PubMed Health⌕ Search

Biomedical subjects

C Hahn

Publications and source records attributed to C Hahn.

At least 55 records · Page 3Linked to original sources
PubMed1998

Two cases of esophageal carcinoma metastatic to the pineal region with a review of the literature.

BACKGROUND: Metastasis to the pineal region is rare, and there are no previously reported cases of esophageal carcinoma metastatic to the pineal region. CASE DESCRIPTION: We now present two cases of solitary esophageal carcinoma metastatic to the pineal region. In each case there was no evidence of disease progression at the primary site at the time of presentation, and neurologic symptoms were the first indication of recurrent disease. Both patients underwent infratentorial/supracerebellar resection of the pineal lesions and were subsequently referred for radiation therapy. CONCLUSIONS: These two cases emphasize that metastatic disease must be a likely differential consideration in a patient with a CNS lesion and a history of previous malignancy, even if the lesion is in an unusual location.

Adenocarcinoma↗
PubMed1998

Microleakage of super-EBA with and without finishing as determined by the fluid filtration method.

Super-EBA (SEBA) has been used as a root-end filling material because of its superior sealing properties and clinical success. The purpose of this study was to evaluate whether finishing SEBA after it had set would affect the apical seal. Sixty-five extracted maxillary anterior teeth were instrumented and obturated with a single gutta-percha master cone. The root end was resected, and a 3 mm deep root-end preparation was made using ultrasonic tips. Teeth were randomly divided into three groups. Group 1 received SEBA and was finished with a 30-flute high-speed finishing bur. Group 2 received SEBA, which was cold-burnished with a ball burnisher. Temporary Endodontic Restorative Material was used as the negative control in group 3. Microleakage (microliter/min) was measured under 10 psi using the fluid filtration method at days 1, 7, 30, 90, and 180. SEBA/finished exhibited significant microleakage at day 1 when compared with the burnished group. The differences in leakage were not significant at any other time period.

Dental Leakage↗
PubMed1998

A real-time algorithm to improve the response time of a clinical multigas analyser.

OBJECTIVE: An algorithm to improve the response time of a clinical respiratory multigas analyser is presented. METHODS: The algorithm involves the application of a second order differential equation to the analyser gas output signals in real-time. The adjusted analyser output signals are compared with those of a quadrupole respiratory mass spectrometer sampling and analysing simultaneously. RESULTS: Our results show a close correlation between the adjusted clinical gas analyser and the mass spectrometer signals. Lung volumes derived from a non-invasive sinusoidal inert gas forcing technique, in a model test lung, using the adjusted clinical gas analyser and the mass spectrometer signals demonstrated comparable results. CONCLUSIONS: The algorithm provides an improvement on the relatively slow response times of the clinical gas analyser for breath-by-breath time-dependent applications. The same algorithm can also be applied to other instruments which have slow response times.

Algorithms↗
PubMed1998

Antifungal prophylaxis with itraconazole in neutropenic patients with acute leukaemia.

The efficacy of antifungal prophylaxis with itraconazole capsules and its serum concentrations were evaluated in patients intensively treated for acute leukaemia. A consecutive group of patients without systemic antifungal prophylaxis (January 1993 to August 1994, period 1) was compared with another consecutive group of patients (period 2) who received itraconazole capsules (September 1994 to April 1995 400 mg/day, from May 1995 onwards 600 mg/day). All patients admitted with acute leukaemia and standard or high-dose chemotherapy were included into the study. Clinical endpoint was mortality from proven fungal infection. Seventy-six patients and 148 courses of cytotoxic chemotherapy were analysed in the control group as well as 47 patients and 112 treatment courses in the intervention group. Antifungal prophylaxis led to a significant decrease of mortality from invasive fungal infections (8.8%-0.9%, P = 0.005). The median trough concentration of itraconazole of all measurements was 520 ng/ml (range 230-793) in patients who received 400 mg/day and 760 ng/ml (370-1200) in patients receiving a dosage of 600 mg/day (P = 0.002). These findings suggest that itraconazole is an effective drug for antifungal prophylaxis but also that a considerable number of patients do not reach the desired trough levels (>500 ng/ml) with itraconazole capsules.

Acute Disease↗
PubMed1998

Evaluation of five devices for self-monitoring of blood glucose in the normoglycaemic range.

