HIV virions and HIV infection in vitro are unaffected by human granzymes A and B

Granzymes are a family of serine proteinases commonly found in the granules of CD8+ T cells. In HIV infection, CD8+ cells show cytotoxic and noncytotoxic antiviral activities. The latter is mediated, at least in part, by a secreted CD8+ cell antiviral factor, CAF. Because of the antiviral nature of CD8+ cells, we examined the potential anti-HIV activity of free granzymes that can be found in CD8+ cell culture fluids. Pretreatment of CD4+ T cells with granzyme A or granzyme B had no effect on their susceptibility to infection with HIV, nor did incubation of the granzymes with HIV virions alter their infectivity. Continuous culture of acutely infected CD4+ T cells with granzyme A or B showed no effect on cell viability or the replication of HIV. The findings of this study suggest that free granzymes do not control HIV infection and spread in CD4+ T cells.

Treatment of human immunodeficiency virus infection with hydroxyurea, didanosine, and a protease inhibitor before seroconversion is associated with normalized immune parameters and limited viral reservoir

Current treatments for human immunodeficiency virus (HIV) require uninterrupted drug administration because they are unable to reconstitute the immune response and do not affect the viral reservoir. Ten patients were treated during acute HIV infection before complete Western blot (WB) seroconversion with the combination of hydroxyurea, didanosine, and indinavir. This treatment was associated with the normalization of some immune parameters and functions. No loss of naive CD4 T lymphocytes was observed, and recovery of up to 35% of naive CD8 T lymphocytes occurred in several weeks. A vigorous HIV-specific T helper response (stimulation index >8) was observed in 7 of 8 patients treated before complete WB seroconversion but in only 1 of 5 controls treated after seroconversion. In addition, a limited latent viral reservoir (<0.02-0.5 infectious units/106 cells) was documented in quiescent peripheral blood lymphocytes after treatment initiated before complete WB seroconversion.

A transgenic mouse model to analyze CD8(+) effector T cell differentiation in vivo

Antigen-specific effector T cells are prerequisite to immune protection, but because of the lack of effector cell-specific markers, their generation and differentiation has been difficult to study. We report that effector cells are highly enriched in a T cell subset that can be specifically identified in transgenic (T-GFP) mice expressing green fluorescent protein (GFP) under control of the murine CD4 promoter and proximal enhancer. Consistent with previous studies of these transcriptional control elements, GFP was strongly and specifically expressed in nearly all resting and short-term activated CD4(+) and CD8(+) T cells. However, when T-GFP mice were challenged with vaccinia virus, allogeneic tumor cells, or staphylococcal enterotoxin A, the cytotoxic and IFN-gamma-producing T cells lost GFP expression. Upon T cell receptor (TCR) ligation by alphaCD3, sorted GFP(+) cells fluxed calcium and proliferated vigorously. In contrast, GFP(-) effector cells showed a diminished calcium flux and did not proliferate. Instead, they underwent apoptosis unless supplied with exogenous IL-2. By reverse transcription-PCR analysis, the GFP(-) cells up-regulated the pro-apoptotic molecule, Fas-L, and down-regulated gene expression of the proximal TCR signaling molecule, CD3zeta, and c-jun, a component of the AP-1 transcription factor. Thus, differential regulation of TCR signaling may explain the divergent responses of naïve and effector T cells to antigen stimulation.

Viral-specific cytotoxic T lymphocytes lyse human immunodeficiency virus-infected primary T lymphocytes by the granule exocytosis pathway

Cytotoxic T lymphocytes (CTL) lyse antigen-bearing target cells by two distinct pathways. Whereas granule exocytosis targets any antigen-bearing cell, fas-mediated cytotoxicity kills only fas-expressing cells and does not require antigen expression. Fas pathway activation can potentially lead to lysis of uninfected bystander cells. We examined the relative usage of the two pathways by CTL clones and cell lines directed against four different human immunodeficiency virus (HIV) proteins in lysing primary HIV-infected targets. Although fas was expressed on HIV-infected primary CD4(+) T cells, their lysis by antigen-specific CD8(+) CTL was only by the granule pathway. Fas ligand (fasL) was not detectable on antigen-specific CD8 clones, T-cell lines, or circulating HIV-specific CD8 T cells from HIV-infected donors, stained with a tetrameric HLA-A2-HIV-peptide complex. FasL expression by HIV-specific CTL clones was not activated by exposure to HIV-presenting cells, but was after unphysiological stimulation with phorbol myristate acetate (PMA). CTL clones did not lyse bystander Jurkat cells, but HIV-infected primary CD4(+) T cells lysed uninfected bystander cells by the fas-mediated pathway. These results suggest that HIV-specific CD8(+) CTL do not cause HIV immunopathology by lysing bystander cells. On the contrary, fas-mediated lysis of uninfected cells by HIV-infected cells may contribute to CD4 decline.

Hydroxyurea and didanosine long-term treatment prevents HIV breakthrough and normalizes immune parameters

Hydroxyurea and didanosine treatment suppressed HIV replication for more than 2 years, in the absence of viral breakthrough, in chronically infected patients. The profile of viral load reduction was unusual for a two-drug combination, since a continuous gradual decrease in viremia persisted despite residual viral replication. The increase in CD4+ T cell counts was not robust. However, unlike those of patients treated by other therapies, CD4+ T lymphocytes were functionally competent against HIV, mediating a vigorous HIV-specific helper T cell response in half of these patients. In addition, the percentages of naive CD4+ and CD8+ T lymphocytes were not different from those in uninfected individuals. These results demonstrate that prolonged antiretroviral therapy with a simple, well-tolerated combination of two affordable drugs can lead to sustained control of HIV, normalization of immune parameters, and specific anti-HIV immune response.

Perforin is not co-expressed with granzyme A within cytotoxic granules in CD8 T lymphocytes present in lymphoid tissue during chronic HIV infection

BACKGROUND

Residual HIV-1-infected cells are poorly eliminated from lymphoid tissue (LT) reservoirs by effector cytotoxic T lymphocytes (eCTL) despite antiretroviral therapy. Perforin and granzyme A (grA) constitute major effector molecules within eCTL granules that induce apoptosis and lysis of virally infected cells.

OBJECTIVE

Expression of perforin and grA was studied at the single cell level in LT and blood from 16 patients infected with HIV-1 (stage A1-C) who were not taking antiretroviral therapy.

METHOD

Immunohistochemical analysis by in situ imaging of cells from blood and LT.

