The aging HIV/AIDS population: fragile social networks.

Social support becomes an increasingly critical resource for people as they age. In New York City, 25% of all people living with HIV/AIDS are over age 50, and 64% are over age 40. This study sample (n=160) reflects current HIV/AIDS epidemiology, with 34% females and 89% people of color. This study provides a detailed profile of this growing, aging cohort and their social networks. Our study finds this growing group of aging adults is isolated from informal networks due to the stigma of HIV/AIDS and ageism. Typically, partners and family members are key sources of informal support, but only 1/3 of respondents had a partner and 71% lived alone. This group relies heavily on friends, many of whom are also HIV-positive. Participants were in primary care and many (86%) utilized Medicaid. The fragile networks of these older adults will be challenged by age-related comorbidities. Without traditional caregivers, these aging adults with HIV/AIDS will have an immense impact on healthcare delivery and community-based programs.

Cortical cell plasma membrane alterations after in vitro alcohol exposure: prevention by GM1 ganglioside.

Using choleratoxin/antitoxin immunohistochemistry, this study examined the effects of in vitro alcohol exposure on the morphology of cell plasma membranes in mixed fetal rat cortical cultures, and assessed the neuroprotective effects of exogenous monosialoganglioside (GM1). Gangliosides are involved in critical biological functions, including maintenance of membrane integrity. Plasma membranes are directly affected by alcohol exposure through multiple mechanisms. Results indicate that exposure to alcohol altered plasma membrane morphology as assessed by staining for the surface distribution of membrane GM1. Pretreatment with endogenous GM1 ameliorated the alcohol-induced alterations.

In utero ethanol exposure retards growth and alters morphology of cortical cultures: GM1 reverses effects.

Ethanol, a developmental neurotoxin, alters plasma membranes' physicochemical properties affecting embryogenesis, cell migration, differentiation, and synaptogenesis. In a previous study using a model for fetal alcohol effects, GM1 ganglioside treatment was shown to reduce ethanol-induced accumulation of endogenous GM1 and fatty acid ethyl esters in rat fetuses. The present study was initiated to define further the in utero effects of ethanol and the capacity of GM1 treatment to ameliorate such effects. Wistar dams were exposed to ethanol (intragastrically) on gestation day (GD) 7 and GD8 and GD13 and GD14. GM1 ganglioside (10 mg/kg, im) was given 24 hr before ethanol administration. Cortical cultures were derived from GD15 and GD20 fetuses. GM1, which is highly localized on the cellular plasma membrane outer surface of CNS cells, was used as a marker molecule to assess cell integrity. Cholera toxin/antitoxin/fluorescence immunohistochemistry was used to localize GM1. Results indicate that the brief in utero exposure to ethanol affected cell growth and morphology. A marked retardation of cell development and arborization was observed as early as 24 hr after plating. Ethanol-exposed cells evidenced considerably altered GM1 localization. Such alterations likely reflect losses of membrane integrity. These in utero ethanol-induced pathologies are remarkably diminished in cultures derived from ethanol-exposed fetuses of dams treated with GM1.

GM1 ganglioside treatment of spontaneously hypertensive stroke prone rats.

Many reports indicate that GM1 ganglioside is effective in reducing CNS ischemic injury in animal models. These models employ invasive surgery to induce ischemic damage in otherwise healthy animals. The purpose of this study was to determine if the beneficial effects of GM1 could be generalized to Spontaneously Hypertensive Rats-Stroke Prone (SHRSP). The SHRSP strain develops a pathology similar to those observed in patients with stroke. The SHRSP have "risk" factors that include hypertension, fibrinoid necrosis, and sensitivity to diet. Female SHRSP were randomly assigned to GM1- or saline-treatment conditions. Rats were fed a stroke-inducing diet. Daily body weights, weekly blood pressure, time of stroke onset, and age at death were recorded. Spontaneous activity and performance on a tail-hang test were assessed thrice weekly. The results indicate that GM1 treatment did not delay the time of stroke onset or death. GM1 did reduce hyperactivity in the initial stages of the ischemic pathology, but did not prevent the marked decline in behavioral activity observed at later time points. There were no differences in weight loss, performance on the tail-hang test, or number of CNS injury-related symptoms observed. These findings suggest that GM1 was not as effective in decreasing mortality, weight loss, or behavioral deficits in SHRSP as previously reported using other animal models of ischemia. Distinguishing between those animal models in which GM1 is more and less effective may be useful in determining under which clinical situations GM1 is likely to be most suitable.

