PubMed Health⌕ Search

Biomedical subjects

B Wiese

Publications and source records attributed to B Wiese.

At least 37 records · Page 2Linked to original sources
PubMed1994

Increased renal net acid excretion in prematures below 1,600 g body weight compared with prematures and small-for-date newborns above 2,100 g on alimentation with a commercial preterm formula.

In 76 low birth weight infants with an actual body weight ranging from 1,210 to 2,540 g and fed a commercial preterm formula, urine samples were collected and blood acid base status was measured on day 38 (+/- 17, mean +/- SD) of life. Infants with an actual body weight below 1,600 g demonstrated a higher daily weight gain (22 +/- 3 vs. 14 +/- 5 g/kg/day), lower blood pCO2 (35.4 +/- 5.0 vs. 38.9 +/- 3.8 mm Hg), lower urine pH (5.8 +/- 0.5 vs. 6.5 +/- 0.3), higher renal net acid (1.86 +/- 0.38 vs. 1.28 +/- 0.55 mmol/kg/day) and higher phosphorus excretion (0.67 vs. 0.52 mmol/kg/day) than infants with an actual body weight above 2,100 g. Urinary ionogram data of these 2 groups of infants show that the increased renal net acid excretion of the smaller prematures is the result of a lower urinary excretion of sodium, potassium and chloride, due to a higher daily weight gain, probably a higher retention of these minerals, and a higher urinary phosphorus excretion probably due to an age-specific lower intestinal calcium absorption, and therefore a lower rate of calcium and phosphorus retention. Considering the low renal capacity for hydrogen ion excretion, very low birth weight infants still run a considerable risk for disturbances of acid base metabolism due to the high mean level of net acid excretion in nutrition with preterm formulas and an additional age-specific augmentation of renal acid load.

Acid-Base Equilibrium↗
PubMed1994

[Prospective study of maternal behavior in the neonatal period: a pilot study].

This study intends to test empirically some pre- and perinatal conditions of loving motherly behavior and motherly anxiety during the first month after birth. In the framework of a prospective study a sample of 40 women, pregnant for the first time, was tested by a questionnaire in the last trimester of pregnancy. They were visited in their homes about 19 days after having given birth. There loving behavior during nursing was observed. Their anxiety was credited by a structured interview. When considering the single postulated predictors separately a significant prediction of the observed loving behavior was only possible by the frequency of their attempts to establish a contact with the unborn. This predictor was able to explain one third of the variance. If all the relevant predictors were considered, two fifth of the loving behavior could be explained. It was clearly confirmed that the experience of a direct sensual and physical contact was most important for the continuity of a loving relationship with the child while the cognitive engagement was far less important. Personality characteristics like emotional lability and anxiety proved to be significant correlates of early maternal anxiety, thus confirming once again the relevance of stable personality characteristics for motherly behavior.

Adult↗
PubMed1993

Quantitative angiographic follow-up studies on the development of coronary artery disease: which coronary segments should be analyzed? Experience from INTACT.

Angiographic follow-up studies on the evolution of coronary artery disease are of increasing relevance. It has still to be evaluated which coronary segments are predominantly involved in the process of atherosclerosis and, thus, should be preferably included in the analysis. Therefore, the correlation of progression and regression of coronary disease with the diameter and location (proximal, mid or distal) of coronary segments was investigated from the data of the INTACT-study, in which 25 different coronary segments were defined including anatomic variants of rather distal segments. In 348 patients with coronary artery disease, standardized coronary angiograms were repeated within 3 years and were quantitatively analyzed (CAAS). In 1063 coronary stenoses (% diameter stenosis > 20%) compared from both angiograms, progression and regression were not influenced by diameter nor location of arterial segments. In the follow-up angiograms, the number of new lesions (stenoses and occlusions) per coronary segment differed with regard to segment diameter (> 3 mm: 64/1125 (6%); 2-3 mm: 139/1967 (7%); < 2 mm: 44/1756 (2%); p < 0.001) and location of segments (proximal: 86/1285 (7%); mid: 84/1193 (7%); distal: 77/2370 (3%); p < 0.001). Out of 77 distal new lesions, only 25 (32%) were found in segments < 2 mm in diameter. Since the absolute number of new lesions was high in distal coronary segments, but low in segments with diameters < 2 mm, angiographic follow-up studies should analyze coronary segments at any location, but may neglect segments with diameters smaller than 2 mm.

