Collective dynamics of complex plasma bilayers.

A classical dusty plasma experiment was performed using two different dust grain sizes to form a strongly coupled asymmetric bilayer (two closely spaced interacting monolayers) of two species of charged dust particles. The observation and analysis of the thermally excited particle oscillations revealed the collective mode structure and dispersion (wave propagation) in this system; in particular, the existence of the theoretically predicted k=0 energy (frequency) gap was verified. Equilibrium molecular-dynamics simulations were performed to emulate the experiment, assuming Yukawa-type interparticle interaction. The simulations and analytic calculations based both on lattice summation and on the quasilocalized charge approximation approach are in good agreement with the experimental findings and help in identifying and characterizing the observed phenomena.

Characterization of Jamaican agro-industrial wastes. Part I: characterization of amino acids using HPLC: pre-column derivatization with phenylisothiocyanate.

Jamaican agro-industries generate large quantities of wastes, which are either discarded or under-utilized. In order to evaluate the possible utilization of these wastes, it is necessary that the profiles of the major biochemical groups be developed. This paper describes the determination of the amino acid composition of coffee, citrus, and rum distillery wastes using a reversed-phase high-performance liquid chromatography method. Acid hydrolysates of the wastes are derivatized with phenylisothiocyanate. They are analyzed as their phenylthiocarbamyl derivatives and determined quantitatively using norleucine as the internal standard. The presence of all the 17 amino acids investigated, nine of which include those essential for animal nutrition, are observed in the samples investigated, suggesting a high quality of protein with implications in the formulation of animal feeds.

The biogenesis of dicarboxylic acid in rats given hypoglycin.

The metabolic origin of dicarboxylic acids which are produced as a result of hypoglycin poisoning (Jamaican vomiting sickness) was investigated. 14C- and 3H-labelled palmitic acid was administered with hypoglycin to rats, and radioactivity was measured in urinary dicarboxylic acids that were isolated by gas-liquid chromatography. Both isotopes were incorporated into adipic and sebacic acids, indicating a precursor-product relationship. Glutaric acid was, essentially, unlabelled. Preferential incorporation of C-16, relative to C-1 of palmitate, while not evident from data for fraction of isotopic dose incorporated, could be deduced by comparing ratios of 14C:3H in precursor with those ratios in products. It thus appears that omega-oxidation of the fatty acid intervenes predominantly at an intermediate stage of chain-shortening, when inhibition of beta-oxidation by hypoglycin becomes more pronounced.

gutfeeling, a Drosophila gene encoding an antizyme-like protein, is required for late differentiation of neurons and muscles.

The gutfeeling (guf) gene was uncovered in a genetic screen for genes that are required for proper development of the embryonic peripheral nervous system. Mutations in guf cause defects in growth cone guidance and fasciculation and loss of expression of several neuronal markers in the embryonic peripheral and central nervous systems. guf is required for terminal differentiation of neuronal cells. Mutations in guf also affect the development of muscles in the embryo. In the absence or guf activity, myoblasts are formed properly, but myoblast fusion and further differentiation of muscle fibers is severely impaired. The guf gene was cloned and found to encode a 21-kD protein with a significant sequence similarity to the mammalian ornithine decarboxylase antizyme (OAZ). In mammals, OAZ plays a key regulatory role in the polyamine biosynthetic pathway through its binding to, and inhibition of, ornithine decarboxylase (ODC), the first enzyme in the pathway. The elaborate regulation of ODC activity in mammals still lacks a defined developmental role and little is known about the involvement of polyamines in cellular differentiation. GUF is the first antizyme-like protein identified in invertebrates. We discuss its possible developmental roles in light of this homology.

The pioneer gene, apontic, is required for morphogenesis and function of the Drosophila heart.

In an effort to isolate genes required for heart development and to further our understanding of cardiac specification at the molecular level, we screened PlacZ enhancer trap lines for expression in the Drosophila heart. One of the lines generated in this screen, designated B2-2-15, was particularly interesting because of its early pattern of expression in cardiac precursor cells, which is dependent on the homeobox gene tinman, a key determinant of heart development in Drosophila. We isolated and characterized a gene in the vicinity of B2-2-15 that exhibits an identical expression pattern than the reporter gene of the enhancer trap. The product of his gene, apontic (apt; see also "Gellon et al., 1997"), does not appear to have any homology with known genes. apt mutant embryos show distinct abnormalities in heart morphology as early as mid-embryonic stages when the heart tube assembles, in that segments of heart cells (those of myocardial and pericardial identity) are often missing. Most strikingly, however, apt mutant embryos or larvae only develop a much reduced heart rate, perhaps because of defects in the assembly of an intact heart tube and/or because of defects in the function or physiological control of the myocardial cells, which normally mediate heart contractions. These cardiac defects may be the cause of death of these mutants during late embryonic or early larval stages.

