Dopamine Release at Individual Presynaptic Terminals Visualized with FFNs

The nervous system transmits signals between neurons via neurotransmitter release during synaptic vesicle fusion. To observe neurotransmitter uptake and release from individual presynaptic terminals directly, we designed fluorescent false neurotransmitters as substrates for the synaptic vesicle monoamine transporter. Using these probes to image dopamine release in the striatum, we made several observations pertinent to synaptic plasticity. We found that the fraction of synaptic vesicles releasing neurotransmitter per stimulus was dependent on the stimulus frequency. A kinetically distinct "reserve" synaptic vesicle population was not observed under these experimental conditions. A frequency-dependent heterogeneity of presynaptic terminals was revealed that was dependent in part on D2 dopamine receptors, indicating a mechanism for frequency-dependent coding of presynaptic selection.Hui Zhang and Niko G. Gubernator contributed equally to this work.Download video file.^{(112M, mp4)}     

Are there differences in serum cholesterol and cortisol concentrations between violent and non-violent schizophrenic male suicide attempters?

Previous studies have shown an association between low concentration of serum cholesterol, as well as high concentration of serum cortisol, in suicide behavior. The aim of this study was to evaluate whether men after a violent suicide attempts have different serum cholesterol and cortisol concentrations than those who attempted suicide by non-violent methods. Venous blood samples were collected within 24 hours of admission, to study concentrations of serum cholesterol and cortisol. The sample consisted of 31 male subjects suffering from schizophrenia, admitted in a general hospital after suicide attempt, and was compared with 15 schizophrenic nonsuicidal male controls. Patients with a violent suicidal attempt were found to have significantly lower cholesterol levels and significantly higher cortisol level than patients with non-violent attempts and the control subjects. Our findings suggest that suicide attempts should not be considered a homogenous group. The hypothesis of an association of violent suicidal attempts and peripheral biological markers (cholesterol and cortisol) was supported by our findings.     

Glutathione–ascorbic acid redox cycle and thioredoxin reductase activity in the digestive tract of Leptinotarsa decemlineata (Say)

In view of the antioxidant role of glutathione (GSH) and ascorbic acid (AA), we have examined capacity of the GSH–AA redox cycle in relation to oxidative stress effects in the midgut of the Colorado potato beetle Leptinotarsa decemlineata. Adult gut harbors a higher capacity to cope with oxidative stress than the larval gut. Protein carbonylation was pronounced in the wall of anterior larval midgut and was generally lower in the food digest than in the gut wall. Restriction of oxidative stress effects in anterior gut lumen manifested by lipid peroxidation and protein carbonylation is interpreted as a mechanism favoring digestion and absorption in the posterior midgut. Presence of high GSH in the posterior midgut and AA in both posterior and anterior midguts of adults points to higher utility of the GSH–AA redox system in limiting oxidative stress to manageable levels. The presence, gene expression and activity of thioredoxin reductase (TrxR) were demonstrated for the first time in L. decemlineata which was markedly higher in the anterior than in the posterior midgut in both stages. It is probably central to the maintenance of reduced GSH levels in the whole gut, despite a GSSG/2GSH redox potential tending towards oxidizing ranging from ?183.5 to ?124.4 mV. Glutathione-dehydroascorbate reductase (G_DHAR) activity was markedly augmented in adult gut compared with larva, pointing to a more efficient conversion of dehydroascorbate (DHA) to AA. Also, ascorbate peroxidase (APOX) activity was significantly elevated in all gut compartments of adult except the wall of posterior midgut. The results emphasize the potential importance and role of the GSH–AA redox cycle as a defense strategy against oxidative stress in the gut of L. decemlineata.     

Prevalence of honeybee viruses in the Czech Republic and coinfections with other honeybee disease

Six bee viruses, which occur in Apis mellifera, were monitored in the Czech Republic between 2006 and 2009. Samples of larvae and pupae collected from hives where American foulbrood was detected were screened for bee viruses and in the 125 samples of larvae, there was no confirmed case of a larva infected with both American foulbrood and a bee virus. Of 145 samples infected with the protozoan Nosema apis, there were 23 cases of coinfections with the BQCV virus, 18 with the DWV virus and 11 with the ABPV virus. All coinfections with three or four viruses were also statistically significant apart from the one between ABPV with CBPV and DWV. The PCA ordination diagram indicates that BQCV occurs mainly with Nosema apis and DWV mainly with ABPV.     

The proximal femoral nail antirotation (PFNA) in the treatment of proximal femoral fractures

Proximal femoral fractures, especially in elderly persons with osteoporosis, present a challenge for the traumatologist. While the dynamic hip screw (DHS) became the implant of choice for the treatment of stable fractures, the ideal implant for the treatment of unstable fractures remains an issue. In our experience, Proximal Femoral Nail Antirotation (PFNA) is an excellent device for osteosynthesis as it can be easily inserted, it provides angular and rotational stability and allows early weight bearing on the affected limb. Between February 2007 and August 2009, 76 patients underwent the PFNA fixation for proximal femoral fractures (15 men and 61 women). Forty seven fractures were pertrochanteric, 14 subtrochanteric, 2 pathological and 5 ipsilateral trochanteric and diaphyseal fractures whereas in 8 cases the PFNA was used in reosteosynthesis. The mean age of patients was 73.4 years (range 22-91 years). The fractures were reduced on a traction table and the implant was inserted using minimally invasive technique. Four patients developed superficial postoperative wound infection. No cases of implant breakage have been recorded; there was one cut-out; delayed union was noted in three patients. The majority of patients regained their pre-injury mobility status. The PFNA is an excellent implant for stabilisation of both trochanteric and complex combination fractures as well as an exceptional device for reosteosynthesis. It is easily inserted with few intra- and postoperative complications and allows early weight bearing on the affected limb as well as quicker rehabilitation of patients.