Cross-national comparison of internal migration: issues and measures

Our objectives are to identify the issues that researchers encounter when measuring internal migration in different countries and to propose key indicators that analysts can use to compare internal migration at the 'national' level. We establish the benefits to be gained by a rigorous approach to cross-national comparisons of internal migration and discuss issues that affect such comparisons. We then distinguish four dimensions of internal migration on which countries can be compared and, for each dimension, identify a series of summary measures. We illustrate the issues and measures proposed by comparing migration in Australia and Great Britain.

GH treatment in adults with chronic liver disease: A randomized, double-blind, placebo-controlled, cross-over study

Patients with chronic liver disease (CLD) are catabolic and GH-resistant. The effects of supraphysiological recombinant human GH (rhGH; 0.2 IU.kg(-1).d(-1)) treatment in adults with CLD were assessed in a randomized, double-blind, placebo-controlled cross-over trial (4-wk dietary run-in, 4-wk treatment, and 2-wk wash-out phases). Nine adults with mild- to moderate-severity CLD participated (median age, 49 yr; three males and six females; Child's classification A in six and B in three). Biopsy-proven etiologies were: alcohol (four patients), primary biliary cirrhosis (three patients), non-A, non-B, non-C hepatitis (one patient), and cryptogenic (one patient). Treatment with rhGH increased serum IGF-I (median increase over placebo, +93 mug.liter(-1); P = 0.004), IGF-binding protein-3 (+0.9 mg.liter(-1): P = 0.004), and acid labile subunit (+10.7 nM; P = 0.004). Total body potassium (+8.0 g; P = 0.023), body weight (+1.6 kg; P = 0.008), and total body water (by bioelectrical impedance; +4.9 kg; P = 0.004) increased. Resting metabolic rate (+313 ml.kg(-1).min(-1); P = 0.004) and lipid oxidation (+1072.0 kcal.d(-1); P = 0.032) increased. Metabolic changes included increased fasting plasma glucose (+1.2 mm; P = 0.008), insulin (+33.8 mU.liter(-1); P = 0.004), C-peptide (+0.7 nM; P = 0.004), and free-fatty acids (+0.1 mEq.liter(-1); P = 0.04). Clinical side effects included worsening edema and ascites. Hepatocellular function did not change. Therefore, rbGH treatment in CLD: 1) overcame hepatic GH resistance; 2) may have improved whole-body protein catabolism; 3) increased lipolysis and lipid oxidation; 4) increased insulin resistance; and 5) had potent antinatriuretic effects. Long-term safety and efficacy require further assessment.

Geography's emerging cross-disciplinary links: Process, causes, outcomes and challenges

In Australian universities the discipline of Geography has been the pace-setter in forging cross-disciplinary links to create multidisciplinary departments and schools, well ahead of other disciplines in humanities, social sciences and sciences, and also to a greater extent than in comparable overseas university systems. Details on all cross-disciplinary links and on immediate outcomes have been obtained by surveys of all heads of departments/schools with undergraduate Geography programs. These programs have traced their own distinctive trajectories, with ramifying links to cognate fields of enquiry, achieved through mergers, transfers, internal initiatives and, more recently, faculty-wide restructuring to create supradisciplinary schools. Geography's `exceptionalism' has proved short-lived. Disciplinary flux is now extending more widely within Australian universities, driven by a variety of internal and external forces, including: intellectual questioning and new ways of constituting knowledge; technological change and the information revolution; the growth of instrumentalism and credentialism, and managerialism and entre-preneurial imperatives; reinforced by a powerful budgetary squeeze. Geographers are proving highly adaptive in pursuit of cross-disciplinary connections, offering analytical tools and selected disciplinary insights useful to non-geographers. However, this may be at cost to undergraduate programs focussing on Geography's intellectual core. Whereas formerly Geography had high reproductive capacity but low instrumental value it may now be in a phase of enhanced utility but perilously low reproductive capacity.

Reverse transcriptase activity and untranslated region sharing of a new RTE-like, non-long terminal repeat retrotransposon from the human blood fluke, Schistosoma japonicum

A new RTE-like, non-long terminal repeat retrotransposon, termed SjR2, from the human blood fluke, Schistosoma japonicum, is described. SjR2 is similar to3.9 kb in length and is constituted of a single open reading frame encoding a polyprotein with apurinic/apyrimidinic endonuclease and reverse transcriptase domains. The open reading frame is bounded by 5'- and 3'-terininal untranslated regions and, at its 3-terminus, SjR2 bears a short (TGAC)(3) repeat. Phylogenetic analyses based on conserved domains of reverse transcriptase or endonuclease revealed that SjR2 belonged to the RTE clade of non-long terminal repeat retrotransposons. Further, SjR2 was homologous, but probably not orthologous, to SR2 front the African blood fluke, Schistosoma mansoni; this RTE-like family of non-long terminal repeat retrotransposons appears to have arisen before the divergence of the extant schistosome species. Hybridisation analyses indicated that similar to 10,000 copies of SjR2 were dispersed throughout the S. japonicum chromosomes, accounting for up to 14% of the nuclear genome. Messenger RNAs encoding the reverse transcriptase and endonuclease domains of SjR2 were detected in several developmental stages of the schistosome, indicating that the retrotransposon was actively replicating within the genome of the parasite. Exploration of the coding and non-coding regions of SjR2 revealed two notable characteristics. First, the recombinant reverse transcriptase domain of SjR2 expressed in insect cells primed reverse transcription of SjR2 mRNA in vitro. By contrast, recombinant SjR2-endonuclease did not appear to cleave schistosome or plasmid DNA. Second, the 5'-untranslated region of SjR2 was >80% identical to the 3-untranslated region of a schistosome heat shock protein-70 gene (hsp-70) in the antisense orientation, indicating that SjR2-like elements were probably inserted into the non-coding regions of ancestral S. japonicum HSP-70, probably after the species diverged from S. mansoni. (C) 2002 Australian Society for Parasitology Inc. Published by Elsevier Science Ltd. All rights reserved.

