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Biomedical subjects

M Hahn

Publications and source records attributed to M Hahn.

At least 19 recordsLinked to original sources
PubMed2007

Complete extirpation of benign breast lesions with an ultrasound-guided vacuum biopsy system.

OBJECTIVES: To investigate whether ultrasound-guided vacuum biopsy (VB) with curative intent is suitable for the complete extirpation of selected sonographically detectable benign lesions of the breast, and to establish the limitations of the method with regard to lesion size and complications, the extent of scar formation and the prognostic value. METHODS: One hundred and nine patients underwent hand-held, ultrasound-guided VB (8G or 11G needle) between June 2000 and September 2003. Of these, 45 (41%) women underwent ultrasound-guided extirpation of 46 lesions, and 42 women with 43 lesions were followed up clinically and sonographically for an average of 5.9 months. The complete extirpation rate, residual lesions, and patient satisfaction with the intervention were evaluated. RESULTS: Removal of all sonographic evidence of lesions (median diameter, 13 mm) was achieved in 86% of cases (8G needle, 80%; 11G needle, 89%). 19% of the patients had suspected scar formation at the biopsy site. A palpable lesion in the breast could be removed by VB in 90% of cases. None of the patients developed infections and there were no hemorrhages requiring intervention, or damage to the skin or chest wall. A total of 95% of the patients stated that they would prefer this approach to open excision for possible future intervention. CONCLUSIONS: VB is an ambulatory procedure associated with a low degree of pain. It has a high degree of patient acceptance and, as a minimally invasive biopsy technique for benign lesions, is a good alternative to open excision. The rate of complications is low and is similar to that observed with conventional microbiopsy.

Adolescent↗
PubMed2006

Identification of novel tumour-associated genes differentially expressed in the process of squamous cell cancer development.

Chemically induced mouse skin carcinogenesis represents the most extensively utilized animal model to unravel the multistage nature of tumour development and to design novel therapeutic concepts of human epithelial neoplasia. We combined this tumour model with comprehensive gene expression analysis and could identify a large set of novel tumour-associated genes that have not been associated with epithelial skin cancer development yet. Expression data of selected genes were confirmed by semiquantitative and quantitative RT-PCR as well as in situ hybridization and immunofluorescence analysis on mouse tumour sections. Enhanced expression of genes identified in our screen was also demonstrated in mouse keratinocyte cell lines that form tumours in vivo. Self-organizing map clustering was performed to identify different kinetics of gene expression and coregulation during skin cancer progression. Detailed analysis of differential expressed genes according to their functional annotation confirmed the involvement of several biological processes, such as regulation of cell cycle, apoptosis, extracellular proteolysis and cell adhesion, during skin malignancy. Finally, we detected high transcript levels of ANXA1, LCN2 and S100A8 as well as reduced levels for NDR2 protein in human skin tumour specimens demonstrating that tumour-associated genes identified in the chemically induced tumour model might be of great relevance for the understanding of human epithelial malignancies as well.

Animals↗
PubMed2006

[Endolumninal catheter-guided laser therapy of varicosities].

Chronic venous insufficiency is one of the most common diseases with a high socio-economic importance. The most common operation is vein stripping to remove the greater or lesser saphenous vein eliminating venous reflux. In comparison to classical vein stripping, endoluminal laser therapy is a minimally invasive and effective alternative with few complications and a shorter convalescent period. Varicosities can also be treated with the laser, using local anesthesia and sonographic monitoring. The recurrence rate is around 2%, comparable to surgical methods. This article reviews the practical aspects of endoluminal laser therapy, concentrating on the two most widely available systems, reviews the current literature and considers other endoluminal approaches.

Angioplasty↗
PubMed2006

Lead content of dietary calcium supplements available in Brazil.

The lead and calcium content of calcium supplements available in Brazil were determined by graphite furnace and flame atomic absorption spectrometry, respectively. Samples were microwave-digested in concentrated HNO(3). Citric acid was used as a chemical modifier in the lead analysis. Supplements were classified into six categories: oyster industrialized (OI, n=4), oyster prepared in pharmacy (OP, n=3), refined industrialized (RI, n=6), refined prepared in pharmacy (RP, n=3), bone meal (B, n=3), and dolomite (D, n=4). Lead levels (microg g(-1) of measured calcium) were higher in D products (2.33), followed by OI, RP, OP, and RI products (1.46, 1.32, 1.29, 0.75), while B products had levels lower than the limit of quantification (0.02 microg g(-1) unit weight). Daily lead intake of eight supplements exceeded the limit of California, USA (1.5 microg g(-1) calcium), but none exceeded the federal limit of USA (7.5 microg g(-1) calcium) or the provisional tolerable lead intake by FAO/WHO (25 microg kg(-1) per week).

