The Kohonen network incorporating explicit statistics and its application to the travelling salesman problem

In this paper we introduce a new self-organizing neural network, the Kohonen Network Incorporating Explicit Statistics (KNIES) that is based on Kohonen's Self-Organizing Map (SOM). The primary difference between the SOM and the KNIES is the fact that every iteration in the training phase includes two distinct modules-the attracting module and the dispersing module. As a result of the newly introduced dispersing module the neurons maintain the overall statistical properties of the data points. Thus, although in SOM the neurons individually find their places both statistically and topologically, in KNIES they collectively maintain their mean to be the mean of the data points, which they represent. Although the scheme as it is currently implemented maintains the mean as its invariant, the scheme can easily be generalized to maintain higher order central moments as invariants. The new scheme has been used to solve the Euclidean Travelling Salesman Problem (TSP). Experimental results for problems taken from TSPLIB [Reinelt, G. (1991). TSPLIB-A travelling salesman problem library. ORSA Journal on Computing, 3, pp. 376-384] indicate that it is a very accurate NN strategy for the TSP-probably the most accurate neural solutions available in the literature.

Direct trocar insertion versus Veress needle insertion in laparoscopic cholecystectomy

BACKGROUND

Direct insertion of the trocar is an alternative method to Veress needle insertion for the creation of pneumoperitoneum. The safety of direct disposable shielded trocar insertion for the creation of pneumoperitoneum was assessed by comparing with Veress needle insertion during laparoscopic cholecystectomy (LC).

METHODS

One thousand five hundred patients undergoing LC with pneumoperitoneum were included in this study. In 470 patients the Veress needle insertion technique was used, and in 1,030 patients direct trocar insertion technique was used. Patients having indications for open trocar insertion were excluded from the study.

RESULTS

Complication rate was significantly higher in the Veress needle group (14% versus 0.9%; P <0.01), and the two major complications, gastric perforation and iliac artery laceration, were also encountered in this group.

CONCLUSIONS

Our results suggest that with a lower complication rate, direct insertion of the disposable trocar is a safe alternative to Veress needle insertion technique for the creation of pneumoperitoneum. Such an approach has further advantages such as less cost/instrumentation and rapid creation of pneumoperitoneum.

Successful medical treatment of an epithelioid hemangioendothelioma of liver

Hepatic epithelioid hemangioendothelioma (HEH) is a rare vascular tumor of the liver of unknown etiology. Although HEH is usually characterized by a low grade malignancy and a good long-term prognosis, its growth can be progressive and lead to hepatic failure, extrahepatic metastasis and death. Several different antineoplastic agents have been proposed for cases of nonresectable HEH. We report the case of a 45-year-old man with HEH successfully treated with intravenous infusion of Adriamycin.

Comparison of long-term quality of life after laparoscopic and open cholecystectomy

BACKGROUND

Although many studies have compared open and laparoscopic procedures, showing many advantages in favor of the laparoscopic technique during the early postoperative period, only a limited number of reports in the literature compare the two techniques during the later follow-up period with regard to quality of life. This study aimed to compare the effects of these two cholecystectomy techniques on the quality of life and clinical outcome of the patients during long-term follow-up evaluation.

METHODS

This study evaluated 200 patients who underwent cholecystectomy operations with either technique between 1993 and 1999 in our department. There were 100 patients in each group. Both groups were similar with respect to age, gender, body mass indexes, American Society of Anesthesiology (ASA) scores, and indications for surgery. The Medical Outcome Study Short Form 36 Health survey (SF-36), which includes 36 items, was used for evaluating the quality-of-life index. In addition to this, a system-specific instrument for gastrointestinal diseases was used to investigate clinical outcome.

RESULTS

The mean administration time for the questionnaire was 46.8 +/- 18.7 months in the laparoscopic cholecystectomy (LC) group and 41.5 +/- 16 months in the open cholecystectomy (OC) group. Statistically significant differences were noted in the scores for all eight SF = 36 health status domains in favor of laparospopic surgery. No statistically significant difference was found for abdominal pain, location of the pain, referral to a doctor for the pain, accompanying symptoms, relieving factors for the pain, distention, and dyspeptic complaints, usage of antacid therapy, weight changes, changes in bowel habit, need for a special diet, or sexual functions between the two groups.

