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Biomedical subjects

M J Levin

Publications and source records attributed to M J Levin.

At least 19 recordsLinked to original sources
PubMed1996

Structural and functional analysis of the B cell epitopes recognized by anti-receptor autoantibodies in patients with Chagas' disease.

IgG fractions of patients were screened for autoantibodies against the beta1- and beta2-adrenoceptors and the M2 acetylcholine receptor by enzyme immunoassays and surface plasmon resonance (SPR) using peptides corresponding to the second extracellular loop of these receptors. A high prevalence of anti-M2 acetylcholine receptor and, in decreasing order, of anti-beta1- and anti-beta2-adrenoceptor autoantibodies was shown. The enzyme immunoassays and the SPR studies on the anti-beta1 adrenoceptor and the M2 acetylcholine receptor autoantibodies were dependent on the ionic strength of the interaction buffer, suggesting the importance of electrostatic interactions in Ab recognition. IgG fractions showed chronotropic effects on neonatal rat cardiomyocytes in vitro. The positive chronotropic effect was enhanced in the presence of 1 microM of atropine, demonstrating a muscarinic stimulation by the IgG fractions in the presence of a beta-adrenergic stimulation, which was blocked by the use of 1 microM of the beta1-selective antagonist bisoprolol. The beta2-selective antagonist ICI 118,551 only partially inhibited the positive chronotropic effect induced by the IgG fractions, confirming the minor functional importance of autoantibodies against the beta2-adrenoceptor. Affinity-purified Abs confirmed that Abs against the beta1-adrenoceptors and the M2 muscarinic receptors exist together with an Ab population recognizing a cross-reactive epitope on both receptors. This epitope could be identified as a polyanionic stretch present in the second extracellular loop of both the beta1-adrenoceptor and the M2 acetylcholine receptor. This stretch corresponds to the previously determined cross-reactive epitope between the P0 ribosomal protein of Trypanosoma cruzi and the beta1-adrenoceptor.

Adrenergic beta-Antagonists↗
PubMed1996

The varicella vaccine. Prevention of herpes zoster.

The live attenuated varicella vaccine offers some hope that the frequency or severity of herpes zoster might be reduced. Universal immunization with this vaccine should result in less latent varicella-zoster virus in dorsal root and cranial nerve ganglia than that which occurs following varicella. Moreover, the vaccine virus is not well adapted for growth in human cells at normal body temperature. Thus, reduced virus for reactivation, and less robust replication, may lessen the problem of herpes zoster in vaccinees. For those individuals who have already had varicella, the risk of herpes zoster is closely related to the loss of varicella-zoster virus cell-mediated immune responses, which decline with aging (or immune suppression). In aging individuals these immune responses can be enhanced by booster immunization with the varicella vaccine, suggesting that a vaccine to prevent herpes zoster is feasible.

Aged↗
PubMed1996

The frequency and consequences of varicella exposure and varicella infection in children receiving maintenance therapy for acute lymphoblastic leukemia.

PURPOSE: The frequency and cost of varicella and varicella exposure were determined in children receiving maintenance chemotherapy for acute lymphocytic leukemia, and the cost of a preventative strategy using the varicella vaccine was estimated. PATIENTS AND METHODS: Retrospective analysis of clinic and hospital records for 472 children at 12 sites who were receiving maintenance chemotherapy on Protocol 105 of the Childrens Cancer Group. RESULTS: During a mean maintenance period of 2 1/2 years there were 120 exposures to varicella among susceptible children (10/100 patient-years). During the same period there were 60 cases of varicella (4.6/100 patient-years). Half of the cases of varicella occurred without a known exposure. Exposures and varicella resulted in significant omission or delay in chemotherapy. Total medical charges for varicella-related events were $492,000 ($470 per varicella exposure; $7,450 per case of varicella). A proposed preventative strategy using varicella vaccine after 6 months of maintenance therapy would theoretically reduce varicella-related charges by 80%. CONCLUSIONS: Varicella exposure and varicella are common in this patient population. The use of varicella vaccine during the early maintenance period should be considered to prevent these events. This strategy is likely to be safe, and will save significant medical charges, drug omission, disease-related morbidity, hospitalization, and work and school disruption.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1996

Comparison of two methods for detecting varicella-zoster virus antibody with varicella-zoster virus cell-mediated immunity.

