[Changes of 24-h Holter monitor recordings in association with interferon alpha therapy for chronic hepatitis C]

We examined cardiovascular complication of interferon (IFN) therapy in 23 patients with chronic hepatitis C who did not have cardiac disease prospectively. Twenty four-h Holter monitor recordings were performed before and during IFN therapy. Seven of these patients (30%) showed abnormalities on their 24-h Holter monitoring recordings. Premature ventricular contraction (PVC) occurred in two patients, intermittent WPW syndrome in one, and ST-T change in four. Only one patient with PVC complained of palpitation. These complications were not severe and immediately after IFN therapy was stopped. There was no correlation between Holter ECG abnormalities and sex, age, quantity of HCV, or 2-5 oligoadenylate synthetase activity. It was suggested that cardiovascular complications caused by IFN therapy occurred more frequently than expected. However, diagnosis of these complications is difficult because most patients have no subjective symptoms and there is scarcely any change in laboratory test results. Careful observation of patients may be required during IFN therapy regardless of cardiovascular symptoms.

Differential effect of the antidiabetic thiazolidinediones troglitazone and pioglitazone on human platelet aggregation mechanism

Troglitazone and pioglitazone, antidiabetic thiazolidinediones, are known to improve insulin resistance. However, the effect of these drugs on platelet aggregation remains unclear. The chemical structure of troglitazone contains vitamin E. Accordingly, we studied the effect of troglitazone, pioglitazone, and vitamin E on thrombin-induced platelet aggregation, metabolism of phosphoinositide, protein phosphorylation, protein kinase C (PKC)-alpha and -beta, and phosphatidylinositol (PI) 3-kinase activation in vitro in human platelets. Maximum platelet aggregation by ADP, collagen, and thrombin decreased in the presence of 0.1-1 micromol/l troglitazone and 500 nmol/l vitamin E for 60 min compared with controls. However, pioglitazone did not inhibit ADP-, collagen-, or thrombin-induced platelet aggregation. Pretreatment with troglitazone and vitamin E, but not with pioglitazone, resulted in decreases in thrombin-induced phosphatidic acid production, hydrolysis of phosphatidylinositol 4,5-bisphosphate by phospholipase C, and 47-kDa protein phosphorylation. Thrombin-induced PKC-alpha and -beta activation in membrane fraction was suppressed by pretreatment with troglitazone and vitamin E, but not with pioglitazone. Separately, troglitazone and pioglitazone stimulated PI 3-kinase activity, but thrombin-induced PI 3-kinase activation was suppressed by pretreatment with troglitazone and pioglitazone for 60 min. These results suggest that troglitazone and vitamin E, but not pioglitazone, have a potent inhibitory effect on platelet aggregation via suppression of the thrombin-induced activation of phosphoinositide signaling in human platelets. Finally, the chemical structure of vitamin E may contribute to the inhibitory effect of troglitazone on platelet aggregation in human platelets.

The effect of high-salt diet intake on muscular exercise ability in young Japanese women

This study was designed to test whether high-salt diet intake has some acute impaired effect to the muscular exercise ability due to the calcium deficit in muscle cell via the accelerated sodium-calcium exchanger. Six healthy young Japanese women (aged: 22.3 +/- 1.9 yr) performed two types of muscle strength tests and ramp mode cycle ergometer exercise until exhaustion after normal- (NaCl is approximately 5.6 g) and high-salt (21.0 g) controlled diet intake on two separate days in random order. The urinary sodium excretion sampled during 12 hours on the high-salt diet day was significantly higher compared to that of normal-salt diet day (3301 +/- 992 vs 1595 +/- 540 mg; P < 0.05), while there was no substantial difference between the urinary calcium excretion in high- and normal-salt diet days (58.6 +/- 19.7 vs 55.0 +/- 17.2 mg; ns). There were no significant differences in back strength, repeated maximal hand grip exercise ability, and VO2max and duration time during ramp exercise between high- and normal-salt diet conditions. It was concluded that high-salt diet intake even exceeding 20 g per day had substantially no acute effect on muscular exercise ability in young Japanese women.

