The molecular cloning and characterization of potential chick DM-GRASP homologs in zebrafish and mouse

A full-length zebrafish cDNA clone and a partial mouse cDNA clone similar to chick DM-GRASP were isolated and analyzed. The nucleotide sequence of the full-length zebrafish clone shares 54% identity, and predicts 39% amino acid identity, with chick DM-GRASP. The partial mouse clone shares 76% nucleotide identity, and predicts 76% amino acid identity, with chick DM-GRASP. The predicted proteins encoded by both of these clones exhibit conserved structural domains that are characteristic of the chick protein. These features may identify them as a distinct subfamily within the immunoglobulin superfamily of cell adhesion molecules. Express of the zebrafish DM-GRASP protein is similar to chick DM-GRASP and is principally restricted to a small subset of developing sensory and motor neurons during axonogenesis. Zebrafish DM-GRASP expression was temporally regulated and limited to specific axon domains. This regional expression correlated with fasciculated axon domains. These results suggest that the zebrafish and mouse cDNA clones represent the respective fish and mammalian homologs of thick DM-GRASP. The highly selective expression of zebrafish DM-GRASP suggests that it is involved in the selective fasciculation and guidance of axons along their normal pathways. 1994 John Wiley & Sons, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/50085/1/480250708_ftp.pd

Diverse genetic subtypes of HIV-1 among female sex workers in Ibadan, Nigeria

Genetic diversity is the hallmark of HIV-1 infection. It differs among geographical regions throughout the world. This study was undertaken to identify the predominant HIV-1 subtypes among infected female sex workers (FSWs) in Nigeria. Methods: Two hundred and fifty FSWs from brothels in Ibadan Nigeria were screened for HIV antibody using ELISA. All reactive samples were further tested by the Western Blot Techniques. Peripheral Blood Mononuclear Cells (PBMCs) were separated from the blood samples of each subject. Fragments of HIV Proviral DNA was amplified and genetic subtypes of HIV-1 was determined by direct sequencing of the env and gag genes of the viral genome followed by phylogenetic analysis . Results: The age of the FSWs ranged from 15 to 55 years old (Mean = 25.8years, SD =3.74). Majority were Nigerians while others (1.6 %) were from neighboring West Africa countries. Four ( 1.6% ) of the FSWs were active for less than one year as sex workers, and the mean length of sex work was 2.80 years ( Range = 1.0 – 15.0 years ). Sixty-four (25.6%) of the 250 CSWs were positive for HIV-1 while 7 (2-8%) had dual infections to HIV-1 / HIV-2. Among the 34 HIV-1 strains  characterized by sequencing, 19 (55-9%) were subtype G, 9 (26.5%) CRF02_A/G, 3 (8.8%) CRF06_cpx while 1 (2.9%) each were identified as subtype C, CRF01_A/E and CRF09_cpx respectively. Nineteen (55.9%) of the FSWs with subtype G had been active in the sex work for between one to five years. The youngest of the HIV -1 infected FSWs with sexual activity of less than a year had subtype G strain. There is a significant probability that infection with this subtype occurred with a short incubation period (p< 0.05). Conclusion: This study showed a wide range of HIV- 1 subtypes among FSWs in Nigeria. The situation poses serious challenge for the design of HIV vaccine candidate for use in Nigeria.Keywords: Diverse, HIV, subtypes, Female Sex workers and Vaccin

Theory of Thermoelectric Power in High-Tc Superconductors

We present a microscopic theory for the thermoelectric power (TEP) in high-Tc cuprates. Based on the general expression for the TEP, we perform the calculation of the TEP for a square lattice Hubbard model including all the vertex corrections necessary to satisfy the conservation laws. In the present study, characteristic anomalous temperature and doping dependences of the TEP in high-Tc cuprates, which have been a long-standing problem of high-Tc cuprates, are well reproduced for both hole- and electron-doped systems, except for the heavily under-doped case. According to the present analysis, the strong momentum and energy dependences of the self-energy due to the strong antiferromagnetic fluctuations play an essential role in reproducing experimental anomalies of the TEP.Comment: 5 pages, 8 figures, to appear in J. Phys. Soc. Jpn. 70 (2001) No.10. Figure 2 has been revise

The Role of HIV/AIDS Prevention Campaigns on HIV Related Behavioural Changes in Ibadan, Nigeria

This study examined the impact of sources of AIDS education on HIV-related behavioural changes, and its implications for HIV prevention and service delivery in Nigeria. We analysed cross-sectional data obtained from a structured face-to-face interview with 1,373 respondents aged 15-50, who have ever had sex in Ibadan, Nigeria. Knowledge of HIV/AIDS, its route of transmission and prevention strategies was high.  About 20 % of the respondents were exposed to the AIDS prevention campaigns. A majority reported sexual behavioral changes, which included restriction of sex partners, use of condoms, sexual abstinence and avoidance of casual sex. Thirty-nine percent took some steps to reduce risk of infection by avoiding transfusion with unscreened blood and testing for HIV status.  Using multiple logistic regressions, the factors affecting the reported changes were identified. The application of health belief model shows that the model cannot wholly explain the changes in behavior. The role of female powerlessness in safer sex decision-making is noted. Despite the limitations of the study, the need for a sustained AIDS prevention campaign is stressed. The implications of the study for AIDS programs and research are highlighted