Animals↗
PubMed2006

Biomechanical, morphological, and histological analysis of early failures in hip resurfacing arthroplasty.

The present revival of hip resurfacing arthroplasty may be related to an increase in early failures owing to the challenging technique of the procedure. Fifty-five retrieved implants were analysed with respect to wear, cement mantle and cement penetration, fracture and head morphology, as well as standard histology. Femoral neck fractures occurred in median after 102 days. The time to failure was shorter for older women. Major deviations from the suggested cement mantle thickness and cement penetration were found. Indications for high trauma during implantation leading to early failure due to weakening of the femoral neck were also observed. Some failures had signs of pseudarthrosis beneath the implant. Four different fracture patterns with different mean survival times were identified. Observed wear was minor with the exception of that due to alignment mistakes (rim loading). The cups were not damaged by the failures. Histological results indicate that avascular necrosis is not necessarily connected with this kind of endoprosthetic surgery. Most of the failures analysed can probably be attributed to the 'learning curve' effect, which is an unsatisfactory situation.

Aged↗
PubMed2006

Massive cavernous lymphangioma of the breast and thoracic wall: case report and literature review.

Lymphangiomas are benign lesions but are associated with high morbidity when they become very large, occur in critical locations, or when surgically removed, develop secondary wound infections. Almost all lesions require surgical treatment. Complete excision is curative; however, relapses must be anticipated with incomplete excision. We report the case of a patient with a long history of massive cavernous lymphangioma of the breast and thoracic wall extending into the axilla in whom complete excision was not possible.

Adult↗
PubMed2005

[Health economic aspects of psoriasis therapy. Is inpatient topical treatment of plaque-type psoriasis in this age of biologics still appropriate from both medical and economic viewpoints?].

BACKGROUND: We tried to clarify whether the treatment of plaque psoriasis as an inpatient with dithranol and narrow band UV-B 311 nm is still appropriate and economical when compared to biologics such as efalizumab. PATIENTS AND METHODS: In a 15 month period, all patients admitted to the hospital after unsuccessful outpatient treatment of psoriasis were evaluated prospectively according to medical and economical criteria. RESULTS: PASI-score was reduced by 89% in 74 patients. The direct cost to improve one in-patient by 75% in PASI score (PASI-75) was 4342.27 EUR; the total costs for employed patients were 7441.81 EUR. Direct costs of treatment with efalizumab would come to 15048.89 EUR per patient with PASI-75 in a 12 weeks period. CONCLUSION: Topical inpatient therapy for plaque psoriasis is well tolerated and a less expensive option than biologics in those who fail ambulatory treatment.

Adult↗
PubMed2005

[Principles of fixation of the cementless modular revision stem Revitan].

AIM AND METHOD: To analyse the femoral fixation of a modular cementless revision endoprosthesis, eight prosthetic combinations of the Revitan-System (Centerpulse, Winterthur, Switzerland) were implanted in four cadavers. On three cadavers a curved revision Revitan stem was implanted by an endofemoral approach on one side and by a transfemoral approach on the contralateral side. On the fourth cadaver a straight Revitan stem was implanted on one side and a curved Revitan stem on the contralateral side using a transfemoral approach. Transversal slides of 7-8 mm thickness were performed at the fixation areas of each implant and the implant-bone contact was analysed macroscopically and using contact radiography. RESULTS: The straight stem implanted by a transfemoral approach showed a double-conical press-fit fixation with cutting of the eight longitudinal fins into the cortical bone. The curved revision stems implanted by the same approach had a circular surface fixation similar to the press-fit fixation of the straight stem. In contrast, the curved stems implanted by the endofemoral approach (without a window) showed a three-surface fixation. Hereby the two distal fixation areas led to the primary implant stability by three of the four double edges of the octagonal cross-sectional area cutting into the cortical bone. At the proximal fixation zone the implant only had contact of two implant double edges to the cortical bone. CONCLUSION: Different approaches for implantation lead to different fixation techniques of a curved revision stem. This should be considered by analysing postoperative sintering rates of cementless revision stems.

