Biomedical subjects

S Benz

Publications and source records attributed to S Benz.

At least 19 recordsLinked to original sources

PubMed2006

Solid ammonium sulfate aerosols as ice nuclei: a pathway for cirrus cloud formation.

Laboratory measurements support a cirrus cloud formation pathway involving heterogeneous ice nucleation by solid ammonium sulfate aerosols. Ice formation occurs at low ice-saturation ratios consistent with the formation of continental cirrus and an interhemispheric asymmetry observed for cloud onset. In a climate model, this mechanism provides a widespread source of ice nuclei and leads to fewer but larger ice crystals as compared with a homogeneous freezing scenario. This reduces both the cloud albedo and the longwave heating by cirrus. With the global ammonia budget dominated by agricultural practices, this pathway might further couple anthropogenic activity to the climate system.

Journal Article↗

PubMed2005

[Comparison of various methods of surgical hernia repair].

Over the last 15 years, a number of different procedures for hernia repair have been developed. Apart from the open techniques, with or without the use of a prosthetic mesh or mesh plug, endoscopic procedures such as transabdominal preperitoneal (TAPP), and totally endoscopic preperitoneal (TEPP), hernioplasty are now established operations. In the present paper, the common open surgical procedures are compared with the minimally invasive repairs with regard to practicability, postoperative wound pain and complications, mobilization, recurrence rates and cosmesis. In the view of the authors, the standard method for inguinal hernial repair is the open Lichtenstein procedure or the Rutkow patch and plug method.

Germany↗

PubMed2005

Protective effect of endotoxin preconditioning in pancreas: analysis with DNA chip arrays.

Recently we demonstrated a protective effect of endotoxin preconditioning 24 hours before pancreatic ischemia-reperfusion injury, which has also been described for other organs. The mechanisms underlying this phenomenon, such as differential gene expression, are poorly investigated. We chose to approach this question by investigating differential gene expression in the rat pancreas over the time course of endotoxin pretreatment. Male Wistar rats (5 groups, 5 animals per group) were pretreated with endotoxin intraperitoneally (1 mg/kg of body weight). After treatment at 30 minutes, and at 3 and 24 hours the pancreas was removed. Untreated animals and animals with injection of saline solution served as controls. After RNA isolation, RNA was pooled and hybridized to Affymetrix chips to measure the relative mRNA levels of 7000 genes and 1000 expression sequence tags. Three hours after administration of endotoxin there was an activation of proinflammatory transcription factors and other proinflammatory genes. After 24 hours there was a clear decrease of these proinflammatory genes, but a remaining and increasing upregulation of important antiapoptotic genes, antiproteases, and other probably protective genes. There was also a significant upregulation of complement factors. It was surprising that heat-shock proteins and other typical immediate early genes of the AP-1 complex were not upregulated. Our data show that 24 hours after endotoxin stress there is a regulation of a network of genes that represents a multifaceted preconditioning. As most important factors, inhibition of apoptosis and antiproteatic strategies are identified. Heat-shock proteins seem to play no important role in the mechanism of endotoxin preconditioning.

Animals↗

PubMed2004

Heterotopic pancreatitis with obstruction of the major duodenal papill--a rare trigger of obstructive orthotopic pancreatitis.

BACKGROUND: Heterotopic pancreas appears in 0.5 to 13% of autopsies. The most frequent locations are stomach, duodenum or upper jejunum. Pancreatitis in heterotopic pancreas is rarely described, and clinical symptoms caused by this heterotopic inflammation are uncommon. METHOD: We report a case of heterotopic pancreatitis localized in the major duodenal papilla causing biliary obstruction and mimicking a pancreatic head tumor. Clinically and radiologically, malignancy was suspected. Preoperative biopsies showed only fibrosis. A pylorus preserving resection of the pancreatic head was performed followed by an uneventful postoperative course. RESULT: Macroscopically, in the periampullary region on the pancreatic side a thickened duodenal wall with multiple lobules and cysts was found, compressing the common bile duct. Microscopic examination showed heterotopic pancreas with inflammatory lesions surrounding the ampulla. In the orthotopic pancreas a diffuse chronic pancreatitis with marked inflammation, fibrosis and atrophy of exocrine tissue was found. CONCLUSION: In our case it was impossible to differentiate between chronic pancreatitis and pancreas carcinoma preoperatively. Radiological findings and endoscopic biopsies were not sufficient to distinguish heterotopic pancreatitis from other tumors of the pancreatic head. Clear diagnosis could only be made by complete histological examinations after pancreatic head resection, being the treatment of choice for pancreatic head tumors of unclear dignity. The differential diagnosis of heterotopic pancreatitis as trigger of unclear enlargement of the pancreatic head is very seldom.

