The mechanical behavior and biocompatibility of polymer blends for Patent Ductus Arteriosus (PDA) occlusion device.

Patent Ductus Arteriosus (PDA) is a cardiovascular defect that occurs in 1 out of every 2000 births, and if left untreated, may lead to severe cardiovascular problems. Current options for occluding utilize meta scaffolds with polymer fabric, and are permanent. The purpose of this study was to develop a fully degradable occluder for the closure of PDA, that can be deployed percutaneously without open-heart surgery. For percutaneous deployment, both elasticity and sufficient mechanical strength are required of the device components. As this combination of properties is not achievable with currently-available homo- or copolymers, blends of biodegradable poly(ε-caprolactone) (PCL) and poly(L-lactide-co-ε-caprolactone) (PLC) with various compositions were studied as the potential material for the PDA occlusion device. Microstructures of this blend were characterized by differential scanning calorimetry (DSC) and tensile tests. DSC results demonstrated the immiscibility between PCL and its copolymer PLC. Furthermore, the mechanical properties, i.e. elastic modulus and strain recovery, of the blends could be largely tailored by changing the continuous phase component. Based on the thermo-mechanical tests, suitable blends were selected to fabricate a prototype of PDA occluder and its in vitro performance, in term of device recovery (from its sheathed configuration), biodegradation rate and blood compatibility, was evaluated. The current results indicate that the device is able to recover elastically from a sheath within 2-3min for deployment; the device starts to disintegrate within 5-6 months, and the materials have no adverse effects on the platelet and leucocyte components of the blood. Biocompatibility implantation studies of the device showed acceptable tissue response. Finally, an artificial PDA conduit was created in a pig model, and the device deployment was tested from a sheath: the device recovered within 2-3min of unsheathing and fully sealed the conduit, the device remains stable and is completely covered by tissue at 1 month follow up. Thus, a novel prototype for PDA occlusion that is fully degradable has been developed to overcome the limitations of the currently used metal/fabric devices.

Toll-like receptors.

Toll-like receptors are a family of transmembrane receptors responsible for recognition and initiation of a response to invading microbes by the immune system. As part of the innate immune system, Toll-like receptors recognise pathogen-associated molecular patterns, highly conserved components that are essential to microbial function. Some of ten toll-like receptors identified in humans are able to recognise several pathogen-associated molecular patterns.

The maximal vertical pocket and amniotic fluid index in predicting fetal distress in prolonged pregnancy.

OBJECTIVE: To determine cut-off values for amniotic fluid volume (AFV) predictive of fetal distress in pregnancies 40 weeks or longer, assessed using both amniotic fluid index (AFI) and height of the of maximal vertical pocket (MVP). METHODS: Amniotic fluid index and MVP were evaluated in 100 women with pregnancies of 40 or more weeks and intact membranes using a 3.5-MHz linear transducer less than 1 week prior to onset of labor. Both measurements were obtained for each participant by the same obstetrician in one sitting. Oligohydramnios was defined as an AFI of 5 cm or less or an MVP of 3 cm or less. External cardiotocography was performed during intrapartum in all cases. Fetal distress was diagnosed when any one of the nonreassuring fetal heart rate pattern occurred or when the Apgar score at birth was 6 or less. The results were analyzed by the chi(2) and the t tests. RESULTS: An AFI of 5 cm or less was a better predictor of fetal distress than an MVP of 3 cm or less (P=0.000). The most statistically significant cut-off values for the occurrence of fetal distress in prolonged pregnancies were an AFI of 8 cm or less (odds ratio, 7.50) or an MVP of 2 cm or less (odds ratio, 2.67). There was a significant correlation between these 2 methods (r=+0.67), with a level of significance of 0.01, as shown by the regression curve. The secondary outcome was the statistically significant association between meconium-stained liquor and fetal distress (P=0.001). CONCLUSION: In pregnancies of 40 weeks or longer there was a risk of fetal distress when the AFV was 8 cm or less by the AFI method or 2 cm or less as measured by MVP. In such cases, intensive intrapartum monitoring should be performed to prevent fetal jeopardy.

Seroprevalence of Burkholderia pseudomallei in East Timorese refugees: implications for healthcare in East Timor.

Melioidosis is a disease with protean clinical manifestations caused by the bacterium Burkholderia pseudomallei. It is endemic in countries surrounding the newly independent East Timor, but has yet to be isolated or demonstrated serologically in that country. One illness that can be clinically indistinguishable from melioidosis is pulmonary tuberculosis, a condition with a very high prevalence in East Timor. We used an indirect hemagglutination test (IHA) to measure antibodies to B. pseudomallei in 407 East Timorese evacuated to Darwin, Australia, in September 1999. Assuming a positive IHA titer as > or = 1:40, the overall seroprevalence rate was 17.0%, in keeping with other seroprevalence studies from the region. The IHA titres ranged up to 1:320. After adjusting for age, females were 2.5 times more likely to be seropositive than males (p = 0.0001). There was an inverse relationship between seropositivity and age. This study shows that exposure to B. pseudomallei occurs in East Timor melioidosis is also likely to occur. Due to the lack of laboratory facilities at present, it may be some time before a laboratory-confirmed case proves that melioidosis occurs. In the meantime, clinicians in East Timor should include melioidosis in the differential diagnosis of the many conditions that it may mimic.

Granulocyte colony-stimulating factor and an in vitro whole blood model of melioidosis.

The study reported here was conducted in order to explore the mechanism of action of granulocyte colony-stimulating factor (G-CSF) in the treatment of Burkholderia pseudomallei infections (otherwise known as melioidosis). Use of G-CSF as an adjunct to antibiotics has been associated with decreasing mortality among patients with melioidosis in the tropical region of the Northern Territory of Australia. However, using an in vitro whole blood assay, no significant difference was detected in the bactericidal activity of samples obtained from dialysis patients, patients with type 2 diabetes mellitus and healthy controls, and there was no improvement following coincubation with G-CSF.

Primary peritoneal pregnancy: a case report.

A 22-year-old primipara using intrauterine contraceptive device was diagnosed to be in haemorrhagic shock due to acute ruptured ectopic pregnancy. At laparotomy, both tubes and ovaries were normal and products of conception were found to be implanted on the posterior surface of uterus near the attachment of right uterosacral ligament producing a haemoperitoneum of more than 2 l. This is the fourth case report of primary abdominal pregnancy associated with intrauterine contraceptive device (IUCD).