Proof-of-concept trial on the efficacy of sodium tungstate in human obesity

AIM

Considering the poor long-term success of current dietary and pharmacological interventions, we aimed to evaluate the potential effect of sodium tungstate in the treatment of grade I and II obesity (ClinicalTrials.gov identifier: NCT00555074).

METHODS

Prospective, randomized, placebo-controlled, double-blind, proof-of-concept study was carried out. Following a 2-week lead-in period, 30 obese (body mass index, BMI 30.0-39.9 kg/m(2)), non-diabetic subjects were randomized to receive either sodium tungstate (100 mg bid) or placebo for 6 weeks. The primary study endpoint was the absolute change in body weight relative to the time of randomization.

RESULTS

Treatment with sodium tungstate [-0.135 ± 0.268 kg (95% CI -0.686 to +0.416 kg)] was not associated with a significant weight loss compared to placebo [-0.063 ± 0.277 kg (95% CI -0.632 to +0.507 kg)] (p = 0.854). Likewise, treatment with sodium tungstate was not associated with significant changes in fat mass (DEXA), resting energy expenditure (indirect calorimetry) or caloric consumption (3-day food records).

CONCLUSION

Our data do not support sodium tungstate as a pharmacological agent in the treatment of human obesity.

Comparison of the toxicity and distribution of cadmium and lead in plant cells

The toxicity of heavy metals (Cd, Zn, and Pb) was assessed by in vivo observations of their effect on cytoplasmic streaming in Allium cepa L. bulb scale epidermal cells. On the basis of our results, the order of toxicity of the studied cations is Zn < Pb << Cd. The difference in toxicity between cadmium and lead was found to be very large. When cytoplasmic streaming was assessed, this difference was threefold. When the total content of cadmium and lead (determined by inductively coupled plasma mass spectrometry) was the criterion, the difference in toxicity was 15-fold. Fractionation of the tissue and enzymatic digestion of the cells revealed that the largest proportion of cadmium was located in the cell walls (56%), whereas almost all of the lead (97.6%) was accumulated in an insoluble form. The speciation of water-soluble Pb and Cd fractions is discussed on the basis of analysis by capillary zone electrophoresis interfaced with inductively coupled plasma mass spectrometry of water extracts from epidermal cells. Lead and cadmium appeared to be bound mainly to salts, which explains their toxicity. Cadmium was complexed (detoxified) by organic acids, while thiols were the metal-complexing species for lead. Histidine formed complexes with both cadmium and lead. Ultrastructural analyses showed that lead was encapsulated in small vesicles in the cytoplasm. Fluorescence studies of the endoplasmic reticulum (ER) revealed that it underwent extensive fragmentation under the influence of lead, with numerous ER vesicles appearing in the cells. In other words, the lead deposits in the cytoplasm were contained in vesicles arising from fragmentation of the ER. These observations indicate that epidermal cells have a rapid and effective mechanism for detoxifying lead involving the ER, and this may be one of the mechanisms accounting for the lower toxicity of lead in comparison with cadmium. The suitability of Allium cepa bulb scale epidermal cells for use in ecotoxicological studies is also discussed. Step-by-step directions for this test are given.

Concentrations and bioavailability of cadmium and lead in cocoa powder and related products

Concentrations and bioavailability of cadmium (Cd) and lead (Pb) were determined in cocoa powders and related products (beans, liquor, butter) of different geographical origins. Particular attention was paid to the fractionation of these metals, which was investigated by determining the metal fraction soluble in extractant solutions acting selectively with regard to the different classes of ligands. The targeted classes of Cd and Pb species included: water-soluble compounds, polypeptide and polysaccharide complexes, and compounds soluble in simulated gastrointestinal conditions. The bioavailability of Cd and Pb from cocoa powder, liquor and butter was evaluated using a sequential enzymolysis approach. The data obtained as a function of the geographical origin of the samples indicated strong differences not only in terms of the total Cd and Pb concentrations, but also with regard to the bioavailability of these metals. The Cd concentrations in the cocoa powders varied from 94 to 1833 microg kg(-1), of which 10-50% was potentially bioavailable. The bioavailability of Pb was generally below 10% and the concentrations measured in the cocoa powders were in the 11-769 microg kg(-1) range. Virtually all the Cd and most of Pb were found in the cocoa powder after the pressing of the liquor.