Cholestasis↗

PubMed2004

Influence of nitric oxide on microcirculation in pancreatic ischemia/reperfusion injury: an intravital microscopic study.

Recently, protective effects of nitric oxide donors in pancreatic ischemia/reperfusion (IRI) injury have been described. Their role in post-ischemic microcirculation was previously not investigated. Ischemia reperfusion was induced in an isolated pancreatic tail segment in situ. Animals were randomized to four experimental groups (n=7 animals/group), the control group (CO) received saline as placebo. Treatment groups received either sodium nitroprusside (SN) 5 min before until 2 h after reperfusion, L-arginine (LA) 30 min before reperfusion until 2 h after reperfusion or sodium nitroprusside and L-arginine (SNLA) together. After induction of ischemia (2 h) post-ischemic microcirculation was observed for 2 h by intravital-fluorescence microscopy. Functional-capillary density (FCD), leukocyte adherence in post-capillary venules (LAV) and histological damage were analysed. After reperfusion FCD decreased in all groups (P<0.05). FCD was significantly restored in all groups with administration of nitric oxide donors after reperfusion (P<0.05) as compared to CO without significant difference between the individual nitric oxide donor groups. Leukocyte adherence was significantly increased 1 h and 2 h after reperfusion (P<0.001) as compared to baseline, which was lower in all nitric oxide donor groups. Histological damage in the pancreatic tail-segment was significantly reduced in nitric oxide donor groups (P<0.01). Administration of nitric oxide donors might be useful in ischemia-reperfusion injury of the pancreas by its protective effect on microcirculation and inflammatory reaction.

Animals↗

PubMed2004

Endoscopic management of pancreatic fistulas secondary to intraabdominal operation.

BACKGROUND: Pancreatic fistulas may arise secondary to several disorders of the pancreas. Although approximately 70% of pancreatic fistulas close with nonoperative management, this course of treatment usually takes several weeks or even months. To reduce this long period, closures with fibrin glue have been attempted in the past. In this study, we describe the course, management, and outcome of eight patients with postoperative external pancreatic fistulas of the pancreatic body and tail that arose after oncologic operations in the upper abdomen. METHODS: All eight cases were treated by external drainage, insertion of an endoprosthesis into the pancreatic duct, and closure of the fistula with fibrin glue. RESULTS: Immediately after this intervention, secretion from the fistulas was absent in all cases. None of the patients developed abscesses, recurrent fistulas, or complications associated with the fibrin glue. CONCLUSION: The early endoscopic management of postoperative pancreatic fistula with an approach combining internal drainage of the pancreatic duct and external occlusion of the fistula with fibrin glue is expeditious and beneficial.

Cholangiopancreatography, Endoscopic Retrograde↗

PubMed2004

High levels of C-reactive protein after simultaneous pancreas-kidney transplantation predict pancreas graft-related complications and graft survival.

