Search PubMed⌕ Search

Biomedical subjects

J Hoffmann

Publications and source records attributed to J Hoffmann.

At least 127 records · Page 7Linked to original sources
PubMed1998

[Artificial bradycardias due to tape-running problems of old long-term ECG records].

Artificial bradycardias due to tape-running alterations of old long-term ECG recorders were observed with increasing frequency in the last 2 years at our hospital. To document the extent of this problem, 115 consecutive 24-hour long-term ECG recordings of 10 still used tape recorders with an age of 12 +/- 4 years were examined. Analysis of the tapes with a new analysis system revealed artificial bradycardias with rates of 10 to 40/min in 22 of 115 long-term ECG recordings (19%). These artificial bradycardias were observed in 4 out of 10 examined tape recorders (40%). Three of 4 concerned recorders were 14 years old at the time of examination, and one recorder was only 5 years old. Artificial bradycardias were caused by extensive alterations of tape-running speed in all cases. Diagnostic proof of artificial bradycardias due to tape running alterations on long-term ECG are simultaneous with prolonged RR-intervals occurring increases in all ECG times including P-width. PQ-time, QRS-width and QT-duration with otherwise unchanged ECG morphology. To avoid prolonged hospital stays or therapeutic mistakes like unnecessary pacemaker implantation, especially older long-term ECG-tape recorders should be checked regularly and, if necessary, be replaced by new devices.

Artifacts↗
PubMed1998

[Using individually designed ceramic implants for secondary reconstruction of the bony orbit].

The use of autogenous transplants and the application of intraoperatively customised alloplastic materials show, in cases of secondary orbital reconstruction, a higher postoperative morbidity caused by additional approaches to the transplant donor site. On the other hand, thorough surgical exploration and fitting of the transplants or alloplastic materials greatly prolongs operating times. For these reason we designed ceramic implants (Bioverit) on the basis of stereolithography models and prefabricated them using a commercially available dental copy milling unit (Celay). In five cases up until now seven customised implants have been inserted for reconstruction of the lamina papyracea, zygomatic complex and infraorbital floor and rim. Encouraged by the good postoperative aesthetic and functional results, with significantly reduced operating times and morbidity in all cases, we will continue to take this technique into account for reconstruction after complex orbital fractures.

Adult↗
PubMed1998

Intraoperative and postoperative kinetics of serum tumor markers in patients with oral carcinoma.

PURPOSE: There are no reliable laboratory procedures to monitor intraoperative tumor antigen dispersal in patients with squamous cell carcinoma of the head and neck. This study evaluated the use of serologic parameters as perioperative indicators of systemic manifestations. PATIENTS AND METHODS: In 28 patients, serial measurements of different tumor markers (squamous cell carcinoma antigen, carcinoembryonic antigen, carbohydrate antigen 19.9, carcinoma antigen 125) were made preoperatively, intraoperatively, and postoperatively at short intervals to determine the influence of tumor ablation on the antigen concentration in the serum. A microparticle enzyme immunoassay was used for the serologic analysis. RESULTS: Squamous cell carcinoma antigen showed elevated serum levels preoperatively, which increased intraoperatively and decreased significantly postoperatively. The serologic examinations in the control group and the other tumor markers showed no correlation with the clinical situation. CONCLUSIONS: The results suggest that the titer of squamous cell carcinoma antigen in serum has a positive correlation with the tumor burden and the operative trauma in the case of surgery. These results support the value of intraoperative and postoperative serum antigen monitoring.

Adult↗
PubMed1998

Programmed ventricular stimulation for arrhythmia risk prediction in patients with idiopathic dilated cardiomyopathy and nonsustained ventricular tachycardia.