Coronary Angiography↗
PubMed1993

Progression of coronary artery disease is dependent on anatomic location and diameter. The INTACT investigators.

OBJECTIVES: This study represents the first prospective, quantitative analysis of the association of progression of coronary atherosclerosis with anatomic site and diameter. BACKGROUND: The progressive course of coronary artery disease has been documented in many angiographic follow-up trials. METHODS: The data of 348 patients with coronary artery disease from the International Nifedipine Trial on Antiatherosclerotic Therapy (INTACT) were reviewed. Standardized coronary angiograms were taken 3 years apart and were analyzed quantitatively. The coronary tree was subdivided into 25 segments. The progression of 1,063 preexisting coronary stenoses and the appearance of 247 newly formed stenoses was assessed in relation to the mean diameter of segments (< 2 mm, 2 to 3 mm, > 3 mm) and to their position in the coronary tree (proximal, mid, distal) and in the three major coronary arteries. RESULTS: Decreases in the minimal diameter of preexisting stenoses were largest in segments that were > 3 mm in diameter (mean +/- SD 0.23 +/- 0.5 mm vs. 0.10 +/- 0.4 mm and 0.02 +/- 0.3 mm, p < 0.001), in a proximal position (0.14 +/- 0.5 mm vs. 0.09 +/- 0.4 mm and 0.06 +/- 0.3 mm, p = 0.081) and in the right coronary artery (0.14 +/- 0.4 mm vs. 0.07 +/- 0.4 mm and 0.07 +/- 0.3 mm, p < 0.01). Changes in percent diameter stenosis of preexisting stenoses were lowest in segments that were < 2 mm in diameter and in a distal position (p = NS). The number of new stenoses/segment was lowest in segments that were < 2 mm in diameter (44 of 1,756 vs. 139 of 1,967 and 64 of 1,125, p < 0.001) and in a distal position (77 of 2,370 vs. 84 of 1,193 and 86 of 1,285, p < 0.001) and was highest in segments of the right coronary artery (100 of 1,546 vs. 66 of 1,496 and 72 of 1,492, p = 0.044). CONCLUSIONS: Progression of coronary artery disease occurs most frequently in coronary segments that are > 2 mm in diameter, in a proximal or midartery position and in the right coronary artery.

Coronary Angiography↗
PubMed1992

Concept of an antiatherosclerotic efficacy of calcium entry blockers. INTACT Investigators.

Animal experiments suggest an inhibitory effect of calcium entry blockers on arterial calcinosis and the formation of atherosclerotic plaques. Experiments with isolated tissues suggest various mechanisms for an antiatherosclerotic effect of calcium entry blockers. INTACT, the International Nifedipine Trial on Antiatherosclerotic Therapy, is the first study investigating, with a prospective, placebo-controlled, randomized, double-blind design, the influence of a calcium entry blocker (nifedipine 80 mg/day) on the progression of coronary atherosclerosis in patients with proven coronary artery disease. Study endpoints were changes of established coronary stenoses (diameter reduction greater than or equal to 20%), as well as the formation of new stenoses as documented by coronary angiography. Standardized coronary angiograms were taken before and after a treatment period of 3 years. The angiograms were quantitatively analyzed with the computer-assisted edge detection system CAAS. Of the 425 patients included in the study, 282 patients (134 on nifedipine and 148 on placebo) revealed no protocol violations. In the inclusion angiograms of these patients, 893 coronary stenoses were detected which were not significantly influenced in their development by nifedipine. However, 196 entirely new coronary lesions, 185 stenoses and 11 occlusions, were found in the follow-up angiograms. There were 78 lesions in 54 patients (40%) on nifedipine (0.58 new lesions/patient) and 118 lesions in 73 patients (49%; n.s.) on placebo (0.8 new lesions/patient; p = 0.031). In two other studies on the inhibiting effect of dihydropyridine calcium entry blockers on the progression of coronary artery disease in man defining angiographic endpoints, the drugs were also shown to reduce the number of newly formed significant coronary lesions. If further trials in man confirm a protective role of calcium entry blockers against the formation of atherosclerotic coronary lesions, a new strategy in the prevention of coronary artery disease has to be considered.

