Biomedical subjects
Publications and source records attributed to G Meyer.
The ability of cells to readjust their volume after swelling, a phenomenon known as regulatory volume decrease (RVD), is a fundamental biological achievement guaranteeing survival and function of cells under osmotic stress. This article reviews the mechanisms of RVD in mammalian cells with special emphasis on the activation of ion channels during RVD.
Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is a rare, but well-defined monogenic disorder that is caused by mutations in the autoimmune regulator (AIRE) gene on chromosome 21q22.3. Patients most often suffer from loss of endocrine function in the parathyroid and adrenal glands but may also develop Type 1 diabetes, thyroid disease or hypogonadism. The disease may therefore serve as a model for sporadic endocrine autoimmunity and help to develop new screening and prevention methods. To date at least 46 mutations of AIRE have been identified in affected individuals. Little is known about heterozygosity states but patients with the more prevalent isolated autoimmune endocrinopathies such as Type 1 diabetes, Hashimoto's thyroiditis, Graves' or Addison's disease do not have any of the common mutations. This does not rule out AIRE to be affected either by so far unknown or regulatory variants. The recent characterization of AIRE knockout mice with similar immune pathological findings compared to the human setting will help to elucidate endocrine autoimmunity.
INTRODUCTION: Aim of this study was the evaluation of antireflux surgery in Germany. METHODS: An anonymous questionnaire including 288 structured items about diagnostic and therapeutic approaches, complications and mortality was sent to 33% randomly selected German general surgeons (n = 546) at the end of 2000. RESULTS: A total of 2,540 antireflux procedures was reported, 81% were performed laparoscopically; 65% were total, 31% partial fundoplications. The number of surgeons offering laparoscopic antireflux surgery increased from 0.3% in 1990 to 5% in 1995 and to 32% in 2000. Numerous modifications regarding esophageal mobilisation, crural repair, kind and extension of the wrap, use and size of a bougie, as well as an additional gastropexy were observed. Morbidity rates were significantly higher for open than for laparoscopic procedures (15.0% vs. 7.7%), mainly caused by wound healing problems (4.4% vs. 0.8%) and splenic lesions (3.1 vs. 0.6%). Gastric and esophageal perforations were similar in both groups (1.1 vs. 0.9%). Hospital mortality rate was 0.1%. We observed a frequency dependent learning curve regarding complication rates after laparoscopic antireflux surgery (< 11 fundoplication p.a.: 14.0%; 11-30 fundoplications: 7.3% (p = 0.05); > 30 fundoplications: 4.2% (p = 0.05%). Long-term-dysphagia occurred more often after 360 degrees-versus partial fundoplications (6.6% vs. 2.4%; p < 0.001) and after Nissen/Nissen-Rossetti--than after Floppy-Nissen-procedures (6.6% vs. 3.6%, p = 0.1). The recurrency rate was 9.3% without significant differences between the procedures. CONCLUSION: Laparoscopy has replaced the open technique. Different technical approaches significantly affect the outcome after laparoscopic antireflux surgery in Germany.
A variety of endoscopic methods are available as the main tools in the diagnostics and therapy of various complications after visceral and thoracic surgery. Indications for endoscopic interventions are anastomotic leaks, stenoses, Gl-tract bleedings, biliary lesions and functional problems after surgical procedures. The most common are fibrin sealing of fistulas, dilatation and bougienage, injection therapy for bleeding, bile duct interventions and stent implantations. In most cases operative revisions can be avoided by using endoscopic methods with an overall good success rate. No disadvantages are foreseen following conventional operative interventions if the endoscopic treatment is not successful.