[Two cases of coronary artery aneurysm including one case of the left main coronary artery aneurysm]

We report two cases of coronary artery aneurysm including one case of the left main coronary artery aneurysm. The coronary angiogram of one patient, a 68-year-old male, having anterior chest pain on exertion, revealed left anterior descending coronary artery (segment 6) aneurysm of 7 mm in diameter with 90% stenosis distal to the aneurysm and 75% stenosis in the right coronary artery (segment 2). The coronary angiogram of another patient, a 69-year-old female, having chest pain unrelated to exertion, revealed left main coronary artery aneurysm of 25 mm in diameter and delayed filling of contrast medium into the left anterior descending coronary artery. We decided to operate by the reason of not only significant coronary artery stenosis but risks of myocardial infarction due to embolization into distal coronary arteries and rupture of the aneurysm. We performed coronary artery bypass graftings using the great saphenous veins and closure of the coronary arteries running into and out the aneurysm under cardiopulmonary bypass. It is recommended that ligation of the coronary arteries connecting to the aneurysm or resection of the aneurysm followed by coronary artery bypass grafting is performed before developing myocardial infarction or rupture of aneurysm.

Alterations in insulin-induced postreceptor signaling in adipocytes of the Otsuka Long-Evans Tokushima fatty rat strain

The Otsuka Long-Evans Tokushima fatty (OLETF) rat is a new spontaneous non-insulin-dependent diabetes mellitus (NIDDM) model rat strain developed in Tokushima, Japan. After 18 weeks of age, decreases of 45% and 40% respectively in insulin- and phorbol ester-stimulated [3H]2-deoxyglucose (DOG) uptake were observed, compared with those in Long-Evans Tokushima (LETO) rats (control). Insulin-specific binding and 95 kDa autophosphorylation of insulin receptor in OLETF rats were not different from those in LETO rats. Insulin-induced diacylglycerol (DG) production and Mono Q column-purified protein kinase C (PKC) translocation in adipocytes of OLETF rats were decreased compared with those of LETO rats. Insulin-induced PKC beta translocation from cytosol to membrane was also decreased in adipocytes of OLETF rats. Increases of the PKC beta I, beta II, epsilon and zeta isoforms in membranes of OLETF rats were markedly smaller than those of LETO rats. Analysis of mRNA levels of PKC isoforms in adipocytes of OLETF rats showed decreases of basal level and insulin-induced delayed responses of PKC beta I, beta II, epsilon and zeta mRNA in OLETF rats. On the other hand, insulin- or phorbol ester-induced phosphatidylinositol 3-kinase (PI 3-kinase) activation was decreased in adipocytes of OLETF rats compared with those of LETO rats. These results suggest that insulin resistance in OLETF rats, a spontaneous NIDDM model rat, may be associated with deterioration of insulin-induced DG-PKC signaling and subsequent decrease in PI 3-kinase activation.

ACTH-induced cortisol secretion is mediated by cAMP and PKC in various adrenocortical adenomas

We examined the role of PKC in cortisol secretion from adrenocortical adenomas. Isolated cells were prepared from aldosterone producing adenoma (APA, n=5), APA complicated with pre-clinical Cushing's syndrome (APA+PC, n=1), PC (n=2), and cortisol producing adenoma (CPA, n=5). They were stimulated with 100 nM ACTH, 1 microM forskolin (FS), 1 microM tetradecanoyl phorbol 13-acetate (TPA), and 100 nM angiotensin II (AngII). ACTH was most potent to secret cortisol. FS also stimulated cortisol secretion, but did less-potently. TPA and AngII also stimulated cortisol secretion significantly in cells from CPA. Furthermore, ACTH- and TPA-induced PKCalpha and beta translocations from cytosol to membrane were observed in adenoma cells from APA+PC, PC, and CPA. In conclusion, it was suggested that ACTH-induced cortisol secretion may be mediated by both PKC and protein kinase A in adrenocortical adenomas, and that PKC-mediated signal transduction may be involved in ACTH-induced cortisol secretion in CPA.

