Interphase gap decreases electrical stimulation threshold of retinal ganglion cells.

The most common electrical stimulation pulse used in retinal implants is a symmetric biphasic current pulse. Prior electrophysiological studies in peripheral nerve have shown that adding an interphase gap (IPG) between the two phases makes stimulation more efficient. We investigated the effect of IPG duration on retinal ganglion cell (RGC) electrical threshold. We used calcium imaging to measure the activity of RGCs in isolated retina in response to electrical stimulation. By varying IPG duration, we were able to examine the effect of duration on threshold. We further studied this effect by simulating RGC behavior with a Hodgkin-Huxley-type model. Our results indicate that the threshold for electrical activation of RGCs can be reduced by increasing the length of the IPG.

A case of needle ingestion in a female - laparoscopic retrieval.

BACKGROUND: Ingestion of foreign bodies is an old medical problem of decreasing occurrence. Several cases have been reported in the medical literature, and the diagnostic and therapeutic approaches must be applied in a multifaceted and differentiated manner. CASE REPORT: Our case concerns a 54-year-old female with accidental swallowing of a needle. We describe our diagnostic procedure with laparoscopic removal of the appendix due to fixation of the object in the right lower abdomen. DISCUSSION: The ingestion of foreign bodies is an old medical problem, although its incidence has decreased drastically due to changes in lifestyles. Today, it is rather the unusual cases and intentional ingestion that are in the forefront. Initial endoscopic treatment attempts are followed by the "wait-and-see" attitude in hopes of spontaneous passage that can be monitored via radiological methods. If the object does not pass naturally and is localized in the colon, what remains as a treatment option is endoscopy followed by surgery that can be performed in a minimally invasive manner.

DeGarengeot hernia: transabdominal preperitoneal hernia repair and appendectomy.

BACKGROUND: The incarcerated appendix in the femoral hernia represents a rare clinical case that was first described by the Frenchman de Garengeot in 1731. Besides the open procedures, laparoscopy presented itself as a treatment option. CASE REPORT: Our case concerns a 38-year-old patient with a right femoral hernia with an inflamed incarcerated appendix. Because of the clinically inconclusive finding, we chose transperitoneal preperitoneal hernia repair (TAPP) combined with a laparoscopic appendectomy. The intra- and postoperative course was uneventful. This case shows that a laparoscopic procedure is possible even in the case of an incarceration in conjunction with an appendicitis that has not spread to the adjacent peritoneum. DISCUSSION: Compared with open interventions, the subjective social advantages (shorter hospital stay, earlier return to work, less need for pain killers, and others) of laparoscopic hernia treatment have been extensively studied. The use of both methods in the case of an incarcerated hernia is open to dispute, though various small series confirm the feasibility. CONCLUSION: Here, TAPP seems to be the more reliable method in terms of patient safety because of the simultaneous possibility of using laparoscopy.

Indications and results of surgery for incidentally found adrenal tumors.

INTRODUCTION: The accidental discovery of an adrenal mass called incidentaloma has become an increasingly frequent clinical problem with the question of a correct and appropriate therapeutic approach being the subject of controversial discussions. MATERIALS AND METHODS: Clinical charts of 52 patients (22 male, 30 female) who underwent adrenalectomy for an incidentaloma at our institution between 1987 and 2001 were reviewed. RESULTS: Median age was 56.4 years. Reasons for surgery were unclear significance in 22 patients, suspicion of malignancy in 5, increase in size in 8, maximum tumor diameter of more than 5 cm in 7, fear of malignancy in 1, and subclinical secretion of cortisol in 5 patients. No data were available for 4 patients. Surgical resection was performed using a conventional transabdominal approach in 28 patients, a conventional dorsal approach in 17 patients, and an endoscopic retroperitoneal approach in 7 patients. Histopathologic examination ruled out adrenal adenoma in 32 patients, adrenal myelolipoma in 12, unilateral nodular hyperplasia in 4, cystic lesion in 3, and adrenocortical carcinoma in 1 patient. The mean size of all lesions was 5.5 cm. Evaluating the criteria for surgical treatment regarding age of the patients and size of the lesions, 25 patients (48%), including the patient with the adrenocortical carcinoma, were younger than 60 years and had an adrenal lesion exceeding 4 cm in size. During postoperative follow-up that was available for 39 patients, 3 developed contralateral tumors that were treated by resection in 1 and by close follow-up in 2. CONCLUSIONS: Size should not be the sole criterion; treatment should be tailored to the individual patient. Especially in patients younger than 60 years with an adrenal lesion exceeding 4 cm in size, an adrenalectomy, predominantly via an endoscopic approach, should be carried out, because a repeated and life-long close follow-up of an anxious patient who has been informed of the diagnosis will in some cases exceed the cost of a single endoscopic operation.

