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Biomedical subjects

A Hartmann

Publications and source records attributed to A Hartmann.

At least 271 records · Page 15Linked to original sources
PubMed1996

Environmental effects on laser Doppler pulpal blood-flow measurements in man.

The increasing number of experiments using laser Doppler flowmetry in man for pulpal blood-flow recordings leads to questioning of the experimental recording conditions. The present study focused on three points: the design of the laser probe holder, the isolation of the tooth, and the influence of the recording site. A rigid polyurethane splint used in addition to different isolation devices (cotton roll, metal shield, rubber dam) was compared with a silicone splint. The silicone resulted in significantly higher values (+341%) than the polyurethane splint. The combination of the polyurethane splint with isolation devices decreased, in all cases, the flux values. The polyurethane/rubber-dam combination was the most efficient in individualizing the pulpal blood flow (-69% decrease). Recordings on non-vital teeth confirmed the hypothesis that there was periodontal contamination of the recorded flow, as the signal was abolished when using the polyurethane/rubber-dam combination. Cervical recording sites gave significantly higher values than occlusal sites (+42%). It is concluded that, in man, the part played by the periodontium may have been underestimated in previous recordings of pulpal blood flow. The use of a rubber dam in combination with a rigid splint to enhance the validity of recordings is proposed.

Dental Pulp↗
PubMed1996

Time course of endothelial function in epicardial conduit coronary arteries and in the microcirculation in the long-term follow-up after cardiac transplantation.

BACKGROUND: Endothelial dysfunction has been reported in epicardial conduit coronary arteries and in the microcirculation after cardiac transplantation. It has been assumed that endothelial dysfunction may precede hemodynamically relevant transplant vasculopathy. In this study the long-term course of endothelial function was investigated in conduit coronary arteries and in the microcirculation after cardiac transplantation. METHODS: Patients were stratified according to time after transplantation (group I, up to 2 years after transplantation; group II, 2 to 4 years after transplantation; group III, more than 4 years after transplantation). Changes of the diameter of proximal, mid and distal segments of the left anterior descending coronary artery and the circumflex branch of the left coronary artery were investigated after endothelium-dependent and endothelium-independent stimulation with acetylcholine (ACh, 50 and 100 micrograms i.c.) and nitroglycerin 0.3 mg i.c. Coronary flow changes were assessed endothelium-dependently (ACh 50 and 100 micrograms i.c.) and endothelium-independently (dipyridamole 0.56 mg/kg i.v.) utilizing an 8 F Judkins-style Doppler catheter. RESULTS: Application of 50 micrograms/100 micrograms ACh resulted in a reduction of coronary artery diameter in proximal, mid and distal vascular segments of the left anterior descending coronary artery and the circumflex branch of the left coronary artery. The vasoconstrictive effect did not differ significantly between groups I,II and III. Nitroglycerin 0.3 mg i.c. increased coronary artery diameters in groups I, II and III. ACh (50 micrograms/100 micrograms) increased coronary flow index by 217 +/- 70%/236 +/- 110% (P < 0.05 vs. baseline) in group I, 113 +/- 26%/77 +/- 22% (P < 0.05 vs. baseline) in group II and 108 +/- 26%/109 +/- 21% (P < 0.05 vs. baseline) in group III. Dipyridamole increased coronary flow index by 296 +/- 78% (P < 0.05 vs. baseline) in group I, by 63 +/- 16% (P < 0.05 vs. baseline and vs. group I) in group II and by 113 +/- 30% (P < 0.05 vs. baseline and vs. group I) in group III. CONCLUSION: A constant vasosonstrictor response to ACh was observed in epicardial coronary arteries after cardiac transplantation indicating endothelial dysfunction independent of the time course. Endothelial dysfunction in these vessels may not be an early indicator of hemodynamically relevant transplant vasculopathy. Endothelium-dependent and endothelium-independent flow reserves decreased 2 years after transplantation and remained constant thereafter.

Acetylcholine↗
PubMed1996

Detection of DNA effects in human cells with the comet assay and their relevance for mutagenesis.