RESULTS

Quantitative in situ imaging showed that perforin-expressing CD8 T cells comprised 0.3-1.5% of total cells within the LT from recent HIV-1 seroconverters, while grA was found in 2.1-7.2% of total cells. However, despite high-level grA upregulation (1.5-4.5% of total cells) compared with that in non-infected individuals (0.4-0.9%), perforin expression remained low (< 0.1% of total cells) (P < 0.02) in LT from patients with chronic HIV-1 infection (stage A2-C). This contrasted with findings in peripheral blood mononuclear cells (PBMC) from the same HIV-1 infected cohort where perforin was detected in 13-31% of all PBMC, which was 10- to 100-fold higher than in lymphoid tissue (P < 0.001); grA was found in 14-32% of total PBMC. Two-colour staining showed that granular expression of perforin and grA was restricted to CD8 T cells in over 90% of total cells in both LT and blood.

CONCLUSIONS

These findings indicate that cytotoxic perforin expression is impaired at local sites of HIV replication within lymphoid tissue. Since perforin is required together with grA for granule-mediated cytolysis, the low perforin expression in the LT may limit the ability of eCTL to eliminate HIV-1 infected cells in lymphoid tissue.

Expansion of CD57 and CD62L-CD45RA+ CD8 T lymphocytes correlates with reduced viral plasma RNA after primary HIV infection

OBJECTIVE

CD8 T cells, expressing cell surface molecules distinct from those on resting and naive T cells, are increased in HIV infection. The association of increased CD38 and human leukocyte antigen DR (HLA-DR) CD8 T cells with poor prognosis has suggested that activated CD8 T cells may aggravate HIV infection. We examined whether other immunological parameters might influence the viral setpoint.

DESIGN

Peripheral T cells from nine untreated patients, obtained after primary HIV infection when plasma HIV had stabilized, were examined for proteins expressed in activated versus resting, memory versus naive, and cytolytic versus non-cytolytic T cells.

METHODS

The proportion of CD8 T cells that stain for CD38 and HLA-DR, CD28 and CD57 was compared with plasma viraemia and CD4 cell count. These parameters were also compared with the proportion of CD4 and CD8 T cells that express CD62L and CD45RA, present on naive cells and down-modulated in memory cells. Internal staining for the cytotoxic protein granzyme A was also examined.

RESULTS

An increase in CD38 and CD38 HLA-DR CD8 T cells correlated with increased plasma viral RNA (P < 0.00002, P < 0.03, respectively). An increase in CD8 T cells expressing granzyme A was associated with lower CD4 cell counts (P < 0.04). However, the expansion of CD57 and CD62L CD45RA+ CD8 T cells was associated with a lower viral setpoint (P < 0.01, P < 0.02, respectively).

CONCLUSION

Phenotypically defined activated CD8 T cells may have different functions in HIV infection. Activated CD8 T cells that are CD57 or CD62L(-)CD45RA+ may be beneficial, because their expansion in untreated patients correlates with a reduced viral setpoint after primary infection.

Clonal expansion of antigen-specific CD8+ cytotoxic T lymphocytes is regulated by late exposure to serum to prevent apoptosis

Although serum-free media have been used to expand lymphokine-activated killer cells, antigen-specific CD8 T cell cytotoxicity does not develop in vitro in the absence of serum. The immunodominant Vbeta17 response to an influenza A matrix protein epitope restricted by HLA A2.1 was used to study the serum requirement for CTL activation. Serum acts directly on T cells and not indirectly by activating APCs. In the absence of serum, the initial steps of T cell activation, including expression of CD69 and CD25, are unimpaired and some antigen-specific cytotoxicity may be generated in the first few days after stimulation. However, expression of late activation markers, such as HLA-DR and CD38, and clonal expansion of class I-restricted antigen-specific CTL does not occur if CTL are not exposed to serum within 4 days of antigen exposure. The antigen-specific CTL, but not unstimulated bystander T cells, undergo apoptosis if they are not exposed to serum within a few days of activation. Apoptosis of TCR-activated CTL does not appear to be Fas-mediated since it is not blocked by inhibiting the Fas pathway. Therefore, late exposure to an unidentified serum protein regulates the clonal expansion of TCR-activated CD8 CTL.

Immune restoration by combination of a cytostatic drug (hydroxyurea) and anti-HIV drugs (didanosine and indinavir)

Cell activation is essential for HIV infection. CD4+ T lymphocyte activation allows virus replication and CD8+ T lymphocyte activation may contribute to pathogenesis. We combined hydroxyurea, a cytostatic drug that inhibits cell activation and proliferation, with two drugs that inhibit HIV (didanosine and indinavir), to block the "cell activation-virus production-pathogenesis" cycle. HIV was strongly suppressed in treated patients, and the average CD4 count increased to 224/mm3. Compared with a matched group of patients who had declined antiretroviral treatment, treated patients had a significantly lower proportion of activated CD8+ T lymphocytes and a significantly higher number of naive CD8+ and CD4+ T lymphocytes. The proliferative responses to allogeneic and influenza virus antigens were increased in treated patients, and a defect in CD3-zeta expression, the signaling chain of the T cell receptor complex, was reversed. The use of a cytostatic drug was not detrimental to the immune system; on the contrary, the combination of antiviral and cytostatic treatment improved all of the immune parameters tested.

Analysis of genome-wide CAG/CTG repeats, and at SEF2-1B and ERDA1 in schizophrenia and bipolar affective disorder

A shift towards larger CAG/CTG triplet repeats and schizophrenia (SCZ) and bipolar affective disorder (BPAD) has been detected by several recent studies, using the Repeat Expansion Detection (RED) technique, however no specific loci have been shown to be responsible for this shift. Further analyses by our group of RED (CTG)10 ligation products amongst an extended sample of patients and comparison with controls matched for age, sex and ethnicity show no significant differences in distribution (P= 0.23, n=95; P=0.93, n=91, for SCZ and BPAD respectively). Alleles at two recently discovered unstable trinucleotide repeat loci at 18q21.1 (SEF2-1B) and 17q21.3 (ERDA1) have also been analysed in affecteds and matched controls. We observed no increase in frequency of larger alleles (>37 repeats) in affected individuals at SEF2-1B (BPAD: P=0.95, n= 100; SCZ: P=0.61, n=97) or at ERDA1 (BPAD: P= 0.4, n = 101; SCZ: P= 0.05, n = 151, with larger alleles more frequent in controls). Our findings suggest that larger CAG/CTG repeats at these loci are neither major contributory factors to the etiology of psychosis, nor in linkage disequilibrium with a gene that is. Furthermore, when the RED results were compared to allele sizes at SEF2-1B and ERDA1, it was observed that a majority of SCZ, BPAD and control individuals with large RED products had a large allele at either or both sites (78% for RED products > or =270 bp; 62% for RED products > or =180 bp).

