Evaluation of dioxin-like chemicals in pooled human milk samples collected in Australia.

DESIGN: Human milk samples were collected and analysed for the levels of polychlorinated dibenzodioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and selected dioxin-like polychlorinated biphenyls (PCBs). In total, 157 individual samples collected during 2002 and 2003 as well as 24 samples collected in 1993 were analysed as 20 pools. RESULTS: PCDDs, PCDFs and dioxin-like PCBs were detected in all pooled samples. For samples collected during 2002/2003, the TEQ(DFP) ranged from 6.0 to 15.2 pg TEQ g(-1) lipid with an average of 9.0 pg TEQ g(-1) lipid. The average lipid content was 3.7+/-0.5%. No systematic differences were observed in the levels of PCDDs, PCDFs and PCBs in human milk samples collected from different regions of Australia during 2002/2003. For samples collected in 1993 and analysed as pools, the mean level, expressed as TEQ(DFP) was 16+/-1.4 pg TEQ g(-1) lipid. The average lipid content was 3.9+/-0.7%. CONCLUSION: The levels of PCDDs, PCDFs and dioxin-like PCBs in the human milk of Australian women are both low compared to international levels and similar across all regions of Australia. Consistent with world-wide trends, the levels of PCDDs, PCDFs and dioxin-like PCBs have decreased over a 10 year period from 1993 to 2003 by approximately 40%.

Isolation and NMR spectroscopic clarification of the alkaloid 1,3,7-trimethylguanine from the ascidian Eudistoma maculosum.

The alkaloid 1,3,7-trimethylguanine was isolated from the ascidian Eudistoma maculosum, and differences in the NMR spectroscopic data for this compound compared with data in the literature are due to ammonium salt formation.

The presence of a human UV filter within the lens represents an oxidative stress.

It has recently been demonstrated that, with age, UV filters such as 3-hydroxykynurenine glucoside, bind to proteins in the human lens. This covalent interaction leads to colouration of the normal lens, and results from the instability of the kynurenine side chain. Other primate UV filters, in addition to containing the same side chain, can also be readily oxidized. One such compound is 3-hydroxykynurenine (3OHKyn). It has been proposed that oxidation of bound and/or free UV filters, such as 3OHKyn may give rise to the lens colouration associated with age-related nuclear cataract. Therefore it has become important to understand the oxidation of 3OHKyn within the lens. In this study, intact bovine lenses (which lack UV filters) were incubated with 3OHKyn and various lens parameters monitored. The effect of exposure to hyperbaric oxygen (HBO) was also assessed, both alone, and in combination with prior 3OHKyn incubation. Glutathione (GSH), protein sulfhydryl and protein-bound sulfhydryl levels, as well as soluble protein content and gel filtration profiles, were obtained for cortical and nuclear regions after defined periods of incubation. The presence of the primate UV filter, 3OHKyn, at concentrations similar to those present in the human lens, was shown to produce considerable oxidative stress within the lens, as judged by its effect on GSH. This effect was noted under normobaric conditions, but was exacerbated by increased oxygen. Exposure of lenses to HBO caused a marked fall in GSH in cortical and nuclear regions. This effect was exaggerated in the presence of 3OHKyn. HBO treatment also lead to a fall in protein sulfhydryl content, however, this was only partial (approximately 1 mol SH per mol protein) and changed only slowly, even with extended periods of exposure to HBO, suggesting that most crystallin sulfhydryl groups may be buried. 3OHKyn did not appreciably affect this oxidation although it did cause an increase in the level of protein-bound sulfhydryl. HBO treatment produced a more than two-fold increase in protein-bound sulfhydryl content in the cortex. There was little influence of 3OHKyn alone on protein solubility, even with extended periods of incubation, however, incubation for 72 hr in the presence of HBO caused a significant increase in insoluble protein particularly in the nucleus. This insolubilization was further increased in the presence of 3OHKyn. FPLC profiles showed that the proportion of gamma and beta crystallins in the soluble fraction decreased following HBO, suggesting that these may be involved in disulfide bond formation. This study demonstrates that a readily oxidized compound, such as the primate UV filter 3OHKyn, represents an oxidative stress within the lens and that such oxidative processes can be exacerbated if the concentration of oxygen within the lens is increased. We speculate that this factor may account for the evolution of unusually high levels of glutathione reductase in human lenses.

Antibacterial compounds from Carissa lanceolata R.Br.

The dichloromethane extract of the wood of Carissa lanceolata R.Br. (Apocynaceae) afforded the eudesmanes carissone, dehydrocarissone and carindone. This is the first account of carissone being isolated from the wood of C. lanceolata, and of carindone being isolated from this Carissa species. Dehydrocarissone has not been isolated previously from any Carissa species. The antibacterial activity of these natural products were examined against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. All three compounds showed activity, with dehydrocarissone and carindone having a minimum inhibitory concentration less than 0.5 mg/ml against S. aureus and E. coli.

Development of the human corpus callosum during childhood and adolescence: a longitudinal MRI study.

1. Interest in the morphologic development of the corpus callosum (CC) during childhood and adolescence stems from adolescent changes in cognitive functions subserved by the CC, reports of CC anomalies for a wide variety of childhood neuropsychiatric illnesses, and controversy regarding sexual dimorphism. 2. Characterization of the normal developmental pattern of the CC is hindered by enormous variability of its size. This is especially problematic for cross-sectional studies seeking to assess possible non-linear developmental curves. 3. To more accurately characterize developmental changes, a longitudinal brain magnetic resonance imaging study with subjects rescanned at approximately 2 year intervals was conducted resulting in 251 scans from 139 healthy children and adolescents. 4. Midsagittal area of the CC, especially the posterior regions, increased robustly from ages 5 to 18 years. 5. Although the genu of the CC was significantly larger in males there were no sex differences in mean area after adjustment for total cerebral volume and the growth patterns did not differ between sexes. 6. Analysis revealed a non-linear increase in the splenium, the most posterior region, with increases greatest in the younger years. 7. The results of this longitudinal study, in addition to confirming and extending previous cross-sectional reports, provide an increasingly accurate yardstick from which to assess pathological development.

Oncocytic nodule. An unusual case of a submaxillary gland mass in an elderly patient.

A submaxillary gland mass in an elderly woman was diagnosed as an oncocytic nodule by cutting needle biopsy and was followed with serial fine needle aspiration (FNA) biopsy for seven years. All specimens showed pure populations of oncocytes. Oncocytic nodules of the salivary gland are unusual lesions that may represent hyperplastic proliferations or true neoplasms. Although oncocytic metaplasia is commonly identified in the salivary glands of elderly patients, oncocytes rarely form masses that are targets for needle biopsy. This case suggests that FNA biopsy may be a useful method of evaluating salivary gland lesions in elderly patients who are not candidates for surgery.