The single cell gel test (SCG-test or comet assay) is a rapid and sensitive method for measuring DNA damage and repair in individual cells. A wide variety of mutagens have been shown to cause DNA alterations detectable with the comet assay, but it is not yet clear whether a relationship exists between the DNA effects and the induction of mutations. We are therefore investigating in a cell culture system with human cells (MRC5CV1) the induction of DNA damage by environmental mutagens and the formation of mutations at the HPRT gene. In the present study we investigated benzo[a]pyrene (BP), an environmental mutagenic and carcinogenic polycyclic aromatic hydrocarbon, and its reactive metabolite (+)-anti-benzo[a]pyrene-7,8-diol 9, 10-oxide ((+)-anti-BPDE). S9 mix activated BP and the direct acting mutagen (+)-anti-BPDE caused a concentration-related increase in DNA migration in the comet assay. Postincubation experiments indicated that induced DNA effects are eliminated by DNA repair within 24 h. BP-treatment caused a strong genotoxic effect in the comet assay but had only a marginal effect on the frequency of gene mutations. When cells were treated with BP in the presence of cadmium sulphate, a clear increase in genotoxicity was observed while the effect on mutations was unchanged. Our results indicate that DNA alterations detected with the comet assay do not necessarily relate to mutagenesis. The absence of a close relationship between DNA migration in the comet assay and mutagenesis may be explained by the fact that some effects seen in the comet assay occur as a consequence of an error free DNA repair process.

Benzo(a)pyrene↗
PubMed1996

High frequency of p53 gene mutations in primary breast cancers in Japanese women, a low-incidence population.

The pattern of acquired mutations in the p53 tumour-suppressor gene is potentially useful for determining factors contributing to carcinogenesis in diverse populations differing in incidence and/or mortality from the disease. We previously reported differences in mutational patterns of the p53 gene in primary breast cancers from Midwest US Caucasian, African-American and Austrian women. Herein, we report 16 mutations in 27 primary breast cancers from Japanese women from Hirosaki, a population with a low incidence of breast cancer. The frequency of 59.3% of p53 mutations is the highest reported in breast cancers from a particular ethnic group thus far. A relatively high number of mutations (7/16) were heterozygous in at least some tumour cell clusters. Intergroup comparisons of the mutational pattern between this population and several other US, European and Japanese populations do not show any statistically significant differences. There were recurrent mutations at two sites, codon 273 (R --> H; three mutations), a common hotspot of mutations in breast and other cancers, and codon 183 (S --> Stop; two mutations), a very rare location for p53 mutations. These mutations were shown to be independent and presumably not in the germ line. The highest frequency of p53 mutations raises the possibility that p53 mutagenesis is a predominant factor for breast cancer development in this low-risk Japanese group, whereas in other cohorts different mechanisms are likely to account for the higher proportion of breast cancer. Further studies are needed to confirm the present observations.

Adult↗
PubMed1996

DNA damage after exhaustive treadmill running in trained and untrained men.

The single cell gel electrophoresis (SCG) assay was used to compare the occurrence of DNA damage in peripheral white blood cells in 6 trained (TR) and 5 untrained (UT) men after exhaustive exercise. The subjects completed an incremental treadmill test until exhaustion (maximal lactate: 12.9 +/- 1.7 in TR and 12.2 +/- 2.5 mmol.l-1 in UT). A clear and significant increase of DNA migration from 2.31 +/- 0.20 (TR) and 2.22 +/- 0.16 (UT) at rest to 2.65 +/- 0.30 (TR) and 3.00 +/- 0.41 tail moment (UT) was found 24 hours after exercise. Noteworthy is that the increase of DNA migration was significantly lower in TR (+ 18.7 +/- 6.8%) compared to UT (+ 35.7 +/- 8.9%). Plasma levels of malondialdehyde (MDA) were not significantly increased in TR and UT after exercise. At rest and 15 minutes after exercise MDA-values were significantly lower in TR compared to UT. In conclusion the present investigation demonstrates the occurrence of DNA damage in white blood cells following exhaustive exercise. This observation may be induced by oxidative stress. Our data suggest that adaptation to training seems to be capable of reducing free radical associated effects, such as DNA damage. Further investigations are needed to clarify the causal mechanisms and biological relevance of exercise-induced DNA damage.

