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PubMed2003

Brain surgery in motor areas: the invaluable assistance of intraoperative neurophysiological monitoring.

AIM: Surgery for tumors in the central and precentral region, as much as for insular tumors, places at risk the functional integrity of the motor cortex and the subcortical motor pathways. These procedures may therefore benefit from the assistance of intraoperative neurophysiological monitoring (INM). INM consists of "mapping" and true "monitoring" (the continuous "on-line" assessment of the functional integrity of neural pathways) techniques. In spite of the large interest in mapping techniques, monitoring techniques have received less attention. We describe our experience with intraoperative neurophysiological mapping and monitoring of motor tracts during surgery for brain gliomas in or near motor areas, in order to support the feasibility and reliability of monitoring as an essential adjunct to mapping during surgery in these areas. METHODS: Between September 2000 and January 2002, 51 patients were surgically treated for brain gliomas located in the precentral gyrus (45.1%), the postcentral gyrus (23.5%), anterior to the precentral gyrus (15.6%), or in the insula (15.6%). INM of the motor system consisted of monitoring muscle motor evoked potentials (mMEPs) recorded via needle electrodes inserted into the controlateral upper and lower extremity muscles and elicited by transcranial multipulse electrical stimulation (TES). Once the dura was open and the central sulcus was identified using the phase reversal technique, mMEPs were elicited by direct stimulation of the motor cortex (DCS). Motor mapping was performed with a monopolar electrode using the same stimulation parameters as used for monitoring except for much lower intensity (up to 20 mA). RESULTS: Ninety-eight percent of the patients exhibited recordable baseline mMEPs. The success rate of the phase reversal technique was 95.8%. Eight patients presented disappearance of mMEPs during tumor removal. Using corrective measures, all intraoperative changes in mMEPs were reversed in time to prevent an irreversible complete injury to the motor system and no patient lost mMEPs at the end of the operation. At discharge, 66% of the patients remained at their preoperative status, 4% improved, and 24% had a mild worsening as compared to the preoperative status assessed using the Medical Research Council scale; 6% of the patients presented a moderate to severe supplementary motor area syndrome. CONCLUSION: Monitoring techniques significantly implement the reliability and effectiveness of INM since these provide: 1) continuous "on-line" assessment of the functional integrity of motor pathways with higher chance to early detect a progressive mechanical or vascular injury to the neural tissue, as compared to mapping techniques; 2) lower risk to induce intraoperative seizures and strong muscular twitches as compared to the single pulse mapping technique; 3) possibility to monitor motor pathways using TES also when there is no direct access to the motor cortex.

Adult↗

PubMed1993

The contribution of cytochrome P450-dependent arachidonate metabolites to integrated renal function.

Arachidonic acid can be metabolized to diverse products which differ widely in their biological activities. These metabolites affect basic biological mechanisms such as vascular reactivity and transport function in critical nephron segments. Metabolism of arachidonic acid is discretely localized to specific cells and differs within segments of the nephron; for example, cells of the medullary ascending limb of Henle's loop have a considerable capacity to generate cytochrome P450-dependent arachidonate metabolites but have negligible cyclooxygenase activity. Arachidonic acid metabolites participate in fluid and electrolyte homeostasis, and in the regulation of tissue blood flow, and act as modulators of vasoactive hormones, and, thereby, make important contributions to integrated renal function.

Animals↗

PubMed2001

Protein overexport in a Saccharomyces cerevisiae mutant depends on mitochondrial genome integrity and function.

The wild-type yeast Saccharomyces cerevisiae (S. cerevisiae) is able to export less than 1 percent of the protein to be secreted. The reasons for retention of most of the secretory proteins on the cell surface of S. cerevisiae are unknown. Recently, temperature-sensitive (ts) mutants of S. cerevisiae showing an oversecretion phenotype were isolated. In order to study the influence of the mitochondrial genome status on protein export in yeast cells, we have isolated several types of respiratory impaired mitochondrial mutants of either the parental S. cerevisiae strain or their derivative ts protein-overexporting mutants. In this paper we demonstrate by quantitative analyses of exported proteins and by SDS-PAGE analysis that protein overexport in ts mutants requires mitochondrial genome integrity and function.

