Biomedical subjects

H Hecker

Publications and source records attributed to H Hecker.

At least 109 records · Page 6Linked to original sources

PubMed1989

Instability of the nuclear chromatin of procyclic Trypanosoma brucei brucei.

Digestion of nuclear chromatin of Trypanosoma brucei brucei procyclic culture forms with micrococcal nuclease yielded DNA fragments which formed DNA ladders in agarose gels, similar to those of rat liver. However, the chromatin of trypanosomes was digested more rapidly. The digestion of T. b. brucei chromatin yielded a large amount of DNA fragments of core-particle size. The numbers of base pairs per nucleosomal and linker DNA were identical in both species, if the digestion conditions were reduced in the case of T. b. brucei. Psoralen cross-linking of soluble chromatin of trypanosomes at 5 mM salt at pH 7 or pH 10 resulted in an irregular array of single-stranded (ss) bubbles separated by variable stretches of double-stranded (ds) DNA. The proportion of ss DNA was low compared with the ratio of ss/ds stretches in rat liver chromatin, which also showed regularly arranged nucleosomal DNA. Soluble chromatin of T. b. brucei, pre-treated with 500 mM NaCl to remove a potential H1 and psoralen cross-linked at 5 mM salt at pH 7 or pH 10 was to a great extent ds in both situations. The true nucleosome filament organization of T. b. brucei chromatin could only be shown by psoralen cross-linking the DNA in whole nuclei under physiological conditions. The results indicate that the chromatin of procyclic T. b. brucei differs significantly in its compaction pattern from rat liver chromatin; a typical histone H1 is not found, and the DNA-protein interactions are also less stable and can more easily be destabilized by experimental conditions.

Animals↗

PubMed1989

Coronary vasodilation with dihydropyridines--a pharmacokinetic study.

In 26 patients with coronary artery disease, the mean diameters of angiographically 'normal' epicardial coronary arteries were assessed with the aid of a computer-assisted contour detection system (CAAS) before and up to 15 min after onset of a 4-min intravenous-infusion of 2 mg nifedipine (13 patients, group I) or 1 mg nisoldipine (13 patients, group II). Maximal coronary dilation amounted to 20 +/- 9% (4th min) in group I and to 18 +/- 9% (15th min) in group II. In addition, in group II changes of the minimal diameters of 9 coronary obstructions were measured; the maximum increase averaged 28 +/- 15% (7th min). In order to compare the pharmacokinetic properties of these compounds the dilation of the 'normal' coronary segments was correlated with the respective drug plasma levels; maximal plasma concentrations averaged 62 +/- 21 ng ml-1 (7th min) in group I and 17 +/- 7 ng ml-1 (4th min) in group II respectively. A positive, linear correlation between coronary dilation and plasma levels was only found with nifedipine (P less than 0.05); with nisoldipine, however, coronary dilation developed in form of a hysteresis curve, when plotted against plasma levels, probably due to the high receptor affinity of this substance. The prolonged efficacy of nisoldipine could be favourable in oral long-term treatment of patients with coronary artery disease.

Adult↗

PubMed1989

Influence of ionic and non-ionic radiographic contrast media on the vasomotor tone of epicardial coronary arteries.

The effect of ionic and non-ionic contrast media on the vasomotility of epicardial coronary arteries was investigated in 21 patients during coronary angiography by use of either diatrizoate-76% (10 patients, group A) or iopromide-370 (11 patients, group B). Coronary angiograms were taken in RAO 30 degrees projection before (= reference) and directly after (t0) diagnostic angiography of the left coronary artery (approx. 7 dye injections in approx. 7 min). Additional angiograms in the same projection followed after 1, 3, 6 and 10 min. Mean diameters of angiographically normal coronary segments were analysed with an automatic edge detection system (CAAS). With diatrizoate-76% coronary dilation at t0 averaged 18.9 +/- 6.7% (P less than 0.001); it correlated positively (P less than 0.001) with the number of diagnostic injections performed per min (mean 1.2 +/- 0.3 min-1), and negatively (P less than 0.5) with the time interval between the last diagnostic contrast injection and t0 (mean interval 73 +/- 35 s). Coronary dilation was unchanged 1 min after t0 (18.3 +/- 5.4%, P less than 0.001) and was still present after 6 min (6.2 +/- 4.6%, P less than 0.01). With iopromide-370 coronary dilation at t0 was mild (5.4 +/- 4.3%; P less than 0.05); the subsequent injections led to minimal insignificant dilation. It is concluded that in quantitative angiographic studies on changes in coronary vasomotor tone repeated coronary angiograms should be taken with non-ionic contrast media; furthermore adequate injection intervals of greater than 3 min should be observed.

