H-atom relay reactions in real space.

Hydrogen bonds are the path through which protons and hydrogen atoms can be transferred between molecules. The relay mechanism, in which H-atom transfer occurs in a sequential fashion along hydrogen bonds, plays an essential role in many functional compounds. Here we use the scanning tunnelling microscope to construct and operate a test-bed for real-space observation of H-atom relay reactions at a single-molecule level. We demonstrate that the transfer of H-atoms along hydrogen-bonded chains assembled on a Cu(110) surface is controllable and reversible, and is triggered by excitation of molecular vibrations induced by inelastic tunnelling electrons. The experimental findings are rationalized by ab initio calculations for adsorption geometry, active vibrational modes and reaction pathway, to reach a detailed microscopic picture of the elementary processes.

Water clusters on Cu(110): chain versus cyclic structures.

Water clusters are assembled and imaged on Cu(110) by using a scanning tunneling microscope. Water molecules are arranged along the Cu row to form "ferroelectric" zigzag chains of trimer to hexamer. The trimer prefers the chain form to a cyclic one in spite of the reduced number of hydrogen bonds, highlighting the crucial role of the water-substrate interaction in the clustering of adsorbed water molecules. On the other hand, the cyclic form with maximal hydrogen bonds becomes more favorable for the tetramer, indicating the crossover from chain to cyclic configurations as the constituent number increases.

Effects of STN stimulation on the initiation and inhibition of saccade in Parkinson disease.

OBJECTIVES: The basal ganglia (BG) play an important role in controlling saccades. Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is widely used as a treatment of Parkinson disease (PD) by altering the function of the BG. Nevertheless, the effects of STN DBS on saccade performance are not fully clarified in a systematic manner. In this study, we examined the effects of bilateral STN DBS on both the initiation and inhibition of saccades in PD. METHODS: Thirty-two patients with PD performed 4 oculomotor tasks. Two tasks (visually guided saccades and gap saccades) were reflexive and 2 (memory-guided saccades [MGS] and antisaccades) were volitional. While taking their regular doses of antiparkinsonian drugs, patients performed these tasks under 2 conditions: during DBS (DBS-on condition) and without DBS (DBS-off condition). Fifty-one age-matched subjects served as controls. RESULTS: In the DBS-on condition, parameters of saccade initiation were improved in all tasks, with shorter latencies and increased amplitudes, except for MGS latency. STN DBS improved the ability to suppress unwanted saccades to the cue stimulus in the MGS task. However, it did not suppress prosaccades during the antisaccade task. CONCLUSIONS: These results suggest that deep brain stimulation (DBS) of the subthalamic nucleus (STN) affects the neural pathway common to both reflexive and volitional saccades, possibly by acting on the STN-substantia nigra pars reticulata-superior colliculi pathway. STN DBS may set the functional level of the superior colliculi appropriate for both saccade initiation and inhibition through this pathway. These findings provide novel insights into the pathophysiology of Parkinson disease and may yield better treatment strategies.

Microelectrode findings and topographic reorganisation of kinaesthetic cells after gamma knife thalamotomy.

A 64-year-old woman with Parkinson is disease had a severe resting tremor that was not completely relieved by right-sided gamma knife thalamotomy (GKT). We performed bilateral staged thalamic deep brain stimulation (DBS) and compared the right and left ventral intermediate nucleus (Vim) of the thalamus including the frequency of single units recorded with microelectrodes, and also the somatotopical distribution of kinaesthetic cells (Ki). The average frequency of units for the presumed left Vim exceeded that of the right (22.6 +/- 19.2 Hz vs. 14.3 +/- 8.8 Hz). Regarding the somatotopic distribution of Ki, the receptive field for the leg, which is usually situated in the dorsolateral Vim, was more widely scattered in the right Vim than the non-lesioned left side. Our findings raise the possibility that the specific properties of the neurons changed due to partial coagulation by GKT within both the coagulated and the surrounding thalamic lesions.

Direct observation of hydrogen-bond exchange within a single water dimer.

