Gender-related penetrance and de novo GTP-cyclohydrolase I gene mutations in dopa-responsive dystonia

We evaluated the influence of gender on penetrance of GTP-cyclohydrolase I (GCH) gene mutations in hereditary progressive dystonia/dopa-responsive dystonia (HPD/DRD) and determined whether some apparently sporadic HPD/DRD patients owe their disorder to a de novo mutation of the GCH gene. Previous clinical investigations of HPD/DRD have shown a predominance of affected women, with approximately half of HPD/DRD patients being sporadic. We conducted genomic DNA sequencing of the GCH gene in five HPD/DRD families having at least two generations of affected members and in four apparently sporadic cases and all of their parents. In the nine HPD/DRD pedigrees, we found independent mutations of the GCH gene (five deletions, one insertion, one nonsense mutation, and two point mutations at splice acceptor sites). The female-to-male ratio of the HPD/DRD patients was 4.3 with the penetrance of GCH gene mutations in women being 2.3 times higher than that in men (87% versus 38%, p = 0.026). There was no significant difference in the penetrance between maternally and paternally transmitted offspring. All of the four sporadic cases had de novo mutations because none of their parents were carriers. The results demonstrate gender-related incomplete penetrance of GCH gene mutations in HPD/DRD and suggest that this may not be due to genomic imprinting. Our data also suggest a relatively high spontaneous mutation rate of the GCH gene in this autosomal dominant disorder.

[Repair of intrathoracic visceral damage using video-assisted thoracoscopic surgery for blunt chest trauma and rib fixation at the site of mini-thoracotomy]

We treated three patients with intrathoracic visceral damage caused by severely dislocated fractured ribs resulting from blunt trauma by using video-assisted thoracoscopic surgery (VATS) and rib fixation through a mini-thoracotomy. Under general anesthesia and unilateral respiration, the thoracic cavity was inspected with a thoracic video scope through the port inserted through the thoracic drainage opening which was made upon arrival at hospital. As the visceral damage seemed restorable under VATS, a mini-thoracotomy was positioned just above the rib fracture. Two thoracic ports were inserted through the site of rib fracture or through the intercostal space and then VATS was performed using three ports. After the restoration of intrathoracic visceral damage, the fractured rib was fixated using a bioabsorbable poly-L-lactide rib fixation pin or a marlex mesh. Lung injuries were sutured and ligated under VATS in two of our cases and a spur of the fractured rib was shaved in one case. Only severely dislocated ribs were fixated through the mini-thoracotomy in all cases. Air leakage stopped just after this procedure and there were no complications. The rib fixation and bone regeneration were excellent after this procedure. The advantages of this method are the visceral restoration under VATS through a mini-thoracotomy and the ability to perform rib fixation without injuries to the intercostal muscle, artery, vein or nerve. This operative procedure is recommended for intrathoracic visceral damage caused by severely dislocated rib fracture.

Role of endogenous nitric oxide in the brain stem on the rapid adaptation of baroreflex

It has been shown that nitric oxide in the brain stem plays an important role in the control of sympathetic nerve activity. We examined the role of endogenous nitric oxide in the brain stem in the rapid central adaptation of baroreflex control of sympathetic nerve activity in anesthetized rabbits. Bilateral carotid sinuses were isolated, and a stepwise increase in pressure of 25 or 50 mm Hg for 50 to 60 seconds was applied to the carotid sinuses while the arterial pressure and renal sympathetic nerve activity were recorded. The renal sympathetic nerve activity was inhibited by the stepwise increase in carotid sinus pressure, but thereafter it gradually returned toward the baseline level despite the fact that carotid sinus pressure was kept constant. This procedure was performed after intracisternal injection of N(omega)-nitro-L-arginine methyl ester (L-NAME, 8 micromol), N(omega)-nitro-D-arginine methyl ester (D-NAME, 8 micromol), L-arginine (40 micromol), or the vehicle solution. The magnitude of the immediate and maximal inhibition of renal sympathetic nerve activity caused by a stepwise increase in carotid sinus pressure was similar between the vehicle and L-NAME treatment, but the rate of recovery of the renal sympathetic nerve activity after immediate inhibition was faster after L-NAME than after vehicle. L-Arginine reversed the effects of L-NAME. However, D-NAME or L-arginine alone had no such effects on the rate of recovery of the nerve activity. These results thus suggest that endogenous nitric oxide in the brain stem attenuates rapid adaptation of the arterial baroreflex control of the sympathetic nerve activity in rabbits.

Cyst-like lesion of a developing tooth induced by mandibular fracture

A dentigerous cyst-like formation in the lower canine region caused by mandibular fracture in a 10-year-old boy is reported. His medical history revealed that he had been unconscious for about 2 weeks after traumatic head injuries sustained in a traffic accident, and a complicated mandibular fracture had been left untreated until his dentist diagnosed the lesion. Eleven months after trauma, a dentigerous cyst measuring 20 mm in diameter was found in the fracture area. The lesion was enucleated and the boy's postoperative recovery was uneventful. The mass completely enveloped the developing canine, and epithelial cells proliferated into the connective tissue. However, there was no distinct epithelial lining. Small round cell infiltrations and several vessels with thrombosis were noted in the cyst wall. The cause of cyst formation was considered to be infection of the canine tooth bud and the surrounding soft tissue.

Short-term estrogen augments both nitric oxide-mediated and non-nitric oxide-mediated endothelium-dependent forearm vasodilation in postmenopausal women

Estrogen is known to improve in the short term the impaired endothelium-dependent vasodilating responses in postmenopausal women, which may account in part for the beneficial cardiovascular effects of the female hormone. Endothelium-dependent vasodilation is achieved by combined effects of endothelium-derived prostacyclin, nitric oxide (NO), and hyperpolarizing factor. In this study, we investigated our hypothesis that short-term estrogen improves both NO-mediated and non-NO-mediated endothelium-dependent vasodilation in postmenopausal women. The study included 12 postmenopausal women (aged 64 +/- 3 years). The forearm blood flow was measured by strain-gauge plethysmography. The forearm vascular responses to the endothelium-dependent vasodilators, acetylcholine and substance P, were examined before and after intravenous administration of conjugated estrogen and subsequently after intraarterial infusion of NG-monomethyl-L-arginine (L-NMMA), an inhibitor of NO synthesis. Short-term estrogen augmented the forearm vasodilating responses to both acetylcholine and substance P. The treatment with L-NMMA almost abolished the augmented response to acetylcholine but did not affect that to substance P. The forearm vascular response to sodium nitroprusside was unchanged by the estrogen administration. These results indicate that estrogen augments (in the short-term) both NO-mediated and non-NO-mediated endothelium-dependent forearm vasodilation in postmenopausal women. Thus the beneficial effect of estrogen on endothelial vasodilator function appears to extend to non-NO-dependent mechanism(s).

Zonisamide monotherapy in newly diagnosed infantile spasms

PURPOSE

We determined the short-term efficacy of zonisamide (ZNS) monotherapy in newly diagnosed patients with infantile spasms (IS).

METHODS

Eleven hospitals participated in this open, prospective trial. ZNS 3-10 mg/kg/day was administered as the second-choice drug to 11 newly diagnosed patients with IS (cryptogenic 3, symptomatic 8) who failed to respond to high-dose vitamin B6.

