Tokuhiro Ishihara

Regression of abdominal aortic aneurysm by inhibition of c-Jun N-terminal kinase.

Abdominal aortic aneurysm (AAA) is a common disease among elderly people that, when surgical treatment is inapplicable, results in progressive expansion and rupture of the aorta with high mortality. Although nonsurgical treatment for AAA is much awaited, few options are available because its molecular pathogenesis remains elusive. Here, we identify JNK as a proximal signaling molecule in the pathogenesis of AAA. Human AAA tissue showed a high level of phosphorylated JNK. We show that JNK programs a gene expression pattern in different cell types that cooperatively enhances the degradation of the extracellular matrix while suppressing biosynthetic enzymes of the extracellular matrix. Selective inhibition of JNK in vivo not only prevented the development of AAA but also caused regression of established AAA in two mouse models. Thus, JNK promotes abnormal extracellular matrix metabolism in the tissue of AAA and may represent a therapeutic target.

Reperfusion of Rat Heart After Brief Ischemia Induces Proteolysis of Calspectin (Nonerythroid Spectrin or Fodrin) by Calpain

Rat myocardium expresses the 240- and 235-kD polypeptides antigenically related to alpha- and beta-subunits of brain calspectin (nonerythroid spectrin or fodrin), respectively. In the subcellular fractions of the myocardium, alpha-calspectin was found in the 600g, 10,000g, and 100,000g pellets, whereas beta-calspectin was localized to the 10,000g pellet. On the basis of the Na+,K(+)-ATPase activity and the contents of a gap junction protein, the sarcolemma was distributed to the 10,000g and 100,000g pellets, and the intercalated disks were enriched in the 10,000g pellet. Both alpha- and beta-calspectin were proteolyzed by calpain in vitro. The two subunits were also proteolyzed in vivo, when the rat hearts underwent 10 to 60 minutes of global ischemia followed by 30 minutes of reperfusion. The reperfusion following the ischemia induced the proteolysis of alpha-calspectin in the 10,000g and 100,000g pellets, producing the 150-kD fragment. A synthetic calpain inhibitor, calpain inhibitor-1, suppressed the degradation of calspectin in vivo, which indicates that calpain is responsible for the reperfusion-induced proteolysis of calspectin. The inhibitor also improved myocardial stunning. Immunohistochemical study revealed that the proteolysis of alpha-calspectin occurs at the intercalated disks and the sarcolemma after postischemic reperfusion, in accord with the biochemical data. These results suggest that degradation of calspectin partly accounts for the contractile failure of the myocardium after postischemic reperfusion by disrupting the membrane skeleton and the intercalated disks.

Translocation of protein kinase C-α, δ and ϵ isoforms in ischemic rat heart

To explore the spatial and temporal localization of PKC isoforms during ischemia, we quantified PKC isoforms in the subcellular fractions in perfused rat heart by immunoblotting using specific antibodies against PKC isoforms. PKCs-alpha and epsilon translocated from the 100000 x g supernatant (S, cytosolic) fraction to the 1000 x g pellet (PI, nucleus-myofibril) and the 1000-100000 x g pellet (P2, membrane) fractions during 5-40 min of ischemia. PKC-delta redistributed from the P2 to the S fraction. A 50-kDa fragment of PKC-alpha appeared during ischemia possibly through calpain action. Immunohistochemical observations showed the different localizations of PKC-alpha, delta, and epsilon in the myocytes. The PKC assay displayed high basal levels of Ca(2+)-independent PKC, the activation of Ca(2+)-dependent PKC in the P1 and P2 fractions, and the activation of Ca(2+)-independent PKC in the P1 fraction after 20 min of ischemia. These observations show that ischemia induces different patterns of translocation of the three PKC isoforms, suggesting differences in their roles.

Ultrastructural evidence for intracellular formation of amyloid fibrils in macrophages

Early amyloid deposition in the spleen was studied by immunoelectron microscopy following the administration of rapid amyloid-inducing agents to mice. Two days after the injection of an amyloidenhancing factor and casein solution, a small amount of amyloid material was observed at the border of the white pulp and the marginal zone (perifollicular area) and also within the white pulp. At this stage, amyloid fibrils were seen mainly in an extracellular distribution along the cytoplasmic processes of reticular cells and also in the cytoplasmic invaginations of macrophages. By immunoelectron microscopy, gold particles labelled fibrillar structures in lysosome-derived organelles in some macrophages as well as dense bodies consisted of a homogeneous, granular matrix not having any recognizable fibrillar structures. Similar immunolabelled organelles were also observed in the amyloid resorption stage, although, at that stage, they commonly contained other phagocytized materials as well. From these findings, we suggest that at least some amyloid fibrils are polymerized in the cytoplasm of the macrophages by the proteolytic cleavage of previously pinocytized serum amyloid A protein (SAA).