Development of a sequential enzymolysis approach for the evaluation of the bioaccessibility of Cd and Pb from cocoa

An in vitro model simulating enzymatic activity in the gastrointestinal tract was developed for the assessment of the potential bioaccessibility of Cd and Pb in cocoa powder and liquor. The model was based on the sequential extraction with simulated gastric and intestinal juices; the residue after the latter extraction was further investigated by using, in parallel, solutions of phytase and cellulase. The solubility of Cd and Pb in the corresponding enzymatic extracts was measured by ICP MS. The bioaccessibility of Cd in cocoa varied from 10 to 50% in gastrointestinal conditions. An additional 20 or 30% of Cd could be recovered by phytase and cellulase, respectively. The bioaccessibility of Pb in gastrointestinal conditions did not exceed 5-10%. Only a few percent more of this metal could be recovered by extraction with phytase and cellulase.

Butyltins in sediments and three-spined stickleback (Gasterosteus aculleatus) from the marinas of the Gulf of Gdansk, Baltic Sea

Fifty four sediment samples and three pooled samples of whole three-spined stickleback (Gasterosteus aculleatus) collected from four marinas located along the south-western coast of the Gulf of Gdańsk, Baltic Sea, Poland, were examined for butyltins (BTs) i.e., tributyltin (TBT), dibutyltin (DBT) and monobutyltin (MBT), to understand the degree of pollution and distribution pattern. Total butyltin concentrations in sediments from the marina of the city of Gdynia ranged between 130 and 20,000 ng Sn/g dry wt. with a mean value of 2,900 ng Sn/g. In sediments collected from the marinas located in the area of the Brave Vistula River Channel BT concentrations ranged between 10 to 15,000 ng Sn/g drywt. with a mean values between 500 and 5,500 ng Sn/g, and the innermost sites of each of four marinas were the most polluted. The mean BT concentrations in three-spined stickleback were between 1,500 and 3,100 ng Sn/g wetwt. and the values followed mean concentrations noted in sediments from the corresponding marina. The pleasure yachts are identified as the main source of BT pollution of sediment and fish. Tributyltin was a major form of BTs present in sediments (between 24 and 43%) and in three-spined stickleback (between 54 and 70%), suggesting a very recent use of marine paints containing TBT in pleasure yachts. Evidently at the Polish coast of the Baltic Sea TBT was continuously used in 1997 in marine paints for boats less then 25 m long.

Investigation of arsenic speciation in oyster test reference material by multidimensional HPLC-ICP-MS and electrospray tandem mass spectrometry (ES-MS-MS)

Multidimensional (size-exclusion-anion-exchange-cation-exchange) liquid chromatography with ICP-MS detection was developed to produce a map of water-soluble species in an oyster test reference material. The presence of arsenobetaine, trimethyl(2-carboxyethyl)arsonium inner salt, arsenocholine, dimethylarsonic acid, tetramethylammonium ion, As(v) and two arsenosugars was demonstrated by ES-MS-MS. A previously unreported compound was isolated and identified by ES-MS-MS as 5-dimethylarsinoyl-beta-ribofuranose. Anion-exchange chromatography was optimized to produce a chromatographically pure peak of arsenobetaine (accounting for ca. 64% of all water-soluble As present) that was used to quantify this compound.