Granzyme A loading induces rapid cytolysis and a novel form of DNA damage independently of caspase activation

Cytotoxic lymphocytes trigger apoptosis by releasing perforin and granzymes (Grn). GrnB activates the caspase apoptotic pathway, but little is known about GrnA-induced cell death. Perforin was used to load recombinant GrnA and GrnB and enzymatically inactive variants into target cells. GrnA induces single-strand DNA breaks that can be labeled with Klenow polymerase and visualized on alkaline gels. GrnA-induced DNA damage but not cytolysis requires GrnA proteolysis. GrnA-induced membrane perturbation, nuclear condensation, and DNA damage are unimpaired by caspase blockade. GrnA fails to induce cleavage of caspase-3, lamin B, rho-GTPase, or PARP. GrnA-induced cytotoxicity and cleavage of PHAP II, a previously identified GrnA substrate, are unimpaired in Jurkat cells that overexpress bcl-2. Therefore, GrnA activates a novel apoptotic pathway.

Mitochondria-dependent and -independent regulation of Granzyme B-induced apoptosis

Granzyme B (GraB) is required for the efficient activation of apoptosis by cytotoxic T lymphocytes and natural killer cells. We find that GraB and perforin induce severe mitochondrial perturbation as evidenced by the release of cytochrome c into the cytosol and suppression of transmembrane potential (Deltapsi). The earliest mitochondrial event was the release of cytochrome c, which occurred at the same time as caspase 3 processing and consistently before the activation of apoptosis. Granzyme K/perforin or perforin treatment, both of which kill target cells efficiently but are poor activators of apoptosis in short-term assays, did not induce rapid cytochrome c release. However, they suppressed Deltapsi and increased reactive oxygen species generation, indicating that mitochondrial dysfunction is also associated with this nonapoptotic cell death. Pretreatment with peptide caspase inhibitors zVAD-FMK or YVAD-CHO prevented GraB apoptosis and cytochrome c release, whereas DEVD-CHO blocked apoptosis but did not prevent cytochrome c release, indicating that caspases act both up- and downstream of mitochondria. Of additional interest, Deltapsi suppression mediated by GraK or GraB and perforin was not affected by zVAD-FMK and thus was caspase independent. Overexpression of Bcl-2 and Bcl-XL suppressed caspase activation, mitochondrial cytochrome c release, Deltapsi suppression, and apoptosis and cell death induced by GraB, GraK, or perforin. In an in vitro cell free system, GraB activates nuclear apoptosis in S-100 cytosol at high doses, however the addition of mitochondria amplified GraB activity over 15-fold. GraB- induced caspase 3 processing to p17 in S-100 cytosol was increased only threefold in the presence of mitochondria, suggesting that another caspase(s) participates in the mitochondrial amplification of GraB apoptosis. We conclude that GraB-induced apoptosis is highly amplified by mitochondria in a caspase-dependent manner but that GraB can also initiate caspase 3 processing and apoptosis in the absence of mitochondria.

The dentition of Abraham's people. Why Abraham left Mesopotamia

Ancient Mesopotamia (southern Iraq) in 2000 B.C. was the home of the biblical figure Abraham and his people. An analysis of skeletal material from cemeteries in the ancient cities of Ur (birthplace of Abraham) and Kish shows a homogeneous, short-lived population that suffered severe dental attrition (95 percent of inhabitants), periodontal disease (42 percent) and caries (two percent). Many oral congenital and neoplastic lesions were noted Skeletal (dental) evidence indicates the population suffered from extensive disease and nutritional deficiency. Of special note was a possible case of endodontic treatment. The people of Abraham had modern dentition but relatively poor dental health. It is probable that Abraham, if in truth he existed, left Mesopotamia because of the threat of famine, as evidenced by biblical record, geologic strata and dental analysis.

Striatal enlargement in rats chronically treated with neuroleptic

BACKGROUND

Striatal enlargement with chronic neuroleptic treatment in schizophrenic patients has been reported by several investigators. Longitudinal magnetic resonance imaging studies of patients suggest that changes in striatal volume may be caused by treatment with antipsychotic medication.

METHODS

We have examined the effects of chronic neuroleptic treatment on postmortem striatal volume in the laboratory rat and have examined the relationship between striatal volume and vacuous chewing movements (VCMs). Autoradiographs of 50 rats treated with haloperidol (1.5 mg/kg/day) or drug free for varying durations of time (1-12 months) were utilized in this analysis.

RESULTS

Chronic treatment with neuroleptics (1 month or greater) was associated with larger striatal volumes. The increase in striatal volume was present at 1 month of treatment and was sustained to 12 months of treatment. Rats that developed the high-VCM syndrome had larger striatal volumes than both drug-free and low-VCM rats, while low-VCM rats had larger striatal volumes than drug-free rats.

CONCLUSIONS

These data suggest that chronic neuroleptic treatment is the cause of striatal enlargement in the laboratory rat, and that this enlargement is most prominent in rats that have the high-VCM syndrome.

Effects of clozapine on auditory event-related potentials in schizophrenia

BACKGROUND

Schizophrenia is associated with cognitive deficits that are an intrinsic component of the disorder. Clozapine is an atypical antipsychotic that is superior to typical agents in the treatment of positive symptoms. The degree to which clozapine ameliorates cognitive deficits, however, is still controversial. Mismatch negativity (MMN), N200 (N2), and P300 (P3) are cognitive event-related potentials (ERPs) that index preattentive (MMN) and attention-dependent information processing (N2, P3) and provide a measure of cognitive deficits associated with schizophrenia. In schizophrenic patients deficient generation of MMN, N2, and P3 has been observed, suggesting impairments of discrete stages of information processing.

METHODS

This study investigates the effects of clozapine treatment on MMN, N2, and P3 generation. Patients were recruited from a haloperidol-controlled, double-blind treatment study of clozapine in chronic schizophrenia. ERPs were obtained at the beginning of the study and after 9 weeks (4 patients) and 16 weeks (13 patients) of treatment.

RESULTS

Clozapine treatment was associated with a significant increase of P3 amplitude, which was not observed in the haloperidol group; however, clozapine treatment did not affect deficits in MMN and N2.

CONCLUSIONS

These findings suggest that clozapine--in contrast to conventional antipsychotics--improves electrophysiological measures of attention-dependent information processing, but does not ameliorate preattentive deficits.

