A Multimodality Hybrid Gamma-Optical Camera for Intraoperative Imaging.

The development of low profile gamma-ray detectors has encouraged the production of small field of view (SFOV) hand-held imaging devices for use at the patient bedside and in operating theatres. Early development of these SFOV cameras was focussed on a single modality-gamma ray imaging. Recently, a hybrid system-gamma plus optical imaging-has been developed. This combination of optical and gamma cameras enables high spatial resolution multi-modal imaging, giving a superimposed scintigraphic and optical image. Hybrid imaging offers new possibilities for assisting clinicians and surgeons in localising the site of uptake in procedures such as sentinel node detection. The hybrid camera concept can be extended to a multimodal detector design which can offer stereoscopic images, depth estimation of gamma-emitting sources, and simultaneous gamma and fluorescence imaging. Recent improvements to the hybrid camera have been used to produce dual-modality images in both laboratory simulations and in the clinic. Hybrid imaging of a patient who underwent thyroid scintigraphy is reported. In addition, we present data which shows that the hybrid camera concept can be extended to estimate the position and depth of radionuclide distribution within an object and also report the first combined gamma and Near-Infrared (NIR) fluorescence images.

Near-infrared light to aid peripheral intravenous cannulation in children: a cluster randomised clinical trial of three devices.

Intravenous cannulation can be difficult in children. Recently, new devices using near-infrared light to make blood vessels visible have become available. We aimed to evaluate the effectiveness of three such devices in facilitating peripheral intravenous cannulation in children. In this cluster randomised clinical trial, daily operating rooms at a tertiary childrens' hospital were randomised to the use of the VeinViewer®, AccuVein® AV300, VascuLuminator Vision® or to a control group. We included 1913 children between birth and 18 years scheduled for elective surgery. Suitable veins for cannulation were more easily visible with the VeinViewer (307/322 (95.3%)) and AccuVein (239/254 (94.1%)) devices than with VascuLuminator (229/257 (89.1%)) (p = 0.03). However, success at the first attempt was not significantly different among groups, ranging from 73.1% to 75.3% (p = 0.93). We conclude that although vein visibility is enhanced, near-infrared devices do not improve cannulation.

Decreased expression of ErbB4 and tyrosine hydroxylase mRNA and protein in the ventral midbrain of aged rats.

Decreased availability or efficacy of neurotrophic factors may underlie an increased susceptibility of mesencephalic dopaminergic cells to age-related degeneration. Neuregulins (NRGs) are pleotrophic growth factors for many cell types, including mesencephalic dopamine cells in culture and in vivo. The functional NRG receptor ErbB4 is expressed by virtually all midbrain dopamine neurons. To determine if levels of the NRG receptor are maintained during aging in the dopaminergic ventral mesencephalon, expression of ErbB4 mRNA and protein was examined in young (3 months), middle-aged (18 months), and old (24-25 months) Brown Norway/Fischer 344 F1 rats. ErbB4 mRNA levels in the substantia nigra pars compacta (SNpc), but not the adjacent ventral tegmental area (VTA) or subtantia nigra pars lateralis (SNl), were significantly reduced in the middle-aged and old animals when compared to young rats. Protein expression of ErbB4 in the ventral midbrain was significantly decreased in the old rats when compared to the young rats. Expression of tyrosine hydroxylase (TH) mRNA levels was significantly reduced in the old rats when compared to young animals in the SNpc, but not in the VTA or SNI. TH protein levels in the ventral midbrain were also decreased in the old animals when compared to the young animals. These data demonstrate a progressive decline of ErbB4 expression, coinciding with a loss of the dopamine-synthesizing enzyme TH, in the ventral midbrain of aged rats, particularly in the SNpc. These findings may implicate a role for diminished NRG/ErbB4 trophic support in dopamine-related neurodegenerative disorders of aging such as Parkinson's disease.

Chills in 'early sepsis': good for you?

We evaluated the predictive value of chills, bacteraemia and endotoxaemia for in-hospital mortality and survival at 5-10 years long-term follow-up in a prospective cohort of 'early sepsis' patients presenting with fever resulting from community-acquired pneumonia or pyelonephritis. Febrile patients with chills had bacteraemia more often (RR 3.1, 95% CI 1.8-5.4) than those without chills. Neither chills nor bacteraemia were significantly related to in-hospital mortality, but patients with endotoxaemia had a higher in-hospital mortality rate than those without endotoxaemia. Patients with chills had a significantly higher survival rate at long-term follow-up than those without chills on admission: the estimated risk of dying was 0.644 (95% CI 0.43-0.95, P = 0.029) for an individual with chills, compared to a person without chills, adjusting for the other factors [age cohort, underlying disease and the pro-inflammatory response in the blood, i.e. tumour necrosis factor-alpha (TNF-alpha) and blood leucocyte number, as scored on hospital admission] in the Cox proportional hazards model. Chills may characterize a patient subpopulation that upon pulmonary and urinary tract infection is able to raise a more rapid and/or efficient host response.

