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Biomedical subjects

A K Dhar

Publications and source records attributed to A K Dhar.

At least 19 recordsLinked to original sources
PubMed2000

Infectious hypodermal and hematopoietic necrosis virus of shrimp is related to mosquito brevidensoviruses.

We purified and sequenced infectious hypodermal and hematopoietic necrosis virus (IHHNV), a small DNA virus of shrimp, from wild Penaeus stylirostris. The virion has a buoyant density of 1.45 as determined by cesium chloride gradient. Analysis of 3873 nucleotides of the viral genome revealed three large open reading frames (ORFs) and parts of the noncoding termini of the viral genome. The left, mid, and right ORFs on the complementary (plus) strand have potential coding capacities of 666 amino acids (aa) (75.77 kDa), 363 aa (42.11 kDa), and 329 aa (37.48 kDa), respectively. The overall genomic organization is similar to that of the mosquito brevidensoviruses. The left ORF most likely encodes the major nonstructural (NS) protein (NS-1) since it contains conserved replication initiator motifs and NTP-binding and helicase domains similar to those in NS-1 from all other parvoviruses. The IHHNV putative NS-1 shares the highest aa sequence homology with the NS-1 of mosquito brevidensoviruses, Aedes densovirus and Aedes albopictus parvovirus. A search for putative splicing sites revealed that the N-terminal region of NS-1 is very likely located in a small ORF upstream of the left ORF. The right ORF is presumed to encode structural polypeptides (VPs), as in other parvoviruses. Two putative promoters, located upstream of the left and right ORFs, are presumed to regulate expression of NS and VP genes, respectively. Thus, IHHNV is closely related to densoviruses of the genus Brevidensovirus in the family Parvoviridae, and we therefore propose to rename this virus Penaeus stylirostris densovirus (PstDNV).

Amino Acid Sequence↗
PubMed2000

Age and nortriptyline concentrations in plasma ultrafiltrate.

OBJECTIVES: Since plasma protein binding of tricyclic antidepressants may be relevant to treatment effects and can be influenced by age-associated factors, we examined both plasma ultrafiltrate and total concentrations of nortriptyline (NT) in patients and compared these to age. We hypothesized negative associations with age of both ultrafiltrate NT and the ratio of ultrafiltrate NT to total plasma NT. METHODS: Patients with major depression at a psychiatric service treated with a stable dose of NT were studied. Trough plasma ultrafiltrate NT concentrations and total plasma NT concentrations were measured by high performance liquid chromatography. Concentrations were corrected for dose. RESULTS: Eighty-seven patients aged 26 - 88 years were studied. Ultrafiltrate NT concentrations and the ratio of ultrafiltrate NT to total NT concentrations were both significantly negatively associated with age. Total NT concentrations were not significantly associated with age. CONCLUSIONS: Relatively low ultrafiltrate NT concentrations in older patients may reflect lower tissue exposure at a given total plasma NT concentration. This could be relevant to toxic and therapeutic effects. Studies of relationships between non-bound drug concentrations and NT treatment outcomes across the age span are needed.

Adult↗
PubMed2000

Determination of the cDNA sequence and mRNA expression of interleukin-1 receptor antagonist in horses.

OBJECTIVE: To determine the complementary DNA (cDNA) sequence of interleukin-1 receptor antagonist (IL-1ra) in horses and compare messenger RNA (mRNA) expression of IL-1ra among horses of various breeds. SAMPLE POPULATION: Blood samples from neonatal and adult horses examined for a variety of diseases. PROCEDURE: A polymerase chain reaction procedure was used to amplify a 220 base pair (bp) portion of the genomic DNA. The upstream and downstream regions of the cDNA sequence were determined by means of 5' and 3' rapid amplification of cDNA ends (RACE) procedures. Northern blot hybridization was used to examine steady-state mRNA expression of IL-1ra. RESULTS: The consensus sequence of the cDNA obtained with the 5'-RACE procedure and the sequence for the 220 bp portion of the genomic DNA represented the putative sequence for secreted IL-1ra. The predicted secreted IL-1ra amino acid sequence contained 176 residues with an in-frame stop codon; the N-terminal 25 amino acid residues resembled the signal peptide reported for human secreted IL-1ra. An approximately 1.3 kilobase pair (kb) band that represented a portion of the 3' end of the coding region and the 3' untranslated region was obtained by use of the 3' -RACE procedure. Northern blot hybridization detected a 1.6 kb transcript in blood RNA from adult Arabian, Belgian, Thoroughbred, and Standardbred horses. CONCLUSIONS: Results suggest that the DNA for equine secreted IL-1ra has a short (29 bp) 5' untranslated region, a 534 bp coding region, and a long (approximately 1,080 bp) untranslated region.

