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Biomedical subjects

K Ahmed

Publications and source records attributed to K Ahmed.

At least 127 records · Page 7Linked to original sources

Right atrial catheters in children with cancer: a decade of experience in the use of tunnelled, exteriorized devices at a single institution.

In the period 1980-1988, data were collected (prospectively from 1985) on the clinical utilization of exteriorized, tunnelled, right atrial catheters in children with cancer undergoing treatment at a single institution. A total of 231 devices were placed in 180 patients. Individual catheters were in place for a median of 314 days, with a total experience of more than 83,000 days. This form of long-term venous access was used for the administration of antineoplastic agents and other drugs, blood products (especially platelet concentrates and packed red blood cells), parenteral nutrition and infusion of other fluids, obtaining samples of venous blood, and giving intravenous contrast media and radiolabeled substances for radiological investigations. Almost 80% of catheters were removed electively (on completion of scheduled therapy or at death), with the remainder requiring removal in the management of infection or device displacement. Infections were manifest in two-thirds of the children, most commonly (60%) at the catheter exit site on the anterior chest wall. "Clinically significant" infection occurred with a frequency of 2.1 episodes per 1,000 patient days, with Staphylococcal species predominating except for the circumstances of catheter colonization in which Gram-negative, waterborne organisms were most in evidence. Empirical, intravenous, combined antibiotic therapy was effective in approximately 90% of "clinically significant" episodes. Mechanical complications (traveling, leakage, or catheter occlusion) occurred less frequently and were managed by repairing or replacing the device, or clearing the block. Indwelling catheters, of the Broviac or Hickman types, offer major advantages with acceptable morbidity in the management of children with malignant diseases.

Adolescent↗

Digitalis receptor sugar binding site characteristics: a model based upon studies of Na+, K(+)-ATPase preparations with differing digitalis sensitivities.

The structure-activity relationships of the genin moieties of digitalis glycosides are commonly elucidated by determining the inhibitory potency of a variety of genins toward the plasma membrane Na+, K(+)-ATPase; qualitatively these relationships appear to be fairly independent of the specific Na+, K(+)-ATPase preparation utilized for the analysis. To determine whether this is the case with regard to the sugar moieties of glycosides, the inhibitory effects of 12 monoglycosides of digitoxigenin toward four Na+, K(+)-ATPase preparations of different origin were measured. It was found that while recognition of the major structural determinants of sugar activity appeared to be independent of enzyme source, recognition of the minor structural determinants of activity showed some source dependence. It was also observed that the intrinsic sensitivity to sugar potentiation may be source dependent and unrelated to intrinsic sensitivity to inhibition by digitoxigenin. These observations are compatible with a model of the Na+, K(+)-ATPase sugar binding site(s) in which intrinsic sensitivity to sugar attachment as well as recognition characteristics (for sugar structural features) both determine the extent to which a sugar moiety may contribute to the activity of monoglycosides. Further, in these studies one of the Na+, K(+)-ATPase preparations employed was obtained from rat brain, a tissue known to contain a mixture of ouabain sensitive and insensitive isoforms. We have observed that the rigorous purification techniques employed appear to have selectively removed from or denatured the less ouabain sensitive alpha 1 isoform found in this enzyme preparation.

Animals↗

Effect of anticancer drugs on the release of tumour necrosis factor in vitro.

The anticancer drugs Adriamycin, bleomycin, vincristine, 4-hydroperoxycyclophosphamide, FK156 and FK565 and the immunosuppressive drug cyclosporin-A were tested for their effect on lipopolysaccharide-induced tumour necrosis factor-alpha (TNF) release from rat peritoneal exudate cells in vitro. FK565 resulted in a marked enhancement of TNF release when added to cultures at doses of 1 microgram/ml and 10 micrograms/ml. However, FK156, Adriamycin, bleomycin, 4-hydroperoxycyclophosphamide, vincristine and cyclosporin A did not affect the release of TNF under the same conditions. Puromycin inhibited the release of TNF in the same system at non-cytotoxic doses of 1 microgram/ml and 10 micrograms/ml.

Animals↗

Monoclonal antibodies against nuclear casein kinase NII (PK-N2).