Is pancreatic resection justified for metastasis of papillary thyroid cancer?

BACKGROUND: This case report describes a patient with symptomatic anaemia due to a bleeding duodenal metastasis from metastasising differentiated thyroid cancer (DTC), which was treated by partial duodenopancreatectomy (DP). CASE REPORT: A 71-year old male was sent to hospital with severe anaemia. This patient had suffered multiple cervical recurrences of differentiated papillary thyroid cancer, which had been treated by several resections and irradiation, and an adrenal gland metastasis, via adrenalectomy. Abdominal computed tomography showed an enlarged pancreatic head, an upper gastrointestinal endoscopy revealed a bleeding ulcer in the duodenum, and a biopsy revealed metastasis from DTC. Due to the symptomatic metastasis, a partial DP was performed; the postoperative course was uneventful. Histopathological examination revealed metastasis of the DTC next to the papilla lying in the head of the pancreas, with growth into the muscularis propria of the duodenum. The patient survived for another 41/2 years before dying from progressive metastatic disease elsewhere. CONCLUSION: DP for metastatic disease should be considered in selected patients for alleviation of the symptoms and prolongation of survival, as long as this operation is performed by experienced surgeons who can achieve minimal morbidity and mortality.

[Early results of proximal interphalangeal joint replacement with pyrolytic carbon prosthesis (Ascension) in idiopathic and post-traumatic arthritis]. / Frühe Ergebnisse der Fingermittelgelenkendoprothetik mit der Pyrocarbonprothese (Ascension) bei idiopathischen und posttraumatischen Arthrosen.

Surgical treatment of painful idiopathic and post-traumatic arthritis with joint replacement of the proximal interphalangeal joint has become increasingly important. Due to shortcomings of former constrained and partially constrained prostheses with regard to abrasion and durability we have been using an unconstrained prosthesis since April 2002. This model is an almost abrasion free, biocompatible 2-component prosthesis. The surface is shaped like the condyles and the position is secured in a press-fit technique. During October 2004 we reviewed the results of 20 out of 29 patients with idiopathic or post-traumatic arthritis who had been treated with a pyrolytic carbon proximal interphalangeal joint prosthesis from April 2002 to April 2004 retrospectively. Clinical, subjective and radiological parameters were studied. On follow-up after 0.5 to 2.5 years the patients were satisfied with the pain relief. The range of motion varied. However, with an average ROM of 50 degree it was equivalent to the results in literature. Signs of periprosthetic cysts, osteophytes and loosening of the proximal as well as of the distal component could be seen in the radiograms of some patients. There was no correlation between these radiological observations and range of motion, pain or grip strength. In three cases the joint prosthesis had to be converted to an arthrodesis of the proximal interphalangeal joint. Bearing in mind the correct indications (intact collateral ligaments, stable bone stock and sufficient extensor and flexor tendons), pyrocarbon prosthesis are a treatment option for idiopathic and posttraumatic arthritis preserving motion and reducing pain. Radiological results seem to indicate an absence of osteointegration and tension forces at the prosthesis/bone interface. Further investigation will be necessary to improve surface and design to increase radiological results in long-term follow-up. Additional surveys are required to improve indications, surgical approach and intraoperative control of correct component positioning.

[Resistance to pressure of bronchial closures. Comparison of pressure resistance of manual and stapler bronchial closures depending on the angle to the cartilaginous rings]. / Druckresistenz einer Bronchusnaht. Vergleich der linearen Klammennaht vs. Handnaht in Abhängigkeit vom Absetzungswinkel zum Knorpelring.

