Survival prolongation of microencapsulated allogeneic islet by nanosized nordihydroguaiaretic acid.

Immunoisolation such as alginate-poly-L-lysine-alginate (APA) microencapsulation may protect entrapped islet graft cells from destruction by cellular and humoral immunities, but cannot avoid aggregation of macrophages and fibroblasts around microcapsules, which has been known to cause late dysfunction. Nordihydroguaiaretic acid (NDGA) is a lipoxygenase inhibitor that prevents the activation and chemotaxis of macrophages. In this study, we used the dialysis method without surfactant to prepare poly (DL-lactide-co-glycolide) (PLGA) nanoparticles to entrap NDGA. We determined the formulation conditions suitable for sustained release when coencapsulated with the islets. Nanoparticle sizes of 0.2-0.3 microm were suitable for sustained release in electromagnetic driven APA microcapsules. In the toxicity study, we coincubated islets with PLGA-NDGA nanoparticles in vitro for 2 and 4 weeks. The glucose stimulated insulin secretion and insulin contents of islets were not influenced significantly. To test whether nanosized NDGA provides extra protection for APA islets, about 160-200 allogeneic islets of C57BL/6 mice were either encapsulated alone using APA or coencapsulated with PLGA-NDGA. At 2 and 4 weeks after implantation into the peritoneal cavities of healthy BALB/c mice, the intraperitoneal islet grafts were recovered using lavage. Mice that received islets of APA-PLGA-NDGA preparations showed a higher recovery rate of functioning grafts than those that received islets prepared using APA alone (10.1%, n = 4 vs 5.2%, n = 3). In conclusion, nanosized NDGA prolonged the graft survival of APA microencapsulated allogeneic islets.

Enhancing islet engraftment with rosiglitazone.

To study the role of a peroxisome proliferator-activated receptor agonist, rosiglitazone, on islet engraftment, streptozotocin-induced diabetic C57BL/6 mice were fed daily rosiglitazone (2.4 mg/kg) for 9 and 31 days starting 2 days before transplantation with 75 and 150 syngeneic islets, respectively. After receiving 75 islets and 9 days of rosiglitazone, half of the treated diabetic mice became normoglycemic at 4 weeks, while none were normoglycemic among those mice that did not receive treatment. After transplanting 150 islets and receiving 31 days of rosiglitazone, 80% of the treated diabetic mice became normoglycemic while the incidence was only 25% for the controls. The insulin content of the islet grafts in the rosiglitazone groups was 0.8 times (75-islet group) and 1.3 times (150-islet group) higher than that of control mice. The insulin content of pancreatic remnants did not differ significantly among all groups. An in vitro study revealed that the glucose-stimulated insulin secretion and insulin content of cultured islets was not different in the presence versus absence of 4.5 or 22.5 micromol/L rosiglitazone. In vitro study revealed that rosiglitazone inhibited the lipopolysaccharide-induced secretion of interleukin-1 beta and interferon-gamma from peritoneal exudate cells. In conclusion, our data suggest that short-term administration of rosiglitazone enhances islet engraftment.

Adding learning to cellular genetic algorithms for training recurrent neural networks.

This paper proposes a hybrid optimization algorithm which combines the efforts of local search (individual learning) and cellular genetic algorithms (GA's) for training recurrent neural networks (RNN's). Each weight of an RNN is encoded as a floating point number, and a concatenation of the numbers forms a chromosome. Reproduction takes place locally in a square grid with each grid point representing a chromosome. Two approaches, Lamarckian and Baldwinian mechanisms, for combining cellular GA's and learning have been compared. Different hill-climbing algorithms are incorporated into the cellular GA's as learning methods. These include the real-time recurrent learning (RTRL) and its simplified versions, and the delta rule. The RTRL algorithm has been successively simplified by freezing some of the weights to form simplified versions. The delta rule, which is the simplest form of learning, has been implemented by considering the RNN's as feedforward networks during learning. The hybrid algorithms are used to train the RNN's to solve a long-term dependency problem. The results show that Baldwinian learning is inefficient in assisting the cellular GA. It is conjectured that the more difficult it is for genetic operations to produce the genotypic changes that match the phenotypic changes due to learning, the poorer is the convergence of Baldwinian learning. Most of the combinations using the Lamarckian mechanism show an improvement in reducing the number of generations required for an optimum network; however, only a few can reduce the actual time taken. Embedding the delta rule in the cellular GA's has been found to be the fastest method. It is also concluded that learning should not be too extensive if the hybrid algorithm is to be benefit from learning.

Ectopic ureter as a cause of wetting: the role of laparoscopy in its management.

