Fabrication of Hydrogen Boride Thin Film by Ion Exchange in MgB2

In this study, hydrogen boride films are fabricated by ion-exchange treatment on magnesium diboride (MgB₂) films under ambient temperature and pressure. We prepared oriented MgB₂ films on strontium titanate (SrTiO₃) substrates using pulsed laser deposition (PLD). Subsequently, these films were treated with ion exchangers in acetonitrile solution. TOF-SIMS analysis evidenced that hydrogen species were introduced into the MgB₂ films by using two types of ion exchangers: proton exchange resin and formic acid. According to the HAXPES analysis, negatively charged boron species were preserved in the films after the ion-exchange treatment. In addition, the FT-IR analysis suggested that B-H bonds were formed in the MgB₂ films following the ion-exchange treatment. The ion-exchange treatment using formic acid was more efficient compared to the resin treatment; with respect to the amount of hydrogen species introduced into the MgB₂ films. These ion-exchanged films exhibited photoinduced hydrogen release as observed in a powder sample. Based on the present study, we expect to be able to control the morphology and hydrogen content of hydrogen boride thin films by optimising the ion-exchange treatment process, which will be useful for further studies and device applications.

Longitudinal study of auditory brainstem response in leigh syndrome

To assess the utility of auditory brainstem response (ABR) in diagnosing brainstem changes in patients with Leigh syndrome (LS), we performed a longitudinal study of five patients with LS using both ABR and neuroimaging techniques (CT and MRI). The brainstem components of the initial ABRs we performed on the patients were abnormal in all five patients. In four of the patients, these abnormal findings preceded any clinical signs of brainstem impairment. Improvements in clinical findings were reflected in improvements in ABR findings in three patients. In one of these three patients, improvements in clinical findings were also reflected in improvements in MRI findings. In the other two patients, MRI findings showed no improvements, despite the improvements in clinical findings. In two of our patients, ABR clearly revealed functional improvements in the brainstem which were not revealed by MRI. Therefore, we conclude that ABR is an essential diagnostic technique for patients with LS.

[A survey on occupational health nursing activities and evaluation in TOHOKU area]

We did a mail survey in 1998 in Tohoku district. We sent questionnaires to approximately 300 Occupational Health (OH) nurses and got 132 replies. Occupations of respondents were 66 public health nurses and 57 nurses. More than 70% did not have a managerial position. About 40% were respondents without colleagues in nursing occupations. Full time occupational physicians were in 40% of companies, and semi-full time occupational physicians were in 60%. Respondents citing good coordination in the former were 60%, and in the latter were 80%. Of all business activities occupying OH nursing employees, persons who performed more than 90% of the tasks numbered more than 30%. Persons not satisfied with present employment positions were 80%. Reasons for dissatisfaction in declining order of incidence were work duties, contract conditions for employment, and personal relations. Planning and summary of OH nursing activities were carefully done highly. For the OH nursing activity evaluation, we examined guidelines for business locations by observing them from the OH nursing aspect and the OH nursing job itself. Guidelines considered for business locales from the OH nursing vantage point show numerically, for example, rates of examinees with abnormal findings, work absenteeism, etc, and expectations as to whether or not health conditions are conspicuously reflected in productivity. Conversely, from the OH nursing vantage point for guidelines on business locales, while receiving affirmative economic evaluation of occupational health and safety measures, progress (process) should also be included in the object of evaluation. Furthermore, guidelines should be mindful of the need to have qualitative and quantitative changes in health behavior of workers and perspectives on health.

Long-term denervation impairs insulin receptor substrate-1-mediated insulin signaling in skeletal muscle

Long-term denervation is associated with insulin resistance. To investigate the molecular bases of insulin resistance, the downstream signaling molecules of insulin receptor including insulin receptor substrate-1 (IRS-1) and phosphatidylinositol 3-kinase (PI 3-K) were examined in skeletal muscle of rats after 7 days of denervation. Long-term denervation attenuated insulin-stimulated activation of the initial steps of the intracellular signaling pathway. Insulin-stimulated tyrosine phosphorylation of insulin receptor was reduced to 36% (P < .005), as was the phosphorylation of IRS-1 to 34% (P < .0001) of control. While insulin receptor protein level was unchanged, the protein expression of IRS-1 was significantly decreased in denervated muscles. Insulin-stimulated percent tyrosine phosphorylation of IRS-1, normalized to the IRS-1 protein expression, was also reduced to 55% (P < .01) of control in denervated muscle. Denervation caused a decline in the insulin-induced binding of p85 regulatory subunit of PI 3-K to IRS-1 to 61% (P < .001) and IRS-1-associated PI 3-K activity to 57% (P < .01). These results provide evidence that long-term denervation results in insulin resistance because of derangements at multiple points, including tyrosine phosphorylation of insulin receptor and its downstream signaling molecule, IRS-1, protein expression of IRS-1, and activation of PI 3-K.

Immobilization depresses insulin signaling in skeletal muscle

Prolonged immobilization depresses insulin-induced glucose transport in skeletal muscle and leads to a catabolic state in the affected areas, with resultant muscle wasting. To elucidate the altered intracellular mechanisms involved in the insulin resistance, we examined insulin-stimulated tyrosine phosphorylation of the insulin receptor beta-subunit (IR-beta) and insulin receptor substrate (IRS)-1 and activation of its further downstream molecule, phosphatidylinositol 3-kinase (PI 3-K), after unilateral hindlimb immobilization in the rat. The contralateral hindlimb served as control. After 7 days of immobilization of the rat, insulin was injected into the portal vein, and tibialis anterior muscles on both sides were extracted. Immobilization reduced insulin-stimulated tyrosine phosphorylation of IR-beta and IRS-1. Insulin-stimulated binding of IRS-1 to p85, the regulatory subunit of PI 3-K, and IRS-1-associated PI 3-K activity were also decreased in the immobilized hindlimb. Although IR-beta and p85 protein levels were unchanged, IRS-1 protein expression was downregulated by immobilization. Thus prolonged immobilization may cause depression of insulin-stimulated glucose transport in skeletal muscle by altering insulin action at multiple points, including the tyrosine phosphorylation, protein expression, and activation of essential components of insulin signaling pathways.