BACKGROUND: Although pancreas graft-related complications are frequent after simultaneous pancreas-kidney transplantation (SPK), there are no parameters predicting the risk for these complications. METHOD: A two-center retrospective study was performed in 97 patients who underwent SPK to investigate the peak serum value of c-reactive protein (CRP) during the first 72 hr after SPK in view of graft-related complications and graft survival. RESULTS: Mean peak CRP was 115.6 +/- 71.5 mg/L. Mean peak CRP was higher in patients needing relaparotomy (n=31) (136.4 vs. 105.8 mg/L, P=0.048), especially when postoperative bleeding was excluded (P=0.015); in patients with graft pancreatitis (P=0.03); and in patients with graft loss (n=19; P<0.001) compared with patients without these complications. With a cut-off of peak CRP at the level of mean plus 1 SD (187.05 mg/L), there was a significantly higher incidence of relaparotomies (P=0.01; bleedings excluded: P=0.003), graft pancreatitis (P=0.03), and pancreas graft loss (P<0.0001) in patients with high peak CRP compared with patients with low peak CRP. No differences were noticed with regard to rejection rate, mortality, and kidney graft loss. CONCLUSION: Our findings suggest that peak CRP is a helpful parameter in predicting pancreas graft-related complications and pancreas graft survival after SPK. Our results also stress the importance of early graft damage in pancreas transplantation.

Adult↗

PubMed2004

Ischemic preconditioning attenuates capillary no-reflow and leukocyte adherence in postischemic pancreatitis.

BACKGROUND AND AIMS: Ischemic preconditioning (IPC) has been shown to protect several organs from ischemia-reperfusion injury. Postischemic microvascular dysfunction is considered to be the key mechanism of early graft pancreatitis after transplantation. The aim of the study was to determine whether brief ischemia and reperfusion before prolonged ischemia followed by reperfusion is protective in respect to microcirculatory derangement in postischemic pancreatitis. METHODS: In an in-situ model of ischemia-reperfusion was induced in the isolated pancreatic tail segment. Wistar rats were randomized to one group ( n=7/group) with 2-h ischemia and reperfusion (I/R) and another group with 10-min ischemia and 10-min reperfusion (IPC) before the prolonged ischemia time. Microcirculation was observed for 2 h by intravital-fluorescence microscopy that analyzed functional capillary density and leukocyte adherence in postcapillary venules. Histological damage was quantified by a semiquantitative score (edema, vacuolization, PMN infiltration, necrosis). RESULTS: IPC resulted in a significant improvement of functional capillary density (248+/-20 vs 372+/-8 cm(-1), P<0.001), a significant reduction in leukocyte adherence in postcapillary venules (476+/-79 vs 179+/-15 cells/mm(2), P<0.001) and in significantly lower histological damage (score 9+/-0.8 vs 5+/-1.4, P<0.001), when compared with the ischemia-reperfusion group. CONCLUSION: IPC reduces pancreatic inflammatory reaction by preservation of postischemic microcirculation. Therefore, it might become a useful procedure before organ procurement in pancreas transplantation.

Acute Disease↗

PubMed2004

Transdermal lisuride delivery in the treatment of Parkinson's disease.

Transdermal delivery of dopamine agonists (DA) is a promising therapeutic concept, which aims to ameliorate frequency and intensity of motor fluctuations in patients with Parkinson's disease (PD). We treated 8 PD patients with unpredictable on-off phenomena with lisuride patches (release: 2-5 microg lisuride base/cm2/hour in mice) in addition to their preexisting antiparkinsonian drug regime up to a period of 8 days. In order to quantify the intensity and frequency of motor fluctuations, we determined the motor changing rate (MCR), which corresponds to the patient's self rating of motor function, performed every thirty minutes, divided through the number of scored intervals minus 1. Additional lisuride patch application significantly (p = 0.023) improved the MCR compared to baseline. Relevant side effects were transient skin irritations in four patients. Our observational study demonstrates the safety, tolerability and efficacy of transdermal lisuride delivery in the treatment of motor complications.

Administration, Cutaneous↗

PubMed2004

Worsened motor test performance following acute apomorphine injection in previously untreated patients with Parkinson's disease.

Instrumental tests and clinical rating assess motor disability in Parkinson's disease (PD) patients. Previous long-term dopaminergic substitution influences the behaviour following acute dopaminergic stimulation. Objective of this study was to investigate the motor response following an apomorphine application in previously untreated-, treated- and before treated PD patients, who received placebo. Outcomes of instrumental tests worsened in previously untreated-, but not in before treated PD patients after apomorphine injection and in the PD subjects under the placebo condition. Generally, rating scores of motor symptoms significantly improved after apomorphine administration, whereas placebo application showed no effects. Tolerance to sedative effects of apomorphine in treated PD patients or sensitivity of employed motor tests to presynaptic dopaminergic autoreceptor mediated inhibition of endogenous dopamine release or postsynaptic dopaminergic overstimulation with resulting decreased cognitive function in previously untreated PD patients hypothetically caused this discrepancy between outcomes of subjective clinical rating and objective motor test performance.

