Seroepidemiological and molecular studies of human T cell lymphotropic virus type II, subtype b, in isolated groups of Mataco and Toba Indians of northern Argentina

We studied plasma samples from 2082 Mataco Indians living in 22 different communities in the western part of Formosa Province, northern Argentina. Samples were screened for HTLV-I/II antibodies by particle agglutination assay. All positive or borderline samples were then tested by an immunofluorescence assay (IFA) on C19 HTLV-II-producing cells. Western blot was used for confirmation of all IFA-positive plasma samples. The crude HTLV-II seroprevalence was 3.0% (62 of 2051), and 0.9% (5 of 588) in children less than 10 years old. The latter result suggests ongoing mother-to-child transmission, probably by breast feeding. There was a marked increase in HTLV-II seroprevalence with age (0.9%, 0-10 years; 1.6%, 11-20 years; 4.4%, 21-30 years; 3.4%, 31-40 years; 7.2%, 41-50 years; 5.7%, >50 years) in both male (p = 0.002) and female subjects (p = 0.00002). None of the 80 non-Indian inhabitants tested was HTLV-I/II seropositive. In a second study, among 105 Toba Indians from a village (Primavera) of the eastern part of this region, 23 were HTLV-II seropositive with a seroprevalence of 59% in those more than 40 years old. From seven of the Indians from Primavera, three others from neighboring regions (including two Tobas and one Pilaga), and one intravenous drug user (IVDU) from Rosario, DNA was extracted from peripheral blood mononuclear cells, and the gp21 transmembrane-encoding gene (590 bp) was amplified by PCR, cloned, and sequenced. LTR sequences were also obtained from the Pilaga, the IVDU, and one Toba. Molecular and phylogenetic analyses revealed that the Indians were all infected with closely related HTLV-II molecular strains belonging to the b subtype, while the IVDU was infected with an HTLV-II subtype a variant. Such data help to make a phylogenetic atlas of HTLV-II among Amerindian tribes and are crucial to gain new insights into the origin and modes of dissemination of this human retrovirus in the Americas.

Reduced capacitative calcium entry correlates with vesicle accumulation and apoptosis

A preneoplastic variant of Syrian hamster embryo cells, sup(+), exhibits decreased endoplasmic reticulum calcium levels and subsequently undergoes apoptosis in low serum conditions (Preston, G. A., Barrett, J. C., Biermann, J. A., and Murphy, E. (1997) Cancer Res. 57, 537-542). This decrease in endoplasmic reticulum calcium appears to be due, at least in part, to reduced capacitative calcium entry at the plasma membrane. Thus we investigated whether inhibition of capacitative calcium entry per se could reduce endoplasmic reticulum calcium and induce apoptosis of cells. We find that treatment with either SKF96365 (30-100 microM) or cell-impermeant 1,2-bis(o-amino-5-bromophenoxy)ethane-N,N,N', N'-tetraacetic acid (5-10 mM) is able to induce apoptosis of cells in conditions where apoptosis does not normally occur. Because previous work has implicated vesicular trafficking as a mechanism of regulating capacitative calcium entry, we investigated whether disruption of vesicular trafficking could lead to decreased capacitative calcium entry and subsequent apoptosis of cells. Coincident with low serum-induced apoptosis, we observed an accumulation of vesicles within the cell, suggesting deregulated vesicle trafficking. Treatment of cells with bafilomycin (30-100 nM), an inhibitor of the endosomal proton ATPase, produced an accumulation of vesicles, decreased capacitative entry, and induced apoptosis. These data suggest that deregulation of vesicular transport results in reduced capacitative calcium entry which in turn results in apoptosis.

A Triad of Research Roles: Experiential Learning in an Undergraduate Research Course

This article describes an innovative approach to teaching undergraduate research content directly involving students in a faculty research study, and a student research project undertaken in a nursing research course. Junior-level students participated as research subjects in a faculty study focusing on the health perceptions of baccalaureate nursing students, became data collectors in a related student project on the health perceptions of lay people, and became consumers of the research by analyzing the findings and clinical relevance of these studies. This strategy for teaching research assisted students to master undergraduate research content by participatory involvement in several distinct phases of the research process. The project generated considerable interest and served to foster positive attitudes toward nursing research while concurrently increasing students' comfort level with the total process.

