The hydration state of human red blood cells and their susceptibility to invasion by Plasmodium falciparum

In most inherited red blood cell (RBC) disorders with high gene frequencies in malaria-endemic regions, the distribution of RBC hydration states is much wider than normal. The relationship between the hydration state of circulating RBCs and protection against severe falciparum malaria remains unexplored. The present investigation was prompted by a casual observation suggesting that falciparum merozoites were unable to invade isotonically dehydrated normal RBCs. We designed an experimental model to induce uniform and stable isotonic volume changes in RBC populations from healthy donors by increasing or decreasing their KCl contents through a reversible K(+) permeabilization pulse. Swollen and mildly dehydrated RBCs were able to sustain Plasmodium falciparum cultures with similar efficiency to untreated RBCs. However, parasite invasion and growth were progressively reduced in dehydrated RBCs. In a parallel study, P falciparum invasion was investigated in density-fractionated RBCs from healthy subjects and from individuals with inherited RBC abnormalities affecting primarily hemoglobin (Hb) or the RBC membrane (thalassemias, hereditary ovalocytosis, xerocytosis, Hb CC, and Hb CS). Invasion was invariably reduced in the dense cell fractions in all conditions. These results suggest that the presence of dense RBCs is a protective factor, additional to any other protection mechanism prevailing in each of the different pathologies.     

Conscious and subliminal conflicts in normal subjects and patients with schizophrenia: the role of the anterior cingulate

The human anterior cingulate cortex (ACC), which is active during conflict-monitoring tasks, is thought to participate with prefrontal cortices in a distributed network for conscious self-regulation. This hypothesis predicts that conflict-related ACC activation should occur only when the conflicting stimuli are consciously perceived. To dissociate conflict from consciousness, we measured the behavioral and brain imaging correlates of a motor conflict induced by task-irrelevant subliminal or conscious primes. The same task was studied in normal subjects and in patients with schizophrenia in whom the ACC and prefrontal cortex are thought to be dysfunctional. Conscious, but not subliminal, conflict affected anterior cingulate activity in normal subjects. Furthermore, patients with schizophrenia, who exhibited a hypoactivation of the ACC and other frontal, temporal, hippocampal, and striatal sites, showed impaired conscious priming but normal subliminal priming. Those findings suggest that subliminal conflicts are resolved without ACC contribution and that the ACC participates in a distributed conscious control network that is altered in schizophrenia.     

Differential recognition of a tyrosine-dependent signal in the basolateral and endocytic pathways of thyroid epithelial cells

Trafficking of receptors is of crucial importance for the physiology of most exocrine and endocrine organs. It is not known yet if the same mechanisms are used for sorting in the exocytic and endocytic pathways in the different epithelial tissues. In this work, we have used a deletion mutant of the human neurotrophin receptor p75(hNTR) that is normally localized on the apical membrane when expressed in Madin-Darby canine kidney cells. This internal 57-amino acid deletion of the cytoplasmic tail leads to a relocation of the protein from the apical to the basolateral membrane and to rapid and efficient endocytosis. These events are mediated by a signal localized within 9 amino acids of the mutated cytoplasmic tail that is strictly dependent on a tyrosine residue (Tyr-308). We have analyzed the basolateral sorting efficiency and endocytic capacity of this signal in Fischer rat thyroid (FRT) cells, in which basolateral and endocytic determinants have not yet been identified. We found that this targeting signal can mediate efficient transport to the basolateral membrane also in FRT cells with similar tyrosine dependence as in MDCK cells. In contrast to MDCK cells, this Tyr-based signal was not able to mediate coated pits localization and endocytosis in FRT cells. These data represent the first characterization of basolateral/endocytic signals in thyroid epithelial cells. Furthermore, our results indicate that requirements for tyrosine-dependent basolateral sorting signals are conserved among cell lines from different tissues but that the recognition of the colinear endocytic signal is tissue specific.     

