Ecological and temporal placement of early Pliocene hominids at Aramis, Ethiopia

Sedimentary deposits in the Middle Awash research area of Ethiopia's Afar depression have yielded vertebrate fossils including the most ancient hominids known. Radioisotopic dating, geochemical analysis of interbedded volcanic ashes and biochronological considerations place the hominid-bearing deposits at around 4.4 million years of age. Sedimentological, botanical and faunal evidence suggests a wooded habitat for the Aramis hominids.     

DNA damage and cell cycle checkpoints

DNA is prone to numerous forms of damage that can injure cells and impair fitness. Cells have evolved an array of mechanisms to repair these injuries. Proliferating cells are especially vulnerable to DNA damage due to the added demands of cellular growth and division. Cell cycle checkpoints represent integral components of DNA repair that coordinate cooperation between the machinery of the cell cycle and several biochemical pathways that respond to damage and restore DNA structure. By delaying progression through the cell cycle, checkpoints provide more time for repair before the critical phases of DNA replication, when the genome is replicated, and of mitosis, when the genome is segregated. Loss or attenuation of checkpoint function may increase spontaneous and induced gene mutations and chromosomal aberrations by reducing the efficiency of DNA repair. Defects in checkpoint control have been seen in certain hereditary cancer syndromes and at early stages of cell transformation. Mutations in checkpoint control genes therefore may contribute to the genetic instability that appears to drive neoplastic evolution.     

Use of vinorelbine in non-small-cell lung cancer. Provincial Lung Disease Site Group

The best known of the nation's welfare programs, Aid to Families with Dependent Children (AFDC), has from its inception reflected a tension between the desire to support children in poor, lone-parent families and the belief that parents should be held responsible for providing for themselves and their children. Against that backdrop, this article reviews the history of the AFDC program and traces the emergence of policies and programs intended to encourage employment of the parents (almost exclusively mothers) who receive benefits. The article examines in detail the Work Incentive Program (WIN) launched in 1967 and the Family Support Act of 1988, comparing these to each other and to the outlines of welfare reform signed into law in 1996. The article emphasizes the importance of sustained attention to the implementation of policy goals in concrete programs and shows that the merits of those early programs have not been fully tested because they were never funded or implemented at the scale intended. The article also outlines ways in which welfare-to-work programs can be used to assist children as well as parents, and urges that children's well-being remain the core purpose of welfare policy.     

Phenotype and genotype of advanced premalignant head and neck lesions after chemopreventive therapy

BACKGROUND: The goal of chemoprevention is to reduce the risk of cancer development by reversing or blocking the tumorigenic process through the use of pharmacologic or natural agents. To determine the potential role of genetic alterations in assessing cancer risk and in evaluating the efficacy of chemopreventive agents, we studied 22 patients with advanced premalignant lesions of the head and neck who were part of a prospective cancer prevention trial that is investigating a regimen of 13-cis-retinoic acid, interferon alfa, and alpha-tocopherol administered for 12 months or until disease progression. METHODS: We used polymerase chain reaction analysis of microsatellite DNA sequences in cells from precancerous lesions to determine the frequencies of genetic alterations--namely, loss of heterozygosity (LOH) and microsatellite instability--at chromosomal loci that are commonly deleted in head and neck cancer. RESULTS: Prior to treatment, 17 (81%) of 21, eight (44%) of 18, and eight (42%) of 19 patients who were informative (i.e., heterozygous) at chromosomes 9p21, 3p14, and 17p13, respectively, exhibited LOH in at least one of their lesion biopsy specimens. Among nine patients who exhibited LOH at chromosome 9p21 in pretreatment biopsy specimens and who had completed at least 5 months of therapy, the genetic loss persisted in eight--including three of the four patients who exhibited complete histologic responses (i.e., no evidence of dysplasia in their biopsy specimens). IMPLICATION: Our data suggest that clinical and histologic assessments of the response to chemopreventive agents may be insufficient to determine their efficacy and that critical genetic alterations could be used as independent biomarkers to augment the ability to evaluate the efficacy of such agents.     

A new enzyme immunoassay to detect antibodies to arboviruses in the blood of wild birds

A selective recruitment of eosinophils to sites of inflammation is claimed to be controlled by regulation of cytokines, chemokines and adhesion molecules. In animal models, eotaxin has been suggested to be a potent chemokine since it in cooperation with interleukin-5 induce selective chemotaxis and infiltration of eosinophils to lung tissue after an allergen provocation. We have investigated the in vitro effect of eotaxin on human peripheral blood eosinophils with respect to CD11b/CD18 expression and adhesion properties to the matrix protein fibronectin. We did not find any effect of eotaxin per se on CD11b/CD18 expression, neither on eosinophils from healthy subjects nor from patients with asymptomatic pollen related asthma. However, eotaxin significantly upregulated the quantitative level of CD11b/CD18 and increased the adhesion to fibronectin in eosinophils from healthy subjects preincubated in vitro with interleukin-5, but not in eosinophils preincubated with fMLP. Moreover, eosinophils harvested 24 hours after an in vivo allergen inhalation provocation in asthmatics, upregulated CD11b/CD18 after in vitro incubation with eotaxin alone.     

Spontaneous dissection of the internal carotid artery

The arteriographic diagnosis of spontaneous, nontraumatic dissection of the internal carotid artery was made in 19 patients and confirmed at operation in ten. The tapered narrowing beginning in or about the carotid bulb and ending at the bony canal was a consistent finding. Four patients had associated aneurysm formation. All but one patient developed an acute hemispheric neurologic deficit as the initial symptom. The deficit was transient in ten and prolonged in eight. The dissection occurred in the outer layers of the media. None of the surgical specimens showed atherosclerosis. Surgical methods of management included segmental resection and grafting, thrombectomy and intimectomy, dilation, and simple ligation. Considerable improvement of luminal diameter occurred in six of seven patients whose arteries were left undisturbed.     

Placental diffusing capacities at varied carbon monoxide tensions

To test the hypothesis that carbon monoxide transfer across the placenta is, in part, a facilitated process, we have looked for evidence of saturation kinetics for carbon monoxide. In eight pregnant ewes, fetal to maternal carbon monoxide transfer was examined in a preparation in which the fetal side of the placenta was perfused with blood. The carboxyhemoglobin concentrations on the fetal side of the placenta were varied from 4.8 to 70% in 23 measurements. At increased carbon monoxide tensions, the transfer from fetus to mother always decreased. The slope of log rate of carbon monoxide transfer vs. log partial pressure gradient across the placenta was significantly different from 1. Placental membrane diffusing capacity was calculated separately from total placental diffusing capacity which includes hemoglobin reaction rates and erythrocyte membrane diffusion. Placental membrane diffusing capacity decreased at increased carbon monoxide tensions. Placental permeability for urea did not change with increasing carbon monoxide tensions. These results are consistent with the hypothesis that carbon monoxide diffusion in the placenta is, in part, carrier mediated.