Mechanism of hyperinsulinism in short-chain 3-hydroxyacyl-CoA dehydrogenase deficiency involves activation of glutamate dehydrogenase

The mechanism of insulin dysregulation in children with hyperinsulinism associated with inactivating mutations of short-chain 3-hydroxyacyl-CoA dehydrogenase (SCHAD) was examined in mice with a knock-out of the hadh gene (hadh(-/-)). The hadh(-/-) mice had reduced levels of plasma glucose and elevated plasma insulin levels, similar to children with SCHAD deficiency. hadh(-/-) mice were hypersensitive to oral amino acid with decrease of glucose level and elevation of insulin. Hypersensitivity to oral amino acid in hadh(-/-) mice can be explained by abnormal insulin responses to a physiological mixture of amino acids and increased sensitivity to leucine stimulation in isolated perifused islets. Measurement of cytosolic calcium showed normal basal levels and abnormal responses to amino acids in hadh(-/-) islets. Leucine, glutamine, and alanine are responsible for amino acid hypersensitivity in islets. hadh(-/-) islets have lower intracellular glutamate and aspartate levels, and this decrease can be prevented by high glucose. hadh(-/-) islets also have increased [U-(14)C]glutamine oxidation. In contrast, hadh(-/-) mice have similar glucose tolerance and insulin sensitivity compared with controls. Perifused hadh(-/-) islets showed no differences from controls in response to glucose-stimulated insulin secretion, even with addition of either a medium-chain fatty acid (octanoate) or a long-chain fatty acid (palmitate). Pull-down experiments with SCHAD, anti-SCHAD, or anti-GDH antibodies showed protein-protein interactions between SCHAD and GDH. GDH enzyme kinetics of hadh(-/-) islets showed an increase in GDH affinity for its substrate, α-ketoglutarate. These studies indicate that SCHAD deficiency causes hyperinsulinism by activation of GDH via loss of inhibitory regulation of GDH by SCHAD.

RNAi targeting micro-calpain increases neuron survival and preserves hippocampal function after global brain ischemia

The calpain family of cysteine proteases has a well-established causal role in neuronal cell death following acute brain injury. However, the relative contribution of calpain isoforms has not been determined in in vivo models. Identification of the calpain isoform responsible for neuronal injury is particularly important given the differential role of calpain isoforms in normal physiology. This study evaluates the role of m-calpain and micro-calpain in an in vivo model of global brain ischemia. Adeno-associated viral vectors expressing short hairpin RNAs targeting the catalytic subunits of micro- or m-calpain were used to knockdown expression of the targeted isoforms in adult rat hippocampal CA1 pyramidal neurons. Knockdown of micro-calpain, but not m-calpain, prevented calpain activity 72 h after 6-min transient forebrain ischemia, increased long-term survival and protected hippocampal electrophysiological function. These findings represent the first in vivo evidence that reducing expression of an individual calpain isoform can decrease post-ischemic neuronal death and preserve hippocampal function.

Paroxysmal hemicrania responding to topiramate

Chronic paroxysmal hemicrania (CPH) is a rare primary headache syndrome, which is classified along with cluster headache and short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT) as a trigeminal autonomic cephalalgia. CPH is exquisitely responsive to indomethacin, so much so that the response is one of the current diagnostic criteria. The case of a patient with CPH, who had marked epigastric symptoms with indomethacin treatment and responded well to topiramate 150 mg daily, is reported. Cessation of topiramate caused return of episodes, and the response has persisted for 2 years. Topiramate may be a treatment option in CPH.

Arousability in schizophrenia: relationship to emotional and physiological reactivity and symptom severity

OBJECTIVE

Socioenvironmental stressors have been linked with increased symptom severity and relapse in those with schizophrenia. However, little is known about how individual differences in stress reactivity may contribute to these outcomes.

METHOD

This study examined the association between the temperament characteristic of arousability and changes in negative affect and cardiovascular activity during a challenge task in 58 in-patients with diagnosis of schizophrenia and 21 controls.

RESULTS

In the patient group, levels of arousability were significantly associated with increases in negative affect in response to the task and greater severity of affective symptoms. Levels of arousability were associated with decreased heart rate during the challenge task in our patient group.

CONCLUSION

These findings suggest that greater attention be given to individual differences, such as temperament and personality characteristics, and their role in the experience of stressors, including emotional and physiological response, as well as symptom development.

Unilateral photophobia or phonophobia in migraine compared with trigeminal autonomic cephalalgias

Our objective was to compare the presence of self-reported unilateral photophobia or phonophobia, or both, during headache attacks comparing patients with trigeminal autonomic cephalalgias (TACs)--including cluster headache, short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT) and paroxysmal hemicrania--or hemicrania continua, and other headache types. We conducted a prospective study in patients attending a referral out-patient clinic over 5 months and those admitted for an intramuscular indomethacin test. Two hundred and six patients were included. In episodic migraine patients, two of 54 (4%) reported unilateral photophobia or phonophobia, or both. In chronic migraine patients, six of 48 (13%) complained of unilateral photophobia or phonophobia, or both, whereas none of the 24 patients with medication-overuse headache reported these unilateral symptoms, although these patients all had clinical symptoms suggesting the diagnosis of migraine. Only three of 22 patients (14%) suffering from new daily persistent headache (NDPH) experienced unilateral photophobia or phonophobia. In chronic cluster headache 10 of 21 patients (48%) had unilateral photophobia or phonophobia, or both, and this symptom appeared in four of five patients (80%) with episodic cluster headache. Unilateral photophobia or phonophobia, or both, were reported by six of 11 patients (55%) with hemicrania continua, five of nine (56%) with SUNCT, and four of six (67%) with chronic paroxysmal hemicrania. Unilateral phonophobia or photophobia, or both, are more frequent in TACs and hemicrania continua than in migraine and NDPH. The presence of these unilateral symptoms may be clinically useful in the differential diagnosis of primary headaches.

Harvested human neurons engineered as live nervous tissue constructs: implications for transplantation. Laboratory investigation

OBJECT

Although neuron transplantation to repair the nervous system has shown promise in animal models, there are few practical sources of viable neurons for clinical application and insufficient approaches to bridge extensive nerve damage in patients. Therefore, the authors sought a clinically relevant source of neurons that could be engineered into transplantable nervous tissue constructs. The authors chose to evaluate human dorsal root ganglion (DRG) neurons due to their robustness in culture.

METHODS

Cervical DRGs were harvested from 16 live patients following elective ganglionectomies, and thoracic DRGs were harvested from 4 organ donor patients. Following harvest, the DRGs were digested in a dispase-collagenase treatment to dissociate neurons for culture. In addition, dissociated human DRG neurons were placed in a specially designed axon expansion chamber that induces continuous mechanical tension on axon fascicles spanning 2 populations of neurons originally plated approximately 100 microm apart.

RESULTS

The adult human DRG neurons, positively identified by neuronal markers, survived at least 3 months in culture while maintaining the ability to generate action potentials. Stretch-growth of axon fascicles in the expansion chamber occurred at the rate of 1 mm/day to a length of 1 cm, creating the first engineered living human nervous tissue constructs.

CONCLUSIONS

These data demonstrate the promise of adult human DRG neurons as an alternative transplant material due to their availability, viability, and capacity to be engineered. Also, these data show the feasibility of harvesting DRGs from living patients as a source of neurons for autologous transplant as well as from organ donors to serve as an allograft source of neurons.

