Showing papers by "King Saud University published in 1998"

Ischaemia-reperfusion injury: Implications for the hand surgeon

Abstract: Prolonged ischaemia sometimes occurs in replantation and free flap surgery. The re-establishment of circulatory flow to the ischaemic tissue leads to a cascade of events which augments tissue necrosis. This paper reviews the pathophysiology of this ischaemia-reperfusion injury and discusses different methods to modulate this injury.

Thymoquinone protects against doxorubicin-induced cardiotoxicity without compromising its antitumor activity

Abstract: Doxorubicin (DOX) has a wide spectrum of antitumor activity with dose-related cardiotoxicity as a major side effect. This cardiotoxicity has been suggested to result from the generation of oxygen-free radicals. The objective of the present study was to investigate the influence of the antioxidant, thymoquinone (TQ) on cardiotoxicity and antitumor activity of DOX in mice. TQ (8 mg/kg/day, p.o.) administered with drinking water starting 5 days before a single i.p. injection of DOX (20 mg/kg) and continuing during the experimental period ameliorated the DOX-induced cardiotoxicity in mice. This finding was evidenced by significant reductions in serum lactate dehydrogenase and creatine kinase elevated levels and further supplemented by histopathological examination of cardiac tissue. TQ did not alter the plasma and heart DOX levels as monitored by fluorometric analysis. In in vivo study on mouse Ehrlich ascites carcinoma tumor, it could then be shown that TQ does not interfere with the antitumor activity of DOX. The current data support TQ as a potentially selective cytoprotective agent, which may ameliorate cardiotoxicity without decreasing DOX antitumor activity.

Acute and subchronic toxicity of thymoquinone in mice

Abstract: The effects of acute and subchronic administration of thymoquinone (TQ), the main constituent of the volatile oil of the black seeds Nigella sativa, with significant cytoprotective properties, were studied in male Swiss albino mice. After acute oral administration, the LD50 value (95% CL) was 2.4 g/kg (1.52–3.77). Signs of toxicity at high doses were hypoactivity and difficulty in respiration. Twenty-four hours after TQ (2 and 3 g/kg) administration, a significant reduction in tissue (liver, kidneys, and heart) reduced glutathione (GSH) content was observed. Plasma urea and creatinine concentrations and the enzyme activities of alanine amino transferase (ALT), lactate dehydrogenase (LDH), and creatine phosphokinase (CPK) were significantly increased. In the subchronic study, mice received TQ in drinking water at concentrations of 0.01, 0.02, and 0.03% for 90 days with no resulting mortality or signs of toxicity. The average daily intake of the compound was approximately 30, 60, or 90 mg/kg/day. There were no changes of toxicological significance in body and organ weights, food and water intake, or urine and feces output. Tissue GSH, plasma concentrations of TP, urea, creatinine and triglycerides, and enzyme activities of ALT, LDH, and CPK were also not affected. Histological examination revealed no gross or microscopic tissue damage. TQ, however, produced a significant decrease in fasting plasma glucose level. The results indicate that the acute oral toxicity of TQ in mice is of a low order and it is generally well tolerated when given subchronically at doses previously shown to have cytoprotective activity. Drug Dev. Res. 44:56–61, 1998. © 1998 Wiley-Liss, Inc.

Prenatal nicotine exposure modifies behavior of mice through early development.

Abstract: Studies in humans and animal models (including rodents) have revealed lasting behavioral and cognitive impairments in offspring prenatally exposed to nicotine. Offspring of pregnant mouse dams prenatally subjected to 9-10 daily subcutaneous injections into the nape of the neck during pregnancy have been postnatally subjected to several developmental and behavioral tests to investigate the effects of prenatal nicotine exposure on those offspring at various stages of their life. The prenatal exposure to nicotine has resulted in significant reduced postnatal body weight gain, as well as in significant delay in eye opening, in the appearance of body hairs, and in sensory motor reflexes. However, motor activity was significantly stimulated in early adulthood of mouse pups prenatally exposed to nicotine, and such exposure proved to have long-lasting hyperactive effects on mice. Thus, exposure to nicotine during a critical prenatal period of brain development deduced from the present study in mice raises the alarm of the possible hazard of prenatal exposure to nicotine in humans. Hence, smoking by pregnant women might constitute a serious hazard to their in utero developing children.