Skeletal muscle apoptosis after burns is associated with activation of proapoptotic signals

Critical illness is associated with muscle wasting and muscle weakness. Using burn injury as a model of local and systemic inflammatory response, we tested the hypothesis that thermal injury causes apoptosis in muscle. After a 40% body surface area burn to rats, abdominal muscles beneath the burn and limb muscles distant from the burn were examined for apoptosis at varying times after burn. Ladder assay, ELISA, and histological methods showed evidence of apoptosis in the abdominal muscles within 4-12 h with peak changes occurring at 3-7 days. Maximal apoptosis was also evident at distant limb muscles at 3-7 days. Investigation of proapoptotic pathways indicated mitochondrial membrane potential to be altered by 1 h after burn. Starting at 15 min after burn, cytochrome c was released from the mitochondria into the cytosol, followed by increased activity of caspase-3, starting at 6 h after burn. These studies suggest that mitochondria and caspase-mediated apoptotic pathways may be an additional mechanism of muscle weight loss in burns and may be potential therapeutic targets for prevention of muscle wasting.

The 1999 Moyer award. Burn injury induces skeletal muscle apoptosis and the activation of caspase pathways in rats

Burn injury induces many metabolic disorders, including altered protein kinetics with muscle weakness. The skeletal muscle weakness that occurs as a result of the loss of muscle mass causes hypoventilation and dependence on respirators, a condition that increases morbidity and mortality. The presence or absence of apoptosis in muscle, which can be a cause of the loss of muscle mass, was studied in rats after they had received scald burns to 40% of their body surface areas. The potential pro-apoptotic pathways that were activated were also examined. The burn injury produced did not directly destroy the muscle beneath; muscles just beneath the burned surface showed dramatic apoptotic changes according to assessments with the cell death enzyme-linked immunosorbent assay and in situ TdT-mediated dUTP-X nick-end labeling staining. The extent of apoptosis reached a peak on postburn days 3 and 7. Of note is that apoptosis was also confirmed in muscles at sites distant from the burn injury (eg, tibialis anterior) on both postburn days 3 and 7, a condition that is suggestive of the systemic effects of pro-apoptotic factors. To show that heat itself causes the initiation of the pro-apoptotic signaling, muscle-derived C2C12 cells were subjected to heat treatment at 55 degrees C. Ceramide, a key apoptotic second messenger, was observed to increase in the caveolae fraction but not in non-caveolae fraction of these muscle cells. In muscle tissue from burned rats, stress-activated protein kinase (a downstream-signaling kinase of ceramide) was activated soon after burn injury; this finding is consistent with the hypothesis that ceramide plays a role in burn-induced apoptosis. Caspase-1, -3, and -9, important final apoptotic enzymes involved with the downstream signaling of stress-activated protein kinase, were also activated after burn injury in muscle tissue from burned rats. These findings confirm the hypothesis that apoptosis occurs in skeletal muscle and that major apoptotic pathways are activated after a burn injury. Further characterization of these apoptotic signaling cascades may provide new therapeutic targets for the prevention of burn-induced muscle wasting.

A unique mechanism of desensitization to lipolysis mediated by beta(3)-adrenoceptor in rats with thermal injury

Thermal injury causes a hypermetabolic state associated with increased levels of catabolic hormones, but the molecular bases for the metabolic abnormalities are poorly understood. We investigated the lipolytic responses after beta(3)-adrenoceptor (beta(3)-AR) agonists and evaluated the associated changes in beta-AR and its downstream signaling molecules in adipocytes isolated from rats with thermal injury. Maximal lipolytic responses to a specific beta(3)-AR agonist, BRL-37344, were significantly attenuated at post burn days (PBD) 3 and 7. Despite significant reduction of the cell surface beta(3)-AR number and its mRNA at PBD 3 and 7, BRL-37344 and forskolin-stimulated cAMP levels were not decreased. Glycerol production in response to dibutyryl cAMP, a direct stimulant of hormone-sensitive lipase (HSL) via protein kinase A (PKA), was significantly attenuated. Although immunoblot analysis indicated no differences in the expression and activity of PKA or in the expression of HSL, HSL activity showed significant reductions. Finally, beta(3)-AR-induced insulin secretion was indeed attenuated in vivo. These studies indicate that the beta(3)-AR system is desensitized after burns, both in the adipocytes and in beta(3)-AR-induced secretion of insulin. Furthermore, these data suggest a complex and unique mechanism underlying the altered signaling of lipolysis at the level of HSL in animals after burns.

Efficacy of extracorporeal ultrafiltration of ascitic fluid as a treatment of refractory ascites

BACKGROUND

Refractory ascites is recognized in patients with various conditions. Although intravenous reinjection of ascitic fluid after its filtration and concentration (IRA) is an effective method of treating this condition, many associated side-effects have been reported. We performed extracorporeal ultrafiltration of ascitic fluid (EUA) to demonstrate the efficacy and advantages of this method of treating refractory ascites.

METHODS

EUA was performed in seven patients with hepatic cirrhosis (3 cases), lupus nephritis, diabetic nephropathy, and carcinomatous peritonitis (2 cases) for a total of 122 sessions. IRA was performed in three of these seven patients for a total of 12 sessions.

RESULTS

The average volumes of ascitic fluid removed by EUA and IRA were 3.94+/-1.45 litres and 2.87+/-0.69 litres (mean+/-SD) respectively. Although chills and acute renal failure were recognized as complications of IRA in five and one sessions respectively, the only complication of EUA was severe intra-abdominal haemorrhage, which resolved spontaneously. In spite of rapid and massive removal of ascitic fluid (maximum 2.0 litres per 15 min), significant changes in blood pressure were not noted during EUA. In three patients (hepatic cirrhosis, lupus nephritis, and diabetic nephropathy), de novo production of ascitic fluid disappeared. In one patient with hepatic cirrhosis and chronic renal failure on haemodialysis, 67 sessions of EUA have been performed under stable conditions. Three patients (one case of hepatic cirrhosis and two cases of carcinomatous peritonitis) died of their primary diseases.

CONCLUSIONS

We conclude that EUA is a useful method for the treatment of massive refractory ascites.

