Initiation of combined antiretroviral therapy confers suboptimal beneficial effects on neurovascular function in people with HIV

Introduction

Due to advances in combined anti-retroviral treatment (cART), there is an increased burden of age-related cerebrovascular disease (CBVD), in people living with HIV (PWH). The underlying CNS injury can be assessed by measuring cerebral blood flow (CBF) and cerebrovascular reactivity (CVR).

Methods

35 treatment-naïve PWH and 53 HIV negative controls (HC) were enrolled in this study. Study participants underwent T1-weighted anatomical, pseudo-continuous arterial spin labeling, and resting-state functional MRI to obtain measures of CBF and CVR prior to starting cART treatment and at two-time points (12 weeks and 2 years) post-cART initiation. Controls were scanned at the baseline and 2-year visits. We also measured plasma levels of microparticles of endothelial and glial origin and well-known endothelial inflammation markers, ICAM-1 and VCAM-1, to assess HIV-associated endothelial inflammation and the interaction of these peripheral markers with brain neurovascular function.

Results

HIV infection was found to be associated with reduced CVR and increased levels of endothelial and glial microparticles (MPs) prior to initiation of cART. Further, CVR correlated negatively with peripheral MP levels in PWH.

Discussion

Our results suggest that while cART treatment has a beneficial effect on the neurovascular function after initiation, these benefits are suboptimal over time.

Role of non-classical monocytes in HIV-associated vascular cognitive impairment

Despite antiretroviral treatment (cART), people living with HIV (PLWH) are more susceptible to neurocognitive impairment (NCI), probably due to synergistic/additive contribution of traditional cerebrovascular risk factors. Specifically, altered blood brain barrier (BBB) and transmigration of inflammatory monocytes are risk factors for developing cerebral small vessel disease (CSVD). In order to investigate if inflammatory monocytes exacerbate CSVD and cognitive impairment, 110 PLWH on cART and 110 age-, sex- and Reynold’s cardiovascular risk score-matched uninfected individuals were enrolled. Neuropsychological testing, brain magnetic resonance imaging and whole blood analyses to measure platelet-monocyte interaction and monocyte, endothelial activation were performed. Results demonstrated that PLWH exhibited increased levels of platelet-monocyte complexes (PMCs) and higher expression of activation molecules on PMCs. PLWH with CSVD had the poorest cognitive performance and the highest circulating levels of non-classical monocytes which exhibited significant inverse correlation with each other. Furthermore, markers of monocyte and endothelium activation were significantly positively correlated indicating BBB impairment. Our results confirm that interaction with platelets activates and drives monocytes towards an inflammatory phenotype in PLWH. In particular, elevated levels of non-classical monocytes may represent a common pathway to neuroinflammation, CSVD and subsequent cognitive impairment, warranting further longitudinal studies to evaluate responsiveness of this potential biomarker.

Executable models of immune signaling pathways in HIV-associated atherosclerosis

Atherosclerosis (AS)-associated cardiovascular disease is an important cause of mortality in an aging population of people living with HIV (PLWH). This elevated risk has been attributed to viral infection, anti-retroviral therapy, chronic inflammation, and lifestyle factors. However, the rates at which PLWH develop AS vary even after controlling for length of infection, treatment duration, and for lifestyle factors. To investigate the molecular signaling underlying this variation, we sequenced 9368 peripheral blood mononuclear cells (PBMCs) from eight PLWH, four of whom have atherosclerosis (AS+). Additionally, a publicly available dataset of PBMCs from persons before and after HIV infection was used to investigate the effect of acute HIV infection. To characterize dysregulation of pathways rather than just measuring enrichment, we developed the single-cell Boolean Omics Network Invariant Time Analysis (scBONITA) algorithm. scBONITA infers executable dynamic pathway models and performs a perturbation analysis to identify high impact genes. These dynamic models are used for pathway analysis and to map sequenced cells to characteristic signaling states (attractor analysis). scBONITA revealed that lipid signaling regulates cell migration into the vascular endothelium in AS+ PLWH. Pathways implicated included AGE-RAGE and PI3K-AKT signaling in CD8+ T cells, and glucagon and cAMP signaling pathways in monocytes. Attractor analysis with scBONITA facilitated the pathway-based characterization of cellular states in CD8+ T cells and monocytes. In this manner, we identify critical cell-type specific molecular mechanisms underlying HIV-associated atherosclerosis using a novel computational method.

Human immunodeficiency virus-1 Tat exerts its neurotoxic effects by downregulating Sonic hedgehog signaling

We previously showed that HIV-1 can alter the expression of tight junction proteins by downregulating Sonic hedgehog (Shh) signaling, thereby disrupting blood-brain barrier (BBB) integrity. In this study, we employed a conditional, CNS specific, Tat transgenic murine model to investigate if HIV-Tat exerts its neurotoxic effects by downregulating Shh signaling. Results indicate that Tat + mice exhibit significantly reduced expression of Shh and Gli1. HIV-Tat induced downregulation of Shh signaling correlated with disruption of BBB function and induced infiltration of peripheral leukocytes into the brain tissue. Further, our in vivo and in vitro experiments suggest that activation of Shh signaling can rescue detrimental effects of Tat on endothelial function by inducing the expression of junctional proteins and by decreasing the levels of inflammatory cytokines/chemokines.

Increased risk for cerebral small vessel disease is associated with quantitative susceptibility mapping in HIV infected and uninfected individuals

The aim of this study was to assess, in the context of cerebral small vessel disease (CSVD), whether cardiovascular risk factors and white matter hyperintensities (WMHs) were associated with brain tissue susceptibility as measured by quantitative susceptibility mapping (QSM). Given that CSVD is diagnosed by the presence of lacunar strokes, periventricular and deep WMHs, increased perivascular spaces, and microbleeds, we expected that QSM could capture changes in brain tissue due to underlying CSVD pathology. We compared a cohort of 101 HIV-infected individuals (mean age ± SD = 53.2 ± 10.9 years) with mild to moderate cardiovascular risk scores, as measured by the Reynolds risk score, to 102 age-matched controls (mean age (SD) = 50.3 (15.7) years) with similar Reynolds scores. We performed brain MRI to assess CSVD burden by acquiring 3D T1-MPRAGE, 3D FLAIR, 2D T2-TSE, and mGRE for QSM. We found that signs of CSVD are significantly higher in individuals with HIV-infection compared to controls and that WMH volumes are significantly correlated with age and cardiovascular risk scores. Regional QSM was associated with cardiovascular risk factors, age, sex, and WMH volumes but not HIV status. These results suggest that QSM may be an early imaging marker reflective of alterations in brain microcirculation.

