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Biomedical subjects

A Mehta

Publications and source records attributed to A Mehta.

At least 73 records · Page 4Linked to original sources
PubMed2001

Impact of PACS on the education of radiology residents: the residents' perspective.

RATIONALE AND OBJECTIVES: Because digital imaging and the picture archiving and communication system (PACS) are replacing radiographic film, the effect of PACS on residents' perceptions and their educational experience was investigated. MATERIALS AND METHODS: Residents taking part in large diagnostic radiology training programs at two hospitals were surveyed. Approximately 75% of radiographic studies were reviewed with the use of PACS at both hospitals. Survey topics included technical and didactic issues based on direct and indirect comparison with analog (conventional film) images. RESULTS: Fifty residents were polled (20 respondents). The majority has been using PACS for more than 1 year (14 of 20, 70%) to interpret 75%-100% of cases (11 of 20, 55%). The majority believed that PACS improved patient care (15 of 20, 75%) and their educational experience (15 of 20, 75%). A minority believed that increased patient throughput was harmful to the educational experience (five of 20, 25%) because it permitted attending radiologists to review cases too quickly (four of 20, 20%). Residents favored PACS over hard-copy images for ease of manipulation, resolution, and ability to see pathologic conditions and normal anatomic characteristics. CONCLUSION: Residents believe that PACS has positively affected their learning experience and does not negatively affect the quality of resident education.

Attitude of Health Personnel↗
PubMed2001

Combined administration of a chelating agent and an antioxidant in the prevention and treatment of acute lead intoxication in rats.

The administration of chelating agents, meso 2,3-dimercaptosuccinic acid (DMSA), monoisoamyl DMSA (MiADMSA) either individually or in combination with an antioxidant, n-acetylcysteine (NAC) in the prevention and treatment of acute lead intoxication in rats, was investigated. The results suggest that concomitant oral supplementation of DMSA with lead was most effective in preventing the inhibition of lead sensitive blood delta-aminolevulinic acid dehydratase (ALAD) activity in blood, elevation of zinc protoporphyrin level and the alterations in hepatic reduced and oxidized glutathione (GSH and GSSG) contents. A number of other biochemical variables either remained insensitive to lead exposure or responded moderately to chelation treatment. Combined administrations of NAC plus DMSA was most effective when given during lead exposure or post exposure, followed by DMSA and MiADMSA alone or NAC plus MiADMSA treatment, in reducing the accumulation of lead in blood and liver. Administration of NAC alone was only mildly effective in preventing lead absorption in the blood and tissues. The results suggest that combined administration of DMSA and NAC could be a more effective treatment protocol for acute lead toxicity, keeping in view its beneficial effect on oxidative injury.

Journal Article↗
PubMed2001

Assessment of the genetic diversity of Xylella fastidiosa isolated from citrus in Brazil by PCR-RFLP of the 16S rDNA and 16S-23S intergenic spacer and rep-PCR fingerprinting.

The genetic diversity among twenty three strains of Xylella fastidiosa, isolated from sweet orange citrus, was assessed by RFLP analysis of the 16S rDNA and 16S-23S intergenic spacer and by rep-PCR fingerprinting together with strains isolated from coffee, grapevine, plum and pear. The PCR products obtained by amplification of the 16S rDNA and 16S-23S spacer region were digested with restriction enzymes and a low level of polymorphism was detected. In rep-PCR fingerprinting, a relationship between the strains and their hosts was observed by using the BOX, ERIC and REP primers. Two major groups were obtained within the citrus cluster and relationships to the geographic origin of the strains revealed. Citrus strains isolated from the States of São Paulo and Sergipe formed one group and strains from the Southern States formed another group. Distinct origins of X. fastidiosa in the Southern and Southeastern States is postulated. The pear isolate was distantly related to all of the other X. fastidiosa strains.

Brazil↗
PubMed2001

Acute myeloblastic leukaemias of FAB types M6 and M4, with cryptic PML/RARalpha fusion gene formation, relapsing as acute promyelocytic leukaemia M3.

Demonstration of either the translocation t(15;17)(q22;q21) or the fusion of PML and RARalpha genes is regarded as diagnostic for acute myeloid leukaemia (AML) of FAB type M3, but has occasionally been seen in other FAB types. We present two such cases. Case 1 presented with FAB type M6 and a complex karyotype involving chromosomes 1, 2, 11 and 17. Bone marrow relapse of FAB type M3 followed autologous bone marrow transplantation. Subsequent marrow dysplasia and an M6 relapse were accompanied by a new cytogenetic clone involving chromosomes X, 2, 4, 6, 7 and 16. Fluorescence in situ hybridization (FISH) of metaphase chromosomes at diagnosis showed insertion of material from chromosome 17 into a 'normal' 15 with juxtaposition of PML and RARalpha. Case 2 presented as AML M4 and relapsed as M3. Cytogenetic analysis at diagnosis and in relapse showed 46,XY,t(15;17)(q22;q11),del(16)(q22). FISH analysis showed this to be a three-way translocation involving chromosomes 15, 16 and 17 again with juxtaposition of PML and RARalpha. Reverse transcription-polymerase chain reaction (RT-PCR) revealed PML/RARalpha fusion at diagnosis, in remission and in first relapse. These examples strengthen the case for RT-PCR screening of all AML patients for these fusion genes.