Effective lysis of HIV-1-infected primary CD4+ T cells by a cytotoxic T-lymphocyte clone directed against a novel A2-restricted reverse-transcriptase epitope

Most HIV-specific cytotoxic T-lymphocyte (CTL) epitopes have been identified using peptide-pulsed and recombinant vaccinia virus-infected targets. These systems may not accurately reflect the ability of epitopes to be presented by HIV-infected T cells. Recent studies suggest, in fact, that some CTL epitopes are poorly presented on HIV-infected cells. In this study, we have identified a novel A2.1-restricted HIV reverse-transcriptase (RT) epitope and investigated the presentation of this epitope by HIV-infected primary CD4+ T cells and T-cell lines. A CD8+ CTL clone, isolated from a seropositive subject that recognized a novel A2-restricted epitope KYTAFTIPSI (aa 293-302) in RT, was used for these studies. Primary CD4+ T cells and the CD4+ T-cell line T1 were infected with virus from T1-nPLAP, a cell line stably transfected with HXB-nPLAP, a molecular construct of HIV linked to a placental alkaline phosphatase (PLAP) marker gene. A uniformly infected cell population, obtained by immunomagnetic selection for PLAP expression, was used as targets in CTL assays. HIV-infected T cells were lysed by CTL recognizing this RT epitope as effectively as peptide-pulsed targets. This suggests that some RT epitopes are good targets for CTL recognition.

A role for heat shock protein 27 in CTL-mediated cell death

CTL exocytosis of granules containing perforin and granzyme proteases induces apoptotic cell death. Either granzyme A or B can act with perforin to trigger apoptosis. Granzyme B activates a ubiquitous apoptotic cascade induced by caspase cleavage, but the granzyme A pathway is largely unknown. Using affinity chromatography with recombinant mutant inactive granzyme A, we previously isolated two granzyme A-binding proteins, PHAP (putative HLA-associated protein) I and II. PHAP II, a substrate of granzyme A, is degraded within minutes of CTL attack. Two additional cytoplasmic proteins of 27 and 53 kDa bind strongly to the mutant granzyme A column, requiring 6 M urea to elute. Sequencing identified these as the monomer and dimer of hsp27, a small heat shock protein up-regulated by stress and cellular activation. Hsp27 coprecipitates with granzyme A from cytoplasmic lysates and is not a substrate of the enzyme. Hsp27 translocates to the detergent-insoluble fraction of target cells and relocalizes from diffuse cytoplasmic staining to long filamentous fibers, especially concentrated in a perinuclear region, within minutes of CTL attack. Hsp27 may participate in morphologic changes during granule-mediated lysis. Low or absent levels of hsp27 expression in T lymphocytes, even after heat shock, may play a role in CTL resistance to granule-mediated lysis.

Emerging roles for novel antipsychotic medications in the treatment of schizophrenia

Antipsychotic medications are the mainstay of treatment for schizophrenia. The recent advent of atypical antipsychotics has provided new clinical options and set higher expectations for the treatment of schizophrenia. It is not yet clear how each different drug will fit within the therapeutic armamentarium and this lack is most evident with considering patients with treatment refractory schizophrenia. On the other hand, the expectation of superior efficacy, more benign side effect profile and potential to impact the longitudinal course of schizophrenia provide a rationale for the use of novel antipsychotics as a first-line treatment of schizophrenia.

Expression and purification of enzymatically active recombinant granzyme B in a baculovirus system

Granzyme B (GranB), a serine protease stored in the granules of cytotoxic T lymphocytes and natural killer cells, can initiate target cell apoptosis. To produce large amounts of purified active enzyme, recombinant murine granzyme B (rGranB) was expressed from baculovirus in insect cells. The expressed rGranB is secreted into the culture medium and can be readily purified to homogeneity by one-step affinity chromatography to yield 1.5 mg enzyme per liter insect cell medium. RGranB is recognized by a GranB-specific anti-peptide antibody and is active against synthetic substrate Boc-Ala-Ala-Asp-SBzl with kinetic constant (kcat/Km 45,000 M-1s-1) comparable to purified human GranB, RGranB processes the caspase pro-CPP32 into its enzymatically active form and induces DNA fragmentation in isolated nuclei in the presence of cytosolic factors. The ability to express enzymatically active rGranB using the baculovirus system will help elucidate the role of this granzyme in the immune response.

Human cardiovascular and metabolic response to acute, severe isovolemic anemia

CONTEXT

Although concern over the risks of red blood cell transfusion has resulted in several practice guidelines for transfusion, lack of data regarding the physiological effects of anemia in humans has caused uncertainty regarding the blood hemoglobin (Hb) concentration requiring treatment.

OBJECTIVE

To test the hypothesis that acute isovolemic reduction of blood Hb concentration to 50 g/L in healthy resting humans would produce inadequate cardiovascular compensation and result in tissue hypoxia secondary to inadequate oxygen transport.

DESIGN

Before and after interventional study.

SETTING

Academic tertiary care medical center.

PARTICIPANTS

Conscious healthy patients (n =11) prior to anesthesia and surgery and volunteers not undergoing surgery (n=21).

INTERVENTIONS

Aliquots of blood (450-900 mL) were removed to reduce blood Hb concentration from 131 (2) g/L to 50 (1) g/L [mean (SE)]. Isovolemia was maintained with 5% human albumin and/or autologous plasma. Cardiovascular parameters, arterial and mixed venous oxygen content, oxyhemoglobin saturation, and arterial blood lactate were measured before and after removal of each aliquot of blood. Electrocardiogram and, in a subset, Holter monitor were monitored continuously.

MAIN OUTCOME MEASURES

"Critical" oxygen delivery (TO2) as assessed by oxygen consumption (VO2), plasma lactate concentration, and ST changes on electrocardiogram.

RESULTS

Acute, isovolemic reduction of Hb concentration decreased systemic vascular resistance and TO2 and increased heart rate, stroke volume, and cardiac index (each P<.001). We did not find evidence of inadequate oxygenation: VO2 increased slightly from a mean (SD) of 3.07 (0.44) mL of oxygen per kilogram per minute (mL O2 x kg(-1) x min[-1]) to 3.42 (0.54) mL O2 x kg(-1) x min(-1) (P<.001) and plasma lactate concentration did not change (0.81 [0.11] mmol/L to 0.62 [0.19] mmol/L; P=.09). Two subjects developed significant ST changes on Holter monitor: one apparently related to body position or activity, the other to an increase in heart rate (at an Hb concentration of 46-53 g/L); both occurred in young women and resolved without sequelae.

CONCLUSIONS

Acute isovolemic reduction of blood Hb concentration to 50 g/L in conscious healthy resting humans does not produce evidence of inadequate systemic TO2, as assessed by lack of change of VO2 and plasma lactate concentration. Analysis of Holter readings suggests that at this Hb concentration in this resting healthy population, myocardial ischemia would occur infrequently.

