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Biomedical subjects

B Bauer

Publications and source records attributed to B Bauer.

At least 127 records · Page 7Linked to original sources
PubMed1995

Gender does not influence acute myocardial infarction in adult dogs.

Mechanisms responsible for the well-documented "protection" against myocardial ischemia and infarction in young women and subsequent loss of protection after menopause remain speculative. One possibility is that gender-related variables (such as endogenous hormone levels or regular loss of stored iron) alter the susceptibility of the heart to ischemia: if so, then premenopausal women when compared with men may manifest endogenous protection against acute myocardial ischemic injury. Using the canine model we therefore sought to determine whether gender influences acute myocardial ischemia and infarction. Retrospective analysis was performed on data compiled from 60 mature adult dogs subjected to 1 hour of coronary artery occlusion and > or = 4 hours of reperfusion. We first compared the incidence of lethal ventricular fibrillation in the male and female cohorts and then for survivors compared collateral blood flow during coronary occlusion (by injection of radioactive microspheres), infarct size (assessed by tetrazolium staining and expressed as a percentage of the myocardium at risk), and regional wall motion (by somomicrometry) in the infarct-related area. The incidence of lethal ventricular fibrillation was 23% in the male dogs and 19% in the female dogs (p = 0.70, difference not significant). For survivors, the area at risk of infarction was comparable in males and females (23 +/- 2% and 22% +/- 1% of the total left ventricular weight), and the groups were equally ischemic during coronary occlusion, with collateral blood flow to the ischemic subendocardium averaging 0.05 +/- 0.02 and 0.07 +/- 0.01 ml/min/g tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Obese binge eaters: metabolic characteristics, energy expenditure and dieting.

The study was carried out in two groups of massively obese women with BMI values who were to undergo bariatric surgery. The patients were evaluated for weight variability and for the presence and the frequency of binge eating. Body composition, resting energy expenditure (REE) and metabolic parameters were also measured. When non-bingeing individuals were compared with patients who met Binge Eating Disorder criteria, no differences in body composition, fat distribution, REE values and concentrations of serum lipids, insulin and thyroid hormones were found. On the other hand, weight variability due to reduced diet in the subjects' lifetime was significantly higher. This study does not support the hypothesis that in massively obese women binge eating is somehow induced by a reduced energy expenditure.

Adipose Tissue↗
PubMed1995

Interference of angiotensin-converting enzyme inhibition with vasoactive peptides in the coronary circulation of dogs.

The coronary effects of angiotensin-converting enzyme (ACE) inhibitors and their mechanisms of action are not well understood. Because these drugs may interfere with hormone systems other than the reninangiotensin system (RAS), we studied modulation of the coronary effects of neurotensin, neuropeptide Y (NPY), and endothelin-1 (ET-1) by pretreatment with captopril in anesthetized, open-chest dogs. The left anterior descending coronary artery (LAD) was cannulated and perfused at a pressure equal to mean aortic blood pressure. Coronary blood flow (CBF) was measured by an electromagnetic flowmeter, subendocardial segment length by ultrasonic crystals. ACE inhibition (captopril 0.25 mg/kg), as an intracoronary (i.c.) injection, followed by an intracoronary infusion (0.25 mg/kg/h) did not affect the relative vasoconstrictor effects of ET-1 (10(-4)-10(-1) micrograms/kg i.c.) or neuropeptide Y (10(-3)-1 microgram/kg i.c.). However preinjection flow of a second dose-response curve of ET-1 was significantly higher in captopril-treated as compared with control animals. The increase in CBF induced by neurotensin (10(-3)-1 microgram/kg i.c.) was potentiated by captopril (40 +/- 14% after vs. 20 +/- 9% before captopril, p < 0.01, at the highest dose used). Changes in hemodynamics or in regional myocardial function could not explain altered effects of neurotensin. We therefore conclude that ACE inhibition does not interfere with the acute vasoconstrictor effects of ET-1 or NPY in this canine model but may reverse the long-term tonic coronary constrictor effect of ET-1. Potentiation of the neurotensin effect on CBF might be due to prevention of hydrolysis of neurotensin or to a cyclooxygenase-dependent mechanism.

Analysis of Variance↗
PubMed1995

Sports-related eye injuries.

