NO dissociation on Cu(111) and Cu2O(111) surfaces: a density functional theory based study.

NO dissociation on Cu(111) and Cu(2)O(111) surfaces is investigated using spin-polarized density functional theory. This is to verify the possibility of using Cu-based catalyst for NO dissociation which is the rate limiting step for the NO(x) reduction process. The dissociation of molecularly adsorbed NO on the surface is activated for both cases. However, from the reaction path of the NO-Cu(2)O(111) system, the calculated transition state lies below the reference energy which indicates the possibility of dissociation. For the NO-Cu(111) system, the reaction path shows that NO desorption is more likely to occur. The geometric and electronic structure of the Cu(2)O(111) surface indicates that the surface Cu atoms stabilize themselves with reference to the O atom in the subsurface. The interaction results in modification of the electronic structure of the surface Cu atoms of Cu(2)O(111) which greatly affects the adsorption and dissociation of NO. This phenomenon further explains the obtained differences in the dissociation pathways of NO on the surfaces.

Self-regeneration of a Pd-perovskite catalyst for automotive emissions control.

Catalytic converters are widely used to reduce the amounts of nitrogen oxides, carbon monoxide and unburned hydrocarbons in automotive emissions. The catalysts are finely divided precious-metal particles dispersed on a solid support. During vehicle use, the converter is exposed to heat, which causes the metal particles to agglomerate and grow, and their overall surface area to decrease. As a result, catalyst activity deteriorates. The problem has been exacerbated in recent years by the trend to install catalytic converters closer to the engine, which ensures immediate activation of the catalyst on engine start-up, but also places demanding requirements on the catalyst's heat resistance. Conventional catalyst systems thus incorporate a sufficient excess of precious metal to guarantee continuous catalytic activity for vehicle use over 50,000 miles (80,000 km). Here we use X-ray diffraction and absorption to show that LaFe(0.57)Co(0.38)Pd(0.05)O(3), one of the perovskite-based catalysts investigated for catalytic converter applications since the early 1970s, retains its high metal dispersion owing to structural responses to the fluctuations in exhaust-gas composition that occur in state-of-the-art petrol engines. We find that as the catalyst is cycled between oxidative and reductive atmospheres typically encountered in exhaust gas, palladium (Pd) reversibly moves into and out of the perovskite lattice. This movement appears to suppress the growth of metallic Pd particles, and hence explains the retention of high catalyst activity during long-term use and ageing.

Visual and tear function improvement after superficial phototherapeutic keratectomy (PTK) for mid-stromal corneal scarring.

PURPOSE: To study the changes in visual and tear film function following superficial excimer laser phototherapeutic keratectomy in patients with mid-stromal corneal scars. METHODS: Fourteen eyes of 14 patients with mid-stromal corneal scars seen at the Department of Ophthalmology at Kobe Kaisei Hospital underwent superficial phototherapeutic keratectomy (PTK). The subjects underwent routine ophthalmic examinations, corneal sensitivity measurements, tear film break-up time (BUT), Schrimer test and tear film lipid layer interferometry. Thirty eyes of 15 normal control subjects were also studied. The patients and the control subjects were compared for pre-PTK tear function parameters and tear film lipid layer interferometry grade. The alterations in these parameters within 6 months following PTK were also determined. RESULTS: Visual improvement was achieved in 12 eyes (86%). A hyperopic shift was observed in all eyes. The average pre-PTK corneal sensitivity and tear film BUT were lower in patients compared with control subjects before PTK. Tear film lipid layer interferometry grades were also higher in the patients than the controls before PTK. All these parameters improved gradually and significantly after PTK. Schirmer test results did not show any significant alterations after PTK. CONCLUSION: We conclude that PTK is an effective means of treating corneal scars and attaining visual improvement, even in cases with deeper corneal involvement, and may obviate the need for corneal transplantation. Simultaneous improvements in corneal sensitivity and tear film stability suggest favourable effects of PTK on the ocular surface.

Ocular surface changes after excimer laser phototherapeutic keratectomy.