RESULTS

Four infants with symptomatic IS had cessation of spasms and disappearance of the hypsarrhythmia. In these responders, the spasms ceased after a few days (1-5 days) of treatment at a dose of ZNS 4-5 mg/kg/day which produced plasma ZNS concentrations ranging from 5.2 to 16.3 microg/ml (mean 9.8 microg/ml). There were two relapses (50%) 4-6 weeks after cessation of seizures, however. Relapse was predicted by effects of ZNS on EEG; the 2 infants in whom an abnormal EEG persisted had relapses, whereas the 2 whose EEG normalized remained seizure-free (follow-up 20 and 26 months). No adverse reactions were noted.

CONCLUSIONS

ZNS may be effective in the initial treatment of selected patients with IS.

Hypomelanosis of Ito associated with hemimegalencephaly: a clinicopathological study

A girl with hypomelanosis of Ito was studied both clinically and at postmortem examination. She manifested severe epilepsy early after birth. Magnetic resonance imaging demonstrated left-sided hemimegalencephaly. The seizures were secondarily generalized or unilateral initially, followed by infantile spasms with asymmetrical hypsarrhythmia at 1.5 months of age. Frequent complex partial seizures, refractory to anti-epileptic drug treatments appeared at 4 months of age. She died of pneumonia at the age of 14 months. Postmortem examination revealed marked asymmetry of the cerebrum and gyral abnormalities in the left cerebral hemisphere. Histopathologically, severe disorganization of the neuronal cytoarchitecture was evident. Absence of delineation between cortical gray and white matter was evident, as was increase and hypertrophy of the neurons and glial cells. We believe that the association of skin and brain lesions was not one of chance; that is, they may share a common pathogenetic mechanism.

Immunoliposomes bearing polyethyleneglycol-coupled Fab' fragment show prolonged circulation time and high extravasation into targeted solid tumors in vivo

We have developed a new type of long-circulating immunoliposome (Fab'-PEG immunoliposomes) which is efficiently extravasated into the targeted solid tumor in vivo. Small unilamellar liposomes (100-130 nm in diameter) were prepared from distearoylphosphatidylcholine (DSPC), cholesterol (CHOL) and a dipalmitoylphosphatidylethanolamine derivative of PEG with a terminal maleimidyl group (DPPE-PEG-Mal), and conjugated Fab' fragment of antibody. Inclusion of DPPE-PEG-Mal and linkage of the Fab' fragment instead of intact antibody to PEG terminals allowed the liposomes to evade RES uptake and remain in the circulation for a long time, resulting in enhanced accumulation of the liposomes in the solid tumor. Because of the ability of such Fab'-PEG immunoliposomes to target solid tumors, they appear highly attractive as carriers of not only chemotherapeutic agents, but also of macromolecular drugs.

[Esophago-bronchial fistula which developed after the insertion of an expandable metallic stent for corrosive esophageal stenosis]

A 69-year-old man attempted suicide by abdominal penetrating injury and taking sulfonyl acid. After a laparotomic drainage operation, corrosive esophageal stenosis occurred. Esophageal bougienage was not effective. An expandable metallic stent (GIANTURCO-ROCHE Z stent, Cook Bloomington U.S.A.) was inserted aiming to achieve temporary oral diet and nutritional improvement. But diet did not improve sufficiently because of the awareness of the prosthesis, severe hiccup, uncontrolled regurgitation esophagitis and restenosis caused by intraluminal mucosal growth. After 4 months of insertion, an esophago-bronchial fistula was produced by the wire of EMS. An operation became necessary for this complication. No data exist on the long-term use of the EMS and it is not suitable for benign esophageal stenosis. Unavoidably if the palliative treatment of endoprosthesis is necessary for benign esophageal stenosis such as corrosive esophageal stenosis, a removable esophageal tube prosthesis is preferable.

Basal release of nitric oxide is decreased in the coronary circulation in patients with heart failure

It is unknown whether basal release of endothelium-derived nitric oxide in the coronary artery is altered in heart failure in humans. The aim of the present study was to evaluate the effect of inhibition of nitric oxide synthesis on basal tone of the conduit and resistance coronary arteries in awake patients. Coronary blood flow velocity (Doppler guide wire) and coronary arterial diameter (quantitative coronary angiography) were measured in 14 patients with heart failure caused by nonischemic left ventricular dysfunction (7 idiopathic dilated cardiomyopathy and 7 valvular insufficiency) and 7 patients with normal ventricular function (controls). Intracoronary N(G)-monomethyl-L-arginine (L-NMMA), an inhibitor of nitric oxide synthesis, at graded doses decreased coronary blood flow in both groups. However, the magnitude of flow reduction was smaller in patients with heart failure than in control patients (P<.0001). The magnitude of coronary blood flow reduction in response to L-NMMA inversely correlated to indexes of left ventricular contractile function (P<.01) but was not affected by the cause of heart failure. Constriction of the large epicardial coronary artery with L-NMMA also tended to be attenuated in patients with heart failure. In summary, vasoconstricting response to L-NMMA was blunted in the coronary resistance artery in heart failure in vivo. These findings suggest that basal release of nitric oxide in the coronary circulation is decreased in patients with heart failure.

Bradykinin-induced vasodilation of human coronary arteries in vivo: role of nitric oxide and angiotensin-converting enzyme

OBJECTIVES

The present study aimed to determine the role of nitric oxide (NO) and angiotensin-converting enzyme (ACE) in bradykinin (BK)-induced dilation of human coronary arteries in vivo.

BACKGROUND

BK, produced by way of the kinin-kallikrein system, causes endothelium-dependent vasodilation. However, little is known about the mechanism of BK-induced dilation of coronary arteries in humans in vivo.

METHODS

The effects of an inhibitor of NO synthesis and of an ACE inhibitor on BK-induced coronary vasodilation were examined in 20 patients who had no significant atherosclerotic stenosis in the artery under study. Lumen diameters of the large epicardial coronary arteries and coronary blood flow (CBF) were measured by quantitative coronary arteriography and intracoronary Doppler technique.

RESULTS

Intracoronary infusion of BK (0.6 and 2.0 micrograms/min) increased coronary artery diameter and CBF with no change in arterial pressure or heart rate. The BK-induced increases in coronary artery diameter and CBF were significantly reduced (p < 0.01) after pretreatment with NG-monomethyl-L-arginine (200 mumol) and were significantly increased (p < 0.01) after pretreatment with enalaprilat (50 micrograms).

CONCLUSIONS

BK-induced dilation of human large epicardial and resistance coronary arteries is mediated by NO and increased by prior ACE inhibition.

Pure red cell aplasia during carbamazepine monotherapy

A 7-year-old girl developed pure red cell aplasia during carbamazepine (CBZ) monotherapy for epilepsy. She developed generalized clonic convulsions at the age of 7 years and 8 months. Treatment with CBZ was begun. Two months later she was admitted to our hospital because of severe anemia. Bone marrow examination revealed the almost complete absence of erythroblasts, with normal myelopoiesis and megakaryocytopoiesis, indicating pure red cell aplasia. Following the discontinuation of CBZ, she developed brisk reticulocytosis within 1 week and her hemoglobin level rose to a normal one within 1 month. Although the hematological toxicity of CBZ is well documented, isolated cessation of red cell production is uncommon. A patient who is undergoing treatment with CBZ should be carefully monitored, especially for serious adverse reactions including pure red cell aplasia.