Adaptation, Physiological↗
PubMed1996

[Diagnostic advantage by transthoracic and transesophageal echocardiography in acute ischemic infarct. A contribution to indications for transesophageal echocardiography].

The yield of TTE and TEE in identifying cardiac sources of embolism in patients with TIA or stroke was calculated from data from the Berlin Stroke Data Bank. High risk sources of embolism were detected by TTE in 4.2% with and in 1.6% of patients without evidence of cardiac disease from case history, clinical symptomatology, and ECG respectively. TEE yielded high risk sources of embolism in 10.6% of patients with and in 4.2% of patients without evidence of cardiac disease from case history, clinical symptomatology, ECG, and TTE respectively. Pathological findings were 12 atrial thrombi, 4 ventricular thrombi, and 1 atrial myxoma. 12 out of 14 atrial thrombi were only detected by TEE and not by TTE. There was a significant association of high risk cardiac sources of embolism with pial artery infarct pattern in CCT compared with lacunes. The yield of TEE in detecting high risk sources was not significantly associated with CCT infarct pattern probably due to the small numbers of investigations.

Adult↗
PubMed1996

[Neurosteroids--basic principles, anxiolysis and clinical applications].

Steroids which are synthesised de novo in the CNS are termed neurosteroids. In contrast to classical non-genomic steroid effects, neurosteroids interact with GABAa and NMDA receptors localized on the cell membrane. This mode of action implies an influence of neurosteroids on a variety of central nervous processes. More specifically, this compound class could act as an endogenous anxiolytic agent through modulation of the GABAa receptor complex, thereby presenting potential advantages over existing classes of anxiolytics, e.g. benzodiazepines, with regard to tolerance, dependence and abuse liability. The present paper reviews the current state of research in this field.

Animals↗
PubMed1996

Production and characterization of strain-specific monoclonal antibodies against outer membrane components of Azospirillum brasilense Sp245.

Several hybridoma cell lines producing murine monoclonal antibodies (MAbs) directed against outer membrane components of the Gram-negative rhizosphere bacterium Azospirillum brasilense Sp245 have been established and characterized. Whole bacterial cells were used as immunogens. Among the clones obtained, 14 hybridoma cell lines were selected for further characterization. Eight MAbs were strain-specific and 6 MAbs showed cross-reactivity with a closely related strain Azospirillum brasilense Sp246. According to the biochemical characterization of the antigenic determinants, MAbs were classified into four groups. The corresponding antigens were lipopolysaccharides (class 1) and an outer membrane protein (class 4), which is common to Azospirillum brasilense Sp245 and Azospirillum brasilense Sp246 as well as two outer membrane proteins (class 2 and class 3) that are characteristic for Azospirillum brasilense Sp245. The number of antigens per cell varied from 4000 (class 1) to 100 (class 4). In each class high affinity MAbs were identified, which made a sensitive direct quantification of Azospirillum brasilense Sp245 possible.

Animals↗
PubMed1996

Detection of DNA damage after hyperbaric oxygen (HBO) therapy.

Hyperbaric oxygen (HBO) therapy is successfully used for the treatment of a variety of conditions. However, exposure to high concentrations of oxygen is known to induce damage to cells, possibly due to an increased oxygen radical production. As reactive oxygen species also cause DNA damage, we investigated the DNA-damaging effect of HBO with the alkaline version of the single cell gel test (comet assay). Oxidative DNA base modifications were determined by converting oxidized DNA bases to strand breaks using bacterial formamidopyrimidine-DNA glycosylase (FPG), a DNA repair enzyme, which specifically nicks DNA at sites of 8-oxo-guanines and formamidopyrimidines. HBO treatment under therapeutic conditions clearly and reproducibly induced DNA damage in leukocytes of all test subjects investigated. Increased DNA damage was found immediately at the end of the treatment, while 24 h later, no effect was found. Using FPG protein we detected significant oxidative base damage after HBO treatment. DNA damage was detected only after the first treatment and not after further treatments under the same conditions, indicating an increase in antioxidant defences. DNA damage did not occur when the HBO treatment was started with a reduced treatment time which was then increased stepwise.

