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Biomedical subjects

R Weber

Publications and source records attributed to R Weber.

At least 217 records · Page 12Linked to original sources
PubMed1996

Contributions of vascular tone and structure to elastic properties of a medium-sized artery.

Isobaric compliance and distensibility of the radial artery were recently reported to be normal or slightly increased in untreated hypertensive patients. However, these findings provide no information on the intrinsic mechanical properties of the wall material. To address this question, we determined intima-media wall thickness, wall-to-lumen ratio, and incremental elastic modulus in the radial artery of 25 untreated hypertensive patients with blood pressure of 150 +/- 14/103 +/- 6 mm Hg (mean +/- SD) and 25 matched control subjects with blood pressure of 118 +/- 9/79 +/- 6 mm Hg. High-resolution echotracking for assessment of internal diameter and intima-media wall thickness was combined with measurements of blood flow velocity by Doppler and blood pressure by photoplethysmography. In addition, isobaric compliance and distensibility and incremental elastic modulus were measured at peak diameter during reactive hyperemia after a 5-minute brachial occlusion. No significant difference was found between the two groups for isobaric compliance or distensibility at baseline or during hyperemia. However, incremental elastic modulus at 100 mg Hg tended to be lower in hypertensive patients than control subjects (1.9 +/- 1.1 versus 2.5 +/- 1.2 mm Hg x 10(4), P = .1) in resting conditions. Hypertensive patients and control subjects had similar internal diameters (2.47 +/- 0.32 versus 2.41 +/- 0.35 microm), but intima-media wall thickness and wall-to-lumen ratio were significantly increased in hypertensive patients compared with control subjects (0.268 +/- 0.032 versus 0.236 +/- 0.025 mm -P < or = .01- and 0.220 +/- 0.038 versus 0.195 +/- 0.028 -P < or = .05-, respectively). Peak hyperemic blood flow response (hypertensive patients versus control subjects: 349% versus 360% increase from baseline) and reactive hyperemic dilation (7.2% versus 7.9%) were similar in amplitude and duration in the two groups. These results suggest that wall thickening is an adaptive process that reduces wall tension in hypertensive patients while preserving a normal mechanical behavior of the radial artery. This is most likely accomplished by modification of the incremental elastic modulus of wall components rather than by a change in vascular tone.

Adult↗
PubMed1996

[Dynamic imaging of gastric ulcer healing using the most modern Morph-Software].

The presentation of gastric ulcer healing taken from video endoscopy as a dynamic process could not be realized till now. The documentation of the dynamic healing process shattered either on the patient's compliance or on the inconstancy of the image cut due to wobbling. The replay should be performed as a time lapse whereby the picture disturbances would become an essential part.-Instead of presenting a continuous film, instant takes of ulcer healing were processed. A dynamic effect was produced by computer-assisted production of intermediate pictures. A video was created in which short video sequences in definite time intervals were recorded endoscopically. Single stills-so-called original pictures-fitting together from each sequence were selected and spliced together. The missing intermediate pictures were made with a special computer technique according to the mathematical concept of interpolation. With this technique, the dynamic documentation of gastric ulcer healing in a 47-year-old male patient was performed. The technique enables an almost natural and real observation of ulcer healing and promises new physiological and patho-physiological knowledge in gastroenterologic endoscopy.

Amoxicillin↗
PubMed1996

Surgery of the lacrimal system.

Several surgical techniques of the lacrimal system are presented and analyzed regarding indications and results. Endonasal dacryocystorhinostomy is performed in cases of postsaccal stenosis. Pre- and intrasaccal stenosis are operated on with conjunctivorhinostomy or with placement of Heermann-Jones tubes. After interruption of the canaliculi, splinting and primary suturing are best suited. During tumor surgery, the nasolacrimal duct can be temporarily or permanently relocated in the soft tissues of the cheek. Performing these techniques, a good lacrimal drainage is usually achieved. The results are based upon subjective and objective findings.

Conjunctiva↗
PubMed1996

Efficacy of current molecular cytogenetic protocols for the diagnosis of chromosome aberrations in tumor specimens.

Molecular cytogenetics provides a powerful link between molecular genetic analysis and chromosome morphology, allowing one to pinpoint structurally aberrant chromosome regions on the molecular level. Fluorescence in situ hybridization with selected DNA probes allows the design of efficient and sensitive tools for the diagnosis of chromosomal aberrations present in tumor cells. Comparative genomic hybridization (CGH) allows the identification of chromosomal imbalances in a comprehensive manner, and is applied to solid tumors and hematological malignancies in order to (i) identify clonal differences within a specimen, (ii) contribute to tumor classifications, (iii) identify recurrent chromosomal gains and losses as starting points for the characterization and isolation of pathogenetically relevant genes, such as proto-oncogenes and tumor suppressor genes respectively, (iv) identify imbalances of prognostic relevance, (v) detect high-copy-number amplification and other markers of genetic instability, and (vi) analyze chromosomal imbalances during tumor progression.