PURPOSE: To study the ocular surface disorder in patients with Avellino, granular, and lattice dystrophy, band keratopathy, and corneal leukoma before and after excimer laser phototherapeutic keratectomy. DESIGN: A prospective case-controlled study. PARTICIPANTS: A total of 45 eyes of 33 patients with superficial corneal opacities seen at Kobe Kaisei Hospital, Department of Ophthalmology, and 40 eyes of 20 normal control subjects were studied. INTERVENTION: The subjects underwent routine ophthalmic examinations, corneal sensitivity measurements, tear film break up time (BUT), Schirmer test, tear film lipid layer interferometry, and conjunctival impression cytology. MAIN OUTCOME MEASURES: The patients and the control subjects were compared for prephototherapeutic keratectomy (PTK) tear function parameters, tear film lipid layer interferometry grade, goblet cell density, and conjunctival squamous metaplasia grade. Alterations of these parameters within 3 months after PTK were also looked for. RESULTS: The average pre-PTK corneal sensitivity and tear film break up time were lower in patients compared with control subjects before PTK. Tear film lipid layer interferometry grade and conjunctival squamous metaplasia grades were higher in the patients than the controls before PTK. All these parameters improved gradually and significantly after PTK. Goblet cell density was significantly lower in the patients compared with controls before PTK. Schirmer test results and goblet cell density did not show any significant alterations after PTK. CONCLUSIONS: Concurrent improvements in corneal sensitivity, tear film break up time, lipid layer interference grades, and conjunctival squamous metaplasia grades all point to the favorable effects of PTK on the ocular surface by improving the stability of the tear film and ocular surface health through attainment of a regular corneal surface and probably inducing qualitatively/quantitatively better mucin production by a healthier epithelium after PTK.

[A case of curatively operated gastric cancer with peritonitis carcinomatosa treated by intraperitoneal administration of CDDP.Etoposide and EAP therapy].

Intraperitoneal administration of cisplatin (CDDP) etoposide (VP-16) and EAP therapy (combination chemotherapy with CDDP, adriamycin (ADM) and etoposide provided the curative resection for advanced gastric cancer with peritonitis carcinomatosa in a 48-year-old woman. She suffered from epigastralgia. CT shows the ascites, and ultrasonography shows Schnitzler metastasis. First, CDDP 100 mg and etoposide 200 mg were given intraperitoneally. Then, the ascites completely disappeared. Next, the patient underwent EAP therapy, after which Schnitzler metastasis disappeared, and total gastrectomy was performed. Macroscopically, it was of H0P0N0S2. Histopathologically, it was poorly differentiated adenocarcinoma and n0s2. She has been doing well with no evidence of recurrence for 18 months after operation.

[Chemotherapy of biliary tract infections (XXXVII). Excretion into bile and gallbladder tissue levels of levofloxacin and its clinical effect in biliary tract infections].

Evaluations were made on biliary excretion and penetration into the gallbladder tissue of levofloxacin (LVFX, DR-3355), a new quinolone antibacterial agent, and its clinical efficacy in biliary tract infections. 1. Gallbladder tissue concentrations and biliary concentrations of LVFX at 2-6 hours at oral administration of 100 mg were 0.58-1.99 micrograms/g and 0.49-5.63 micrograms/ml, respectively. These tissue and biliary levels are almost equal or somewhat higher than the serum levels (0.55-1.63 micrograms/ml) of the compound. 2. The concentrations of LVFX and optical isomer DR-3354 in the serum, gallbladder tissue, and bile were determined after a single or a concomitant administration of LVFX 100 mg and/or ofloxacin (OFLX) 100 to 200 mg. The concentration ratio of LVFX to DR-3354 paralleled with the ratio of the 2 compounds administrated. 3. At a dose of 100 mg, the glucuronide of LVFX in the common duct bile was detected at proportions between 0.9 and 36.0%. 4. A total of 11 patients with biliary tract infections, including 6 cholecystitis 3 cholangitis, and 1 each of cholecystocholangitis and liver abscess was treated with LVFX at 100-200 mg t.i.d. for 3-14 days. Clinical results were excellent or good in 8 cases and fair in 3 cases, resulting in an efficacy rate of 72.7%. 5. A side effect and an abnormal change in laboratory findings were observed in both 1 case each and they were both mild. It was concluded that LVFX showed good penetration to the biliary tract as does OFLX, and that it would be a useful oral agent for the treatment of biliary tract infections.