Infective endocarditis-induced crescentic glomerulonephritis dramatically improved by plasmapheresis

A 50-year-old woman was referred to our hospital because of skin purpura, anemia, high fever, and acute renal insufficiency. Five years ago, she had been diagnosed as having ventricular septal defect without any complications. A blood culture drawn during the hospitalization grew Streptococcus viridans. She was diagnosed as having infective endocarditis-induced crescentic glomerulonephritis (GN) according to echocardiography and renal biopsy results. Although antibiotic treatment alone showed no apparent efficacy, after the initiation of plasmapheresis, the high fever and acute renal insufficiency were dramatically improved. After clinical stability was achieved, closure of the ventricular septal defect was performed. This result suggests that plasmapheresis may be beneficial in the treatment of infective endocarditis-induced crescentic GN. The possible mechanisms of this therapy are discussed.

Regulation of brain G-protein go by Alzheimer's disease gene presenilin-1

To investigate a possible association between G-proteins and presenilin-1 (PS-1), a series of glutathione S-transferase-fusion proteins containing portions of PS-1 were prepared and used in vitro in binding experiments with tissue and recombinant G-proteins. The results demonstrate that the 39 C-terminal amino acids of PS-1 selectively bind the brain G-protein, Go. Addition of guanosine 5'-3-O-(thio)triphosphate promoted Go dissociation from PS-1, indicating that this domain mimics the function of G-protein-coupling domains found in receptors. The 39-amino acid synthetic polypeptide activated Go in a magnesium ion-dependent manner. Physical interaction of full-length PS-1 and Go was also demonstrated. Following transfection of Goalpha and N-terminally FLAG-tagged PS-1 in COS-7 cells, Go was immunoprecipitated by FLAG antibodies. In addition, endogenous PS-1 and Goalpha were colocalized immunocytochemically in human glioma cell lines. The results indicate that PS-1 regulates Go activities in living cells.

Value of iodine-123 metaiodobenzylguanidine scintigraphy in patients with vasospastic angina

To assess the presence and location of presynaptic myocardial sympathetic abnormality in patients with vasospastic angina, iodine-123 labelled metaiodobenzylguanidine (MIBG) single-photon emission tomography (SPET) was performed. Fifty patients suspected of having vasospastic angina pectoris were enrolled in the study. All patients underwent a provocative test with intracoronary ergonovine infusion during coronary angiography, in which 99%-100% obstructive spasm was defined as a positive result. Twenty-five patients were diagnosed as having vasospastic angina based on a positive provocative test. MIBG SPET was performed at 20 min and 3 h after administration of 111 MBq or MIBG. On early images, only 5 of 25 patients with vasospastic angina showed a mild reduction in MIBG uptake, whereas 3-h delayed images demonstrated MIBG abnormality in 20 patients (80%). The location of the MIBG abnormality was completely or partially consistent with the spastic coronary territory in 18 patients. On the other hand, only 4 of 25 patients (16%) with negative provocative test demonstrated reduced MIBG uptake. Accordingly, positive and negative predictive values of MIBG SPET for the provocative test were 83% (20/24) and 81% (21/26) respectively. In conclusion, MIBG scintigraphy with SPET can permit the non-invasive detection and evaluation of suspected vasospastic angina.

Recombinant expression of caveolin-1 in oncogenically transformed cells abrogates anchorage-independent growth

Caveolae are plasma membrane-attached vesicular organelles. Caveolin-1, a 21-24-kDa integral membrane protein, is a principal component of caveolae membranes in vivo. Both caveolae and caveolin are most abundantly expressed in terminally differentiated cells: adipocytes, endothelial cells, and muscle cells. Conversely, caveolin-1 mRNA and protein expression are lost or reduced during cell transformation by activated oncogenes such as v-abl and H-ras (G12V); caveolae are absent from these cell lines. However, its remains unknown whether down-regulation of caveolin-1 protein and caveolae organelles contributes to their transformed phenotype. Here, we have expressed caveolin-1 in oncogenically transformed cells under the control of an inducible-expression system. Regulated induction of caveolin-1 expression was monitored by Western blot analysis and immunofluorescence microscopy. Our results indicate that caveolin-1 protein is expressed well using this system and correctly localizes to the plasma membrane. Induction of caveolin-1 expression in v-Abl-transformed and H-Ras (G12V)-transformed NIH 3T3 cells abrogated the anchorage-independent growth of these cells in soft agar and resulted in the de novo formation of caveolae as seen by transmission electron microscopy. Consistent with its antagonism of Ras-mediated cell transformation, caveolin-1 expression dramatically inhibited both Ras/MAPK-mediated and basal transcriptional activation of a mitogen-sensitive promoter. Using an established system to detect apoptotic cell death, it appears that the effects of caveolin-1 may, in part, be attributed to its ability to initiate apoptosis in rapidly dividing cells. In addition, we find that caveolin-1 expression levels are reversibly down-regulated by two distinct oncogenic stimuli. Taken together, our results indicate that down-regulation of caveolin-1 expression and caveolae organelles may be critical to maintaining the transformed phenotype in certain cell populations.

[Perforation of the intestine by a peritoneal tube 10 years after a ventriculo-peritoneal shunt]

A case is reported of intestinal perforation by a ventriculoperitoneal shunt (V-P shunt) tube 10 years after V-P shunt. A 49-year-old male received V-P shunt for normal pressure hydrocephalus following subarachnoid hemorrhage. Ten years later he was admitted to our department with an abscess on the anterior chest and on the abdominal wall along the shunt tube. When CT scan revealed that the peritoneal tube had perforated the bowel, the shunt was removed. During the operation it was found that the peritoneal tube was wrapped with fibrous tissue and that it had perforated the intestine. The subcutaneous abscess healed after the patient received systemic antibiotics. He was discharged and returned to work. We discussed the mechanism of bowel perforation in this case. It is assumed that bowel perforation occurred because of continuous friction at the same site of the bowel wall after the peritoneal tube received fibrous encasement in the abdominal cavity. Bowel perforation was diagnosed ten years after the V-P shunt in this case. To our knowledge, this is the longest period amongst reported cases.

Evolution of coronary vascular tone in vasospastic angina

In general, anginal symptoms diminish with time in patients with vasospastic angina. We assessed changes in coronary vascular tone (CVT) in patients with vasospastic angina over a 4-year period to evaluate the time course of spastic activity. Vasospastic angina was evaluated in 39 patients in whom occlusive spasm was evoked by selective intracoronary injection of ergonovine maleate (ERG-S) 48 h after stopping all coronary vasodilator drugs. These patients had no organic coronary stenosis and developed no stenosis during follow-up. ERG-S was repeated 3 times at 2-year intervals. CVT was determined at each ERG-S study using the equation: CVT = 1-(coronary artery diameter before ERG-S/coronary artery diameter after intracoronary injection of isosorbide dinitrate). Thirty-four patients (87%) had no angina pectoris at the second ERG-S study and 28 (72%) had none at the third. Coronary spasm was induced in 25 patients at the second ERG-S study and in 20 at the third. The overall CVT was shown to decrease at each successive ERG-S study (p < 0.01). There was no correlation between changes in CVT and anginal symptoms or the coronary spasm induction rate. These results demonstrate that CVT decreases over time in patients with vasospastic angina, suggesting that myocardial ischemia may improve spontaneously.

