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Biomedical subjects

J Lieberman

Publications and source records attributed to J Lieberman.

At least 109 records · Page 6Linked to original sources
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

Zalcitabine compared with zidovudine in patients with advanced HIV-1 infection who received previous zidovudine therapy.

OBJECTIVE: To evaluate the safety and efficacy of zalcitabine (also known as dideoxycytidine [ddC]) in patients with advanced human immunodeficiency virus (HIV) infection. DESIGN: Open-label, randomized study. SETTING: AIDS Clinical Trials Units, university-affiliated medical centers, and private practice groups. PATIENTS: Patients with the acquired immunodeficiency syndrome (AIDS) or advanced AIDS-related complex who had tolerated zidovudine for 48 weeks or more. INTERVENTION: Fifty-nine patients received zidovudine (500 to 1200 mg/d) and 52 patients received zalcitabine (2.25 mg/d). MEASUREMENTS: The primary end points were survival and time to an AIDS-defining event or death. RESULTS: Because significantly more patients withdrew from zidovudine therapy, the median duration of treatment was greater in the zalcitabine group than in the zidovudine group (279.0 days compared with 174.5 days; P = 0.001). The estimated 12-month, event-free probabilities were 53% for the zalcitabine group and 57% for the zidovudine group (relative risk, 1.02; 95% CI, 0.5 to 2.2). The estimated 12-month survival rates were 81% for the zalcitabine group and 75% for the zidovudine group (relative risk, 1.39; CI, 0.5 to 3.8). The rate of decline in CD4 lymphocyte counts was significantly slower in the zalcitabine group than in the zidovudine group (-0.08 cells/day compared with -0.17 cells/day). Patients in the zalcitabine group had gained an average of 0.5 kg at week 20 and 0.4 kg at week 24, whereas patients in the zidovudine group had lost an average of 1.8 kg at week 20 and 2.4 kg at week 24 (P = 0.04 and P = 0.05, respectively). Moderate to severe peripheral neuropathy and ulcerative stomatitis occurred in 10 and 9 patients, respectively, in the zalcitabine group. CONCLUSIONS: The sample size for this study was smaller than planned, and no differences in survival and clinical end points were found. Slower rates of decline in CD4 lymphocyte counts and weight, however, were noted for the zalcitabine group.

Adult↗
PubMed1993

Time course and biologic correlates of treatment response in first-episode schizophrenia.

OBJECTIVE: To examine the course and potential predictors of treatment response in the early phase of schizophrenia. DESIGN: Prospective study of an inception cohort. SETTING: Psychiatric division of an academic medical center with a suburban metropolitan catchment area. PATIENTS AND INTERVENTION: Seventy first-episode patients who had undergone four biologic assessment procedures (brain magnetic resonance imaging, behavioral response to methylphenidate hydrochloride, growth hormone levels, eye tracking) were treated with a standardized antipsychotic drug protocol until recovery. Response was measured in terms of psychopathology and degree of remission. RESULTS: Using survival analysis, the proportion of patients remitting by 1 year was estimated at 83%. Mean and median times to remission were 35.7 weeks and 11 weeks, respectively. No baseline demographic or psychopathologic measure significantly predicted time to or level of remission. However, males tended to be nonresponders to treatment and have diagnoses of schizophrenia rather than schizoaffective disorder. Brain pathomorphology and abnormal basal growth hormone significantly predicted time to remission. CONCLUSIONS: These results indicate that the antipsychotic treatment response of first-episode schizophrenics is better than chronic multiepisode patients and suggest that specific pathobiologic markers reflect pathophysiologic processes that mediate antipsychotic treatment response.

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↗
PubMed1993

Serum angiotensin-converting enzyme as a marker for the chronic fatigue-immune dysfunction syndrome: a comparison to serum angiotensin-converting enzyme in sarcoidosis.

