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Biomedical subjects

C Hoffmann

Publications and source records attributed to C Hoffmann.

At least 55 records · Page 3Linked to original sources
PubMed2000

Prothrombin G20210A, factor V Leiden, and factor XIII Val34Leu: common mutations of blood coagulation factors and deep vein thrombosis in Austria.

Mutations in the gene for prothrombin (F2 20210A) and factor V (F5 1691A, factor V Leiden) are established risk factors for deep venous thrombosis (DVT). Recently, a mutation in the gene for factor XIII (F13 100T) leading to a Valine-Leucine exchange at amino acid position 34 has been reported to be protective against DVT. To analyze the role of these mutations for DVT in Austria, we analyzed their prevalence in 154 patients with documented DVT and 308 sex- and age-matched control subjects. Allele frequencies of F2 20210A, F5 1691A, and F13 100T were 0.018, 0.039, and 0.274 among controls, and 0.045, 0.120, and 0.211 among patients, respectively. Odds ratios for DVT associated with F2 20210A, F5 1691A, and F13 100T alleles were 2.5 (95% CI: 1.1-5.7), 3.4 (95% CI: 1.9-5.8), and 0.7 (95% CI: 0.5-1.0). We conclude that F2 20210A, F5 1691A, and F13 100T are common mutations in the Austrian population. F2 20210A and F5 1691 increase the risk for DVT, whereas F13 100T is associated with a decreased risk for DVT. Routinely, analysis of these mutations may help to analyze the individual risk for DVT.

Adolescent↗
PubMed2000

Rotationplasty--surgical treatment modality after failed limb salvage procedure.

Twelve patients aged between 10.9 and 64.7 (mean 28.5) years with a malignant tumour of the knee region underwent a rotationplasty after failed primary limb salvage procedure. The reasons for failure which finally lead to surgery were recurrent infection in 10 patients and local recurrence of the tumour in 2. The number of operations before the rotationplasty was performed was between 2 and 23 (mean 6.7). According to the primary tumour site, 9 patients underwent a rotationplasty type A1, 3 patients type A2, and 1 patient type BII. In 9 patients the rotationplasty was successful, but 3 patients finally had to undergo amputation. Intraoperative preservation of the vessels was difficult in these 3 patients due to infection and oedema of the arteries or massive fibrous tissues after the previous surgery. After rotationplasty, 3 of 9 patients had to undergo additional surgery because of thrombosis, pseudarthrosis and infection (n = 5, range 1-2). The mean follow-up after rotationplasty was 34.9 (range 13-65) months. The mean functional status according to the MSTS criteria in patients after rotationplasty scored 21.3 of 30 points. In the group of amputees, the score was 19 (range 16-22). Concerning the health-related quality-of-life, the mean score in physical functioning was 76.3 in the group with a rotationplasty versus 50.0 in the group of amputees. Patients with a rotationplasty reached a higher score of global health status (77.1 vs 58.3). Based on the present results we are convinced that rotationplasty can be recommended as a treatment option after a failed limb salvage procedure.

Adolescent↗
PubMed2000

The influence of economic evaluation studies on decision making. A European survey. The EUROMET group.

Despite the growing activity in the field of health economics very little is known about the influence of economic evaluation studies on health care decision making in the EU member states. Several investigations about the impact of health economic studies on decision making have been performed, but most of them did not involve decision makers themselves. In this paper the results of the EUROMET survey are reported and discussed. Different types of decision makers in nine European countries were surveyed by postal questionnaires, semi-structured interviews and focus group discussions. Questions include issues about the extent of knowledge about economic evaluation, the actual and potential use of study results as well as barriers and incentives in the use of studies. It is concluded that despite the general positive attitude knowledge about the formal methodology is rather limited. Accordingly, results of economic evaluation studies are not widely used in decision making. The results show that institutional dimensions, such as difficulties in transferring budgets, are viewed as important barriers. Also, the lack of credibility of studies is assigned a high relevance. Moreover, decision makers wish for a better explanation of the practical relevance of studies and feel that there is a need for more training in health economics. Considering these requirements a number of recommendations for enhancing the value of health economic studies are given.

Attitude of Health Personnel↗
PubMed2000

Intraocular bacterial contamination during sutureless, small incision, single-port phacoemulsification.

