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Biomedical subjects

R Kaul

Publications and source records attributed to R Kaul.

At least 91 records · Page 5Linked to original sources
PubMed1994

Integration of aqueous two-phase extraction and affinity precipitation for the purification of lactate dehydrogenase.

Integration of extraction in aqueous two-phase system and affinity precipitation was investigated as a technique for purification of lactate dehydrogenase (LDH) from porcine muscle extract. An enteric coating polymer, Eudragit S 100, which can be made reversibly soluble and insoluble by change in pH was used as the ligand carrier. The ligand used was Cibacron blue 3GA. The polymer is nearly totally partitioned to the top phase (> 98%) in PEG-dextran aqueous two-phase system. The enzyme, lactate dehydrogenase, was first spontaneously partitioned to the bottom phase in a 6% (w/w) PEG 8000-8% (w/w) dextran T250 phase system. New PEG phase and Eudragit-dye were then added to the bottom phase, which helped in extraction of LDH to the top phase. After a washing step with a fresh bottom phase, Eudragit-dye-target protein affinity complex was precipitated out from the top phase by lowering the pH to 5.1. The enzyme was recovered by treatment of the complex with 0.5 M NaCl with a yield of 54% and a specific activity of 245 units/mg. The purification of LDH by this procedure was better than that obtained by a single step of affinity partitioning.

Acrylic Resins↗
PubMed1994

Major histocompatibility complex class II gene disruption prevents experimental autoimmune myasthenia gravis.

To analyze the impact of lack of MHC class II gene expression, and to demonstrate the direct genetic evidence for the involvement of the MHC class II gene product in the development of experimental autoimmune myasthenia gravis (EAMG), MHC class II gene-disrupted C57BL6 mutant (-/-) and EAMG-susceptible MHC class II wild-type C57BL6 mice (+/+) were evaluated for the clinical and immunopathologic manifestations of EAMG. The deficiency of MHC class II, and therefore, CD4+ T cells, completely prevented the C57BL6 MHC class II mutant (-/-) mice from mounting an autoimmune response to the nicotinic acetylcholine receptor. Further, the mutant (-/-) mice failed to show any immunopathologic and clinical manifestations of EAMG. The data unequivocally provide direct genetic evidence for the essential role of MHC class II molecules in the induction of EAMG, and rule out any pathogenic effector role for MHC class I-restricted CD8+ T cells, gamma delta TCR-bearing cells, or NK cells, which are intact in the MHC class II mutant mice in the induction of EAMG.

Animals↗
PubMed1994

Immunoreactivity with native zona pellucida of antibodies against a 19 amino acid synthetic peptide corresponding to human ZP3.

Immunization of female Syrian hamsters with a 19mer-synthetic peptide corresponding to amino acid sequence 323-341 of human ZP3 and coupled to diphtheria toxoid (DT) led to generation of antibodies against both the peptide as well as DT. Antisera showed positive reaction in ELISA with solubilized isolated zona pellucida (SIZP) from human oocytes. In an indirect immunofluorescence assay, the anti-peptide antibodies bound to zona pellucida of human and bonnet monkey but failed to recognize that of mouse, rabbit, hamster and dog. These studies will help in designing a synthetic peptide based ZP immunocontraceptive vaccine for human application.

Amino Acid Sequence↗
PubMed1994

Abnormal pattern of lung functions in rubber factory workers.

The influence of suspended particulate matter, benzo(e) pyrene, benzo(e) pyrene and benzo(a) anthracene concentration on pulmonary lung functions ie, residual volume, total lung capacity, residual volume/total lung capacity, forced residual capacity were studied in 667 rubber factory workers during 1990-91. The respirable fraction of the particulate size (< 0.5 micron) showed high mean concentration of suspended particulate matter, benzo(a) pyrene, benzo(e) pyrene and benzo(a) anthracene in the compounding section (group III), when compared with vulcanising (group II) and packing loading (group I) units. While comparing the lung functions amongst these groups, the higher results of residual volume, residual volume/total lung capacity ratio, forced respiratory capacity and lower values of total lung capacity were observed in group III workers as compared with other two groups. And also these results seem to be correlated with the high pollutant concentrations to which group III workers were exposed, and reflect a clear combination of obstructive and restrictive pattern of lung functions in them.

Air Pollutants, Occupational↗
PubMed1994

Canavan disease: mutations among Jewish and non-Jewish patients.

Canavan disease is an autosomal recessive leukodystrophy caused by the deficiency of aspartoacylase (ASPA). Sixty-four probands were analyzed for mutations in the ASPA gene. Three point mutations--693C-->A, 854A-->C, and 914C-->A--were identified in the coding sequence. The 693C-->A and 914C-->A base changes, resulting in nonsense tyr231-->ter and missense ala305-->glu mutations, respectively, lead to complete loss of ASPA activity in in vitro expression studies. The 854A-->C transversion converted glu to ala in codon 285. The glu285-->ala mutant ASPA has 2.5% of the activity expressed by the wild-type enzyme. A fourth mutation, 433 --2(A-->G) transition, was identified at the splice-acceptor site in intron 2. The splice-site mutation would lead to skipping of exon 3, accompanied by a frameshift, and thus would produce aberrant ASPA. Of the 128 unrelated Canavan chromosomes analyzed, 88 were from probands of Ashkenazi Jewish descent. The glu285-->ala mutation was predominant (82.9%) in this population, followed by the tyr231-->ter (14.8%) and 433 --2(A-->G) (1.1%) mutations. The three mutations account for 98.8% of the Canavan chromosomes of Ashkenazi Jewish origin. The ala305-->glu mutation was found exclusively in non-Jewish probands of European descent and constituted 60% of the 40 mutant chromosomes. Predominant occurrence of certain mutations among Ashkenazi Jewish and non-Jewish patients with Canavan disease would suggest a founding-father effect in propagation of these mutant chromosomes.