Adult↗
PubMed2001

Inhibition of hepatitis B virus DNA replication by imino sugars without the inhibition of the DNA polymerase: therapeutic implications.

Previously we have shown that the imino sugar inhibitor of N-linked glycan processing, N-nonyl-deoxynojirimycin (N-nonyl-DNJ), had antiviral activity in the woodchuck model of chronic hepatitis B virus (HBV) infection. In studying the mechanism of action of this compound, it was discovered that imino sugars could inhibit HBV secretion without inhibiting N-linked glycoprocessing. Although N-nonyl-DNJ is an inhibitor of the endoplasmic reticulum (ER) glucosidase, here it is shown that N-nonyl-DNJ retained antiviral activity at concentrations that had no significant impact on ER glucosidase function. Taken together, these results suggested that N-nonyl-DNJ possessed an antiviral activity attributable to a function other than an impact on glycoprocessing. This hypothesis was confirmed by experiments showing that N-nonyl-deoxygalactojirimycin (N-nonyl-DGJ), an alkyl derivative of galactose with no impact on glycoprocessing, retains anti-HBV activity. The data suggest that N-nonyl-DGJ exerts its antiviral action at a point before viral envelopment and may prevent the proper encapsidation of the HBV pregenomic RNA.

1-Deoxynojirimycin↗
PubMed2001

Phylogenetic relationships of Xylella fastidiosa strains from different hosts, based on 16S rDNA and 16S-23S intergenic spacer sequences.

The phylogenetic relationships of Xylella fastidiosa strains isolated from different hosts, including citrus trees, coffee, grapevine, plum and pear, were inferred by sequence analysis of the 16S rDNA and 16S-23S intergenic spacer region. A high level of similarity (97.1-100%) was found in the 16S rDNA of the Xylella fastidiosa strains. The 16S-23S region showed a higher level of variation, with similarity values ranging from 79.8 to 100%. Two tRNAs (tRNA(Ala) and tRNA(Ile)) were encountered within the spacer sequence. The phylogenetic trees, constructed using the neighbour-joining method, showed that the citrus, coffee, peach and plum strains were closely related and separate from grapevine strains. The pear strain remained isolated from all the other Xylella strains in both analyses and produced values of less than 20% in DNA-DNA hybridization experiments with a citrus strain. These results show that this strain does not belong to the Xylella fastidiosa genomic species.

DNA, Bacterial↗
PubMed2001

A proteomic approach for the discovery of early detection markers of hepatocellular carcinoma.

Individuals chronically infected with hepatitis B or C virus (HBV, HCV) are at high risk for the development of hepatocellular carcinoma (HCC), with disease progression occurring relentlessly over many years. The diagnosis of HCC usually occurs at late stages in the disease when there are few effective treatment options and the prognosis for patients with HCC is very poor. The long latency period, together with clearly identified at risk populations, provide opportunities for earlier detection that will allow more timely and effective treatment of this devastating cancer. We are using a proteomic approach to test the hypothesis that changes in the amount of certain serum polypeptides, or changes in their post-translational modifications, can be used to predict the onset of HCC. Advances in the standardization of two dimensional gel electrophoresis (2DE) coupled with computerized image analysis now permit the reproducible resolution of thousands of polypeptides per run. Serum polypeptides from individuals at different stages in the disease continuum are being resolved by 2DE to identify those that change with disease progression. Polypeptides found by this method can be further characterized by mass spectrometry. In addition, the potential for changes in the glycan structure of certain polypeptides to serve as a marker for disease progression can be explored. The proteomic approach is expected to liberate us from the need to "cherry pick" or guess the best biomarkers and let the data tell us which are the best indicators of disease. Information may also be gleaned about the pathobiology of the disease process.

Biomarkers↗
PubMed2001

A randomized, controlled study of a mandibular advancement splint for obstructive sleep apnea.

Although there is increasing interest in the use of oral appliances to treat obstructive sleep apnea (OSA), the evidence base for this is weak. Furthermore, the precise mechanisms of action are uncertain. We aimed to systematically investigate the efficacy of a novel mandibular advancement splint (MAS) in patients with OSA. The sample consisted of 28 patients with proven OSA. A randomized, controlled three-period (ABB/BAA) crossover study design was used. After an acclimatization period, patients underwent three polysomnographs with either a control oral plate, which did not advance the mandible (A), or MAS (B), 1 wk apart, in either the ABB or BAA sequence. Complete response (CR) was defined as a resolution of symptoms and a reduction in Apnea/Hypopnea Index (AHI) to < 5/h, and partial response (PR) as a > or = 50% reduction in AHI, but remaining > or = 5/h. Twenty-four patients (19 men, 5 women) completed the protocol. Subjective improvements with the MAS were reported by the majority of patients (96%). There were significant improvements in AHI (30 +/- 2/h versus 14 +/- 2/h, p < 0.0001), MinSa(O(2)) (87 +/- 1% versus 91 +/- 1%, p < 0.0001), and arousal index (41 +/- 2/h versus 27 +/- 2/h, p < 0.0001) with MAS, compared with the control. The control plate had no significant effect on AHI and MinSa(O(2)). CR (n = 9) or PR (n = 6) was achieved in 62.5% of patients. The MAS is an effective treatment in some patients with OSA, including those patients with moderate or severe OSA.

