Magnesium decreases inflammatory cytokine production: a novel innate immunomodulatory mechanism.

MgSO(4) exposure before preterm birth is neuroprotective, reducing the risk of cerebral palsy and major motor dysfunction. Neonatal inflammatory cytokine levels correlate with neurologic outcome, leading us to assess the effect of MgSO(4) on cytokine production in humans. We found reduced maternal TNF-α and IL-6 production following in vivo MgSO(4) treatment. Short-term exposure to a clinically effective MgSO(4) concentration in vitro substantially reduced the frequency of neonatal monocytes producing TNF-α and IL-6 under constitutive and TLR-stimulated conditions, decreasing cytokine gene and protein expression, without influencing cell viability or phagocytic function. In summary, MgSO(4) reduced cytokine production in intrapartum women, term and preterm neonates, demonstrating effectiveness in those at risk for inflammation-associated adverse perinatal outcomes. By probing the mechanism of decreased cytokine production, we found that the immunomodulatory effect was mediated by magnesium and not the sulfate moiety, and it was reversible. Cellular magnesium content increased rapidly upon MgSO(4) exposure, and reduced cytokine production occurred following stimulation with different TLR ligands as well as when magnesium was added after TLR stimulation, strongly suggesting that magnesium acts intracellularly. Magnesium increased basal IĸBα levels, and upon TLR stimulation was associated with reduced NF-κB activation and nuclear localization. These findings establish a new paradigm for innate immunoregulation, whereby magnesium plays a critical regulatory role in NF-κB activation, cytokine production, and disease pathogenesis.

Lower Switch Rate in Depressed Patients With Bipolar II Than Bipolar I Disorder Treated Adjunctively With Second-Generation Antidepressants.

Objectives: The authors compared the switch rate into hypomania/mania in depressed patients treated with second-generation antidepressants who had either bipolar I or bipolar II disorder. Methods: In a 10-week trial, 184 outpatients with bipolar depression (134 with bipolar I disorder, 48 with bipolar II disorder, two with bipolar disorder not otherwise specified) were treated with one of three antidepressants as an adjunct to mood stabilizers. The patients' switch rates were assessed. Switch was defined as a Young Mania Rating Scale (YMRS) score >13 or a Clinical Global Impression (CGI) mania score ≥3 (mildly ill). Results: Depressed subjects with bipolar II disorder had a significantly lower acute switch rate into hypomania/mania when either YMRS or CGI criteria were used to define switch. Conclusions: These data suggest that depressed patients with bipolar II disorder are less vulnerable than those with bipolar I disorder to switch into hypomania/mania when treated with an antidepressant adjunctive to a mood stabilizer.Reprinted from Am J Psychiatry 2006; 163:313-315, with permission from American Psychiatric Association Publishing. Copyright © 2006.

Single mutations in HIV integrase confer high-level resistance to raltegravir in primary human macrophages.

CD4(+) T cells and macrophages are the primary target cells for HIV in vivo, and antiretroviral drugs can vary in their ability to inhibit the infection of these different cell types. Resistance pathways to the HIV integrase inhibitor raltegravir have previously been investigated in T cells. Primary raltegravir resistance mutations, most often at integrase amino acid position 148 or 155, afford some resistance to the drug. The acquisition of pathway-specific secondary mutations then provides higher-level resistance to viruses infecting T cells. We show here that during macrophage infection, the presence of a single primary raltegravir resistance mutation (Q148H, Q148R, N155H, or N155S) is sufficient to provide resistance to raltegravir comparable to that seen in viruses expressing both primary and secondary mutations in costimulated CD4(+) T cells. These data implicate macrophages as a potential in vivo reservoir that may facilitate the development of resistance to raltegravir. Notably, the newer integrase inhibitor MK-2048 effectively suppressed the infection of all raltegravir-resistant viruses in both T cells and macrophages, indicating that more recently developed integrase inhibitors are capable of inhibiting infection in both major HIV cellular reservoirs, even in patients harboring raltegravir-resistant viruses.

Baseline immune phenotypes and CD4+ T lymphocyte responses to antiretroviral therapy in younger versus older HIV-infected individuals.