The dynamics of water dimers was investigated at the single-molecule level by using a scanning tunneling microscope. The two molecules in a water dimer, bound on a Cu(110) surface at 6 K, were observed to exchange their roles as hydrogen-bond donor and acceptor via hydrogen-bond rearrangement. The interchange rate is approximately 60 times higher for (H2O)2 than for (D2O)2, suggesting that quantum tunneling is involved in the process. The interchange rate is enhanced upon excitation of the intermolecular mode that correlates with the reaction coordinate.

Developing Iraq's mental health policy.

As Iraq faces the challenge of securing a sustainable resolution to the current violence, the burden of mental illness is likely to increase dramatically. The impact of Saddam Hussein's dictatorship, the Iran-Iraq war, U.S.-led economic sanctions, the Persian Gulf wars, and the U.S. invasion and subsequent violent insurgency have devastated Iraq's governmental and social infrastructure. Health care delivery across sectors has suffered greatly. During the reconstruction phase, the United States and coalition forces allocated resources to restructure Iraq's health care system. Many multinational organizations, governments, and policy makers had the political will as well as the financial and human resources to greatly influence Iraq's mental health program. However, the lack of an existing mental health plan stifled these efforts. Applying Kingdon's model for policy development, which includes political analysis, problem defining, and proposal drafting, the authors describe the development of Iraq's current mental health policy.

Oxygen at high pressures: a theoretical approach to monoatomic phases.

We have studied the ζ-phase of solid oxygen using the generalized gradient approximation in the density functional approach. Calculations of total energies and pressures have been carried out for the prototype of diatomic ζ-phase and other hypothetical monoatomic crystal structures. The diatomic phase was found to be stable over a wide range of pressure (100-2000 GPa). The stacking of molecular layers is discussed in comparison with the available experimental data.

Relationship between lesion location and the outcome of pallidotomy for Parkinson's disease.

The relationships between lesion location and clinical outcome following posteroventral pallidotomy for Parkinson's disease were studied. Forty-four patients were operated forty-six times and studied with neurological and psychological examinations before and after pallidotomy. Lesion location was confirmed using films with a coagulation electrode which were X-rayed during the operation. Changes of intelligence were observed in the patients with anteromedial lesions. Wearing-off phenomenon in four patients and dopa-induced dyskinesia in three patients were not improved following pallidotomy in twenty patients with severe wearing-off and dyskinesia. Lesions in the patients with no improvement of wearing off were located more lateral and those in the patients with sustained severe dyskinesia were located more dorsal in the internal part of the globus pallidus. It may be concluded that clinical outcome is related to lesion location.

[Anesthetic management in a patient with Simpson-Golabi-Behmel syndrome].

We report the anesthetic management of a 4-yr-old boy with Simpson-Golabi-Behmel syndrome. This syndrome is an X-linked condition characterized by pre- and postnatal overgrowth with visceral and skeletal anomalies. Affected males have a distinctive facial appearance with wide nasal bridge, anteverted nostrils, wide-open mouth, enlarged tongue, and large protruding maxilla and jaw. Although it had been speculated preoperatively that airway management would be complicated by the macroglossia, there was no difficulty in endotracheal intubation in the present patient. Preparations for difficult airway management should be made by the anesthesiologist before induction of anesthesia.

Organization of inputs from cingulate motor areas to basal ganglia in macaque monkey.

The cingulate motor areas reside within regions lining the cingulate sulcus and are divided into rostral and caudal parts. Recent studies suggest that the rostral and caudal cingulate motor areas participate in distinct aspects of motor function: the former plays a role in higher-order cognitive control of movements, whereas the latter is more directly involved in their execution. Here, we investigated the organization of cingulate motor areas inputs to the basal ganglia in the macaque monkey. Identified forelimb representations of the rostral and caudal cingulate motor areas were injected with different anterograde tracers and the distribution patterns of labelled terminals were analysed in the striatum and the subthalamic nucleus. Corticostriatal inputs from the rostral and caudal cingulate motor areas were located within the rostral striatum, with the highest density in the striatal cell bridges and the ventrolateral portions of the putamen, respectively. There was no substantial overlap between these input zones. Similarly, a certain segregation of input zones from the rostral and caudal cingulate motor areas occurred along the mediolateral axis of the subthalamic nucleus. It has also been revealed that corticostriatal and corticosubthalamic input zones from the rostral cingulate motor area considerably overlapped those from the presupplementary motor area, while the input zones from the caudal cingulate motor area displayed a large overlap with those from the primary motor cortex. The present results indicate that a parallel design underlies motor information processing in the cortico-basal ganglia loop derived from the rostral and caudal cingulate motor areas.