Neurotrophin-mediated neuroprotection of hippocampal neurons following traumatic brain injury is not associated with acute recovery of hippocampal function

Traumatic brain injury (TBI) causes selective hippocampal cell death which is believed to be associated with the cognitive impairment observed in both clinical and experimental settings. The endogenous neurotrophin-4/5 (NT-4/5), a TrkB ligand, has been shown to be neuroprotective for vulnerable CA3 pyramidal neurons after experimental brain injury. In this study, infusion of recombinant NT-4/5 increased survival of CA2/3 pyramidal neurons to 71% after lateral fluid percussion brain injury in rats, compared with 55% in vehicle-treated controls. The functional outcome of this NT-4/5-mediated neuroprotection was examined using three hippocampal-dependent behavioral tests. Injury-induced impairment was evident in all three tests, but interestingly, there was no treatment-related improvement in any of these measures. Similarly, injury-induced decreased excitability in the Schaffer collaterals was not affected by NT-4/5 treatment. We propose that a deeper understanding of the factors that link neuronal survival to recovery of function will be important for future studies of potentially therapeutic agents.

Brain injury impairs dentate gyrus inhibitory efficacy

Every 23 s, a person sustains a traumatic brain injury in the United States leaving many patients with substantial cognitive impairment and epilepsy. Injury-induced alterations in the hippocampus underpin many of these disturbances of neurological function. Abnormalities in the dentate gyrus are likely to play a major role in the observed pathophysiology because this subregion functions as a filter impeding excessive or aberrant activity from propagating further into the circuit and following experimental brain injury, the dentate gyrus becomes more excitable. Although alteration in excitation or inhibition could mediate this effect in the dentate gyrus, we show a key role played by an impairment of GABA(A)ergic inhibition. The efficacy of GABA(A)-mediated inhibition depends on a low [Cl-]i that is maintained by neuronal K-Cl co-transporter 2 (KCC2). Using fluid percussion injury (FPI) in the mouse, we demonstrate significant reductions in KCC2 protein and mRNA expression in the dentate gyrus that causes a depolarizing shift in GABA(A) reversal potential, due to impaired chloride clearance, resulting in reduced inhibitory efficiency. This study elucidates a novel mechanism underlying diminished dentate gyrus inhibitory efficacy and provides an innovative target for the development of potential therapeutics to restore the severe pathological consequences of traumatic brain injury.

Injury-induced alterations in CNS electrophysiology

Mild to moderate cases of traumatic brain injury (TBI) are very common, but are not always associated with the overt pathophysiogical changes seen following severe trauma. While neuronal death has been considered to be a major factor, the pervasive memory, cognitive and motor function deficits suffered by many mild TBI patients do not always correlate with cell loss. Therefore, we assert that functional impairment may result from alterations in surviving neurons. Current research has begun to explore CNS synaptic circuits after traumatic injury. Here we review significant findings made using in vivo and in vitro models of TBI that provide mechanistic insight into injury-induced alterations in synaptic electrophysiology. In the hippocampus, research now suggests that TBI regionally alters the delicate balance between excitatory and inhibitory neurotransmission in surviving neurons, disrupting the normal functioning of synaptic circuits. In another approach, a simplified model of neuronal stretch injury in vitro, has been used to directly explore how injury impacts the physiology and cell biology of neurons in the absence of alterations in blood flow, blood brain barrier integrity, or oxygenation associated with in vivo models of brain injury. This chapter discusses how these two models alter excitatory and inhibitory synaptic transmission at the receptor, cellular and circuit levels and how these alterations contribute to cognitive impairment and a reduction in seizure threshold associated with human concussive brain injury.

Paroxysmal hemicrania responding to topiramate

Chronic paroxysmal hemicrania (CPH) is a rare primary headache syndrome, which is classified along with cluster headache and short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT) as a trigeminal autonomic cephalalgia. CPH is exquisitely responsive to indomethacin so much so that the response is one of the current diagnostic criteria. The case of a patient with CPH, who had marked epigastric symptoms with indomethacin treatment and responded well to topiramate 150 mg daily, is reported. Cessation of topiramate caused return of episodes, and the response has persisted for 2 years. Topiramate may be a treatment option in CPH.

Response of the contralateral hippocampus to lateral fluid percussion brain injury

Traumatic brain injury is a leading cause of death and disability in the United States. Pathological examinations of humans and animal models after brain injury demonstrate hippocampal neuronal damage, which may contribute to cognitive impairments. Data from our laboratories have shown that, at 1 week after brain injury, mice possess significantly fewer neurons in all ipsilateral hippocampal subregions and a cognitive impairment. Since cognitive function is distributed across both cerebral hemispheres, the present paper explores the morphological and physiological response of the contralateral hippocampus to lateral brain injury. We analyzed the contralateral hippocampus using design-based stereology, Fluoro-Jade (FJ) histochemistry, and extracellular field recordings in mice at 7 and 30 days after lateral fluid percussion injury (FPI). At 7 days, all contralateral hippocampal subregions possess significantly fewer healthy neurons compared to sham-injured animals and demonstrate FJ-positive neuronal damage, but not at 30 days. Both the ipsilateral and contralateral dentate gyri demonstrate significantly increased excitability at 7 days post-injury, but only ipsilateral dentate gyrus hyperexcitability persists at 30 days compared to sham. In the contralateral hippocampus, the transient decrease in the number of healthy neurons, concomitant with FJ damage, and electrophysiological alterations establish a stunned period of cellular and circuit dysfunction. The return of healthy neuron number, absence of FJ damage, and sham level of excitability in the contralateral hippocampus suggest recovery of structure and function by 30 days after injury. The cognitive recovery observed after human traumatic brain injury may stem from a differential injury exposure and time course of recovery between homologous regions of the two hemispheres.

Stretch-grown axons retain the ability to transmit active electrical signals

Little is known about extensive nervous system growth after axons reach their targets. Indeed, postnatal animals continue to grow, suggesting that axons are stretched to accommodate the expanding body. We have previously shown that axons can sustain stretch-growth rates reaching 1 cm/day; however, it remained unknown whether the ability to transmit active signals was maintained. Here, stretch-growth did not alter sodium channel activation, inactivation, and recovery or potassium channel activation. In addition, neurons generated normal action potentials that propagated across stretch-grown axons. Surprisingly, Na and K channel density increased due to stretch-growth, which may represent a natural response to preserve the fidelity of neuronal signaling.

Pharmacologically induced calcium oscillations protect neurons from increases in cytosolic calcium after trauma

Increases in cytosolic calcium ([Ca(2+)](i)) following mechanical injury are often considered a major contributing factor to the cellular sequelae in traumatic brain injury (TBI). However, very little is known on how developmental changes may affect the calcium signaling in mechanically injured neurons. One key feature in the developing brain that may directly impact its sensitivity to stretch is the reduced inhibition which results in spontaneous [Ca(2+)](i) oscillations. In this study, we examined the mechanism of stretch-induced [Ca(2+)](i) transients in 18-days in vitro (DIV) neurons exhibiting bicuculline-induced [Ca(2+)](i) oscillations. We used an in vitro model of mechanical trauma to apply a defined uniaxial strain to cultured cortical neurons and used increases in [Ca(2+)](i) as a measure of the neuronal response to the stretch insult. We found that stretch-induced increases in [Ca(2+)](i) in 18-DIV neurons were inhibited by pretreatment with either the NMDA receptor antagonist, APV [D(-)-2-Amino-5-phosphonopentanoic acid], or by depolymerizing the actin cytoskeleton prior to stretch. Blocking synaptic NMDA receptors prior to stretch significantly attenuated most of the [Ca(2+)](i) transient. In comparison, cultures with pharmacologically induced [Ca(2+)](i) oscillations showed a substantially reduced [Ca(2+)](i) peak after stretch. We provide evidence showing that a contributing factor to this mechanical desensitization from induced [Ca(2+)](i) oscillations is the PKC-mediated uncoupling of NMDA receptors (NMDARs) from spectrin, an actin-associated protein, thereby rendering neurons insensitive to stretch. These results provide novel insights into how the [Ca(2+)](i) response to stretch is initiated, and how reduced inhibition - a feature of the developing brain - may affect the sensitivity of the immature brain to trauma.