Chromosome Aberrations↗
PubMed1995

[Clinical manifestations and course of cytomegalovirus colitis in AIDS patients].

The clinical findings and course in 10 HIV-positive patients with cytomegalovirus (CMV) colitis were analyzed. Homosexuality was the main risk factor for HIV infection. All patients had markedly reduced CD4 counts (mean 25 x 10(9)/l). Symptoms at presentation were chronic diarrhea, weight loss, fever and abdominal pain. One of the patients had an abdominal mass in the ileocecal region due to inflammation as the leading symptom. Endoscopically the colitis was more often segmental than diffuse. In 2 out of 9 patients who underwent colonoscopy, only the right hemicolon was affected. Concurrent intestinal infections with up to 4 different pathogens were found in 7 patients. 5 patients had chorioretinitis as an extraintestinal CMV symptom (2 before, 3 after the occurrence of CMV-colitis). In only one patient was there a partial response of CMV-colitis to therapy with ganciclovir and foscarnet. Even under therapy CMV colitis was complicated in 2 patients by perforation and inflammatory stenosis respectively. Both needed surgical treatment. Most of the patients died of generalized CMV infection or wasting syndrome.

AIDS-Related Opportunistic Infections↗
PubMed1995

[New parasitic diseases in man: infections caused by Microsporida and Cyclospora species].

The non-taxonomic term microsporidia relates to a group of organisms belonging to the order Microsporida of the phylum Microspora. Microsporidia are obligate intracellular spore-forming protozoa and have no metabolically active stages outside the host cell. Their host range is extensive and includes most invertebrates and all 5 classes of vertebrates. More than 100 microsporidial genera and almost 1000 species have now been identified. 5 genera (Enterocytozoon, Encephalitozoon, Septata, Pleistophora and Nosema) and unclassified microsporidia have been associated with human disease. Only 10 cases of microsporidiosis have been described among persons not infected with HIV. In contrast, microsporidia have gained increasing attention as important opportunistic pathogens in the evolving pandemic of HIV infection. Diagnosis depends on morphological demonstration of the organisms themselves. The potential sources and modes of transmission of human microsporidial infections are uncertain. The clinical manifestations of microsporidiosis are diverse and include intestinal, pulmonary, ocular, muscular, and renal disease. Preliminary observations of the possible utility of albendazole for infections due to Septata intestinalis and Encephalitozoon sp. have been reported. The success of therapy for intestinal Enterocytozoon bieneusi infection has been limited. Cyclospora sp. are recently described protozoa capable of causing diarrhea in immunocompetent and immunodeficient patients. Groups at risk for infection are children in the developing world, travellers and HIV-infected patients. Diagnosis depends on light-microscopic detection of oocysts in stool smears stained with acid-fast stains. Diarrhea is usually self-limiting. Diarrhea, however, may often last weeks to months, causing significant morbidity. Cotrimoxazole appears to be the drug of choice for treatment of Cyclospora infection.

Adult↗
PubMed1995

[Noninvasive assessment of morphology and function of the great vessels].

Hypertension is well recognized as a risk factor that is associated with an increased incidence of stroke and myocardial infarction. The early detection of atherosclerosis is a real challenge and should be carried on at a cost and with a degree of risk and invasiveness that does not preclude its use in subjects with cardiovascular risk factors. For this purpose we have developed a non-invasive approach using a high resolution echotracking device making it possible to measure internal diameter and wall thickness of conduit arteries as well as their biomechanical properties. We present here a methodological overview of the system with a brief clinical study addressing the biomechanical properties of a medium size artery in hypertension as compared with normotension.

Arteries↗
PubMed1995

A prospective analysis of immunohistochemically determined hormone receptors and nuclear features as predictors of early recurrence in primary breast cancer.

The immunohistochemically determined receptor status, as well as first-generation risk factors (tumor size, lymph node status, histologic grading including subfactors, tumor histology, and biochemically determined receptor status) were prospectively analyzed in 288 cases of primary breast cancer for their impact on recurrence-free survival (RFS) and overall survival (OS) after a median observation period of 41 months. Immunohistochemically (ER-ICA) and biochemically determined estrogen receptors (ER-DCC), as well as tumor size, lymph node status, histologic grading, mitotic rate, and nuclear polymorphism, were of prognostic value for recurrence-free survival and/or overall survival. In multivariate analysis, lymph node status, tumor size, and mitotic rate proved to be independent prognosticators; ER-ICA showed significance in the univariate analysis which dropped, however, when multivariate analysis was applied. The prognostic power of histologic grading in our series seemed to depend mainly on the subfactors which relate to nuclear features.

