Complement and polymorphonuclear leukocyte activation each play a role in determining myocardial ischemia-reperfusion injury.

Cobra venom factor (CVF) transiently activates polymorphonuclear leukocytes (PMN) by complement activation, followed by rapid complement depletion and gradual reversal of PMN activation. Utilizing these sequential changes caused by CVF, the individual and combined effects of complement and PMNs on myocardial infarct size (IS) were investigated. Rats were treated with CVF, and/or anti-PMNs. Complement was depleted, but circulating PMNs were being activated at 4h after CVF administration, and at 36h after, complement was depleted, but PMNs were in a near basal condition. Under anesthesia, the rats had a 30-min coronary occlusion followed by 6h of reperfusion. The IS was assessed by tetrazolium staining. CVF, as well as anti-PMNs, reduced myeloperoxidase (MPO) activity in the risk area and the reduced MPO resulted in a reduced IS, which was also the effect of anti-PMNs, but complement depletion by CVF, during which circulating PMNs were activated, failed to reduce the IS despite low MPO activity. These results suggest that complement and the condition of PMNs each play a role in determining the IS, and ischemic reperfusion injury might be produced even by relatively low myocardial MPO activity.

Continuous observation of superoxide generation in an in-situ ischemia-reperfusion rat lung model.

To investigate the time course of superoxide generation in ischemia-reperfusion in the in-vivo rat lung, the present study used an enhanced chemiluminescence method with 2-methyl-6-[p-methoxyphenyl]-3,7-dihydroimidazo[1, 2-alpha]pyrazin-3-one (MCLA) as a specific probe. The right pulmonary artery was occluded for 120 min, followed by 90-min reperfusion. Chemiluminescence induced by MCLA was continuously monitored by a photomultiplier exposed to the right lung. Chemiluminescence increased gradually in 30 min of reperfusion and remained elevated throughout reperfusion. The ratio of the luminescence count during reperfusion to the preischemic value increased to 2.20+/-0.31 (mean+/-SEM) (p<0.02 vs preischemic level), 2.50+/-0.39 (p<0.005), and 2.69+/-0.44 (p<0.005), at 30, 60, and 90 min of reperfusion, respectively. Bolus administration of superoxide dismutase during the reperfusion period significantly attenuated the chemiluminescence by 45.0+/-6.7% (p<0.01). The present results suggest that increasing oxygen radical formation leading to ischemia-reperfusion lung injury may occur even after a short period of occlusion of the pulmonary artery alone in vivo.

Expression of bone morphogenetic proteins and rat distal-less homolog genes following rat femoral fracture.

Expression of the genes encoding bone morphogenetic proteins (BMPs), BMP type IA receptor (BMPR-1A), and rat distal-less homolog (rDlx) was studied in bone, callus, and the surrounding soft tissue following rat femoral closed fracture, using RT-PCR-based techniques. Before fracture, the genes encoding BMP-5, BMP-6, and BMPR-1A were found to be expressed in both bone and the surrounding soft tissue, whereas the BMP-2 gene was expressed only in bone and BMP-7 was not expressed in either tissue. Expression of these genes was unaffected by fracture. The gene encoding BMP-4 was also expressed in both bone and the surrounding soft tissue before fracture. Moreover, although unchanged in bone, 6 h after fracture BMP-4 expression was increased tenfold in the surrounding soft tissue. The increased BMP-4 expression was transient and returned to prefracture levels within 72 h. Expression of rDlx was also increased in bone after fracture, but at later times than were observed with BMP-4: elevated rDlx expression was detected after 48 h and persisted for 30 days or more. No expression of rDlx was observed in the surrounding soft tissue before or after fracture. These findings indicate that BMP-4 and rDlx are selectively expressed following femoral fracture in the rat, and also suggest that they are involved in the formation of the callus at an early point during the postfracture healing of bone.

Apoptosis in relevant clinical situations: contribution of apoptosis in myocardial infarction.

