Population genetic implications from sequence variation in four Y chromosome genes

Some insight into human evolution has been gained from the sequencing of four Y chromosome genes. Primary genomic sequencing determined gene SMCY to be composed of 27 exons that comprise 4,620 bp of coding sequence. The unfinished sequencing of the 5' portion of gene UTY1 was completed by primer walking, and a total of 20 exons were found. By using denaturing HPLC, these two genes, as well as DBY and DFFRY, were screened for polymorphic sites in 53-72 representatives of the five continents. A total of 98 variants were found, yielding nucleotide diversity estimates of 2.45 x 10(-5), 5. 07 x 10(-5), and 8.54 x 10(-5) for the coding regions of SMCY, DFFRY, and UTY1, respectively, with no variant having been observed in DBY. In agreement with most autosomal genes, diversity estimates for the noncoding regions were about 2- to 3-fold higher and ranged from 9. 16 x 10(-5) to 14.2 x 10(-5) for the four genes. Analysis of the frequencies of derived alleles for all four genes showed that they more closely fit the expectation of a Luria-Delbrück distribution than a distribution expected under a constant population size model, providing evidence for exponential population growth. Pairwise nucleotide mismatch distributions date the occurrence of population expansion to approximately 28,000 years ago. This estimate is in accord with the spread of Aurignacian technology and the disappearance of the Neanderthals.

Variation in in-patient stroke management in ten centres in different countries: the INCLEN multicentre stroke collaboration

BACKGROUND AND PURPOSE

Large within-country variations have been described in stroke management and there have been a few studies of between-country variation (in the USA and the UK). We designed a study to examine stroke management across a wide range of countries representing different stages of economic development. Large variations would suggest the need to explore methods of increasing the uptake of evidence-based stroke practice.

METHODS

Members of the International Clinical Epidemiology Network (INCLEN) from 14 centres in ten countries agreed to review the records of the last 50 patients admitted to hospital with a clinical diagnosis of stroke. Information on demographic variables, the clinical diagnosis of stroke type, investigations performed and treatments given and the discharge destination of the patient were recorded and sent to the coordinating centre in Australia for analysis.

RESULTS

There were statistically significant between-centre differences in the proportions of patients cared for by a neurologist, staying in hospital for at least ten days and having CT or MRI scans. Significant between-centre differences were also seen for treatment, for example, the use of aspirin in non-haemorrhagic stroke varied from 11 to 79%. The variation (for all interventions studied) was no longer statistically significant when examined within strata according to availability of facilities.

CONCLUSIONS

The large variation between centres in the management of stroke is largely 'explained' by the availability of resources, even for interventions that do not depend on resource availability. It will be important to develop management guidelines that reflect evidence-based practice of relevance across a range of economic settings.

Regional studies of serotonin and dopamine metabolism and quantification of serotonin uptake sites in human cerebral cortex

An increasing number of studies have indicated that neuronal metabolism of serotonin (5-HT) and other monoamines may be altered in patients with affective disorders and in completed suicides. However, studies have yielded discordant results. The purpose of this study was to determine the regional variation of 5-hydroxyindolacetic acid (5-HIAA), homovanillic acid (HVA), (5-HT) and 5-HT uptake sites within the human cerebral cortex. Our sample consisted of 19 patients who died suddenly and accidently. Cortical concentrations of 5-HIAA, HVA and 5-HT were measured in six regions using an HPLC. 5-HT uptake sites in cortex were examined using [3H]-Paroxetine. 5-HT values within each brain were fairly constant in cortical regions studied except for the posterior parietal areas. By contrast, 5-HIAA values showed a trend towards a rostro-caudal increase, with peak values seen at sections corresponding to the post-central gyrus and the occipital pole. Using the ratio of 5-HIAA/5-HT as a crude index of 5-HT turnover, there was a progressive rostro-caudal increase of values which achieved statistical significance: the posterior superior parietal area and the occipital pole displayed a greater ratio than the other four cortical regions. HVA values were highest in the pre-central region and decreased both rostrally and caudally. 5-HIAA and HVA values were correlated positively in 5 of 6 cortical areas, while 5-HIAA and 5-HT were correlated in areas 4 and 5. Results obtaining using [3H]-Paroxetine suggest that 5-HT uptake sites in the human cortex are distributed rather uniformally and are not correlated with 5-HT levels.

A monoclonal IgA in a patient with amyotrophic lateral sclerosis reacts with neurofilaments and surface antigen on neuroblastoma cells

A 75-year-old woman had breast carcinoma, an IgA paraprotein and autopsy-proven amyotrophic lateral sclerosis. Autopsy tissues showed immune-reactive IgA within surviving motor neurons and deposits of IgA and C3 within renal glomeruli. By indirect immunofluorescence, the patient's serum contained high-titer IgA that bound to axons and to the perikarya of nerve cells in central and peripheral nervous system. The IgA paraprotein reacted with the 200 kDa, high molecular weight subunit of neurofilament protein (NFH) in Western blots of purified neurofilaments. It also reacted with dephosphorylated NFH and with NFH expressed as a fusion protein in E. coli, suggesting that the autoantibody recognized a peptide epitope. The IgA crossreacted with a surface antigen of cultured human neuroblastoma cells but mouse monoclonal antibodies to NFH did not. Absorption of the patient's serum with neurofilaments eliminated IgA binding to neuroblastoma cells, indicating that the same antibodies bound to both determinants. The IgA paraprotein seems to be an autoantibody with specificity for neurofilament protein and a cell surface component of neuronal cells; the antibody may have been important in the pathogenesis of neuronal degeneration.

Changes in excitatory amino acid modulation of phosphoinositide metabolism during development

Two different developmental patterns of stimulation of phosphoinositide (PI) metabolism by excitatory amino acid (EAA) receptors were observed during the postnatal maturation of various brain regions. A 'burst' in PI metabolism was seen at postnatal day 6 (PND6) in olfactory bulb and cerebellum and at PND9 in hippocampus. In cortex and thalamus/hypothalamus high levels of PI metabolism were observed initially, and then began to decline at PND15 and PND18, respectively. NMDA inhibition of PI metabolism was generally found to parallel the EAA activation but the persistence of inhibition varied in the different brain regions.