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Biomedical subjects

A Shaikh

Publications and source records attributed to A Shaikh.

At least 37 records · Page 2Linked to original sources
PubMed1995

The fimA locus of Streptococcus parasanguis encodes an ATP-binding membrane transport system.

The gene encoding fimA, a 36 kDa fimbrial adhesion of Streptococcus parasanguis FW213, is highly conserved in all four genetic groups of sanguis streptococci. FimA-like peptides were produced by all strains tested. The nucleotide sequence directly upstream of fimA contains two open reading frames, ORF5 and ORF1, whose deduced protein products are homologous to members of a superfamily of ATP-binding cassette membrane transport proteins, including both prokaryotic and eukaryotic uptake and export systems. The amino acid sequence of FimA contains the consensus prolipoprotein cleavage site (LxxC) common to the 'periplasmic' binding proteins of Gram-positive transport systems. The deduced product of ORF5 is a 28.6 kDa membrane-associated protein that has the consensus binding site for ATP (GxxGxGKS). It shares significant homology with AmiE of Streptococcus pneumoniae as well as with Escherichia coli proteins involved in iron(III) uptake. Allelic-replacement mutagenesis of ORF5 resulted in greatly increased resistance to aminopterin. These data demonstrate functionality with the amiE locus as well. The deduced product of ORF1 is an extremely hydrophobic integral membrane protein of 30.8 kDa with a pattern of six potential membrane-spanning regions, typical of a component of these types of transport system. The nucleotide sequence downstream of fimA, ORF3, encodes a 20 kDa protein having 78% identity with the 20 kDa protein encoded downstream of ssaB, a fimA homologue in S. sanguis 12. It also exhibits significant homology with bacterioferritin co-migratory protein (Bcp) of E. coli K-12. Allelic-replacement mutagenesis in the fimA locus of FW213 showed that (i) expression of fimA was initiated at a site far upstream of the fimA start codon, and (ii) expression of fimA was not linked to expression of ORF3. Northern blots probed with internal fragments of ORF5, ORF1, fimA or ORF3 hybridized to the same transcript of 3.3 kb, which suggested that these loci were transcribed as a polycistronic message. The ORF3 probe also hybridized to a 540 bp transcript consistent with the size of ORF3 alone and supportive of the mutagenesis data of non-linkage. Strains mutated in fimA continued to produce fimbriae, indicating that FimA was not the fimbrial structural subunit. Immunoelectron microscopy revealed FimA was localized at the tips of the fimbriae of FW213. This is the first study that demonstrates that an adhesin which binds a bacterial cell to a substrate is associated with an ATP-binding cassette.

ATP-Binding Cassette Transporters↗
PubMed1995

Effects of Ba2+ and Cs+ on apical membrane K+ conductance in toad retinal pigment epithelium.

Intracellular microelectrode techniques were employed to characterize the blocker sensitivity of the K+ conductance (gK) at the apical membrane of the toad retinal pigment epithelium (RPE). Increasing the K+ concentration in the apical bath ([K+]o) from 2 to 5 mM produced a rapid depolarization of the apical membrane potential (VA). The addition of 0.5 mM Ba2+ or 5 mM Cs+ to the apical bath rapidly depolarized VA and increased the transepithelial resistance and ratio of apical-to-basolateral membrane resistance. In the presence of apical Ba2+ or Cs+, the response of VA to delta [K+]o was markedly reduced, indicating that these ions are effective blockers of apical gK. The Ba(2+)- and Cs(+)-induced decreases in the apparent apical-to-basolateral membrane conductance ratio were concentration dependent, with apparent dissociation constants of 17 microM and 0.5 mM, respectively. The apparent blocker sensitivity of apical gK is similar to that previously demonstrated for the inwardly rectifying K+ conductance in isolated toad RPE cells, suggesting that the inwardly rectifying K+ conductance comprises much of apical gK.

Animals↗
PubMed1994

Management of congenital dacryocele.

Congenital dacryocele is a distension of the naso-lacrimal sac usually present at birth or in the first three months of life. It occurs commonly in females and may present with dacryocystitis. Treatment includes probing and antibiotics if infection is present.

