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Biomedical subjects

K Yusoff

Publications and source records attributed to K Yusoff.

51 records · Page 3Linked to original sources
PubMed1993

Conduction abnormalities in thyrotoxicosis--a report of three cases.

Cardiac arrhythmias are common in patients with thyrotoxicosis. Conduction abnormalities have been seen in a few thyrotoxic patients, but these, in particular high grade atrioventricular (AV) block, often occur in the presence of other conditions. Three thyrotoxic patients with conduction abnormalities are described: two were associated with severe hypokalaemia and the third had congestive cardiac failure. Conditions predisposing to conduction abnormality should be identified when this occurs in a thyrotoxic patient as their correction may help resolve or explain the conduction abnormality.

Adult↗
PubMed1993

Painful thyroiditis in postpartum period.

Destructive thyroiditis commonly occurs during the postpartum period, with a prevalence rate of 5% to 16%, and is mainly due to postpartum autoimmune thyroiditis (PPT) and, very rarely, to subacute thyroiditis. The thyroiditis is similar to Hashimoto's thyroiditis and is generally painless in nature, although cases with painful thyroiditis have been described. We report a case of painful destructive thyroiditis occurring during the postpartum period, which was clinically and biochemically indistinguishable from the variant of painful PPT or subacute thyroiditis. Fine needle aspiration cytology showed multi-nucleated giant cells diagnostic of subacute thyroiditis.

Adult↗
PubMed1992

Risk factor awareness and expectations of outpatients attending the Cardiology Clinic, Universiti Kebangsaan Malaysia.

One hundred consecutive patients attending the UKM (Universiti Kebangsaan Malaysia) Cardiology Clinic completed a questionnaire enquiring about their own assessment of their knowledge about their illness, their awareness of cardiac risk factors and their expectations in their management. Only 11% of our patients had graduated from tertiary education. 59% of our patients were being treated for ischaemic heart disease. Although only 28% of our patients considered having considerable knowledge of their illness, a majority of our patients were aware of cardiac risk factors. This was independent of the formal education achieved. However this awareness did not necessarily result in appropriate behaviour; 32% of patients admitted to smoking despite being aware of the harmful effects of smoking. 74% of our patients expected a cure from their doctors; only 37% of our patients thought they required medication indefinitely. Thus, patients could be made aware of their illness regardless of their formal educational status. However this may not necessarily result in appropriate behaviour. The high expectations which the patients have of their doctors is unrealistic and may be detrimental to appropriate long-term management of their chronic illness.

Adult↗
PubMed1989

Cloning and genetic analysis of tra cistrons of the Tra 2/Tra 3 region of plasmid RP1.

Transfer-defective mutants of the 10.4-kb Tra 2/Tra 3 region of RP1 were identified by their ability to be complemented by clones carrying all or part of this region. The respective mutations occurred in six cistrons whose order (traA, B, E, R, P, Q) and location were determined by deletion and insertion mapping. The cistrons occupy a minimum of 5.5 kb with the most distal, traA, spanning the 28.0-kb map position and traR the KpnI site at map position 24.1 kb. Each cistron is expressed independently, as Tn5 or Tn504 insertions in any one cistron do not affect the other five. The phenotypes controlled by each cistron suggest that all contribute to pilus biosynthesis/function while three (traB, R, and P) also contribute to surface exclusion. Given the occurrence of tra cistrons in the "silent" region between Tra 2 and Tra 3 we propose that the epithet "Tra 2" should be used to describe this entire region.

Chromosome Deletion↗
PubMed1989

Location of neutralizing epitopes on the fusion protein of Newcastle disease virus strain Beaudette C.

