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Biomedical subjects

B Duggan

Publications and source records attributed to B Duggan.

At least 19 recordsLinked to original sources
PubMed2004

Pilonidal sinus of the penis.

A pilonidal sinus is a subcutaneous sinus containing hair. It is most commonly found in the natal cleft of hirsute men. Here we describe the unusual finding of a pilonidal sinus arising on the male foreskin.

Humans↗
PubMed1997

Contribution of increased length and intact capping sequences to the conformational preference for helix in a 31-residue peptide from the C terminus of myohemerythrin.

In order to examine the effects of chain length on the propensity of short peptides to form helix-like structures in aqueous solution, we have studied a peptide of 31 residues consisting of the C-terminal sequence (residues 88-118) of the four-helix bundle protein myohemerythrin from Themiste zostericola. This peptide, termed MDC, represents the final two elements of secondary structure in the protein, the D-helix and the C-terminal loop sequence, together with a five-residue sequence at the N terminus corresponding to the linker between the C- and D-helices. An N-capping sequence, VDAKNV, immediately precedes the D-helix sequence, and a C-capping sequence, VNHIKGT, corresponding to the alphaL termination motif, occurs at the C-terminal end. The effect of replacement of a cysteine residue in the middle of the sequence with an alanine was explored by the comparison of the MDC peptide and a 16-residue peptide representing the sequence of the D-helix alone, both containing the change Cys99Ala. Significant changes in the NMR and CD spectra were seen for both peptides compared to the wild-type sequence. A comparison of the fluorescence spectra of the wild-type and Cys99Ala peptides indicated that a specific interaction between the side chains of Cys 99 and Trp 102 acts to quench the fluorescence of the tryptophan ring and probably contributes a component that distorts the CD spectrum of the wild-type peptide at approximately 220-235 nm. The effect of an increase in the length of the peptide, with the incorporation of capping sequences derived from the native sequence, was explored by NMR and CD spectroscopy of the 31-residue and 16-residue peptides in aqueous solution and in TFE/water mixtures. Evidence for the formation of a significant population of helical conformers in the region of the MDC peptide corresponding to the D-helix was observed in aqueous solution using CD and NMR spectroscopy. The C-terminal 10 residues of the MDC peptide behave in solution in a manner identical to that of a 10-residue peptide with the same sequence; a highly specific local interaction between an aromatic ring and a glycine amide proton appears to be retained in the longer peptide. Upon addition of trifluoroethanol (TFE), significant shifts are observed in a number of resonances in the NMR spectrum, and both chemical shifts and NOEs provide evidence for a higher population of helix in the D-helix region of the peptide in TFE. However, TFE is unable to promote the propagation of helix beyond the N-cap or alphaL termination motifs, and the specific local interaction observed in the C-terminal sequence is retained in TFE. The CD spectrum in TFE shows an increase in the proportion of helix, to an overall maximum of approximately 55% helix at 50% v/v TFE, corresponding to approximately 100% helix in the D-helix sequence of the peptide, since the N and C termini of the MDC peptide are not helical according to the NMR spectra. The high proportion of helix observed in the D-helix sequence of the longer MDC peptide demonstrates that the presence of intact capping sequences can constrain the peptide conformational ensemble to resemble that seen in the native protein. A compendium of results from this and previous peptide studies has also led to a novel observation, the existence of a correlation between the amide proton chemical shift and temperature coefficient.

Amino Acid Sequence↗
PubMed1994

Modulation of gene expression by calreticulin binding to the glucocorticoid receptor.

Calreticulin is a multifunctional protein that acts as a major Ca(2+)-binding (storage) protein in the lumen of the endoplasmic reticulum. It is also found in the nucleus, suggesting that it may have a role in transcription regulation. Calreticulin has been reported to bind to the synthetic peptide KLGFFKR, which is almost identical to an amino-acid sequence in the DNA-binding domain of the superfamily of nuclear receptors. Could calreticulin interact with the DNA-binding domain of these receptors and affect their function? Here we report that the amino terminus of calreticulin interacts with the DNA-binding domain of the glucocorticoid receptor and prevents the receptor from binding to its specific glucocorticoid response element. Overexpression of calreticulin in mouse L fibroblasts inhibits glucocorticoid-response-mediated transcriptional activation of a glucocorticoid-sensitive reporter gene and of the endogenous, glucocorticoid-sensitive gene encoding cytochrome P450. Together these results indicate that calreticulin may be important in gene transcription, regulating the glucocorticoid receptor and perhaps other members of the super-family of nuclear receptors.

Amino Acid Sequence↗
PubMed1993

Cervical cancer in pregnancy: reporting on planned delay in therapy.