Monocytes complexed to platelets differentiate into functionally deficient dendritic cells

In addition to their role in hemostasis, platelets store numerous immunoregulatory molecules such as CD40L, TGFβ, β2-microglobulin, and IL-1β and release them upon activation. Previous studies indicate that activated platelets form transient complexes with monocytes, especially in HIV infected individuals and induce a proinflammatory monocyte phenotype. Because monocytes can act as precursors of dendritic cells (DCs) during infection/inflammation as well as for generation of DC-based vaccine therapies, we evaluated the impact of activated platelets on monocyte differentiation into DCs. We observed that in vitro cultured DCs derived from platelet-monocyte complexes (PMCs) exhibit reduced levels of molecules critical to DC function (CD206, dendritic cell-specific intercellular adhesion molecule-3-grabbing nonintegrin, CD80, CD86, CCR7) and reduced antigen uptake capacity. DCs derived from PMCs also showed reduced ability to activate naïve CD4+ and CD8+ T cells, and secrete IL-12p70 in response to CD40L stimulation, resulting in decreased ability to promote type-1 immune responses to HIV antigens. Our results indicate that formation of complexes with activated platelets can suppress the development of functional DCs from such monocytes. Disruption of PMCs in vivo via antiplatelet drugs such as Clopidogrel/Prasugrel or the application of platelet-free monocytes for DCs generation in vitro, may be used to enhance immunization and augment the immune control of HIV.

Molecular characterization of atherosclerosis in HIV positive persons

People living with HIV are at higher risk of atherosclerosis (AS). The pathogenesis of this risk is not fully understood. To assess the regulatory networks involved in AS we sequenced mRNA of the peripheral blood mononuclear cells (PBMCs) and measured cytokine and chemokine levels in the plasma of 13 persons living with HIV and 12 matched HIV-negative persons with and without AS. microRNAs (miRNAs) are known to play a role in HIV infection and may modulate gene regulation to drive AS. Hence, we further assessed miRNA expression in PBMCs of a subset of 12 HIV+ people with and without atherosclerosis. We identified 12 miRNAs differentially expressed between HIV+ AS+ and HIV+ , and validated 5 of those by RT-qPCR. While a few of these miRNAs have been implicated in HIV and atherosclerosis, others are novel. Integrating miRNA measurements with mRNA, we identified 27 target genes including SLC4A7, a critical sodium and bicarbonate transporter, that are potentially dysregulated during atherosclerosis. Additionally, we uncovered that levels of plasma cytokines were associated with transcription factor activity and miRNA expression in PBMCs. For example, BACH2 activity was associated with IL-1β, IL-15, and MIP-1α. IP10 and TNFα levels were associated with miR-124-3p. Finally, integration of all data types into a single network revealed increased importance of miRNAs in network regulation of the HIV+ group in contrast with increased importance of cytokines in the HIV+ AS+ group.

Pathomechanisms of HIV-Associated Cerebral Small Vessel Disease: A Comprehensive Clinical and Neuroimaging Protocol and Analysis Pipeline

Rationale: We provide an in-depth description of a comprehensive clinical, immunological, and neuroimaging study that includes a full image processing pipeline. This approach, although implemented in HIV infected individuals, can be used in the general population to assess cerebrovascular health.

Aims: In this longitudinal study, we seek to determine the effects of neuroinflammation due to HIV-1 infection on the pathomechanisms of cerebral small vessel disease (CSVD). The study focuses on the interaction of activated platelets, pro-inflammatory monocytes and endothelial cells and their impact on the neurovascular unit. The effects on the neurovascular unit are evaluated by a novel combination of imaging biomarkers.

Sample Size: We will enroll 110 HIV-infected individuals on stable combination anti-retroviral therapy for at least three months and an equal number of age-matched controls. We anticipate a drop-out rate of 20%.

Methods and Design: Subjects are followed for three years and evaluated by flow cytometric analysis of whole blood (to measure platelet activation, platelet monocyte complexes, and markers of monocyte activation), neuropsychological testing, and brain MRI at the baseline, 18- and 36-month time points. MRI imaging follows the recommended clinical small vessel imaging standards and adds several advanced sequences to obtain quantitative assessments of brain tissues including white matter microstructure, tissue susceptibility, and blood perfusion.

Discussion: The study provides further understanding of the underlying mechanisms of CSVD in chronic inflammatory disorders such as HIV infection. The longitudinal study design and comprehensive approach allows the investigation of quantitative changes in imaging metrics and their impact on cognitive performance.

Novel Mechanism of Microvesicle Regulation by the Antiviral Protein Tetherin During HIV Infection

Background Microvesicles are cell membrane-derived vesicles that have been shown to augment inflammation. Specifically, monocyte-derived microvesicles (MDMVs), which can express the coagulation protein tissue factor, contribute to thrombus formation and cardiovascular disease. People living with HIV experience higher prevalence of cardiovascular disease and also exhibit increased levels of plasma microvesicles. The process of microvesicle release has striking similarity to budding of enveloped viruses. The surface protein tetherin inhibits viral budding by physically tethering budding virus particles to cells. Hence, we investigated the role of tetherin in regulating the release of MDMVs during HIV infection. Methods and Results The plasma of aviremic HIV-infected individuals had increased levels of tissue factor + MDMVs, as measured by flow cytometry, and correlated to reduced tetherin expression on monocytes. Superresolution confocal and electron microscopy showed that tetherin localized at the site of budding MDMVs. Mechanistic studies revealed that the exposure of monocytes to HIV-encoded Tat triggered tetherin loss and subsequent rise in MDMV production. Overexpression of tetherin in monocytes led to morphologic changes in the pseudopodia directly underneath the MDMVs. Further, tetherin knockout mice demonstrated a higher number of circulating MDMVs and less time to bleeding cessation. Conclusions Our studies define a novel regulatory mechanism of MDMV release through tetherin and explore its contribution to the procoagulatory state that is frequently observed in people with HIV. Such insights could lead to improved therapies for individuals infected with HIV and also for those with cardiovascular disease.

Characterization of platelet signature on monocytes isolated from HIV infected individuals

Background

Higher levels of platelet-monocyte complexes (PMCs) are detected in human immunodeficiency virus (HIV)-infected individuals. Such complexes are implicated in expansion of monocytes exhibiting inflammatory phenotype, and their translocation into tissues, thus promoting development of cerebrovascular and cardiovascular disorders. Here we have recruited small sub-set of HIV-infected individuals to investigate how platelets cause epigenetic changes in monocytes of HIV-infected individuals. We posit that the formation of PMCs facilitates monocyte differentiation via exchange of biomaterial between activated platelets and monocytes during HIV-infection.