CONCLUSIONS

The gastrointestinal clinical symptoms were similar in the two groups during the long-term follow-up evaluation, but laparoscopic cholecystectomy was found to be significantly superior to the open technique with respect to the quality of life over the long term.

A prospective, randomized protocol to examine the efficacy of postinternal urethrotomy dilations for recurrent bulbomembranous urethral strictures

OBJECTIVES

The high recurrence rate is still the major complication of endoscopic treatment of urethral stricture disease. To compare the outcome of patients who underwent direct vision internal urethrotomy (DVIU) and then followed a protocol that randomized them to either our urethral dilation protocol or consecutive DVIUs for the treatment of their urethral stricture.

METHODS

A total of 37 patients, who had undergone at least two DVIUs to treat their recurrent urethral strictures, were enrolled in this study. They were randomized into two groups. The etiology and location of the strictures were similar, and their length ranged from 0.5 to 2 cm in each group. In group 1 (n = 18), the patients were observed by regular visits and uroflowmetry profiles after the initial DVIU and consecutive DVIUs were considered when the stricture recurred. In group 2 (n = 19), patients received urethral dilations with Benique dilatators (maximal 21F) under intraurethral anesthesia, beginning 10 days after the initial internal urethrotomy, according to the following protocol: weekly for the first month, once after 3 and after 6 months, and then once each year.

RESULTS

After a median follow-up of 30 months, the urethral stricture recurred within 12 months in 55.6% (n = 10) of group 1, and consecutive DVIUs were indicated. During the same follow-up period, recurrence was observed in 2 patients (10.5%), 9 months and 2 years after randomization, in group 2 (P <0.05). The mean maximal urinary flow rate in groups 1 and 2 at last follow-up was 7.8 +/- 3.7 and 21.0 +/- 8.7 mL/s, respectively (P <0.01).

CONCLUSIONS

We suggest a regular, simple urethral dilation protocol for patients with recurrent bulbomembranous urethral stricture shorter than 2 cm, because this significantly allays the stricture recurrence rate, possibly eliminates the need for consecutive DVIU, and reduces morbidity.

Low-field interventional MRI in neurosurgery: finding the right dose of contrast medium

MRI is increasingly being used as an interventional tool in neurosurgery. The field strength of "intraoperative" MR systems is usually lower than that of imagers commonly used for diagnostic purposes. However, lesion enhancement and apparent lesion extent depend on field strength. The aim of this study was to compare the contrast between intracranial, contrast-enhancing space-occupying lesions and the surrounding white matter obtained with low-field (0.2 T) and high-field (1.5 T) MR imaging and to find the contrast medium dosage for low-field MRI that produces the same lesion-to-white-matter contrast as the one obtained with high-field MRI after the administration of a standard dose of the contrast medium. A total of 38 patients with intracranial metastases or high-grade glioma were enrolled in this study. T1-weighted spin-echo sequences were acquired. High-field (1.5 T) studies were performed after the i.v. administration of 0.1 mmol gadolinium-DTPA/kg body weight. For low-field MRI (0.2 T) a dose escalation technique was used. T1-weighted sequences were repeated after each of three i. v. injections of 0.1 mmol gadolinium-DTPA/kg body weight. Thus, at the low-field examinations three T1-weighted sequences with a contrast medium dosage of 0.1, 0.2 and 0.3 mmol gadolinium-DTPA/kg body weight were obtained. Lesion-to-white-matter contrasts were calculated and compared. The average lesion-to-white-matter contrast obtained with high-field MR examinations was 1.63 (standard deviation 0.32). In the low-field MR examinations the average lesion-to-white-matter contrast was 1.34 (0.2) after a single dose, 1.57 (0.2) after a double dose, and 1.71 (.19) after a triple dose of contrast medium. The lesion-to-white-matter contrast of the high-field MR examination after a single dose of contrast medium was significantly higher than that of the low-field study after a single dose (P < 0.0001), but did not differ significantly from the low-field studies after a double (P = 0.28) or a triple dose (P = 0.17) of contrast medium. In a series of patients with contrast-enhancing space occupying brain lesions low-field MRI (0.2 T) after a double dose of contrast medium yielded the same lesion-to-white-matter contrasts as high-field MRI (1.5 T) after a standard dose. This is an important finding to avoid errors in intraoperative MRI due to the immanently lower degree of lesion enhancement in low-field MR imaging.