Myocardial infarction is associated with increased TUNEL-positivity in cardiac resident and infiltrated cells. Apoptosis of proliferated interstitial myofibroblasts and infiltrated inflammatory cells may have a role in terminating tissue repair processes after infarction. Lateral and endocardial border zones of infarction within the risk area have frequent appearance of TUNEL-positive cardiomyocytes. Although the typical ultrastructural morphology of apoptosis has rarely been detected in ischaemic cardiomyocytes, there are many reports in which the TUNEL method was used for assessment of cardiomyocyte apoptosis. It has become evident that TUNEL-positivity reflects a wide range of cellular conditions; viable cells undergoing DNA repair, apoptosis, and necrosis. Therefore, it is controversial whether TUNEL-positive cardiomyocytes in infarcted myocardium are all apoptotic. Methods which will be more specific for identifying apoptosis are required for future study. TUNEL-positivity can be attenuated by anti-apoptotic interventions such as inhibition of caspases, mitochondrial protection, free radical scavenging, and some conventional pharmacotherapies. However, it remains to be determined whether anti-apoptotic interventions result in satisfactory reduction of infarct size. The injurious impact of myocardial ischaemia comes from a mixture of pro-apoptotic and necrosis-promoting signals, and the target of both signals is mitochondria. Through a common pathway they may cause permeability transition. Interventions which act only at the post-mitochondrial stage of apoptosis may fail to reduce infarct size, whereas those acting at pre-mitochondrial and mitochondrial stages may reduce infarct size. Progress in investigating the basic mechanisms of apoptosis and recognition of the modes of cardiomyocytes death will contribute to advances in cardioprotective therapy in myocardial infarction.

Therapeutic advantage of angiotensin converting enzyme inhibitors in chronic glomerulonephritis.

Hypertension in chronic progressive renal disease is a major clinical problem leading to renal function loss. We studied the influence of ambulatory blood pressure (ABP) and the effect of hypertension therapy on renal function in 116 patients with chronic glomerulonephritis. Patients were subdivided as hypertensive, normotensive and hypotensive according to the level of ABP and age. Hypotensive subjects showed improvement of renal function and normotensive subjects showed slower rate of progression of renal function loss than hypertensives, suggesting the adequate level of ABP was 100-125/55-75 mm Hg in patients less than 40 years old, 100-135/60-80 mm Hg in patients 40-60 years old, and 105-140/60-85 mm Hg in patients over 60 years, respectively. The renal protection of calcium antagonists was associated with achieving lower blood pressure levels, whereas the blood pressure level did not affect progression of renal function in patient treated with angiotensin converting enzyme (ACE) inhibitor. ACE inhibitor, but not calcium antagonists, showed a reduction of urinary protein excretion. Thus, the mechanisms of renal protection were different between ACE inhibitors and calcium antagonists.

[Effect of adenosine on isolated afferent arterioles].

We investigated the direct effect of adenosine on afferent arterioles (Af-Arts) and the receptor subtype that mediates the constrictor or dilator action of adenosine. Af-Arts were isolated from the superficial cortex of rabbit kidney and perfused in vitro. Adenosine added to either the lumen or bath constricted the Af-Arts in a dose-dependent manner. This constriction was blocked by the A1 receptor antagonist, 6-oxo-3-(2-phenylpyrazole(1,5-a)pyridin-3-yl)-1 (6H)-pyridazinebutyric acid (FK838) or 8-cyclopentyl-1, 3-dipropylxanthine(DPCPX). We also examined the effect of adenosine on preconstricted Af-Arts with norepinephrine. Adenosine added to either the lumen or bath further constricted the preconstricted Af-Arts. In the presence of FK838, adenosine added to either the lumen or bath dilated the preconstricted Af-Arts, but in a different dose-dependent manner. Adenosine-induced dilation was inhibited by the A2 receptor antagonist, 3, 7-dimetyl-1-propargylxanthine(DMPX). These data indicate that adenosine constricts Af-Arts via A1 receptors and that adenosine dilates preconstricted Af-Arts via A2 receptors when A1 receptors are blocked.

Bullous pemphigoid IgG2 and IgG4 antibodies have a capability to inhibit a transient increase of intracellular Ca2+ induced by bullous pemphigoid IgG1 antibody.