PURPOSE: To evaluate the incidence of anterior chamber bacterial contamination during no-stitch, 1-handed, small incision phacoemulsification. SETTING: Little Company of Mary Hospital, Evergreen Park, Illinois, USA. METHODS: This study comprised 53 eyes of 46 patients. Topical gentamicin sulfate was administered 1 hour preoperatively. After povidone-iodine cleansing solution and povidone-iodine paint (5% and 10%) were applied, the eyes were draped in a sterile manner. Aqueous fluid was aspirated upon entering the anterior chamber and at the end of surgery; the specimens were cultured for up to 14 days. All eyes had no-stitch, 1-handed, small incision phacoemulsification with implantation of a foldable acrylic posterior chamber intraocular lens through a 3.5 mm scleral tunnel incision. RESULTS: Three specimens (5.7%) aspirated on entry into the anterior chamber were positive for microorganisms. Of the cultures obtained at the end of surgery, 4 (7.5%) were positive for microorganisms. All posterior lens capsules were intact. The following organisms were cultured at the end of phacoemulsification: alpha-streptococci, micrococci, saprophytic mold, alpha-viridans streptococci, coagulase-negative Staphylococcus species, and anaerobic positive cocci. No eye developed endophthalmitis. CONCLUSIONS: The incidence of anterior chamber bacterial contamination was low. Bacterial contamination of the anterior chamber occurred at the beginning and toward the end of phacoemulsification. Staphylococcus species was the most common organism in the beginning, while Streptococcus species was the most common at the end. Saprophytic mold was present only at the end. No eye developed endophthalmitis.

Aged↗
PubMed2000

CT diagnosis of malpositioned chest tubes.

Insertion of a chest tube into the pleural space is standard management for various pleural disorders. Malpositioning of chest tubes in extrathoracic, intraparenchymal and mediastinal locations and in the fissures is common. Malpositioning results not only in inadequate drainage of air and fluid but may also result in increased morbidity and mortality. Diagnosis of a malpositioned tube is sometimes difficult to establish on a chest radiograph. CT, however, has proven to be extremely accurate in evaluating the position of a chest tube and has often provided additional valuable information with significant therapeutic impact.

Adult↗
PubMed2000

Osteoarticular allograft in surgery for high-grade malignant tumours of bone.

We assessed the results of 17 limb-salvage procedures using osteoarticular allografts after wide resection of high-grade malignant bone tumours. All patients received chemotherapy. At the five-year follow-up, three patients had died from metastases. The allografts survived for five years in only seven patients all of whom had good function, ranging from 73% to 90% of normal. The allografts were removed because of fracture in seven patients and infection in one, and in all of these a second limb-salvage procedure was undertaken. With such a low rate of survival of osteoarticular allografts, we believe that their use in the management of high-grade malignant bone tumours should, at best, be considered a temporary solution.

Adolescent↗
PubMed2000

Electromyographic and gait analysis of forty-three patients after rotationplasty.

BACKGROUND: Rotationplasty is considered to be a treatment option for patients who have had a primary malignant bone tumor of the distal part of the femur or the proximal part of the tibia. The present study was performed to evaluate the muscle activity, the kinetics (range of motion of the hip and knee joints), and the kinematics (joint moments) after rotationplasty and to determine whether there was an association between these parameters and the functional outcome. METHODS: Forty-three patients who had been managed with rotationplasty for the treatment of a femoral or tibial bone tumor were evaluated clinically and functionally. The mean age (and standard deviation) at the time of follow-up was 24.4 +/- 10.7 years (range, eight to sixty-eight years), the mean age at the time of the procedure was 17.8 +/- 10.2 years (range, seven to sixty-three years), and the mean duration of follow-up was 6.7 +/- 4.9 years (range, 0.7 to eighteen years). Instrumented gait and electromyographic analyses were performed. The qualitative data were compared with the functional outcome, which was determined with the functional evaluation score of the Musculoskeletal Tumor Society. RESULTS: Gait analysis revealed a fairly normal walking pattern with a slight limp and a lateral lean of the trunk over the ipsilateral limb that led to a reduced joint moment in the hip (moment on involved side, 68 percent [compared with a control group]; moment on uninvolved side, 81 percent). The ranges of motion of the hips (uninvolved side, 42.0 +/- 8.2 degrees; involved side, 42.4 +/- 8.0 degrees) and the knees (uninvolved side, 59.7 +/- 5.0 degrees; involved side [former ankle joint], 58.1 +/- 11.6 degrees) were symmetrical even though the knee-motion pattern of the involved limb indicated a slightly reduced extensor mechanism in 51 percent (twenty-two) and a markedly reduced extensor mechanism in 35 percent (fifteen) of the forty-three patients. Electromyography revealed function of the muscles of the involved limb, with comparable amplitudes in the involved and uninvolved limbs. The leg muscles of the involved limb were active in the stance phase (the soleus and the lateral and medial heads of the gastrocnemius) and the swing phase (the peroneus longus and the tibialis anterior) according to their function in relation to the new knee joint. The patients had a good functional result, with a mean score of 23.9 +/- 2.7 of 30 points. With the numbers available for study, we could not show the duration of follow-up to be related to the overall outcome, but the age at the time of the operation was related to the total functional score as well as to gait and walking ability (p < 0.05). CONCLUSIONS: The results of the electromyographic and gait analyses demonstrated good functional restoration of gait following rotationplasty.