A panel of eight neutralizing monoclonal antibodies (MAbs) against the fusion (F) protein of Newcastle disease virus (NDV) has been shown to locate a major antigenic site on the basis of competitive binding assay and additivity index studies. Five epitopes (A1 to A5) have been located within this site on the F protein of the Beaudette C strain of NDV on the basis of cross-resistance plaque assays of MAb-resistant mutants raised against these MAbs. Epitopes A1, A4 and A5 are distinct; epitope A2 partially overlaps epitope A3. Nucleotide sequence analysis of the F genes of MAb-resistant mutants showed that each predicted single amino acid substitutions ranging from amino acid residues 157 to 171 for epitope A4 and at residues 72, 78, 79 and 343 for epitopes A1, A2, A3 and A5 respectively. These locations indicate that both the F1 and F2 fragments are involved in the formation of a single antigenic site and suggest the involvement of extensive protein folding in the active form of this F protein.

Amino Acid Sequence↗
PubMed1989

Effect of amino acid substitutions on glycosylation of the haemagglutinin-neuraminidase glycoprotein of Newcastle disease virus strain Beaudette C.

The nucleotide sequences of two monoclonal antibody-resistant mutant viruses predict changes from the wild-type in the number of potential glycosylation (Asn-X-Thr/Ser) in the mutant haemagglutinin-neuraminidase (HN) glycoproteins of the Beaudette C strain of Newcastle disease virus. The HN glycoproteins of these mutants, F5 and Z18, migrate either slower (F5) or faster (Z18) than that of the wild-type in SDS-PAGE. HN proteins synthesized in chick embryo fibroblasts following infection by either mutant or wild-type virus in the presence of tunicamycin (an inhibitor of glycosylation), comigrate on SDS-PAGE. These results confirm that the HN protein of the mutant virus, F5, has gained a glycosylation site at Asn(323)-Ser-Ser and that the conserved potential glycosylation site at Asn(481)-His-Thr is indeed glycosylated in the HN protein of the wild-type Beaudette C strain of Newcastle disease virus but is lost in that of the mutant virus, Z18.

Amino Acid Sequence↗
PubMed1988

Importance of lead selection in QT interval measurement.

The influence of lead selection on QT estimation in the 12-lead electrocardiogram was assessed in 63 patients (21 control subjects, 21 with anterior myocardial infarction, 21 with inferior myocardial infarction). QT estimates varied between leads. The variation was greater in patients with myocardial infarction than in control subjects (mean dispersion of QT: control subjects, 48 +/- 18 ms [+/- standard deviation]; anterior myocardial infarction, 70 +/- 30 ms; inferior myocardial infarction, 73 +/-32 ms). The maximum QT in any lead (QTmax) was determined and the deviation of each lead from this maximum value calculated. In all 3 groups, anteroseptal leads (V2 or V3) provided the closest approximation to QTmax. Interlead variability was found to be mainly due to variation in timing of the end of the T wave, rather than the onset of the QRS complex. The variability due to leads was considerably greater than the variability due to cycles, observers or measurement error. Implementation of a variety of current lead selection practices resulted in widely divergent estimates of QT interval. It is concluded that there is a need for standardization of lead selection practice for QT measurement. If measurements are confined to one or a few leads, anteroseptal leads provide the closest approximation to QTmax.

Electrocardiography↗
PubMed1988

Mapping of three antigenic sites on the haemagglutinin-neuraminidase protein of Newcastle disease virus.

Nine neutralizing monoclonal antibodies (MAbs), each of which react with the haemagglutinin-neuraminidase (HN) glycoprotein of the Beaudette C strain of Newcastle disease virus (NDV), have been used in competitive binding assays to delineate three non-overlapping antigenic sites A, B and C. Epitopes within these sites have been identified on the basis of cross-reactivity of MAb-resistant mutants against the panel of MAbs, determined by plaque assays and Western blotting. Site A contains three non-overlapping epitopes (A1, A2 and A3). A1 is the only linear epitope; all remaining epitopes are conformational. MAbs which react with epitopes A2 and A3 inhibit neuraminidase activity (NA) when assayed with neuraminlactose. Site B contains three partially overlapping epitopes (B1, B2 and B3) and site C is represented by a single epitope (C1). HN gene sequence analysis of MAb-resistant mutants showed that they each had only single amino acid substitutions which range from amino acid residues 347-460 for site A, 284-325 for site B, and at 481 for the C1 epitope. The apparent molecular mass of the HN glycoprotein of one mutant was increased from 72 to 75 kDa. This correlates well with the creation of an additional potential glycosylation site in this mutant from Asn-Ser-Pro(325) to Asn-Ser-Ser(325).