Female↗
PubMed1993

Characterization of allelic replacement in Streptococcus parasanguis: transformation and homologous recombination in a 'nontransformable' streptococcus.

We have obtained transformants of Streptococcus parasanguis FW213 containing allelic replacements in several chromosomal loci. Transformation occurred following electroporation with nonreplicating plasmids carrying two antibiotic-resistance-encoding genes, one of which is inserted into DNA homologous to the chromosomal target. In contrast with other streptococci, S. parasanguis FW213 is not transformed by linear DNA. Mutations in nonreplicating plasmid DNA preferentially replaced their homologues in the S. parasanguis FW213 chromosome by a double-crossover homologous recombination event, as shown by the fact that over 90% of transformants were sensitive to the vector-coded antibiotic marker. Southern blot analysis of these transformants showed that three of the five target loci had been mutated, and that the wild-type sequence had been replaced by the mutated sequence carried on the transforming plasmid. This bias toward homologous replacement rather than integration of the entire transforming plasmid DNA simplifies site-specific mutagenesis and genetic analysis of the streptococcal chromosome.

Alleles↗
PubMed1993

Suppression of human IgE antibody forming cell responses by IL-6.

To study the effects of cytokines on human IgE antibody forming cells (AFCs), log phase U266 myeloma cells (3 x 10(3)/ml), which secrete immunoglobulin E (IgE), were cultured for 0-24 h with and without cytokine or with or without antibodies against various cytokines. The numbers of IgE AFCs were determined in ELISPOT assay. We found that interleukin-6 (IL-6) suppressed (to 95%) whereas anti-IL-6 increased (to 148%) the numbers of IgE AFCs and that both worked in a dose-dependent fashion. IL-4 and interferon-gamma (IFN-gamma) also suppressed IgE AFC responses in a dose-dependent fashion. However, antibodies to these cytokines had no effect. In contrast, IFN-alpha increased (to fourfold) the numbers of IgE AFCs in a dose-dependent fashion. The data are the first to show a suppressive effect of IL-6 on human IgE responses and may also suggest a role for IL-6 in the treatment of atopic disease.

Antibody-Producing Cells↗
PubMed1992

Percutaneous mitral valvotomy with the Inoue balloon catheter in children and adults: immediate results and early follow-up.

Percutaneous mitral balloon valvotomy (PMV) using the Inoue balloon catheter was attempted in 60 consecutive patients with severe symptomatic mitral stenosis. There were 10 children (mean age 13 years) and 50 adults (mean age 31 years). Forty patients were females and 20 were males; 53 were in sinus rhythm. The procedure was technically successfully performed in 57 (95%) patients. There were no deaths or thromboembolic complications. Balloon valvotomy was done using a 22 to 30 mm diameter catheter with the echo/Doppler guided stepwise mitral dilatation technique. After PMV the mean left atrial pressure decreased from 23.0 +/- 5.0 to 14.0 +/- 4.0 mm Hg (p less than 0.001). The mean mitral valve gradient (MVG) decreased from 15.0 +/- 4.0 to 6.0 +/- 2.0 mm Hg (p less than 0.001). The mitral valve area (Gorlin formula) increased from 0.7 +/- 0.2 to 1.6 +/- 0.4 cm2 (p less than 0.001). The mitral valve area as determined by echocardiography increased from 0.8 +/- 0.1 to 1.9 +/- 0.3 cm2 (p less than 0.001). Mild mitral regurgitation (MR) developed in six patients (11%) and increased by one grade in another five patients (9%). No patient developed severe mitral regurgitation. Mitral valve area at mean follow-up of 4.8 months remained unchanged at 1.9 +/- 0.3 cm2. We conclude that PMV, using the Inoue balloon catheter, is safe and effective in the treatment of severe mitral stenosis in children and adults, without inducing significant mitral regurgitation.

Adolescent↗
PubMed1992

Balloon coarctation angioplasty in adolescents and adults: early and intermediate results.

