Shifting and Splitting of Resonance Lines due to Dynamical Friction in Plasmas.

A quasilinear plasma transport theory that incorporates Fokker-Planck dynamical friction (drag) and pitch angle scattering is self-consistently derived from first principles for an isolated, marginally unstable mode resonating with an energetic minority species. It is found that drag fundamentally changes the structure of the wave-particle resonance, breaking its symmetry and leading to the shifting and splitting of resonance lines. In contrast, scattering broadens the resonance in a symmetric fashion. Comparison with fully nonlinear simulations shows that the proposed quasilinear system preserves the exact instability saturation amplitude and the corresponding particle redistribution of the fully nonlinear theory. Even in situations in which drag leads to a relatively small resonance shift, it still underpins major changes in the redistribution of resonant particles. This novel influence of drag is equally important in plasmas and gravitational systems. In fusion plasmas, the effects are especially pronounced for fast-ion-driven instabilities in tokamaks with low aspect ratio or negative triangularity, as evidenced by past observations. The same theory directly maps to the resonant dynamics of the rotating galactic bar and massive bodies in its orbit, providing new techniques for analyzing galactic dynamics.

Observation of Critical-Gradient Behavior in Alfvén-Eigenmode-Induced Fast-Ion Transport.

Experiments in the DIII-D tokamak show that fast-ion transport suddenly becomes stiff above a critical threshold in the presence of many overlapping small-amplitude Alfvén eigenmodes (AEs). The threshold is phase-space dependent and occurs when particle orbits become stochastic due to resonances with AEs. Above threshold, equilibrium fast-ion density profiles are unchanged despite increased drive, and intermittent fast-ion losses are observed. Fast-ion Dα spectroscopy indicates radially localized transport of the copassing population at radii that correspond to the location of midcore AEs. The observation of stiff fast-ion transport suggests that reduced models can be used to effectively predict alpha profiles, beam ion profiles, and losses to aid in the design of optimized scenarios for future burning plasma devices.

Neoclassical transport in the helical reversed-field pinch.

Test particle evaluation of the diffusion coefficient in a fusion plasma in the reversed-field pinch (RFP) configuration shows distinct similarities with stellarators when the plasma spontaneously evolves towards a helical shape. The almost total absence of superbanana particles at the levels of helical deformation seen in experiment (Bh/B=10%) causes transport to be proportional to collision frequency (at low collisions). This fact excludes the possibility that the minimum conceivable transport could be inversely proportional to collision frequency, which is typical of unoptimized stellarators. This result strengthens the perspectives of the helical RFP as a fusion configuration.

Targeted enzyme therapy of experimental glomerulonephritis in rats.

We sought to determine whether systemic administration of proteases ameliorates membranous nephritis induced in rats by immunization and challenge with cationic bovine gamma globulin, and whether targeting of protease to glomerular capillaries increases efficacy. Proteases substituted with biotin were targeted via the cationic protein avidin A, which by virtue of its charge has affinity for the glomerular basement membrane. Despite identical pretreatment proteinuria, rats given untargeted protease (biotin-conjugated without avidin, or unconjugated plus avidin) had significantly less proteinuria than saline-treated controls and nephrotic rats given avidin plus biotin-conjugated (targeted) protease had even less proteinuria and reduced glomerular rat IgG and C3. Among more severely nephrotic rats, targeted protease was again more effective than untargeted protease at reducing proteinuria, and also decreased the size of electron-dense glomerular deposits, hypercholesterolemia, and creatininemia. Inactivated targeted proteases had no effect on proteinuria, hypercholesterolemia, or azotemia. Finally, active targeted protease did not affect proteinuria in the nonimmune mediated nephrosis induced by puromycin aminonucleoside. We conclude that systemic protease can specifically diminish glomerular immune deposits, proteinuria, hyperlipidemia, and creatininemia associated with experimental immune complex glomerulonephritis but not toxic nephrosis, and that targeted protease is more effective than untargeted protease.

Gonadotropin-releasing hormone receptor in the teleost Haplochromis burtoni: structure, location, and function.

GnRH acts via GnRH receptors (GnRH-R) in the pituitary to cause the release of gonadotropins that regulate vertebrate reproduction. In the teleost fish, Haplochromis burtoni, reproduction is socially regulated through the hypothalamus-pituitary-gonadal axis, making the pituitary GnRH-R a likely site of action for this control. As a first step toward understanding the role of GnRH-R in the social control of reproduction, we cloned and sequenced candidate GnRH-R complementary DNAs from H. burtoni tissue. We isolated a complementary DNA that predicts a peptide encoding a G protein-coupled receptor that shows highest overall identity to other fish type I GnRH-R (goldfish IA and IB and African catfish). Functional testing of the expressed protein in vitro confirmed high affinity binding of multiple forms of GNRH: Localization of GnRH-R messenger RNA using RT-PCR revealed that it is widely distributed in the brain and retina as well as elsewhere in the body. Taken together, these data suggest that this H. burtoni GnRH receptor probably interacts in vivo with all three forms of GNRH:

Regional expression of mRNA encoding a second form of gonadotropin-releasing hormone in the macaque brain.