Adult↗

PubMed1989

Coronary vasodilation with nitrocompounds--is there a maximum?

The maximal extent of the dilation of epicardial coronary arteries attainable with nitro-compounds was investigated in 12 patients with coronary artery disease. Before and 5, 10, 15, 19, 60 and 64 min after onset of a 4-min-intravenous infusion of 0.025 mg SIN-1/kg bodyweight coronary angiograms were performed in identical projection; simultaneously, the mean pulmonary wedge pressure (PWP) was measured. At 15 and 60 min, 0.8 mg nitroglycerin (NTG) were additionally administered as sublingual spray. Mean diameters of angiographically normal coronary segments were analyzed with the computer-assisted contour detection system CAAS; they increased by an average maximum of 29 +/- 5% prior to NTG (p less than 0.001). PWP decreased from 9.2 +/- 3.1 mmHg to an average minimum of 4.3 +/- 1.6 mmHg (p less than 0.01) prior to NTG. Neither of these SIN-1-effects was significantly augmented by additional NTG: at 19 min coronary dilation amounted to 28 +/- 7% (p less than 0.001), PWP to 3.9 +/- 1.0 mmHg (p less than 0.01). At 60 min coronary dilation still amounted to 24 +/- 8% (p less than 0.001), PWP to 6.2 +/- 2.5 mmHg (p less than 0.05). By the second administration of NTG the maximal effects attained before could be reproduced: coronary dilation 28 +/- 8% (p less than 0.001), PWP 4.6 +/- 2.2 mmHg (p less than 0.01). Thus, the dilation reserve of epicardial coronary arteries for nitrocompounds is approximately 30% on average. These results suggest the possibility of a reproducible maximal activation of the enzyme guanylate cyclase which seems to be the mediator of the nitro-compound-induced vasodilation.

Administration, Sublingual↗

PubMed1989

Correlation between isosorbide dinitrate plasma levels and coronary vasodilation after chewing capsules.

In 10 patients with coronary artery disease coronary angiograms were performed in identical projections before and 5, 10 and 15 min after sublingual administration of two chewing capsules with 5 mg of isosorbide dinitrate (ISDN) each. Simultaneously, blood samples were taken for gas-chromatographical determination of nitrate plasma levels. The average ISDN plasma levels amounted to 138 +/- 73 ng/ml, 102 +/- 76 ng/ml and 62 +/- 34 ng/ml in the fifth, tenth and fifteenth min, resp. In the fifteenth min significant isosorbide mononitrate plasma levels (greater than 70 ng/ml) were found only in three patients. Mean diameters of angiographically normal coronary segments were measured with the automatic edge detection system CAAS; they increased by an average of 20 +/- 10%, 26 +/- 11%, and 27 +/- 13% (p less than 0.001) in the fifth, tenth and fifteenth min, resp. Due to hysteresis of the coronary dilation in relation to ISDN plasma levels no significant correlation was found between these parameters. The minimal diameters of seven of 10 coronary stenoses analyzed in seven patients reacted with a maximal increase of 23%-98%. Thus, ISDN chewing capsules may be preferable for rapid and prolonged relief of anginal attacks as well as for potent dilation of epicardial coronary arteries as desired during angiography.

Administration, Sublingual↗

PubMed1989

Drug plasma levels and coronary vasodilation after isosorbide dinitrate chewing capsules.