Clonal involvement of eosinophils in therapy-related myelodysplastic syndrome with eosinophilia, translocation t(1;7) and lung cancer

We report a therapy-related MDS (RAEB) patient with eosinophilia, unbalanced translocation der(7)t(1;7) (q12;q22) and lung cancer. We observed no increase in cytokine levels in serum or in the conditioned medium (CM) of peripheral T cells cultured with or without IL-2. When bone marrow (BM) cells were cultured with GM-CSF, IL-3 and SCF in a semisolid system, the colonies were exclusively eosinophilic. Cytogenetic analysis of the colony cells identified the same chromosome abnormality in all metaphases to that of BM cells. Suspension and clonogenic colony assay of BM cells cultured with various cytokines showed predominant eosinophilic growth and differentiation with GM-CSF, but not with the other cytokines examined. These findings, together with mild morphological abnormalities of eosinophils, indicate clonal involvement of eosinophils in the myelodysplastic syndrome (MDS) clone, and that the eosinophilia was derived from the neoplastic clone with the translocation and was not associated with the patient's lung cancer.

Use of a split dura for revascularization of ischemic hemispheres in moyamoya disease

A new technique of indirect revascularization using the dural arterial supply to provide donor vessels is presented together with the results of an assay performed to determine the angiogenic activity of the dura. At surgery, a portion of the dura near the branches of the middle meningeal artery was split into outer and inner layers, and the split surface of the outer layer was attached to the cortical surface. This procedure, combined a with standard encephaloduroarteriosynangiosis, was applied to 25 hemispheres in 18 patients with pediatric moyamoya disease (mean age 6 years). All of the patients were symptom free by 1.5 years after surgery. The follow-up period ranged from 1 to 12 years (mean 6.5 years). Thirteen (81%) of 16 patients were able to lead normal lives and three were mildly handicapped due to mental retardation that existed preoperatively. Postoperative superselective angiograms demonstrated effective cortical revascularization through the dural arteries as well as from the scalp arteries. A histological study of the dura in cases of moyamoya disease showed an increased number of blood vessels in the outer layer. Angiogenic activity determined by chorioallantoic membrane assay was higher in the split surface of the dura than in the internal surface of the dura (the natural interface between the dura and cortex). The split duroencephalosynangiosis described in this report is a useful addition to indirect revascularization techniques, allowing extension of the area of revascularization in the ischemic hemispheres of patients with moyamoya disease.

Regression of moyamoya vessels and hemodynamic changes after successful revascularization in childhood moyamoya disease

Successful revascularization improves ischemic symptoms in the pediatric patients with moyamoya disease. However, it is not clear whether the revascularization prevents future intracranial hemorrhage from the residual moyamoya vessels. The purpose of this study is to investigate perioperative morphological and hemodynamic changes in the moyamoya vessels. Four pediatric patients (age < 15 years old) with bilateral moyamoya disease were selected for this study. To quantify the number of moyamoya vessels, T1-weighted transverse images at the level of the basal ganglia and the thalamus were selected and characteristic flow voids in the lentiform nucleus were counted. Resting CBF and cerebrovascular reserve capacity (CRC) were measured pre- and 1 year after surgery using Xenon-CT CBF method with acetazolamide test. The ratio of deep CBF/cortical CBF was calculated as an index of hemodynamic stress distribution. The one-year follow-up studies showed that 1) the number of moyamoya vessels decreased on the operative side, but did not change on the non-operative sides in all cases; 2) the ratio of deep CBF/cortical CBF decreased on the operative sides, but did not change in the non-operative sides; and 3) the CRC increased on both sides. This observation suggests the possibility that revascularization surgery may be effective for preventing the future risk intracranial hemorrhage.

Constancy and variability of contractile efficiency as a function of calcium and cross-bridge kinetics: simulation

We simulated myocardial Ca2+ (Ca) and cross-bridge (CB) kinetics to get insight into the experimentally observed constancy and variability of cardiac contractile efficiency in generating total mechanical energy under various inotropic and pathological conditions. The simulation consisted of a Ca transient, Ca association and dissociation rate constants of troponin C, and CB on and off rate constants. We evaluated sarcomere isometric twitch contractions at a constant muscle length. We assumed that each CB cycle hydrolyzes one ATP and that the force-length area (FLA) quantifies the total mechanical energy generated by CB cycles in a twitch contraction. FLA is a linear version of pressure-volume area, which quantifies the total mechanical energy of cardiac twitch contraction and correlates linearly with cardiac oxygen consumption (H. Suga, Physiol. Rev. 70: 247-277, 1990). The simulation shows that the contractile efficiency varies with changes in the Ca transient and Ca and CB kinetics except when they simultaneously speed up or slow down proportionally. These results point to possible mechanisms underlying the constancy and variability of cardiac contractile efficiency.

Myocardial VO2 of mechanically unloaded contraction of rat ventricular slices measured by a new approach

We instituted a new approach of measuring mechanically unloaded myocardial oxygen consumption (VO2) by using rat left ventricular (LV) slices in an air-tight chamber filled with oxygenated Tyrode solution. Myocardial slices (300 microns in thickness) freely shortened without external load by electrical field stimulation (St). VO2 without St (n = 6) was 1.69 +/- 0.41 ml O2.min-1.100 g LV-1. VO2 with St (n = 6) increased to 2.28 +/- 0.36 ml O2.min-1.100 g LV-1. VO2 in Ca(2+)-free Tyrode solution irrespective of St was nearly equal to VO2 without St in normal Tyrode solution, indicating that all these VO2 correspond to basal metabolic VO2. The increment in VO2 by St (delta VO2) increased up to twice normal with the extracellular Ca2+ concentration up to 4 times normal. Inhibition of cross-bridge cycling by 2,3-butanedione monoxime (5 and 10 mM) did not decrease delta VO2. These results suggest that delta VO2 consists of VO2 primarily for excitation-contraction coupling but not for cross-bridge cycling.