Antagonistic interaction of laryngeal and central chemoreceptor respiratory reflexes.

Stimulation of laryngeal afferent fibers evokes a profound reflex inhibition of central respiratory drive. The interaction of this airway reflex with chemoreceptive ventilatory control mechanisms is poorly understood. The present study was undertaken to determine whether there is significant interaction between the effects of central chemoreceptor and laryngeal afferent stimulation on central inspiratory activity and, if so, to also determine the nature of the interaction. The effect of electrical stimulation of the superior laryngeal nerve (SLN) on the timing and intensity of central inspiratory activity was determined from the rectified and filtered phrenic neurogram in 10 dogs. Each dogs was decerebrated, artificially ventilated, vagotomized, and had the carotid bodies denervated. In each case, stimulation of the right SLN at 3 and 10 Hz caused a frequency-dependent slowing or arrest of central inspiratory activity. Increases in arterial PCO2 (PaCO2) attenuated the absolute level of inhibition of central inspiratory activity recorded during both SLN stimulation and control periods. Tp clarify the nature of the interaction between chemoreceptor and laryngeal afferent stimulation, the relationship between PaCO2 and central inspiratory activity was investigated during stimulation of the SLN at 0, 3, and 10 Hz. Control central inspiratory activity increased as a sigmoidal function of PaCO2. This sigmoidal relationship was greatly depressed during SLN stimulation but did not appear to be shifted along the PaCO2 axis. The results of this study therefore suggest that the interaction between central chemoreceptor and laryngeal afferent stimulation is multiplicative: the inhibition of the central inspiratory activity is mediated by an attenuation and not a resetting of central chemoreflexes.

The use of continuous spinal anesthesia in severe tetanus with autonomic disturbance.

Eight patients with severe tetanus experienced episodes of marked cardiovascular instability. During these unstable periods, cardiac output and vascular resistance varied independently. Beta blocking and low doses of ganglionic blocking agents failed to control cardiovascular instability even when combined. High doses of ganglionic blockers stabilized hemodynamics for a short period, but caused the elevation of transaminases. After unsuccessful treatment with cardiovascular drugs, continuous spinal anesthesia (CSA) was applied to five patients. For 5 to 23 days circulation was regulated artificially under complete blockade of the autonomic nervous system by infusing isotonic 0.5% bupivacaine intrathecally. Catecholamine was added intravenously to maintain adequate blood pressure. Before the introduction of CSA, three patients died of circulatory failure. In contrast, CSA dramatically suppressed the cardiovascular instabilities, and all five treated patients survived. This suggests that both sympathetic and parasympathetic nervous systems need to be blocked to stabilize hemodynamics in severe tetanus.

Effects of vasopressin and catecholamines on the maintenance of circulatory stability in brain-dead patients.

