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Biomedical subjects

J Hoffmann

Publications and source records attributed to J Hoffmann.

At least 163 records · Page 9Linked to original sources
PubMed1996

IVBT-documented platelet function correlates with flow cytometric data.

Thrombocytopenic patients with identical platelet counts often show different bleeding tendencies owing to significant differences in the platelet function. This could be demonstrated by the in vitro bleeding test (IVBT). Using flow cytometry, we tried to find characteristics of platelet antigen expression in order to explain these differences in function. Thirty patients with bone marrow hypoplasia receiving 65 platelet transfusions (mainly from a cell separator) were observed for 3 to 29 days. Size, granulation and fluorescence of platelet-rich plasma (n = 522 samples) were evaluated using monoclonal antibodies against GP IIIb (collagen receptor), GP IIb/IIIa (fibrinogen receptor) and GP Ib (thrombin receptor). We defined separate gates for each antibody using the results from 50 normals and by laying an orthograde cross over the gate to divide the gate into four equal quadrants. The platelet populations were divided into four different groups according to the occlusion time (OT) of the IVBT and the Simplate time (ST). The thrombocytes with the most impaired function (OT > or = 485 s/ST > 30 min) had significantly less platelet fluorescence when marked with antibodies against GP IIIb and GP Ib than those with short OT and ST (OT < 100 s/ST < 15 min). Similar results were obtained when evaluating the data relative to the bone marrow status: patients with < 1000 WBC/microliters showed significantly less platelet fluorescence when marked with anti-GP IIIb and anti-GP Ib than thrombocytopenic patients, who had a spontaneous platelet rise beyond 30,000 platelets/microliters a few days later. One day after platelet transfusion, significantly more platelets with high GP IIIb and Ib expression could be found. We were also able to document better transfusion efficacy of platelet concentrates with high GP IIIb and Ib expression. Finally, patients with high bleeding scores showed less GP Ib expression on the platelets than patients with low bleeding scores. In summary, the IVBT-documented platelet function clearly corresponded to an increased expression of the collagen receptor and the thrombin receptor of platelets.

Bleeding Time↗
PubMed1996

[Stimulus and reaction patterns in serial choice reactions].

In serial choice-reaction-tasks reaction times decrease faster if the sequence of stimuli is structured rather than of being random. Nevertheless, the issue whether this structure-specific improvement of performance is due to the structure of the stimulus- or the response-sequences is controversially discussed. After a review of the corresponding literature, an experiment will be reported which was designed to contribute to this issue. Contrary to the present experiments, which exclusively analysed effects of statistical redundancy, relational patterns are introduced into the sequences of stimuli as well as into the sequences of responses. These relational patterns were varied independently of each other. The data reveal strong effects of the relational patterns in the sequence of responses, whereas the relational patterns of the stimulus sequences were not systematically effective. Furthermore, the data suggest that the relational structure of the response sequences especially favours the formation of "motor-chunks". In the discussion it is emphasized that effects of relational patterns on serial choice reactions are not yet adequately regarded, neither in experimental research nor in the theoretical accounts.

Adult↗
PubMed1996

[Development of a mandibular model for evaluating and optimizing the design of osteosynthesis materials using finite element analysis].

The present study was designed to investigate biomechanical and clinical changes in the mandibular complex by means of finite element analysis. An analytical model developed from human native mandibles was used for this model, CT image data were transferred to a computer, and an edge extraction program generated the cross-section of bone by specifying a range of CT values for each slice. Pixel data from the CT scan were converted into a vector of points (x, y, z) which can specify the boundaries of bone. Lateral surfaces are defined by stacking up the slices and making use of the vectorized data. The constructed model was used as input data for the finite element analysis. The models were solved for stresses and forces. The highest principal stresses occurred at the bite point, anterior aspects of the coronoid processes, symphyseal region, and right and left sides of the mandibular corpus. For further investigation muscular structures have to be integrated to establish a model, which can be analysed under multivariate aspects.

Biomechanical Phenomena↗
PubMed1996

Alcohol and rhythm disturbance: the holiday heart syndrome.