HIV subtype and drug resistance patterns among drug naïve persons in Jos, Nigeria

To determine HIV-1 subtypes and antiretroviral drug resistance mutations for 16 infected, pregnant women in Jos, Nigeria, part of pol (1040 bp) was amplified from patient PBMC DNA, sequenced andanalyzed. Eight of the samples were subtype G, three were CRF02_AG and 2 were unique recombinant forms (URF) between G and CRF02_AG. The remaining consisted of 3 different strains: one was subtypeC, and the other 2 were unrelated URF. Nearly full-length genome sequences were completed for 6 of the strains: 4 subtype G and 2 CRF02_AG. In the 14 drug-naïve subjects, no primary resistance-associated mutations were found, but secondary mutations were identified in 7 different codons of the gene coding for protease: PR K20I, M36I, L63A/P/V, V82I, L10M/I and I93L. In addition, the K238R mutation was identified in the reverse transcriptase gene of 3 viruses. The PR K20I and M36I mutations occurred in all of the strains, and the L10M and V82I mutations occurred only in subtype G. The mutation, I93L, was carried by subtype C viruses. Two of the women that had prior niverapine treatment, had primary resistance-associated mutations, RT M184V and K103N, archived in their proviral DNA several months after treatment cessation. The study reports a predominance of clade G and CRF02_AG, and provides many more examples of nearly full-length genome sequences for subtype G viruses from Nigeria. The ubiquitous presence of PI secondary resistance-associated mutations, as well as primary resistanceassociatedmutations in 2 previously treated women, underscores the need to ensure adherence compliance to treatment

Discrete Painlevé equations from Y-systems

We consider T-systems and Y-systems arising from cluster mutations applied to quivers that have the property of being periodic under a sequence of mutations. The corresponding nonlinear recurrences for cluster variables (coefficient-free T-systems) were described in the work of Fordy and Marsh, who completely classified all such quivers in the case of period 1, and characterized them in terms of the skew-symmetric exchange matrix B that defines the quiver. A broader notion of periodicity in general cluster algebras was introduced by Nakanishi, who also described the corresponding Y-systems, and T-systems with coefficients. A result of Fomin and Zelevinsky says that the coefficient-free T-system provides a solution of the Y-system. In this paper, we show that in general there is a discrepancy between these two systems, in the sense that the solution of the former does not correspond to the general solution of the latter. This discrepancy is removed by introducing additional non-autonomous coefficients into the T-system. In particular, we focus on the period 1 case and show that, when the exchange matrix B is degenerate, discrete Painlev\'e equations can arise from this construction

Electrical Conductivity of Fermi Liquids. I. Many-body Effect on the Drude Weight

On the basis of the Fermi liquid theory, we investigate the many-body effect on the Drude weight. In a lattice system, the Drude weight $D$ is modified by electron-electron interaction due to Umklapp processes, while it is not renormalized in a Galilean invariant system. This is explained by showing that the effective mass $m'$ for $D\propto n/m'$ is defined through the current, not velocity, of quasiparticle. It is shown that the inequality $D>0$ is required for the stability against the uniform shift of the Fermi surface. The result of perturbation theory applied for the Hubbard model indicates that $D$ as a function of the density $n$ is qualitatively modified around half filling $n\sim 1$ by Umklapp processes.Comment: 20 pages, 2 figures; J. Phys. Soc. Jpn. Vol.67, No.

Evolution of Hall coefficient in two-dimensional heavy fermion CeCoIn5_5

We report on the pressure dependence of the Hall coefficient $R_H$ in quasi-2D heavy fermion CeCoIn$_5$. At ambient pressure, below a temperature associated with the emergence of non-Fermi liquid properties, $R_H$ is anomalously enhanced. We found that the restoration of the Fermi liquid state with applied pressure leads to a gradual suppression of this dramatic enhancement. Moreover, the enhancement in $R_H$ was found to be confined to an intermediate temperature window, where inelastic electron-electron scattering is dominant. Our results strongly support the presence of cold and hot spots on the Fermi surface probably due to anisotropic scattering by antiferromagnetic fluctuations, which may also prove relevant for the debate on the anomalous normal-state properties of high-$T_c$ cuprates.Comment: 9 pages, 5 fiqures, to be published in J. Phys. Soc. Jp

Cyclotron Resonance in the Layered Perovskite Superconductor Sr2RuO4

We have measured the cyclotron masses in Sr2RuO4 through the observation of periodic-orbit-resonances - a magnetic resonance technique closely related to cyclotron resonance. We obtain values for the alpha, beta and gamma Fermi surfaces of (4.33+/-0.05)me, (5.81+/-0.03)me and (9.71+/-0.11)me respectively. The appreciable differences between these results and those obtained from de Haas- van Alphen measurements are attributable to strong electron-electron interactions in this system. Our findings appear to be consistent with predictions for a strongly interacting Fermi liquid; indeed, semi-quantitative agreement is obtained for the electron pockets beta and gamma.Comment: 4 pages + 3 figure