Effect of glucocorticoid receptor antagonist RU 38486 on acute glucocorticoid-induced insulin resistance in rat adipocytes

We examined the mechanism of acute glucocorticoid-induced insulin resistance in rat adipocytes using the glucocorticoid receptor antagonist RU 38486. Pretreatment with dexamethasone (DEX) and prednisolone for 60 minutes resulted in 50% inhibition of insulin-induced [3H]2-deoxyglucose (DOG) uptake at 10(-8) and 10(-7) mol/L, respectively, in rat adipocytes and 20% and 25% inhibition of insulin-induced [3H]2-DOG uptake, respectively, in soleus muscles. Our previous experiments indicated that DEX and prednisolone alone stimulate protein kinase C (PKC) in rat adipocytes. Accordingly, we examined [3H]DEX binding to PKC from MonoQ column-purified rat brain cytosol. Specific [3H]DEX binding to MonoQ column-purified PKC was observed (kd, 56.8 nmol/L; Bmax, 725 fmol/mg protein). Thus, insulin-induced PKC translocation from the cytosol to the membrane was suppressed by pretreatment with 10(-7) mol/L DEX and 10(-6) mol/L prednisolone for 80 minutes. During treatment with RU 38486 for 60 minutes, there was no change in the glucocorticoid-induced inhibitory effect on insulin-induced [3H]2-DOG uptake and PKC translocation from the cytosol to the membrane. Moreover, pretreatment with RU 38486 for 120 minutes slightly prevented the DEX-mediated inhibition of insulin-induced glucose uptake. These results suggest that acute glucocorticoid-induced insulin resistance may be mainly mediated through the other non-glucocorticoid receptor pathway.

Acute effects of phorbol ester and insulin on insulin-induced glucose uptake and protein kinase C activation in rat adipocytes

We examined the acute effect of pretreatment with phorbol ester and insulin on insulin-induced glucose uptake and protein kinase C (PKC) translocation from cytosol to the membrane in rat adipocytes. Adipocytes were preincubated with 1 microM tetradecanoylphorbol 13-acetate (TPA) and 10 nM insulin for 60 min and then stimulated with 10 nM insulin for 10 and 30 min to measure PKC activity in cytosol and membrane fractions using a Mono Q column connected onto an HPLC system and [3H]2-deoxyglucose (DOG) uptake, respectively. Pretreatment with 1 microM TPA and 10 nM insulin for 60 min resulted in the marked decreases of insulin-induced [3H]2-DOG uptake. Translocation of Mono Q column-purified cytosolic PKC enzyme activity and PKC beta immunoreactivity from cytosol to the membrane was suppressed by pretreatment with TPA and insulin for 60 min. These results indicate that acute treatment with TPA and insulin which are PKC activators suppress translocation/activation of PKC, and accordingly inhibit insulin-induced glucose uptake. We suggest that a decrease of cytosolic PKC activity may mainly-contribute to the impaired responsiveness of the glucose transport system after acute TPA and insulin treatment.

Antimutagenicity of Tochu tea (an aqueous extract of Eucommia ulmoides leaves): 1. The clastogen-suppressing effects of Tochu tea in CHO cells and mice

The suppressing effect of crude extracts of Tochu tea, an aqueous extract of Eucommia ulmoides leaves and a popular beverage in Japan, on the induction of chromosome aberrations in CHO cells and mice was studied. When CHO cells were treated with Tochu tea crude extract after MMC treatment, the frequency of chromosome aberrations was reduced. Out of 17 Tochu tea components, 5 irridoids (geniposidic acid, geniposide, asperulosidic acid, deacetyl asperulosidic acid, and asperuloside) and 3 phenols (pyrogallol, protocatechuic acid, and p-trans-coumaric acid) were found to have anticlastogenic activity. Since the anticlastogenic irridoids had an alpha-unsaturated carbonyl group, this structure was considered to play an important role in the anticlastogenicity. The anticlastogenic effect of Tochu tea extracts was examined in mice using a micronucleus assay. When mice received 1.0 ml 4% Tochu tea extract by oral gavage 6 h before intraperitoneal injection of MMC, a decrease in the frequency of micronuclei was observed. This decrease was not due to a delay in the maturation of micronucleated reticulocytes.

