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P D Mehta

Publications and source records attributed to P D Mehta.

106 records · Page 6Linked to original sources
PubMed1975

Measles antibodies and immunoglobulins in sera from patients with subacute sclerosing panencephalitis (SSPE) and from an infected ferret.

Cellulose acetate electrophoresis of sera from 2 patients with SSPE revealed a slow-moving and a fast-moving gamma-globulin band. The IgG fractions from sera were isolated by the combination of starch block electrophoresis, Sephadex gel filtration and isoelectric focusing techniques. The purity of each protein was tested by immunoelectrophoresis using a potent goat anti-whole human serum. The isolated IgG preparations were tested in HI, CF and N tests against measles virus envelope, measles virus nucleocapsid and whole measles virus, respectively. The results showed that isolated IgG fractions, having different electrophoretic mobilities, contained high titers of HI, CF and N antibodies, and these titers were proportional to the protein concentration of IgG. Although both IgG fractions appeared to show an increase of K-type chain, neither fraction was devoid of L-type chain. These results indicate that the homogeneous IgG bands observed in the SSPE serum were not monoclonal as they failed to show selective increase of one type of light chain and uneven distribution of measles antibody activity. These findings were compared with the results from a ferret, which developed encephalitis 2 months after intracerebral inoculation with cell-associated measles virus derived from the brain of an SSPE patient. The electrophoretic pattern of the ferret serum was similar to that of the human. High titers of measles HI and N antibodies were seen in the isolated slow- and fast-moving IgG's. The similarities observed in the human and ferret IgG's, with respect to homogeneous bands in electrophoresis and measles HI and H antibody activities, suggest that the ferret may be a useful animal model for studying the immune mechanism of SSPE.

Animals↗
PubMed1975

Comparative studies of Visna and Maedi viruses as antigens.

Rabbits were immunized with purified visna and maedi viruses, using complete Freund adjuvant, in footpad and intramuscular sites. The resulting antisera and their isolated immunoglobulin G (IgG) and M (IgM) classes were evaluated by tanned-cell passive hemagglutination (PHA), complement fixation, gel diffusion, and virus neutralization tests. Early, intermediate, and late bleedings showed increasingly high antibody activities by the PHA, complement fixation, and gel diffusion tests. The activities were associated mainly with the IgG class, although low, but significant activities were also found in the IgM class, as detected by PHA and complement fixation tests. Both antibody classes appeared at the same time during the course of immunization. The viruses, when tested against specific rabbit anti-visna and anti-maedi sera in gel diffusion tests, showed the presence of one to two precipitin lines depending upon the antibody concentration of the sera. A low amount of neutralizing activity was demonstrated in late bleedings but was not seen in earlier bleedings. The neutralizing activity against visna virus in immunized rabbit sera was found to be associated only with the IgG class. Visna and maedi viruses appeared to be immunologically identical when examined in gel diffusion tests and showed the same degree of inhibition when compared in passive hemagglutination inhibition test using antisera made specific for each virus.

Animals↗
PubMed1974

Neutralizing activity in isolated serum antibody fractions from visna-infected sheep.

The neutralization technique was used to detect specific antibodies against visna virus in isolated immunoglobulin (Ig) G(1), IgG(2), and IgM fractions of visna-infected sheep serum. The neutralizing antibodies were present chiefly in the IgG(1) class. Low amount of activity was demonstrated in the IgM class, but no significant activity was seen in the IgG(2) class.

Animals↗
PubMedDate not supplied

Alpha 1-antichymotrypsin and IL-1 beta are not increased in CSF or serum in Alzheimer's disease.

Chronic inflammation associated with the amyloid plaques may represent an acute phase response in the brain. We quantitated the levels of two inflammatory markers; alpha 1-antichymotrypsin (alpha 1-ACT) and interleukin 1 beta (IL-1 beta) in paired serum and cerebrospinal fluid (CSF) samples from 40 patients with Alzheimer's disease (AD), 20 patients with Parkinson's disease (PD), and 42 age-matched controls. No differences in serum or CSF levels of either alpha 1-ACT or IL-1 beta were found between the groups. However, some AD patients had increased alpha 1-ACT index, suggesting an intrathecal production of alpha 1-ACT. Although alpha 1-ACT or IL-1 beta might be involved in the pathogenesis of AD, our results show that their measurement in serum or CSF is not valuable to support the clinical diagnosis of AD.

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PubMedDate not supplied

Relationship between apoE genotype and CSF beta-amyloid (1-42) and tau in patients with probable and definite Alzheimer's disease.

We investigated the usefulness of cerebrospinal fluid (CSF) beta-amyloid42 (Abeta42), beta-amyloid40 (Abeta40) and tau analyses in the diagnosis of Alzheimer's disease (AD). The study included 41 definite AD cases, 80 patients with probable AD. 27 with other dementias and 39 neurological controls. Abeta42, Abeta340 and tau protein concentrations in CSF were measured of using ELISA assays. Abeta42 levels were decreased and tau increased in AD. Combination of Abeta42 and tau resulted a sensitivity of 50.4% for AD and specificities of 94.8% for controls and 85.2% for other dementias. Ninety-one percent of the patients with Abeta42 below the cutoff value (340 pg/ml) and tau above the cutoff value (380 pg/ml) had AD. AD patients carrying apoE epsilon4 allele had lower Abeta42 (P < 0.005) and higher tau (P < 0.05) levels than those without an E4 allele, and 18 (81.8%) of the 22 AD patients who had normal Abeta42 and tau levels were apoE e4 allele non-carriers. Low Abeta42 and high tau concentration in CSF strongly support the diagnosis of AD. Measurement of Abeta42 may help the early diagnosis of cases at risk for AD such as apoE E4 allele carriers.

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PubMedDate not supplied

Apolipoprotein E genotype and amyloid load in Alzheimer disease and control brains.

We investigated the effect of apolipoprotein E (apoE) genotype on amyloid load in the frontal and cerebellar cortices of 24 patients with definite Alzheimer disease (AD) and 19 controls. Amyloid load was examined by using two methods: 1) acid-extractable amyloid beta-protein (A beta) and insoluble A beta levels of frontal and cerebellar cortices were measured by using enzyme-linked immunosorbent assay, and 2) all types of amyloid plaques and neurofibrillary tangles (NFT) in the frontal cortices were counted after silver staining. Acid-extractable A beta and insoluble A beta levels were higher in AD brains than controls, although there was an overlap between the groups. Acid-extractable A beta and insoluble A beta levels were higher from AD and controls with the apoE epsilon 4 alleles than those without such alleles. However, the differences did not reach statistical significance in AD group. There was no correlation between acid-extractable A beta or insoluble A3 levels and the number of amyloid plaques in AD and control brains. However, insoluble A beta levels correlated positively with the number of NFT in AD brains. Our results show that although apoE epsilon 4 influences the accumulation of A beta, multiple processes may be involved in deposition of A beta in the brain.

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