Population panmixia and demographic expansion of a highly piscivorous marine fish Scomberomorus niphonius.

Population structure and demographic history of the Japanese Spanish mackerel Scomberomorus niphonius a highly piscivorous and migratory marine fish, were assessed using mitochondrial DNA control region sequences (n = 720) and microsatellite genotypes at five loci (n = 1331) for samples collected on Japanese coasts from 2001 to 2010. The population structure was panmictic and the haplotype and allele frequencies were temporally stable even during the recent recovery process. Demographic expansion was strongly supported throughout the Pleistocene, suggesting that the oscillating glacial and interglacial climate conditions in the Pleistocene had no substantial impact on the demographic history of S. niphonius.

Validation of a commercial serodiagnostic kit for diagnosing pulmonary Mycobacterium avium complex disease.

SETTING: A commercial serodiagnostic kit for diagnosing pulmonary disease due to Mycobacterium avium complex (MAC-PD) was developed and launched in Japan in 2011. OBJECTIVE: To evaluate the performance of this kit in routine clinical settings. METHODS: In this retrospective single-centre study, data on serum levels of anti-glycopeptidolipid (GPL) core IgA antibody (U/ml) measured using the kit were analysed in patients diagnosed with MAC-PD according to American Thoracic Society criteria, in those with pulmonary tuberculosis (PTB) or pulmonary M. kansasii disease and in healthy volunteers. RESULTS: The anti-GPL-core IgA antibody levels of serum were significantly higher (P < 0.0001) in patients with MAC-PD (n = 485) than in those with PTB (n = 133) or pulmonary M. kansasii disease (n = 23) or in healthy subjects (n = 265). When the cut-off level was set at 0.7 U/ml, the sensitivity and specificity were respectively 78.6% and 96.9%. Higher antibody levels were observed in patients with greater extent of disease on chest computed tomography (P < 0.0001). CONCLUSIONS: The serodiagnostic kit revealed good sensitivity and specificity. The antibody levels may reflect disease activity. Additional work is needed to determine whether the diagnostic assay could be used in conjunction with current diagnostic criteria to improve the diagnosis of MAC-PD.

The combination of strong expression of ZNF143 and high MIB-1 labelling index independently predicts shorter disease-specific survival in lung adenocarcinoma.

BACKGROUND: The transcription factor, zinc finger protein 143 (ZNF143), positively regulates many cell-cycle-related genes. The ZNF143 would show high expression of multiple solid tumours related closely to cancer cell growth, similar to the widely accepted Ki67 (MIB-1) protein, but the underlying mechanisms for ZNF143 remain unclear. We investigated the association of ZNF143 expression with clinicopathological features and prognoses of patients with lung adenocarcinoma. METHODS: Expressions of ZNF143 and MIB-1 were immunohistochemically analysed in 183 paraffin-embedded tumour samples of patients with lung adenocarcinoma. The ZNF143 expression was considered to be strong when >30% of the cancer cells demonstrated positive staining. RESULTS: Strong ZNF143+ expression showed a significantly close relationship to pathologically moderate to poor differentiation and highly invasive characteristics. The ZNF143 positivity potentially induced cell growth of lung adenocarcinoma, correlated significantly with high MIB-1 labelling index (⩾10%). Univariate and multivariate analyses demonstrated that both strong ZNF143+ and the high MIB-1 index group have only and significantly worse survival rates. CONCLUSIONS: The combination of strong ZNF143 expression and high MIB-1 index potentially predicts high proliferating activity and poor prognosis in patients with lung adenocarcinoma, and may offer a therapeutic target against ZNF143.

Polypeptide N-acetylgalactosaminyl transferase 3 independently predicts high-grade tumours and poor prognosis in patients with renal cell carcinomas.

