bluuebunny/crossref_metadata_2025 huggingface dataset:
Hepatitis C Virus and Hepatocarcinogenesis
Authors: Hayashi Junpei , Aoki Hiroshi , Arakawa Yasuyuki , Hino Okio
Published: April 2003

Although human hepatocellular carcinoma (HCC) is one of the most common types of tumors in the world, the molecular mechanisms underlying hepatitis-C-related human hepatocarcinogenesis are still not clear. HCC is accompanied by virus infections in most cases, and it is suggested that hepatitis B virus and hepatitis C virus (HCV) significantly influence the oncogenic process. The persistence of inflammation following HCV infection is reportedly related to carcinogenesis, and the mechanism of chronic inflammation has been approached by taking viral, immunologic, cytokine and apoptotic responses into consideration. With the progress made in molecular biology, the functional abnormality of oncogenes/tumor suppressor genes has been identified and, apart from the p53 gene, involvement of the IGF-II gene has also been described recently. Furthermore, it has been suggested that uncontrolled proliferation of cancer cells might be based on abnormal regulation of intracellular signal transduction pathways. Here we review the cutting edge of molecular hepatitis C virology in terms of virus-cell interactions, which may contribute to the development of human HCCs. We also discuss the recent progress made in the molecular and cell biology of human hepatocarcinogenesis.
Hepatitis B Virus Mutants
Authors: Brunetto Maurizia Rossana , Rodriguez Ulisses Aragon , Bonino Ferruccio
Published: April 2003

During hepatitis B virus (HBV) infection, selection and takeover of mutant viruses are frequent events driven by both humoral and cellular host-immune response and antiviral therapy. Therefore, dynamic studies of the variations of viral mutants over time within the overall viral population in relation with the host-virus interactions are extremely important to better understand the biological and pathogenic role of each mutant. With these premises, we review the more frequent mutations detected in each of the 4 open reading frames of HBV. A detailed analysis of the pathobiologic implications of pre-C region mutations which suppress the expression of the hepatitis B ‘e’ antigen, will be presented, as these mutations induce a specific change in virus biology and the variations of the ratio between wild-type and mutant correlate with significant events in host-virus interactions.
GB Virus C/Hepatitis G Virus
Authors: Kiyosawa Kendo , Tanaka Eiji
Published: April 2003

Hepatitis G virus (HGV) is a positive, single-strand RNA virus that has been classified in the family Flaviviridae. The 5′-untranslated region (UTR) of the HGV genome is lengthy and does not share any significant primary and secondary RNA structures with the 5′-UTR of hepatitis C virus (HCV). The internal ribosome entry site has extraordinarily weak activity. The HGV genome does not seem to encode a nucleocapside protein analogous to HCV. Blood-borne transmission is presumed to be the commonest mode of transmission of the virus. Current infection with HGV is diagnosed by detection of HGV RNA by the polymerase chain reaction (PCR), and past infection with HGV is detectable by testing anti-HGV E2. HGV is distributed worldwide, but its prevalence varies widely from one population to another. Although the prevalence of HGV in association with acute and chronic hepatitis is higher than that in the general population, further prospective studies are needed to demonstrate its relative significance in causing hepatitis and other disease. The major unresolved biological issue at the moment is its hepatotropsim and site of propagation. Recent progress demonstrates that HGV replicates in lymphocytes rather than hepatocytes. HGV may be pathogenic under special conditions, but does not influence carcinogenesis.
Efficacy of an Inactivated Vaccine for Equine Herpesvirus Type 1 in a Novel Hamster Model
Authors: Skinner G.R.B. , Davies J.
Published: April 2003

A vaccine designated F.EHV1(S–)BHK, which was prepared by formaldehyde treatment of equine herpesvirus type 1 (EHV1)-infected baby hamster kidney cells, stimulated neutralising antibodies in hamsters and rabbits and protected new-born hamsters against a lethal challenge with EHV1 by vaccination of their pregnant mothers. The preparative method was then modified to eliminate virus particles and intraparticulate DNA, producing a vaccine designated Bg.F.EHV1(S–)BHK. this modification stimulated neutralising antibodies with evidence of in vivo inactivation of the virus above non-specific levels in a mouse model. There were no adverse effects from these vaccines in rodent or rabbit species.
Phylogenetic Comparison of the DEN-2 Mexican Isolate with Other Flaviviruses
Authors: Ruiz B.H. , Sánchez I. , Ortega G. , López I. , Rosales L. , Medina G.
Published: April 2003

Recent attention has focused on the geographic variation of dengue viruses, since major epidemies may follow introduction of a new virus strain into susceptible populations. We cloned and sequenced a very interesting Mexican isolate (200787/1983) which is antigenically unique by signature analysis with respect to all other dengue-2 topotype viruses. This strain is also unique in biological behavior (neurotropism) and is of epidemiological significance in Mexico. The dengue-2 Mexican isolate sequence information was compared with that of other flaviviruses, analyzing the branching structure of the phylogenetic tree reconstructed from the E gene amino acid sequences. The E glycoprotein, is target for neutralizing antibodies and T-cell responses, and defines the tropism and virulence of flaviviruses. In the phylogram, our strain was located in the position of greatest dissimilarity within serotype-2. Also, frequency analysis of amino acids revealed a very different signature pattern from that found in viral serotype-2.
Efficient Diagnosis of Dengue Infections Using Patients’ Peripheral Blood Leukocytes and Serum/Plasma
Authors: Wang H.L. , Lin K.H. , Yueh Y.Y. , Chow L. , Wu Y.C. , Chen H.Y. , Sheu M.M. , Chen W.J.
Published: April 2003

