Requisite role of dorsal raphé in contextual cocaine-memory reconsolidation.

Memory reconsolidation is a process by which labile drug memories are restabilized in long-term memory stores, permitting their enduring control over drug-seeking behaviors. In the present study, we investigated the involvement of the dorsal raphé nuclei (DRN) in cocaine-memory reconsolidation. Sprague-Dawley rats (male, female) were trained to self-administer cocaine in a distinct environmental context to establish contextual drug memories. They then received extinction training in a different context. Next, the rats were re-exposed to the cocaine-predictive context for 15 min to reactivate their cocaine memories or remained in their home cages (no-reactivation control). Memory reactivation was sufficient to increase c-Fos expression, an index of neuronal activation, in the DRN, but not in the median raphé nuclei, during reconsolidation, compared to no reactivation. To determine whether DRN neuronal activity was necessary for cocaine-memory reconsolidation, rats received intra-DRN baclofen plus muscimol (BM; GABAB/A agonists) or vehicle microinfusions immediately after or 6 h after a memory reactivation session conducted with or without lever access. The effects of DRN functional inactivation on long-term memory strength, as indicated by the magnitude of context-induced cocaine seeking, were assessed 72 h later. Intra-DRN BM treatment immediately after memory reactivation with or without lever access attenuated subsequent context-induced cocaine-seeking behavior, independent of sex. Conversely, BM treatment in the adjacent periaqueductal gray (PAG) immediately after memory reactivation, or BM treatment in the DRN 6 h after memory reactivation, did not alter responding. Together, these findings indicate that the DRN plays a requisite role in maintaining cocaine-memory strength during reconsolidation.

Influence of hydrological regime and land cover on traits and potential export capacity of adult aquatic insects from river channels.

Despite many studies highlighting the widespread occurrence and effects of resource movement between ecosystems, comparatively little is known about how anthropogenic alterations to ecosystems affect the strength, direction and importance of such fluxes. Hydrological regime and riparian land use cause well-documented changes in riverine larval invertebrate communities. Using a dataset from 66 sites collected over 20 years, we showed that such effects led to spatial and temporal differences in the density and type of larvae with winged adults within a river reach, altering the size and composition of the source pool from which adult aquatic insects can emerge. Mean annual larval densities varied 33-fold and the temporal range varied more than 20-fold between sites, associated with the hydrological regime and land cover and antecedent high and low flows, respectively. Densities of larvae with winged adults were greater in sites that had more algal coverage, agricultural land use, seasonally predictable flow regimes and faster water velocities. More interestingly, by influencing larval communities, riparian land use and the magnitude and frequency of high and low flows affected the size structure, dispersal ability and longevity of adults available to emerge from river reaches, potentially influencing the spatial extent and type of terrestrial consumers supported by aquatic prey. This suggests that anthropogenic alterations to land use or river flows will have both spatial and temporal effects on the flux and potential availability of adult aquatic insects to terrestrial consumers in many rivers.

Leukocyte count as a predictor of death during remission induction in acute myeloid leukemia.

Acute myeloid leukemia (AML) presenting with a high leukocyte count has been associated with an increase in induction mortality and poor results in a number of other survival measures. However, the level at which an elevated leukocyte count has prognostic significance in AML remains unclear. In this report on a series of 375 adult (non-M3) AML patients undergoing induction chemotherapy at a single institution, leukocyte count analyzed as a continuous variable is shown to be a better predictor of induction death (ID) and overall survival (OS) than a leukocyte count of > or = 100 x 10(9)/L, a value characteristically associated with "hyperleukocytosis" (HL). In this patient cohort, a presenting leukocyte count of > or = 30 x 10(9)/L had high sensitivity and specificity for predicting ID, and both performance status (PS) and leukocyte count more accurately predicted for ID than age. Considering these parameters in newly-diagnosed AML patients may facilitate the development of strategies for reducing induction mortality.

Posterior leukoencephalopathy in association with the tumour lysis syndrome in acute lymphoblastic leukaemia--a case with clinicopathological correlation.

We report a case and autopsy findings of posterior leukoencephalopathy (PL) developing during induction chemotherapy for B-cell acute lymphoblastic leukaemia (B-ALL) complicated by tumour lysis syndrome. PL may present with seizures, headache, altered mental status and occipital blindness, associated with transient parieto-occipital abnormalities on neuro-imaging studies. Precipitants include immunosuppressive agents, renal insufficiency, hypertension and fluid retention. It has also been reported in association with pre-eclamptic and eclamptic states, nephrotic syndrome and following liver and bone marrow transplantation. Only rare cases of PL developing during treatment for haematological malignancy have been reported and to our knowledge it has not been previously reported in association with tumour lysis syndrome. Since the condition is generally regarded as being fully reversible few autopsy findings have been reported.