At the University Eye Hospital of Lund 272 patients were treated following blunt trauma during a two and half year period. The number of cases related to sports activity were extracted. The major sports responsible for the injuries and the type of injuries were identified and also an investigation into the sex and age distribution was made. Forty percent of the total number of cases were sports-related. Floor ball was responsible for 46% of these cases.

Adolescent↗
PubMed1995

Argon laser photocoagulation of cyclodialysis clefts after cataract surgery.

Three patients with cyclodialysis clefts, hypotony and hypotonic retinopathy subsequent to cataract surgery were treated with argon laser photocoagulation. The hypotony was reversed in each patient and their visual acuity was normalized. Laser photocoagulation is a noninvasive treatment that can be repeated easily and safely. The complications of the treatment are minor. A hypertensive episode commonly occurs in the early postoperative period.

Aged↗
PubMed1995

Successful application of deltamethrin pour on to cattle in a campaign against tsetse flies (Glossina spp.) in the pastoral zone of Samorogouan, Burkina Faso.

1,500-2,000 head of cattle were treated with deltamethrin 1% Spot On in an area of high tsetse densities, notably of Glossina morsitans submorsitans. After four treatments at monthly intervals, the time between two treatments was increased to two months. 11 months after the commencement of the campaign the fly population had decreased from initially 54.2 flies/trap/day to densities varying between 0.06-2.0 flies/trap/day, mostly G. palpalis gambiensis. Blood-meal analysis showed that this species was surviving in limited areas, mainly feeding on monitor lizards; consequently it is unlikely that this species can be eradicated solely by the use of cattle treated with a pyrethroid. The resistance of Trypanosoma congolense to all commercially available trypanocides necessitated the epidemiological monitoring of calves which were born after the start of the campaign in order to reasses the real challenge. The risk of new infections was low, basically due to contracts between the cattle and tsetse outside the ranching area. A weight increase from 122.3 kg to 213.6 kg of calves aged 6-12 months was recorded from October 1993 to October 1994. An average daily weight gain of more than 400 g was observed from the end of April 1994 to the beginning of August 1994.

Animal Husbandry↗
PubMed1994

Eating disorder inventory in the assessment of psychosocial status in the obese patients prior to and at long-term following biliopancreatic diversion for obesity.

Psychological traits of obese patients, assessed with the Eating Disorder Inventory (EDI), were compared to those of subjects in the long-term following biliopancreatic diversion for obesity (BPD), when body weight has been steadily normal for over 1 year and any preoccupation with dieting and weight has been completely abandoned. The overall results suggest that the stable body weight normalization on a completely free diet does confer considerable psychological benefit on obese individuals. On the basis of the EDI results, post-BPD subjects were divided into weight-preoccupied and not-weight-preoccupied individuals. In the not-weight-preoccupied subjects, the psychosocial status and emotional rectivity were closely similar to those observed in lean control persons, whereas the few weight-preoccupied subjects, in spite of completely normal body weight, showed residual body dissatisfaction and personality traits very similar to those of eating-disordered patients.

Adolescent↗
PubMed1994

Single-photon emission tomography studies of rubidium-81 in the detection of ischaemic heart disease, using a stress-reinjection protocol.

The present study was designed to determine the feasibility of using single-photon emission tomography (SPET) imaging with rubidium-81 (T1/2 = 4.54 h) to detect ischaemic heart disease, using a stress-reinjection protocol and a specially constructed 511-keV hexagonal hole collimator for a standard gamma camera. The diagnostic performance of 81Rb SPET in detecting coronary artery disease (CAD) was investigated in 52 patients with a high prevalence of CAD. Coronary arteriography was performed in 34 patients, 25 of whom were classified as having significant stenosis (> or = 50%). At peak exercise (Cornell protocol), 111-222 MBq 81Rb was injected i.v. for stress imaging, and after 3 h of rest, 74-111 MBq was reinjected for rest imaging. The displayed short- and long-axis slices and the polar map images were interpreted qualitatively. In comparison to coronary arteriography, which served as the gold standard, the performance of 81Rb SPET revealed a sensitivity of 95% for the detection of CAD. Images of diagnostic quality were obtained in all patients, these being comparable to thallium-201 SPET images. In conclusion, these results indicate that the described method can be routinely used for the positron emitter 81Rb with a conventional gamma camera and special shielding. 81Rb has the well-known advantages of a potassium analogue and 81Rb SPET permits better visualization, particularly of the posterior wall of the myocardium, due to the higher photon energy. Considering the typical dose of 201Tl used for SPET (74-148 MBq), a 81Rb SPET scan imposes a significantly lower radiation burden on the patient.