Adult↗

PubMed2004

Apoptosis is caused by prolonged organ preservation and blocked by apoptosis inhibitor in experimental rat pancreatic grafts.

UNLABELLED: Apoptosis is a major mode of cell death after ischemia/reperfusion injury in several organs. The aims of this study were to evaluate apoptosis induction after different conditions of pancreas preservation and to investigate the impact of a caspase inhibitor on apoptosis induction in pancreatic grafts. METHODS: Inbred male Lewis rats served as donors and recipients. Apoptosis was detected using an in situ cell death detection kit and an apoptotic DNA ladder kit (Roche, Germany). An apoptotic index (AI) was defined as the number of apoptotic cells per field (400x) under a light microscope. The five groups included: group 1 (n = 5), normal pancreata; group 2 (n = 7), pancreata stored in University of Wisconsin (UW) solution (4 degrees C) for 6 hours (hr); group 3 (n = 7), pancreata preserved in UW solution (4 degrees C) for 18 hr; group 4 (n = 7), pancreata preserved in 0.9% saline (4 degrees C) for 6 hours; and group 5 (n = 5), pancreata preserved in 0.9% saline (4 degrees C) for 6 hours with Z-Asp-2,6-dichlorobenzoyloxymethylketone (caspase inhibitor) treatment. The pancreatic grafts in all experimental groups underwent a 2-hr period of reperfusion after transplantation. RESULTS: The results in this study showed that the AI was not significantly increased among pancreatic grafts in group 2 compared to group 1 (P >.05). However, AI in group 3 was significantly higher than that in group 2 (P <.05). The highest AI was observed in group 4. Interestingly, AI in group 5 was significantly lower than that in group 4 (P <.01), and not significantly different from group 1 (P >.05). Apoptotic DNA ladders were detected in the pancreatic grafts in group 2, 3, and 4, but not in group 1 and 5. CONCLUSIONS: Prolonged preservation of pancreata in cold UW solution induces a dramatic increase in apoptotic cell death among the pancreatic grafts following Tx. This observation may well be an important mechanism of graft damage. A caspase inhibitor might be useful to inhibit apoptosis induction in pancreatic grafts.

Adenosine↗

PubMed2004

Differential response in choice reaction time following apomorphine based on prior dopaminergic treatment.

Choice reaction time (CRT) paradigms demonstrated deficits in the preparation and execution of movements in patients with Parkinson's Disease (PD). Predominantly these trials did not consider an influence of acute and long-term dopaminergic substitution. Objective was to determine the acute effect of apomorphine on the response to a repeatedly performed CRT task. We repeatedly executed the CRT paradigm before and after subcutaneous apomorphine injection in previously treated, untreated and long-term dopamine substituted PD patients, who took placebo. No significant change of CRT and movement time (MT) appeared in PD patients with chronic dopaminergic drug intake after apomorphine injection. CRT and MT both significantly worsened in untreated PD patients. Placebo application induced no significant alteration. Binding of apomorphine to presynaptic autoreceptors with subsequent sedation or inhibition of locomotor activity hypothetically explain our results in before untreated PD patients. Previous long-term dopaminergic substitution may cause a certain tolerance to this phenomenon.

Adult↗

PubMed2004

Pancreas graft thrombosis: is there a role for trypsin.