Role of nitric oxide in substance P-induced vasodilation differs between the coronary and forearm circulation in humans

It has been shown that substance P causes endothelium-dependent vasodilation in the human coronary and forearm vessels. However, the precise mechanism whereby substance P dilates the coronary and peripheral vasculatures is unknown in humans. The aim of this study was to examine whether the vasodilator effect of substance P is mediated by nitric oxide in the human coronary and forearm vessels. Eight patients with normal coronary angiograms were studied for the measurements of coronary blood flow (intracoronary Doppler guide wire and quantitative coronary arteriography) and forearm blood flow (strain-gauge plethysmograph). Intracoronary acetylcholine (10 micrograms/min for 2 min) and substance P (30 and 90 ng/min for 2 min) increased coronary blood flow from the baseline value. Intracoronary infusion of NG-monomethyl-L-arginine (L-NMMA) at 200 mumol significantly attenuated the magnitudes of increase in coronary blood flow induced by both acetylcholine (p < 0.01) and substance P (p < 0.01). Acetylcholine (4, 8, and 16 micrograms/min for 2 min) and substance P (0.8, 1.6, and 3.2 ng/min for 2 min) also increased forearm blood flow in a dose-dependent manner. Intraarterial L-NMMA (8 mumol/min for 5 min) decreased the magnitudes of increase in forearm blood flow induced by acetylcholine (p < 0.01). L-NMMA at the same dosage decreased the increase in forearm blood flow induced by substance P, but the magnitude of the inhibitory effect of L-NMMA on blood-flow responses to substance P was significantly smaller in the forearm than in coronary vessels. It is suggested that endothelium-derived nitric oxide contributes to substance P-induced vasodilation, and that the contribution of nitric oxide to substance P-induced vasodilation is smaller in the forearm than in coronary circulation.

Ekman-Westborg-Julin syndrome. A case report

A rare case of the Ekman-Westborg-Julin syndrome in a 15-year-old boy is presented. The patient had general macrodontia with gigantic mandibular third molars. Other dental anomalies, such as peak-shaped cuspids, central cusps, dens in dente, multituberculism, and single conical molar roots, were also present.

Graft damage after a single lung transplantation for pulmonary hypertension in a rat model

The hemodynamic effect and degree of damage in grafts of single lung transplants for pulmonary hypertension were studied in rats with monocrotaline-induced pulmonary hypertension. Inbred male Lewis rats (weight 200-230 g) were divided into two groups. Group 1 (control group, n = 16) underwent isogenic left lung transplantation, while group 2 (n = 15) received an intravenous administration of monocrotaline (80 mg/kg i.v.) and underwent isogenic left single lung transplantation 3 week later. Hemodynamic evaluations were performed prior to transplantation, at 1 h postoperatively, and on days 3 and 7 after transplantation. Mean pulmonary arterial pressure (mPAP) rapidly declined after transplantation in group 2, from 39.3 +/- 8.7 mmHg to 18.5 +/- 3.0 mmHg 1 h after transplantation, and remained stable on day 7 after transplantation. No significant difference in the mPAP between the two groups was observed after transplantation. The extravascular lung water volume (ELWV: dry/wet ratio) in the right lung of group 2 significantly increased on day 3 (0.86 +/- 0.02) (P < 0.01), and subsequently decreased to control levels on day 7 (0.83 +/- 0.02). There was no significant difference in the ELWV in the grafted lungs between the two groups (0.84 +/- 0.03 vs 0.86 +/- 0.04), but there was tendency toward an increase in ELWV in group 2 on days 3 and 7. These data thus demonstrated that a hemodynamic improvement was obtained by single lung transplantation; however the degree of graft damage was remarkable in the pulmonary hypertension group.

Kinky hair disease with multiple eruption cysts: a case report

A rare case of kinky hair disease with multiple eruption cysts is described. Dental abnormalities include eruption cysts, delayed tooth eruption, prognathia, open bite, generalized gingival swelling, and high arched palate.

Adenomatoid serous hyperplasia of sublingual gland: a case report

We present an example of adenomatoid serous lobular hyperplasia of the sublingual gland. Pathologic examination revealed the lesion was composed of multiple aggregates of normal-appearing serous and mucous acini that varied in size. The ratio of serous gland to mucous glands was 7 to 1. We cannot identify the cause of this condition, however, calcium channel blocking agents prescribed for the treatment of this patient's essential hypertension cannot be ruled out as a pathogenetic factor in the development of the lesion.

[SPECT, MRI and EEG in infants with lissencephaly]

Single photon emission tomography (SPECT), MRI and EEG were studied in two infants with lissencephaly. One infant had generalized tonic convulsions at 7 month of age and continuous high voltage fast activities on EEG. The other infant developed infantile spasms at the age of 2.5 months, and showed low voltage disorganized background with pseudorhythmic high voltage sharp waves on EEG. Cranial CT and MRI in both infants revealed abnormally thick cortex, dilatation of the lateral ventricles, and smooth or relatively smooth cerebral surface. In SPECT studies, a diffuse increase of tracer uptake was shown at the cerebral cortex compared with the basal ganglia or cerebellum in both infants. The SPECT finding might reflect the abnormal cortical architectures in this cerebral malformation.

Role of endothelium-derived nitric oxide in coronary vasodilatation induced by pacing tachycardia in humans

Endothelium-derived NO contributes to the control of coronary perfusion. We investigated the roles of NO in the metabolic coronary vasodilatation induced by rapid pacing in humans. We evaluated the dilatation of large epicardial and resistance coronary arteries during rapid atrial pacing before and after intracoronary infusion of NG-monomethyl-L-arginine (L-NMMA), an inhibitor of NO synthesis, in 19 patients without significant coronary artery disease. The diameter of the large epicardial coronary artery and coronary blood flow (CBF) were assessed by quantitative coronary arteriography and by a Doppler flow velocity measurement. An increase in the heart rate increased CBF (P < .01) and the coronary artery diameter (P < .05). L-NMMA at a total dose of 200 mumol reduced basal CBF but did not significantly affect basal coronary artery diameter, arterial pressure, or heart rate. L-NMMA inhibited the pacing-induced dilatation of the large coronary arteries (P < .05) but did not affect pacing-induced increases in CBF. L-NMMA inhibited the acetylcholine-induced increase in CBF (P < .01) and acetylcholine-induced dilatation of the large epicardial coronary artery (P < .05). These results show that the contribution of NO to the metabolic vasodilatation during rapid pacing may differ between large epicardial and resistance coronary arteries in patients without significant coronary artery disease.