Objective: Dengue fever has been one of the most important health problems in Taiwan since a large outbreak during 1987 and 1988. It is critically necessary to have a diagnostic approach that can detect early infections in an outbreak or even find infections existing in silent transmission of the disease. Methods: To develop an efficient diagnostic protocol, 105 plasma/serum and 35 peripheral blood leukocyte (PBL) specimens from the 1994 outbreak in southern Taiwan were collected for assessment by various diagnostic techniques in this study. Results: In acute blood samples, dengue viruses were isolated from 19.4% (14/72) and 33.3% (14/42) of reported and confirmed cases, respectively. Viral RNA in serum/plasma was detected from 20.0% (12/60) of acute samples, which was significantly higher than that from convalescent samples (3/44; 6.8%). However, viral RNA in PBLs, detected by reverse transcription polymerase chain reaction (PBL-RT-PCR), could be observed in 73.2% (19/26) and 66.7% (6/9) of acute and convalescent samples, respectively. The persistence of dengue viruses in PBLs was also evidenced by the presence of viral antigens in 42.9% (4/7) of confirmed convalescent samples by the immunofluorescence antibody test. In addition, IgM antibodies were detected in 43.8% (46/105) of reported cases and 85.2% (46/54) of confirmed cases by the IgM antibody capture enzyme-linked immunosorbent assay (MAC-ELISA). Conclusions: Although IgM antibody detection achieved the highest detection rate among techniques assessed in this study, no individual test can actually reach full efficiency for early diagnosis of dengue infections. Here, we propose a protocol which applies MAC-ELISA and PBL-RT-PCR in sequence, by which 22 confirmed cases were definitely proved as dengue positive. High levels of both sensitivity and specificity were shown in this protocol.
Calcium-Dependent Phospholipase A2 Mediates the Production of Endothelium-Derived Hyperpolarizing Factor in Perfused Rat Mesenteric Prearteriolar Bed
Authors: Adeagbo Ayotunde S.O. , Henzel Mary K.
Published: April 2003

The isolated, perfused rat mesenteric bed releases a cytochrome P450-linked metabolite of arachidonic acid (AA) as endothelium-derived hyperpolarizing factor (EDHF) in response to acetylcholine and histamine. This study assessed the relative contribution of two AA-generating pathways, phospholipase A2 (PLA2) and diacylglycerol (DAG) lipase, to EDHF-mediated dilation of the rat mesenteric bed. We tested the hypothesis that PLA2-mediated release of AA is essential for the production of EDHF. Mesenteric beds were perfused with physiological salt solution (PSS) containing indomethacin and nitro-L-arginine methyl ester to block cyclooxygenase and nitric oxide synthase, respectively, and constricted with cirazoline (an α1-adrenoceptor agonist). Bolus applications of acetylcholine and histamine caused dose-dependent dilation of the constricted beds. The 85-kDa PLA2 inhibitor, arachidonyl trifluoromethyl ketone (AACOCF3), at 3 µM, profoundly blunted decreases in perfusion pressure initiated by 1 nmol acetylcholine (94.3 ± 1.7%) and by 100 nmol histamine (88.5 ± 3.3%) to 9.6 ± 7.5 and 8.6 ± 6.0%, respectively. AACOCF3 also blocked cirazoline-stimulated release of 6-keto-PG1α, but did not alter the vasodilation initiated by sodium nitroprusside (a nitric oxide donor), cromakalim (a K+ channel activator), or by Na+/K+-ATPase activation, as measured by KCl vasodilation in preconstricted beds perfused with K+-free PSS. The 14-kDa PLA2 inhibitor, oleyloxyethyl phosphorylcholine, also blocked EDHF vasodilation and also significantly inhibited K+ channel activity. Neither the Ca2+-independent PLA2 inhibitor, HELSS [E-6-(bromomethylene)-tetrahydro-3-(1-naphthalenyl)-2H-pyran-2-one], nor DAG lipase inhibitor, RHC-80267 [1,6-bis-(cyclohexyloximino-carbonylamino)-hexane] altered EDHF-mediated vasodilation. However, RHC-80267 blocked cirazoline-stimulated release of 6-keto-PGF1α. We conclude that Ca2+-dependent PLA2, rather than DAG lipase, generates the AA for the production of EDHF in the perfused rat mesenteric bed.
Expression of Membrane-Type Matrix Metalloproteinase in Rabbit Neointimal Tissue and Its Correlation with Matrix-Metalloproteinase-2 Activation
Authors: Wang He , Keiser Joan A.
Published: April 2003

