Water molecules and exchangeable hydrogen ions at the active centre of bacteriorhodopsin localized by neutron diffraction. Elements of the proton pathway?

Neutron diffraction is used to localize water molecules and/or exchangeable hydrogen ions in the purple membrane by H2O/2H2O exchange experiments at different values of relative humidity. At 100% relative humidity, differences in the hydration between protein and lipid areas are observed, accounting for an excess amount of about 100 molecules of water in the lipid domains per unit cell. A pronounced isotope effect was observed, reproducibly showing an increase in the lamellar spacing from 60 A in 2H2O to 68 A in H2O. At 15% relative humidity, the positions of exchangeable protons became visible. A dominant difference density peak corresponding to 11 +/- 2 exchangeable protons was detected in the central part of the projected structure of bacteriorhodopsin at the Schiff's base end of the chromophore. A difference density map obtained from data on purple membrane films at 15% relative humidity in 2H2O, and the same sample after complete drying in vacuum, revealed that about eight of these protons belong to four water molecules. This is direct evidence for tightly bound water molecules close to the chromophore binding site of bacteriorhodopsin, which could participate in the active steps of H+ translocation as well as in the proton pathway across this membrane protein.

Confidence estimation methods for neural networks: a practical comparison

Feedforward neural networks, particularly multilayer perceptrons, are widely used in regression and classification tasks. A reliable and practical measure of prediction confidence is essential. In this work three alternative approaches to prediction confidence estimation are presented and compared. The three methods are the maximum likelihood, approximate Bayesian, and the bootstrap technique. We consider prediction uncertainty owing to both data noise and model parameter misspecification. The methods are tested on a number of controlled artificial problems and a real, industrial regression application, the prediction of paper "curl". Confidence estimation performance is assessed by calculating the mean and standard deviation of the prediction interval coverage probability. We show that treating data noise variance as a function of the inputs is appropriate for the curl prediction task. Moreover, we show that the mean coverage probability can only gauge confidence estimation performance as an average over the input space, i.e., global performance and that the standard deviation of the coverage is unreliable as a measure of local performance. The approximate Bayesian approach is found to perform better in terms of global performance.

Venous and paradoxical air embolism in the sitting position. A prospective study with transoesophageal echocardiography

This prospective study investigates the frequency of patent foramen ovale (PFO), venous air embolism (VAE) and paradoxical air embolism (PAE) by transoesophageal echocardiography (TOE) in neurosurgical patients operated on in the sitting position. The risk of PAE after exclusion of PFO is assessed. A PFO was identified by pre-operative TOE and VAE and PAE by continuous intraoperative TOE. Sixty-two patients were divided into two groups, 22 patients were studied in group 1 (posterior fossa surgery) and group 2 (cervical surgery) contained 40 patients. Pre-operative TOE demonstrated a PFO in 5 of the 22 patients in group 1 (23%). Patients with proven PFO were excluded from the sitting position. Two further patients of this group (12% of 17 patients), in whom a PFO had been excluded pre-operatively, nevertheless had PAE, air occurring in all cavities of the heart. In group 2 the incidence of PFO was 4 out of 40 patients (10%). No PAE was observed in this group. Three morphological types of VAE with different haemodynamic and ventilation changes were demonstrated. VAE was observed in 76% of all posterior fossa operations and in 25% of cervical laminectomies. We conclude that a pre-operative search for PFO is mandatory considering its incidence of 23% in group 1 and of 10% in group 2, and the risk of PAE. If a PFO is detected, the sitting position should be avoided. A residual risk for PAE remains despite exclusion of PFO because the reliability of TOE is limited. TOE is the method of choice for detecting VAE and PAE.

Measuring Alzheimer's disease progression with transition probabilities: estimates from CERAD

OBJECTIVES

To estimate annual transition probabilities (i.e., the likelihood that a patient will move from one disease stage to another in a given time period) for AD progression. Transition probabilities are estimated by disease stages (mild, moderate, severe) and settings of care (community, nursing home), accounting for differences in age, gender, and behavioral symptoms as well as the length of time a patient has been in a disease stage.