OBJECTIVES: The aim of this study was to evaluate in vitro the relationship between polymerization shrinkage and microleakage in dentin-bordered restorations. METHODS: Four light-cured restorative materials in combination with their respective dental bonding agents (DBA) were investigated: Tetric Ceram/Syntac classic (Vivadent), Solitaire/Gluma Solid bond (Heraeus Kulzer), Definite/Etch & Prime 3.0 (Degussa), Solitaire 2/Gluma Solid bond (Heraeus Kulzer). The chemically cured resin Degufill sc microhybrid (Degussa) in combination with ART Bond (Coltène) was also included. Polymerization shrinkage of the restorative materials was measured using three different methods (dilatometer, linometer, buoyancy method) and analyzed with ANOVA. For the determination of microleakage, caries-free human molars were embedded in acrylic resin and subsequently abraded with a wet abrasion machine to produce four level dentin surfaces. One hundred sixty cavities (3 mm diameter/1.5 mm deep) were randomly assigned to four groups of equal size. The groups were restored without (group 1 and 2) and with DBA (group 3 and 4), and either not subjected (group 1 and 3) or subjected (group 2 and 4) to 2000 cycles from 5-55 degrees C. Each group was further divided into five material subgroups of eight cavities each. Microleakage was determined using a dye penetration test assessed at depths of 200, 400 and 600 microm into the fillings. Data were analyzed with the Kruskal-Wallis and the Mann-Whitney test. RESULTS: All three methods of measuring polymerization shrinkage (PS) generated the same, statistically secured ranking for the four light-cured restorative materials: PS Definite < PS Tetric Ceram < PS Solitaire 2 < PS Solitaire. In the microleakage study, only a few statistically significant differences were observed. Etch & Prime 3.0/Definite in group 3 and Solid Bond/Solitaire 2 in group 4 tended to exhibit the least microleakage. Correlation coefficients between aggregated shrinkage and microleakage data were 0.3 for group 3 and -0.2 for group 4. SIGNIFICANCE: The results do not suggest any correlation between polymerization shrinkage and microleakage in dentin of direct adhesive restorations.
Type 1 diabetes mellitus is an autoimmune disease with a strong genetic background. The CTLA4 gene region (IDDM12) has been implicated in genetic susceptibility to type 1 diabetes by genome scanning and both family- and population-based analyses. As the genes encoding the costimulatory molecules CTLA4 and CD28, which compete for the receptor B7, reside close together on chromosome 2q33 and have high sequence homology, we investigated a recently described polymorphism in intron 3 of the CD28 gene and the CLTA4 codon 17 polymorphism in 176 patients with type 1 diabetes and 220 healthy controls. Whereas CTLA4 was found to be associated with type 1 diabetes, the frequency of the CD28 polymorphism did not differ between patients and controls, either in the entire sample or after stratification for CTLA4 genotype. Thus, the CD28 intron 3 polymorphism does not appear to be associated with susceptibility to type 1 diabetes.
BACKGROUND: Aim of this study was the evaluation of the management of choledocholithiasis and outcome of laparoscopic as well as open cholecystectomy in Germany. METHODS: A written questionnaire was sent to 449 randomly selected German surgeons annually from 1991 to 1994 and additionally to all German university hospitals until 1998. RESULTS: A total of 98 482 operations for gallstone disease including 86 485 cholecystectomies (non-university hospitals 1991-1993: n = 60 246, university hospitals 1991-1996: n = 26 239) and 8 433 common bile duct (CBD) explorations (non-university hospitals: n = 6 919, university hospitals: n = 1 514) with or without cholecystectomy were reported. The overall complication rate for CBD explorations was 13.2 % (non-university hospitals) and 15.1 % (university hospitals), the overall hospital mortality rate was 0.64 % (non-university hospitals) and 0.58 % (university hospitals, n. s.). When choledocholithiasis was suspected, in 1998 all university hospitals used a two-stage management with preoperative ERC. In case of diagnosed isolated choledocholithiasis 93 % usually chose an endoscopic approach. When simultaneous cholecysto-choledocholithiasis was diagnosed preoperatively 86 % of the university hospitals used a two-stage management with preoperative ERC and stone extraction and secondary cholecystectomy (1991: 45 %). The percentage of CBD explorations decreased continuously from 7.4 % in 1991 to 3.8 % in 1996 (p < 0.01). CONCLUSION: These results allow for the estimation of frequency and overall risks in surgical therapy of CBD stones. At the moment, laparoscopic CBD exploration does not play a significant role in Germany. Data show a trend to the two-stage "therapeutical splitting" with lower complication rates.