Amino Acid Sequence↗
PubMed1999

Identification of abundant and informative microsatellites from shrimp (Penaeus monodon) genome.

Microsatellites were isolated from P. monodon genomic libraries by direct sequencing of recombinant clones without probe screening. Forty-nine out of 83 clones sequenced contained 99 microsatellite arrays of three or more repeats. When five or more and ten or more repeats were considered, 28 and 14 microsatellites were detected, respectively. The 99 microsatellites were classified as perfect (75%), imperfect (6%), compound perfect (3%) and compound imperfect (16%). The abundance of di-, tri-, tetra- and hexanucleotide repeats were 67%, 20%, 9% and 3%, respectively. The dinucleotide repeats included 36 (CT)n, 31 (GT)n, 17(AT)n and 3 (CG)n. One octanucleotide repeat (ATTTATTC)5 was found within a large repeat sequence. Optimal annealing temperatures were determined for PCR using 11 primer sets encompassing 15 microsatellites. Ten primer sets provided successful amplifications with allele sizes generally ranging from 139 to 410 bp. All these primers amplified polymorphic loci with PIC values ranging from 0.63 to 0.96. Two primer sets amplified additional bands which can easily be distinguished from the bands of the main locus. Three out of 10 P. monodon microsatellites also amplified alleles in P. vannamei. The abundance and informative nature of P. monodon microsatellites and their potential for cross-species amplification make them useful for genetic studies.

Animals↗
PubMed1997

Molecular characterization of coat protein genes of serologically distinct isolates of potato virus Y necrotic strain.

The cost protein (CP) genes of two potato virus Y necrotic isolates (N27 and a mutant strain N27-92), which differed in their reactivity to a monoclonal antibody (mab), were characterized. Both isolates could be detected by mab 4E7, but mab VN295.5 selectively reacted to N27 and not to N27-92. The CP genes of both isolates coded for 267 amino acids with approximately 99.0% identity at both the nucleotide and the amino acid levels. nucleotide sequence comparison indicated five substitutions in N27-92 compared with N27. Three of these changes resulted in substitution of amino acids. Two transitions (A-->G) in N27-92 changed threonine to alanine and lysine to arginine at positions 7 and 55, respectively, whereas a A-->T transversion changed asparagine to isoleucine at positions 27. The surface probability curves of both the isolates could almost be superimposed, except at amino acid positions 7 and 27. Since amino acid substitution at position 55 is conservative, changes from polar to hydrophobic amino acids (threonine-->alanine and asparagine-->isoleucine) at positions 7 and 27 might have changed the epitope(s) of N27-92, abolishing its detection by mab VN295.5.

Amino Acid Sequence↗
PubMed1996

Comparative evaluation of the clinical efficacy and safety of ondansetron and metoclopramide in the prophylaxis of emesis induced by cancer chemotherapy regimens including cisplatin.

