Fracture prevention by femoroplasty--cement augmentation of the proximal femur.

The prevention of hip fractures is a desirable goal to reduce morbidity, mortality, and socio-economic burden. We evaluated the influence on femoral strength of different clinically applicable cementing techniques as "femoroplasty." Twenty-eight human cadaveric femora were augmented by means of four clinically applicable percutaneous cementing techniques and then tested biomechanically against their native contralateral control to determine fracture strength in an established biomechanical model mimicking a fall on the greater trochanter. The energy applied until fracture could be significantly increased by two of the methods by 160% (53.1 Nm vs. 20.4 Nm, p < 0.001) and 164% (47.1 Nm vs. 17.8 Nm, p = 0.008), respectively. The peak load to failure was significantly increased by three of the methods by 23% (3818.3 N vs. 3095.7 N, p = 0.003), 35% (3698.4 N vs. 2737.5 N, p = 0.007), and 12% (3056.8 N vs. 2742.8 N, p = 0.005), respectively. The femora augmented with cemented double drill holes had a lower fracture strength than the single drilled ones. Experimental femoroplasty is a technically feasible procedure for the prophylactic reinforcement of the osteoporotic proximal femur and, hence, could be an auxiliary treatment option to protect the proximal femur against osteoporotic fractures.

Speech processing in radiology.

The goal of this study was to evaluate the recognition rate, learning potential and amount of time needed to complete a report with the Philips speech recognition system SP 6000 (Philips, Best, The Netherlands). Four radiologists dictated reports of interventional radiology, MRI examinations of the musculoskeletal system and CT examinations of the thorax and abdomen with the Philips system using the German language. The recognition rate of each report and improvement rate after each learning phase of the Philips system was assessed. The time needed to complete a report using the Philips system was then compared with the time needed to complete a report using the tape-based system via a time analysis. The average recognition rate for the four radiologists using the Philips system was 79.6 %, which improved to 92.5 % after the third adaptation. Initially, the average time demand to dictate and correct one report was approximately 16.8 min, but this time decreased to 8.1 min after the third adaptation. In contrast, only 3. 6 min were needed to dictate and correct one report using the tape-based system. However, with the speech recognition system, dictation, correction and transcription of the report can be completed within 15 min, whereas with the tape-based system, it takes nearly 1 day. With the Philips system, speech recognition can reach as high as 95 % since each adaptation of the system improves the recognition rate by approximately 5 %. While the Philips system is associated with longer dictation times than the tape-based system, turn-around time for a complete report is substantially shorter with the Philips system than the tape-based system.

A brain gain with a brain drain.

"We study human capital depletion and formation in an economy open to out-migration, as opposed to an economy which is closed. Under the assumption of asymmetric information, the enlarged opportunities and the associated different structure of incentives can give rise to a brain gain in conjunction with a brain drain. Migration by high-skill members of its workforce notwithstanding, the home country can end up with a higher average level of human capital per worker."

Return and dynamics: the path of labor migration when workers differ in their skills and information is asymmetric.

"An implementation of the theory of labor migration under asymmetric information shows that return migration arises from the reinstatement of informational symmetry which induces low-skill workers, who are no longer pooled with high-skill workers, to return. When workers in an occupation constitute more than two skill levels, say four (without loss of generality), the following patterns emerge: Migration is sequential, that is, it proceeds in waves. Each wave breaks into workers who return and workers who stay; within waves the returning migrants are the low-skill workers. The average skill level of migrants is rising in the order of their wave."

Birth weight and body mass index in childhood, adolescence, and adulthood as predictors of blood pressure at age 36.

STUDY OBJECTIVE: The purpose of this study was to investigate the relation between blood pressure at age 36, and birth weight and body mass index (BMI) in childhood, adolescence and adulthood. DESIGN: Prospective longitudinal survey over a period of 36 years in England, Scotland, and Wales. PARTICIPANTS: A nationally representative sample consisting of 3332 men and women born in one week in March 1946. Altogether 82% of these subjects had complete data for the present analysis. MAIN RESULTS: There was an inverse linear relation between birth weight and blood pressure at age 36. The relation between BMI and blood pressure at age 36 was initially inverse and became increasingly positive throughout life. Weight gain in childhood was positively associated with adult blood pressure, although less important than weight change in later life. The associations between blood pressure and birth weight, and blood pressure and adult BMI were independent, and together they accounted for no more than 4% of the variation in adult blood pressure. Both low birth weight (birth weight < or = 2.5kg) and high BMI at age 36 (BMI > 30kg/m2) were associated with hypertension (> 140/90mmHg), but the per cent population risk of hypertension attributable to low birth weight was less than 5%, and to high BMI less than 12%. CONCLUSIONS: Low birth weight and high BMI at age 36 were independently related to high blood pressure. A reduction in the percentage of low birthweight babies born in the fourth decade of this century would only have a negligible effect on the incidence of adult hypertension 30-40 years later.