BACKGROUND: This study was aimed to determine the resistance to pressure of manual and stapled bronchial closures under ideal conditions (90 degrees to the bronchial tree) and parallel to the trachea (45 degrees). MATERIAL AND METHODS: An experimental study was done on 60 explanted pig tracheae which were alternatively closed with either double-layer, running sutures angled 90 degrees to the cartilaginous rings or an automatic stapling device. The closure line was placed exactly 90 degrees to the bronchial tree in 30 cases and parallel to the trachea (45 degrees) in 30. The sutures were placed under pressure until air leakage was observed. The leakage pressure was digitally recorded. RESULTS: A statistically significant difference existed between the two groups. Mechanical sutures proved more resistant to pressure (P=0.011). CONCLUSIONS: Under ideal conditions, the resistance to pressure of mechanical sutures is equal to if not better than that of manual sutures.

Experience with the surgical treatment of adrenal cortical carcinoma.

UNLABELLED: We report on a series of 20 consecutive patients (10 males, 10 females) with adrenal cortical carcinoma (ACC) who were treated by surgery between 1987 and 2001. AIM: The aim of this study was to evaluate the outcome and the role of surgery in the management of this tumour. RESULT: One patient was at stage I, five patients at stage II, five patients at stage III and nine patients at stage IV of disease. Ten patients suffered from a functioning tumour, whilst ten patients revealed non-functioning tumours. In all patients a transabdominal approach was performed for the complete resection of the tumour, adjacent organs or metastases. The medium survival after surgical resection, calculated by the Kaplan-Meier method, was 45 months for the overall group, 65 months for patients at stage I or II, 38 months for patients at stage III and 19 months for patients at stage IV of disease. The 5-year survival rate for all patients was 23%, for patients at stage I or II 33%, for patients at stage III 20%, and for patients at stage IV around zero. CONCLUSION: Radical surgery with a complete resection of the tumour, adjacent organs, solitary metastases and loco-regional recurrence wherever possible improves survival, even at advanced stages of disease.

Secretion of free and protein-bound leptin from subcutaneous adipose tissue of lean and obese women.

Leptin circulates as a free (FL) and a protein-bound (BL) form, with the soluble leptin receptor (LR) as an important binding compound. Here we measured these components of leptin in serum and in the incubation medium of sc adipose tissue in healthy lean (n = 10) and obese (n = 13) female subjects using recently developed specific RIA systems. In addition, immunostaining for FL, BL, and LR in adipose tissue was performed. Serum FL levels were increased in the obese subjects (P < 0.0001), whereas BL and LR concentrations in serum of lean and obese subjects were similar. Both FL and BL were secreted from human preadipocytes and increased in parallel to the differentiation of the cells. In sc fat cell explants LR antibodies predominantly stained the fat cell membrane, whereas FL and BL antibodies revealed intracytoplasmatic adipocyte staining. The release of FL, BL, and LR from adipose tissue was increased in obese compared with lean subjects (P < 0.005 for FL; P < 0.02 for BL, and P < 0.01 for LR). In summary, fat cells are capable of releasing not only FL, but also BL and LR.

[Spontaneous bleeding of focal nodular hyperplasia as a rare cause of acute abdomen]. / Eine spontan blutende focal noduläre Hyperplasie als seltene Ursache eines akuten Abdomens.

Focal nodular hyperplasia (FNH) is a benign tumor of the liver. It is most frequently found in women of reproductive age. An association with oral contraceptives and sexual hormones is therefore possible. FNH lesions are frequently discovered incidentally. Spontaneous complications are rare. When the diagnosis is known with reasonable accuracy, a nonoperative approach is in common use. We report here the rare case of spontaneous intraabdominal bleeding from FNH.

Breaking strength of native and sutured trachea. An experimental study on sheep trachea.