Amino Acid Sequence↗
PubMed1988

Location of a neutralizing epitope for the haemagglutinin-neuraminidase glycoprotein of Newcastle disease virus.

The binding site of a monoclonal antibody to the haemagglutinin-neuraminidase (HN) polypeptide of Newcastle disease virus (NDV) has been located. Complementary DNA or synthetic oligonucleotides corresponding to portions of the HN gene were cloned into the Escherichia coli vector pUC19 and fragments of the HN protein were thereby fused to the alpha-peptide of beta-galactosidase. Western blot analysis of E. coli lysates containing expressed fragments of the HN cDNA or synthetic oligonucleotides identified an antibody-binding peptide (Asp-Glu-Gln-Asp-Tyr-Gln-Ile-Arg; amino acid residues 346 to 353). Nucleotide sequence analysis of an antibody-resistant mutant of NDV revealed a Glu (wild-type) to Lys (mutant) substitution within the above sequence. The methods described could be useful for the location of continuous epitopes of other polypeptides.

Animals↗
PubMed1988

Hemodynamic consequences of supraventricular tachycardias and their antiarrhythmic treatment.

Complex adjustments in contractility, resistance, stroke volume and atrio-ventricular contraction relationships underlie the optimization of cardiac output during variations in sinus rate. In patients with intra AV nodal re-entry tachycardia and accessory pathway tachycardias, rate and loss of appropriately timed atrial transport reduce cardiac efficiency, but this is serious only when heart rates are very high. True atrial tachycardia, atrial fibrillation, and atrial flutter are often associated with cardiovascular disease. In atrial fibrillation and flutter, loss of atrial transport may be less important than the hemodynamic consequences of irregularity of ventricular systole. Antiarrhythmic management may ameliorate the consequences of the arrhythmia by reducing heart rate, restoring sinus rhythm or more controversially by regularizing ventricular contraction. Digoxin and antiarrhythmic surgery have little negative inotropic potential but most other antiarrhythmic drugs and ablation procedures depress myocardial function. Antitachycardia pacemakers may produce acute adverse hemodynamic effects depending upon the type of pulse trains delivered to terminate the tachycardia.

Anti-Arrhythmia Agents↗
PubMed1987

Nucleotide sequence analysis of the L gene of Newcastle disease virus: homologies with Sendai and vesicular stomatitis viruses.

The nucleotide sequence of the L gene of the Beaudette C strain of Newcastle disease virus (NDV) has been determined. The L gene is 6704 nucleotides long and encodes a protein of 2204 amino acids with a calculated molecular weight of 248822. Mung bean nuclease mapping of the 5' terminus of the L gene mRNA indicates that the transcription of the L gene is initiated 11 nucleotides upstream of the translational start site. Comparison with the amino acid sequences of the L genes of Sendai virus and vesicular stomatitis virus (VSV) suggests that there are several regions of homology between the sequences. These data provide further evidence for an evolutionary relationship between the Paramyxoviridae and the Rhabdoviridae. A non-coding sequence of 46 nucleotides downstream of the presumed polyadenylation site of the L gene may be part of a negative strand leader RNA.

Amino Acid Sequence↗
PubMed1984

Location of a function on RP1 that fertility inhibits Inc W plasmids.

Two fertility inhibition (Fi+) functions which reduce R388 (Inc W) transfer were detected on RP1 (Inc P). Neither function affected R388 -mediated surface exclusion but they could be distinguished by their effect on pilus production. One of the functions was located in the 6.5-kb Pst1 -C region of RP1, part or all of which also occurs on six Fi+ but not two Fi- Inc P plasmids studied.

Conjugation, Genetic↗