A simple check valve for microfluidic point of care diagnostics.

Check valves are often essential components in microfluidic devices, enabling automated sample processing for diagnostics at the point of care. However, there is an unmet need for a check valve design that is compatible with rigid thermoplastic devices during all stages of development-from initial prototyping with a laser cutter to final production with injection molding. Here, we present simple designs for a passive, normally closed check valve that is manufactured from commonly available materials with a CO2 laser and readily integrated into prototype and production thermoplastic devices. The check valve consists of a thermoplastic planar spring and a soft elastomeric pad that act together to seal against fluid backflow. The valve's cracking pressure can be tuned by modifying the spring's planar geometry and thickness. Seal integrity is improved with the addition of a raised annular boss beneath the elastomeric pad. To demonstrate the valve's usefulness, we employ these valves to create a finger-operated on-chip reagent reservoir and a finger-actuated pneumatic pump. We also apply this check valve to passively seal a device to enable portable detection of RNA from West Nile virus in a laser-cut device.

Palliative treatment of an enterorectal fistula with a covered metallic stent.

In patients with recurrent colorectal cancer, the development of fistulae presents a difficult therapeutic problem. The traditional surgical approach of resection and intestinal diversion may not always be appropriate in those with disseminated or terminal disease. We present the successful use of a covered esophageal stent to occlude an enterorectal rectal fistula in a patient with recurrent inoperable colonic carcinoma.

Congenital absence of the portal vein in liver transplantation for biliary atresia.

BACKGROUND: Extrahepatic biliary atresia is the most common indication for liver transplantation in children. Coexistent congenital anomalies are common (25%), but the combination of polysplenia syndrome (10%) and absence of portal vein is rare. AIMS: We report a case of successful reduced size liver transplantation on a 13-month-old girl with extrahepatic biliary atresia, polysplenia syndrome and congenital absence of the portal vein. METHODS: Technical and post-operative problems related to absence of the portal vein and polysplenia are described and the literature reviewed. RESULTS: The donor portal vein was successfully anastomosed to the confluence of the superior mesenteric vein and splenic vein. The child is well with good graft function at a follow-up of 20 months. CONCLUSION: Absence of the portal vein and polysplenia syndrome is not a contraindication for liver transplantation although an increased post-operative morbidity may be expected.

Cri du chat and Turner syndrome features in a newborn girl with an unbalanced 45,X,psu dic(5;X)(p15.2;p22.1) karyotype: FISH and replication banding studies.

A newborn girl with features of Turner and Cri du chat syndromes was found to have a pseudodicentric 5;X chromosome. Her karyotype was 45,X, psu dic(5;X)(p15.2;p22.1). The net result was monosomy for 5p15.2-pter and Xp22.1-pter. Fluorescence in situ hybridization (FISH) showed the Cri du chat region was deleted. Replication banding studies to assess the X-inactivation pattern found only the X portion of the pseudodicentric chromosome to be late replicating without any apparent spread of inactivation into chromosome 5 segment. There are only two cases reported with a dicentric X; autosome. In this paper, we compare the cytogenetics of the present case and those in the literature.

Global issues in pediatric nutrition: AIDS.

Nutrition is a final common pathway in chronic disease, and weight loss is a major manifestation of acquired immunodeficiency syndrome (AIDS). In sub-Saharan Africa, studies have shown that 25% of children with malnutrition have human immunodeficiency virus (HIV) infection, although patterns of malnutrition are indistinguishable from those who are HIV negative. Breast-feeding increases the risk of vertical transmission, and the overall risk versus benefit needs continuing careful consideration in relation to local mortality from gastroenteritis and malnutrition. Chronic diarrhea is much more common in HIV-infected children in Africa and may have a multiplicity of causes, including infection with adherent forms of Escherichia coli, protozoa, and even direct HIV infection of intestinal mucosal cells. The HIV wasting syndrome produces reduction in bioelectrical impedence, fat, lean body mass, and body cell mass, but the changes can be predicted from equations used in starvation states. Micronutrients may be important, but observed changes may be due to immune mediator activation, rather than malnutrition. Calorie supplementation is beneficial when delivered by any route, but is likely to produce the greatest positive change when CD4 counts are highest in relation to calorie intake. Paradoxically, HIV-infected children may be obese early in the disease until AIDS develops. There is an inextricable link between disease and nutritional status. In children with AIDS wasting syndrome, a low CD4 count and high viral load are likely so that effective antiviral treatment may ultimately produce the greatest improvement in health, including nutritional status.