PURPOSE: To study the reliability of a serum angiotensin-converting enzyme (ACE) assay as a marker for the chronic fatigue-immune dysfunction syndrome (CFIDS), and to compare some enzyme characteristics of ACE in CFIDS with that in sarcoidosis. PATIENTS AND METHODS: Forty-nine patients with CFIDS and 56 endemic control subjects from Lyndonville, New York, and Charlotte, North Carolina; plus 23 untreated patients with active sarcoidosis, 24 with sarcoidosis receiving corticosteroid therapy, and 32 patient controls without sarcoidosis from California. Serum ACE levels were determined with a spectrophotometric method. The effect of freezing and thawing and the effect of storage at 4 degrees C were compared between CFIDS and sarcoidosis samples. RESULTS: Serum ACE levels were elevated in 80% of patients with CFIDS and 30% of endemic control subjects as compared with 9.4% of nonendemic California control subjects. The ACE activity in CFIDS differed from that in sarcoidosis because of its lability with storage at 4 degrees C in CFIDS and its partial activation with freezing and thawing. Thus, ACE activity was elevated in the majority of CFIDS patients either upon initial assay or upon a subsequent assay after refreezing. ACE activity was elevated in 87% of patients with active sarcoidosis and was not affected by storage or freezing and thawing. CONCLUSIONS: Serum ACE elevations may be a useful marker for CFIDS, especially if a method can be developed to distinguish ACE in CFIDS from that in sarcoidosis. The sensitivity for CFIDS was 80%, with 68% specificity in an endemic area. The increased prevalence of serum ACE elevations in endemic controls as compared with nonendemic controls suggests that an ACE increase may be an early manifestation of CFIDS and supports the concept that CFIDS is a definite disease state.

Adult↗
PubMed1993

Depression in first-episode schizophrenia.

OBJECTIVE: Because findings regarding the prognostic significance of depressive symptoms in schizophrenia and their effect on the course and treatment of schizophrenia have been limited by the effects of previous treatment, retrospective evaluations, and differing definitions and criteria, the authors sought to determine the prevalence and prognostic significance of depressive symptoms in first-episode schizophrenia. METHOD: Thirty-nine men and 31 women experiencing their first episode of schizophrenia were evaluated with behavioral and extra-pyramidal symptom scales before treatment (baseline), biweekly during acute treatment, and then monthly. Extracted scores on the Hamilton Rating Scale for Depression and a "syndromal" definition of depression based on Research Diagnostic Criteria were obtained. Patients were followed prospectively for up to 5 years and received open standardized treatment. RESULTS: The prevalence of depressive symptoms at baseline ranged from 75% (patients who met extracted Hamilton and/or syndromal criteria) to 22% (patients who met both criteria). Of 808 psychotic ratings given to the 70 patients over a 5-year follow-up period, 210 (26%) were concurrently rated as depressed; of the 1,754 nonpsychotic ratings, only 70 (4%) were concurrently rated as depressed. Of the 210 depressive symptoms that occurred concurrently with psychosis, 206 (98%) resolved as the psychosis remitted. Depressive symptoms were prodromal to a psychotic relapse in only two (7%) of 27 patients who relapsed. Depressive symptoms correlated more with positive and negative symptoms than with extrapyramidal symptoms. CONCLUSIONS: These findings suggest that depressive symptoms in patients experiencing their first episode of schizophrenia may represent a core part of the acute illness or may occur as a subjective reaction to the experience of psychotic decompensation. Since most of the depressive symptoms resolved as the psychosis remitted, antidepressant therapy should be limited to patients in whom the depression persists.

Acute Disease↗
PubMed1993

Variants of alpha 1-antitrypsin in Puerto Rican children with asthma.

A survey of 393 Puerto Rican and 354 non-Hispanic pediatric patients at Beth Israel Hospital, New York, revealed a significantly larger percentage of asthmatic subjects among Puerto Ricans, confirming findings of a study of Puerto Rican adults in New York. Assays of alpha 1-antitrypsin (AAT) concentration and phenotypes in 61 Puerto Rican asthmatic children revealed a significantly larger number with an S or Z variant in AAT phenotype. The AAT concentration was not a significant variable in this relationship, since four of five subjects with intermediate deficient AAT concentrations and a PiM phenotype were among control nonasthmatic Puerto Rican subjects. A family history of asthma was more common among asthmatic than control subjects and was most common for variant AAT phenotypes in either asthmatic or control subjects. We speculate that the S or Z variant of AAT affects the inflammatory response in such a way as to predispose to asthma.

Adolescent↗
PubMed1993

High plasma clozapine levels in tardive dyskinesia.

Studies in the literature that attempt to relate neuroleptic plasma levels to the development of tardive dyskinesia (TD) report inconsistent findings. As part of an open, long-term study, 60 schizophrenic and schizoaffective patients were started gradually on a b.i.d. schedule of the atypical antipsychotic drug clozapine. Blood samples were drawn weekly for 6 weeks and analyzed for a variety of constituents including clozapine plasma levels. Patients with higher levels of TD were found to have significantly higher levels of plasma clozapine and a higher ratio of plasma/dose than those with lower levels of TD. Our data suggests that schizophrenics with TD may have different pharmacokinetics, drug metabolism, and elimination processes than those without TD. Higher typical plasma neuroleptic levels may increase susceptibility to TD development. A second hypothesis implies that it is not the higher mean plasma level of a neuroleptic that is associated with TD but the greater fluctuations of plasma levels over time (i.e., a higher variance). This hypothesis is discussed in the context of our data.