OBJECTIVE: The purpose of the study was to determine associations between pre-antiretroviral therapy (ART) senescent CD8+ T lymphocytes and naïve versus non-naive CD8+ and CD4+ T lymphocyte subpopulations and CD4+ responses after initiation of ART in younger versus older individuals. METHODS: Retrospective analysis of 100 subjects with pre-ART cryopreserved peripheral blood mononuclear cells samples was performed with flow cytometry. Subjects were divided into four groups by age (30-50 years or > 50 years) and 96-week CD4+ response (<100 or >200 cells/mm(3)). All subjects had 96-week viral suppression to <50 copies/mm(3). Regression was utilized to investigate associations between pre-ART CD8+ and CD4+ T cell phenotypes with age and CD4+ response categories. RESULTS: Individuals <50 years had a lower frequency of senescent CD8+ T lymphocytes of the CD56 + 57+, CD56+, and CD28- phenotypes (95%CI -3.6 to -0.02; 95%CI -4.2 to -0.03; 95%CI -12.5 to -1.4, respectively) and a higher frequency of naïve (CD45RA + CD28+) CD8+ T lymphocytes (95%CI 2.6 to 10.9). Younger age and good CD4+ response were associated with a higher frequency of pre-ART naïve CD4+ T cells (95%CI 2.0 to 16.4 and 95%CI 1.5 to 15.6, respectively). CONCLUSIONS: Prior to ART, younger HIV-infected individuals have a higher frequency of naïve CD4+ and CD8+ T cells and lower frequency of senescent CD8+ T cell phenotypes.

Telomerase-based pharmacologic enhancement of antiviral function of human CD8+ T lymphocytes.

Telomerase reverse transcribes telomere DNA onto the ends of linear chromosomes and retards cellular aging. In contrast to most normal somatic cells, which show little or no telomerase activity, immune cells up-regulate telomerase in concert with activation. Nevertheless, during aging and chronic HIV-1 infection, there are high proportions of dysfunctional CD8(+) CTL with short telomeres, suggesting that telomerase is limiting. The present study shows that exposure of CD8(+) T lymphocytes from HIV-infected human donors to a small molecule telomerase activator (TAT2) modestly retards telomere shortening, increases proliferative potential, and, importantly, enhances cytokine/chemokine production and antiviral activity. The enhanced antiviral effects were abrogated in the presence of a potent and specific telomerase inhibitor, suggesting that TAT2 acts primarily through telomerase activation. Our study is the first to use a pharmacological telomerase-based approach to enhance immune function, thus directly addressing the telomere loss immunopathologic facet of chronic viral infection.

Incomplete peripheral CD4+ cell count restoration in HIV-infected patients receiving long-term antiretroviral treatment.

BACKGROUND: Although antiretroviral therapy has the ability to fully restore a normal CD4(+) cell count (>500 cells/mm(3)) in most patients, it is not yet clear whether all patients can achieve normalization of their CD4(+) cell count, in part because no study has followed up patients for >7 years. METHODS: Three hundred sixty-six patients from 5 clinical cohorts who maintained a plasma human immunodeficiency virus (HIV) RNA level 1000 copies/mL for at least 4 years after initiation of antiretroviral therapy were included. Changes in CD4(+) cell count were evaluated using mixed-effects modeling, spline-smoothing regression, and Kaplan-Meier techniques. RESULTS: The majority (83%) of the patients were men. The median CD4(+) cell count at the time of therapy initiation was 201 cells/mm(3) (interquartile range, 72-344 cells/mm(3)), and the median age was 47 years. The median follow-up period was 7.5 years (interquartile range, 5.5-9.7 years). CD4(+) cell counts continued to increase throughout the follow-up period, albeit slowly after year 4. Although almost all patients (95%) who started therapy with a CD4(+) cell count 300 cells/mm(3) were able to attain a CD4(+) cell count 500 cells/mm(3), 44% of patients who started therapy with a CD4(+) cell count <100 cells/mm(3) and 25% of patients who started therapy with a CD4(+) cell count of 100-200 cells/mm(3) were unable to achieve a CD4(+) cell count >500 cells/mm(3) over a mean duration of follow-up of 7.5 years; many did not reach this threshold by year 10. Twenty-four percent of individuals with a CD4(+) cell count <500 cells/mm(3) at year 4 had evidence of a CD4(+) cell count plateau after year 4. The frequency of detectable viremia ("blips") after year 4 was not associated with the magnitude of the CD4(+) cell count change. CONCLUSIONS: A substantial proportion of patients who delay therapy until their CD4(+) cell count decreases to <200 cells/mm(3) do not achieve a normal CD4(+) cell count, even after a decade of otherwise effective antiretroviral therapy. Although the majority of patients have evidence of slow increases in their CD4(+) cell count over time, many do not. These individuals may have an elevated risk of non-AIDS-related morbidity and mortality.