Bounds on the complex permittivity of polycrystalline materials by analytic continuation.

An analytic continuation method for obtaining rigorous bounds on the effective complex permittivity ε * of polycrystalline composite materials is developed. It is assumed that the composite consists of many identical anisotropic crystals, each with a unique orientation. The key step in obtaining the bounds involves deriving an integral representation for ε *, which separates parameter information from geometrical information. Forward bounds are then found using knowledge of the single crystal permittivity tensor and mean crystal orientation. Inverse bounds are also developed, which recover information about the mean crystal orientation from ε *. We apply the polycrystalline bounds to sea ice, a critical component of the climate system. Different ice types, which result from different growth conditions, have different crystal orientation and size statistics. These characteristics significantly influence the fluid transport properties of sea ice, which control many geophysical and biogeochemical processes important to the climate and polar ecosystems. Using a two-scale homogenization scheme, where the single crystal tensor is numerically computed, forward bounds for sea ice are obtained and are in excellent agreement with columnar sea ice data. Furthermore, the inverse bounds are also applied to sea ice, helping to lay the groundwork for determining ice type using remote sensing techniques.

Voodoo in Africa and the United States.

The authors states that the practice of hexing is not just a nearly extinct phenomenon of isolated rural communities of the deep south of the United States but is evident in large urban areas in the northeast and west. He describes the psychological mechanisms of voodoo as practiced in West Africa to provide insight into similar practices in the United States.

Combinations of clozapine and phencyclidine: effects on drug discrimination and behavioral inhibition in rats.

Phencyclidine (PCP) produces psychotomimetic effects in humans that resemble schizophrenia symptoms. In an effort to screen compounds for antipsychotic activity, preclinical researchers have investigated whether these compounds block PCP-induced behaviors in animals. In the present study, the atypical antipsychotic clozapine was tested in combination with an active dose of PCP in two-lever drug discrimination and mixed signalled-unsignalled differential-reinforcement-of-low-rates (DRL) procedures. PCP produced distinctive effects in each task: it substituted for the training dose in PCP discrimination and it increased the number of responses with short (<3 s) interresponse times as well as increasing overall response rates in the DRL schedule. Acute dosing with clozapine failed to alter the behavioral effects of PCP in either procedure even when tested up to doses that produced pharmacological effects alone. These results suggest that acute dosing with clozapine would not affect behaviors most closely associated with PCP intoxication. Further, they bring into question the utility of using PCP combination procedures in animals to screen for antipsychotic potential. Since chronic dosing is required for therapeutic efficacy of antipsychotics, future studies should focus on investigation of chronic dosing effects of these drugs in combination with PCP.

Traumatic brain injury-induced changes in gene expression and functional activity of mitochondrial cytochrome C oxidase.

Traumatic brain injury (TBI) is documented to have detrimental effects on CNS metabolism, including alterations in glucose utilization and the depression of mitochondrial oxidative phosphorylation. Studies on mitochondrial metabolism have also provided evidence for reduced activity of the cytochrome oxidase complex of the electron transport chain (complex IV) after TBI and an immediate (lhr) reduction in mitochondrial state 3 respiratory rate, which can persist for up to 14 days postinjury. Using differential display methods to screen for differences in gene expression, we have found that cytochrome c oxidase II (COII), a mitochondrial encoded subunit of complex IV, is upregulated following TBI. Since COII carries a binding site for cytochrome c in the respiratory chain, and since it is required for the passage of chain electrons to molecular oxygen, driving the production of ATP, we hypothesized that metabolic dysfunction resulting from TBI alters COII gene expression directly, perhaps influencing the synaptic plasticity that occurs during postinjury recovery processes. To test this hypothesis, we documented COII mRNA expression and complex IV (cytochrome c oxidase) functional activity at 7 days postinjury, focusing on the long-term postinjury period most closely associated with synaptic reorganization. Both central fluid percussion TBI and combined TBI and bilateral entorhinal cortical lesion were examined. At 7 days survival, differential display, RT-PCR, and Northern blot analysis of hippocampal RNA from both TBI and combined insult models showed a significant induction of COII mRNA. This long-term elevation in COII gene expression was supported by increases in COII immunobinding. By contrast, cytochrome oxidase histochemical activity within tissue sections from injured brains suggested a reduction of complex IV activity within the TBI cases, but not within animals subjected to the combined insult. These differences in cytochrome c oxidase activity were supported by in vitro assay of complex IV using cerebral cortical and hippocampal tissues. Our present results support the hypothesis that COII is selectively vulnerable to TBI and that COII differences may indicate the degree of metabolic dysfunction induced by different pathologies. Taken together, such data will better define the role of metabolic function in long-term recovery after TBI.