Regional analysis of sinonasal ciliary beat frequency

BACKGROUND

Mucociliary clearance, a primary host defense mechanism, depends on mucus production and its clearance by the coordinated beating of cilia lining the airways. Numerous investigations have analyzed ciliary activity in brushings from the inferior turbinate. To date, only one study has investigated whether there exists variation in ciliary beat frequency (CBF) within the sinonasal cavity. We analyzed CBF from the inferior turbinate, uncinate process, and sphenoethmoid recess in nonsinusitis patients to determine regional variability of ciliary activity within the sinonasal cavity.

METHODS

Explants of sinonasal epithelium were analyzed at 37 degrees C. Beating cilia were visualized with differential interference contrast microscopy. Images were captured using a high-speed digital camera with a sampling rate of 250 frames per second. A one-dimensional tracking algorithm analyzed individual pixel grayscale values within each frame of the video. The differences in grayscale were plotted as a time-dependent waveform, and frequency was calculated as the inverse of the peak-to-peak distance. A minimum of three areas of beating cilia were analyzed per regional sample. Statistical analysis was performed with repeated-measures analysis of variance.

RESULTS

Complete sampling of all three sites was accomplished in 10 patients. No difference in CBF within the sinonasal cavity was identified (p < 0.05). The mean CBF for all sites in all patients was 12.6 +/- 2.9 Hz, in agreement with published values.

CONCLUSION

This study shows no regional differences in CBF within the sinonasal cavity, supporting previous work and validating analysis of inferior turbinate cilia.

Mechanisms underlying the inability to induce area CA1 LTP in the mouse after traumatic brain injury

Traumatic brain injury (TBI) is a significant health issue that often causes enduring cognitive deficits, in particular memory dysfunction. The hippocampus, a structure crucial in learning and memory, is frequently damaged during TBI. Since long-term potentiation (LTP) is the leading cellular model underlying learning and memory, this study was undertaken to examine how injury affects area CA1 LTP in mice using lateral fluid percussion injury (FPI). Brain slices derived from FPI animals demonstrated an inability to induce LTP in area CA1 7 days postinjury. However, area CA1 long-term depression could be induced in neurons 7 days postinjury, demonstrating that some forms of synaptic plasticity can still be elicited. Using a multi-disciplined approach, potential mechanisms underlying the inability to induce and maintain area CA1 LTP were investigated. This study demonstrates that injury leads to significantly smaller N-methyl-D-aspartate potentials and glutamate-induced excitatory currents, increased dendritic spine size, and decreased expression of alpha-calcium calmodulin kinase II. These findings may underlie the injury-induced lack of LTP and thus, contribute to cognitive impairments often associated with TBI. Furthermore, these results provide attractive sites for potential therapeutic intervention directed toward alleviating the devastating consequences of human TBI.

Quantification of ciliary beat frequency in sinonasal epithelial cells using differential interference contrast microscopy and high-speed digital video imaging

BACKGROUND

Mucociliary clearance is a critical upper airway host defense mechanism. Ciliated epithelium in the mammalian airway continually beat at a baseline frequency. Importantly, during times of stress such as exercise or infection, the cilia beat faster to increase clearance. Nasal epithelial ciliary beat frequency (CBF) has been analyzed previously in ex vivo specimens using a variety of methods including photodiode detectors and conventional video recording. Recent studies performed using lower airway ciliated mucosa have shown poor correlation between CBF quantified by photodiode/conventional video and those using high-speed digital video capture at temperatures close to physiological temperatures. Thus, to more rigorously interrogate sinonasal CBF at physiological conditions, we have incorporated a high-speed digital video camera to our CBF analysis system. This is the first report of sinonasal epithelial CBF analysis performed using high-speed video digital analysis.

METHODS

Ex vivo samples of sinonasal epithelium were placed in lactated Ringer's in a temperature-controlled microscope stage chamber. An edge of tissue containing beating cilia was observed at a magnification of 630x using differential interference contrast microscopy. The images were captured using a high-speed digital camera with a sampling rate of 250 frames per second. CBF was determined using computerized data analysis.

RESULTS

The mean nasal CBF was calculated from a minimum of five regions for each sample. Temperature curves were generated from tissue obtained from chronically infected subjects.

CONCLUSION

Analysis of high-speed digital video capture of sinonasal CBF observed under differential interference contrast microscopy is a powerful method to investigate environmental as well as host influences on mucociliary clearance within the upper airways.

Regional hippocampal alteration associated with cognitive deficit following experimental brain injury: a systems, network and cellular evaluation

Cognitive deficits persist in patients who survive traumatic brain injury (TBI). Lateral fluid percussion brain injury in the mouse, a model of human TBI, results in hippocampal-dependent cognitive impairment, similar to retrograde amnesia often associated with TBI. To identify potential substrates of the cognitive impairment, we evaluated regional neuronal loss, regional hippocampal excitability and inhibitory synaptic transmission. Design-based stereology demonstrated an approximate 40% loss of neurons through all subregions of the hippocampus following injury compared with sham. Input/output curves recorded in slices of injured brain demonstrated increased net synaptic efficacy in the dentate gyrus in concert with decreased net synaptic efficacy and excitatory postsynaptic potential-spike relationship in area CA1 compared with sham slices. Pharmacological agents modulating inhibitory transmission partially restored regional injury-induced alterations in net synaptic efficacy. Both evoked and spontaneous miniature inhibitory postsynaptic currents (mIPSCs) recorded in surviving dentate granule neurons were smaller and less frequent in injured brains than in uninjured brains. Conversely, both evoked and spontaneous mIPSCs recorded in surviving area CA1 pyramidal neurons were larger in injured brains than in uninjured brains. Together, these alterations suggest that regional hippocampal function is altered in the injured brain. This study demonstrates for the first time that brain injury selectively disrupts hippocampal function by causing uniform neuronal loss, inhibitory synaptic dysfunction, and regional, but opposing, shifts in circuit excitability. These changes may contribute to the cognitive impairments that result from brain injury.

Characterization of quaternary ammonium oligomers by paired-ion reversed-phase liquid chromatography-mass spectrometry

The separation of novel permanently charged oligomers was studied using paired-ion reversed-phase liquid chromatography. The polyionene studied is less than 5 kDa in size, but contains three oligomer series with different end-group chemistries. The complexity of this polyionene makes development of a single-dimension separation quite challenging. Separation under critical conditions was employed to fractionate the end-group conformations and then the chain length of the oligomers in each series was confirmed by LC-MS. The oligomers were then used to optimize a single-dimension HPLC separation. Precise modulation of the hydrophobicity of the ion-pair reagent and the stationary-phase chemistry yielded very high resolution one-dimensional separations.