Methods

We performed ATAC-seq to measure changes in chromatin accessibility from two types of monocytes, PMC-derived or non-PMC-derived, isolated from HIV-infected persons.

Results

Using ATAC-Seq data, we were able to detect distinct changes in chromatin accessibility patterns within the genomic regions of proinflammatory mediators in PMC-derived monocytes. Chromatin accessibility of inflammatory genes was dramatically increased in PMC-derived monocytes. This suggested to us a possibility of active exchange of molecules that causes such alterations in monocytes.

Conclusions

Increases in chromatin accessibility of pro-inflammatory genes occur in the PMC-derived monocytes in persons with HIV. This change is likely due to the transfer of platelet antigens to monocytes via cell-cell interaction, suggesting a novel mechanism through which platelets trigger inflammatory response in monocytes. Thus, our initial findings pave a way that has a strong diagnostic as well as therapeutic value.

Studying platelet-HIV interactions and potential to promote viral spread

HIV-infected individuals experience persistent inflammation, which is associated with increased platelet activation. There is growing evidence that platelets contribute to immune responses, through the release of inflammatory granules and complex formation with other cells including monocytes and CD4+ T-cells, both of which are susceptible to infection. Previous studies have found evidence that HIV is engulfed by platelets. However, such studies were primarily conducted in vitro. It is important to study consequences of HIV-platelet interactions, and to ascertain whether or not they occur in patients.

We confirmed previous in vitro findings through co-culturing platelets from healthy donors, with HIV virions, and using electron microscopy identified virus-like particles inside platelets. Utilizing RNAscope in tandem with RT-PCR we created a timeline of virus-platelet associations and found viral genomic RNA remained associated with platelets for a prolonged period of time. Importantly, platelet-associated virus remained infectious, as platelets were able to spread infection to activated CD4+ T-cells in coculture experiments. Furthermore, we established a system to screen for HIV-positive platelets. We isolated platelets from cART-naïve viremic patients and performed super resolution microscopy and imagestream flow cytometry. This analysis revealed evidence of HIV-positive platelets in these infected individuals. In contrast, the amount of HIV-positive platelets was drastically, although not entirely, reduced following 3 months of cART treatment. Our findings suggest that platelet-virus interactions may be important in contributing to viral spread, and the development and maintenance of viral reservoirs.

Senescent Phenotype Induced by p90RSK-NRF2 Signaling Sensitizes Monocytes and Macrophages to Oxidative Stress in HIV-Positive Individuals

BACKGROUND

The incidence of cardiovascular disease is higher in HIV-positive (HIV⁺) patients than it is in the average population, and combination antiretroviral therapy (cART) is a recognized risk factor for cardiovascular disease. However, the molecular mechanisms that link cART and cardiovascular disease are currently unknown. Our study explores the role of the activation of p90RSK, a reactive oxygen species-sensitive kinase, in engendering senescent phenotype in macrophages and accelerating atherogenesis in patients undergoing cART.

METHODS

Peripheral whole blood from cART-treated HIV⁺ individuals and nontreated HIV-negative individuals was treated with H₂O₂ (200 µmol/L) for 4 minutes, and p90RSK activity in CD14⁺ monocytes was measured. Plaque formation in the carotids was also analyzed in these individuals. Macrophage senescence was determined by evaluating their efferocytotic ability, antioxidation-related molecule expression, telomere length, and inflammatory gene expression. The involvement of p90RSK-NRF2 signaling in cART-induced senescence was assessed by p90RSK-specific inhibitor (FMK-MEA) or dominant-negative p90RSK (DN-p90RSK) and NRF2 activator (NRF2A). Further, the severity of atherosclerosis was determined in myeloid cell-specific wild-type and DN-p90RSK transgenic mice.

RESULTS

Monocytes from HIV⁺ patients exhibited higher levels of p90RSK activity and were also more sensitive to reactive oxygen species than monocytes from HIV-negative individuals. A multiple linear regression analysis involving cART, Reynolds cardiovascular risk score, and basal p90RSK activity revealed that cART and basal p90RSK activity were the 2 significant determinants of plaque formation. Many of the antiretroviral drugs individually activated p90RSK, which simultaneously triggered all components of the macrophage senescent phenotype. cART inhibited antioxidant response element reporter activity via ERK5 S496 phosphorylation. NRF2A reversed the H₂O₂-induced overactivation of p90RSK in cART-treated macrophages by countering the induction of senescent phenotype. Last, the data obtained from our gain- or loss-of-function mice conclusively showed the crucial role of p90RSK in inducing senescent phenotype in macrophages and atherogenesis.

CONCLUSIONS

cART increased monocyte/macrophage sensitivity to reactive oxygen species- in HIV⁺ individuals by suppressing NRF2-ARE activity via p90RSK-mediated ERK5 S496 phosphorylation, which coordinately elicited senescent phenotypes and proinflammatory responses. As such, our report underscores the importance of p90RSK regulation in monocytes/macrophages as a viable biomarker and therapeutic target for preventing cardiovascular disease, especially in HIV⁺ patients treated with cART.

Abstract 223: Monocytes/macrophages Are Sensitized to Secondary Oxidative Insult by Cardiovascular Toxic Drugs via the P90rsk-erk5 S496 Phosphorylation Pathway, Aggrandizing Atherosclerotic Plaque Formation

Increased cardiovascular (CV) events in HIV patients and cancer survivors and the fact that combination antiretroviral therapy (cART) and chemotherapy induce similar unwanted CV effects are becoming evident, but the reason for this is unclear. In this study, we examined the role of p90RSK in the CV toxicity of cART and anti-cancer drugs. The level of p90RSK activation by H2O2 was higher in peripheral monocytes from cART-treated patients than in those from untreated patients. Multiple linear regression analysis involving HIV+/-, Reynolds CV risk score, and basal p90RSK activation revealed HIV+/- and basal p90RSK activation to be strong determinants for plaque formation when adjusted for other independent variables. In murine macrophages most of the cART and several chemotherapy agents activated p90RSK and reduced antioxidant molecule expression and telomere (TL) lengths. p90RSK-mediated ERK5 S496 phosphorylation inhibited transcriptional activity of ERK5 and NRF2, decreasing efferocytosis, antioxidant production and TL lengths. NRF2 activator normalized cART-induced sensitization of p90RSK to H2O2. Lastly, we generated myeloid cells-specific wild type (WT) and dominant negative (DN) p90RSK transgenic mice, and ERK5 S496A knock-in mice, crossed with Ldlr-/- mice or treated with a single injection of adeno-associated virus vector (AAV) encoding a gain-of-function mutant of PCSK9 and fed a high fat diet. Our animal studies showed the crucial role of p90RSK-mediated ERK5 S496 phosphorylation in suppressing effecrocytosis and antioxidant production, and up-regulating senescence and inflammation-related molecules expression, leading to atherogenesis. Our results taken together show that p90RSK is activated by anti-HIV and anti-cancer drugs, and this activation sensitizes the monocyte/macrophages to the secondary oxidative insult by reducing NRF2 transcriptional activity and TL length. The p90RSK activation also reduces macrophage efferocytosis and antioxidant capacity, and increases inflammation and senescence via up-regulating ERK5 S496 phosphorylation, thereby accelerating atherosclerosis. Monocyte/macrophage p90RSK-ERK5 S496 phosphorylation could be a good target to prevent drugs-induced CV diseases.