Circulating CD8 T lymphocytes in human immunodeficiency virus-infected individuals have impaired function and downmodulate CD3 zeta, the signaling chain of the T-cell receptor complex

Although human immunodeficiency virus (HIV)-infected subjects without acquired immunodeficiency syndrome have a high frequency of HIV-specific CD8 T lymphocytes, freshly isolated lymphocytes frequently lack detectable HIV-specific cytotoxicity. However, this effector function becomes readily apparent after overnight culture. To investigate reasons for T-cell dysfunction, we analyzed T-cell expression of the cytolytic protease granzyme A and CD3 zeta, the signaling component of the T-cell receptor complex. An increased proportion of CD4 and CD8 T cells from HIV-infected donors contain granzyme A, consistent with the known increased frequency of activated T cells. In 28 HIV-infected donors with mild to advanced immunodeficiency, a substantial fraction of circulating T cells downmodulated CD3 zeta (fraction of T cells expressing CD3 zeta, 0.74 +/- 0.16 v 1.01 +/- 0.07 in healthy donors; P < .0000005). CD3 zeta expression is downregulated more severely in CD8 than CD4 T cells, decreases early in infection, and correlates with declining CD4 counts and disease stage. CD3 zeta expression increases over 6 to 16 hours of culture in an interleukin-2-dependent manner, coincident with restoration of viral-specific cytotoxicity. Impaired T-cell receptor signaling may help explain why HIV-specific cytotoxic T lymphocytes fail to control HIV replication.

Safety of autologous, ex vivo-expanded human immunodeficiency virus (HIV)-specific cytotoxic T-lymphocyte infusion in HIV-infected patients

We infused six human immunodeficiency virus (HIV)-seropositive subjects with autologous CD8+ cytotoxic T cells (CTLs) enriched for HIV-specific cytotoxicity targeted against a diversity of HIV epitopes in gp120, gag p17 and p24, and nef. There was no toxicity and no subject deteriorated clinically. In the first 2 weeks, CD4 counts increased for all subjects and plasma viremia decreased in five of six subjects. Twenty-four weeks later, the mean values of all measures of viral burden and surrogate markers of HIV infection were either unchanged or improved, but none of the changes was statistically significant. Two subjects continued to have decreased cell-associated viral burden and another subject had more than doubled CD4 cell count. HIV-specific CTL activity increased in most subjects. The increase in CD4 T-cell counts in the first weeks after the infusion suggests that antiviral CTLs of diverse specificities do not play a significant role in CD4 T-cell decline. The lack of any acute toxicity or adverse effect on viral burden suggests that therapy with antiviral CTLs deserves further study.

Recombinant human granzyme A binds to two putative HLA-associated proteins and cleaves one of them

The release of cytotoxic granule contents by cytotoxic T lymphocytes triggers apoptotic target cell death. Cytotoxic granules contain a pore-forming protein, perforin, and a group of serine proteases called granzymes. We expressed human granzyme A in bacteria as a proenzyme capable of in vitro activation by enterokinase. The recombinant activated enzyme has catalytic activity against substrates with Arg, preferably, or Lys at the P1 position, comparable to trypsin. An enzymatically inactive recombinant granzyme A, with the active site Ser mutated to Ala, was produced and used with affinity chromatography to identify potential substrates. Two granzyme A-binding cytoplasmic proteins of molecular mass 33 and 44 kDa were isolated and identified by tryptic fragment sequencing as PHAP I and II, ubiquitous putative HLA-associated proteins, previously coisolated by binding to an HLA class II peptide. PHAP II forms an SDS-stable complex with recombinant mutant granzyme A and coprecipitates with it from cytoplasmic extracts. PHAP II, either purified or in cell lysates, is cleaved by the recombinant enzyme at nanomolar concentrations to a 25-kDa fragment. PHAP II begins to be degraded within minutes of initiation of cytotoxic T lymphocyte attack. PHAP I and II are candidate participants in the granzyme A pathway of cell-mediated cytotoxicity.

Tumor necrosis factor constellation polymorphism and clozapine-induced agranulocytosis in two different ethnic groups

Genes of the major histocompatibility complex (MHC) are associated with susceptibility to different immune and nonimmune mediated diseases. We had reported that the drug adverse reaction, clozapine-induced agranulocytosis (CA), is associated with different HLA types and HSP70 variants in Ashkenazi Jewish and non-Jewish patients, suggesting that a gene within the MHC region is associated with CA. This study was designed to find common genetic markers for this disorder in both ethnic groups. The tumor necrosis factor (TNF) microsatellites d3 and b4 were found in higher frequencies in both Jewish and non-Jewish patients: 51 of 66 (77%) and 48 of 66 (57%), respectively. Comparisons of these frequencies with those of controls, 28 of 66 (42%) and 18 of 66 (27%), were statistically significant (corrected P value = .001 for the d3 allele and .0005 for the b4 allele). On the other hand, the TNF microsatellite b5 was underrepresented in the group of patients, 9 of 66 (14%), when compared with the control subjects, 43 of 66 (65%) (corrected P value = .0005), probably related to protection from CA. Our results show a strong association of some genetic variants of the TNF loci with susceptibility to CA in two different ethnic groups suggesting involvement of TNF and/or associated gene(s) products in the pathogenesis of this hematologic-drug adverse reaction.

Small simulated polyps in pig colon: sensitivity of CT virtual colography

PURPOSE

The authors evaluated computed tomographic (CT) virtual colography for the detection of simulated polyps under ideal conditions, as well as the effects on lesion conspicuity of (a) collimation, (b) table pitch, and (c) orientation of the colon lumen with respect to the gantry.

MATERIALS AND METHODS

Pig colon was resected and cleansed, and polyps with diameters of 3, 7, and 10 mm were created. Each specimen was scanned with collimation of 5 and 7 mm and table pitch of 1.0, 1.6, and 2.0 at angles of 0 degrees, 45 degrees, and 90 degrees to the gantry. The initial two-dimensional (2D) images were reconstructed at 1-mm intervals (2D reconstructions), from which three-dimensional (3D) virtual colography images were generated. Polyp conspicuity on the initial and reconstructed 2D images and the 3D reconstructions was evaluated on a three-point scale: 0 = polyp not depicted, 1 = polyp faintly depicted, and 2 = polyp clearly depicted.

RESULTS

The 10-mm-diameter polyp was clearly depicted (grade 2 conspicuity) on every initial and reconstructed 2D image and 3D reconstruction without regard to collimation, table pitch, or angle to the gantry. The 7-mm-diameter polyp was clearly depicted (grade 2 conspicuity) on every initial and reconstructed 2D image, but conspicuity on 3D reconstructions varied as the imaging parameters varied. The 3-mm-diameter polyp was faintly depicted (grade 1 conspicuity) on the initial and reconstructed 2D images and 3D reconstructions, but conspicuity varied on the 3D reconstructions as the imaging parameters varied.

CONCLUSION

CT virtual colography helped detection of small mucosal polyps regardless of the angle of the colon lumen to the gantry at which they were obtained.