The fate of intraperitoneally retained gallstones with different morphologic and microbiologic characteristics: an experimental study

Management of intraperitoneally retained gallstones after laparoscopic cholecystectomy (LC) is controversial, as their natural course is not known. This study was undertaken to assess the probable effects of stone morphology and clinically obvious infection on the outcome of retained gallstones in a mouse model. Forty albino mice were divided into four groups. Group I served as the control group (simple laparotomy, n = 10). Groups II, III, and IV (n = 10 in each group) were study groups. "Intact-sterile-cholesterol" (group II), "crushed-sterile-cholesterol" (group III), and "intact" (n = 5) [group IVa] and "crushed" (n = 5) [group IVb] "infected-cholesterol" gallstones aseptically retrieved from three different human patients were implanted to the peritoneal cavity of the animals. Group IV animals were implanted with stones retrieved from an acutely inflamed gallbladder with proven infection. Animals were sacrificed 6 and 12 weeks after the operations. Cultures and tissue samples were obtained. No animal was lost, no microscopic or macroscopic abnormality was observed in groups I and II, and cultures remained negative. In group III, adhesions surrounding the fragmented stones were evident at the 12th week, and no mortality was encountered. The histopathology revealed a fibroblastic reaction, and cultures remained negative in group III. In group IV, three animals from group IVb and one animal from group IVa died because of intra-abdominal sepsis before their sacrifice. All remaining mice showed severe adhesions with localized abscesses at the 12th week. In conclusion, intraperitoneally retained cholesterol gallstones remain inert and do not cause serious peritoneal reaction unless they are crushed into fragments or are from an acutely inflamed gallbladder. It is for this group of patients that laparotomy for total stone clearance is probably not justifiable. Better stone retrieval techniques or even laparotomy may be worthwhile considering in patients with crushed and particularly infected retained stones.

Haemodynamic effects of pneumoperitoneum during laparoscopic cholecystectomy: a prospective comparative study using bioimpedance cardiography

The haemodynamic effects of increased intra-abdominal pressure during laparoscopic cholecystectomy in 22 patients were compared with those in 11 patients undergoing open cholecystectomy; bioimpedance cardiography was used for monitoring at predetermined time intervals. In the laparoscopy group stroke volume, cardiac and ejection velocity indices were significantly decreased and the total peripheral resistance index was significantly increased during the insufflation period when compared with preinsufflation and corresponding values in the group undergoing open operation. Routine intraoperative parameters such as heart rate and blood pressure did not show any significant change or indicate alterations in cardiovascular performance during laparoscopic procedures. Continuous non-invasive cardiovascular monitoring by bioimpedance cardiography may be useful in patients with limited cardiac function.

Contribution of Calcium and Other Dietary Components to Global Variations in Bone Mineral Density in Young Adults

A research project on comparative international studies of osteoporosis using isotope techniques was organized by the International Atomic Energy Agency (IAEA) with the participation of 12 countries (Brazil, Canada, Chile, China, Croatia, Hungary, Philippines, Russia, Singapore, South Africa, Turkey, and the United Kingdom). Participating centers in 11 countries (all but the UK) made measurements and collected data on men and women aged 15 to 49 years. In addition to studies of bone mineral density (BMD) at the femoral neck and lumbar spine using DEXA, anthropometric, lifestyle, and nutritional data were also collected. The results of the nutritional studies are reviewed in this paper. Overall, about 8% of the observed variability in spine BMD could be attributed to nutritional factors in men and women; in men, no such relationship could be determined. No single nutritional component (not even calcium) stood out as being of particular importance across all participating centers.