Although hypoglycaemia is a serious risk of intensive insulin therapy, studies on the accuracy of devices for self-monitoring of blood glucose (SMBG) include only a few values below 100 mg/dl. This study evaluated five SMBG devices in the normal range of blood glucose. In three separate series, capillary blood was taken from 207, 214 and 49 healthy subjects and was analysed with the SMBG devices and a laboratory method. Mean (+/- standard deviation) blood glucose values were 86+/-13 mg/dl, 83+/-12 mg/dl and 90+/-16 in series 1-3. All measurements with SMBG devices differed significantly from the laboratory method. The relative deviation from the laboratory method was 5.5% (2.4-10.5%, median and interquartile range) for Accutrend, 7.1% (3.6-12.6%) for Precision QID, 7.5% (3.7-13.7%) for Accu-Chek III, 14.1% (6.2-22.2%) for Companion 2 and 15.2% (10.3-21.3%) for One Touch II (p < 0.05). In conclusion, this study shows important differences in the accuracy of five SMBG devices in the normoglycaemic range. Accutrend and--to a lesser degree--Accu-Chek III and Precision QID obtained better results and can be recommended for SMBG in patients treated with intensive insulin therapy.

Blood Glucose↗
PubMed1998

Activation of the cerebellum by sensory finger stimulation and by finger opposition movements. A functional magnetic resonance imaging study.

Activation of the ipsilateral anterior lobe of the cerebellum by means of hand movements by humans is a well-known phenomenon, but the cerebellar encoding of sensory information has not been well established. The authors delineated the representation of sensory stimulation of fingers in the anterior lobe of the cerebellum using functional magnetic resonance imaging sensitized to changes in blood oxygenation and compared these areas to the regions activated by means of finger opposition movements. Activation was determined by means of pixel-by-pixel correlation of the signal intensity time course with a reference waveform equivalent to the stimulus protocol. All subjects showed significant activation of the anterior lobe of the cerebellum, mainly located in the ipsilateral Larsell lobules IV-V and less consistent in the vermis in relation to sensory finger stimulation. Among some subjects the authors also found activation in the anterior lobe on the contralateral side. The finger movements activated regions that overlapped with the areas activated by sensory finger stimulation but showing a larger and more intense activation pattern.

Adult↗
PubMed1998

Skin thermoregulation during local cooling in healthy volunteers and patients with systemic sclerosis--synchronous assessment of capillary red blood cell velocity, laser Doppler flux and skin temperature.

BACKGROUND: Patients with Raynaud's phenomenon due to systemic sclerosis exhibit a functional microangiopathy with endothelial cell damage. The aim of this study was to assess differences in the so-called nutritive and thermoregulative skin blood flow and to obtain further information by Fourier transformation and by nonlinear analysis of laser Doppler flux (LDF) time series. PATIENTS AND METHODS: A local cold stress test was performed in 10 patients and 10 age- and sex-matched healthy controls. Significant differences were detected between nutritive blood flow in the nailfold capillaries, assessed by capillary red blood cell velocity (CBV), and thermoregulatory blood flow, which was synchronously assessed by LDF. RESULTS: CBV was reduced during cooling, the drop being significantly larger in the patients than in the controls. In contrast, there was no significant difference in the decrease of LDF during cooling. The difference between the fall in CBV values and that in LDF was significantly more pronounced in patients. Further analysis of the LDF frequency spectrum by fast Fourier transformation revealed a significantly greater decrease in amplitude at the heart frequency level in healthy volunteers. A further analysis of the LDF signal revealed significant differences at rest and after cooling in fractal dimensions, suggesting an increased complexity of LDF signals in patients. SUMMARY: The patient's increased sensitivity towards local cold cn be observed best at the capillary level. But the changes of LDF in the frequency spectrum during cooling as calculated by fast Fourier transformation revealed significant differences. In addition differences in fractal dimensions of LDF time series suggest that an analysis of nonlinear dynamics may be a promising approach.

Adult↗
PubMed1997

[Symptoms, tumor stage and primary treatment in patients with colorectal carcinoma].

OBJECTIVE: To obtain population-related data, previously not available for Germany, regarding primary symptoms, diagnosis and treatment of patients with colorectal carcinoma. PATIENTS AND METHODS: During 1994, in the catchment area of Bonn (town of Bonn, districts of Euskirchen and Rhein-Sieg), there were 354 cases of newly diagnosed colorectal carcinoma. For all of them initial symptoms, primary diagnosis, cancer stage at time of diagnosis as well as surgical and conservative treatment were prospectively documented. By comparing entries from all relevant hospitals and doctors with those of the pathology institutes of the region, data of about 98% of all these patients were recorded. RESULTS: The average age of the patients was older (median of 69 for men, 72 for women) with more far metastases than in comparable groups reported by German university surgical departments. Only 4.6% of the group had occult blood in the stool as the only symptom. Most of the patients had local or regional metastases (T3-4: 63.9%; N1-3: 41%, respectively). Operations intended to be curative were possible in only 65.9% of the cohort. Adjuvant radiotherapy and/or chemotherapy was given to 11.7%, using current consensus recommendations.

