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The present study carried out on fruitful Washington Navel orange trees 12 years old, budded on sour orange rootstock grown in clay loamy soils in private farm at Toukh region, El-Kalubeia Governorate to evaluate response the trees productivity to foliar spray with some stimulating compounds at two concentrations for each i.e., yeast extract at 2.50 ml/l & 5.0 ml/l, sea weeds at 0.2 &0.4 ml/l, promalin at 100 & 200 ppm and humic acid at 3.0 & 6.0 g/l and mixture of lower concentration of each substance, beside control which sprayed with tap water during 2019 and 2020 seasons. The results indicated that, treatments significantly increased yield indicators and improved fruit quality compared to control. Promalin at 200ppm or yeast extract at 2.5 m/L+ sea weeds extract at 0.2m/L + promalin at 100 ppm gave highest values of yield measurements and fruit quality. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) contamination in the soil potentially hampers microbial biomass and adversely affects their services such as decomposition and mineralization of organic matter. It can reduce nitrogen (N) metabolism and consequently affect plant growth and physiology. Further, Cd accumulation in plants can pose health risks through vegetable consumption. Here, we investigated consequences of Cd contamination on fertilizer value and associated health risks following the application of biogas residues (BGR) to various soil types. Our results indicate that the application of BGR to all soil types significantly increased dry matter (DM) yield and N uptake. However, the Cd contamination negatively affected DM yield and N recovery from BGR in a dose-dependent manner. Organic N mineralization from BGR also decreased in Cd-contaminated soils. The highest DM yield and N recovery were recorded in sandy soil, whereas the lowest values were observed in clay soil. Cadmium was accumulated in spinach, and health risk index (HRI) associated with its dietary intake revealed that consuming spinach grown in Cd-contaminated soil, with or without BGR, is unsafe. Among the soil types, values of daily intake of metals (DIM) and HRI were lowest in clay soil and highest in sandy soil. However, the application of BGR curtailed HRI across all soil types. Notably, the application of BGR alone resulted in HRI values < 1, which are under the safe limit. We conclude that soil contamination with Cd reduces fertilizer value and entails implications for human health. However, the application of BGR to the soil can decrease Cd effects.

With the development of MXene as the efficient adsorbent for U(VI), the tendency of MXene coming into contact with U(VI) in wastewaters increases. Motivated by UV light irradiation applied in wastewater treatments, the UV light induced photochemical co-transformation of Ti 3 C 2 T x MXene and U(VI) is studied. To clarify the role of U(VI) induced Ti 3 C 2 T x aggregation in phototransformation of Ti 3 C 2 T x , the aggregation kinetics of Ti 3 C 2 T x in the presence of various valent radioactive ions are investigated, obtaining the critical coagulation concentrations (CCC) of Ti 3 C 2 T x for Cs + , Sr 2+ , UO 2 2+ , Eu 3+ , and Th 4+ . Besides, the colloidal stability of UV-induced Ti 3 C 2 T x as a function of standing time is discussed. The results show that the aggregation behavior of Ti 3 C 2 T x induced by radioactive ions follows the classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory and the Schulze-Hardy rule. The UV irradiation will change the physicochemical properties and colloidal stabilities of Ti 3 C 2 T x . Furthermore, the degradation of Ti 3 C 2 T x can be accelerated by UV irradiation and further promoted by the presence of U(VI). The removal of U(VI) is highest in the case of Ti 3 C 2 T x combined with UV irradiation via adsorption and reduction. This study provides an example demonstrating that the simultaneous transformation of Ti 3 C 2 T x (adsorbent) and U(VI) (adsorbate) to mild toxic components., (Copyright © 2022 Elsevier B.V. All rights reserved.)

