Asymmetry in search.

Most of the work on search in artificial intelligence (AI) deals with one search direction only-mostly forward search-although it is known that a structural asymmetry of the search graph causes differences in the efficiency of searching in the forward or the backward direction, respectively. In the case of symmetrical graph structure, however, current theory would not predict such differences in efficiency. In several classes of job sequencing problems, we observed a phenomenon of asymmetry in search that relates to the distribution of the are costs in the search graph. This phenomenon can be utilized for improving the search efficiency by a new algorithm that automatically selects the search direction. We demonstrate fur a class of job sequencing problems that, through the utilization of this phenomenon, much more difficult problems can be solved-according to our best knowledge-than by the best published approach, and on the same problems, the running time is much reduced. As a consequence, we propose to check given problems for asymmetrical distribution of are costs that may cause asymmetry in search.

Immunoarchitecture and specific functions of splenic autotransplants at different implantation sites.

The present study deals with the morphological and functional development of intraomentally and subcutaneously implanted splenic tissue. Spleens and splenic transplants from 138 Lewis rats were investigated with immunohistological, immunological and molecular biological methods at different times after operation (up to 200 days postoperatively). The analysis of the development revealed a nonsignificant reduction concerning the weight of subcutaneous replants and a nonsignificant decrease of the weight of female transplants of both groups at different phases after operation. The cell composition of cell suspensions from spleen and both transplant types showed a deficiency of T, B, MHC-I+ cells and a certain macrophage subset (ED-3+ cells) in transplants. In a quantitative immunohistological analysis of compartments (red pulp, periarteriolar lymphoid sheaths, marginal zone and follicles) the T cell reduction was related to the Tsupp/cyt cells and T cell receptor bearing cells in the periarteriolar lymphoid sheaths, whereas the density of T helper cells was normal. In addition, a different homing of kappa-light chain positive and leukocyte common antigen (B cell type)-positive B cells in follicles and marginal zone was detected. The amount of two macrophage subsets (ED-1+ and ED-2+ cells) was increased in the red pulp. Only minor differences in the immunoarchitecture of transplants at different implantation sites were measured. A functional analysis of spleen compared to both transplant groups elicited a B cell defect after LPS stimulation in subcutaneous transplants and a reduced allogeneic response of both transplant types but a normal proliferation of T cells after ConA stimulation and a correct IgM antibody response against sheep red blood cells. The in vivo mRNA expression and the expression kinetics of interferon-gamma and granulocyte-macrophage colony-stimulating factor after antigen stimulation differed in both transplant groups with a remarkable permanent expression of both mediators in subcutaneous transplants. It can be summarized that the results clearly indicate a development of spleen-like immunoarchitecture of intraomental replants with subtle cellular, functional and molecular alterations. In contrast, despite a comparable development, some severe functional defects occurred in subcutaneous implants pointing out the important role of interactions between the regenerating splenic tissue and the target tissue on a functional and molecular level.

[Laparoastoma (open packing) in the treatment concept of infected pancreatic necroses]. / Das Laparoastoma (Open Packing) im Behandlungskonzept infizierter Pankreasnekrosen.

Out of 284 patients with acute pancreatitis 73 (26%) had pancreas necrosis. Of these 73 cases 43 patients with infected pancreas necrosis were treated surgically, whereas conservative treatment proved successful in the remaining 30 cases with so-called sterile necrosis. Our interdisciplinary treatment combined delayed surgery for the better demarcation of the necrotic tissue, with extended intensive care therapy and epigastral laparostomy; through this laparostomy surgical revision with necrosectomy and peritoneal lavage was performed daily for 15 (+/- 6) days, necessitating long-term artificial respiration for an average of 15 (4/168) days. The mortality rate in the 43 patients with infected pancreas necrosis amounted to 16.2% (n = 7); none of the patients with sterile necrosis died. In cases of multiple organ failure the mortality rate was significantly higher (30%) than with failure of only one organ system (4.3%). The mortality rate in all cases with pancreas necrosis (n = 73) amounted therefore to 9.5%. Serious complications of laparostomy occurred in 28% (n = 12) of the 43 patients, whereby 8 of these cases were gastrointestinal fistulae, with a fatal outcome in one patient. The overall mortality rate in the total group of 284 patients with acute pancreatitis was 2.8%.