Effects of tri-, di- and monobutyltin on synaptic parameters of the cholinergic system in the cerebral cortex of mice

Triorganotin compounds like tributyltin have been reported to be biodegraded to diorganotin, monoorganotin and then inorganic tin in animals after they have been ingested. Effects of tributyltin, dibutyltin and monobutyltin on various cholinergic parameters that are involved in synaptic transmission in the mouse cerebral cortex were investigated in vitro. Tributyltin and dibutyltin, but not monobutyltin, inhibited the activity of choline acetyltransferase, both the high-affinity and low-affinity uptakes of choline into synaptosomes, and the binding of [3H]quinuclidinyl benzilate to muscarinic acetylcholine receptors. Tributyltin and dibutyltin, but not monobutyltin, had a slightly suppressive effect on the K(+)-induced release and synthesis of acetylcholine in slices of the cortex. All three butyltins at concentrations from 10(-6) to 10(-4) M had no effect on the activity of acetylcholinesterase. The extent of the inhibitory effects on the cholinergic parameters, apart from the activity of acetylcholinesterase, was slightly greater in the case of tributyltin than dibutyltin, in particularly at the highest concentration (10(-4) M) tested. Therefore, it is concluded that tributyltin metabolites inhibit various parameters of cholinergic activity with a potency ranking of tributyltin > dibutyltin > monobutyltin.

Replication protein-A mediates the association of calf thymus DNA polymerase alpha-DNA primase complex with guanine-rich DNA sequence

We have shown that calf thymus DNA polymerase alpha-DNA primase complex (pol alpha-primase) preferentially binds to pyrimidine-rich sequences and initiates RNA primer synthesis [Suzuki, M. et al. (1993) Biochemistry 32, 12782-12792]. Here we tested the association of pol alpha-primase with a guanine-rich DNA fragment (SVG, 30-mer) containing in vivo initiation sites of simian virus 40 DNA replication. While pyrimidine-rich fragment (CTPPS 1, 30-mer), that is a preferred sequence for calf thymus DNA primase, was well co-precipitated with pol alpha-primase using anti-pol alpha antibody, SVG was hardly precipitated under the same conditions. Competition studies in either gel-retardation assay or during de novo DNA synthesis by pol alpha-primase demonstrated that the interaction of pol alpha-primase with SVG was much weaker than that with CTPPS-1. On the other hand, replication protein-A (RP-A) could bind SVG, although less efficiently than CTPPS 1. After preincubation with RP-A, SVG could bind pol alpha-primase that was immobilized on Sepharose beads. The simian virus 40 large T antigen also enhanced association of SVG to pol alpha-primase, while Escherichia coli single-stranded DNA-binding protein did not. However, pol alpha-primase, bound to SVG in the presence of RP-A, failed to synthesize RNA primers. When SVG was extended 10 nucleotides at its 5'-end, pol alpha-primase synthesized trace amounts of RNA primers, and this activity was stimulated more than 10-fold by adding RP-A. These results suggest a new role for RP-A, i.e., as a molecular tether that allows pol alpha-primase to bind guanine-rich regions of DNA in order to initiate RNA primer synthesis.

[Drug-induced hemolytic anemia]

Acquired drug-related hemolytic anemia is mainly induced by immune mechanism or microvascular lesion. Three mechanisms of drug-related immunologic injury to red blood cells are recognized. They are hapten or drug adsorption mechanism, ternary or drug-antibody-target cell complex mechanism and autoantibody mechanism. Prototype drugs are penicillin, quinidine and alpha-methyldopa, respectively. Symptoms are mild to moderate in cases of hapten and autoantibody mechanisms and ameliorate by withdrawal of the drugs. Hemolytic anemia due to ternary mechanism may have severe even fetal symptoms, including hemoglobinemia and hemoglobinuria. Some antineoplastic agents can cause hemolytic anemia that resembles the hemolytic uremic syndrome. The prototype drug is mitomycin.

