The abdomen of <Emphasis Type="Italic">Drosophila</Emphasis>: does planar cell polarity orient the neurons of mechanosensory bristles?

Background

In the adult abdomen of Drosophila, the shafts of mechanosensory bristles point consistently from anterior to posterior. This is an example of planar cell polarity (PCP); some genes responsible for PCP have been identified. Each adult bristle is made by a clone of four cells, including the neuron that innervates it, but little is known as to how far the formation or positions of these cells depends on PCP. The neurons include a single dendrite and an axon; it is not known whether the orientation of these processes is influenced by PCP.

Results

We describe the development of the abdominal mechanosensory bristles in detail. The division of the precursor cell gives two daughters, one (pIIa) divides to give rise to the bristle shaft and socket cell and the other (pIIb) generates the neuron, the sheath and the fifth cell. Although the bristles and their associated shaft and socket cells are consistently oriented, the positioning and behaviour of the neuron, the sheath and the fifth cell, as well as the orientation of the axons and the dendritic paths, depend on location. For example, in the anterior zone of the segment, the axons grow posteriorly, while in the posterior zone, they grow anteriorly. Manipulating the PCP genes can reverse bristle orientation, change the path taken by the dendrite and the position of the cell body of the neuron. However, the paths taken by the axon are not affected.

Conclusion

PCP genes, such as starry night and dachsous orient the bristles and position the neuronal cell body and affect the shape of the dendrites. However, these PCP genes do not appear to change the paths followed by the sensory axons, which must, therefore, be polarised by other factors.

     

Vitamin K status in cystic fibrosis

Appearance of PIVKA-II (protein induced by vitamin K absence-II) in serum is a biochemical sign of insufficient vitamin K-dependent carboxylation of prothrombin. Plasma concentrations of PIVKA-II and vitamin K1 were determined in 24 children with cystic fibrosis. Eight were supplemented with vitamin K1. The purpose of the study was to determine the occurrence of vitamin K deficiency in cystic fibrosis and to evaluate the effect of vitamin K supplementation. PIVKA-II was detectable in only one unsupplemented child. In this patient, the concentration of vitamin K1 was below the limit of detection of 60 ng/l. Vitamin K1 levels in the other unsupplemented children were normal (mean 476 ng/l = 1 mmol/l). The supplemented patients showed extremely high levels of vitamin K1 (mean 22445 ng/l = 50 nmol/l). In conclusion, vitamin K deficiency occurs infrequently in cystic fibrosis. Checking the coagulation system is advised, but routine vitamin K supplementation is not recommended. If additional vitamin K is needed, the starting dose should not exceed 1 mg daily.     

Gonadotropin-releasing hormone-induced changes in testosterone secretion in normal women

This study investigated the pattern of testosterone (T) secretion in spontaneous (n = 14) and gonadotropin-releasing hormone (GnRH)-treated (n = 6) menstrual cycles in normal women. In spontaneous cycles, T was found to increase progressively over the follicular phase (P less than or equal to 0.001), with the peak T value occurring on cycle day 0 (luteinizing hormone [LH] surge). The mean (+/- standard error of the mean [SEM]) T values on cycle day -14 and cycle day 0 were 35 +/- 4 and 51 +/- 4 ng/dl, respectively. GnRH was administered intravenously to six women at 1.3 to 1.7 micrograms per dose every 30 minutes in a study that assessed the ovarian effects of a rapid gonadotropin pulse frequency. In three of the women, the T levels followed a normal follicular phase pattern, whereas in the remaining three GnRH-treated women, there were marked increases in T with peak levels of 97, 123, and 81 ng/dl on day 0. The GnRH-treated subgroup with increased T levels had significantly increased follicular levels of LH, follicle-stimulating hormone (FSH), LH-bio and number of preovulatory ovarian follicles. This study demonstrated that increased levels of LH, FSH, and LH/FSH are capable of acutely increasing the secretion of ovarian androgens.     