METHODS

Using data from the Consortium to Establish a Registry for Alzheimer's Disease (CERAD), the authors employed a modified survival analysis to estimate stage-to-stage and stage-to-nursing home transition probabilities. To account for individual variability, a Cox proportional hazards model was fit to the CERAD data to estimate hazard ratios for gender, age (50 to 64, 65 to 74, and more than 75 years), and level of behavioral symptoms (low/high, according to responses to the Behavioral Rating Scale for Dementia) for each of the key stage-to-stage and stage-to-nursing home transitions.

RESULTS

The transition probabilities underscore the rapid progression of patients into more severe disease stages and into nursing homes and the differences among population subgroups. In general, male gender, age under 65, and high level of behavioral symptoms were associated with higher transition probabilities to more severe disease stages. Disease progression is roughly constant as a function of the time a patient has spent in a particular stage.

CONCLUSIONS

Transition probabilities provide a useful means of characterizing AD progression. Economic models of interventions for AD should consider the varied course of progression for different population subgroups, particularly those defined by high levels of behavioral symptoms.

Activation and lateralization of sensorimotor field for perioral biting reflex by intranigral GABA agonist and by systemic apomorphine in the rat

In Experiment 1 unilateral injection of the GABA agonist, muscimol (20 ng in 0.1 microliter saline) into the substantia nigra (SN) of rats elicited contraversive turning and a correlated transient asymmetry in responsiveness to tactile stimulation of the mouth area. On the side of the face contralateral to the injected SN they responded stronger than on the ipsilateral side, and, furthermore, they responded to tactile stimulation with a withdrawal of the lip, followed by a vigorous biting of the probe. In Experiment 2, systemic injection of apomorphine also sensitized the perioral biting response to tactile stimulation. Unilateral injection into the SN of 8 micrograms 6-OHDA blocked this response to stimulation of the side of the face ipsilateral to the lesion. The experiments demonstrate: (1) pharmacological control of sensory-motor neglect, the asymmetry being determined by the direction of turning; and (2) a possible neuropharmacological basis of the perioral biting reflex, which may be related to certain types of aggressive behaviors.

Epidural anaesthesia and analgesia for liver resection

Although epidural analgesia is routinely used in many institutions for patients undergoing hepatic resection, there are unresolved issues regarding its safety and efficacy in this setting. We performed a review of papers published in the area of anaesthesia and analgesia for liver resection surgery and selected four areas of current controversy for the focus of this review: the safety of epidural catheters with respect to postoperative coagulopathy, a common feature of this type of surgery; analgesic efficacy; associated peri-operative fluid administration; and the role of epidural analgesia in enhanced recovery protocols. In all four areas, issues are raised that question whether epidural anaesthesia is always the best choice for these patients. Unfortunately, the evidence available is insufficient to provide definitive answers, and it is clear that there are a number of areas of controversy that would benefit from high-quality clinical trials.

Oxytocinergic innervation of the rat spinal cord. An electron microscopic study

Pre- and postembedding immunocytochemical procedures were used, together with antisera raised against oxytocin or its neurophysin, to characterize oxytocinergic pathways in the rat spinal cord, at the electron microscopic level. Pre-embedding immunoperoxidase staining performed on vibratome sections revealed oxytocin- and neurophysin-positive axonal profiles and terminals scattered predominantly in laminae I and II of the dorsal horn and in the central gray (lamina X). They were also visible, but to a lesser extent, in the intermediolateral columns, at thoracic and lumbar levels. Postembedding immunogold staining performed directly on ultrathin sections of the same areas, fixed in osmium and embedded in resin, permitted to show clearly that the oxytocinergic axons made symmetrical and asymmetrical synaptic contacts onto dendritic profiles. It also allowed subcellular localization of the neuropeptide immunoreactivities which were restricted to relatively large, electron-dense vesicles in the immunopositive terminals. Oxytocinergic terminals were never seen to participate in glomerular configurations in the superficial layers of the dorsal horn nor were immunoreactive cell bodies visible in any spinal area. Our results provide direct morphological evidence that oxytocinergic pathways make synapses in several regions of the spinal cord, thus supporting the contention that oxytocin may exert neurotransmitter/neuromodulator actions in this area of the CNS.