Twenty-three adolescent and adult patients with native coarctation of the aorta underwent balloon dilatation. Dissection of the aorta developed in one patient. Data were collected on the remaining 22 patients. They ranged in age from 15 to 55 years (mean 23 +/- 9.2 years). Invasive measurement of the peak systolic gradient (PSG) and biplane angiography were performed before and immediately after angioplasty and at follow-up 4 to 48 months (mean 15 months) later. PSG before dilatation was 37 to 100 mm Hg (mean 66.9 +/- 19.9 mm Hg) and decreased to 0 to 30 mm Hg (mean 9.1 +/- 11 mm Hg) immediately after dilatation (p less than 0.001). Restenosis occurred in two patients 6 months after dilatation, and one patient had an incomplete dilatation. These three patients underwent successful redilatation and remained improved 12 to 19 months later. There was no significant change in gradient at repeat catheterization in the remaining 20 patients. PSG was 0 to 20 mm Hg (mean 5.8 +/- 7.2 mm Hg). Angiography showed that a small aneurysm developed in one patient immediately after dilatation and in another 6 months later. Eleven patients were restudied more than once, and no change in gradient or size of the aneurysm was noted at mean follow-up 25 months after dilatation. This study demonstrated that balloon angioplasty is an effective method of treating adolescent and adult patient with native coarctation of the aorta. However, because of the uncertain natural history of aneurysm after dilatation, this procedure should be considered investigational until much longer follow-up times are available.

Adolescent↗
PubMed1991

Decrease in pulmonary artery pressure with slow release nifedipine in Saudi patients with primary pulmonary hypertension.

We studied the acute and short-term hemodynamic effects of vasodilators in three Saudi patients with primary pulmonary hypertension. The study protocol included the measurement of pulmonary artery pressure, resistance and cardiac output at baseline and at 15, 30, 45 and 60 minutes after 10 mg sublingual nifedipine. These hemodynamic studies repeated at 3 and 6 months follow-up. A 24 hour profile of pulmonary artery and aortic pressures were recorded to evaluate the effect of 20 mg of slow release nifedipine, after 25 mg of captopril and 5 mg of sublingual isordil. After nifedipine there was a marked reduction in systolic pulmonary artery pressure from 85 +/- 18 to 55 +/- 8 mmHg and the pulmonary resistance decreased from 1422 +/- 367 to 954 +/- 69 dynes-sec/cm-5. The cardiac output increased from 2.9 +/- 0.2 to 0.2 to 4.0 +/- 0.4 l/min after nifedipine. The patients were discharged on nifedipine 10 mg qid, except for patient #3 who was a non-responder. At follow-up there was a symptomatic improvement and a favourable hemodynamic response was maintained, though patient #2 required a higher dose of nifedipine. The pulmonary artery 24 hour pressure profile revealed that 20 mg slow release adalat reduced pulmonary artery pressure for a 6 hour period. Whereas, regular nifedipine decreased pulmonary artery pressure for a period of less than 90 minutes. There was no favourable hemodynamic response to either captopril 25 mg oral of isordil 5 mg administered sublingually. We conclude that slow release nifedipine decreases the pulmonary artery pressure for longer periods compared to regular nifedipine in patients with primary pulmonary hypertension.

Adolescent↗
PubMed1991

Mitral balloon valvotomy using the Inoue balloon technique for selected patients with severe pliable rheumatic mitral valve stenosis: immediate and short-term results.

We selected 40 patients with severe symptomatic rheumatic mitral stenosis for balloon valvotomy using the Inoue balloon technique. The patients' mean age was 31 +/- 14 years and there were 24 females and 16 males. The patients were selected according to the following echo/Doppler criteria; 1. Severe mitral stenosis, i. e. mitral valve area (MVA) less than 1.1 cm2; 2. pliable anterior mitral valve leaflet; 3. absence of calcification of the mitral commissures and 4. absence of significant subvalvular mitral valve disease (Block echo score less than 8). We failed to cross the mitral valve in three cases and repeat attempts in two patients with higher transeptal puncture was successful. Thirty-nine procedures were technically successful (98%). There were no complications. We used an Inoue balloon size 24-30 mm using echo/Doppler guided stepwise mitral dilatation. After mitral balloon valvotomy, the MVA increased from 0.8 +/- 0.2 to 1.7 +/- 0.5 cm2 (p less than 0.001). Five patients developed mild mitral regurgitation and in one patient the degree of mitral regurgitation increased from mild to moderate. The mean mitral valve area 48 hours after the procedure measured 1.9 +/- 0.4 cm2 (echo/Doppler); one patient (2.5%) had residual mitral stenosis (MVA less than 1.5 cm2). At six weeks follow-up study the mean mitral valve area was 1.9 +/- 0.5 cm2 (Echo/Doppler), with no restenosis. We conclude that in selected cases of severe pliable mitral stenosis, the Inoue balloon technique achieves a greater than 100% increase of the MVA, without inducing significant iatrogenic mitral regurgitation or residual stenosis.