Adult↗
PubMed1994

A novel intergenic site for integration and expression of foreign genes in the genome of pseudorabies virus.

Restriction enzyme analysis of DNA of a number of Pseudorabies virus (PRV) single plaque isolates revealed in several cases the existence of a unique EcoRI cleavage site, which has not been observed in PRV DNA before. This EcoRI site was mapped to the right end of the unique long region of the PRV genome, in BamHI-fragment 6. Sequence analysis of this region demonstrated the presence of an 11 bp tandem repeat in variable copy numbers in different PRV strains, suggesting the creation of the EcoRI recognition site by a recombinational event. The occurrence of variable reiterations and Northern blot analysis indicated an intergenic region. We therefore, used this site for integration and expression of heterologous DNA (the multiple cloning site of phage M13 and the E. coli lacZ gene). Viable PRV recombinants could be obtained which showed no detectable differences in virus growth in vitro compared to wild-type PRV. The novel insertion site can be used for the construction of PRV recombinants expressing foreign genes without apparent impairment of PRV genes.

Base Sequence↗
PubMed1994

Murine squamous cell carcinoma cell lines produced by a complete carcinogenesis protocol with benzo[a]pyrene exhibit characteristic p53 mutations and the absence of H-ras and cyl 1/cyclin D1 abnormalities.

In this report, we describe the isolation and characterization of six murine squamous cell carcinoma cell lines (BPCC) derived from carcinomas produced by a complete carcinogenesis protocol with benzo[a]pyrene (B[a]P). All six cell lines were tumorigenic to varying degrees in nude mice, and several were spontaneously metastatic to the lungs. The in vivo invasive potential of each BPCC cell line was determined using de-epithelialized tracheal xenotransplants into which cells were inoculated. This assay revealed positive association of tumor grade with in vivo invasiveness, yet no clear relationship to the spontaneous metastatic potential of the cell lines, suggestive that invasive potential is only one determinant of the overall metastatic phenotype. At the molecular level, all six BPCC cell lines revealed the absence of mutations in the H-ras oncogene and no amplification or rearrangement in the cycl 1/cyclin D1 putative oncogene. Analysis of the p53 tumor suppressor gene revealed a direct correlation between positive nuclear immunohistochemical staining of the p53 protein in four BPCC cell lines and the presence of p53 mutations identified by direct sequence analysis. The localization of mutations to exons 7 and 8 of the p53 gene and the detection of G to T transversions in two of the four cell lines bearing p53 mutations are in agreement with previous analyses of a large series of primary B[a]P-induced murine skin tumors. In addition, frameshift mutations were identified in two cell lines. The correlation of the biological and molecular properties of these BPCC cell lines with the known characteristics of primary squamous cell carcinomas induced by B[a]P indicates that these cell lines could be useful tools in elucidating the mechanisms of tumorigenesis of this important chemical carcinogen.

Animals↗
PubMed1993

Benzo[a]pyrene-induced murine skin tumors exhibit frequent and characteristic G to T mutations in the p53 gene.

Human tobacco-related cancers exhibit a high frequency of G to T transversions in the mutation hot spot region of the p53 tumor suppressor gene, possibly the result of specific mutagens in tobacco smoke, most notably benzo[a]pyrene (B[a]P). No in vivo animal model of B[a]P-induced tumorigenesis has been used, however, to substantiate these molecular epidemiological data experimentally. Direct DNA sequence analysis of the hot spot region (exons 5-8 inclusive) of murine p53 was performed in 20 skin tumors induced by a complete carcinogenesis protocol with B[a]P. Sequence analyses revealed numerous heterozygous missense mutations in carcinomas, specifically in exons 7 and 8 of the p53 gene, and targeting exclusively guanine residues. Moreover, 70% (5/7) of the mutations characterized were G to T transversions. In contrast, direct DNA sequence analysis of 36 skin tumors induced by 7,12-dimethylbenz[a]anthracene (DMBA) in either a complete carcinogenesis protocol or in a two-stage carcinogenesis protocol revealed a 30% frequency of heterozygous p53 mutations, with the majority of mutations found in carcinomas, but only a single G to T transversion (1/8). Thus, while mutation frequencies are similar, the pattern and type of p53 mutations in B[a]P-induced skin tumors differs significantly from the mutation spectra in DMBA-induced squamous neoplasias. These in vivo findings in B[a]P-induced tumors lend support to in vitro and molecular epidemiological evidence, suggesting that the p53 tumor suppressor gene may be a selective target of metabolically activated B[a]P species etiologically associated with human tobacco-related cancers.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1993