A diagnosis of wetting caused by an ectopic ureter usually can be made from the history because of the characteristic pattern of wetting. Localization of the origin of the ectopic ureter is important in guiding the surgical approach. This is usually not a problem for cases of ectopic ureter arising from a duplex system. However, the single ectopic ureter arising from a small dysplastic and often ectopic kidney may defy a long search. Videolaparoscopy, with its magnifying effect, can confirm the diagnosis, localize the dysplastic kidney and allow its removal using endoscopic equipment.

Case report: neonatal adrenal haemorrhage presenting as an acute right scrotal swelling (haematoma)--value of ultrasound.

Acute scrotal swelling resulting from remote intra-abdominal pathology is a well recognized but rare entity. The present report relates to such a case in a neonate who presented with an acute right scrotal haematoma, adrenal haemorrhage not being suspected clinically, but detected ultrasonographically. In the imaging of neonatal scrotal swellings, abdominal ultrasound is important in excluding a primary intra-abdominal event.

Acute scrotal swelling: a sign of neonatal adrenal haemorrhage.

Two neonates presented with acute scrotal swelling suggestive of testicular torsion. Surgical exploration in one patient revealed an infected haematoma. Subsequent investigations including ultrasonography and urinary catecholamine determination disclosed adrenal haemorrhage as the cause of the scrotal haematoma. A second patient in whom a purplish discolouration of the right hemiscrotum was noted was also investigated with ultrasonography, which revealed a normal right testis and a right adrenal haematoma. Both cases of adrenal haemorrhage resolved spontaneously on conservative treatment. Adrenal haemorrhage should be considered as a possible cause of acute scrotal swelling in neonates. Ultrasonography assessment should be performed in such cases to examine the intra-abdominal organs especially the adrenal glands.

Sacrococcygeal teratoma in children: a diagnostic challenge.

Sacrococcygeal teratoma is relatively rare. Its characteristic appearance, location and size usually leave little doubt as to the diagnosis, but the less obvious ones may occasionally give rise to diagnostic difficulty. Four cases of sacrococcygeal teratoma in children are reported. One neonate presented with a large protuberant swelling at the sacrococcygeal area, with no diagnostic difficulty. The second neonate presented with a small paraxial sacral swelling with an overlying haemangioma. The third patient presented with a small tail-like appendage at the natal cleft. A properly performed rectal examination in both the second and third patients disclosed the diagnosis. The fourth patient presented with an anocutaneous fistula and partial sacral agenesis with no external sacrococcygeal swelling. The diagnosis was confirmed with computerized tomography. While the diagnosis of the protuberant sacrococcygeal teratoma presents no difficulty, that of the less obvious cases requires a high index of clinical suspicion. A properly performed rectal examination supplemented with appropriate imaging allows the diagnosis to be made.

Amoxycillin and clavulanic acid versus cefotaxime and metronidazole as antibiotic prophylaxis in elective colorectal resectional surgery.

In a prospective randomised controlled trial, amoxycillin plus clavulanic acid was compared to a combination of cefotaxime and metronidazole as prophylactic antibiotics in 164 patients who underwent elective colorectal resectional surgery. Wound infection occurred in 15 patients (9.1%) and deep surgical infection in 4 (2.4%). Seven cases of wound infection and 2 cases of deep infection occurred in the amoxycillin plus clavulanic acid arm, while 8 cases of wound infection and 2 cases of deep infection occurred in the cefotaxime plus metronidazole arm. Eighty-eight percent of infections occurred in patients who had low anterior resection or abdominoperineal resection of the rectum. Both the amoxycillin plus clavulanic acid and the combination of cefotaxime and metronidazole offer the same degree of protection against post-operative infection. The use of amoxycillin plus clavulanic acid as antibiotic prophylaxis is recommended because of its easier use and cheaper cost.

Management of bleeding liver tumours in Hong Kong.

A retrospective study was undertaken of 41 patients diagnosed as having suffered spontaneous liver rupture over a 4-year period to identify the clinical features, treatment and outcome of this complication in an area in which hepatocellular carcinoma is endemic. Two patients were excluded with a revised diagnosis of haemorrhagic malignant ascites. Of the remaining 39 patients, 37 bled from ruptured hepatocellular carcinoma, one from peliosis hepatis and multiple liver cell adenomas, and one from a malignant hepatic epithelioid haemangioendothelioma. Analysis showed that 59 per cent of patients were in shock on admission and that all but two of the 37 patients with ruptured hepatocellular carcinoma were men with cirrhosis. The association with cirrhosis was significantly higher than in a series of 45 patients with hepatocellular carcinoma undergoing elective resection during the same period (P less than 0.05). Treatment consisted of supportive care only in two patients, angiographic embolization in four, emergency liver resection in 11 of whom six died, hepatic artery ligation in 12 of whom eight died, and suture and/or packing in eight of whom six died. One patient died at laparotomy and in another patient bleeding was successfully arrested by intratumoural injection of absolute alcohol. Because of the high operative mortality of emergency surgery in these poor risk patients, prospective evaluation of emergency angiographic embolization is required.