An Egyptian rhizobacterium Azospirillum sp. isolated from Sadat city was able to produce indole acetic acid (IAA) up to (30.59 µg/ml). The isolate was identified biochemically and by 16S rRNA sequencing which showed 99.9% similarity to Azospirillum brasilense. The new isolate has been registered in Genbank with accession number MH179119.1. Extracted IAA was used as reducing or stabilizing agent of sliver nanoparticles (AgNPs). Successful fabrication of biogenic IAA-AgNPs was confirmed by Fourier Transform Infrared Spectrophotometer (FTIR) analysis of IAA which showed absorbance peak at 3434.78 cm -1 due to the N-H stretch of primary amines. Highly resolution Transmission Electron Microscopy (HR-TEM) showed AgNPs coating or capping with IAA in spherical shaped with size ranged from 6.01 to 44.02 nm. Energy dispersive X-ray (EDX) analysis revealed that Ag + ions were attached to the surface of IAA-AgNPs particles. HR-TEM examination showed cell wall damage of Citrobacter freundii cells after exposure to IAA-AgNPs leading to cell death. In vivo results showed that C. freundii infection of rats induced significant increase in liver and kidney functions and deleterious histopathological alteration in rat's tissues. However, treatment by extracted IAA and IAA-AgNPs could normalize the biochemical and histopathological alterations occurred in infected rats. This is the first study to prove that IAA extracted from Azospirillum brasilense is a hopeful capping agent for NPs which has potential to protect against pathogenic infections, nontoxic and/or safe on rat's metabolisms., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Objective: This study was designed to determine the efficacy of ivermectin, an FDA-approved drug, in producing clinical benefits and decreasing the viral load of SARS-CoV-2 among asymptomatic subjects that tested positive for this virus in Lebanon., Methods: A randomized controlled trial was conducted in 100 asymptomatic Lebanese subjects that have tested positive for SARS-CoV2. Fifty patients received standard preventive treatment, mainly supplements, and the experimental group received a single dose (according to body weight) of ivermectin, in addition to the same supplements the control group received., Results: There was no significant difference ( p = 0.06) between Ct-values of the two groups before the regimen was started (day zero), indicating that subjects in both groups had similar viral loads. At 72 h after the regimen started, the increase in Ct-values was dramatically higher in the ivermectin than in the control group. In the ivermectin group, Ct increased from 15.13 ± 2.07 (day zero) to 30.14 ± 6.22 (day three; mean ± SD), compared to the control group, where the Ct values increased only from 14.20 ± 2.48 (day zero) to 18.96 ± 3.26 (day three; mean ± SD). Moreover, more subjects in the control group developed clinical symptoms. Three individuals (6%) required hospitalization, compared to the ivermectin group (0%)., Conclusion: Ivermectin appears to be efficacious in providing clinical benefits in a randomized treatment of asymptomatic SARS-CoV-2-positive subjects, effectively resulting in fewer symptoms, lower viral load and reduced hospital admissions. However, larger-scale trials are warranted for this conclusion to be further cemented.

In the present work, boron nitride (BN) nanosheets were prepared through bulk BN liquid phase exfoliation while various wt. ratios (2.5, 5, 7.5 and 10) of bismuth (Bi) were incorporated as dopant using hydrothermal technique. Our findings exhibit that the optical investigation showed absorption spectra in near UV region. Density functional theory calculations indicate that Bi doping has led to various modifications in the electronic structures of BN nanosheet by inducing new localized gap states around the Fermi level. It was found that bandgap energy decrease with the increase of Bi dopant concentrations. Therefore, in analysis of the calculated absorption spectra, a redshift has been observed in the absorption edges, which is consistent with the experimental observation. Additionally, host and Bi-doped BN nanosheets were assessed for their catalytic and antibacterial potential. Catalytic activity of doped free and doped BN nanosheets was evaluated by assessing their performance in dye reduction/degradation process. Bactericidal activity of Bi-doped BN nanosheets resulted in enhanced efficiency measured at 0-33.8% and 43.4-60% against S. aureus and 0-38.8% and 50.5-85.8% against E. coli, respectively. Furthermore, In silico molecular docking predictions were in good agreement with in-vitro bactericidal activity. Bi-doped BN nanosheets showed good binding score against DHFR of E. coli (- 11.971 kcal/mol) and S. aureus (- 8.526 kcal/mol) while binding score for DNA gyrase from E. coli (- 6.782 kcal/mol) and S. aureus (- 7.819 kcal/mol) suggested these selected enzymes as possible target.