Stroke Register: Experience from the Eastern Province of Saudi Arabia

Abstract: A stroke registry was established in the Eastern Province of Saudi Arabia with an estimated population of 750,000 inhabitants of whom 545,000 are Saudi citizens The register started in July 1989 and

Radiographic study of the mental foramen in a selected Saudi population.

Abstract: OBJECTIVES To determine the most common position of the mental foramen in a selected Saudi population and to compare the results with those reported for other populations. METHODS Four hundred and fourteen panoramic radiographs of a Saudi population from four different dental centres were studied. RESULTS The commonest position of the mental foramen was in line with the longitudinal axis of the second premolar (45.3%) followed closely by location between the first and second premolars (42.7%). The mental foramen was symmetrical in 80% of patients. CONCLUSION Clinicians should expect to find the position of the mental foramen to be symmetrical and in line with the second premolar teeth.

Laminar mixed convection from a continuously moving vertical surface with suction or injection

Abstract: The boundary layer flow over a uniformly moving vertical surface with suction or injection is studied when the buoyancy forces assist or oppose the flow. Similarity solutions are obtained for the boundary layer equations subject to power law temperature and velocity boundary conditions. The effect is of various governing parameters, such as Prandtl number Pr, temperature exponent n, injection parameter d, and the mixed convection parameter λ=Gr/Re2, which determine the velocity and temperature distributions and the heat transfer coefficient, are studied. The heat transfer coefficient increases as λ assisting the flow for all d at Pr=0.72 however, for n=−1 it decreases sharply with λ. On the other hand, increasing λ has no effect on heat transfer coefficient for Pr=10 at n=0, and 1 for almost all values of d studied. However, for n=−1 it has similar effect as for Pr=0.72. It is also found that Nusselt number increases as n increases for fixed λ and d.

Repair of acrylic resin denture base reinforced with glass fiber.

Abstract: Statement of problem. The ultimate goal of any denture repair is to restore the original strength of the denture and to avoid further fracture. Purpose. This study investigated the strength and deflection of repaired acrylic resin joints reinforced with various glass fiber concentrations. Material And Methods. Transverse strength, maximum deflection, and modulus of elasticity of glass fiber-reinforced polymethyl methacrylate acrylic resin were studied with a 3-point load test on 54 intact specimens. Six concentrations of type B glass fiber specimens were prepared (n = 9 per each fiber group). Fractured joint margins were rounded, a 2-mm gap was placed between them, and then they were repaired with autopolymerizing acrylic resin and retested. Results. Transverse strength, maximum deflection, and the stiffness of all joints were significantly lower after the repair. Among the groups tested, the units treated with 1% glass fiber displayed the highest transverse strength before and after repair. Modulus of elasticity of the repaired 1% fiber concentration units was enhanced by approximately 25% over those repaired but untreated with glass fiber (0% fiber). (J Prosthet Dent 1998;80:546-50.)

Flexural behaviour of concrete beams reinforced with gfrp bars

Abstract: This study presents the results of the comparison made between the predicted and the measured load-deflection relationships for 12 concrete beams reinforced either by steel or glass fibre reinforced plastic (GFRP) bars. The numerical part of the study was carried out using: (i) the computer model which accounts for the actual properties of the composite constituents developed as part of this study, (ii) the ACI load-deflection model, and (iii) the modified load-deflection model available in the literature for beams reinforced by FRP bars. The last two models were implemented on a spreadsheet. The deflection limit and the ultimate strength of concrete were the control parameters in design of the test beams. The computer model provides an accurate prediction of the measured service and full load-deflection curves. The errors in prediction of service load deflection and ultimate flexural strength are less than 10% and 1%, respectively. In the case of GFRP reinforced beams, the service load deflection predicted by the ACI model is in error by 70%, while that predicted by the modified model is in error by less than 15%.