Sonic Hedgehog mimetic prevents leukocyte infiltration into the CNS during acute HIV infection

Infiltration of infected leukocytes culminates in establishment of a brain niche for Human Immunodeficiency Virus (HIV) during acute phase of infection, initiating an ongoing cascade of persistent viral replication and inflammation, that causes irreversible neuronal injury and HIV associated neurocognitive disease (HAND). In this study, humanized mice were treated with Smoothened Agonist (SAG), a Sonic Hedgehog (Shh) mimetic in order to fortify blood brain barrier (BBB) and dampen leukocyte extravasation into CNS during AHI. Results indicate that SAG treatment reduced viral burden in the CNS immediately after HIV transmission, but also conferred extended neuroprotection via increased BBB integrity (elevated levels of tight-junction protein, Claudin 5, and reduced S100B levels in periphery). These mice also showed healthier neurons with thick, uniform dendrites and reduced numbers of activated astrocytes. Additional in vitro experiments suggested SAG treatment was not associated with the establishment or reversal of latency in the target cells. Altogether, these findings validate neuroprotective role of Shh signaling and highlight the therapeutic potential of Shh mimetics against CNS complications associated with HIV infection. Further our results strongly demonstrate that pharmacological interventions to reduce leukocyte mobilization during early HIV infection, can provide prolonged neuroprotection, which might significantly delay the onset of HAND.

Preventive and therapeutic challenges in combating Zika virus infection: are we getting any closer?

The neuroteratogenic nature of Zika Virus (ZIKV) infection has converted what would have been a tropical disease into a global threat. Zika is transmitted vertically via infected placental cells especially in the first and second trimesters. In the developing central nervous system (CNS), ZIKV can infect and induce apoptosis of neural progenitor cells subsequently causing microcephaly as well as other neuronal complications in infants. Its ability to infect multiple cell types (placental, dermal, and neural) and increased environmental stability as compared to other flaviviruses (FVs) has broadened the transmission routes for ZIKV infection from vector-mediated to transmitted via body fluids. To further complicate the matters, it is genetically similar (about 40%) with the four serotypes of dengue virus (DENV), so much so that it can almost be called a fifth DENV serotype. This homology poses the risk of causing cross-reactive immune responses and subsequent antibody-dependent enhancement (ADE) of infection in case of secondary infections or for immunized individuals. All of these factors complicate the development of a single preventive vaccine candidate or a pharmacological intervention that will completely eliminate or cure ZIKV infection. We discuss all of these factors in detail in this review and conclude that a combinatorial approach including immunization and treatment might prove to be the winning strategy.

Novel Antiplatelet Activity of Minocycline Involves Inhibition of MLK3-p38 Mitogen Activated Protein Kinase Axis

Platelets play an essential role in hemostasis and wound healing by facilitating thrombus formation at sites of injury. Platelets also mediate inflammation and contain several pro-inflammatory molecules including cytokines and chemokines that mediate leukocyte recruitment and activation. Not surprisingly, platelet dysfunction is known to contribute to several inflammatory disorders. Antiplatelet therapies, such as aspirin, adenosine diphosphate (ADP) antagonists, glycoprotein IIb/IIIa (GPIIb/IIIa) inhibitors, and anticoagulants such as warfarin, dampen platelet activity at the risk of unwarranted bleeding. Thus, the development of drugs that reduce platelet-mediated inflammation without interfering with thrombus formation is of importance to combat platelet-associated disorders. We have shown here for the first time that the tetracycline antibiotic, minocycline, administered to HIV-infected individuals reduces plasma levels of soluble CD40L and platelet factor 4 levels, host molecules predominately released by platelets. Minocycline reduced the activation of isolated platelets in the presence of the potent platelet activator, thrombin, as measured by ELISA and flow cytometry. Platelet degranulation was reduced upon exposure to minocycline as shown by mepacrine retention and flow cytometry. However, minocycline had no effect on spreading, aggregation, GPIIb/IIIa activation, or in vivo thrombus formation. Lastly, immunoblot analysis suggests that the antiplatelet activity of minocycline is likely mediated by inhibition of mixed lineage kinase 3 (MLK3)-p38 MAPK signaling axis and loss of p38 activity. Our findings provide a better understanding of platelet biology and a novel repurposing of an established antibiotic, minocycline, to specifically reduce platelet granule release without affecting thrombosis, which may yield insights in generating novel, specific antiplatelet therapies.

Platelet Activation in Human Immunodeficiency Virus Type-1 Patients Is Not Altered with Cocaine Abuse

Recent work has indicated that platelets, which are anucleate blood cells, significantly contribute to inflammatory disorders. Importantly, platelets also likely contribute to various inflammatory secondary disorders that are increasingly associated with Human Immunodeficiency Virus Type-1 (HIV) infection including neurological impairments and cardiovascular complications. Indeed, HIV infection is often associated with increased levels of platelet activators. Additionally, cocaine, a drug commonly abused by HIV-infected individuals, leads to increased platelet activation in humans. Considering that orchestrated signaling mechanisms are essential for platelet activation, and that nuclear factor-kappa B (NF-κB) inhibitors can alter platelet function, the role of NF-κB signaling in platelet activation during HIV infection warrants further investigation. Here we tested the hypothesis that inhibitory kappa B kinase complex (IKK) activation would be central for platelet activation induced by HIV and cocaine. Whole blood from HIV-positive and HIV-negative individuals, with or without cocaine abuse was used to assess platelet activation via flow cytometry whereas IKK activation was analyzed by performing immunoblotting and in vitro kinase assays. We demonstrate that increased platelet activation in HIV patients, as measured by CD62P expression, is not altered with reported cocaine use. Furthermore, cocaine and HIV do not activate platelets in whole blood when treated ex vivo. Finally, HIV-induced platelet activation does not involve the NF-κB signaling intermediate, IKKβ. Platelet activation in HIV patients is not altered with cocaine abuse. These results support the notion that non-IKK targeting approaches will be better suited for the treatment of HIV-associated inflammatory disorders.