Dentate granule cell GABA(A) receptors in epileptic hippocampus: enhanced synaptic efficacy and altered pharmacology

The dentate gyrus (DG) normally functions as a filter, preventing propagation of synchronized activity into the seizure-prone hippocampus. This filter or 'gatekeeper' attribute of the DG is compromised in various pathological states, including temporal lobe epilepsy (TLE). This study examines the role that altered inhibition may play in the deterioration of this crucial DG function. Using the pilocarpine animal model of TLE, we demonstrate that inhibitory synaptic function is altered in principal cells of the DG. Spontaneous miniature inhibitory postsynaptic currents (mIPSCs) recorded in dentate granule cells (DGCs) from epileptic animals were larger, more sensitive to blockade by zinc and less sensitive to augmentation by the benzodiazepine type site 1 modulator zolpidem. Furthermore, mIPSCs examined during a quiescent period following injury but preceding onset of epilepsy were significantly smaller than those present either in control or in TLE DGCs, and had already acquired sensitivity to blockade by zinc prior to the onset of spontaneous seizures. Rapid agonist application experiments demonstrated that prolonged (>35 ms) exposure to zinc is required to block GABAA receptors (GABAARs) in patches pulled from epileptic DGCs. Therefore, zinc must be tonically present to block DGC GABAARs and alter DG function. This would occur only during repetitive activation of mossy fibres. Thus, in the pilocarpine animal model of TLE, an early, de novo, expression of zinc-sensitive GABAARs is coupled with delayed, epilepsy-induced development of a zinc delivery system provided by aberrant sprouting of zinc-containing mossy fibre recurrent collaterals. The temporal and spatial juxtaposition of these pathophysiological alterations may compromise normal 'gatekeeper' function of the DG through dynamic zinc-induced failure of inhibition, predisposing the hippocampal circuit to generate seizures.

Indirect enzyme-linked immunosorbent assay for the detection of antibody against Rift Valley fever virus in domestic and wild ruminant sera

An indirect enzyme-linked immunosorbent assay (I-ELISA) for the detection of specific IgG immunoglobulins against Rift Valley fever virus (RVFV) was validated in-house. A total of 3055 sera from sheep (n = 1159), goats (n = 636), cattle (n = 203), African buffalo (n = 928), and other wild ruminants (n = 129), including eland, kudu, and black wildebeest, was used. Sera from domestic ruminants were collected in West (n = 10), South (n = 1654) and East Africa (n = 334), and sera from wild ruminants (n = 1064) were collected in South Africa. In addition, 136 sera from eight experimentally RVFV-infected sheep, taken during a period of 28 days post infection (dpi), were used to study the kinetics of RVFV antibody production. Field sera were tested by the serum neutralization (VN) test and experimental sera by VN and haemagglutination-inhibition (HI) test. Based on VN test results, negative sera were regarded as reference controls from RVFV-free, and positive sera were regarded as reference controls from RVFV-infected subpopulations of animals. ELISA data were expressed as the percentage positivity (PP) of an internal high positive control. The two-graph receiver operating characteristics approach was used for the selection and optimization of I-ELISA cut-offs including the misclassification costs term and Youden index (J). In addition, cut-off values were determined as the mean plus two-fold standard deviation of the result observed with the RVFV-free subpopulations. Established optimal cut-offs were different for each of the data sets analyzed, and ranged from 1.65 PP (buffalo) to 9.1 PP (goats). At the cut-off giving the highest estimate of combined measure of diagnostic accuracy (highest J value), the I-ELISA test parameters were determined as follows: (1) Diagnostic sensitivity (%): cattle--84.31, buffalo--94.44, sheep--98.91, goats--99.18. (2) Diagnostic specificity (%): cattle--99.34, buffalo--98.28, sheep--99.16, goats--99.23 and other game ruminants--99.26. In the group of RVFV-experimentally infected sheep, seroconversion In all individuals was detected by VN on 4-6 dpi, by HI on 5-7 dpi, and by I-ELISA on 6-7 dpi. All tests showed the same kinetic pattern of immunological response. Antibody levels were low for a very short period before increasing to high titres, after which it was easily detectable by all tests. Compared to traditional tests, the lower sensitivity of I-ELISA in the detection of the earliest stage of immunological response may be practically insignificant, particularily when this assay is used in population-based, disease-surveillance programmes. The high sensitivity and specificity of I-ELISA established in this study, especially for the statistically more representative subpopulations of animals tested, seem to support this prediction. Test parameters determined in this study should, however, be regarded as in-house diagnostic decision limits, for which further updating is recommended, particularly for specimens from other countries, and preferably by applying a standardized method for sampling of new subpopulations of animals to be targeted by the assay.

AMPA glutamate receptor-mediated calcium signaling is transiently enhanced during development of oligodendrocytes

Cells of the oligodendroglial lineage express Ca2+-permeable alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate-preferring glutamate receptors (AMPA-GluR) during development. Prolonged activation of their AMPA-GluR causes Ca2+ overload, resulting in excitotoxic death. Prior studies have shown that oligodendroglial progenitors and immature oligodendrocytes are susceptible to excitotoxicity, whereas mature oligodendrocytes are resistant. An unresolved issue has been why Ca2+-permeability of AMPA-GluR varies so markedly with oligodendroglial development, although the level of expression of edited GluR2, an AMPA-GluR subunit which blocks Ca2+ entry, is relatively constant. To address this question, we performed Ca2+ imaging, molecular and electrophysiological analyses using purified cultures of the rat oligodendroglial lineage. We demonstrate that transient up-regulation of expression of GluR3 and GluR4 subunits in oligodendroglial progenitors and immature oligodendrocytes results in the assembly by these cells, but not by oligodendroglial pre-progenitors or mature oligodendrocytes, of a population of AMPA-GluR which lack GluR2. This stage-specific up-regulation of edited GluR2-free, and hence Ca2+-permeable, AMPA-GluR explains the selective susceptibility to excitotoxicity of cells at these stages of oligodendroglial differentiation, and is likely to be important to these cells in the trans-synaptic Ca2+-signaling from glutamatergic neurons, which occurs in hippocampus

Specific proteolysis of the NR2 subunit at multiple sites by calpain

The NMDA subtype of glutamate receptor plays an important role in the molecular mechanisms of learning, memory and excitotoxicity. NMDA receptors are highly permeable to calcium, which can lead to the activation of the calcium-dependent protease, calpain. In the present study, the ability of calpain to modulate NMDA receptor function through direct proteolytic digestion of the individual NMDA receptor subunits was examined. HEK293t cells were cotransfected with the NR1a/2A, NR1a/2B or NR1a/2C receptor combinations. Cellular homogenates of these receptor combinations were prepared and digested by purified calpain I in vitro. All three NR2 subunits could be proteolyzed by calpain I while no actin or NR1a cleavage was observed. Based on immunoblot analysis, calpain cleavage of NR2A, NR2B and NR2C subunits was limited to their C-terminal region. In vitro calpain digestion of fusion protein constructs containing the C-terminal region of NR2A yielded two cleavage sites at amino acids 1279 and 1330. Although it has been suggested that calpain cleavage of the NMDA receptor may act as a negative feedback mechanism, the current findings demonstrated that calpain cleavage did not alter [(125)I]MK801 binding and that receptors truncated to the identified cleavage sites had peak intracellular calcium levels, (45)Ca uptake rates and basal electrophysiological properties similar to wild type.

Affective reactivity of language symptoms, startle responding, and inhibition in schizophrenia

The speech of some schizophrenia patients becomes markedly more disordered when negative affect is aroused. The authors tested associations between affective reactivity of speech and responsiveness and inhibition on an acoustic startle task in a sample of 27 outpatients. Patients whose language was reactive to negative affect showed significantly higher initial startle amplitudes than those whose language was not reactive. However, they also showed greater habituation to repeated startle stimuli over trials, even after differences in initial amplitudes were controlled statistically. These findings suggest that affective reactivity of speech is associated with higher initial startle responsiveness but also with greater habituation and, conversely, that patients who are relatively nonreactive to excitatory affective and sensory stimuli are also less reactive to inhibitory input.