Preverbal, Early Verbal Pediatric Pain Scale (PEPPS): development and early psychometric testing

The Pre-Verbal, Early Verbal Pediatric Pain Scale (PEPPS) is conceptualized to measure the established pain response in toddlers, a pediatric group void of pain assessment scales. It consists of seven categories, each with weighted indicators. Scores can range from 0 to 26. Using a blinded, cross-sectional design, 40 children, aged 12 to 24 months, were videotaped throughout their postoperative stay in the postanesthesia care unit. Vignettes were randomly selected and viewed by four experienced pediatric nurses. Results indicated that the PEPPS was easy to use and demonstrated acceptable inter-rater and intrarater reliability. Early evidence of construct validity was established by statistically significant differences in premedication and postmedication pain scores.

Isolation and characterization of two distinct forms of liver fatty acid binding protein from the rat

Liver fatty acid binding protein (L-FABP) appears to contain several different forms that may result from post-translational modification or bound ligand. To further assess this possibility, L-FABP was purified from rat liver homogenate and two putative isoforms separated using a sulfonyl column, a strong cation exchange resin. Fraction I eluted at 0.2 M NaCl, had a pI of 7.59, and following a final size exclusion step contained > 98% L-FABP. Fraction II eluted at 1.0 M NaCl, had a pI of 7.59, and following a final size exclusion step contained > 99% L-FABP. Both fractions contained approx. 0.15 moles of endogenous bound fatty acid per mole of protein, while L-FABP not subjected to the cation exchange step contained 0.75 moles of fatty acid per mole of protein. Fractions I and II had a greater proportion of saturated and monounsaturated fatty acids with a large reduction in polyunsaturated fatty acids compared to L-FABP not fractionated by cation exchange. Mass spectral analysis indicated the molecular mass of Fraction I was 14,315.02 +/- 0.35 Da and Fraction II was 14,315.86 +/- 0.34 Da. The peptide map for each fraction was determined by limited digestion of each fraction with either trypsin, Asp-N, or chymotrypsin to yield overlapping peptide fragments. Mass spectral analysis of these digests indicated the two proteins had identical amino acid fragments and that Cys69 was reduced and there were no Asn to Asp exchanges. Hence, these two forms of L-FABP were not isoforms and were not the result of differences in bound fatty acid. It is proposed that these two distinct forms of rat L-FABP were structural conformers based on two alternative folding pathways.

Overexpression of the cardiac Na+/Ca2+ exchanger increases susceptibility to ischemia/reperfusion injury in male, but not female, transgenic mice

Influx of Ca2+ into myocytes via Na+/Ca2+ exchange may be stimulated by the high levels of intracellular Na+ and the changes in membrane potential known to occur during ischemia/reperfusion. This increased influx could, in turn, lead to Ca2+ overload and injury. Overexpression of the cardiac Na+/Ca2+ exchanger therefore may increase susceptibility to ischemia/reperfusion injury. To test this hypothesis, the hearts of male and female transgenic mice, overexpressing the Na+/Ca2+ exchange protein, and hearts of their wild-type littermates, were perfused with Krebs-Henseleit buffer and subjected to 20 minutes of ischemia and 40 minutes of reperfusion. Preischemic left ventricular developed pressures and +dP/dtmax, as well as -dP/dtmin, were higher in the male transgenic hearts compared with wild-type, implying a role for Na+/Ca2+ exchange in the contraction, as well as the relaxation, phases of the cardiac beat. Postischemic function was lower in male transgenic than in male wild-type hearts (7+/-2% versus 32+/-6% of preischemic function), but there was no difference between female transgenic and female wild-type hearts, both at approximately 30% of preischemic function. To assess whether this male/female difference was due to female-specific hormones such as estrogen, the hearts of bilaterally ovariectomized and sham-operated transgenic females were subjected to the same protocol. The functional recoveries of ovariectomized female transgenic hearts were lower (17+/-3% of preischemic function) than those of wild-type and sham-operated transgenic females. The lower postischemic functional recovery in the male transgenic and female ovariectomized transgenic hearts correlated with lower recoveries of the energy metabolites, ATP and phosphocreatine, as measured by 31P nuclear magnetic resonance spectroscopy. Alternans were observed during reperfusion in male transgenic and female ovariectomized transgenic hearts only, consistent with intracellular Ca2+ overload. Western analyses showed that alterations in the expression of the Na+/Ca2+ exchange or L-type Ca2+ channel proteins were not responsible for the protection observed in the female transgenic hearts. In conclusion, in males, overexpression of the Na+/Ca2+ exchanger reduced postischemic recovery of both contractile function and energy metabolites, indicating that the Na+/Ca2+ exchanger may play a role in ischemia/reperfusion injury. From the studies of females, however, it appears that this exacerbation of ischemia/reperfusion injury by overexpression of the Na+/Ca2+ exchanger can be overcome partially by female-specific hormones such as estrogen.

