Cellular expression of somatostatin in MAM-induced microencephaly in the rat.

Methylazoxymethanol acetate (MAM) is a mitotic inhibitor that has been used to selectively destroy neuroblasts at specific times during gestation. The administration of MAM results in a dose-dependent microencephaly. Following MAM treatment at 15 days of gestation, we have noted an increase in the level of SS immunoreactivity in the neocortex, as determined by radioimmunoassay. Northern blot analysis for preproSS mRNA revealed an increase in MAM-treated cortex. The cellular distribution of SS has been determined using in situ hybridization and immunocytochemistry. There was a 30% increase in the density of SS-immunoreactive neurons in the cortex of the MAM-treated animals. These data suggest that SS neurons in the cortex are spared following MAM treatment at GD 15.     

Astigmatism and visual recovery after phacoemulsification and conventional extracapsular cataract extraction

In this study we wanted to investigate the post-operative astigmatism and visual acuity after phacoemulsification and conventional extracapsular cataract surgery. Patients operated between April and June 1993 (n=150) were retrospectively analyzed. The patients were examined prior to surgery and at day 1, at day 10, and in week 6 post-operatively. The difference between the post-operative log mean visual acuity in the Phaco group and in the CECCE group was significant after 1 and 10 days, however it was not significant (p=0.191) after 6 weeks. The mean astigmatism was significantly less in the Phaco group than in the CECCE group during the whole post-operative check-up period. This study suggests that Phaco results in a lower post-operative astigmatism and an earlier visual rehabilitation compared to the CECCE technique.Abbreviations Phaco Phacoemulsification - CECCE Conventional extracapsular cataract extraction     

Specific antibody responses to three schistosome-related carbohydrate structures in recently exposed immigrants and established residents in an area of Schistosoma mansoni endemicity

By the use of surface plasmon resonance spectroscopy, immunoglobulin G (IgG) subclass and IgM antibodies against three schistosome-derived carbohydrate structures, FLDN (Fucalpha1-3GalNAcbeta1-4GlcNAcbeta1-3Galalpha1), LDN-DF [GalNAcbeta1-4(Fucalpha1-2Fucalpha1-3)GlcNAcbeta1], and LDNF [GalNAcbeta1-4(Fucalpha1-3)GlcNAcbeta1-3Galalpha1], were measured in 184 previously unexposed Kenyan immigrants who moved into the Masongaleni area, where Schistosoma mansoni is endemic. They were sampled within their first year of exposure and again 2 years later. A cohort selected out of the original residents of the area, who had been exposed for many years, served as controls. Associations with responses to S. mansoni worm, egg (SEA), and cercarial (CERC) antigens were examined. In addition, we measured responses to keyhole limpet hemocyanin, a glycoprotein which carries glycan epitopes that are also expressed by schistosomes. Specific IgG1 responses were most pronounced against FLDN and LDN-DF and strongly associated with those previously measured to SEA and CERC. Similarly to previously published age profiles of IgG1 and IgG2 responses to SEA, levels of IgG1 against LDN-DF decreased with age. In contrast, specific IgM responses against the three schistosome-derived carbohydrate structures were most marked against LDNF. Our results indicate that, of the three glycan structures tested, the acute response against schistosome glycoconjugate antigens in young children is mainly directed against the LDN-DF epitope. The response to LDN-DF in older individuals and the responses to the two other epitopes were similar in the two cohorts, suggesting that these antigens are recognized in the early stages of infection and that the immune response persists. The biological significance of these observations needs further elucidation.     

Homozygosity mapping of achromatopsia to chromosome 2 using DNA pooling

Achromatopsia is an autosomal recessive disease of the retina, characterized clinically by an inability to distinguish colors, impaired visual acuity, nystagmus and photophobia. A genome-wide search for linkage was performed using an inbred Jewish kindred from Iran. To facilitate the genome-wide search, we utilized a DNA pooling strategy which takes advantage of the likelihood that the disease in this inbred kindred is inherited by all affected individuals from a common founder. Equal molar amounts of DNA from all affected individuals were pooled and used as the PCR template for short tandem repeat polymorphic markers (STRPs). Pooled DNA from unaffected members of the kindred was used as a control. A reduction in the number of alleles in the affected versus control pool was observed at several loci. Upon genotyping of individual family members, significant linkage was established between the disease phenotype and markers localized on chromosome 2. The highest LOD score observed was 5.4 (theta = 0). When four additional small unrelated families were genotyped, the combined peak LOD score was 8.2. Analysis of recombinant chromosomes revealed that the disease gene lies within a 30 cM interval which spans the centromere. Additional fine-mapping studies identified a region of homozygosity in all affected individuals, narrowing the region to 14 cM. A candidate gene for achromatopsia was excluded from this disease interval by radiation hybrid mapping. Linkage of achromatopsia to chromosome 2 is an essential first step in the identification of the disease-causing gene.      

Contralateral corticorubral fibers induced by neonatal lesions are not collaterals of the normal ipsilateral projection

Unilateral neonatal cortical ablation induces the development of a bilateral corticorubral projection from the remaining sensorimotor cortex. The retrograde fluorescent tracers Fast blue (FB) and Nuclear yellow (NY) were used to determine if the aberrant contralateral projection arises from axon collaterals of the normal uncrossed projection. Six to 8 weeks after unilateral cortical ablation in neonatal rats, the red nuclei were injected with FB on one side and NY on the other to study the source of the normal and aberrant afferents from the cerebral cortex. In control animals, many neurons in layer V of the sensorimotor cortex were retrogradely labeled with the tracer that had been injected into the ipsilateral red nucleus. In animals with unilateral ablations, many neurons throughout the remaining sensorimotor cortex were retrogradely labeled with FB or NY. No cortical neurons were doubly labeled. In addition to demonstrating the bilaterality of the corticorubral projection in animals which had received neonatal lesions, these results indicate that the aberrant contralateral corticorubral projection does not consist of axon collaterals of the normal ipsilateral fibers.     

Human NT2/D1 cells differentiate into functional astrocytes

As the most numerous cell type in the brain, astrocytes are coupled via gap junction channels. It is believed that communication among astrocytes is normally regulated by extracellular ions, neurotransmitters and neuromodulators. However, the level of astrocytic coupling is altered in abnormal conditions such as stroke, brain trauma and Alzheimer's disease. A well established human progenitor cell line, NT2/D1, has been previously differentiated into pure neuronal cultures. In the current study, for the first time, we report the differentiation of NT2/D1 cells into astrocytes, which express connexin43 and are coupled via gap junctions. Thus, human NT2/D1 cells are not merely committed neuronal progenitors but, similar to the embryonal stem cells, they can give rise to both lineages.     

The elderly as prophets

An understanding of the biological, psychological, and social factors of aging is just one part of helping older persons to view their own aging as the fulfillment of living, since spiritual growth takes place in the context of these factors but transcends them. Younger persons can facilitate such growth for themselves and their elders by helping the aging to function as "prophets" for the younger.