[Prevention of MRSA spread in the neurosurgical field]

We investigated the distribution of MRSA (methicillin-resistant Staphylococcus aureus) on and around six patients with MRSA infection in our neurosurgical ward. All patients had a disturbance of consciousness and had sputum colonization of MRSA. Samples were obtained from 11 sites (patients' hands, attendances' hands, floors, sidetables, bedclothes, chairs, walls, curtains, door knobs, faucets and disposable gloves) in the patients' rooms by the wiping method. High counts of MRSA were detected on horizontal planes such as floors, sidetables and chairs, but MRSA was not detected on vertical planes such as curtains and walls. The reason why MRSA was detected on the horizontal planes was due to a fall of MRSA spread from sputum in the air. These findings indicate that the disinfection of horizontal planes is important for preventing the spread of MRSA. We also evaluated what disinfectant was useful for floor disinfection and concluded that 0.5% chlorhexidine digluconate (Hibitane) and 0.5% benzalkonium chloride (Osvan) were more effective than the other usually-used disinfectants such as alkyldiaminoethyl glycine (Tego-51).

[Endovascular stenting for a recurrent angina patient]

We report successful Palmaz-Schatz stenting for recurrent angina. Coronary arteriography in a 65-year-old man with recurrent angina six months after coronary artery bypass grafting (CABG) showed stenosis in the right coronary artery and in the saphenous vein graft to the left anterior descending artery. For both stenotic lesions, balloon dilatation was performed. However, both lesions recoiled after dilatation. Therefore, Palmaz-Schatz stents were inserted in both stenotic lesions. After stenting, the patient did not experience any further chest pain. Three months later coronary arteriography showed the stents remained patient. Balloon angioplasty for post-CABG angina is technically easier than additional surgery. However, angioplasty by balloon dilatation alone can induce dangerous complications during the acute phase and restenosis frequently develops. This method is not sufficiently effective or safe for recurrent angina. To prevent these problems, the stent was developed as a useful adjunct to balloon dilatation for the native artery. Using this new device, angioplasty for recurrent angina will be safer and more effective than additional surgery.

Logistic time constant of isovolumic relaxation pressure-time curve in the canine left ventricle. Better alternative to exponential time constant

BACKGROUND

The time constant of left ventricular (LV) relaxation derived from a monoexponential model has been widely used as an index of LV relaxation rate or lusitropism, although this model has several well-recognized problems. In the present study, we proposed a logistic model and derived a "logistic" time constant (TL) as a better alternative to the conventional "exponential" time constant (TE).

METHODS AND RESULTS

A total of 189 beats (147 isovolumic and 42 ejecting beats) were investigated in seven canine excised cross-circulated heart preparations. We found that the logistic model fitted much more precisely all the observed LV isovolumic relaxation pressure-time [P(t)] curves than the monoexponential model (P < .05). The logistic model also fitted well both the time curve of the first derivative of the observed P(t) (dP/dt) and the dP/dt-P(t) phase-plane curve. Like TE, TL indicated that volume loading depressed LV lusitropism and that increasing heart rate and ejection fraction augmented it. TL was independent of the choice of cutoff point defining the end of isovolumic relaxation; TE was dependent on that choice.

CONCLUSIONS

We conclude that the logistic model better fits LV isovolumic relaxation P(t) than the monoexponential model in the present heart preparation. We therefore propose TL as a better alternative to TE for evaluating LV lusitropism.

Effects of capsaicin on mechanoenergetics of excised cross-circulated canine left ventricle and coronary artery

Capsaicin selectively acts on sensory nerve endings in cardiac muscles and coronary arterial smooth muscles. Capsaicin at high doses has cell-nonselective effects including both inhibition of cardiac muscle exciteability and enhancement of vascular smooth muscle tone. We studied whether and how intracoronary infusion of capsaicin affects mechanoenergetics of the excised blood-perfused canine heart and coronary vascular resistance. We found that capsaicin at low concentrations increased Emax (a contracility index) and oxygen consumption (VO2) possibly due to a specific action on capsaicin-sensitive sensory nerves in left ventricular muscles, though in a small number of hearts (3/10). This result coincides with the reported histochemical observations that the distribution of capsaicin-sensitive sensory nerves in the canine left ventricle is not dense. Capsaicin at high doses dose-dependently decreased Emax and proportionally decreased coronary flow. It also lowered the linear VO2-PVA (pressure-volume area; total mechanical energy) relationship without a change in the slope, decreasing unloaded VO2 (VO2 intercept of the VO2-PVA relation). These effects of high-dose capsaicin seem to be direct negative inotropic action on cardiac muscles associated with enhancement of coronary arterial smooth muscle tone, since these effects were not desensitized. No morphological changes of myocardial cells or mitochondria were detected. Therefore, the negative inotropic action is not due to the toxic effect of capsaicin.

Comparative effects of captopril and nifedipine on split renal function in renovascular hypertension

Comparative effects of angiotensin-converting enzyme inhibitor (ACEI) captopril and calcium entry blocker nifedipine on the split renal function were studied in six patients with renovascular hypertension (RVH) with unilateral stenosis (38 +/- 5 years). Both captopril and nifedipine showed potent antihypertensive effects; the mean arterial pressure was reduced from 131 +/- 16 to 105 +/- 8 mm Hg (P less than 0.001) by captopril, and from 128 +/- 15 to 109 +/- 11 mm Hg (P less than 0.001) by nifedipine. The glomerular filtration rate (GFR) in the stenotic kidney was 24 +/- 6 mL/min, which decreased to 11 +/- 2 mL/min (P less than 0.01) during captopril administration, and only slightly decreased (18.8 +/- 5 mL/min) during nifedipine administration. The effective renal plasma flow (ERPF) increased in the nonstenotic kidneys in response to both drugs. These results show that angiotensin II rather than renal perfusion pressure may be important for maintaining GFR in the stenotic kidney, and further suggest that nifedipine may be used relatively safely in treating patients with RVH, although caution should be exercised in terms of their ability to preserve the renal function in individual kidneys.