Adult↗
PubMed1996

Bilateral nephrectomy simultaneously with renal allografting does not alleviate hypertension 3 months following living-donor transplantation.

Severe hypertension prior to renal transplantation has traditionally been an indication for bilateral nephrectomy. The reasons for hypertension after successful renal transplantation are however many, and the impact of simultaneous bilateral nephrectomy (BN) in this setting has not been well documented. We retrospectively evaluated 158 living-donor renal graft recipients. BN had been performed in 76 patients at the time of the transplantation and 82 were not nephrectomized (controls). All received a triple immunosuppressive drug regimen. Before transplantation, patients in the BN group used 1.8 +/- 0.9 (mean +/- SD) antihypertensive drugs/day, significantly more than in the control group (1.3 +/- 0.8; P < 0.05). Three months after renal transplantation no difference was found (0.9 +/- 1.0 drugs/day in the BN group vs 1.0 +/- 0.8 drugs/day in the control group). No difference was found with respect to serum creatinine, whole blood cyclosporin A (CsA) concentration or blood pressure between the groups. The number of blood transfusions during the first week after transplantation was significantly increased in the BN group (66 SAG units vs 4 SAG units). The median hospitalization length was also longer in the BN group (21 days vs 16 days). In order to circumscribe the pre-transplant difference in use of antihypertensive medication we studied a subgroup of 62 hypertensive recipients (BN/control = 31/31) matched for number of antihypertensive drugs at the time of transplantation (2.3 +/- 0.5 drugs/day in the BN group, 2.1 +/- 0.3 drugs/day in the control group). Three months after transplantation the use of antihypertensive drugs remained the same in the two groups (1.3 +/- 1.0 drugs/day in the BN group vs 1.3 +/- 0.9 drugs/day in the control group). At 3 months no difference was found between the two hypertensive subgroups regarding serum creatinine, whole blood CsA and haemoglobin concentration or systolic blood pressure. However, the BN patients were younger than the control group (38 +/- 10 years vs 49 +/- 11 years, P < 0.05) and this may explain the marginally lower diastolic blood pressure observed in the BN group (82 +/- 10 mmHg vs 87 +/- 7 mmHg, P < 0.05). It is concluded that, in recipients of living-donor grafts, bilateral nephrectomy performed at the time of transplantation did not influence the number of antihypertensive drugs used 3 months after a successful transplantation. Bilateral nephrectomy did however increase the need of blood transfusions during the first week after transplantation and also the hospitalization length.

Adult↗
PubMed1996

Emended description of Herbaspirillum; inclusion of [Pseudomonas] rubrisubalbicans, a milk plant pathogen, as Herbaspirillum rubrisubalbicans comb. nov.; and classification of a group of clinical isolates (EF group 1) as Herbaspirillum species 3.

[Pseudomonas] rubrisubalbicans, a mild plant pathogen. Herbaspirillum seropedicae, and EF group 1 strains (clustered by an immunological method) were investigated by a polyphasic approach with DNA-rRNA and DNA-DNA hybridizations and auxanography on 147 substrates. Our results show that they all belong to the genus Herbaspirillum. In addition to H. seropedicae, two other species are described: Herbaspirillum rubrisubalbicans and a new unnamed species, Herbaspirillum species 3, containing mainly strains of clinical origin. The three species can be differentiated on the basis of their auxanographic features and DNA-DNA similarities. The type strain of H. rubrisubalbicans is NCPPB 1027 (=LMG 2286); representative strains of the third Herbaspirillum species are strains CCUG 189 (=LMG 5523), CCUG 10263 (=LMG 5934), and CCUG 11060 (=LMG 5321). It has been confirmed that H. rubrisubalbicans is an endophytic diazotroph. It colonizes the roots, the stems, and predominantly the leaves of sugarcane (Saccharum spp.), while Herbaspirillum seropedicae colonizes in large numbers many different species of the Gramineae. Both diazotrophic Herbaspirillum species could be differentiated with meso-erythritol and N-acetylglucosamine. Oligonucleotide probes based on partial sequences of the 23S rRNA of H. seropedicae and H. rubrisubalbicans (HS and HR probes, respectively), were constructed and used as diagnostic probes.