Occurrence and effects of organotins on adult common whelk (Buccinum undatum) (Mollusca, Gastropoda) in harbours and in a simulated dredging situation

Transplanted common whelk (Buccinum undatum) (Mollusca, Gastropoda) accumulated fairly high levels of organotins (tributyltin (TBT) and triphenyltin (TPT)) during exposure in three harbours with different TBT contamination. This did not though lead to an increase in imposex frequency in the adult females studied. Simulating harbour dredging in an experiment using suspended sediment from one of the harbours only resulted in a low concentration of TBT in the tissues of the common whelk and subsequently no changes in the occurrence and degree of imposex. The common whelk seemed to receive the main part of TBT from the water column and the limited bioaccumulation in the experiment indicates that desorption of TBT from the suspended sediment was slow. After TBT has been totally banned, dredging of contaminated sediments will cause increased exposure of the biota to TBT. Due to slow desorption the increase may however, be slight and temporary to pelagic and epibenthic species unless the settled particles are resuspended.

Determination of phytochelatins by capillary zone electrophoresis with electrospray tandem mass spectrometry detection (CZE-ES MS/MS)

The coupling of capillary zone electrophoresis with electrospray mass spectrometry was optimized for the direct determination of phytochelatins (PCs) in extracts obtained from cells and plants that had been exposed to metal stress. Gluthathione and phytochelatins belonging to the different families (gamma Glu-Cys)nGly (n-PC), (gamma Glu-Cys)nSer, (gamma Glu-Cys)n beta Ala and (gamma Glu-Cys)n were separated in an uncoated capillary at pH 4 using a 5 mM ammonium acetate buffer, and detected by electrospray (ES) MS in the full scan mode (300-1100 u). The use of on-line tandem MS detection in the product ion scan mode of putative protonated molecules of PCs allowed the unambiguous confirmation of the identity of the compounds detected by ES MS. The operational conditions were optimized and the figures of merit were evaluated using n-PC2, n-PC3 and n-PC4 standards purified from a mixture obtained after the reaction of glutathione in the presence of Cd2+ and the enzyme PC-synthase. The method was applied to the characterization of bioinduced ligands in cell cultures of soybeans (Glycine max) and in rice (Oryza sativa) roots without the need for a preliminary sample cleanup by size-exclusion and/or reversed phase chromatography.

Labyrinthine fistula and tympanoplasty

Three interdependent problems have to be solved by a surgeon in each case of middle ear cholesteatoma with a fistula of the horizontal canal: 1) Whether the matrix can be safely removed from fistula or should be left in place; 2) if the matrix is removed, whether the fistula should be covered or not and, in the positive case, by which kind of graft; and 3) whether closed or open tympanoplasty should be performed. In well selected cases the matrix can be safely removed from the fistula and some technique of closed tympanoplasty used. Suitable for this type of surgery are cases of superficial fistula of the horizontal canal, with preservation of the endosteal membrane, where complete removal of the matrix from the tympanic cavity is possible. Very poor hearing and obvious middle ear infection are apparent contraindications. Furthermore, this type of surgery should not be performed on a better hearing ear. If any difficuty in removal of the matrix from the fistula is encountered, the matrix should be left in place. Fistula cases which do not fulfill these criteria should be treated either by open tympanoplasty or by modified radical mastoidectomy, leaving the matrix on the fistula. A small series of five consecutive fistula cases treated by closed tympanoplasty, using intact wall technique or reconstruction of the bony canal wall, with removal of the matrix from the fistula, leaving it bare, is reported after a follow up of three to six years. The results indicate that, in selected fistula cases, this type of surgery seems to bring favorable late hearing results and to create good conditions for closure of the fistula, apparently not presenting any risk to the inner ear.

Early diagnosis of maxillary carcinoma

Problems of early diagnosis of maxillary carcinoma are discussed and symptomatology of early and relatively early cases is fully presented. In cases which might be suspected of being malignant thoughtful attention to all details of examination and careful evaluation of seemingly insignificant symptoms and signs are of greatest importance. All methods of early detection of antral cancer are evaluated. The most valuable from among them are: tomography, including panoramic tomography, and sinoscopy. Measures which should be taken to shorten the interval between symptoms onset and the definite diagnosis of maxillary carcinoma are specified.