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Biomedical subjects

K Ahmed

Publications and source records attributed to K Ahmed.

At least 73 records · Page 4Linked to original sources
PubMed1997

Serotypes of Streptococcus pneumoniae causing invasive childhood infections in Bangladesh, 1992 to 1995.

One hundred sixty-five invasive Streptococcus pneumoniae strains were isolated from children under five at Dhaka Shishu (Children's) Hospital during the period 1992 to 1995. Ninety-four strains were from cerebrospinal fluid, and 71 were from blood. More than 91% of the strains were isolated from patients aged 24 months or less. Predominant serotypes were, in descending order 7F, 12F, 14, 15B, 18, 5, and 22A. These comprised 70% of all isolates. The marked differences in serotype distribution in different countries indicate the need for a sentinel surveillance study for the countries of South Asia, particularly Bangladesh, China, India, and Pakistan.

Bacterial Vaccines↗
PubMed1997

Effects of isradipine on renal hemodynamics in renal transplant patients treated with cyclosporine.

Cyclosporine A is the mainstay of modern immunosuppressant therapy in human organ transplants. However, its use has been associated with nephrotoxicity and hypertension that may be hemodynamically mediated. This study was undertaken to see if the calcium channel blocker, isradipine, could improve renal hemodynamics by decreasing renal vascular resistance and to determine its effects on cyclosporine pharmacokinetics. Eighteen hypertensive renal transplant recipients (3 to 60 months post transplant) were enrolled. Antihypertensive medications were stopped. Patients were placed on isradipine and followed for 8 weeks. Blood pressure, creatinine clearance, cyclosporine trough levels, and renal plasma flow using p-aminohippurate clearance, were measured pre- and at 8 weeks of therapy. Only one patient did not complete renal plasma flow measurement. Systolic and diastolic blood pressures dropped significantly (p < 0.001) from baseline to 8 weeks with isradipine. Sbp decreased from 166 +/- 18 to 142 +/- 14 mmHg and Dbp decreased from 97 +/- 8 to 82 +/- 10 mmHg (mean +/- 1 SD). Renal vascular resistance, calculated from mean arterial pressure and renal blood flow, decreased significantly (p < 0.002) from 0.57 +/- 0.21 to 0.41 +/- 0.12 mmHg/ml/min (mean +/- 1 SD). Isradipine appeared to have no significant effect on cyclosporine trough levels, creatinine clearance, or renal plasma flow. This study shows a role for isradipine use in renal transplant recipients on cyclosporine. Renal vasoconstriction caused by cyclosporine may be partially prevented with isradipine therapy. Furthermore, isradipine is effective in the treatment of hypertension in renal transplant recipients without affecting cyclosporine levels.

Adolescent↗
PubMed1996

Evidence that casein kinase 2 phosphorylates hepatic microsomal calcium-binding proteins 1 and 2 but not 3.

We have extensively purified three of the hepatic microsomal intralumenal Ca2+-binding proteins, CBP1, CBP2, and CBP3, which were originally described by Van et al. [(1989) J. Biol. Chem. 264, 17494-17501]. These apparently homogeneous preparations showed only single 45Ca2+ binding bands. On the basis of the peptide sequence, CBP2 was found to be highly homologous with the previously described protein ERp72. Similarly, CBP3 was identical to calreticulin and CBP1 had some homology to calmodulin. Contrary to the report of Van et al. (1989), we found that CBP2 had little thiol:protein disulfide oxidoreductase activity. Of the three purified preparations, only CBP2 exhibited apparent intrinsic protein kinase activity. This activity was found to be due to contamination of the CBP2 preparation by an extremely low concentration of tightly bound casein kinase 2 (CK2). In line with this observation, the phosphorylation was inhibited by heparin, removed by antibody to CK2, and stimulated by spermine. Furthermore, CBP2 was readily phosphorylated in vitro by added CK2 but only slowly phosphorylated by several other protein kinases. Thus, the persistence of CK2 in a highly purified preparation of CBP2 along with several other lines of evidence presented in this study might suggest that the protein CBP2 is a physiologically relevant substrate for CK2. Furthermore, these data suggest that CK2 might be localized in the lumen of the endoplasmic reticulum and that the phosphorylation of CBP2 in the lumen may play a role in the chaperone activity attributed to this protein.

Amino Acid Sequence↗
PubMed1996

Interference in protein assays of biological specimens by vanadyl compounds.