Aged↗
PubMed2005

[Ampicillin and sulbactam concentrations in the irradiated mandible after oral squamous cell cancer].

INTRODUCTION: Radiation therapy of the oral and maxillo-facial region increases the risk of an infected osteoradionecrosis (IORN) which is a severe complication. Therefore, perioperative antibiotics for the prophylaxis of ORN is a standard in clinical oncology. The combination therapy of ampicillin and sulbactam (Unacid) promises a good therapeutic and prophylactic outcome. PATIENTS: We compared the concentration of Unacid in bone and blood specimens of 22 irradiated patients. All patients were irradiated with 39.6 Gy prior to surgery. The specimens were obtained during the operation 3 weeks after the end of the radiation therapy. RESULTS: The concentration of ampicillin/sulbactam in the blood was 124.9/64.5 microg/ml. The bone specimens showed a concentration of ampicillin/sulbactam of 5.54/1.21 microg/g. The concentration of the antibiotic in the bone was three to four times lower than in non-irradiated patients. Nevertheless, this concentration exceeds the minimum inhibitory concentration for bacteria in the oral cavity such as streptcoccae (MHK90<0.25 microg/ml) or staphylococcae (MHK90=0.12-2.0 microg/ml). CONCLUSIONS: The results of this study suggest, that Unacid is an effective antibiotic in the prophylaxis of ORN in irradiated patients with head and neck tumors.

Adult↗
PubMed2005

Characterization of the Bacillus subtilis spore morphogenetic coat protein CotO.

Bacillus spores are protected by a structurally and biochemically complex protein shell composed of over 50 polypeptide species, called the coat. Coat assembly in Bacillus subtilis serves as a relatively tractable model for the study of the formation of more complex macromolecular structures and organelles. It is also a critical model for the discovery of strategies to decontaminate B. anthracis spores. In B. subtilis, a subset of coat proteins is known to have important roles in assembly. Here we show that the recently identified B. subtilis coat protein CotO (YjbX) has an especially important morphogenetic role. We used electron and atomic force microscopy to show that CotO controls assembly of the coat layers and coat surface topography as well as biochemical and cell-biological analyses to identify coat proteins whose assembly is CotO dependent. cotO spores are defective in germination and partially sensitive to lysozyme. As a whole, these phenotypes resemble those resulting from a mutation in the coat protein gene cotH. Nonetheless, the roles of CotH and CotO and the proteins whose assembly they direct are not identical. Based on fluorescence and electron microscopy, we suggest that CotO resides in the outer coat (although not on the coat surface). We propose that CotO and CotH participate in a late phase of coat assembly. We further speculate that an important role of these proteins is ensuring that polymerization of the outer coat layers occurs in such a manner that contiguous shells, and not unproductive aggregates, are formed.

Bacillus subtilis↗
PubMed2003

[Ceftriaxone versus Levofloxacin for antibiotic therapy in patients with acute cholangitis].

INTRODUCTION: For the therapy of acute cholangitis complete biliary drainage and antibiotic therapy is needed. The aim of the current study was to compare intravenous therapy of acute cholangitis with Ceftriaxone or Levofloxacin in a prospective and randomized fashion. METHODS: Patients with biliary obstruction and clinical signs of infection received in addition to 1.5 g Metronidazole either 500 mg Levofloxacin/die or 2 g Ceftriaxone/die. Early on during ERCP, bile was aspirated via the cannulation catheter and cultured for bacteria under aerobic and anaerobic conditions. Minimal inhibitory concentrations of the respective antibiotics were determinate for each isolate. The clinical course was followed for at least 6 days with clinical and laboratory data. RESULTS: 60 patients with clinical signs of acute cholangitis were randomised. In 40 patients (66 %) biliary colonization with bacteria could be identified. In all bacterial species Levofloxacin showed significantly lower rates of in-vitro resistance as compared to Ceftriaxone. However, the percentage of patients with a clinical cure or significant improvement was the same in the two groups. CONCLUSIONS: The clinical effect of Levofloxacin and Ceftriaxone in patients with acute cholangitis showed no significant differences. Because of improved in-vitro efficiency, a calculated therapy with Levofloxacin might be advantageous.

Acute Disease↗
PubMed2003

Value of chromoendoscopy and magnification endoscopy in the evaluation of duodenal abnormalities: a prospective, randomized comparison.