In mammals, reproduction is thought to be controlled by a single neuropeptide, gonadotropin-releasing hormone (GnRH-I), which regulates the synthesis and secretion of gonadotropins from the pituitary gland. However, another form of this decapeptide (GnRH-II), of unknown function, also exists in the brain of many vertebrate species, including humans; it is encoded by a different gene and its amino acid sequence is 70% identical to that of GnRH-I. Here we report the cloning of a GnRH-II cDNA from the rhesus macaque (Macaca mulatta), and show for the first time by in situ hybridization that GnRH-II mRNA is expressed in the primate midbrain, hippocampus and discrete nuclei of the hypothalamus, including the supraoptic, paraventricular, suprachiasmatic and arcuate. Because the regional distribution pattern of cells containing GnRH-II mRNA is largely dissimilar to that of cells containing GnRH-I mRNA, it is likely that these two cell populations receive distinct neuroendocrine inputs and thus regulate GnRH synthesis and release differently.

Second form of gonadotropin-releasing hormone in mouse: immunocytochemistry reveals hippocampal and periventricular distribution.

Hypothalamic GnRH (GnRH-I) is known and named for its role in regulating reproductive function in vertebrates by controlling release of gonadotropins from the pituitary. However, another form of GnRH of unknown function (pGlu-His-Trp-Ser-His-Gly-Trp-Tyr-Pro-Gly; GnRH-II) is expressed in the mesencephalon of all vertebrate classes except jawless fish. Here we show with immunocytochemical staining that the GnRH-II peptide is localized to the mouse midbrain as in other vertebrates, as well as in cells surrounding the ventricles and in cells adjacent to the hippocampus. Staining of adjacent sections using GnRH-I antibody revealed that the distribution of GnRH-I does not overlap with that of GnRH-II.

Chronic administration of neuropeptide Y into the lateral ventricle of C57BL/6J male mice produces an obesity syndrome including hyperphagia, hyperleptinemia, insulin resistance, and hypogonadism.

Neuropeptide Y (NPY) is involved in the central regulation of appetite, sexual behavior, and reproductive function. We have previously shown that chronic infusion of NPY into the lateral ventricle of normal rats produced an obesity syndrome characterized by hyperphagia, hyperinsulinism and collapse of reproductive function. We further demonstrated that acute inhibition of LH secretion in castrated rats was preferentially mediated by the NPY receptor subtype 5 (Y(5)). In the present study, the effects of chronic, central infusion of NPY, or the mixed Y2-Y5 agonist PYY(3-36), were evaluated both in normal male C57BL/6J mice and Sprague-Dawley rats. After a 7-day infusion to male mice, both NPY and PYY(3-36) at 5 nmol per day, induced marked hyperphagia leading to significant increases in body and fat pad weights. Furthermore, both compounds markedly reduced several markers of the reproductive axis. In the rat study, PYY(3-36) was more active than NPY to inhibit the pituitary-testicular axis, confirming the importance of the Y5 subtype for such effects. In the mouse, chronic NPY infusion induced a sustained increase in corticosterone and insulin secretion. Plasma leptin levels were also markedly increased possibly explaining the observed reduction in gene expression for hypothalamic NPY. Gene expression for hypothalamic POMC was reduced in the NPY- or PYY(3-36)-infused mice, suggesting that NPY exacerbated food intake by both acting through its own receptor(s), and reducing the satiety signal driven by the POMC-derived alpha-MSH. The present study in the mouse suggests in analogy with available rat data, that constant exposure to elevated NPY in the hypothalamic area unabatedly enhances food intake leading to an obesity syndrome including increased adiposity, insulin resistance, hypercorticism, and hypogonadism, reminiscent of the phenotype of the ob/ob mouse, that displays elevated hypothalamic NPY secondary to lack of leptin negative feedback action.

Two molecular forms of gonadotropin-releasing hormone (GnRH-I and GnRH-II) are expressed by two separate populations of cells in the rhesus macaque hypothalamus.

Gonadotropin-releasing hormone represents the primary neuroendocrine link between the brain and the reproductive axis, and at least two distinct molecular forms of this decapeptide (GnRH-I and GnRH-II) are known to be expressed in the forebrain of rhesus macaques (Macaca mulatta). Although the distribution pattern of the two corresponding mRNAs is largely dissimilar, their expression appears to show some overlap in specific regions of the hypothalamus; this raises the possibility that some cells express both molecular forms of GnRH. To resolve this issue, double-label histochemistry was performed on hypothalamic sections from six male rhesus macaques, using a monoclonal antibody to GnRH-I and a riboprobe to monkey GnRH-II mRNA. In total, more than 2000 GnRH neurons were examined but in no instance were GnRH-I peptide and GnRH-II mRNA found to be coexpressed. This finding emphasizes that GnRH-I and GnRH-II are synthesized by two distinct populations of hypothalamic neurons, and suggests that they may be regulated by different neuroendocrine pathways.