Blotting, Southern↗

PubMed2002

Differences in the abilities of estrogen receptors to integrate activation functions are critical for subtype-specific transcriptional responses.

Estrogen receptors (ER) alpha and beta are members of a superfamily of nuclear receptors and mediate estrogen [17beta-estradiol (E2)] signaling. ERbeta has considerably less transcription potency than ERalpha in heterologous expression systems that use E2 response elements (ERE) in tandem as the trans-acting unit. We show here that despite similar intracellular characteristics, ERbeta, in contrast to ERalpha, fails to induce gene transcription synergistically in response to E2 from tandem EREs. Moreover, our results indicate that ERalpha-specific partial agonistic activity of antagonists occurs additively. Although synergy contributes, it is not sufficient for differences in the transcription potencies between the ER subtypes. We demonstrate here that differences in the abilities of ERs to integrate activation functions through functional interactions between amino and carboxyl termini are critical for the transcriptional strength of ER subtypes.

Animals↗

PubMed1993

A new portable device for automatic controlled-gradient cryopreservation of blood mononuclear cells.

Protection of the functional integrity of mononuclear cells stored in liquid N2 requires careful control of the freezing procedure. Consequently, optimal quality of cryopreserved cells is usually assured by freezing according to a specified time-temperature gradient generated by computer-controlled freezing devices. While such equipment offers large capacity and secures maximum survival and functional integrity of the lymphocytes upon thawing, it is quite costly and strictly stationary. We have previously developed and tested an alternative, manual device for controlled-gradient lymphocyte freezing, which has proved suitable for field conditions. We report here the development and testing of a similar micro-controller regulated device, allowing unattended and automatic controlled-gradient cell freezing. The equipment exploits the temperature gradient present between the liquid N2 surface and the neck in an ordinary liquid N2 refrigerator. The lymphocyte samples are placed in a small elevator, which is moved through the N2 gas phase by a stepper motor. Time and temperature are measured at regular intervals, and the position of the samples adjusted to ensure that the actual measurements closely match encoded ideal values. Results of assays of the functional integrity and phenotypic composition of human mononuclear cells frozen by the new system were comparable to those obtained when using cells frozen by a commercially available, stationary cell-freezing equipment, or fresh autologous cell samples tested in parallel. Furthermore, there was a good correlation between functional and phenotypic data obtained using frozen and autologous fresh samples of mononuclear cells. The equipment described is low weight and has low N2 consumption, and is thus suitable for the collection and cryopreservation of lymphocytes under field conditions. Furthermore, the technique provides an inexpensive alternative for researchers with a limited requirement for the simultaneous freezing of large quantities of cells.

Blood Preservation↗

PubMed2001

The integration of functional and fixed appliance treatment.

This article describes a functional appliance system to correct Class II problems, which is clipped on to bands, cemented to the teeth. This appliance has several advantages, as the patient cannot remove it. It acts on the teeth and jaws for 24 hours each day, patient co-operation is not a problem, and as a result the treatment time is short. Any fixed appliance system can be added while the functional phase is being completed so allowing full integration of the two treatment systems.

Child↗

PubMed1993

Transactivating function of integrated hepatitis B virus.

HBV DNAs are often found in integrated forms in human hepatocellular carcinoma (HCC). Discovery of a transactivation function coded by a limited region of the HBV genome has promoted us to survey our collection of HBV integrants with flanking cellular sequences, asking whether they might exhibit a transactivation function. In transient cotransfection assays using the HepG2 cell line, six out of the twelve integrants showed transactivation effects on the expression of cellular genes such as c-fos. These results strongly demonstrate that the transactivating effects of integrated HBV DNA are widely distributed, and some of these effects might be correlated to hepatocarcinogenesis.