Animals↗
PubMed1992

Anatomical progression of coronary artery disease in humans as seen by prospective, repeated, quantitated coronary angiography. Relation to clinical events and risk factors. The INTACT Study Group.

BACKGROUND: At present, there is extensive knowledge on the clinical course of coronary artery disease (CAD), whereas data on the underlying anatomical changes and their relation to clinical events are still limited. METHODS AND RESULTS: We investigated progression and regression of CAD prospectively over 3 years in 230 patients (average age, 53.2 years) with mild to moderate disease by applying quantitated, repeated coronary angiography. Minimal stenotic diameters, segment diameters, and percent stenosis were analyzed by the computer-assisted Coronary Angiography Analysis System (CAAS). Progression was defined either as an increase in percent stenosis of preexisting stenoses by greater than or equal to 20% including occlusions or as formation of new stenoses greater than or equal to 20% and new occlusions in previously angiographically "normal" segments. At first angiography, we found 838 stenoses greater than or equal to 20% (average degree, 39.3%) and 135 occlusions in the four major coronary branches (4.23 lesions per patient). At second angiography, 82 (9.8%) of the preexisting stenoses had progressed, 15 of them up to occlusion (1.8%; preocclusion degree averaging 46.6%; 29.7-65.6%). In addition, there were 144 newly formed stenoses (average degree, 39.2%) and 10 new occlusions. Hence, 25 (2.6%) of all stenoses had become occluded. Altogether, 129 patients (56.1%) showed progression: 68 (29.6%) with new lesions only, 27 (11.7%) with preexisting lesions, and 34 (14.8%) with both types. Regression (decrease in degree of stenoses greater than or equal to 20%) was present in 29 stenoses (3.6%) and 28 patients (12%). The incidence of new myocardial infarctions was low, with three originating from occluding preexisting stenoses and one from new stenoses; hence, only four (16%) of the 25 new occlusions led to myocardial infarctions. Risk factor analysis showed that cigarette smoking correlated significantly with the formation of new lesions (p = 0.001), whereas total cholesterol correlated with the further progression of preexisting stenoses (p = 0.017) but not with the incidence of new lesions. CONCLUSIONS: In patients with mild to moderate CAD, the angiographic progression is slow (in this study 18.7% of patients and 7% of stenoses per year) but exceeds regression (4.1% of patients and 1.2% of stenoses per year). Progression is predominantly seen in the formation of new coronary stenoses and less in growth of preexisting ones. Most of the stenoses were of a low degree (less than 50%), clinically not manifest including those going into occlusion and leading to myocardial infarction. Progression was influenced by risk factors, especially cigarette smoking (formation of new lesions) and high cholesterol levels (progression of preexisting stenoses).

Constriction, Pathologic↗
PubMed1991

Bioanalysis of diclofenac as its fluorescent carbazole acetic acid derivative by a post-column photoderivatization high-performance liquid chromatographic method.

A sensitive and selective bioanalytical liquid chromatographic method for diclofenac is described. The drug was detected as a flourescent derivative, which was demonstrated by 1H NMR and mass spectrometric studies to be carbazole acetic acid. Diclofenac was derivatized by UV irradiation of the substance performed as a post-column photoreaction. The reactor was a PTFE capillary wound around a 254-nm UV lamp. Diclofenac was isolated from the plasma samples by precipitation of the proteins with acetonitrile. A 50-microliters volume of the supernatant was injected onto a Nucleosil C18 column. The mobile phase was 32% acetonitrile in pH 6.6 buffer. Carbazole acetic acid was detected by a fluorescence detector using an excitation wavelength of 288 nm and an emission wavelength of 360 nm. The recovery was 92%, the standard curve was linear in the range 10-5500 ng diclofenac per ml plasma, and the relative standard deviation at 10 and 5000 ng of diclofenac per ml plasma was 9.0% and 3.3%, respectively. The limit of detection was 6 ng/ml at an injection volume of 50 microliters. Chromatograms of human and rat plasma containing diclofenac are shown.

