PubMed Health⌕ Search

Biomedical subjects

A M Omar

Publications and source records attributed to A M Omar.

At least 19 recordsLinked to original sources
PubMed2004

Assessing the benefits of "gaze-down" display location in complex tasks.

BACKGROUND: Location of the image display is one of several factors that influence perceptual processing and endoscopic manipulation in minimal access surgery. Previous studies have proved the benefits of the gaze-down stance, as compared with the conventional gaze-up stance. This study investigates the effect of the gaze-down stance on the performance of a task with varying manipulative and perceptual demands. METHODS: The participants in this study were 20 medical students. Each student performed endoscopic touching tasks under standard conditions using the Dundee Projection System (DPS) display, positioned to provide gaze-up and gaze-down stances. To increase task complexity, two kinds of manual coordination (unilateral vs bilateral) and three endoscope positions (different positions of misalignment) were used. The outcome measures were task execution time and number of errors. RESULTS: Overall, the gaze-down stance reduced time and errors, as compared with the gaze-up display. However, the benefit obtained from the gaze-down stance was more significant in the more difficult tasks (bilateral task and 90 degrees misalignments). CONCLUSIONS: The gaze-down stance reduces task time and errors, as compared with a gaze-up stance. The reduction in time and errors is more appreciable as task complexity increases.

Laparoscopy↗
PubMed2004

Laparoscopic radical prostatectomy a review of the literature and comparison with open techniques.

BACKGROUND: The development of laparoscopic radical prostatectomy (LRP) has been one of the surgical advances in the treatment of localized prostate cancer. The procedure aims to combine the advantages of minimal access surgery with resection based on established oncological principles with cure rates and functional results that are at least comparable to open radical prostatectomy (ORP). OBJECTIVES: This review compares the advantages and disadvantages of the LRP to the ORP with regard to the real benefits to the patient. The impact on the urological practice was also addressed by the review. METHODS: A comprehensive literature review of the published series/cases of both open and laparoscopic radical prostatectomy was performed. RESULTS: LRP is a feasible and reproducible procedure for the treatment of localized prostate cancer. Although its technique is standardized, LRP is technically demanding and it takes longer time than ORP. CONCLUSION: The current published results of LRP show no advantages over that of the ORP. If long-term data shows better results in terms of functional and oncological outcomes, LRP may challenge or even replace the standard ORP in the treatment of localized prostate cancer.

Humans↗
PubMed1999

Novel triazolo[4,3-a]quinazolinone and bis-triazolo[4,3-a:4,3'-c]quinazolines: synthesis and antitoxoplasmosis effect.

Several quinazoline derivatives containing substituted thiosemicarbazido and S-methylisothiosemicarbazido groups at the 2-position and at both the 2- and 4-positions have been synthesized. Treatment of the S-methylthiosemicarbazides with morpholine or diethylamine did not give the corresponding guanidines. Instead, they underwent cyclodesulfurization into the condensed ring systems, [1,2,4]triazolo[4,3-a]quinazolinones and bis-[1,2,4]triazolo[4,3-a:4'.3'-c]quinazolines. Evaluation of the products for antitoxoplasmosis effect by studying the ultrastructure morphology of the organisms using scanning electron microscopy (SEM) indicated their efficacy in causing structural deformity of Toxoplasma gondii. Such a deformity plays an important role in obstructing the entry of the organisms into host cells.

Animals↗
PubMed1999

Phylogenetic characterization of novel transport protein families revealed by genome analyses.

As a result of recent genome sequencing projects as well as detailed biochemical, molecular genetic and physiological experimentation on representative transport proteins, we have come to realize that all organisms possess an extensive but limited array of transport protein types that allow the uptake of nutrients and excretion of toxic substances. These proteins fall into phylogenetic families that presumably reflect their evolutionary histories. Some of these families are restricted to a single phylogenetic group of organisms and may have arisen recently in evolutionary time while others are found ubiquitously and may be ancient. In this study we conduct systematic phylogenetic analyses of 26 families of transport systems that either had not been characterized previously or were in need of updating. Among the families analyzed are some that are bacterial-specific, others that are eukaryotic-specific, and others that are ubiquitous. They can function by either a channel-type or a carrier-type mechanism, and in the latter case, they are frequently energized by coupling solute transport to the flux of an ion down its electrochemical gradient. We tabulate the currently sequenced members of the 26 families analyzed, describe the properties of these families, and present partial multiple alignments, signature sequences and phylogenetic trees for them all.

Amino Acid Sequence↗
PubMed1997

Synthesis, estrogen receptor binding affinity and biological evaluation of some 2-substituted estrone derivatives.

