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Biomedical subjects

J Lieberman

Publications and source records attributed to J Lieberman.

At least 19 recordsLinked to original sources
PubMed1995

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.

AIDS Vaccines↗
PubMed1995

A vaccinia-gp160-based vaccine but not a gp160 protein vaccine elicits anti-gp160 cytotoxic T lymphocytes in some HIV-1 seronegative vaccinees.

Cytotoxic T lymphocytes (CTL) play an important role in the immune response to viral infection by recognizing and destroying infected cells. HIV-1 elicits an unusually strong CTL response in infected individuals and clearance of the viremia of acute infection coincides with the development of HIV-specific CTL. Because HIV-specific CTL may provide protection against de novo viral infection, we compared the CTL response in seronegative volunteers treated with two vaccination approaches. Seven volunteers were immunized with a live recombinant vaccinia virus expressing the HIV envelope protein gp160LAI (HIVAC-1e) and boosted with 640 micrograms recombinant baculovirus-expressed gp160LAI in alum 1-13 months later. In a second study, three volunteers underwent four successive immunizations with 640 micrograms subunit gp160LAI in alum at 0, 1, 6, and 12 months. The first vaccination strategy using a liver vector would be expected to generate gp160-specific CTL, while for the second, using only whole-protein subunit, the generation of specific CTL would be unlikely. Predominantly CD8+ T-cell lines generated from PBMC by nonspecific stimulation with PHA and IL-2 were screened after three to four weeks of culture for cytolytic activity against autologous targets infected with vaccinia vectors encoding envLAI, RT, gag, and lacZ control. A strong gp 160-specific CTL response was detected in two vaccines in the recombinant vaccinia plus subunit boost study. Modest responses were seen in four of the other five live vector-primed vaccinees. No significant gp160-specific CTL were observed in three volunteers given only subunit rgp160 or in five control subjects.

AIDS Vaccines↗
PubMed1995

CD43 diminishes susceptibility to T lymphocyte-mediated cytolysis.

CD43 is a major membrane sialoglycoprotein expressed by cells of hematopoietic origin. One property of CD43 is its ability to interfere with heterotypic and homotypic cellular adhesion. To determine whether CD43 expression can affect cell functions requiring intercellular adhesion, we compared a CD43-positive human T cell line (CEM) and its CD43-negative counterpart derived by gene targeting for susceptibility to cell-mediated lysis. CD43-negative CEM cells were more susceptible than CD43-positive cells to lysis by allospecific T cell lines derived from several donors. Induction of CD43 expression on transfected HeLa cells also imparted resistance to lectin-mediated lysis by a CD8+ T cell clone. The effect of CD43 expression on reducing susceptibility to lysis was more pronounced in short-term cytotoxicity assays and tended to disappear as the time of contact between the effector cell and its target increased. The enhanced susceptibility of CD43-negative cells to lysis was not associated with increased expression of adhesion molecules known to mediate antigen-independent cellular adhesion. Sialic acid residues on CD43 contributed to the CD43 protective effect. These results suggest that either diminished CD43 expression or incomplete sialylation may render hematopoietic cells more susceptible to T lymphocyte-mediated cytolysis.

Antigens, CD↗
PubMed1995

Ex vivo expansion of HIV type 1-specific cytolytic T cells from HIV type 1-seropositive subjects.

Cytotoxic T lymphocytes that specifically lyse HIV-1-infected cells occur at uncommonly high frequency in the blood of infected individuals. The CTL response is dominated by the recognition of a small number of peptides encoded by HIV-1 structural and regulatory genes. These two facts have enabled us to develop potent HIV-specific CTL lines from the blood of infected patients without AIDS opportunistic infections by ex vivo culture of nonspecifically stimulated T cell lines with autologous antigen-presenting cells (APCs) preincubated with immunodominant HIV-1 peptides. After one selection, HIV-specific cytotoxicity is enhanced 1.4- to sixfold. Frequency analysis of the T cell line from 1 patient revealed that after exposure to peptide-incubated autologous B-LCLs, the frequency of CTLs specific for the gp160-expressing APCs was enhanced 6-fold and, after a second exposure, 11-fold compared to the nonselected T cell line. Because the APCs used for the frequency analysis were EBV-transformed B-LCLs, some of the specific CTLs in the culture recognized the EBV-expressing APCs. HIV-specific cytotoxicity is enhanced without augmentation of EBV-specific cytotoxicity when PBMCs are used as APCs. Because T cell lines enhanced for HIV-1 specificity are highly cytotoxic and can be expanded to approximately 10(9)-10(10) cells/ml of blood, they may be useful for laboratory research or for immunotherapy.