Regulation of the Ca2+ gradient across the sarcoplasmic reticulum in perfused rabbit heart. A 19F nuclear magnetic resonance study

Myocardial contractility depends on Ca2+ release from and uptake into the sarcoplasmic reticulum (SR). The Ca2+ gradient between the SR matrix and the cytosol (SR Ca2+ gradient) is maintained by the SR Ca2+-ATPase using the free energy available from hydrolysis of ATP. The activity of the SR Ca2+-ATPase is not only dependent on the energy state of the cell but is also kinetically regulated by SR proteins such as phospholamban. To evaluate the importance of thermodynamic and kinetic regulation of the SR Ca2+ gradient, we examined the relationship between the energy available from ATP hydrolysis (DeltaGATP) and the energy required for maintenance of the SR Ca2+ gradient (DeltaGCa2+SR) during physiological and pathological manipulations that alter DeltaGATP and the phosphorylation state of phospholamban. We used our previously developed 19F nuclear magnetic resonance method to measure the ionized [Ca2+] in the SR of Langendorff-perfused rabbit hearts. We found that addition of either pyruvate or isoproterenol resulted in an increase in left ventricular developed pressure and an increase in [Ca2+]SR. Pyruvate increased DeltaGATP, and the increase in the SR Ca2+ gradient was matched to the increase in DeltaGATP; DeltaGATP increased from 58.3+/-0.5 to 60.4+/-1.0 kJ/mol (P<0.05), and DeltaGCa2+SR increased from 47.1+/-0.3 to 48.5+/-0.1 kJ/mol (P<0.05). In contrast, the increase in the SR Ca2+ gradient in the presence of isoproterenol occurred despite a decline in DeltaGATP from 58. 3+/-0.5 to 55.8+/-0.6 kJ/mol. Thus, the data indicate that the SR Ca2+ gradient can be increased by an increase in DeltaGATP, and that the positive inotropic effect of pyruvate can be explained by improved energy-linked SR Ca2+ handling, whereas the results with isoproterenol are consistent with removal of the kinetic limitation of phospholamban on the activity of the sarcoplasmic/endoplasmic reticulum Ca2+-ATPase, which allows the SR Ca2+ gradient to move closer to its thermodynamic limit. Ischemia decreases DeltaGATP, and this should also have an effect on SR Ca2+ handling. During 30 minutes of ischemia, DeltaGATP decreased by 12 kJ/mol, but the decrease in DeltaGCa2+SR was 16 kJ/mol, greater than would be predicted by the fall in DeltaGATP and consistent with increased SR Ca2+ release and increased SR Ca2+ cycling. Because ischemic preconditioning is reported to decrease SR Ca2+ cycling during a subsequent sustained period of ischemia, we examined whether ischemic preconditioning affects the relationship between the fall in DeltaGATP and the fall in DeltaGCa2+SR during ischemia. We found that preconditioning attenuated the fall in DeltaGCa2+SR during ischemia; the fall in DeltaGCa2+SR was of comparable magnitude to the fall in DeltaGATP, and this was associated with a significant improvement in functional recovery during reperfusion. The data suggest that there is both thermodynamic regulation of the SR Ca2+ gradient by DeltaGATP and kinetic regulation, which can alter the relationship between DeltaGATP and DeltaGCa2+SR.