BACKGROUND AND STUDY AIMS: Endoscopic staining methods are increasingly being used to evaluate lesions in the esophagus and colon. The aim of this prospective study was to investigate chromoendoscopy and magnification endoscopy for the evaluation of mucosal lesions in the duodenum. PATIENTS AND METHODS: Consecutive patients were randomly assigned to undergo conventional endoscopy without staining (group A) or intravital staining of the duodenal mucosa with indigo carmine and evaluation with a conventional video endoscope (group B) or a magnification endoscope (group C). Visible lesions were characterized before and after staining, and biopsies were taken for histological assessment. RESULTS: A total of 118 patients was examined. Chromoendoscopy detected significantly more lesions in the duodenal bulb (98 vs. 28; P = 0.0042) in more patients (29 vs. 15; P = 0.0025) compared with conventional endoscopy (group A). After mucosal staining, there was no difference between video endoscopy and magnification endoscopy with regard to the number or extent of the lesions identified. Significantly more targeted biopsies were possible after intravital staining. The most commonly identified lesions on targeted biopsies included (staining/control groups): gastric metaplasia (14/3), hyperplastic Brunner's glands (6/3), inflammatory changes (7/6), villous atrophy (1/3), adenoma (1/0). CONCLUSIONS: Intravital staining of the duodenum with indigo carmine may be useful for detecting mucosal abnormalities, delineating their extent, and allowing targeted biopsies. Magnification endoscopy, when used in addition to chromoendoscopy, does not appear to further increase the diagnostic yield for detecting duodenal abnormalities.

Adolescent↗
PubMed2003

[Surgery of hemorrhoids using the Long method and its complications].

BACKGROUND: The aim of this article is an assessment of new surgical procedure--stapled hemorroidectomy according to Longo. We do concentrate on surgical complications and possibilities of it's management. METHODS: Prospective, clinical follow up of patients in which stapled hemorrhoidectomy was performed during the period of 2 years (1st December 2000--30st November 2002). Observation concentrates on surgical complications of this method. All patients had a clinical check up 3 weeks and 3 months after surgery. In case of any problems treatment and follow up continues. RESULTS: Stapled hemorroidectomy was performed during the period of 2 years in 52 patients (100%). There was 11 patients (21.2%) with some of surgical complication. The most serious one was massive rectal bleeding after surgery, which has been observed in 4 patients (7.6%). Other surgical complications observed in our group were anal stenosis, local infection, acute anal fissure and retention of urine. CONCLUSION: Stapled hemorroidectomy is now one of feasible alternatives for surgical treatment of hemorrhoids. Serious surgical complications observed in our patients were bleeding from the stapled suture line and anal stenosis. The aim of this article is to refer possible surgical complications of this method, it's prevention and management.

Adult↗
PubMed2002

Infrequent genetic alterations of the tumor suppressor gene PTEN/MMAC1 in squamous cell carcinoma of the oral cavity.

BACKGROUND: Fifty tumor specimens from primarily untreated patients were analyzed to elucidate the involvement of the tumor suppressor gene PTEN/MMAC1 in the development of oral squamous cell cancer. METHODS: Eight microsatellite markers, spanning 10 cM of genomic DNA located centromeric, telomeric or intragenic of PTEN/MMAC1 were used for loss of heterozygosity (LOH) and breakpoint analysis. The microsatellite panel within or in close proximity (1 cM) to the 10q23.3 locus showed a LOH rate of 12%. Complete sequence analysis of the genes coding region was performed in all 10 cases that exhibited LOH in one of the eight microsatellite markers within or around the PTEN/MMAC1 gene. Comparative multiplex PCR reactions served to screen for homozygous deletions. RESULTS: There was no association between allelic loss of the gene, overall patient survival and recurrence-free survival. Sequencing did not reveal any mutation in the coding region of PTEN/MMAC1. Differential PCR analysis failed to detect any homozygous deletion. CONCLUSIONS: We conclude that PTEN/MMAC1 gene alterations do not play a key role in tumorigenesis of oral squamous cell cancers.

Adult↗
PubMed2001

Cross-reactive binding of cyclic peptides to an anti-TGFalpha antibody Fab fragment: an X-ray structural and thermodynamic analysis.