Excitatory cortical inputs to pallidal neurons via the subthalamic nucleus in the monkey.

How the motor-related cortical areas modulate the activity of the output nuclei of the basal ganglia is an important issue for understanding the mechanisms of motor control by the basal ganglia. In the present study, by using awake monkeys, the polysynaptic effects of electrical stimulation in the forelimb regions of the primary motor and primary somatosensory cortices on the activity of globus pallidus (GP) neurons, especially mediated by the subthalamic nucleus (STN), have been characterized. Cortical stimulation induced an early, short-latency excitation followed by an inhibition and a late excitation in neurons of both the external and internal segments of the GP. It also induced an early, short-latency excitation followed by a late excitation and an inhibition in STN neurons. The early excitation in STN neurons preceded that in GP neurons. Blockade of STN neuronal activity by muscimol (GABA(A) receptor agonist) injection resulted in abolishment of both the early and late excitations evoked in GP neurons by cortical stimulation. At the same time, the spontaneous discharge rate of GP neurons decreased, pauses between the groups of spikes of GP neurons became prominent, and the firing pattern became regular. Injection of (+/-)-3-(2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP) [N-methyl-D-aspartate (NMDA) receptor antagonist], but not 1,2,3, 4-tetrahydro-6-nitro-2,3-dioxo-benzo[f]quinoxaline-7-sulfonamide disodium [NBQX (non-NMDA receptor antagonist)], into the STN attenuated the early and late excitations in GP neurons, suggesting that cortico-subthalamic transmission is mediated mainly by NMDA receptors. Interference with the pallido-subthalamic transmission by bicuculline (GABA(A) receptor antagonist) injection into the STN made the inhibition distinct without affecting the early excitation. The present results indicate that the cortico-subthalamo-pallidal pathway conveys powerful excitatory effects from the motor-related cortical areas to the GP with shorter conduction time than the effects conveyed through the striatum.

A cortical motor region that represents the cutaneous back muscles in the macaque monkey.

A cortical motor region that represented the cutaneous muscles on the back was identified on the medial wall of the frontal lobe in the macaque monkey. In this region, neurons responded to somatosensory stimuli such as light touch or squeezing of the back skin, and intracortical microstimulation elicited contraction of the back skin. Such a region was located primarily on the dorsal bank of the cingulate sulcus, corresponding to the dorsal cingulate motor area.

A modified microsyringe for extracellular recording of neuronal activity.

We describe a modified Hamilton microsyringe that allows extracellular recording of neuronal activity and subsequent injections. It is assembled with a Hamilton removable needle and a syringe for injection, a Teflon-coated tungsten wire for recording, and polyimide tubing as a sheath. The device is inexpensive and easy to handle in anatomical and physiological experiments in awake monkeys.

Myolipoma of the round ligament: report of a case with a review of the English literature.

Tumours consisting of a mixture of mature adipose and smooth muscle tissues, including those designated lipoleiomyomas, fibrolipoleiomyomas and myolipomas, are exceedingly rare, but most often occur in the uterine corpus. We describe here a case of such a tumour arising in the right round ligament of a 44-year-old woman. The tumour, which measured approximately 20x15x10 cm, was well encapsulated and did not involve the intrapelvic organs. Intricate mixtures of adult adipose tissue and bland smooth muscle exhibited no cellular atypia or nuclear mitotic figures, and there was little vascular proliferation. We diagnosed the lesion as a myolipoma of soft tissue with dual differentiation, and have found only 13 cases of this tumour including our own in the English literature. The present tumour is the first reported in the round ligament. Although this tumour is rare, its recognition is important for the avoidance of erroneous diagnoses.

Detection of Epstein-Barr virus DNA in cardiac and aortic tissues from chronic, active Epstein-Barr virus infection associated with Kawasaki disease-like coronary artery aneurysms.

We describe three patients with chronic, active Epstein-Barr virus infection associated with Kawasaki disease-like coronary artery aneurysms. The Epstein-Barr virus genome was detected in three cardiac tissue samples and one aortic tissue sample examined by means of the polymerase chain reaction. These findings suggest that chronic Epstein-Barr virus infection may play a pathogenic role in the development of coronary artery aneurysms.