Traumatic injury of spinal cord cells in vitro reduced by GM1 ganglioside.

GM1 ganglioside (monosialoganglioside) is a significant endogenous component of central nervous system (CNS) cellular membranes, thereby contributing to the membranes' integrity and function. Exogenous gangliosides have been shown to be incorporated into plasma membranes and can exert neuroprotective effects on damaged neuronal tissue(s). An in vitro method of physical injury (trauma) previously described which used cultures derived from fetal mouse spinal cord [38] was adapted for these studies in order for us to assess GMl's neuroprotective efficacy. Injury was induced by uniformly crosshatching the spinal cell cultures with a 1 mm plastic pipette tip. The extent of injury and the effects of GM1 ganglioside posttreatment (80 µM) was assessed after 48 h by measuring lactate dehydrogenase (LDH) released and by observing changes in the plasma membrane surface distribution of endogenous GM1 using cholera toxin/antitoxin/fluorescent antibody immunohistochemistry. A gradient of injury, from the zone of maximum injury to partially traumatized or non-injured areas, was seen using immunohistochemistry. The primary injury zone in this gradient was characterized by areas of swollen or dead cells and abnormal or degenerating cell processes. At further distances, cells were observed to be nearly normal, with intact fibers. This gradient of injury may reflect proximate (at the locus of trauma) and distant effects of the release of neurotoxic levels of endogenous glutamate (Glu) and other excitatory amino acids. Ganglioside GM1 treatment resulted in a significantly reduced (>75%) release of LDH as well as enhanced cell and process integrity indicative of reduced tissue injury. These initial results indicate that GMl's previously documented neuroprotective effects using neuronal culture systems can be generalized to injured spinal cells in vitro wherein there is evidence for preservation (rescue) of cellular plasma membranes after injury as reflected by reduced cell loss, swelling, and process degeneration, as well as decreased LDH release.

GM1 ganglioside reduces glutamate toxicity to cortical cells. Lowered LDH release and preserved membrane integrity.

As an in vitro model of CNS excitatory amino acid (EAA) injury, rat cortical neuronal cultures were challenged with glutamate (0.5 or 10 mM) and the levels of released lactate dehydrogenase (LDH) were monitored at 1 h, 1, 2, and 7 d. LDH release is correlated with levels of plasma membrane damage. GM1 has been shown to be continuously distributed on the outer surface of CNS cellular membranes. By staining for the distribution of endogenous GM1 ganglioside using cholera toxin/antitoxin immunohistochemistry, we were able to assess morphologically cellular plasma membrane integrity after damage. We used these two measures (LDH and GM1 localization) to study the neuroprotective effects of exogenous GM1 ganglioside to further elucidate its mechanism. Cortical cultures derived from 15-d rat fetuses were subjected to the glutamate challenge for 30 min. Parallel cultures were either pre- or post-treated with 80 microM of GM1. Exposure to 10 mM glutamate caused a highly significant increase in LDH release at 1-48 h. Pretreatment with GM1 reduced the release, whereas posttreatment reduced the LDH release even more. Plasma membrane changes observed by the GM1 immunohistochemistry reflected the LDH release data. All cultures treated with GM1 evidenced substantial structural integrity (continuous staining of GM1 along perikarya and processes) as compared to untreated cultures. These data support our hypothesis that GM1 treatment (pre- and post-) reduces plasma membrane damage.