OBJECTIVES: This study investigated the role of programmed ventricular stimulation (PVS) for arrhythmia risk prediction in patients with idiopathic dilated cardiomyopathy (IDC) and spontaneous nonsustained ventricular tachycardia (VT). BACKGROUND: Nonsustained VT in patients with IDC has been associated with a high incidence of sudden cardiac death. METHODS: Over the course of 4 years, 34 patients with IDC, a left ventricular (LV) ejection fraction < or = 35%, and spontaneous nonsustained VT underwent PVS. All patients were prospectively followed for 24+/-13 months. RESULTS: Sustained ventricular arrhythmias were induced in 13 patients (38%). Sustained monomorphic VT was induced in three patients (9%), and polymorphic VT or ventricular fibrillation (VF) in another 10 patients (29%). No sustained ventricular arrhythmia could be induced in 21 study patients (62%). Prophylactic implantation of third-generation defibrillators (ICDs) with electrogram storage capability was performed in all 13 patients with inducible sustained VT or VF, and in nine of 21 patients (43%) without inducible sustained VT or VF. There were no significant differences between the additional use of amiodarone, d,I-sotalol, and beta-blocker therapy during follow-up in patients with and without inducible VT or VF. During 24+/-13 months of follow-up, arrhythmic events were observed in nine patients (26%) including sudden cardiac deaths in two patients and ICD shocks for rapid VT or VF in seven patients. Arrhythmic events during follow-up occurred in four of 13 patients with inducible ventricular arrhythmias compared with five of 21 patients without inducible ventricular arrhythmias at PVS (31% vs. 24%, p=NS). CONCLUSION: PVS does not appear to be helpful for arrhythmia risk stratification in patients with IDC, a left ventricular ejection fraction < or =35%, and spontaneous nonsustained VT. Due to the limited number of patients, however, the power of this study is too small to exclude moderately large differences in outcome between patients with IDC with and without inducible VT or VF.

Adolescent↗
PubMed1998

Relevance of SCC-Ag, CEA, CA 19.9 and CA 125 for diagnosis and follow-up in oral cancer.

The prognosis of oral cavity carcinoma is limited by recurrent disease or lymph node metastasis. Secondary to surgery and radiotherapy, anatomical structures are often severely changed and make early diagnosis of renewed tumour growth by clinical and radiological examination difficult. We studied the course of serum SCC-Ag, CEA, CA 19.9 and CA 125 in 121 patients with untreated squamous cell carcinoma of the head and neck (SCCHN) before and after therapy and evaluated their relevance for diagnosis and follow-up in oral cancer. CA 19.9 and CA 125 seemed to be useless for this tumour entity. CEA resembled more the alcohol consumption and smoking habits of the patients examined than their state of disease. Only SCC-Ag correlated with the tumour burden and represented the disease course. In the event of relapse, half the patients had an exponential increase in SCC-Ag, 1-2 months prior to diagnosis.

Alcoholism↗
PubMed1998

Complications after microsurgical tissue transfer in the head and neck region.

In recent years, the use of microsurgically re-anastomosed free transplants has become a proven technique for the reconstruction of defects in the head and neck region, which is demanding from both aesthetic and functional points of view. A retrospective catamnestic study on 227 free tissue transfers in the Department for Oral and Maxillofacial Surgery at the University of Tübingen showed good healing with relatively low failure rates of the transplants used. A significant proportion of local complications, arising postoperatively, was to some degree due to pre-existing medical conditions, tumour-specific pretreatments and the particular wound-healing situation found in head and neck interventions. The highest relative rate of complications at the site of origin was seen amongst osteomuscular transplants (20%) whilst (fascio) cutaneous and visceral transplants were found to result in a low percentage of problems (4%). In contrast, the healing of iliac crest transplants was accompanied by various local complications in 12% of the cases, slightly higher than 20% amongst (fascio) cutaneous and abdominal transplants and well above 30% for latissimusdorsi and scapular transplants. General complications, in particular of a respiratory and/or psychiatric nature, were found in 23% of the patients.

Adult↗
PubMed1998

Experiences with a minimally invasive surgical technique for the treatment of coronary artery multivessel disease in 100 patients.