A monoclonal antibody was produced against the nuclear casein kinase II (PK-N2) isolated from rat liver. The antibody was of the IgM class, and showed immunoreactivity towards the higher molecular weight subunit (41K Da) of the protein kinase in Western blots. The antibody was equally reactive towards the PK-N2 isolated from rat ventral prostate indicating that it can recognize the enzyme from different tissues of the rat. The antibody also detected the cytosolic casein kinase II (CK-2) suggesting significant similarity of the antigenic domains in the two forms of this protein kinase. No binding was detected with the nuclear or cytosolic casein kinase I (PK-N1 and CK-1). The antibody did not inhibit the enzyme activity or directly precipitate the enzyme, but when coupled to an affinity matrix and cross-linked with dimethylpimelimidate, it was capable of removing nearly all the PK-N2 activity from solution.

Animals↗

Electron microscopic observation of Branhamella catarrhalis.

The hemagglutination (HA) test was done on 85 strains of Branhamella catarrhalis, isolated from sputum of patients with respiratory infections; 53% were HA positive strains. Three HA positive and three HA negative strains were selected and were observed under the electron microscope. The bacterial cell wall appeared to be lobulated and its total thickness was about 38 nm. The nuclear region consisted of whorls or fibrils and dense bodies. Five strains were fimbriated and one strain was nonfimbriated. The size of fimbriae was about 68 nm in length and 4.5 nm in width. The fimbriae of Branhamella catarrhalis were densely arranged and peritrichous in distribution. There was no change of fimbriation between broth and agar cultures.

Bacterial Infections↗

The value of preoperative estimation of haemoglobin in children undergoing tonsillectomy.

Preoperative estimation of haemoglobin in children undergoing tonsillectomy is routinely practised in most centres. To assess the value of this investigation the haemoglobin of 250 consecutive children undergoing tonsillectomy was estimated. Two children were clinically found anaemic preoperatively, and this was confirmed on blood testing. Since the prevalence of anaemia is low, it is proposed that the practice of routine preoperative estimation of haemoglobin is unnecessary, traumatic and expensive, and therefore requires reconsideration.

Anemia↗

Effect of ampicillin, cefmetazole and minocycline on the adherence of Branhamella catarrhalis to pharyngeal epithelial cells.

Using pharyngeal epithelial cells from a healthy adult and eight strains of Branhamella catarrhalis (B. catarrhalis) isolated from eight patients with respiratory infection the effect of subminimal inhibitory concentrations of cefmetazole, ampicillin and minocycline on adherence was examined. Cefmetazole-treated bacterial attachment (44 +/- 28; mean +/- S.D.) decreased significantly (p less than 0.05) compared to the control (84 +/- 27). Statistically no significant difference in adherence was found between ampicillin-treated bacteria (63 +/- 36) and the control (95 +/- 40) or minocycline-treated bacteria (91 +/- 39) and the control (109 +/- 40). Large bacteria was observed after cefmetazole and ampicillin treatment. In addition to diplococci, tetrads were observed after cefmetazole treatment. Significant correlation between the MICs and adherence ability was not found. The results suggests that these three antibiotics were not responsible for the increase in B. catarrhalis infection by increasing adherence ability.

Ampicillin↗

Twinning rates in a rural area of Bangladesh.

In this study we investigate the incidence of twin births over a period of 16 years in a rural area of Bangladesh using data from the Demographic Surveillance System of the International Centre for Diarrhoeal Disease Research. Over the study period twinning rates fluctuated between 7.8 and 11.2 per 1000 live births. The twinning rate was strongly correlated with maternal age; the rate for mothers over 35 years of age was about 3 times higher than for mothers younger than 20 years. The variation in twinning rate with maternal age is due to the variation in dizygotic twinning; the rate of monozygotic twinning is almost constant for all ages. Twinning rates were higher in the treatment area than in the comparison area after controlling for maternal age and parity. The rates were lower for monozygotic twinning and higher for dizygotic twinning in the treatment area than in the comparison area. Seasonality was observed for both twins and singletons, but the peak for twinning precedes that for singleton births by more than a month.

Bangladesh↗

Polyclonal antibodies against rat liver cytosolic casein kinase II (CK-2) cross-react with CK-2 from other tissues and nuclear form (PK-N2) of the enzyme.

