PubMed Health⌕ Search

Biomedical subjects

A Mahmoud

Publications and source records attributed to A Mahmoud.

44 records · Page 3Linked to original sources
PubMed1986

Isolation of cDNA clones for differentially expressed genes of the human parasite Schistosoma mansoni.

Little is known about the mechanisms that control transformations during the life cycle of Schistosoma mansoni. To enable isolation of DNA sequences encoding developmentally regulated antigens a cDNA expression library in the vector lambda gt11 amp3 was constructed from adult mRNA and immunologically screened with sera from infected individuals. We report here on the properties of three recombinant clones that derive from developmentally regulated genes. Clone 10-3 encoded a beta-galactosidase fusion protein present in high abundance in infected Escherichia coli. Clones 7-2 and 8-2 also produced immunologically recognized proteins; however, the peptides did not appear to be beta-galactosidase fusion proteins. The expression of mRNAs hybridizing to these cDNAs was examined in the different stages of the parasite life cycle. Messenger RNA corresponding to clone 10-3, approximately equal to 1000 bases in length, was present in higher abundance in male worms than in females but was not detected in schistosome eggs. A 900-base mRNA hybridizing to clone 7-2 was observed in adult worms and eggs. Both clone 10-3 and clone 7-2 hybridized to smaller mRNAs in cercariae and freshly transformed schistosomula than in adult worms. Clone 8-2 contained tandem cDNA inserts. One cDNA hybridized to a 1700-base mRNA present in all stages, while the second hybridized to an 800-base mRNA specific to adult female worms.

Animals↗
PubMed1986

Effect of murine schistosomiasis on hepatic cytochrome P-450 and microsomal protein.

Experimental hepatic schistosomiasis was produced in CBA mice using a local strain of S. mansoni. A comparative study of the hepatic concentrations of cytochrome P-450 and microsomal protein in the control and infected animals was carried out. S. mansoni infection significantly (P less than 0.05) reduced the liver cytochrome P-450 and microsomal protein. This suggests impairment of drug metabolism in the liver of infected animals. The study calls attention to the possible clinical and pharmacokinetic implications of the late severe S. mansoni infection of the liver in man.

Animals↗
PubMedDate not supplied

Axial vibration of threaded external fixation pins: detection of pin loosening.

The hypothesis of this study was that a nondestructive vibrational method could detect bone lysis at the external fixation pin-bone interface prior to current clinical and radiographic methods. In vitro models were used to simulate changes observed during pin loosening in vivo. Fixation pin axial natural frequency decreased with decreasing tensile modulus of the material into which it was implanted. In a live animal study the right tibia of 12 dogs was fractured and stabilized with a four-pin unilateral external fixation frame. The axial natural frequency of each pin was measured and radiographs were taken at 0, 2, 4, 6, 8, and 10 weeks after surgery. The natural frequency did not change when the first radiographic changes around the interface were observed. Pins were palpably stable at this point. As loosening progressed, the natural frequency did decrease. Frequency and quasistatic tests of dissected pin-bone structures revealed a good correlation between natural frequency and pin-bone interface stiffness. In addition, the measurement of natural frequency was more sensitive to bone structure changes at the pin-bone interface than low-load quasi-static stiffness. Therefore, a nondestructive vibration technique could be used instead of low-load quasistatic tests for assessing the pin-bone interface ex. vivo.

Animals↗
PubMedDate not supplied

Cutaneous estradiol permeation, penetration and metabolism in pig and man.

AIM AND METHODS: Drug development in dermatotherapy and also development of transdermal therapeutic systems (TTS) demand high-predictive in vitro models to estimate drug levels in skin and systemic uptake. Here we compare three ready-to-use models, reconstructed human epidermis, split porcine skin and the perfused porcine forelimb. 17beta-Estradiol (E(2)), which is highly metabolized by skin cells, serves as model drug since E(2) application is of high relevance in hormone replacement therapy while topical E(2) may promote wound healing. E(2) TTS, gel and an ethanolic solution were investigated for cutaneous penetration, permeation and metabolism. RESULTS: E(2) TTS enabled an E(2) uptake of 42.9% of the applied dose accompanied by a high percentage of E(2) metabolism (30% of the penetrated dose) in the perfused porcine forelimb. In Franz cell experiments with reconstructed human epidermis and split porcine skin, the gel allowed an E(2) uptake of 41.7 and 22.9% of the applied dose accompanied by a high E(2) metabolism (42.6 and 28.6% of the penetrated dose). Due to toxic effects of the vehicle, this was not true with an ethanolic solution, then E(2) permeation and metabolism were clearly diminished. Most importantly, the in vitro models proved to be predictive with respect to the E(2)/estrone ratio in female plasma under transdermal hormone replacement therapy. CONCLUSION: In vitro tests should reduce the need for both animal and human studies for cutaneous uptake and metabolism in the future.

Administration, Cutaneous↗
PubMedDate not supplied

A comparative study of propolis and saline application on human dentin. A SEM study.

The purpose of this study was to compare the texture changes of dentinal surfaces after the application of propolis and saline. Twenty-four recently extracted human premolar teeth were obtained from the Division of Oral and Maxillofacial Surgery, King Saud University, College of Dentistry, Riyadh. The teeth were classified as sound, periodontally involved and with recession. Forty-eight, 3 x 3 mm dentin disc specimens were prepared and only 24 specimens were treated with propolis (pH 8.5) and saline (pH 6). They were treated in 4 categories i.e.: (1) no application of any material (control); (2) propolis for 60 seconds; (3) propolis for 120 seconds and (4) saline for 60 seconds. All experimental specimens were burnished with cotton pellet with propolis and saline for the prescribed time. All specimens were prepared for scanning electron microscopy (SEM) with sputter technique, (Blomlof and Lindskog, 1995), and examined in the SEM (Jeol, Japan) operated at 25 KV with a tilt angle between 0-30 degrees. The bar was 10 mm and magnification 2000x. There were dentinal tubules occlusion in all three groups of dentin treated with propolis for 120 seconds. The propolis was better than saline in occluding dentinal tubules. It may be suggested that further research is needed for double blind clinical trials of propolis in patients with dentinal hypersensitivity.

Dentin↗
PubMedDate not supplied

Is there a relationship between subclinical myocardial abnormalities, conduction defects and Ro/La antibodies in adults with systemic lupus erythematosus?

Thirty-three adult patients with systemic lupus erythematosus (SLE) were studied to determine whether there was an association between subclinical abnormalities of left ventricular function, conduction defects, and the presence of antibodies to Ro and/or La. Twelve patients had one or both of these antibodies. Conduction defects were present in 2, neither being currently positive for Ro or La antibody. There was no difference in abnormalities of left ventricular function between those with or without antibody. Valvular abnormalities were present in 11, 6 of whom had focal or diffuse thickening of one or more valves. Adults with SLE and anti-Ro and/or La antibody do not appear to be at particular risk of conduction defects. Subclinical left ventricular functional abnormalities were not associated with the presence of these antibodies.

Adult↗