Monosialoganglioside (GM1) restores membrane fatty acid levels in ischemic tissue after cortical focal ischemia in rat.

Using a consistent, reproducible and reliable cortical focal ischemia in rat (permanent unilateral occlusion of the left middle cerebral artery & the ipsilateral common carotid artery [MCAo + CCAo] with a 1 h temporary occlusion of the contralateral CCA), the levels of four major membrane fatty acids (palmitic, C16:0; stearic, C18:0; Oleic, C18:1 and arachidonic, C20:4) were analyzed at 3, 36 and 72 h, and 2 and 4 wk following ischemia to determine the critical point of irreversibility of the cellular plasma membrane disorganization in primary ischemic (Area 1, parietal cortex) and peri-ischemic (Area 2, tempero-occipital cortex) areas. The cortical focal ischemia resulted in time dependent differential loss in four of these major membrane fatty acids. The quantitative differences among primary and peri-ischemic areas reflected the different degree of ischemic injury inflicted to these regions. Acute treatment with ganglioside GM1 protected the further losses of all of these fatty acids and differentially restored their levels in these various injury sites over periods of time. The changes in levels of these membrane fatty acids indicate that the primary ischemic area suffers an irreversible injury and peri-ischemic area suffers reversible injury. After acute treatment (< 2 h) with ganglioside GM1, a partial recovery was observed in primary ischemic area and complete recovery was observed in peri-ischemic areas. These studies support the hypothesis that, ischemia leads to a irreversible plasma membrane disorganization which underlies the eventual cell death, and protection and restoration of these membrane changes by drugs, such as ganglioside GM1 leads to neuroprotection against ischemic injury.

Temporal changes in superoxide dismutase, glutathione peroxidase, and catalase levels in primary and peri-ischemic tissue. Monosialoganglioside (GM1) treatment effects.

Time-dependent changes in levels of the antioxidant enzymes, superoxide dismutase (SOD), glutathione peroxidase (GSHPOD), and catalase (CAT) after cortical focal ischemia in rat indicate that: (1) primary and peri-ischemic tissues differ in both rate and the magnitude of oxyradical-induced ischemic injury, and (2) ischemic tissue remains vulnerable to oxyradical damage as long as 72 h after ischemia since the antioxidant enzyme levels remain at or below basal levels. After 72 h, the increased levels of these enzymes are sufficient to protect tissue against oxyradical damage. GM1 ganglioside (10 mg/kg, im) further increased the already elevated levels of the enzymes after ischemia, thereby indicating the GM1 treatment increases the capacity of ischemic tissue to protect against oxyradical injury.

Loss and recovery of activities of alpha+ and alpha isozymes of (Na(+) + K+)-ATPase in cortical focal ischemia: GM1 ganglioside protects plasma membrane structure and function.

Alterations in cellular membrane structure and the subsequent failure of its function after CNS ischemia were monitored by analyzing changes in the plasma membrane marker enzyme (Na(+) + K(+)-ATPase. The levels of two isozymes of (Na(+) + K(+)-ATPase, alpha+ and alpha, which have distinct cellular and anatomical distributions, were studied to determine if differential cellular damage occurs in primary and peri-ischemic injury areas. The efficacy of monosialoganglioside (GM1) treatment was assessed, since this glycosphingolipid has been shown to reduce ischemic injury by protecting cell membrane structure/function. Using a rat model of cortical focal ischemia, levels of both ATPase isozyme activities were assayed in total membrane fractions from primary ischemic tissue (parietal cortex) and three peri-ischemic tissue areas (frontal, occipital, and temporal cortex) at 1, 3, 5, 7, and 14 days after ischemia. No significant loss of either isozyme's activity occurred in any tissue area at 1 day after ischemia. At 5 days, in the primary ischemic area, both isozyme activity levels decreased by 70-75%. The alpha+ enzyme activity loss persisted up to 14 days, while a 17% recovery in alpha activity occurred. In the three peri-ischemic tissue areas, enzyme activity losses ranged from 42%-59% at 3 days after ischemia. A complete restoration of both isozyme activities was seen at 14 days. After three days of GM1 ganglioside treatment there was no loss of total (Na*+) + K(+)-ATPase activity in the three peri-ischemic areas, and a significantly reduced loss in the primary infarct tissue. An autoradiographic analysis of brain coronal sections using 3H-ouabain supports the enzymatic data and GM1 effects. Reductions in 3H-ouabain binding in all cortical layers at 3 days after ischemia were visualized. GM1 treatment significantly reduced these 3H-ouabain binding losses. In summary, time-dependent quantitative changes in activity levels of ATPase isozymes (alpha+ and alpha) reflect the different degree of membrane damage that occurs in primary vs. peri-ischemic tissues (e.g., irreversible vs. reversible membrane damage), and that ischemia affects cell membranes of all neural elements in a largely similar fashion. GM1 ganglioside was found to reduce plasma membrane damage in all CNS cell types.