Excitotoxic acid lesions of the primate subthalamic nucleus result in transient dyskinesias of the contralateral limbs.

1. To examine the role of the subthalamic nucleus (STN) in the pathogenesis of dyskinesias, the STN was experimentally lesioned with fiber-sparing excitotoxins in two awake monkeys. 2. A combined recording-injection device was used to locate and lesion the STN accurately under physiological guidance. A small amount (1 microliters) of ibotenic acid (10 micrograms/microliters) or kainic acid (1 micrograms/microliters) was injected into each of four to seven target sites in the STN. Postmortem histology confirmed that lesions were confined to the STN, and the volume of each lesion at each site was 4-11% of the total volume of the nucleus. 3. Approximately 20 min after the end of each injection, the frequency of movements increased in the distal portions of the upper and lower limbs contralateral to the injection site. Severe dyskinesias, involving the proximal joints to a greater degree than the distal, developed in the contralateral limbs after 60-80 min and lasted < or = 4 h. The pattern of involvement and time course were similar after each lesion. In the days after the lesioning, only rare dyskinesias were observed in the contralateral hands and feet, typically occurring when the animals were stimulated. 4. Despite the severe dyskinesias, there was no obvious effect on voluntary movements such as grooming or reaching. 5. These results suggest that reduction of STN activity plays a role in the production of dyskinesias.

Excitotoxic acid lesions of the primate subthalamic nucleus result in reduced pallidal neuronal activity during active holding.

1. To gain a better understanding of the pathophysiology of hemiballismus in primates, and to test directly the hypothesis that the subthalamopallidal projection is excitatory, we studied the effects of lesions of the subthalamic nucleus (STN) on neuronal activity in the globus pallidus (GP) of monkeys during performance of a motor behavioral task. 2. Animals were trained to position and hold a manipulandum to which torque pulses were applied, producing elbow flexion and extension. The activity of neurons in the external (GPe) and internal (GPi) segments of GP was recorded in two monkeys during task performance before and after STN lesions. The STN was lesioned by the fiber-sparing neurotoxins ibotenic acid and/or kainic acid. 3. After lesioning, the firing rate of neurons in both segments of GP, which was measured during the period of holding before torque application, was significantly decreased in both animals. The mean of discharge rates of GPi neurons decreased (P < 0.001) from 69.8 (n = 169, SD = 21.6) to 47.4 spikes/s (n = 180, SD = 22.6) after lesioning. The mean of discharge rates of GPe neurons decreased from 63.6 spikes/s (n = 218, SD = 25.1) before lesions to 41.0 spikes/s (n = 208, SD = 18.1) after lesioning. 4. These results provide further evidence that STN gives rise to a major excitatory input to both segments of the GP and support the hypothesis that dyskinesias result from decreased GPi output.

[Acute pulmonary edema in five patients undergoing sevoflurane anesthesia].

Four adults and a child undergoing surgery with sevoflurane anesthesia developed acute pulmonary edema immediately after anesthesia. Prior to development of pulmonary edema all patients exhibited severe arterial hypertension and tachycardia. Their episodes of circulatory changes were, we believed, caused by the local injection of epinephrine for hemostasis in 2 patients (9 y.o. child, 45 y.o. man) and the intrusion of painful surgical stimuli in one patient (67 y.o. man). Circulatory changes in these three patients were treated by increasing the inspired sevoflurane concentration. We, however, speculate that the increase in inspired sevoflurane decreased the cardiac output and that the resulting increase in pulmonary wedge and capillary pressures was caused by an abrupt increase of arterial blood pressure, followed by a rapid increase in afterload due to cardiac suppression from the high concentration of sevoflurane. In 2 patients (74 y.o. man, 61 y.o. woman) arterial hypertension occurred during endotracheal extubation after sevoflurane anesthesia. Because of fast uptake and elimination of sevoflurane due to a low blood/gas partition coefficient, a fast awakening in the latter 2 patients, may be responsible for the abrupt increase in arterial blood pressure. In conclusion, it should be noted that pulmonary edema may be involved when severe circulatory changes occur in a patient undergoing sevoflurane anesthesia.