Smooth muscle cell (SMC) phenotypic alteration, followed by migration and proliferation, is a prominent feature of atherogenesis and vascular neointimal formation. Despite extensive research, mechanism(s) responsible for this alteration remain unclear. Recently, matrix metalloproteinases (MMP), a family of potent proteinases, have been implicated in vascular diseases by way of extracellular matrix degradation. Of particular interest is that expression of a 72-kD MMP (MMP-2) is elevated in neointima, and inhibition of this MMP results in reduced SMC migration and proliferation, suggesting a role for MMP-2 in neointimal development. However, MMP-2 needs activation before digesting protein; the mechanism of this activation in the arterial wall is largely unexplored. A novel membrane-type MMP termed MT-MMP-1 has recently been identified, and its expression in tumor cells is concomitant with MMP-2 activation. Transfection of this MMP cDNA into mammalian cells results in activation of MMP-2. However, the importance of this MMP in various pathological situations is not clear. The present study was designed to explore the relationship between MT-MMP-1 expression and MMP-2 activation during rabbit neointimal development. Using polymerase chain reaction, we isolated a rabbit cDNA from arterial SMC; sequence analysis indicated that it is a rabbit form of MT-MMP-1. A segment of this cDNA was subcloned into pGEM-3 and employed to synthesize a DIG-labeled RNA probe. This probe was then used in the Northern blot analysis for MT-MMP-1 mRNA expression both in aortic tissue and in neointimal tissues developed 3, 7, 14 and 21 days after balloon catheter de-endothelialization. The results show low-level expression of MT-MMP-1 in the normal aortic wall; expression is significantly increased in the neointimal tissues, with peak expression observed in tissues 3 days after injury. Expression of active MMP-2 was also determined using gel zymography. A close temporal expression pattern was observed between MT-MMP-1 and active MMP-2. These data verify the expression of MT-MMP-1 in arterial SMC and suggest its importance in MMP-2 activation after balloon catheter de-endothelialization.
Effects of Chemical Sympathectomy on Angiotensin II-Induced Neointimal Growth in the Balloon-Injured Rat Carotid Artery
Authors: Bruijns Richard H.J. , van Kleef Ellen M. , Smits Jos F.M. , De Mey Jo G.R. , Daemen Mat J.A.P.
Published: April 2003

To investigate the role of the sympathetic nervous system in angiotensin II (AngII)-stimulated medial and neointimal smooth muscle cell (SMC) replication, we sympathectomized rats with 6-hydroxydopamine (6-OHDA) in which the left carotid artery was injured by a balloon catheter. Balloon injury is associated with a loss of specific [3H]-prazosin binding. AngII (250 ng/kg/min), infused 2 weeks after balloon injury of the rat left carotid artery, increased systolic blood pressure by approximately 70 mm Hg. There was no effect of 6-OHDA on this pressor response. AngII increased the cumulative 5-bromo-2′-deoxyuridine (BrdU) labeling fraction (LF) in the uninjured right carotid media and the injured left carotid neointima as compared to controls (5.7 ± 1.6% vs. 0.4 ± 0.1%, p < 0.05; 10.6 ± 0.9% vs. 5.0 ± 0.8%, p < 0.05, respectively). 6-OHDA decreased the AngII-induced increase in LF in the media of the uninjured right carotid artery (AngII/6-OHDA 0.9 ± 0.2% vs. AngII 5.7 ± 1.6%, p < 0.05). 6-OHDA did not decrease the AngII-induced increase in LF in both the injured left carotid media and neointima at 4 weeks after balloon injury. The effects of chemical sympathectomy were comparable with those obtained 12 weeks after balloon injury. Thus, the data show that the sympathetic nervous system mediates the AngII-induced increase in SMC DNA synthesis, but only in the uninjured carotid media. This indicates a differential regulation of AngII-induced SMC replication in injured and uninjured vessels.
Intracellular Application of Calmidazolium Increases Ca2+ Current through Activation of Protein Kinase A in Cultured Vascular Smooth Muscle Cells
Authors: Sunagawa Masanori , Yokoshiki Hisashi , Seki Takashi , Sperelakis Nicholas
Published: April 2003

In the present study, we investigated the actions of calmodulin (CaM) and CaM-dependent protein kinase II (CaMK-II) on the L-type Ca2+ currents (ICa(L)) of cultured vascular smooth muscle (VSM) cells (A7r5 cell line), using the whole-cell voltage clamp method. The peak IBa (Ca2+ channel using 5 mM Ba2+ as charge carrier) was evoked every 15 s by a test potential to +10 mV from a holding potential of –60 mV. To test the effect of CaM on IBa, 1 µM calmidazolium (CMZ), an inhibitor of CaM, was added to the pipette solution (pCa of 6.5 or 300 nM [Ca]i). The amplitude of maximally activated IBa was –4.3 ± 0.5 pA/pF (n = 13) for control and –8.1 ± 0.9 pA/pF (n = 14) in the presence of CMZ. This difference was statistically significant (p = 0.016). The CMZ stimulation of IBa was not abolished when 5 µM KN-62, a specific inhibitor of CaMK-II, was included in the pipette (–9.5 ± 1.1 pA/pF; n = 10). Introduction of CaMK-II itself intracellularly had no effect on the basal IBa. On the other hand, the CMZ stimulation of IBa was prevented by both H-7, a nonspecific protein kinase inhibitor, and H-89, a specific inhibitor of protein kinase A (PK-A). Since CMZ is a strong inhibitor of Ca2+/CaM-dependent phosphodiesterase (type I PDE), we studied the effect of 8-methoxymethyl-3-isobutyl-1-methylxanthine (MIBMX), another specific inhibitor of the PDE. MIBMX, like CMZ, stimulated IBa: control, –4.6 ± 0.4 pA/pF (n = 10); MIBMX, –9.6 ± 1.2 (n = 8), and CMZ, –7.9 ± 0.9 (n = 15). 0.1 mM 8Br-cAMP, a membrane permeable cAMP analogue, stimulated IBa by +42%: before, –3.7 ± 0.7 pA/pF; after, –5.2 ± 1.0 (n = 6). In conclusion, Ca2+ channels of VSM cells might not be directly regulated by the CaM/CaMK-II pathway. Therefore, the CMZ stimulation of IBa might occur due to the increase in intracellular concentration of cAMP produced by inhibition of CaM-dependent PDE.
Vasodilation Mediated by Angiotensin II Type 2 Receptor Is Impaired in Afferent Arterioles of Young Spontaneously Hypertensive Rats
Authors: Endo Yoshimi , Arima Shuji , Yaoita Hiraku , Tsunoda Kazuo , Omata Ken , Ito Sadayoshi
Published: April 2003