Equilibrium urban unemployment in developing countries: is migration the culprit?

"This paper challenges the prediction of Todaro's model of rural-to-urban migration that an 'increase in urban employment increases urban unemployed.' It is shown that if the urban demand for labor is isoelastic or inelastic, creation of urban jobs causes urban unemployment to decline and urban-to-rural migration to take place. Moveover, urban job creation always reduces the rate of urban unemployment. The paper then remodels the urban job search process and derives the result that equilibrium urban unemployment would not vanish even if the urban-rural wage gap were eliminated." The geographical focus is on developing countries.

The probability of return migration, migrants' work effort, and migrants' performance.

"This paper demonstrates that differences in earnings between migrants and the native population may reflect differences in incentives rather than differences in characteristics. The analysis indicates that in the presence of a positive probability of return migration, migrants' work effort is higher than that of comparable native-born workers. This differential may explain why, even if all workers are perfectly homogeneous in skills, migrants often outperform the native-born workers in the receiving economy."

Weight and age at menarche.

In the National Child Development Study (1958 cohort) information on their age at menarche and their weights and heights measured at 7, 11, and 16 years was available for 4427 girls. The distribution of age at menarche was not influenced by social class. Weight adjusted for height did not play an important part in the timing of sexual maturation of the girls in the study. Relative weight (weight expressed as a percentage of standard weight) at the ages of 7 and 11 years explained only 3.2%, and 4.9%, respectively of the variation in age at menarche, and changes in relative weight between these two ages accounted for 2%. Girls with early menarche were more likely to be overweight at ages 7, 11, and 16 years than those with late menarche, although early menarche was also reported by girls who were underweight or of average weight. These findings support the hypothesis that in well nourished populations the relation between menarche and body size is largely regulated by genetic factors and that nutrition is less important.

Relative deprivation and international migration.

This article provides theoretical reasoning and empirical evidence that international migration decisions are influenced by relative as well as absolute income considerations. Potential gains in absolute income through migration are likely to play an important role in households' migration decisions, but international migration by household members who hold promise for success as labor migrants can also be an effective strategy to improve a household's income position relative to others in the household's reference group. The findings reported in this article provide empirical support for the hypothesis that relative deprivation plays a significant role in Mexico-to-U.S. migration decisions. The findings also suggest that this migration is an effective mechanism for achieving income gains in households that send migrants to the U.S. and that households wisely choose as migrants those of their members who are most likely to provide net income gains.

On marriage and migration.

PIP: Marriage, migration, and related phenomena such as marital stability, fertility, and investment in human capital may be better explained by studying marriage and migration jointly. This paper examines the role of migration in obtaining joint labor market and marriage market equilibrium. When broadly interpreted, marriage and migration share a number of common features. Both involve search and its resolution (pairing of mates in the former and matching of labor and firms in the latter). In both cases, success in finding a partner is sensitive to the availability of partners and to the distribution of their endowments and traits. Almost always, and along with separation and divorce, marriage mandates spatial relocation which may translate into migration. Both involve a movement that is associated with adjustment costs from 1 state into another. The decisions to enter marriage and undertake employment or the decisions to divorce and quit a job depend on exogenous parameters, some of which are determined by the marriage market and the labor market. Since both marriage and divorce take place in the context of broadly defined markets, they may and often are analyzed applying market concepts, theorems, and solutions. Yet the authors could not pinpoint 1 single, systematic attempt that checks through the interactions between marriage and migration, so this paper attempts to rectify this state of research. Essentially, this paper 1) discusses individual decision making pending possible migration prior to or following marriage, 2) examines whether it is easier for a married couple or a single person to migrate, and 3) considers whether marriage dissolution could cause migration when marriage is the only reason that has kept a spouse from moving. This integrated research agenda for both marriage and migration can delineate interesting new implications to examine.^ieng

Labour migration as a response to relative deprivation.