PURPOSE: Thrombosis of the pancreas graft is the main cause of early graft loss in pancreas transplantation. We investigated whether hypercoagulability develops locally in the pancreas and contributes to thrombosis formation because of ischemia or reperfusion injury. It was further hypothesized that this might be induced by excessive intravascular trypsin activity. METHODS: Ten Patients undergoing pancreas transplantation were studied. In addition to the standard operation a 14 French catheter was inserted in the distal part of the splenic vein of the pancreas graft. After reperfusion blood samples were drawn simultaneously from the splenic vein of the pancreas graft (local samples) and the radial artery (systemic samples) at 0,1,2,5,10,30, and 60 minutes after reperfusion. RESULTS: After reperfusion a progressive hypercoagulability developed locally in the pancreas as seen by an increase of thrombin-antithrombin complexes and only a transient increase of plasmin-antiplasmin complexes. In addition antithrombin 3 and protein c decreased systemically. The alterations seem not to be triggered by trypsin because trypsin activity locally remained low despite trypsinogen release and activation as assessed by trypsinogen activation peptides. CONCLUSION: Local hypercoagulability might contribute to the development of graft thrombosis, however, the mechanism seems not to be related to ectopic trypsin activation.

Antithrombins↗

PubMed2004

Fusion of computed tomography data and optical 3D images of the dentition for streak artefact correction in the simulation of orthognathic surgery.

OBJECTIVE: To determine the limits of accuracy of fusion of optical three-dimensional (3D) imaging and computed tomography (CT) with and without metal artefacts in an experimental setting and to show the application of this hybrid system in 3D orthognathic surgery simulation. METHODS: Ten plaster casts of dental arches were subjected to a CT scan and optical 3D surface imaging. Subsequently, the first molars in the plaster casts were supplied with metal restorations, bilaterally, and new CT scans and optical surface images were assessed. The registration of the surface data of the two imaging modalities of the study models without and with metal restorations was carried out. The mean distance between the two data sets was calculated. From a patient a CT scan of the skull as well as optical 3D images of plaster casts of the dental arches were acquired. Again the two imaging modalities were registered and virtual orthognathic surgery simulation was carried out. RESULTS: The mean distance between the corresponding data points of CT and optical 3D surface images was 0.1262+/-0.0301 mm and 0.2671+/-0.0580 mm, respectively, for the plaster casts without and with metal restorations. The differences between these data were statistically significant (P<0.0005). For the patient case a mean difference of 0.66+/-0.49 mm and 0.56+/-0.48 mm for mandible and maxilla, respectively, was calculated between CT and optical surface data. CONCLUSION: The accuracy of the fusion of 3D CT surface data and optical 3D imaging is significantly reduced by metal artefacts. However, it seems appropriate for virtual orthognathic surgery simulation, as post-operative orthodontics are performed frequently.

Adult↗

PubMed2003

Value of ultrasound in the diagnosis of acute appendicitis: interesting aspects.

OBJECTIVE: The value of ultrasound in the diagnosis of acute appendicitis is still unclear. Both, studies with excellent and such with disappointing results have been published. The aim of this investigation was to answer the question, whether the results of these studies depend on study design, the investigating clinical department, or the number of ultrasound investigators. METHODS: A systematic literature research (PubMed (NLM) database) was performed. Of 99 publications dealing with ultrasound in the diagnosis of acute appendicitis, 69 were relevant to investigate the value of ultrasound in suspected appendicitis. RESULTS: Results of single-center studies (sensitivity 81.6%, specificity 89.8%, accuracy 85.7%) are better then those of multi-center trials (38.3%, 87.6%, 62.9%). There are no distinct differences between the investigating departments (surgeons 78.9%, 88.9%, 86.0%; radiologists 83.1%, 88.1%, 83.5%; mixed 77.8%, 87.1%, 79.4%, no specification 73.8%, 87.1%, 80.45.9%). Less than 10 investigators showed better diagnostic values (84.3%, 86.8%, 85.6%) compared to studies with 10 or more investigators (64.7%, 88.6%, 67.7%). CONCLUSION: The results of multi-center trials are disappointing and the good results of single-center studies do not reflect surgical everyday life. However, excellent results can be obtained if the investigation is restricted to a few specialists irrespectively of the clinical department.

Acute Disease↗

PubMed2003

Repeated rating improves value of diagnostic dopaminergic challenge tests in Parkinson's disease.