OBJECTIVE: The treatment of coronary single vessel disease under minimally invasive surgical conditions was followed by the treatment of coronary multivessel disease using a new technique. METHODS: Using this technique 100 patients (80 male, 20 female, median age 61.0+/-8.9 years, ranged from 39 to 82 years) with coronary single vessel disease, double vessel disease or multivessel disease were treated between November 1996 and December 1997. Via a small (6-9 cm) left lateral chest incision in the second or third intercostal space, the left internal thoracic mammary artery (LIMA) was harvested and access to the central portion of the heart including the ascending aorta was obtained. In parallel, saphenous vein segments were harvested. Arterial cannulation was instituted via the ascending aorta, thus avoiding retrograde flow. In all patients except three the LIMA was used for the left anterior descending artery (LAD). In addition vein grafts were used for revascularization of the other coronary arteries. All cardiac anastomoses were performed during cardioplegic arrest after external aortic cross clamping and antegrade application of cardioplegia. RESULTS: No death or intraoperative complications were observed in this series. The median hospital stay was 6.0+/-1.4 days (median+/-SEM). Postoperative complications were reexplored for bleeding (n = 1), delayed wound healing (n = 2), wound infections (n = 4), lymphatic fistulas (n = 4), and a chest wall hernia (n = 1). CONCLUSIONS: This minimally invasive surgical technique presents a safe alternative to conventional coronary artery surgery avoiding sternotomy related complications and decreasing hospital stay and morbidity.

Adult↗
PubMed1998

Management of complex orbital fractures.

Fractures of the orbit place the globe and associated structures at significant risk. Management of these fractures requires a thorough ophthalmic evaluation and precise imaging. Contemporary surgical approaches allow the surgeon to repair these injuries with minimal secondary cosmetic deformities and should avoid injury to the globe. A principle goal of therapy is to anatomically reduce fracture segments and to restore a normal orbital volume. Reconstitution of a normal orbital volume and support for the globe will prevent post-injury enophthalmos and globe malposition. The evaluation, imaging, exposure, and repair of orbital fractures is reviewed. Prevention and management of complications is also discussed. The causes of and prevention of blindness is discussed. Application of these techniques should allow for the repair of orbital fractures in a single stage with minimal morbidity.

Adult↗
PubMed1998

Applicability of the Kubelka-Munk theory for the evaluation of reflectance spectra demonstrated for haemoglobin-free perfused heart tissue.

Reflectance spectrometry is a useful tool for studying in vivo kinetic changes in the oxygen saturation of haemoglobin and myoglobin as well as the redox state of cytochromes. A method is given which allows the quantification of tissue reflectance spectra using multicomponent analysis. This method utilizes the Kubelka-Munk theory for modelling the measured tissue spectra. To test this approach, reflectance spectra of a haemoglobin-free perfused guinea pig heart were measured by a fast scanning spectrophotometer (100 spectra/s, spectral resolution 1.0 nm) and evaluated using the component absorbance spectra measured separately. A relative mean spectral residual error of 0.15% was achieved by least-squares fitting. Using statistical error propagation, oxygenation of myoglobin is obtained within a relative precision of 1%, and the redox state of cytochromes aa3 and c are determined simultaneously within a margin of 3%; the results for the redox-state of cytochrome b, however, are less precise. Special component error functions are presented to provide a reliability measure for the concentration prediction using this multicomponent assay. The consistency of the theory and the component absorptivity data is tested by regressing the actual concentrations obtained for each of the redox pair components during the various states of tissue oxygenation. A method is described for the recognition and reduction of systematic errors.

Animals↗
PubMed1998

Orbital reconstruction with individually copy-milled ceramic implants.

Diagnostic advances such as computed tomography and new surgical techniques have dramatically improved both the functional and aesthetic outcome of orbital reconstructions. Taking a further approach, we designed ceramic implants (Bioverit) on the basis of stereolithographic models. After copy milling a resin template with a commercially available dental unit (Celay), the prefabricated implants were inserted for reconstruction of the lamina papyracea (n = 1), zygomatic complex (n = 2), infraorbital floor (n = 5), and rim (n = 3). Intraoperatively, only slight modifications of the implants had to be performed. The results were encouraging, as all cases showed a good aesthetic and functional postoperative outcome. Preoperative evaluation of the osseous defect and prefabrication of the required implant reduced operating time and patient morbidity significantly.

Adult↗
PubMed1998

Analysis of K-ras gene mutations in rare pancreatic and ampullary tumours.