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.
Developmental Biology of the Vascular Smooth Muscle Cell: Building a Multilayered Vessel Wall
Authors: Hungerford JillE. , Little CharlesD.
Published: April 2003

The assembly of the vessel wall from its cellular and extracellular matrix components is a critical process in the development and maturation of the cardiovascular system. However, fundamental questions concerning the origin of vessel wall cells and the mechanisms that regulate their development and differentiation remain unanswered. The initial step of vessel wall morphogenesis is formation of a primary vascular network, comprised of nascent endothelial cell tubes, via the processes of vasculogenesis and angiogenesis. Subsequently, primordial vascular smooth muscle cells (VSMCs) are recruited to the endothelium to form a multilayered vessel wall. During the course of development and maturation, the VSMC plays diverse roles: it is a biosynthetic, proliferative, and contractile component of the vessel wall. Although the field of vascular development has blossomed in the past decade, the molecules and mechanisms that regulate this developmental pathway are not well defined. The focus of this review is on those facets of VSMC development important for transforming a nascent endothelial tube into a multilayered structure. We discuss the primordial VSMC with particular attention to its purported origins, the components of the extracellular milieu that contribute to its development, and the contribution of embryonic hemodynamics to vessel wall assembly.
Role of Prostacyclin and Nitric Oxide in Regulation of Basal Microvascular Hydraulic Permeability in Cat Skeletal Muscle
Authors: Möller Alma D. , Grände Per-Olof
Published: April 2003

The effects of prostacyclin, nitric oxide (NO) and β2-receptor stimulation on capillary filtration coefficient (CFC) and vascular tone were analyzed in an autoperfused cat skeletal muscle in vivo preparation, to evaluate if these substances are involved in regulation of basal microvascular hydraulic permeability. CFC was increased from control (100%) to 124% with the prostacyclin-synthase inhibitor tranylcypromine and restored by simultaneous infusion of prostacyclin at 0.1 ng·kg–1· min–1, with further reduction to 76% at 1 ng· kg–1·min–1. Prostacyclin at these doses did not influence vascular tone. NO inhibition by L-NAME increased CFC to 116% of control, with a vascular resistance increase of 45%. CFC was restored by simultaneous infusion of the NO precursor L-arginine. L-arginine given alone reduced CFC to 86% of control. Tranylcypromine and L-NAME given together increased CFC to 141% of control and CFC was reduced to 86% by prostacyclin at 1 ng·kg–1·min–1 with no significant further reduction by adding L-arginine. Adrenaline alone, in a vasodilating dose verifying β2 stimulation, or when followed by simultaneous β-blockade with propranolol, did not influence CFC. We conclude that NO and especially prostacyclin are involved in bi-directional regulation of basal microvascular hydraulic permeability and can account for up to 30–40% increase or decrease from a basal value. Physiological β2 stimulation has no effect on basal hydraulic permeability. The permeability-reducing effects of prostacyclin and NO are additive. NO, but not prostacyclin, is involved in regulation of basal vascular tone.
Arterial Injury Increases Expression of Inflammatory Adhesion Molecules in the Carotid Arteries of Apolipoprotein-E-Deficient Mice1
Authors: Manka David R. , Wiegman Peter , Din Salah , Sanders John M. , Green Samuel A. , Gimple Lawrence W. , Ragosta Michael , Powers Eric R. , Ley Klaus , Sarembock Ian J.
Published: April 2003

Recent studies demonstrate increased cellular adhesion molecule expression by neointimal endothelium overlying primary and restenotic atherosclerotic plaque. In this study, we developed an atherosclerotic mouse model of arterial injury and characterized adhesion molecule expression after injury. Sixteen apolipoprotein-E-(ApoE)-deficient mice fed a Western-type diet for 4 weeks underwent carotid artery wire denudation at week 2. For each segment, the extent of neointima formation and medial thickening, or adhesion molecule expression, were scored separately on a scale from 0 (no plaque/thickening or expression) to 3 (extensive plaque/thickening or expression) using Movat staining (n = 3) or immunohistochemical analysis (n = 13). Histology revealed significant medial thickening (1.8 ± 0.9 vs. 0.3 ± 0.5, p < 0.001) versus controls and pronounced staining for monocytes/macrophages in the wall of injured vessels. Immunohistochemical analysis showed more robust expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) on the luminal surface of injured arteries versus controls (2.2 ± 0.6 vs. 1.4 ± 0.7, p < 0.01, and 2.5 ± 0.5 vs. 1.2 ± 0.6, p < 0.001, respectively). Injury increased adventitial ICAM-1 expression (2.6 ± 0.5 vs. 1.6 ± 0.5, p < 0.002) and medial VCAM-1 expression (2.2 ± 0.6 vs. 1.2 ± 0.7, p < 0.004). Thus, carotid injury results in significant medial thickening and increases adhesion molecule expression beyond that induced in ApoE-deficient mice fed a Western diet alone. The observation of macrophage infiltration into the media at sites of increased ICAM-1 and VCAM-1 expression suggests that these molecules may mediate monocyte/macrophage trafficking into the wall of injured arteries.
Size Dependence of Functional Alterations in Mesenteric Arteries from the Aldosterone-Salt Hypertensive Rat
Authors: Magliola Lawrence , Jones Allan W.
Published: April 2003