Eleven patients with congenital, traumatic and functional extrahiatal diaphragmatic lesions are reported. Since 1991 two patients with acute, two patients with old ruptures of the diaphragm and one patient with a Morgagni-Larrey-hernia were successfully treated by laparoscopic direct suturing. In two other patients with Morgagni hernias we used a polypropylene mesh for closure of the defect. One procedure was performed in a patient with symptomatic congenital dysplasia of the diaphragm with aplasia of the pericard. Laparoscopic plication of the diaphragm was performed in three symptomatic patients with phrenic nerve palsy after cardiac surgery. The intra- and postoperative course was uneventful in all cases. During a median follow-up of 60 months there was no recurrence. Therefore the laparoscopic technique is an effective and attractive alternative for treatment of these diseases.
Laparoscopy has improved surgical treatment of various diseases due to its limited surgical trauma and has developed as an interesting therapeutic alternative for the resection of colorectal cancer. Despite numerous clinical advantages (faster recovery, less pain, fewer wound and systemic complications, faster return to work) the laparoscopic approach to colorectal cancer therapy has also resulted in unusual complications, i.e. ureteral and bladder injury which are rarely observed with open laparotomy. Moreover, pneumothorax, cardiac arrhythmia, impaired venous return, venous thrombosis as well as peripheral nerve injury have been associated with the increased intraabdominal pressure as well as patient's positioning during surgery. Furthermore, undetected small bowel injury caused by the grasping or cauterizing instruments may occur with laparoscopic surgery. In contrast to procedures performed for nonmalignant conditions, the benefits of laparoscopic resection of colorectal cancer must be weighed against the potential for poorer long-term outcomes of cancer patients that still has not been completely ruled out. In laparoscopic colorectal cancer surgery, several important cancer control issues still are being evaluated, i.e. the extent of lymph node dissection, tumor implantation at port sites, adequacy of intraperitoneal staging as well as the distance between tumor site and resection margins. For the time being it can be assumed that there is no significant difference in lymph node harvest between laparoscopic and open colorectal cancer surgery if oncological principles of resection are followed. As far as the issue of port site recurrence is concerned, it appears to be less prevalent than first thought (range 0-2.5%), and the incidence apparently corresponds with wound recurrence rates observed after open procedures. Short-term (3-5 years) survival rates have been published by a number of investigators, and survival rates after laparoscopic surgery appears to compare well with data collected after conventional surgery for colorectal cancer. However, long-term results of prospective randomized trials are not available. The data published so far indicate that the oncological results of laparoscopic surgery compare well with the results of the conventional open approach. Nonetheless, the limited information available from prospective studies leads us to propose that minimally invasive surgery for colorectal cancer surgery should only be performed within prospective trials.
AIM: This study was designed to describe caries experience and treatment response in groups of children in three countries--Finland, Germany and Russia--with different systems of public dental care. MATERIALS AND METHODS: Information concerning permanent teeth (carious and filled surfaces, type of restorative treatment and applied sealants) was collected retrospectively from existing dental records of 12-year-old children who had been treated in dental practices over six years, retrospectively between 1995 and 1989. Prior to conducting the study, research meetings were held among all participating personnel to standardise data collection and terminology as much as possible. STATISTICS: The analysis of variance (ANOVA) was used to test the difference between the means of the various types of data derived from the three countries. RESULTS: Sealants were most commonly used in Finland at a rate of 5.0/child and 3.3 in Germany, but only for a few children in Russia (0.1). Caries increments (cumulative figure of primary and secondary caries surfaces over the six follow-up years of the study) differed very much between these countries. It was very high in Russia (7.4) and in Germany (5.3), but low in Finland (1.6). All the caries surfaces were filled in Finland and in Germany; in Russia, the cumulated number of filled surfaces was smaller than the respective number of caries surfaces (6.4/7.4). The most commonly used restorative filling material was amalgam in Germany and in Russia, but composite or glass ionomer cements in Finland. CONCLUSION: The cost effectiveness of sealant application programs should be considered as exemplified by the Finnish dental care system. The data showed a need for preventive programs in Germany, and this has actually been emphasised since 1993. In Russia, there is an urgent need to implement preventive programs for 6-year-old children and also to provide the necessary restorative treatment.