Adrenal metastasis from hepatocellular carcinoma--report of a case

A 66-year-old man presented with an epigastric tumor demonstrated by both ultrasonography and computed tomography as hepatocellular carcinoma. He referred himself to a specialist at another hospital who performed transarterial embolization (TAE) of the hepatic artery. But the serum alpha fetoprotein (AFP) concentration gradually rose after the procedure. A right adrenal metastasis was discovered by computed tomography 9 months after his presentation, 8 months after first embolization. When TAE was performed for this metastasis, there was transverse palsy of the lower limb secondary to spinal artery embolization. He returned to our hospital where a right adrenectomy was performed 14 months after his first presentation. The operation was successful and he was discharged 6 weeks later. But he was readmitted in 8 months with an elevated serum AFP concentration and died within 2 weeks. The details of this case are presented, and the indications for resection of adrenal metastasis from hepatocellular carcinoma are discussed.

Translocation (3;14)(q27;q11): a new variant translocation in a patient with non-Hodgkin's lymphoma of B-cell type with BCL6 rearrangement

We report a 65-year-old woman with non-Hodgkin's lymphoma (NHL) carrying a t(3;14)(q27;q11) and BCL6 rearrangement in the affected cells. She had generalized lymphadenopathy and the bone marrow was infiltrated by lymphoma cells at presentation. Histological diagnosis was "malignant lymphoma, diffuse, large cell" type according to an International Working Formulation. Chromosome analysis revealed a t(3;14)(q27;q11), which is a new variant translocation of t(3;14) (q27;q32). Southern blot analysis showed rearrangement of BCL6, JH, and TCR beta but not of TCR delta. Cosmid probe of BCL6 hybridized to 14q11 and 3q27 by fluorescence in situ hybridization (FISH). Although the band 14q11 is a locus of T-cell receptor alpha- and delta-chains (TCR alpha/delta), lymphoma cells expressed B-cell, IgGk phenotype. The findings suggest that a novel proto-oncogene in the vicinity of TCR alpha/delta is involved in this translocation.

Insulin regulated PKC isoform mRNA in rat adipocytes

Insulin and 12-O-tetradecanoyl phorbol-13-acetate (TPA) induce both glucose uptake and translocation of protein kinase C (PKC) from cytosol to membrane in insulin-sensitive tissues as previously reported by several investigators. We examined insulin-mediated PKC beta I, beta II, and epsilon translocation from cytosol to cytoskeleton, and expression of PKC alpha, beta I, beta II, gamma, and epsilon isoforms using the reverse transcription polymerase chain reaction (RT-PCR) method during treatment with insulin for 240 min in rat adipocytes. Insulin-induced increases in PKC beta I, beta II, and epsilon were greater in the cytoskeleton fraction than those in the membrane fraction. Insulin induced time-dependent increases in PKC alpha, gamma, epsilon and zeta mRNA levels for up to 240 min (555%, 117%, 236% and 138% increase, respectively). TPA also induced time-dependent increases in PKC alpha and gamma (34% and 500% increase, respectively) but not in PKC zeta. However, PKC beta I mRNA was decreased for up to 60 min and then maintained at under the basal level during stimulation with insulin and TPA. On the other hand, PKC beta II mRNA was markedly increased for up to 240 min. These results suggest that insulin-regulated PKC alpha, gamma and epsilon mRNA levels and PKC beta mRNA alternative splicing may occur in rat adipocytes.

[Methicillin-resistant Staphylococcus aureus infection in the Akita University Hospital: surveillance and microbiology data]

In order to control the nosocomial infections by methicillin-resistant Staphylococcus aureus (MRSA) in the Akita University Hospital, the systematic surveillance for MRSA-infection has been done since October in 1991. We reviewed MRSA-isolation numbers, MRSA-detected patient numbers, risk factors of nosocomial infection and patient's basic diseases with the data of a total 336 cases, and then examined the microbiological characteristics of MRSA strains which had been isolated in our hospital in 1986 approximately 1994. The results obtained are as follows; 1) MRSAs were isolated at 13 per month on the average and the detection rate was 0.81 to 1,000 inpatients per day. 2) MRSAs were isolated more in the surgical ward. 3) Patients with 0 year old and more than 60 years old were more infected. 4) MRSA was isolated more from the immunocompromised patients with underlying diseases such as malignant tumors but half of the diseases were not affected by MRSA. 5) Seventy percent of patients had the risk factors of MRSA-transmission such as surgical operation and IVH-cathetering. 6) All isolates of MRSA strains in our hospital showed type II in coagulase type analysis and resistance to minocycline and ofloxacin. 7) It was suggested that one strain expanded throughout the hospital by several DNA analysis with the mecA gene in MRSA. These surveillance and microbiology data will be useful for our nosocomial mecA gene in MRSA. These surveillance and microbiology data will be useful for our nosocomial infection control.