Five, ten and fifteen min after sublingual administration of 10mg isosorbide dinitrate (ISDN) in chewing capsules, in 10 patients with coronary artery disease, ISDN plasma levels were correlated with the dilation of epicardial coronary arteries as well as with changes in aortic blood pressure and heart rate. Due to the rapid and extensive drug absorption, maximal ISDN plasma levels averaged 138 +/- 73 ng ml-1 and were already obtained after 5 min; they declined to 102 +/- 76 and 62 +/- 34 ng ml-1 in the 10th and 15th min respectively. In 7 patients isosorbide mononitrate plasma levels were still negligibly low (less than 30 ng ml-1). Mean diameters of 'normal' coronary segments increased by an average of 20 +/- 10%, 26 +/- 11% and 27 +/- 13% (P less than 0.001) at 5, 10 and 15 min respectively compared to control. The maximal drop in systolic aortic pressure (147 +/- 19 to 115 +/- 15 mmHg; P less than 0.01) as well as the maximal increase in heart rate (66 +/- 4 to 80 +/- 11 beats min-1; P less than 0.01) were observed in the 15th min; diastolic aortic pressure and double product remained constant. Due to the long persistence of coronary dilation and haemodynamic changes, none of these drug effects correlated significantly with the ISDN plasma levels. In addition, the minimal diameters of 10 coronary stenoses were measured in 7 patients; with ISDN 7 stenoses showed dilation ranging from 23% to 98%.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Sublingual↗

PubMed1989

[Computer-assisted geometric measuring technic in coronary angiography interval studies: results of initial angiograms of the International Nifedipine Trial of Anti-atherosclerotic Therapy (INTACT) study].

In 396 of 423 (93.6%) patients with mild to moderate coronary artery disease participating in a coronary angiographic follow-up trial, diameters of the epicardial coronary arteries were measured with an automatic contour detection system (CAAS). The underlying INTACT study (International Nifedipine Trial on Antiatherosclerotic Therapy), a prospective, placebo-controlled, randomized, double-blind multicenter trial, investigates the influence of the calcium antagonist nifedipine (80 mg/day) on the progression of coronary atherosclerosis over a three-year interval. The study is based on coronary angiograms repeated in identical projections after premedication with 10 mg isosorbide dinitrate sublingually. For quantitative analysis the coronary artery system was, in consideration of all anatomical variations, subdivided into 25 segments. In the first angiograms of the 396 patients evaluated up to April 1, 1988, altogether 5,425 different coronary segments could be analyzed over their entire length in one or more angiographic projections--on the average 13.7 +/- 2.8 segments per patient. Analysis parameters were the mean diameters of the entire segments and of the individual subsegments (about 5 mm in length). The 10 major proximal segments could be evaluated in 76-94% of patients respectively in more than two different angiographic projections on the average; in 0-13% of patients the respective segments were occluded. In 1-4% of patients the evaluation of these segments was prevented by poor film quality and in 1-16% of patients prevented by anatomical abnormalities (e.g., segment too short or too small). 184 segments were found occluded (RCA 42%, LAD 30%, CX 28%) and 909 mostly low-grade to moderate stenoses (RCA 34%, CX 32%, LAD 30%, left main 4%) were analyzed with a special algorithm. The following obstruction parameters were derived: minimal diameter, percentage severity, length, and plaque area. The present data demonstrate that in an angiographical multicenter follow-up study such as INTACT a nearly complete quantitative morphometric analysis of the visualized coronary artery system can indeed be obtained in virtually all angiograms when a computer-assisted contour detection system is applied.

Clinical Trials as Topic↗

PubMed1988

Clinical application of quantitative coronary angiography using the CAAS system: preliminary results of the INTACT study (International Nifedipine Trial on Antiatherosclerotic Therapy).