Catheterization↗
PubMed1990

Regression of infundibular pulmonary stenosis after successful balloon pulmonary valvuloplasty in adults.

Between July 1985 and March 1988, 22 adult patients with congenital pulmonary stenosis underwent balloon pulmonary valvuloplasty. There were 10 males and 12 females aged 16-45 (average 25 +/- 9.9) years. All patients had additional mild to severe infundibular stenosis; 16 were restudied 6-36 (mean 12.6) months later by repeat catheterization. Student's t-test was used for comparison of data. Right ventricular (RV) systolic pressure before dilatation was 84-196 (mean 129 +/- 32.3) mm Hg, and the peak pulmonary gradient (PPG) was 60-176 (mean 111 +/- 33.2) mm Hg immediately after dilatation. The RV systolic pressure dropped to 32-140 (mean 59.2 +/- 27) (P less than 0.001); and PPG dropped to 10-113 (mean 37.8 +/- 26.4) (P less than 0.001), and the infundibular gradient ranged from 8 to 113 (mean 35.1 +/- 25.8) mm Hg. The infundibular diameter, before dilatation, ranged from 2 to 15 (mean 9.5 +/- 4) mm Hg. At repeat catheterization, the RV systolic pressure dropped further to 33-66 (mean 42.8 +/- 9.7) mm Hg and the PPG was reduced to 0-48 (mean 18.4 +/- 10.9) mm Hg (P less than 0.001). The infundibular gradient regressed to 0-34 (mean 15 +/- 8.8) mm Hg (P less than 0.001). The infundibular diameter increased to 8-25 (mean 15.8 +/- 5.4) (P less than 0.001). It is concluded that moderate to severe infundibular stenosis, in adults, can regress after successful pulmonary valvuloplasty.

Adult↗
PubMed1990

The ideal tissue adhesive in facial plastic and reconstructive surgery.

In this paper we have reviewed cutaneous wound closure in facial plastic and reconstructive surgery using two different tissue adhesives: (1) Fibrin glue (Tisseel), and (2) N-butyl-2-Cyanoacrylate (Histoacryl Blue). Fibrin glue was used on 23 patients: eight lower blepharoplasties, eight hemi-facelifts, five mid browlifts and seven facial reconstructive procedures. Histoacryl glue was used in 108 blepharoplasty incisions, 30 facelift incisions, 21 submental incisions for liposuction, and 19 local flaps for facial reconstructive procedures. Comparison was made of the adequacy of bonding, cosmetic result of the incision, ease of use and cost. The results of our experience with tissue adhesives indicate the use of fibrin glue mainly on the undersurface of flaps. We think histoacryl glue is the ideal tissue adhesive for surface cutaneous wound closure in regards to safety, reliability, tensile strength and cost effectiveness.

Enbucrilate↗
PubMed1990

Benign migratory stomatitis: a literature review and case report.

Although benign migratory stomatitis (BMS) was first reported in the literature as early as 1955 (Cooke), fewer than 40 cases have been recorded. This article reviews the literature and describes a case of BMS involving the ventral surface of the tongue of a 74-year-old male. This is the first South African case to be reported.

Aged↗
PubMed1988

Increased mitral valve insufficiency during precordial "whoop".

A patient with rheumatic mitral valve stenosis and regurgitation presented with shortness of breath and a "noise" in her chest. Cardiac auscultation revealed an intermittent late systolic "whoop." An increase in severity of mitral valve insufficiency during the periods of "whoop" was observed by pulsed Doppler, hemodynamic tracings and left ventriculography.

Aged↗