To elucidate the role of Bullous pemphigoid (BP) IgG subclasses in the transmembrane signal transduction of keratinocytes, we examined whether BP IgG2 or IgG4 inhibits the intracellular Ca2+ concentration ([Ca2+]i) increase induced by BP IgG1. IgG2 from one of five BP patients inhibited the increase of [Ca2+]i in human squamous cell carcinoma cell line; DJM-1 cells induced by BP IgG1. IgG4 from two of four BP patients inhibited the increase of [Ca2+]i induced by BP IgG1. In addition, a two fold quantity of IgG2 inhibited the increase of [Ca2+]i induced by BP IgG1. A two fold quantity of IgG4 from two of five BP patients inhibited the increase of [Ca2+]i induced by BP IgG1. These results indicate that BP IgG2 and IgG4 have a capability to inhibit the increase of [Ca2+]i induced by BP IgG1.

Local injection of recombinant human stem cell factor promotes human skin mast cell survival and neurofibroma cell proliferation in the transplanted neurofibroma in nude mice.

We studied the effects of stem cell factor (SCF) on human skin mast cell (HSMC) survival and the proliferation of neurofibroma (NF) cells in transplanted NF in nude mice. Small pieces of cutaneous NF from a patient with von Recklinghausen's disease were transplanted subcutaneously into nude mice. Recombinant human SCF (10 or 100 ng) was injected six or seven times around the NF transplantation sites over 11 days (i.e. every other day). The number of HSMCs was reduced in vehicle-injected NF compared to the amount present before transplantation. In contrast, NF-transplanted animals that were injected with SCF (10 or 100 ng) showed preservation of mast cell numbers in the tissue. Using computerized image analysis, mast cell size in SCF-treated NF transplants was significantly altered (larger at the 10 ng dose, and smaller at the 100 ng dose) compared with the size before transplantation or in vehicle-injected tissue. Furthermore, at the higher SCF dose (100 ng) PCNA-positive NF cells showed a significant increase. These results indicate that HSMCs in transplanted NF tissue retain their capacity to respond to SCF in vivo, and that SCF contributes to the regulation of both HSMC survival and size in cutaneous NF. In addition, activated HSMCs induced by SCF may be involved in the growth of cutaneous NF in von Recklinghausen's disease. Thus, this experimental model may be useful in the study of the cellular interactions between HSMCs and other stromal cells in cutaneous NF.

Cytotoxicity and mutagenicity of UVB assessed using cultured rat fibroblast.

A retroviral vector carrying both positive (neo) and negative (herpes simplex virus thymidine kinase or HSV-tk) selection markers was constructed as a substrate for mutational assay in mammalian cells. Using a population of rat fibroblast cells carrying a single copy per cell of retroviral DNA randomly integrated in their chromosomes, we examined the cytotoxic and mutagenic activities of ultraviolet light (UV) at four wavelengths (254, 290, 300, and 320 nm). The action spectra for these activities are similar to some of the previously reported spectra for photochemical DNA modifications, erythema, cell killing, and mouse skin carcinogenesis, except at 290 and 320 nm. At 290 nm, no significant mutagenicity was observed. At 320 nm, both cytotoxic and mutagenic activities were 10 times higher than the values expected from the absorption spectrum for DNA and the action spectrum for bacterial inactivation and mutagenesis. Structural comparison of some of the HSV-tk mutants obtained after irradiation with 300 and 320 nm UV revealed partially different patterns of mutation specificity, suggesting the involvement of multiple molecular mechanisms in the genotoxicity associated with this range of UV.

Vascular endothelial growth factor in angiosarcoma.

Angiosarcoma(AS) is a malignant tumour of the endothelium of lymphatic or blood vessels. Vascular endothelial growth factor (VEGF), a specific mitogen of endothelial cells, is considered essential for the growth of many tumours including AS. We have recently treated several patients with AS; in two of them, using a newly developed enzyme-linked immunosorbent assay (ELISA) for VEGF, we sequentially measured serum VEGF concentrations. While serial serum VEGF levels reflected tumour burden, the various VEGF concentrations were within the normal range we reported previously. Furthermore, the VEGF concentrations were not remarkably elevated in AS tumour tissue compared with benign vascular lesions and hypervascular tumours.

Vasodilation mediated by angiotensin II type 2 receptor is impaired in afferent arterioles of young spontaneously hypertensive rats.