Effects of modulation of nitric oxide on acoustic startle responding and prepulse inhibition in rats.

The nitric oxide-arginine pathway is intimately connected to the release of dopamine and glutamate, two neurotransmitter systems that may be dysfunctional in schizophrenia. In addition, nitric oxide synthase inhibitors share several behavioral effects with the psychotomimetic drug, phencyclidine. Previous research has found that phencyclidine-like drugs disrupt prepulse inhibition of the acoustic startle response, an animal model of sensorimotor gating, an attentional process that is disrupted in certain neuropsychiatric disorders in humans (e.g., acute schizophrenia). The purpose of the present study was to examine the effects of nitric oxide modulators in this model. Following injection with a nitric oxide modulator or phencyclidine, rats were placed in startle chambers in which they were exposed to acoustic pulses presented alone or preceded by a prepulse. As in previous reports, phencyclidine disrupted prepulse inhibition at doses that did not affect startle during pulse alone trials. In contrast, the nitric oxide synthase inhibitors, N(G)-nitro-L-arginine (L-NOARG) and N(G)-nitro-L-arginine methyl ester (L-NAME), dose-dependently decreased startle during pulse alone trials, but neither drug affected prepulse inhibition. A nitric oxide precursor, L-arginine, produced similar results. Sodium nitroprusside (a nitric oxide releaser) and 7-nitroindazole (a third nitric oxide synthase inhibitor) did not affect startle amplitudes during pulse alone or prepulse + pulse trials. The present results suggest that modulation of nitric oxide synthesis or availability does not disrupt sensorimotor gating of the acoustic startle response and is probably not involved in mediation of this type of attentional deficit in humans.

Jamaican vomiting sickness: a study of two adult cases.

An acute illness (Jamaican vomiting sickness) which affected two adults after eating unripe ackee fruit was investigated. Analyses of serum and urine samples were performed to compare the patterns of organic acidaemia and aciduria with those reported from childhood cases. The main conclusion from the comparison is that the toxic ackee constitutent, hypoglycin, produces essentially the same metabolic effects in adults as in children.

Evaluation of cannabimimetic discriminative stimulus effects of anandamide and methylated fluoroanandamide in rhesus monkeys.

In previous research arachidonylethanolamide (anandamide) has been shown to produce behavioral effects in mice characteristic of psychoactive cannabinoids, including antinociception, catalepsy, hypothermia, and hypomotility. However, differences have also been found between anandamide and delta9-tetrahydrocannabinol (delta9-THC), with anandamide having lower potency, a more rapid onset, and shorter duration of action than delta9-THC. Although it can produce delta9-THC like discriminative stimulus effects in rats, anandamide also produces concomitant response rate decreasing effects, whereas with delta9-THC there is a better separation of these two behavioral effects. The present study was designed to examine the discriminative stimulus effects of anandamide in rhesus monkeys trained to discriminate delta9-THC from vehicle. While anandamide failed to produce reliable substitution for delta9-THC and did not reduce response rates at doses up to 10 mg/kg, 2-methylarachidonyl-2'-fluoroethylamide (methylated fluoroanandamide), a putative stable analog of anandamide, produced full dose-dependent substitution for delta9-THC at doses that caused no significant changes in response rates. These results suggest that systemically administered anandamide may be metabolized in monkeys before behaviorally active concentrations could reach the brain and further suggest that the metabolically more stable analog of anandamide, methylated fluoroanandamide, may aid in the discovery of functional properties of the endogenous cannabinoid system.

Dynamical theory of strongly coupled two-dimensional Coulomb fluids in the weakly degenerate quantum domain.

We study the problem of dynamical response and plasma mode dispersion in strongly coupled two-dimensional Coulomb fluids (2DCFs) in the weakly degenerate quantum domain. Adapting the nonlinear response function approach of Golden and Kalman [Phys. Rev. A 19, 2112 (1979)] to the 2DCF, we construct a self-consistent approximation scheme for the calculation of the density response functions and plasma mode dispersion at long wavelengths. The basic ingredients in the construction are (i). the first kinetic equation in the Bogoliubov-Born-Green-Kirkwood-Yvon hierarchy, (ii). the velocity-average-approximation (VAA) hypothesis, (iii.) the quadratic fluctuation-dissipation theorem, and (iv). the dynamical superposition approximation (DSA) closure hypothesis. The reliability of the VAA-DSA theory can be assessed by observing that the principal coupling correction to the 2D temperature-dependent Lindhard function is identified as being precisely the part of the third-frequency-moment sum-rule coefficient proportional to the potential energy.

Compressibility sum rule for the two-dimensional electron gas.

The authors establish formulas for the isothermal compressibility and long-wavelength static density-density response function of a weakly correlated two-dimensional electron gas in the 1<

Separation of drug effects on timing and behavioral inhibition by increased stimulus control.