Oxidized lipids enhance RANKL production by T lymphocytes: implications for lipid-induced bone loss.

Osteoporosis is a systemic disease that is associated with increased morbidity, mortality and health care costs. Whereas osteoclasts and osteoblasts are the main regulators of bone homeostasis, recent studies underscore a key role for the immune system, particularly via activation-induced T lymphocyte production of receptor activator of NFkappaB ligand (RANKL). Well-documented as a mediator of T lymphocyte/dendritic cell interactions, RANKL also stimulates the maturation and activation of bone-resorbing osteoclasts. Given that lipid oxidation products mediate inflammatory and metabolic disorders such as osteoporosis and atherosclerosis, and since oxidized lipids affect several T lymphocyte functions, we hypothesized that RANKL production might also be subject to modulation by oxidized lipids. Here, we show that short term exposure of both unstimulated and activated human T lymphocytes to minimally oxidized low density lipoprotein (LDL), but not native LDL, significantly enhances RANKL production and promotes expression of the lectin-like oxidized LDL receptor-1 (LOX-1). The effect, which is also observed with 8-iso-Prostaglandin E2, an inflammatory isoprostane produced by lipid peroxidation, is mediated via the NFkappaB pathway, and involves increased RANKL mRNA expression. The link between oxidized lipids and T lymphocytes is further reinforced by analysis of hyperlipidemic mice, in which bone loss is associated with increased RANKL mRNA in T lymphocytes and elevated RANKL serum levels. Our results suggest a novel pathway by which T lymphocytes contribute to bone changes, namely, via oxidized lipid enhancement of RANKL production. These findings may help elucidate clinical associations between cardiovascular disease and decreased bone mass, and may also lead to new immune-based approaches to osteoporosis.

Primary human immunodeficiency virus type 1 (HIV-1) infection during HIV-1 Gag vaccination.

Vaccination for human immunodeficiency virus type 1 (HIV-1) remains an elusive goal. Whether an unsuccessful vaccine might not only fail to provoke detectable immune responses but also could actually interfere with subsequent natural immunity upon HIV-1 infection is unknown. We performed detailed assessment of an HIV-1 gag DNA vaccine recipient (subject 00015) who was previously uninfected but sustained HIV-1 infection before completing a vaccination trial and another contemporaneously acutely infected individual (subject 00016) with the same strain of HIV-1. Subject 00015 received the vaccine at weeks 0, 4, and 8 and was found to have been acutely HIV-1 infected around the time of the third vaccination. Subject 00016 was a previously HIV-1-seronegative sexual contact who had symptoms of acute HIV-1 infection approximately 2 weeks earlier than subject 00015 and demonstrated subsequent seroconversion. Both individuals reached an unusually low level of chronic viremia (<1,000 copies/ml) without treatment. Subject 00015 had no detectable HIV-1-specific cytotoxic T-lymphocyte (CTL) responses until a borderline response was noted at the time of the third vaccination. The magnitude and breadth of Gag-specific CTL responses in subject 00015 were similar to those of subject 00016 during early chronic infection. Viral sequences from gag, pol, and nef confirmed the common source of HIV-1 between these individuals. The diversity and divergence of sequences in subjects 00015 and 00016 were similar, indicating similar immune pressure on these proteins (including Gag). As a whole, the data suggested that while the gag DNA vaccine did not prime detectable early CTL responses in subject 00015, vaccination did not appreciably impair his ability to contain viremia at levels similar to those in subject 00016.

Two-way Bayesian hierarchical phylogenetic models: An application to the co-evolution of gp120 and gp41 during and after enfuvirtide treatment.