We tested the hypothesis that an elevated potassium-42 (42K+) efflux (highly dependent on Ca2+) and an increase in the sensitivity of contraction and 42K+ efflux to norepinephrine (NE) in conduit arteries of aldosterone-salt hypertensive rats (AHR) exended to smaller, distributing arteries. Functional endpoints were compared in two sizes of arteries from the mesenteric bed: second-order branches of the superior mesenteric artery (SMA branches) and the SMA. Contraction and free cytosolic Ca2+ concentration ([Ca2+]c; fura-2 microfluorometry) were measured simultaneously and 42K+ efflux was measured separately in SMA branches. Contraction and 42K+ efflux were measured separately in SMA. Basal tone, [Ca2+]c, and 42K+ efflux were similar in SMA branches from AHR and control-salt rats (CSR). However, basal 42K+ efflux was elevated in SMA from AHR compared to CSR. The sensitivity of the contractile, [Ca2+]c, and 42K+ efflux responses to NE was similar in SMA branches. In contrast, the sensitivity of the contractile and 42K+ efflux responses to NE was enhanced in SMA from AHR compared to CSR. Inhibiton of endothelium-derived vasoactive substances by pretreatment with Nω-nitro-L-arginine methyl ester and indomethacin significantly shifted the NE concentration-response relationships to the left for contraction, [Ca2+]c, and 42K+ efflux in both SMA branches and SMA from CSR. A similar shift to the left was observed in AHR for contraction but not consistently for [Ca2+]c and 42K+ efflux. We conclude that SMA branches from AHR demonstrate neither the elevated basal 42K+ efflux, nor the NE supersensitivity exhibited by SMA. Endothelial function was not impaired both in SMA and SMA branches.
Prostacyclin Reduces Microvascular Fluid Conductivity in Cat Skeletal Muscle through Opening of ATP-Dependent Potassium Channels
Authors: Bentzer Peter , Holbeck Staffan , Grände Per-Olof
Published: April 2003

Prostacyclin is suggested to reduce microvascular permeability, but the cellular mechanisms mediating this response in the microvascular endothelial cells are still unknown. Considering that prostacyclin relaxes vascular smooth muscle cells via opening of ATP-dependent potassium channels, and opening of ATP-dependent potassium channels in the endothelial cells is suggested to influence microvascular permeability, this study was designed to test (1) if ATP-dependent potassium channels are involved in the regulation of microvascular hydraulic permeability, (2) if the permeability-reducing effect of prostacyclin is mediated through opening of ATP-dependent potassium channels, and (3) if cAMP is involved in this process. An autoperfused cat calf hindlimb was used as experimental model, and microvascular hydraulic permeability (conductivity) was estimated by a capillary filtration coefficient (CFC) technique. The potassium channel opener PCO-400 (0.5 μg·min–1 per 100 g muscle, intra-arterially), prostacyclin (1 ng·min–1 per kg body weight, intravenously) and the cAMP analogue dibutyryl-cAMP (24 μg·min–1 per 100 g muscle, intra-arterially), decreased CFC to 77, 72 and 69% compared to control, respectively (p < 0.01). The decrease in CFC obtained by these substances was completely restituted after the start of a simultaneous infusion of the ATP-dependent potassium channel blocker glibenclamide (6 μg·min–1 per 100 g muscle, intra-arterially; p < 0.01). Infusion of glibenclamide alone increased CFC to 107% of control (p < 0.05). In conclusion, the ATP-dependent potassium channels contribute to the regulation of microvascular hydraulic conductivity, and the prostacyclin permeability-reducing effect may act through this mechanism via increase in intracellular cAMP.
Spontaneous Elastic Tissue Lesions in the Rat Abdominal Aorta, a Genetically Determined Phenotype
Authors: Jones Gregory T. , Harris Eugenie L. , Jacob Howard J. , van Rij André M.
Published: April 2003

In this study, phenotypic expression of spontaneous elastic laminae defects within the rat abdominal aorta was examined. Lesions in Brown Norway (BN) rats were compared with those of New Zealand genetically hypertensive (GH) rats. BN and GH rats were cross-bred to determine the phenotypic expression of these lesions in successive F1 and F2 generations. Lesions were assessed by distribution, number and a semiquantitative index of severity. All BN aortae contained numerous elastic tissue defects. In comparison, GH aortae contained only occasional elastic tissue lesions. F1 aortae contained lesions in numbers similar to those of the parental BN strain; however, F1 lesions were of significantly greater severity. Within the F2 generation, a wide range in both lesion numbers and severity indices was observed, with approximately a quarter of animals having lesion numbers analogous to the GH parental strain. In conclusion, this study indicates that the spontaneous elastic tissue lesions observed within BN rats are consistent with an autosomal dominant, possibly single gene, effect. Moreover, epistatic effects, derived from the GH strain, may influence the severity of these lesions. The gene(s) responsible may be important in the development of conditions such as arteriosclerosis and aneurysms in humans.
Can the Green Laser Doppler Measure Skin-Nutritive Perfusion in Patients with Peripheral Vascular Disease?
Authors: Ubbink Dirk T. , Tulevski Igor I. , Jacobs Michael J.H.M.
Published: April 2003