Intracerebral transplantation of adult mouse neural progenitor cells into the Niemann-Pick-A mouse leads to a marked decrease in lysosomal storage pathology.

Niemann-Pick disease is caused by a genetic deficiency in acid sphingomyelinase (ASM) leading to the intracellular accumulation of sphingomyelin and cholesterol in lysosomes. In the present study, we evaluated the effects of direct intracerebral transplantation of neural progenitor cells (NPCs) on the brain storage pathology in the ASM knock-out (ASMKO) mouse model of Type A Niemann-Pick disease. NPCs derived from adult mouse brain were genetically modified to express human ASM (hASM) and were transplanted into multiple regions of the ASMKO mouse brain. Transplanted NPCs survived, migrated, and showed region-specific differentiation in the host brain up to 10 weeks after transplantation (the longest time point examined). In vitro, gene-modified NPCs expressed up to 10 times more and released five times more ASM activity into the culture media compared with nontransduced NPCs. In vivo, transplanted cells expressed hASM at levels that were barely detectable by immunostaining but were sufficient for uptake and cross-correction of host cells, leading to reversal of distended lysosomal pathology and regional clearance of sphingomyelin and cholesterol storage. Within the host brain, the area of correction closely overlapped with the distribution of the hASM-modified NPCs. No correction of pathology occurred in brain regions that received transplants of nontransduced NPCs. These results indicate that the presence of transduced NPCs releasing low levels of hASM within the ASMKO mouse brain is necessary and sufficient to reverse lysosomal storage pathology. Potentially, NPCs may serve as a useful gene transfer vehicle for the treatment of CNS pathology in other lysosomal storage diseases and neurodegenerative disorders.

Discrete expression of insulin receptor substrate-4 mRNA in adult rat brain.

The insulin receptor substrate (IRS) proteins are a family of important regulatory adapters that mediate the coupling between receptor-associated tyrosine kinases and downstream effectors including phosphatidylinositol-3'-kinases (PI-3-Ks). In the present study, the distribution of IRS-4 mRNA was determined in rat brain by in situ hybridization. IRS-4 mRNA was widely expressed throughout the hypothalamus, with the most dense labeling observed in the medial preoptic nucleus, ventromedial hypothalamus, and arcuate nucleus. In contrast, and unlike IRS-1 or IRS-2, expression of IRS-4 mRNA in other forebrain and midbrain regions was much more restricted. The expression of IRS-4 mRNA in the hypothalamus suggests a specific role for this factor in the signaling of one or more receptors involved hypothalamic functions including feeding, lactation, sexual and parental behaviors.

Regulation of phospholipase Cgamma in the mesolimbic dopamine system by chronic morphine administration.

Neurotrophic signaling pathways have been implicated in the maintenance of the mesolimbic dopamine system, as well as in changes in this system induced by chronic morphine exposure. We found that many of these signaling pathway proteins are expressed at appreciable levels within the ventral tegmental area (VTA) and related regions, although with substantial regional variation. Moreover, phospholipase Cgamma1 (PLCgamma1) was significantly and specifically up-regulated within the VTA by 30% following chronic exposure to morphine. PLCgamma1 mRNA expression is enriched in dopaminergic neurons within the VTA; however, the up-regulation of PLCgamma1 in this region was not seen at the mRNA level. In contrast to PLCgamma1, insulin receptor substrate (IRS)-2, a protein involved in phosphatidylinositol 3-kinase signaling, and another putative IRS-like protein were significantly down-regulated within the VTA by 49 and 45%, respectively. Levels of several proteins within the Ras-ERK pathway were not altered. Regulation of neurotrophic factor signaling proteins may play a role in morphine-induced plasticity within the mesolimbic dopamine system.

Expression of trkB and trkC mRNAs by adult midbrain dopamine neurons: a double-label in situ hybridization study.