Useful polyclonal antibodies against synthetic peptides corresponding to immunoglobulin light chain constant region for immunohistochemical detection of immunoglobulin light chain amyloidosis

For the immunohistochemical detection of immunoglobulin (Ig) light chain amyloidosis on formalin‐fixed, paraffin‐embedded tissue sections, we prepared polyclonal antibodies against synthetic peptides corresponding to positions 118–134 of Ig λ light chain and positions 116–133 of Ig κ light chain. Nineteen cases of systemic Ig λ light chain amyloidosis (Aλ amyloidosis), 10 cases of systemic Ig κ light chain amyloidosis (Aκ amyloidosis), one case of immunohistochemically unclassified systemic amyloidosis and five cases of localized Aλ amyloidosis were tested with these antibodies. Anti‐λ (118–134) antiserum and the affinity‐purified antibody both reacted with 18 of the 19 cases of systemic Aλ amyloidosis and all cases of localized Aλ amyloidosis, although the immunoexpression was somewhat variable in intensity in different areas within the same specimen in both systemic and localized amyloidosis. The signal intensities in plasma cells and serum reacted for anti‐λ (118–134) antiserum were weaker than signals obtained with commercially available anti‐Ig λ light chain antibodies. Anti‐κ (116–133) antiserum and the affinity‐purified antibody reacted with nine of the 10 cases of systemic Aκ amyloidosis. We conclude that these antibodies against synthetic peptides corresponding to the Ig light chain constant region are useful for the classification of amyloidosis on formalin‐fixed, paraffin‐embedded tissue sections.

Structure and expression of human mitochondrial adenylate kinase targeted to the mitochondrial matrix

The previously isolated cDNA encoding human adenylate kinase (AK) isozyme 3 was recently renamed AK4. Consequently, human AK3 cDNA remains to be identified and we have little information about the functional relationship between human AK3 and AK4. In pursuit of the physiological roles of both the AK3 and AK4 proteins, we first isolated an authentic human AK3 cDNA and compared their expression. Nucleotide sequencing revealed that the cDNA encoded a 227-amino-acid protein, with a deduced molecular mass of 25.6 kDa, that shares greater homology with the AK3 cDNAs isolated from bovine and rat than that from human. We named the isolated cDNA AK3. Northern-blot analysis revealed that AK3 mRNA was present in all tissues examined, and was highly expressed in heart, skeletal muscle and liver, moderately expressed in pancreas and kidney, and weakly expressed in placenta, brain and lung. On the other hand, we found that human AK4 mRNA was highly expressed in kidney, moderately expressed in heart and liver and weakly expressed in brain. Western-blot analysis demonstrated expression profiles of AK3 and AK4 that were similar to their mRNA expression patterns in each tissue. Over expression of AK3, but not AK4, in both Escherichia coli CV2, a temperature-sensitive AK mutant, and a human embryonic kidney-derived cell line, HEK-293, not only produced significant GTP:AMP phosphotransferase (AK3) activity, but also complemented the CV2 cells at 42 degrees C. Subcellular and submitochondrial fractionation analysis demonstrated that both AK3 and AK4 are localized in the mitochondrial matrix.

Postoperative Outcome of 37 Patients With Lobar Intracerebral Hemorrhage Related to Cerebral Amyloid Angiopathy

BACKGROUND AND PURPOSE Several recent studies have suggested that neurosurgical procedures are not contraindicated in patients with cerebral amyloid angiopathy (CAA). The purpose of this study was to elucidate the clinical factors influencing the outcome of patients with CAA-related intracerebral hemorrhage (ICH) treated surgically. METHODS A total of 50 neurosurgical procedures (42 intracerebral hematoma evacuations, 4 ventriculoperitoneal shunts, 3 ventricular drainages, and 1 brain biopsy) were performed in 37 patients with CAA-related ICH. To ascertain the clinical factors that may influence their postoperative outcome, their clinical data (demographics, medical history, recurrent lobar hemorrhage, radiographic characteristics, multiple lobar hemorrhage, surgical details, and postoperative hemorrhage) were examined retrospectively and subjected to multivariate analysis. RESULTS Twenty patients (54%) had a good outcome, and only 4 (11%) died. Parietal hematomas, advanced age (>/=75 years), and intraventricular hemorrhages had significant adverse influence on the postoperative outcome. Clinically significant postoperative hemorrhage requiring evacuation occurred after 2 (5%) of 42 intracerebral hematoma evacuations. Postoperative hemorrhage did not have significant adverse influence on the outcome. CONCLUSIONS Neurosurgery can be performed relatively safely in patients with CAA-related ICH, and their postoperative outcome is better than that reported previously. Surgical treatment should be considered for such patients aged <75 years without a parietal hematoma and intraventricular hemorrhage.

