Role of the domestic chicken (Gallus gallus) in the epidemiology of urban visceral leishmaniasis in Brazil

Zoonotic visceral leishmaniasis (ZVL) is a serious public health problem in several Brazilian cities. Although the proximity of chicken houses is often cited as a risk factor in studies of urban ZVL, the role chickens play in the epidemiology of the disease has not been defined. Chickens attract both male and female sand flies (Lutzomyia longripalpis) but are unable to sustain Leishmania infections, and their presence may exert a zooprophylactic effect. We discuss environmental, physiologic, socioeconomic, and cultural factors related to chicken raising that could influence Le. infantum transmission in Brazilian cities and evaluate whether this practice significantly affects the risk of acquiring ZVL.

Remitting behaviour of Nepalese rural-to-urban migrants: Implications for theory and policy

This article uses data for Nepal to test contemporary hypotheses about the remitting behaviour and associated motives of rural-to-urban migrants and to consider the likely impact of such remittances on rural development. Possibilities for inheritance, degree of family attachment, likelihood of eventual return to place of origin and family investment in the education of the migrants are found to be significant influences on levels of remittances by Nepalese migrants. However, in Nepal, remittances do not seem to result in long-term capital investment in rural areas and so may not promote long-term development of these areas.

Current concepts in central nervous system regeneration

A dictum long-held has stated that the adult mammalian brain and spinal cord are not capable of regeneration after injury. Recent discoveries have, however, challenged this dogma. In particular, a more complete understanding of developmental neurobiology has provided an insight into possible ways in which neuronal regeneration in the central nervous system may be encouraged. Knowledge of the role of neurotrophic factors has provided one set of strategies which may be useful in enhancing CNS regeneration. These factors can now even be delivered to injury sites by transplantation of genetically modified cells. Another strategy showing great promise is the discovery and isolation of neural stem cells from adult CNS tissue. It may become possible to grow such cells in the laboratory and use these to replace injured or dead neurons. The biological and cellular basis of neural injury is of special importance to neurosurgery, particularly as therapeutic options to treat a variety of CNS diseases becomes greater. (C) 2002 Published by Elsevier Science Ltd.

Axonal regeneration of retinal ganglion cells after optic nerve pre-lesions and attachment of normal or pre-degenerated peripheral nerve grafts

Axonal regeneration of retinal ganglion cells (RGCs) into a normal or pre-degenerated peripheral nerve graft after an optic nerve pre-lesion was investigated. A pre-lesion performed 1-2 weeks before a second lesion has been shown to enhance axonal regeneration in peripheral nerves (PN) but not in optic nerves (ON) in mammals. The lack of such a beneficial pre-lesion effect may be due to the long delay (1-6 weeks) between the two lesions since RGCs and their axons degenerate rapidly 1-2 weeks following axotomy in adult rodents. The present study examined the effects of the proximal and distal ON pre-lesions with a shortened delay (0-8 days) on axonal regeneration of RGCs through a normal or pre-degenerated PN graft. The ON of adult hamsters was transected intraorbitallv at 2 mm. (proximal lesion) or intracranially at 7 mm (distal lesion) from the optic disc. The pre-lesioned ON was re-transected at 0.5 mm from the disc after 0, 1, 2, 4, or 8 days and a normal or a pre-degenerated PN graft was attached onto the ocular stump. The number of RGCs regenerating their injured axons into the PN graft was estimated by retrograde labeling with FluoroGold 4 weeks after grafting. The number of regenerating RGCs decreased significantly when the delay-time increased in animals with both the ON pre-lesions (proximal or distal) compared to control animals without an ON pre-lesion. The proximal ON pre-lesion significantly reduced the number of regenerating RGCs after a delay of 8 days in comparison with the distal lesion. However, this adverse effect can be overcome, to some degree, by a pre-degenerated PN graft applied 2, 4, or 8 days after the distal ON pre-lesion enhanced more RGCs to regenerate than the normal PN graft. Thus, in order to obtain the highest number of regenerating RGCs, a pre-degenerated PN should be grafted immediately after an ON lesion.

Some new killing trick: Welfare reform and drug markets in a U.S. urban ghetto

Ethnographic data collected over a 5-year period is analyzed to determine how the Personal Responsibility & Work Opportunity Reconciliation Act of 1996 (PRWORA) has affected the lives of young male drug dealers from AIDS-afflicted families residing in Detroit. The data analysis indicated that the participants perceived drug dealing as the only viable employment opportunity for meeting the quotidian & health care needs of their families. The findings also revealed that the participants were highly aware of local political processes & the necessities of caring for relatives living with AIDS. Additional attention is dedicated to exploring the state of MI's rationale for ending the General Assistance Program, the sociocultural foundations of the PRWORA, various stipulations of the PRWORA, & how the PRWORA has augmented the legal vulnerability of welfare recipients. It is concluded that the PRWORA will force many welfare recipients to engage in illicit activities & will generally decrease recipients' health. 59 References. J. W. Parker

Tissue engineering for bone regeneration using differentiated alveolar bone cells in collagen scaffolds

Regeneration of osseous defects by a tissue-engineering approach provides a novel means of treatment utilizing cell biology, materials science, and molecular biology. In this study the concept of tissue engineering was tested with collagen type I matrices seeded with cells with osteogenic potential and implanted into sites where osseous damage had occurred. Explant cultures of cells from human alveolar bone and gingiva were established. When seeded into a three-dimensional type I collagen-based scaffold, the bone-derived cells maintained their osteoblastic phenotype as monitored by mRNA and protein levels of the bone-related proteins including bone sialoprotein, osteocalcin, osteopontin, bone morphogenetic proteins 2 and 4, and alkaline phosphatase. These in vitro-developed matrices were implanted into critical-size bone defects in skulls of immunodeficient (SCID) mice. Wound healing was monitored for up to 4 weeks. When measured by microdensitometry the bone density within defects filled with osteoblast-derived matrix was significantly higher compared with defects filled with either collagen scaffold alone or collagen scaffold impregnated with gingival fibroblasts. New bone formation was found at all the sites treated with the osteoblast-derived matrix at 28 days, whereas no obvious new bone formation was identified at the same time point in the control groups. In situ hybridization for the human-specific Alu gene sequence indicated that the newly formed bone tissue resulted from both transplanted human osteoblasts and endogenous mesenchymal stem cells. The results indicate that cells derived from human alveolar bone can be incorporated into bioengineered scaffolds and synthesize a matrix, which on implantation can induce new bone formation.