The melanocortin agonist Melanotan-II reduces the orexigenic and adipogenic effects of neuropeptide Y (NPY) but does not affect the NPY-driven suppressive effects on the gonadotropic and somatotropic axes in the male rat.

Neuropeptide Y (NPY) is a strong orexigenic neurotransmitter also known to modulate several neuroendocrine axes. alpha-Melanocyte-stimulating hormone (MSH) is an essential anorectic neuropeptide, acting on hypothalamic MC3/4 receptor subtypes. When given as an intracerebroventricular bolus injection, Melanotan-II (MT-II), a non selective MC receptor agonist, inhibits feeding, suppresses the NPY orexigenic action, and reduces basal insulinaemia. We evaluated the effects of a 7-day central infusion of MT-II (15 nmol/day) given either alone or in association with NPY (5 nmol/day) in male Sprague-Dawley rats. MT-II produced almost full anorexia for 1-2 days but then feeding gradually returned to normal despite continued MT-II infusion. When coinfused with NPY, MT-II also produced the same initial anorectic episode but then maintained feeding to upper normal levels, thus cancelling the hyperphagia driven by NPY. Whereas NPY infusion produced a doubling of fat pad weight, MT-II reduced adiposity by a factor of two compared to pair-fed rats, and vastly curtailed the NPY-driven increase in fat pad weight. MT-II infusion also significantly curtailed the NPY-induced rise in insulin and leptin secretions. NPY infusion significantly inhibited hypothalamic pro-opiomelanocortin mRNA expression, most likely cancelling the alpha-MSH anorectic activity. As expected from previous studies, chronic NPY infusion strongly inhibited both the gonadotropic and somatotropic axes, and coinfusion of MT-II did not reverse these NPY-driven effects, in sharp contrast with that seen for the metabolic data. MT-II infusion alone had little effect on these axes. In conclusion, chronic MT-II infusion generated a severe but transient reduction in feeding, suggesting an escape phenomenon, and clearly reduced fat pad size. When coinfused with NPY, MT-II was able to cancel most of the NPY effects on feeding, but not those on the neuroendocrine axes. It appears therefore that, as expected, NPY and alpha-MSH closely interact in the control of feeding, whereas the neural pathways by which NPY affects growth and reproduction are distinct and not sensitive to MC peptide modulation.

Near threshold anomalous transport in the standard map.

Anomalous transport is investigated near threshold in the standard map. Very long time flights, and a large anomaly in the transport, are shown to be associated with a new form of multi-island structures causing orbit sticking. The phase space structure of these traps, and the exponents of the characteristic long time tails associated with them are determined. In general these structures are very complex, but some cases, consisting of layers of islands, allow simple modeling. (c) 1998 American Institute of Physics.

Maternal perinatal risk factors and child abuse.

A retrospective matched pair study was designed to compare maternal perinatal factors such as abnormal pregnancy history and labor and delivery experience in families who subsequently were reported as physically abusive to one or more of their children as compared to non-abusive families. The study population consisted of the mothers of 532 children reported to the Baltimore (Maryland) Department of Social Services as physically abused during the years 1975-77. The comparison group was handmatched to the study group from State of Maryland birth certificates on the basis of the abused child's birth year and sex, maternal race, education and hospital of delivery. The study population was 67% black with a mean maternal education of 10.5 completed years. The abused children were 59% male with 48% less than 2 years of age. Results indicated that selected medical definitions of abnormal pregnancy, labor and delivery did not identify families at differential risk of maltreatment. However, mothers in maltreating families were younger, had shorter birth intervals, less prenatal care and were significantly more likely to have had a stillbirth or reported abortion or a prior child death. Study limitations are addressed as are suggestions for future research.

Current parental stress in maltreating and nonmaltreating families of children with multiple disabilities.

Questionnaires were mailed to families of children with multiple disabilities to investigate whether differences in parental perception of stress and burden of care could be identified in those families who had previously been reported and substantiated as abusive or neglectful as compared to those families who had not been so reported. Two hundred and fifty-seven parents completed Friedrich's revised version of Holroyd's Questionnaire on Resources and Stress (QRS-F), an instrument designed to measure stress and burden of care in families of children with disabilities. Twenty-five (9.7%) had previously substantiated maltreatment reports. Results suggest that a history of maltreatment is not related to the family's currently perceived stress levels as measured by the Friedrich scale. Implications of the results are discussed.