In addition to its canonical functions, vitamin D has been proposed to be an important mediator of the immune system. Despite ample sunshine, vitamin D deficiency is prevalent (>80%) in the Middle East, resulting in a high rate of supplementation. However, the underlying molecular mechanisms of the specific regimen prescribed and the potential factors affecting an individual's response to vitamin D supplementation are not well characterized. Our objective is to describe the changes in the blood transcriptome and explore the potential mechanisms associated with vitamin D3 supplementation in one hundred vitamin D-deficient women who were given a weekly oral dose (50,000 IU) of vitamin D3 for three months. A high-throughput targeted PCR, composed of 264 genes representing the important blood transcriptomic fingerprints of health and disease states, was performed on pre and post-supplementation blood samples to profile the molecular response to vitamin D3. We identified 54 differentially expressed genes that were strongly modulated by vitamin D3 supplementation. Network analyses showed significant changes in the immune-related pathways such as TLR4/CD14 and IFN receptors, and catabolic processes related to NF-kB, which were subsequently confirmed by gene ontology enrichment analyses. We proposed a model for vitamin D3 response based on the expression changes of molecules involved in the receptor-mediated intra-cellular signaling pathways and the ensuing predicted effects on cytokine production. Overall, vitamin D3 has a strong effect on the immune system, G-coupled protein receptor signaling, and the ubiquitin system. We highlighted the major molecular changes and biological processes induced by vitamin D3, which will help to further investigate the effectiveness of vitamin D3 supplementation among individuals in the Middle East as well as other regions.

Land occupation by solar power installations has become a rising concern that may cause adverse impacts on natural ecosystems and biodiversity. Existing studies mainly adopt a local perspective to view land use requirements of solar power and forget that the solar-based electricity system is subordinate to the macro economy and nourished by the material, machinery and service support by various economic sectors. To manifest a key aspect of the footprint of solar power on land resources, this study uncovered the extensive industrial land use initiated by the infrastructure of a representative pilot solar-based electricity plant using a systems perspective. The results in this study show that in magnitude, land footprint by the infrastructure of the pilot solar plant amounts to three times as much as the onsite land area. Also, the land footprint calculated is revealed as one order of magnitude larger than a previous finding that includes primary materials only, and four to seven times higher than the onsite land use by coal-based electricity plants. The outcome implies that existing environmental management policies need to be re-evaluated by putting enough emphasis on the land displacement by solar power systems along the production chain., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

All-inorganic halide perovskite solar cells (PerSCs) have achieved rapid development in recent years. However, limited by narrow absorption bands, the power conversion efficiency (PCE) of all-inorganic halide PerSCs lag behind the organic-inorganic hybrid ones. In this contribution, to expand their absorption spectra and enhance the PCE, tandem solar cells (TSCs) with inorganic perovskite and organic conjugated molecules are constructed, utilizing CsPbI 2 Br as an ultraviolet-visible light absorber and a PTB7-Th:IEICO-4F bulk-heterojunction (BHJ) active layer as a near-infrared light absorber. To physically and electronically connect the front and rear subcells, P3HT/MoO 3 /Ag/PFN-Br is introduced as an interconnecting junction. Finally, the TSCs exhibit a remarkably higher PCE of 17.24% compared to that of the single junction PerSCs (12.09%) and organic solar cells (OSCs) (10.89%). These results indicate that the combination of all-inorganic perovskite and a low bandgap organic active layer for TSCs is a feasible approach to realize broad spectra utilization and efficiency enhancement.

Background: Activation of Toll-like-receptor 4 ( TLR4 ) causes chronic inflammation that can result in obesity and metabolic syndrome (MeS)., Aim: This study aimed to investigate the role of TLR4 polymorphisms of TLR4 D299G/T399I, and its impact on protein expression of TLR4 in obese female subjects., Methodology: A prospective cross-sectional association study was performed on Arab female subjects from Qatar University. The subjects were categorized according to BMI classifications into two groups: "obese; n = 69" and "non-obese; n = 136". Anthropometric measurements, weight (kg), height (m) and waist circumference (WC) were evaluated, and the body mass index (BMI) was calculated. Fasting blood samples were collected, and assessment of glucose, lipid profile, C-reactive protein (CRP), leptin, IL-6 and insulin was performed. Insulin resistance was computed using HOMA-IR. Genotyping of the TLR4 polymorphisms of TLR4 D299G (rs4986790) and TLR4 T399I (rs4986791) was performed by the 5' nuclease assay by TaqMan MGB probe. Flow cytometry was used to evaluate the monocyte cell surface expression of TLR4 ., Results: The frequency distribution of the genotype revealed that homozygous AA is the most frequent among obese subjects (86.4%) for ( TLR4 D299G, A > G) and the homozygous CC genotype is the most frequent (92.4%) for ( TLR4 T399I, C > T). Haplotype analysis of TLR4 D299G/T399I showed that GT carriers had a significant association with increased probability of insulin resistance (odds ratio = 4.73; 95% CI 1.19-18.90; p -value = 0.016). The monocyte cell surface of TLR4 was significantly higher by 1.3 folds in obese compared to non-obese subjects., Conclusions: TLR4 D299G/T399I haplotype polymorphism is associated with an increased risk of insulin resistance with the upregulation of TLR4 protein expression in obese subjects.

