PubMed Health⌕ Search

Biomedical subjects

S Parmar

Publications and source records attributed to S Parmar.

At least 19 recordsLinked to original sources
PubMed2006

Ex vivo expanded umbilical cord blood T cells maintain naive phenotype and TCR diversity.

BACKGROUND: Umbilical cord blood (CB) is a promising source of hematopoietic stem cells for allogeneic transplantation. However, delayed engraftment and impaired immune reconstitution remain major limitations. Enrichment of donor grafts with CB T cells expanded ex vivo might facilitate improved T-cell immune reconstitution post-transplant. We hypothesized that CB T cells could be expanded using paramagnetic microbeads covalently linked to anti-CD3 and anti-CD28 Ab. METHODS: CB units were divided into three fractions: (1) cells cultured without beads, (2) cells cultured with beads and (3) cells cultured with beads following CD3+ magnetic enrichment. All fractions were cultured for 14 days in the presence of IL-2 (200 IU/mL). RESULTS: A mean 100-fold expansion (range 49-154) of total nucleated cells was observed in the CD3+ magnetically enriched fraction. Following expansion, CB T cells retained a naive and/or central memory phenotype and contained a polyclonal TCR diversity demonstrated by spectratyping. DISCUSSION: Our data provide evidence that naive and diverse CB T cells may be expanded ex vivo and warrant additional studies in the setting of human CB transplantation.

Antigens, CD↗
PubMed2004

Coordinated expression of sulfate uptake and components of the sulfate assimilatory pathway in maize.

A high-affinity-type sulfate transporter (Group 1: ZmST1;1, Accession No. AF355602) has been cloned from maize seedlings by RT-PCR. Tissue and cell specific localisation of this sulfate transporter has been determined along the developmental gradient of the root and in leaves of different ages. In S-sufficient conditions there was uniform low expression of ZmST1;1 in the root and very low expression in the leaves. Increased mRNA abundance and sulfate influx capacity indicated that S-starvation increased ZmST1;1 expression in roots, especially at the top of the root (just behind the seed, the area possessing most laterals and root hairs) compared to the root tip. Similarly a group 2, probable low affinity-type sulfate transporter, ZmST2;1, and also ATP-sulfurylase and APS-reductase but not OAS(thiol)lyase were induced by S-starvation and showed highest expression in the upper section of the root. S-starvation increased root/shoot ratio by 20 % and increased root lateral length and abundance in the region closest to the root tip. As the increase in root proliferation was not as great as the increase in mRNA pools, it was clear that there was a higher cellular abundance of the mRNAs for sulfate transporters, ATP-sulfurylase, and APS-reductase in response to sulfur starvation. In the leaves, the sulfate transporters, ATP-sulfurylase and APS-reductase were induced by S-starvation with the most mature leaf showing increased mRNA abundance first. In situ hybridization indicated that ZmST1;1 was expressed in epidermal and endodermal cell layers throughout the root whilst OAS(thiol)lyase was highly expressed in the root cortex.

Base Sequence↗
PubMed2004

Real-time PCR investigation into the importance of Fusobacterium necrophorum as a cause of acute pharyngitis in general practice.

Fusobacterium necrophorum is recognized as the cause of a severe life-threatening illness characterized by bacteraemia with metastatic abscesses following an acute sore throat (Lemierre's disease). However, the importance of F. necrophorum as a cause of simple sore throat in the community is unknown. Using quantitative real-time PCR with primers targeting the rpoB gene, 100 routine throat swabs collected from patients presenting to general practitioners with pharyngitis were analysed for the presence of F. necrophorum-specific DNA. The results were compared with those obtained from throat swabs collected from 100 healthy subjects. Ten clinical samples were positive for F. necrophorum DNA, identified as F. necrophorum subspecies funduliforme, using a haemagglutinin-related protein gene-specific PCR assay. All the healthy controls were negative (two-tailed P value = 0.0015; Fisher exact test). These findings suggest that F. necrophorum may play a more important role as a cause of simple sore throat in the community than has been previously appreciated.

Acute Disease↗
PubMed2004

Pilot scheme for performance assessment of HIV-1 genotypic resistance testing in the UK.

HIV-1 drug susceptibility testing by genotypic methods is now widespread in the UK and it is thus important to determine the reproducibility of such investigations. A pilot study was carried out to determine the reproducibility between laboratories of genotypic testing by nucleotide sequencing of patient samples, and to compare the interpretations of the results provided to the clinicians. Samples were distributed between the participating laboratories. Eight laboratories, using three different methods, sequenced four samples. Nucleotide sequence and reports were collated and compared by one laboratory. Where sequencing data were obtained > 99% concordance was observed for nucleotide designations. No discordances in nucleotide sequencing were found in positions associated with drug resistance. However, there were considerable differences between the laboratories in the interpretation of some of the mutations with respect to their effect on drug susceptibility. This study emphasises the variability in the available interpretation systems, and the importance of joint laboratory-clinical discussion in making decisions about treatment options.