Adult↗
PubMed2001

Myosin learns to walk.

Recent experiments, drawing upon single-molecule, solution kinetic and structural techniques, have clarified our mechanistic understanding of class V myosins. The findings of the past two years can be summarized as follows: (1) Myosin V is a highly efficient processive motor, surpassing even conventional kinesin in the distance that individual molecules can traverse. (2) The kinetic scheme underlying ATP turnover resembles those of myosins I and II but with rate constants tuned to favor strong binding to actin. ADP release precedes dissociation from actin and is rate-limiting in the cycle. (3) Myosin V walks in strides averaging approximately 36 nm, the long pitch pseudo-repeat of the actin helix, each step coupled to a single ATP hydrolysis. Such a unitary displacement, the largest molecular step size measured to date, is required for a processive myosin motor to follow a linear trajectory along a helical actin track.

Actins↗
PubMed2001

Use of T cell epitopes for vaccine development.

T lymphocytes play a major role in the recognition and subsequent elimination of tumors and intracellular pathogens. Induction of epitope-specific T cell responses can help in the clearance of diseases for which no conventional vaccines exist. However, the lack of simple methods to identify relevant T cell epitopes, the high mutation rate of many pathogens, and HLA polymorphism have made the development of efficient T cell epitope-based, or "epitope-driven" vaccines difficult to achieve. Our research over the past several years has applied bioinformatics tools in conjunction with T cell assays to identify naturally processed putative T cell epitopes from several pathogens. This strategy will accelerate the development of new generation T cell epitope-based vaccines against various pathogens including viruses such as HIV and WNV, bacteria such as M.tb., and parasites such as plasmodium. This chapter will review the use of a bioinformatics-based approach to identify putative T cell epitopes. It will summarize the current state of knowledge regarding T cell-epitope-based vaccines and discuss several ways to improve their efficacy.

Algorithms↗
PubMed2001

Mitral valve replacement and repair. Report of 5 patients with systemic lupus erythematosus.

Severe mitral valve regurgitation due to systemic lupus erythematosus is a rare cause of valvular heart disease, necessitating valve surgery. Currently, there are 36 case reports in the world medical literature of mitral valve replacement or repair in patients who have lupus. The current trend in mitral valve surgery is toward anatomic valve repair. In patients who have systemic lupus erythematosus, however, valve repair often leads to repeat surgery and valve replacement. We report the cases of 5 patients with lupus and severe mitral valve regurgitation who underwent mitral valve surgery. In 3 of these patients, replacement with a mechanical prosthetic mitral valve was performed with good long-term results. In the other 2 patients, mitral valve repair was performed, but only 1 of the repairs was successful. The 2nd patient required subsequent replacement with a mechanical valve. To our knowledge, this report of 5 patients is the largest series of mitral valve surgery in patients with lupus. These results, along with a review of the literature, suggest the superiority of mechanical prosthetic valve replacement to repair in patients who have systemic lupus erythematosus.

Adult↗
PubMed2001

Trends in caesarean section rates at a maternity hospital in Mumbai, India.

The steady rise in caesarean section rates is an emerging area of concern in mother-child healthcare and a matter of international attention, since the trend is no longer confined to western industrialized countries. Crude and caesarean section-related perinatal mortality and case-fatality rates may well serve as public-health indicators. Monitoring time-trends in caesarean section rates has been considered a useful approach in the recognition of this rapidly-changing health policy and in estimating the magnitude of this problem. The study examined the observed time-trends in caesarean section rates in relation to perinatal mortality rates and maternal case-fatality rates in a hospital setting in Mumbai, India, using 1957-1998 data on retrospective cohort. Both overall rates and those specific to type of delivery were assessed. During 1957-1998, the caesarean section rates in the Nowrosjee Wadia Maternity Hospital (NWMH) increased from 1.9% to 16%, with the most significant rise over the past decade. The perinatal mortality rate showed a significant reduction from 69 per 1,000 in 1957 to 36 per 1,000 in 1992 and remained steady in the 1990s despite the higher caesarean section rates. The caesarean section rate in the NWMH rose by almost 10-fold during 1957-1998. No improvement in perinatal outcome was observed beyond a caesarean section rate of 10%, but the perinatal mortality rate in caesarean births increased significantly due to a more liberal use of caesarean sections in preterm deliveries and those that yielded low-birth-weight babies.

Cesarean Section↗