The efficacy and safety of ondansetron was evaluated and compared with metoclopramide in 93 patients receiving cisplatin containing cancer chemotherapy in a randomized, parallel group study. 8 mg Ondansetron i.v. was administered prior to chemotherapy followed by two further doses of 8 mg i.v. over the first 24 hours. Ondansetron 8 mg b.d. was then administered orally for the next 5 days. The metoclopramide dosage was 20 mg i.v. prior to chemotherapy followed by 2 i.v. doses of 10 mg each, 4 hours apart. For the next 5 days, an oral dose of 20 mg metoclopramide was administered. The anti-emetic efficacy of ondansetron as a prophylactic treatment was found to be significantly more effective than metoclopramide both during the acute and delayed phase of nausea and vomiting. Both treatments were well tolerated with no reported side-effects.

Adult↗
PubMed1996

Molecular analysis of a RAPD marker (B20) reveals two microsatellites and differential mRNA expression in Penaeus vannamei.

We previously reported a population-specific DNA fragment (B20) in Penaeus vannamei shrimp, fragment found using the randomly amplified polymorphic DNA (RAPD) procedure, that was present in Population 2 but not in Populations 1 and 4. The specific objectives of this study were to clone and sequence this genetic marker, determine if all or part of this cloned sequence could be found in any of the other populations in which this marker could not be amplified, and examine if this marker represents a functional gene by examining the steady-state levels of mRNA expression using Northern blot hybridization. Sequence information of the 1259-bp B20 clone revealed two microsatellites and two candidate open reading frames. Although the entire B20 sequence could only be amplified in Population 2 (from Ecuador), Population 3 (a hybrid of Populations 1 and 2), and a few individuals from wild Ecuadorian shrimp samples, portions of the B20 DNA could be amplified in individuals from Populations 1, 2, 3, candidate Population 4, and wild Ecuadorian samples. These microsatellites vary in size between populations and families. Northern blot hybridization analysis using radiolabeled B20 probe detected two mRNA transcripts of approximately 1.5 and 2.0 kb. Expression data throughout development indicated that these transcripts were present at low levels in nauplii from two of the three crosses examined using broodstocks of Population 1. Higher levels were observed in postlarvae (PL) 6, PL8, and PL10 in one of the three crosses. Individuals from all crosses showed higher levels of expression in the juvenile tail muscle. The mRNA transcript levels were undetected in zoea 3, PL2, and PL4 stages of development and broodstock tail muscle. The levels of expression of B20 mRNA transcripts varied significantly between Populations 1, 2, 3, 4, and wild Ecuadorian individuals as well as between families and within individuals representative of seven families from Population 1. In summary, the B20 clone revealed the presence of two microsatellites that vary in size between populations. These microsatellites will be useful for estimating genetic diversity within and between populations, identifying family-specific markers, and mapping loci responsible for economically important traits in penaeid shrimp. The mRNA levels detected by the B20 clone showed differential expression during development, and the pattern of expression was influenced by the genetic background of the parental crosses used.

Animals↗
PubMed1995

Rapid cytoreduction in childhood leukemic hyperleukocytosis by conservative therapy.

Childhood leukemic hyperleukocytosis poses a serious threat to life because of its associated metabolic complications. The present prospective trial utilized conservative management of childhood acute lymphoblastic leukemia with hyperleukocytosis (total white cell count equal or > 100 x 10(9)/L) by intravenous hydration, urinary alkalinization, and allopurinol presenting without severe life-threatening complications. The median reduction in WBC count was 81.51% (range: 66-98.8%) within a median period of 36 hours (range: 12-60 hours) following hospitalization. There were no failures or treatment related complications. Thus we conclude that in childhood acute lymphoblastic leukemia, hyperleukocytosis can be managed safely and effectively with intravenous hydration, urinary alkalinization, and allopurinol before starting any specific anti-leukemic chemotherapy avoiding risk-associated cranial irradiation, leukapheresis, and exchange transfusion.

Adolescent↗
PubMed1995

Evaluating efficiency of bone marrow harvest and its manipulation--role of CD 34 positivity.