The relationship between labor migration and relative deprivation is examined. "We model migration from one reference group to another as a response to relative deprivation and satisfaction: We say that a strong incentive to migrate exists if relative deprivation decreases while satisfaction rises with migration and that a weak incentive exists if the individual increases or decreases his satisfaction and deprivation at the same time by migrating. We derive conditions under which different incentives, weak or strong, hold for different individuals.... Our analysis enables us to explain several perplexing migratory phenomena, identify income inequality as a distinct explanatory variable of migration and establish an incentive to migrate in situations where the utility-social welfare approach does not."

Congenital cytomegalovirus infection: a cause of sensorineural hearing loss.

Prospective studies have suggested that about 108 children with congenital cytomegalovirus (CMV) infection and bilateral sensorineural hearing loss are born each year in England and Wales; this represents about 12% of all children with congenital sensorineural hearing loss. Over a nine year period 1644 children aged between 6 months and 4 years who were attending the Nuffield Hearing and Speech Centre were screened for CMV infection. The prevalence of CMV in the urine of children with sensorineural hearing loss but no immediate family history of deafness was nearly twice that (13%) found in other children with impaired hearing and those with normal hearing (7%). These findings indicate the importance of CMV as a cause of hearing loss.

Genetic heterogeneity in different BB rat subpopulations.

Two different BB-rat subpopulations were followed over 7 inbred generations under identical environmental conditions: BB/OK as derived in 1983 from the original stock in Ottawa, BB/PhiK as derived in 1983 from a stock at the University of Pennsylvania, Philadelphia. They showed significant differences in incidence, age at onset, untreated survival time of diabetes, leucopenia and body weight gain. By crossing experiments these phenotypical differences could be attributed to a genetic diversity between the 2 subpopulations. It is concluded that this genetic diversity is based on the heterogeneity of the parental BB Wistar rat stock and that the genetic differentiation between subpopulations of a different history is favoured by the "bottle neck effect", selection, mutation and genetic drift. The study of defined subpopulations and of their genetic interaction will provide deeper insight into the mechanisms of inheritance of diabetes in different species.

In vitro and in vivo behaviour of rat islets of Langerhans treated with MHC antisera and complement.

The in vitro and in vivo behaviour of rat islets of Langerhans pretreated with polyclonal MHC antisera and complement was investigated. Complement-dependent cytotoxicity against rat islets was mediated by the antisera which were either directed against all MHC products ("a anti-u") or against products of the B-region of rat MHC ("Ba anti-Bu"). There were only minor alterations in glucose-stimulated insulin secretion and in 3H-leucine incorporation into islet proteins and into (pro)insulin in the pretreated islets. The syngeneic transplantation of "Ba anti-Bu"-treated islets led to a permanent graft survival in all streptozotocin-diabetic rats but after "a anti-u"-pretreatment permanent graft survival was only achieved in 33% of the syngeneic recipients. It is concluded, that in the latter case a complement-dependent cytotoxicity is exerted against the islets which may not allow sufficient in vivo survival. Now it appears necessary to look for effects of pretreatment prior to an allogeneic transplantation.

Genetic studies of IDDM in BB rats: the incidence of diabetes in F2 and first backcross hybrids allows rejection of the recessive hypothesis.

The BB rat spontaneously develops an IDDM with many analogies to human IDDM, i.e. the genetic basis is a puzzle, since more than one mode of inheritance of IDDM in BB rats has been proposed. These different proposals reflect the heterogeneity of BB rats used for genetic studies. This prompted us to investigate the inheritance of IDDM in two subpopulations of BB rats (BB/OK and BB/PhiK) by crossing studies with the production of (diabetic BB x LEW 1.A) F1, F2 generations and of first backcross hybrids onto BB (B1BB) and LEW.1A (B1A) rats respectively. Both BB rat subpopulations were different in origin, degree of inbreeding, incidence and age at onset of diabetes and in certain immunologic, metabolic and hematologic traits. All hybrids were serotyped and checked for diabetes by determination of urine and plasma glucose twice weekly up to an age of 200 days. None of the F1 and B1A hybrids developed diabetes. Some cases were observed in the F2 hybrids with a different incidence in the two subpopulations (2.3% in BB/OK, 11.0% in BB/PhiK). The percentage of diabetes in the B1BB hybrids was 13.8% (BB/OK) and 24.0% (BB/PhiK) respectively. All diabetic hybrids were characterized by at least one RT1uv haplotype which was derived from the original BB animals. These results demonstrated clearly (1) that the mode of inheritance depends on the genotype of the animals observed and (2) simple autosomal-recessive genetics cannot be accepted for BB rat diabetes.(ABSTRACT TRUNCATED AT 250 WORDS)