The association between alcohol use and rhythm disturbances, particularly supraventricular tachyarrhythmias in apparently healthy people is called "holiday heart syndrome". The syndrome was first described in persons with heavy alcohol consumption, who typically presented at weekends or after holidays, but it may also occur in patients who usually drink little or no alcohol. The most common rhythm disorder is atrial fibrillation, which usually converts to normal sinus rhythm within 24 hours. The incidence of the holiday heart syndrome depends on the drinking habits of the studied population. The holiday heart syndrome should be considered particularly as a diagnosis in patients without overt heart disease presenting with new onset atrial fibrillation. Though recurrences occur, the clinical course is benign and specific antiarrhythmic therapy is usually not warranted.

Alcohol Drinking↗
PubMed1996

[What does it mean for men to be nurses?].

In the course of a study concerning the vocational self-concept of men occupied in female-dominated fields male nurses were questioned about a broad range of job related aspects: access to the profession, experiences in the work with patients and teammates, public image, socialization, job satisfaction and the like. The findings help to enlighten male nurses' views of this job and of themselves as its holders. The men perceive special handicaps and problems but opportunities as well. At the time of their vocational choice they aimed primarily at the social and not at the former or medical aspect; today it is still the first of those to which they attach importance. Working as a man in this female-dominated field turns out to be a special opportunity for individual personal growth.

Career Choice↗
PubMed1996

[Value of old and new electrocardiography criteria for differential diagnosis between ventricular tachycardia and supraventricular tachycardia with bundle branch block].

In 240 tachycardias with wide QRS-complex (> or = 120 ms), the value of the "old" ECG criteria published in 1978 by Wellens and coworkers was compared to the "new" ECG criteria published in 1991 by Brugada and coworkers for the differential diagnosis of tachycardias with wide QRS-complex. As main result of the study, it could be demonstrated that with the old as well as with the new ECG criteria a sensitivity of more than 90% for the correct diagnosis ventricular tachycardia can be reached. The specificity of the old and new ECG criteria for the diagnosis ventricular tachycardia is 70% and 72% for tachycardias with right bundle branch block configuration and 87% each for tachycardias with left bundle branch block configuration. The combined use of the old and the new ECG criteria in this study could not increase sensitivity and specificity for the diagnosis of ventricular tachycardia. Therefore, it does not appear to be important for the differential diagnosis of tachycardias with wide QRS-complex whether the old or the new step diagnostic criteria are being used, but that either the old or the new ECG criteria are being used correctly.

Adult↗
PubMed1995

[Menstrual cycle and surgery of breast cancer. Point of time for the surgery of primary breast cancer in connection with menstrual cycle is without prognostic significance].

From 1977 to 1989 6488 patients under fifty years with primary breast cancer were registered in the nationwide Danish Breast Cancer Cooperative Group (DBCG). Among these information on last menstrual period prior to surgery was available in 1635 cases which constitute the study group of the present analysis. The group was representative of the total group with regard to prognostic factors and survival. In the study group time of surgery in relation to last menstrual period was found to have no influence on five- and ten year survival.

Adult↗
PubMed1995

The role of neuropeptide Y in the antiobesity action of the obese gene product.

Recently Zhang et al. cloned a gene that is expressed only in adipose tissue of the mouse. The obese phenotype of the ob/ob mouse is linked to a mutation in the obese gene that results in expression of a truncated inactive protein. Human and rat homologues for this gene are known. Previous experiments predict such a hormone to have a hypothalamic target. Hypothalamic neuropeptide Y stimulates food intake, decreases thermogenesis, and increases plasma insulin and corticosterone levels making it a potential target. Here we express the obese protein in Escherichia coli and find that it suppresses food intake and decreases body weight dramatically when administered to normal and ob/ob mice but not db/db (diabetic) mice, which are thought to lack the appropriate receptor. High-affinity binding was detected in the rat hypothalamus. One mechanism by which this protein regulated food intake and metabolism was inhibition of neuropeptide-Y synthesis and release.

Animals↗
PubMed1995

Thrombocytopenia-adapted in vitro bleeding test assesses platelet function in thrombocytopenic patients.