We evaluated an enzyme-linked immunoassay (EIA; BioWhittaker) and a latex agglutination (LA; Becton Dickinson) for varicella-zoster virus (VZV) antibody determination, using cell-mediated immunity (CMI) as a "gold standard." VZV EIA had a sensitivity, specificity, positive predictive value, and negative predictive value of 87, 91, 87, and 91%, respectively, compared with CMI. Correlation was excellent except when the varicella index was 0.9 to 1.2. We defined sera with varicella indices of 0.9 to 1.2 as indeterminate. LA had a sensitivity, specificity, positive predictive value, and negative predictive value of 96, 91, 97, and 90%, respectively, compared with EIA. LA reactivity only at a 1:2 dilution did not correlate with CMI, but sera reactive at dilutions of > or = 1:8 indirectly did. We defined indeterminate sera as those reactive at 1:2 and nonreactive at 1:8. EIA and LA were equivalent for determining VZV immune status, and both methods required modified criteria of interpretation to increase their specificity.

Antibodies, Viral↗
PubMed1995

Cloning and sequence analysis of the TcP2 beta cDNA variants of Trypanosoma cruzi.

P2 beta acidic ribosomal protein is a relevant antigen in Chagas' disease. cDNA cloning demonstrated that Trypanosoma cruzi expresses at least six types of TcP2 beta transcripts that differed by point nucleotides substitutions. The distribution and type of mutations seemed to follow the typical structural organization of eukaryotic acidic ribosomal proteins. Most of the synonymous changes clustered in the amino-terminus, suggesting that conservation of this domain was crucial for an equivalent functional ability of each TcP2 beta variant to bind to the ribosome. Interestingly, most amino acid changes in the central-globular and hinge domains caused polymorphism in putative phosphorylatable sites.

Amino Acid Sequence↗
PubMed1995

Molecular mimicry between the immunodominant ribosomal protein P0 of Trypanosoma cruzi and a functional epitope on the human beta 1-adrenergic receptor.

Sera from chagasic patients possess antibodies recognizing the carboxy-terminal part of the ribosomal P0 protein of Trypanosoma cruzi and the second extracellular loop of the human beta 1-adrenergic receptor. Comparison of both peptides showed that they contain a pentapeptide with very high homology (AESEE in P0 and AESDE in the human beta 1-adrenergic receptor). Using a competitive immunoenzyme assay, recognition of the peptide corresponding to the second extracellular loop (H26R) was inhibited by both P0-14i (AAAESEEEDDDDDF) and P0-beta (AESEE). Concomitantly, recognition of P0-beta was inhibited with the H26R peptide. Recognition of P0 in Western blots was inhibited by P0-14i, P0-beta, and H26R, but not by a peptide corresponding to the second extracellular loop of the human beta 2-adrenergic receptor or by an unrelated peptide. Autoantibodies affinity purified with the immobilized H26R peptide were shown to exert a positive chronotropic effect in vitro on cardiomyocytes from neonatal rats. This effect was blocked by both the specific beta 1 blocker bisoprolol and the peptide P0-beta. These results unambiguously prove that T. cruzi is able to induce a functional autoimmune response against the cardiovascular human beta 1-adrenergic receptor through a molecular mimicry mechanism.

Amino Acid Sequence↗
PubMed1995

Neonatal enterovirus infection: virology, serology, and effects of intravenous immune globulin.

A prospective study of the virology of and serological responses to enterovirus infection in 16 neonates (< or = 2 weeks of life) and their mothers was performed. At study entry, 11 neonates did not have detectable serum neutralizing antibody to their own viral isolates, despite the presence of neutralizing antibody in 9 of 11 mothers of these infants. Viremia and viruria were demonstrated in 8 and 7 neonates, respectively, with maximal detected titers of 6.3 x 10(3) 50% tissue culture infective dose per mL (TCID50) and 6.8 x 10(1) TCID50/mL, respectively. Viremia was associated with onset of illness in the first 5 days of life, low initial serum neutralization titer, and the presence of echovirus serotypes. Randomized administration of intravenous immune globulin (IVIG; 750 mg/kg) to nine neonates overall modestly increased serum neutralization titers but did not reduce the daily incidence of viremia and viruria compared with that of controls. However, receipt of IVIG containing a neutralization titer of > or = 1:800 to the patients' own viral isolates was associated with significantly higher serum neutralization titers and more rapid cessation of viremia and viruria. Future trials of IVIG for neonatal enterovirus disease should assess the efficacy and safety of higher or repeated doses of this agent and/or of IVIG selected for their high titers to frequently circulating and/or particularly virulent enterovirus serotypes.