Vanadyl ribonucleoside and orthovanadate are commonly employed as inhibitors of ribonuclease and protein phosphatase activities, respectively, in a variety of tissue preparations. We have observed that the presence of these agents in the tissue samples interferes in the measurement of their protein content using the Coomassie dye binding procedure. We have demonstrated that this interference in the protein assay can be overcome by including H2O2 at a final concentration of 0.1% in the protein assay medium prior to the addition of the dye reagent. This results in accurate measurements of the protein content in the tissue preparation containing vanadyl ribonucleoside or orthovanadate.

Animals↗
PubMed1996

Elevated protein kinase CK2 activity in chromatin of head and neck tumors: association with malignant transformation.

We hypothesized that malignant transformation of normal mucosa of the upper aerodigestive tract to squamous cell carcinoma of the head and neck (SCCHN) might be associated with altered CK2 activity in the chromatin compartment of these tumors. We measured CK2 activity in the cytosol and chromatin of 7 surgical specimens of SCCHN, and 5 specimens of normal oropharyngeal mucosa from non-smokers/non-drinkers. CK2 activity in SCCHN tumors was significantly elevated in both the nuclear chromatin (P < 0.0005) and cytosolic (P <0.04) compartments relative to normal mucosa. These data suggest that activation of dysregulation of the chromatin-associated CK2 signal may play a role in the pathobiology od SCCHN.

Amino Acid Sequence↗
PubMed1996

Attachment of Moraxella catarrhalis to pharyngeal epithelial cells is mediated by a glycosphingolipid receptor.

Moraxella catarrhalis is one of the major pathogens of respiratory infections and has the ability to attach to the pharyngeal cells iva fimbriae. We characterized the epithelial cell receptor to which fimbriate M. catarrhalis binds. Neuraminidase pretreatment of pharyngeal epithelial cells resulted in a significant decrease of M. catarrhalis attachment, suggesting interaction with the sialic acid component. The attachment was not decreased in M. catarrhalis pretreated with 2 and 1 mg/ml of fucose, N-acetyl-neuraminic acid, N-acetyl-glucosamine, N-acetyl-galactosamine, acetyl-salicylic acid and colominic acid. However, M. catarrhalis treated with gangliosides M1, M2, D1a, D1b and T1a at a concentration of 2.5 micrograms/ml had significantly decreased the attachment compared to the control. In contrast treatment with gangliosides M3 and asialoganglioside M1 did not decrease the attachment of M. catarrhalis and thereby provided evidence for specificity of the inhibition. Concentration dependent effects of ganglioside M2 on the attachment were also observed. Other fimbriate isolates of M. catarrhalis showed decrease in attachment after treatment with ganglioside M2. However there was no effect on attachment when a nonfimbriate isolate was treated with ganglioside M2. This study indicates that the receptor of fimbriate M. catarrhalis on pharyngeal epithelial cells resides in the sequences of ganglioside M2.

Bacterial Adhesion↗
PubMed1996

Nuclear matrix as an anchor for protein kinase CK2 nuclear signalling.

Nuclear matrix (NM) is not only the structural basis for nuclear shape but also is intimately involved in nuclear functional activities. Among the modulatory factors that may affect these diverse activities are the signals that may influence the state or composition of the NM proteins. One such mechanism for altering the functional activity of at least some NM proteins may be the extent of their phosphorylation. Protein kinase CK2 appears to associate with NM and to phosphorylate a number of NM-associated proteins. Chromatin- and NM-associated CK2 is rapidly modulated by mitogenic signals. We propose that NM serves as a physiological anchor for nuclear signalling of protein kinase CK2 which may influence functions of NM such as transcription of active genes and growth.

Animals↗
PubMed1996

A monoclonal antibody reactive with a common epitope of Moraxella (Branhamella) catarrhalis lipopolysaccharides.

A hybrid cell line producing a monoclonal antibody (MAb) against Moraxella (Branhamella) catarrhalis lipopolysaccharide (LPS) was established. The specificity of the MAb 1B12 to purified rough LPSs from six strains of M. catarrhalis was ascertained by enzyme-linked immunosorbent assay (ELISA), competitive-inhibition ELISA, and immunoblotting. MAb 1B12 bound to live bacterial cells and culture supernatants from a total of 34 strains of M. catarrhalis, including 12 strains with different LPS serotypes. No cross-reactions with smooth and rough LPSs from selected enterobacterial and nonenterobacterial strains, with other respiratory pathogens, or with Neisseria species were observed. These data suggest that MAb 1B12 recognizes a common epitope of M. catarrhalis LPS which differs from serotype determinants.