Animals↗
PubMed1991

Angioplasty of subacute and chronic total coronary occlusions: success, recurrence rate, and clinical follow-up.

Angioplasty of single total, subacute, or chronic coronary occlusions was performed in 90 patients. It was successful in 54 occlusions (60%), in 77% of those less than 6 weeks old, and in 44% of those of greater than 6 weeks' duration (p less than 0.005). All procedures were uneventful. Control angiography was performed in 53 (98%) patients with successful angioplasty after an average interval of 97 +/- 53 days. Stenosis had recurred in 16 patients (30%). During a follow-up period of 36 +/- 13 months, three patients died, five patients underwent coronary bypass operation, and 10 had reangioplasty. Despite an additional late angiographic recurrence of stenosis in seven patients, 36 patients revealed angiographic long-term success. In the 46 nonoperated patients, angina pectoris and exercise stress tests were substantially improved. Thus angioplasty of subacute and chronic total coronary occlusions is an uneventful procedure, the success rate depending on the duration of the occlusions. Despite a high angiographic recurrence rate, the angiographic and clinical long-term results are favorable.

Adult↗
PubMed1991

[Percutaneous, transluminal angioplasty of aortocoronary venous bypass grafts--acute success, angiography and clinical follow-up].

In 41 consecutive patients with 49 stenoses of aorto-coronary venous bypass (ACVB) grafts percutaneous transluminal angioplasty (PTA) was attempted. PTA was successful, i.e., the percent area stenosis was reduced by greater than 20% to less than 70% (quantitative measurement with a precision magnifying lens from two orthogonal angiographic views) in 46 stenoses (94%) of 38 patients (93%). In 35 patients (92%) with 42 stenoses control coronary angiography was performed after a mean interval of 189 +/- 186 days. Recurrence, defined as an increase of percent area stenosis to greater than or equal to 70%, was found in nine stenoses (21%) of nine patients (26%). Recurrence correlated with a stenosis length greater than 10 mm before PTA (5/8 vs 4/32 stenoses: p less than 0.01). In recurrent stenoses, the average diameter of the grafted native coronary artery was significantly smaller than in recurrence-free stenoses (1.92 +/- 0.52 mm vs 2.45 +/- 0.50 mm; p less than 0.01). Clinical data were collected from all 38 patients with successful PTA after an average of 30 +/- 17 months following PTA. In this interval, 11 patients had undergone re-angioplasty and eight patients were re-operated; in addition, there were three cardiac deaths. In the 27 surviving patients without re-operation (71%), angina pectoris had improved from a mean of 3.0 +/- 0.7 before PTA to 1.8 +/- 1.0 (CCS-classification) (p less than 0.001). In 19 of the 27 patients (70%) the exercise stress test was negative, in contrast to only three patients (11%) before PTA. Thus, in the majority of patients PTA of ACVB-graft stenoses improves quality of life.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1990

Features of the angiographic evaluation of the INTACT study. International Nifedipine Trial on Antiatherosclerotic Therapy.

