The relation of the accumulation of cadmium in human placenta to the intake of high-fibre grains and maternal iron status.

Exposure to cadmium via the diet is known to depend to a large extent on the intake of cereal grains, particularly the high-fibre fractions of wheat. Subjects with low iron status absorb more cadmium than those with better iron status. The purpose of the present study was to determine to what extent cadmium accumulation in human placenta is affected by the intake of grain fibre and maternal iron status during pregnancy. Thirty-nine pregnant women participated in the study. In each trimester the women were requested to complete a dietary history and to allow blood samples to be taken for haemoglobin, serum ferritin and serum thiocyanate determinations, the latter as a marker for smoking. At delivery the whole placenta was taken for the determination of the cadmium concentration. The 32 women who had serum thiocyanate levels less than 70 mumol/l, who had completed at least one dietary history and from whom a blood sample was obtained in the third trimester, were included in the final statistical analyses. In the group of women who consumed less than the median intake of grain fibre and had more than 15 micrograms ferritin/l serum in the third trimester, the placenta cadmium concentration was nearly half that in the placentae of women who had consumed more grain fibre or had lower iron status in late pregnancy.     

Possible anatomical base of snoring

Variations of the medial and inferior choanal limits may facilitate snoring. These are: 1) short vomer without crista choanalis vomeris and adaptational formations, 2) extremely concave posterior margin of the hard palate leading to disproportion between the muscular and aponeurotic part of m. tensor veli palatini and hence to a flabby soft palate especially during sleep, and 3) neonatal relation of the height and width of the choane resulting in a very large choanal region instead of relative reduction of choanal width compared to its increasing height. All these variations result in a flabby soft palate especially during sleep and may lead to formation of whirles of inspired air and snoring.     

Development of an auxotrophic oral live Shigella flexneri vaccine

An oral live attenuated Shigella flexneri vaccine candidate strain was constructed by making it auxotrophic and dependent on aromatic metabolites not available in mammalian tissues. An aroD gene of Escherichia coli K12 strain NK 5131, inactivated by insertion in it of the Tn 10 transposon, was transduced using phage P1 into a virulent S. flexneri serotype Y strain (Sfl 1) isolated from a patient with bacillary dysentery. One of the transductant strains Sfl 114 was found to invade HeLa cells in vitro, to cause plaque formation in HeLa monolayers (i.e. maintain intracellular multiplication in vitro), but to be unable to cause keratoconjunctivitis in guinea-pig eyes. When the strain was fed to Macacca fascicularis monkeys it was well tolerated, excreted for 1-4 days, and found to elicit a local intestinal sIgA and serum IgA, IgM and IgG responses. Monkeys challenged with 100 ID50 dose (1 X 10(11) bacteria) of the virulent parent Sfl 1 strain were completely protected from development of diarrhoea. Coloscopy of the monkeys and the sampling of intestinal biopsies showed that the vaccine protected against the surface epithelial erosions and ulcerations seen in unimmunized monkeys. Killing of invading virulent shigellae apparently took place intracellularly in the mucosa suggesting that cellular immune mechanisms played a role in the elicited host defence. The constructed S. flexneri Sfl 114 strain has the properties of a promising shigella vaccine and will next be the subject of studies with human volunteers.     

Linseed and cod liver oil induce rapid growth in a 7-year-old girl with N-3- fatty acid deficiency

N-3 fatty acid deficiency is described in a 7-year-old girl who had been fed solely by gastric tube from the age of 3 years. She had received the same nutrient during the last 22 months, supplying 16.2% of calories from linoleate and 0.07% from alpha-linolenate. She weighed 9.5 kg at the age of 3, and 10.3 kg at the start of the study, the weight being constant the last 15 months. She was now supplemented daily with 1.2 ml of a linseed- and cod liver-oil mixture (5:1, v/v), thereby increasing her alpha-linolenate intake to 0.71% and total N-3 fatty acids to 0.74% of total energy. Two months later, her rate of weight gain was 0.43 kg/month. After 5 months, the fatty acid supplement was changed to 7.5 ml of cod liver oil daily, thereby changing alpha-linolenate and total N-3 acid intake to 0.10% and 1.3% of total energy, respectively. Her rate of weight gain now increased to 0.64 kg/month, and her length increased from 117 to 122 cm in 5 months. The results indicate that the optimal dietary requirement for N-3 fatty acids in this child is higher than 0.74%, and extrapolation estimated the optimal requirement to be 1.1%-1.2% of total calories. The results suggest that N-3 fatty acids are required for normal growth in man.     

An analysis of astrocytic cell lines with different abilities to promote axon growth

The adult mammalian central nervous system (CNS) lacks the capacity to support axonal regeneration. There is increasing evidence to suggest that astrocytes, the major glial population in the CNS, may possess both axon-growth promoting and axon-growth inhibitory properties and the latter may contribute to the poor regenerative capacity of the CNS. In order to examine the molecular differences between axon-growth permissive and axon-growth inhibitory astrocytes, a panel of astrocyte cell lines exhibiting a range of axon-growth promoting properties was generated and analysed. No clear correlation was found between the axon-growth promoting properties of these astrocyte cell lines with: (i) the expression of known neurite-outgrowth promoting molecules such as laminin, fibronectin andN-cadherin; (ii) the expression of known inhibitory molecules such tenascin and chondroitin sulphate proteoglycan; (iii) plasminogen activator and plasminogen activator inhibitor activity; and (iv) growth cone collapsing activity. EM studies on aggregates formed from astrocyte cell lines, however, revealed the presence of an abundance of extracellular matrix material associated with the more inhibitory astrocyte cell lines. When matrix deposited by astrocyte cell lines was assessed for axon-growth promoting activity, matrix from permissive lines was found to be a good substrate, whereas matrix from the inhibitory astrocyte lines was a poor substrate for neuritic growth. Our findings, taken together, suggest that the functional differences between the permissive and the inhibitory astrocyte cell lines reside largely with the ECM.     

Relation between energy expenditure and body composition in man: specific energy expenditure in vivo of fat and fat-free tissue

The relationship between energy expenditure and body composition, in terms of fat and fat-free masses, has previously been described by a variety of predictive regression equations with parameters devoid of physiological content. We present here results obtained by calculating the specific energy expenditure, ie, the energy expenditure per unit of mass, of fat and fat-free tissue on the basis of measurements of the total energy expenditure (EE), the masses of fat (FM), and fat-free (FFM) tissue using the following simple model: EE = k1.FM + k2.FFM where k1 and k2 are the specific energy expenditures of fat and fat-free tissue, respectively. The results of observations on 104 women at rest yielded values for k1 and k2 of 0.31 and 1.35 watts/kg of fat and fat-free mass, respectively, with standard errors of estimate of 0.074 and 0.052 watts/kg, respectively. Analysis of several series of measurements, from other sources and on smaller samples of subjects, yielded similar values at rest but with larger standard errors of estimate. Data from subjects performing varying amounts of work in 24-h measurements showed, as expected, larger values for both tissues. The results explain to a very large extent the well-established relation between resting metabolic rate and body weight, ie, a linear relation with a non-zero intercept. The results also offer a clear-cut explanation for the well known difference in energy expenditure between men and women with the same body weight.     

银汞充填体悬突的去除及效果的临床观察

本文选择34颗有银汞充填体悬突的患牙,采用金刚砂钻和银汞磨光钻去除悬突,并观察去除悬突前后部分牙周组织的变化、结果表明银汞充填体悬突危害牙周组织的健康.去除悬突并协同口腔卫生宣教、可促进牙周组织的恢复.