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Biomedical subjects

T Böhm

Publications and source records attributed to T Böhm.

At least 19 recordsLinked to original sources
PubMed2006

[Optical quality of the cornea following incisional correction of astigmatism].

BACKGROUND: Unilateral lamellar keratotomy (LKT) and curved dual lamellar keratotomy (BLK) were compared to evaluate the influence of incisional correction of astigmatism on the optical quality of the cornea. PATIENTS AND METHODS: Forty-six patients with a preoperative astigmatism greater than 1.5 D were studied. LKT was performed on 30 eyes during cataract surgery and 20 eyes were treated with a BLK. Preoperatively and 4 weeks after surgery the corneal topographical data were analyzed with ray tracing in a 3-mm optical zone. The potential visual acuity (PVA) and the optical distortion (OD), which is represented by the width of the point spread in the optical center, were calculated as parameters for the optical quality. RESULTS: The mean surgically induced astigmatism was 2.6+/-1.5 D for the LKT group and 3.5+/-1.4 D for the BLK group. The PVA decreased significantly in the LKT group from 1.2+/-0.2 to 1.0+/-0.3 (p=0.008), whereas in the BLK group the PVA remained unchanged (p=0.916). The OD increased from 6.6+/-0.9 microm to 7.9+/-2.0 microm (p=0.007) in the LKT group. In the BLK group the values were stable (p=0.843). CONCLUSIONS: The optical quality of the cornea decreased after unilateral keratotomy in the early postoperative period. Thus, optical quality values should also be considered in incisional correction of astigmatism.

Adult↗
PubMed2006

Trochleaplasty for recurrent patellar dislocation in association with trochlear dysplasia. A 4- to 14-year follow-up study.

We investigated the clinical and radiological outcome of trochleaplasty for recurrent patellar dislocation in association with trochlear dysplasia in 38 consecutive patients (45 knees) with a mean follow-up of 8.3 years (4 to 14). None had recurrence of dislocation after trochleaplasty. Post-operatively, patellofemoral pain, present pre-operatively in only 35 knees, became worse in 15 (33.4%), remained unchanged in four (8.8%) and improved in 22 (49%). Four knees which had no pain pre-operatively (8.8%) continued to have no pain. A total of 33 knees were available for radiological assessment. Post-operatively, all but two knees (93.9%) had correction of trochlear dysplasia radiologically but degenerative changes of the patellofemoral joint developed in 30% (10) of the knees. We conclude that recurrent patellar dislocation associated with trochlear dysplasia can be treated successfully by trochleaplasty, but the impact on patellofemoral pain and the development of patellofemoral osteoarthritis is less predictable. Overall, subjective patient satisfaction with restored patellofemoral stability after trochleaplasty appeared to outweigh its possible sequelae.

Adolescent↗
PubMed2003

Detection of submucosal gastric fundal varices with multi-detector row CT angiography.

BACKGROUND AND AIM: The diagnosis of submucosal fundal varices is challenging. Currently, endoscopy and endoscopic ultrasound (EUS) are considered most useful for this purpose. The aim of this study was to evaluate if multi-detector row CT (MDCT) angiography contributes to the diagnosis of submucosal fundal varices. PATIENTS AND METHODS: Twenty two patients with endoscopically suspected fundal varices were prospectively included in the study. All patients underwent EUS and MDCT angiography. Levels of agreement between EUS and MDCT angiography for the detection of submucosal and perigastric fundal varices were evaluated by three blinded independent readers. In addition, variceal size and location, as well as afferent and efferent vessels of the submucosal varices, were determined. RESULTS: Good or excellent image quality of MDCT angiography was obtained in 21/22 patients (95%). Based on EUS, submucosal varices were detected in 16 of 22 patients (73%) and perigastric varices in 22/22 patients (100%). Using MDCT angiography, the presence of submucosal varices was confirmed in all of these 16 patients by all three readers. Perigastric varices were also confirmed in all 22 patients by all three readers. In addition, all three readers noted the presence of a submucosal varix in an additional patient which was not detected on initial EUS. MDCT angiography showed an excellent interobserver reliability with regard to variceal diameter (kappa=0.90) and variceal location (kappa=0.94). Based on MDCT angiography, afferent and efferent vessels of submucosal varices included the left gastric vein in 11 (65%), the posterior/short gastric veins in 15 (88%), gastrorenal shunts in 10 (59%), the left inferior phrenic vein in six (35%), and the left pericardiophrenic vein in six (35%) of 17 patients. CONCLUSIONS: MDCT angiography is equivalent to EUS in terms of detection and characterisation of fundal varices, in particular with regard to the distinction between submucosal and perigastric fundal varices.