Adenocarcinoma↗
PubMed1997

The Nck SH2/SH3 adaptor protein is present in the nucleus and associates with the nuclear protein SAM68.

SH2/SH3 adaptor proteins are essential components of the signal transduction pathways initiated by tyrosine kinases. Nck is a ubiquitously expressed adaptor protein whose function has been enigmatic. We performed confocal microscopy to localize Nck in NIH3T3 and A431 cells. Surprisingly, Nck was identified in the nucleus as well as the cytoplasm with no visible change in localization due to PDGF or EGF stimulation. Western blot analysis of nuclear and cytosolic fractions confirmed that there was no translocation in response to growth factor and that tyrosine phosphorylation was specific to only cytosolic Nck. Far Western blot analysis with either Nck, the SH2 domain, or the SH3 domains revealed differential binding in nuclear and cytosolic lysates, indicating specific binding partners for each subcellular location. The major target of c-Src during mitosis is SAM68, a RNA-binding protein ordinarily localized to the nucleus. SAM68 was identified as a nuclear specific binding partner of Nck in both nonmitotic and mitotic cells. Several tyrosine kinases can be found in the nucleus but their signal transduction remains undefined. The discovery of an adaptor protein in the nucleus suggests there are signal transduction mechanisms within the nucleus that recapitulate those found in the cytoplasm.

3T3 Cells↗
PubMed1997

The low-dose monoethylglycinexylidide test: assessment of liver function with fewer side effects.

The hepatic metabolism of lidocaine (1 mg/kg intravenously) to its metabolite monoethylglycinexylidide (MEG-X) is the basis of the standard MEG-X test. To reduce the lidocaine-induced side effects, we evaluated the MEG-X formation after 0.5 and 1 mg/kg lidocaine intravenously in subjects with normal (n = 5) and severely impaired liver function (n = 7) (study I). From this study, a low-dose test (MEG-X concentration 30 minutes after 50 mg lidocaine intravenously [MEG-X30min] normalized to standard MEG-X test results) was developed. Sensory side effects from this low dose and from the standard MEG-X test were compared in a double-blind, randomized, cross-over study (study II) comprising 15 individuals with normal liver function and 45 patients with cirrhosis (15 Child A, 15 Child B, and 15 Child C). In study I, MEG-X formation rate was dose-independent in patients with severely impaired liver function. In study II, normalized MEG-X test results (ranging from < or = 4 to 120 microg/L) were virtually identical to the standard test results (mean difference: -1.9 microg/L; 95% confidence interval [CI]: -5.3; 1.5 microg/L). Fewer individuals experienced side effects (30% vs. 53%) with the low-dose test (P = .0013). In a multivariate analysis, the Child-Pugh score was inversely related to the occurrence of side effects. The low-dose MEG-X test gives almost identical results to the standard MEG-X test and is associated with fewer side effects, which occur less often in individuals with more severely compromised liver function.

Adult↗
PubMed1997

Rapid cooling contracture with cold cardioplegia.

BACKGROUND: Cold cardioplegia can induce rapid cooling contracture. The relations of cardioplegia-induced cooling contracture to myocardial temperature or myocyte calcium are unknown. METHODS: Twelve crystalloid-perfused isovolumic rat hearts received three 2-minute cardioplegic infusions (1 mmol/L calcium) at 4 degrees, 20 degrees, and 37 degrees C in random order, each followed by 10 minutes of beating at 37 degrees C. Finally, warm induction of arrest by a 1-minute cardioplegic infusion at 37 degrees C was followed by a 1-minute infusion at 4 degrees C. Indo-1 was used to measure the intracellular Ca2+ concentration in 6 of these hearts. Additional hearts received hypoxic, glucose-free cardioplegia at 4 degrees or 37 degrees C. RESULTS: After 1 minute of cardioplegia at 4 degrees, 20 degrees, and 37 degrees C, left ventricular developed pressure rose rapidly to 54% +/- 3%, 43% +/- 3%, and 18% +/- 1% of its prearrest value, whereas the intracellular Ca2+ concentration reached 166% +/- 23%, 94% +/- 4%, and 37% +/- 10% of its prearrest transient. Coronary flow was 5.7 +/- 0.2, 8.7 +/- 0.3, and 12.6 +/- 0.6 mL/min, respectively. Warm cardioplegia induction at 37 degrees C reduced left ventricular developed pressure and [Ca2+]i during subsequent 4 degrees C cardioplegia by 16% (p = 0.001) and 34% (p = 0.03), respectively. Adenosine triphosphate and phosphocreatine contents were lower after 4 degrees C than after 37 degrees C hypoxic, glucose-free cardioplegia. CONCLUSIONS: Rapid cooling during cardioplegia increases left ventricular pressure, [Ca2+]i and coronary resistance, and is energy consuming. The absence of rapid cooling contracture may be a benefit of warm heart operations and warm induction of cardioplegic arrest.