Adolescent↗
PubMed2000

COX-2 in brain and spinal cord implications for therapeutic use.

Following the discovery of inducible COX-2 in arthritic joint fluid and immunocompetent cells a revolution in the field of antiinflammatory treatment was expected. The detection of a constitutive COX-2 in the kidney, in stomach and central nervous system destroyed this hypotheses. Further experiments in animal models were done to elucidate the role of the constitutive COX-2 in different physiological and pathophysiological states. In central nervous system was shown that the constitutive COX-2 is the predominant isoform of cyclooxygenases in brain and spinal cord and is highly regulated by different mediators. After experimental induction of peripheral inflammation a significant induction of COX-2 gene, protein expression and synthesis of prostaglandins in the spinal cord was detected. It was concluded that COX-2 is strongly involved in pain mediation processing in the spinal cord. The detection of COX-2 in the brain endothelial cells and its role in fever led to new insights of development and time course of temperature elevation. Probably, the use of selective COX-2 inhibitors decreases fever more effective than classical antipyretics. Furthermore, newer results show a role of COX-2 in differentiation and maturation processes in brain. These findings implicate new ways for the treatment of Alzheimer's disease and other degenerative brain disorders. Clinical and experimental results with selective COX-2 inhibitors show a better safety profile than non-selective COX inhibitors. The clinical use after drug registration will be decide on the further role of this new class of drugs in analgesic/antiinflammatory therapy and on new fields of clinical use.

Animals↗
PubMed1999

[Common effect measures in medical and health economics studies? Results of an exploratory survey of physicians].

BACKGROUND: In economic evaluation studies quality-adjusted life years (QALYs) are often used as measure of effects. QALYs are calculated by weighting survival time with a valuation of health-related quality of life (HRQoL). The results may support clinical decisions for patient groups provided that physicians consider QALYs acceptable and clinically relevant. This study investigates whether physicians accept the various methodological steps of the calculation of QALYs and whether effect measures that result from these steps are useful in clinical studies, too. METHODS: In summer 1998, 41 physicians (21 principal investigators of clinical studies in oncology, 12 surgeons, 8 primary care physicians) completed a questionnaire. RESULTS: 90% of the physicians considered HRQoL a relevant measure of clinical effectiveness but only 54% were familiar with the concept of HRQoL. 80% accepted the creation of an index of HRQoL, 68% accepted the integration of HRQoL and survival time into a single effect measure, but only 44% accepted the multiplicative way of calculating QALYs. According to most physicians, HRQoL should be valued either by study patients or health care professionals rather than general population samples. 92% of the physicians considered identical effect measures in clinical and economic studies necessary or desirable. CONCLUSIONS: QALYs are not generally rejected by the responding physicians. The integration of HRQoL is largely accepted. The multiplicative way of combining survival time and HRQoL values is rejected by many physicians. The findings can be used to define a starting point for the development of common effect measures in medicine and health economics.

Attitude of Health Personnel↗
PubMed1999

The role of amino acids in extracellular loops of the human P2Y1 receptor in surface expression and activation processes.