Platelet counts do not always reflect the true bleeding risk in chronically thrombocytopenic patients, and the posttransfusion platelet increments do not necessarily demonstrate that therapeutic efficacy. There are no easy and reliable tests yet permitting the determination of platelet function in thrombocytopenic patients. The in-vitro bleeding test (IVBT) with the Thrombostat 4000 proved to be a very sensitive and specific test for the detection of platelet disorders. In order to become suitable for the investigation of thrombocytopenic blood with platelet count between 5 x 10(9)/L and 50 x 10(9)/L, special modifications were necessary. We report on the evaluation of two thrombocytopenia-adapted modifications (TP-IVBT 150/120), first with blood of healthy donors made thrombocytopenic (three experiments with six blood samples each of different platelet concentrations and identical hematocrit) and then in a clinical study on 77 thrombocytopenic patients (69 with bone marrow hypoplasia, eight with autoimmune thrombocytopenia) receiving 267 platelet transfusions. The patients were followed over 15 days on average (1-67 days) by daily examinations (total 1,285 observation days). Most TP-IVBT measurements were carried out in triplicate, using the modification with the 120-microns filter (TP-IVBT 120) because it proved to be superior to the other modification. Additionally, cell counts, hematocrit, body temperature, platelet volume, platelet distribution width, expression of CD 36, 41a, 42b on platelets, Simplate bleeding time, and detailed analysis of bleeding signs were performed for the calculation of a bleeding score. There was a close correlation between TP-IVBT and platelet counts with thrombocytopenic normal blood (r2 = 0.81-0.94). This indicated the suitability of this test modification to examine platelet function in thrombocytopenic patients. The clinical study showed that the TP-IVBT helped at least to determine the platelet-related bleeding risk in thrombocytopenic patients. It allowed differentiation between hypoplastic and autoimmune thrombocytopenia in most cases. In addition, significant differences in platelet function of various diseases and of different bone marrow regeneration could be demonstrated. The TP-IVBT is well-suited for the control of platelet transfusion efficacy and may replace the in-vivo bleeding time in most cases. On the other hand, the test still shows too much of a variation and involves too much labor and cost for routine application.

Bleeding Time↗
PubMed1995

Invasive electrophysiological evaluation of patients with sleep apnoea-associated ventricular asystole-methods and preliminary results.

Twelve patients (aged 48 +/- 12 y) with ventricular asystole of >3 s due to complete atrioventricular (AV) block (n = 8), sinoatrial (SA) block or sinus node arrest (n = 3) or both (n = 1) associated with obstructive sleep apnoea underwent invasive electrophysiological evaluation of sinus node function and AV conduction properties before and after administration of atropine (0.02 mg kg-1). Ventricular asystole lasted for 5.9 +/- 2.8 s (range 3.1-13 s). Sinus node function was assessed by measurement of sinus node recovery time, sinoatrial conduction time, and the response of sinus rate to atropine. Parameters of AV-conduction assessment included AH- and HV-intervals, AV- and VA-Wenckebach periods, and effective refractory period of the AV node before and after atropine. Sinus node function was normal in 11 of the 12 study patients and moderately abnormal in 1 patient. AV-nodal function was normal in 8 patients and moderately abnormal in 4 patients. A slightly prolonged HV-interval (59-63 ms) was present in 6 patients. Intra- or infra His block was not observed in any patient. In conclusion, normal or only moderately abnormal electrophysiological findings in patients with sleep apnoea-associated ventricular asystole suggest that a neurally mediated cardioinhibitory reflex may cause ventricular asystole in these patients. This sleep apnoea-triggered 'vasovagal' reflex may unmask pre-existing mild to moderate structural abnormalities of the AV conduction system.

Journal Article↗
PubMed1994

Parietal cell vagotomy. A 23-year study.