Adult↗
PubMed2002

[22-year-old patient with left groin pain].

A 22 year old man from Ethiopia suffered from progressive left inguinal pain and weight loss for ten months. The pain aggravated with leg movement, in particular with flexion of the left hip. ESR and CRP were slightly elevated, and a PPD was strongly positive. Abdominal ultrasound was normal but CT-scan revealed a left sided psoas abscess. Pott's disease was suspected and tuberculostatic therapy with INH, PZA, ETH, RIF was initiated immediately. A MRI of the spine excluded spondylodiscitis. Primary Tb psoas abscess was diagnosed. Treatment response after 5 weeks was clinically insufficient and CT-scan showed enlargement of the abscess. Treatment adherence was verified by drug prescriptions and INH urinary stix testing. M. tuberculosis, suspected microscopically in the puncture fluid, grew in culture and was fully drug sensitive. After 12 weeks, surgical abscess debridement had to be performed due to disease progression. The patient's health state improved considerably the first two postoperative months, inflammatory markers normalized, although a small residual abscess was still visible on CT. Subsequently, three months after surgery, pain reemerged, CT showed abscess progression. The patient had to be reoperated. Tb psoas abscess was a frequently described complication of Tb spondylodiscitis (Pott's disease) the first half of the last century and became rare thereafter in the Western hemisphere. However, the last two decades, due to migration policies and a worldwide increase of Tb epidemic because of socioeconomic destabilization and spread of the HIV-pandemic, Tb reemerged in Western countries. Therefore, physicians should be aware of atypical manifestations of tuberculosis. Primary Tb psoas abscess is extremely rare. Only four cases are described in the literature. In analogy to Pott's disease, therapy consists of tuberculostatic treatment, supported by surgical debridement.

Adult↗
PubMed2001

Controlling small guanine-nucleotide-exchange factor function through cytoplasmic RNA intramers.

ADP-ribosylation factor (ARF) GTPases and their regulatory proteins have been implicated in the control of diverse biological functions. Two main classes of positive regulatory elements for ARF have been discovered so far: the large Sec7/Gea and the small cytohesin/ARNO families, respectively. These proteins harbor guanine-nucleotide-exchange factor (GEF) activity exerted by the common Sec7 domain. The availability of a specific inhibitor, the fungal metabolite brefeldin A, has enabled documentation of the involvement of the large GEFs in vesicle transport. However, because of the lack of such tools, the biological roles of the small GEFs have remained controversial. Here, we have selected a series of RNA aptamers that specifically recognize the Sec7 domain of cytohesin 1. Some aptamers inhibit guanine-nucleotide exchange on ARF1, thereby preventing ARF activation in vitro. Among them, aptamer M69 exhibited unexpected specificity for the small GEFs, because it does not interact with or inhibit the GEF activity of the related Gea2-Sec7 domain, a member of the class of large GEFs. The inhibitory effect demonstrated in vitro clearly is observed as well in vivo, based on the finding that M69 produces similar results as a dominant-negative, GEF-deficient mutant of cytohesin 1: when expressed in the cytoplasm of T-cells, M69 reduces stimulated adhesion to intercellular adhesion molecule-1 and results in a dramatic reorganization of F-actin distribution. These highly specific cellular effects suggest that the ARF-GEF activity of cytohesin 1 plays an important role in cytoskeletal remodeling events of lymphoid cells.

ADP-Ribosylation Factor 1↗
PubMed2001

Additional value of electrical impedance scanning: experience of 240 histologically-proven breast lesions.

The aim of this study was to quantify the clinical value of using electrical impedance scanning (EIS) as an adjunct to other diagnostic techniques in order to identify cancerous tissue based upon its inherent altered local dielectric properties. 210 consecutive women with 240 sonographically and/or mammographically suspicious findings were examined using EIS. All lesions were histologically-proven. 86/103 malignant and 91/137 benign lesions were correctly identified using EIS (87.8% sensitivity, 66.4% specificity). NPV and PPV of 84.3% and 65.2% were observed, respectively. Excluding cases as defined by a priori criteria, i.e. lesions located deeper than 35 mm, lesions larger than 35 mm, and retroareolar lesions, a sensitivity of 85.5% was observed, and for invasive cancers, 91.7%. The detection rate for ductal carcinoma in situ (DCIS) was poor (57.1%, n=14). By adding EIS to mammography and ultrasound, the sensitivity rose from 86.4 to 95.1%, whereas the accuracy decreased from 82.3 to 75.7%. EIS appears to be of interest as an adjunct to breast diagnostic techniques, performing with a reasonable sensitivity. Further investigations on histomorphological characteristics and the reasons for false-negative findings are essential to gain further knowledge about the bioelectricity of breast lesions, and prove the value of this new technology.