Enfuvirtide (ENF) is a fusion inhibitor that prevents the entry of HIV virions into target cells. Studying the characteristics of viral evolution during treatment and after a treatment interruption can lend insight into the mechanisms of viral evolution and fitness. Although interruption of anti-HIV therapy often results in rapid emergence of an archived "wild-type" virus population, previous work from our group indicates that when only ENF is interrupted, viral gp41 continues to evolve forward and resistance mutations are lost due to back-mutation and remodeling of the envelope protein. To examine the co-evolution of gp120 and gp41 during ENF interruption we extend the Bayesian Hierarchical Phylogenetic model (HPM). Current HPMs enforce conditional independence across all outcomes while biologically all gene regions within a patient should return the same tree unless recombination confers an evolutionary selective advantage. A two-way-interaction HPM is proposed that provides middle ground between these two extremes and allows us to test for differences in evolutionary pressures across gene regions in multiple patients simultaneously. When the model is applied to a well-characterized cohort of HIV-infected patients interrupting ENF we find that across patients, the virus continued to evolve forward in both gene regions. Overall, the hypothesis of independence over dependence between the gene regions is supported. Models that allow for the examination of co-evolution over time will be increasingly important as more therapeutic classes are developed, each of which may impact other through novel and complex mechanisms.

Lower Switch Rate in Depressed Patients With Bipolar II Than Bipolar I Disorder Treated Adjunctively With Second-Generation Antidepressants.

(Reprinted with permission from Am J Psychiatry 2006; 163:313-315).

Clarifying CB2 receptor-dependent and independent effects of THC on human lung epithelial cells.

Marijuana smoking is associated with a number of abnormal findings in the lungs of habitual smokers. Previous studies revealed that Delta(9)-tetrahydrocannabinol (THC) caused mitochondrial injury in primary lung epithelial cells and in the cell line, A549 [Sarafian, T. A., Kouyoumjian, S., Khoshaghideh, F., Tashkin, D. P., and Roth, M. D. (2003). Delta 9-tetrahydrocannabinol disrupts mitochondrial function and cell energetics. Am J Physiol Lung Cell Mol Physiol 284, L298-306; Sarafian, T., Habib, N., Mao, J. T., Tsu, I. H., Yamamoto, M. L., Hsu, E., Tashkin, D. P., and Roth, M. D. (2005). Gene expression changes in human small airway epithelial cells exposed to Delta9-tetrahydrocannabinol. Toxicol Lett 158, 95-107]. The role of cannabinoid receptors in this injury was unclear, as was the potential impact on cell function. In order to investigate these questions, A549 cells were engineered to over-express the type 2 cannabinoid receptor (CB2R) using a self-inactivating lentiviral vector. This transduction resulted in a 60-fold increase in CB2R mRNA relative to cells transduced with a control vector. Transduced cell lines were used to study the effects of THC on chemotactic activity and mitochondrial function. Chemotaxis in response to a 10% serum gradient was suppressed in a concentration-dependent manner by exposure to THC. CB2R-transduced cells exhibited less intrinsic chemotactic activity (p<0.05) and were 80- to 100-fold more sensitive to the inhibitory effects of THC. Studies using SR144528, a selective CB2R antagonist, verified that these effects were mediated by the CB2R. Marijuana smoke extract, but not smoke extracts from tobacco or placebo marijuana cigarettes, reproduced these effects (p<0.05). THC decreased ATP level and mitochondrial membrane potential (Psi(m)) in both control and CB2R-transduced cells. However, these decreases did not play a significant role in chemotaxis inhibition since cyclosporine A, which protected against ATP loss, did not increase cell migration. Moreover, CB2R-transduced cells displayed higher Psi(m) than did control cells. Since both Psi(m) and chemotaxis are regulated by intracellular signaling, we investigated the effects of THC on the activation of multiple signaling pathways. Serum exposure activated several signaling events of which phosphorylation of IkappaB-alpha and JNK was regulated in a CB2R- and THC-dependent manner. We conclude that airway epithelial cells are sensitive to both CB2R-dependent and independent effects mediated by THC.

Increased susceptibility of vault poly(ADP-ribose) polymerase-deficient mice to carcinogen-induced tumorigenesis.