Improvement of pharmacokinetics and antitumor activity against human hepatoma cell line by using adriamycin-entrapped stealth liposomes

Preferential accumulation in the reticuloendothelial system is one of the major obstacles to the use of liposomes as a drug carrier for targeting therapy. To reduce their uptake, ganglioside GM1 was introduced into the components of conventional liposomes that had been used in our targeting experiments. Two types of such liposomes were prepared. Tissue distribution studies on Adriamycin entrapped in both types of liposomes clearly indicated that the uptake of Adriamycin by liver and spleen decreased to the level comparable to that of free Adriamycin administration. By contrast, the level of Adriamycin in the serum remains high, and some increase was observed in the accumulation to the tumor. Furthermore, Adriamycin in these liposomes, which were conjugated with anti-alpha-fetoprotein (AFP) antibody, inhibited the growth of AFP-positive human hepatoma Li-7 more efficiently than free Adriamycin or Adriamycin in antibody-conjugated conventional liposomes.

GTP-cyclohydrolase I gene mutations in hereditary progressive amd dopa-responsive dystonia

Recently, mutations of the GTP-cyclohydrolase I (GTP-CH I) gene, which catalyzes the first step in the tetrahydrobiopterin (BH4) biosynthesis, were discovered in Japanese patients with hereditary progressive dystonia/dopa-responsive dystonia (HPD/DRD). However, it has not been confirmed that non-Japanese patients also contain mutations in the same gene, or whether these mutations are specific to HPD/DRD. In this study, two novel nonsense mutations in exon I of the GTP-CH I gene and a new mutation at the splice acceptor site of intron I were identified in an autopsied case of English-Irish descent and 2 Japanese patients with HPD/DRD. In the latter, cerebrospinal fluid (CSF) neopterin levels (which may reflect the GTP-CH I activity in the brain) were reduced to 18% and 37% of controls. A therapeutic trial of oral BH4 was ineffective, however, in a genetically proven patient. In contrast, no mutations in any exons of the GTP-CH I gene were found in 2 patients with early-onset parkinsonism with dystonia (EOP-D) who developed dopa-responsive parkinsonism and dystonia at 6 and 8 years old, respectively. Neopterin levels in CSF were well preserved in 6 EOP-D patients. These data suggest that, among patients of different racial backgrounds, the pathogenesis of HPD/DRD, unlike EOP-D, involves partial reduction of the brain GTP-CH I activity consequent to mutations in the GTP-CH I gene. Measurement of CSF neopterin concentration may be useful for the differential diagnosis between HPD/DRD and EOP-D.

Basal release of endothelium-derived nitric oxide at site of spasm in patients with variant angina

OBJECTIVES

The aim of this study was to investigate the basal release of nitric oxide at spastic sites in patients with variant angina.

BACKGROUND

We previously reported that endothelium-dependent dilator responses to acetylcholine, substance P and bradykinin are preserved at the site of coronary artery spasm. However, it is not known whether the basal release of endothelium-derived nitric oxide is altered at the spastic site.

METHODS

The effects of intracoronary N(G)-monomethyl-L-arginine (L-NMMA, an inhibitor of nitric oxide synthesis) at cumulative doses of 50, 100 and 200 micromol on basal coronary artery tone were investigated in eight patients with variant angina and normal coronary angiograms and in eight control subjects. The lumen diameters of large epicardial coronary arteries were assessed by quantitative coronary arteriography.

RESULTS

Coronary spasm was provoked by the intracoronary administration of acetylcholine in all patients with variant angina. L-NMMA did not alter the arterial pressure and heart rate but significantly decreased the coronary artery diameter at spastic and nonspastic sites. Constrictive responses to L-NMMA were significantly greater (p < 0.01) at the spastic site (constriction by 200 micromol, 22+/-7%, mean +/- SD) than at the nonspastic site (10+/-7%). Constrictive responses to L-NMMA at the nonspastic site in patients with variant angina were comparable to those in the control subjects.

CONCLUSIONS

These findings support the hypothesis that the basal release of nitric oxide may not be decreased at the spastic site in patients with variant angina.

Antihypertensive effects of a new transdermal delivery system for clonidine in genetic and experimental hypertensive rats

The antihypertensive effects of a new transdermal delivery system for clonidine (CAS 4205-90-7, clonidine tape, M-5041T) were investigated in spontaneously hypertensive rats (SHR), 2-kidney, 1-clip renal hypertensive rats (RHR) and deoxycorticosterone acetate (DOCA)-salt hypertensive rats. M-5041T (0.5-4.5 mg/kg) elicited a long-lasting hypotensive effect that was accompanied by bradycardia in a dose-dependent manner during 24-h patching on the backs of rats in all three hypertensive rat models. The hypotensive effect of M-5041T was more persistent than that of oral administration of clonidine (50 and 100 micrograms/kg) in both SHR and RHR. The most pronounced hypotensive effect of M-5041T was observed in DOCA-salt hypertensive rats. Plasma clonidine concentrations following transdermal application of M-5041T (1.5 mg/kg) were approximately 2-3 fold higher in DOCA-salt hypertensive rats compared with SHR. Electrical conductance of the skin surface, an index of the water content of the stratum corneum, was greater in DOCA-salt hypertensive rats than in SHR, suggesting that the delivery of clonidine may have been enhanced as a result of an increase in skin permeability due to the increase in water content of the stratum corneum in DOCA-salt hypertensive rats. Co-administration of M-5041T (0.5 mg/kg) with either trichloromethiazide (1 mg/kg, orally) or nifedipine (3 mg/kg, orally) at each sub-dose which affected both systolic blood pressure and heart rate produced significant hypotensive and bradycardic effects in SHR. Following repeated daily applications of M-5041T (1.5 mg/kg) for 7 consecutive days in SHR, significant hypotensive and bradycardic effects were produced at 6 h post-patching and then disappeared at 24 h post-patching in each trial. The plasma clonidine concentrations at 6 and 24 h post-patching were similar from the first to the seventh trial. No significant changes in blood pressure and heart rate were observed after termination of the regimen. These findings suggest that M-5041T could serve as an efficient and useful antihypertensive transdermal delivery system in humans without producing tolerance to the hypotensive effect and withdrawal syndrome after abrupt cessation of the treatment when used alone or with either a diuretic or a calcium channel blocker.

Transfer function analysis of central arc of aortic baroreceptor reflex in rabbits

While electrically stimulating the aortic depressor nerve (ADN) pseudorandomly, we recorded renal sympathetic nerve activity (RSNA) and systemic arterial pressure (SAP) in 19 alpha-chloralose-anesthetized rabbits with sinoaortic denervation. From the recorded signals, we determined the transfer functions from ADN stimulation by a pseudorandom binary sequence to RSNA [HCMD.RSNA(f)] and to SAP [HCMD.SAP(f)]. The modulus of HCMD.RSNA(f) was flat over 0.0122-0.8 Hz, whereas the phase lag increased linearly with frequency. Thus the central transduction appeared not to modify the relative amplitude of the signals from the baroreflex afferents but to provide a fixed time delay (approximately 400 ms). In contrast, the modulus of HCMD.SAP(f) decreased precipitously toward high frequencies, and the degree of the phase lag was larger than that of HCMD.RSNA(f). We conclude that 1) the transfer property of the central are does not significantly modify the relative amplitude of the frequency components of the baroreflex afferents but provides a fixed time delay and 2) the frequency independence of the modulus of the transfer property is not preserved when the analysis is extended to SAP.