Recognition of a small number of diverse epitopes dominates the cytotoxic T lymphocytes response to HIV type 1 in an infected individual

Mitogen-activated T cell lines may be reproducibly used to identify relatively conserved HIV-1 epitopes that dominate CTL recognition of HIV-infected cells. Using a combination of nested truncations of HIV-vaccinia recombinants encoding HIV-1LAI Env and overlapping peptides that span the coding regions of the HIV-1 SF2 subclone of env, gag, nef, rev, and tat, we have mapped the immunodominant, relatively conserved CTL epitopes recognized by 25 HIV-seropositive individuals with CD4 counts between 100 and 500/mm3 and no history of AIDS opportunistic infection. We could characterize at least 1 peptide CTL epitope recognized by the T cell lines of 18 of 25 of the subjects; the T cell lines from 2 additional subjects recognized HIV-vaccinia presenting targets, but no dominant peptide epitope was identified. CTL epitopes were most frequently encoded by gag (recognized by 16 of 25 patient T cell lines), followed by nef and env (11 of 25 each), and the RT region of pol (9 of 25). Tat and Rev were rarely the sites of CTL epitopes. The identified epitopes occurred predominantly in relatively conserved regions of HIV-1. The mean number of HIV peptides identified at a single time for each cell line was 2.7 +/- 1.7. Although no single peptide dominated CTL recognition in more than four individuals, clusters of epitopes were found in the N-terminal region of gp160 and in two central regions of Nef. The dominant HIV-1 CTL epitopes in infected patients were not predictable on the basis of MHC expression and varied widely in an MHC-diverse population.

Effects of methylphenidate on regional brain glucose metabolism in humans: relationship to dopamine D2 receptors

OBJECTIVE

The authors' goals were to determine whether baseline dopamine activity contributes to response to methylphenidate and to assess the pattern of metabolic responses associated with enhanced dopamine activity.

METHOD

They used positron emission tomography with 2-deoxy-2[18F]fluoro-D-glucose to evaluate the effects of two sequential doses of methylphenidate on brain metabolism in 15 healthy subjects. Dopamine D2 receptor availability was measured with [11C]raclopride to evaluate its relation to methylphenidate-induced metabolic changes.

RESULTS

Methylphenidate increased brain metabolism in six subjects, decreased it in two, and did not change it in seven; however, it consistently increased cerebellar metabolism. Methylphenidate significantly increased "relative" (region relative to the whole brain) metabolism in the cerebellum and decreased it in the basal ganglia. Regional metabolic changes in the cerebellum and the frontal and temporal cortices were significantly correlated with D2 availability. Frontal and temporal metabolism were increased in subjects with high D2 receptors and decreased in subjects with low D2 receptors.

CONCLUSIONS

Methylphenidate induced variable changes in brain metabolism, but it consistently increased cerebellar metabolism. It also induced a significant reduction in relative metabolism in the basal ganglia. The significant association between metabolic changes in the frontal and temporal cortices and in the cerebellum and D2 receptors suggests that methylphenidate's metabolic effects in these brain regions are due in part to dopamine changes and that differences in D2 receptors may be one of the mechanisms accounting for the variability in response to methylphenidate.

Symmetrical cerebral metastasis presenting with bilateral upper extremity weakness

This report describes a man with known metastatic disease who presented with bilateral upper extremity weakness. The cause was discovered to be symmetrical cerebral metastases.

Relationship between psychostimulant-induced "high" and dopamine transporter occupancy

The ability of cocaine to inhibit the dopamine transporter (DAT) appears to be crucial for its reinforcing properties. The potential use of drugs that produce long-lasting inhibition of the DAT as a mean of preventing the "high" and reducing drug-seeking behavior has become a major strategy in medication development. However, neither the relation between the high and DAT inhibition nor the ability to block the high by prior DAT blockade have ever been demonstrated. To evaluate if DAT could prevent the high induced by methylphenidate (MP), a drug which like cocaine inhibits the DAT, we compared the responses in eight non-drug-abusing subjects between the first and the second of two MP doses (0.375 mg/kg, i.v.) given 60 min apart. At 60 min the high from MP has returned to baseline, but 75-80% of the drug remains in brain. Positron-emission tomography and [11C]d-threo-MP were used to estimate DAT occupancies at different times after MP. DAT inhibition by MP did not block or attenuate the high from a second dose of MP given 60 min later, despite a 80% residual transporter occupancy from the first dose. Furthermore some subjects did not perceive a high after single or repeated administration despite significant DAT blockade. These results indicate that DAT occupancy is not sufficient to account for the high, and that for DAT inhibitors to be therapeutically effective, occupancies > 80% may be required.

EBV-specific cytotoxic T lymphocytes protect against human EBV-associated lymphoma in scid mice

Scid mice develop human EBV-positive B cell tumors after injection with EBV-transformed human B cells or peripheral blood lymphocytes from EBV-seropositive donors. Injection of cytotoxic T cell (CTL) lines, selectively expanded in vitro to recognize autologous EBV-transformed B cells, protected mice against developing human lymphoproliferative disease. CTL protection required a single dose of polyethylene-glycol-conjugated IL2. Mice were not protected by CTL that did not specifically recognize EBV-transformed B cells or by mitogen-activated lymphocytes.

Three regions of HIV-1 gp160 contain clusters of immunodominant CTL epitopes

HIV-1 infection stimulates a strong CTL response that coincides with resolution of viremia in acute infection and declines with development of opportunistic infections. Recognition of HIV gp160 by PBMC-derived T cell lines from 20 HIV-infected subjects is dominated by the response to a small number of peptide epitopes. Overlapping CTL epitopes restricted by multiple MHC Class I elements were identified in 3 relatively conserved regions of gp160 (amino acids 49-68, 591-600 and 844-863). CTL from five of 20 subjects recognized three overlapping immunodominant epitopes in the 49-68 a.a. region restricted by A24, B38, and B55. CTL from four subjects recognized at least three distinct epitopes in a.a 591-600 in the context of A24, B8, B14, and B27. CTL from seven subjects recognized epitopes within a.a. 844-863 restricted by A30, B7, B8 and B35.

No evidence for association of dopamine D2 receptor variant (Ser311/Cys311) with major psychosis

We investigated a variant of the dopamine D2 receptor gene (Ser311/Cys311 substitution) in Caucasian patients with schizophrenia (n = 273), delusional disorder (n = 62), bipolar I affective disorder (n = 63), and controls (n = 255). No evidence for association between the receptor variant and any of the diseases was found, even when patients with younger age-of-onset (< 25 years) were compared with controls. Furthermore, in a subgroup of schizophrenia patients whom we assessed for negative symptoms, those with the Cys allele did not differ from the remainder of the group. Also, the bipolar affective disorder patients with psychotic features did not show evidence for association with the receptor variant. Thus, our results do not provide evidence for an association between this D2 receptor variant and schizophrenia, or delusional disorder, or bipolar affective disorder.