The zipper-mesh method for treating delayed generalized peritonitis

Recently, many articles have been published related to the "open abdomen" concept which is performed particularly on patients with delayed generalized peritonitis. Since most arguments still support the effectiveness of this method and the results have been mostly favourable, it was decided to use the technique on 14 patients with peritonitis. Commercial zippers either with or without mesh were used on all. Four patients, however, died in the very early postoperative period and were excluded from the study. Others were examined as to the operative findings, period of delay, concomittant diseases, primary operations, indications of the technique, the number and type of the reinterventional procedures, status of remote organ failure, expected and realized mortality. Forty laparatomies were performed on 10 patients. In addition to obtaining a clean intraperitoneal cavity, some additional procedures such as anastomotic repair or gastroenterostomy could be done. The mean period of ventilator support was 27 h, the ambulation period was 3 days. The start of enteral nutrition early was able to be achieved more easily. In the patients whose expected mortality rate was as high as 70%-90%, a rate of 40% was established in those ten patients.

Effect of hypertonic saline and alcohol on viability of daughter cysts in hepatic hydatid disease

OBJECTIVE

To test the efficacy of hypertonic saline (20%) and absolute alcohol on the integrity of daughter cysts and the viability of the protoscoleces contained in these cysts.

DESIGN

Experimental study.

SETTING

Teaching hospital, Turkey.

MATERIAL

80 daughter cysts obtained from two patients with Gharbi type III hydatid cysts of the liver.

INTERVENTIONS

The cysts were divided into two groups, in the first of which cysts were placed into hypertonic saline and in the second into absolute alcohol; they were kept there for 5, 15, 30 or 60 minutes.

MAIN OUTCOME MEASURES

Integrity of the cyst wall and viability of the contents were evaluated using a vital staining technique with 0.1% eosin.

RESULTS

Neither hypertonic saline nor absolute alcohol solution had any effect on the integrity of the daughter cysts or the viability of the protoscoleces.

CONCLUSION

Percutaneous drainage of type III hydatid cysts can lead to high recurrence rates.

Cavernosal arterial anatomic variations and its effect on penile hemodynamic status

OBJECTIVE

With continuous improvements in ultrasound technology, small vessels with remarkably slow blood flow that may not be assessed by color Doppler ultrasonography, can be evaluated using power Doppler ultrasonography. In the present study, penile arterial anatomic variations were determined with power Doppler ultrasonography and its impact on penile hemodynamic status.

METHODS

A total of 54 patients with erectile dysfunction were evaluated with power Doppler ultrasonography. The effects of vascular anatomic variations and the structure of the corpora cavernosa and tunica albuginea on vascular status were assessed on both sides.

RESULTS

A normal penile vascular system was observed in 35.2% and 25% of 54 patients (mean age: 46.6+/-11.5 years) at the radix and mid-shaft of the penis, respectively. Pure arterial component was observed in 40.7% (22/54) and 47.2% (17/36) of the patients at the base and mid-shaft of the penis, respectively. Penile arterial insufficiency was severe in 9.2 and 5.5% of the patients at the base and mid-shaft of the penis, respectively, whereas intrapenile truncus was found in six patients (5.5%), the ratio of single cavernosal artery, intrapenile and extrapenile bifurcations were 69.4, 7.4 and 12.0%, respectively. Twenty (18.5%) dorso-cavernosal perforators, 15 (13.9%) cavernoso-dorsal and 30 (27.8%) intercavernosal branches were found. Peak systolic blood flow velocity values were decreased in 12 of 36 patients (33.3%) distally, while increased blood flow was observed in 11 (30.5%).

CONCLUSIONS

Hemodynamic parameters might be variable at either side of the penis and depend on intrapenile arterial anatomic variations. Parameters determined using power Doppler ultrasonography should be evaluated from the proximal to distal side of the penis to obtain reliable and standard results. However, variations of penile arterial anatomy and its effect on penile hemodynamic changes should not be overlooked especially in the patients who are candidates for penile reconstructive or vascular surgery.