Apoptosis and hematopoiesis in murine fetal liver.

The fetal mouse liver (FL) is an organ of intense, but transient, hematopoietic activity during mid-gestation, with erythropoiesis being predominant during days 11 through 16. It therefore seemed reasonable to expect that hematopoietic cytokines, such as erythropoietin (epo), interleukin-3 (IL-3), and stem cell factor (SCF), may play important roles in maintaining a homeostatic balance of erythropoiesis and apoptosis in liver during ontogeny. First, we determined the effects of these growth factors on hematopoiesis by measuring colony formation and hemoglobin synthesis of cultured FLs. Secondly, we determined the protection from apoptosis afforded by these cytokines, using electrophoretic analysis of DNA and by flow cytometry of FL cells deprived in culture of epo, IL-3, and SCF. Erythropoietin was necessary and alone sufficient for hemoglobin synthesis in colony-forming units-erythroid colonies, but IL-3 was a required cofactor to obtain maximal development of burst-forming units-erythroid colonies. SCF alone caused little colony formation in methylcellulose cultures of FLs, but when combined with epo and IL-3, it had dramatic effects both on the number of colonies and their size. Secondly, indices of apoptosis were determined by measuring DNA fragmentation caused by endogenous nuclease activity in apoptotic cells. Liver cells from cultures without cytokines showed the extensive degradation of DNA to low molecular weight nucleosomal oligomers, which is characteristic of apoptosis. Protection from apoptosis afforded by epo directly corresponded to the level of erythropoiesis in FLs of different gestational age. Erythropoietin was by far the most critical cytokine in sparing FL cells from apoptosis. Analyses of agarose gels showed that SCF and IL-3 alone had no apparent effect in reducing the amount of DNA in fragments, and when combined with epo they had no more protective effect than that provided by epo alone. However, using the more sensitive flow cytometric determination of cells with subdiploid amounts of DNA, SCF, and IL-3 alone had measurable protective effects that were less than those caused by epo. Thus, we show that normal, untransformed cells of the developing hematopoietic system not only require cytokines for proliferation and differentiation, but they have an initial and absolute requirement of them for protection from apoptosis.

Animals↗
PubMed1993

Combination of ramipril and hydrochlorothiazide in the treatment of mild to moderate hypertension--Part 2: An open long-term study of efficacy and safety.

In an open, multicenter extension of a short-term study, 159 patients with mild to moderate hypertension were treated with either ramipril monotherapy or a combination of ramipril and hydrochlorothiazide for up to 1 year. Patients started with either 5 mg ramipril once daily (responders in the short-term study) or a combination of ramipril 5 mg plus hydrochlorothiazide 25 mg once daily. The dose could be adjusted and nonresponders to ramipril monotherapy could have hydrochlorothiazide added. In the 38 patients treated with ramipril monotherapy, the largest drop in mean blood pressure (BP) had already occurred in the previous short-term study; from Week 2 in the long-term study, the BP remained stable with means below 150/90 mmHg. In the 83 patients treated with the combination for 50 weeks or more, mean BP continued to decrease until around Week 10 in the long-term study while therapy was being adjusted. Thereafter, it also remained stable with means below 150/85 mmHg. Both treatment groups showed good mean reductions at end point, as did the group of 38 patients treated with the combination for less than 50 weeks. High response rates (84-95%) were seen in all groups at end point. The combination was well tolerated and the efficacy of ramipril in combination with hydrochlorothiazide was maintained over the 1-year period of investigation.

Adult↗
PubMed1993

Immune restoration in children after partial splenectomy.