Casein kinase II (CK-2) is a ubiquitous serine/threonine protein kinase, and is localized to both the cell nucleus and cytoplasm. Despite extensive biochemical similarities in their properties, there is evidence that the two forms of the enzyme exhibit certain distinctions (1). This prompted us to produce antibodies against CK-2, which could be utilized as a possible tool for investigations of the various forms of this enzyme. Specific polyclonal antibodies against the rat liver cytosolic CK-2 were raised in egg yolk of laying hens; the enzyme had repeatedly failed to elicit an immunogenic response in rabbits. The purified polyclonal antibody (egg yolk immunoglobulin, IgY) recognized all three subunits (42, 38, and 28 kDa) of the enzyme in immunoblots. The antibody when bound to a matrix was capable of removing CK-2 from solution, and the bound enzyme could be recovered from the immunoaffinity matrix with 0.1 M diethylamine. The antibody exhibited a high affinity towards CK-2 prepared from cytosol of liver, ventral prostate, and several other rat tissues, but no immunoreactivity was detected towards a number of other protein kinases tested. The subunits of the nuclear form of CK-2 (PK-N2) migrated differently when electrophoresed in parallel in the same gel. However, the antibody did cross-react with the various subunits of PK-N2 suggesting a significant homology in the immunogenic domains in the various subunits of the two forms of the enzyme.

Animals↗

Hypertensives who cannot get proper antihypertensive treatment.

Hypertension is common in developing countries particularly in Africa and the Caribbean. Antihypertensive treatment has been validated as effective in preventing strokes but often even the cheapest antihypertensive drugs are unavailable. This means that a large number of patients are not receiving the treatment that they need. Action is needed by the International Society of Hypertension, the World Hypertension League, the European and American Societies of Hypertension and the pharmaceutical industry to correct this major shortfall of treatment.

Antihypertensive Agents↗

Metastatic squamous cell carcinoma of an unknown primary localized to the neck. Advantages of an aggressive treatment.

Treatment of patients with squamous cell carcinoma (SCC) of an unknown primary localized to the neck is still controversial, particularly regarding advanced disease. We reviewed 41 such patients treated with surgery and/or radiotherapy (RT) (n = 25) or with combined modality treatment including chemotherapy (CH) (n = 16). The male to female ratio was 28 to 13, and the median age was 58 years (range, 32 to 94 years). There were 27 (66%) patients with poorly differentiated SCC and 8 with moderately differentiated or well-differentiated cancer. Twenty-three (56%) patients had N3 disease, 16 (39%) had N2, and 2 had N1. The majority of N3 patients have been treated with CH and RT (n = 12) or with RT alone (n = 9). The combined CH-RT was well tolerated, with no life-threatening toxicity. The complete response (CR) to CH-RT was 81% (11 patients have no evidence of disease [NED] currently). The median survival time of this group was 37+ months. Of the 25 patients who had surgery and/or RT as their first planned treatment, 7 (28%) have NED currently. The median survival time of this group was 24 months. Patients with N3 disease who received CH had a higher CR rate and a longer survival time as compared with those treated with surgery and/or RT, despite a higher (N3) stage of disease. These findings warrant further investigation in randomized cooperative studies.

Adult↗

Effect of anticancer agents neothramycin, aclacinomycin, FK-565 and FK-156 on the release of interleukin-2 and interleukin-1 in vitro.

Four anticancer agents, neothramycin, aclacinomycin, FK-565 and FK-156, were tested for their effects on concanavalin-A-induced interleukin-2 release from rat splenocytes in vitro. Neothramycin showed an enhancement of the release of interleukin-2, whereas aclacinomycin had no effect. FK-565 and FK-156 were found to inhibit the release of interleukin-2 under similar conditions. The inhibition was much more marked with FK-565. These drugs were also tested for their effects on the release of interleukin-1 from rat peritoneal exudate cells stimulated by lipopolysaccharide in vitro. Neothramycin and aclacinomycin did not affect the release of interleukin-1; however, both FK-565 and FK-156 resulted in its enhanced release under these conditions.

Aclarubicin↗

Effect of anticancer drugs on the release of interferon gamma in vitro.

Some conventional and experimental anti-cancer drugs were tested for their effect on concanavalin-A-induced interferon gamma release from rat splenocytes in vitro. When 2.5 x 10(6) rat splenocytes/ml, stimulated with 1 microgram/ml concanavalin A, were incubated with various non-cytotoxic doses of the vinca alkaloid vincristine, there was an inhibition of the release of interferon gamma in culture supernatants. The antitumour antibiotics bleomycin and Adriamycin, alkylating agents 4-hydroperoxycyclophosphamide and mafosfamide, and the immunoactive peptides FK156 and FK565 did not affect the release of interferon gamma under similar conditions. However, cyclosporin A, in similar experiments, markedly inhibited the release of interferon gamma.