It is the objective of the INTACT-study to test in man, whether a significant retardation of the progression of coronary artery disease is attainable with the Ca-antagonist nifedipine; this may be possible on the basis of numerous animal experiments. INTACT is a prospective, randomized, double blind, placebo controlled investigation in 423 patients with preferably early stages of coronary sclerosis in whom a progression of the disease seems likely. A proper coronary angiogram led to inclusion of the patients in the study (October 1983-June 1985). Over the following 3-years-period patients received either nifedipine 80 mg/day or placebo. The study is concluded by a control coronary angiogram with angiographic projections which are identical to those of the first coronary angiography. The extent of coronary sclerosis is objectivated by computer-assisted quantitative measurement of the entire coronary arterial system with the CAAS-system (Rotterdam). For definition purposes the coronary artery system subdivided into 25 segments. Parameters for progression assessment will be mean segment diameter, minimal obstruction diameter, percentage severity of obstruction, length of obstruction and plaque area. So far 4826 coronary segments have been analyzed from the first angiograms of 383 patients. Per patient an average of 12.6 different segments could be evaluated in at least one angiographic projection. The major coronary segments could be measured in 72-93% of the patients in one or more angiographic projections (at the average about 2 different projections). Five hundred and forty-six coronary obstructions were analyzed; 131 of these were total occlusions. Only 9% of the length of the vessel contours detected by the computer algorithm required manual correction by the operators, suggesting a high reliability of the system. It can be concluded that quantitative measurement of the complete coronary artery system can indeed be obtained in a large angiographical multicenter study such as INTACT.

Angiography↗

PubMed1988

Effects of nifedipine and nitrates on coronary vasomotion.

The diameter changes of angiographically normal coronary arteries following vasodilator drugs were studied in 41 patients. In group 1 (22 patients) angiograms and plasma levels were obtained before as well as 10, 20 and 30 minutes after 20 mg nifedipine s.l. (15 patients) or placebo (7 patients). A cluster analysis allowed a classification of patients into group A (N = 4) and B (N = 11) according to the slope of plasma level increase. Plasma levels A versus B were 27.8 +/- 9.8/13.5 +/- 4.5 ng ml-1; P less than 0.05; 54.0 +/- 11.7/21.7 +/- 6.6 ng ml-1; P less than 0.001; 79.1 +/- 9.3/28 +/- 9.8 ng ml-1; P less than 0.001. Corresponding diameter changes A versus B were: 7.3 +/- 5.1%/-5.6 +/- 9.0%; P less than 0.01; 11.4 +/- 4.1%/-4.5 +/- 11.3%; P less than 0.01; 14.5 +/- 5.9%/0.5 +/- 13.6%; P less than 0.05. In group 2 (N = 19) angiograms were obtained before as well as 2, 4, 7 and 15 minutes after administration of 10 mg isosorbide dinitrate (N = 9) or placebo (N = 10). Coronary dilation ISDN versus placebo was: 2.4 +/- 3.6%/0.9 +/- 4.0%; NS; 10.6 +/- 5.1%/3.1 +/- 3.8%; P less than 0.001; 12.3 +/- 5.9%/-0.3 +/- 6.4%; P less than 0.005; 10.5 +/- 6.5%/-4.0 +/- 7.7%; P less than 0.005. These data indicate that the interindividual variations of changes in coronary lumen size are due to different slopes of plasma level increase, most likely due to different rates of drug absorption after sublingual administration of nifedipine.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Sublingual↗

PubMed1988

[Comparison of high and low osmolar roentgen contrast media in quantitative coronary angiography].

In 48 patients undergoing diagnostic coronary angiography changes of mean diameters of angiographically "normal" coronary segments after intracoronary injections of diatrizoate 76% or iopromide 370 performed in different intervals, were analyzed with a computer-assisted contour detection system (CAAS). Four study protocols were applied, differing in respect to the type of contrast medium administered and/or to the timing of the reference- and control-angiograms in the course of diagnostic coronary angiography. Coronary angiograms in identical projections were performed before (= reference) and directly after (1. control = C1) diagnostic angiography of the left coronary artery by injection of either diatrizoate 76% (group 1, 10 patients) or iopromide 370 (group II, 11 patients). Additional coronary angiograms were performed 1, 3, 6, and 10 min after C1. During diagnostic angiography in either group about eight dye injections were performed in about seven min. With diatrizoate 76% a significant coronary dilation averaging 18.9 +/- 6.7% (p less than 0.001) was observed at C1, depending on the number of diagnostic dye injections performed per min (mean 1.2 +/- 0.3) and on the interval between the last diagnostic injection and C1 (mean 73 +/- 35 s). Coronary dilation persisted up to the sixth minute (6.2 +/- 4.6%, p less than 0.01). With iopromide 370 a small but significant coronary dilation was observed merely at C1 (5.8 +/- 4.3%, p less than 0.05). In two other studies coronary angiograms were performed in identical projections immediately following complete diagnostic coronary angiography (reference) and in addition after 3, 4, 5, 6, 10, and 20 min (group III, 18 patients) and after 10, 20, and 30 min, respectively (group IV, 9 patients) by administration of diatrizoate 76% as the only contrast medium. Short injection intervals (1 min) resulted in a mild coronary dilation (mean up to 2.4 +/- 4.1% compared to reference; p less than 0.05), longer intervals (3-10 min) resulted in a marked diameter reduction (averaging up to -9.7 +/- 9%; p less than 0.05), probably a consequence of the return of coronary vasomotor tone to baseline levels. These results suggest that in quantitative coronary angiographic studies (e.g., testing coronary vasomotility) non-ionic contrast media should preferably be applied, and adequate injection intervals (greater than 2 min) are mandatory. In intervention- and follow-up studies based on repeated coronary angiograms dye-induced changes of coronary vasomotor tone can be avoided by premedication with vasodilating drugs, e.g. nitrates, and/or calcium antagonists.

