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Biomedical subjects

M Mohammad

Publications and source records attributed to M Mohammad.

13 recordsLinked to original sources
PubMed2000

Three different proteins recognize a multifunctional determinant that controls replication initiation, fork arrest and transcription in Tetrahymena.

Type I elements regulate the initiation of DNA replication, elongation of replication forks and transcription of the Tetrahymena thermophila rDNA minichromosome. Previous studies identified a 24 kDa protein, ssA-TIBF, which binds the A-rich strand of type I elements. Here we describe two additional type I element binding activities (native mol. wt approximately 65 and approximately 250 kDa) that interact with DNA via previously unidentified 32 and 110 kDa polypeptides. The 65 kDa activity was purified to homogeneity and consists of a homodimer of a 32 kDa polypeptide. In contrast to the other type I element binding factors, the 65 kDa activity partitions preferentially to the nuclear fraction during isolation. Levels of the 65 kDa activity increase dramatically in starved cells, raising the possibility that it might negatively regulate replication or transcription. By comparison, the other two binding activities were elevated slightly during macronuclear development, when the rDNA was undergoing DNA replication. Previous studies indicate that the initiation of rDNA replication is regulated by long range interactions between dispersed type I elements. Competitive DNA binding or cooperative protein-protein interactions between the factors described here may play a regulatory role in replication or expression of the rDNA minichromosome.

Animals↗
PubMed2000

Octylcyanoacrylate versus polyurethane for treatment of burns in swine: a randomized trial.

In order to determine whether the enhanced reepithelialization of second-degree burns treated with octylcyanoacrylate (OCA) was due to its occlusive nature we compared reepithelialization (REP) and infection rates of second degree burns treated with OCA and polyurethane film (Tegaderm) in swine. Forty-four standardized partial thickness burns were created by applying an aluminum bar preheated to 80 degrees C to the backs of pigs for 20 s and randomly treated with OCA or Tegaderm. Full thickness biopsies were taken at 7, 10 and 14 days for blinded histopathological evaluation of rates of infection and reepithelialization. T-tests and chi(2) tests were used for group comparisons. There were no between group difference in the rates of reepithelialization and infection. All wounds were reepithelialized by day 14 and there were no infections in either group. We conclude that treatment of partial thickness burns with OCA spray or Tegaderm results in similar rates of reepithelialization and infection, suggesting that the beneficial effects of OCA on reepithelialization are due to its occlusive nature.

Animals↗
PubMed2000

Octylcyanoacrylate for the treatment of contaminated partial-thickness burns in swine: a randomized controlled experiment.

OBJECTIVE: To compare infection and reepithelialization rates of contaminated second-degree burns treated with octylcyanoacrylate (OCA), silver sulfadiazine (SSD), polyurethane (PU) film, and dry gauze (control; C) in swine. METHODS: Eighty standardized burns were created by applying an aluminum bar preheated to 80 degrees C to the backs and flanks of young pigs for 20 seconds. All burns were immediately contaminated with 0.1 mL of Staphylococcus aureus 10(5)/mL and randomly treated with OCA spray, SSD, PU, or dry gauze (C). Full-thickness biopsies were taken at 3, 7, and 14 days for blinded histopathologic evaluation using hematoxylin and eosin (H&E)-stained slides. Burns were considered infected in the presence of interstitial reticular dermal neutrophils containing bacteria (intraobserver agreement, kappa = 1.00). Quantitative wound cultures were performed on a second day-3 specimen. RESULTS: At day 3, wound infection rates were 30% (OCA), 50% (SSD), 55% (PU), and 50% (C); p = 0.40 (Kruskal-Wallis test). At day 7, infection rates were 35% (OCA), 85% (SSD), 70% (PU), and 65% (C); p = 0.01. Median bacterial counts at day 3 were 6,500 (OCA), 20,000 (SSD), 1,000,000 (PU), and 650,000 (C); p = 0.29. The proportion of completely reepithelialized wounds at day 14 were 75% (OCA), 90% (SSD), 85% (PU), and 90% (C); p = 0.50. CONCLUSIONS: Treatment of contaminated partial-thickness burns with OCA spray resulted in fewer infections at one week than with the other three treatments.

Animals↗
PubMed1997

Alterations of physostigmine-induced yawning by chronic lithium administration in rats.

The effect of chronic lithium pretreatment on physostigmine-induced yawning was investigated in male rats. Intraperitoneal administration of physostigmine to rats induced yawning in a biphasic manner. However the maximum response was obtained by 0.2 mg/kg of the drug. Intracerebroventricular administrations of a putative M1 and M2 muscarinic receptor antagonists, pirenzepine and methoctramine decreased physostigmine-induced yawning. Intraperitoneal administration of a non-selective muscarinic receptor antagonist, atropine, also decreased the physostigmine-induced yawning significantly. Chronic lithium pretreatment (30 days) reduced yawning induced by physostigmine. The inhibitory effect of pirenzepine, methoctramine and atropine on physostigmine-induced yawning increased in rats pretreated with chronic lithium. These findings indicate that yawning is induced by a central cholinergic mechanism and that chronic pretreatment of lithium may interact with the cholinergic-induced behaviour.