The Kaposi sarcoma-associated herpesvirus (KSHV) is present as an intact latent genome in KS tissue but replicates in the peripheral blood mononuclear cells of KS patients

Short DNA sequences have been identified, originally in association with Kaposi's sarcoma (KS) biopsies, that are highly homologous to oncogenic, lymphotropic herpesviruses. Recently a virus, Kaposi sarcoma associated herpesvirus (KSHV) or human herpesvirus-8 (HHV-8), bearing these sequences has been identified in a cell line derived from a body cavity-based lymphoma. In this report, we show that the same sequences are present in KS biopsies as DNA molecules of a form and size characteristic of latent herpesviruses-large, covalently closed, circular episomes. The genomes migrate with an apparent size larger than the herpesvirus Epstein-Barr virus (172 kb). This form of the viral genome was found in four of four biopsies and three of five peripheral blood samples from KS patients. Linear forms of the viral genome, characteristic of viral replication, were not detected in the biopsies, but were present in the peripheral blood of three out of five patients. The sequences for KSHV/HHV-8 were also detected in the blood of four of five allograft patients and three of five healthy donors without KS suggesting that the virus is widespread throughout the human population.

Successfully treated invasive pulmonary aspergillosis associated with smoking marijuana in a renal transplant recipient

Invasive pulmonary aspergillosis (IPA) is often a lethal entity in transplant recipients (up to 90%). We report the successful treatment of a case of IPA in a renal transplant recipient whose only risk for exposure was habitual marijuana smoking. Although marijuana smoking has been linked to the development of IPA in patients immunosuppressed for a variety of reasons, this case is the first report involving a solid organ transplant recipient. The patient's clinical course and treatment are described and the literature is reviewed with respect to environmental and patient risk factors. In this case, IPA was associated with the patient's heavy usage of marijuana during the immediate posttransplant period. Treatment was successful and included the experimental amphotericin product amphotericin B colloidal dispersion. Contemporaneous exposure to a large amount of inocula of Aspergillus within 30 days of receiving high doses of steroids appeared to be the most important factor that predisposed this patient to IPA. Transplant recipients should be specifically proscribed from marijuana use during periods of high steroid administration.

Serum enhances the ex vivo generation of HIV-specific cytotoxic T cells

The ex vivo expansion of antigen-specific cytotoxic T lymphocyte (CTL) lines is being developed for immunotherapy of viral infections and cancer and is critically dependent on the precise cell expansion and stimulation conditions. In this article, we investigate medium requirements for the development of HIV-specific CTL in cell lines generated from the peripheral blood of seven asymptomatic HIV-infected individuals. We find that HIV-specific CTL do not readily develop in the serum-free medium AIM V but do develop if the medium is supplemented with 1% plasma or serum. T cell lines with antigen-specific cytolytic activity express more cell-surface CD57 than do cell lines grown in the absence of serum or plasma. Three sources of serum (human autologous, human AB, or fetal calf) are comparable. Human plasma is somewhat less effective than serum from an identical source.

Effect of interleukin 12 on in vitro HIV type 1 replication depends on clinical stage

CD8-depleted PBMCs from 20 HIV-1-seropositive donors were incubated in the presence of no cytokines, rIL-2, rIL-12, or both. HIV-1 replication, measured by culture supernatant p24 Ag, was increased to a comparable extent by either rIL-2 or rIL-12 in five of seven asymptomatic subjects and was not induced by either cytokine in the remaining two asymptomatic subjects. Recombinant IL-2 induced increased p24 in cultures from 8 of 13 symptomatic subjects, but rIL-12 did only in cell lines from 5 symptomatic subjects and then only marginally. In IL-2 containing cultures from subjects with minor symptoms of HIV infection, the mean p24 Ag was 320 +/- 217 pg/ml versus 27 +/- 6 in IL-12-containing cultures (p = 0.03). When rIL-12 was added with rIL-2, p24 Ag levels were reduced fourfold compared to cultures from this group incubated with only rIL-2 (p = 0.03). Neither cytokine had much effect on viral replication in CD8-depleted PBMCs from subjects who had had a major AIDS infection, although the number of CD4 cells in four of six of those cultures was markedly reduced. IL-4, IFN-gamma, and IL-10 production induced by exposure to IL-2 and/or IL-12 were also measured. In CD8-depleted cultures from all infected asymptomatic donors and from some symptomatic donors, addition of rIL-12 to rIL-2 decreased IL-4 and increased both IFN-gamma and IL-10 production. Cytokine-induced production of IL-4, IFN-gamma, and IL-10 was greater in cultures from asymptomatic donors than in cultures from symptomatic subjects. Our results suggest that IL-12 immunotherapy may be complicated by enhancement of viral expression in asymptomatic individuals.

Deriving respiration from pulse wave: a new signal-processing technique

Investigations of autonomic nervous system activity using spectral analysis of heart rate (HR) and blood pressure (BP) variability is very popular in many scientific disciplines, and yet only half of all studies involving spectral analysis control for respiration. Because respiration modulates HR and BP variability, knowledge of the respiratory rate is necessary for the proper interpretation of HR and BP power spectra. We devised and validated a new signal-processing technique to derive respiration from the blood pressure wave. This technique is based on the relationship between oscillations in the area under the dicrotic notch of the pulse wave and respiration. The results of our view signal-processing technique yielded significant correlations between protocols of the actual number of respiratory cycles and our blood pressure-derived respiratory cycles and their respective spectra for a number of standard autonomic tests (P < 0.05). Our method will allow retrospective extraction of the respiratory wave and as such afford a more precise interpretation of HR and BP spectra.

Prediction of HIV peptide epitopes by a novel algorithm

Identification of promiscuous or multideterminant T cell epitopes is essential for HIV vaccine development, however, current methods for T cell epitope identification are both cost intensive and labor intensive. We have developed a computer-driven algorithm, named EpiMer, which searches protein amino acid sequences for putative MHC class I- and/or class II-restricted T cell epitopes. This algorithm identifies peptides that contain multiple MHC-binding motifs from protein sequences. To evaluate the predictive power of EpiMer, the amino acid sequences of the HIV-1 proteins nef, gp160, gag p55, and tat were searched for regions of MHC-binding motif clustering. We assessed the algorithm's predictive power by comparing the EpiMer-predicted peptide epitopes to T cell epitopes that have been published in the literature. The EpiMer method of T cell epitope identification was compared to the standard method of synthesizing short, overlapping peptides and testing them for immunogenicity (overlapping peptide method), and to an alternate algorithm that has been used to identify putative T cell epitopes from primary structure (AMPHI). For the four HIV-1 proteins analyzed, the in vitro testing of EpiMer peptides for immunogenicity would have required the synthesis of fewer total peptides than either AMPHI or the overlapping peptide method. The EpiMer algorithm proved to be more efficient and more sensitive per amino acid than both the overlapping peptide method and AMPHI. The EpiMer predictions for these four HIV proteins are described. Since EpiMer-predicted peptides have the potential to bind to multiple MHC alleles, they are strong candidates for inclusion in a synthetic HIV vaccine.