The P2Y1 receptor is a membrane-bound G protein-coupled receptor stimulated by adenine nucleotides. Using alanine scanning mutagenesis, the role in receptor activation of charged amino acids (Asp, Glu, Lys, and Arg) and cysteines in the extracellular loops (EL) of the human P2Y1 receptor has been investigated. The mutant receptors were expressed in COS-7 cells and measured for stimulation of phospholipase C induced by the potent agonist 2-methylthioadenosine-5'-diphosphate (2-MeSADP). In addition to single point mutations, all receptors carried the hemagglutinin epitope at the N- terminus for detection of cell-surface expression. The C124A and C202A mutations, located near the exofacial end of transmembrane helix 3 and in EL2, respectively, ablated phospholipase C stimulation by </=100 microM 2-MeSADP. Surface enzyme-linked immunosorbent assay detection of both mutant receptors showed <10% expression, suggesting that a critical disulfide bridge between EL2 and the upper part of transmembrane 3, as found in many other G protein-coupled receptors, is required for proper trafficking of the P2Y1 receptor to the cell surface. In contrast, the C42A and C296A mutant receptors (located in the N-terminal domain and EL3) were activated by 2-MeSADP, but the EC50 values were >1000-fold greater than for the wild-type receptor. The double mutant receptor C42A/C296A exhibited no additive shift in the concentration-response curve for 2-MeSADP. These data suggest that Cys42 and Cys296 form another disulfide bridge in the extracellular region, which is critical for activation. Replacement of charged amino acids produced only minor changes in receptor activation, with two remarkable exceptions. The E209A mutant receptor (EL2) exhibited a >1000-fold shift in EC50. However, if Glu209 were substituted with amino acids capable of hydrogen bonding (Asp, Gln, or Arg), the mutant receptors responded like the wild-type receptor. Arg287 in EL3 was impaired similarly to Glu209 when substituted by alanine. Substitution of Arg287 by lysine, another positively charged residue, failed to fully restore wild-type activity.

Amino Acid Sequence↗
PubMed1999

Role of the extracellular loops of G protein-coupled receptors in ligand recognition: a molecular modeling study of the human P2Y1 receptor.

The P2Y1 receptor is a G protein-coupled receptor (GPCR) and is stimulated by extracellular ADP and ATP. Site-directed mutagenesis of the three extracellular loops (ELs) of the human P2Y1 receptor indicates the existence of two essential disulfide bridges (Cys124 in EL1 and Cys202 in EL2; Cys42 in the N-terminal segment and Cys296 in EL3) and several specific ionic and H-bonding interactions (involving Glu209 and Arg287). Through molecular modeling and molecular dynamics simulations, an energetically sound conformational hypothesis for the receptor has been calculated that includes transmembrane (TM) domains (using the electron density map of rhodopsin as a template), extracellular loops, and a truncated N-terminal region. ATP may be docked in the receptor, both within the previously defined TM cleft and within two other regions of the receptor, termed meta-binding sites, defined by the extracellular loops. The first meta-binding site is located outside of the TM bundle, between EL2 and EL3, and the second higher energy site is positioned immediately underneath EL2. Binding at both the principal TM binding site and the lower energy meta-binding sites potentially affects the observed ligand potency. In meta-binding site I, the side chain of Glu209 (EL2) is within hydrogen-bonding distance (2.8 A) of the ribose O3', and Arg287 (EL3) coordinates both alpha- and beta-phosphates of the triphosphate chain, consistent with the insensitivity in potency of the 5'-monophosphate agonist, HT-AMP, to mutation of Arg287 to Lys. Moreover, the selective reduction in potency of 3'NH2-ATP in activating the E209R mutant receptor is consistent with the hypothesis of direct contact between EL2 and nucleotide ligands. Our findings support ATP binding to at least two distinct domains of the P2Y1 receptor, both outside and within the TM core. The two disulfide bridges present in the human P2Y1 receptor play a major role in the structure and stability of the receptor, to constrain the loops within the receptor, specifically stretching the EL2 over the opening of the TM cleft and thus defining the path of access to the binding site.

Amino Acid Sequence↗
PubMed1999

ATP depletion, purine riboside triphosphate accumulation and rat thymocyte death induced by purine riboside.