Preclinical assessment of a new transdermal delivery system for clonidine (M-5041T)

The effects of a new transdermal delivery system for clonidine (M-5041T) on hypotensive effect, urine volume, plasma renin activity (PRA) and antidiuretic hormone (ADH) in spontaneously hypertensive rats (SHRs) were compared to the effects of the continuous infusion of clonidine. Both M-5041T (1.5 and 4.5 mg/kg) and the continuous infusion of clonidine (250 micrograms/kg/24 h) elicited hypotensive effects persisting for 12 hours or more. These effects were based on consistent plasma concentrations of clonidine. These two treatments produced diuresis followed by antidiuresis, which was remarkably observed by continuous infusion of clonidine. Single subcutaneous injection of clonidine (50 micrograms/kg) produced diuresis accompanied by increases in electrolytes corresponding to plasma levels of clonidine. M-5041T at 1.5 mg/kg did not affect PRA until 12 h, and produced an increase in PRA at 24 h. M-5041T at 4.5 mg/kg and the continuous infusion of clonidine resulted in a decrease in PRA at 2 and 1 h followed by an increase at 12 and 24 h, respectively. M-5041T at 1.5 mg/kg did not affect plasma levels of ADH. Plasma ADH did increase at 2 and 4 h accompanied by diuresis following M-5041T at 4.5 mg/kg or the continuous infusion of clonidine, respectively. Clonidine-induced diuresis was not at least due to the inhibition of ADH release. The decrease in urine volume observed by continuous infusion of clonidine may be due to decrease in renal blood flow based on stimulation of peripheral adorenoceptors of clonidine. These findings suggest that the increases in ADH and PRA are due to the compensatory effects related to both diuresis and the long-lasting hypotensive effect induced by high plasma concentrations of clonidine. Thus, it can be expected that M-5041T at 1.5 mg/kg showing the minimum effective plasma concentration of clonidine will not result in tolerance to the hypotensive effect of clonidine associated with the retention of sodium in SHRs.

Effects of a newly developed transdermal clonidine delivery system (M-5041T) on EEG sleep-wake cycle in relation to plasma concentration in rabbits

1. The effects of a transdermal clonidine delivery system (M-5041T) on EEG sleep pattern with relation to plasma concentrations in unrestrained rabbits were investigated and compared with those of intravenous (i.v.) administration of clonidine. 2. Although M-5041T did not affect the EEG recorded from cortex and hippocampus at doses up to 2.5 mg/kg, slow theta waves in hippocampal EEG accompanied by low-voltage slow waves in cortex were induced at a higher dose of 12.5 mg/kg. On i.v. injection (0.25 mg/kg), EEG tracings with bursts of high-voltage slow waves in cortical EEG and slow theta waves in hippocampus were observed. 3. At doses of 0.5 and 2.5 mg/kg, M-5041T did not cause any alterations of the sleep-wake cycle, and plasma concentrations of 1-2 ng/ml were maintained for an 8-hr observation period. However, this delivery system significantly suppressed the incidence of rapid-eye movement sleep (REMS) from 11.9 to 4.7% and enhanced drowsiness (DW) from 9.0 to 21.0% during the 8-hr recording period at 12.5 mg/kg with a plasma concentration of up to 10 ng/ml. Contrary to transdermal administration, i.v. clonidine (0.25 mg/kg) completely blocked light and deep slow wave sleep as well as REMS with a plasma concentration indicated more than 10 ng/ml at 2 hr post administration. Recovery to a normal sleep-wake cycle was eventually established thereafter. The incidence of REMS and DW were significantly decreased from 11.9 to 6.3% and increased from 9.0 to 25.5%, respectively. 4. Concurrent monitoring of clonidine concentrations in cerebrospinal fluid (CSF) indicated that CSF concentrations after patching M-5041T, as well as i.v. clonidine, were almost equal to plasma levels. 5. These results suggest that alteration of the sleep-wake cycle with clonidine occurs depending upon brain concentrations, which increase to a level similar to that in plasma after administration, and that M-5041T at doses of less than 2.5 mg/kg could establish effective hypertensive therapy without obvious effects on the cycle.

[Clinical and electroencephalographic studies in children with hemimegalencephaly]

Clinical and electroencephalographic (EEG) studies were performed in two children with hemimegalencephaly. The ages of seizure onset were 44 hours after birth in one infant and 33 days of postnatal life in the other patient. In both children, infantile spasms (IS) associated with hemihypsarrhythmia, developed at 1.5 months and 4 months, respectively. The subsequent clinical courses in these children were notable for frequent, intractable seizures. The seizures consisted of either generalized or partial seizures which originated from not only the hemimegalic hemisphere but also the contralateral one. Later, the clinical and EEG findings in one child indicated the development of Lennox-Gastaut syndrome (LGS). These findings suggested that the lesions of epileptogenesis in patients with hemimegalencephaly involved not only the pathological hemisphere, but also the contralateral hemisphere and subcortical structures. A detailed neurophysiological investigation in hemimegalencephaly could help the elucidation of the pathophysiology of intractable epilepsies, such as IS or LGS.

Central GABAergic mechanisms are defective in salt-induced hypertension in borderline hypertensive rats

We examined the role of central GABAergic mechanisms in salt-induced hypertension and exaggerated responses to stress in borderline hypertensive rats (BHR), the first offspring of spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY). The studies were done in conscious BHR and WKY on high (H) (8% NaCl) or normal (N) (0.3% NaCl) salt diets for 5 weeks. A high-salt diet elevated arterial pressure (AP) (p < 0.01) and augmented pressor responses to shaker stress (p < 0.05) in BHR but not in WKY. Intravenous hexamethonium caused a greater decrease in AP in BHR-H than in BHR-N at rest. Muscimol (a GABA agonist) injected into the central ventricle (i.c.v.) caused a greater decrease in resting AP (p < 0.01) and heart rate (HR) (p < 0.05) and BHR-H than in BHR-N. Renal sympathetic nerve activity (RSNA) did not change in BHR-H, but increased (p < 0.05) in BHR-N during muscimol-induced hypotension, although the magnitudes of muscimol-induced hypotension were greater in BHR-N than in BHR-N. The increases in RSNA in response to intravenous nitroglycerin were similar in BHR-N and BHR-N. Muscimol attenuated pressor and tachycardic responses to stress more in BHR-N than in BHR-N (p < 0.01). Muscimol did not alter AP and HR at rest or their responses to stress in the two groups of WKY. The magnitudes of pressor response to bicuculline (a GABA antagonist) did not differ between the two groups of BHR. These results suggest that a high salt diet may alter the central GABAergic system in BHR, which contributes to salt-induced hypertension and augmented pressor and tachycardic responses to stress.

Hypotensive effects of a new transdermal delivery system for clonidine (M-5041T) in spontaneously and renal hypertensive rats

1. Antihypertensive effects of a new transdermal delivery system for clonidine (clonidine tape; M-50417) were investigated in spontaneously hypertensive rats (SHR), 2-kidney, 1-clip renal hypertensive rats (RHR) and deoxycorticosterone acetate/salt (DOCA/Salt) hypertensive rats. 2. M-5041T (0.5-4.5 mg/kg) elicited long-lasting hypotensive effects and bradycardia in a dose-dependent manner during 24 h patching in three hypertensive models compared with oral clonidine (100 mu g/kg). 3. The most hypotensive effect of M-5041T was observed in DOCA/salt hypertensive rats. 4. Co-administration of M-5041T with either trichloromethiazide (1 mg/kg, orally) or nifedipine (3 mg/kg, orally) at each dose without hypotensive effects per se induced significant hypotension in SHR. 5. Repeated administrations of M-5041T (1.5 mg/kg per day) for a consecutive 7 days produced significant hypotensive effects at postpatching 6 h, and recovered a postpatching 24 h in SHR. 6. Repetitive M-5041T administrations displayed no tolerance on the hypotensive effects and were devoid of any withdrawal syndrome. 7. These findings suggest that M-5041T may serve as an efficiently useful antihypertensive transdermal delivery system in humans.