The development of a community-based family HIV service.

This paper describes the development of a community-based family HIV clinic in south London, an area with one of the highest rates of HIV seroprevalence in the UK. The King's family clinic was developed by broadening existing interdisciplinary services for women with HIV, utilizing the strengths of community-based paediatric care as well as integrating paediatric support from acute hospital-based services. Different models of care for children infected or affected by HIV and problems encountered in developing the service, including ethical dilemmas, and current activity are discussed.

Effect of rifampicin in the treatment of pruritus in hepatic cholestasis.

Pruritus in hepatic cholestasis has been suggested to be secondary to a high concentration of serum bile acids. Rifampicin, which inhibits the uptake of bile acids by hepatocytes, has been used to treat pruritus. To determine the efficacy of rifampicin as a treatment for refractory pruritus, the medical records of 33 children (median age 25 months, range 4-135; 19 boys) with chronic cholestasis liver disease (21 with Alagille's syndrome, eight with progressive intrahepatic cholestasis, one with extrahepatic biliary atresia, one with an inborn error of bile acid metabolism, and one with cryptogenic cirrhosis) were reviewed retrospectively. The median dose of rifampicin was 5(4-10) mg/kg/day. The median duration of intake was 36(4-120) weeks. Complete relief of pruritus was noted in five (15%) patients and a partial response in 12 (36%). Overall, no significant difference was noted in the laboratory parameters before and after treatment with rifampicin. In the 21 patients with Alagille's syndrome, however, a significant decrease in alkaline phosphatase was seen before and after one and six months of starting treatment. No adverse side effects were seen. Rifampicin appears to be effective in the treatment of refractory pruritus. A prospective study is warranted to assess further the effect of rifampicin treatment in children with hepatic cholestasis.

Role of intragastric and intraoesophageal alkalinisation in the genesis of complications in Barrett's columnar lined lower oesophagus.

Patients with Barrett's columnar lined lower oesophagus have severe acid gastrooesophageal reflux and may develop complications, including ulceration, stricture, and carcinoma. The aim of this study was to establish if a relationship exists between the pH profile in the oesophagus and stomach and the development of complications in patients with Barrett's columnar lined lower oesophagus. Twenty four hour ambulatory oesophageal pH monitoring was performed in 26 patients with Barrett's columnar lined lower oesophagus and combined with 24 hour ambulatory gastric pH monitoring in 16. Ten of the 26 with Barrett's columnar lined lower oesophagus had complications including stricture (eight), deep ulceration (one), and carcinoma (one). Oesophageal acid exposure (% time < pH 4) was similar in patients with or without complications (19.2% v 19.3% p > 0.05). Oesophageal alkaline exposure (% time > pH 7) was greater in patients with complications (24.2% v 8.4% p > 0.05). Of the 16 patients who underwent gastric pH monitoring there was a clear relationship between gastric and oesophageal alkalinisation in 13. These results support the hypothesis that complications in Barrett's columnar lined lower oesophagus develop in association with increased exposure of the oesophagus to an alkaline environment which appears to be secondary to duodenogastric reflux. The routine use of 24 hour ambulatory gastric pH monitoring in conjunction with oesophageal pH monitoring can help identify those patients at risk.

A more physiological alternative to total fundoplication for the surgical correction of resistant gastro-oesophageal reflux.

The incidence of mechanical complications associated with the Nissen fundoplication has prompted evaluation of an anti-reflux procedure designed to be simpler and more physiological, and encompassing a broader view of the many factors involved in the anti-reflux mechanism. Preliminary assessment of the first 100 patients with a mean follow-up of 3.5 years showed symptomatic improvement in 96 per cent and complete relief in 85 per cent. A further 100 patients were studied using formal symptom scoring, endoscopy, manometry and pH monitoring performed before operation and 3 months after operation. Similar clinical results were accompanied by improvement in endoscopic oesophagitis in 95 per cent, complete healing in 74 per cent and restoration of the pH profile to physiological levels in 84 per cent. Troublesome mechanical complications comprised a 2 per cent incidence of dysphagia, but there was no gas bloat or inability to belch or vomit, which may relate to the restoration of lower oesophageal sphincter characteristics close to those of 30 asymptomatic controls. The procedure is simpler to perform than total fundoplication, is well tolerated and is applicable to patients with reflux stricture and impaired oesophageal body motility. The results of this study support the hypotheses that effective reflux control can be achieved without total fundoplication by attention to several factors of known relevance to the anti-reflux mechanism, and that restoration of characteristics of the lower oesophageal sphincter close to physiological levels results in a lower incidence of mechanical complications.