Tracheal anastomoses are, even more so than other sutures, often only possible to prepare under tension and thus in danger of breakage. No information is available regarding native tracheae and freshly sutured tracheae. For this reason, our objective was to examine the tensile strength of native tracheae and compare it with freshly sutured specimens. Fresh tracheae were collected from the local slaughterhouse within 30 min of slaughter. With the help of a suitable holding device, 24 fresh tracheae were mounted on a material testing machine and stretched to breaking point, during which the force and distance required were recorded. The same study was carried out on each 10 freshly anastomosed tracheae using three different suturing techniques. The mean value of the maximum force required for native tracheae was 198 N. With continuous suturing (polypropylene), a mean value of 171 N was attained, and with single interrupted suturing (polydioxanone and polyglactin 910), 123 N, respectively, 108 N. Differences between the groups proved to be highly significant. With respect to the mechanical strain from traction, the continuous suture proved to be statistically identical to native tracheae, whereas single interrupted sutures revealed a considerably lower stability under burden. Therefore, the continuous suture is of advantage in respect of the mechanical strain from traction and the suture protection of tracheal anastomoses. Further studies with differing survival times in vivo with this method provide insight into the stability of tracheal anastomoses during the healing process.

Adverse gastrointestinal effects of mycophenolate mofetil: aetiology, incidence and management.

Mycophenolate mofetil (MMF) is a relatively new immunosuppressive drug. It inhibits inosine monophosphate dehydrogenase, a key enzyme in the de novo pathway of purine synthesis, and thus causes lymphocyte-selective immunosuppression. Large clinical trials have revealed the efficacy of MMF in the prevention of allograft rejection when administered together with cyclosporin or tacrolimus and corticosteroids. Although the adverse effect profile of MMF is comparatively benign, gastrointestinal adverse effects are a major concern. These effects are partially explained by the increased immune suppression, by the mode of action and by interactions, particularly with other immunosuppressants. The aetiology of the rarest gastrointestinal adverse effects is still not completely clear. Therapy depends upon the clinical gravity of the adverse effects and is therefore a case of waiting and ob- serving. An adjustment of dosage of immunosuppressants according to the clinical situation and, particularly in the case of MMF, spreading the total dosage over more than 2 daily doses are often sufficient. Should adverse effects persist for a longer period of time and be of a more serious nature, a comprehensive invasive diagnostic process is necessary, including endoscopy and biopsy and the search for opportunistic infections. In this case, dosage reduction or the complete withdrawal of MMF seems to be unavoidable. Severe gastrointestinal complications with MMF are rare, but when they do occur they may require extensive diagnosis and treatment. In the future, therapeutic drug monitoring and, where necessary, pharmacological modifications of MMF could lead to a further reduction of adverse effects with an equal or even increased efficacy.

Tracheal reconstruction under tension: an experimental study in sheep.

AIMS: Invasion of the trachea by thyroid cancer is a difficult problem. Circumferential resection and end-to-end reconstruction is the treatment of choice. The objective of our study was to investigate the effect of tension on tracheal healing and stenosis formation, and to ascertain the maximum tolerable tension. METHODS: Tracheal resections of 3, 6 and 9 cm with end-to-end anastomosis were performed on 25 sheep. The intraoperative force required for approximation of the tracheal stumps was measured. Luminal stenosis was determined with the aid of computerized planimetry 1, 2, 4, 8 and 24 weeks post-operatively. RESULTS: A gradual increase of the stenosis rate occurred with increasing tension on the anastomosis. Acceptable results were achieved in the majority of cases without release techniques or tension suture. CONCLUSIONS: Tracheal anastomosis under tension does not always lead to disruption or separation of the anastomosis. With the additional use of release manoeuvres and tension sutures, tracheal anastomosis under tension are possible without severe stenosis. The additional use of temporary stenting needs to be elucidated.

Influence of suture material and technique on end-to-end reconstruction in tracheal surgery: an experimental study in sheep.

Resection and end-to-end anastomosis of the trachea represent the preferred treatment for various benign and malignant diseases involving the trachea. Various studies have reported conflicting results with alternative techniques and suture materials for tracheal anastomosis. Our objective was to evaluate three frequently used techniques concerning stenosis rate and histological reaction in a large-animal species. Tracheal resection of 3 cm and end-to-end anastomosis were performed in 15 sheep with the use of three different techniques. In the first group, an interrupted suture with polyglactin, in the second group an interrupted suture with polydioxanone, and in the last group a continuous suture with polypropylene were used. The animals were killed 1, 2, 4, 8, and 24 weeks postoperatively. The luminal stenosis was determined by means of computerized planimetry. All three techniques appeared to be appropriate for tracheal anastomosis. The luminal stenosis developed within the first 8 weeks after surgery. A cross-sectional area of approximately 40-70% was finally achieved. Differences dependent on the suture material are less important than the technical details of the operation.