The monoclonal antibody tAb2 binds the N-terminal sequence of transforming growth factor alpha, VVSHFND. With the help of combinatorial peptide libraries it is possible to find homologous peptides that bind tAb2 with an affinity similar to that of the epitope. The conformational flexibility of short peptides can be constrained by cyclization in order to improve their affinity to the antibody and their stability towards proteolysis. Two cyclic peptides which are cross-reactive binders for tAb2 were selected earlier using combinatorial peptide libraries. One is cyclized by an amide bond between the N-alpha group and the side-chain of the last residue (cyclo-SHFNEYE), and the other by a disulfide bridge (cyclo-CSHFNDYC). The complex structures of tAb2 with the linear epitope peptide VVSHFND and with cyclo-SHFNEYE were determined by X-ray diffraction. Both peptides show a similar conformation and binding pattern in the complex. The linear peptide SHFNEYE does not bind tAb2, but cyclo-SHFNEYE is stabilized in a loop conformation suitable for binding. Hence the cyclization counteracts the exchange of aspartate in the epitope sequence to glutamate. Isothermal titration calorimetry was used to characterize the binding energetics of tAb2 with the two cyclic peptides and the epitope peptide. The binding reactions are enthalpically driven with an unfavorable entropic contribution under all measured conditions. The association reactions are characterized by negative DeltaC(p) changes and by the uptake of one proton per binding site. A putative candidate for proton uptake during binding is the histidine residue in each of the peptides. Hydrogen bonds and the putative formation of an electrostatic pair between the protonated histidine and a carboxy group may contribute markedly to the favorable enthalpy of complex formation. Implications to cyclization of peptides for stabilization are discussed.

Amino Acid Sequence↗
PubMed2001

The role of haustoria in sugar supply during infection of broad bean by the rust fungus Uromyces fabae.

Biotrophic plant pathogenic fungi differentiate specialized infection structures within the living cells of their host plants. These haustoria have been linked to nutrient uptake ever since their discovery. We have for the first time to our knowledge shown that the flow of sugars from the host Vicia faba to the rust fungus Uromyces fabae seems to occur largely through the haustorial complex. One of the most abundantly expressed genes in rust haustoria, the expression of which is negligible in other fungal structures, codes for a hexose transporter. Functional expression of the gene termed HXT1 in Saccharomyces cerevisiae and Xenopus laevis oocytes assigned a substrate specificity for D-glucose and D-fructose and indicated a proton symport mechanism. Abs against HXT1p exclusively labeled haustoria in immunofluorescence microscopy and the haustorial plasma membrane in electron microscopy. These results suggest that the fungus concentrates this transporter in haustoria to take advantage of a specialized compartment of the haustorial complex. The extrahaustorial matrix, delimited by the plasma membranes of both host and parasite, constitutes a newly formed apoplastic compartment with qualities distinct from those of the bulk apoplast. This organization might facilitate the competition of the parasite with natural sink organs of the host.

Animals↗
PubMed2001

Expression pattern of Drosophila ret suggests a common ancestral origin between the metamorphosis precursors in insect endoderm and the vertebrate enteric neurons.

The RET gene, encoding a receptor tyrosine kinase, is unusual among human protooncogenes in that its mutant alleles are implicated in a developmental defect involving enteric neurons as well as in tumorigenesis. The cells affected in both types of disorders are derived from the neural crest. Targeted disruption of mouse ret has revealed an additional role in kidney development. Here we report the analysis of a ret homolog in Drosophila melanogaster, an arthropod with no neural crest. Drosophila ret (D-ret) encodes a protein of 1,235 amino acids that has all of the domains identified in the vertebrate ret, including a cadherin motif. During embryogenesis, D-ret mRNA is first detected in the yolk sac at the late gastrula stage. In the postgastrula, D-ret is expressed in the foregut neurons, excretory system, peripheral ganglia, and the central nervous system. Thus, despite the wide divergence of early embryonic fate maps between vertebrates and invertebrates, D-ret is expressed in cells that are presumed to be the functional equivalents of the ret-expressing cells in vertebrates. Unexpectedly, D-ret is also expressed in the imaginal islands of the endodermal gut. These cells are proliferation-competent precursors for adult midgut that are diffusely embedded in the growth-arrested juvenile gut. These ret-expressing nonneuronal cells are strikingly analogous to vertebrate enteric neurons in their topography, but not in their cell fate. Our finding suggests a previously unrecognized phylogenetic relationship between the ret-expressing cells in vertebrates and the precursor reserves of metamorphosing insects.

Amino Acid Sequence↗