Adult↗

PubMed1987

International nifedipine trial on antiatherosclerotic therapy (INTACT).

A number of animal studies revealed an inhibition or retardation of the progression of atherosclerosis by calcium-antagonists. Encouraged by these studies, a multicenter trial on the progression of coronary artery disease (CAD) in man was initiated testing the antisclerotic effect of nifedipine against placebo in 426 patients with mild to moderate coronary disease over 3 years. All patients underwent coronary angiography before entering the trial and will be restudied after 3 years; changes of the coronary artery lumen size are quantitatively assessed by a computer-assisted system (CAAS). INTACT (International Trial on Antiatherosclerotic Coronary Therapy) is therefore the first randomized prospective study on the progression of CAD based on a quantitated anigraphic control of the coronary system. This report presents the design of this still-ongoing study as well as inclusion and exclusion criteria. The quantitative evaluation of the coronary angiograms and the mode of compliance test are described in detail. A number of baseline data as well as the preliminary results of the quantitative evaluation of the first coronary angiograms are presented. Beside the results on the effect of the calcium-antagonist nifedipine on the progression of CAD, INTACT might also supply information on the antiatherosclerotic potency of other drugs administered additionally (beta-blockers and nitrates) and of HDL-cholesterol.

Adult↗

PubMed1987

Immunoelectron microscopic demonstration of pancreatic polypeptide in midgut epithelium of hematophagous dipterans.

Midguts of mosquitoes, Aedes aegypti and Anopheles stephensi, and of the tsetse fly, Glossina morsitans morsitans, as well as guinea pig pancreas, were prepared for electron microscopy by using low-temperature embedding in Lowicryl K4M. Rabbit antiserum to bovine pancreatic polypeptide (PP) crossreacted with secretory granules of pancreatic PP-producing cells and of the clear cells in mosquito gut. Rabbit antiserum to human somatostatin crossreacted with the control tissue, guinea pig pancreas D-cells, but not with the mosquito clear cells. None of the antisera used showed a distinct reaction with the endocrine-like cells of tsetse fly midgut. Positive reactions were revealed by gold as electron-dense marker. The gold particles were coated with protein A-gold or goat antibodies to rabbit immunoglobulin.

Aedes↗

PubMed1987

[Change in the diameter of the coronary vessels following sublingual or intravenous nifedipine administration correlated with the plasma level].