Carcinoma, Hepatocellular↗

PubMedDate not supplied

Convergence insufficiency in brain-injured patients.

Disorders of eye movements are relatively common in brain-injured patients. Some of these disturbances are caused by direct trauma to the orbital content, cranial nerves and other brain areas. Convergence, which is a part of the near-vision complex and depends on the integrative function of the cortical and subcortical areas, is commonly affected by traumatic brain injury. Intact vergence needs the integrative function of brain structures associated with acquisition of information on one side and intact mesencephalic function, including function of a vergence integrator, and their interconnections. Clinical investigation of vergence function in 26 traumatically brain-injured patients examined as early as possible after trauma revealed disturbances in over a third of the examinees. A follow-up of 72 patients some 3 years after injury revealed vergence insufficiency in 42%. Convergence insufficiency was associated with longer periods of coma (p less than 0.001), presence of cognitive disturbances (p less than 0.005) and patients' failing to find work in the open market (p less than 0.01). It is suggested that the presence of disturbed vergence several years after trauma, and its close association with prolonged coma and cognitive disturbances, is an expression of permanent damage to mesencephalic and cortical brain structures and can serve as an important aid in evaluation of these patients. This paper describes the close relationship between vergence state and over-all rehabilitation outcome as evaluated by patients' occupational status.

Adult↗

PubMed2005

Engineering a dopaminergic phenotype in stem/precursor cells: role of Nurr1, glia-derived signals, and Wnts.

Recent results from clinical trials using fetal tissue grafts in patients with Parkinson's disease (PD) have indicated that current surgical strategies for dopamine cell replacement therapy need to be improved in order to achieve better functional integration of the grafts and to avoid dyskinesias. Previous studies using rich dopaminergic (DA) cell suspensions have provided proof-of-concept that PD patients can benefit from cell replacement therapy. Stem cells have been proposed as better candidates for cell replacement therapy in PD since they can be standardized, expanded, and engineered in vitro. Recent developments indicate that cell preparations enriched in DA neurons can be generated in vitro, but their functional integration in animal models of disease is still far from optimal. This is not entirely surprising considering our limited knowledge of the development of DA neurons and the reduced number of factors that have been implemented in stem cell differentiation protocols. This review will focus on three aspects of DA neuron development: (1) the function of Nurr1 and retinoid X receptors (RXR) in the differentiation of DA precursors and in the survival of DA neurons; (2) the role of glia in DA neurogenesis and the differentiation of DA precursors; and (3) the function of the Wnt family of lipoproteins in the proliferation and differentiation of DA precursors. A greater understanding of the cellular and molecular mechanisms that control DA neuron development, as well as their functional integration in vivo, are likely to ultimately contribute to the development of novel stem cell replacement therapies for PD.

Animals↗

PubMed2005

Saccharomyces cerevisiaeTSC11/AVO3 participates in regulating cell integrity and functionally interacts with components of the Tor2 complex.

Saccharomyces cerevisiae TSC11/AVO3 is an essential gene encoding one component of TORC2, a multi-protein complex of yeast Tor2p that also contains Lst8p, Avo1p, and Avo2p. Despite the proven physical association among TORC2 components, little is known about the functional linkage or cellular pathways these proteins act in. Here, we present genetic data linking the function of TSC11 to the regulation of cell integrity. Mutants carrying temperature-sensitive (ts) alleles in different regions of TSC11 displayed cell wall defects, evidenced by characteristic osmotic stabilizer-remediable cell lysis, susceptibility to trypan blue staining, and sensitivity to cell wall-digesting enzymes. Dosage suppression analysis identified different groups of genes in rescuing phenotypes of different tsc11(ts) mutants. AVO1 suppressed one class of mutants, whereas active PKC1, AVO2, and SLM1 partially rescued another. Our findings demonstrate functional connections among TORC2 components and we speculate that Tsc11p exerts its function via a Pkc1p-independent mechanism mediated through Avo1p, and a Pkc1p-dependent mechanism mediated through Avo2p and Slm1p.

