Tolerance of Low Intracellular pH During Hypercapnia by Rat Cortical Brain Slices: A 31P/1H NMR Study

Metabolic tolerance of low intracellular pH (pH(i)) was studied in well-oxygenated, perfused, neonatal, rat cerebrocortical brain slices (350 microns thick) by inducing severe hypercapnia. In each of 17 separate experiments 80 brain slices (approximately 3.2 g wet weight) were suspended in an NMR tube, perfused with artificial CSF (ACSF), and studied at 4.7 T with 31P and 1H NMR spectroscopy. Spectra obtained every 5 min monitored relative concentrations of lactate or high-energy phosphate metabolites, from which pH(i) and extracellular pH were determined. Unperturbed slice preparations were metabolically stable for > 10 h, with no significant changes occurring in pHi, ATP, phosphocreatine (PCr), inorganic phosphate, or lactate. Different levels of hypercapnia were produced by sequentially perfusing slices with the following different ACSF batches, each having previously been equilibrated with a specific mixture of CO2 in oxygen: (a) 10% CO2, 15 min of perfusion; (b) 30% CO2, 15 min of perfusion; (c) 50% CO2, 15 min of perfusion; (d) 70% CO2, 30 min of perfusion; (e) 50% CO2, 15 min of perfusion; (f) 30% CO2, 15 min of perfusion; and (g) 10% CO2, 15 min of perfusion. At the completion of this protocol slices were again perfused with fresh ACSF that was equilibrated with a 95% O2/5% CO2 gas mixture. In each of five separate 1H and 31P experiments, brain slices were recovered within 2 h after termination of exposure to high CO2. The pHi was determined from measurements of the chemical shift difference between phosphoethanolamine and PCr, using a calibration curve obtained for our preparation.(ABSTRACT TRUNCATED AT 250 WORDS)     

A multiparametric advection-diffusion reduced-order model for molecular transport in scaffolds for osteoinduction

Biomechanics and Modeling in Mechanobiology - Scaffolds are microporous biocompatible structures that serve as material support for cells to proliferate, differentiate and form functional tissue....     

Reversible decreases in ATP and PCr concentrations in anoxic turtle brain

A hallmark of anoxia tolerance in western painted turtles is relative constancy of tissue adenylate concentrations during periods of oxygen limitation. During anoxia heart and brain intracellular compartments become more acidic and cellular energy demands are met by anaerobic glycolysis. Because changes in adenylates and pH during anoxic stress could represent important signals triggering metabolic and ion channel down-regulation we measured PCr, ATP and intracellular pH in turtle brain sheets throughout a 3-h anoxic-re-oxygenation transition with ³¹P NMR. Within 30 min of anoxia, PCr levels decrease 40% and remain at this level during anoxia. A different profile is observed for ATP, with a statistically significant decrease of 23% occurring gradually during 110 min of anoxic perfusion. Intracellular pH decreases significantly with the onset of anoxia, from 7.2 to 6.6 within 50 min. Upon re-oxygenation PCr, ATP and intracellular pH recover to pre-anoxic levels within 60 min. This is the first demonstration of a sustained reversible decrease in ATP levels with anoxia in turtle brain. The observed changes in pH and adenylates, and a probable concomitant increase in adenosine, may represent important metabolic signals during anoxia.     

Prognostic value of a CCR5 defective allele in pediatric HIV-1 infection

BACKGROUND: A deletion of 32 base pairs in the CCR5 gene (delta32 CCR5) has been linked to resistance to HIV-1 infection in exposed adults and to the delay of disease progression in infected adults. MATERIALS AND METHODS: To determine the role of delta32 CCR5 in disease progression of HIV-1 infected children born to seropositive mothers, we studied a polymerase chain reaction in 301 HIV-1 infected, 262 HIV-1 exposed-uninfected and 47 HIV-1 unexposed-uninfected children of Spanish and Italian origin. Infected children were further divided into two groups according to their rate of HIV-1 disease progression: rapid progressors who developed severe clinical and/or immunological conditions within the second year of life, and delayed progressors with any other evolution of disease. Among the latter were the long-term, non-progressors (LTNP) who presented with mild or no symptoms of HIV-1 infection above 8 years of age. Viral phenotype was studied for 45 delayed progressors. RESULTS: No correlation was found between delta32 CCR5 and mother-to-child transmission of HIV-1. However, the frequency of the deletion was substantially higher in LTNP, compared with delayed (p = 0.019) and rapid progressors (p = 0.0003). In children carrying the delta32 CCRS mutation, the presence of MT-2 tropic virus isolate was associated with a severe immune suppression (p = 0.028); whereas, the presence of MT-2 negative viruses correlated with LTNP (p = 0.010). CONCLUSIONS: Given the rapidity and simplicity of the assay, the delta32 CCR5 mutation may be a useful predictive marker to identify children with delayed disease progression who, consequently, may not require immediate antiretroviral treatment.     

Compatibility Between Pasteuria penetrans Isolates and Meloidogyne Populations from Spain

Several populations of Pasteuria isolated from fields in Spain were compared with other Pasteuria populations, held in collections at the Institute de Recerca i Tecnologia, Agroalimentaries (IRTA), Cabrils or IACR-Rothamsted, for their ability to adhere to and infect root-knot nematodes ( Meloidogyne spp.) grown on host plants differing in their susceptibility to root-knot nematodes. The results showed a high level of variation in both the ability of a population of Pasteuria to adhere to a particular population of nematode and vice versa. In particular the isolates of Pasteuria originating from M. hapla retained a high level of specificity for the species from which they originated. The infection of the nematodes by the bacteria was generally low, even when nematodes were encumbered with relatively high levels of spores. It is suggested that prolonged storage (6 years) may reduce the ability of spores to infect nematodes independently of adhesion.     

Defective self-reactive antibody repertoire of serum IgM in patients with hyper-IgM syndrome

We have analyzed the self-reactive repertoires of IgM and IgG Abs in the serum of 19 patients with hyper-IgM syndrome (HIM) by means of a quantitative immunoblotting technique that allows for a quantitative comparison of Ab repertoires in health and disease by multiparametric statistical analysis. Normal tissue extracts of liver, lung, stomach, and kidney were used as sources of self Ags. Extracts of Pseudomonas aeruginosa and Staphylococcus epidermidis were used as sources of nonself Ags. We demonstrate a significant bias in repertoires of reactivities of IgM of patients with HIM with self Ags. Ab repertoires of IgM toward nonself Ags did not differ, however, between patients and controls. No difference was found between IgM repertoires of untreated patients and those of patients receiving substitutive treatment with i.v. IgG. IgG in the serum of HIM patients lacked reactivity with self Ags, although it exhibited a pattern of reactivity with nonself Ags that was similar to that of IgG of healthy controls. The data demonstrate that functional CD40-CD40 ligand interactions are essential for the selection of natural self-reactive B cell repertoires.     

X-linked immunodeficiency with hyperimmunoglobulinemia M appears to be linked to the DXS42 restriction fragment length polymorphism locus

Summary The gene involved in X-linked immunodeficiency with hyperimmunoglobulinemia M (XHM) was localized by the use of nine restriction fragment length polymorphic (RFLP) markers covering the entire X chromosome. Multipoint linkage analysis of RFLP data obtained in a three generation XHM pedigree indicates the Xq24-q27 area around the DXS42 RFLP locus as the most likely localization of the XHM locus.