Cadaver lungs for transplantation. Effect of ventilation with alveolar gas

In an effort to increase the donor pool for lung transplantation (LTX), we have demonstrated the feasibility of LTX from circulation-arrested cadavers in a canine LTX model. We hypothesized that ventilation of the cadaver lung with alveolar gas (20% O2, 5% CO2, balance N2) (AG) would be superior to ventilation with 100% oxygen (O2) after circulatory arrest of the donor. Twelve mongrel dogs were intubated, heparinized and euthanized by pentothal injection and ventilated with AG (n=6) or O2 (n=6). Four hours later, donor animals underwent sternotomy, and the lungs were flushed with cold modified Euro-Collins solution, harvested, and stored inflated in ice slush. Left lung allotransplantation was performed, and recipients were made dependent o n the transplanted lung by occlusion of the contralateral bronchus and pulmonary artery. Recipient animals were ventilated with an FiO2 of 0.4 and followed for 8 hr. Total ischemic time was 7.9 hr for both groups. Pulmonary edema developed in all recipients of AG lungs; one recipient survived the 8-hr observation period with poor oxygenation. In contrast, three of six recipients of O2-ventilated lungs survived for 8-hr with excellent gas exchange. Specimens of donor lungs before and after transplant were evaluated histologically utilizing trypan blue exclusion as an indicator of cell viability. At the time of organ retrieval 4 hr after death, 6% of cells were nonviable in the O2-ventilated cadaver lungs. Circulation-arrested cadaver lungs ventilated with 100% O2 prior to organ retrieval have superior pulmonary function after transplant compared with lungs ventilated with AG. Ventilation of cadaver lungs with AG induces pulmonary injury in this model. retrieval of donor lungs from circulation-arrested cadavers has potential for increasing the pulmonary donor pool.     

Application of neural networks and machine learning in networkdesign

Communication network design is becoming increasingly complex, involving making networks more usable, affordable, and reliable. To help with this, we have proposed an expert network designer (END) for configuring, modeling, simulating, and evaluating large structured computer networks, employing artificial intelligence, knowledge representation, and network simulation tools. We present a neural network/knowledge acquisition machine-learning approach to improve the END's efficiency in solving the network design problem and to extend its scope to acquire new networking technologies, learn new network design techniques, and update the specifications of existing technologies     

Absence of detectable human herpesvirus 8 in the semen of human immunodeficiency virus-infected men without Kaposi's sarcoma

The prevalence of human herpesvirus 8 (HHV-8)/Kaposi's sarcoma (KS)-associated herpesvirus was investigated in the semen of 99 human immunodeficiency virus (HIV)-infected men (median CD4 cell count, 357/mm3) by use of a polymerase chain reaction (PCR) assay capable of detecting <10 copies of HHV-8 DNA. Of the subjects, 95 (96%) self-identified as men who have sex with men (MSM), and 3 had a history of clinical KS. Seminal cell specimens were negative for HHV-8 in 98 subjects. None of the 26 without KS (27.1% of 96 tested) who were seropositive for HHV-8 by IFA for latency-associated nuclear antigens had HHV-8 detected in their semen. The only subject with any evidence for seminal HHV-8 DNA was seropositive for HHV-8 and had active KS. HHV-8 was detected in 10 (10.4%) of 96 peripheral blood mononuclear cell specimens. The prevalence of HHV-8 DNA by PCR in semen of HIV-infected MSM without KS is low.     

FlowMate: scalable on-line flow clustering

We design and implement an efficient on-line approach, FlowMate, for clustering flows (connections) emanating from a busy server, according to shared bottlenecks. Clusters can be periodically input to load balancing, congestion coordination, aggregation, admission control, or pricing modules. FlowMate uses in-band (passive) end-to-end delay measurements to infer shared bottlenecks. Delay information is piggybacked on feedback from the receivers, or, if impossible, TCP or application round-trip time estimates are used. We simulate FlowMate and examine the effects of network load, traffic burstiness, network buffer sizes, and packet drop policies on clustering correctness, evaluated via a novel accuracy metric. We find that coordinated congestion management techniques are more fair when integrated with FlowMate. We also implement FlowMate in the Linux kernel v2.4.17 and evaluate its performance on the Emulab testbed, using both synthetic and tcplib-generated traffic. Our results demonstrate that clustering of medium to long-lived flows is accurate, even with bursty background traffic. Finally, we validate our results on the Internet Planetlab testbed.     

Renal length in sickle cell disease: observations from a cohort study

Renal length has been measured by ultrasound in 237 subjects with homozygous sickle cell (SS) disease, 147 with sickle cell-hemoglobin C (SC) disease, and in 78 age-matched controls with a normal hemoglobin (AA) genotype. As expected, renal length increased with age in all genotypes but mean length was significantly greater in SS disease compared with SC disease (mean difference 4.3 mm after adjustment for height) and significantly greater in both genotypes than in AA controls (SS/AA difference 9.2 mm, SC/AA difference 5.0 mm after adjustment for height). Examination of relationships between renal length and some hematological indices (hemoglobin, fetal hemoglobin, reticulocyte counts, alpha thalassemia status) in SS or SC disease showed only a significant negative correlation with hemoglobin and positive correlation with reticulocyte count in SS disease. Further analysis suggested that the stronger relationship was between renal length and high reticulocyte count. The mechanism of renal enlargement is unknown although glomerular hypertrophy and increased renal blood volume are likely contributors.     