[A combined endoscopic surgical treatment concept in acute biliary pancreatitis]. / Kombiniertes, endoskopisch-chirurgisches Behandlungskonzept bei akuter, biliärer Pankreatitis.

This paper presents the results of a combined endoscopic-surgical approach with management of acute biliary pancreatitis in 91 patients. The diagnosis was always made by means of endoscopic-retrograde cholangiography. Papillary or bile duct stones, or unmistakable signs of previous stone passage, and in exceptional cases flow obstruction due to preiampullary diverticuli were considered criteria for a positive diagnosis. All 91 patients were subjected to endoscopic sphincterotomy with/without stone extraction subsequent to the diagnostic cholangiogram. Endoscopic intervention was performed as soon as possible after admission to hospital, but by 48 hours at the latest. Cholecystectomy was carried out in all patients who were free of risk factors and without previous cholecystectomy, during the disease-free interval. The complication rate of this combined endoscopic-surgical approach amounted to 10.9%; the mortality rate was 3.3%. The achieved results suggest that endoscopic sphincterotomy with stone extraction in the acute phase of biliary pancreatitis is the method of choice in order to interrupt the process of this disease. In combination with the final surgical treatment of gallstone disease by cholecystectomy to avoid recurrences, the prognosis of acute biliary pancreatitis can be significantly improved by using this combined endoscopic-surgical management.

[Extracorporeal shock wave treatment of calcium containing gallbladder calculi]. / Die extrakorporale Stosswellenbehandlung von kalkhältigen Gallenblasensteinen.

A total of 50 patients--37 female and 13 male--with an average age of 50 +/- 27 years (23-86 years), suffering from rim-calcified gallbladder stones, underwent extracorporeal shock-wave lithotripsy (ESWL), using an ultrasound-guided overhead module of Lithostar Plus (Siemens Company). The total number of stones was 87, with an average diameter of 16 +/- 7 (7-38) mm. 29 patients had a solitary stone, 13 had two and 8 patients three or more stones. All patients received adjunct medication of 10 mg/kg body weight chenodeoxycholic and ursodeoxycholic acid 14 days prior to ESWL as a single bedtime dose. An average number of 5,300 +/- 2,200 shock waves (1,200-15,000) was applied for stone disintegration. The corresponding energy amounted to 750 bar. 29 patients needed one, 21 two or more treatments. After ESWL a variety of clinical abnormalities was observed: flank pain (15%), transient microhaematuria (33%) and transient macrohaematuria (2%). Subsequent to ESWL 5 patients suffered from complications such as biliary obstruction 3 weeks to 9 months after treatment and had to undergo ERCP. Three times endoscopic papillotomy was performed to remove stones from the common bile duct. Up to now 4 patients have undergone cholecystectomy: acute cholecystitis (n = 3), recurrent colicky pain (n = 1). 20 patients have been followed up over a 12-month period; 12 of them are completely free of stones and fragments.

[Reconstruction-plasty of iatrogenic choledochal stenoses using human pericardium. An experimental study in the domestic pig]. / Erweiterungsplastik von iatrogenen Choledochusstenosen mit Humanperikard. Experimentelle Studie am Hausschwein.

The effect of human pericardial patch plastic for reconstruction of iatrogenic common bile duct stenosis was investigated in experiments performed in pigs. All patches (n = 8) were overgrown with immature biliary epithelium detectable on light and electron microscopy within 6 weeks. No restenosis nor any fistula developed during this observation period. Liver function tests, especially bilirubin, were not suitable parameters for the detection of biliary obstruction (preoperative value 0.38 +/- 0.09 mg/dl; 1 week after subtotal stenosis 3.36 +/- 1.53 mg/dl; 2 weeks after subtotal stenosis 1.49 +/- 0.62 mg/dl; 3 weeks after subtotal stenosis 0.50 +/- 0.27 mg/dl; 6 weeks after pericardial patch plastic 0.33 +/- 0.05 mg/dl, mean +/- SD. Ultrasonographic measurement of the common bile duct diameter was the diagnostic method of choice. Preoperative dimension 4.5 +/- 0.5 mm; 1 week after subtotal stenosis 8.5 +/- 2.0 mm; 2 weeks after subtotal stenosis 10.5 +/- 1.8 mm; 3 weeks after subtotal stenosis 14.0 +/- 3.6 mm; 6 weeks after pericardial patch plastic 9.0 +/- 1.6 mm, mean +/- SD.

