Ability analysis of gender relevance and sex differences in cardiovascular response to behavioral challenge

Cardiovascular effects of gender-specific ability perceptions (ability perceptions linked to one's identity as being female or male) were examined under different task conditions. In Study I, participants were led to believe that either men (masculine task) or women (feminine task) tend to do well on a memory task and then were provided the chance to avoid noise by attaining a low or high performance standard. As expected, sex differences in systolic blood pressure response during performance depended not only on task type but also on the degree of challenge. In Study 2, high standard effects were strengthened and extended through the use of an appetitive procedure and the inclusion of conditions in which the performance standard was extreme. Findings are discussed in terms of an interactional analysis of ability percepts, task demand, and cardiovascular responsivity.

Ability analysis of gender relevance and sex differences in cardiovascular response to behavioral challenge

Cardiovascular effects of gender-specific ability perceptions (ability perceptions linked to one's identity as being female or male) were examined under different task conditions. In Study I, participants were led to believe that either men (masculine task) or women (feminine task) tend to do well on a memory task and then were provided the chance to avoid noise by attaining a low or high performance standard. As expected, sex differences in systolic blood pressure response during performance depended not only on task type but also on the degree of challenge. In Study 2, high standard effects were strengthened and extended through the use of an appetitive procedure and the inclusion of conditions in which the performance standard was extreme. Findings are discussed in terms of an interactional analysis of ability percepts, task demand, and cardiovascular responsivity.

The three-dimensional structures of two complexes between recombinant MS2 capsids and RNA operator fragments reveal sequence-specific protein-RNA interactions

Crystal structures of two complexes between recombinant MS2 capsids and RNA operator fragments have been determined at 2.7 A resolution. The coat protein of the RNA bacteriophage MS2 is bifunctional; it forms the icosahedral virus shell to protect the viral nucleic acid and it acts as a translational repressor by binding with high specificity to a unique site on the RNA, a single stem-loop structure, containing the initiation codon of the gene for the viral replicase. In order to determine the structure of these protein-RNA complexes, we have used chemically synthesized variants of the stem-loop fragment and soaked them into crystals of recombinant capsids. The RNA stem-loop, as bound to the protein, forms a crescent-like structure and interacts with the surface of the beta-sheet of a coat protein dimer. It makes protein contacts with seven phosphate groups on the 5' side of the stem-loop, with a pyrimidine base at position -5, which stacks onto a tyrosine, and with two exposed adenine bases, one in the loop and one at a bulge in the stem. Replacement of the wild-type uridine with a cytosine at position -5 increases the affinity of the RNA to the dimer significantly. The complex with RNA stem-loop having cytosine at this position differs from that of the wild-type complex mainly by having one extra intramolecular RNA interaction and one extra water-mediated hydrogen bond.

Munchausen syndrome/Munchausen syndrome by proxy

Munchausen syndrome (MS) is characterized by patients' chronic and relentless pursuit of medical treatment for combinations of symptoms of consciously self-inflicted injury and falsely reported symptomatology. MS patients are adults, as are perpetrators of Munchausen syndrome by proxy (MSBP). MSBP is an unusual form of child abuse in which a parent, usually the mother, brings a child for medical attention with symptoms falsified or directly induced by the mother. Most reports of MSBP have been of a few cases appearing in medical and pediatric literature. Motivation in both disorders is unclear, and diagnosis and treatment present difficult problems that require more research.

Capturing the structure of a catalytic RNA intermediate: the hammerhead ribozyme

The crystal structure of an unmodified hammerhead RNA in the absence of divalent metal ions has been solved, and it was shown that this ribozyme can cleave itself in the crystal when divalent metal ions are added. This biologically active RNA fold is the same as that found previously for two modified hammerhead ribozymes. Addition of divalent cations at low pH makes it possible to capture the uncleaved RNA in metal-bound form. A conformational intermediate, having an additional Mg(II) bound to the cleavage-site phosphate, was captured by freeze-trapping the RNA at an active pH prior to cleavage. The most significant conformational changes were limited to the active site of the ribozyme, and the changed conformation requires only small additional movements to reach a proposed transition-state.

Depression in Parkinson's disease

Depression occurs in 40% to 50% of Parkinson's disease (PD) patients. From research over the last decade, this co-occurrence appears to be more than an emotional reaction to disability. Replacement of the neurotransmitter, dopamine, benefits the PD motor functions, and the neurotransmitter, serotonin, in antidepressants, reduces depressive symptoms. However, identification of the physiological linkage between PD and depression continues to evade research efforts.