The region Ser333-Arg356 of the alpha-chain of human C4b-binding protein is involved in the binding of complement C4b

Human C4b-binding protein (C4BP) functions as a cofactor to factor I in the degradation of C4b and accelerates the decay rate of the C4b2a complex. In this study we describe a monoclonal antibody directed against the alpha-chain of C4BP that inhibits the binding of C4b to C4BP. In order to identify the structural domain of the alpha-chain of C4BP that interacts with C4b, tryptic fragments of C4BP were generated. Amino acid sequence analysis of the fragments revealed that the residues Ser333-Arg356 of the alpha-chain of C4BP contain the epitope of this antibody, and as a consequence, that this part of the alpha-chain of C4BP is likely to be involved in the interaction with C4b.     

Determinants of genital human papillomavirus infection among cytologically normal women attending the University of New Mexico student health center

OBJECTIVES: To confirm the risk factors for genital human papillomavirus (HPV) infection. GOAL OF THIS STUDY: To investigate risk factors for HPV detection apart from the correlated risk factors for cervical neoplasia. STUDY DESIGN: Cervical human papillomavirus (HPV) DNA was assessed in 357 cytologically normal women attending the University of New Mexico student health center. Cervical swab samples were obtained for HPV DNA detection and typing using a PCR-based DNA amplification system. Possible determinants of cervical HPV were examined including age, ethnicity, history of sexually transmitted disease, oral contraceptive use, smoking, age at first intercourse, lifetime number of sex partners, marital status, and history of pregnancy. RESULTS: A 44.3% overall prevalence of cervical HPV was observed. On univariate analysis, factors associated with increasing HPV prevalence included higher lifetime number of sex partners and single marital status. After adjustment for potential confounding variables, we found that HPV prevalence increased with higher lifetime number of sexual partners. CONCLUSION: These findings, along with those from the companion reports in this issue of the journal, support the sexual route of transmission of the virus.     

Effects of chronic U50,488H treatment on binding and mechanical responses of the rat hearts

The effects of chronic injection of U50,488H (trans-3,4-dichloro-N-[2-(1-pyrrolidinyl)cyclohexyl]benzeacetamidel++ +), a selective kappa opioid agonist, on the properties of the binding sites of tritiated U69593 [(5 alpha,7 alpha,8 beta)-(-)-N-methyl-N-(7-(1-pyrrolidinyl)-1-oxaspiro (4,5)dec-8-yl)benzeneacetamide], another selective kappa opioid agonist, and mechanical responses to U50,488H of the heart were studied. Rats received injection twice a day with U50,488H for 4 days. Binding studies on the crude membrane homogenates revealed that there was no change in maximum binding, but a significant increase in Kd after the treatment, indicating that the number of kappa binding sites remained unchanged whereas the affinity of the binding sites to kappa-agonist decreased. The study on the mechanical responses to U50,488H in the isolated perfused heart preparation showed that although the agonist at 10(-6) M caused MR2266 reversible reductions in heart rate and force of contraction as well as ventricular ectopic beat in the heart of rats in the control group, its effects were absent in the U50,488H-treated group, indicating the development of tolerance to the mechanical effects of U50,488H on the heart. The results indicate that the development of tolerance to the mechanical effects of a kappa-agonist after chronic treatment with the agonist was not accompanied by down-regulation, but only a slight and significant reduction in affinity of kappa binding sites in the rat heart.     

Evaluation of a proper controller performance for maximum-power point tracking of a stand-alone PV system

In this paper the implementation of a suggested stand-alone PV system, for maximum-power point tracking (MPPT), is carried out. Also, this paper presents a comparative study, through experimental work, between the conventional PI controller and the fuzzy logic controller (FLC) under different atmospheric conditions. The implemented system with both the PI controller and the FLC gives a good maximum-power operation of the PV array, but the tracking capability for different optimum operating points is better and faster for the case of using the FLC compared to the case of using the PI controller.     

TAG-1 can mediate homophilic binding, but neurite outgrowth on TAG-1 requires an L1-like molecule and beta 1 integrins

Subsets of axons in the embryonic nervous system transiently express the glycoprotein TAG-1, a member of the subfamily of immunoglobulin (Ig)-like proteins that contain both C2 class Ig and fibronectin type III domains. TAG-1 is attached to the cell surface by a glycosylphosphatidylinositol linkage and is secreted by neurons. In vitro studies have shown that substrate-bound TAG-1 promotes neurite outgrowth. We have examined the nature of axonal receptors that mediate the neurite-outgrowth promoting properties of TAG-1. Although TAG-1 can mediate homophilic binding, neurite outgrowth on a substrate of TAG-1 does not depend on the presence of TAG-1 on the axonal surface. Instead, neurite outgrowth on TAG-1 is inhibited by polyclonal antibodies directed against L1 and, independently, by polyclonal and monoclonal antibodies against beta 1-containing integrins. These results provide evidence that TAG-1 can interact with cell surfaces in both a homophilic and heterophilic manner and suggest that neurite extension on TAG-1 requires the function of both integrins and an L1-like molecule.