Vault poly(ADP-ribose) polymerase (VPARP) and telomerase-associated protein 1 (TEP1) are components of the vault ribonucleoprotein complex. Vaults have been implicated in multidrug resistance of human tumors and are thought to be involved in macromolecular assembly and/or transport. Previous studies showed that VPARP-deficient mice were viable, fertile, and did not display any vault-related or telomerase-related phenotype, whereas disruption of telomerase-associated protein 1 in mice led to reduced stability of the vault RNA and affected its stable association with vaults, although there were no telomerase-related changes. In this study, we evaluated the susceptibility of Vparp-/- and Tep1-/- mice to dimethylhydrazine-induced colon tumorigenesis and urethane-induced lung tumorigenesis. Mice received i.p. injections of either 1 g/kg body weight of urethane twice a week for 2 weeks or 20 mg/kg body weight of dimethylhydrazine once a week for 10 weeks and were analyzed after 10 and 60 weeks, respectively. The colon tumor incidence and multiplicity were significantly higher and colon tumor latency was significantly shorter in Vparp-/- mice compared with wild-type mice. Increased colon tumor incidence, multiplicity, and reduced tumor latency were also seen in Tep1-/- mice, however, these results were statistically not significant. Lung tumor multiplicities were increased in both Vparp-/- and Tep1-/- mice but were not significant. The increase in carcinogen-induced tumors in VPARP-deficient mice is the only phenotype observed to date, and suggests a possible role for VPARP, directly or indirectly, in chemically induced neoplasia.

Thymic volume, T-cell populations, and parameters of thymopoiesis in adolescent and adult survivors of HIV infection acquired in infancy.

OBJECTIVES: Antiretroviral therapy has significantly prolonged the lifespan of children who acquire HIV infection in infancy, but the impact of HIV on thymus-mediated maintenance of T lymphocytes has not been studied. To examine the long-term effects of HIV infection in childhood on thymopoiesis, thymic volume and parameters of thymic function from clinically stable adolescents and young adults with HIV infection acquired in infancy were compared with those from uninfected controls. METHODS: Thymic volume was determined using three-dimensional reconstruction and volumetric analysis of non-contrast enhanced computed tomography images of the upper chest. The degree of fat involution was assessed using a semiquantitive scoring system. CD4 and CD8 T cell populations and T cell receptor recombination excision circles (TREC) concentrations in peripheral blood lymphocytes were measured in all subjects. RESULTS: Twenty youths (aged 17.6 +/- 2.5 years) with HIV infection acquired perinatally (n = 18) or by neonatal transfusion (n = 2) were enrolled whose HIV plasma viral load had been undetectable for a median of 3.1 years, along with 18 seronegative healthy young adults (aged 20.6 +/- 1.3 years). HIV infected subjects and controls had indistinguishable CD4 T cell counts, thymus volumes (20.5 versus 15.8 cm), thymic index scores, and TREC values. Thymic volume correlated with the number and percentage of CD4 T lymphocytes in the control group and with the number of TREC in CD4 lymphocytes in the HIV infected group. CONCLUSIONS: Long term survivors of pediatric HIV infection appear to have retained or recovered thymic volume and thymic activity approximating uninfected youths.

Lower switch rate in depressed patients with bipolar II than bipolar I disorder treated adjunctively with second-generation antidepressants.

OBJECTIVES: The authors compared the switch rate into hypomania/mania in depressed patients treated with second-generation antidepressants who had either bipolar I or bipolar II disorder. METHOD: In a 10-week trial, 184 outpatients with bipolar depression (134 with bipolar I disorder, 48 with bipolar II disorder, two with bipolar disorder not otherwise specified) were treated with one of three antidepressants as an adjunct to mood stabilizers. The patients' switch rates were assessed. Switch was defined as a Young Mania Rating Scale (YMRS) score >13 or a Clinical Global Impression (CGI) mania score > or =3 (mildly ill). RESULTS: Depressed subjects with bipolar II disorder had a significantly lower acute switch rate into hypomania/mania when either YMRS or CGI criteria were used to define switch. CONCLUSIONS: These data suggest that depressed patients with bipolar II disorder are less vulnerable than those with bipolar I disorder to switch into hypomania/mania when treated with an antidepressant adjunctive to a mood stabilizer.

Continued evolution in gp41 after interruption of enfuvirtide in subjects with advanced HIV type 1 disease.