Intrahospital transport of critically ill patients

Severe complications sometimes occur in critically ill patients during intrahospital transport. Possible causes may be inadequate ventilation, insufficient monitoring, interrupted application of vasoactive drugs, or disconnections and accidental extubation. We constructed a transport unit equipped with a respirator; capnometer; monitor to measure ECG, arterial and intracranial pressures, and temperature; and two syringe pumps that can be connected easily to the patient's bed. Gas is supplied by cylinders with oxygen and air. Electrical power is supplied by two accumulators connected to recharger and transformer devices that deliver 220 V (110 V). Since this transfer unit was introduced, we have had no unanticipated problems during intrahospital ICU patient transport.

The frequency of chromosome anomalies in human preimplantation embryos after in-vitro fertilization

Previous studies have reported chromosome aberrations in human pre-embryos after in-vitro fertilization (IVF). Although the reason for these abnormalities is not clear, there is evidence that they can arise during gametogenesis, fertilization or cleavage. The present study has examined further the incidence of chromosome abnormalities in human pre-embryos after IVF, using oocytes recovered from normal volunteer women and from women undergoing infertility treatment in an embryo-replacement programme. Chromosome preparations were performed for 75 pre-embryos. Of these 35 (47%) gave at least one metaphase in which analysis was possible. The overall incidence of abnormal pre-embryos was 40% (14/35). The absolute frequency of aberrations was 9% for trisomies, 3% for polyploidies, 26% for structural anomalies and 3% for hypodiploidies. Five pre-embryos were found to be mosaics, three of which had each one trisomic metaphase. In five of the pre-embryos multiple anomalies were found. In 13 of the 14 abnormal pre-embryos the aberrations were found in only one metaphase. The present study demonstrates that trisomic mosaicism may not be a rare event in human pre-embryos. Further evidence is provided that mitotic non-disjunction is important for the production of aberrations in human pre-embryos.

Turning behavior after unilateral lesion of the subthalamic nucleus in the rat

Unilateral stereotaxic lesions of the subthalamic nucleus of rats with kainic acid induced a transient spontaneous ipsiversive turning which was present for several days, and which could be blocked by i.p. administration of haloperidol. After the 20th postoperative day, when no spontaneous turning activity was present, i.p. administration of apomorphine or amphetamine in the kainic acid lesioned rats induced ipsiversive turning, while i.p. haloperidol in the same rats induced contraversive turning. These findings suggest that the subthalamic nucleus is involved in the dopaminergic mechanisms mediating turning behavior of rats.

Cardiac troponin I in fulminant adenovirus myocarditis treated with a 24-hour infusion of high-dose intravenous immunoglobulin

We report a successful outcome on an acute adenovirus myocarditis treated with a 24-hour high-dose intravenous immunoglobulin (24-HDIVIG) in a 4.5-year-old girl. A postviral etiology of acute myocarditis was assessed on the basis of the polymerase chain reaction technique. Among other early markers of cardiac injury, cardiac isoform of troponin-I (cTnI) was significantly correlated to the left ventricular ejection fraction (r = -0.86, p < 0.0001). Follow-up of cTnI, which might also be correlated to the short-term outcome, allows fast, easy, and noninvasive estimation of response to the aggressive treatment with 24-HDIVIG in acute adenovirus myocarditis in children.