Zinc-induced augmentation of excitatory synaptic currents and glutamate receptor responses in hippocampal CA3 neurons

Zinc is found throughout the CNS at synapses co-localized with glutamate in presynaptic terminals. In particular, dentate granule cells' (DGC) mossy fiber (MF) axons contain especially high concentrations of zinc co-localized with glutamate within vesicles. To study possible physiological roles of zinc, visualized slice-patch techniques were used to voltage-clamp rat CA3 pyramidal neurons, and miniature excitatory postsynaptic currents (mEPSCs) were isolated. Bath-applied zinc (200 microM) enhanced median mEPSC peak amplitudes to 153.0% of controls, without affecting mEPSC kinetics. To characterize this augmentation further, rapid agonist application was performed on perisomatic outside-out patches to coapply zinc with glutamate extremely rapidly for brief (1 ms) durations, thereby emulating release kinetics of these substances at excitatory synapses. When zinc was coapplied with glutamate, zinc augmented peak glutamate currents (mean +/- SE, 116.6 +/- 2.8% and 143.8 +/- 9.8% of controls at 50 and 200 microM zinc, respectively). This zinc-induced potentiation was concentration dependent, and pharmacological isolation of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor-mediated currents (AMPAR currents) gave results similar to those observed with glutamate application (mean, 115.0 +/- 5.4% and 132.5 +/- 9.1% of controls at 50 and 200 microM zinc, respectively). Inclusion of the AMPAR desensitization blocker cyclothiazide in the control solution, however, abolished zinc-induced augmentation of glutamate-evoked currents, suggesting that zinc may potentiate AMPAR currents by inhibiting AMPAR desensitization. Based on the results of the present study, we hypothesize that zinc is a powerful modulator of both excitatory synaptic transmission and glutamate-evoked currents at physiologically relevant concentrations. This modulatory role played by zinc may be a significant factor in enhancing excitatory neurotransmission and could significantly regulate function at the mossy fiber-CA3 synapse.

Affective reactivity of language symptoms, startle responding, and inhibition in schizophrenia

The speech of some schizophrenia patients becomes markedly more disordered when negative affect is aroused. The authors tested associations between affective reactivity of speech and responsiveness and inhibition on an acoustic startle task in a sample of 27 outpatients. Patients whose language was reactive to negative affect showed significantly higher initial startle amplitudes than those whose language was not reactive. However, they also showed greater habituation to repeated startle stimuli over trials, even after differences in initial amplitudes were controlled statistically. These findings suggest that affective reactivity of speech is associated with higher initial startle responsiveness but also with greater habituation and, conversely, that patients who are relatively nonreactive to excitatory affective and sensory stimuli are also less reactive to inhibitory input.

Protracted postnatal development of inhibitory synaptic transmission in rat hippocampal area CA1 neurons

In the CNS, inhibitory synaptic function undergoes profound transformation during early postnatal development. This is due to variations in the subunit composition of subsynaptic GABA(A) receptors (GABA(A)Rs) at differing developmental stages as well as other factors. These include changes in the driving force for chloride-mediated conductances as well as the quantity and/or cleft lifetime of released neurotransmitter. The present study was undertaken to investigate the nature and time course of developmental maturation of GABAergic synaptic function in hippocampal CA1 pyramidal neurons. In neonatal [postnatal day (P) 1-7] and immature (P8-14) CA1 neurons, miniature inhibitory postsynaptic currents (mIPSCs) were significantly larger, were less frequent, and had slower kinetics compared with mIPSCs recorded in more mature neurons. Adult mIPSC kinetics were achieved by the third postnatal week in CA1 neurons. However, despite this apparent maturation of mIPSC kinetics, significant differences in modulation of mIPSCs by allosteric agonists in adolescent (P15-21) neurons were still evident. Diazepam (1-300 nM) and zolpidem (200 nM) increased the amplitude of mIPSCs in adolescent but not adult neurons. Both drugs increased mIPSC decay times equally at both ages. These differential agonist effects on mIPSC amplitude suggest that in adolescent CA1 neurons, inhibitory synapses operate differently than adult synapses and function as if subsynaptic receptors are not fully occupied by quantal release of GABA. Rapid agonist application experiments on perisomatic patches pulled from adolescent neurons provided additional support for this hypothesis. In GABA(A)R currents recorded in these patches, benzodiazepine amplitude augmentation effects were evident only when nonsaturating GABA concentrations were applied. Furthermore nonstationary noise analysis of mIPSCs in P15-21 neurons revealed that zolpidem-induced mIPSC augmentation was not due to an increase in single-channel conductance of subsynaptic GABA(A)Rs but rather to an increase in the number of open channels responding to a single GABA quantum, further supporting the hypothesis that synaptic receptors may not be saturated during synaptic function in adolescent neurons. These data demonstrate that inhibitory synaptic transmission undergoes a markedly protracted postnatal maturation in rat CA1 pyramidal neurons. In the first two postnatal weeks, mIPSCs are large in amplitude, are slow, and occur infrequently. By the third postnatal week, mIPSCs have matured kinetically but retain distinct responses to modulatory drugs, possibly reflecting continued immaturity in synaptic structure and function persisting through adolescence.

Equating health status measures with item response theory: illustrations with functional status items

BACKGROUND

More than 75 instruments have been developed to measure functional status. These measures differ in number of items, type of rating scale, and item difficulty. Such variations render it impossible to compare data across different measures. One way to overcome such test dependency is test equating, which relates scores from different measures to a common metric.

OBJECTIVE

We developed a bank of physical functioning items and equated them using item response theory.

DESIGN

We used a common-item equating design and a self-administered survey of functional status.

SUBJECTS

Individuals > or = 65 years of age who had > or = 1 ambulatory visit across a 3-month sampling frame to a Veterans Administration Medical Center or its affiliated university medical center.

RESULTS

The dressing items were the most discriminating, followed by bathing, toileting, mobility, cooking/eating, and household and community activities. The 5 most discriminating items were to put underclothes on, manage clothes after toileting, move between rooms, take pants/slacks off, and get into bed. Most of the items were located on the easier end of the ability continuum. Only 6 would classify as being very difficult.

CONCLUSIONS

We used item response theory to equate and calibrate a large number of activities of daily living on the same scale; by doing so, we were able to better understand the structure and order of domain-specific items to each other, as well as the interrelations among items across the ability continuum.

Polymer solutions as a pseudostationary phase for capillary electrochromatographic separation of DNA diastereomers

The solutions of linear polymers traditionally used for DNA separation have been employed for the capillary electrophoresis (CE) of diastereomers of chemically modified DNA. The selectivity of diastereomeric separation of the phosphorothioate (PS) and 2'-O-methylated (2-OMe) PS oligonucleotides depends on the nature of the polymer additive in the CE background electrolyte. The selectivity of separation for different polymers increases in the line: linear polyacrylamide < polyethylene glycol < polyvinyl pyrrolidone. The separation of oligomer diastereomers was shown to be primarily based on the hydrophobic interaction with the polymer network that acts as a pseudostationary phase. While lowering the temperature resulted in improved separation, the addition of organic modifiers such as formamide, methanol or acetonitrile counteracts the solute adsorption on the polymer network, and decreases the selectivity of DNA diastereoseparation. The effect of molecular mass and concentration of the polymer on the separation selectivity was investigated.