[Preoperative plasmapheresis for lung cancer with multiple myeloma]

A 66-old-male admitted to our hospital was diagnosed multiple myeloma (IgA kappa type, Durie & Salmon stage IIIA) and squamous cell lung cancer (c-T2N0M0 stage I). The function of platelets was within a normal range (11.7 x 10(4)/mm3 and the bleeding time of two minutes), but the function of coagulation was reduced (prothrombin time, 13.1 seconds; activating prothrombin time, 45.1 seconds; and antithrombin III, 65%). The hyperviscosity syndrome was anticipated because of high IgA M protein (6,551 mg/dl). Plasmapheresis with 800 ml of fresh frozen plasma was performed before the left lower pulmonary lobectomy and R1 lymph node dissection. Then the function of coagulation was improved (prothrombin time, 12.6 seconds; activating prothrombin time, 31.3 seconds; and antithrombin III, 75%). IgA M protein was also decreased to 4,696 mg/dl. Postoperative bleeding necessitated a second thoracotomy. The cause of postoperative bleeding was the ablasion of the pleural adhesion due to tuberculous pleuritis as well as bleeding tendency of multiple myeloma. The plasmapheresis performed in this case did not fully improve the bleeding tendency. Cases of cancer complicated with multiple myeloma have been increasing and if an operation is needed, plasmapheresis should be considered. The indication and the extent of hematologic restoration to be achieved should be further investigated.

Cholesterol sulfate, a second messenger for the eta isoform of protein kinase C, inhibits promotional phase in mouse skin carcinogenesis

Cholesterol sulfate is a second messenger for the eta isoform of protein kinase C mediating squamous differentiation. We found that cholesterol sulfate inhibited the promotional phase of skin carcinogenesis in female CD-1 mice, which was initiated by 100 micrograms 7,12-dimethylbenz[a]-anthracene and promoted by a single application of 10 micrograms 12-O-tetradecanoylphorbol-13-acetate, followed by repeated applications of 10 micrograms mezerein once a week for 19 weeks. Cholesterol sulfate, when applied topically at a dose of 400 micrograms (820 mumol) 10 min before treatment with the promoters, markedly suppressed tumor formation, resulting in decrease of 56% in the incidence of tumor-bearing mice, 81% in the number of tumors/mouse, and 60% in the size of tumors at 20 weeks of the promotion. This inhibition was not due to elimination of the initiated cells. Treatment with the parental cholesterol at a dose of 320 micrograms (820 mumol), which does not activate the eta isoform, did not inhibit tumor promotion. Repeated treatment with cholesterol sulfate induced scaling of skin at the site of application. Cholesterol sulfate, unlike most inhibitors of tumor promotion, did not inhibit induction of ornithine decarboxylase and hyperplasia in mouse epidermis caused by topical treatment with 12-O-tetradecanoylphorbol-13-acetate. These findings suggest that cholesterol sulfate inhibits tumor promotion by stimulating a differentiation pathway mediated by the eta isoform of protein kinase C.

Myofibroma of the mandible. Clinicopathologic study and review of the literature

A case of mandibular myofibroma in a 2-month-old boy is presented. Including this case, 24 pediatric and 11 adult patients with maxillofacial myofibroma have been reported since 1981. Of the 24 pediatric patients, 15 (62.5%) had lesions affecting the mandible. The adult cases had no mandibular involvement. Histologic evaluation of the tissue specimen revealed an interlacing pattern of spindle-shaped cells with long oval nuclei. Tissue immunohistochemical staining found it to be reactive for antibodies directed against vimentin and alpha-smooth muscle actin, but not desmin, S-100 protein, neuron-specific enolase, or myoglobin. Electron microscopy examination revealed the following cells: myofibroblast-like cells, fibroblast-like cells, and intermediate cells that were similar to the fibroblast-like cells except for the presence of a few microfilaments. Myoblast-like cells were not seen.

The cell cycle-dependent nuclear import of v-Jun is regulated by phosphorylation of a serine adjacent to the nuclear localization signal

Cell cycle-dependent phosphorylation and nuclear import of the tumorigenic transcription factor viral Jun (v-Jun) were investigated in chicken embryo fibroblasts. Nuclear accumulation of v-Jun but not of cellular Jun (c-Jun) is cell cycle dependent, decreasing in G1 and increasing in G2. The cell cycle-dependent regulation of v-Jun was mapped to a single serine residue at position 248 (Ser248), adjacent to the nuclear localization signal (NLS). Ser248 of v-Jun represents an amino acid substitution, replacing cysteine of c-Jun. It was shown by peptidase digestion and immunoprecipitation with antibody to the NLS that v-Jun is phosphorylated at Ser248 in the cytoplasm but not in the nucleus. This phosphorylation is high in G1 and low in G2. Nuclear accumulation of v-Jun is correlated with underphosphorylation at Ser248. The regulation of nuclear import by phosphorylation was also examined using NLS peptides with Ser248 of v-Jun. Phosphorylation of the serine inhibited nuclear import mediated by the NLS peptide in vivo and in vitro. The protein kinase inhibitors staurosporine and H7 stimulated but the phosphatase inhibitor okadaic acid inhibited nuclear import mediated by the NLS peptide. The cytosolic activity of protein kinases phosphorylating Ser248 increased in G0 and decreased during cell cycle progression, reaching a minimum in G2, whereas phosphatase activity dephosphorylating Ser248 was not changed. These results show that nuclear import of v-Jun is negatively regulated by phosphorylation at Ser248 in the cytoplasm in a cell cycle-dependent manner.

Absence of tolerance to hypotensive effects of clonidine in spontaneously hypertensive rats

Development of tolerance to the hypotensive effects of clonidine was investigated in spontaneously hypertensive rats (SHR). Clonidine (125 micrograms/kg/day) was administered subcutaneously for 5 weeks using an osmotic infusion pump. During the whole infusion period, significant hypotensive and bradycardiac effects were observed. Plasma clonidine concentrations were maintained relatively constant at about 2 ng/ml during the infusion period. On termination of treatment with clonidine, both the blood pressure and heart rate rapidly recovered to the control levels. These findings suggest that clonidine does not cause tolerance to its hypotensive effects in SHR with the present administration regimen.