Antibiotic interactions with the hammerhead ribozyme:tetracyclines as a new class of hammerhead inhibitor

A screening of a range of common laboratory antibiotics for inhibition of the hammerhead ribozyme has shown that in addition to certain aminoglycosides (most notably neomycin B) the tetracyclines are also effective inhibitors, with chlorotetracycline being more effective than tetracycline. Inhibition by chlorotetracycline is not as strong as that by neomycin B but is more complicated, with at least two binding sites apparent. As with hammerhead inhibition by neomycin B, chlorotetracycline inhibition can be overcome by raising the concentration of the Mg2+ ion cofactor. We find that around six Mg2+ ions will displace neomycin B, compared with twelve for chlorotetracycline. Inhibition observed in the presence of mixtures of neomycin B and chlorotetracycline is consistent with separate binding sites on the hammerhead for these two classes of antibiotic. Under certain conditions of the mixing order and low concentration of chlorotetracycline, enhancement of single-turnover hammerhead cleavage by up to 20% is observed, with higher concentrations of antibiotic being inhibitory. We have also found that the presence of 2.5% (v/v) DMSO causes a 30% enhancement of the single-turnover cleavage. These results thus extend the range of known inhibitors of hammerhead cleavage, and also demonstrate how the cleavage can be accelerated.

Psychophysiological aspects of autistic disorders: overview

The neurological, neurochemical, and neurotransmitter level differences as well as genetic influences associated with autism have been studied extensively in the last two decades. The varied findings from research offer hope for better understanding, effective treatment, and, perhaps, cure of this pervasive developmental disorder.

The roles of the conserved pyrimidine bases in hammerhead ribozyme catalysis: evidence for a magnesium ion-binding site

We report details of the synthesis and characterization of oligoribonucleotides containing 4-thiouridine or 2-pyrimidinone ribonucleoside (4HC). We have used these probes to examine the roles of the conserved pyrimidines in the central core of the hammerhead ribozyme. The effects on catalysis of singly-substituted hammerhead ribozyme and substrate strands were quantified in multiple-turnover reactions. Various effects were observed on kcat. and Km, with up to a 7-fold decrease and a 3-fold increase respectively. For substitutions with 4HC at positions 3 or 17, catalytic activity in single turnover reactions can be increased up to 8-fold equivalent to 40% of wild-type activity, by increasing the concentration of the Mg2+ cofactor, implying that these substitutions had a deleterious effect on Mg2+ binding. Calculations of the change in the apparent free energy of binding for variants at positions 3, 4 or 17 are each consistent with deletion of a single hydrogen-bond to an uncharged group in the ribozyme. The cytidine 5' to the scissile phosphate had not previously been thought to play a direct role in catalysis, however, removal of the exocyclic amino group decreased kcat. 4-fold. Recently, the crystal structures of a hammerhead ribozyme bound to either a non-cleavable 2'-deoxy substrate strand or a ribo-substrate strand have been reported. The kinetic properties of the variants described here are consistent with several key interactions seen in the crystals, in particular they provide experimental support for the assignment of the proposed catalytically active magnesium ion-binding site.

Probing sequence-specific RNA recognition by the bacteriophage MS2 coat protein

We present the results of in vitro binding studies aimed at defining the key recognition elements on the MS2 RNA translational operator (TR) essential for complex formation with coat protein. We have used chemically synthesized operators carrying modified functional groups at defined nucleotide positions, which are essential for recognition by the phage coat protein. These experiments have been complemented with modification-binding interference assays. The results confirm that the complexes which form between TR and RNA-free phage capsids, the X-ray structure of which has recently been reported at 3.0 A, are identical to those which form in solution between TR and a single coat protein dimer. There are also effects on operator affinity which cannot be explained simply by the alteration of direct RNA-protein contacts and may reflect changes in the conformational equilibrium of the unliganded operator. The results also provide support for the approach of using modified oligoribonucleotides to investigate the details of RNA-ligand interactions.

Crystal structure of an RNA bacteriophage coat protein-operator complex

The RNA bacteriophage MS2 is a convenient model system for the study of protein-RNA interactions. The MS2 coat protein achieves control of two distinct processes--sequence-specific RNA encapsidation and repression of replicase translation--by binding to an RNA stem-loop structure of 19 nucleotides containing the initiation codon of the replicase gene. The binding of a coat protein dimer to this hairpin shuts off synthesis of the viral replicase, switching the viral replication cycle to virion assembly rather than continued replication. The operator fragment alone can trigger self-assembly of the phage capsid at low protein concentrations and a complex of about 90 RNA operator fragments per protein capsid has been described. We report here the crystal structure at 3.0 A resolution of a complex between recombinant MS2 capsids and the 19-nucleotide RNA fragment. It is the first example of a structure at this resolution for a sequence-specific protein-RNA complex apart from the transfer RNA synthetase complexes. The structure shows sequence-specific interactions between conserved residues on the protein and RNA bases essential for binding.

Dimensions of multiple personality disorder

Research on multiple personality disorder (MPD) has burgeoned, and large-scale investigations indicate that a typical MPD patient is a woman, a victim of childhood abuse (especially sexual abuse), a person whose symptoms meet criteria for other psychiatric disorders, and a person who would employ many psychological defenses. Treatment approaches have frequently included hypnotherapy, which requires skill and caution.