The effectiveness and reliability of long-term control of circulatory stability in brain-dead patients by combined administration of vasopressin and catecholamine was examined in detail. Twenty-five patients were divided into three groups according to the dose of vasopressin. The first group (n = 10) received no vasopressin, the second group (n = 2) an antidiuretic dose (0.1-0.4 U/hr), and the third group (n = 13) a pressor dose (1-2 U/hr), respectively. Patients given no vasopressin or an antidiuretic dose demonstrated circulatory deterioration and cardiac arrest within a short time after brain death, despite administration of a large dose of epinephrine. All patients with a pressor dose of vasopressin, however, demonstrated stable circulation as long as vasopressin and epinephrine were administered. Five patients in whom stable circulation was maintained by this technique were randomly chosen from the third group and studied under the following four conditions: (1) neither vasopressin nor epinephrine; (2) vasopressin only; (3) epinephrine only; and (4) both vasopressin and epinephrine. Compared with the controls (neither vasopressin nor epinephrine), vasopressin only increased the total peripheral resistance index, whereas epinephrine alone increased the cardiac index. Combined administration, however, raised the mean arterial blood pressure significantly by markedly increasing the total peripheral resistance index and cardiac index. Finally, in four brain-dead patients also randomly chosen from the third group, epinephrine, norepinephrine, and dopamine were compared in their circulatory effects with a pressor dose of vasopressin. Epinephrine increased both the total peripheral resistance index and cardiac index, whereas norepinephrine increased the total peripheral resistance index, compared with the baseline (no catecholamine). The required dose of norepinephrine, however, was four times that of epinephrine. The major effect of dopamine was to increase the cardiac index. We conclude that a pressor dose of vasopressin plays a central role in circulatory stabilization of brain-dead patients, and that long-term maintenance of stable circulation for a desired length of time is possible by the combined use of vasopressin and a catecholamine. Individually, catecholamines exhibit characteristic differences. Epinephrine has significant effects on both peripheral vessels and the heart, whereas norepinephrine keeps the circulation stable by increasing the total peripheral resistance index, with a much larger dose than epinephrine. Dopamine acts primarily on the heart.

A study on limulus amebocyte lysate (LAL) reactive material derived from dialyzers.

The amebocytes of horseshoe crab (Limulus) hemolymph contain a coagulation system highly sensitive to bacterial endotoxins. Limulus amebocyte lysate (LAL) reactive material derived from cuproammonium rayon membranes, however, is not an endotoxin and acts upon the alternative pathway in the coagulation cascade found in Limulus amebocyte lysate. This study confirmed these facts by using the coagulation system of Limulus without factor G, which is a substrate of the alternative pathway. LAL reactive material lingered in the circulation for a relatively long time. In acute hemodialysis, its plasma concentration increased by an average of 100 pg/ml with each dialysis and eventually reached a plateau of approximately 300 pg/ml. In patients with chronic renal failure under regular hemodialysis, the mean level of LAL reactive material was 330.0 +/- 8.0 pg/ml before hemodialysis which increased by 70.6 +/- 20.7 pg/ml after four hours of hemodialysis.

Optimal contractility and minimal oxygen consumption for constant external work of heart.

We theoretically considered the relation between left ventricular O2 consumption (MVO2) and a contractility index (Emax), searching for an optimal Emax that minimizes MVO2 for a given external mechanical work. We used one equation relating Emax with ventricular pressure and volume and another equation relating MVO2 with pressure-volume area (PVA). PVA is theoretically and experimentally a good predictor of MVO2 with Emax as a parameter. Then we could theoretically show the existence of the optimal Emax. For example, MVO2 was minimized to 8.9 ml O2.min-1.100 g-1 at an Emax of 6.3 mmHg.ml-1.100 g when cardiac output was 1.2 l/min, afterload pressure was 100 mmHg, and heart rate was 150 beats/min. These values can be observed experimentally in a 10- to 15-kg dog. Optimal Emax values for a wide range of external work fall in the middle of the normal working range of Emax. Thus our MVO2-PVA-Emax relationship supports the contemporary concept of the optimal contractility that MVO2 for a given cardiac external work is minimum at a middle level of ventricular contractility.

Efficiency of energy transfer from pressure-volume area to external mechanical work increases with contractile state and decreases with afterload in the left ventricle of the anesthetized closed-chest dog.

We studied the effects of ventricular end-systolic elastance (Ees) and effective arterial elastance (Ea) on the efficiency of energy transfer from pressure-volume area (PVA) to external mechanical work (EW) in the left ventricle of anesthetized closed-chest dogs. PVA represents the total mechanical energy generated by ventricular contraction, which is an intermediate form of energy between oxygen consumption, the total energy input, and EW, the effective energy output. PVA and EW were determined from ventricular pressure and volume, which were continuously measured with a volumetric conductance catheter. Measurements of Ees were obtained by transiently increasing afterload by an inflation of a Fogarty catheter in the thoracic descending aorta. Ea was determined as the ratio of end-systolic pressure to stroke volume. The EW/PVA efficiency of a steady-state contraction increased from 55% to 64%, with a 58% increase in Ees after dobutamine. Ees, which was smaller than Ea before dobutamine, became nearly equal to Ea after dobutamine, maximizing EW for a given end-diastolic volume. EW/PVA efficiency decreased with an abrupt increase in afterload before and after dobutamine. The sensitivity of the decrease in the EW/PVA efficiency to an increase in end-systolic pressure was significantly less after than before dobutamine. We could account for all these changes in EW/PVA efficiency by the relative changes in Ees and Ea in the pressure-volume diagram.