Renal vasoconstrictor action of angiotensin II (Ang II) is exaggerated in the spontaneously hypertensive rat (SHR) before development of hypertension. We have recently demonstrated that in the rabbit afferent arteriole (Af-Art) activation of the AT2 receptor causes vasodilation, which modulates the vasoconstrictor action of Ang II mediated by the AT1 receptor. In this study, we tested the hypothesis that vasoconstrictor action of Ang II is exaggerated in SHR Af-Arts due to an impaired function of the AT2 receptor before development of hypertension. Af-Arts were microdissected from the superficial cortex of 4- to 5-week-old SHR or age-matched Wistar Kyoto rats (WKY), and perfused at 60 mm Hg in vitro. Ang II (10(-11) to 10(-8) M) decreased the luminal diameter of Af-Arts of both strains in a dose-dependent manner. However, the constriction was stronger in SHR; at 10(-10) M, the diameter decreased by 34 +/- 4% in SHR (n = 6) compared to 18 +/- 3% in WKY (n = 6; p < 0.01). Pretreatment with PD123319 (PD), an AT2 receptor antagonist, significantly augmented Ang II-induced constriction in WKY but not SHR Af-Arts; at 10(-10) M, the diameter now decreased by 41 +/- 5 and 37 +/- 1% in SHR (n = 6) and WKY (n = 6), respectively. Thus, blockade of the AT2 receptor abolished the difference in Ang II action on Af-Arts between strains. Moreover, with the AT1 receptor blockade Ang II caused dose-dependent dilation of preconstricted Af-Arts only in WKY (27 +/- 5% at 10(-8) M, n = 5), and the dilation was abolished by simultaneous treatment with PD. In contrast, no such dilation was observed in SHR Af-Arts. These results suggest that activation of the AT2 receptor modulates AT1 receptor vasoconstriction in WKY Af-Arts, while impaired modulatory function of AT2 receptor may play a role in the exaggerated vasoconstrictor action of Ang II on the Af-Art of prehypertensive SHR.

A case of an inflammatory variant of epidermolysis bullosa acquisita: chronic bullous dermatosis associated with nonscarring mucosal blisters and circulating IgG anti-type-VII-collagen antibody.

A 42-year-old man showed prominent blistering lesions of the mouth and esophagus in addition to a few bullous lesions of the skin. Direct immunofluorescence microscopy revealed distinct linear deposition of IgG and C3 at the epidermal basement membrane zone where slight deposition of IgA and IgM was also observed. In direct immunoelectron-microscopic examination, antibody was detected in the sublamina densa of the basement membrane zone. Immunoblot analysis with dermal extracts demonstrated that the patient's serum contained circulating IgG antibodies against the 290-kD protein, which comigrated with type VII collagen. The lesions healed without any scars. The results of these studies corresponded to the laboratory findings in epidermolysis bullosa acquisita (EBA), although the clinical features were distinct from classic EBA.

The vascular space-like structure in melanocytic nevus is not an injection artifact: report of a case and an experimental study.

Melanocytic nevi may microscopically associate with clefts or slits of the nests resembling lymphatic or vascular spaces. This unique histologic feature has been known as an artifact of injection or tissue-processing. We present a case of melanocytic nevus with a prominent vascular space-like structure. We also studied whether intralesional injection of local anesthetic could reproduce similar histologic findings. A 45-year-old Japanese female visited us with a solitary, brownish papule on the chest. Histology revealed numerous nests composed of round to oval-shaped nevus cells throughout the entire dermis. In the mid-dermis, nevus cells were lined up in a layer anastomosing and forming a vascular space-like structure. These nevus cells were uniformly stained with vimentin and S100 protein but not with factor VIII-related antigen. They were also positively immunoreactive with anti-type IV collagen and anti-fibronectin. There were no significant differences in staining intensity in the nevus cells between the solid portion and the vascular space-like structure. In the experimental study, eight melanocytic nevi were removed under local anesthesia. The local anesthetic solution was then injected into the excised nevus. Intralesional injection of a considerable volume of local anesthetic was capable of causing slits or clefts of the nests and dermal edema; however, it failed to reproduce a vascular space-like structure similar to that in the present case. These findings suggest that a vascular space-like structure in melanocytic nevus is not caused by the injection alone. Some other factor(s) may play a major role in the development of such structures in melanocytic nevus.