Splenectomy (SE) is recognized to be a therapeutical approach in treating children with severe autoimmune diseases (chronic idiopathic thrombocytopenia; hemolytic anemia) or hypersplenism because of portal hypertension. Nevertheless, removal of a main immune organ results in elevated infection risk for these patients. Partial splenectomy (PSE) was developed as a therapeutical compromise to retain immunologically active spleen tissue. Here, we document the analysis of immune parameters obtained from children after both partial and total splenectomy, which have been followed up for a period of more than 6 years: (i) Lymphocytes from both groups of patients failed to produce IgG in response to pokeweed mitogen in vitro. This was observed in 11/20 splenectomized patients even 10 years after operation, whereas in PSE patients a restoration of this parameter after 1-2 years was seen. (ii) In patients after PSE, but not in splenectomized persons, an elevated number of HLA-class II positive cells had been detected suggesting a different situation of immune regulation following this operation. However, in parallel with an improvement of B cell in vitro activity this parameter was found to achieve normal values. Our findings indicate that partial splenectomy may be a therapeutical alternative, if the therapeutic goal can be achieved by this procedure.

Adolescent↗
PubMed1993

Invasive tumors derived from xenotransplanted, immortalized human cells after in vivo exposure to chemical carcinogens.

Several chemicals that are found in cigarette smoke or diesel oil engine exhausts, such as benzo[a]pyrene (B[a]P) and 1,6-dinitropyrene (DNP) are carcinogenic in experimental animal models. In the present study, we have exposed in vivo the xenotransplanted immortalized human bronchial epithelial cell line BEAS-2B to the ultimate carcinogen of B[a]P, benzo[a]pyrene diolepoxide (BPDE), to DNP or to the benzo[e]pyrene, a less active compound that has tumor-promoting abilities in mouse skin carcinogenesis bioassays. All three compounds were administered using slow-release beeswax pellets. After a 6 month exposure, BPDE produced two tumors in seven transplants, four tumors were seen in 10 transplants treated with DNP and one tumor was observed in five tracheal grafts exposed to B[a]P. All the neoplasms were well-differentiated invasive adenocarcinomas. Tracheal transplants exposed to beeswax without carcinogen did not show any evidence of neoplastic growth, and their luminal surfaces were lined by a single or double layer of cuboidal cells. All lines derived from the adenocarcinomas showed increased in vitro resistance to serum-induced terminal differentiation, gelatinolytic activity, s.c. tumorigenicity and invasive growth in an in vivo assay. When these cell lines were compared with previously described tumor cell lines derived from xenotransplants exposed to cigarette smoke condensate, it became clear that the latter exhibited a more aggressive invasive behavior. Nevertheless treatment with the three chemicals gave rise to tumor cell lines that exhibited a similar invasive behavior in vivo, and were able to penetrate early into the wall of the tracheal transplants in which they were seeded. These data indicate that this system based on xenotransplanted bronchial epithelial cells is a very relevant model to identify human carcinogens and to study mechanisms of bronchogenic cancer pathogenesis.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗
PubMed1993

Cardiac dysfunction and development of heart failure.

A major consequence of chronic cardiac dysfunction is chronic overload of contractile myocardium. Various aetiologies, in reaction to this, may induce compensatory mechanisms consisting of excentric (dilatation) and concentric hypertrophy. Chronic left ventricular dysfunction is caused most frequently by myocardial infarction. Left ventricular dilatation and hypertrophy occurs in patients with extensive infarction. Dilatation may at first be compensatory, restoring stroke volume within 4 weeks of the infarct. However, as dilatation progresses, left ventricular ejection fraction and stroke volume deteriorate during exercise and at rest, and finally pulmonary capillary wedge pressure increases and patients become symptomatic 1.5-3 years after the infarct. Major determinants of progressive left ventricular dilatation and deterioration of haemodynamics are a depressed left ventricular ejection fraction, angiographically determined infarct size, stroke volume early (4 days) after myocardial infarction, infarct location (anterior/inferior) and the grade (TIMI) of perfusion of the infarct-associated coronary artery. Chronic loading and unloading may accelerate or decelerate this process. Efficiency and energy reserve (phosphocreatine) of the dilated ventricles is reduced. Further intrinsic changes in surviving myocardium include morphological and functional disturbance of coronary microcirculation.

Cardiomegaly↗