The frequency of chromosome anomalies in human unfertilized oocytes and uncleaved zygotes after insemination in vitro

Data on first trimester human abortions have shown chromosome aberrations in approximately 50% of the cases, most of which were trisomies. More than 80% of these trisomies have been attributed to an error in the oocyte. In this study we investigated the frequency of chromosome anomalies in 44 human unfertilized oocytes and 13 uncleaved zygotes after insemination in vitro. The oocytes were aspirated from preovulatory follicles in parous volunteer donors and patients participating in an embryo replacement programme. Thirty cases could be analysed, 18 of which (60%) carried a chromosome abnormality. There were two hyperhaploidies (6.7%), four hypohaploidies (13.3%), three polyploidies (10%), six with structural aberrations (20%) and five diploidies (16.7%). The incidence of these abnormalities, except for the structural anomalies, was similar to that reported previously. The higher frequency of structural aberrations in the present study may be related to delayed cytogenetic analysis for up to 48 h after insemination.

Expression of the glucocorticoid receptor in the human adrenal cortex

Glucocorticoids produced in the adrenal cortex act by binding to a specific intracellular protein, the glucocorticoid receptor (GR), which then modulates gene transcription in target tissues. Whether the adrenal cortex itself is a glucocorticoid target tissue has not been analyzed as yet. Since the presence of GR would be a prerequisite for such "intracortical" glucocorticoid action, this study was designed to analyze GR expression in the normal human adrenal gland using RT-PCR, Western blot, and immunohistochemistry. RT-PCR revealed the presence of GR mRNA in adrenal cortex as well as in NCIh295 cells. These results were confirmed at the protein level by Western blot employing a specific anti-human GR antibody. Immunohistochemically, weak GR staining was observed in the adrenal medulla. In contrast, GR was strongly expressed in the adrenal cortex with the zona reticularis showing the most intense staining. Transfection of a GR-responsive luciferase reporter gene into NCIh295 cells resulted in dexamethasone-dependent induction of luciferase activity, indicating that GR is functional in this tissue. In this study, we show for the first time that GR is expressed in the human adrenal cortex. Its preferential expression in the zona reticularis may indicate a functional role in the regulation of adrenal androgen biosynthesis.

Use of a simplified dilute Russell's viper venom time (DRVVT) confirms heterogeneity among 'lupus anticoagulants'

A simplified dilute Russell's viper venom time (DRVVT) test--in which the venom, trace phospholipid and calcium were combined into a single reagent--was evaluated for the detection of lupus anticoagulants (LA) in 28 plasma samples containing non-specific circulating anticoagulants. In agreement with previous studies, the DRVVT was found to be insensitive to defects in contact and haemophilic factors and was only marginally affected by antibodies directed against factor VIII. Thus, the use of a DRVVT test in investigations of anticoagulants reduces the risk of confusing a haemorrhagic inhibitor of factor VIII with a non-haemorrhagic LA. In comparisons of sensitivity against activated partial thromboplastin time tests (APTT-Actin FSL and Organon-Teknika reagents) the simplified DRVVT was prolonged slightly more than the APTT in most of the test plasmas containing various non-specific circulating anticoagulants. Three anticoagulants affecting APTTs more than the DRVVT were found to be associated with anticardiolipin IgMs. APTT-prolonging anticoagulants, whether prolonging DRVVT tests or not, showed similar 'correction' of their APTTs by the addition of platelets or phospholipid. Thus, phospholipid-dependent or LA show heterogeneity. Those affecting only the APTT and not DRVVT should perhaps be classified differently.

Removal of the telencephalon spares turning induced by injection of GABA agonists and antagonists into the substantia nigra

Unilateral injections into the substantia nigra of GABA agonists or the GABA-related agents muscimol (5-50 ng), baclofen (10-50 ng) or B-aminobutyric acid (25-50 ug) induced intensive turning in the direction contralateral to the injected hemisphere. Intranigral injection of the GABA antagonist picrotoxin (100-500 ng) led to ipsiversive turning. Surgical removal of the whole telencephalon (including the neocortex, hippocampus, striatum, septal nuclei and amygdalae) influenced neither direction nor magnitude of the turning responses induced by these various drugs. A GABAergic system in the substantia nigra can, therefore, cause turning independent of telencephalic structures.