Actins↗

PubMed2005

Comparison between glycerol and ethylene glycol for dog semen cryopreservation.

The aim of this study was to compare the effect of ethylene glycol versus glycerol for dog semen freezing, on post-thaw longevity, motility and motility parameters, and on plasma membrane functional integrity. Semen was diluted in two steps with an egg yolk TRIS extender containing a final concentration of either 5% glycerol or 5% ethylene glycol, and frozen in 0.5 ml straws, with 100 x 10(6) spermatozoa/ml, over nitrogen vapours. Semen motility was evaluated both under a light microscope and with a Computer Assisted Motility Analyser System, immediately after thawing and then hourly till 4h of incubation. Sperm membrane functional integrity was assessed with the hypoosmotic swelling test (60 mOsm fructose solution) applied at thawing and then hourly, for 4 h, on incubated samples. Motility (light microscope) and total and progressive motility (analyser) were significantly higher in ethylene glycol frozen samples at thawing (P < 0.01); from hour 1 onwards the effect of the cryoprotectant became not significant. Semen frozen with ethylene glycol showed higher path velocity and higher straight line velocity till 3 h after thawing; however, ethylene glycol semen samples also showed higher curvilinear velocity and higher lateral head displacement, which may indicate a capacitation-like condition affecting sperm membranes and possibly reducing post-thaw longevity. Functional integrity of plasma membrane was similar in glycerol and ethylene glycol samples till 3 h after thawing, then ethylene glycol samples showed a higher decline. The strong though short-lived positive effect of ethylene glycol is worth being evaluated further.

Animals↗

PubMed1984

A mutant murine leukemia virus with a single missense codon in pol is defective in a function affecting integration.

We have used site-directed mutagenesis of cloned Moloney murine leukemia virus (MuLV) DNA to define a function encoded in the 3' region of the viral pol gene and required for efficient integration of viral DNA. One mutant, MuLV-SF1, contained a single base substitution (C to T at base 4950) that resulted in an arginine to cysteine change in a region highly conserved among retroviruses. Mutant DNA, introduced into rat cells by cotransfection with a herpes simplex virus thymidine kinase gene (HSV tk), directed production of virus particles with reverse transcriptase activity. Infection of cells with these particles led to synthesis of full-length linear and circular forms of unintegrated viral DNA; however, integrated viral DNA was decreased at least by a factor of 10 when examined by DNA hybridization, and the mutant particles were less efficient then wild-type virus at establishing an infection by a factor of at least 300. Pseudotypes formed with the proteins of MuLV-SF1 and the genome of a replication defective marker MuLV, carrying the HSV tk gene, were less effective by at least a factor of 100 in producing tk+ colonies than pseudotypes formed with proteins encoded by wild-type virus. When the MuLV-SF1 pseudotypes did produce tk+ cells, most of the proviruses were integrated aberrantly. We conclude that the MuLV-SF1 pol gene is defective for a function that is required for normal integrative recombination and dissociable from DNA synthesis.

Cell Transformation, Viral↗

PubMed1988

Influence of ascending serotonergic pathways on glucose use in the conscious rat brain. II. Effects of electrical stimulation of the rostral raphé nuclei.