Data Interpretation, Statistical↗
PubMed2001

The relative quiescence of hematopoietic stem cells in nonhuman primates.

Quiescence has been thought to be required for the retention of the full biological potential of pluripotent hematopoietic stem cells (PHSCs). This hypothesis has been challenged recently by the observation that all murine PHSCs cycle continuously and constantly contribute to steady-state blood cell production. It was asked whether these observations could be extrapolated to describe hematopoiesis in higher mammals. In this series of experiments, the replicative history of PHSCs was examined in baboons by continuously administering bromodeoxyuridine (BrdU) for more than 85 weeks. The results indicate that under steady-state conditions, PHSCs remain largely quiescent but do cycle, albeit at a far lower rate than previously reported for rodent PHSCs. BrdU-labeled cycling PHSCs and progenitor cells were shown to have an extensive proliferative capacity and to contribute to blood cell production for prolonged periods of time. The proportion of PHSCs entering cell cycle could, however, be rapidly increased by the in vivo administration of granulocyte-colony stimulating factor. These data indicate that during steady-state hematopoiesis, baboon PHSCs require prolonged periods of time to cycle and that the proportion of PHSCs in cycle is not fixed but can be altered by external stimuli. The relative quiescence of PHSCs observed in this nonhuman primate model, in contrast to murine PHSCs, might explain the current barriers to genetic modification and ex vivo expansion of human PHSCs.

Animals↗
PubMed2000

Application and validation of a urinary methadone metabolite (EDDP) immunoassay to monitor methadone compliance.

A total of 1381 urine specimens were screened using a Microgenics CEDIA urinary primary methadone metabolite (2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine; EDDP) immunoassay (cut-off calibrator concentration of 100 microg/L) in combination with a Dade Behring EMIT urinary methadone immunoassay (cut-off calibrator concentration of 300 microg/L). Of these, 642 (46%) were found to be positive using the EDDP assay but only 541 (39%) were found to be positive by the methadone assay. Out of the 108 specimens which were EDDP-positive but negative by the methadone assay, 47 (7%) could not be confirmed as positive using the routine in-house method of gas chromatography incorporating nitrogen-specific detection. Of these 47 results, 38 were re-screened using a more sensitive gas chromatography-mass spectrometry (GC-MS) technique, which demonstrated the presence of EDDP in every case. There was insufficient specimen to analyse the remaining nine samples. There were seven specimens which gave negative results by the EDDP and GC-MS assays but which had methadone concentrations ranging from 4000 to 37,500 microg/L. These were therefore presumed to be 'spiked' with methadone, i.e. to have had methadone added to the specimen to yield positive screening results and simulate compliance. It is concluded that the Microgenics CEDIA EDDP assay is a sensitive and reliable technique to determine the compliance of subjects prescribed methadone for opiate detoxification and maintenance.

Calibration↗
PubMed1999

Structural aspects of the effectiveness of bisphosphonates as competitive inhibitors of the plant vacuolar proton-pumping pyrophosphatase.

The bisphosphonates (general structure PO3-R-PO3) competitively inhibit soluble and membrane-bound inorganic pyrophosphatases (PPases) with differing degrees of specificity. Aminomethylenebisphosphonate (AMBP; HC(PO3)2NH2) is a potent, specific inhibitor of the PPase of higher plant vacuoles (V-PPase). To explore the possibility of constructing photoactivatable probes from bisphosphonates to label the active site of V-PPase we analysed the effects of different analogues on the hydrolytic and proton pumping activity of the enzyme. Bisphosphonates with a range of structures inhibited competitively and the effects on PPi hydrolysis correlated with the effects on proton pumping. Low-molecular-mass bisphosphonates containing hydrophilic groups (alpha-NH2 or OH) were the most effective, suggesting that the catalytic site is in a restricted polar pocket. Bisphosphonates containing a benzene ring were less active but the introduction of a nitrogen atom into the ring increased activity. Compounds of the general formula NH2(CH2)nC(PO3)2OH were more inhibitory than compounds of the H(CH2)nC(PO3)2NH2, NH2(CH2)nC(PO3)2NH2 or OH(CH2)nC(PO3)2NH2 series, with activity decreasing as n increased. A nitrogen atom in the carbon chain increased activity but activity was decreased by the presence of an oxygen atom. An analogue with a ring attached via a four-carbon chain, which included an amide linkage and a hydroxy group on the alpha-carbon atom, inhibited competitively (Ki=62.0 microM), suggesting that it may be possible to design bisphosphonate inhibitors which contain a photoactivatable azido group for photoaffinity labelling of V-PPase active site.

Binding Sites↗
PubMed1998

Effect of mutations of residue 340 in the large subunit polypeptide of Rubisco from Anacystis nidulans.

Residues 338-342 at the C-terminal end of loop 6 in the large subunit beta/alpha barrel structure of Rubisco influence specificity towards CO2 and O2. In Anacystis nidulans Rubisco, replacement of alanine 340 by tyrosine or histidine increased the specificity factor by 12-13%, accompanied by a 25-33% fall in Vc, the rate of carboxylation, while replacement by asparagine increased the specificity factor by 9% and Vc by 19%. Other mutations did not significantly alter specificity. Alanine 340 does not interact directly with the bisphosphate substrate, thus replacing it with other residues must have indirect effects on the specificity factor and rate of carboxylation.