BACKGROUND: The polypeptide N-acetylgalactosaminyltransferases (GalNAc-Ts) family of enzymes regulates the initial steps of mucin-type O-glycosylation. N-acetylgalactosaminyltransferases might show novel patterns of GalNAc-T glycosylation on tumour-derived proteins, which could influence cancer biology, but its mechanisms are unclear. We investigated the association of GalNAc-T3 and -T6 expressions with clinicopathological features and prognoses of patients with renal cell carcinomas (RCCs). METHODS: Expressions of GalNAc-T3/6 and cell-adhesion molecules were analysed immunohistochemically in 254 paraffin-embedded tumour samples of patients with RCC. RESULTS: Of 138 GalNAc-T3+ cases, 46 revealed significant co-expression with GalNAc-T6. N-acetylgalactosaminyltransferases-3+ expression showed a close relationship to poor clinical performance and large tumour size, or pathologically high Fuhrman's grading, and presence of vascular invasion and necrosis. The GalNAc-T3-positivity potentially suppressed adhesive effects with a significantly low ß-catenin expression. Univariate and multivariate analyses showed the GalNAc-T3+ group, but not the GalNAc-T6+ group, to have significantly worse survival rates. CONCLUSION: N-acetylgalactosaminyltransferases-3 expression independently predicts high-grade tumour and poor prognosis in patients with RCC, and may offer a therapeutic target against RCC.

Long-term radiographic outcome of nodular bronchiectatic Mycobacterium avium complex pulmonary disease.

BACKGROUND: Although Mycobacterium avium complex pulmonary disease (MAC-PD) is a growing health problem, little is known about long-term radiographic outcome and factors for deterioration in patients with MAC-PD. METHODS: Data on patients with nodular bronchiectatic (NBE) MAC-PD who underwent regular follow-up for >5 years were retrospectively reviewed. Changes in plain chest radiograph (CXR) and baseline characteristics were compared between the stable and deteriorated groups. RESULTS: Seventy-two patients were investigated, including 30 patients who were examined 10 years after the initial visit. One patient (1.4%) showed progressive or remarkably progressive disease on CXR at 1 year; this rate increased to 22.2% at 5 years and to 53.3% at 10 years. Body mass index (BMI) at the initial visit was lower in the deteriorated group than in the stable group. Cavitary disease and resistance to a macrolide were seen more frequently at the initial visit in the deteriorated group than in the stable group. CONCLUSIONS: NBE MAC-PD is a slowly but substantially progressive long-term infection (5-10 years). Our data suggest that patients with lower BMI, cavitary disease and resistance to a macrolide at initial visit are more likely to progress to deteriorating disease.

Genetic effects of hatchery fish on wild populations in red sea bream Pagrus major (Perciformes, Sparidae) inferred from a partial sequence of mitochondrial DNA.

Variation in the mitochondrial DNA transcriptional control region sequence was investigated in wild and hatchery-released red sea bream Pagrus major from Kagoshima Bay, where an extensive hatchery-release programme has been conducted for >30 years. The programme has successfully augmented commercial catches in the bay (released juveniles have been produced from the captive broodstock, repeatedly used over multiple generations). Samples were also obtained from outside the bay, where limited stocking has occurred. Genetic diversity indices measured as number of haplotypes, haplotype richness, haplotype diversity and nucleotide diversity were lower in hatchery-released fish than in wild fish. Genetic differences in wild fish from the bay, especially in the inner bay, compared with fish from outside the bay were detected in terms of decreased genetic diversity indices and changed haplotype frequencies. Unbiased population pair-wise F(ST) estimates based on an empirical Bayesian method, however, revealed low genetic differentiation between samples from the bay and its vicinity. Mixed stock identification analyses estimated the proportion of hatchery-released fish in wild populations in the inner and central bays at 39·0 and 8·7%, respectively, although the precision of the estimates was very low because of the small genetic differentiation between populations and relatively small sample sizes. Hence, the long-term extensive hatchery release programme has affected the genetic diversity of wild populations in the bay; however, the genetic effects were low and appeared to remain within the bay.

A survey of the anti-apoptotic Bcl-2 subfamily expression in cancer types provides a platform to predict the efficacy of Bcl-2 antagonists in cancer therapy.

We investigated the mRNA expression levels of all six antiapoptotic Bcl-2 subfamily members in 68 human cancer cell lines using qPCR techniques and measured the ability of known Bcl-2 inhibitors to induce cell death in 36 of the studied tumor cell lines. Our study reveals that Mcl-1 represents the anti-apoptotic Bcl-2 subfamily member with the highest mRNA levels in the lung, prostate, breast, ovarian, renal, and glioma cancer cell lines. In leukemia/lymphoma and melanoma cancer cell lines, Bcl-2 and Bfl-1 had the highest levels of mRNA, respectively. The observed correlation between the cell killing properties of known Bcl-2 inhibitors and the relative mRNA expression levels of anti-apoptotic Bcl-2 proteins provide critical insights into apoptosis-based anticancer strategies that target Bcl-2 proteins. Our data may explain current challenges of selective Bcl-2 inhibitors in the clinic, given that severe expression of Bcl-2 seems to be limited to leukemia cell lines. Furthermore, our data suggest that in most cancer types a strategy targeted to Mcl-1 inhibition, or combination of Bfl-1 and Mcl-1 inhibition for melanoma, may prove to be more successful than therapies targeting only Bcl-2.