Although lesions of the rostral raphé nuclei have minimal effects on integrated functional activity, as studied by the 2-deoxyglucose technique, the repercussions of activating the ascending serotonergic pathways have yet to be reported in the literature. To examine this question, we studied the consequences of the electrical stimulation of the rostral (median or dorsal) raphé nuclei on local cerebral glucose use in the conscious rat. Glucose use was determined by quantitative autoradiography in 105 defined brain structures. Raphé stimulation increased glucose utilization in a number of well-defined structures and pathways, dorsal raphé stimulation being systematically more effective than median raphé stimulation. Of all the neocortical regions studied, only the somatosensory cortex displayed a columnar and laminar pattern of increased glucose use that was restricted to the somatotopic delineation of the rat's head and face. Increased glucose use was seen in almost all key elements of the extrapyramidal system with the notable exception of the caudate-putamen. The thalamic nuclei that were activated by rostral raphé stimulation included those that subserve the processing of somesthetic, accessory visual and limbic information. Raphé stimulation-induced decreases in local cerebral glucose use were never observed. Almost all of the induced changes could be prevented or obtunded by prior intraventricular administration of the serotonergic neurotoxin 5,7-dihydroxytryptamine, suggesting that the majority of the raphé-induced changes in integrated functional activity were mediated via the activation of serotonergic neurones. The magnitude and pattern of the increases in glucose use could not always be correlated with the regional density of serotonergic innervation nor with the distribution of 5-hydroxytryptamine receptor subtypes in the adult brain. However, the pattern of increased cortical glucose use closely matches the selective serotonergic innervation of the somatosensory cortex found in early postnatal development. Thus, it would appear that the 2-deoxyglucose technique reveals functional units in the cortex that are innervated at an early ontogenic stage. We postulate that the discrete and highly organized changes in integrated functional activity that follow raphé stimulation are due to serotonin acting in a phasic manner on restricted, possibly specialized, postsynaptic structures.(ABSTRACT TRUNCATED AT 400 WORDS)

5,7-Dihydroxytryptamine↗

PubMed1982

The integrative sensorimotor function of the LP-pulvinar complex.

An important number of studies have paid attention to the sensorial function of the LP-pulvinar complex and its probable polisensorial integrative role. In the present review, on the basis of some experimental results, we have tried to emphasize the importance of the LP-pulvinar complex in the motor function. In this sense, this thalamic complex appears as a probable sensorimotor integrative structure. Considering the behavior elicited by electrical as well as chemical stimulation of the LP-pulvinar complex, it would seem that this structure is related to the type of behavior that researches and examines the environment, mainly, by internal motivation. Furthermore, the possible role of the LP-pulvinar complex in the sleep and wakefulness mechanism and in the epileptic phenomena, is mentioned.

Animals↗

PubMed1997

Synaptic integration of functionally diverse pallidal information in the entopeduncular nucleus and subthalamic nucleus in the rat.

To determine the principles of synaptic innervation of neurons in the entopeduncular nucleus and subthalamic nucleus by neurons of functionally distinct regions of the pallidal complex, double anterograde labeling was carried out at both light and electron microscopic levels in the rat. Deposits of the anterograde tracers Phaseolus vulgaris-leucoagglutinin and biotinylated dextran amine were placed in different functional domains of the pallidal complex in the same animals. The tracer deposits in the ventral pallidum and the globus pallidus gave rise to GABA-immunopositive projections to the entopeduncular nucleus, the subthalamic nucleus, and the more medial lateral hypothalamus that were largely segregated but overlapped at the interface between the two fields of projection. In these regions the proximal parts of individual neurons in the entopeduncular nucleus, lateral hypothalamus, and subthalamic nucleus received synaptic input from terminals derived from both the ventral pallidum and the globus pallidus. Furthermore, the analysis of the afferent synaptic input to the dendrites of neurons in the subthalamic nucleus that cross functional boundaries of the nucleus defined by the pallidal inputs, revealed that terminals with the morphological and neurochemical characteristics of those derived from the pallidal complex make synaptic contact with all parts of the dendritic tree, including distal regions. It is concluded that functionally diverse information carried by the descending projections of the pallidal complex is synaptically integrated by neurons of the entopeduncular nucleus, lateral hypothalamus, and subthalamic nucleus by two mechanisms. First, neurons located at the interface between functionally distinct, but topographically adjacent, projections could integrate diverse information by means of the synaptic convergence at the level of the cell body and proximal dendrites. Second, because the distal dendrites of neurons in the subthalamic nucleus receive input from the pallidum, those that extend across two distinct domains of pallidal input could also provide the morphological basis of integration.

Afferent Pathways↗

PubMed2003

Maintenance of integrity and function of isolated hepatocytes during extended suspension culture at 25 degrees C.