Exposure to HIV: medical management and legal implications.

The management of exposures to HIV, whether occurring in the occupational or non-occupational setting, involves balancing the risk and inconvenience of antiviral therapy that lacks strong evidence of efficacy against the benefit of it possibly preventing a potentially fatal disease. Clinicians increasingly will be responsible for managing Health Care Workers (HCWs) and other persons exposed to HIV. This will require making a clinical assessment of the risk of HIV transmission and making recommendations for postexposure prophylaxis (PEP) according to the CDC, and other guidelines. Management also requires applying the elements of the doctrine of informed consent, considering involuntary testing of source patients, and reporting of exposure incidents. Proper management will protect all those involved: the exposed person will be protected from unacceptable risks either of contracting HIV, should PEP be indicated, or harm caused by PEP when it is not; the source patient will be protected from unconstitutional invasions of privacy. Finally, the clinician will be protected from claims of malpractice as a result of management of an HIV exposure.

The influence of social programs in source countries on various classes of U.S. immigration.

"This article uses a unique set of pooled cross-sectional and time series data to examine the annual rate of U.S. immigration during 1972-1991 from 60 source countries. One distinguishing feature of the article is that it breaks out and cross-classifies various classes of immigrants--numerically limited versus numerically exempt and new immigrant versus adjustment of status. A second distinguishing feature is that it utilizes a unique vector of variables relating to the presence and characteristics of various social programs in source countries. The models developed here emphasize the importance of both differential economic advantage and the ease with which a prospective migrant can transfer skills to the U.S. labor market. Hausman-Taylor instrumental variable estimates of the coefficients indicate that in addition to other factors, social programs in source countries are significant determinants of immigration to the USA." Data are from the Immigration and Naturalization Service's Public Use Files.

Differential diagnosis of the hip vs. lumbar spine: five case reports.

With recent health care policy changes and the implementation of direct access in many states, physical therapists must be able to identify pathology that is beyond their scope of practice. The five case reports presented in this series required the differential diagnosis of hip vs. lumbar spine pathology. All of the cases required a referral from the physical therapist to either the patient's physician or a specialist because of abnormal screening test results. Each referral resulted in a new diagnosis of pathology that was beyond the scope of physical therapy. Cyriax's concepts of capsular and noncapsular patterns of joint restriction and the "Sign of the Buttock" proved useful in differentiating between hip and lumbar spine pathology in each patient. Our clinical experience indicates that utilizing the presence/absence of a capsular pattern and a "Sign of the Buttock" to screen out hip pathology in patients may be effective; however, further research is needed to support these claims.

Geographically indirect immigration to Canada: description and analysis.

"This article is concerned with geographically indirect immigration to Canada over the period 1968-1988. A geographically indirect immigrant is an individual legally admitted to Canada whose country of last permanent residence differs from country of birth. Records maintained by Employment and Immigration Canada on every immigrant legally admitted over the period were used in the study. Relative to geographically direct immigrants, geographically indirect immigrants tend to be older, more educated, and more highly skilled. Moreover, if they were not born in an English or French speaking country, indirect immigrants are more likely to speak English and/or French capably than direct migrants born in such countries. The study also contains bivariate logit estimates of a model of geographically indirect Canadian immigration. This model suggests that indirect migrants tend to be influenced by personal characteristics (age, sex, marital status, occupation, language ability), as well as by various characteristics of the country of birth (distance from Canada, income level, political conditions)."

The effects of perceptions of hazardous waste on migration: a laboratory experimental approach.

"This study develops a methodology that allows migration decision-making to be studied in a laboratory experimental setting. Moreover, this methodology permits an examination of the importance of natural and man-made hazards in migration decisions--factors that have not been extensively studied as determinants of migration. The specific application is to the location of the U.S. nuclear waste repository at Yucca Mountain, Nevada. Empirical results suggest that the repository may influence employment-related migration, but probably not retirement migration."

Economic effects of immigrants on native and foreign-born workers: complementarity, substitutability, and other channels of influence.

PIP: The authors use Standard Metropolitan Statistical Area (SMSA) data constructed from 1980 census microdata files and other sources to estimate a structural model of native/foreign-born labor demand and labor supply which distinguishes the effects upon real wages of each type of labor and on the employment of natives. The authors specify, econometrically estimate, and simulate the structural model which incorporates not only a production structure channel through which immigrants influence area real wages and employment, but also demand and native labor supply channels. It is noted that while these are not the only channels through which immigrants may affect native workers, the model nonetheless constitutes a step in the direction of a general equilibrium approach. In the production structure channel, immigrants and natives are found to be substitutes in production. Immigration lowers foreign-born wage rates and leads to lower wages for natives. The negative effects of the production channel usually are ameliorated through the demand channel. Further, immigrants add to local demand through their earnings and potentially through non-labor income, while also lowering unit costs and local prices which enhances real incomes and potentially net exports, and thus the demands for local output and area labor. The author discusses findings of interest from the simulation results based upon an analysis of all areas.^ieng

Forecasting state and local population growth with limited data: the use of employment-migration relationships and trends in vital rates.

