Human newborn autologous mixed lymphocyte response: frequency and phenotype of responders and xenoantigen specificity

The response of human newborn lymphocytes in autologous mixed lymphocyte culture was examined for specificity (by restimulation), responder cell phenotype, and responder cell frequency. When the newborn T cells were separated from non-T cells by rosetting with sheep erythrocytes (E) in fetal calf serum (FCS), approximately 1:20,000 T cells proliferated. These responders had specificity for E + FCS, were T4+, and were self-restricted. Significant numbers of responder T cells were not found when newborn T and non-T cells were separated by nylon wool. Responses in parallel autologous cultures of adult T cells showed that 1) adults had a higher frequency than newborns of E + FCS specific responders, 2) evidence for self specificity was lacking in restimulated cultures, and 3) occasional responses to antigen on the surface of monocytes could not be excluded.     

Monitoring signal transduction in cancer: cDNA microarray for semiquantitative analysis.

This study targeted the development of a novel microarray tool to allow rapid determination of the expression levels of 58 different tyrosine kinase (tk) genes in small tumor samples. The goals were to define a reference probe for multi-sample comparison and to investigate the variability and reproducibility of the image acquisition and RT-PCR procedures. The small number of tk genes on our arrays enabled us to define a reference probe by artificially mixing all genes on the arrays. Such a probe provided contrast reference for comparative hybridization of control and sample DNA and enabled cross-comparison of more than two samples against one another. Comparison of signals generated from multiple scanning eliminated the concern of photo bleaching and scanner intrinsic noise. Tests performed with breast, thyroid, and prostate cancer samples yielded distinctive patterns and suggest the feasibility of our approach. Repeated experiments indicated reproducibility of such arrays. Up- or downregulated genes identified by this rapid screening are now being investigated with techniques such as in situ hybridization.     

The total burden of rare,non-synonymous exome genetic variants is not associated with childhood or late-life cognitive ability

Human cognitive ability shows consistent, positive associations with fitness components across the life-course. Underlying genetic variation should therefore be depleted by selection, which is not observed. Genetic variation in general cognitive ability (intelligence) could be maintained by a mutation–selection balance, with rare variants contributing to its genetic architecture. This study examines the association between the total number of rare stop-gain/loss, splice and missense exonic variants and cognitive ability in childhood and old age in the same individuals. Exome array data were obtained in the Lothian Birth Cohorts of 1921 and 1936 (combined N = 1596). General cognitive ability was assessed at age 11 years and in late life (79 and 70 years, respectively) and was modelled against the total number of stop-gain/loss, splice, and missense exonic variants, with minor allele frequency less than or equal to 0.01, using linear regression adjusted for age and sex. In both cohorts and in both the childhood and late-life models, there were no significant associations between rare variant burden in the exome and cognitive ability that survived correction for multiple testing. Contrary to our a priori hypothesis, we observed no evidence for an association between the total number of rare exonic variants and either childhood cognitive ability or late-life cognitive ability.     

Permeability studies on liposomes formed from polymerizable diacetylenic phospholipids and their potential applications as drug delivery systems

We have investigated the permeability and entrapment characteristics of liposomes formed from a group of polymerizable phospholipids, containing diacetylenic groups in one or both of their acyl chains. Permeability was assessed by the release of an entrapped dye, 6-carboxyfluorescein. Diacetylenic phosphatidylcholine (PC) liposomes were found to exhibit a wide range of permeability properties, depending on: the nature of the diacetylenic lipid, i.e. mixed-chain (mc) or identical-chain (id), the extent of polymerisation, vesicle size, and cholesterol content. Ultraviolet-initiated polymerisation affected a significant decrease in the permeability of C25idPC liposomes. The increase in permeability of liposomes formed from four other diacetylenic lipids (C25mcPC, C23idPC, C23mcPC and C20idPC) after polymerisation was attributed to disturbances in the packing of lipid molecules, and/or the limited ability of small unilamellar vesicles to accommodate long polymers. The C20idPC lipid is atypical, forming irregular monomeric and polymeric vesicles. The permeability of C25idPC liposomes was also assessed by the release of [3H]inulin. C25idPC liposomes exhibited low permeabilities to [3H]inulin in their monomeric and polymeric states. Incubation of C25idPC liposomes in human plasma caused a substantial increase in the permeability of monomeric vesicles to both carboxyfluorescein and [3H]inulin. The permeability of polymerised C25idPC liposomes, however, was unaffected in the presence of plasma, with vesicles retaining most of their entrapped [3H]inulin after 50 h. These findings demonstrate that polymeric C25idPC liposomes exhibit high resistance to the destructive actions of plasma components, such as high-density lipoproteins (HDLs). Polymeric C25idPC liposomes may have an application in drug delivery systems.