This report details the preparation of modified estrogens which are structurally designed to possess estrogenic and/or antiestrogenic activity. The prominent feature of these estrogens is the introduction of a novel side chain in the 2-position of ring A of the steroid nucleus. Their synthesis includes the use of transformations based upon Mannich base chemistry: preparation of the intermediate 2-dimethylamino-methylestrone via aminomethylation of estrone and introduction of various functionalities via reaction of this Mannich base with different reagents. When evaluated for their interaction with the estrogen receptor by competitive binding assays, the tested products were found to be relatively weak competitors at 0 degree C. The uterotrophic and post-coital antifertility assays indicated effects varying in magnitude relative to estradiol. Ethyl[(2'-acetyl-3'-(3-hydroxyestra-17-oxo-1,3,5 (10)-trien-2-yl)]propionate (15) showed uterotrophic and antiimplantation activities of 95% and 20% respectively.

Animals↗
PubMed1996

Novel steroidal 1,4-diketones and pyridazine derivatives as potential antiestrogens.

A series of steroidal 1,4-diketone derivatives was synthesized by acid-catalyzed condensation of 2-acetylestradiol-17 beta-acetate with substituted phenylglyoxals. Conversion of the products into the corresponding pyridazine derivatives was achieved by reaction with hydrazine hydrate. The synthesized compounds were evaluated for their uterotrophic, antiuterotrophic, and antifertility activities in mature female albino rats. Among the compounds tested, the phenyl 2, p-bromophenyl 3, and p-methoxyphenyl 5 diketone derivatives displayed uterotrophic activity of 72%, 72%, and 91%, respectively. The gradation of antiestrogenic activity was assessed in vivo by the inhibition of the estrone-stimulated uterine growth. Compounds 2-5 showed moderate antiestrogenic activity of 53-56%. None of the tested compounds elicited antifertility activity as assessed by the post-coital antiimplantation activity test.

Animals↗
PubMed1995

Instantaneous lead entrapment: an unusual complication of nonthoracotomy implantation of an endocardial defibrillation lead.

Nonthoracotomy implantation of implantable cardioverter defibrillators is performed with transvenous leads that are similar to pacemaker leads and are subject to the same potential problems. We report an unusual complication of lead placement in which an electrode immediately became entrapped in the superior rim of the tricuspid valve, resisting all efforts at removal.

Aged↗
PubMed1984

Synthesis and biological evaluation of new 2,3-dihydrothiazole derivatives for antimicrobial, antihypertensive, and anticonvulsant activities.

A novel series of 2-arylimino-2,3-dihydrothiazole derivatives, substituted in the 3-position with a beta-phenethyl moiety and the 4-position with substituted aryl functions, was synthesized as potential antimicrobial, antihypertensive and anticonvulsive agents. While no antimicrobial or significant antihypertensive activity was observed for the products, XII, XIII, and XXI displayed potent anticonvulsant activity.

Animals↗
PubMed1984

Synthesis and evaluation of novel N-substituted N'-(3-hydroxy-17-oxoestra-1,3,5(10)-trien-2- and -4-yl)thiourea derivatives for binding to the estrogen receptor and cytotoxic activity on MCF-7 cells.

A novel series of estrone derivatives having a free 3-phenolic group with the 2- or 4-position substituted with a thiourea function was synthesized. None of the products showed significant binding to the estrogen receptor, and the cytotoxic activity on MCF-7 cells for VII and X was weak.

Animals↗
PubMed1983

Steroidal derivatives. Part 4: Synthesis and in vitro anabolic and catabolic properties of a new group of steroidal alkylating agents.

A new group of steroidal alkylating agents has been synthesized for potential anticancer activity. The compounds contain a sulfonic ester, a mono- or a bifunctional nitrogen mustard function attached to an ethyl chain and forming ether linkages at the 3- or 17 beta-position of the steroids selected. The products were tested for their in vitro anabolic and catabolic properties by measuring their effects on the bovine pancreatic ribonuclease.

Alkylating Agents↗
PubMed1983

Steroidal thiourea and thiazoline derivatives: synthesis and in vitro effects on bovine pancreatic ribonuclease activity.

Two novel series of steroidal derivatives containing various thiourea and substituted thiazoline moieties attached to the 2- or 4-position of estrone were synthesized and examined for in vitro effect on bovine pancreatic ribonuclease activity. All compounds studied exhibited a catabolic activity. The steroidal thiazoline derivatives were more potent activators of ribonuclease than the steroidal thioureas.

Animals↗