Effect of metoclopramide on orthostatic hypotension in diabetes mellitus: failure to demonstrate the role of vasoconstrictive hormones

Effect of metoclopramide (MCP), a dopaminergic antagonist, on orthostatic hypotension associated with diabetes mellitus, was investigated to prove its plausible role of renin-angiotensin-aldosterone and catecholamine activation by comparative study in 6 diabetics with orthostatic hypotension (OH) and 9 diabetics without OH. With MCP treatment, drop of systolic blood pressure (SBP) on standing was significantly improved. However, the postural responses of plasma renin activity (PRA), plasma aldosterone and norepinephrine were not enhanced by MCP treatment. Moreover, MCP treatment did not modify the vascular reactivity to the exogenously infused angiotensin II and norepinephrine. Thus, it would be interesting to speculate that MCP can improve SBP through its suppressive effect on some depressor substance(s) such as bradykinin which liberates exaggeratively in diabetic OH.

Effects of a calcium entry blocker on cerebral circulation in essential hypertension

The acute effects of the calcium entry blocker, nifedipine, on cerebral circulation were studied in 22 patients (56 +/- 5 years) with essential hypertension (EHT, WHO I-II) and 12 age-matched normal subjects. Cerebral effects were reevaluated in sixteen EHT patients after 8 weeks of treatment. The cerebrovascular resistance (Rp), cerebral capacitance (Cp), carotid velocity, and flow volume were measured by a newly developed ultrasonic volume flow meter coupled with a built-in computer which calculates Rp and Cp based on a simulated model. In EHT, acute administration of nifedipine (10 mg orally) decreased Rp from 13.5 +/- 1.8 to 8.0 +/- 0.3 (p less than 0.01) and increased Cp from 22.8 +/- 3.3 to 54.9 +/- 5.2 mFc (p less than 0.01). The carotid blood flow and velocity increased by 25.7% and 22.9%, respectively (p less than 0.05) in the face of lowered arterial pressure. In normal subjects, nifedipine also decreased Rp and increased Cp but to a lesser degree compared with EHT. The acute changes in cerebrovascular circulation in EHT were maintained at 8 weeks of treatment. These results suggest that nifedipine reduces Rp, possibly as the consequence of systemic hypotension and direct vasodilation of the cerebral arteries. This may be beneficial for hypertensive patients.

Effects of corticotropin-releasing factor (CRF) on aldosterone and 18-hydroxycorticosterone in essential hypertension and primary aldosteronism

The effects of ovine corticotropin releasing factor (o-CRF) on plasma aldosterone, 18-OH-corticosterone (18-OHB), plasma adrenocorticotropin (ACTH) and cortisol were determined in eight patients with primary aldosteronism, six with aldosterone-producing adenoma (APA) and two with idiopathic hyperaldosteronism (IHA). The results were compared with those in six normal subjects and eleven patients with essential hypertension (EHT, 5 with low renin and 6 with normal renin). In patients with APA, the peak plasma aldosterone and 18-OHB responses to 100 micrograms iv of o-CRF (226% and 113% increase from baseline, respectively) were greater than those in EHT and normal subjects. The net integrated aldosterone and 18-OHB responses (840 +/- 156, and 419 +/- 121 ng/dl.hr, respectively) were also significantly greater (p less than 0.01) in APA than those in normals and EHT. In two patients with IHA, both the peak and net integrated aldosterone response were smaller than those in APA, in spite of nearly identical plasma ACTH and cortisol responses. These results suggest that augmented responses of mineralocorticoids to o-CRF may be characteristic of aldosteronism due to APA, mediated by CRF-induced ACTH, and possibly other proopiomelanocortin (POMC)-derived peptides.

The renal, cardiovascular and hormonal actions of human atrial natriuretic peptide in man; effects of indomethacin

The renal, cardiovascular and hormonal effects of intravenous infusion of alpha-human atrial natriuretic polypeptides (alpha-hANP) at the concentrations of 0.0125, 0.025, 0.05, 0.1 microgram kg-1 min-1 for 20 min was studied in six male volunteers before and after indomethacin administration (150 mg day-1, three times daily for 3 days). Dose-dependent diuresis and natriuresis were observed in all subjects between the concentrations of 0.025 and 0.1 microgram kg-1 min-1, which were not influenced by indomethacin. Diastolic blood pressure decreased significantly (P less than 0.05) at the higher dose (0.05 microgram kg-1 min-1) of alpha-hANP, which was attenuated by indomethacin pretreatment. The plasma concentration of the immunoreactive alpha-hANP was 73.7 +/- 25 pg ml-1 on the control in subjects taking 200 mEq day-1 of sodium, and significant diuresis occurred when plasma concentration reached approximately 330.5 +/- 74.4 pg ml-1. alpha-hANP infusion caused a dose-dependent increase in cyclic GMP, no significant changes in plasma aldosterone and 18-hydroxycorticosterone, which were not influenced by indomethacin pretreatment. Plasma renin did not change in response to alpha-hANP infusion, which was significantly decreased (P less than 0.05) after indomethacin pretreatment. These results support that the renal effects of alpha-hANP may be exerted by prostaglandin-independent mechanisms. The renal effects occur at lower doses, and cardiovascular changes occur at higher doses of alpha-hANP.

Long-term effects of converting enzyme inhibitors on split renal function in renovascular hypertension

Long-term effects of angiotensin converting enzyme inhibitors on split renal function were studied using a noninvasive radioisotopic method in five patients with renovascular hypertension. In the stenotic side the glomerular filtration rate which acutely decreased following captopril, tended to return toward pretreatment levels on prolonged captopril administration (up to 2 years), while the value remained unchanged in the nonstenotic side of the kidney. Effective renal plasma flow increased in both sides. During long-term captopril treatment, there were no significant changes in serum creatinine, sodium, potassium, and blood pressure control was maintained at the same level in an acute period. These results suggest that the glomerular filtration in the stenotic kidney of renovascular hypertension, which was acutely reduced, will not further deteriorate, but will increase after prolonged captopril treatment.