OBJECTIVE: The authors studied the long-term ulcer recurrence rate after elective parietal cell vagotomy (PCV) for duodenal, pyloric, or prepyloric ulcers. SUMMARY BACKGROUND DATA: Recurrent ulceration rates of around 10% are reported after PCV. Recurrence rates are, however, proportional to the duration of follow-up. Series presenting long-term follow-up are sparse in the literature. METHODS: From 1969 to 1979, 350 patients underwent elective PCV. Three hundred forty-seven accessible patients were observed prospectively at intervals of 1 to 5 years to detect recurrent ulcers. The median duration of follow-up was 140.2 months (range 1 month-22.75 years). RESULTS: Seventy-six of the 347 patients (21.9%) developed recurrent ulcers. Calculation of the integrated ulcer recurrence rate indicates a constant monthly recurrence risk of 0.16%. Recurrences occurred as late as 17 3/4 years after operation. Eighty per cent of the recurrences occurred after 10 years of follow-up. CONCLUSION: The results confirm that the rate of recurrent ulceration after PCV is proportional to the duration of follow-up.

Actuarial Analysis↗
PubMed1994

Efficacy of 24-week monotherapy with acarbose, glibenclamide, or placebo in NIDDM patients. The Essen Study.

OBJECTIVE: To compare the different therapeutic principles of alpha-glucosidase inhibitors and sulphonylureas as first-line treatment in non-insulin-dependent diabetes mellitus (NIDDM) patients with dietary failure. RESEARCH DESIGN AND METHODS: Ninety-six NIDDM patients (35-70 years of age, body mass index [BMI] < or = 35), insufficiently treated with diet alone (HbA1c 7-9%) were randomized into three groups and treated for 24 weeks with acarbose, glibenclamide, or placebo. Efficacy, based on fasting blood glucose (BG), BG 1 h after ingestion of standard breakfast (postprandial), serum insulin, postprandial insulin increase, and HbA1c; and tolerability, based on subjective symptoms and laboratory values, were investigated every 6 weeks. Efficacy evaluation was valid for 85 patients. RESULTS: The test drugs were dosed as follows: 100 mg acarbose (A) three times a day, 1 placebo tablet three times a day, 3.5 mg glibenclamide tablets dosed 1-0-0 or 1-0-1, mean dose 4.3 mg/day. Compared with the placebo, both drugs showed the same mean efficacy on fasting BG (-1.4 mM with acarbose, -1.6 mM with glibenclamide), 1-h postprandial BG (-2.2 mM with acarbose, -1.9 mM with glibenclamide), and HbA1c (-1.1% with acarbose, -0.9% with glibenclamide); but they showed a marked difference in 1-h postprandial insulin values (-80.7 pM with acarbose, 96.7 pM with glibenclamide). The mean relative insulin increase (1-h postprandial) was 1.5 in the placebo group, 1.1 in the acarbose group, and 2.5 in the glibenclamide group. No changes in body weight could be observed. No adverse events were seen under placebo. Acarbose led to mild or moderate intestinal symptoms in 38% of patients. Glibenclamide led to hypoglycemia, which could be solved by dose reduction, in 6% of patients. No dropouts occurred in any of the treatment groups. CONCLUSIONS: Acarbose and glibenclamide are effective drugs for the monotherapy of NIDDM patients when diet alone fails. Because postprandial insulin increase has been shown to be associated with increased risk for cardiovascular disease, acarbose, which lowers pp increase, may be superior to glibenclamide, which elevates postprandial insulin increase.

Acarbose↗
PubMed1994

[Accelerated idioventricular rhythm].

The term accelerated idioventricular rhythm describes an ectopic ventricular rhythm with 3 or more consecutive ventricular premature beats with a rate faster than the normal ventricular intrinsic escape rate of 30 to 40 beats per minute, but slower than ventricular tachycardia. Accelerated idioventricular rhythm differs from ventricular tachycardia by additional features such as the onset with a long coupling interval, the end by a gradual decrease of the ventricular rate or increase of the sinus rate and, last but not least, by a good prognosis. Clinically, accelerated idioventricular rhythm can occur in any form of structural heart disease and occasionally in adults or children without structural heart disease. Accelerated idioventricular rhythm most often can be seen in patients with coronary artery disease. Its occurrence after thrombolysis during acute myocardial infarction is a marker of successful reperfusion. Since accelerated idioventricular rhythm is usually hemodynamically well tolerated and not associated with malignant ventricular tachycardias; as a rule, no specific treatment other than care of the underlying heart disease is necessary. The present overview discusses electrocardiographic criteria, possible mechanisms, and the clinical significance of accelerated idioventricular rhythms.

Accelerated Idioventricular Rhythm↗