The first strand transfer reaction of HIV-1 reverse transcription is more efficient in infected cells than in cell-free natural endogenous reverse transcription reactions

Background: In the presence of dNTPs, intact HIV-1 virions are capable of reverse transcribing at least part of their genome, a process known as natural endogenous reverse transcription (NERT). PCR analysis of virion DNA produced by NERT revealed that the first strand transfer reaction (1stST) was inefficient in intact virions, with minus strand (-) strong stop DNA (ssDNA) copy numbers up to 200 times higher than post-1stST products measured using primers in U3 and U5. This was in marked contrast to the efficiency of 1stST observed in single-round cell infection assays, in which (-) ssDNA and U3-U5 copy numbers were indistinguishable. Objectives: To investigate the reasons for the discrepancy in first strand transfer efficiency between intact cell-free virus and the infection process. Study design: Alterations of both NERT reactions and the conditions of cell infection were used to test whether uncoating and/or entry play a role in the discrepancy in first strand transfer efficiency. Results and Conclusions: The difference in 1stST efficiency could not be attributed simply to viral uncoating, since addition of very low concentrations of detergent to NERT reactions removed the viral envelope without disrupting the reverse transcription complex, and these conditions resulted in no improvement in 1stST efficiency. Virus pseudotyped with surface glycoproteins from either vesicular stomatitis virus or amphotrophic murine leukaemia virus also showed low levels of 1stST in low detergent NERT assays and equivalent levels of (-) ssDNA and 1stST in single-round infections of cells, demonstrating that the gp120-mediated infection process did not select for virions capable of carrying out 1stST. These data indicate that a post-entry event or factor may be involved in efficient HIV-1 reverse transcription in vivo. (C) 2002 Elsevier Science B.V. All rights reserved.

Direction of Causation Modeling Between Cross-Sectional Measures of Parenting and Psychological Distress in Female Twins

Under certain conditions, cross-sectional analysis of cross-twin intertrait correlations can provide important information about the direction of causation (DOC) between two variables. A community-based sample of Australian female twins aged 18 to 45 years was mailed an extensive Health and Lifestyle Questionnaire (HLQ) that covered a wide range of personality and behavioral measures. Included were self-report measures of recent psychological distress and perceived childhood environment (PBI). Factor analysis of the PBI yielded three interpretable dimensions: Coldness, Overprotection, and Autonomy. Univariate analysis revealed that parental Overprotection and Autonomy were best explained by additive genetic, shared, and nonshared environmental effects (ACE), whereas the best-fitting model for PBI Coldness and the three measures of psychological distress (Depression, Phobic Anxiety, and Somatic Distress) included only additive genetic and nonshared environmental effects (AE). A common pathway model best explained the covariation between (1) the three PBI dimensions and (2) the three measures of psychological distress. DOC modeling between latent constructs of parenting and psychological distress revealed that a model which specified recollected parental behavior as the cause of psychological distress provided a better fit than a model which specified psychological distress as the cause of recollected parental behavior. Power analyses and limitations of the findings are discussed.

Cross-protective and Infection-Enhancing Immunity in Mice Vaccinated Against Flaviviruses Belonging to the Japanese Encephalitis Virus Serocomplex

The Japanese encephalitis virus serocomplex is a group of mosquito-borne flaviviruses that cause severe encephalitic disease in humans. The recent emergence of several members of this serocomplex in geographic regions where other closely related flaviviruses are endemic has raised urgent human health issues. Thus, the impact of vaccination against one of these neurotropic virus on the outcome of infection with a second, serologically related virus is unknown. We show here that immunity against Murray Valley encephalitis virus in vaccinated mice can cross-protect but also augment disease severity following challenge with Japanese encephalitis virus. Immunepotentiation of heterologous flavivirus disease was apparent in animals immunized with a 'killed' virus preparation when humoral antiviral immunty of low magnitude was elicited. (C) 2002 Elsevier Science Ltd. All rights reserved.

Caenorhabditis elegans mutants resistant to phosphine toxicity show increased longevity and cross-resistance to the synergistic action of oxygen

Phosphine (hydrogen phosphide, PH3) is the fumigant most widely used to protect stored products from pest infestation. Despite the importance of this chemical, little is known about its mode of action. We have created three phosphine-resistant lines (pre-1, pre-7, pre-33) in the model organism C. elegans, with LC50 values 2, 5, and 9 times greater than the fully susceptible parental strain. Molecular oxygen was shown to be an extremely effective synergist with phosphine as, under hyperoxic conditions, 100% mortality was observed in wild-type nematodes exposed to 0.1 mg/l phosphine, a nonlethal concentration in air. All three mutants were resistant to the synergistic effects of oxygen in proportion to their resistance to phosphine with one mutant, pre-33, showing complete resistance to this synergism. We take the proportionality of cross-resistance between phosphine and the synergistic effect of oxygen to imply that all three mutants circumvent a mechanism of phosphine toxicity that is directly coupled to oxygen metabolism. Compared with the wild-type strain, all three mutants have an extended average life expectancy of from 12.5 to 25.3%. This is consistent with the proposed involvement of oxidative stress in both phosphine toxicity and ageing. Because the wild-type and mutant nematodes develop at the same rate, the longevity is unlikely to be caused by a clk-type reduction in oxidative metabolism, a potential alternative mechanism of phosphine resistance.