Careful examination of viral dynamics during antiretroviral treatment can provide important insights into HIV pathogenesis. We examined viral evolution during and after enfuvirtide (T-20) treatment with an objective of defining the characteristics of viral evolution during advanced HIV immunodeficiency. Specifically, we examined the viral quasispecies from nine patients who experienced incomplete viral suppression on an enfuvirtide-based regimen, and who subsequently interrupted enfuvirtide while remaining on a stable optimized background regimen (enfuvirtide "partial treatment interruption"). On average, eight clones were sequenced from three time points: pre-enfuvirtide, post-enfuvirtide failure, and post-enfuvirtide interruption. We utilized a Bayesian hierarchical phylogenetic model to assess the evolutionary relatedness of the virus that emerged over time. In most subjects, interruption of enfuvirtide was associated with continued viral evolution as enfuvirtide mutations waned; in no subject did we find clear evidence supporting the reemergence of archived wild-type variants (Bayes factor=30.2, p=0.01). Evidence supporting ongoing viral evolution was particularly strong in subjects whose virus remained diverse or became more diverse during enfuvirtide therapy. In contrast to observations when all drugs are interrupted, loss of resistance during enfuvirtide interruption is most likely due to ongoing viral evolution (and back-mutation), rather than emergence of an archived virus.

Is unawareness of psychotic disorder a neurocognitive or psychological defensiveness problem?

We examined whether deficits in attention and perceptual encoding as well as psychological defensiveness were associated with impaired awareness of disorder in schizophrenia. The Scale for Unawareness of Mental Disorder (SUMD) was administered to 52 outpatients with a recent onset of schizophrenia approximately 1-2 months following hospital discharge. Two versions of the Continuous Performance Test (CPT) were used to measure attentional impairment--the Degraded Stimulus CPT (DS-CPT) and a memory-load version (3-7 CPT). Three scales from the Minnesota Multiphasic Personality Inventory were used as indicators of psychological defensiveness: Scales L (Lie), K (Correction), and R (Repression). The Classification and Regression Tree (CART) program, a nonparametric statistical method, was used to identify relationships among multiple predictor variables and to provide optimal splitting scores for each predictor variable. Different combinations of poor target discrimination (d') on the 3-7 CPT and a cautious response style on the DS-CPT were associated with the three levels of overall unawareness of having a mental disorder. For nonpsychotic patients, better target discrimination (d') on the 3-7 CPT tended to be associated with better awareness of having a mental disorder. In contrast, unawareness among the patients who were psychotic at the time of the SUMD administration was not discriminated by attentional measures, but was associated with a combination of two measures of psychological defensiveness from the MMPI reflecting guardedness, psychological suppression, attempting to present oneself in a socially desirable light, and social acquiescence. Generally similar associations were found for two other dimensions of poor insight: unawareness of the beneficial effects of antipsychotic medication, and inability to attribute unusual thoughts and hallucinatory experiences to a mental disorder.

HIV type 1 infection alters cytokine mRNA expression in thymus.

We and others have previously shown that HIV infection of human thymus/liver implants in severe combined immunodeficient (SCID-hu Thy/Liv) mice results in a loss of CD4(+) thymocytes and a decreased recovery of human myeloid and erythroid colony-forming activity. Furthermore, our previous studies have shown that this decrease in colony-forming potential is due to indirect effects, rather than to massive loss of CD34(+) hematopoietic progenitor cells, suggesting that HIV infection might alter expression of hematopoietic cytokines. Herein we have investigated potential HIV-1-induced perturbations of hematolymphoid microenvironments by determining the effect of HIV-1 infection on levels of cytokine mRNAs in human stroma and thymocytes, using the reverse transcription-polymerase chain reaction (RT-PCR). The levels of interleukin 6 (IL-6), interferon gamma (IFN-gamma), and IL-2 RNAs increased and macrophage inflammatory protein 1beta (MIP-1beta) RNA decreased significantly in infected thymocytes. IL-6 RNA levels in stroma also increased somewhat with infection; however, expression of stromal cell-derived factor 1 (SDF-1) by stromal elements was not affected. IL-4 RNA levels were unaffected by infection in both stroma and thymocytes. Antiretroviral drug treatment of the infected animals, which results in restoration of colony-forming potential, tends to restore the cytokine mRNA levels in HIV-1-infected implants to those of mock-infected implants. These results indicate that HIV-1 infection can greatly distort the cytokine profiles in Thy/Liv implants, and suggest that cytokine perturbation could be involved in virus-induced inhibition of hematopoiesis.

Medical burden, cerebrovascular disease, and cognitive impairment in geriatric depression: modeling the relationships with the CART analysis.