V2 receptor-mediated vasodilation in healthy humans

Arginine vasopressin (AVP) causes biphasic changes in vascular resistance in human forearms: vasoconstriction at lower doses and vasodilation at higher doses. Vasoconstriction is mediated by the V1 receptor, but the mechanism of AVP-induced vasodilation remains unclear. To determine if the AVP-induced vasodilation in human forearm vessels is mediated by the V2 receptor, we examined the effects of OPC-31260 (a novel vasopressin V2 receptor antagonist) on AVP-induced vasodilation. The brachial artery was cannulated for drug infusions and direct measurement of arterial blood pressure (BP). We measured forearm blood flow (FBF) by a strain-gauge plethysmograph and calculated forearm vascular resistance (FVR). AVP was infused intraarterially (i.a.) at doses of 0.1, 0.2, 0.5, 1.0, and 2.0 ng/kg/min (n = 8). The lower dose of AVP (0.1 ng/kg/min) increased, whereas the higher doses of AVP (> or = 0.5 ng/kg/min) decreased, FVR (p < 0.01). Infusion of nitroglycerin (NTG) i.v. doses of 1.7, 3.3, and 10.0 ng/kg/min decreased FVR dose dependently (p < 0.01). OPC-31260 (1.0 micrograms/kg/min) infused i.a. did not alter arterial BP, baseline FVR, or heart rate (HR). OPC-31260 did not affect AVP-induced vasoconstriction but blocked AVP-induced vasodilation completely. OPC-31260 did not affect NTG-induced vasodilation. These results suggest that AVP-induced vasodilation is mediated by the V2 receptor in human forearm resistance vessels.

Canine pulmonary hypertension model induced by pulmonary artery embolization of gelatin sponges

We attempted to develop a pulmonary hypertension model in dogs by gelatin sponge embolization. We then monitored right-ventricular pressure overload by echocardiography. Gelatin sponges (Spongel, Yamanouchi, Tokyo) were homogenized and mixed in normal saline (0.6 mg/ml). The mixture was administered via the jugular vein to general pulmonary emboli. Repeated administration of the sponges increased the mean pulmonary arterial pressure and caused right ventricular pressure overload. The degree of pulmonary hypertension was proportional to the volume of gelatin sponge injected. Echocardiography, performed both before and after embolization, proved useful assessing for the degree of right-ventricular pressure overload.

Role of nitric oxide in exercise-induced vasodilation of the forearm

BACKGROUND

We wished to determine the role of NO in exercise-induced metabolic forearm vasodilation.

METHODS AND RESULTS

Young healthy volunteers (n = 11) underwent static handgrip exercise (4 to 5 kg, 3 minutes). Forearm blood flow (FBF) measured by strain plethysmography increased from 4.1 +/- 0.7 mL.min-1.100 mL-1 at rest to 9.8 +/- 1.2 mL.min-1.100 mL-1 immediately after exercise and gradually decreased thereafter. Exercise was repeated after intrabrachial artery infusion of NG-monomethyl-L-arginine (L-NMMA) at 4.0 mumol/min for 5 minutes. L-NMMA did not alter blood pressure and heart rate. L-NMMA decreased FBF at rest to 2.9 +/- 0.4 mL.min-1.100 mL-1 (P < .01), peak FBF immediately after exercise to 7.2 +/- 0.7 mL.min-1.100 mL-1 (P < .01), and FBF during the mid to late phase of metabolic vasodilation (P < .01). Calculated oxygen consumption during peak exercise was comparable before and after L-NMMA. Intra-arterially infused L-arginine (10 mg/min, 5 minutes) reversed the inhibitory effect of L-NMMA. To determine the effect of the decrease in resting FBF on exercise-induced hyperemia, we normalized FBF after exercise by resting FBF. The percent increases in FBF after exercise from resting FBF were similar before and after L-NMMA. Furthermore, we examined the effect of intra-arterially infused angiotensin II on FBF at rest and after exercise (n = 7). Angiotensin II decreased FBF at rest from 3.1 +/- 0.3 to 1.8 +/- 0.3 mL.min-1.100 mL-1 (P < .01), peak FBF after exercise from 8.1 +/- 0.5 to 5.6 +/- 0.5 mL.min-1.100 mL-1 (P < .01), and FBF during the mid to late phase of metabolic vasodilation. The effects of L-NMMA and angiotensin II on FBF at rest and exercise were similar.

CONCLUSIONS

Our results suggest that L-NMMA decreased FBF after exercise largely by decreasing resting FBF. These results suggest that NO may not play a significant role in exercise-induced metabolic arteriolar vasodilation in the forearm of healthy humans.

[Hypomelanosis of Ito associated with hemimegalencephaly]

A girl aged 1 year and 2 months with hypomelanosis of Ito was reported. She suffered from intractable epileptic seizures since the second day after birth. Characteristic bizarre hypopigmented skin lesions were seen on her left shoulder and extended in a linear fashion to the flexion side of the left upper extremity. Brain MRI revealed diffuse enlargement of the left hemisphere, dilatation of the left lateral ventricle, and neuronal migration anomalies, indicating hemimegalencephaly. The types of her seizures were secondarily generalized or unilateral initially, followed by infantile spasms at 1.5 month. Around 4 months of age, frequent partial seizures appeared. Her seizures were intractable despite vigorous anticonvulsant therapy. As patients with hypomelanosis of Ito are frequently associated with neurological abnormalities, brain MRI studies were thought to be essential in detecting central nervous system anomalies, particularly in the presence of early onset intractable seizures.

Serial IMP-SPECT and EEG studies in an infant with hemimegalencephaly

An 8-month-old girl of hypomelanosis of Ito associated with hemimegalencephaly had frequent seizures beginning 44 h after birth. The seizures were secondarily generalized or unilateral initially, followed by infantile spasms at about 1.5 months of age. Frequent partial seizures appeared at 4 months of age. [123I]N-Isopropyl-p-iodoamphetamine (IMP) single photon emission computed tomography (SPECT) was performed serially during an interictal period at 1, 3 and 7 months of age. At 1 and 3 months, IMP-SPECT showed a marked increase of IMP uptake in the pathological left hemisphere and electroencephalography (EEG) revealed left-sided dominant hypsarrhythmia. At 7 months of age, a reversal was seen, there being decreased uptake on SPECT in the pathological hemisphere and abundant high amplitude background activity mingled with epileptic discharges on EEG in the non-pathological hemisphere. These serial changes of IMP uptake on SPECT seemed to reflect either changes in epileptic activity or maturational changes in cerebral perfusion in hemimegalencephaly.

Relationship between hypotensive effects and plasma concentrations of clonidine in spontaneously hypertensive rats: continuous treatment and sudden termination of clonidine infusion

1. Clonidine was administered subcutaneously (62.5, 125 and 250 micrograms/kg/day) for 8 days using an osmotic infusion pump in spontaneously hypertensive rats (SHR). Clonidine, administered at 125 and 250 micrograms/kg/day at 48 hr after infusion, respectively, and thereafter were maintained at this level throughout the infusion period. 3. After terminating clonidine infusion, a rapid drug elimination from the plasma was manifested in both groups (125 and 250 micrograms/kg/day) with plasma clonidine levels, resulting in a decrease below 0.5 ng/ml at 4 and 6 hr, respectively. Four hours after terminating clonidine infusion at 125 and 250 micrograms/kg/day, transient but not remarkable increases in blood pressure and heart rate were observed only in the latter group compared with the values before termination. 4. These findings reveal that marked hypotensive effects were induced by relatively high doses (125 and 250 micrograms/kg/day) of clonidine in SHR, but no remarkable withdrawal symptoms after termination of clonidine infusion were observed. Therefore, unwanted withdrawal symptoms probably occur when an extremely high dose (250 micrograms/kg/day or more) of clonidine was infused for a long period (8 days or more) in SHR.