Lithospheric seismic velocity discontinuities beneath the Arabian Shield

Abstract: We determined crustal and lithospheric mantle velocity structure beneath the Arabian Shield through the modeling of receiver function stacks obtained from teleseismic P waves recorded by the 9 station temporary broadband array in western Saudi Arabia. The receiver function deconvolution technique was used to isolate the receiver-side PS mode conversions. A grid search method, which should yield an unbiased global minimum, was used to solve for a shear wave velocity model that is optimal and has the minimum number of layers needed to fit the receiver function waveform. Results from this analysis show that the crustal thickness in the shield area varies from 35 to 40 km in the west, adjacent to the Red Sea, to 45 km in central Arabia. Stability tests of each solution indicate that the models are relatively well constrained. We have also observed evidence for a large positive velocity contrast at sub-Moho depths at four stations at depths of 80 to 100 km. This discontinuity may represent a change in rheology in the lower part of the lithosphere or remnant structure from the formation of the Arabian Shield.

Caries prediction model in pre‐school children in Riyadh, Saudi Arabia

Abstract: Objectives. To evaluate the significance of variables such as oral hygiene, dietary habits, socio-economic status and medical history of a child in assessing the level of caries risk and to generate a caries prediction model for pre-school Saudi children. Design. Cross-sectional study of pre-school children. Setting. Clinics and schools in Riyadh, Saudi Arabia. Sample and methods. A sample of 446 Saudi pre-school children, 199 males and 247 females, with a mean age of 4·13 years, were selected at random from clinics and schools. Selection was limited to subjects who either had no caries (dmft= 0) or who had high caries experience (dmft > 8). Each child was examined for caries experience and oral hygiene status. Their mothers were interviewed through a standardized questionnaire for information about oral hygiene habits of the children, diet history, childhood illness and socio-economic status. Results. There was a highly significant difference between the two groups in: debris index (P<0.0001), age child started tooth brushing, (P<0·0001), age breastfeeding was stopped (P<0·005), nocturnal bottle feeding with milk formula (P<0·0001), use of sweetened milk (P<0·0001), frequency of use of soft drinks (P<0·0005), frequency of consumption of sweets (P<0·0001), and age at first dental visit (P<0·0001). A caries prediction model developed through stepwise multivariate Logistic Regression (LR) analyses showed debris index, use of sweetened milk in bottle, frequency of consumption of soft drinks, frequency of intake of sweets and child’s age at the first dental visit to be significant. Predictive probability of the model was 86·31% with a sensitivity of 90·1% and a specificity of 80·6%. Conclusions. Risk factors for dental caries have been identified and a caries prediction model has been developed for Saudi pre–school children. The prediction model, if verified, may provide dentists with guidance in identifying high caries risk Saudi pre-school children as targets for preventive programmes

Artemisinin-derived sesquiterpene lactones as potential antitumour compounds: cytotoxic action against bone marrow and tumour cells.

Abstract: We determined the in vitro cytotoxic activity of the sesquiterpene lactone endoperoxide artemisinin (1) and some chemically prepared derivatives, which have been found to display cytotoxicity to cloned murine Ehrlich ascites tumour (EAT) cells and human HeLa cells and against murine bone marrow using a clonogenic assay for committed progenitor cells of the granulocyte-monocyte lineage (CFU-GM assay). Comparing artemisinin (1) to deoxyartemisinin (2), the endoperoxide group appeared to play a role in cytotoxicity to CFU-GM cells. Dimers of dihydroartemisinin and dihydrodeoxyartemisinin revealed that the stereochemistry of the ether linkage of the dimers was a more important determinant for this cytotoxic activity. The nonsymmetrical dimer of dihydroartemisinin (3) and the corresponding endoperoxide-lacking dimer of dihydrodeoxyartemisinin (5) were equally cytotoxic to CFU-GM cells. Despite the differences between both systems, it may be stated that most compounds displayed higher cytotoxicity to CFU-GM cells than to EAT cells. Dimers of dihydroartemisinin (3, 4) were selected as potential antitumour compounds and subjected to the National Cancer Institute drug-screening programme consisting of about sixty human cancer cell lines derived from nine different tissues. Both compounds displayed the same specific cytotoxicity pattern. Throughout the screen dimer 3 was more active than 4.