Animals↗
PubMed1997

Intraaortic balloon pumping for cardiac support: trends in practice and outcome, 1968 to 1995.

OBJECTIVES: A total of 4756 cases of intraaortic balloon pump support have been recorded at the Massachusetts General Hospital since the first clinical insertion for cardiogenic shock in 1968. This report describes the patterns of intraaortic balloon use and associated outcomes over this time period. METHODS: A retrospective record review was conducted. RESULTS: Balloon use has increased to more than 300 cases a year at present. The practice of balloon placement for control of ischemia (2453 cases, 11.9% mortality) has become more frequent, whereas support for hemodynamic decompensation (congestive heart failure, hypotension, cardiogenic shock) has been relatively constant (1760 cases, 38.2% mortality). Mean patient age has increased from 54 to 66 years, and mortality has fallen from 41% to 20%. Sixty-five percent (3097/4756) of the total patient population receiving balloon support underwent cardiac surgery. Placement before the operation (2038 patients) was associated with a lower mortality (13.6%) than intraoperative (771 patients, 35.7% mortality) or postoperative use (276 patients, 35.9% mortality). Independent predictors of death with balloon pump support were insertion in the operating room or intensive care unit, transthoracic insertion, age, procedure other than angioplasty or coronary artery bypass, and insertion for cardiogenic shock. Independent predictors of death with intraoperative balloon insertion were age, mitral valve replacement, prolonged cardiopulmonary bypass, urgent or emergency operation, preoperative renal dysfunction, complex ventricular ectopy, right ventricular failure, and emergency reinstitution of cardiopulmonary bypass. CONCLUSIONS: Balloons are being used more frequently for control of ischemia in more patients who are elderly with lower mortality. An institutional bias toward preoperative use of the balloon pump appears to be associated with improved outcomes.

Age Distribution↗
PubMed1997

Promising survival with three-dimensional conformal radiation therapy for non-small cell lung cancer.

PURPOSE: Local failure is a major obstacle to the cure of locally advanced non small-cell lung cancer. Three-dimensional conformal radiation therapy (3-DCRT) selects optimal treatment parameters to increase dose to tumor and reduce normal tissue dose, potentially representing an enhancement of the therapeutic ratio of radiation therapy for lung cancer. We performed this analysis of 45 non-small cell lung cancer patients treated with 3-DCRT alone, to evaluate the ability of computer derived lung dose volume histograms to predict serious pulmonary toxicity, to assess the feasibility of this approach, and to examine the resulting survival. METHODS: There were 28 males (62%) and 17 females (38%). The median age was 65 (range: 38-82). Tumor stage was Stage I/II in 13%, IIIa in 42%, and IIIb in 44%. The histology was squamous in 44%, adenocarcinoma in 36%, and other non-small cell histologies in the others. Only 47% of patients. had combined favorable prognostic factors (i.e. KPS < or = 80, and < or = 5% wt. loss). The median dose of radiation to gross disease was 70.2 Gy (range: 52.2-72 Gy) delivered in fractions of 1.8 Gy, 5 days per week. RESULTS: Seven patients did not complete 3-DCRT due to disease progression outside the port. Follow-up data are mature: the median follow up of the 6 survivors is 43.5 months (35-59). Thoracic progression occurred in 46%. Median survival (all 45 patients.) is 15.7 months and survival is 32% at 2 years and 12% at 59 months. Pulmonary toxicity > or = grade 3 occurred in 9% of patients. Dose volume histograms were available in 31 patients and showed a correlation between risk of pulmonary toxicity and indices of dose to lung parenchyma. Grade 3 or higher pulmonary toxicity occurred in 38% (3/8) of patients with > 30% of lung volume receiving > or = 25 Gy, versus 4% (1/23) of patients with < or = 30% lung receiving > or = 25 Gy (P = 0.04). Grade 3 or higher pulmonary toxicity occurred in 29% (4/14) of patients with a predicted pulmonary normal tissue complication probability of 12% or higher versus 0% (0/17) in patients with a predicted probability of less than 12% (P = 0.03). CONCLUSIONS: Despite adverse prognostic criteria median survival is encouraging and may be higher than some combined modality approaches. Dose volume histogram parameters may be useful to determine the maximum dose for individual patients and thereby permit avoidance of toxicity.