Immunohistochemical classification of 140 autopsy cases with systemic amyloidosis

One hundred and forty autopsy cases of systemic amyloid‐osis were examined using the potassium permanganate method for distinction of amyloid A protein from other amyloid proteins and an immunohistochemical technique. Of those cases, amyloid proteins were identified in 121 cases. There were 68 cases of amyloid A‐related (AA) amyloidosis and these were the most common type among the cases (56.2%). There were 39 cases of immunoglobulin light chain‐related (AL) amyloidosis (32.2%), six cases of β2‐microglobulin‐related (Aβ2M) amyloidosis (5%), and five cases of transthyretin‐related (ATTR) amyloidosis (4.1%). Minute areas of amyloid deposits in four cases with AA were resistant to potassium permanganate pretreatment. In Aβ2M amyloidosis amyloid deposits were either resistant or sensitive to potassium permanganate pretreatment, from case to case. The coexistence of two different amyloid proteins was seen in three cases: one case had ATTR and Ax types, and two cases had Aβ2M and AA types. Some discrepancies were seen between the immunohistochemical typing and clinical classification of amyloidosis referred to in the Annual of the Pathological Autopsy Cases in Japan, for example, one case of AA type in myeloma‐associated amyloidosis and one case of AL type in secondary amyloidosis. From the present results, the importance of the immunohistochemical method in classifying amyloidosis is stressed.

Incidence and distribution of isolated atrial amyloid: Histologic and immunohistochemical studies of 100 aging hearts

The incidence and anatomic distribution of isolated atrial amyloid (IAA) in 100 aging hearts were studied histologically and immunohistochemically using antibodies against α‐human‐atrial natriuretic peptide (α‐ANP), human transthyre‐tin (TTR) and human amyloid P component (AP). Ninety‐one of 100 hearts (91%) had amyloid deposits in the atria. Amyloid deposits in all 91 hearts reacted with α‐ANP and AP antisera, and in four hearts other amyloid deposits that reacted with lTR antiserum were coincidentally seen in the atria. The prevalence of IAA deposition, using a semiquantitative evaluation, was significantly higher in the hearts from patients over 80 years of age, from women, those weighing over 450g, with a thickened left ventricular wall (>1.4 cm) and with multiple myocardial scars. IAA deposition showed a significant distribution in the auricle and left atrium; it was located mostly in the interstitium of the subendocardial layer and the subendorcardial myocardium. These results indicate that IAA occurs more frequently than previously appreciated in the elderly and in patients with certain cardiac disorders.

Prolyl 4-hydroxylase inhibitor (HOE 077) inhibits pig serum-induced rat liver fibrosis by preventing stellate cell activation

BACKGROUND/AIMS The aim of this study was to investigate the effect and mechanism of fibrosuppression by a newly synthesized prolyl 4-hydroxylase inhibitor [HOE 077, 2, 4-pyridine dicarboxylic acid bis [(2-methoxyethyl) amide]] on pig serum-induced liver fibrosis in the rat. METHODS Male Wistar rats received 0.5 ml of pig serum twice a week for 10 weeks with 0, 100 or 200 ppm of HOE 077. At the end of the experiment, the hydroxyproline content of the liver, and alanine aminotransferase were measured. Histological stains used were HE, azan and a stain for alpha-smooth muscle actin (alpha-SMA). Electron microscopy was also performed. Messenger RNA expressions of type I and III procollagen were examined by Northern blot analysis. alpha-SMA positive cells and fibers with azan staining were assessed as percent area of the tissue specimen, using an image analysis system. RESULTS Rats that received pig serum for 10 weeks showed an increased liver hydroxyproline content of 318+/-39 microg/g wet weight (n=15). HOE 077 at doses up to 200 ppm significantly (p<0.01) reduced this increase of liver hydroxyproline content (181+/-39 microg/g wet weight, n=15) in accordance with improved histological findings. 200 ppm of HOE 077 significantly reduced mRNA expressions of alpha2(I) (486+/-102 vs 151+/-36, p<0.01) and alpha1(III) (276+/-127 vs 160+/-67, p<0.05) procollagen and percent area of alpha-SMA positive cells (2.94+/-2.14 vs 1.17+/-0.88%). Electron microscopy revealed that 200 ppm of HOE 077 prevented the loss of fat droplets. CONCLUSIONS A prolyl 4-hydroxylase inhibitor (HOE 077) prevented pig serum-induced rat liver fibrosis by inhibiting stellate cell activation.