Amino Acid Sequence↗
PubMed1995

A simple method to selectively expand HIV-1 specific cytotoxic T lymphocytes in vitro.

Cytotoxic T lymphocytes (CTL) may play a critical role in controlling the progression of HIV-1 disease. Conventional assays for demonstration of CTL against HIV-1 have used either fresh PBMC or T cell lines and clones generated by non-specific stimulation. These methods are limited in their sensitivity since without specific secondary stimulation in vitro, epitopes recognized at low frequency may not be detected. Moreover, derivation of CTL clones is labor intensive and not practical for studying a large number of patients. We have developed a simple method to enrich HIV-1 specific CTL in vitro. Autologous antigen presenting cells (APC), either adherent macrophages or EBV transformed B-lymphoblastoid cells, are infected with recombinant vaccinia virus encoding individual HIV-1 proteins and after overnight culture the vaccinia virus is inactivated by uv irradiation in the presence of psoralin. The infected APC are then cultured with patient's T cells and CTL activity determined 10-14 days later. We have used this method to stimulate patients' T cells obtained directly from PBMC and also after mitogenic stimulation. In both systems, the HIV-1 specific response could be enhanced up to five to ten fold. This enhancement is comparable to CTL selection by exposure to HIV-1 immunodominant peptide incubated APC. In some patients, viral-specific CTL could be detected after HIV-vaccinia selection even though the mitogen stimulated cultures had no demonstrable antiviral CTL activity. Selective expansion of CTL directed against multiple HIV-1 proteins (env, gag and RT) could be obtained from PBMC as well as from mitogen-stimulated lines from individual patients. As these lines are predominantly CD8+ T cells by flow cytometric analysis and are free of vaccinia virus as ascertained by the lack of cytopathic effect in culture, in vitro vaccinia selection might also be useful to generate CTL lines for adoptive immunotherapy.

Antigen-Presenting Cells↗
PubMed1994

Plasma homovanillic acid levels in first-episode schizophrenia. Psychopathology and treatment response.

OBJECTIVES: To examine plasma homovanillic acid (pHVA) levels in first-episode schizophrenia, to compare pHVA levels in patients and controls, and to assess the association of pHVA levels with psychopathology and treatment response. METHODS: Forty-one patients entered the study, and pHVA levels were measured at baseline and on a weekly basis for up to 6 weeks of open standardized neuroleptic treatment. Psychopathology was evaluated with the Schedule for Affective Disorders and Schizophrenia, the Scale for Assessment of Negative Symptoms, and the Clinical Global Impressions scale. Ten healthy controls were used for comparison of baseline pHVA levels. RESULTS: No differences were observed between patients and controls. Baseline pHVA level was not associated with psychopathology but was associated with time to reach remission. Baseline pHVA levels and week-1 pHVA levels were higher in responders than nonresponders. Regardless of responsiveness, female participants had higher pHVA levels than male participants throughout the study. The pattern of pHVA levels with treatment was similar in all patients with a short-term rise initially and then a decrease toward baseline values. CONCLUSIONS: These findings suggest that pHVA levels have prognostic significance for response and time to reach remission. Qualitative and quantitative differences between first-episode patients' pHVA levels and studies using a long-term, neuroleptic-exposed population suggest that changes occur with neuroleptic treatment or the progression of the illness.

Adult↗
PubMed1994

Absence of recoverable infectious virus and unique immune responses in an asymptomatic HIV+ long-term survivor.