Adult↗
PubMed1995

Polyfluorinated dibenzodioxins and dibenzofurans--synthesis, analysis, formation and toxicology.

The 75 congeners of the polyfluorinated dibenzodioxins (PFDDs) and about half of the 135 polyfluorinated dibenzofurans (PFDFs) have been synthesized by pyrolysis of fluorophenols and fluorobenzenes. The individual congeners were characterized by GC/MS. 2,3,7,8-TFDD was also characterized by 1H-, 13C- and 19F-NMR spectroscopy. The retention behaviour of PFDDs and PFDFs during gaschromatographic separation is entirely different from that of PCDDs/PCDFs or PBDDs/PBDFs. The PFDDs/PFDFs elute earlier than the PCDDs/PCDFs and the order of the elution is not governed by the degree of substitution, O8FDD eluting e.g. much earlier than the M1FDDs. A preliminary toxicological evaluation of 2,3,7,8-TFDD was carried out. The elimination of 2,3,7,8-TFDD from mice after a single i.p. injection is biphasic with a very rapid elimination half-life of 5 minutes and a slower phase of 165 minutes. This means a dramatically reduced half-life compared to 2,3,7,8-TCDD with 8.5 d. In liver the TFDD level reaches a maximum 30 minutes after injection and also declined in a biphasic manner. In rat hepatocytes a primary culture induction of CYP4501A1-catalyzed EROD activity could be demonstrated, indicating that 2,3,7,8-TFDD activates the dioxin receptor. In rat hepatocyte cultures similar EC50 values were found for 2,3,7,8-TCDD and 2,3,7,8-TFDD. So far no de novo synthesis of PFDD/PFDF could be detected under conditions were PCDDs/PCDFs are formed. Also, formation of PFDDs/PFDFs could not be detected during thermal treatment of fluorotrichloromethane or Teflon.

Animals↗
PubMed1995

Magnetic resonance imaging after frontal sinus surgery with fat obliteration.

The obliteration of the frontal sinus via an osteoplastic approach is performed with the aim of achieving a permanent 'switching off' by final and conclusive clearing out. For this, freshly harvested abdominal fat has shown itself to be the best clinically. It is possible to demonstrate the vitality of fat transplanted into the frontal sinus without an operation, i.e. by a macroscopical and histological examination using magnetic resonance imaging (MRI). The magnetic resonance examinations were carried out on a supraconductive 0.5 T Magnet (Gyroscan T.S.II, Philips Medicine Systems, Eindhoven, Netherlands) with a quadrature (square) head spool. We produced T1-weighted spin echo images (TR: 450-550 ms; TE: 20-25 ms), T2-weighted fast spin echo images or in double-echo technique in transverse orientation (Turbo SE or TR: 2000-2500 ms; TE: 50-90 ms) and short tau inversion recovery (STIR) sequences for fat suppression (TJ: 140 ms; TR: 1400 ms; TE: 30 ms). The fat implanted into the frontal sinus of 11 patients aged 22-65 years, having undergone an osteoplastic frontal sinus operation with obliteration, was examined post-operatively by MRI. Objectives were the time-dependent distribution of portions of vital fatty or connective tissue, the eventual development of necroses or cysts as well as recurrences, inflammatory complications or re-epithelization of the frontal sinus four to 24 months post-operatively. In only six out of 11 cases was vital fatty tissue found. Fatty necrosis occurred five times, whereas in four cases a transformation into granulation tissue and in one case into connective tissue could be seen. All 11 patients were complaint-free. Long-term observations are needed to see if differences in the recurrence rate of frontal sinus disease are dependent on whether the implanted fat remains vital or necrosed and transformed.

Adipose Tissue↗
PubMed1995

[Synovial cell sarcomas of the head- and neck area].

