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Biomedical subjects

R Ahmed

Publications and source records attributed to R Ahmed.

At least 235 records · Page 13Linked to original sources
PubMed1980

Genetic variation during lytic reovirus infection: high-passage stocks of wild-type reovirus contain temperature-sensitive mutants.

Wild-type clones of reovirus serotypes 1 (Lang), 2 (Jones), and 3 (Dearing) were serially passaged in L cells at a high multiplicity of infection, and the virus population was examined at passage levels 2, 5, and 11 for the presence of temperature-sensitive (ts) mutants. By passage 11 all three serotypes contained ts mutants that were not present in the original wild-type stock. ts mutants representing three mutant groups were identified. The majority of these mutants were in group G. Our results show that high-passage stocks of reovirus consist of a genetically heterogeneous population.

Genes, Viral↗
PubMed1980

Genetic variation during persistent reovirus infection: presence of extragenically suppressed temperature-sensitive lesions in wild-type virus isolated from persistently infected L cells.

Persistent reovirus infection of L cells was established with a serially passaged stock of temperature-sensitive (ts) mutant C(447) containing greater than 90% defective interfering particles. Within a month after establishment of the carrier culture, the ts mutant was replaced by virus that expressed the wild-type (ts(+)) temperature phenotype (R. Ahmed and A. F. Graham, J. Virol. 23:250-262, 1977). To determine whether the ts(+) phenotype of the virus was due to intragenic reversion or to the presence of an extragenic mutation suppressing the original ts defect, several clones were backcrossed to wild-type reovirus, and the progeny of each cross were screened for temperature sensitivity. The results indicated that the original tsC lesion had reverted. However, in two of the seven clones examined, new ts lesions were found. These new ts lesions appeared phenotypically as ts(+) due to the presence of extragenic suppressor mutations. Temperature-sensitive mutants representing three different groups were rescued from one suppressed clone, indicating that this ts(+) clone contained multiple ts lesions. Among the ts mutants rescued were the initial isolates of a new recombination group which we have designated H. Some of the ts mutants rescued from the suppressed clones are capable of interfering with the growth of wild-type reovirus and may play a role in maintaining the carrier state. The results of this study show that persistently infected L cells contain a genetically heterogeneous population of reovirus even though all virus clones express the ts(+) phenotype. It is thus critical to distinguish between genotype and phenotype when analyzing viruses that emerge during persistent infection.

Animals↗
PubMed1979

Hypothyroidism.

Explore the source record for details and available documents.

Female↗
PubMed1977

Persistent infections in L cells with temperature-sensitive mutants of reovirus.

Serial passage of reovirus temperature-sensitive (ts) mutant C(447) produced by passage 9 (P9) a heavily defective population of virus from which the double-stranded RNA genomic segments L(1), L(3), and M(1) were largely missing. Viral cores obtained from this P9 population were heterogeneous with respect to buoyant density in CsCl gradients, suggesting that particles were present with different combinations of deleted segments. Similar observations were made with the E(320) ts mutant of reovirus. By serial passage P15, 90% of the E(320) viral population was defective and the major missing genomic segments were L(1) and L(3). Persistent infections were readily established in monolayer cultures of L cells with P9 of C(447) virus and P15 of E(320) virus and in Vero cells with P9 of C(447) virus. Under similar conditions persistent infections could not be initiated with defective-free populations of C(447) or E(320) viruses. The greater the capacity of defective virus in the population to interfere with viral growth, the more readily persistent infection was initiated. During their maintenance persistently infected cells were subcultured approximately twice a week. More than 80% of the cells continuously produced virus. By subculture 6 the original ts infectious viral component had been replaced by a small-plaque mutant with a ts(+) phenotype. Defective virus was always present in the carrier cells. In addition to the more commonly observed defectives whose cores banded at approximately rho = 1.40 to 1.415 g/ml in CsCl gradients, a new class of defective core was seen banding in the region of 1.34 to 1.36 g/ml. This latter particle, which has not been thoroughly characterized as yet, is termed "light defective." Persistently infected cells underwent periodic crises during their maintenance, during which the cultures partially lysed and then rapidly grew to confluence. Crises corresponded to a burst of infectious virus from the cells and a relatively low concentration of light defectives. During quiescent periods the concentration of light defectives amounted to as much as 98% of the total viral population. The function of light defectives is not yet clear, but it seems essential to assign major importance to defective virus in maintaining persistent infections in this system.

Defective Viruses↗
PubMed1977

Complications of long term transbrachial hepatic arterial infusion chemotherapy.

A total of 127 transbrachial hepatic artery catheters were placed in 75 patients for prolonged infusion of chemotherapeutic agents for primary and secondary tumors of the liver. Hepatic or celiac artery catheterization was possible in 97.4% of patients. The most frequent major complication was partial or complete arterial thrombosis (30 patients). bleeding at the arteriotomy site and pseudoaneurysm also occurred. Minor complications included displacement of catheter from the hepatic artery in 46, cracks or leaks in the catheter at the arteriotomy site in 21, and clotted catheter in 10 instances. Infection occurred in four patients and loss of radial pulse in seven. In view of a significant increase in survival, the complications did not contraindicate long term intraarterial infusion of chemotherapeutic agents. The no. 5 French blue thin wall 1.24-1.70 mm tubing proved to be easiest to use and least prone to complications. Proper management of these patients by a team approach (nurse, oncologist, and radiologist) helps to minimize the frequency and severity of complications.