Characterization of platelet-monocyte complexes in HIV-1-infected individuals: possible role in HIV-associated neuroinflammation

HIV-1-associated neuroinflammation persists even with effective combined antiretroviral therapy, and it is associated with the presence of activated monocytes/macrophages within the CNS. To infiltrate the CNS, monocytes transmigrate across the selectively permeable blood-brain barrier, which is compromised during HIV-1 infection. Interestingly, platelet-derived excess soluble CD40 ligand found in the plasma and cerebrospinal fluid of HIV-1-infected individuals with cognitive impairment has previously been implicated in increased blood-brain barrier permeability. In this study we show that soluble CD40 ligand also promotes the formation of complexes between inflammatory monocytes and activated platelets (PMCs), which are detected by flow cytometry as monocytes that express excess of CD61, a platelet marker, and that these complexes are increased in individuals with HIV-1 infection. PMCs exhibit an enhanced ability to adhere to human brain microvascular endothelial cells as compared with monocytes alone, and they migrate across the transendothelial barrier. These complexes can be found marginalized in the lumen of postcapillary venules in postmortem brain tissue derived from cases of HIV-1-associated encephalitis. The extravasation of monocytes across the brain endothelium may exacerbate neuroinflammation, indicating that enhancing this event via platelet interaction may be a contributing factor in the development of cognitive impairment. Thus, dampening platelet activation, and in turn PMC formation, with antiplatelet agents may prove beneficial in developing adjunctive therapies for use in combination with combined antiretroviral therapy in an effort to reduce HIV-1-associated neurologic deficit.

Excess soluble CD40L contributes to blood brain barrier permeability in vivo: implications for HIV-associated neurocognitive disorders

Despite the use of anti-retroviral therapies, a majority of HIV-infected individuals still develop HIV-Associated Neurocognitive Disorders (HAND), indicating that host inflammatory mediators, in addition to viral proteins, may be contributing to these disorders. Consistently, we have previously shown that levels of the inflammatory mediator soluble CD40L (sCD40L) are elevated in the circulation of HIV-infected, cognitively impaired individuals as compared to their infected, non-impaired counterparts. Recent studies from our group suggest a role for the CD40/CD40L dyad in blood brain barrier (BBB) permeability and interestingly, sCD40L is thought to regulate BBB permeability in other inflammatory disorders of the CNS. Using complementary multiphoton microscopy and quantitative analyses in wild-type and CD40L deficient mice, we now reveal that the HIV transactivator of transcription (Tat) can induce BBB permeability in a CD40L-dependent manner. This permeability of the BBB was found to be the result of aberrant platelet activation induced by Tat, since depletion of platelets prior to treatment reversed Tat-induced BBB permeability. Furthermore, Tat treatment led to an increase in granulocyte antigen 1 (Gr1) positive monocytes, indicating an expansion of the inflammatory subset of cells in these mice, which were found to adhere more readily to the brain microvasculature in Tat treated animals. Exploring the mechanisms by which the BBB becomes compromised during HIV infection has the potential to reveal novel therapeutic targets, thereby aiding in the development of adjunct therapies for the management of HAND, which are currently lacking.

Determination of lead and cadmium concentration limits in agricultural soil and municipal solid waste compost through an approach of zero tolerance to food contamination

Cadmium and lead are important environmental pollutants with high toxicity to animals and human. Soils, though have considerable metal immobilizing capability, can contaminate food chain via plants grown upon them when their built-up occurs to a large extent. Present experiment was carried out with the objective of quantifying the limits of Pb and Cd loading in soil for the purpose of preventing food chain contamination beyond background concentration levels. Two separate sets of pot experiment were carried out for these two heavy metals with graded levels of application doses of Pb at 0.4-150 mg/kg and Cd at 0.02-20 mg/kg to an acidic light textured alluvial soil. Spinach crop was grown for 50 days on these treated soils after a stabilization period of 2 months. Upper limit of background concentration levels (C(ul)) of these metals were calculated through statistical approach from the heavy metals concentration values in leaves of spinach crop grown in farmers' fields. Lead and Cd concentration limits in soil were calculated by dividing C(ul) with uptake response slope obtained from the pot experiment. Cumulative loading limits (concentration limits in soil minus contents in uncontaminated soil) for the experimental soil were estimated to be 170 kg Pb/ha and 0.8 kg Cd/ha. Based on certain assumptions on application rate and computed cumulative loading limit values, maximum permissible Pb and Cd concentration values in municipal solid waste (MSW) compost were proposed as 170 mg Pb/kg and 0.8 mg Cd/kg, respectively. In view of these limiting values, about 56% and 47% of the MSW compost samples from different cities are found to contain Pb and Cd in the safe range.

An assessment of municipal solid waste compost quality produced in different cities of India in the perspective of developing quality control indices

A study was conducted to investigate physico-chemical properties, fertilizing potential and heavy metal polluting potentials of municipal solid waste composts produced in 29 cities of the country. Results indicated that except a very few samples, all other samples have normal pH and EC. Organic matter as well as major nutrients N and P contents in MSW composts are generally low as compared to the composts prepared from rural wastes. Heavy metal contents in composts from bigger cities (>1 million population) were higher by about 86% for Zn, 155% for Cu, 194% for Cd, 105% for Pb, 43% for Ni and 132% for Cr as compared to those from smaller cities (<1 million population). Composts prepared from source separated biogenos wastes contained, on average, higher organic matter (by 57%), total N (by 77%) and total P (by 78%), but lower concentrations of heavy metals Zn (by 63%), Cu (by 78%), Cd (by 64%), Pb (by 84%), Ni (by 50%), and Cr (by 63%) as compared to those prepared from mixed wastes. Partial segregation at the site of composting did not improve quality of compost significantly in terms of fertilizing parameters and heavy metal contents. Majority of MSW composts did not conform to the quality control guideline of 'The Fertilizer (Control) Order 1985' in respect of total organic C, total P, total K as well as heavy metals Cu, Pb and Cr. In order to enable the relevant stakeholders to judge overall quality, a scheme has been proposed for the categorization of composts into different marketable classes (A, B, C, and D) and restricted use classes (RU-1, RU-2, and RU-3) on the basis their fertilizing potential and as well as potential for contaminating soil and food chain. Under the scheme, 'Fertilizing index' was calculated from the values of total organic C, N, P, K, C/N ratio and stability parameter, and 'Clean index' was calculated from the contents of heavy metals, taking the relative importance of each of the parameters into consideration. As per the scheme, majority of the compost samples did not belong to any classes and hence, have been found unsuitable for any kind of use. As per the regulatory limits of different countries, very few compost samples (prepared from source separated biogenos wastes) were found in marketable classes (A, B, C and D) and some samples (11-14) were found suitable only for some restricted use.