The documented trophic actions of the neurotrophins brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and neurotrophin-4/5 (NT-4/5) upon ventral mesencephalic dopamine neurons in vitro and in vivo are presumed to be mediated through interactions with their high-affinity receptors TrkB (for BDNF and NT-4/5) and TrkC (for NT-3). Although both neurotrophin receptor mRNAs have been detected within the rat ventral midbrain, their specific association with mesencephalic dopaminergic cell bodies remains to be elucidated. The present study was performed to determine the precise organization of trkB and trkC mRNAs within rat ventral midbrain and to discern whether the neurotrophin receptor mRNAs are expressed specifically by dopaminergic neurons. In situ hybridization with isotopically labeled cRNA probes showed that trkB and trkC mRNAs were expressed in all mesencephalic dopamine cell groups, including all subdivisions of the substantia nigra and ventral tegmental area, and in the retrorubral field, rostral and caudal linear raphe nuclei, interfascicular nucleus, and supramammillary region. Combined isotopic/nonisotopic double-labeling in situ hybridization demonstrated that virtually all of the tyrosine hydroxylase (the catecholamine biosynthetic enzyme) mRNA-containing neurons in the ventral midbrain also expressed trkB or trkC mRNAs. Additional perikarya within these regions expressed the neurotrophin receptor mRNAs but were not dopaminergic. The present results demonstrate that essentially all mesencephalic dopaminergic neurons synthesize the neurotrophin receptors TrkB and TrkC and thus exhibit the capacity to respond directly to BDNF and NT-3 in the adult midbrain in vivo. Moreover, because BDNF and NT-3 are produced locally by subpopulations of the dopaminergic cells, the present data support the notion that the neurotrophins can influence the dopaminergic neurons through autocrine or paracrine mechanisms.

Differential regulation of neurotrophin and trk receptor mRNAs in catecholaminergic nuclei during chronic opiate treatment and withdrawal.

The neurotrophins brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) and their receptors trkB and trkC, respectively, are expressed in the locus coeruleus (LC) and ventral tegmental area (VTA), brain regions known to be involved in opiate addiction. Previously, administration of exogenous neurotrophins has been shown to oppose effects of chronic morphine treatment on LC and VTA neurons. However, the response of endogenous neurotrophins in LC and VTA to opiate treatment is unknown. In this study, BDNF, NT-3, trkB, and trkC mRNAs were analyzed in these regions after chronic morphine treatment and during antagonist precipitated withdrawal. Although chronic morphine exposure resulted in only modest increases in BDNF and NT-3 mRNA expression in LC, precipitated withdrawal led to a marked, rapid, and prolonged increase in BDNF mRNA and a delayed decrease in NT-3 mRNA. Levels of trkB and trkC mRNAs, which were unchanged by chronic morphine treatment, were elevated in LC at 2 and 6 hr of withdrawal. By 20 hr, trkB mRNA levels in LC had returned to control, whereas trkC mRNA levels fell below control values. In contrast to the substantial alterations observed in LC, there was no regulation of the neurotrophins or trk mRNAs within the VTA during chronic opiate treatment or withdrawal, with the exception of an increase in trkB mRNA at 6 hr of withdrawal. These results suggest that neurotrophins and their receptors per se may be involved in opiate-induced plasticity of the LC, whereas other mechanisms would appear to be involved in the VTA.

Alterations in BDNF and NT-3 mRNAs in rat hippocampus after experimental brain trauma.

Previous studies have suggested that the neurotrophins brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) are neuroprotective or neurotrophic for certain subpopulations of hippocampal neurons following various brain insults. In the present study, the expression of BDNF and NT-3 mRNAs in rat hippocampus was examined after traumatic brain injury. Following lateral fluid percussion (FP) brain injury of moderate severity (2.0-2.1 atm) or sham injury, the hippocampi from adult rats were processed for the in situ hybridization localization of BDNF and NT-3 mRNAs using 35S-labeled cRNA probes at post-injury survival times of 1, 3, 6, 24 and 72 h. Unilateral FP injury markedly increased hybridization for BDNF mRNA in the dentate gyrus bilaterally which peaked at 3 h and remained above control levels for up to 72 h post-injury. A moderate increase in BDNF mRNA expression was also observed bilaterally in the CA3 region of the hippocampus at 1, 3, and 6 h after FP injury, but expression declined to control levels by 24 h. Conversely, NT-3 mRNA was significantly decreased in the dentate gyrus following FP injury at the 6 and 24 h survival times. These results demonstrate that FP brain injury differentially modulates expression of BDNF and NT-3 mRNAs in the hippocampus, and suggest that neurotrophin plasticity is a functional response of hippocampal neurons to brain trauma.

Increased expression of trkB mRNA in rat caudate--putamen following 6-OHDA lesions of the nigrostriatal pathway.