The recently developed green laser (GL; wavelength 543 nm) is thought to measure perfusion derived from a more superficial skin layer than does the standard near-infrared laser (RL; wavelength 780 nm). These lasers were used to investigate the disturbances in the different layers of skin perfusion in ischaemic legs before and after treatment and compared with capillary microscopy. Eighteen patients (20 legs) with different stages of leg ischaemia scheduled for a vascular intervention (11 males, 7 females; median age 73, range: 52–81 years; Fontaine stages II–IV) were investigated by means of capillary microscopy, visualising the nail fold capillary perfusion, and a laser Doppler, equipped with a special dual probe conducting both GL and RL. The probe was attached to the pulp and the dorsum of the big toe to assess skin perfusion at rest and during reactive hyperaemia, while sitting and while supine. Resting and hyperaemic perfusion using GL was low and significantly lower (p < 0.01) than with RL in both areas and positions. Laser Doppler perfusion was higher in the pulp than on the dorsum with both wavelengths (p < 0.05). The hyperaemia response was highest using GL and differed among the three techniques. Postural reduction of capillary and RL flow was reduced, but not with GL. After treatment, skin capillary perfusion improved more clearly than did the laser Doppler perfusion with either wavelength, while postural vasoconstriction improved only when measured with the capillary microscope. The differences found between RL and GL Doppler perfusion, but also between GL and capillary microscopy measurements suggest that the GL does measure the more superficial, but not exclusively the nutritive skin perfusion. Clinically, the use of the green laser in its present form in patients with leg ischaemia offers no advantage over the red laser.
The Synthetic Metalloproteinase Inhibitor Batimastat Suppresses Injury-Induced Phosphorylation of MAP Kinase ERK1/ERK2 and Phenotypic Modification of Arterial Smooth Muscle Cells in vitro
Authors: Lövdahl Cecilia , Thyberg Johan , Hultgårdh-Nilsson Anna
Published: April 2003

Smooth muscle cell (SMC) migration and proliferation are important events in the formation of intimal lesions associated with atherosclerosis and restenosis following balloon angioplasty. The extracellular matrix has important functions in modulating SMC structure and function, but less is known about the role of the matrix metalloproteinases (MMPs) and their endogenous tissue inhibitors. The present study investigates the effects of the synthetic MMP inhibitor batimastat (BB94) on vascular SMCs. As experimental model, rat aortic smooth muscle cells in primary and secondary cultures were employed. Electron microscopy was used to investigate the effects of BB94 on the overall phenotypic properties of the cells. Induction of DNA synthesis and migration was studied by thymidine autoradiography and counting of cells moving into an injured zone. Gelatin zymography was used for the detection of BB94-mediated inhibition of injury-induced MMP activity. Phosphorylation of the mitogen-activated protein kinases ERK1/ERK2, two potential mediators of the injury-induced activation of the cells, was measured by Western blotting. The results show that BB94 restrained the phenotypic modulation of vascular SMCs in primary cultures and suppressed injury-induced DNA synthesis and migration. Moreover, the upregulation of ERK1/ERK2 phosphorylation in injured secondary cultures and in cells treated with bFGF was markedly reduced by BB94, whereas TIMP-2 lacked a clear effect. Our data suggest that BB94 inhibits injury-induced activation of vascular SMCs by acting on MMPs as well as other targets.
Neurotrophins and Neurotrophin Receptors in Human Pulmonary Arteries
Authors: Ricci Alberto , Greco Stefania , Amenta Francesco , Bronzetti Elena , Felici Laura , Rossodivita Isidoro , Sabbatini Maurizio , Mariotta Salvatore
Published: April 2003

The localization of neurotrophins (NTs) and NT receptors was analyzed in sections of human extra- and intrapulmonary arteries by Western blot analysis and immunohistochemistry. In extrapulmonary branches of human pulmonary artery, NT and NT receptor immunoreactivity was located in the tunica intima, within endothelium, in the tunica media, within smooth muscle and in the tunica adventitia. In different sized intrapulmonary arteries, NT and NT receptor immunoreactivity was observed primarily in the tunica adventitia. A faint NT and NT receptor immunoreactivity was observed in the tunica media of large-sized branches of intrapulmonary arteries, but not within medium- or small-sized intrapulmonary vessels or in tunica intima of different sized intrapulmonary arteries. These findings suggest that NTs may have a role in the control of vascular responses in the pulmonary system acting as local paracrine or autocrine mediators. The possible relevance of the NT system in human pulmonary vasculature identified in this study is discussed.
Blockade of Smooth Muscle Cell Migration and Proliferation in Baboon Aortic Explants by Interleukin-1β and Tumor Necrosis Factor-α Is Nitric Oxide-Dependent and Nitric Oxide-Independent
Authors: Kenagy R.D. , Clowes A.W.
Published: April 2003

Interleukin-1β (IL-1β) and tumor necrosis factor-α (TNFα) are found in injured and atherosclerotic vessels and have been shown to influence smooth muscle cell (SMC) function in vitro. We have investigated the effects of IL-1β and TNFα on SMC migration and proliferation in baboon aortic explants, an in vitro model of arterial injury. Because platelet-derived growth factor (PDGF) is also present in the vessel wall, we have studied the interaction of PDGF with the cytokines. IL-1β and TNFα inhibited migration of SMCs and synthesis of DNA by SMCs. Cell death (terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling-positive cells and total DNA) was not altered by the cytokines. The cytokines increased levels of nitrite in the medium and L-nitroarginine partly reversed the inhibitory effects of the cytokines indicating a role for nitric oxide in these inhibitory effects. Treatment with indomethacin partially reversed the inhibition of migration, but not DNA synthesis by IL-1β suggesting cyclooxygenase products play an inhibitory role in migration. PDGF-BB reversed the inhibitory effect of the cytokines on SMC migration, but not mitogenesis, without changing levels of nitrite in the medium. These data show that IL-1β and TNFα decrease primate SMC migration and proliferation in arterial tissue partly through production of NO, and that PDGF antagonizes the effect of the cytokines. IL-1β and TNFα may act directly to limit injury-induced intimal hyperplasia by decreasing SMC migration and proliferation.
Atrial Natriuretic Peptide Enhances IL-1β-Stimulated Nitric Oxide Production in Cultured Rat Vascular Smooth Muscle Cells
Authors: Iimura Osamu , Kusano Eiji , Homma Sumiko , Takeda Shigeyuki , Ikeda Uichi , Shimada Kazuyuki , Asano Yasushi
Published: April 2003

