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Biomedical subjects

M Rajagopalan

Publications and source records attributed to M Rajagopalan.

At least 19 recordsLinked to original sources
PubMed2001

The Mycobacterium avium-intracellulare complex dnaB locus and protein intein splicing.

Intein is a protein sequence mebedded in-frame within a precursor protein and is posttranslationally excised by a self-catalytic protein splicing process. Protein splicing is believed to follow a pathway requiring Cys, Ser, or Thr residues at the intein N-terminus and substitutions other than Cys, Ser, or Thr residues prevent splicing. We show that the dnaB locus in some strains of M. avium-intracellulare complex (MAC) contains intein and that the intein N-terminal amino acid is Ala [Ala-type]. We demonstrate that the M. avium DnaB precursor protein undergoes posttranslational proteolytic processing producing proteins corresponding to the sizes of the DnaB and intein. Further, by Western analysis we detect a protein corresponding to the size of the spliced DnaB protein in MAC cell extracts. Together, these results indicate that the Ala-type MAC DnaB inteins can splice and provide another example that points to an interesting alternative splicing mechanism (Southworth, M. W., Benner, J., and Perler, F. B., EMBO J. 19, 5019-5026, 2000).

Bacterial Proteins↗
PubMed2000

Development of simple and efficient protocol for isolation of plasmids from mycobacteria using zirconia beads.

A two-step protocol has been developed for isolation of plasmids from recombinant mycobacteria via Escherichia coli. First either mycobacterial primary transformants or propagated cultures were lysed in a mini-bead beater using zirconia beads and the lysate thus obtained was used to transform E. coli recA mutant cells. Secondly, plasmid DNA was isolated from recombinant E. coli cells and analysed. Bead beating times of 2 min for Mycobacterium smegmatis, a rapid grower, and 4 min for M. bovis BCG, a slow grower, were found to be optimal for recovery of plasmid DNA. This protocol was also amenable to other mycobacterial species such as M. avium, M. fortuitum and M. tuberculosis H37Ra. Plasmid recovery from the recombinant M. bovis BCG using this protocol is approximately 300-fold higher than that reported for the electroduction method.

Blotting, Southern↗
PubMed1999

Characterization of the functional replication origin of Mycobacterium tuberculosis.

The gene order in the 5kb Mycobacterium tuberculosis dnaA region is rnpA, rpmH, dnaA, dnaN and recF. We show that M. tuberculosis DNA fragment containing the dnaA-dnaN intergenic region functioned as oriC, i.e., allowed autonomous replication to otherwise nonreplicative plasmids, in M. tuberculosis H37Ra (H37Ra), avirulent strain of M. tuberculosis, and in Mycobacterium bovis BCG (BCG), a closely related, slowly growing mycobacterial strain. Removal of Escherichia coli plasmid replication origin (ColE1) from the M. tuberculosis oriC plasmids did not abolish their ability to function as oriC, confirming that the autonomous replication activity of these plasmids is due to the presence of the DNA fragment containing the dnaA-dnaN intergenic region. Deletion analyses revealed that the minimal oriC DNA fragment is 814bp. The copy number of M. tuberculosis oriC plasmids containing ColE1 ori relative to chromosomal oriC is one and the 5' flanking region of minimal oriC contains features that support stable autonomous replication. The M. tuberculosis oriC did not function in rapidly growing mycobacterial species such as M. smegmatis. M. smegmatis oriC functioned only in M. fortuitum, but not in any of the slowly growing mycobacterial species such as M. tuberculosis and BCG. Together these data suggest that the replication initiation mechanisms in the slowly growing Mycobacteria are similar and probably different from those in the rapidly growing Mycobacteria and vice versa.

Bacterial Proteins↗
PubMed1999

Discontinuation symptoms with nefazodone.

OBJECTIVE: We report a patient who developed discontinuation symptoms following nefazodone cessation. CLINICAL PICTURE: The patient experienced nausea, vomiting, diarrhoea, ataxia, insomnia, marked agitation, headache and flu-like symptoms. TREATMENT: She was reluctant to recommence nefazodone and was symptomatically treated with oxazepam. OUTCOME: The patient recovered completely in 10 days. CONCLUSIONS: Nefazodone discontinuation can result in withdrawal symptoms and therefore needs to be tapered gradually. Those who have experienced discontinuation symptoms with other antidepressants in the past may be at increased risk.

Adult↗
PubMed1999

The dnaA gene region of Mycobacterium avium and the autonomous replication activities of its 5' and 3' flanking regions.

A 3.9 kb DNA fragment containing the dnaA gene region of Mycobacterium avium was cloned and its nucleotide sequence was determined. Nucleotide sequence analyses indicated that this region encodes three genes in the order rpmH (ribosomal protein L34), dnaA (the putative initiator protein) and dnaN (the beta subunit of DNA polymerase III). The intergenic regions between the rpmH-dnaA and dnaA-dnaN genes were found to contain several putative DnaA boxes, 9 nt long DnaA protein recognition sequences. A DNA fragment containing the 3' but not the 5' flanking region of the M. avium dnaA gene when cloned in Escherichia coli plasmids, which are otherwise non-replicative in mycobacteria, exhibited autonomous replication activity in M. avium but not in Mycobacterium bovis BCG and Mycobacterium smegmatis. The 5' flanking region of dnaA, on the other hand, exhibited autonomous replication activity in M. bovis BCG but not in M. avium and M. smegmatis. The implications of these results for the understanding of the M. avium oriC replication initiation process are discussed.