The effects of inducing a follicular phase gonadotropin secretory pattern in normal women during the luteal phase

It has been hypothesized that the slowing of the luteinizing hormone (LH) pulse frequency in the luteal phase may be necessary for the demise of the corpus luteum, the intercycle rise in baseline follicle-stimulating hormone (FSH), or ovarian follicular development in the subsequent cycle. For assessment of the physiologic role of the luteal phase LH pulse pattern, this pattern was converted to a follicular pattern in six normal women who used exogenous gonadotropin-releasing hormone administered with a portable pump (dose 50 to 100 ng/kg subcutaneously every 90 minutes beginning in the early luteal [n = 3] and midluteal [n = 3] cycle phases). There was no significant difference between the treated and the subsequent cycle for luteal progesterone production [186.3 versus 159.0 (ng/ml) day], preovulatory follicular size (23.1 versus 22.5 mm), estradiol levels, luteal phase length (15.6 versus 14.3 days), and daily gonadotropin concentrations including the intercycle FSH rise (160.5 versus 139.1 ng/ml). A follicular phase gonadotropin pulse pattern (increased frequency, decreased amplitude) in the luteal phase had no discernible effects on the corpus luteum or on follicular development in the subsequent cycle.     

Psychotic depression and mortality

OBJECTIVE: Major depressive disorder is associated with elevated mortality rates that increase with the severity of depression. The authors hypothesized that patients with psychotic depression would have higher mortality rates than patients with nonpsychotic depression. METHOD: Survival analytic techniques were used to compare the vital status of 61 patients with psychotic major depression with that of 59 patients with nonpsychotic major depression up to 15 years after hospital admission. Medical status was assessed with the Cumulative Illness Rating Scale. Dexamethasone suppression test (DST) data were available for 101 patients. RESULTS: The mortality rate for subjects with psychotic depression was significantly greater than that for those with nonpsychotic depression, with 41% versus 20%, respectively, dying within 15 years after hospital admission. A proportional hazards model with age and medical status entered as covariates confirmed a significantly higher mortality rate in patients with psychotic depression (hazards ratio=2.31). A positive DST result was associated with psychotic depression but was not related to vital status. CONCLUSIONS: Patients with psychotic depression have a two-fold greater risk of death than do patients with severe, nonpsychotic major depression.     

Positron emission tomography in female patients with borderline personality disorder

The pathology of Borderline personality disorder (BPD) is poorly understood and its biological basis remains largely unknown. One functional brain imaging study using [(18)F]Deoxyglucose-PET previously reported frontal and prefrontal hypometabolism. We studied brain metabolism at baseline in 12 medication-free female patients with BPD without current substance abuse or depression and 12 healthy female controls by [(18)F]Deoxyglucose-PET and statistical parametric mapping. We found significant frontal and prefrontal hypermetabolism in patients with BPD relative to controls as well as significant hypometabolism in the hippocampus and cuneus. This study demonstrated limbic and prefrontal dysfunction under resting conditions in patients with BPD by FDG-PET. Dysfunction in this network of brain regions, which has been implicated in the regulation of emotion, may underlie symptoms of BPD.     

Perforating Barrett's ulcer resulting in a life-threatening esophagobronchial fistula

Perforating benign ulcer is a very rare complication of Barrett's esophagus. This report presents the management of a patient with a Barrett's ulcer that penetrated into the left mainstem bronchus resulting in a life-threatening bronchial esophageal fistula. This rare complication was successfully managed by using a staged surgical approach, which combined the principles used for treating benign esophagorespiratory fistulas and perforating Barrett's ulcers.     

Neuroimaging of childhood trauma

Childhood abuse is a major public health problem affecting as many as a third of children in this country today at some point before their 18(th) birthday. The effects of childhood trauma on the brain are increasingly an area of interest. In trying to understand the effects of early stressors on the brain we use animal models of early stress to guide the development of hypotheses. An important potential tool in understanding the effects of abuse on the brain is neuroimaging. Neuroimaging studies in traumatized children are in a relative state of infancy. A number of methodological and ethical issues make this a difficult area for research, including problems ranging from patient motion during scanning to the ethical issues of the duty to report abuse and working with child protective services. Some studies have shown that adults abused as children have smaller volume of the hippocampus, a brain area involved in learning and memory, as measured with magnetic resonance imaging (MRI). One study in children with posttraumatic stress disorder (PTSD) did not find smaller hippocampal volume, but did find smaller brain volume and corpus callosum. Functional neuroimaging studies are consistent with alteration in function and structure of medial prefrontal cortex and hippocampus in patients with childhood sexual trauma and PTSD. These initial results suggest that childhood abuse in the setting of PTSD is associated with long-term changes in brain structure and function.