OBJECTIVE: Mutation of the K-ras oncogene is a frequent event in pancreatic ductal carcinogenesis and it is believed to occur at an early stage in the development of pancreatic cancer. However, little is known of the role of K-ras mutations in rare pancreatic epithelial neoplasms, endocrine tumours or other non-epithelial tumours of the pancreas. Furthermore, limited data are available regarding the role of K-ras mutations in the pathogenesis of ampullary tumours. DESIGN AND METHODS: Using single-strand conformation polymorphism (SSCP) and direct sequencing of polymerase chain reaction (PCR)-amplified fragments, we analysed codons 12 and 13 for the presence of oncogenic mutations of the K-ras oncogene. Tissues were obtained from patients undergoing tumour resection for various rare pancreatic or ampullary neoplasms (number of cases in brackets): ampullary adenoma (1), neuro-endocrine tumour (3), malignant fibrous histiocytoma of the pancreas (1), pancreatic cystadenocarcinoma (1), serous cystadenoma (1), and primary and metastatic adenocarcinoma of the ampulla (5) and pancreas (3). RESULTS: K-ras gene mutations at codon 12 were detected in both pancreatic adenocarcinomas and in the metastatic lesion, whereas two ampullary cancers harboured a point mutation at codon 13: GGC-->GGG and GGC-->GGT. None of the other tumours exhibited a K-ras gene mutation at codons 12 or 13. CONCLUSION: Pancreatic tumours other than ductal adenocarcinoma of the pancreas do not harbour mutations of the K-ras oncogene. In addition, ampullary adenocarcinomas may present with codon 13 mutations; however, these mutations were not associated with amino acid substitution. Therefore, K-ras gene mutations seem to be a specific genetic alteration contributing to the pathogenesis of pancreatic ductal adenocarcinoma.

Adenocarcinoma↗
PubMed1998

Failure of third-generation implantable cardioverter defibrillators to abort shock therapy for nonsustained ventricular tachycardia due to shortcomings of the VF confirmation algorithm.

Unnecessary shocks by ICDs for rhythms other than sustained VT or VF have been described as the most frequent adverse event in ICD patients. To avoid unnecessary shocks for self-terminating arrhythmias, the third-generation Jewel PCD defibrillators 7202, 7219, and 7220 Plus use a specially designed VF confirmation algorithm after charge end. The purpose of this study was to determine the ability of this VF confirmation algorithm to recognize nonsustained VT, and to analyze the reasons for failure of the PCD device to abort shock therapy for nonsustained VT despite use of this VF confirmation algorithm. Analysis of stored electrograms of electrical events triggering high voltage capacitor charging in the programmed VF zone of the device showed 36 spontaneous episodes of nonsustained VT (227 +/- 21 beats/min) during 18 +/- 7 months follow-up in 15 patients who had a Jewel PCD implanted at our hospital. Intracardiac electrogram recordings and simultaneously retrieved marker channels demonstrated that the ICD shock was appropriately aborted according to the VF confirmation algorithm in 24 (67%) of 36 episodes of nonsustained VT. Twelve episodes (33%) of nonsustained VT, however, were followed by spontaneous ICD shock in 6 (40%) of the 15 study patients. The only reason for all 12 shocks for sustained VT was the inability of the device to recognize the absence of VT after charge end due to shortcomings of the VF confirmation algorithm: 11 of the 12 shocks for nonsustained VT were triggered by the occurrence of paced beats during the VF confirmation period and 1 shock for nonsustained VT was triggered by the occurrence of 2 premature beats after charge end. Thus, better VF confirmation algorithms need to be incorporated in future PCD devices to avoid unnecessary shocks for nonsustained VT.

Defibrillators, Implantable↗
PubMed1998

Heart rate variability during head-up tilt testing in patients with suspected neurally mediated syncope.