A 40-year-old woman with complaints of relapse in the upper abdomen and dysphagia was referred for laparascopic hiatal hernia repair. Chest radiograph, barium-swallow, and upper endoscopy revealed a paraesophageal hernia. Esophageal manometry and 24-h-pH study showed no pathological findings. A laparoscopic gastropexy was planned. Intraoperatively, in contradiction to the preoperative findings, an extrahiatal hernia containing most of the stomach was found. After resection of the hernia sac, the beating heart without covering pericardium was seen. These findings were confirmed by an additional thoracoscopy at the end of the operation. The defect was closed by direct suturing. The postoperative course and 2-month follow-up were uneventful. The resected parts of the hernia sac showed an embryonic and dysgenetic etiology. This rare malformation has been reported in combination with complex syndromes, which appear with serious clinical and morphological signs in the neonatal period. In adults, the pericardial aplasia can be observed during diagnostic or surgical interventions. In these patients, complaints are usually not caused by the malformation but may be due to the occasional herniation of abdominal organs. We consider laparoscopic repair to be a gentle and safe procedure for the treatment of extrahiatal hernias.
A representative anonymous questionnaire was sent to all German university hospitals ( n=45) to address the development and outcome of laparoscopic gallstone surgery between 1991 and 1998. The response rate was 64%, and 28,753 operations for gallstone disease were analysed. Two-thirds of the procedures (67%) were performed laparoscopically. While a significant decrease of surgical complications (1991 vs 1998: 5.4% vs 3.4%; P<0.001) and re-laparotomy rate (1.0% vs 0.5%, P<0.05) was observed, no significant changes were detected with regard to the mortality rate. A learning curve regarding common bile duct (CBD) injuries was detected, showing a significant increase between 1991 and 1994 (0.3% and 0.7%, respectively, P<0.05) and a decrease to 0.2% in 1995 and 1996 ( P<0.05). The use of intraoperative cholangiography is compulsory in 10%, selective in 52%, while 38% of the university hospitals never use it. Most institutions use the Veress needle for pneumoperitoneum installation, and 93% use hook cautery for dissection. Since 1998, 45% of all institutions have also used the harmonic scalpel. The spectrum of indications for laparoscopic procedures has increased with time since acute cholecystitis, CBD stones and adhesions are not considered a general reason for a primary open approach. Our findings confirm a learning curve with regard to postoperative morbidity after laparoscopic cholecystectomy. This observation may be due to better training as well as surgical experience.
The effects of the vaccination of neonatal calves with a glycoprotein E (gE)-negative bovine herpesvirus type 1 (BHV-1) were investigated in naïve and passively immunised calves either with the recommended dose or a 5-fold concentrated one. After inoculation (PI), all calves excreted the virus vaccine except three passively immunised calves inoculated with the lower titre. No antibody response could be detected in passively immunised calves, whatever the dose used, and they all became BHV-1 seronegative and remained so after dexamethasone treatment (PDT). Nevertheless, as shown by a gamma-interferon assay, all calves that excreted the vaccine PI developed a cell-mediated immune response and a booster response was observed PDT, suggesting viral reactivation. The vaccine virus was recovered PDT from nasal secretions in two calves and BHV-1 DNA were detected in trigeminal ganglia from five calves belonging to all inoculated groups. The results show that the BHV-1 gE-negative vaccine can establish latency not only in naïve but also in passively immunised neonatal calves after a single intranasal inoculation. Moreover, this study shows for the first time that the gE-negative vaccine, when used in passively immunised calves, can lead to seronegative vaccine virus carriers.
The technique of single atom manipulation by means of the scanning tunneling microscope (STM) applies to the controlled displacement of large molecules. By a combined experimental and theoretical work, we show that in a constant height mode of manipulation the STM current intensity carries detailed information on the internal mechanics of the molecule when guided by the STM tip. Controlling and time following the intramolecular behavior of a large molecule on a surface is the first step towards the design of molecular tunnel-wired nanorobots.