Mycophenolate mofetil: suggested guidelines for use in kidney transplantation.

Mycophenolate mofetil (MMF) is an immunosuppressive drug designed to inhibit inosine monophosphate dehydrogenase (IMPDH). IMPDH is a key enzyme in the de novo purine synthesis of lymphocytes. It is crucially important for proliferative responses of human T and B lymphocytes. The inhibition of IMPDH thus leads to selective lymphocyte suppression. After successful use in various in vitro and animal models, MMF was brought to clinical trial in patients undergoing transplantation. The drug is rapidly and completely absorbed following oral administration. Pilot studies of administration with cyclosporin and corticosteroids suggested a significant reduction in the incidence of organ rejection at dosages of 1 to 3 g/day. As a result of these studies, 3 pivotal randomised double-blind multicentre trials, involving nearly 1500 patients, were designed to investigate the effects of addition of MMF to different standard immunosuppressive protocols on the prevention of acute renal allograft rejection. After 6 months, the rates of biopsy-proven rejection were significantly reduced in patients receiving MMF. In combination with cyclosporin and corticosteroids, the adverse effect profile resembled that of azathioprine. Most adverse effects were associated with the gastrointestinal tract, the blood system and opportunistic infections. MMF offers improved immunosuppressive therapy following renal and probably other solid organ transplantation. MMF has been licensed since 1995 for the prevention of acute renal allograft rejection in most countries. It has been used in different combinations of immunosuppressive drugs and in various dosages and regimens.

Immune-adhesion molecules in the prevention of allograft rejection and reperfusion injury.

Control of the immune system is of indispensable importance for graft acceptance and function. Immunological changes in the graft before and after organ harvesting, the transplantation procedure itself and the organ recipients clinical state contribute to the immune response. Leukocyte trafficking [1] into a graft is regulated by various signal transducing molecules, which have been characterised during the past years. Ligand molecules on endothelial cells and in the organ parenchyma are the counterparts for leukocyte adhesion and tissue infiltration. The expression of these ligand molecules is regulated by soluble factors and cell-cell interactions [2]. The regulation of tissue inflammation and repair mechanisms involving components of the immune system therefore depends on a number of cell-surface interactions. The processes of intravascular adhesion, transmigration and infiltration by leukocytes and platelets are mainly mediated by receptor ligand interactions with target cells (cell-cell) and extracellular matrix proteins (cell-matrix). The main molecular families of adhesion receptor/ligand molecules have been identified. Today, we are still far from understanding this network of interactions. The numbers of molecules and factors involved are still increasing. This review summarises the currently available knowledge on the intervention in this system by monoclonal antibodies (mAbs), peptides and blocking agents. From this review, it is evident that further investigations are justified.

[Development of obstructive jaundice after hemorrhage into a benign, non-parasitic liver cyst]. / Entwicklung eines obstruktiven Ikterus nach Einblutung in eine benigne, nicht-parasitäre Lebercyste.

Benign, non-parasitic liver cysts are usually asymptomatic and found incidentally by abdominal ultrasound or CT scan. We present the case of a 68-year-old patient who showed obstructive jaundice due to a hemorrhagic liver cyst compressing the choledochal duct. Due to the location of the cyst in the porta hepatis with partial compression of central liver vessels and the meanwhile organized hematoma, operative therapy was preferred in order to prevent secondary complications such as portal vein thrombosis and to exclude a malignant neoplasm.

Transplantation of H-2Kb-transgenic adrenocortical cells in the mouse having undergone an adrenalectomy: functional and morphological aspects.