Blood gases, hematology, and renal blood flow during prolonged mountain sojourns at 3500 and 5800 m

BACKGROUND

This study mainly focused on renal blood flow, hematological parameters, blood gases, and blood pH, which are affected on exposure to moderate (3500 m) and extreme altitudes (5800 m) in sea level residents.

HYPOTHESIS

Acute and prolonged exposure to high or extreme altitude may cause pathophysiological changes in kidney and renal plasma/blood flow, leading to retention of fluids in the tissues. Combined with the decreased availability of oxygen to the tissues, these may be responsible for high altitude maladies.

METHOD

Fifteen male sea level (SL) volunteers, 22-25 yr old, were studied for blood gases, blood viscosity, hematocrit, hemoglobin concentration, and effective renal blood/plasma flow at Delhi (260 m), 3500 m (60 d stay), 5800 m (70 d stay), and 7 d after return to SL.

RESULTS

Compared with SL, a significant increase from 7.34 to 7.43 (p < 0.01) in blood pH was observed at 3500 m that remained significantly increased at 5800 m. PO2 was about 39% less at 5800 m than at SL. PCO2 reduced significantly from 42.07 to 28.05 mm Hg on return from 5800 m to SL. The blood viscosity increased significantly (38%) at 5800 m and decreased significantly by 38% (p < 0.01) after return to SL. The effective renal plasma flow reduced significantly (p < 0.01) from 615.6 at SL to 381.5 ml x min(-1) x 1.73 m(-2) at 5800 m.

CONCLUSION

The study suggests a crucial role of renal function in the acclimatization process; renal function also appears to be one factor by which the body protects itself against severe hypoxia.

Long-term effects of intercropping and bio-litter recycling on soil biological activity and fertility status of sub-tropical soils

On-farm field experiments were carried out at two sites having 38- and 10-year-old orchard cropping systems under sub-tropical climatic regions to evaluate changes in organic carbon accumulation and chemical and microbiological properties of the soils. Under a system of different intercropped fruit trees, the cultivation of coconut (Cocos nucifera L.) intercropped with guava (Psidium guajava L.) enhanced the soil microbial activity approximately 2-fold after 38 yrs over 10 yrs of the same intercropped system. Soil organic carbon increased from 3.4 to 7.8 and 2.4 to 6.2 g kg-1 after 38 and 10 yrs, respectively, following the establishment of orchards. The increase was attributed to greater recycling of bio-litters. Levels of dehydrogenase, phosphatase and soil microbial biomass under field conditions generally depended more on the nature of the cropping system than on soil types. Similarly, average carbon inputs of bio-litter to the soil in monocrop (0.98 Mg ha-1 yr-1) was less than intercropped fruit trees (2.07 Mg ha-1 yr-1). The average level of soil microbial biomass carbon was 1158 kg ha-1 (0-0.15 m depth) and the organic carbon turnover rate was 8.5 yr-1 after 38 yrs of intercropped fruit trees, which resulted in a lower ratio (1.81) of carbon inputs to soil microbial biomass carbon.

Effect of time exposure to high altitude on zinc and copper concentrations in human plasma

BACKGROUND

Research has focused mainly on the relationship of zinc and copper contents and physical stresses like running, cycling, etc. It has also been reported that other forms of stresses change the concentration of these trace elements in humans. However,there are no reports on the effects of high altitude induced hypoxic stress on the plasma levels of these metals. Since hypoxia is one of the important stresses, we considered it appropriate to observe the changes in the levels of zinc and copper concentrations and in certain related zinc and copper enzymes and hormones in the plasma of human volunteers on acute induction to high altitude. From these findings, we intended to ascertain whether supplementation of these trace elements would be required for optimal health under such conditions.

HYPOTHESIS

On acute induction to hypoxia, contents of these trace elements may change as the requirements of stressed organs and tissue may increase. Hence, further supplementation may be beneficial under hypoxic stress for better adaptability.

METHOD

Volunteers were divided into two groups: with and without zinc and copper salt supplementation. Blood samples were collected at sea level and on induction to acute hypoxia on days 3 and 10. Trace mineral contents and their related enzyme (alkaline phosphatase) and hormone (ceruloplasmin) levels were determined in plasma samples.

RESULTS

Plasma zinc contents were significantly reduced upon induction to high altitude in the non-supplemented group, but not in the zinc-supplemented group. Alkaline phosphatase activity increased significantly upon induction to the high altitude stress. The enzyme activity remained elevated up to day 10 of the stress. Plasma copper contents and ceruloplasmin activity did not change upon induction to high altitude.

CONCLUSION

Under hypoxic stress, circulating levels of zinc and alkaline phosphatase in plasma changed appreciably as plasma zinc was transported into the organs and tissues. However, circulating levels of copper and ceruloplasmin in plasma did not change, indicating no extra supplementation of copper is required under hypoxic stress.

Improved high altitude hypoxic tolerance and amelioration of anorexia and hypophagia in rats on oral glutamate supplementation

BACKGROUND

The objective of this study is to evaluate the efficacy of oral glutamic acid supplementation in promoting hypoxic tolerance.

METHODS

The experiments were conducted in albino rats by exposing them to three levels of hypoxia in a simulated environment for varying periods of time. The parameters studied include: gasping time at 35,000 ft (10,668 m), food and water intake, and heart to body weight (b.w.) ratio at 25,000 ft (7620 m), tolerance to composite stress at 15,000 ft (4572 m) and biodistribution of glutamate (glu).

RESULTS

Supplementation of Glu (27 mg x kg(-1) b.w.) as glutamic acid dissolved in normal saline resulted in 4.8 times enhanced hypoxic tolerance (time taken for appearance of first gasp), 23% body weight gain and 24% increase in food consumption over control during hypoxia. When animals were subjected to composite stress of cold, hypoxia and restraint (CHR), the Glu fed animals showed higher resistance to fall in rectal temperature than the control group. Hypoxia significantly enhanced heart to body weight ratio compared with control, and Glu supplementation reduced and brought it down to that of control.

CONCLUSION

The study reveals that Glu in optimal doses may be a conditionally essential amino acid resulting in enhanced tolerance to hypoxia and cold.

Tyrosinase transfection produces melanin synthesis and growth retardation in glioma cells

Tyrosinase is the key enzyme in melanin biosynthesis in pigmented cells. We transfected 9L rat glioma cells with human tyrosinase cDNA that had been cloned in a high expression vector. Stable transfectants were selected by their resistance to the antibiotic G418. More than a dozen G418-resistant clones were isolated and were screened for tyrosinase expression using dopa-oxidase activity. The clone with the highest tyrosinase activity was selected and expanded for further studies. Northern blot analyses of total RNA from cells showed that the transfected cells had relatively more tyrosinase transcript than SK-MEL-23 human melanotic melanoma cells. The melanin content of the transfected cells was dependent on the concentration of L-tyrosine in the culture medium. In addition, the growth of transfected cells was inhibited when grown in a medium containing high concentrations of L-tyrosine. These results suggest that tyrosinase activity is cytotoxic in a substrate-dependent manner. This may have far reaching therapeutic use for glioma tumours.