Internal DNA deletion within the BCL-6 gene on untranslocated chromosome in non-Hodgkin's lymphoma with 3q27 abnormality

Chromosomal translocations involving the band 3q27 are recognized as common specific cytogenetic abnormalities in B cell non-Hodgkin's lymphoma (NHL), and the BCL-6 gene, identified on 3q27 was shown to be disrupted by these translocations. Previously, we have reported biallelic BCL-6 rearrangements occurring in some patients with B cell NHL. In the present study, we describe a NHL patient with t(3;22)(q27;q11) translocation. In this patient, biallelic BCL-6 abnormalities were indicated by Southern blot analysis. Further studies revealed that one of the two independent abnormalities was a juxtaposition to the immunoglobulin (Ig) lambda gene associated with chromosomal translocation, whereas the other was an internal DNA deletion of 1.5 kb area on untranslocated chromosome 3. Deletion junctions were located within the first exon and the 5' region of the first intron. The result provides the evidence that, besides chromosomal translocation, submicroscopic local DNA recombination can cause structural alteration of the BCL-6 gene.

The effect of a collagenous implant on deep dermo-periosteal defects in the rabbit

In plastic surgery, extensive wounds with exposed bone and loss of the periosteum (i.e., deep dermo-periosteal defects) are difficult to treat, even with split-thickness skin grafts, because such grafts rarely survive. Even when these grafts do survive, functional impairment often occurs subsequently. The application of a collagen sponge (Terudermis, Terumo, Tokyo) to such wounds has previously been reported to accelerate granulation tissue formation, resulting in would healing and graft survival. However, this previous report only presented data relating to gross morphological appearance. In this paper, we present histological evidence to demonstrate the beneficial effect of the collagen sponge on experimental dermo-periosteal scalp defects in rabbits. About two weeks after the application of collagen sponge to the experimental wounds, a well-vascularized granulation tissue was formed. Autologous split-thickness skin grafts applied to this new granulation tissue were found to be viable one week after grafting. The results confirm histologically that collagen sponge is effective for the treatment of deep dermo-periosteal defects which would not have regenerated skin cover with conventional therapies such as skin grafting or the temporary use of dermoprotective materials followed by skin grafting.

Functional diffusive/convective interaction determining maximal oxygen uptake in humans: its modeling perspective

In this short review, the frame of current understandings concerning what determines the upper limit of oxygen flow from the ambient air to the muscular mitochondria during maximal dynamic exercise in humans (i.e., VO2max), was summarized mainly from its modeling perspective. Several models and experimental evidences which appeared repeatedly in the recent debates regarding the factors limiting VO2max, were adopted and criticized. In conclusion, VO2max is determined in particular by the integrated interaction between the diffusive and convective factors both to lung O2-loading and muscular O2-unloading in the pathway for O2 flow, although all experimental observations cannot be satisfactorily explained at the present time.

Fatal diarrhea in a patient with Castleman's disease associated with intestinal amyloidosis

A 32-year-old woman presented with Castleman's disease associated with intestinal amyloidosis. The association of amyloidosis and Castleman's disease is very rare, with only 15 cases reported in the literature. To our knowledge, this is the second case in which persistent diarrhea and malnutrition led to the patient's death.

The reducing ability of iron chelates by NADH-cytochrome B5 reductase or cytochrome B5 responsible for NADH-supported lipid peroxidation

We studied iron reduction, NADH oxidation, and lipid peroxidation in the presence of iron chelates with a chelator, such as nitrilotriacetate, ADP, citrate, and pyrophosphate, in NADH-supported reconstituted system. The results showed the selectivity of NADH-cytochrome b5 reductase or cytochrome b5 towards iron chelates and the subsequent ability of this system to promote peroxidation. The lipid peroxidation was partially inhibited by superoxide dismutase. In the presence of any iron chelate, hydrogen peroxide was produced in the systems including the reductase, and the production was accompanied with an increase in NADH oxidation.