Amidohydrolases↗
PubMed1993

Canavan disease: biochemical and molecular studies.

Deficiency of the enzyme aspartoacylase and the accumulation of N-acetylaspartic acid lead to a severe leukodystrophy and spongy degeneration of the brain, Canavan disease (McKusick 271900). Since our discovery in 1988 of the defect in Canavan disease, 144 patients with Canavan disease have been diagnosed in our laboratory. Most of these children are of Ashkenazi Jewish extraction. The level of enzyme activity can be used for carrier testing. Prenatal diagnosis has been difficult using the enzyme assay owing to the low activity of aspartoacylase in cultured chorionic villus samples or amniocytes. The determination of N-acetylaspartic acid in the amniotic fluid is another parameter for diagnosis; however, the levels may not always be elevated. Bovine and human aspartoacylase have been purified in our laboratory. Bovine and human cDNA and genomic clones have been isolated and six exons have been localized. This information is being used for the study of Canavan disease at the molecular level.

Amidohydrolases↗
PubMed1993

Cloning of the human aspartoacylase cDNA and a common missense mutation in Canavan disease.

Canavan disease, an autosomal recessive leukodystrophy, is caused by deficiency of aspartoacylase and accumulation of N-acetylaspartic acid in brain. We have cloned the human aspartoacylase (ASP) cDNA spanning 1,435 basepairs, and show that the isolated cDNA expresses aspartoacylase activity in bacteria. Furthermore, an A to C base change, at nucleotide 854, has been found in 85% of the 34 Canavan alleles tested so far. This base change results in a missense Glu285Ala mutation that is predicted to be part of the catalytic domain of aspartoacylase. The data suggest that the catalytic centre of aspartoacylase involves a triad of Ser, His and Glu residues. Our findings have implications for diagnosis and screening of Canavan disease.

Amidohydrolases↗
PubMed1992

Interspecies structural diversity among chlamydial genes encoding histone H1.

Recently, a eukaryotic histone H1-like protein has been detected in Chlamydia trachomatis serovar L2 [Hackstadt et al., Proc. Natl. Acad. Sci. USA 88 (1991) 3937-3941; Tao et al., J. Bacteriol. 173 (1991) 2818-2822]. We have cloned the corresponding gene from C. trachomatis serovar J and the Chlamydia psittaci strain mn. Sequencing demonstrated absolute gene identity between the two C. trachomatis serovars L2 and J, but divergence in the C. psittaci strain mn. These differences resulted in altered aa residues (in particular no cysteines) and a smaller molecular mass for H1 from C. psittaci strain mn. The amino acid (aa) sequence comparisons with other histone proteins show best alignment to sea urchin H1, notably in the C terminus, for both C. trachomatis and C. psittaci histones. Chlamydial interspecies aa homology, however, is most conserved at the N terminus, suggestive of a bi-functional role for these unique histone proteins.

Amino Acid Sequence↗
PubMed1992

Antineutrophil cytoplasmic antibody associated with pulmonary hemorrhage: Wegener's granulomatosis?

Antineutrophil cytoplasmic antibodies have been described mainly in patients with Wegener's granulomatosis. It has proven useful for both diagnosis and follow-up in these patients. We have described a patient with diffuse pulmonary hemorrhage in whom the suspicion of Wegener's granulomatosis was raised by the identification of antineutrophil cytoplasmic antibodies.

Antibodies, Antineutrophil Cytoplasmic↗
PubMed1992

Cloning and sequence analysis of the Chlamydia trachomatis spc ribosomal protein gene cluster.

We identified and sequenced a segment of Chlamydia trachomatis chromosomal DNA that shows homology to the Escherichia coli spc and distal region of the S10 ribosomal protein (r-protein) operons. Its sequence revealed a high degree of nucleotide and operon context conservation with the E. coli r-protein genes. The C. trachomatis spec operon contains the r-protein genes for L14, L24, L5, S8, L6, L18, S5, L15, and Sec Y along with the genes for r-proteins L16, L29, and S17 of the S10 operon. The two operons are separated by a 16-bp intragenic region which contains no transcription signals. However, a putative promoter for the transcription of the spc operon was found 162 nucleotides upstream of the CtrL14e start site; it revealed significant homology to the E. coli consensus promoter sequences. Interestingly, our results indicate the absence of any structure resembling an EcoS8 regulatory target site on C. trachomatis spc mRNA in spite of significant amino acid identity between E. coli and C. trachomatis r-proteins. Also, the intrinsic aminoglycoside resistance in C. trachomatis is unlikely to be mediated by CtrL6e since E. coli expressing CtrL6e remained susceptible to gentamicin (MIC less than 0.5 micrograms/ml).

Amino Acid Sequence↗