Purpose: Infantile hepatic hemangioendothelioma (IHHE) is the most common hepatic vascular tumor in children. We report on the treatment outcome of our large single-center experience of patients with IHHE over a 9-year period., Materials and Methods: A retrospective analysis of all IHHE patients treated at the Children Cancer Hospital Egypt from April 2008 through April 2017., Results: In total, 28 patients (18 females, 10 males) were diagnosed with IHHE with a median age at diagnosis of 3 months. The lesions were multifocal (n=12), focal (n=10), and diffuse (n=6). Six (21.4%) patients initially had low T3 and T4. Eleven patients did not receive any treatment, whereas 1 patient underwent resectional surgery. Sixteen patients received drug treatment, 9 of whom responded well to first-line propranolol/prednisolone, whereas 7 patients needed salvage treatment. Twenty-five patients are alive, whereas 3 patients have died., Conclusions: Overall, patients with IHHE do well, a significant percentage of whom do not require drug therapy, particularly for those with small focal lesions. In patients with multifocal/diffuse disease, there is a high incidence of low T3 and T4 and while some of these patients did well without additional therapy, those with rapidly progressive lesions during treatment may do poorly.

Introduction: The aim of the current study is to report the epidemiologic data, response rate, treatment outcome, and overall survival of anaplastic large cell lymphoma (ALCL) patients during the 8-year period., Patients and Methods: A retrospective study included all patients with newly diagnosed ALCL from July 2007 till December 2015., Results: A total of 48 patients were enrolled. The majority (66.7%) were male individuals. Twenty-one patients (43.7%) were low stage I or II, whereas 27 (56.2%) had advanced stage III or IV. Two patients (4.2%) died during induction chemotherapy. Disease status at last follow-up showed 35 patients (72.9%) in complete remission, 5 (10.5%) relapse, and 5 disease progression. The median time to relapse was 17.2 months. Four patients (8.4%) were salvaged by high-dose chemotherapy ifosphamide, carboplatine, etoposide followed by autologous hematopoietic stem cell transplantation, whereas 5 (10.5%) died out of disease progression. The 5-year overall survival and event-free survival were 81.2% and 68.6%, respectively. Median FU period was 58.7 month. Multivariate analysis included age, sex, stage, and response to chemotherapy and showed no statistical significance., Conclusion: Treatment of ALCL according to the Children's Oncology Group ANHL 0131 protocol is well tolerated. The relapsing patient could be salvaged by high-dose chemotherapy and autologous hematopoietic stem cell transplantation.

Background: Children and adolescents with HL have excellent long-term survival exceeding 95% after combined modality treatment. However, about 20% will either relapse or have PRF. Salvage HDCT followed by AHSCT is considered to be the preferential treatment., Objective: To describe the outcome (OS and EFS) and prognostic factors in pediatric patients with relapsed or refractory HL (r/rHL) who underwent AHSCT., Methods: We retrospectively included 43 pediatric patients with r/rHL who underwent AHSCT from July 1, 2007, till December 31, 2016, at the Children's Cancer Hospital of Egypt. MAC regimen given was CMV., Results: Of the whole cohort, 88.4% of patients achieved CR, while 11.6% had a positive PET scan prior to transplantation. The 3-year OS and EFS were 85% and 70.6%, respectively. The 3-year OS for patients > 10 years was 94% versus 65.5% for patients 10 years of age or younger (P = 0.046). There is strong tendency toward better 3-year OS for patients with negative PET scan as compared to those with positive PET scan before AHSCT, 89.4% vs 60%, respectively (P = 0.059). This tendency is also applicable when looking at the 3-year EFS for the two groups, 78.3% vs 40%, respectively (P = 0.069)., Conclusion: Poor predictors of OS were younger age and positive PET scan before AHSCT. The latter, along with single modality treatment before AHSCT, were poor predictors of EFS., (© 2019 Wiley Periodicals, Inc.)

