Xanthurenic acid induces gametogenesis in Plasmodium, the malaria parasite

A small, heat stable chromophore extracted from mosquitoes has recently been implicated as the signal that induces mating of Plasmodium, the malaria parasite. We have used high resolution electrospray mass spectrometry to determine that this gamete activation factor (GAF) has a m/z = 205.0450, suggesting a molecular species composition of C10H7NO4. Xanthurenic acid (XA), a product of tryptophan catabolism, was determined to have an elemental composition, ultraviolet absorbance maxima, and mass spectrum consistent with those characteristics of GAF. XA activated gametogenesis of Plasmodium gallinaceum and P. falciparum in vitro at concentrations lower than 0.5 microM in saline buffered to pH 7.4. A structural analog of XA, kynurenic acid (C10H6NO3), also activated gametogenesis but only at higher concentrations and with less effect. We propose that XA is GAF. This is the first evidence that XA has induction activity.

The mosquito Anopheles stephensi limits malaria parasite development with inducible synthesis of nitric oxide

We have discovered that the mosquito Anopheles stephensi, a natural vector of human malaria, limits parasite development with inducible synthesis of nitric oxide (NO). Elevated expression of A. stephensi NO synthase (NOS), which is highly homologous to characterized NOS genes, was detected in the midgut and carcass soon after invasion of the midgut by Plasmodium. Early induction is likely primed by bacterial growth in the blood meal. Later increases in A. stephensi NOS expression and enzyme activity occurred at the beginning of sporozoite release. Circulating levels of nitrite/nitrate, end-products of NO synthesis, were significantly higher in Plasmodium-infected mosquitoes. Dietary provision of the NOS substrate L-arginine reduced Plasmodium infections in A. stephensi. In contrast, dietary provision of a NOS inhibitor significantly increased parasite numbers in infected mosquitoes, confirming that A. stephensi limits Plasmodium development with NO.

Increased saturation of the fatty acids in the sn-2 position of phospholipids reduces cholesterol crystallization in model biles

Changes in the molecular structure of biliary phospholipids were shown to have major effects on cholesterol solubility, carriers and crystallization in human and model biles. This study investigated systematically the effects of varying saturation of the phosphatidylcholine (PC) sn-2 fatty acid on the cholesterol crystallization process in 3 different model biles. Twenty % of the egg PC (EPC) in these biles were replaced by synthetic PC's with 16:0-18:0, 16:0-18:1, or 16:0-18:2 fatty acyl chains. With 18:0 in the sn-2 position, the crystal observation time (COT) was prolonged from 2 days in the control EPC solution to 14 days (p<0.05). The crystal growth rate (CGR) was reduced from 0.1 OD/day to unmeasurable levels, and the total crystal mass on day 14 decreased by 86%. The introduction of one (18:1), and two (18:2) double bonds in the sn-2 fatty acid rapidly reversed these effects. Ultracentrifugal analysis showed precipitable cholesterol as monohydrate crystals. In the 16:0-18:0 test solution, most of the precipitable cholesterol remained in the supersaturated multilamellar vesicles. Saturation of the biliary PC sn-2 fatty acyl chain prolongs the COT, slows the CGR, reduces the crystal mass, and extends cholesterol solubility in multilamellar vesicles. Desaturation of the sn-2 fatty acid reverses these effects.

5-HT1A receptors in lithium-induced conditioned taste aversion

Experiments were carried out using rats to investigate whether 5-HT1A neural mechanisms are involved in lithium-induced conditioned taste aversion (CTA). We found that the 5-HT1A antagonists p-MPPI and pindolol caused CTA similar to that produced by LiCl. The 5-HT1A agonist 8-OH-DPAT counteracted lithium-induced CTA. Pindolol dose-dependently abolished effects of 8-OH-DPAT on LiCl-induced CTA. These findings support the notion that lithium has antagonistic actions on 5-HT1A receptors. Inhibition of 5-HT synthesis by PCPA failed, however, to prevent lithium-induced CTA. Evidently, mechanisms other than those governed solely by 5-HT are also involved in lithium-induced CTA.

Isolation of a substance from the mosquito that activates Plasmodium fertilization

We have isolated a small, heat stabile, hydrophilic molecule from the gut lumen of unfed, female Anopheles stephensi that is a potent inducer of gametogenesis in Plasmodium falciparum and P. gallinaceum at a hydrogen ion concentration, pH 7.4, that normally suppresses activation. This gamete activation factor (GAF) was purified using reverse phase high performance liquid chromatography and determined to have a major ion m/z of 206.1 by low resolution electrospray mass spectrometry. The molecule, which was also found in the heads of both female and male A. stephensi, absorbed light in the ultraviolet region at three maxima (lambda(max) = 213, 245 and 350 nm); the 245/350 nm absorbance ratio was 7.0. The structure of the molecule and its normal function in the mosquito are not yet known, but in a sample of diverse insect species, extracts from those that feed on blood were bioactive. We propose that GAF is the previously observed malaria exflagellation factor (MEF).