[Autotransplantation of the spleen in rats: development, function and cytokine expression in intra-omental and subcutaneous regeneration]. / Autotransplantation der Milz an Ratten: Entwicklung, Funktion und Cytokin-Expression in intraomentalen und subkutanen Regeneraten.

The implantation of splenic tissue at different implantation sites (intraomental and subcutaneous) into one animal (Lewis rats) results in the development of splenic nodules at both sites. In a quantitative immunohistological analysis of splenic compartments such as red pulp (RP), periarteriolar lymphoid sheaths (PALS), marginal zone (MZ) and follicles (F) the T-cell reduction was related to the T(helper) cells in the MZ and T(supp/cyt) cells in the PALS. In contrast, the cell density of B cells and ED-1+ macrophages in the PALS and T(supp/cyt) cells in the MZ was increased. Significant differences between the implantation sites were restricted to CD5+ cells (thymocytes and T cells) in the MZ and OX-33+ cells (B cells with LCAB antigen) in the PALS. The reorganisation of the compartments of subcutaneous implants showed a delay of one week as compared with omental ones. Functional assays like haemolytic plaque assay, mitogen stimulation and mixed lymphocyte assay elicited an analogous delay of the functional maturation of IgM-positive B cells, a reduced proliferation of both transplant groups after pokeweed mitogen (PWM) stimulation, a decreased response after lipopolysaccharide (LPS) stimulation in solely subcutaneous replants and no differences concerning the mitogens concanavalin A (ConA) and phytohaemagglutinin (PHA). Both transplant groups showed a significantly reduced allogeneic response. The results of the functional analysis and the abnormal mRNA expression of Il-5, Il-6 (Interleukin 5 and 6), GMCSF (Granulocyte-Macrophage-Colony-Stimulation-Factor) and IFN-gamma (Interferon gamma) in subcutaneous replants indicate subtle molecular alterations (independent of a spleen-like immunoarchitecture) at this site.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunocytochemical localization of estrogen and progesterone receptors in human thyroid.

The presence of steroid hormone receptors has previously been suggested in thyroid tissue by biochemical means. Our studies were designed to confirm these results and to localize the specific receptor-containing cell type using a novel immunocytochemical method. Monoclonal antibodies specific to estrogen receptors (ER) and progesterone receptors (PgR) were used to localize these steroid hormone receptors in the human thyroid gland. Frozen tissue sections from surgical specimens excised from 22 patients of both sexes with benign thyroid disease were studied. The sections were incubated with rat antiestrophilin and antiprogesterone receptor antibodies and were then exposed to rabbit anti-rat IgG and to rat peroxidase-antiperoxidase complex. The reaction product was visualized with diaminobenzidine tetrahydrochloride and hydrogen peroxide. Four specimens were positive for both ER and PgR, 16 were ER-positive and PgR-negative, and two were negative for both ER and PgR. Positive reactivity was limited to the follicular lining cell nuclei and varied from focal to diffuse. The immunohistochemical findings confirmed the presence of ER and PgR in the thyroid tissue and demonstrated for the first time that these receptors are present only in the nuclei of the lining cells of the thyroid follicle. The role of steroid hormone receptors in the thyroid in health and disease remains to be explained.

Incidence of septic and thromboembolic-related deaths after splenectomy in adults.

In a review of 37,012 autopsies over the last 20 years 202 deceased adults who had had a splenectomy were investigated. The incidence of infections and thromboembolic complications related to death in these patients was compared with that of a matched deceased population (n = 403) who had not undergone splenectomy. Death-related pneumonia was diagnosed frequently in the splenectomy group and to a lesser extent in the control group (57.9 versus 24.1 per cent, P less than 0.001). Lethal sepsis with multiple organ failure occurred in 6.9 per cent of the splenectomy group and in 1.5 per cent of the controls (P less than 0.001). Purulent pyelonephritis was observed in 7.9 per cent of the splenectomy group and was significantly more frequent than in the control group with its rate of 2.2 per cent (P less than 0.001). Finally, pulmonary embolism was the major or a contributory cause of death more often in the splenectomy group than in the control group (35.6 versus 9.7 per cent, P less than 0.001). We conclude that splenectomy generates a considerable life-long risk of severe infection and of thromboembolism.