In this study, graphene aerogel (GA) was successfully prepared through a simple hydrothermal method. The resulting GA exhibited a porous network structure with a large specific surface area (350.8 m 2 /g), ultra-light mass and easy separation from water. The pH IEP value of the GA was estimated to be 3.5. The adsorption process and the factors that affect adsorption capacity were studied. The adsorption could be conducted in a wide pH range from 2.0 to 7.0. The maximum adsorption capacity of GA towards U(VI) at pH 4.0 and T = 298 K was 238.67 mg/g calculated from the Langmuir model. The GA had greatly rapid adsorption property for the removal of U(VI) at pH 4.0. Kinetic data showed good correlation with pseudo-second-order equation. Fourier transform infrared spectroscopy and X-ray photoelectron spectrometry characterizations showed that GA adsorbed U(VI) through chemical interaction by oxygen-containing and nitrogen-containing groups functional groups. The results show that GA has excellent application potential as an adsorbent material for removing U(VI) from aqueous solution., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Layered double oxides (LDO) and γ-Fe 2 O 3 have been demonstrated to be promising adsorbents to remove radioactive elements from aqueous media. Herein, magnetic γ-Fe 2 O 3 nanoparticles decoration onto porous layered double oxides belts (γ-Fe 2 O 3 /LDO) were fabricated by in situ solid-state thermolysis technique combined with Fe(III)-loaded layered double hydroxides as a precursor. The microstructure, chemical composition, and magnetic properties of γ-Fe 2 O 3 /LDO were characterized in detail. The as-obtained γ-Fe 2 O 3 /LDO was employed as an adsorbent for the elimination of U(VI) from water. The adsorption process followed the Langmuir model with the maximal adsorption capacity of U(VI) onto γ-Fe 2 O 3 /LDO being 526.32 mg·g -1 at 303 K and pH 5, which surpassed pristine LDO and many other materials. The Fourier transformed infrared spectra and the X-ray photoelectron spectra analysis suggested that the interaction mechanism was mainly controlled by the surface complexation and electrostatic interactions. All in all, the γ-Fe 2 O 3 /LDO with remarkable adsorption capacity, excellent regeneration, and easy magnetic separation opens a new expectation as a suitable material for the cleanup of U(VI) from contaminated water., (Copyright © 2018 Elsevier Inc. All rights reserved.)

The rational construction of heterostructures by using layered semiconductors with two-dimensional (2D) nanosheet configurations is promising to improve the efficiency of CO 2 photoreduction. Herein, the fabrication of layered heterojunction photocatalysts (PCN/ZnIn 2 S 4 ) by in situ growth of 2D ZnIn 2 S 4 nanosheets on the surfaces of ultrathin polymeric carbon nitride (PCN) layers is presented for greatly enhanced CO 2 conversion with visible light. The solution-processed self-assembly strategy renders the building of uniform and intimate junctions between PCN layers and ZnIn 2 S 4 subunits, which remarkably accelerates the separation and transfer of photogenerated charge carriers. In addition, the layered composites can also promote CO 2 adsorption and strengthen the visible-light absorption. Consequently, the optimized PCN/ZnIn 2 S 4 sheet-shaped composite shows reinforced photoactivity for deoxygenative CO 2 conversion, affording a high CO-production rate of 44.6 μmol h -1 , which is 223 times higher than that of the pristine PCN nanosheets. Moreover, the heterojunction photocatalyst also exhibits high stability during repeated runs for five cycles., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Exploiting efficient photocatalysts with strengthened structure for solar-driven alcohol oxidation is of great significance. The photocatalytic performance of graphitic carbon nitrides can be considerably promoted by modulating its crystallinity. Results confirmed that a high crystallinity accelerates the separation and transfer of photogenerated charge carriers, thus providing more free charges for photoredox reactions. More importantly, the high crystallinity facilitated the adsorption of benzyl alcohol and desorption of benzaldehyde and simultaneously lowered the energy barrier for O 2 activation. As a result, the crystalline carbon nitride exhibited a roughly twelvefold promotion with respect to the normal carbon nitride. The remarkable enhancement of activity can be attributed to the synergistic effects of increased electron-hole separation and increased surface reaction kinetics. These findings will open up new opportunities to modulate the structure of polymers for a wide variety of organic reactions., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Aim: This study evaluated the effect of a single time tooth brushing instruction using video on a tablet PC (Apple iPad) compared to operator presentation using jaw model for plaque removal., Methods: This cross-sectional study included a convenience sample of 100 children divided into two groups. For Group 1 brushing was demonstrated to the child by the operator with the use of a jaw model. This demonstration was videotaped for subsequent use in Group 2 using a tablet PC (Apple iPad). Plaque index was recorded before and after demonstration of the assigned method of teaching tooth brushing., Results: The results showed a significant difference using the two methods. The difference between the mean plaque index values with the jaw model and tablet PC at baseline and after tooth brushing represented 17.27% (50% improvement) and 11.56% (34% improvement) respectively. Boys showed a 18.3%. higher improvement in tooth brushing compared to girls. Seventy-five percent of the children reported using tablet computers in their daily life. CONCLUSION Teaching children by using a jaw model was more effective in improving plaque index score than using video on tablet PC by 16%. Both methods of tooth brushing teaching were fully accepted by all children.