Impulsive behavior may represent, in part, a failure of behavioral inhibition (the ability to delay or inhibit a response). In this study, use of a multiple signaled-unsignaled differential-reinforcement-of-low-rates (DRL) 15-s schedule allowed examination of drug effects in conditions in which level of stimulus control differed. Results showed that whereas diazepam increased premature responding during signaled and unsignaled DRL components, amphetamine and delta9-tetrahydrocannabinol increased premature responding primarily during unsignaled components when timing was necessary for efficient performance on the task. In contrast, pimozide and desipramine increased long-delay responses across both components, resulting in longer mean interresponse times. Collectively, these results suggest that the use of different levels of stimulus control may aid in separation of drug effects on timing and other behavioral processes, including behavioral inhibition.

Amino acid, fatty acid, and carbohydrate content of Artocarpus altilis (breadfruit).

A study is conducted to determine the amino acid, fatty acid, and carbohydrate content of breadfruit using high-performance liquid chromatography (HPLC) and gas chromatography (GC). An HPLC method is used for the determination of amino acids and fatty acids in breadfruit. Representative amino acid samples are derivatized with phenylisothiocianate and the resulting phenylthiocarbamyl derivatives are separated on a reversed-phase column by gradient elution with a 0.05M ammonium acetate buffer and 0.01M ammonium acetate in acetonitrile-methanol-water (44:10:46, v/v). Representative fatty acid samples are derivatized with phenacyl bromide and the resulting fatty acid phenacyl esters are separated on a reversed-phase column by gradient elution with acetonitrile and water. Amino acid and fatty acid derivatives are detected by ultraviolet detection at 254 nm. The analysis of the carbohydrates in breadfruit employs a GC method. Carbohydrates are derivatized using trimethylchlorosilane and hexamethyldisilazane to form trimethylsilyl ethers. Compounds in the samples are separated by the temperature programming of a GC using nitrogen as the carrier gas. Percent recoveries of amino acids, fatty acids, and carbohydrates are 72.5%, 68.2%, and 81.4%, respectively. The starch content of the breadfruit is 15.52 g/100 g fresh weight.

High-performance liquid chromatographic analysis of amino acids in ackee fruit with emphasis on the toxic amino acid hypoglycin A.

High-performance liquid chromatography is used to determine the amino acid content of ripe and unripe ackee fruit. Specific emphasis is placed on the level of the toxic amino acid hypoglycin A (hyp-A) in the unripe and ripe ackee fruit and seed. Unripe samples are found to contain significantly higher quantities (P < 0.05) of hyp-A when compared with ripe samples. Uncooked unripe fruit is found to contain 124.4 +/- 6.7 mg/100 g fresh weight and uncooked ripe fruit 6.4 +/- 1.1 mg/100 g fresh weight. The seed of the uncooked unripe fruit is found to contain 142.8 +/- 8.8 mg/100 g fresh weight, and the seed of uncooked ripe fruit has 106.0 +/- 5.4 mg/100 g fresh weight. Boiling fruit in water for approximately 30 min is efficient in removing hyp-A from the edible arilli; however, low levels of 0.54 +/- 0.15 mg/200 mL are detected in the water that was used to cook the ripe fruit. The average %recovery of the amino acids was 80.34%.

Psychiatry. The physician as family therapist.

Patients or families with emotional problems often ask for help or come to the physician's attention in other ways. For those with long-standing or severe problems, referral to an appropriate mental health resource is indicated. Many, however, are simply involved in situational upsets which have temporarily overwhelmed the family's ability to resolve problems. For these families, the physician can be an effective family therapist. Problems can often be dealt with quickly and successfully without disruption of normal office routine. Basic to the physician's providing effective help are knowledge of the effects of childhood experiences on later interactions within a family and honest self-evaluation as to ability and interest in undertaking family therapy.

Tandem psychotherapy: a model for rotating student therapists.

Student psychotherapists often spend relatively brief periods in clinical placements or rotations. In this article, Lewis R. Wolberg's model for short-term therapy is extended and adapted for use in long-term treatment by multiple student therapists treating patients in tandem. Techniques are proposed to enhance continuity of therapy and smooth changing of therapists.

Suicide assessment: a clinical model.

One of the most critical and ill-defined areas of the physican's practice is the evaluation of suicidal intent, particularly of the patient who has made no previous such attempts. Making the problem more complex is the attitude of the physician toward the self-destroyer, as determined by his/her upbringing and training. This article first confronts the issue of how the attitude of the physician can and does affect the potentially suicidal patient. Secondly, a conceptual model for a suicide evaluation is presented. This model has been designed for flexibility and practicality in order to help ensure that a complete evaluation can be done within the requirements and necessities of the practicing physician.