Review: history of the amyloid fibril

Rudolph Virchow, in 1854, introduced and popularized the term amyloid to denote a macroscopic tissue abnormality that exhibited a positive iodine staining reaction. Subsequent light microscopic studies with polarizing optics demonstrated the inherent birefringence of amyloid deposits, a property that increased intensely after staining with Congo red dye. In 1959, electron microscopic examination of ultrathin sections of amyloidotic tissues revealed the presence of fibrils, indeterminate in length and, invariably, 80 to 100 A in width. Using the criteria of Congophilia and fibrillar morphology, 20 or more biochemically distinct forms of amyloid have been identified throughout the animal kingdom; each is specifically associated with a unique clinical syndrome. Fibrils, also 80 to 100 A in width, have been isolated from tissue homogenates using differential sedimentation or solubility. X-ray diffraction analysis revealed the fibrils to be ordered in the beta pleated sheet conformation, with the direction of the polypeptide backbone perpendicular to the fibril axis (cross beta structure). Because of the similar dimensions and tinctorial properties of the fibrils extracted from amyloid-laden tissues and amyloid fibrils in tissue sections, they have been assumed to be identical. However, the spatial relationship of proteoglycans and amyloid P component (AP), common to all forms of amyloid, to the putative protein only fibrils in tissues, has been unclear. Recently, it has been suggested that, in situ, amyloid fibrils are composed of proteoglycans and AP as well as amyloid proteins and thus resemble connective tissue microfibrils. Chemical and physical definition of the fibrils in tissues will be needed to relate the in vitro properties of amyloid protein fibrils to the pathogenesis of amyloid fibril formation in vivo.

Long-lasting increase in cellular excitability associated with the priming of LTP induction in rat hippocampus

The mechanisms underlying the facilitation (priming) of long-term potentiation (LTP) by prior activation of metabotropic glutamate receptors (mGluRs) were investigated in area CA1 of rat hippocampal slices. In particular, we focused on whether a long-lasting increase in postsynaptic excitability could account for the facilitated LTP. Administration of the mGluR agonist 1S, 3R-aminocyclopentanedicarboxylic acid (ACPD) produced rapid decreases in the amplitude of both the slow spike afterhyperpolarization (AHP(slow)) and spike frequency adaptation recorded intracellularly from CA1 pyramidal cells. These changes persisted after drug washout, showing only a slow decay over 20 min. ACPD also caused a leftward shift of the field EPSP-population spike relation and an overall increase in population spike amplitude, but this effect was not as persistent as the intracellularly measured alterations in cell excitability. ACPD-treated cells showed increased spike discharges during LTP-inducing tetanic stimulation, and the amplitude of the AHP(slow) was negatively correlated with the degree of initial LTP induction. The beta-adrenergic agonist isoproterenol also caused excitability changes as recorded intracellularly, whereas in extracellular experiments it weakly primed the induction but not the persistence of LTP. ACPD primed both LTP measures. Isoproterenol administration during the tetanus occluded the priming effect of ACPD on initial LTP induction but not its effect on LTP persistence. We conclude that the persistent excitability changes elicited by ACPD contributes to the priming of LTP induction but that other ACPD-triggered mechanisms must account for the facilitated persistence of LTP in the priming paradigm.

A double dissociation within the hippocampus of dopamine D1/D5 receptor and beta-adrenergic receptor contributions to the persistence of long-term potentiation

We compared the effects of the D1/D5 receptor antagonist SCH-23390 with the beta-adrenergic receptor antagonist propranolol on the persistence of long-term potentiation in the CA1 and dentate gyrus subregions of the hippocampus. In slices, SCH-23390 but not propranolol reduced the persistence of long-term potentiation in area CA1 without affecting its induction. The drugs exerted reverse effects in the dentate gyrus, although in this case the induction of long-term potentiation was also affected by propranolol. The lack of effect of SCH-23390 on the induction and maintenance of long-term potentiation in the dentate gyrus was confirmed in awake animals. The drug also had little or no effect on the expression of inducible transcription factors. In area CA1 of awake animals, SCH-23390 blocked persistence of long-term potentiation beyond 3 h, confirming the results in slices. To rule out a differential release of catecholamines induced by our stimulation protocols between brain areas, we compared the effects of the D1/D5 agonist SKF-38393 with the beta-adrenergic agonist isoproterenol on the persistence of a weakly induced, decremental long-term potentiation in CA1 slices. SKF-38393 but not isoproterenol promoted greater persistence of long-term potentiation over a 2-h period. In contrast, isoproterenol but not SKF-38392 facilitated the induction of long-term potentiation. These data demonstrate that there is a double dissociation of the catecholamine modulation of long-term potentiation between CA1 and the dentate gyrus, suggesting that long-term potentiation in these brain areas may be differentially consolidated according to the animal's behavioural state.

Ancient mantle in a modern arc: osmium isotopes in izu-bonin-mariana forearc peridotites

Mantle peridotites drilled from the Izu-Bonin-Mariana forearc have unradiogenic 187Os/188Os ratios (0.1193 to 0.1273), which give Proterozoic model ages of 820 to 1230 million years ago. If these peridotites are residues from magmatism during the initiation of subduction 40 to 48 million years ago, then the mantle that melted was much more depleted in incompatible elements than the source of mid-ocean ridge basalts (MORB). This result indicates that osmium isotopes record information about ancient melting events in the convecting upper mantle not recorded by incompatible lithophile isotope tracers. Subduction zones may be a graveyard for ancient depleted mantle material, and portions of the convecting upper mantle may be less radiogenic in osmium isotopes than previously recognized.

Study of phosphorothioate-modified oligonucleotide resistance to 3'-exonuclease using capillary electrophoresis

The effect of phosphorothioate (PS) internucleotide linkages on the stability of phosphodiester oligodeoxyribonucleotides (ODNs) was investigated using 25-mer ODNs containing single or multiple PS backbone modifications. The in vitro stability of the oligomers was measured both in 3'-exonuclease solution and in plasma. For the separation of ODNs, capillary electrophoresis with a replaceable polymer separation matrix was used. As expected, DNA fragments with PS linkages at the 3'-end were found to be more resistant to 3'-exonuclease hydrolysis. Also increasing exonuclease resistance was the non-specific adsorption of phosphorothioate ODNs to enzyme.

Postmenopausal estrogen replacement therapy and the risk of developing systemic lupus erythematosus or discoid lupus

OBJECTIVE

There is evidence that estrogens play a role in the etiology of systemic lupus erythematosus (SLE), but this has not yet been shown for discoid lupus. We examined the association of postmenopausal estrogen use with the development of SLE and discoid lupus.

METHODS

We did a case-control evaluation, using the UK based General Practice Research Database. We analyzed 41 cases with SLE, 34 cases with discoid lupus, and 295 age, sex and practice matched controls, and estimated relative risk estimates (odds ratios) in relation to estrogen exposure duration as well as total cumulative dose and estrogen type (alone or combined with progestogens).

RESULTS

While short term estrogen exposure was not associated with increased risk, the risk of developing SLE (adjusted OR 2.8; 95% CI 0.9-9.0) or discoid lupus (adjusted OR 2.8; 95% CI 1.0-8.3) was significantly increased among current users who were exposed for 2 or more years. The adjusted RR estimate comparing longer term estrogen users and nonusers for all cases (SLE and discoid lupus combined) was 2.8 (95% CI 1.3-5.8; p < 0.01). A difference was found between longterm users of estrogens alone (OR 5.3; 95% CI 1.5-18.6) and those who used estrogens combined with progestogens (OR 2.0; 95% CI 0.8-5.0), compared to nonusers.