Background. Rhabdomyosarcoma (RMS) is the most common soft-tissue sarcoma in children. Fifty percent of RMS cases occur in the first 10 years of life and less commonly in infants younger than one-year old. These infants require adapted multimodality treatment approaches. Patients and Methods. We analyzed patients' characteristics, treatment modalities, and the outcome for RMS infants treated at Children's Cancer Hospital Egypt (CCHE) between July 2007 and December 2010 and compared them to patients above one year treated on the same protocol. Results. Out of the 126 RMS treated during this period, 18 were below the age of one year. The male: female ratio was 1.25 : 1. The median age at diagnosis was 0.7 ± 0.2 years. Most of the cases (27.8%) were presented in head and neck regions. The estimated 4-years failure-free survival and overall survival for infants were 49 ± 12% and 70 ± 12%, respectively. These failure-free survival rate and overall survival rate did not differ from those for older patients (P = 0.2). Conclusion. Infants with RMS are a unique group of RMS who needs special concerns in tailoring treatment in addition to concerns regarding toxicity and morbidity in infants.

Fifty four patients presenting by huge splenomegaly were admitted to Tropical Medicine Department, El-Minia University Hospital. Tissue biopsy revealed pure bilharziasis due to S. hematobium in 10 (19%) cases, liver cirrhosis in 23 (42%), mixed schistosomiasis and cirrhosis in 8 (15%), hepatoma in 3 (6%), lymphoma in 6 (11%) and hematological diseases in the form of chronic myeloid leukemia in 2 (3.5%) and thalassemia major in 2 (3.5%) cases. The sensitivity and specificity of abdominal ultrasonography was 100% and 97% in cases of schistosomiasis, 100% and 100% in cases of hepatoma, 87% and 100% in cases of liver cirrhosis, 33% and 100% in cases of lymphoma respectively. There was a positive significant correlation between endoscopic variceal grading, portal vein diameter, splenic vein diameter, size of the spleen and the grading of the portal tract thickenings. The pathological and ultrasonographic diagnosis was the same in 38 (70%) cases. Splenogram was characteristic but not diagnostic in cases of schistosomiasis and liver cirrhosis. It was diagnostic and similar to peripheral blood picture in the 2 cases of chronic myeloid leukemia and was normal in cases of thalassemia major. Splenic aspiration was able to diagnose all cases of lymphomas. It can be considered as a useful adjunct to the usual diagnostic procedures, both in staging and follow up, especially in cases presenting only by splenomegaly.

The incidence of vitiligo at King Khalid University Hospital (KKUH), Riyadh, Saudi Arabia was 2.5% for the period from 1985-1990. The majority (96.1%) were Saudis. Approximately 64% were below the age of 30 years and the average was 25.6+/- SD 13.7 years. Fifty-six percent of the patients were males and 43% were females. More than half of the patients had the lesions for a period between one and nine years and 17.17% had them for more than 15 years. Only 12% had a positive family history of vitiligo. The majority (54%) of the lesions were in exposed areas. The associated diseases with vitiligo are also reported. It appears that the clinical pattern of vitiligo is not different from what is reported in other studies.

The biosynthesis of the triterpenoid alcohol tetrahymanol by Tetrahymena pyriformis is rapidly inhibited by the addition of cholesterol to the growth medium. The primary site of this inhibition by cholesterol has been established to be at the level of the enzyme squalene synthetase. The protein synthesis inhibitor cycloheximide produces an identical decline in squalene synthetase activity to that of cholesterol and the half-life of the enzyme is about 50 minutes. No direct inhibition of the enzyme is observed and suggests that cholesterol inhibits the actual synthesis of the enzyme squalene synthetase. Farnesol is accumulated during in vitro incubations derived from cells grown in the presence of cholesterol or cycloheximide.