Purine riboside (purine-1-D-ribofuranoside, nebularine), an adenosine analog, exerts cytotoxic effect both in vivo and in vitro. However, exact biochemical mechanism for its toxicity and sensitivity of lymphoid cells remains unknown. The present experiments have examined the sequential metabolic changes leading to cell death, induced in cultured rat thymocytes during incubation with purine riboside. Among 22 analogs tested, purine-riboside and tubercidin were most toxic as determined by trypan blue exclusion and lactate dehydrogenase leakage from the cells. 2-Chloroadenosine and 2'-deoxyadenosine were only moderately toxic, whereas other analogs tested were without effect on cell viability. In the presence of purine riboside, more than 90% of ATP was lost after 2 h of incubation. Hypoxanthine accumulated in the medium and the formation of purine-riboside triphosphate exceeded 4-fold the physiological concentration of ATP in the cell. Inhibition of adenosine kinase by 5-iodotubercidin reversed the cytotoxic effect of purine riboside. Interestingly, cells virtually deprived of ATP after 2 h of incubation with purine riboside maintained high nucleotide energy charge value and high viability. Purine riboside triphosphate was capable to replace ATP in stimulation of glycolysis in cell-free thymus extract. We conclude that for a short time (a few hours) purine riboside triphosphate formed in the cell may serve in the absence of ATP as an intermediate of cellular energy metabolism in rat thymocytes. However, possibly due to toxic effects of purine-riboside triphosphate, cells were finally dying. Thus, ATP depletion and adenosine kinase mediated purine riboside phosphates formation are the principle causes of rat thymocytes death exposed to purine riboside.

Adenosine↗
PubMed1999

Pelvic Ewing sarcoma: a retrospective analysis of 241 cases.

BACKGROUND: This article reports on 241 patients each with pelvic Ewing sarcoma registered for studies in Germany, Austria, and the Netherlands from January 1, 1981, until January 31, 1994. One hundred sixty-four patients had localized disease and 87 had metastases at diagnosis (PMP). Eighty-four patients with localized disease were entered on protocol (PP) and 80 were followed (FP). METHODS: Statistics included an analysis of event free survival by the Kaplan-Meier method and a Cox regression analysis of factors influencing prognosis. RESULTS: In the Kaplan-Meier analysis, on February 1, 1995, the event free survival (EFS) rate was 32% at 12 years for all patients, 54% for PP, 25% for FP, and 13% for PMP. Cox regression analysis showed that response to chemotherapy, initial metastases, and less intense therapy were significant prognostic factors. Among patients who had surgery for local control, the histologic response to chemotherapy was analyzed in the surgical specimen and had a significant influence on survival: EFS 69% for PP with good response compared with 47% (P = 0.11) for patients with poor response, and for FP 56% versus 13% (P = 0.002). All PP with small tumors had relapse free survival, compared with 69% of patients with medium-sized tumors and 36% of patients with tumors larger than 200 mL (P = 0.006). The initial tumor volume was a significant predictor of survival. CONCLUSIONS: Combined modality treatment has resulted in definitive improvement of prognosis for patients with localized pelvic Ewing sarcoma. However, the results for patients with metastases at diagnosis are still discouraging, and their treatment requires new approaches. Tumor load, responsiveness to chemotherapy, and adequate surgical margins are the major factors influencing the prognosis of patients with localized Ewing sarcoma of the pelvis.

Adolescent↗
PubMed1999

Evaluation of prognostic factors in a tumor volume-adapted treatment strategy for localized Ewing sarcoma of bone: the CESS 86 experience. Cooperative Ewing Sarcoma Study.