UNLABELLED: The diameter changes of angiographically normal epicardial coronary arteries were studied in 25 patients in correlation to nifedipine plasma levels. In group 1 (15 patients) 20 mg of s.l. nifedipine were administered. Measurements of the coronary lumen size (automated contour detection system, accuracy 0.12 mm) and detection of plasma levels (gas-chromatography) were done before and 10, 20 and 30 min after drug administration. According to the slope of nifedipine plasma levels, patients were divided into group 1 A (n = 4) and 1 B (n = 11). Plasma levels in both groups were: at 10 min, 27.8 +/- 9.8 and 13.5 +/- 4.5 ng/ml resp.; P less than 0.05; at 20 min, 54.0 +/- 11.7 and 21.7 +/- 6.6 ng/ml resp.; P less than 0.001; at 30 min, 79.1 +/- 9.3 and 28 +/- 9.8 ng/ml resp.; P less than 0.001. The corresponding diameter changes in A and B were: 7.3 +/- 5.1%/.-5.6 +/- 9.0% resp.; P less than 0.01; 11.4 +/- 4.1% and -4.5 +/- 11.3% resp.; P less than 0.01; 14.5 +/- 5.9% and 0.5 +/- 13.6% resp.; P less than 0.05. In group 2 (10 patients) 1 mg nifedipine was administered intravenously within 4 min. Measurements were done at 1 min intervals during infusion as well as 7 and 15 min after beginning and compared to a placebo group (n = 10). Peak plasma levels amounted to 16.7 +/- 5.7 ng/ml after 7 min. The maximum coronary dilation was reached after 4 min (verum 5.0 +/- 6.8%; placebo 3.2 +/- 3.6%). Significant differences between both groups were observed after 7 min (verum 4.1 +/- 5.3%; placebo -3.1 +/- 5.8%, P less than 0.05) and 15 min (verum 1.2 +/- 3.2%; placebo -6.2 +/- 8.4%; P less than 0.05). CONCLUSION: based on significantly different plasma levels following sublingual application of 20 mg nifedipine a classification of patients into "early-" and "late-coronary-responders" could be established. After intravenous infusion of 1 mg nifedipine peak plasma levels were much lower than after sublingual application of 20 mg and coronary diameters showed only a mild increase.

Administration, Oral↗

PubMed1986

Demonstration of anti-cuticular antibodies by immuno-electron microscopy in sera of mice immunized with cuticular extracts and isolated cuticles of adult Dipetalonema viteae (Filarioidea).

The immunogold technique was used for the ultrastructural localization of antibody-binding sites on thin sections of Lowicryl K4M embedded adult females, infective larvae and pieces of adult cuticles of Dipetalonema viteae insoluble in SDS-2-ME. The antisera used were either produced against SDS-2-ME extracts of cuticles or the insoluble pellet after SDS-2-ME extraction. With both types of antisera a labelling of epitopes on fibers was achieved in intact cuticles. In isolated cuticles the corresponding structures were absent. The same sera crossreacted with the larval and microfilarial cuticle as well as with somatic structures of all three stages. The only serum against isolated cuticle, which did not recognize cuticle fibers also did not crossreact with somatic structures. The recognition of the electron dense cortical layer insoluble in SDS-2-ME depended on the number of immunizations. A labelling of the filarial surface was never achieved. A dense labelling of the apical membrane enfoldings of the hypodermis pointed to an involvement in the synthesis of the nematode cuticle. The rough endoplasmic reticulum in the apex of the epithelial cells of the uterus, the content of the nutrient channels, and the substance between eggshell and microfilariae crossreacted with most of the antisera. This led to the conclusion that these substances are partly produced by the uterus epithelium.

Animals↗

PubMed1986

[Unstable angina pectoris: disease picture and study of its course].

The object of the present study is to analyse the history of patients with typical unstable angina. For this purpose the data of all patients admitted to the Hannover Medical School between 1977 and 1983 and taken to the CCU because of proven unstable angina (history, duration of symptoms, intrahospital mortality, incidence of infarction, medical or surgical therapy, coronary pathomorphology, mortality after release from hospital, late incidence of infarction and rehospitalization) were documented and stored on a data bank for statistical analysis. 123 patients were entered into the study (97 males, 26 females; average age 58.4 +/- 9.2 years); during hospitalization all patients had angina at rest, 94% had transient ECG-changes (ST-segment changes, BBB etc.). The average follow-up was 4.2 +/- 2.0 years. 80 patients of the whole study population were treated medically, 43 underwent early bypass surgery. The two groups were different with respect to coronary pathomorphology (number of diseased vessels) as well as left ventricular wall motion, which was significantly more impaired in the surgical group (p less than 0.05). The hospital-mortality in the surgical group amounted to 9.3% (n = 4), the incidence of infarction to 18.6% (n = 8); the hospital mortality in medically treated patients was 2.5% (n = 2), the incidence of infarction 7.5% (n = 6). During the whole study period (average follow-up 4.2 years) the overall mortality amounted to 21%, the infarction rate was 23.5%: The cumulative survival rates revealed no significant difference between the 2 groups: after 3 years 84% of all patients were still alive, 65% without new infarction during the observation period; the rate of rehospitalization amounted to 50%. At the end of the study class III or IV angina (NYHA-criteria) was much more common in the medically treated than in the surgically treated group (NYHA mean 2.5 versus 2.0; p less than 0.5). The relatively high rate of perioperative death and myocardial infarction in the surgical group is based on the selection of patients according to coronary pathomorphology and the clinical status.