The enhancement of cellular infiltration and vascularisation of a collagenous dermal implant in the rat by platelet-derived growth factor BB

The implantation of collagen-based dermal substitutes offers one means of management of full-thickness skin lesions. We have examined the effect of the recombinant BB homodimer of platelet-derived growth factor (rPDGF-BB) on the extent of cellular infiltration and vascularisation of collagen sponges implanted into full-thickness excision wounds in rats. Histological examination of sponges excised 14 and 21 days post-implantation in dose-response studies in which 0-4 micrograms rPDGF-BB were applied to the undersurface of each sponge, immediately prior to its implantation, demonstrated a progressively increased infiltration of host cells, especially fibroblasts, and enhanced capillary formation. With 4 micrograms rPDGF-BB, an enhanced infiltration of fibroblasts into sponges was already apparent 3 days post-implantation, and enhanced capillary formation was noticeable after 7 days. This neovascularisation was noted to be associated with improved survival of autologous split-thickness skin grafts applied to the sponges immediately following their implantation.

A possible involvement of sodium channel blockade of class-I-type antiarrhythmic agents in postischemic contractile recovery of isolated, perfused hearts

The present study was undertaken to test the hypothesis that the degree of sodium channel blockade by class-I-type antiarrhythmic agents accounts for enhancement of postischemic contractile recovery of ischemic/reperfused hearts. Electrophysiological studies showed that the class-I-type antiarrhythmic agents quinidine, disopyramide, procainamide, lidocaine, mexiletine, flecainide and pilsicainide suppressed the Vmax value of the rat left ventricular muscle cell, a marker of sodium channel blockade, in a concentration-dependent manner. Isolated rat hearts were subjected to 35 min of ischemia and 60 min of reperfusion. Postischemic contractile recovery, which was never detected in untreated hearts, was enhanced in hearts pretreated with these antiarrhythmic agents during the last 3 min before ischemia at concentrations ranging from 3 to 300 microM. Tissue Na, but not Ca, accumulation was also detected in the ischemic heart, and tissue Na and Ca accumulation was observed in the reperfused heart, which suggests that sodium overload occurs during ischemia, followed by sodium and calcium overload during reperfusion. The degree of postischemic contractile recovery seen in the presence of these antiarrhythmic agents was inversely related to tissue Na or Ca accumulation after reperfusion, which suggests that class-I-type antiarrhythmic agents inhibit sodium overload occurring in ischemic/reperfused myocardial cells. A close relationship between postischemic contractile recovery of the perfused heart and depression in the Vmax value of the ventricular muscle was also observed. These results suggest that the ability class-I-type antiarrhythmic agents to inhibit myocardial sodium channels plays a significant role in the enhancement of postischemic contractile recovery of the ischemic/reperfused heart.

Enhancement of norepinephrine and angiotensin II-induced renal effects by NG-nitro-L-arginine, a nitric oxide synthase inhibitor

We investigated whether endogenous nitric oxide (NO) has a role as an inhibitory modulator of norepinephrine (NE)- and angiotensin II (Ang II)-induced renal effects in anesthetized dogs. Intrarenal arterial infusion of NE (100 ng/kg/min) or Ang II (10 ng/kg/min) decreased renal blood flow (RBF), glomerular filtration rate (GFR) and urine formation. The NE- or Ang II-induced renal effects were augmented by the intrarenal administration of a NO synthase inhibitor, NG-nitro-L-arginine (NOARG), at doses (10 and 40 micrograms/kg/min) which did not affect the mean arterial blood pressure and heart rate. The stimulating activity of NOARG on NE- or Ang II-induced renal effects were abolished by the simultaneous administration of L-arginine, a NO precursor. These findings suggest that endogenous NO, which is probably generated within the kidney, functions as an inhibitory modulator in NE- or Ang II-induced renal vasoconstriction and antidiuresis.