BACKGROUND: A new model of cellular adrenocortical transplantation after bilateral adrenalectomy in the mouse was established. This model was used to study the effects of the expression of the transgenic MHC class I molecule H-2K(b) (Kb) on graft survival and morphologic features, corticosterone secretion, and the possibility of tolerance induction in the recipient. METHOD: A single cell suspension of purified adrenocortical cells was grafted under the kidney capsule of B10.Br (H-2k) mice having adrenalectomies. Syngeneic, fully MHC-mismatched, and MHC class I-incompatible Kb-transgenic mice served as donor strains. To analyze graft function, urinary excretion and serum levels of corticosterone were monitored over 100 days. Tolerance induction in the graft recipients of Kb-transgenic and third party skin grafts was tested on day 50 after adrenocortical transplantation. Histological sections of the adrenocortical grafts were obtained on day 100. RESULTS: Recipients of syngeneic and Kb-transgenic grafts displayed pretransplant corticosterone levels on days 20, 50, and 100 and ACTH-stimulated serum corticosterone levels similar to those of controls on day 100 after adrenocortical transplantation. In contrast, in recipients of fully MHC-mismatched grafts, corticosterone excretion was significantly reduced. In this group, 4 of 7 mice did not survive. Syngeneic skin grafts survived indefinitely in recipients of syngeneic and Kb-transgenic adrenocortical grafts, whereas Kb-transgenic and fully MHC-mismatched skin grafts were acutely rejected. Tissue sections of the adrenocortical grafts revealed vascularized cell conglomerates in syngeneic and Kb-transgenic grafts without infiltrations of mononuclear cells. Furthermore, a differentiation similar to adrenocortical organization was partly found. CONCLUSION: In conclusion, a model of cellular adrenocortical transplantation was established. The results show that syngeneic transplantation resulted in physiological corticosterone levels early after transplantation, whereas fully MHC-incompatible grafts were rejected. Recipients of Kb-transgenic grafts showed unimpaired adrenocortical function, but did not tolerize toward Kb-transgenic skin grafts. Possible mechanisms include a local immunomodulatory effect of glucocorticoids secreted by the graft and a low immunogenicity of the relatively small numbers of transplanted cells.

Invasive differentiated thyroid carcinoma: tracheal resection and reconstruction procedures in the hands of the endocrine surgeon.

BACKGROUND: Although differentiated carcinoma of the thyroid gland is a relatively benign tumor, up to 20% of patients are endangered by potentially fatal complications resulting from infiltrating tumor growth into the upper aerodigestive tract. METHODS: This study included 33 patients who underwent 34 tracheal or laryngotracheal procedures for invasive differentiated thyroid carcinoma under the direction of a single surgeon (G.F.W.S.). From 1990 to 1994, radical tumor extirpation was performed by "window" resection, and from 1995 to 1998, radical surgery consisted of either circumferential sleeve resection or laryngotracheal "step" resection--a novel method of reconstruction in cases of unilateral tumor infiltration into the larynx and trachea. Resection was limited to laminar ablation in 17 cases. The mean follow-up of 16 patients who survived was 42.5 months (range, 2 months to 8.9 years). RESULTS: Procedures resulting in primary end-to-end anastomosis of the upper airways were associated with lower perioperative morbidity and improved recurrence-free survival when compared with "window" resections with muscle flap reconstruction. In cases of superficial tracheal tumor infiltration, laminar ablations were sufficient for local tumor control. CONCLUSIONS: Radical eradication of differentiated thyroid carcinoma infiltrating the upper airways followed by radioiodine application should be considered the treatment of choice. Laryngotracheal "step" resection allows tumor extirpation with preservation of neural and muscular structures of the larynx.

Subacute liver failure induced by phenprocoumon treatment.

We report on a 39-year-old woman suffering from deep venous thrombosis due to a heterozygous factor-V-Leiden mutation with resistance to activated protein C. Four months after beginning oral anticoagulation, generalized jaundice appeared. Subsequently, subacute liver failure developed necessitating an orthotopic liver transplantation. Histopathology showed features of extensive liver cell necrosis without evidence of a substantial inflammatory infiltrate. Based on histopathology and exclusion of other liver diseases, phenprocoumon-induced liver failure was diagnosed. Five months after transplantation the patient is well with normal liver function tests. Because of the widespread use of oral anticoagulants, not only bleeding complications but also hepatotoxicity should be considered in therapy supervision.