Temporal changes in edema, Na+, K+, and Ca++ in focal cortical stroke: GM1 ganglioside reduces ischemic injury.

Cortical focal ischemia in the rat was induced by middle cerebral artery occlusion (MCAo) together with permanent occlusion of the ipsilateral common carotid artery (CCAo) and a temporary (1 hr) occlusion of the contralateral CCA. By using a defined cortical tissue sampling procedure at 3, 6, 24, 72, 96, and 120 hr after the MCAo + CCAo, patterns of edema and ion (Na+, K+, and Ca++) changes in a primary and three peri-ischemic cortical areas are described. Ionic imbalances and edema formation have distinct patterns, are time dependent, and are different when comparing primary and peri-ischemic areas. Calcium increases to "neurotoxic" levels appear temporally independent of edema formation, reaching magnitudes 20 times greater than basal levels in the primary infarct area. Na+ increases correlate with increases in water, while K+ losses do not appear to be directly related to edema formation of Na+ and Ca++ increases. K+ losses are only significant in the primary infarct area. Rats treated with GM1 ganglioside (10 mg/kg, i.m.) daily showed significant reductions in edema, Na+ and Ca++ increases. These ganglioside effects were evident as early as 24 hr after the ischemic injury. Ca++ increases, which was maximal at 72 hr after the ischemic injury, was reduced by greater than 50% in GM1-treated animals. The mechanism by which GM1 is an effective neuroprotective agent may be evidenced by its effects on Ca++ influx/efflux processes in injury.

Enhanced recovery of learned alternation in ganglioside-treated rats after unilateral entorhinal lesions.

The present study demonstrates that an abbreviated regimen of ganglioside treatments attenuates the behavioral impairments produced by unilateral lesions of the entorhinal cortex. Ganglioside treatments not only accelerate recovery of learned alternation on a Y-maze, but also reduce total errors and perseverative errors.

GM1 ganglioside reduces cognitive dysfunction after focal cortical ischemia.

The functional consequences of cortical focal ischemia and the effect of monosialoganglioside (GM1) treatment on learning/performance of a spatial reversal task were investigated. Cortical focal ischemia was induced by a permanent occlusion of the left common carotid artery and the ipsilateral middle cerebral artery, with a 1-h clamping of the contralateral carotid artery. Twenty-six rats were randomly assigned to three groups: sham controls, a saline-treated ischemic group, and a GM1 ganglioside-treated ischemic group (10 mg/kg/day: IM). Fifteen days after surgery rats were trained on a spatial reversal task in a two-lever operant chamber where food reward was contingent on lever pressing. Training continued from day 15 to day 21 after surgery. Cortical focal ischemia resulted in learning/performance deficits that were reduced by GM1 ganglioside treatment. The cognitive deficits were characterized by a significantly higher number of nonperseverative errors and number of responses to criterion. There was a significant difference between left and right lever performance in the saline-treated ischemic group, which was absent in shams and GM1-treated ischemic rats. On all measures GM1-treated rats were not different from sham controls.

