Placenta sampling methods

The only other human tissue that has been analyzed for various BP compounds is the human placenta. Using a LC-MS/MS method, levels of several BPs were determined in 16 placental samples of women residing in Granada, Spain (Vela-Soria et al. 2011). The metabolite of BP, 4-OH BP, was detected in 68.8 % of the placenta samples in the range of 0.6-1.2 ng/g of tissue. Further research is needed to determine if the placenta could be used to monitor levels of BP metabolites in human populations. 

A method applied for placenta tissue and compared with a solid sampling technique has been published by Herber et al. (1985). 

The recent discovery of high-level thallium pollution in the environment has focused attention on the teratogenicity (fetus malformation). For detailed investigations in this field a method is required which enables the quantitative detection of thallium in extremely small tissue samples (embryos, placenta tissues etc.) thus permitting to establish a correlation between measured values and teratological findings. Regarding the pharmacokinetics of thallium in a test animal (mouse) the first results obtained by FDMS have been reported . 

Goyer and Cherian (1992) measured cadmium, zinc and copper, and metallothionein content of human placentas from 55 uncomplicated, full-term deliveries. The mothers ages ranged from 22 to 39 years, mean 29 years. All were current nonsmokers, but 16 (30%) acknowledged smoking in the past. None were on medication apart from iron and vitamin supplements. For 43 it was the first delivery, for 9 the second, for 1 the third, and for 2 the fourth. Samples of maternal and fetal blood were not obtained. Metals were measured by atomic absorption spectrophotometry and metallothionein by a silver saturation method (Scheuhammer and Cherian 1986). The results are shown in Table 1. Zinc levels of placentas were almost the same as those in the Kuhnert et al. (1988) study, but copper levels were considerably lower. No other comparable measurements of metallothionein were found in the literature. There is a strongly positive correlation between... 

Mobile phase M, = toluene-chloroform (50 1) A/j = benzene-methyl isopropylketone (50 1) Mi = methanol-water-acetic acid (50 30 4). Conditions Ascending technique, run 15 cm. layer thickness 0.25 mm, activation at 120°C for 30 min. Detection (a) metal dithizonates were self detected, (b) 5% aqueous copper sulfate solution for metal diethyidithiocarbamates and (c) 0.25% PAN [l-(2-pyridylazo)-2-naphthol solution) in methanol followed by exposure to ammonia vapors for metal ions. Remarks (1) Best separations on RP-18 with My (2) The extracts of complexes of metals originating from biological samples require careful protection from environmental contamination and (3) The developed TLC method was applied for analysing human placentas collected from patients of the obstetrics Clinic in Tychi (Poland) for Pb. Cd, Zn, Cu, Ni, Mn. and Co content. 

The very same principle was applied by Suzuki et al. [19] for the purification of the placental insulin receptor, starting with a prepurified sample, obtained from a plasma membrane fraction of human placenta by a fractionation protocol including affinity chromatography on Sepharose-concanavalin A as the last step. The following purification step was carried out, using insulin bound to dextran (M 40000) as the biospecific, water-soluble carrier. After filtration of the dextran-insulin-receptor complex on an adequate gel and then dissociation by mild acidification, the insulin receptor was obtained in a purified form. This method permitted a 8700 fold purification, from crude plasma membrane and, even more remarkable, a 60-fold purification after the affinity chromatography step. 

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