Attenuation of ischemia/reperfusion injury in rats by a caspase inhibitor.

BACKGROUND: Z-Val-Ala-Asp(OMe)-CH2F (ZVAD-fmk), a tripeptide inhibitor of the caspase interleukin-1beta-converting enzyme family of cysteine proteases, may reduce myocardial reperfusion injury in vivo by attenuating cardiomyocyte apoptosis within the ischemic area at risk. METHODS AND RESULTS: Sprague-Dawley rats were subjected to a 30-minute coronary occlusion followed by a 24-hour reperfusion. An inert vehicle (dimethylsulfoxide; group 1, n=8) or ZVAD-fmk, at a total dose of 3.3 mg/kg (group 2, n=8), was administered intravenously every 6 hours starting at 30 minutes before coronary occlusion until 24 hours of reperfusion. At this 24-hour point, hemodynamics were assessed by means of cardiac catheterization; then, the rats were killed, and the left ventricle was excised and sliced. The myocardial infarct size/ischemic area at risk and the count of presumed apoptotic cardiomyocytes (terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling [TUNEL]-positive cells) within the ischemic area at risk were assessed through triphenyltetrazolium chloride staining and TUNEL methods, respectively. Peak positive left ventricular dP/dt was higher (P=.02) and left ventricular end-diastolic pressure was lower (P=.04) in group 2 than in group 1. The infarct size/ischemic area at risk of group 2 (52.4+/-4.0%) was smaller (P=.02) than that of group 1 (66.6+/-3.7%), and TUNEL-positive cells were fewer (P=.0002) (group 2, 3.1+/-0.9%; group 1, 11.1+/-1.0%). Agarose gel electrophoresis revealed DNA laddering in the border zone myocardium of group 1, but DNA ladder formation was attenuated in group 2. CONCLUSIONS: ZVAD-fmk was effective in reducing myocardial reperfusion injury, which could at least be partially attributed to the attenuation of cardiomyocyte apoptosis.

Malignant schwannoma-derived cells support human skin mast cell survival in vitro.

We have recently observed mast cell infiltration in malignant schwannoma (MS) arising in the patient with von Recklinghausen's disease. To determine the cell to cell interactions between human skin mast cell (HSMC) and MS cell, we investigated the HSMC survival and the morphological changes when cultured with MS-derived cells isolated from the patient. Partially purified HSMCs obtained from normal adult skin and cutaneous neurofibroma by enzymatic digestion were cocultured with MS-derived cells on the coverslips. The number of HSMCs stained with crystal violet were directly counted by light microscope. HSMCs cocultured with MS-derived cell feeder layer revealed significantly increased HSMC survival compared to that with normal human skin fibroblast layer at 1 and 2 weeks. Conditioned medium of cultured MS-derived cell did not influence HSMC survival. In the morphology HSMCs cultured with MS-derived cells demonstrated spindle form in close contact with the adjacent MS-derived cells, suggesting cell to cell interactions. We failed to detect stem cell factor (SCF) mRNA in cultured MS-derived cell by RT-PCR. These results suggest that MS-derived cell is capable of supporting HSMC survival in vitro. Some factor(s) other than SCF, which is associated with direct contact between HSMCs and MS-derived cells, might relate to these observations.

Immunocytochemical characterization of malignant schwannoma-derived cells in culture.

We recently demonstrated that cultured malignant schwannoma (MS)-derived cells can support human skin mast cell (HSMC) survival in vitro. Cultured HSMCs were spindleshaped in close contract with MS-derived cells, suggesting cell to cell interaction. To elucidate the mechanism of the enhanced HSMC survival in coculture with MS-derived cells and the cellular interactions between HSMC and MS-derived cells, we examined the immunocytochemical characteristics of MS-derived cells using immunofluorescence. Morphologically, cultured MS-derived cells were polygonal with abundant cytoplasm and resembled perineurial cells. The cultured cells immunoreacted positively with vimentin, fibronectin, laminin and collagen IV, but negatively with anti-S100 protein, anti-neuron specific enolase, and anti-neurofilament (68 kd, 145 kd, 200 kd) antibodies. MS-derived cells were distinct from Schwann cells in their lack of S100 protein and also distinguishable from endoneurial fibroblasts that produce fibronectin, but never expressed laminin or collagen IV. MS-derived cells thus possess the characteristics of perineurial cells in their general morphology and their immunocytochemical properties. Immunoreactivity for substance P (SP) and neurokinin A (NKA) was found in the cytoplasm of these cells, particularly around the nuclei. Vasoactive intestinal peptide, somatostatin, and calcitonin gene related peptide were negative. From these findings, we characterized the MS-derived cell's in vitro properties and concluded that it is similar to a perineurial cell. The extracellular matrix protein, laminin, and fibronectin expressed in the MS-derived cell might contribute to HSMC survival and morphology through cell to matrix adhesion. Neuropeptides such as SP and NKA, expressed in the MS-derived cell, might play some role in enhanced HSMC survival in vitro.