Role of bradykinin for orthostatic hypotension in diabetes mellitus

A possible contribution of circulating kinin for orthostatic hypotension (OH) in diabetic patients was investigated using a sensitive RIA of plasma bradykinin (BK). Thirty six diabetics underwent 10 min of orthostasis, in which 20 patients developed OH. The baseline plasma BK was 15.8 +/- 1.8 pg/ml in diabetics with OH, which increased to 31.0 +/- 5.6 pg/ml (p less than 0.05). The basal plasma BK was 19.4 +/- 4.1 and 17.8 +/- 2.3 pg/ml in normal subjects (n = 10) and in diabetics without OH (n = 16), respectively. These values were not significantly different from the diabetics with OH. In response to standing there were no significant changes in plasma BK in both groups. There was a significant correlation between the absolute increment of plasma BK and the decrement of systolic blood pressure (BP) when all diabetic patients were compared (r = -0.364, p less than 0.05). The baseline PRA and plasma norepinephrine (NE) were similar in normal subjects and diabetics with or without OH. In response to standing there were approximately two-fold increases in PRA and plasma NE. There was no significant correlation between plasma NE increment and the fall in systolic BP. These results suggest that kinins may participate in OH in diabetic patients.

Effect of 9 alpha-fluorocortisol on the excretion of urinary digoxin-like substance in normotensive men

In order to investigate the possible role of mineralocorticoid in the regulation of digoxin-like substance (DLS), 9 alpha-fluorocortisol (9-F) was administered to 6 healthy men and urinary excretion of DLS was measured. The administration of 0.6 mg of 9-F caused slight increases in body weight and blood pressure and significant decreases in urinary Na excretion, plasma renin activity and plasma aldosterone, which indicate the expansion of extracellular fluid (ECF) volume by 9-F administration. Urinary excretion of DLS decreased significantly from the baseline level of 43.3 +/- 2.6 (SEM) to 29.8 +/- 5.1 (SEM) ng/day; digoxin equiv. after 9-F. These results suggest that a large dose of mineralocorticoid may suppress DLS despite an increase in the ECF volume.

Effects of converting enzyme inhibition on split renal function in renovascular hypertension

The effects of captopril on effective renal plasma flow and glomerular filtration rate were studied using a noninvasive radioisotopic method on individual kidneys in eight patients with renovascular hypertension and 12 patients with essential hypertension with various renin levels. Four patients with renovascular hypertension had unilateral while three had bilateral renal artery stenosis. The effective renal plasma flow and glomerular filtration rate were determined by using 131I-iodohippurate sodium and 99mTc-diethylenetriamine pentaacetic acid, respectively. Glomerular filtration rate and effective renal plasma flow were significantly reduced in the stenotic kidneys of patients with renovascular hypertension compared with values in nonstenotic kidneys (p less than 0.01). Treatment with captopril, 37.5 to 75 mg/day for 1 to 48 weeks, further reduced the glomerular filtration rate only in stenotic kidneys, and effective renal plasma flow increased in both kidney types. In two of the three renal hypertensive patients with bilateral renal artery stenosis, captopril produced a reversible azotemia that was unrelated to the fall in blood pressure, as evidenced by the lack of azotemia seen after a moderate blood pressure reduction induced by other antihypertensive medications. These results indicate that endogenous angiotensin II is essential in maintaining the glomerular filtration rate in stenotic kidneys and suggest that a reduction in glomerular filtration rate during captopril administration could indicate the presence of renal artery stenosis.

[Responses of plasma bradykinin and the renin angiotensin axis to angiotensin II in hyperthyroid patients]

The present investigation was undertaken to elucidate the possible interplay between the circulating kinin(s) and the renin angiotensin axis in hyperthyroidism. The responsiveness of plasma aldosterone (p-Ald), kinin (p-BK), plasma renin activity (PRA) and serum angiotensin converting enzyme activity (ACEA) to infusion of angiotensin II at a dose of 4, 8 and 16 ng/kg.min. was asessed in 15 hyperthyroid patients and 10 euthyroid controls. There was impaired angiotensin II induced response of blood pressure in hyperthyroid patients, and basal concentrations of p-Ald were 7.7 +/- 3.8 ng/dl in euthyroid controls and 12.6 +/- 3.1 ng/dl in hyperthyroid patients (p less than 0.05). As compared to the euthyroid controls, the hyperthyroid patients showed a reduced response of plasma aldosterone to angiotensin II infusion. Angiotensin II infusion increased p-BK from basal levels of 19.1 +/- 8.2 pg/ml to 31.0 +/- 7.8 pg/ml (p less than 0.05) only in hyperthyroid patients and did not increase ACEA in either group. Next, the effects of a single administration of captopril (50 mg p.o.) on blood pressure and p-BK in hyperthyroid patients and euthyroid controls were studied. In the two groups blood pressure was not changed by captopril, but p-BK increased significantly. The present results do not support the view that there may be a direct linkage between the kallikrein kinin system and the renin angiotensin axis mediated by kininase II or angiotensin converting enzyme in human peripheral blood. Also it is unlikely that kinin may play a role in the mechanism of reduced responsiveness of aldosterone and blood pressure to angiotensin II in hyperthyroidism.

Single-blind study of epoprostenol and 6-keto-prostaglandin E1 in man: effects of platelet aggregation and plasma renin

The effects of epoprostenol (PGI2, 2-8 ng kg-1 min-1) and 6-keto-prostaglandin E1 (6-keto-PGE1, 7.5-30 ng kg-1 min-1) on ADP-induced platelet aggregation, blood pressure (BP), heart rate and plasma renin activity (PRA) were studied in six healthy male volunteers. During graded intravenous administration of PGI2, platelet aggregation was inhibited at a minimum dose of 4 ng kg-1 min-1. The dose required to produce the same degree of platelet inhibition was approximately 15 ng kg-1 min-1 for 6-keto-PGE1. Diastolic BP was significantly reduced and PRA was increased by PGI2 at a dose greater than 8 ng kg-1 min-1. In contrast, 6-keto-PGE1 did not produce BP and PRA changes up to a dose of 30 ng kg-1 min-1. These data indicate that PGI2 has approximately four times more potent antiplatelet activity than 6-keto-PGE1 on a molar basis in man. The cardiovascular and PRA changes were less prominent for 6-keto-PGE1 than PGI2.

Effect of sodium intake on the excretion of urinary natriuretic factor in essential hypertensives

A simplified method for the determination of natriuretic factor in the urine as measured by digoxin-like substance was studied. Digoxin-like substance in the urine was estimated by RIA using anti-digoxin antibody after being extracted by reversed phase cartridge column but without gel filtration. The values found by radioimmunoassay (RIA) yielded a significant correlation with those of the inhibitory effect of Na-K-ATPase activity which was measured by biochemical assay as described by Hamlyn et al. Using this RIA method, the effect of salt intake on natriuretic factor in urine was studied in patients with essential hypertension. The natriuretic factor on a high sodium diet (NaCl 20 g/day for three days) increased approximately 1.5 times, as compared to those on a low sodium diet (NaCl 3 g/day) (p less than 0.05). The Natriuretic factor showed a positive correlation with urinary Na excretion (P less than 0.050) when the patients were placed on ad. lib. sodium diet. From these results, it is suggested that secretion of natriuretic factor in the urine might be regulated in part by salt intake.

