Environmental, urinary iodine status and prevalence of goitre among schoolchildren in a high altitude area of Saudi Arabia.

OBJECTIVE: This study aimed to assess the iodine deficiency, prevalence of goitre among schoolchildren and measuring environmental iodine in Taif city, Saudi Arabia. METHODS: A cross-sectional multistage cluster-sampling methodology was done on 1887 schoolchildren. Their urinary iodine concentration (UIC) and goitre prevalence was assessed. Blood level of triiodothyronin, thyroxine and thyroid-stimulating-hormone was carried out for students with normal, mild; moderate and sever iodine deficiency. The iodine content of salt, water and soil was also assessed. RESULTS: Goitre prevalence was 7.4% and about 71% of the participants had UIC less than 100µg/L. An inverse relationship between median UIC and the percent prevalence of goitre was found. The mean serum T3, T4 and TSH were 1.05ng/dL, 6.81µg/dL, and 5.69mIU/L, respectively. A significant positive correlation was found between the mean value of urinary iodine and the mean value of both T3 and T4. While a significant negative correlation between the mean value of urinary iodine and the mean value of TSH was also noted. CONCLUSIONS: The results revealed the presence of a potential public health problem of iodine deficiency among school going children in high altitude areas of Saudi Arabia. There is a need to monitor and evaluate the salt iodization process, and distribute adequately iodized salt in the affected areas.

The antileukemic activity of modified fibrinogen-methotrexate conjugate.

BACKGROUND: The search for new, innovative methods to treat all types of diseases, especially cancer-related ones, is a challenge taken by pharmaceutical companies and academic institutions. The use of conjugates containing widely-known and widely-used bioactive substances is one of the ways to solve this problem. Research into drug binding with macromolecular carrier systems has joined the search for new therapeutic strategies. METHODS: The main goal of this paper is the potential offered by the use of fibrinogen derivatives as an antileukemic drug carrier. Physicochemical properties of the obtained conjugate were analyzed, characterizing alterations in relation to the starting carrier and analyzing biological implications. The intraperitoneally (i.p.) inoculated P388 mouse leukemia model for in vivo studies was used. RESULTS AND CONCLUSIONS: Conjugates consisting of a fibrinogen derivative with a covalently bound anticancer drug were developed. Carrier preparation and a conjugate synthesis in aqueous solution were formulated, as well as purification of the conjugate was performed. The study showed that the survival of leukemia mice treated with FH-MTX conjugate was indeed significantly longer than survival in both untreated animals (control) and mice treated with unbound MTX. A significant increase in the antileukemic activity of MTX conjugated with hydrolysed fibrinogen was observed as compared with the unconjugated drug. Reported data suggest that hydrolysed fibrinogen can serve as a carrier molecule for the MTX drug with the aim of enhancing its antileukemic activity. GENERAL SIGNIFICANCE: Conjugates consisting of a fibrinogen derivative with a covalently bound anticancer drug seem to be a promising anticancer drug.

Antitumor properties and toxicity of dextran-methotrexate conjugates are dependent on the molecular weight of the carrier.

Methotrexate (MTX) is widely utilized in the clinical treatment of many forms of cancer. However, the drug has a short plasma half-life and causes toxic effects on normal proliferating cells. Conjugation with carriers is a possible way to alter these disadvantageous pharmacokinetics. Our aim was to synthesize dextran-MTX (D-MTX) conjugates, using carriers with molecular weights (Mw) ranging from 10 kDa to 500 kDa. Their in vitro and in vivo properties were compared with free MTX. The in vitro studies revealed that D-MTX conjugates had 4- to 10-fold lower antiproliferative effects against neoplastic cell lines compared to free MTX. There was a negative relationship between the Mw of the carrier and the antiproliferative effect of the respective conjugate. The data obtained in a mouse leukemia P388 in vivo model suggested that a lower in vitro antiproliferative effect of the conjugates does not result in diminished antileukemic activity in vivo. The toxicity of the conjugates was greater in comparison with the parent drug and tended to rise with increasing Mw. However, no superiority over free MTX in terms of an antileukemic effect was demonstrated. In particular, the D-MTX conjugate based on the dextran with Mw 10 kDa showed a comparable antileukemic effect with an even lower toxicity than that of free MTX. The data suggest that at least the toxicity of conjugates is dependent on the Mw of the carrier. This fact should be taken into account when designing new anticancer polymer-drug compounds.

The effect of the substitution level of some dextran-methotrexate conjugates on their antitumor activity in experimental cancer models.

Methotrexate (MTX) is widely used in the treatment of a number of oncological and hematological diseases. Due to its known limitations, MTX is often conjugated with different carriers to obtain amended forms of the drug. In this study, the potential influence of the substitution level (loading ratio) of the dextran T10- and T40-based MTX conjugates (D-MTX) on their properties were investigated in vitro and in vivo. The clear dependence of the in vitro antiproliferative effect on the substitution level was established only in the case of the dextran T10-based preparations (T10-MTX conjugates). Conjugates with the higher substitution level had the lower antiproliferative effect. For the dextran T40-based (T40-MTX conjugates) set no similar relationship was observed in the tested range of substitution levels, nor was any dependence observed between the biological properties of the D-MTX preparations in vivo and their substitution levels. However, the difference between the two conjugates was well pronounced in a multiple-dose schedule, when the advantage of T40-MTX over T10-MTX was cumulative during the prolonged course of administration.

Antileukemic activity of glycated fibrinogen-methotrexate conjugates.

BACKGROUND: The aim of the study was to compare the antileukemic activity of methotrexate (MTX) conjugates with native and glycated fibrinogen. We expected that conjugates based on glycated fibrinogen would reveal higher antileukemic activity because of decreased plasmin digestibility and a higher retention rate of glycated fibrinogen in the body. MATERIALS AND METHODS: Fibrinogen was glycated using a high-temperature procedure at 65-85 degrees C. Glycated fibrinogens were examined with respect to their ability to clot and susceptibility to plasmin digestion. Native fibrinogen (F) and fibrinogens glycated at 65 and 73 degrees C (F65 and F73) were conjugated with MTX and tested in mice bearing P388 leukemia, at a dose of 40 mg of MTX per kg of body weight. RESULTS: Glycated fibrinogens retained their ability to clot. Compared to native fibrinogen, they were more resistant to digestion by plasmin. All tested conjugates revealed higher antitumor activity than the free drug. Increases in average lifespan over the control group were 34% for free MTX, 137% for F-MTX, 151% for F65-MTX and 91% for F73-MTX. The differences between the antitumor activities of all conjugates were not statistically significant. CONCLUSION: It seems necessary to compare the antitumor activities of MTX conjugates based on native and glycated fibrinogen in different tumor models, to demonstrate the expected differences.