The dose-effect relationships between torture and psychiatric symptoms in Vietnamese ex-political detainees and a comparison group

The purpose of this study was to determine in Vietnamese ex-political detainees newly arrived into the United States a) the prevalence of torture and psychiatric symptoms and b) the dose-effect relationships between cumulative torture experience and the psychiatric symptoms of posttraumatic stress disorder (PTSD) and major depression. The study population included Vietnamese ex-political detainees (N = 51) and a comparison group (N = 22). All respondents received culturally validated instruments with known psychometric properties including Vietnamese versions of the Hopkins Symptom Checklist-25 and the Harvard Trauma Questionnaire. The ex-political detainees, in contrast to the comparison group, had experienced more torture events (12.2 SD = 4.2 vs. 2.6 SD = 3.1) and had higher rates of PTSD (90% vs. 79%) and depression (49% vs. 15%). Dose-effect relationships between cumulative torture experience and psychiatric symptoms were positive with the PTSD subcategory of "increased arousal" revealing the strongest association. These findings provide evidence that torture is associated with psychiatric morbidity in Vietnamese refugees. The demonstration of significant dose-effect responses supports the hypothesis that torture is a major risk factor in the etiology of major depression and PTSD. The generalizability of these results to other torture survivor groups is unknown. The interaction between torture and other pre- and post-migration risk factors over time in different cultural settings still needs to be examined.

Characterization of a novel subset of CD8(+) T cells that expands in patients receiving interleukin-12

IL-12 has significant antitumor activity in mice that may be mediated by CD8(+) T cells. We show in this report that repeated subcutaneous injections of IL-12 in patients with cancer resulted in the selective expansion of a subset of peripheral blood CD8(+) T cells. This T cell subset expressed high levels of CD18 and upregulated IL-12 receptor expression after IL-12 treatment in vivo. In normal subjects, these CD3(+)CD8(+)CD18(bright) T cells expressed IL-12 and IL-2 receptors and adhesion/costimulatory molecules to a greater degree than other CD8(+) and CD4(+) T cells. They appeared morphologically as large granular lymphocytes, although they did not express NK cell markers such as CD56. In addition, CD8(+)CD18(bright) T cells were almost exclusively T cell receptor (TCR) alphabeta+, and exhibited a TCR Vbeta repertoire that was strikingly oligoclonal, whereas the Vbeta repertoire of CD18(dim) T cells was polyclonal. Although CD8+CD18(bright) T cells demonstrated little functional responsiveness to IL-12 or IL-2 alone in vitro, they responded to the combination of IL-12+IL-2 with strong IFN-gamma production and proliferation and enhanced non-MHC-restricted cytolytic activity. In contrast, CD18(dim) T cells were not activated by IL-12 or IL-2, alone or in combination. These findings demonstrate that CD8+CD18(bright) T cells are a unique population of peripheral blood lymphocytes with features of both memory and effector cells that are capable of TCR-independent activation through combined stimulation with IL-12+IL-2. As this activation results in IFN-gamma production and enhanced cytolytic activity, these T cells may play a role in innate as well as acquired immunity to tumors and infectious pathogens. Additional studies will be necessary to determine whether CD8+CD18(bright) T cells mediate the antitumor effect of IL-12 or IL-2 administered to cancer patients, and if so, whether maximal activation of these T cells with the combination of IL-12+IL-2 in vivo can augment the clinical effectiveness of these cytokines.

Sterol carrier protein-2 expression increases NBD-stearate uptake and cytoplasmic diffusion in L cells

The effects of sterol carrier protein-2 (SCP-2) expression on fatty acid uptake and cytoplasmic diffusion were determined using L cell fibroblasts transfected with cDNA encoding either the 15- or 13. 2-kDa form of SCP-2. Cis-parinarate and 12-N-methyl-(7-nitrobenz-2-oxa-1,3-diazol)aminostearate (NBD-stearate) were used as nonesterifiable fluorescent fatty acid probes. NBD-stearate and cis-parinarate uptake was rapid and saturable. In 15-kDa SCP-2-expressing cells, the extent of NBD-stearate and cis-parinarate uptake was increased 1.4- and 1. 2-fold, respectively, compared with control. In the 13.2-kDa SCP-2-expressing cells, the extent of NBD-stearate and cis-parinarate uptake was increased 1.3- and 1.1-fold, respectively, compared with control cells. NBD-stearate cytoplasmic diffusion was increased 1.5-fold in 15-kDa SCP-2-expressing cells, but not in 13. 2-kDa SCP-2-expressing cells, compared with control cells. After incubation with NBD-stearate for 30 min at 37 degrees C, fluorescence imaging indicated that NBD-stearate was localized primarily in lipid droplets in all cell lines. These results suggest that SCP-2 may be involved not only in fatty acid uptake but also in intracellular fatty acid trafficking.

