Polymorphic Alu insertions and the Asian origin of Native American populations

A rapid PCR-based assay was used to study the distribution of 5 polymorphic Alu insertions in 895 unrelated individuals from 30 populations, 24 from North, Central, and South America. Although a significant level of interpopulation variability was detected, the variability was less than that observed in a worldwide population survey. This is consistent with the bottleneck effect and genetic drift forces that may have acted on the migrating founder groups. The results corroborate the Asian origin of native American populations but do not support the multiple-wave migration hypothesis supposedly responsible for the tri-partite Eskaleut, Nadene, and Amerind linguistic groups. Instead, these populations exhibit three major identifiable clusters reflecting geographic distribution. Close similarity between the Chinese and native Americans suggests recent gene flow from Asia.     

Tumor-induced suppression of T lymphocyte proliferation coincides with inhibition of Jak3 expression and IL-2 receptor signaling: role of soluble products from human renal cell carcinomas

The proliferative capacity of T cells infiltrating human tumors is known to be impaired, possibly through their interaction with tumor. Here we demonstrate that soluble products derived from renal cell carcinoma (RCC-S) explants but not normal kidney can inhibit an IL-2-dependent signaling pathway that is critical to T cell proliferation. A major target of the immunosuppression was the IL-2R-associated protein tyrosine kinase, Janus kinase 3 (Jak3). RCC-S suppressed basal expression of Jak3 and its increase following stimulation with anti-CD3/IL-2. Jak3 was most sensitive to suppression by RCC-S; however, reduction in expression of p56(lck), p59(fyn), and ZAP-70 was observed in some experiments. Expression of other signaling elements linked to the IL-2R (Jak1) and the TCR (TCR-zeta, CD3-epsilon, and phospholipase C-gamma) were minimally affected. In naive T cells, RCC-S also partially blocked induction of IL-2R alpha-, beta- and gamma-chain expression when stimulating via the TCR/CD3 complex with anti-CD3 Ab. To determine whether RCC-S suppressed IL-2-dependent signaling, primed T cells were employed since RCC-S had no effect on IL-2R expression but did down-regulate Jak3 expression and, to a lesser degree, p56(lck) and p59(fyn). Reduction in Jak3 correlated with impaired IL-2-dependent proliferation and signal transduction. This included loss of Jak1 kinase tyrosine phosphorylation and no induction of the proto-oncogene, c-Myc. These findings suggest that soluble products from tumors may suppress T cell proliferation through a mechanism that involves down-regulation of Jak3 expression and inhibition of IL-2-dependent signaling pathways.     

Mice lacking osteopontin show normal development and bone structure but display altered osteoclast formation in vitro

We have used homologous recombination in embryonic stem cells to generate mice with a targeted disruption of the osteopontin (Opn, or Spp1, for secreted phosphoprotein 1) gene. Mice homozygous for this disruption fail to express osteopontin (OPN) as assessed at both the mRNA and protein level, although an N-terminal fragment of OPN is detectable at extremely low levels in the bones of -/- animals. The Opn -/- mice are fertile, their litter size is normal, and they develop normally. The bones and teeth of animals not expressing OPN are morphologically normal at the level of light and electron microscopy, and the skeletal structure of young animals is normal as assessed by radiography. Ultrastructurally, proteinaceous structures normally rich in OPN, such as cement lines, persist in the bones of the Opn-/- animals. Osteoclastogenesis was assessed in vitro in cocultures with a feeder layer of calvarial osteoblast cells from wild-type mice. Spleen cells from Opn-/- mice cells formed osteoclasts 3- to 13-fold more frequently than did control Opn+/+ cells, while the extent of osteoclast development from Opn -/- bone marrow cells was about 2- to 4-fold more than from the corresponding wild-type cells. Osteoclast development occurred when Opn-/- spleen cells were differentiated in the presence of Opn-/-osteoblasts, indicating that endogenous OPN is not required for this process. These results suggest that OPN is not essential for normal mouse development and osteogenesis, but can modulate osteoclast differentiation.     

Osteopontin expression in mammary gland development and tumorigenesis

Osteopontin (OPN) is a secreted phosphoprotein that binds to cells via an Arg-Gly-Asp sequence and to mineralized surfaces. The protein can mediate cell adhesion and is strongly implicated in transformation and tumorigenesis. We have examined the expression pattern of OPN in mouse mammary glands at different stages of postnatal development. Whereas OPN is expressed at low-to-moderate levels in mammary glands from virgin and pregnant mice, the levels of OPN mRNA are extremely high in the lactating gland, consistent with the presence of the protein in milk. Expression is highest at 2 days of lactation and declines thereafter, but it remains high through involution. OPN expression is restricted to small nests or groups of cells at 9 days of involution. These results suggest that OPN may play a specific role in the process of involution that may be distinct from its role during lactation. In mammary tumors arising spontaneously in transgenic mice expressing the oncogenes c-myc and/or v-Ha-ras under the control of the mouse mammary tumor virus promoter, the level of OPN expression is increased dramatically over that in the normal gland in these same animals. Numerous cells expressing OPN mRNA are widespread throughout the tumors. OPN protein is detectable by Western blotting in extracts from the mammary gland at 2 days of lactation and from the tumors, but not in mammary glands at other stages of development. We hypothesize that OPN is exported from most tissues and that the protein is only detectable in tissues elaborating fluids, such as the lactating mammary gland, or in pathological situations when expression of OPN is abnormally high, such as in tumors.     

Understanding phylogenies in biology: The influence of a Gestalt perceptual principle.