Participation of vascular prostacyclin for the pathogenesis of experimental glucocorticoid hypertension in rats

Prostacyclin (PGI2) generation in the mesenteric arteries from dexamethasone acetate (DX) and deoxycorticosterone acetate (DOCA) treated rats was assessed by ex vivo perfusion method. PGI2 generation which was measured by 6-keto-PGF1 alpha output in the perfusate was significantly reduced in DX treated rats at prehypertensive stage both under the basal conditions and in response to angiotensin (ANG) II, whereas in DOCA group rats, vascular PGI2 production was not impaired. Plasma renin activity (PRA) was significantly suppressed in DOCA but normal in DX rats. These results suggest that the reduced PGI2 generation in the resistance arteries may contribute to the development of hypertension induced by DX.

[The role of prostaglandins for norepinephrine clearance in borderline hypertension]

Studies were done to determine the role of endogenous prostaglandins (PGs) for norepinephrine (NE) clearance in 10 male borderline hypertensives (BHT) (age: 20-28) and six age-matched male normotensives (NT). Two experimental protocols were followed in these subjects: 10 min orthostasis with blood sampling (protocol I), and 100 ng/kg/min of L-NE infusion for 60 min at supine position. Blood was collected from indwelling catheter at every min for 10 min after stopping the NE infusion (protocol II). Plasma NE was measured by THI method using HPLC. Disappearance curve of plasma NE was analyzed following the two compartment open model. The orthostasis and the steady state NE infusion were repeated after 150 mg/day of indomethacin (Ind) for three days. There were significant increases in plasma NE after orthostasis in both groups: from 180.8 +/- 28.0 pg/ml to 346.2 +/- 78.0 pg/ml (p less than 0.05) in NT and from 120.1 +/- 12.8 pg/ml to 289.6 +/- 20.3 pg/ml (p less than 0.001) in BHT, but there were no significant differences between the two groups. Ind pretreatment did not alter these responses. The calculated half-time of the first exponential phase (T 1/2) was 1.50 +/- 0.07 min in NT which decreased to 0.98 +/- 0.10 min (p less than 0.05) after Ind pretreatment. In BHT, T 1/2 was 1.03 +/- 0.08 min (p less than 0.01 vs NT), which was not significantly changed after Ind. These results may suggest that endogenous PGs have some role(s) in NT for NE clearance, probably exerting inhibitory action on neuronal uptake. In BHT, neuronal uptake of NE is increased, probably due to an adaptation mechanism to elevated blood pressure.

Role of prostacyclin in blood pressure regulation and aldosterone production in conscious rabbits

The effects of subdepressor infusion of prostacyclin (PGI2, 5.3 pmol min-1 kg-1) on arterial pressure and aldosterone production induced by angiotensin II (ANG II) were studied in conscious rabbits. Indomethacin pretreatment caused an augmented blood pressure response after ANG II infusion, which returned to near control level after concomitant infusion of a subdepressor dose of PGI2. Aldosterone production after ANG II was significantly attenuated after pretreatment with indomethacin. PGI2 infusion restored this reduced response to near control level. These results may suggest that PGI2 in the circulation could also serve to modulate the pressor and hormonal action(s) of ANG II.

Circadian rhythm of plasma aldosterone and time dependent alterations of aldosterone regulators

In order to investigate the relative contribution of ACTH, the renin angiotensin and dopaminergic system to the circadian rhythm of plasma aldosterone, hormone levels were determined at hourly intervals over a 24 h span in four supine healthy men. Blood was withdrawn under basal conditions (control), after either dexamethasone, captopril or bromocriptine++ (CB-154) administration. Plasma aldosterone rhythmicity was abolished in dexamethasone treated groups but not in captopril or CB treated groups. Time dependent alterations of aldosterone regulators were analyzed by multiple regression methods at 3 hourly intervals. These results indicate that plasma aldosterone rhythmicity is predominantly under the control of ACTH whereas the renin angiotensin or dopaminergic system plays a little role. In supine, sodium repleted states, ACTH is a potent stimulus of aldosterone at 000-0600 h and 1700-1900 h clocktime, whereas during daytime renin-angiotensin is an additional regulator.

Spontaneous remission of cranial diabetes insipidus due to concomitant development of ADH-producing lung cancer--an autopsied case

The very rare occurrence of an ADH-producing small cell carcinoma of the lung in a 52 year old male patient with cranial diabetes insipidus since childhood is described. In this case diabetes insipidus disappeared concomitantly with development of lung cancer and re-appeared with shrinkage of the lung tumour by radiation therapy. Further progressive expansion of the primary and metastatic tumours induced the syndrome of inappropriate ADH secretion once again (SIADH). This deterioration in the clinical course was reflected in the plasma levels of ADH and neurophysins. The existence of vasopressin in the tumour tissue was also demonstrated by means of an immunohistochemical staining technique combined with anti-vasopressin serum.

Effect of sodium intake on prostacyclin generation in rabbit mesenteric artery

Effect of sodium intake on prostacyclin (PGI2) generation in response to angiotensin II (A II) or noradrenaline (NA) stimulation was studied using the rabbit mesenteric artery (RMA) perfusion system. 6-oxo-PGF1 alpha, a stable metabolite of PGI2, was continuously released into the effluent at a rate of 10.7 +/- 2.2 ng/min for the initial 60 min. Perfusion pressure and 6-oxo-PGF1 alpha promptly increased in response to A II and NA. Chronic sodium loading caused a significantly (p less than 0.05) smaller PGI2 production following the A II stimulation. Vasoconstrictive responses induced by these stimuli were greater in the high sodium group. Acute changes in potassium concentration at a range between 1.2 and 5.4 mEq/L failed to affect basal PGI2 production, but an augmented response of PGI2 release by A II and NA was observed at the lowest potassium concentration. These results may suggest that vascular prostaglandins may participate in the mechanism of an altered vascular responsiveness during an altered sodium or potassium homeostasis.