Adult↗
PubMed1997

KAMEDIN: a telemedicine system for computer supported cooperative work and remote image analysis in radiology.

The software system KAMEDIN (Kooperatives Arbeiten und MEdizinische Diagnostik auf Innovativen Netzen) is a multimedia telemedicine system for exchange, cooperative diagnostics, and remote analysis of digital medical image data. It provides components for visualisation, processing, and synchronised audio-visual discussion of medical images. Techniques of computer supported cooperative work (CSCW) synchronise user interactions during a teleconference. Visibility of both local and remote cursor on the conference workstations facilitates telepointing and reinforces the conference partner's telepresence. Audio communication during teleconferences is supported by an integrated audio component. Furthermore, brain tissue segmentation with artificial neural networks can be performed on an external supercomputer as a remote image analysis procedure. KAMEDIN is designed as a low cost CSCW tool for ISDN based telecommunication. However it can be used on any TCP/IP supporting network. In a field test, KAMEDIN was installed in 15 clinics and medical departments to validate the systems' usability. The telemedicine system KAMEDIN has been developed, tested, and evaluated within a research project sponsored by German Telekom.

Humans↗
PubMed1997

Inactivation of the small GTPase Rho disrupts cellular attachment and induces adhesion-dependent and adhesion-independent apoptosis.

Rho small GTPases regulate a variety of cellular signaling pathways involved in cell growth and transformation. In this study, we examined potential roles for Rho in adhesion-dependent and -independent pathways regulating apoptosis. Rho GTPases are specifically inactivated by exoenzyme C3 (C3) of Clostridium botulinum. Using a novel Sindbis virus-based gene expression system, we created a double subgenomic recombinant (dsSIN:C3) capable of expressing active C3 in intact cells. Infection of L929 fibroblasts with dsSIN:C3 caused essentially complete ADP-ribosylation of intracellular Rho within 1 h. dsSIN:C3-infected cells also became rounded within 1-2 h and detached by 5 h post-infection. Infection of L929 in suspension with dsSIN:C3 disrupted the ability for normal cellular attachment and spreading. Infection of primary cell explants of chicken embryo fibroblasts (CEF) and rat aortic smooth muscle cells (RSM) with dsSIN:C3 caused cytoskeletal effects similar to those seen in L929. We also observed that C3 markedly decreased the basal phosphorylation state of focal adhesion kinase (FAK). Most intriguingly, we found that dsSIN-based expression of C3 or loss of function mutants of Rho could each induce apoptosis and, in RSM, this effect was observed to be adhesion-independent. Rho GTPases, therefore, appear to regulate signal pathways that are required for cell survival and growth that are separate from, but likely overlap with, Rho-dependent pathways involved in cellular adhesion.

ADP Ribose Transferases↗
PubMed1997

Nonreplacement operations for mitral valve regurgitation.

Mitral valve reconstruction offers patients an important alternative to the traditional method for treating severe mitral regurgitation--mitral valve replacement. Over the last 15 years, surgical techniques have evolved for treating mitral regurgitation occurring from various anatomic mechanisms--annular dilatation, abnormal leaflet motion due to a variety of causes, or leaflet perforation. Currently, over 90% of regurgitant mitral valves of varying etiologies are amenable to nonreplacement therapy by reconstruction, with good intermediate- and long-term results. Reconstruction obviates the need for long-term anticoagulation, and thus, there has evolved a trend toward reconstruction earlier in the course of this disease, before fixed atrial fibrillation and ventricular dilatation occur.

Heart Valve Prosthesis↗
PubMed1997

Image transfer and computer-supported cooperative diagnosis.

The KAMEDIN system was designed as a low-cost communication tool as part of a computer-supported cooperative work project that included synchronized user interaction, telepointing and audioconferencing. During a five-month field trial, it was used for medical image transfer and cooperative diagnosis in 14 clinics and medical departments in Germany. During the field test, 297 teleconsultations were performed via ISDN and 875 MByte of data were transferred. An image compression ratio of 2-3 was obtained, so that the total quantity of data transferred corresponded to 14,000-21,000 magnetic resonance images or 3500-5250 computerized tomography images. Furthermore, 694 local sessions were conducted for the preparation of teleconsultations and the review of transferred images. Participants learned to handle the KAMEDIN system in a few hours. This was mainly owing to the design of the user-oriented graphical user interface and the restriction of the system to a set of essential image-processing functions.

Computers↗