The synovial cell sarcoma is a malignant soft tissue tumour which mostly occurs associated with or in a large joint. To date, the histogenetic origin has been discussed controversially and there is still no agreement as to whether it arises from normal synovium of joints, tendon sheaths or bursae, specialised forms of mesenchymal tissue (arthrogenous mesenchyma) or ordinary connective tissue. The tumour rarely occurs in the head and neck region. Only about 76 cases world-wide have been described up to now. We report on a case of a 30-year old man with a synovial cell sarcoma of the temporomandibular joint and a case of a 70-year old man with a synovial cell sarcoma of the hypopharynx. In the first case, although all possible therapeutical efforts were made (radical operation, radiotherapy, chemotherapy), recurrence of the tumour occurred locally, as well as metastases in the lungs and bones. The patient died three and a half years after the initial diagnosis of the tumour. The second patient suffered multiple metastases in the lungs and bones one year after operation followed by chemotherapy. To the present time there is no general agreement on how to treat synovial cell sarcomas, but without doubt first of all radical surgical excision must be performed if possible. Additional radiation and/or multidrug chemotherapy may be useful in special cases. In our opinion every case of synovial cell sarcoma should be published because it is of importance to get to know new aspects and therapeutical possibilities of this rare disease.

Adult↗
PubMed1995

[Surgical continuing education with multi-media techniques exemplified by endonasal micro-endoscopic pan-sinus operation].

The concept of multimedia involves the integration of various media into a single computer system which, properly configured, permits an interactive approach. Modern computer technology makes it possible to display of varied audio-visual documents on screen and allow the users to work independently and learn at their own pace. Our new teaching multimedia software (available in English or German) illustrates future possibilities for individualized interactive medical education. Required hardware consists of an IBM-compatible PC plus a CD-ROM drive, two speakers, and a special MPEG multimedia board. The program is supplied on a compact disc. The user begins at an introductory screen and works through the technique of endonasal sinus surgery individually and interactively. He can switch between the following chapters by clicking the mouse: an introduction to anatomy of this region, an atlas of computed tomography of the paranasal sinuses, and a chapter dealing with the danger areas. The main chapter contains a video about how to perform endonasal microendoscopic sinus surgery, which we have divided into thirteen sections. Each of these contains a section on dangers and complications with tips on to avoid and correct them (e.g. how to close a dura defect; what to do after damaging the anterior ethmoidal artery). In addition, CT scans of the relevant areas are shown. A special MPEG multimedia board permits full-screen video.

CD-ROM↗
PubMed1995

[Imaging time-dependent changes in the nasal mucosa using the most modern morphing software].

Changes in the nasal mucous membrane lasting longer than 1-2 minutes have, until now, escaped dynamic observation. Even the congestion and decongestion of the turbinates during the nasal cycle and after application of vasoconstrictive nose drops have been documented only by instant stills. For this reason, we developed a method which permits documenting time-dependent endonasal mucosal changes with their natural dynamics on time-lapse video film. Instead of primarily recording a continuous video film, we processed instant stills. Computer interpolation of intermediate steps gives the viewer a dynamic impression. As continuous video endoscopy is not feasible, we produced the continuous film by recording video sequences of approximately 30 seconds length in defined time intervals endoscopically, selecting single stills (so-called original photographs) from each sequence, and splicing them, producing the missing intermediate photographs by a special computer technique (morphing), similar to mathematical interpolation. In this way we could demonstrate the changes of the right and left inferior turbinate during a nasal cycle of lasting five hours and the effect of xylometazolin nose drops on the nasal mucosa. The practical value of this technique, lies in the comprehensive realistic observation of dynamic processes of the nasal mucosa with respect to physiology and pathophysiology.

Adult↗
PubMed1995

[Behavior of fatty tissue in frontal sinus obliteration].

The purpose of obliterating the frontal sinus is to provide a permanent solution to the underlying problem. The material of choice for obliteration is freshly removed abdominal fat. Using magnetic resonance imaging, one can assess the vitality of fat tissue in an obliterated frontal sinus without surgery. Eight patients ranging in age from 22 to 65 years underwent osteoplastic frontal sinus surgery with fat obliteration. The freshly implanted abdominal fat was postoperatively investigated using magnetic resonance tomography. The magnetic resonance examinations were carried out on a supraconductive 0.5 T Magnet (Gyroscan T S II, Philips Medicine Systems, Eindhoven, Netherlands) with a square head spool. We produced T1-weighted spin echo images (TR: 450-550 ms, TE: 20-25 ms), T2-weighted fast spin echo images or in double echo technique in transverse orientation (Tubo SE or TR-2000-2500 ms, TE: 50, 90 ms) and STIR sequences for fat suppression (TJ: 140 ms, TR: 1400 ms, TE: 30 ms). Our goal was to determine the time-dependent distribution of vital fat or fibrous tissue, development of necrosis, cysts, recurrences, inflammatory complications, or re-epithelization of the frontal sinus. Six to 24 months postoperatively, we found vital fat tissue in only three of eight cases. In the other five cases fat necrosis was present. The frontal sinus was filled by granulation tissue or fibrous tissue (once). It is not yet possible to determine when the fat changes to connective tissue. This process varies between individual patients. All eight patients were free of symptoms.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