CONCLUSION

Our findings suggest that longer term use of postmenopausal estrogens plays a role in the etiology of both SLE and discoid lupus. There is a suggestion that progestogens may reduce the effect of estrogens on these autoimmune disorders.

Priming of long-term potentiation induced by activation of metabotropic glutamate receptors coupled to phospholipase C

Activation of metabotropic glutamate receptors (mGluRs) with 1-aminocyclopentane-1S,3R-dicarboxylic acid 20 min prior to tetanus facilitates, or "primes," subsequent induction of long-term potentiation (LTP; Cohen and Abraham, J Neurophysiol 1996;76:953-962). In the present study, we investigated the receptor specificity and associated second messenger pathways involved in the mGluR priming effect by using field potentials recorded from area CA1 of rat hippocampal slices. In controls, mild theta-burst or high-frequency (100 Hz) stimulation induced 16% and 21% LTP, respectively. A 10-min application of the group I mGluR agonist 3,5-dihydroxyphenylglycine (DHPG) caused a transient depression of synaptic responses but a significant enhancement of subsequent LTP for both tetanus protocols (45% and 41% LTP, respectively). Maximal LTP, induced by stronger tetanization protocols, was not enhanced by DHPG, nor was mild LTP facilitated by post-tetanic application of DHPG. Priming with agonists selective for group II or III mGluRs had no effect on LTP. The mGluR antagonists L-2-amino-3-phosphonopropionic acid and 1-aminoindan-1,5-dicarboxylic acid inhibited the LTP facilitatory effect of DHPG but not the transient response depression, whereas alpha-methyl-4-carboxyphenylglycine produced the opposite effects. Priming with N-methyl-D-aspartate or alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid did not facilitate LTP induction. Prior activation of muscarinic acetylcholine receptors produced at best a weak priming effect. Inhibition of phospholipase C by U-73122 completely abolished the priming of LTP by DHPG. We conclude that mGluR priming of LTP results from biochemical cascades triggered by activation of phospholipase C coupled to group I mGluRs.

Impact of 3'-exonuclease stereoselectivity on the kinetics of phosphorothioate oligonucleotide metabolism

For the enzymatic digestion of a 25-mer phosphorothioate (PS) oligonucleotide, the reaction kinetics was previously determined to be the sum of two parallel processes: a fast and a very slow phase of digestion suggesting a two-exponential model. A characteristic metabolite profile was observed both in vitro and in vivo. This behavior is shown to be the result of the stereoselective cleavage of chiral R-configuration and S-configuration PS internucleotide linkages by 3'-exonucleases. The stereoselective nature of 3'-exonuclease action was analyzed by reverse-phase HPLC. The separation of eight diastereomers of the tetramer TTCT (5'-3') was used to follow the stereoselective course of exonuclease hydrolysis of PS internucleotide linkages. Degradation of the 25-mer parent compound having a 3' S-terminal internucleotide linkage was calculated to be more than 300 times slower than an analog with a 3'-terminal R-configuration. These results support an approach for protecting antisense oligonucleotides based on the chirality of only the 3'-end internucleotide linkage.

Ca2+-induced Ca2+ release mediates a slow post-spike hyperpolarization in rabbit vagal afferent neurons

The relation between Ca2+-induced Ca2+ release (CICR) elicited by action potentials (APs) and a Ca2+-dependent slow post-spike hyperpolarization (AHPslow) in acutely dissociated adult rabbit nodose neurons was studied using microfluorimetric calcium measurements in conjunction with standard intracellular current- and voltage-clamp recording techniques. The magnitude of the AP-induced transient increase in [Ca2+]i (DeltaCat) was used to monitor CICR. There was a close correlation between the magnitude of the DeltaCat and the AHPslow current over the range of 1-16 APs (r = 0.985). Functional CICR blockers, ryanodine (10 muM), thapsigargin (100 nM), 2,5-di(t-butyl)hydroquinone (10 muM) or cyclopiazonic acid (10 muM), selectively reduced the peak amplitude of the AHPslow >/=91%. In five neurons, simultaneous recordings of the DeltaCat and the AHPslow revealed that both responses were blocked in parallel. These findings indicate that CICR is necessary for the generation of the AHPslow in rabbit nodose neurons. The DeltaCat rises and decays significantly faster than the AHPslow. This temporal disparity suggests that activation of the AHPslow by Ca2+ may require additional signal transduction steps.

Method for phosphorothioate antisense DNA sequencing by capillary electrophoresis with UV detection

The progress of antisense DNA therapy demands development of reliable and convenient methods for sequencing short single-stranded oligonucleotides. A method of phosphorothioate antisense DNA sequencing analysis using UV detection coupled to capillary electrophoresis (CE) has been developed based on a modified chain termination sequencing method. The proposed method reduces the sequencing cost since it uses affordable CE-UV instrumentation and requires no labeling with minimal sample processing before analysis. Cycle sequencing with ThermoSequenase generates quantities of sequencing products that are readily detectable by UV. Discrimination of undesired components from sequencing products in the reaction mixture, previously accomplished by fluorescent or radioactive labeling, is now achieved by bringing concentrations of undesired components below the UV detection range which yields a 'clean', well defined sequence. UV detection coupled with CE offers additional conveniences for sequencing since it can be accomplished with commercially available CE-UV equipment and is readily amenable to automation.

Kinetics of phosphorothioate oligonucleotide metabolism in biological fluids

The in vitro stability and metabolism of GEM[91, a 25mer phosphorothioate antisense oligonucleotide complementary to the gag mRNA region of HIV-1, was investigated using capillary electrophoresis (CE). The in vitro degradation of the parent compound at 37 degrees C was followed over the course of 120 h in human plasma. A CE method using laser-induced fluorescence detection was able to detect 5'-end intact metabolites including the parent compound extracted from biological fluids. Because the primary metabolic pathway is believed to be via 3'-exonuclease activity, the results of this study were compared with the stability of the compound in a solution containing 3'-exonuclease. The numerical solution of sequential first-order reactions was used to obtain kinetic parameters. Exonuclease digestion of the parent compound, as measured using an automated CE-UV instrument, yielded striking similarities between the two in vitro systems as well as between in vitro and in vivo systems.

Lipid peroxidation, antioxidant status and troponin-T following cardiopulmonary bypass. A comparison between intermittent crossclamp with fibrillation and crystalloid cardioplegia

OBJECTIVE

Intermittent crossclamp with fibrillation affords equivalent myocardial protection to cold crystalloid cardioplegia in patients undergoing elective coronary artery surgery. This study is a direct comparison between the two techniques with regards to free radical activity.

METHODS

The study design was part of a prospective randomised trial. We studied 24 consecutive patients with ejection fraction of 30% or greater undergoing elective coronary artery surgery. Patients were randomised into two groups. In group 1 (n = 13) the myocardium was protected by intermittent aortic cross clamping with fibrillation and group 2 (n = 11) by antegrade cold crystalloid cardioplegia. The determinants of free radical activity were serial peripheral venous samples for lipid peroxidation and plasma antioxidant status (before and at 1, 6, 24 and 72 h after the end of cardiopulmonary bypass). The determinant of the efficacy of myocardial protection was serial peripheral venous samples of cardiac troponin-T taken at the same time intervals.