Adolescent↗
PubMed1970

Phenolic acid concentrations in the lumbar cerebrospinal fluid of Parkinsonian patients treated with L-dopa.

The acid metabolites of dopamine and 5-hydroxytryptamine were estimated in the lumbar cerebrospinal fluid (CSF) of Parkinsonian patients both before and during treatment with l-dopa, the amino acid precursor of dopamine. An attempt was made to relate clinical improvement to the biochemical results. The dopamine metabolites, 3,4-dihydroxyphenylacetic acid and homovanillic acid, showed increases related to the dose of l-dopa, the increase in homovanillic acid concentration being proportionately greater than that of 3,4-dihydroxyphenylacetic acid. The concentration of the 5-hydroxytryptamine metabolite, 5-hydroxyindol-3ylacetic acid, was unaltered by the drug. Clinical improvement, which in the early stages was evident particularly in the bradykinesia, was found to occur at doses of l-dopa greater than 1·5 g/day. Effective doses of l-dopa gave rise to concentrations of dopamine metabolites in the CSF which were greater than normal. Possible implications of these findings are discussed.

Adult↗
PubMedDate not supplied

Hepatic hydatid cysts: sonographic follow-up after percutaneous sonographically guided aspiration.

PURPOSE: We studied the sonographic appearances of hepatic hydatid cysts and used sonography to follow up these cysts after sonographically guided aspiration using the PAIR technique. METHODS: Included in this study were 362 patients with 558 hepatic hydatid cysts. Initial sonographic examination revealed 510 noncomposite cysts and 48 composite cysts (18 rosette and 30 honeycomb pattern). Noncomposite hydatid cysts (510 cysts) were aspirated and treated with scolicidal agents using the PAIR technique. Sonographic follow-up was done for up to 5 years after aspiration. RESULTS: There was immediate detachment of the germinal layer in all cysts during aspiration. There were no serious complications. Sonographic follow-up after 1 month and 1 year revealed complete cyst collapse in 326 cysts (64%) and 449 cysts (88%), respectively. Repeat ultrasound scanning showed a continued decrease in the sizes of all remaining cysts. Organized lesions (pseudosolid pattern) were detected in only 26 cases after up to 5 years of follow-up. CONCLUSIONS: The most common sonographic appearance of hepatic hydatid cysts among Egyptians is noncomposite, anechoic cysts. The PAIR technique is a safe, effective, and inexpensive therapeutic modality.

Adolescent↗
PubMedDate not supplied

Necrotising fasciitis in the head and neck region.

Necrotising fasciitis is an uncommon entity in present day medicine. Our review of the literature did not reveal any case involving the head and neck region. A case of this rare disease involving the head and neck region is presented.

Facial Dermatoses↗
PubMedDate not supplied

Genetic dissection of age-related changes of immune function in mice.

Understanding of the genetic basis of normal and abnormal development of the immune response is an enormous undertaking. The immune response, at the most minimal level, involves interactions of antigen presenting cells (APCs), T and B cells. Each of these cells produce cell surface and soluble factors (cytokines) that affect both autocrine and paracrine functions. A second level of complexity needs to consider the development of the macrophage/monocyte lineage as well as the production of the common lymphoid precursor which undergoes distinct maturation steps in the thymus and periphery to form mature T cells as well as in BM (BM) and lymphoid organs to form mature B cells. A third level of complexity involves the immune response to infectious agents including viruses and also the response to tumour antigens. In addition, there are imbalances that predispose to decreased responses (immunodeficiencies) or increased responses (autoimmunity). A fourth level of complexity involves attempts to understand the differences in the immune response that occurs at a very young age, in adults, and at a very old age. This review will focus on the use of C57BL/6 J X DBA/2 J (BXD) recombinant inbred (RI) strains of mice to map genetic loci associated with the production of lymphoid precursors in the BM, development of T cells in the thymus, and T-cell responses to stimulation in the peripheral lymphoid organs in adult and in aged mice. Strategies to improve the power and precision in which complex traits such as the age-related immune response can be mapped is limited with the current set of 35 strains of BXD mice. Strategies to increase these strains by generating recombinant intercross (RIX) strains of mice are being developed to enable this large set of lines to detect quantitative trait loci (QTLs) with a much higher consistency and statistical power. More importantly, the resolution with which these QTLs can be mapped would be greatly improved and, in many cases, adequate to carry out direct identification of candidate genes. It is likely that, given the complexity of the immune system development, the number of cells involved in an immune response, and especially the changes in the immune system with ageing, mapping hundreds of genes will be required to fully understand age-related changes in the immune response. This review outlines ongoing and future strategies that will enable the mapping and identification of these genes.

Aging↗
PubMedDate not supplied

Complications of thyroidectomy for benign disease.

BACKGROUND: Goitre is a common ailment seen in mountainous regions, like the periphery of Abbottabad. Thyroidectomies are very common in our center. METHODS: This study was done to find out the complication rate of thyroidectomies. RESULTS: 189 cases were operated in Ayub Hospital Complex, Abbottabad during July 96 and Dec. 99. All patients were with benign disease and any case found to have malignancy were excluded from the study. The overall complication rate for all the categories was 15%. In total 5 patients died within one month of surgery.

Female↗