Breast Neoplasms↗
PubMed2001

The NITY motif of the beta-chain cytoplasmic domain is involved in stimulated internalization of the beta3 integrin A isoform.

Beta3 integrin adhesion molecules play important roles in wound repair and the regulation of vascular development and three beta3 integrin isoforms (beta3-A, -B, -C) have been described so far. Surface expression of beta3 integrins is dynamically regulated through internalization of beta3 integrins, however, the molecular mechanisms are understood incompletely. To evaluate the role of the cytoplasmic domain of beta3 integrins for internalization, we have generated single chain chimeras with variant and mutated forms of beta3 cytoplasmic domains. Upon transient transfection into chinese hamster ovary cells, it was found that the beta3-A chimera had strongly reduced cell surface expression compared with the corresponding beta3-B, or beta3-C fusion proteins, or the tail-less constructs, whereas steady state levels of all chimeras were near identical. Studies employing cytoplasmic domain mutants showed that the NITY motif at beta3-A 756-759 is critical for plasma membrane expression of beta3-A. Furthermore, delivery of beta3-A to the cell surface was specifically modulated by the cytoplasmic protein beta3-endonexin, a previously described intracellular protein. Coexpression of the native, long form of beta3-endonexin, which does not interact with the beta3 tail, acted as a dominant negative inhibitor of beta3-A-internalization and enhanced steady-state surface expression of the beta3-A-chimera. Furthermore, anti-beta3 antibody-induced internalization of the native beta3 integrin (alpha(IIb)beta3 was dramatically reduced for the Tyr(759)-Ala substitution mutant (alpha(IIb)beta3) (Y759A) and expression of the long isoform of beta3-endonexin substantially decreased the internalization of wild-type alpha(IIb)beta3. Thus, the NITY motif of the beta-chain cytoplasmic domain is involved in stimulated internalization of the beta3 integrin A isoform and beta3-endonexin appears to couple the beta3-A isoform to a specific receptor-recycling pathway.

Amino Acid Sequence↗
PubMed2000

Characteristics of P2X7 receptors from human B lymphocytes expressed in Xenopus oocytes.

Human B lymphocytes express an ATP-gated ion channel (P2Z receptor), which shares similarities with the recently identified P2X7 receptor. Using gene specific primers, we have now isolated P2X7 cDNA from the total RNA of human B lymphocytes. This hP2X7 receptor subtype was expressed in Xenopus oocytes and electrophysiologically characterized. The hP2X7 receptor is similar to, but does not completely match, P2Z of human B cells. The hP2X7 receptors resemble the P2Z receptors with regard to the ATP concentration of half maximal activation, reproducibility, permeation characteristics and lack of desensitization of the ATP-evoked currents. However, in contrast to the native lymphocytic P2Z receptor, the time course of activation of hP2X7 displayed an additional linearly increasing current component. Furthermore, a second, small and slowly deactivating current component exists only in hP2X7 expressed in oocytes. The activation and deactivation kinetics as well as permeation characteristics of hP2X7 are different from rat P2X7 recently expressed in oocytes. Unlike in mammalian cells, hP2X7 expressed in Xenopus oocytes is not sufficient to induce large non-selective pores.

Adenosine Triphosphate↗
PubMed2000

Reproducibility--an important factor determining the quality of computer-aided detection (CAD) systems.

PURPOSE: To test the reproducibility of markings on mammography films set by a commercial computer aided detection (CAD) system. PATIENTS AND METHODS: One hundred unilateral mammography examinations (each in CC and MLO) of 100 patients with mammographically detected suspicious foci, which were histopathologically proven to be malignant, were scanned three times with the CAD system, retrospectively. Every fifth patient of the institutional tumor case sampler was enrolled in the study. Only cases with one visible lesion were included in the study. Reproducibility and sensitivity (in both the strict and the broader sense) were determined. Strict sensitivity means the correct set of markers in both images, whereas broader sensitivity means the correct set in at least one of the images. Sixteen of 100 malignancies were indicated by focal suspicious microcalcification clusters, 53 tumors by masses and 31 cases by both signs of breast cancer. The CAD evaluation was divided into only two different markers: one for microcalcifications and one for masses. Thus, 47 (16+31) tumor-induced microcalcifications and 84 (53+31) malignancy-related masses were checked using the CAD system. RESULTS: Eighteen of 100 unilateral mammography examinations revealed identical patterns in all three scans (18% reproducibility). Eleven of 47 suspicious focal microcalcification clusters and 43/84 masses were correctly marked on both mammographic views in all three CAD scans (strict and broader sensitivity, 23.4 and 51.1%, respectively). Six of 47 microcalcification clusters and 8/84 masses were totally missed in all images by the system (false negative rate, 12.8 and 9.6%, respectively). CONCLUSION: Reproducibility is essential for CAD systems. Currently, reproducibility of the used CAD system appears to be insufficient for clinical routine. Improvement of the system characteristics would make such systems valuable as a 'second reader' in clinical examination.