Base Sequence↗
PubMed1996

Presence and removal of arteriovenous malformation: Impact of regional cerebral blood flow, as assessed with xenon/CT.

In 26 patients with supratentorial AVMs and 1 patient with a dural arteriovenous fistula, the regional cerebral blood flow (rCBF) was assessed by means of xenon-enhanced computed tomography (Xe/CT) before and after complete resective surgery. Each assessment comprised an acetazolamide challenge in order to check the cerebrovascular reserve capacity. While scanning through the AVM was purposely avoided, a single brain slice at the level of the basal ganglia was examined. Five regions of interest (ROIs) in gray matter of the AVM-bearing hemisphere were compared to the contralateral ROIs and categorized into 7 CBF groups. Interhemispherical differences exceeding 20% of the contralateral value in either direction were considered to the significant. AVM-related (AVM-R) and AVM-non-related (AVM-NR) ROIs were looked at separately. Before surgery, all possible rCBF patterns were found, including a normal rCBF as well as a reduced or an increased rCBF, either in AVM-R, AVM-NR, or both. After AVM removal, a rCBF increase in AVM-R is relatively rare, whereas a rCBF decrease is twice as frequent. A rCBF drop to a level of impaired reserve capacity correlates with the occurrence of post-operative neurological deficit.

Acetazolamide↗
PubMed1996

Changes in late auditory evoked potentials induced by corticotropin-releasing hormone and corticotropin fragment 4-9 in male controls.

In order to investigate influences of corticotropin-releasing hormone (CRH) and corticotropin fragment (adrenocorticotropic hormone, ACTH, 4-9) on auditory perception processes, 10 subjects received either a placebo (sodium chloride 0.9%), CRH (100 micrograms) or ACTH 4-9 (Hoe 427, 300 micrograms) intravenously on different days. Late auditory evoked potentials (AEP) were computed and further analyzed using the brain electric source analysis method. As expected, CRH administration was followed by a rise in plasma cortisol and ACTH concentrations, whereas the injection of the ACTH 4-9 fragment did not alter plasma cortisol concentrations. In contrast to these different hormonal responses, both CRH and ACTH 4-9 modulated AEP in a similar manner, differing in quantity rather than in quality. The changes in AEP after the administration of ACTH 4-9 were most likely induced by a direct CNS action, whereas for the CRH effects, an indirect mechanism throughout the release of endogenous ACTH must be considered.

Adrenocorticotropic Hormone↗
PubMed1996

Persisting effect of Ca(2+)-channel blockers on left ventricular function in hypertrophic cardiomyopathy after 14 years' treatment.

Ca(2+)-channel blockers of the verapamil type have been reported to exert a beneficial effect on clinical symptoms and survival rates in hypertrophic cardiomyopathy. The effects of verapamil have been attributed predominantly to an improved diastolic filling. It is unknown whether an effect on diastolic filling persists in these patients after long-term treatment. Fourteen patients (12 men, 2 women, median age fifty-one [thirty-two to fifty-five] years) with hypertrophic cardiomyopathy were included in the study. Patients had been treated with verapamil 240-480 mg/d or gallopamil 150-200 mg/d for fourteen (seven to seventeen) years. The effect of a withdrawal of Ca(2+)-channel blockers on parameters of left ventricular diastolic function was evaluated at rest and during exercise in patients with hypertrophic cardiomyopathy after long-term therapy. Investigations were performed at rest and during supine ergometric exercise during ongoing Ca(2+)-channel blocking therapy and after five (four to nine) days' withdrawal (control). Pulsed Doppler echocardiography was used to record diastolic mitral flow profiles from an apical four-chamber view. Withdrawal of Ca(2+)-channel blockers of the phenylalkylamine type after long-term treatment of hypertrophic cardiomyopathy resulted in a significant reduction of early diastolic inflow velocity at rest and during exercise. In conclusion, these results indicate a persistent improvement of early diastolic filling by Ca(2+)-channel blockers even after long-term treatment.

Adult↗
PubMed1996

Leprosy (Hansen's disease) in South Dakota.