Readiness to adopt a self-management approach to chronic pain: the Pain Stages of Change Questionnaire (PSOCQ)

This manuscript describes the development and initial validation of a self-report questionnaire designed to assess an individual's readiness to adopt a self-management approach to their chronic pain condition. Theory and preliminary empirical work informed the development of a pool of items that were administered to a sample of individuals reporting chronic pain. Analyses of the data support a four factor measure that is consistent with the transtheoretical model of change and associated stages of change model. Each of the four factors, precontemplation, contemplation, action, and maintenance, was found to be internally consistent and stable over time. There was also substantial support for each factor's discriminant and criterion-related validity.

Continuous in vitro propagation of the malaria parasite Plasmodium vivax

The difficulty in controlling Plasmodium vivax, the most common cause of human malaria, has been complicated by growing drug resistance. We have established a method to cycle parasite generations in continuous culture using human blood cells. Chesson strain parasites were passaged from owl monkey erythrocytes to human reticulocytes in McCoy's 5A medium modified with L-glutamine with 25 mM Hepes buffer supplemented with 20% AB+ human serum. Reticulocytes were separated by differential centrifugation in homologous plasma from the peripheral blood of a hemochromatosis patient. Parasites were grown during each 48-hr cycle in a static candle jar environment until the beginning of schizogony, at about 36-40 hr, when reticulocytes were added and cultures transferred to a shaker for 10-12 hr. The addition of a concentration of 10% reticulocytes resulted in stabilizing parasite densities between 0.28 and 0.57 after cycle 3 and increasing the total number of parasites at least 2-fold with each generational cycle. Cultured parasites successfully infected an owl monkey. The morphology of cultured parasites was typical of P. vivax, with highly ameboid trophozoites evident; however, infected erythrocytes were enlarged and distorted on thin film preparations. The species identity of cultivated parasites was confirmed by analysis of the A and C 18S rRNA genes from genomic DNA and expression of only the A gene during erythrocytic asexual growth. The ability to culture P. vivax opens new opportunities to develop vaccines, test drugs, and clone parasites for genome sequencing.

Psychophysiological protective factors for male subjects at high risk for criminal behavior

OBJECTIVE

This study examines the role of elevated autonomic nervous system reactivity in protecting individuals at high risk for criminal behavior from antisocial outcomes. The authors hypothesized that subjects with criminal fathers who did not become criminals themselves were biologically protected from such an outcome because of, in part, heightened responsiveness of the autonomic nervous system.

METHOD

Ninety-four male subjects were placed into one of four study groups: criminal with criminal father (N = 26), noncriminal with criminal father (N = 24), criminal with noncriminal father (N = 20), and noncriminal with noncriminal father (N = 24). Skin conductance and heart rate data were gathered in an orienting paradigm.

RESULTS

Skin conductance and heart rate orienting reactivity were found to be significantly higher in the group of noncriminal subjects with criminal fathers than in the other three groups.

CONCLUSIONS

For subjects at high risk for criminal behavior, heightened autonomic nervous system responsiveness appears to be associated with lower likelihood of criminal outcome.

A new method for the rapid measurement of cholesterol crystallization in model biles using a spectrophotometric microplate reader

Measurements of the cholesterol crystal observation time, and particularly the crystal growth rate in model biles, are important in biliary pathophysiology. The aim of this study was to develop a semi-automated method permitting multiple, simultaneous, and precise measurements of the crystal growth rate in model biles. Incubated model biles were mixed with a high concentration of NaTDC to solubilize non-crystalline turbidity and spectrophotometric measurements were performed. In parallel, samples were observed by light microscopy. The absorbance correlated linearly with the crystal mass and permitted quantitation of the crystal growth rate. Polarized light microscopy was more sensitive than spectrophotometry for determining the initial crystal observation time, while spectrophotometry was more precise and quantitative for measuring the crystal growth rate.

Comparison of the efficacy, safety and acceptability of cefixime and amoxicillin/clavulanate in acute otitis media

BACKGROUND

Use of a beta-lactamase stable antibiotic is called for in cases of acute otitis media (AOM) likely to be caused by beta-lactamase-producing Haemophilus influenzae or Moraxella catarrhalis. Two beta-lactamase-stable agents commonly used for empirical treatment of AOM are amoxicillin/clavulanate and cefixime.

METHODS

A multicenter, randomized clinical trial compared cefixime (CFX; 8 mg/kg once daily) with amoxicillin/clavulanate (A/C; 40 mg/kg/day in three divided doses) for the treatment of children with AOM. Three hundred thirteen children were randomly assigned to a 10-day course of either CFX (n = 158) or A/C (n = 155). Based on history, physical examinations and otoscopic and tympanometric assessments, clinical responses were evaluated as cure, improvement, failure, relapse or nonevaluable. Compliance and patient/parent acceptability were also analyzed.