We evaluated harvested marrow cells for total nucleated cells (27.49 x 10(9)), absolute 'lymphocyte' count (6.29 x 10(9)) and CD 34 positive cells (3.57 x 10(9)). The same parameters were studied after in vitro manipulation to remove RBCs and plasma. Reinfused WBCs contained 12.87 x 10(9) nucleated cells, 4.25 x 10(9) absolute 'lymphocyutes' and 3.34 x 10(9) CD 34 positive cells. The corresponding figures for loss during in vitro manipulation (tubing, RBCs and plasma) are 14.62 (53.18%), 2.04 (32.43%) and 0.23 x 10(9) (6.44%) cells respectively. Therefore CD 34 positivity may be a better indicator of total yield, loss during manipulation and reinfusion of hemopoietic progenitor cells in bone marrow transplantation.

Antigens, CD34↗
PubMed1995

Interleukins.

Explore the source record for details and available documents.

Humans↗
PubMed1994

Improvement in the sensitivity of PVYN detection by increasing the cDNA probe size.

Cloned cDNA to a North American isolate of tobacco veinal necrotic strain of potato virus Y (PVYN) RNA was used for the detection of PVYN in diseased samples. Digoxigenin-labelled cDNA probes were prepared from approximately 0.56 kb, approximately 1.2 kb, approximately 2.5 kb, and approximately 3.25 kb overlapping clones representing the 3'-terminus of the PVYN genome. It was shown that the probe sizes, as determined by alkaline gel-electrophoresis, generally corresponded to the size of the template cDNA used. The sensitivity of detection of PVYN was maximum using the largest probe and the sensitivity generally decreased with a decrease in probe size. Five pg of homologous purified PVYN RNA was detected with the approximately 3.25 kb probe, and 1000 pg of PVYN RNA was required for the approximately 0.56 kb probe. The different levels of sensitivity of detection were also apparent when crude nucleic acid extracts from PVYN and PVYO infected plants were used. In comparison with tobacco bioassay, and dot immunobinding assay nucleic acid hybridization was found to be more sensitive.

DNA Probes↗
PubMed1994

Molecular cloning and sequencing of the capsid and the nuclear inclusion protein genes of a North American PVYN isolate.

The sequence of the 3'-terminal 3258 nucleotides of a tobacco veinal necrosis strain of a potato virus Y (PVYN) isolate from North America was determined. The sequence revealed an open reading frame of 2931 nucleotides, of which the start codon was not identified. The nontranslated region contains 327 nucleotides upstream of a poly(A) tract. The open reading frame encodes a large polyprotein containing 976 amino acids. The data indicate that the coat protein (CP) and the nuclear inclusion protein (NIb) are derived from the large polypeptide by proteolytic cleavage similar to many other potyviruses. The putative cleavage sites of NIa/NIb and NIb/CP correspond to Q/A and Q/G sequences, respectively, as in other PVYN isolates. The CP and NIb contain 267 and 519 amino acid residues, respectively. Higher sequence homology of CP was observed with other PVYN isolates than with the PVYO isolates.

Amino Acid Sequence↗
PubMed1991

Verbal memory and plasma drug concentrations in elderly depressives treated with nortriptyline.

Performance on a verbal memory task and affective state were assessed in geriatric major depressives before and during 6 weeks of treatment with nortriptyline (NT) in a fixed-dose design study. Higher plasma NT concentration was associated with poorer free recall but better affective outcome. In contrast, higher plasma Z-10-hydroxynortriptyline (Z-10-OH-NT) concentration was associated with more efficient free recall. Concentration-effect relationships were noted in patients later classified as cognitively unimpaired using the Dementia Rating Scale after optimal treatment, rather than in those with residual cognitive impairment.

Aged↗
PubMed1988

Isomers of 10-hydroxynortriptyline in geriatric depression.

In geriatric, depressed inpatients treated with nortriptyline (NT), total unconjugated plasma concentrations of the Z isomer of the 10-hydroxylated metabolite (10-OH-NT) were determined simultaneously with concentrations of the E isomer by high-performance liquid chromatography. Z-10-OH-NT concentrations averaged 14% of E-10-OH-NT concentrations.

Aged↗