L-FABP and I-FABP expression increase NBD-stearate uptake and cytoplasmic diffusion in L cells

The effects of intestinal and liver fatty acid binding protein (I- and L-FABP, respectively) expression on single-cell fatty acid uptake, internalization, and cytoplasmic diffusion were determined in transfected L cell fibroblasts. These parameters were measured using the nonesterifiable fluorescent fatty acid probe 12-N-methyl-(7-nitrobenz-2-oxa-1,3-diazol)aminostearate (NBD-stearate) and fluorescence digital imaging. In single-cell fluorescence imaging experiments, L-FABP-expressing cells, but not I-FABP-expressing cells, increased NBD-stearate uptake 1.7-fold compared with control cells. Both I- and L-FABP increased the cytoplasmic diffusion rate of the internalized NBD-stearate 2.6- and 1.9-fold, respectively, compared with control cells. However, increased NBD-stearate lateral membrane mobility was observed only in L-FABP-expressing cells. After incubation of the cells with 4 microM NBD-stearate at 37 degrees C for 30 min, fluorescence deconvolution imaging indicated that NBD-stearate was localized primarily into lipid droplets in all cell lines. The differential effect of these proteins on fatty acid uptake and intracellular trafficking in single cells illustrates a possible difference in the physiological function of I- and L-FABP in intact cells.

Catching goldfish: quality in qualitative research

This paper reviews the contribution of qualitative methods to health services research (HSR) and discusses some of the issues involved in recognizing quality in such work. The place of qualitative work is first defined by reference to Archie Cochrane's agenda for HSR and the limitations of the recent focus on randomized trials as the standard method. Health care practice involves large elements of improvisation which cannot be captured by evidence-based approaches. Qualitative methods offer ways of understanding this improvisation and of identifying more efficient and effective practices, as well as considering the traditional topics of equity and humanity. The methodological procedures of qualitative work reflect a long-established inductive tradition in scientific practice. The logic of grounded theory provides a contemporary specification. In its application, it is quite different from the methodological anarchy of postmodernism. The use of qualitative research and the theoretically stated generalizations which arise from it inform reflective work by health service managers, planners and clinicians.

Reducing the risk of sudden infant death syndrome: a review of the scientific literature

In March 1997 a multidisciplinary forum was convened by the National SIDS Council of Australia to review recent evidence concerning risk factors of sudden infant death syndrome (SIDS) and to revise and refine the current guidelines for reducing the risk of SIDS. The forum provided an assessment of the evidence for recommendations to reduce the risk of SIDS using an evidence-based process. Strong evidence has now accumulated that the intervention campaigns to reduce prone sleeping during infancy have been followed by SIDS rate declines. Recent data indicate that the supine position is not associated with an increase in significant morbidity outcomes and provides greater protection for SIDS than the side position, which may be unstable. Covering of the baby's head by bedding is strongly related to SIDS. The infant's sleeping environment should be carefully set up to ensure that the baby's head, including the face, cannot be obstructed during sleep. Parental smoking is strongly associated with SIDS. Structural supportive interventions for parental smoking cessation are required. Bedsharing increases the risk of SIDS amongst smokers and the data are currently not sufficient to provide complete reassurance to nonsmoking parents that bedsharing is safe. Infants should be maintained in a comfortable temperature zone. The evidence for a protective effect of breast-feeding is conflicting, so breast-feeding cannot be promoted strongly as reducing the risk of SIDS. Immunisation has not been associated with SIDS. Parents and carers should be aware of the current guidelines. Health professionals should also be aware of the evidence on which the current recommendations are based. Effective health education programmes should lead to a further decline in SIDS mortality in Australia.