O2 consumption of dog heart under decreased coronary perfusion and propranolol.

We compared the effects of decreased coronary perfusion pressure (CP) and propranolol on the relation between left ventricular O2 consumption (VO2) and systolic pressure-volume area (PVA). PVA represents total mechanical energy generated by contraction and is the area under the end-systolic pressure-volume (PV) line and systolic PV trajectory. In excised cross-circulated dog hearts, a decrease in CP from 82 (mean) to 51 mmHg decreased ventricular contractility index Emax (slope of end-systolic PV relation) by 17% (P less than 0.05) and slightly (P less than 0.05 in 3 of 11 hearts) lowered the VO2-PVA relation in a parallel fashion. A further decrease in CP to 32 mmHg decreased Emax by 56% (P less than 0.05) and considerably (P less than 0.05) lowered the VO2-PVA relation by decreasing both the VO2-axis intercept by 26% (P less than 0.05) and the slope by 24% (P less than 0.05) from control. Propranolol decreased Emax by 48% (P less than 0.05) and the VO2-axis intercept by 25% (P less than 0.05) without changing the slope (P greater than 0.05). We attributed the different response of the VO2-PVA relation to the difference of the coronary O2 supply-demand balance between decreased CP and propranolol.

Oxygen-saving effect of negative work in dog left ventricle.

We compared left ventricular oxygen consumptions (VO2) of contractions performing negative external work (EW less than 0) and positive external work (EW greater than 0) that developed comparable peak systolic pressures in the excised cross-circulated dog hearts. We changed the polarity of ventricular work with volume servo-pump and measured both left ventricular VO2 and systolic pressure-volume area (PVA). PVA represents the total mechanical energy generated by contraction and is equal to the area circumscribed by the end-systolic and end-diastolic pressure-volume (PV) relation curves and the systolic PV trajectory. For comparable peak systolic pressures of approximately 90 mmHg, contractions performing negative EW of -834 +/- 327 mmHg.ml.100 g left ventricle-1 had 27 +/- 11% smaller VO2 and 62 +/- 12% smaller PVA than those performing positive EW of 851 +/- 329 mmHg.ml.100 g-1. The smaller VO2 for negative EW could be accounted for by the linear VO2-PVA relation regardless of the polarity and magnitude of work. The results indicate that negative work can save VO2 of contractions to develop a given peak systolic pressure.

Efficiencies from consumed O2 and pressure-volume area to work of in situ dog heart.

We studied the efficiencies from oxygen consumption (VO2) to external mechanical work (EW), from VO2 to the systolic pressure-volume area (PVA), and from PVA to EW, and the effects of cardiac output and contractility index (Emax) on these efficiencies in the left ventricle of open-chest, right-heart-bypassed dogs. PVA is an intermediate form of energy between VO2 and EW. PVA, EW, and Emax were determined by an abrupt occlusion of the ascending aorta. The right-heart bypass allowed us to collect all coronary venous return for VO2 measurement. The EW/VO2 efficiency ranged between 4 and 21%, the PVA/VO2 efficiency ranged between 5 and 27%, and the EW/PVA efficiency ranged between 60 and 95%. At a given Emax, EW/PVA efficiency was independent of cardiac output, but PVA/VO2 and EW/VO2 efficiencies increased with cardiac output. An increase in Emax by dobutamine increased EW/PVA efficiency, but decreased PVA/VO2 and EW/VO2 efficiencies. We could theoretically account for these changes in EW/PVA, PVA/VO2, and EW/VO2 efficiencies of the in situ heart by the VO2-PVA relation and its dependence on Emax that we had observed.