Adult↗
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↗
PubMed1992

Qualitative assessment of brain morphology in acute and chronic schizophrenia.

OBJECTIVE: Neuroimaging studies of brain morphology in schizophrenia have used predominantly morphometric techniques to assess brain scans. However, as currently implemented, such methods are not particularly helpful in the routine assessment of individual patients. The purpose of this study was to evaluate brain morphology seen with magnetic resonance imaging (MRI) by qualitative assessment, the most frequently used method in clinical practice for evaluating brain scans. METHOD: First-episode (N = 62) and chronic, multi-episode (N = 24) schizophrenic patients and healthy comparison subjects (N = 42) underwent MRI of the whole head in a sequence that provided 63 contiguous brain slice images. Each subject received a rating of normal, questionably abnormal, or definitely abnormal for four brain regions (lateral ventricles, third ventricle, medial temporal lobe structures, and frontal/parietal cortex) and a global rating. RESULTS: The schizophrenic patients had significantly higher global rates of abnormal morphology (first-episode group, 31%; chronic group, 42%) than the normal subjects (5%). The highest regional rates of abnormalities were seen in the lateral ventricles and the lowest in the frontal/parietal cortex. Although the chronic patients had generally higher abnormal rates than the first-episode patients, these differences were not statistically significant. The qualitative ratings of brain morphology were significantly correlated with quantitative assessments performed in separate studies. CONCLUSIONS: Despite its limits in sensitivity (and until quantitative morphometric techniques are made practical and more widely available), qualitative evaluation of MRI scans can be a useful technique in research and clinical evaluation of patients with schizophrenia.

Adolescent↗
PubMed1992

Major histocompatibility complex associations with clozapine-induced agranulocytosis. The USA experience.

In order to determine associations between the major histocompatibility complex (MHC) and the development of clozapine-induced agranulocytosis, HLA typing was performed in a group of 42 clozapine-treated patients, of whom 11 had developed this adverse reaction. Among the patients with agranulocytosis, 7 (63%) were of Ashkenazi Jewish background and 4 (37%) were non-Jewish. An association between the HLA-B38, -DR4, -DQw3 haplotype and clozapine-induced agranulocytosis was found in all Jewish cases (7/7; 100%); in contrast only 4 of 21 (19%) Jewish control (nonagranulocytic) patients carried this haplotype. Among non-Jewish patients the HLA-DR2, -DQw1 haplotype was present in 4 of 4 (100%) patients with clozapine-induced agranulocytosis and in only 3 of 10 (30%) ethnically matched control patients. Our results indicate that gene products within the MHC could be involved in clozapine-mediated haematological toxicity.

Agranulocytosis↗
PubMed1991

Mood responses of remitted schizophrenics to methylphenidate infusion.

To investigate the mood response of schizophrenic subjects to psychostimulant challenge, 29 neuroleptic-treated subjects (22 with schizophrenia and 7 with schizoaffective disorder) in clinical remission received two infusions, one with methylphenidate 0.5 mg/kg and the other with normal saline, under double-blind conditions. Twenty-five of these subjects were withdrawn from neuroleptics and given a second set of double-blind infusions. Infusion mood responses were classified as euphoric, neutral, mixed or dysphoric. Subjects were also rated as either psychotic symptom activators to the infusion or no change in psychotic symptoms. Overall response by mood category was as follows: 35.2% euphoric, 50% neutral, 5.6% mixed and 9.3% dysphoric. Mood responses were not correlated with sex, methylphenidate plasma levels or diagnostic distinctions between schizophrenia and schizoaffective disorder. Although they occurred infrequently, dysphoric and mixed mood responses were associated with high rates of psychotic activation. Comparing subjects on and off neuroleptics, subjects on neuroleptics had more euphoric responses than the same subjects off neuroleptics. This increased number of euphoric responses in subjects taking neuroleptics compared to off neuroleptics suggests that neuroleptic treatment status may be an important factor in assessing psychostimulant use in schizophrenia patients.

Adolescent↗
PubMed1991

Measurement standards for the prevertebral region in the lateral soft-tissue radiograph of the neck.

One hundred thirty-one lateral soft-tissue radiographs of the neck, taken over a 6-month period, were reviewed. Eighty-six radiographs were normal. The mean prevertebral soft-tissue thickness in the posterior-anterior dimension for each normal radiograph was measured. The mean thickness in the retropharyngeal region ranged from 6.2 mm in the infant to 3.7 mm in the adult, while the mean thickness in the retrotracheal region ranged from 9.2 mm in the preschool group to 12.1 mm in the adult.

Abscess↗