Nuclear factor 1 is essential for the expression of stearoyl-CoA desaturase 1 gene during preadipocyte differentiation

Stearoyl CoA desaturase gene 1 (SCD1) is a delta 9 desaturase that is transcriptionally activated during the differentiation of 3T3-L1 preadipocytes into adipocytes. We have demonstrated that a SCD1/BP region in SCD1 proximal promoter (-114 to -86 bp) is essential for the transcriptional activation of this gene during differentiation. Mutation in this region abolished the basal activity of the proximal promoter of SCD1, and also failed to induce transcription in response to the differentiation cocktail in transfected cells. The SCD1/BP region contains a TGGCA sequence at -90 bp from the transcription start site. Using competitor oligonucleotides and nuclear factor 1 (NF1)-specific antibodies in gel shift assays, we have shown that in preadipocytes, a NF1 protein binds to this TGGCA sequence. On MDI-induced differentiation of preadipocyte into adipocyte, an additional DNA-protein complex appeared. The appearance of a new NF1 complex is related to the differentiation-specific transcriptional activation of the SCD1 gene. This is the first report to show a differentiation-related change in NF1 protein binding during preadipocyte differentiation.

Inhibition of connexin 43 synthesis by antisense RNA in rat glioma cells

The 9L rat glioma cells communicate via gap junctions which are formed of connexin 43. The gap junctional communication was inhibited in these cells by transfecting them with an antisense Cx43 DNA construct, and its effect on their growth rate was investigated. This construct was induced by a Zn(2+)-inducible metallothionein promoter. Results showed that the induction of antisense RNA expression in rat 9L glioma cells produced the loss of gap junctions which was reflected in the loss of gap junctional communication. By inducing the antisense construct with zinc acetate, and using specific antibodies to connexin 43, the synthesis of this connexin was inhibited in the transfected cells and gap junctions were lost on the cell-cell appositions. There was no such effect on the untransfected cells. The loss of gap junctions at cell-cell appositions also correlated with the loss of Lucifer yellow fluorescent dye transfer between the cells. The effect of loss of gap junctions on the growth rate of the cells was assessed. In spite of the drastic decrease in the number of gap junctions between cells, their growth rate was only approximately 20% less than that of the transfected but non-induced cells. Therefore, gap junction communication is not negatively related to the rate of growth of these cells.

Gap junctions in 9L and C6 glioma cells: correlation with growth characteristics

The relationship between growth properties and gap junctional communication properties of two glioma cell lines, 9L and C6, was compared. Using microinjection of a gap junction permeable fluorescent dye, it was demonstrated that 9L cells were extensively dye coupled through gap junctions, whereas C6 cells had low levels of dye coupling between the cells. More gap junctions were observed between 9L cells than between C6 cells both by electron microscopy and immunofluorescent labelling with specific antibodies. Immunoblotting and immunofluorescence labelling of cellular proteins from 9L and C6 cells also showed differences in the Cx43 connexin contents of these cells, reflecting the differences in their gap junctional communication. Northern blot analyses confirmed that the level of Cx43 mRNA was higher in 9L than in C6 cells. In spite of these differences in gap junctions, the two cell lines did not differ in their growth rates in cultures. These results suggest a lack of direct correlation between gap junctional communication and cell growth regulation in these two glioma cell lines.

Influence of vanadium on acclimatization of humans to high altitude

The study was conducted on human volunteers as controls as well as after administration of vanadyl sulphate on induction to high altitude (HA) at 3500 m. The plasma vanadium contents were significantly reduced in the control group on abrupt induction to HA on days 3 and 10, indicating redistribution to other organs/tissues under the stressful situation. In the vanadium salt-treated group, plasma vanadium contents were similar to those obtained at sea-level. Administration of vanadyl sulphate did not act as a diuretic. Moreover the vanadium supplemented group drank more water and also excrete less urine than the control group.

A STUDY OF EPIDEMIOLOGICAL ASPECTS OF BURN INJURIES

A study was conducted of the epidemiological aspects of 500 fresh cases of burns during the period February to August 1989. Women in the reproductive age group from the lower socioeconomic strata were the most frequently victims (52.8%). Four hundred and thirteen (82.5%) patients sustained accidental burns, 62 (12.4%) were suicidal and 25 (5%) homicidal. Majority (72%) of the accidents occurred as a consequence of garments catching fire. Though most of the subjects wore cotton garments, mortality was higher among those wearing synthetic fabric. Low socioeconomic conditions, overcrowding in the house, floor-level cooking, unsafe cooking appliances and the prevalent clothing pattern stand out prominently as risk factors for burn injury.

Effect of yogic exercises on thyroid function in subjects resident at sea level upon exposure to high altitude

Using radioactive iodine, the effect of 1 month's yogic exercises has been investigated on the thyroid function of subjects resident at sea level (SL) specially after their exposure to high altitude (HA). The results have been compared with a group of SL subjects who underwent physical training (PT) exercises for the same duration. Ten healthy male volunteers in the age range of 20-30 years were used as test subjects in this study with each serving as his own control. The subjects were randomly divided into two groups of 5 each. One group practised hatha yogic exercises, while the other group performed the regular PT exercises. The thyroidal accumulation and release of radioactive iodine have been measured in each of the subjects of both groups before and after 1 month of their respective exercises at SL. One month of yogic exercises at SL has been observed to cause a significant reduction in the trans-thyroidal availability of radioiodine. The thyroid radioactivity in this group of subjects was always below normal levels with the exception of two peaks of radioactive iodine uptake, when the levels of radioactivity in the thyroid were similar to the control values of pre-yogic exercises. The release of radiolabel at 24-48 h was significantly increased after yogic exercises. In contrast, the subjects performing PT exercises for the same duration at SL showed significant thyroid uptake of radioactive iodine at 24 h. Subsequently their 131I uptake continued to rise slowly until 72 h without any demonstrable thyroidal release of radiolabel. This indicated that increased thyroid activity was induced by conventional PT exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Changes in body fluid compartments during hypohydration and rehydration in heat-acclimated tropical subjects