RESULTS

Overall favorable clinical responses (cure plus improvement) were comparable post-therapy for the two treatments (CFX = 76%; A/C = 77%). Significant differences in response rates for both treatments were noted among different geographic regions, with the highest response rates observed in the Northeast and South. Acceptability of CFX was significantly better than that of A/C (P = 0.0001), and the adverse experience rate was lower (P = 0.001). The most frequently reported adverse experiences were diarrhea (CFX 15.2%, A/C 29.7%) and vomiting (CFX 3.2%, A/C 10.32%). Relapse rates were 26% for CFX and 29% for A/C.

CONCLUSION

This study demonstrated that CFX has comparable clinical efficacy and a better adverse events profile than A/C when used to treat AOM of childhood.

Factors influencing subject willingness to participate in clinical gerontologic research

To identify factors influencing willingness to participate (WTP) in clinical gerontologic research, a questionnaire containing descriptions of seven research projects with a corresponding set of questions about perceived intrusiveness (discomfort and inconvenience), stipend, and other incentive factors was sent to 1004 community-dwelling research subject registry members. There was an inverse relationship between perceived level of intrusiveness and WTP. The more intrusive the study, the greater the relative influence of a stipend on WTP. Male gender and a new experience with an opportunity to learn were independently related to WTP. Subject ratings of perceived intrusiveness for each study component were entered into a factor analysis to guide the development of a three-tier "Level of Intrusiveness" scale. Although prospective validation is necessary, the Level of Intrusiveness scale may be useful in predicting WTP, and determining when other incentives are needed to improve subject recruitment for clinical research.

Cutaneous T-cell lymphoma, tropical spastic paraparesis, cerebral vasculitis, and protein S deficiency in a patient with HTLV-I

The clinical spectrum of retroviruses is expanding rapidly. Human T-cell lymphotropic virus type I (HTLV-I) was the first retrovirus to be described, and its role had been established in adult T-cell leukemia/lymphoma and tropical spastic paraparesis. We report the case of a 35-year-old woman with HTLV-I and the unusual combination of cutaneous T-cell lymphoma, tropical spastic paraparesis, cerebral vasculitis, and protein S deficiency. We discuss the relationship of all her diseases to HTLV-I.

[Imaging of hip joint cartilage and its significance for the intertrochanteric transposition osteotomies in coxarthrosis]

The purpose of the study was to examine the accuracy of MRI in distinguishing between the cartilage of the femoral head and the acetabulum in vivo. In 20 healthy and 41 arthrotic hips an MRI was performed, using a special traction on the hips. With T1-weighted 3-dimensional gradient-echo sequence it is possible to distinguish between the high-signal femoral head and acetabular cartilage by having a low signal of the joint space. In the horizontal position of the phase encoding parameters a reduction of the chemical-shift artefact can be achieved mainly in the ventro-lateral areas. In addition it is possible to discriminate between four qualities of cartilage. The extent and localisation of degenerative cartilage in the hip joint can influence the indication of osteotomies for the hip joint.

[Dopamine D4-receptor variants, schizophrenia and clozapine therapy]

Clozapine is an atypical antipsychotic with a low extrapyramidal side effect profile, and is often useful in the treatment of schizophrenics who do not respond to classical neuroleptics. While the dopamine D2-receptor is believed to be the primary target of classical neuroleptics, clozapine has greater affinity to the dopamine D4-receptor (DRD4). Great variability has been reported for the DRD4 gene and in the receptor itself. It is now possible to investigate if this variation influences individual differences in response to clozapine treatment or in the genetic susceptibility to schizophrenia. Till now the examined variations in the DRD4 gene do not seem to influence response to clozapine treatment or genetic susceptibility to schizophrenia. However, some of clozapine's side effects might be mediated through DRD4 binding.

A follicular scoring system for monitoring ovulation induction in polycystic ovary syndrome patients based solely on ultrasonographic estimation of follicular development

OBJECTIVE

To assess the predictive value of a follicular scoring system for monitoring ovulation induction in polycystic ovary syndrome (PCOS) patients, solely with ultrasound (US).

DESIGN

Ultrasound measurements were performed on alternate days to define a serial follicular score for monitoring ovulation induction with hMG alone, as well as GnRH analogue and hMG, in comparison with E2 concentration obtained on the same day.

SETTING

Outpatient Infertility Clinic, Department of Obstetrics and Gynecology.

PATIENTS

Thirty-four consecutive PCOS patients treated for 63 cycles.

MAIN OUTCOME MEASURE

The follicular score was established considering the summation of points obtained after measuring the mean diameter of each follicle > 5 mm, as follows: 5 to 8 mm = 1 point, 9 to 12 mm = 1.5 points, 13 to 16 mm = 2 points, > or = 17 mm = 3 points.

RESULTS

Follicular score correlated positively with E2 concentrations. A score of > or = 30 points was associated with E2 levels of concentration that reached > 1,500 pg/mL (conversion factor to SI unit, 3.671) and could predict ovarian hyperstimulation. A lower follicular score allowed hCG administration.

CONCLUSIONS

A follicular scoring system may be a safe, simple, and highly efficient method to replace serial E2 measurements in monitoring ovulation induction. Moreover, ovarian hyperstimulation may be predicted.