The cause of dysphagia in uncomplicated sliding hiatal hernia and its relief by hiatal herniorrhaphy. A roentgenographic, manometric, and clinical study.

Patients with an uncomplicated sliding hiatal hernia frequently experience dysphagia. The present study shows, using video barium contrast esophagograms, that the cause of dysphagia in 60% of these patients is an obstruction to the passage of the swallowed bolus by diaphragmatic impingement on the herniated stomach. Manometrically this was reflected by a double-hump high pressure zone (HPZ) at the gastroesophageal junction, and specifically to the length and amplitude of the distal HPZ and the length of the intervening segment between the two HPZs. The former represents the degree of the diaphragmatic impingement on the herniated stomach and the latter the size of the supradiaphragmatic herniated stomach. Surgical reduction of the hernia resulted in relief of dysphagia in 91% of the patients.

The pharmacokinetics of the biliary excretion of ciprofloxacin.

The pharmacokinetics of ciprofloxacin excretion have been studied in 54 patients undergoing biliary and pancreatic operations with and without obstruction of the common bile duct. High concentrations were achieved in common duct bile within 20 minutes of intravenous injection and persisted for over 3 hours after 100 mg and for over 8 hours after 200 mg. The concentration of ciprofloxacin in the bile of functioning gall bladders was much greater than that in the common duct bile. Remarkably, it was identified in therapeutic concentrations in the bile of obstructed ducts. This and the rapid fall from initially high venous concentrations probably reflect diffusion from the circulation as a result of the exceptional tissue penetration. A unique feature of this study was the finding of clinically significant concentrations in the bile of obstructed ducts. Two patients developed wound infection and no side effects were observed. The broad spectrum antibiotic ciprofloxacin has potential as a useful agent for prophylaxis in biliary surgery maintaining biliary and venous concentrations in excess of the MIC90 for most biliary pathogens for more than 8 hours.

The significance of the gastric secretory state in gastroesophageal reflux disease.

The gastric secretory status of 75 patients with abnormal esophageal exposure to gastric juice proved by 24-hour pH monitoring was measured to study the significance of gastric hypersecretion in gastroesophageal reflux disease. Gastric hypersecretion was a less-frequent finding than a mechanically defective sphincter (28% vs 72%, respectively). Forty-eight percent of patients with a normal sphincter, compared with 20% of those with a defective sphincter, were hypersecretors. In the presence of normal gastric secretion, complications occurred in 18% of those with a normal sphincter and 77% of those with a defective sphincter. In the presence of hypersecretion, the complication rate was 40% and 82%, respectively. These findings show that the development of reflux complications are related to a defective sphincter. Gastric hypersecretion in reflux patients with a normal sphincter is best treated by acid reduction using H2 blockers. Patients with a mechanically defective sphincter, regardless of their gastric secretory state, should have an antireflux procedure.

Experimental and clinical results with proximal end-to-end duodenojejunostomy for pathologic duodenogastric reflux.

Existing Roux-en-Y bile diversion procedures for duodenogastric reflux coupled with distal gastric resection or antrectomy and vagotomy have varied success due to interruption of the physiologic relationships between stomach and duodenum, the reduction of the gastric reservoir, the side effects of vagotomy, and the effect of the Roux limb on gastric emptying. A new bile diversion procedure, suprapapillary Roux-en-Y duodenojejunostomy, was studied, which eliminates the need for gastric resection to prevent jejunal ulcers by preserving duodenal inhibition of gastric acid secretion and the protective effects of duodenal secretion on the surrounding mucosa. Experimentally, the incidence of jejunal ulceration was significantly decreased by the preservation of the proximal duodenum. Clinically, bile diversion by suprapapillary Roux-en-Y duodenojejunostomy alleviates symptoms of duodenogastric reflux disease without being ulcerogenic (in the presence of normal gastric secretion) or prolonging gastric emptying.