RESULTS

The groups were similar with respect to age, sex distribution, preoperative ventricular function, left main stem disease, number of grafts and bypass times. Lipid peroxidation measurements at the 1 h time point were higher than preoperative values (7.24 +/- 1.19 vs. 4.48 +/- 0.69 and 9.36 +/- 1.46 vs. 4.98 +/- 1.02 (mean +/- S.E) in groups 1 and 2, respectively (units in mmol/l) thereafter values decreased to near preoperative values by 72 h. There was no significant difference between the groups (P = 0.42). Total plasma antioxidant status values at the 1 h time point were lower than the preoperative values for all patients (1.33 +/- 0.07 vs. 1.63 +/- 0.06 and 1.42 +/- 0.07 vs. 1.63 +/- 0.05 (mean +/- standard error) in groups 1 and 2, respectively, (units in mmol/l) and thereafter at the subsequent time points increased but never attained their preoperative value. There was no statistically significant difference between the two groups (P = 0.59). Troponin-T measurements showed no significant difference between the two groups at all time points (P = 0.2217).

CONCLUSIONS

This study shows that lipid peroxidation is initially elevated and the defence mechanisms against oxygen free radicals-antioxidant status'-are depressed following cardiopulmonary bypass. The degree of oxygen free radical activity produced during ischaemia and reperfusion was similar in both types of myocardial protection employed in this study.

Minimally invasive coronary revascularization through parasternal incisions without cardiopulmonary bypass

BACKGROUND

We report the results of minimally invasive coronary revascularization without cardiopulmonary bypass through miniparasternal incisions.

METHODS

This procedure was performed in 40 patients with disease in the left anterior descending, first diagonal, and right coronary arteries. After a 5- to 7-cm left vertical parasternal incision and removal of two costal cartilages, the left internal mammary artery was harvested up to the 2nd rib. The left anterior descending artery was occluded by means of two polydioxanone monofilament sutures. The anastomosis was performed with one 7-0 Prolene suture while the heart was beating. In 4 cases the left internal mammary artery was used as a sequential graft to the left anterior descending artery and the first diagonal artery. In 14 cases the right coronary artery was grafted with the right internal mammary artery through a right parasternal incision. Postoperatively, 95% of the patients underwent angiographic assessment of the anastomoses.

RESULTS

We performed 52 anastomoses (34 to the left anterior descending artery, 4 to the first diagonal artery, and 14 to the right coronary artery). The mortality was 0% and the morbidity included postoperative bleeding (5%), acute renal failure (2.5%), atrial fibrillation (2.5%), and wound infection (5%). No patient had ventricular arrhythmias or circulatory problems during or after the operation. Two patients (5%) with right internal mammary artery-to-right coronary artery grafting had graft failure that required a redo operation.

CONCLUSIONS

Small vertical parasternal incisions may be an alternative approach for single and multiple coronary revascularization, with a low incidence of intraoperative cardiac complications. The application of this approach to the right coronary artery, however, carries additional technical difficulties, and careful patient selection may be required to achieve optimal results.

National survey of endodontists and selected patient samples: infectious diseases and attitudes toward infection control

A survey was conducted of 591 patients from endodontic practices located in six large municipalities in the United States. A comparison was made between the self-reported incidence of transmissible diseases from patients medical histories to national statistics for the incidence of hepatitis B, herpes, tuberculosis, and HIV/AIDS. A national survey of 422 endodontists was also conducted. This survey was used to determine the beliefs and attitudes of practicing endodontists toward infection control techniques and infectious diseases. Compared with previous surveys, a trend toward increasing use of the hepatitis B vaccine, gloves, and greater acceptance of medically compromised patients was found.

Ca(2+)-induced Ca2+ release mediates Ca2+ transients evoked by single action potentials in rabbit vagal afferent neurones

1. Standard intracellular recording techniques with 'sharp' micropipettes were used to evoke action potentials (APs) in acutely dissociated adult nodose neurones. 2. APs induced a transient increase in [Ca2+]i (a calcium transient), recorded with fura-2, that was dependent upon [Ca2+]o and the number of APs. Over the range of one to sixty-five APs, the relation between the amplitude of the calcium transient and the number of APs was well fitted by a rectangular hyperbola (chi 2 = 3.53, r = 0.968). From one to four APs, the calcium transient-AP relation can be described by a line with a slope of 9.6 nM AP-1 (r = 0.999). 3. Charge movement corresponding to Ca2+ influx evoked by a single AP was 39 +/- 2.8 pC (mean +/- S.E.M.) and did not change significantly during trains of one to thirty-one APs (P < 0.05). 4. Caffeine (10 mM), a known agonist of the ryanodine receptor, produced an increase in [Ca2+]i. The caffeine-induced rise in [Ca2+]i was attenuated (by > 90%) by lowering [Ca2+]o, and by ryanodine (10 microM), 2,5-di(t-butyl)hydroquinone (DBHQ, 10 microM), or thapsigargin (100 nM). 5. Neurones incubated with ryanodine, DBHQ or thapsigargin required at least eight APs to evoke a detectable calcium transient. These reagents did not significantly affect Ca2+ influx (P < 0.05). In the presence of these inhibitors, the calcium transient-AP relation exhibited slopes of 1.2, 1.1 and 1.9 nM AP-1 for ryanodine, DBHQ and thapsigargin, respectively. When compared with the slope of 9.6 nM AP-1 in non-treated neurones, it appears that Ca2+ influx produced by a single AP is amplified by ca 5- to 10-fold.

A nonradioisotope approach to study the in vivo metabolism of phosphorothioate oligonucleotides

A 25-mer phosphorothioate oligodeoxynucleotide (GEM 91) complementary to the gag gene mRNA of HIV-1 virus was administered intravenously (i.v.) at a dose of 10 mg/kg/day for 8 weeks or 25 mg/kg single dose subcutaneously (SC) to adult Rhesus monkeys. No radioactive markers were used. A capillary gel electrophoresis (CGE) method with UV detection was used to determine the concentration of GEM 91 in plasma and the metabolite profile. The metabolite profile was virtually the same following a single dose of either 10 mg/kg i.v. or 25 mg/kg SC. A different metabolite profile was observed after 4 or 8 weeks of multiple i.v. doses of 10 mg/kg/day. The extract was subjected to matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOFMS) for positive identification. Mass spectrometry confirmed the major metabolic pathway in vivo to be via 3'-end exonuclease activity. The extract was then subjected to a hybridization-assisted ligation reaction in which only 5'-end intact metabolites were labeled. Analysis by CGE with laser-induced fluorescence (LIF) detection allowed each of these metabolites to be quantified with a limit of detection of 1 ppb (ng/ml). MALDI-TOFMS identified components digested from both ends of the DNA. This study demonstrates that the combination of quantitative CGE-LIF and MALDI-TOFMS yields a powerful and unique approach to study the metabolism of phosphorothioate oligonucleotides.

Improvement in the polyneuropathy associated with familial amyloid polyneuropathy after liver transplantation

OBJECTIVE

To study, following liver transplantation, the neurologic progression or regression of the polyneuropathy in a cohort of patients with familial amyloidotic polyneuropathy (FAP).

BACKGROUND

FAP is characterized by the relentless progression of neurologic and cardiac impairment, leading to death within 7 to 15 years after disease onset. No effective treatment to slow or halt the progression of this disease has been found to date.

DESIGN/METHODS

Over the past 3 years, our FAP patients were offered liver transplantation as treatment. We report on nine patients who were followed longitudinally with serial neurologic examinations since transplantation.

RESULTS

Clinically, all patients evaluated for neurologic progression reported significant improvement in general well being. No patient showed any progression in neurologic disease since receiving a liver transplant. Improvements are documented in symptomatic, autonomic, and sensorimotor neurologic disease in all patients.

CONCLUSION

Our experience suggests that liver transplantation may offer hope for arrest of progression and neurologic improvement in patients with FAP.