A general purification procedure for chemically synthesized oligoribonucleotides

A general procedure for the purification of chemically synthesized oligoribonucleotides is reported. Purification based on the use of a single reverse-phase HPLC column with buffer systems of differing ion-pairing capacity is described. These methods have been applied to the preparation of a series of RNAs which range in size from 10 to 46 nucleotides. The yields obtained are high, up to 53% (based on isolated product compared to those obtained from final trityl assay). The purity of the isolated material is 96-99%. Thus with this general procedure, milligram quantities of extremely pure RNA can be efficiently obtained.

Lithium maintenance therapy for bipolar I patients: possible refractoriness to reinstitution after discontinuation

Recent reports of negative responsiveness in some bipolar I patients to attempts to reinstitute lithium treatment once discontinued are reviewed.

Relationship of childhood sexual abuse to borderline personality disorder, posttraumatic stress disorder, and multiple personality disorder

In this article, I have reviewed recent research into the relationship between childhood sexual abuse and borderline personality disorder, posttraumatic stress disorder, and multiple personality disorder. Evidence that such a relationship exists appears convincing.

Self-induced water intoxication in mental patients

Research on self-induced water intoxication in mental patients, although limited, is reviewed and invites investigation of causes, relation to psychotropic drugs, and effective treatment procedures.

Difficulty as a determinant of cardiovascular response: moderating effect of instrumentality in an alleviation paradigm

Female subjects performed 40 trials of an easy or difficult digit-recognition task while being exposed to intermittent presentations of a noxious noise. Half (high instrumentality) were told that, if they performed well, there was a high chance that they would work without noise in a subsequent trial period. The rest (low instrumentality) were told that, if they performed well, there was a low chance that they would work without noise in the subsequent trial period. Thus, a good performance insured either a high or low probability of alleviating the aversive stimulus. Results indicated that systolic responsiveness was proportional to task demand when the instrumentality of alleviative behavior was high, but low under both task conditions when the instrumentality of alleviative behavior was low. Reaction time and performance data were generally consistent with the view that these effects were due to group differences in task engagement, or 'active coping'. The main findings conceptually replicate and extend results from two previous studies that crossed difficulty and instrumentality manipulations. They also call further into question familiar theoretical conceptions that intimate direct effects of incentive value and perceived control on cardiovascular reactivity.

Review of research on pathological gambling

The literature including a number of review articles was examined for answers to the questions, have distinctive personality test profiles of pathological gamblers been identified, do pathological gamblers have control over their behavior, have studies of alcoholism and addiction increased understanding of compulsive gambling, and has psychotherapy or Gamblers Anonymous been successful for them? Much more information is needed to build on what research on these questions has yielded.

Posttraumatic stress disorder: a review

In this article, I have reviewed posttraumatic stress disorder with Vietnam veterans, soldiers in other wars, and in victims of natural and civilian disasters. A discussion of measurement and therapy approaches is included.

Psychological aspects of chronic fatigue syndrome

Research on Chronic Fatigue Syndrome has not identified a definitive cause or treatment but psychological aspects have been noted.

Kleptomania: a review of the research

Research on kleptomania is limited. Earlier views and recent reports of treatment are reviewed in this article. More study is needed to delineate this impulse-control disorder.

Recombinant interleukin-2 treatment in patients with metastatic colorectal cancer: effect on natural cytotoxicity

Natural cytotoxicity (natural killer, NK, and lymphokine-activated killer, LAK, activity) was documented in 12 patients with metastatic colorectal cancer, both before and after a 5-day course of continuous therapy with intravenous recombinant interleukin-2 (rIL-2). Treatment induced a substantial increase in circulating CD56+ lymphocytes (pretreatment: 12.1 +/- 6.9%, mean +/- SD; posttreatment: 39.2 +/- 6.9%. Maximal NK cell activity was induced by treatment with rIL-2 but only suboptimal augmentation of LAK cell cytotoxicity was obtained. This study indicates that although continuous infusion of rIL-2 does have a significant effect on natural cytotoxicity, this is suboptimal and further studies are necessary to define the most efficacious immunity-enhancing regimens of therapy, thereby hopefully improving clinical outcome of rIL-2 treatment.

Hyperdense renal cyst due to prolonged retention of iodinated contrast material: case report

A case of a hyperdense renal cortical cyst resulting from cyst puncture and opacification 28 months previously is reported. Prolonged retention of water-soluble iodinated contrast material is an unusual cause of a hyperdense renal cyst, which has not previously been described. The findings on serial computed tomography (CT) and chemical analysis are presented and discussed.

Psychoendocrinological aspects of affective disorders

Psychoendocrinological studies have opened a new approach to understanding affective disorders. In this study, the links of affective illnesses to changes in endocrine secretions--particularly adrenal, gonadal, growth, pineal, thyroidal, and prolactin--were reviewed with the object of adding to the number of depressed whose symptoms can be relieved.