Ventricular systolic pressure-volume area (PVA) and contractile state (Emax) determine myocardial oxygen demand.

We have briefly reviewed the recent advances in the understanding of primary determinants of cardiac oxygen consumption (Vo2). We focused on our own experimental findings that Vo2 is a function of left ventricular systolic pressure-volume area (PVA), as a measure of total mechanical energy generated by contraction, and the left ventricular contractility index (Emax). We conclude that the cardiac oxygen demand of the ongoing contractions is equivalent to Vo2 and is a precise function of PVA and Emax whether coronary oxygen supply is normal or mildly limited in the excised, cross-circulated dog left ventricle. However, when the coronary oxygen supply is severely limited, Vo2 may not always be equivalent to the oxygen demand capability shown by the heart when its coronary oxygen supply is restored.

The different contributions of coronary blood flow to changes in myocardial oxygen consumption between excised and in situ canine hearts.

The correlations of CBF-MVO2 and AVD-MVO2 were analyzed by linear regression analysis in three groups of canine heart preparations. CBF correlated well with MVO2 in all cases of in situ heart preparations, and the sensitivity of CBF to changes in MVO2 was high. In contrast, AVD, rather than CBF, correlated well with MVO2 in all cases of excised hearts, and the sensitivity of CBF to changes in MVO2 was low. The different manner of oxygen delivery in excised hearts from that in situ hearts can be attributed to the characteristics of its coronary perfusion and the impaired mechanism of metabolic vasoregulation in the coronary vasculature.

Long-term continuous spinal anesthesia in severe tetanus with autonomic disturbance.

The mortality rate from tetanus is still high if the disease is accompanied by signs of autonomic nervous system dysfunction. We treated a 75-year-old woman with tetanus and autonomic dysfunction with continuous high spinal anesthesia for 23 days. She recovered. Spinal anesthesia may be a useful adjunct for the treatment of severe tetanus.

[Renal tubular impairment in traumatized patients].

Urinary beta 2-microglobulin (beta 2M) and N-acetyl-beta-D-glucosaminidase (NAG) in addition to conventional renal parameters such as creatinine clearance (Ccr), free water clearance (CH2O) and fractional excretion of sodium (FENa) were measured in 79 traumatized patients. These patients were separated into two groups, one with shock on admission (N = 43). In patients with shock, CH2O, FENa and urinary excretion of Beta 2M and NAG indicated abnormal levels correlating with impairment of Ccr, inspite of adequate urine output, on the day of trauma. Even in patients without shock, urinary Beta 2M and/or NAG increased without impairment of urine output, Ccr, CH2O and FENa, and did not return to normal level during the following 7 days. The results suggest a liability to damage and the delayed improvement of renal tubulus in traumatized patients.

Prolonged hemodynamic maintenance by the combined administration of vasopressin and epinephrine in brain death: a clinical study.

The present study attempted long term hemodynamic maintenance in 16 adult brain-dead patients, 14 with head injury and 2 with cerebrovascular accidents. In addition to respiratory and fluid management, 10 were treated with continuous infusion of epinephrine to maintain systolic blood pressure above 90 mm Hg. The remaining 6 patients each received a continuous infusion of synthetic arginine vasopressin (ADH) at a rate of 1 or 2 units/hour (285 +/- 45 microunits/kg/minute) simultaneously with epinephrine. The 10 patients treated with epinephrine alone all succumbed to cardiac arrest within 48 hours of brain death, with a mean survival time of 24.1 +/- 17.2 hours. In the patients who received simultaneous ADH infusion, a minimal dose of epinephrine of no more than 0.5 mg/hr in most instances sufficed to maintain blood pressure. Their mean survival time after brain death was remarkably prolonged to 23.1 +/- 19.1 days. In brain death, ADH plays a critical role in hemodynamic maintenance, and ADH administration permits long term hemodynamic stabilization of brain-death patients, offering increasing opportunities for organ transplantation.