We have studied a woman with transfusion-acquired HIV who appears to have contained infectious virus to consistently undetectable levels over a 13-year period without antiviral treatment. She received the infected transfusion for intra- and postpartum blood loss immediately after delivery of her second child in 1981. She had no acute febrile syndrome and has never had HIV-associated clinical signs or symptoms in the 13 years since infection. She was first tested and found positive for HIV antibodies in 1985, and the infected blood donor was diagnosed with AIDS in 1986 and died of AIDS-related complications in 1989. Two other recipients of packed erythrocytes from this donor (in 1980 and 1982) also became infected and were subsequently diagnosed with AIDS. Between January 1986 and April 1994, in the setting of continuous and unambiguous Western blot HIV-specific antibodies and intermittently positive low-level HIV DNA signal after polymerase chain reaction (PCR) amplification, more than 30 separate cell cocultures performed in several independent laboratories failed to yield evidence of infectious virus, despite special efforts to induce and detect HIV replication. Immunologically, a strong in vitro proliferative response to HIV envelope proteins also distinguished this subject from other asymptomatic HIV+ individuals.

Adult↗
PubMed1994

The resampling method of statistical analysis.

Some non-statisticians occasionally use improper statistical methodology due to a lack of appreciation for the model assumptions that underlie a particular technique. The resampling method is a recent attempt to solve statistical problems with a minimum of assumptions. In essence, resampling involves an intuitive approach to inferential statistics that obviates the need for the mathematically derived sampling distribution. The resampling approach takes advantage of readily accessible high-speed computers to do a computationally intensive Monte Carlo experiment on the available data. The resampling approach liberates the user from imposing assumptions that are sometimes dubious. It also directs one away from a black-box attitude toward statistical analysis and instead forces the user to consider the purpose of the inferential process. A particularly user-friendly implementation of resampling methods that addresses some of the problems faced by non-statisticians is found in a simple, yet powerful, computer program called "Resampling Stats," version 3.13.

Adult↗
PubMed1993

The dopamine-serotonin relationship in clozapine response.

The effects of clozapine on the dopamine and serotonin systems may underlie its atypical pharmacologic and clinical profile. To examine this hypothesis, we measured dopamine and serotonin plasma and cerebrospinal (CSF) metabolites and the relationship of these values to treatment response in 19 neuroleptic refractory and intolerant schizophrenic patients. Only a small change in the CSF and plasma homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5HIAA) levels was found. However, the pretreatment CSF HVA/5HIAA ratio and, to a lesser extent, the CSF HVA level predicted treatment response. These results suggest that the modest relationship between HVA and 5-HIAA and treatment response supports the involvement of both neurotransmitters in the pathophysiology of schizophrenia.

Adolescent↗
PubMed1992

Cytotoxic T lymphocytes from HIV-1 seropositive individuals recognize immunodominant epitopes in Gp160 and reverse transcriptase.

The CTL response to HIV-1 is more vigorous than for any known human pathogen and may be a significant factor in preventing the progression to symptomatic disease. T cell lines, generated by non-specific stimulation with PHA and IL-2, may be reproducibly used to identify HIV-1 isolate-invariant epitopes recognized by the CTL of infected individuals. The CTL response in each of 12 infected individuals to envelope and reverse transcriptase (RT) is dominated by the recognition of one or two viral isolate-invariant epitopes. Seven subjects respond to a single gp160 epitope; three subjects recognize 2 gp160 epitopes. There is a significant increase in recognition of epitopes in the C terminal 104 amino acids of gp41 (p less than 0.002); in fact 40% of the subjects that respond to gp160 recognize the C terminal 20-mer. The CTL-mediated lysis of gp160-expressing targets is MHC restricted, but not all individuals that share the same serologically defined class I-restricting element respond to the same epitope. Recognition of the terminal 20mer is restricted by both A30 and B8. The response to RT in six subjects is distributed over the RT protein. The six subjects recognize four separate regions defined by truncated RT-vaccinia recombinants, but none of the subjects' CTL demonstrate significant recognition of the RT epitope identified in H-2k mice and some humans.

Amino Acid Sequence↗
PubMed1992

A comparison of clinical examination, history, and magnetic resonance imaging for identifying orthodontic patients with temporomandibular joint disorders.