Function of angiotensin II type 2 receptor in the postglomerular efferent arteriole.

The balance of vasucular tone between afferent (Af-Art) and efferent arterioles (Ef-Art) is a critical determinant of the glomerular hemodynamics. We recently reported that selective activation of angiotensin II type 2 receptor (AT-2R) causes dilation in the Af-Art. However, the functional role of AT-2R in the Ef-Art has not been defined. In the present study, we microperfused rabbit Ef-Art in vitro, and examined the effect of angiotensin II (Ang II; 10(-11) to 10(-8) M) on the luminal diameter in the presence or absence of an AT-2R antagonist PD123319 (PD; 10(-7) M). Angiotensin II caused dose-dependent constriction in Ef-Arts, with a significant constriction occurring at 10(-11) M; at 10(-10) M the diameter decreased by 28 +/- 4% (N = 6). Pretreatment with PD significantly (P < 0.0125) augmented vasoconstrictor action of Ang II; at 10(-10) M the diameter decreased by 44 +/- 4% (N = 6). We then examined whether blockade of Ang II type 1 receptor (AT-1R) uncovers vasodilator action of Ang II mediated by AT-2R. Efferent arterioles were preconstricted by about 40% with norepinephrine and AT-1R was blocked with its selective antagonist CV11974 (CV; 10(-8) M). Angiotensin II added to preconstricted and CV-pretreated Ef-Arts caused a dose-dependent dilation; at 10(-8) M diameter increased by 28 +/- 3% (N = 5). The dilation was completely abolished by simultaneous pretreatment with PD (N = 4). Our results demonstrate that in the Ef-Art selective activation of AT-2R causes vasodilation, which opposes the vasoconstrictor action of Ang II.

Possible role of P-450 metabolite of arachidonic acid in vasodilator mechanism of angiotensin II type 2 receptor in the isolated microperfused rabbit afferent arteriole.

Although angiotensin II type 2 (AT2) receptor has recently been cloned, its functional role is not well understood. We tested the hypothesis that selective activation of AT2 receptor causes vasodilation in the preglomerular afferent arteriole (Af-Art), a vascular segment that accounts for most of the preglomerular resistance. We microperfused rabbit Af-Arts at 60 mmHg in vitro, and examined the effect of angiotensin II (Ang II; 10(-11)-10(-8) M) on the luminal diameter in the presence or absence of the Ang II type 1 receptor antagonist CV11974 (CV; 10(-8) M). Ang II was added to both the bath and lumen of preconstricted Af-Arts. Ang II further constricted Af-Arts without CV (by 74+/-7% over the preconstricted level at 10(-8) M; P < 0.01, n = 7). In contrast, in the presence of CV, Ang II caused dose-dependent dilation; Ang II at 10(-8) M increased the diameter by 29+/-2% (n = 7, P < 0.01). This dilation was completely abolished by pretreatment with an AT2 receptor antagonist PD123319 (10(-7) M, n = 6), suggesting that activation of AT2 receptor causes vasodilation in Af-Arts. The dilation was unaffected by inhibiting either nitric oxide synthase (n = 7) or cyclooxygenase (n = 7), however, it was abolished by either disrupting the endothelium (n = 10) or inhibiting the cytochrome P-450 pathway, particularly the synthesis of epoxyeicosatrienoic acids (EETs, n = 7). These results suggest that in the Af-Art activation of the AT2 receptor may cause endothelium-dependent vasodilation via a cytochrome P-450 pathway, possibly by EETs.