Worldwide Hansen's disease is an important and relatively common disease, but is still very rare in South Dakota. Two patients are described to help demonstrate the wide variety of clinical manifestations associated with Hansen's disease. Since the clinical appearance of Hansen's disease is highly variable, the following six forms of Hansen's disease are described: Indeterminate, tuberculoid (TT), borderline tuberculoid (BT), borderline (BB), borderline lepromatous (BL), and lepromatous leprosy (LL). In addition, three well-recognized reactional forms of leprosy are also described: Type 1 (lepra reaction), type 2 (erythema nodosum leprosum), and type 3 (Lucio's phenomenon). While the disease affects primarily the skin and nerves, health care providers of all disciplines should remain alert for this disease which can present with a high degree of clinical variability.

Adult↗
PubMed1996

[An absent correlation between antioxidant blood concentrations and the remission response of preoperatively treated breast carcinomas].

PURPOSE: Deleterious effects of ionizing radiation and some chemotherapeutic agents are predominantly caused by reactive oxygen agents which are detoxified by antioxidants. This study was designed to evaluate the modifying effects of vitamin A-, vitamin E- and selenium serum concentrations and glutathione peroxidase activity on preoperative radio- and chemotherapy of breast cancer. PATIENTS AND METHODS: Tumor volume, vitamin A-, vitamin E-, selenium serum concentrations and glutathione peroxidase activity in circulating erythrocytes were determined in 40 patients with breast cancer before treatment. Interstitial radiohyperthermia was given initially using a single dose of 10 Gy (HDR) combined with hyperthermia between 43.5 to 44.5 degrees C over 60 minutes followed by external beam radiotherapy with 50 Gy in 5 weeks. All patients received anthracyline or anthrachinone containing chemotherapy. Tumor response was determined by histopathological examination. Patients with complete and incomplete remissions were compared using the Wilcoxon test. Pre- and posttreatment tumor-volume differences were correlated with antioxidant concentrations (Spearman correlation coefficient). RESULTS: Twenty patients (50%) achieved a complete histopathologic tumor regression. This high complete remission rate was not related to the antioxidants under investigation (vitamin A: p = 0.32, vitamin E: p = 0.44, selenium: p = 0.68, glutathione peroxidase: p = 0.3). There was no correlation to pre- and posttreatment tumor-volume-differences either (vitamin A: p = 0.89, vitamin E: p = 0.67, selenium: p = 0.41, glutathione peroxidase: p = 0.87). CONCLUSIONS: In this study serum concentrations of antioxidants had no modifying influence on tumor response in breast cancer patients following induction radio-chemotherapy and subsequent surgery. Further studies measuring tissue levels could clarify if there is any modifying influence of antioxidants on tumor remission.

Adult↗
PubMed1996

[Total symptom-oriented and psychodynamic concept in inpatient treatment of anorexia nervosa. A quasi-experimental comparative study of 40 admission episodes].

Inpatient treatment programs for severely anorectic patients often combine or integrate psychodynamic approaches with an explicit focus on symptoms. There is a dearth of studies evaluating treatments, let alone in a controlled way. In a quasi-experimental design we compare the normalization of body weight in the 20 consecutive admission episodes before ("PD") and the 20 episodes after ("PD & SY") introduction and integration of explicit symptom orientation derived from the St. Georges model (Crisp 1980) on a psychoanalytically oriented psychosomatic ward. All patients fulfill ICD-10 criteria for either restrictive (F50.00) or bulimic (F50.01) anorexia nervosa. In addition to AN(C)OVAS growth curve modelling and multi state analysis, a variant of survival analysis, are used to model the shape and temporal course of treatment responses. Clinical features at admission and total duration of treatment and drop-out rates are comparable. The PD & SY group reaches target weight significantly more frequently (14 vs. 5 episodes, p = 0.023) and with a much higher total probability (0.70 vs. 0.25 in the PD group, Cox regression p = 0.002). After a phase of adaptation the treatment team feels relieved by the more systematically structured approach and is now able to treat a far larger number of patients. It does not seem justifiable anymore to withhold anorectic patients explicitely symptom-oriented treatment components. These and other conclusions for clinical practice and research are discussed.

Adolescent↗