The relation between heart rate variability (HRV) and outcome of head-up tilt testing (HUT) in patients with neurally mediated syncope (NMS) was studied in 30 patients with presumed NMS (33 +/- 13 years) and in 11 age-matched controls. After 15 minutes of baseline supine observation, patients were tilted to 60 degrees for 45 minutes or until syncope occurred. HRV parameters included RR intervals, standard deviation of normal-to-normal RR intervals (SDNN), and root mean square successive differences (RMSSD). HRV analysis was performed during 5-minute intervals in the supine position immediately after onset of HUT and before syncope or after 30-35 minutes of tilt in patients without syncope. Syncope occurred after a mean tilt duration of 32 minutes in 14 (47%) of 30 patients with presumed NMS, whereas all controls had an uneventful HUT. In the supine position, RR intervals and RMSSD were comparable among HUT-positive patients, HUT-negative patients, and controls (RR intervals: 799 +/- 92, 854 +/- 137, and 818 +/- 128 ms, P = NS; RMSSD: 43 +/- 40, 36 +/- 34, and 53 +/- 42 ms, P = NS). Baseline SDNN was also comparable in HUT-positive patients versus HUT-negative patients with presumed NMS (50 +/- 26 vs 52 +/- 20 ms, P = NS). Within 5 minutes preceding syncope or after 30-35 minutes of tilt, RR intervals and RMSSD were shorter in HUT-positive patients compared to HUT-negative patients, or to controls (RR intervals: 606 +/- 86 vs 710 +/- 117 and 739 +/- 123 ms, P < 0.05; RMSSD: 12 +/- 5 vs 23 +/- 19 and 40 +/- 32 ms, P < 0.05). Thus, HRV analysis in the baseline supine position was not a predictor of HUT outcome in patients with suspected NMS. Syncope during HUT seemed to be preceded by increased sympathetic activity manifested by an increase in heart rate and by a decreased parasympathetic tone manifested by a decrease in RMSSD measured for 5 minutes before the event, in comparison with HUT-negative patients and with controls.

Adult↗
PubMed1998

Baroreflex sensitivity and heart rate variability in coronary disease compared to dilated cardiomyopathy.

This study was designed to compare baroreceptor sensitivity and heart rate variability as measures of cardiac autonomic tone in patients with coronary disease (CAD, n = 49) and idiopathic dilated cardiomyopathy (IDC, n = 130). Time domain heart rate variability, including SDNN, SDANN, and pNN50, was determined during 24-hour Holter ECG. Baroreflex sensitivity was analyzed nonivasively using the phenylephrine method. Baroreflex sensitivity and heart rate variability were comparable between patients with CAD versus IDC (baroreflex sensitivity: 6.1 +/- 3 vs 6.9 +/- 5 ms/mmHg; SDNN: 97 +/- 40 vs 114 +/- 41 ms; SDANN: 83 +/- 33 vs 99 +/- 41 ms; pNN50: 3.9 +/- 4 vs 9.6 +/- 13 ms, P = NS for all comparisons). Likewise, a subgroup analysis of patients with a left ventricular ejection fraction (LVEF) < or = 30% showed no significant difference in baroreceptor sensitivity and heart rate variability between IDC and CAD patients. Patients with CAD and an LVEF > 30% had a decreased heart rate variability but not a decreased baroreflex sensitivity compared to patients with IDC and LVEF > 30% (baroreflex sensitivity: 6.4 +/- 4 vs 8.3 +/- 6 ms/mmHg, P = NS; SDNN: 98 +/- 19 vs 128 +/- 42 ms, P < 0.05; SDANN: 86 +/- 21 vs 112 +/- 43 ms, P < 0.05; pNN50: 4.2 +/- 3 vs 12.3 +/- 8 ms, P < 0.05). Patients with a markedly depressed LVEF show comparable alterations in cardiac autonomic tone whether they have CAD or IDC. Patients with CAD and preserved LV function, however, have a decreased heart rate variability compared to patients with IDC and preserved LV function. The prognostic significance of these findings will be determined prospectively in a large patient cohort at our institution.

Baroreflex↗
PubMed1998

Noninvasive arrhythmia risk stratification in idiopathic dilated cardiomyopathy: design and first results of the Marburg Cardiomyopathy Study.