Differential influence of rat liver fatty acid binding protein isoforms on phospholipid fatty acid composition: phosphatidic acid biosynthesis and phospholipid fatty acid remodeling

The ability of two rat liver fatty acid binding protein (L-FABP) isoforms to influence microsomal phosphatidic acid biosynthesis, a key intermediate in glycerolipid formation, and phospholipid fatty acid remodeling was examined in vitro. Isoform I enhanced microsomal incorporation of [1-14C]-oleoyl-CoA into phosphatidic acid 7-fold while isoform II had no effect relative to basal. In contrast, isoform II enhanced microsomal incorporation of [1-14C]-palmitoyl-CoA into phosphatidic acid 4-fold while isoform I had no effect. These results suggest that each L-FABP isoform selectively utilized different acyl-CoAs for glycerol-3-phosphate esterification. Both isoforms stimulated phosphatidic acid formation by increasing glycerol-3-phosphate acyltransferase activity, not by increasing lysophosphatidic acid acyltransferase activity. Furthermore, the effects of L-FABP on phosphatidic acid biosynthesis could not be correlated with protection from acyl-CoA hydrolysis. L-FABP isoforms also influenced phospholipid fatty acid remodeling in a phospholipid-dependent manner. Isoform I preferentially enhanced oleate and palmitate esterification into phosphatidylethanol-amine, while isoform II stimulated esterification into phosphatidylcholine, phosphatidylserine and sphingomyelin. Taken together, these data demonstrated a unique role of each L-FABP isoform in modulating microsomally derived phospholipid fatty acid composition. (c) 1998 Elsevier Science B.V.

The leptin receptor mediates apparent autocrine regulation of leptin gene expression

The possibility that the leptin receptor (LEPR) mediates autocrine regulation of leptin expression in adipose tissue was examined in 10-day-old Zucker rat pups with different copy numbers of the leptin receptor mutation (Lepr(fa)). Plasma leptin concentrations and adipose tissue mRNA levels for leptin were related to copy number of the mutation (fa/fa > fa/+ > +/+). These relationships were independent of plasma insulin concentration. Reduced copy number for the functional leptin receptor apparently results in a diminished negative feedback signal to the leptin gene in adipose tissue. Thus, leptin appears to close a short regulatory loop controlling its own synthesis in adipose tissue.

Effects of weight change on plasma leptin concentrations and energy expenditure

Circulating concentrations of leptin are closely correlated with body fat mass, and may thus constitute an afferent limb of a system regulating body fatness, with efferent limbs that affect energy expenditure and food intake. We studied 50 subjects (27 males, 23 premenopausal females; 31 never-obese, 19 obese) at usual body weight during active weight loss or weight gain and during the maintenance of body weights 10% above usual (WT + 10%) and 10% and/or 20% below usual body weight (Wt -10% and Wt -20%) to test the hypotheses that the dynamic process of weight change and the maintenance of an altered body weight are associated with significant changes in circulating concentrations of leptin and/or the relationship between fat mass and leptin, and such changes in the plasma concentration of leptin are related to changes in energy expenditure at altered body weight. Subjects were admitted to the Rockefeller University Hospital, and energy metabolism (24-h energy expenditure, resting energy expenditure, thermic effect of feeding, and nonresting energy expenditure) and circulating concentrations of leptin and insulin were examined at various weight plateaus (usual body weight, 10% above usual body weight, 10% below usual body weight, and 20% below usual body weight). Plasma leptin was also measured in some subjects during dynamic periods of weight gain or loss. Though both plasma leptin concentrations and fat mass were significantly correlated with resting energy expenditure, only the correlation of fat mass and energy expenditure remained significant in a multiple stepwise linear regression analysis. Neither absolute nor relative changes in plasma leptin between weight plateaus were significantly correlated with any of the observed changes in energy expenditure. Plasma leptin concentrations were significantly lower during weight loss than during weight maintenance at the same body composition. Plasma leptin concentrations, normalized to fat mass, were significantly lower during the maintenance of a reduced body weight in females and higher during the maintenance of an elevated body weight in males than in the same subjects at usual body weight. At all weight plateaus, plasma leptin concentrations normalized to fat mass were significantly higher in females than in males, but gender was not a significant covariate of the relationship between leptin and energy expenditure. Postabsorptive serum concentrations of insulin was a significant covariate of plasma leptin concentration in males, but not females, at Wt initial and Wt + 10%. Although plasma leptin is significantly reduced during dynamic weight loss compared with static weight maintenance at the same body weight, the lack of correlation between changes in plasma leptin and changes in energy expenditure between weight plateaus suggests that leptin is not the primary signal that mediates the changes of energy expenditure that accompany the maintenance of an altered body weight in humans.