Antibodies, Viral↗
PubMed1995

Use of cytomegalovirus immunoglobulin in multiply transfused premature neonates.

We undertook a randomized, placebo-controlled, double blind trial of cytomegalovirus (CMV) immunoglobulin (CMVIG) for prevention of CMV-associated disease in 183 multiply transfused, premature neonates. CMVIG (150 mg/kg) or placebo was given within 24 hours of the first transfusion and at Day 10. If an intravenous catheter was still in place an additional dose was given between Days 20 and 30. The globulin and placebo groups were well-matched with respect to birth weight, gestational age, Apgar score, birth to a CMV-seropositive mother, requirement for assisted ventilation and exposure to CMV-positive, unscreened blood products. Among infants followed for more than 10 days, 18 (10.5%) developed CMV infection; 9 had symptomatic CMV disease (5 placebo; 4 CMVIG). Among infants born to a CMV-seropositive mother, CMVIG use was associated with a CMV syndrome rate of 3.2% (95% confidence interval, 0.2 to 18.5%) compared to 12.5% (95% confidence interval, 4.5 to 27.6%) among placebo recipients (P = 0.163). Among placebo recipients infants born to CMV-seropositive mothers were more likely to have a virologically confirmed CMV syndrome than those born to a CMV-seronegative mother, despite receipt of blood not screened for CMV antibody (P = 0.012). Multivariate analysis demonstrated that two factors were independently associated with CMV acquisition: the volume of CMV-seropositive blood products transfused (P = 0.005); and birth to a CMV-seropositive mother (P = 0.006). Infusions of CMVIG were well-tolerated. This study reaffirms that perinatally acquired CMV disease is more common among infants born to CMV-seropositive mothers than CMV-seronegative mothers, even without use of CMV-screened blood products.

Antibodies, Viral↗
PubMed1995

Recurrent brainstem encephalitis associated with herpes simplex virus type 1 DNA in cerebrospinal fluid.

A 47-year-old man had recurrent signs and symptoms of brainstem encephalitis over a 4-year period. Although CSF viral cultures were repeatedly negative, herpes simplex virus type 1 (HSV-1) DNA was detected in CSF by polymerase chain reaction (PCR). HSV-1-specific antibodies were absent at the time of the first positive PCR test, but CSF seroconversion to high HSV-1-specific antibody titer subsequently occurred. CSF antibody to cytomegalovirus (CMV) and varicella-zoster virus (VZV) was not detectable, nor could CMV, VZV, or Epstein-Barr virus nucleic acid be detected by CSF by PCR. This is the first report of the use of CSF PCR for the rapid antemortem diagnosis of herpetic brainstem encephalitis.

Brain Stem↗
PubMed1994

Herpes simplex virus infection as a cause of benign recurrent lymphocytic meningitis.

OBJECTIVE: To identify the role of herpes simplex virus (HSV) in causing benign recurrent lymphocytic meningitis. DESIGN: Prospective cohort study. SETTING: Tertiary referral center. PATIENTS: 20 consecutive patients with a provisional diagnosis of benign recurrent lymphocytic meningitis had cerebrospinal fluid specimens submitted between 1990 and 1993 to the diagnostic virology laboratory. Thirteen patients met our criteria for benign recurrent lymphocytic meningitis. MEASUREMENTS: Herpes simplex virus DNA was detected in cerebrospinal fluid specimens using the polymerase chain reaction, followed by hybridization with a HSV-specific DNA probe. Herpes simplex virus type 1 and type 2 DNA products were distinguished by digestion with restriction enzymes and analysis by gel electrophoresis. Anti-HSV antibodies in cerebrospinal fluid were detected by immunoblot. RESULTS: The patients had 3 to 9 attacks (mean, 4.6 attacks) of benign recurrent lymphocytic meningitis during periods ranging from 2 to 21 years (mean, 8.4 years). Three of 13 patients had known recurrent genital herpes. Cerebrospinal fluid analysis showed 48 to 1600 cells/microL, glucose levels of more than 2.22 mmol/L (40 mg/dL), and protein levels of 41 to 240 mg/dL (0.41 to 2.4 g/L). Herpes simplex virus DNA and anti-HSV antibodies were detected in cerebrospinal fluid samples in 11 of 13 patients (84.6%; 95% CI, 55% to 98%). Ten of these 11 patients had HSV type 2 DNA and HSV type 2 antibodies. One patient had HSV type 1 DNA and HSV type 1 antibodies in the cerebrospinal fluid. The remaining two patients had only anti-HSV type 2 antibodies. CONCLUSIONS: Herpes simplex virus, predominantly HSV type 2, was the major agent causing benign recurrent lymphocytic meningitis that met our specified diagnostic criteria.