Three- versus six-month adjuvant FOLFOX or CAPOX for high-risk stage II and stage III colon cancer patients: the efficacy results of Hellenic Oncology Research Group (HORG) participation to the International Duration Evaluation of Adjuvant Chemotherapy (IDEA) project

BACKGROUND

The International Duration Evaluation of Adjuvant Chemotherapy (IDEA) aimed to investigate whether a 3 months (3M) of oxaliplatin/fluoropyrimidine-based adjuvant chemotherapy (CT) is non-inferior to the 6-month (6M) administration in 3-year disease-free survival (3yDFS) in high-risk (HR) stage II or stage III colon cancer (CC).

METHODS

Hellenic Oncology Research Group (HORG)-IDEA randomized patients between 3M and 6M of CT with FOLFOX4 or CAPOX.

RESULTS

In total 1115 patients, 413 with HR stage II and 702 with stage III CC, were randomized. The median follow-up was 67.0 (38.3-126.0) months. Overall, 394 DFS events (202 in 3M arm and 192 in 6M arm) where recorded. The 3yDFS rate was 77.2% [95% confidence interval (CI) 72.1% to 82.3%] for 3M and 77.9% (72.6% to 82.5%) for 6M of treatment [hazard ratio (HR) 1.05 (95% CI 0.61-1.55); P = 0.647]. Eighty DFS events (3M N = 41; 6M N = 39) were observed in HR stage II patients for a 3yDFS rate of 82.7% and 83.4%, respectively (HR 1.05; 95% CI 0.68-1.63, P = 0.829). For stage III patients, 314 DFS events (3M N = 161 and 6M N = 153) were observed, for a 3yDFS rate of 72.9% for 3M versus 74.1% for 6M (HR 1.06; 95% CI 0.81-1.42, P = 0.622). For HR stage II patients receiving FOLFOX4, 3yDFS rate was 76.7% for 3M and 79.3% for 6M (HR 1.21; 95% CI 0.54-2.70). For HR stage II patients receiving CAPOX the 3yDFS rate was 85.4% for 3M and 83.8% for 6M (HR 0.99; 95% CI 0.59-1.67). For stage III patients receiving FOLFOX4, the 3yDFS rate was 71.5% for 3M and 77.3% for 6M (HR 1.18; 95% CI 0.74-1.86). For stage III patients receiving CAPOX, the 3yDFS rate was 74.5% for 3M and 74.7% for 6M (HR 0.99; 95% CI 0.70-1.44).

CONCLUSIONS

The results of the HORG-IDEA study are in line with those of the global IDEA project, indicating that the 3yDFS is dependent on the administered adjuvant regimen and the choice and duration of regimen should be personalized.

CLINICALTRIALS.GOV REGISTRATION NUMBER

NCT01308086.

Diagnostic Correlation of CT-MRI and Histopathology in 10 Dogs with Brain Neoplasms

Ten dogs with primary (n = 8) and metastatic (n = 2) brain tumours were studied in an attempt to evaluate the diagnostic sensitivity of computed tomography (CT) or magnetic resonance imaging (MRI). Of the clinical signs noticed, seizures (seven of 10), behavioural abnormalities and cognition dysfunction (seven of 10), compulsive walking and circling (six of 10), sensorimotor (five of 10) and neuro-opthalmological (two of 10) dysfunction were the most common. In all 10 animals that finally died of the disease or were killed, the histopathological diagnosis that followed necropsy was taken as a golden standard in the CT or MRI prediction of the histological type of brain neoplasms. In every instance, tumour detection, morphology and histological differentiation were possible with the aid of either CT (seven of 10) or MRI (three of 10) imaging especially after contrast enhancement. Only one CT-evaluated dog, diagnosed as meningioma, was found to be astrocytoma on histopathology. Interestingly, a rare case of cerebellar medulloblastoma was correctly identified in MRI scans.