Decreased intracellular pH is not due to increased H+ extrusion in preconditioned rat hearts

Ischemic preconditioning reduces intracellular acidification during a subsequent, prolonged period of ischemia. This may reflect decreased anaerobic glycolysis or increased H+ efflux. To distinguish between these hypotheses, we monitored intracellular and extracellular pH during a sustained period of ischemia to determine whether the preconditioned hearts had increased H+ efflux compared with nonpreconditioned hearts. At the end of 20 min of ischemia, intracellular pH in nonpreconditioned hearts was 5.90 +/- 0.08 and extracellular pH was 5.51 +/- 0.21, whereas in preconditioned hearts, intracellular pH was 6.50 +/- 0.06 and extracellular pH was 6.62 +/- 0.06. To investigate whether an Na+/H+ exchange inhibitor would alter the reduced acidification during ischemia, we preconditioned hearts with and without dimethylamiloride (DMA). Intracellular pH during ischemia was similar in preconditioned hearts with and without DMA treatment (pH 6.42 +/- 0.02 vs. 6.45 +/- 0.03, respectively). These data do not support the hypothesis that enhanced proton efflux is responsible for the more alkaline intracellular pH during sustained ischemia in preconditioned hearts.

Effects of maturation on the phospholipid and phospholipid fatty acid compositions in primary rat cortical astrocyte cell cultures

Phospholipid and phospholipid fatty acid compositional changes were studied in rat cortical astrocytes during dibutyryl cyclic adenosine monophosphate (dBcAMP, 0.25 mM) treatment starting after 14 days in culture (DIC). After 15 DIC, ethanolamine- and choline glycerophospholipid levels were increased 1.2- and 1.3-fold, respectively in treated compared to control cells. However, after 21 and 28 DIC, these levels were not significantly different between groups. Both groups had an increase in phosphatidylserine levels with increasing time in culture. Similarly, ethanolamine plasmalogen levels were transiently elevated after 21 DIC, but returned to previous levels after 28 DIC. The phospholipid fatty acid compositions for the acid stable and labile ethanolamine- and choline glycerophospholipids indicated that in dBcAMP treated cells, 20:4 n-6 and 22:6 n-3 proportions were elevated with increasing time in culture relative to control cells. As 20:4 n-6 proportions increased, there was a concomitant decrease in 20:3 n-9 proportions, suggesting an up regulation of n-6 series elongation and desaturation. In contrast, in control cells, the 20:4 n-6 proportions decreased with a corresponding increase in the 20:3 n-9 proportions. Thus, in treated cells, the cellular phospholipid fatty acid composition was dramatically different than control cells, suggesting that dBcAMP treatment may act to increase fatty acid elongation and desaturation.

IGIF does not drive Th1 development but synergizes with IL-12 for interferon-gamma production and activates IRAK and NFkappaB

In these studies, IFN gamma-inducing factor (IGIF), unlike IL-12, did not drive Th1 development in BALB/c or C57BL/6 mice, but like IL-1alpha, potentiated IL-12-driven Th1 development in BALB/c mice. IGIF and IL-12 synergized for IFN gamma production from Th1 cells. Unlike IL-1alpha, IGIF had no effect on Th2 cells. IGIF signaled through IRAK, IL-1 receptor-associated kinase, to induce nuclear translocation of p65/p50 NFkappaB in Th1 cells. IL-1alpha had no effect on proliferation, cytokine production, or NFkappaB activation in Th1 cells but activated NFkappaB and proliferation in Th2 cells. Thus, Th1 and Th2 cells may differ in responsiveness and receptor expression for IL-1 family molecules. IGIF and IL-1alpha may differentially amplify Th1 and Th2 effector responses, respectively.