OBJECTIVE: To report our experience with invasive carcinoma of the cervix during pregnancy, assessing maternal morbidity due to treatment delay and reporting maternal and fetal outcome. METHODS: Twenty-seven patients with invasive cervical cancer, who were pregnant at the time of diagnosis or treatment, were identified from review of morbidity and mortality statistics between January 1, 1980 and December 31, 1991. All medical records were examined retrospectively. RESULTS: The incidence of cervical carcinoma in our population was 1.2 cases per 10,000 pregnancies. Most patients had stage I lesions. The predominant histologic cell type was squamous cell carcinoma, followed by adenosquamous carcinoma and adenocarcinoma. Eight patients with stage Ia or Ib cervical cancer postponed therapy to optimize fetal outcome, with a mean diagnosis-to-treatment interval of 144 days (range 53-212). Nineteen patients elected immediate treatment, with a mean diagnosis-to-treatment interval of 17 days (range 2-42). Fetal outcome was uniformly good for the delayed-treatment group. Nine fetal deaths and two neonatal deaths occurred in the immediate-treatment group. All patients who delayed therapy are free of disease after a median follow-up of 23 months. CONCLUSION: Deliberate delay of therapy to achieve fetal maturity appears to be a reasonable option for patients with stage I cervical cancer complicating pregnancy.

Adenocarcinoma↗
PubMed1989

Transcriptional regulation of two cytotoxic T lymphocyte-specific serine protease genes.

The expression of two serine proteases is induced by antigenic stimulation in cytotoxic T lymphocytes. Using nuclear run-on analysis the increase in steady state mRNA level has been shown to correspond to transcriptional activation. However, the two genes appear to be sequentially rather than coordinately induced. Both genes were shown to be more sensitive to DNase I digestion than a beta-globin gene in cytotoxic T cells. In addition, for the cytotoxic cell protease 1 gene the 5' region of the gene was more sensitive than the 3' end. Two DNaseI hypersensitive sites were seen in the 5' flanking sequences of both genes. The DNA sequences of the upstream regions of both genes were determined and compared. Although the two flanking sequences are overall quite dissimilar, there are short regions which are shared between the two CTL-protease genes. A number of these have been implicated in regulating the expression of other T cell genes.

Animals↗
PubMed1988

Organization of two genes encoding cytotoxic T lymphocyte-specific serine proteases CCPI and CCPII.

The genes encoding two recently described cytotoxic T cell proteases, CCPI and CCPII, have been isolated and sequenced. The organizations of the coding and noncoding portions of the two genes are very similar to each other and also to the gene encoding rat mast cell protease type II. Similarly to other serine protease genes, each of the active-site residues is contained on a separate exon; however, two introns were found in particularly interesting positions. One occurs within the postulated activation dipeptide and the other in a position close to the active-site Asp residue. This latter intron interrupts the amino acid sequence in the invariant core region of the protein. We believe that these genes represent a new subfamily of serine protease genes.

Amino Acid Sequence↗
PubMed1988

Isolation of two cDNA sequences which encode cytotoxic cell proteases.

Two cDNAs which cross-hybridized with cytotoxic cell protease genes were identified in a library generated from a cytotoxic T cell line. Sequence analysis revealed that the two new members of the family contained the three catalytic triad residues which characterize the active sites of serine proteases. A comparison of the protein sequences revealed not only a high degree of homology but also the conservation of some unusual structural features. These include the lack of a disulphide bond which spans the active site serine, the presence of a signal sequence and the inference of a dipeptide activation sequence.

Amino Acid Sequence↗
PubMed1980

Biochemical evidence for osteomalacia with carbamazepine therapy.

Many anticonvulsants are known to cause osteomalacia, however, carbamazepine has not previously been studied in this regard. We studied 31 patients on carbamazepine (mean dose 758 mg +/- s.d. 468 mg per day), as a single drug for epilepsy for a duration of 20.5 +/- 10 months. Three patients (10%) had hypocalcaemia, and serum calcium was significantly lower (P less than 0.01), and serum alkaline phosphatase significantly higher (P less than 0.05) than matched control subjects. Serum phosphorus was significantly inversely correlated and serum alkaline phosphatase was positively correlated with both dose and duration, but not blood levels of carbamazepine. These findings are consistent with mild biochemical changes of osteomalacia. None of the patients were symptomatic. Serum bilirubin (mean 2.6 +/- 1.4 mumol/l) was very significantly lower (P less than 0.01) than in controls. Both the calcium and bilirubin disturbances are probably due to carbamazepine causing hepatic microsomal enzyme induction.

Adolescent↗
PubMed1980

Phenobarbitone in previously untreated epilepsy.

In a prospective study we used phenobarbitone to treat 13 new patients with epilepsy (eight adults and five children). Full seizure control was achieved in 11 patients and poor compliance was documented in one of the remaining two patients (in both of whom seizures were reduced by over 50%). Doses sufficient to give mean steady state plasma levels of more than 43 mumol/l (10 microgram/ml) appeared to be associated with better seizure control than lower doses. No serious side effects were observed.

Adolescent↗