BACKGROUND: The Cooperative Ewing Sarcoma Study (CESS 86), conducted by the German Society of Pediatric Oncology and Hematology (GPOH), was planned on the basis of the results of the preceding CESS 81 study. The prognostic significance of tumor volume in localized Ewing sarcoma of bone was well documented in the CESS 81 trial. As a consequence, the treatment intensity was adapted to volume in the follow-up CESS 86 trial: the four-drug combination used in CESS 81 was amended for patients with large tumor volume (> or = 100 ml), where ifosfamide was substituted for cyclophosphamide. PROCEDURE: From January 1986 to June 1991, 177 protocol patients with localized Ewing sarcoma of bone were registered in CESS 86. The prognostic implication of tumor volume and several covariates was evaluated using Kaplan-Meier life table analysis and Cox's proportional hazard model. RESULTS: The estimated 5- and 8-year event-free survival (EFS) rates were both 59%. Age, gender, tumor site, and a tumor volume of 100 ml did not distinguish groups of patients with different prognosis. However, the prognosis of patients with tumors >200 ml (8-year EFS rate: 42%) was significantly inferior compared to patients with tumors both of 100 to 200 ml (70%) and of <100 ml (63%). In contrast to CESS 81, the histological response to chemotherapy was no longer a significant prognostic factor (EFS: 64% for good and 50% for poor responders, respectively). CONCLUSIONS: Despite risk-adapted treatment intensity, tumor volume retained its prognostic significance; the cut point, however, was shifted toward larger volumes.

Adolescent↗
PubMed1999

Adverse reactions after cosmetic lip augmentation with permanent biologically inert implant materials.

Augmentation of lips is a common aesthetic procedure that is mostly performed with alloplastic materials or autologous tissue. Various alloplastic injectable implants have been developed for soft tissue augmentation without surgery. Most biologic materials are resorbed within a few months, fluid silicone may migrate, and autologous fat is not ideal for fine contouring of the lips. The search for a biocompatible, permanent, nontoxic, and biologically inert filler material led to the development of some new materials for subdermal or intradermal implantation. Recently Bioplastique, Artecoll, and Gore-Tex have been well established and recommended by many authors. Although these materials meet most of the characteristics that constitute an ideal injectable prosthetic material, we describe 3 examples of adverse reactions after their implantation into lips.

Adult↗
PubMed1999

Adenosine-induced cell death: evidence for receptor-mediated signalling.

Adenosine modulates the proliferation, survival and apoptosis of many different cell types, ranging from epithelial, endothelial and smooth muscle cells, to cells of the immune and neural lineages. In this review, we critically discuss the available in vitro and in vivo data which support a role for adenosine in both development-associated apoptosis, and in diseases characterized by either pathologically increased cell death (e.g., ischemia, trauma and aging-associated neurodegeneration) or abnormally reduced spontaneous apoptosis (e.g., cancer). Particular emphasis is given to the possible role of extracellular adenosine receptors, since these may represent novel and attractive molecular targets for the pharmacological modulation of apoptosis. In some instances, adenosine-induced cell death has been demonstrated to require entry of the nucleoside inside cells; however, in many other cases, activation of specific adenosine extracellular receptors has been demonstrated. Of the four G protein-coupled adenosine receptors so far identified, the A2A and the A3 receptors have been specifically implicated in modulation of cell death. For the A3 receptor, results obtained by exposing both cardiomyocytes and brain astrocytes to graded concentrations of selective agonists suggest induction of both cell protection and cell death. Such opposite effects, which likely depend on the degree of receptor activation, may have important therapeutic implications in the pharmacological modulation of cardiac and brain ischemia. For the A2A receptor, recent intriguing data suggest a specific role in immune cell death and immunosuppression, which may be relevant to both adenosine-deaminase-immunodeficiency syndrome (a pathology characterized by accumulation of adenosine to toxic levels) and in tumors where induction of apoptosis via activation of specific extracellular receptors may be desirable. Finally, preliminary data suggest that, in a similar way to the adenosine-deaminase-immunodeficiency syndrome, the abnormal accumulation of adenosine in degenerative muscular diseases may contribute to muscle cell death. Although the role of adenosine receptors in this effect still remains to be determined, these data suggest that adenosine-induced apoptosis may also represent a novel pathogenic pathway in muscular dystrophies.

Journal Article↗
PubMed1999

Expanded polytetrafluoroethylene threads for lip augmentation induce foreign body granulomatous reaction.

Especially in cases of facial aesthetic surgery, the demands of the patients are high. The formation of a visible and painful nodule will cause not only discomfort but also dissatisfaction. When alloplastic materials are used for facial and lip augmentation, the possibility of migration, allergic reaction, and formation of a foreign body granuloma is always present. Although e-PTFE is the most bioinert alloplastic material available, the authors could show the formation of a foreign body granuloma. When using e-PTFE threads for facial augmentation, the surgeon should keep in mind and inform the patients that the threads can induce a foreign body granulomatous reaction.

Adult↗