Angina Pectoris↗

PubMed1985

The compaction pattern of the chromatin of trypanosomes.

Protozoa of the family Trypanosomatidae are pathogenic agents of human and animal diseases. Fine structure, compaction pattern, and histone content of the soluble chromatin were investigated in procyclic forms of Trypanosoma cruzi (Chagas disease, S. America) and T. brucei brucei (Nagana disease, Africa) in comparison with rat liver chromatin. At low ionic strength chromatin was present as nucleosome filaments. Condensation into compact fibers (solenoid) was complete for rat chromatin at 100 mM salt concentration while chromatin of T. cruzi showed less condensation (tangle formation), and that of T.b. brucei did barely condense under identical experimental conditions. In general, the nucleosomes of trypanosomes, especially T.b. brucei, seemed to be less regularly arranged than those of the higher eukaryote. Addition of histone H1-containing fractions of rat liver chromatin increased the compaction of T. cruzi chromatin but had no influence on T.b. brucei chromatin. SDS-polyacrylamide gel electrophoresis revealed histone H1 and the 4 core histones in rat liver chromatin. Neither in T. cruzi nor T.b. brucei were proteins identical to rat histone H1 present. Differences existed also in molecular weight of core histones between rat and trypanosomes, as well as between T. cruzi and T.b. brucei. These differences might explain species-specific differences in the fine structural organization and compaction pattern of the chromatin of the rat, T. cruzi, and T.b. brucei.

Animals↗

PubMed1984

A quantitative ultrastructural study on the transformation of Trypanosoma brucei metacyclic to bloodstream forms in vitro.

The transformation of metacyclic to bloodstream forms of Trypanosoma brucei brucei was studied in vitro using light and electron microscopy. The ultrastructural composition was investigated with stereological methods and the mean cell volume determined in a Coulter Channelyzer. The mitochondrion showed the most significant changes during transformation with a reduction in volume as well as in the membrane areas. The glycosomes remained unchanged whereas the lipid inclusions increased over the 24 h incubation period. The metacyclic forms contained many vesicles in the reservoir vicinity with surface coat-like material on the inner side of the membrane. Metacyclic forms also contained a previously undescribed structure, termed "inclusion body". These large, polymorphic structures whose function and origin are unknown disappeared during transformation. The mean cell volume for metacyclic forms was 15-16 microns3. During transformation the values first dropped and then increased to about 20 microns3 after 24 h.

Animals↗

PubMed1984

[Progression of coronary sclerosis. Studies in 19 patients over a 6-year period using quantitative coronary angiography].

The characteristics of progressive coronary artery disease as judged from sequential angiography were quantitatively analysed in 19 patients with stable angina in whom coronary angiograms were repeated after 64-104 months (average 76.5 months). The diameters of at most 15 corresponding segments were measured with a vernier caliper (accuracy: 0.05 mm) at identical sites and in the same projections. Considering the error in measurement (less than 10%) and spontaneous changes in smooth muscle tone only a diameter decrease of greater than 20% and/or every transition to an occlusion were recorded as progression. The progression over a 6-year interval was predominately characterized by: A large amount of total occlusions (61% of all progressive stenoses), relatively independent of the initial degree of stenosis. A large amount of newly developed obstructions which are more severe in coronary arteries already segmentally diseased at the onset, indicating a diffuse intramural disease of the entire vessel. A different pattern of progression in the 3 main coronary arteries. No influence of risk factors on natural history.

Angina Pectoris↗