Isolated hepatocytes in suspension provide a number of advantages for use in bioartificial liver device, however, poor stability of this cell preparation at physiological temperatures is an apparent barrier preventing their use. We therefore investigated the integrity and differentiated function of isolated rat hepatocytes under conditions of mild hypothermia. Isolated hepatocytes were suspended in a bicarbonate buffered saline medium, supplemented with glucose and bovine serum albumin (BSA), and maintained for 48 h at 25 degrees C on a rotary shaker under an atmosphere of 95% O2 and 5% CO2. Under these conditions there was no significant decline in cell viability and good preservation of cellular morphology on transmission electron microscopy for at least 24 h. Isolated hepatocytes in suspension at 25 degrees C were also able to maintain normal Na+ and K+ ion gradients. The cellular energy status ([ATP], ATP/ADP ratio, cytoplasmic and mitochondrial redox potentials), metabolic function (urea synthesis and ammonia removal), albumin synthesis and phase I and phase II drug detoxification activity of these cells were also maintained for at least 24 h post isolation. These observations demonstrate the robust nature of mildly hypothermic isolated hepatocytes in suspension and encourage further studies re-examining the feasibility of using this cell preparation in bioartificial livers.

Animals↗

PubMed2006

Fibers from the dorsal premotor cortex elicit motor-evoked potential in a cortical dysplasia.

OBJECTIVE: To identify the fibers originating from the dorsal premotor cortex (dorsal PMC) that contribute to motor-evoked potentials (MEP), we have applied integrated functional neuronavigation and awake surgery during removal of an epileptic cortical dysplasia located in the right premotor cortex. METHODS: Chronic subdural electrodes were employed for functional mapping during a routine invasive evaluation for intractable epilepsy. After the fibers originating from the dorsal PMC were plotted into the tractography-integrated functional neuronavigation, subcortical MEPs and clinical symptoms were examined during resection of the epileptogenic dorsal PMC. RESULTS: During removal of the epileptogenic area, MEPs were elicited by electrical stimulation of the fibers originating from the dorsal PMC, which were separated from the pyramidal tracts from the precentral gyrus. Resection of the dorsal PMC and its fibers caused a transient dysmetric movement of the left toe without motor weakness. CONCLUSION: Functional corticospinal tract fibers originating from the dorsal PMC can be defined and removed safely under local anesthesia with the aid of integration of functional neuronavigation and subcortical electrical stimulation.

Adolescent↗

PubMed2003

Structure and function of integral membrane protein domains resolved by peptide-amphiphiles: application to phospholamban.

We have used synthetic lipidated peptides ("peptide-amphiphiles") to study the structure and function of isolated domains of integral transmembrane proteins. We used 9-fluorenylmethyloxycarbonyl (Fmoc) solid-phase peptide synthesis to prepare full-length phospholamban (PLB(1-52)) and its cytoplasmic (PLB(1-25)K: phospholamban residues 1-25 plus a C-terminal lysine), and transmembrane (PLB(26-52)) domains, and a 38-residue model alpha-helical sequence as a control. We created peptide-amphiphiles by linking the C-terminus of either the isolated cytoplasmic domain or the model peptide to a membrane-anchoring, lipid-like hydrocarbon tail. Circular dichroism measurements showed that the model peptide-amphiphile, either in aqueous suspension or in lipid bilayers, had a higher degree of alpha-helical secondary structure than the unlipidated model peptide. We hypothesized that the peptide-amphiphile system would allow us to study the function and structure of the PLB(1-25)K cytoplasmic domain in a native-like configuration. We compared the function (inhibition of the Ca-ATPase in reconstituted membranes) and structure (via CD) of the PLB(1-25) amphiphile to that of PLB and its isolated transmembrane and cytoplasmic domains. Our results indicate that the cytoplasmic domain PLB(1-25)K has no effect on Ca-ATPase (calcium pump) activity, even when tethered to the membrane in a manner mimicking its native configuration, and that the transmembrane domain of PLB is sufficient for inhibition of the Ca-ATPase.

Buffers↗