Immunological studies with different classes of mutants affected at the adenosine kinase locus in CHO cells

Adenosine kinase (AK) from CHO cells has been purified to homogeneity and specific antibodies to it have been raised in rabbits. Using this antibody, the presence of a specific cross-reacting protein (CRP) in cell extracts of different classes of mutants resistant to purine nucleoside analogs which are affected in AK has been investigated by the immunoblotting technique. Results of our studies show that 31 of the 32 independently selected class A AK^– mutants (obtained at high frequency in presence of adenosine analogs toyocamycin, tubercidin, 6-methylmercaptopurine riboside, or pyrazofurin and containing no measurable activity of AK in cell extracts) contained similar amounts of a specific CRP as seen in the parental AK⁺ cells. The CRP in the parental and different mutant cell lines has the same relative molecular mass as purified AK. Similar results were obtained with two mutants each of the class B and C type (selected in presence of C-nucleosides formycin A and formycin B), which are also affected in AK but show novel properties. The presence of equivalent amounts of the CRP in the vast majority of the class A mutants strongly indicates that the high frequency of those mutants in CHO cells is not a result of an epigenetic or deletion type of event, but that such mutants may contain missense types of mutations at a presumed mutational hot spot within the structural gene for adenosine kinase.     

Viral load responses to HAART is an independent predictor of a new AIDS event in late stage HIV infected patients: prospective cohort study

Background  

A sizeable number of HIV-infected patients receiving HAART do not maintain prolonged virologic suppression. We evaluated long-term HIV viral load (VL) responses to HAART as a risk factor for AIDS events (AE) that is independent of CD4 responses.     

Transfer of zona-free embryos improves outcome in poor prognosis patients: a prospective randomized controlled study

Assisted zona hatching (AZH) has been used in IVF programmes for several years. Recently one group has reported successful pregnancies after transfer of zona-free blastocysts. The aim of our study was to evaluate outcomes after transfer of zona-free day 3 embryos. Two groups of women undergoing intracytoplasmic sperm injection (ICSI) were included in the study. Group A consisted of 52 women under the age of 40 years undergoing their first ICSI attempt. They were alternately randomized to receive zona-free embryos (27 women) and zona-intact embryos (25 women). The second group (group B) included 71 women with a poor prognosis, as defined by age 40 years or more, and/or at least two previous failed IVF/ICSI attempts. They were randomized in a 3:4 ratio (30 zona-free, 41 zona-intact). Acid Tyrode's solution was used to remove the zona pellucida before embryo transfer on day 3 after oocyte collection. The pregnancy rate in group A was not significantly improved when the zona pellucida was removed. However, in the poor prognosis group B, zona removal resulted in a significantly higher pregnancy rate when compared with controls (23 versus 7.3%). We conclude that complete removal of the zona pellucida can improve pregnancy rates in women with poor IVF/ICSI prognosis.     

Detection by PCR and isolation assays of the anaerobic intestinal spirochete Brachyspira aalborgi from the feces of captive nonhuman primates

The purpose of this study was to investigate the presence of the anaerobic intestinal spirochetes Brachyspira aalborgi and Brachyspira pilosicoli in the feces of captive nonhuman primates (n = 35) from 19 species housed at the Zoological Gardens, Perth, Western Australia. Both spirochete species are known to infect human beings. DNA was extracted from freshly collected feces with a commercially available QIAamp DNA stool minikit and subjected to PCR protocols amplifying portions of the 16S rRNA genes of the two spirochete species. The feces were also subjected to selective culture for the spirochetes. Subsequently, feces from 62 other captive animals or birds representing 39 species at the zoo were examined by PCR to determine whether they were reservoirs of infection. Six fecal samples from individuals from four primate species (two vervet monkeys, two Tonkean macaques, one Japanese macaque, and one hamadryas baboon) tested positive in the B. aalborgi PCR. B. aalborgi was not detected by PCR in any of the other animal or bird species tested, and B. pilosicoli was not detected in the primates or any of the other animals or birds. B. aalborgi was isolated from both PCR-positive vervet monkeys. This is the first time that B. aalborgi has been isolated from nonhuman primates and the first time that it has been isolated from the feces of any species.     

Novel Marine Compounds: Anticancer or Genotoxic?

In the past several decades, marine organisms have generouslygifted to the pharmaceutical industries numerous naturallybioactive compounds with antiviral, antibacterial,antimalarial, anti-inflammatory, antioxidant, and anticancerpotentials. But till date only few anticancer drugs (cytarabine,vidarabine) have been commercially developed from marinecompounds while several others are currently in differentclinical trials. Majority of these compounds were tested in thetumor xenograft models, however, lack of anticancer potentialdata in the chemical- and/or oncogene-induced pre-initiationanimal carcinogenesis models might have cost some of the marineanticancer compounds an early exit from the clinical trials. Thisreview critically discusses importance of preclinicalevaluation, failure of human clinical trials with certainpotential anticancer agents, the screening tests used, and choiceof biomarkers.     

A synthetic nanofibrillar matrix promotes in vivo-like organization and morphogenesis for cells in culture

The purpose of this study was to design a synthetic nanofibrillar matrix that more accurately models the porosity and fibrillar geometry of cell attachment surfaces in tissues. The synthetic nanofibrillar matrices are composed of nanofibers prepared by electrospinning a polymer solution of polyamide onto glass coverslips. Scanning electron and atomic force microscopy showed that the nanofibers were organized into fibrillar networks reminiscent of the architecture of basement membrane, a structurally compact form of the extracellular matrix (ECM). NIH 3T3 fibroblasts and normal rat kidney (NRK) cells, when grown on nanofibers in the presence of serum, displayed the morphology and characteristics of their counterparts in vivo. Breast epithelial cells underwent morphogenesis to form multicellular spheroids containing lumens. Hence the synthetic nanofibrillar matrix described herein provides a physically and chemically stable three-dimensional surface for ex vivo growth of cells. Nanofiber-based synthetic matrices could have considerable value for applications in tissue engineering, cell-based therapies, and studies of cell/tissue function and pathology.     

Perceptions of first and third year medical students on self-study and reporting processes of problem-based learning

Background  

The objective of this study is to investigate the perceptions of first and third year medical students on self-study and reporting processes of Problem-based Learning (PBL) sessions and their usage of learning resources.     

Granulomatous Pneumocystis carinii pneumonia complicating hematopoietic cell transplantation

Pneumocystis carinii pneunonia (PCP) is associated with a wide spectrum of clinical and histopathological presentations. While granulomatous PCP uncommonly occurs in AIDS patients, it is extremely rare in other non-AIDS immunocompromised patients. We identified three patients who developed granulomatous PCP after bone marrow or blood stem cell transplantation. In all cases, fiberoptic bronchoscopy with bronchoalveolar lavage was non-diagnostic, and an open lung biopsy was required for diagnosis. All patients were successfully treated with trimethoprim-sulfamethoxazole. The histological appearance varied from an ill-defined granulomatous pneumonia to well-formed necrotizing granulomas. The typical intraalveolar eosinophilic frothy exudate was absent. Often sparsely distributed, the organisms were detected by GMS and immunohistochemical stains for P. carinii. No other pathogens were identified by additional histochemical stains or by microbiological cultures. Awareness of this unusual granulomatous tissue response to P. carinii and initiation of specific treatment can lead to successful resolution of this potentially lethal infection.