Breast Neoplasms↗
PubMed2000

Saline-enhanced radiofrequency ablation of breast tissue: an in vitro feasibility study.

RATIONALE AND OBJECTIVES: The feasibility of radiofrequency (RF) ablation for the treatment of breast tumors was investigated in vitro. The best parameters for ablation of breast tissue were chosen. METHODS: Saline-enhanced RF ablation was performed in human breast tissue specimens and cow udder tissue. Temperature profiles were measured depending on RF power (20, 28, 36 W) and NaCl infusion rate (15, 30, 60 mL/h) using eight thermocouples. Lesion development was monitored by ultrasound. Thermolysis efficiency was measured by tissue weight determinations before and after ablation. RESULTS: After RF ablation of tissue samples, 73.6% turned into a fat/saline emulsion. Ultrasound monitoring showed a cone-shaped hyperechoic area during the first 2 minutes of RF ablation, followed by an irregular expansion of the area. Time-dependent spatial temperature curves were more homogeneous at low infusion rates (15 mL/h). Peak temperatures up to 160 degrees C were measured. CONCLUSIONS: Controlled RF ablation of breast tissue is feasible. The irregular expansion of RF lesions in fatty breast tissue is due to liquefied fat. Low saline interstitial infusion rates result in better control of lesioning.

Animals↗
PubMed1999

The difficult freedom from a plan.

The author attempts to describe a tendency among analysts in connection with presenting clinical material to become either too dogmatic or too insecure, either idealising knowledge or uncertainty. Both extremes may also mean idealising intellectualisation. Instead, the author suggests that these tendencies arise as a reaction towards complex psychological strategies from the patient, and that these strategies need to become clarified, instead of the analyst intervening prematurely with the mentioned extreme tendencies. In order to do so, the analyst needs to be free from inner automatic programmes. Two clinical vignettes are described where the analyst's own repression plays a part in his interventions. Freud's technical papers are analysed concerning frame factors and technical recommendations and the author shows how Freud's classical technique is modern in its emphasis on freedom and preliminary truth in interpretations. Freud's papers also seem to agree with Bion's motto 'without memory or desire', which the author discusses as the freedom from a programme. He recommends three governing mottoes for the area of interventions, in order not to idealise the image of psychoanalysis and psychoanalysts. He concludes with a third clinical vignette that underlines the connection between classical analysis and modern analysts who emphasise the freedom from idealised programmes within the psychoanalytic frame.

Female↗
PubMed1997

Purinoceptor-operated cationic channels in human B lymphocytes.

1. Using the patch clamp method in the outside-out configuration, purinoceptor-dependent unitary currents were measured in tonsillar and transformed tonsillar human B lymphocytes. 2. Single channel currents were evoked by ATP4-, the free-acid form of ATP, and by 2',3' O-benzoyl-4-benzoyl-ATP (BzATP) in the micromolar concentration range, but not by 10 mM ADP3- or 0.5 mM Mg(2+)-bound ATP. 3. The channels could be activated and deactivated several times for as long as 30 min even in the absence of intracellular ATP, GTP, or glucose. 4. The channels were selective for small cations and had a conductance of 9 pS with Cs+ as the intracellular and Na+ as the extracellular monovalent cation. 5. The half-maximal activation of the channels was obtained by 114 microM ATP4- and by 16 microM BzATP. The increase in the open probability after raising the ATP4- concentration was mainly due to a decrease in the times the channels spend in the closed state. 6. It is concluded that human B lymphocytes possess cationic channels directly gated by extracellular ATP4-. Their agonist binding characteristics are typical for P2z purinoceptors, but their permeation behaviour is different from the large non-specific pores formed by ATP4- in fibroblasts, macrophages and mast cells.

Adenosine Triphosphate↗