Endogenous sex hormones and endometrial cancer risk in women in the European Prospective Investigation into Cancer and Nutrition (EPIC)

Epidemiological data show that reproductive and hormonal factors are involved in the etiology of endometrial cancer, but there is little data on the association with endogenous sex hormone levels. We analyzed the association between prediagnostic serum concentrations of sex steroids and endometrial cancer risk in the European Prospective Investigation into Cancer and Nutrition using a nested case-control design of 247 incident endometrial cancer cases and 481 controls, matched on center, menopausal status, age, variables relating to blood collection, and, for premenopausal women, phase of menstrual cycle. Using conditional regression analysis, endometrial cancer risk among postmenopausal women was positively associated with increasing levels of total testosterone, free testosterone, estrone, total estradiol, and free estradiol. The odds ratios (ORs) for the highest versus lowest tertile were 2.66 (95% confidence interval (CI) 1.50-4.72; P=0.002 for a continuous linear trend) for estrone, 2.07 (95% CI 1.20-3.60; P=0.001) for estradiol, and 1.66 (95% CI 0.98-2.82; P=0.001) for free estradiol. For total and free testosterone, ORs for the highest versus lowest tertile were 1.44 (95% CI 0.88-2.36; P=0.05) and 2.05 (95% CI 1.23-3.42; P=0.005) respectively. Androstenedione and dehydroepiandrosterone sulfate were not associated with risk. Sex hormone-binding globulin was significantly inversely associated with risk (OR for the highest versus lowest tertile was 0.57, 95% CI 0.34-0.95; P=0.004). In premenopausal women, serum sex hormone concentrations were not clearly associated with endometrial cancer risk, but numbers were too small to draw firm conclusions. In conclusion, relatively high blood concentrations of estrogens and free testosterone are associated with an increased endometrial cancer risk in postmenopausal women.     

Influence of sex on disease severity in patients with rheumatoid arthritis

OBJECTIVE: To determine whether patient's sex influences the severity of rheumatoid arthritis (RA) in terms of clinical severity or need for treatments. METHODS: This was a retrospective, single-center study. We compared 133 male patients with 133 female patients presenting with RA and matched for disease duration. Data collection included demographic characteristics, pattern of joint involvement, extraarticular manifestations, medical treatment, and joint surgery. Biological measures, HLA genotypes, Larsen radiological scores on radiographs of hands and feet, and Health Assessment Questionnaire (HAQ) results were obtained. RESULTS: Mean disease duration was 7.4 +/- 6.9 years. Concerning clinical pattern of involvement, sicca syndrome was more frequent in women than in men (p = 0.0003). There were no significant differences concerning absence or presence of at least one disease associated gene (HLA-DRB1*01 or *04) in our patients; however, women more often carried 2 disease associated genes (21% vs 11%). No other difference in clinical, biological, or radiological indicators was noted between the 2 populations. Concerning treatment, there was no difference for large joint arthroplasties; female patients underwent significantly more distal joint arthrodesis, 6.7% vs 1.5% (p = 0.03); they were prescribed slightly more disease modifying drugs, 3.33 vs 2.83 (p = 0.04); and showed a trend toward more large joint arthrodesis, 15% vs 7.5% (p = 0.05), and metacarpophalangeal joint arthroplasties, 5.2% vs 0.7% (p = 0.08). CONCLUSION: When patients are matched for RA duration, sex has little effect on the disease pattern and severity, yet women undergo more distal joint surgery.     

Fetal intracranial hemorrhage related to maternal autoimmune thrombocytopenic purpura

Background

Maternal autoimmune thrombocytopenic purpura (AITP) can cause fetal intracranial hemorrhage.

Case report

A 19-year-old primigravida was referred to our institution for prenatally detected ventriculomegaly at 30th week of gestation. Her personal and family histories were unremarkable. Her platelet count was 54?×?109/L. Fetal neurosonography showed intraparenchymal hemorrhage. AITP was diagnosed in the mother and platelet count decreased at 34?×?109/L. Patient was treated with methylprednisolone and intravenous immunoglobulin. She delivered a 2,340-g infant at 37 weeks with elective cesarean section. The platelet count of the newborn was 181?×?109/L and coagulation tests were normal. No antiplatelet specific antibodies were detected in cord blood. Postnatal MRI evaluation confirmed grade IV intracranial hemorrhage. The newborn baby has suffered from mild spasticity and seizures.

Conclusions

Clinicians must be vigilant about the catastrophic fetal complications of maternal AITP; a close follow-up with a multidisciplinary cooperation between obstetricians, hematologists, and neonatologists must be warranted.