Body fluid compartments at different levels of graded hypohydration and partial rehydration were determined using radiotracers in 28 heat-acclimated, male volunteers from tropical regions of India, in hot dry conditions in a climatic chamber. These subjects were hypohydrated to varying degrees (i.e., 1%, 2%, 3%, and 4% body mass deficit) by moderate work in hot conditions in a climatic chamber maintained at 45 degrees C dry bulb temperature and 30% relative humidity. Rehydration study was carried out only in those subjects who were hypohydrated to 3% and 4% body mass and who were brought back to 2% level of hypohydration by receiving a calculated amount of water. Up to the 2% level of hypohydration, a major contribution towards sweat loss was observed from the interstitial fluid (ISF) compartment. At higher levels of hypohydration, no further significant loss from ISF was seen, though significant losses in intracellular fluid (ICF) and plasma volume (PV) were apparent. The present study also found that at the 4% hypohydration level, a maximum fluid contribution was met by the ICF compartment. Significant increases observed in sweat K+ at 3 and 4% also indicate the ICF mobilization, which is rich in K+ ions. On partial rehydration, the ISF compartment held the repletion fluid in excess, and was found to be enough to restore sweat rate to euhydration level. This study clearly indicates that sudorific gain is achieved with partial restoration alone in subjects hypohydrated to 3 and 4% levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Thyroidal handling of radioiodine in sea level residents exposed to hypobaric hypoxia

In the present investigation thyroidal accumulation of radioiodine and its release were assessed by direct testing of thyroid function using radioactive iodine, in vivo, in sea level residents intermittently exposed to hypobaric hypoxia. Thyroidal accumulation of radioiodine and its turnover were examined daily for 14 days. Twelve healthy human male volunteers were divided into three groups, with an equal number of individuals in each group. A decompression chamber was used to expose each group of subjects to hypoxic conditions at a simulated altitude of 3810 m for 8 h/day for 14 days. An oral dose of 25 mu Ci iodine-131 was administered to each individual of the first group immediately before the initiation of intermittent hypoxia. The second group of subjects received a tracer dose at the beginning of the 4th day of the 14 days, intermittent exposure to hypoxia, while the third group received the tracer dose 1 week after the completion of the exposure. Control studies were carried out on the subjects before they were subjected to the experimental conditions. Thyroidal accumulation of 131I in experimental subjects during the hypoxic state and in the post-hypoxic state was higher than in the control studies. The pattern of accumulation during exposure to hypoxia and in the post-hypoxic state showed multiple peaks of radioactive iodine uptake (PRAIU), a unique feature. The multiple PRAIU by the thyroid in experimental subjects were sharp and of short duration, reflecting an increased rate of 13I release from the thyroid. Control subjects had a single PRAIU by the thyroid 24 h after the administration of tracer.

Changes in plasma volume during hypohydration and rehydration in subjects from the tropics

Plasma volume (PV) at different levels of hypohydration was determined using radio-iodinated serum albumin-125 in 28 heat acclimated male volunteers in hot dry condition in a climatic chamber. The heat acclimated subjects were hypohydrated to varying degrees i.e. 1%, 2%, 3% and 4% body mass deficit by moderate work in hot conditions in a climatic chamber maintained at 45 degrees C dry bulb temperature and 30% relative humidity. A rehydration study was carried out in only those subjects who were hypohydrated to 3% and 4% body mass and they were brought back to a 2% level of hypohydration by giving a calculated amount of water. A significant decrease in PV was observed at 3% and 4% hypohydration only. The magnitude of the decrease was the same in both the groups and not related to the level of hypohydration. With partial rehydration in the 3% hypohydrated group PV was restored fully, while in the 4% hypohydrated group restoration was incomplete, indicating that at this hypohydration level some of the replenished water that entered in plasma may have moved to the intracellular compartment which may have contributed more at 4% hypohydration. It is suggested that with higher levels of thermal hypohydration significant reduction in the intracellular compartment may result in accentuated physiological strain during work in the heat.

Variations in skinfold thickness during de-acclimatisation and re-acclimatisation to high altitude. Relation to body fat content

Skinfold thickness, body weight, body water, anthropometric measurements and segment volumes were determined in 28 young and healthy Indian soldiers on return to Delhi (200 m) after staying for more than 24 months at high altitude (3500 m). The measurements were made on the 2nd day and after 3 weeks. Ten subjects were then randomly selected from this group and returned by air to the high-altitude station, and the measurements were repeated on the 3rd and 12th day of their reinduction. Though body weight and total body water increased marginally on transfer to the lower altitude, body density remained more or less unchanged. There were significant increases in the thickness of skinfolds, even when body density had increased. During this period hand and foot volumes decreased significantly. Despite significant increases in thoracic skinfold thickness, the torso volume decreased slightly. On returning to high altitude, the soldiers lost body weight, were hypohydrated and showed reduced skinfold thickness. Fat losses calculated on the basis of reduction in skinfold thickness were far in excess of those calculated from losses in body weight and in total body water. As the reduced skinfold thickness was unrelated to changes in body water content at high altitude, it seems that such reductions are due to redistribution of blood in the skin. From the results of these investigations it is concluded that variations in skinfold thickness during acclimatisation to high altitude do not accurately represent the changes in body fat content.

A new radiopharmaceutical for gallbladder studies: 99mTc-Sn-LIDA complex

A simple method for the preparation of 99mTc-Sn-LIDA complex is described. Organ distribution and blood clearance studies in animals are reported. This complex has also been used successfully in more than 50 patients for assessing gallbladder function.

99mTc-Sn-acetylcysteine: a new renal scanning agent

A new radiopharmaceutical, 99mTc-Sn-acetylcysteine, for renal scanning is reported. The preparation is simple and quick. It can also be adopted in the kit form. The complex has the advantage of great stability and fast clearance over earlier reported renal scanning radioagnostic agents.

Time factor as a prognostic indicator on the Bender-Gestalt test

Z-scores from Bender-Gestalt records of 62 psychiatric in- and outpatients were computed. The patients were put on active treatment, and a psychiatric rating was done to evaluate therapeutic recovery after a period of 19 to 24 months. These patients were grouped into three categories, i.e., patients with low Z-scores and good therapeutic recovery; patients with high Z-scores and poor therapeutic recovery; patients with low Z-scores who still showed poor response to treatment. Total time taken by each patient to reprduce the BG designs was noted as well. Results indicate that Z-score was a significant prognostic indicator for schizophrenics, affective psychotics, organic psychotics and patients who were suffering from anxiety and conversion reactions, but not for obsessive compulsive neurotics. Time taken for BG reproductions proved to be an important prognostic indicator, as patients who did not respond satisfactorily to the treatment took significantly more time than those who responded well to treatment. Hence, time taken by the patients for BG reproductions also needs to be considered when any predictions are made with regard to therapeutic outcome.