Note: The economic manufacturing lot-sizing problem with imperfect production processes: Bounds and optimal solutions

Abstract: In this paper, we consider the economic production quantity problem in the presence of imperfect processes. In the literature, the time to shift from the in-control state to the out-of-control state is assumed to be exponentially distributed. In this study, we consider general time to shift distributions and provide distribution-based and distribution-free bounds on the optimal cost. For the exponential case, we compare the optimal solutions to approximate solutions proposed in the literature. A numerical example is used to illustrate the analysis presented and to conduct a sensitivity analysis in order to see the effect of the input parameters on the various solutions to the problem. © 1998 John Wiley & Sons, Inc. Naval Research Logistics 45: 423–433, 1998

Compositional analysis and depth profile studies on undoped and doped tin oxide films prepared by spray technique

Abstract: Tin oxide (TO) and fluorine doped tin oxide (FTO) thin films of different thicknesses and varying impurity concentrations have been prepared by spray technique. The XRD results are in good agreement with ASTM data. From the XPS (X-ray photoelectron spectroscopy) studies, the presence of tin and oxygen in tin oxide has been confirmed and also the ratio of Sn/O has been found out. Chemical analysis of FTO films has been carried out by SAM (Scanning Auger Microprobe) studies and from the peak to peak height (PPH) calculations, Sn, O and F concentrations have been determined. The compositional analysis of FTO films at different depths (depth propfiles) has been studied. The results have been explained.

Vogt‐Koyanagi‐Harada syndrome in children compared to adults

Abstract: Purpose To study the course and visual outcome of Vogt-Koyanagi-Harada (VKH) syndrome in children. Methods The medical records of 97 consecutive patients with VKH syndrome were reviewed. Patients had been seen at King Khaled Eye Specialist Hospital in Riyadh, Saudi Arabia. The records were divided into two groups: those in whom the onset of the disease occurred at the age of 14 years or younger (pediatric group) and those in whom the disease manifested after the age of 14 years (adult group). Results Eight (61%) of the 13 children required cataract surgery compared to 14(17%) of 84 adult patients. Despite medical and surgical therapy, eight (61%) of the pediatric group had a final visual acuity of 20/200 or worse compared with 22 (26%) of the 84 adult patients (p=0.0103). Conclusion The course of early-onset VKH (before the age of 14 years) appears to be aggressive. The ocular complications are more severe in children than in adults, leading to rapid deterioration in vision. Despite therapy, the final visual outcome of VKH in children is poor.

Effect of glass fiber reinforcement on some mechanical properties of autopolymerizing polymethyl methacrylate.

Abstract: Purpose. This study investigated the different effects of quantitative percentages of glass fiber intensity on the transverse strength, maximum deformation, and the modulus of elasticity of acrylic resin. Materials and methods. Fifty-four specimens were formed in a specially designed mold to produce identical specimens in accordance with the manufacturer's recommendations. Six percentages of glass fiber reinforcement in loose random form were studied. Each glass fiber treatment percentage (0%, 1%, 2%, 5%, 10%, 15%) was related to the total powder/liquid mass. Results. The results indicated that 1% glass fiber treatment enhanced the transverse strength of the tested specimen. Maximum deformation at failure in the tested treatment groups was found to be different. The interaction of glass fiber concentration on fracture strength and deformation was significant ( p Conclusion. The 1% glass fiber concentration was found to give the best fracture strength and deformation results. Significantly higher glass fiber percentages was found to weaken the resin. (J Prosthet Dent 1998;79:580-4.)

Genetic Background of Congenital Chloride Diarrhea in High-Incidence Populations: Finland, Poland, and Saudi Arabia and Kuwait

Abstract: Congenital chloride diarrhea (CLD) is an inherited intestinal disorder caused by mutations in the down-regulated in adenoma gene. In Finland, the disease is prevalent because of a founder effect, and all but one of the CLD-associated chromosomes carry the same mutation, V317del. In Poland, another area with a high incidence of CLD, as many as seven different mutations have been detected so far. A third known cluster of CLD, around the Persian Gulf, has not been genetically studied. We studied the allelic diversity of CLD in Poland, in Saudi Arabia and Kuwait, and in three isolated families from North America and Hong Kong. Altogether, eight novel mutations were identified, making a total of 19 known CLD gene mutations. The Polish major mutation I675-676ins was found in 47% of the Polish CLD-associated chromosomes. Haplotype analysis and clustering of the I675-676ins mutation supported a founder effect and common ancestral origin. As in Finland, a major founder effect was observed in Arab patients: 94% of the CLD-associated chromosomes carried a nonsense mutation, G187X, which occurred in either a conserved ancestral haplotype or its derivative. Our data confirm that the same locus is mutated in all cases of CLD studied so far. In Poland, a relatively common founder mutation is likely to highlight a set of rare mutations that would very rarely produce homozygosity alone. This suggests that mutations in the CLD locus are not rare events. Although the disease is thought to be rare, undiagnosed patients may not be uncommon.