Retroperitoneal lipoblastoma involving the right common iliac artery and vein

A case of benign lipoblastoma of the retroperitoneum in a 12-month-old boy, presenting as a huge abdominal mass and right lower extremity swelling, was reported. Surgery revealed involvement of the right common iliac artery and vein by lipoblastoma, requiring the sacrifice of both vessels for complete removal of the tumour. Vascular continuity of both vessels was re-established by a saphenous vein graft interposition. Involvement of a great artery by benign lipoblastoma has not been reported before.

Hydrochloric acid for treating metabolic alkalosis

Six patients with severe metabolic alkalosis were treated with intravenous hydrochloric acid (HCl) infusion. HCl was given through a central venous catheter, at a concentration of 0.1 mEq per ml. At least two of the following criteria were considered for initiation of the therapy: An arterial pH of greater than 7.45, a base excess (BE) of greater than +7 mmol/L, a PaCO2 of greater than 50 mmHg. The HCl amount was calculated using the BE formula, however, two thirds was infused for avoiding excessive acid loading. Patients were monitored by the blood gases, serum electrolytes, hemoglobin, hematocrit, bilirubin determinations and blood smear findings. While a significant decrease was noticed in pH and BE values, moderate changes were detected in PaCO2 due to different ventilatory status of the cases. All laboratory test results remained within normal limits and no complication was encountered. The advantage of the therapy is that less volume is needed for the correction of alkalosis, particularly in the cases requiring fluid restriction. HCl therapy, moreover, is a safe and time-saving method because of having rapid response to the treatment in the critically ill surgical patients.

Ischemia and reperfusion injury: prevention of pulmonary hypertension and leukosequestration following lower limb ischemia

Ischemia is a common clinical event with potentially serious consequences. The major part of tissue damage occurs upon reperfusion and is mediated by activated neutrophils. Ischemia reperfusion injury is manifested by oedema and increased microvascular permeability. This study tested cardiopulmonary functions following 2 h of lower limb ischemia. Anesthetized dogs were randomized into three groups: nonischemic sham dogs (n = 4), ischemic control dogs (n = 8) and ischemic dogs pretreated with prostaglandin (PG)E1 (n = 8). In control animals, mean pulmonary artery pressure (mPAP) increased 1 min after declamping from 13.37 +/- 2.61 mmHg to 16.88 +/- 3.68 mm Hg (P < 0.05). Pulmonary microvascular pressure (Pmv) increased within 1 minute of reperfusion from 7.71 +/- 1.87 mm Hg to 10.54 +/- 3.71 mm Hg (P < 0.05). These changes are consistent with increased lung microvascular permeability. White blood cell count fell slightly but not significantly and lung histology showed leukosequestration in alveoli of 171 +/- 22 polymorphonuclear leukocyte (PMN)/10 high powered fields (HPF) in the ischemic control group compared with 121 +/- 56 PMN/10 HPF in the sham group (P < 0.05). Systemic arterial pressure, cardiac output, central venous pressure and pulmonary artery wedge pressure were unaffected. In animals pretreated with PGE1, mPAP and Pmv were unchanged during reperfusion. Lung histologic findings appeared normal and leukosequestration was not observed. PMN counts in alveoli showed 95 +/- 26 PMN/10 HPF, lower than in ischemic control animals (P < 0.05). These data indicate that lower limb ischemia during reperfusion leads to pulmonary hypertension and leukosequestration, PGE1 infusion is effective in limiting ischemia reperfusion injury.

Prospective evaluation of complications in laparoscopic urology at a mid-volume institution using standardized criteria: Experience of 1023 cases including learning curve in 9 years

AIM:

To evaluate the laparoscopic operations performed in our department according to the modified Clavien classification system of complications.

MATERIALS AND METHODS:

Between September, 2005 and February, 2014, a total of 1023 laparoscopic cases were performed. This period was divided into three terms (Terms 1, 2 and 3 consisting of 38, 32 and 32 months, respectively). According to the European Scoring System (ESS), easy (E), slightly difficult (SD), fairly difficult (FD), difficult (D), very difficult (VD) and extremely difficult (ED) cases were 35, 88, 170, 390, 203 and 137, respectively. The perioperative complications were evaluated based on the 3 time periods, with a specific emphasis on determining the learning curve according to the modified Clavien classification system of complications.