Antibodies, Monoclonal↗
PubMed1996

A Sleepy, Hungry Teenager.

A 16-year-old male was admitted for repeated episodes of hypersomnia, hyperphagia, and abnormal behavior, the first of which was preceded by alcohol and marijuana use. He was started on lithium therapy and lethargy and hyperphagia gradually improved, although he remained oppositional and irritable. After careful evaluation, his symptoms were concluded to meet Critchley's criteria for the diagnosis of Klein-Levin syndrome, which was supported by his response to prophylactic use of lithium.

Journal Article↗
PubMed1996

Use of flecainide for refractory atrial tachycardia of pregnancy.

Sustained arrhythmias during pregnancy are uncommon. However, when they do occur, atrial tachycardias are usually amenable to pharmacological or electrical therapy. We describe a case of sustained atrial tachycardia in a pregnant patient. The tachycardia was resistant to commonly used antiarrhythmic drugs and to cardioversion but rapidly responded to flecainide, with return to sinus rhythm until the patient was delivered of a healthy baby.

Adult↗
PubMed1995

CD66 family members are associated with tyrosine kinase activity in human neutrophils.

The granulocyte activation Ags, CD66a, CD66b, CD66c, and CD66d, are expressed at low levels on resting blood granulocytes, but their surface expression is up-regulated following stimulation. CD66a, in contrast to CD66b and CD66c which are anchored to the membrane via a glycosyl-phosphatidylinositol linkage, is a transmembrane protein with a cytoplasmic domain. We have previously reported that CD66a is phosphorylated in human neutrophils, largely on tyrosine, with a lower level of phosphoserine. We have now found that CD66a undergoes a rapid increase in phosphorylation following stimulation with FMLP, platelet-activating factor, and 12-O-tetradecanoyl-phorbol-13-acetate. This increase in phosphorylation was transient, with maximal phosphorylation observed by 1 min and a return to base line by 5 min following stimulation. Protein kinase activity was detected in neutrophils associated with CD66a, CD66b, and CD66c. Most of the protein kinase activity associated with these Ags was tyrosine kinase activity, with a lesser amount of threonine and serine kinase activities. Lyn and Hck accounted for much of the associated tyrosine kinase activity. The data suggest that phosphorylation of CD66a on tyrosine by an associated tyrosine kinase may play a role in the function of CD66a. In addition, associated tyrosine kinase activity may play a role in signal transduction from CD66a, CD66b, and CD66c to regulate other cell functions.

Antigens, CD↗
PubMed1995

Role of protein phosphorylation in post-translational regulation of protein B23 during programmed cell death in the prostate gland.

Protein B23 is a nucleolar and nuclear matrix-associated phosphoprotein that is involved in ribosome synthesis. Its expression and phosphorylation in rat ventral prostate, an androgen target organ, are profoundly influenced by androgens. Induction of programmed cell death (apoptosis) in the prostatic epithelium by androgen deprivation in the animal induces an early decline in protein B23 in the absence of a corresponding loss of protein B23 mRNA. We have now demonstrated that prostatic nuclei retain the ability to transcribe the B23 mRNA and that a significant amount of this mRNA persists even after 7 days of androgen deprivation when > 80% of the prostatic epithelial cells have undergone apoptosis. The B23 mRNA from these nuclei is also translatable in vitro. However, the majority of the B23 mRNA is associated with free and short-stretch polysomes, which may account for the castration-induced decline in synthesis of protein B23 in vivo. In addition, the mechanism of down-regulation of protein B23 in apoptotic prostatic cells appears to relate to two coordinate signals, which include loss of phosphorylation of the protein as well as the expression of a protease active toward dephosphorylated protein B23, under these conditions.

Androgens↗
PubMed1995

CD50 (ICAM-3) is phosphorylated on tyrosine and is associated with tyrosine kinase activity in human neutrophils.

CD50 (ICAM-3) is expressed at a high level on resting blood granulocytes, monocytes, and lymphocytes. The constitutive high expression of CD50 on resting leukocytes suggests that it is an important LFA-1 ligand in the initiation of the immune/inflammatory response. Using a radiolabeling technique initially designed to detect ecto-protein kinase activity, we found that CD50 mAbs immunoprecipitated a approximately 125- to 170-kDa phosphoprotein from human neutrophils. Phosphorylation was increased after stimulation with the chemotactic agent FMLP, platelet-activating factor, 12-O-tetradecanoyl-phorbol-13-acetate, and the calcium ionophore A23187. This increase in phosphorylation was transient with the maximal phosphorylation, being observed by 1 min. Phosphoamino acid analysis revealed that CD50 contained predominantly phosphotyrosine. Although this assay system was designed initially to detect ecto-protein kinase activity, subsequent studies have shown that membrane proteins can be phosphorylated on the cytoplasmic domain under these conditions. When CD50 was immunoprecipitated from solubilized neutrophils, protein tyrosine kinase activity associated with CD50 was detected in the immunoprecipitate. The data suggest that phosphorylation of CD50 on tyrosine by an associated tyrosine kinase plays a role in the function of CD50.