Role of nitric oxide in reactive hyperemia in human forearm vessels

BACKGROUND

The role of nitric oxide (NO) in reactive hyperemia (RH) is not well known. We investigated whether NO plays a role in RH in human forearm vessels by examining the effects of NG-monomethyl-L-arginine (L-NMMA), a blocker of NO synthesis, on reactive hyperemic flow.

METHODS AND RESULTS

Forearm blood flow (FBF) was measured by strain-gauge plethysmography with a venous occlusion technique. The left brachial artery was cannulated for drug infusion and direct measurement of arterial pressure. To produce RH, blood flow to the forearm was prevented by inflation of a cuff on the upper arm to suprasystolic pressure for intervals of 3 and 10 minutes. After the release of arterial occlusion (AO), FBF was measured every 15 seconds for 3 minutes. Resting FBF was 4.3 +/- 0.3 mL.min-1.100 mL-1 before 3 minutes of AO and 4.1 +/- 0.6 mL.min-1.100 mL-1 before 10 minutes of AO. FBF increased to 32.3 +/- 1.9 and 38.2 +/- 3.1 mL.min-1.100 mL-1 immediately after 3 and 10 minutes of AO, respectively, and gradually decayed (n = 13). Intra-arterial infusion of L-NMMA (4 mumol/min for 5 minutes) decreased baseline FBF (P < .01) without changes in arterial pressure. L-NMMA did not affect the peak reactive hyperemic FBF after 3 and 10 minutes of AO. L-NMMA significantly decreased total reactive hyperemic flow (flow debt repayment) by 20% to 30% after 3 and 10 minutes of AO. Simultaneous infusion of L-arginine (a precursor of NO) with L-NMMA reversed the effects of L-NMMA.

CONCLUSIONS

Our results suggest that NO plays a minimal role in vasodilation at peak RH but plays a modest yet significant role in maintaining vasodilation after peak vasodilation. Our results also suggest that reactive hyperemia in human forearms is caused largely by mechanisms other than NO.

Effect of L-arginine on acetylcholine-induced endothelium-dependent vasodilation differs between the coronary and forearm vasculatures in humans

OBJECTIVES

The goal of this study was to determine whether the effect of L-arginine on endothelium-dependent vasodilation evoked with acetylcholine differs between the coronary and forearm vasculatures in humans.

BACKGROUND

Administration of L-arginine, a substrate in the production of endothelium-derived nitric oxide, may stimulate the release of nitric oxide.

METHODS

Seven patients with normal coronary angiograms and seven with mild coronary artery disease and hypertension underwent coronary arteriography and an intracoronary Doppler catheter technique, and the diameter of the large epicardial coronary artery and coronary blood flow were measured. Forearm blood flow was measured by use of a strain gauge plethysmograph.

RESULTS

Before L-arginine administration, acetylcholine (1 to 30 micrograms/min) increased coronary blood flow with modest vasoconstriction of a large coronary artery. Acetylcholine (4 to 24 micrograms/min) also increased forearm blood flow. The acetylcholine-induced increases in coronary and forearm blood flow were significantly less in patients with coronary artery disease than in control patients. Intracoronary infusion of L-arginine at 50 mg/min did not alter responses of the large coronary artery diameter or coronary blood flow to acetylcholine in either group. In contrast, L-arginine at 10 mg/min significantly (p < 0.01) augmented the forearm blood flow response to acetylcholine (4 to 24 micrograms/min) to a similar extent in the two groups.

CONCLUSIONS

The effect of L-arginine on acetylcholine-induced vasodilation differs between the coronary and forearm vasculatures in humans. It is suggested that impaired acetylcholine-induced coronary and forearm vasodilation in patients with coronary artery disease and hypertension may not be related to a limited availability of L-arginine.

Effects of L-arginine on impaired acetylcholine-induced and ischemic vasodilation of the forearm in patients with heart failure

BACKGROUND

Endothelium-dependent vasodilation in response to acetylcholine (ACh) and ischemic vasodilation during reactive hyperemia are attenuated in the forearm of patients with heart failure (HF). It has been shown that L-arginine augments endothelium-dependent vasodilation in healthy subjects. Thus, the aim of the present study was to determine if L-arginine improves endothelium-dependent and ischemic vasodilation in the forearm in HF.

METHODS AND RESULTS

Forearm blood flow was measured by a strain-gauge plethysmograph in 20 patients with HF and in 24 age-matched control subjects (C). Resting forearm vascular resistance (FVR) was significantly higher in HF than in C (37 +/- 4 versus 22 +/- 2 U, P < .01). Intra-arterial infusions of ACh or sodium nitroprusside (SNP) at graded doses progressively decreased FVR in HF as well as in C. The magnitude of ACh-induced vasodilation was attenuated in HF (P < .01), whereas SNP-induced vasodilation was similar between the two groups. The minimal FVR during reactive hyperemia after 10 minutes of arterial occlusion was significantly higher in HF (n = 12) than in C (n = 12) (3.2 +/- 0.4 versus 2.1 +/- 0.1 U, P < .05). L-Arginine significantly augmented maximal vasodilation evoked with ACh and decreased minimal FVR during reactive hyperemia in HF (P < .01) but not in C. L-Arginine did not affect SNP-induced vasodilation in HF or C.

CONCLUSIONS

Our results suggest that defective endothelial function may contribute to impaired ischemic vasodilator capacity in HF.

Nitric oxide influences neuronal activity in the nucleus tractus solitarius of rat brainstem slices

Nitric oxide (NO) is shown to be synthesized in the central nervous system as well as in vascular endothelial cells. However, the physiological role of NO in cardiovascular regulation in the central nervous system remains unclear. The present study examines whether NO plays a role in the regulation of neuronal activity in the nucleus tractus solitarius (NTS). Single-unit extracellular recordings were obtained from NTS neurons in slices (400 microns) of the rat brainstem, which had spontaneous discharges at a frequency of 0.5 to 3 spikes per second. Eighty-one neurons were tested for sensitivity to L-arginine, which is the physiological precursor of NO. L-Arginine (10(-7) to 10(-4) mol/L) increased neuronal activity dose dependently in 33 (40.7%) of 81 neurons tested, but D-arginine (10(-5) mol/L) did not. The neurons that responded to L-arginine responded to glutamate as well. NG-Monomethyl-L-arginine (10(-5) to 3 x 10(-5) mol/L), an inhibitor of the formation of NO, dose-dependently blocked increases in the neuronal activity evoked with L-arginine (10(-5) mol/L). Hemoglobin (1.5 mg/L), a trapper of NO, and methylene blue (10(-5) mol/L), an inhibitor of guanylate cyclase, also blocked increases in the neuronal activity evoked with L-arginine (10(-5) mol/L). Sodium nitroprusside (SNP, 10(-5) to 10(-4) mol/L), which spontaneously produces NO, increased the neuronal activity in the neurons that responded to L-arginine. SNP did not alter the neuronal activity of the neurons that did not respond to L-arginine.(ABSTRACT TRUNCATED AT 250 WORDS)