Clinicians use acute challenges with levodopa (LD) and/or apomorphine (A) for diagnostic dopaminergic response tests in Parkinson's disease (PD) patients. We consecutively compared the value of both drugs with performance of repeated ratings and adverse effect recording. Oral administration of 200 mg LD was superior to subcutaneous injection of 4 mg A in terms of tolerability and onset of temporary UPDRS motor score decline ([previously untreated PD patients] LD: 4.02 [mean] +/- 2.45 [SD] [significant decrease: p = 1.42 E-07] vs. A: 1.58 +/- 3.38 [not significant decrease: p = 0.14], p = 0.0009; [treated PD patients] LD: 7.71 +/- 4.35 [significant decrease: p = 2.48 E-06] vs. A: 5.19 +/- 4.32 [significant decrease: p = 7.83 E-05], p = 0.07). We suggest diagnostic acute challenge test performance with LD as first- and A as second choice due to better tolerability and valuation in combination with repeated scoring procedures to improve sensitivity and specifity.

Administration, Oral↗

PubMed2002

Effect of nitric oxide in ischemia/reperfusion of the pancreas.

BACKGROUND: Ischemia/reperfusion injury, and thus graft pancreatitis, remains a major problem in pancreas transplantation. Contradictory results about the role of nitric oxide (NO) in pancreatic ischemia/reperfusion have been reported; however, in none of the reports has a detailed comparison between inhibition of NO synthase and NO supplementation been carried out. METHODS: Vascular isolation of the pancreatic tail was performed in landrace pigs. After splenectomy catheters placed in the distal part of the splenic vessels allowed collection of the venous effluent and perfusion of the pancreatic tail. Three hours of complete warm ischemia was followed by 6 h of reperfusion. The effect of the NO donor sodium nitroprusside (SNP) and L-arginine was compared to a control group and NO synthase inhibition with L-NAME. RESULTS: Lipase in the venous effluent of the pancreas was significantly decreased in the SNP and the L-arginine groups. Vascular resistance was markedly elevated in the L-NAME group and reduced in the NO donor groups. Tissue pO2 after reperfusion was only significantly elevated in the SNP group. Granulocyte infiltration and also overall histological tissue injury were most severe in the control group followed by the L-NAME group, the SNP group, and the L-ARG group. CONCLUSION: The data show that supplementation of nitric oxide is clearly protective in pancreatic ischemia/reperfusion. However, inhibition of NO synthesis does not lead to an equally clear aggravation of tissue injury.

Acute Disease↗

PubMed2002

[Pancreatic leakage after pancreas resection. An analysis of 345 operated patients].

INTRODUCTION: Complications after pancreatic resections remain frequent despite a decreasing mortality. Pancreatic leakages represent a relevant part of those complications but data on risk factors for their occurrence are rare. We analyzed our experience with incidence, clinical course, and risk factors of pancreatic leakage in a large patient group. METHODS: We analyzed the prospectively documented perioperative data of 345 patients with pancreatic resections carried out between 1994 and 2001. Main indications for surgery were chronic pancreatitis (57%) and malignant tumors (37%). The following operations were performed: Whipple's operation 15%, pylorus-preserving pancreaticoduodenectomy 53%, duodenum-preserving pancreatic head resection 19%, and distal pancreatic resection 13%. Risk factors were analyzed using uni- and multivariate methods. RESULTS: Postoperative mortality and complication rate were 2.9% and 41%, respectively. A pancreatic leakage occurred in 9.9%. In the majority of patients, pancreatic leakage was asymptomatic and controlled by prolonged drainage. However, one fourth of the patients with pancreatic leakage required reoperation. The mortality of pancreatic leakage was 12%. No patient with chronic pancreatitis died as a consequence of pancreatic leakage. Impaired preoperative renal function was the only risk factor for the occurrence of postoperative pancreatic leakage. CONCLUSIONS: Although easily managed in the majority of cases, pancreatic leakage still represents a relevant postoperative complication after pancreatic resection, especially in patients with malignant disease. Because of an increased risk of developing pancreatic leakage, an impaired renal function should be considered specifically in the perioperative management of the patients.

Adolescent↗