INTACT (International Nifedipine Trial on Antiatherosclerotic Therapy) is a prospective, placebo-controlled, randomized, double-blind, multicenter trial analyzing the influence of 80 mg nifedipine/day on the angiographic progression of early stage coronary atherosclerosis. Coronary angiograms were taken in identical projections before and after a treatment period of 3 years. Quantitative analysis of the angiograms was performed with the computer-assisted contour detection system CAAS. For definition purposes, the coronary artery system was subdivided into 25 different segments, including all anatomic variants. Measurement parameters of segments were mean and minimal diameter, and of stenoses minimal diameter, percentage diameter reduction (at least 20%), length, and plaque area. The variable extent of the changes of these parameters in the different projections analyzed per patient in the two study angiograms was considered by separate computation of the maximal, mean, and minimal changes over these projections; the comparison of the parameter changes between the two treatment groups was performed separately according to these three modes. For all parameters, this comparison was performed on the basis of the individual 25 segments, as well as after aggregation of individual segments to arteries (RCA, LAD, and LCX), to groups of large and small segments, and to the entire coronary artery system. Assessment of changes of the coronary (patho)morphology by quantitative analysis of coronary angiograms is associated with a number of methodical limitations, which may lead to a certain variability of the results. However, due to the double-blind feature of INTACT, this variability should be comparable in the two groups of this study, allowing for a conclusive comparison.

Angiography↗
PubMed1989

Basic extraction studies of benzylpenicillin and its determination by liquid chromatography with pre-column derivatisation.

In order to develop a sensitive and precise chemical bioanalysis of benzylpenicillin in biological fluids, basic studies on benzylpenicillin are presented. These studies include pH dependent stability, extraction in aqueous ethylacetate systems in different pH and buffer compositions. A pre-column derivatisation LC method for the detection of benzylpenicillin also is described. The derivatisation of the sample is performed by the beta-lactam ring specific formation of the mercuric(II)mercaptide of the penicillenic acid in the presence of imidazole. The UV spectral properties of the derivative are utilised for detection. The chromatographic conditions are optimised with reference to the pH, the methanol, the imidazole and the mercury(II)chloride content of the mobile phase as well as the column temperature.

Chromatography, Liquid↗
PubMed1989

Digital subtraction chromatography: an LC-technique to reduce disturbing peaks in bioanalysis.

A method of reducing disturbing peaks in LC-chromatograms is described. The technique, here called digital subtraction chromatography (DSCh), makes use of the new generation of integrating chromatographic data processors. These processors are able to store the LC-detector signal and then subtract one chromatogram from another with the resulting chromatogram reintegrated and reprinted. The possibility of getting a useful chromatogram by subtracting a zero sample chromatogram from a sample with disturbing peaks is demonstrated. The theoretical background of the method is given together with a discussion of the optimisation of the chromatographic conditions. A bioanalytical application is given.

Chloramphenicol↗
PubMed1989

Determination of benzylpenicillin in milk at the pg ml-1 level by reversed-phase liquid chromatography in combination with digital subtraction chromatography technique.

A method for the determination of benzylpenicillin in milk at very low levels by a pre-column derivatisation LC-method is described. Nine millilitres of milk were precipitated and extracted. The sample was concentrated 40 times and the recovery of benzylpenicillin was about 90%. The derivatisation of benzylpenicillin was made by the beta-lactam ring specific formation of the mercuric mercaptide of the penicillenic acid in the presence of imidazole. A technique called digital subtraction chromatography (DSCh), which uses the built-in background compensation programme of the chromatographic data processor, was applied to the chromatographic step of the analysis. The blank sample required for this technique was obtained by the beta-lactam ring specific hydrolysis of benzylpenicillin by penicillinase. By this technique it was possible to reduce interfering background peaks on the chromatograms and to increase the specificity of the method. Standard curves were made in the range 0.2-1000 ng benzylpenicillin ml-1 milk. The relative standard deviation (RSD) at 1 ng ml-1 milk, corresponding to an injection of 3.9 ng benzylpenicillin-sodium converted to the mercuric mercaptide of the penicillenic acid, was +/- 7.8% and RSD at 10 ng ml-1 milk was +/- 1.6%.

Animals↗
PubMed1989

Determination of benzylpenicillin in plasma and lymph at the ng ml-1 level by reversed-phase liquid chromatography in combination with digital subtraction chromatography technique.