The Marburg Cardiomyopathy Study (MACAS) is a prospective, observational study designed to determine the value of the following potential noninvasive arrhythmia risk predictors in at least 200 patients with idiopathic dilated cardiomyopathy (IDC) over a 5-year follow-up period: NYHA-class, left ventricular ejection fraction (LVEF), left ventricular end-diastolic diameter, left bundle branch block and atrial fibrillation on ECG, QT/JT dispersion on 12-lead ECG, signal-averaged ECG, ventricular arrhythmias and heart rate variability (HRV) on 24-hour Holter ECG, baroreflex sensitivity, and microvolt T wave alternans during exercise. This article describes the findings among the first 159 patients with IDCs enrolled in MACAS until May 1998 (40 women, 119 men; age: 49 +/- 12 years; LVEF: 32 +/- 10%). Twenty-nine patients (18%) had atrial fibrillation and 130 patients (82%) were in sinus rhythm. Patients with sinus rhythm were further stratified according to LVEF < 30% (n = 54) versus LVEF > or = 30% (n = 76). Compared to patients with LVEF > or = 30%, patients with LVEF < 30% more often had left bundle branch block (43% vs 25%, P < 0.05), nonsustained VT (44% vs 22%, P < 0.05), decreased HRV (SDNN: 95 +/- 39 vs 128 +/- 42 ms, P < 0.01), decreased baroreflex sensitivity (5.6 +/- 4 vs 8.3 +/- 6 ms/mmHg, P < 0.01), and T wave alternans (59% vs 37%, P < 0.05). The prognostic significance of these findings will be determined by multivariate Cox analysis at the end of a 5-year follow-up. Primary endpoints in MACAS are overall mortality and arrhythmic events (i.e., sustained VT or VF, or sudden cardiac death).

Arrhythmias, Cardiac↗
PubMed1998

Antiangiogenic chemotherapeutic agents: characterization in comparison to their tumor growth inhibition in human renal cell carcinoma models.

The mechanism of action of anticancer chemotherapeutic agents is mainly thought to be due to a direct inhibition of tumor cell proliferation. The enhanced endothelial cell proliferation rate in tumor specimens raised the question of whether therapeutic effects of chemotherapeutic agents might be at least partially attributed to inhibition of tumor angiogenesis. In the present study, we investigated the potential effects of chemotherapeutic agents on human renal carcinoma angiogenesis with the alginate implantation model in mice. For the first time, we also compared results from the angiogenesis model with the inhibitory effects on growth of s.c. xenografts in nude mice. Vincristine and bleomycin exerted strong inhibition of tumor angiogenesis in both carcinoma lines close to the level of the standard antiangiogenic agent O-chloroacetyl-carbamyl-fumagillol (AGM-1470; T/C 22%). Adriamycin reduced angiogenesis of Caki-2 cells (T/C 33%) but had no effect on Caki-1 angiogenesis (T/C 137%). Etoposide and 5-fluorouracil reduced Caki-1 tumor angiogenesis but had no effect on Caki-2. Despite antiangiogenic effects in both carcinoma lines, vincristine, bleomycin, and AGM-1470 significantly reduced only the growth of fast-growing Caki-1 s.c. xenografts but not the slow-growing Caki-2. Antivascular effects by bleomycin and AGM-1470 were also shown by a decrease of microvessel density in nude mouse xenografts. Our findings suggest that chemotherapeutic agents may exert inhibition of tumor angiogenesis, which could be exploitable by combination therapy of fast-growing tumors. The resistance of the slow-growing Caki-2 carcinoma against acute angiogenesis inhibition indicates a need for well-tolerated angiogenesis inhibitors. Our results also suggest the use of fast-growing s.c. xenografts for demonstrating growth inhibition by antiangiogenic compounds. Further characterization of antiangiogenic compounds considered for clinical application should, however, have its focus on slow-growing tumors, which are not accessible for most therapeutic strategies.

Animals↗
PubMed1998

Intermediates of prothrombin activation induce intracellular calcium mobilization in rat aortic smooth muscle cells.

While effects of alpha-thrombin have been well characterized in different cell types, the biological function of intermediates of prothrombin activation is still undefined. Meizothrombin could be shown to be a potent agonist for vascular contraction which seems to be mediated by an interaction with the vascular smooth muscle. To explore this effect at intracellular signaling level, we used rat aortic smooth muscle cells and investigated the effect of the intermediates formed by cleavage of human prothrombin with ecarin, the prothrombin activator from Echis carinatus venom, on mobilization of free intracellular calcium. The ecarin-activated prothrombin induced very rapidly transient calcium mobilization in SMC's comparable to that observed with alpha-thrombin. We conclude that meizothrombin/meizothrombin desF1 (MT/MT desF1) are the most likely candidates for this effect. Furthermore, our results suggest the involvement of PAR-1-type thrombin receptors in MT/MT desF1-induced calcium signaling in rat aortic smooth muscle cells.

Amino Acid Sequence↗