Herein, the background information reflecting roles of medical burden, cerebrovascular disease and risk factors, and cognitive impairment in geriatric depression are reviewed. The authors then propose a nonparametric statistical approach to the data analysis of multiple putative causal variables for late-life depression, the Classification and Regression Tree Analysis. This analysis presents a useful approach to modeling nonlinear relationships and interactions among variables measuring physical and mental health, as well as magnetic resonance imaging and cognitive measures in depressed elderly. This method uncovers the existing interactions among multiple predictor variables, and provide thresholds for each variable, at which its predictive power becomes statistically significant. It presents a "hierarchy" of the predictors in a form of a decision tree by finding the best combination of predictors of an outcome. The authors present two models based on demographic variables, measures of vascular and nonvascular medical burden, neuroimaging indices, the Mini-Mental State Examination score, and neuropsychological test scores of 81 elderly depressed subjects. Cognitive tests of verbal fluency and executive function are identified as the best predictors of depression, followed by the frontal lobe volume and Mini-Mental State Examination. The authors observed that an interaction between frontal lobe volume, total lesion volume, and medical burden was predictive of depression.

Magnesium sulfate increases intracellular magnesium reducing inflammatory cytokine release in neonates.

PROBLEM: Magnesium sulfate (MgSO4 ) exposure reduces the risk of cerebral palsy. As neonatal inflammatory cytokine levels strongly correlate with neurologic outcome, we hypothesize that MgSO4 decreases inflammatory cytokine production. METHOD OF STUDY: We assessed the effect of MgSO4 on cellular magnesium levels, cytokine production, and release within THP-1 and cord blood mononuclear cells. RESULTS: MgSO4 exposure increased intracellular magnesium levels, reducing the frequency of THP-1 cells producing IL-1ß, IL-8, and TNF-α following LPS stimulation. Significant reductions in the frequency of neonatal monocytes producing TNF-α (48%) and IL-6 (37%) were seen following LPS stimulation, and MgSO4 also significantly decreased the frequency of monocytes producing TNF-α (35%) under basal conditions. Decreased cytokine production was confirmed via ELISA, demonstrating a sustained effect and dose response. Magnesium also reduced cytokine production following stimulation with TLR ligands representing obstetrical infections (group B Streptococcus and Mycoplasma) and in preterm neonatal monocytes. CONCLUSION: MgSO4 increases intracellular magnesium, reducing inflammatory cytokine production and release, potentially elucidating the mechanism by which MgSO4 prevents cerebral palsy, eclampsia, and preterm birth.

Levels of murine, but not human, CXCL13 are greatly elevated in NOD-SCID mice bearing the AIDS-associated Burkitt lymphoma cell line, 2F7.

Currently, few rodent models of AIDS-associated non-Hodgkin's lymphoma (AIDS-NHL) exist. In these studies, a novel mouse/human xenograft model of AIDS-associated Burkitt lymphoma (AIDS-BL) was created by injecting cells of the human AIDS-BL cell line, 2F7, intraperitoneally into NOD-SCID mice. Mice developed tumors in the peritoneal cavity, with metastases to the spleen, thymus, and mesenteric lymph nodes. Expression of the chemokine receptor, CXCR5, was greatly elevated in vivo on BL tumor cells in this model, as shown by flow cytometry. CXCL13 is the ligand for CXCR5, and serum and ascites levels of murine, but not human, CXCL13 showed a striking elevation in tumor-bearing mice, with levels as high as 200,000 pg/ml in ascites, as measured by ELISA. As shown by immunohistochemistry, murine CXCL13 was associated with macrophage-like tumor-infiltrating cells that appeared to be histiocytes. Blocking CXCR5 on 2F7 cells with neutralizing antibodies prior to injection into the mice substantially delayed tumor formation. The marked elevations in tumor cell CXCR5 expression and in murine CXCL13 levels seen in the model may potentially identify an important link between tumor-interacting histiocytes and tumor cells in AIDS-BL. These results also identify CXCL13 as a potential biomarker for this disease, which is consistent with previous studies showing that serum levels of CXCL13 were elevated in human subjects who developed AIDS-lymphoma. This mouse model may be useful for future studies on the interactions of the innate immune system and AIDS-BL tumor cells, as well as for the assessment of potential tumor biomarkers for this disease.