RESULTS:

A total of 236 (23.1%) complications were observed according to the modified Clavien classification. The minor (Clavien I-II) and major (Clavien III, IV and V) complication rates were 20.5% (n = 210) and 2.4% (n = 26), respectively. Clavien I was the most frequently encountered type of complication (n = 120, %11.7). No significant difference was observed among all 3 time periods regarding total complication rates. The D cases had the highest complication rate compared to E, SD, FD, VD and ED cases among all three terms. The total number of complications increased significantly with increasing grade of technical difficulty according to the ESS.

CONCLUSION:

Complications encountered in our laparoscopic surgery experience were predominantly minor, and the rate of complications was not significantly increased during the learning curve. The present data can provide guidance and manage expectations for surgeons introducing laparoscopy into their practice.

[Extramedullary blastic transformation revealed by a prolonged fever during the course of a 5q- syndrome]

INTRODUCTION

Fever during a myelodysplastic syndrome can be due to infectious complications, systemic disease or acute transformation with clonal evolution.

CASE REPORT

A 51-year-old woman, with a 5q- syndrome and neutropenia, presented with a several week fever duration. Infectious work-up was negative and therapy with antibiotics had no influence on the clinical course. Neither bone marrow nor blood blasts were detected, but liver biopsy demonstrated significant blast infiltration compatible with the diagnosis of acute myeloid leukaemia (AML).

CONCLUSION

The absence of blasts in blood or bone marrow does not exclude the malignant transformation of a myelodysplastic syndrome to AML. Tissue biopsy may be necessary to confirm the leukaemic progression.

Discrete vector quantization for arbitrary distance function estimation

There are currently many vastly different areas of research involving adaptive learning. Among them are the two areas that concern neural networks and learning automata. This paper develops a method by which the general philosophies of vector quantization (VQ) and discretized automata learning can be incorporated for the computation of arbitrary distance functions. The latter is a problem which has important applications in logistics and location analysis. The input to our problem is the set of coordinates of a large number of nodes whose internode arbitrary "distances" have to be estimated. To render the problem interesting, nontrivial, and realistic, we assume that the explicit form of this distance function is both unknown and uncomputable. Unlike traditional operations research methods, which use optimized parametric functional estimators, we have utilized discretized VQ principles to first adaptively polarize the nodes into subregions. Subsequently, the parameters characterizing the subregions are learned by using a variety of methods (including, for academic purposes, a VQ strategy in the meta-domain). After an initial training phase, a system which achieves distance estimation attempts to yield an estimate of any node-pair distance without actually deriving an explicit form for the unknown function. The algorithms have been rigorously tested for the actual road-travel distances involving cities in Turkey and the results obtained are conclusive. Indeed, these present results are the best currently available from any single or hybrid strategy.

Surgical treatment of hepatic hydatidosis combined with perioperative treatment with albendazole

OBJECTIVE

To evaluate the effect of albendazole combined with surgery on the incidence of recurrent hydatid disease.

DESIGN

Prospective open study.

SETTING

Teaching hospital, Turkey.

SUBJECTS

25 patients who presented with hepatic hydatid disease between December 1992 and October 1995.

INTERVENTIONS

Albendazole 10 mg/kg/day for a month before ultrasonography and then excision, and then albendazole for a further two months.

RESULTS

2 patients were excluded because the albendazole caused disturbance of liver enzyme activities. Of the remaining 23 patients only 7 had viable cysts on ultrasonography. In 15 patients (65%) the germinal layer was partially or totally destroyed, and in 15 the fluid was either cloudy or stained with bile. During a mean follow up period of 29 months only one patient developed recurrent disease.

CONCLUSION

Perioperative treatment with albendazole resulted in fewer recurrences than expected. A longer preoperative period of treatment may increase the success rate; this requires further study.