Animals↗
PubMed1996

Risk factors for retinopathy in diabetes mellitus in Kelantan, Malaysia.

Few attempts have been made to determine the risk factors for diabetic retinopathy which is a major cause of visual impairment and blindness. One hundred and forty patients of diabetes mellitus were studied to determine the prevalence and types of retinopathy, and its relation to various risk factors. Nearly half (48.6%) of the patients suffered from retinopathy. The significant associated risk factors were long duration of diabetes, proteinuria and elevated serum creatinine level. However, there was no significant association between the prevalence of retinopathy and high levels of serum cholesterol, C-peptide levels, associated hypertension, and glycaemic control of diabetes mellitus. An effective screening programme for detection of retinopathy in the patients of diabetes as a regular practice is encouraged.

Adolescent↗
PubMed1993

Pulmonary function in symptom-free asthmatics.

Seventy-five adult asthmatic patients with clinical remission underwent spirometry. Only 8.3% of the subjects demonstrated normal spirometry. The others had reduced vital capacity (VC), forced vital capacity (FVC), forced expiratory volume in one second (FEV1), maximum mid-expiratory flow rate (MMF) and peak flow rate (PEFR). This study demonstrates that asthma can cause irreversible airflow obstruction and there is a poor relationship between symptoms in asthmatics and their respiratory function test results.

Adolescent↗
PubMed1985

[Preliminary study in female rats of the immunoregulatory effect of estradiol, progesterone and pituitary prolactin on natural killer-like cell mediated cytotoxic activity].

A spontaneous non-immune natural killing-like cytotoxic activity is induced in cyclic non mated virgin F/344 females by progesterone + oestradiol or progesterone alone treatment after bilateral ovariectomy. Many indications attribute this cytotoxic response to the absence of the mating stimulated pituitary prolactin release which normally rescues the corpora lutea from regression, and brings about the necessary progesterone for pregnancy or pseudopregnancy.

Animals↗
PubMed1984

Rat pregnancy induces two suppressor cell activities.

Pregnancy in rat is able to stimulate two suppressor cell activities. One is specific to the paternal histocompatibility antigens and it resides in the T-lymphocyte population. The second is nonspecific and is of non-T nature. The use of various methods for pseudopregnancy and deciduoma installation has allowed the demonstration of two inducing circuits: (a) the presence of fertilized ova in the female genital tract and (b) the progestation hormonal status.

Animals↗
PubMed1984

Rat pregnancy immunoregulatory circuits are progestation hormonal status, decidual tissue, embryo-trophoblast and late pregnancy changes dependent.

We have tested the spleen cells of rats for their reactivity to mating and unrelated (third party) strain alloantigens during pregnancy, pseudopregnancy, and traumatic deciduoma installation. By cytotoxic T-lymphocyte assays, after 7-day one-way mixed lymphocyte cultures (MLC), we detected the presence of many immunoregulatory circuits among rat pregnancy and postpartum. They are progestation hormonal status, decidual tissue, embryo-trophoblast, late-pregnancy-parturition-associated changes, and lactation-hormonal-status dependent.

Animals↗
PubMed1978

Light-microscopical diagnosis of rabies. A reappraisal.

The validity of reports suggesting that Lyssa and Negri bodies are non-specific in the light-microscopical diagnosis of rabies was investigated. With Seller's impression technique, a substantial proportion of speciments found to be non-rabid with the fluorescent-antibody technique showed structures indistinguishable from Lyssa or Negri bodies. Neither histological examination nor inoculation of animals with non-rabid Seller-positive material explained the nature of these rabies-like structures. The simplicity and reliability of the fluorescent-antibody technique and the occasional serious complications of prophylactic anti-rabies measures make the diagnostic use of Seller's method at best undesirable and at worst dangerous.

Animals↗
PubMedDate not supplied

Maternal alloimmunization in rat pregnancy: in vivo and in vitro studies of T-cell-dependent immunity to mating and third party alloantigens.

Rat pregnancy, experimental pseudopregnancy, and experimental decidua induction promote skin allograft survival of paternal and unrelated skin donors by specific and nonspecific mechanisms. Experimental pseudopregnant females were given allogeneic cells by two routes: intraperitoneal (IP) and in utero (IU). The females injected by the IU route, with allosensitized spleen cells, tolerated paternal skin allografts (average 26 days) better than those from other experimental groups and even from allopregnant females bearing a paternal allograft. The orthotopic immunization by the IU route, as shown by an enhancing effect of in utero culture medium injection, seemed important. In vitro studies revealed that the ability of subscapular lymph node (SCLN) cells draining the allograft to destroy Wistar/Furth (W/Fu) target cells decreases markedly in parallel with prolongation of skin allograft survival. Suppression of lymphocyte-mediated cytotoxicity against W/Fu target cells exceeded 70% when SCLN cells were used as responder cells. We propose that maternal T-cell immunization (via in utero) against fetal antigens occurs in pregnancy and plays a role in maintaining fetal tolerance, while specific cell-mediated cytotoxicity is impaired. Both specific and nonspecific local factors may promote such an enhancement of allograft survival.

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