The temporomandibular joint (TMJ) status of 51 juvenile orthodontic patients was assessed with magnetic resonance imaging (MRI), clinical examination, and questionnaire data. The results of this study demonstrated that the prevalence of anterior displacement of the meniscus was 11.8% (6 of 51) as assessed by MRI. Clicking or pain in the TMJ area was found in 9.8% (5 of 51) of the subjects by clinical exam, and 19.8% (10 of 51) of the subjects had a history of pain or clicking of the TMJ. Three subjects had a positive MRI and a negative history and clinical examination. However, all subjects with positive MRI findings had a history of other risk factors known to be associated with TMJ internal derangement (TMJ-ID). Therefore practitioners should use a history form and a clinical examination technique that includes a broad range of signs and symptoms of temporomandibular disorders (TMD) to identify patients who may have abnormal condyle disk relationships and be at risk for TMD. Clicking and pain in the TMJ helped identify only one half of the patients with abnormal condyle-disk relationships in this study population. Future cephalometric studies will monitor the effects of abnormal condyle disk relationships on facial growth during orthodontic treatment.

Adolescent↗
PubMed1992

Increased prevalence of the cavum septum pellucidum in magnetic resonance scans and post-mortem brains of schizophrenic patients.

A cavum septum pellucidum (CSP) has been regarded as an incidental finding of little clinical importance. However, an association between this developmental anomaly and a diagnosis of psychosis has previously been reported. We determined the prevalence of the CSP in parallel studies of brain scans obtained with magnetic resonance (MR) imaging and in the post-mortem brains of schizophrenic patients compared with normal controls. We found a significantly increased prevalence of the CSP in both the MR scans and post-mortem brains of schizophrenic patients compared with controls. In the MR study, 17 of 81 (21%) schizophrenic patients but only 1 of 46 (2%) control subjects had a CSP. In the post-mortem study, 17 of 28 (61%) schizophrenic patients and 12 of 39 (31%) normal controls had a CSP. The increased prevalence of a CSP in schizophrenic patients further indicates that anomalous development of the limbic system is an important aspect of this disorder.

Adult↗
PubMed1992

Inflammatory abdominal aortic aneurysm and the associated T-cell reaction: a case study.

The immune response associated with an inflammatory abdominal aortic aneurysm was studied by determining the phenotypes of lymphocytes in the peripheral blood, the aortic aneurysm wall, and the perianeurysmal tissue. Increased numbers of activated T cells were found in all three areas. After aneurysm repair, peripheral blood analysis demonstrated normalization of the T-cell subsets. These data suggest that inflammatory abdominal aortic aneurysm is associated with a measurable immune response in peripheral blood with elevation of the same subset of inflammatory cells (CD4) as detected in abdominal aortic aneurysm tissue, and the immune response regresses after aneurysm repair.

Aged↗
PubMed1992

Emergency thoracotomy: survival correlates with physiologic status.

Emergency thoracotomy is a standard procedure in the management of cardiac arrest in patients sustaining severe trauma. We examined the records of 463 moribund trauma patients treated at our institution from 1980 to 1990 to refine indications for emergency thoracotomy. Patients underwent thoracotomy either in the emergency department (ED) (n = 424) or in the operating room (OR) (n = 39) as a component of continuing resuscitation after hospital arrival. The survival rate was 13% (61 of 463) overall, 2% (3 of 193) for blunt, 22% (58 of 269) for all penetrating, 8% (10 of 131) for gunshot, 34% (48 of 141) for stab-wound patients, and 54% (21 of 39) for patients who underwent emergency thoracotomy in the OR. Survival correlated with the physiologic status of patients both on initial evaluation in the field by paramedics and on arrival at the ED. Patients with penetrating trauma and in profound shock (BP less than 60 mm Hg) or mild shock (BP 60-90 mm Hg) with subsequent cardiac arrest had survival rates of 64% (27 of 42) and 56% (30 of 54), respectively. None of the patients with absent signs of life, defined as full cardiopulmonary arrest with absent reflexes (n = 215), on initial assessment by paramedics in the field, survived. We conclude that (1) no emergency thoracotomy should be performed if no signs of life are present on the initial prehospital field assessment; (2) emergency thoracotomy is an indicated procedure in most patients sustaining penetrating trauma; (3) blunt traumatic cardiac arrest is a relative contraindication to emergency thoracotomy.

Adult↗