Cladograms, hierarchical diagrams depicting evolutionary histories among (groups of) species, are commonly drawn in 2 informationally equivalent formats--tree and ladder. The authors hypothesize that these formats are not computationally equivalent because the Gestalt principle of good continuation obscures the hierarchical structure of ladders. Experimental results confirmed that university students (N = 44) prefer to subdivide ladders in accordance with good continuation rather than with the underlying hierarchical structure. Two subsequent experiments (N = 164) investigated cladogram understanding by examining students' ability to translate between formats (e.g., from tree to ladder). As predicted, students had greater difficulty understanding ladders than trees. This effect was larger for students with weaker backgrounds in biology. These results have important implications for evolution education reform. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A randomized prospective controlled trial of oral acyclovir versus oral ganciclovir for cytomegalovirus prophylaxis in high-risk kidney transplant recipients

BACKGROUND: Posttransplantation cytomegalovirus (CMV) infection remains a significant cause of morbidity in kidney transplant recipients. We performed a randomized prospective controlled trial of oral acyclovir versus oral ganciclovir for CMV prophylaxis in a group of renal allograft recipients considered at high risk for CMV disease due to the use of OKT3 induction therapy. METHODS: A total of 101 recipients of cadaveric (83) and zero haplotype-matched live donor (18) kidney transplants were entered into the trial. A total of 22 D-R- patients received no prophylaxis. Twenty-seven D+R-, 29 D+R+, and 23 D-R+ patients were randomized to receive 3 months of either oral acyclovir (800 mg q.i.d.) or oral ganciclovir (1000 mg t.i.d.). Doses were adjusted according to the level of renal function. The D+R- patients were also given CMV immune globulin biweekly for 16 weeks. Surveillance blood cultures were obtained at transplantation, at months 1, 2, 3, and 6, and when clinically indicated. The primary study end points were time to CMV infection and disease the first 6 months after transplantation. RESULTS: The mean follow up was 14.4 months. Both agents were well tolerated, and no drug interruptions for toxicity occurred. CMV was isolated in 14 of 39 (35.9%) acyclovir-treated and 1 of 40 (2.5%) ganciclovir-treated recipients by 6 months (P=0.0001). Symptomatic CMV disease occurred in 9 of 14 (64%) of the acyclovir patients, two with tissue-invasive disease. Infection rates for acyclovir vs. ganciclovir, respectively, stratified by CMV serology were: D+R-, 54 vs. 0%, P=0.0008; D+R+, 43 vs. 6.6%, P=0.01; D-R+, 8.3 vs. 0%, P=NS. No patient developed CMV infection while taking oral ganciclovir, however three delayed infections occurred 2-7 months after finishing therapy. Each patient had been previously treated for acute rejection. CONCLUSIONS: Oral acyclovir provides effective CMV prophylaxis only for recipients of seronegative donor kidneys. Oral ganciclovir is a superior agent providing effective CMV prophylaxis for recipients of seropositive donor kidneys. Recipients who are treated for acute rejection are at risk for delayed CMV infection during the first posttransplantation year.     

Structure-activity analysis of synthetic autoinducing thiolactone peptides from Staphylococcus aureus responsible for virulence

The synthesis of virulence factors and other extracellular proteins responsible for pathogenicity in Staphylococcus aureus is under the control of the agr locus. A secreted agr-encoded peptide, AgrD, processed from the AgrD gene product, is known to be an effector of self-strain activation and cross-strain inhibition of the agr response. Biochemical analysis of AgrD peptides isolated from culture supernatants has suggested that they contain an unusual thiol ester-linked cyclic structure. In the present work, chemical synthesis is used to confirm that the mature AgrD peptides contain a thiolactone structure and that this feature is absolutely necessary for full biological activity. The AgrD synthetic thiolactone peptides exhibited biological activity in vivo in a mouse protection test. Structure-activity studies have allowed key aspects of the peptide structure involved in the differential activation and inhibition functions to be identified. Accordingly, we propose a model for activation and inhibition of the agr response in which the former, but not the latter, involves specific acylation of the agr transmembrane receptor, AgrC.     

Efficacy of multimodality therapy in advanced renal cell carcinoma

OBJECTIVES: The integration of systemic biologic response modifier (BRM) therapy and surgery to treat metastatic renal cell carcinoma (RCC) is an evolving approach. The purpose of this study was to evaluate the efficacy of this form of multimodality therapy in patients with metastatic RCC. METHODS: Between 1988 and 1996, 14 patients at our institution underwent initial BRM therapy followed by surgical resection of primary and metastatic RCC lesions. Patient records were reviewed to determine the response to BRM therapy, progression-free survival rate, and overall survival rate. The mean follow-up for the entire group was 43.5 months. RESULTS: After BRM therapy, 9 patients manifested an objective response and 5 patients had stable disease. All patients were then rendered disease-free by surgical excision of residual or recurrent metastatic lesions and the primary tumor. The cancer-specific survival rate at 3 years was 81.5%. Currently, 7 patients are alive and disease-free (mean follow-up 41.4 months), 3 patients are alive with recurrent disease (mean survival 48.3 months), 3 patients died of metastatic disease (mean survival 27.9 months), and 1 patient died of an unrelated cause 54.4 months after therapy. CONCLUSIONS: The results of this study suggest that adjunctive surgery after BRM therapy can extend the survival of selected patients with metastatic RCC. Aggressive surgical resection of stable or responding lesions after BRM therapy should be considered in the management of these patients.