In this study, the rate of growth of state and local populations in the United States is related to the growth rate of national employment, and to demographic and economic features of the regions concerned, in order to make more realistic long-term population projections. Both natural increase and migration are taken into account in the model developed. "The model is estimated for two regions, the El Paso, TX, standard metropolitan statistical area (SMSA) and the State of New Mexico. Several statistical problems arise because of the limited number of available time-series observations. Fully dynamic historical simulations track the population quite closely, in one case never differing from the actual value by more than 1.17% and in the other never differing by more than 1.36%."

Temporal and spatial patterns of geographically indirect immigration to the United States.

"This article examines the little-studied phenomenon of indirect geographic migration to the United States, or the movement of persons whose country of last permanent residence differed from their country of birth. Over 8 million records of legal immigrants to the United States were studied for the period 1972-1987. Geographically indirect migration is shown to be important, amounting to as many as 86,136 persons during a single year. Primarily because of the dislocations of Southeast Asian refugees from their homelands and their subsequent admittance to the United States, indirect immigration increased during the 1980s. Moreover, again somewhat due to refugees, the patterns of geographically indirect movement changed during recent years. Political conditions in countries of birth appear to be important in explaining these patterns, as well as the age and skills of the indirect migrants themselves."

New directions in migration research: perspectives from some North American regional science disciplines.

"This paper takes several surveys of the literature concerning migration research as its starting point and directs the reader toward a number of potentially fruitful lines for future research. Major sections include one on modeling migrant choice in which the pros and cons of using gross versus net migration measures are discussed. A second introduces and discusses the concept of a 'spatial' choice set, which has the potential to be implemented with laboratory experimental techniques. The third involves a wide-ranging discussion of new directions in modeling the interrelationships between employment and migration." The primary geographical focus is on the United States.

Patterns of change in the intermetropolitan location of population, jobs, and housing: 1950 to 1980.

"This paper presents a discussion and estimates of a simultaneous-equations model of intrametropolitan location of population, employment, and housing. What distinguishes this work from prior research on suburbanization is that population is distinguished by income class, employment is distinguished by type, and housing is distinguished by mode (i.e., owner versus rental). The model is estimated for three distinct decades, namely, the 1950s, 1960s, and 1970s. Moreover, rather than inferring the causal linkages between population, employment, and housing from estimates of urban density functions or from relative changes in central city and suburban population, this paper utilizes [U.S.] data on actual movers between central cities (suburbs) and suburbs (central cities), as well as on the location of metropolitan in-migrants in the central city versus the suburban ring."

Jobs versus amenities in the analysis of metropolitan migration.

"This paper demonstrates that jobs and wages are considerably more important than location-specific amenities in explaining net metropolitan migration of employed persons [in the United States]. These results, which are derived mainly from a unique set of annual migration data, differ considerably from the earlier findings of P. E. Graves...that show amenities to be powerful contributors to the analysis of net metropolitan migration. Several hypotheses are offered and tested to explain the appreciable difference between Grave's results and those of the present study, but the importance of economic factors as opposed to amenities persists."

Changing patterns of migration and regional economic growth in the U.S.: a demographic perspective.

During the 1970s and early 1980s, the South and West census regions accounted for over 90% of incremental national population, which was easily the highest percentage accounted for by these regions in the nation's history. This paper stresses the importance of powerful demographic forces that contributed to the regional shift, but it does not ignore important economic factors. A major theme of the paper is that because the baby boom has now largely matured out of the most mobile age classes, population and employment growth differentials that strongly favored the South and West will moderate in the future.

Migration and employment change: empirical evidence on the spatial and temporal dimensions of the linkage.

"This paper uses a unique set of [U.S.] data to estimate the magnitude of the linkages between employment changes and net employment migration. A simple simultaneous system is specified and estimated for 17 consecutive years. In an average year two extra jobs attract about one additional net migrant, and one additional net migrant has a direct effect on area employment of almost 1.4 jobs." The data are from the One-Percent Social Security Continuous Work History Sample and are for the years 1958 to 1975. The changes in this relationship over time as the economic situation varies are analyzed.

Econometrically accounting for identities and restrictions in models of interregional migration: further thoughts.

PIP: The authors reply to some comments concerning "specification, estimation, and hypothesis testing in models of interregional migration which are internally consistent." They also attempt to clarify some additional conceptual matters in these three areas.^ieng