Objective: To elucidate the effect of atrial natriuretic peptide (ANP) on cytokine-induced nitric oxide (NO) production, we examined whether ANP affects IL-1β-stimulated NO production and inducible NO synthase (iNOS) mRNA expression in cultured rat vascular smooth muscle cells (VSMC). Methods: VSMC were incubated with test agents for 24 h. The nitrite concentration of the culture medium, a stable-end product of NO, was measured by the column reduction method. NOS mRNA expression was analyzed by Northern blotting. The intracellular cAMP content was measured by enzyme immunoassay. cAMP-dependent kinase (PKA) activity was determined by a PKA assay system. Results: IL-1β stimulated nitrite production in VSMC. ANP (10 nM to 1 mM) enhanced the nitrite production and iNOS mRNA expression in the presence of IL-1β. Both 8-bromo-guanosine 3′,5′-cyclic monophosphate (8-br-cGMP) and dibutylyl adenosine 3′,5′-cyclic monophate enhanced IL-1β-induced nitrite production. The effects of these two nucleotide donors on the nitrite production were not additive, suggesting a common pathway. KT 5720, an inhibitor of PKA, abolished the enhancement of nitrite production by ANP and 8-br-cGMP, while KT 5823, an inhibitor of cGMP-dependent protein kinase, did not inhibit the enhancement. In the in vitro assay 8-br-cGMP increased PKA activity. Conclusions: ANP and cGMP enhanced IL-1β-induced NO production in VSMC. PKA rather than PKG may be involved in the enhancement.
Effects of Diadenosine Polyphosphates on Systemic and Regional Hemodynamics in Anesthetized Rats
Authors: Khattab Mahmoud , Hohage Helge , Hollah Peter , Rahn Karl-Heinz , Schlatter Eberhard
Published: April 2003

Diadenosine polyphoshates (Ap4A, Ap5A, Ap6A) induce vasodilatation or vasoconstriction in various isolated vessels and influence central and peripheral hemodynamics. The influence of diadenosine polyphoshates on hemodynamics was studied in anesthetized rats in vivo. Mean arterial blood pressure (MABP) and heart rate (HR) measured in the carotid artery decreased with Ap4A, Ap5A and Ap6A. Renal blood flow (RBF), femoral blood flow (FBF) and cardiac output (CO) were evaluated by an ultrasonic transit-time method. Renal superficial blood flow (RSBF) was measured by laser Doppler flowmetry. CO, RBF and RSBF were decreased initially by all three diadenosine polyphosphates. FBF was also slightly decreased. Total peripheral (TPR), renal (RVR) and femoral (FVR) vascular resistances were calculated. TPR was transiently increased by the dinucleotides following by a decrease. RVR and, to a lesser extent, FVR were also increased. These data show that diadenosine polyphosphates have effects on both the heart and the peripheral blood vessels. The effects on the heart and MABP were dominated by bradycardia and hypotension. In the kidney, diadenosine polyphosphates induced a predominant vascoconstriction. The effects on skeletal muscle blood flow were much smaller. Thus, the three diadenosine polyphosphates studied differ in the effects on heart and peripheral vessels.
Vasoactive Factors and Tubulointerstitial Injury
Authors: Wolf Gunter
Published: April 2003

Morphological changes of the tubulointerstitial architecture are a major determinant in the progression of chronic renal disease. The evolution of the tubulointerstitial lesion includes early tubular hypertrophy, recruitment of inflammatory cells into the tubulointerstitial space, and proliferation of interstitial fibroblasts resulting in the irreversible changes of tubular atrophy and tubulointerstitial fibrosis. Many of these diverse effects are mediated by autocrine or paracrine release of growth factors, cytokines, and chemokines. Proteinuria, reduction in functional renal mass per se, alterations in tubular fluid reabsorption, and well as hemodynamic changes in the injured kidney may all stimulate local release of such growth factors. A more recent conception is that vasoactive substances, traditionally viewed to be only involved in the regulation of vascular tone, could actually mediate many of these functions of the more 'classical’ growth factors and cytokines. In this regard, one of the most intensively studied vasoactive substances is angiotensin II which has been linked to the progression of renal disease by a host of mechanisms, including the induction of tubular hypertrophy and proliferation of interstitial fibroblasts. There is also increasing evidence that other vasoconstrictive factors such as endothelins and eicosanoids are involved in pathophysiological changes leading eventually to tubulointerstitial fibrosis. On the other hand, natriuretic peptides may exert antifibrogenic properties. Although interference with the renin angiotensin system is currently the only treatment being effective in attenuating the loss of function in patients with chronic renal insufficiency, it is likely that future studies will also investigate the role of other vasoactive substances in the progression of human chronic renal disease.
Does Leptin Play a Role in the Pathogenesis of Essential Hypertension?
Authors: Kokot Franciszek , Adamczak Marcin , Więcek Andrzej , Cieplok Joanna
Published: April 2003