A method for the determination of benzylpenicillin (Pc-G) at very low levels in plasma and lymph is described. Detection at 325 nm of the mercuric mercaptide of benzylpenicillinic acid was made by liquid chromatography via a pre-column derivatization method. By using a digital subtraction chromatography technique, the bioanalytical method could be applied to different kinds of samples whether interfering peaks were present or not. Two different clean-up steps were used for two concentration ranges 0.1-100 micrograms and 1-1000 ng Pc-G ml-1; namely, precipitation of a 100-microliters sample with acetonitrile, or precipitation of a 1- or 2-ml sample followed by concentration via liquid-liquid extraction. The pre-column derivative of Pc-G was achieved using mercury(II)chloride in the presence of imidazole. The blank samples required for the digital subtraction chromatography technique were obtained by penicillinase treatment. Standard curves were made in the two concentration ranges. The relative standard deviation (RSD) at 5 ng Pc-G ml-1 plasma was 4.9% and at 5 micrograms Pc-G ml-1 lymph it was 2.8%. The stability of Pc-G, including the problems with non-sterile samples, was studied.

Animals↗
PubMed1989

Validation of an imaging system: steps to evaluate and validate a microscope imaging system for quantitative studies.

The processing methods described in this article are general and can be used with any computer with adequate software without reference to a specific experimental apparatus. To achieve appropriately corrected images, the operations must be performed correctly and in a specific order to extract meaningful information from digital images. The operations are subtraction of the dark current, a shading correction after low pass filtering of the shading mask, a geometric correction with a reference grid obtained at the longest wavelength of interest, and finally registration. Since the digital data sets are too large for manual evaluation, statistical criteria must be used to define the analytical capabilities and error limits of the system before the more interesting cellular studies can be undertaken.

Algorithms↗
PubMed1989

Pharmacokinetics and cardio-respiratory effects of oral theophylline in exercised horses.

The pharmacokinetics of theophylline at rest and the effects on cardio-respiratory and blood lactate responses to exercise were investigated after repeated oral administrations in six healthy Standardbred horses. A dose of 5 mg/kg body weight was administered every 12 h. The binding of theophylline to plasma protein was also determined. There was good agreement between predicted and observed plasma concentrations of theophylline at steady state. The mean half-life of elimination was shown to be 17.0 +/- 2.5 h, the mean half life of absorption was 1.6 +/- 1.8 h, the apparent volume of distribution was 852 +/- 99.0 ml/kg and total plasma clearance 0.61 +/- 0.08 ml/kg/min. Theophylline showed very low plasma protein binding (12%). The heart rate and blood lactate levels, during and after exercise, were significantly increased during theophylline-treatment. There was an increase of the arterial oxygen tension after exercise and the arterial carbon dioxide values before and after exercise were significantly lower than the premedication values. No severe adverse effects of the drug were noted. The recommended oral dose is therefore 5 mg/kg every 12 h but due to inter-individual variation, an adjustment of the dose may be necessary. The changes in the studied exercise parameters indicate that the performance capacity may be impaired by theophylline in the healthy horse.

Administration, Oral↗
PubMed1988

The disposition of chloramphenicol in colostrum-fed and colostrum-deprived newborn pigs.

The pharmacokinetics of chloramphenicol (CAP) were studied in four colostrum-deprived and 4 colostrum-fed newborn piglets after an intravenous bolus dose of CAP, 77 mumol kg-1 (25 mg kg-1). The elimination half-lives in the colostrum deprived piglets had a tendency to be longer (17.2 +/- 3.9 hrs) than in the colostrum-fed piglets (12.7 +/- 1.1 hrs) and in both groups they were considerably longer than reported in older pigs. The long half-lives of CAP in the newborn pigs were a reflexion of very low clearance (Cl) values, 0.0391 +/- 0.007 and 0.0512 +/- 0.007 1 kg-1 hr-1, in the two groups, while the volume of distribution was of the same size in the two groups, 0.9549 +/- 0.247 and 0.9411 +/- 0.211 1 kg-1. The protein binding of CAP in pooled piglet plasma was concentration dependent, 53-45%, (P less than 0.001) in the concentration range 31-232 microM (10-75 micrograms ml-1) and the binding degree was significantly higher in plasma from colostrum deprived piglets, 53.0 +/- 0.8% compared to plasma from colostrum fed, 47.5 +/- 1.3% (P less than 0.01).

Animals↗