Bacterial Proteins↗
PubMed1998

The development of a specimen exchange system for quality assessment of polymerase chain reaction tests.

A programme of external quality assessment of polymerase chain reaction (PCR) assays through regular exchange of appropriate clinical or spiked specimens between Oxford and Cambridge public health laboratories began in February 1997. We report on 60 specimens included in the exchange. These covered most of the molecular diagnostic assays in use at present. In two cases discrepant results were obtained. We conclude that the exchange of specimens under code between laboratories that use molecular techniques as a diagnostic service is an inexpensive way of achieving regular external quality assessment.

Humans↗
PubMed1993

Teaching the procedure of clean intermittent catheterisation.

The procedure of clean intermittent catheterisation (CIC) by 40 carers (23 males and 17 females) for spinal cord injury patients was evaluated (Assessment 1), and was subdivided into 40 steps with one point allotted for each step for evaluation purposes. Those who scored more than 32 out of 40 were excluded from the study. The carers who were enrolled in the study were taught the steps of CIC by personal teaching sessions. Assessment 2 was performed on the third day, and the steps which were unsatisfactory were explained to the carer, with positive feedback. Assessment 3 was carried out after 3 days. In Assessment 1, the mean score was 2, and after the first individualised teaching session, the score in Assessment 2 was 25 (p < 0.01); subsequent to the second teaching session, it further improved to 32 (p < 0.01) in Assessment 3. The relationship of carer to patient (son, daughter, wife, brother etc), age, and sex of the carer vs sex of the patient did not have any influence on the performance of CIC. However, the literacy status of the carer did have a bearing on the performance. The performance of graduates/postgraduates after a second teaching session was 37, whereas the performance of illiterate carers was only 27. The monthly income, habitat (rural vs urban) and occupation of the carers had a bearing on the performance; however, this was related to their literacy status. It is thus concluded that, with individualised teaching sessions and positive feedback, carers who are not literate (a situation frequently existing in developing nations) can be taught to perform satisfactorily the procedure of CIC.

Adolescent↗
PubMed1988

Two-dimensional electrophoresis of cereal prolamins: applications to biochemical and genetic analyses.

Three complementary two-dimensional systems for the analysis of cereal prolamins are described. These are electrophoresis at pH 3.1 followed by electrophoresis at pH 9.2, isoelectric focusing (IEF) followed by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and SDS-PAGE under non-reducing conditions followed by SDS-PAGE with reduction. They together give information on the pIs, Mrs and charge properties of the individual prolamin components, and on their interactions to form oligomers stabilized by inter-chain disulphide bonds. The three systems are then compared for their effectiveness in analysing unreduced prolamin I fractions from wheat and rye, and the IEF/SDS-PAGE system for analysing reduced and pyridylethylated prolamin fractions from all the major cereals. Finally, applications of the systems in biochemical and genetic studies are discussed and illustrated with three examples: analysis of the structural relationships of the S-rich prolamins (B hordeins and gamma-type hordeins) of barley, determination of the interactions of wheat and rye prolamin subunits in a 2RS/2BL translocation line, and the mapping of genes for alpha-type prolamins in the wild grass Haynaldia villosa.

Chromosome Mapping↗
PubMed1988

Routine burns bacteriology and proteus.

On standard agar media Proteus spp. swarm rendering prompt detection of other organisms difficult. Methods for preventing this have been investigated and a simple system devised suitable for inclusion in routine burns bacteriological investigations. Its merits are discussed.

Bacteriological Techniques↗
PubMed1987

Characterization and genetic control of the prolamins of Haynaldia villosa: relationship to cultivated species of the Triticeae (rye, wheat, and barley).

Haynaldia villosa is a wild grass of the tribe Triticeae, other members of which include the cultivated cereals barley, rye, and wheat. We have made an electrophoretic and chemical characterization of the major seed storage proteins (prolamins) of H. villosa and determined the chromosomal locations of the structural genes for some components using the available wheat/H. villosa chromosome addition lines. As in wheat, barley, and rye, groups of high molecular weight (polymeric), sulfur-poor (monomeric), and sulfur-rich (monomeric gamma-type and polymeric) prolamins can be recognized. Most of the components are encoded by genes on chromosome 1 Ha, which is homologous with the chromosomes controlling many of the prolamins in wheat and rye and all of those in barley. In addition, H. villosa also contains alpha-type sulfur-rich prolamins, previously detected only in wheat and its close relatives. These may be encoded by genes on chromosome 6Ha, which is homologous with the group 6 chromosomes that control the alpha-type gliadins of wheat. Despite the proposed close relationship between Haynaldia and ryes, no evidence was found for the presence of proteins closely related to the Mr 75,000 gamma-secalins which are characteristic of wild and cultivated species of Secale.

Chromosome Mapping↗