Adult↗
PubMed1994

Clinical application of responder cell frequency estimates with four years of follow up.

Limiting dilution cultures have been used to estimate the frequency of T cells which respond to antigen stimulation in vitro, but nothing is known of the reproducibility of this assay when applied to human blood. We developed a simplified form of limiting dilution culture in which blood mononuclear cells were diluted in round bottom 96-well plates and cultured for 10 days. The assay was used to estimate the frequency of blood mononuclear cells proliferating in response to varicella-zoster virus antigen. 250 subjects aged 25-87 years were studied: 95 of these subjects had annual measurements repeated over a 4 year period. The coefficients of variation for intra-assay replicates was 5%, and for inter-assay comparisons was 17.6% and 26% for tests at a 1 or 3 month interval respectively. For subjects studied at 1 year intervals the coefficient of variation was 42% with the total variability equally distributed between the variation between subjects and the variation within subjects. These data provide the first quantitative data to validate limiting dilution cultures for the long term in vitro measurement of human T cell responses.

Adult↗
PubMed1994

A short interspersed repetitive element provides a new 3' acceptor site for trans-splicing in certain ribosomal P2 beta protein genes of Trypanosoma cruzi.

Four Trypanosoma cruzi genomic DNA fragments carrying different TcP2 beta genes have been isolated and sequenced. Three of them had a single TcP2 beta gene, while the 3.8-kb-long DNA segment encoding the TcP2 beta-H1.8 locus showed two TcP2 beta genes arranged in tandem. These genes were physically connected by a 428-bp-long DNA sequence that was also located immediately 5' to the first gene and immediately 3' to the second. Comparison of the 4 TcP2 beta gene loci, suggested that the insertion of this repeated element originated the duplication of its target sequence, a poly(dT) stretch. Approximately 1200 copies of this short sequence, named short interspersed repetitive element (SIRE), were found scattered in the genome. Analysis of the 5' non-coding regions of different TcP2 beta mRNAs, and RNA-PCR experiments suggested that the insertion of a SIRE upstream of a TcP2 beta-H1.8 gene introduced a new 3' spliced leader (SL) acceptor site in the TcP2 beta-H1.8 pre-mRNAs, encoded within the SIRE. Consequently, in the mature H1.8 mRNA the SL sequence is followed by 38 bases directly transcribed from the SIRE. Structural and functional features of this repeated element reveal similarity to the short interspersed repetitive DNA sequences detected in the genomes of several microorganisms.

Animals↗
PubMed1994

Safety and immunogenicity of a purified haemagglutinin antigen in very young high-risk children.

Forty-three high-risk preterm children received either one of three doses of purified hemagglutinin antigen (HA) (7.5 micrograms/0.25 ml, 22.5 micrograms/0.25 ml or 67.5 micrograms/0.25 ml) or standard split product vaccine (ST) (22.5 micrograms/ml dose) over the 1990-1991 influenza season. Components for all vaccines included A/Shanghai 16/89, A/Taiwan 1/86 and B/Yamagata 16.88. Sera for antibody was drawn before, 6 weeks and 4 months after the first vaccine dose. The study was randomized and blinded. All children received two 0.25 ml doses of vaccine 4 weeks apart. No significant local or systemic reactions occurred. Six weeks after the first dose, children receiving ST vaccine had significantly higher seroconversion rates to A/Shanghai (p = 0.03) and to A/Taiwan (p = 0.01) than did those receiving equivalent HA vaccine. However, seroconversion rates were significantly higher for those children receiving the highest HA dose. All four vaccine groups responded poorly to B/Yamagata. Geometric mean titres were low for all groups and declined over 4 months. These results suggest that the equivalent dose of HA vaccine offers no advantage over ST vaccine in the immunization of high-risk preterm children.

Antibodies, Viral↗