Background: Leptin is produced and released by adipocytes in proportion to fat stores. Leptin as an anorectic hormone plays an important role in the regulation of food intake, energy expenditure, and insulin secretion. In contrast, neuropeptide Y, insulin, cortisol, and growth hormone are presumed to be appetite modulators. Leptin and neuropeptide Y are both involved in the activation of sympathetic tone. Increased body fat stores in obese patients are involved in the pathogenesis of some metabolic disorders (e.g., hyperinsulinaemia, glucose intolerance) and arterial hypertension. Methods and Results: Based on this pathophysiological background, we tried to assess the relationship between plasma leptin and blood pressure in 41 patients with essential hypertension (EHP; 20 females, 21 males, mean age 38.7±1.9 years, mean body mass index – BMI – 25.8±0.5 kg/m2) and in an appropriately sex– and BMI–matched control group of 27 normotensive healthy subjects (NHS; 11 females, 16 males, mean age 39.7±2.5 years, mean BMI 24.8±0.6 kg/m2). The plasma leptin concentration did not differ significantly between EHP and NHS (13.0±1.9 vs. 8.1±1.0 ng/ml, respectively). In both groups a significant positive correlation was found between BMI and plasma leptin concentration (p<0.0001). A significant positive correlation (p<0.02) was found between leptinaemia and mean (MAP), systolic and diastolic blood pressures, if data were analyzed for all examined subjects or separately only for women. Such a correlation could not be confirmed for male NHS and EHP subjects. The plasma neuropeptide Y concentration was higher in EHP than in NHS (77.1±23.0 vs. 63.6±9.8pg/ml, p = 0.05). In contrast to neuropeptide Y plasma insulin, cortisol, and growth hormone concentrations were similar in EHP and in NHS. Conclusion: Both EHP and NHS are characterized by a positive correlation between BMI and leptinaemia. Leptin may be indirectly involved in blood pressure regulation, especially in women of both NHS and EHP.
Susceptibility of Staphylococci Isolated from a Burns Unit to Mupirocin and Other Antimicrobial Agents
Authors: Udo E.E. , Mokadas E.M. , Jacob L.E. , Sanyal S.C. , Chugh T.D.
Published: April 2003

The activity of mupirocin (Bactroban) against coagulase-positive and coagulase-negative staphylococci isolated in a burns unit was tested to ascertain its effectiveness, and to detect any resistant isolates after continuous use of mupirocin for 2.5 years. A total of 395 staphylococci, consisting of 330 Staphylococcus aureus and 65 coagulase-negative staphylococci, were tested for resistance to mupirocin and other antimicrobial agents. The results showed that 94.5% of the isolates were fully susceptible to mupirocin (MIC ≤4 mg/l), and 5.3% expressed low-level resistance (MIC 8–128 mg/l). One Staphylococcus haemolyticus isolate expressed high-level resistance (MIC >1,024 mg/l). It transferred high-level mupirocin resistance to other staphylococci in conjugation experiments, which indicated a capacity to transmit mupirocin resistance between species. The results demonstrated that mupirocin was still highly effective against staphylococci in the burns unit. However, the demonstration that the resistant S. haemolyticus isolate could transfer high-level mupirocin resistance to other staphylococci was of concern. There is a compelling need to test staphylococci from clinical materials for mupirocin resistance. Early detection of resistance can prevent the establishment and spread of the mupirocin-resistant strains in the unit.
Erythema nodosum or Erythema induratum: An Important Distinction for Appropriate Treatment
Authors: Malaviya A.N. , Abdeend Suad , Qurtom M.A.F. , Al-Ghuriear S. , Kablawi H.I.
Published: April 2003

Objective and Importance: The objective of this case report is to draw the attention of the readers to a commonly seen disorder, namely panniculitis. Clinically, the condition resembles cellulitis, that often causes a diagnostic problem. The report hightlights the importance of accurate diagnosis of panniculitis and its subtypes for its proper management. Clinical Presentation: Two patients with clinically typical lesions of panniculitis on their lower extremities are described. The lesions in these 2 patients had marked clinical resemblance to cellulitis. However, with the help of biopsy and histopathological examination it was possible to accurately diagnose the distinct forms of panniculitis in these patients. It helped in the correct management of the patients with satisfactory outcome. Conclusion: It is concluded that in patients with lesions resembling cellulitis, especially on the shin, the possibility of panniculitis must be considered. The experience with these 2 patients highlights the need for accurate histological characterization as an essential step in the diagnosis and proper management of different forms of panniculitides.
Seroprevalence of Human T-Cell Leukemia/Lymphoma Virus Type I and Type II (HTLV-I/HTLV-II) Infection among Volunteer Blood Donors in Kuwait
Authors: Al-Mufti Siham , Voevodin Alexander , Ahmed Sabeeha , Al Hamdan Samia , Al-Basheer Abdul Azis
Published: April 2003

Objective: The human T-cell leukemia/lymphoma virus type I (HTLV-I) is an etiologic agent of adult T-cell leukemia/lymphoma and tropical spastic paraparesis. One of the major routes of transmission of the virus is through blood transfusion. The aim of this study was to determine the prevalence of HTLV-I infection in volunteer blood donors in Kuwait. Methods: A donation of 97,602 blood units in Kuwait from March 1995 to October 1997 was tested for antibodies against HTLV-I and related virus (HTLV-II). The testing was carried out in three steps: first screening by enzyme immunoassay (EIA) for anti-HTLV-I/II, second testing of initially positive samples by the EIA and final confirmation of true positives by Western blot. Results: Twenty-one HTLV-I-positive donors have been identified (7 Kuwaitis, 5 Indians, 4 Iranians, 2 Bedouins, 1 Omani, 1 Egyptian and 1 Filipino). None of the EIA-reactive samples was positive for HTLV-II by Western blot. The frequency of HTLV-I-positive blood donations was: 1:4,648 and the infection was significantly more prevalent among Indians and Iranians. Conclusion: The prevalence of HTLV-I infection in blood donors in Kuwait is one of the highest in the world and compulsory screening of blood for HTLV-I is fully justified.