesis is put forward that olfactory cues from the young, experienced during the co-caring period promote the increase in ER+ cells in the above brain regions, which all receive input from the olfactory and/or vomeronasal systems.

Animals↗