Antigens, CD↗
PubMed1995

Corynebacterium pseudodiphtheriticum: a respiratory tract pathogen.

From January 1986 through February 1993, there were 16 episodes of respiratory infection due to Corynebacterium pseudodiphtheriticum in 13 patients. The ages of patients ranged from 24 to 77 years; the ratio of male to female patients was 3:1. One patient had three episodes of infection, and another patient had two. In one patient, who died of disseminated intravascular coagulation, the level of IgG was low. One patient was receiving prednisolone when the infection occurred. In two cases a mixed infection with Streptococcus pneumoniae was noted. Sputum cultures yielded C. pseudodiphtheriticum (> or = 10(7) cfu/mL). An increased neutrophil response in the sputum of infected patients was observed. Gram staining and electron microscopy of sputum showed phagocytosis of C. pseudodiphtheriticum by the neutrophils. ELISAs also showed an increase in the level of immunoglobulin against C. pseudodiphtheriticum after infection. Tests for determination of MICs of antibiotics revealed that C. pseudodiphtheriticum isolates were susceptible to ampicillin, amoxycillin/clavulanic acid, cefazolin, cefuroxime, ceftazidime, and imipenem. All strains were resistant to nalidixic acid; borderline susceptibility to ofloxacin, norfloxacin, and ciprofloxacin was noted. We suggest the use of beta-lactam antibiotics in the treatment of infection with C. pseudodiphtheriticum.

Adult↗
PubMed1995

Antimicrobial activity of glycerine-ichthammol in otitis externa.

The clinical efficacy of glycerine-ichthammol in otitis externa may be due to an anti-inflammatory action of ichthammol or a dehydrating effect of glycerine on the oedematous ear canal. Its antimicrobial activity, if any, against the common organisms in otitis externa is not well known. A study of the antibacterial property of glycerine-ichthammol as measured by a growth inhibition test and a modified cidal assay, showed inhibition of selected gram positive organisms (Streptococcus pyogenes and Staphylococcus aureus) by ichthammol and glycerine-ichthammol combination, but only negligible antibacterial activity against Pseudomonas aeruginosa and Escherichia coli. Candida albicans was also weakly inhibited. As the activity against gram negative organisms is minimal, incorporation of an anti-gram negative antibiotic such as gentamicin in the glycerine-ichthammol compound to enhance its antibacterial spectrum is suggested.

Anti-Bacterial Agents↗
PubMed1995

Nephrotic syndrome and pulmonary artery thrombosis.

Nephrotic syndrome is associated with various thromboembolic phenomena. Thrombosis in both the arterial and venous sides of circulation has been reported. We report a case of a 42-year-old man who suffered a right lower lobe pulmonary artery thrombus followed by thrombosis of the middle cerebral artery.

Adult↗
PubMed1995

[Measurement of serum TSH receptor antibodies in thyroid patients using TRAb Dade kits].

TRAb Dade kit is a radioreceptor assay that detects autoantibodies in serum of patients with thyroid diseases which interfere with the binding of 125I labeled TSH to its receptor. In this paper we examined the basic and clinical usefulness of newly developed TRAb assay kits. The intra and inter assay coefficients of variation were 7.9% and 8.4%, respectively. There was no significant effect of temperature and incubation time on TRAb values. The influence of conjugated, unconjugated bilirubin, hemoglobin and turbidity was not so significant on TRAb values. TRAb values in serum of 68 untreated Graves' disease were above the normal range, but most (78%) treated Graves' patients who became euthyroid after receiving antithyroid drug, showed the normal range. In patients with chronic renal failure TRAb values were also within the normal range. A significant correlation (y = 1.0x-0.88, r = 0.95) was observed between this TRAb kit and TRAb Cosmic values in various thyroid conditions. This new assay for TRAb was simple, rapid and reproducible. The measurement of serum TRAb values was useful for the evaluation of physiological and pathological function and seemed to be helpful in the management of patients with thyroid disease.

Autoantibodies↗