Reported maltreatment in children with multiple disabilities.

This study examined a population of children with multiple disabilities to investigate whether functional, developmental, or perinatal factors could differentiate children reported and substantiated as maltreated from those not so reported. Data were collected from medical records of a cohort of 500 children evaluated between 1973 and 1984 at the Kennedy Institute in Baltimore, Maryland. Maltreatment reporting was documented through the State of Maryland Abuse Registry and the counties of residence of all study children. Results indicated that the profiles of demographic and family characteristics associated with child maltreatment reporting in this population are consistent with the literature, but child functional and developmental characteristics were not confirmed as risk factors for substantiated maltreatment reports. Indeed, contrary to investigator expectations, the more severely disabled children, in terms of functioning, appeared at less risk of maltreatment than did disabled children functioning at more age-appropriate levels.

Contested terrain. Beastly questions.

KIE: The practice of vivisection is both defended as necessary to medical advancement and attacked as being symptomatic of a breakdown in society. White cites examples of people who survived critical or debilitating illnesses because of research on animals. His position is that through the use of animal experimentation cures and vaccines were found, and that research using animals must be continued to find cures for AIDS and other current, threatening illnesses. Fox contends that because of an already existing ecological breakdown, further advances in medical knowledge via animal research will not be forthcoming. He compares vivisection to terrorism and, citing the doctrine of ahisma (nonviolence), advocates the abolition of vivisection.^ieng

Variations of Bender-Gestalt constriction and depression in adult psychiatric patients.

The present study explored variations of Bender-Gestalt constriction and their relation to depression. 20 Ss showing constriction of drawings on the upper half-page and 20 Ss showing constriction of drawings on the left half-page were compared with regard to MMPI Depression scores. No significant difference was found between these groups. However, when the constricted groups were combined and then compared with 40 Ss who did not show constriction of Bender drawings, the constricted group had significantly higher (p less than .05) MMPI Depression scores. Thus, variations in Bender constriction are not differently related to depression, but presence of constriction is an indicator. However, its rate of occurrence is so infrequent, appearing in only 5% of the records examined, that its clinical usefulness in the detection of depression is quite limited.

Factors associated with foster care length of stay.

Within foster care service agencies the accurate estimate of children's length of stay in foster care has important implications for both planning and implementing services. Yet information on factors associated with length of stay is incomplete. This article reviews what is presently known and presents new data in a cohort of Maryland children.

Interdisciplinary training for child welfare and health.

Recognition of the symbiotic relationship of the child welfare and child health disciplines led to a project that developed and tested health concepts and methods curricula for child welfare administrators and research staff.

Foster child health care supervision policy.

Foster children represent a high-risk group for physical, emotional, and social health problems, yet few federal or state policies explicitly address foster child health. This article reviews foster child health and the legal background for policy, then discusses components of a comprehensive health care supervision program.

Structural explanations of fertility change: the demographic transition, the economic status of women, and the world system.

PIP: The current study departs from existing analyses by examining change in crude birthrates in a large sample of societies spanning all levels of development and by considering the effects of changes in independent variables on unit changes in fertility rates. It tests for the effects of levels and changes in female labor force representation and for effects of levels and changes in variables derived from classic demographic transition theory -- energy consumption per capita and child mortality. Additionally, it considers the possibility that these variables have differing impacts in least-developed (periphery) and developing (semiperiphery) nations than they had in already developed (core) nations. Data on dependent and independent variables were obtained from tables compiled by the World Bank (1980). In the 1st stage of the analysis, associations between coterminous trends in the dependent and independent variables were examined. To measure trends in fertility between 1960-77 the 1960 crude birthrates were sXrtracted from 1977 crude birthrates. Also obtained from the World Tables were child mortality rates (ages 1-4), female labor force representation (females per 100 persons in the labor force), and energy consumption per capita for both 1960 and 1977. Energy consumption per capita was chosen as the indicator of general development. Both 1960 values and changes between 1960 and 1977 were used as independent variables in the analysis. The blocks derived by Snyder and Kick (1979) were used to assign nations to either the core, semiperiphery, or periphery of the world system. It was possible to classify 93 of the original 100 cases, meaning only 7 cases were excluded in the analyses of subgroups. In the 2nd stage of the analysis, associations between fertility change and lagged changes in its proposed determinants were examined. Analysis of coterminous trends allowed for determining if overall trends in the dependent and independent variables were associated. All 3 theories underlying the hypotheses on causes of fertility change -- demographic transition theory, Caldwell's (1978) revision of the latter as it would be reflected in the economic status of women, and world system theory -- received some support, but it is argued that the evidence from the indirect test of Caldwell's theory of fertility decline was mixed, second, that a number of the results converged in their support for demographic transition theory, and third, that the overall pattern of findings failed to correspond well with expectations based on world system's theory.^ieng