The tyrosine kinase receptors trkB and trkC are essential components of the high-affinity receptors for members of the neurotrophin family, including brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3). Both neurotrophin receptor mRNAs are broadly distributed throughout the caudate-putamen. In animal models of Parkinson's disease, loss of the ventral mesencephalic dopamine projection to the striatum has been shown to alter the expression of several striatal peptides, neurotransmitter-synthesizing enzymes and receptors. To determine if expression of trkB and/or trkC striatal mRNAs is also regulated by the integrity of the dopaminergic afferents, adult rats were given unilateral injections of 6-hydroxydopamine (6-OHDA), a selective catecholamine neurotoxin, or vehicle into the right ascending medial forebrain bundle. Following a 2 week survival period, in situ hybridization with 35S-labelled cRNA probes for the kinase-specific, full-length form of trkB mRNA and all forms of trkC mRNA was performed in striatal sections. A significant increase in the hybridization density for trkB mRNA was observed in the caudate-putamen ipsilateral to the 6-OHDA injection, compared with the uninjected control side (P < 0.001). In contrast, no alteration in the hybridization density for trkC mRNA was observed in the striatum of 6-OHDA-treated rats. No alterations in trkB or trkC mRNA levels were observed in the striata of vehicle-treated animals. These data suggest that midbrain dopaminergic afferents regulate the expression of trkB mRNA in the caudate-putamen. Alternatively, since dopaminergic neurons of the ventral mesencephalon express BDNF mRNA, the up-regulation of striatal trkB mRNA may reflect a compensatory response by striatal neurons due to a loss of anterogradely and/or retrogradely derived trophic support from the ventral midbrain.

Increased expression of 5HT2 receptor mRNA in rat striatum following 6-OHDA lesions of the adult nigrostriatal pathway.

Neonatal destruction of the dopaminergic nigrostriatal system with the specific neurotoxin 6-hydroxydopamine (6-OHDA) leads to increases in several components of the adult serotonergic raphe-striatal system. Although results following similar lesions of adult ventral midbrain dopaminergic neurons are less consistent, increases in striatal serotonin (5-hydroxytryptamine; 5HT) fiber density, content, and metabolites have been reported. The effect of such lesions upon gene expression for striatal 5HT receptors, however, has not been determined. The purpose of the present study was to investigate possible changes in expression of several 5HT receptor mRNAs in rat striatum following destruction of the adult nigrostriatal pathway. In situ hybridization for 5HT1A, 5HT1C, and 5HT2 receptor subtype mRNAs was performed in rat striatum following unilateral injection of 6-OHDA into the medial forebrain bundle or directly into the ventral midbrain. Compared to the uninjected control side, a significant increase in the hybridization density for 5HT2 receptor mRNA was observed in the caudate-putamen ipsilateral to the 6-OHDA lesion (P < 0.05). In contrast, no significant changes in the hybridization densities for 5HT1A or 5HT1C receptor mRNAs were detected. The observed increase in striatal 5HT2 receptor mRNA levels after the dopamine-depleting lesion provides evidence for plasticity of the serotonergic raphe-striatal system in the adult rat at the level of striatal gene expression. Furthermore, the present data indicate that dopaminergic mechanisms differentially regulate the expression of 5HT receptor mRNAs in adult rat striatum.

Expression of EGF receptor mRNA in rat nigrostriatal system.

In situ hybridization with a cRNA probe was used to determine the cellular expression of mRNA for the epidermal growth factor receptor (EGF-R) within the rat dopaminergic nigrostriatal system. Hybridization for EGF-R mRNA was distributed throughout the ventral mesencephalon within cells of the substantia nigra pars compacta and ventral tegmental area (VTA). Unilateral lesion of the nigrostriatal pathway with the neurotoxin 6-hydroxydopamine resulted in substantial elimination of EGF-R cRNA hybridization in the ipsilateral substantia nigra and VTA. EGF-R mRNA was also demonstrated within a population of striatal somata, with highest levels of expression detected neonatally. These results indicate that a subpopulation of ventral midbrain dopaminergic neurons, as well as striatal perikarya, express the EGF-R and, thus, may be directly responsive to endogenous EGF, transforming growth factor-alpha, or another EGF-R ligand in vivo.

Sex differences in the effects of testosterone and its metabolites on vasopressin messenger RNA levels in the bed nucleus of the stria terminalis of rats.

Male rats have about two times as many steroid-responsive vasopressin-immunoreactive (AVP-ir) neurons in the bed nucleus of the stria terminalis (BST) as female rats. This sex difference does not depend on differences in circulating hormone levels, since it persists in males and females that are treated with similar levels of testosterone. To analyze the cellular basis of this sex difference, we compared the effects of testosterone and its metabolites on AVP mRNA expression in the BST of males and females that were gonadectomized at 3 months of age. When rats received implants of Silastic tubing filled with testosterone, males had more cells that were labeled for AVP mRNA and more labeling per cell than females. When, in a second experiment, rats received implants of either empty tubing, or tubing with dihydrotestosterone (DHT), estradiol (E), or E plus DHT, hardly any labeled cells were found in rats with empty implants. E treatment significantly stimulated AVP mRNA expression in both sexes, but significantly more so in males, which had more cells that were labeled for AVP mRNA and more labeling per cell than females. DHT treatment by itself did not stimulate AVP mRNA expression, but when given in combination with E, it significantly increased the number of cells over that of animals treated with E alone. This increase was seen in males only. However, in both sexes, it increased the labeling per cell over that of animals treated with E only, but more so in males than in females.(ABSTRACT TRUNCATED AT 250 WORDS)