Ganglioside reduction of ischemic injury.

Systemically administered gangliosides have been shown to be pharmacologically effective in reducing injury and facilitating recovery after CNS damage in various animal paradigms. Very recent work has indicated that ganglioside therapy following CNS ischemia in animals and in humans causes reductions in the extent of injury (acute phase) and enhanced neurological recovery (long-term effects). These studies are reviewed, and the possible mechanisms (i.e., the protection of plasma membrane integrity/function and the modulation of trophic factors) by which gangliosides protect against and reduce brain injury are discussed.

GM1 ganglioside treatment after global ischemia protects changes in membrane fatty acids and properties of Na+, K+-ATPase and Mg2+-ATPase.

An examination was made of the effects of ganglioside GM1 (i.m.) on the losses of membrane fatty acids (palmitic, stearic, oleic, linoleic, and arachidonic), the plasma membrane enzyme Na+, K+-ATPase, and the mitochondrial membrane enzyme Mg2+-ATPase, associated with global ischemia 24 hr after permanent unilateral occlusion of the carotid artery in Mongolian gerbils. While there was a significant loss of fatty acids in saline controls, no loss was detected in membranes from GM1-injected gerbils. Rather, we found an increase in membrane fatty acid content, indicative of altered turnover. A 38% loss of Na+, K+-ATPase and a 36% loss of mitochondrial Mg2+-ATPase observed in membranes from saline controls was reduced in membranes from GM1-injected animals to losses of 15% and 8% respectively. These effects are further described by analyses of enzyme kinetics (apparent Vmax and apparent Km). After 1 week of storage, the activities of both membrane ATPases from saline controls decreased substantially more than from GM1-injected animals, suggesting that the GM1 membranes were better "preserved." Since there was a minimal loss in protein content after 24 hr of ischemia, these results indicate that systemically injected GM1 may protect structure and function of plama membranes during the acute phases of ischemic injury.

GM1 ganglioside protects nucleus basalis from excitotoxin damage: reduced cortical cholinergic losses and animal mortality.

Ten days after bilateral injections of ibotenic acid into the nucleus basalis, rats injected daily (i.m.) with ganglioside GM1 were protected from anterograde degeneration of cholinergic projections to the fronto-lateral cortex. This protection was reflected by reduced losses (associated with ibotenic acid lesions) of cortical acetylcholinesterase, choline acetyltransferase, and lowered animal mortality.

Haloperidol alters rat CNS cholinergic system: enzymatic and morphological analyses.

Chemical and morphological changes in cholinergic marker enzymes, acetylcholinesterase (AChE), and choline acetyltransferase (ChAT) of striatum, hippocampus, and cerebral cortex were studied following haloperidol treatment of rats. After short-term (7-21 days) haloperidol treatment, the levels of both enzymes (AChE and ChAT) were increased in striatum and hippocampus (greater than 25%), but not in cortex. After long-term (+40 days) haloperidol treatment, the level of AChE activity returned to control levels in all brain areas, whereas the levels of striatal and hippocampal ChAT decreased by 26% and 29%, respectively. No change in levels of both enzymes was detected after acute treatment (single dose) of haloperidol or chronic treatment with either clozapine or imipramine. Morphological analysis of cholinergic neurons and their processes using monoclonal antibody to ChAT showed two types of changes following 40 days of haloperidol treatment. First, parallel to the observed decrease in the levels of ChAT activity there was a visual decrease in the immunoreactivity in neurons as well as in their processes in striatum and hippocampus. Second, there was an apparent reduction in the size and number of stained neurons and their processes. No changes were seen in immunoreactivity after an acute treatment with haloperidol. These results indicate that the chronic haloperidol treatment in rats causes changes in central cholinergic systems that may be relevant to the pathophysiology of schizophrenia and its treatment.