3' Untranslated Regions↗
PubMed1998

The escape.

Explore the source record for details and available documents.

Adult↗
PubMed1998

XYY chromosome anomaly and schizophrenia.

Sex chromosome anomalies have been associated with psychoses, and most of the evidence is linked to the presence of an additional X chromosome. We report a patient with XYY chromosome anomaly who developed schizophrenia.

Adolescent↗
PubMed1998

Symptom relief with amitriptyline in the irritable bowel syndrome.

Anti-depressants have been reported to be useful in the management of the Irritable Bowel syndrome. We studied the efficacy of amitriptyline for 12 weeks in a randomized double-blind placebo-controlled trial. Forty patients who met predefined criteria entered the trial. They received 25 mg amitriptyline for the first week, 50 mg for the second week and 75 mg nightly thereafter until the end of the 12th week. The drug and placebo groups were comparable in all major pretreatment variables. Amitriptyline was found to be significantly more effective than placebo in producing global improvement, increasing feelings of well-being, reducing abdominal pain and increasing satisfaction with bowel movements. Younger age and increasing extroversion predicted a better response to amitriptyline. Severity of depressive and anxiety symptoms and other personality variables did not influence outcome.

Adult↗
PubMed1998

Mental health professionals' attire.

OBJECTIVE: Our aim was to obtain mental health patients' views on psychiatrists' and case managers' attire. METHODS: Eighty-six patients treated at a community mental health service were surveyed. Various types of commonly worn attire were listed. Respondents were asked to choose what they thought was most appropriate for their psychiatrist and case manager to wear. RESULTS: Over 50% of respondents felt that psychiatrist or case manager dress was not an important issue. However, those who felt that it was preferred less formal attire. CONCLUSIONS: Psychiatrists and case managers in a community mental health team could consider adopting less formal attire. This conclusion is limited by the small sample and may be relevant to rural areas only. Further research is needed in urban centres. Implications of these findings are discussed.

Adult↗
PubMed1997

Characterization of the oriC region of Mycobacterium smegmatis.

A 3.5-kb DNA fragment containing the dnaA region of Mycobacterium smegmatis has been hypothesized to be the chromosomal origin of replication or oriC (M. Rajagopalan et al., J. Bacteriol. 177:6527-6535, 1995). This region included the rpmH gene, the dnaA gene, and a major portion of the dnaN gene as well as the rpmH-dnaA and dnaA-dnaN intergenic regions. Deletion analyses of this region revealed that a 531-bp DNA fragment from the dnaA-dnaN intergenic region was sufficient to exhibit oriC activity, while a 495-bp fragment from the same region failed to exhibit oriC activity. The oriC activities of plasmids containing the 531-bp sequence was less than the activities of those containing the entire dnaA region, suggesting that the regions flanking the 531-bp sequence stimulated oriC activity. The 531-bp region contained several putative nine-nucleotide DnaA-protein recognition sequences [TT(G/C)TCCACA] and a single 11-nucleotide AT-rich cluster. Replacement of adenine with guanine at position 9 in five of the putative DnaA boxes decreased oriC activity. Mutations at other positions in two of the DnaA boxes also decreased oriC activity. Deletion of the 11-nucleotide AT-rich cluster completely abolished oriC activity. These data indicate that the designated DnaA boxes and the AT-rich cluster of the M. smegmatis dnaA-dnaN intergenic region are essential for oriC activity. We suggest that M. smegmatis oriC replication could involve interactions of the DnaA protein with the putative DnaA boxes as well as with the AT-rich cluster.

Bacterial Proteins↗
PubMed1997

Randomly amplified polymorphic DNA PCR for comparison of Mycobacterium abscessus strains from nosocomial outbreaks.

Mycobacterium abscessus is an important cause of water-related nosocomial outbreaks or pseudo-outbreaks. Strain comparison has relied on pulsed-field gel electrophoresis (PFGE). Unfortunately, almost 50% of strains cannot be assessed by this method. We studied 118 strains of M. abscessus previously studied by PFGE by randomly amplified polymorphic DNA (RAPD) PCR, including isolates from eight nosocomial outbreaks. Ten random primers were evaluated by using DNA prepared by boiling or phenol-chloroform extraction. Both DNA preparations gave the same grouping of isolates for three outbreaks compared to the groupings obtained by PFGE. Five outbreaks due to M. abscessus which gave broken DNA by PFGE gave evaluable patterns when studied by RAPD-PCR, with isolate clustering being consistent with that from other laboratory and epidemiologic data. The patterns were highly method dependent, strain comparison required the use of multiple primers, and the method worked best with purified DNA and by using strains for comparison on the same gel. We propose categories of indistinguishable, different, and inconclusive when comparing strains by RAPD-PCR. This study demonstrates that RAPD-PCR can be used for genetic comparison of M. abscessus strains, including strains which cannot be compared by PFGE, but the potential for misinterpretation is greater than that by PFGE.

Base Sequence↗