Gender differences in neuroleptic nonresponsive clozapine-treated schizophrenics

Gender differences in neuroleptic-refractory chronic schizophrenic disorder patients were examined to determine whether a superior or equivalent antipsychotic response in women vs. men existed similar to that of the general schizophrenic population. Sixty-nine DSM-III schizophrenic patients (47 males and 22 females) were treated with clozapine using a standardized medication regime. The gender differences in these neuroleptic-nonresponsive chronic schizophrenic disorder patients differed from those previously observed in the general schizophrenic population in that an equivalent antipsychotic treatment response in females versus males was not found. These treatment-refractory women appear to be a severely ill subgroup of female schizophrenics with distinct onset of illness, course and treatment response characteristics.

Psychosis and genes with trinucleotide repeat polymorphism

Abnormal expansion of genes with trinucleotide repeat (TNR) polymorphism has been found in a number of neuropsychiatric disorders. These disorders and the major psychoses, schizophrenia and bipolar affective disorder, appear to share an interesting phenomenon: genetic anticipation. Because TNR expansion correlates with anticipation, these unstable DNA sites are considered important candidate loci for the major psychoses. We investigated genes with TNR polymorphisms, including B1, B33, B37, and the N-cadherin gene, in unrelated Caucasian North American and Italian schizophrenics (n = 53 to 74), and matched controls. Also, unrelated Caucasian North American patients with bipolar I affective disorder were screened for the B33 and N-cadherin genes (n = 49 and 63, respectively). No unusually long alleles that would suggest abnormal expansion of the TNR were observed for any of these genes. Also, no statistically significant results were found in tests for genetic association between any of these genes and schizophrenia. For B37, a trend toward a difference in allele counts between schizophrenics and controls was observed. However, no clear evidence for a role of these TNR-containing genes in schizophrenia or bipolar affective disorders was found.

Temporal relationships between the pharmacokinetics of methylphenidate in the human brain and its behavioral and cardiovascular effects

Positron emission tomography was used to compare the pharmacokinetics of [11C]methylphenidate in the human brain with the temporal course of the subjective and cardiovascular effects observed after intravenous methylphenidate (0.5 mg/kg). Four subjects were tested twice with [11C]methylphenidate, at baseline and after methylphenidate. All subjects showed almost identical uptake of 11C labeled drug in brain, as well as a very similar decrease in binding of [11C]methylphenidate in basal ganglia, after pretreatment with methylphenidate. In contrast, the magnitude of the behavioral and cardiovascular changes induced by methylphenidate varied among the subjects. The temporal course for methylphenidate effects paralleled closely the pharmacokinetics of [11C]methylphenidate in brain for the perception of "restlessness" and for changes in systolic blood pressure and heart rate. In contrast, methylphenidate induced "high", "anxiety" and changes in diastolic blood pressure decreased rapidly despite long lasting binding of the drug in brain. These results indicate that binding of methylphenidate in brain does not appear to predict individual responses to the drug and that more than one neurotransmitter and/or adaptation process are likely to be involved in the behavioral and cardiovascular effects of methylphenidate.

Association study of dopamine D3 receptor gene and schizophrenia

Several groups have reported an association between schizophrenia and the MscI polymorphism in the first exon of the dopamine D3 receptor gene (DRD3). We studied this polymorphism using a North American sample (117 patients plus 188 controls) and an Italian sample (97 patients plus 64 controls). In the first part of the study, we compared allele frequencies of schizophrenia patients and unmatched controls and observed a significant difference in the total sample (P = 0.01). The second part of the study involved a case control approach in which each schizophrenia patient was matched to a control of the same sex, and of similar age and ethnic background. The DRD3 allele frequencies of patients and controls revealed no significant difference between the two groups in the Italian (N = 53) or the North American (N = 54) matched populations; however, when these two matched samples were combined, a significant difference was observed (P = 0.026). Our results suggest that the MscI polymorphism may be associated with schizophrenia in the populations studied.

Induction of cell-mediated immune responses to human immunodeficiency virus type 1 Gag protein by using Listeria monocytogenes as a live vaccine vector

Cytolytic T cells, acting through cytokines or by direct lysis of infected target cells, have been shown to play a significant role in the control of viral infections and may be responsible for the prolonged asymptomatic phase following infection by HIV. Accordingly, methods that can generate strong cell-mediated immune responses may be useful in the development of prophylactic and therapeutic vaccines against HIV. Listeria monocytogenes is a Gram-positive intracellular microorganism that elicits strong cell-mediated immune responses against its own secreted proteins following infection. In this study we have modified the chromosome of L. monocytogenes so that it stably expresses and secretes the p55 HIV gag gene product and examined the cell-mediated immune response of BALB/c mice to infection with this recombinant organism. Infected animals were found to mount a specific, strong, long-lasting CD8+ cytolytic T cell response against a predominant epitope contained within the p24 fragment of the HIV Gag protein. This epitope previously has been shown to be recognized by CTLs obtained from some HIV-infected humans. Our results suggest that chromosomally modified strains of L. monocytogenes may provide valuable vaccine vectors for use against HIV.

Induction of cell-mediated immune responses to human immunodeficiency virus type 1 Gag protein by using Listeria monocytogenes as a live vaccine vector

Cytolytic T cells, acting through cytokines or by direct lysis of infected target cells, have been shown to play a significant role in the control of viral infections and may be responsible for the prolonged asymptomatic phase following infection by HIV. Accordingly, methods that can generate strong cell-mediated immune responses may be useful in the development of prophylactic and therapeutic vaccines against HIV. Listeria monocytogenes is a Gram-positive intracellular microorganism that elicits strong cell-mediated immune responses against its own secreted proteins following infection. In this study we have modified the chromosome of L. monocytogenes so that it stably expresses and secretes the p55 HIV gag gene product and examined the cell-mediated immune response of BALB/c mice to infection with this recombinant organism. Infected animals were found to mount a specific, strong, long-lasting CD8+ cytolytic T cell response against a predominant epitope contained within the p24 fragment of the HIV Gag protein. This epitope previously has been shown to be recognized by CTLs obtained from some HIV-infected humans. Our results suggest that chromosomally modified strains of L. monocytogenes may provide valuable vaccine vectors for use against HIV.