Animals↗

A clinical virology database for a regional virology service.

We describe a laboratory information system employing a virus and chlamydia database developed over seven years which is used by a regional laboratory, performing virus and chlamydia testing. The information system is implemented on a University mainframe computer and accessed by computer terminals in the laboratory. The database is used to identify patients, store patient test results, minimize clerical work and improve accuracy of reported results. The database also serves as a patient registry for use in education and research.

Adolescent↗

A clinical study of stroke.

The records of 99 Saudis (68 males and 31 females) admitted to the King Fahd Hospital of the University (KFHU) over a two-year period were reviewed. There was a male to female ratio of 2.2:1. Eighty-five (86%) patients were above 44 years old. All the patients under 44 years old were males. The major predisposing factors identified were hypertension (65%), diabetes mellitus (36%), cardiac disease (20%) and cigarette smoking (29%). The combination of hypertension and diabetes mellitus seemed to carry a higher risk especially in women. Motor dysfunction, encountered in 95 (96%) patients was the dominant clinical feature, and presented mainly as hemiparesis (83 out of 95). Impaired level of consciousness at presentation carried a poor prognosis particularly in the elderly.

Adolescent↗

Polyamine-like effects of aminoglycosides on various messenger-independent protein kinase reactions.

Gentamicin and several other aminoglycoside antibiotics in millimolar concentrations directly stimulate the phosphorylation of casein by purified preparations of cAMP- and Ca2+-independent protein kinases PK-C2 (equivalent to cytosolic casein kinase II) and its nuclear counterpart PK-N2 from rat liver and ventral prostate. These stimulatory effects of aminoglycoside antibiotics were similar to those exerted by the aliphatic polyamine spermine. Phosphorylation of casein by purified preparations of messenger-independent protein kinases PK-C1 (equivalent to cytosolic casein kinase I) and its nuclear counterpart PK-N1 was much less enhanced by spermine and the aminoglycoside antibiotics tested. Stimulations of PK-N2 reactions evoked by gentamicin or spermine (at 0.5 and 1.0 mM) were not additive. Several amino sugars tested were without effect on these protein kinases. Methylglyoxal bis(guanylhydrazone) which is known to block the stimulatory effects of polyamines on certain other enzymes did not alter spermine-stimulated phosphorylation of casein catalyzed by PK-N2 preparations.

Aminoglycosides↗

An intensive, five course, alternating combination chemotherapy induction regimen used in patients with advanced, unresectable head and neck cancer.

Progress in the treatment of advanced squamous cell cancer (SCC) of the head and neck (H & N) has included the development of combination chemotherapeutic regimens that achieve impressive complete response (CR) rates using two to three courses therapy with minimal toxicity and good patient tolerance. Further improvements in these results will require intensification of induction regimens. Therefore, a five course, alternating combination chemotherapy induction trial was initiated in an attempt to test the feasibility and toxicity of a prolonged, intensive induction regimen in patients with advanced SCC of H & N. Courses 1, 3, and 5 consisted of fluorouracil as a 120-hour infusion (5FU-I) with cisplatin (CACP) as an intravenous (IV) bolus. Courses 2 and 4 consisted of 3 weekly doses of high-dose methotrexate (HDMTX) followed by 5FU (5FU-b) and leucovorin rescue (LR). Forty-six stage IV patients with SCC of H & N (85% T4 and 58% N3) were entered. Thirty-one patients completed the study and 15 did not. Twenty-one of the 46 patients (46%) achieved a CR. Twenty-five of the 46 patients had N3 neck disease, ten of these 25 achieved a CR (40%), and eight did not complete therapy. Of the 15 patients not completing this study, one patient achieved a CR and eight achieved a partial response (PR). Eight of 46 (17%) were removed from study for reasons of toxicity (6% to 13%) or tumor progression (2% to 4%). The remaining seven were removed due to intercurrent medical conditions (four uncomplicated pneumonias and one gun shot wound) or lost to follow-up (2). Myelosuppression, mucositis, and skin toxicity increased in frequency by the end of the trial but were acceptable and reversible. The activity of this five-course regimen is promising given the advanced disease status of patients treated. Consideration of concurrent medical conditions, patient compliance, intensity of medical, nutritional and social support, and levels of acceptable toxicity will be necessary in the design of future, intensive induction trials.

Adult↗