Some rare presentations of hydatid cyst (Echinococcus granulosus).

Abstract: Among all the cases of hydatid disease seen in an 8-year period at Asir Central Hospital, Abha, Saudi Arabia, seven cases are reported here because of their unusual presentations. One patient had a brain hydatid cyst which presented as a space-occupying lesion. The second patient presented with symptoms and signs of cardiac tamponade due to pericardial hydatidosis. The third female had multiple abdominal and pelvic hydatid cysts causing vague abdominal pain, chronic ill-health and primary infertility. The fourth case was a huge single hydatid cyst filling the whole abdominal cavity and involving multiple organs. The fifth case presented with simultaneous involvement of the liver, right diaphragm and pleura with hydatidosis. The sixth case involved the left diaphragm and the patient presented with clinical picture simulating pleurisy. The last patient presented with a hydatid cyst of the right thigh. Even though there was no mortality in these patients, there was disabling morbidity. We conclude that Echinococcus granulosus can affect any organ in the body and a high suspicion of this disease is justified in endemic regions. Moreover, medical treatment should precede and follow the surgical intervention.

Risk factors for diabetic retinopathy among Saudi diabetics.

Abstract: Purpose: To describe the incidence of, and risk factors associated with, diabetic retinopathy in diabetic persons assessed at a Saudi diabetes centre. Methods: Five hundred and two patients with diabetes mellitus assessed by our service were studied. There were 174 patients (34.7%) with insulin-dependent diabetes mellitus (IDDM) and 328 patients (65.3%) with non-insulin-dependent diabetes mellitus (NIDDM). Results: The incidence of retinopathy was 157/502 (31.3%). The incidence was 42.5% in patients with IDDM and 25.3% in those with NIDDM. By logistic regression analysis, it was shown that old age (>60 years), insulin use, long duration of diabetes (>10 years), poor diabetes control, and the presence of nephropathy were significantly associated with the incidence of retinopathy. On the basis of the magnitudes of the regression coefficients in the hazard function, long duration of diabetes was the most important independent risk factor for the development of retinopathy; the presence of nephropathy, age >60 years, poor diabetes control, and use of insulin were less important (regression coefficients: 1.9, 1.71, 1.331, 0.8508 and 0.6178, respectively). The incidence of macular oedema was significantly associated with the presence of hypertension and high cholesterol levels in patients with IDDM. Polycotomous regression analysis showed that the presence of nephropathy was the only factor significantly associated with the severity of retinopathy. Conclusions: The significant associations with poor control and duration of diabetes provide further strong evidence for the benefits of optimal glycaemic control. Other potentially modifiable risk factors for retinopathy may be important, including elevated blood pressure and serum cholesterol.

Captopril ameliorates myocardial and hematological toxicities induced by adriamycin

Abstract: Adriamycin has a wide spectrum of antitumor activity with dose related cardiotoxicity as a major side effect. The objective of this study was to investigate the influence of captopril, a sulphydryl containing angiotensin converting enzyme inhibitor, on the cardio- and hematotoxicity of adriamycin in normal rats. A single dose of adriamycin (15 mg/kg) caused myocardial toxicity after 24 h manifested biochemically by elevation of serum enzymes:- Aspartate transaminase (AST, EC: 2.6.1.1), lactate dehydrogenase (LDH, EC: 1.1.1.27), creatine phosphokinase (CPK, EC: 2.7.3.2) and the cardiac iso-enzymes of LDH and CPK. The hematotoxicity was characterized by severe leukopenia and anemia that appeared after 72 h of adriamycin administration. Captopril (60 mg/kg i.p.) 1 h before adriamycin injection ameliorated the biochemical toxicity induced by adriamycin. This was evidenced by a significant reduction in serum enzymes, after 24 and 48 h and a significant reduction of serum cardiac iso-enzymes after 48 h. Also restoration of the white blood cell counts as well as hemoglobin concentration occurred after 72 h of captopril administration. These results suggest that captopril may be benificial as a protective agent against cardio- and hematotoxicity induced by adriamycin.