The oxidative addition of phenyl iodide to the palladium(o) generated from [Pd0(dba)2] and n equivalents of AsPh3 (the most efficient catalytic precursor in Stille reactions) proceeds from [(solv)Pd0(AsPh3)2] (solv= solvent). However, the latter is present only in trace concentrations because it is involved in an equilibrium with the major, but nonreactive, complex [Pd0(dba)(AsPh3)2]. As regards the phosphine ligands, dba has a decelerating effect on the rate of the oxidative addition by decreasing the concentration of the reactive species. Relative to PPh3, the effect of AsPh3 is to increase the rate of the oxidative addition of PhI by a factor ten in DMF and seven in THF, independent of the value of n, provided that n > or = 2. In contrast to PPh3, the addition of more than two equivalents of AsPh3 to [Pd0(dba)2] (dba= trans,trans-dibenzylideneacetone) does not affect the kinetics of the oxidative addition because of the very endergonic displacement of dba from [Pd0(dba)(AsPh3)2] to form [Pd0(AsPh3)3]. The complex trans-[PhPdI(AsPh3)2], formed in the oxidative addition, is involved in a slow equilibrium with the T-shaped complex [PhPdI(AsPh3)] after appreciable decomplexation of one AsPh3. Under catalytic conditions, that is, in the presence of a nucleophile, such as CH2=CH-SnBu3 which is able to coordinate to [Pd0(AsPh3)2], a new Pd0 complex is formed: [Pd0(eta2-CH2=CHSnBu3)(AsPh3)2]; however, this complex does not react with PhI. Consequently, CH2=CH-SnBu3 slows down the oxidative addition by decreasing the concentration of the reactive species [(solv)Pd0(AsPh3)2]. This demonstrates that a nucleophile may be not only involved in the transmetallation step, but may also interfere in the kinetics of the oxidative addition step by decreasing the concentration of reactive Pd0.
HISTORY: Case 1. Thrombotic-thrombocytopenic purpura (TTP, Moschkowitz' disease) in a 57-year-old woman had for one year been treated conservatively. But when daily plasmapheresis was temporarily discontinued she developed behavioural changes and impaired speech, providing an indication for splenectomy. Case 2. A 53-year-old woman with TTP had been similarly treated for one month. Splenectomy was indicated when neurological symptoms rapidly developed. INVESTIGATIONS: At admission, creatinine 110 mg/d, white cell count (WBC) 12.4 G/l haemoglobin 10.1 g/dl, haematocrit 0.29, platelets 91 G/l. Prothrombin time (PTT) and thromboplastin time were normal. Patient 2. At admission, platelet count was below 10 G/l and she had various neurological abnormalities. Haemoglobin was 9.0 f/dl, haematocrit 0.27. Platelet count, PTT, thromboplastin time and renal functions were normal. TREATMENT AND COURSE: Case 1. After plasmapheresis and administration of cryoprecipitate-free fresh frozen plasma (FFP) excess, laparoscopic splenectomy was performed. On the third postoperative day WBC count was 11.5 G/l, haemoglobin level was unchanged, but platelet count was now normal, as were PTT and thromboplastin time and renal functions. 8 and 32 months after the operation WBC count, haemoglobin, haematocrit and platelets were all normal. There were no neurological abnormalities postoperatively. Case 2. Laparoscopic splenectomy was performed after intensive haematological preparation. The pre- and postoperative course was uneventful and she was discharged on the 8th postoperative day, at which time her haemoglobin was 8.4 g/dl, haematocrit 0.25, while platelets, PTT, thromboplastin time and renal functions were all normal and remained so at follow-up 11 months later. There have been no neurological symptoms after the splenectomy. CONCLUSION: Laparoscopic splenectomy is a haematologically and surgically safe treatment of TTP and should be considered for all cases of TTP that fail to respond to conservative management.
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In situ X-ray absorption near edge structure (XANES) investigations were carried out at chlorine K edge and palladium L3 edge to study the mechanism of the thermal decomposition of ammonium hexachloropalladate. The spectra show a characteristic feature for the initial step that might be explained as the formation of the precursor via ligand exchange (Cl --> NH3). Multiple scattering calculations (Feff 8) for the Cl K, Pd and Rh L3 edges were successful in simulating the XANES spectra of the precursor as well as the reference compounds (NH4)2 [PdCl4] and (NH4)3[RhCl6].