Serological test and chest computed tomography findings in patients with Mycobacterium avium complex lung disease.

The present authors have previously reported the usefulness of a serodiagnostic test to detect serum glycopeptidolipid (GPL) core antibody in diagnosing Mycobacterium avium complex (MAC) lung disease in immunocompetent patients. The aim of the present study was to investigate correlations between the levels of antibody against GPL core and chest computed tomography (CCT) findings in patients with MAC lung disease. A total of 47 patients with MAC-positive culture from their sputum and who had radiographic abnormalities were investigated. Thirty-three patients met the American Thoracic Society criteria for MAC disease; 14 did not. All patients underwent both CCT examination and the serodiagnostic test for MAC at the same time. Small nodular shadows were seen on CCT in all 47 patients and bronchiectasis shadows were seen in 39 (83%) of them. There was a significant positive correlation between the extent of the disease and the level of GPL core immunoglobulin (Ig)A antibody. The levels of GPL core IgA antibody were significantly elevated in patients who had nodular shadows (10-30 mm) compared with patients who had small nodular shadows (<10 mm). The present results document that the levels of immunoglobulin A antibody against glycopeptidolipid core correlate with the chest computed tomography findings of Mycobacterium avium complex lung disease.

Targeting inhibition of K-ras enhances Ad.mda-7-induced growth suppression and apoptosis in mutant K-ras colorectal cancer cells.

Melanoma differentiation-associated gene-7/interleukin-24 (mda-7/IL-24) is a cancer-specific, growth-suppressing and apoptosis-inducing gene with broad-spectrum antitumor activity. However, when administered by means of a replication-incompetent adenovirus, Ad.mda-7, several colorectal carcinoma cell lines are resistant to its antiproliferative and antisurvival effects. We have presently endeavored to determine if K-ras mutations, present in approximately 40-50% of colorectal cancers and which may mediate resistance to chemotherapy and radiotherapy, represent a predisposing genetic factor mitigating reduced sensitivity to Ad.mda-7. To suppress ras expression, three structurally different replication-incompetent adenoviral vectors were engineered that express (1) an intracellular, neutralizing single-chain antibody (scAb) to p21 ras (Ad.K-ras scAb), (2) an antisense (AS) K-ras gene (Ad.K-ras AS) or (3) both mda-7/IL-24 and a K-ras AS gene in a single bipartite virus (Ad.m7.KAS). Simultaneous inhibition of K-ras and expression of mda-7/IL-24 enhanced killing of colorectal carcinoma cells with mutated K-ras, but not with wild-type K-ras. The extent of killing depended on the degree of K-ras downregulation, with Ad.K-ras AS being generally more efficient than Ad.K-ras scAb in combination with Ad.mda-7. These findings support an effective dual-combinatorial approach for the therapy of colorectal cancers that employs a unique cancer-specific suppressor gene (mda-7/IL-24) with targeted inhibition of oncogene (ras) expression.

Clinical impact of interstitial pneumonia following surgery for lung cancer.

BACKGROUND: Operative morbidity in patients with lung cancer associated with perioperative interstitial pneumonia (IP) has emerged as a serious problem. PATIENTS AND METHODS: We studied the clinical impact of perioperative related IP in 11 patients (IP group: 7 preoperative known, 4 acute onset) of 473 lung cancer patients who received a pulmonary resection. The IP group was compared to the remaining 462 patients (non-IP group). Demographic data, clinical presentation, and serum KL-6 levels were compared. RESULTS: There were no differences in age, gender, type of surgery, and pulmonary function except for % DLco between the non-IP and IP groups. The IP group showed a higher in-hospital mortality (n=2: 18.3%) than that of the non-IP group (n=3: 0.6%) (P<0.005). Seven patients with underlying IP with high KL-6 levels showed an uneventful recovery. Two patients with postoperative onset of acute IP had a fatal course associated with elevation of serum KL-6 levels. CONCLUSIONS: Postoperative development IP is a serious complication with high mortality, and serial measurement of KL-6 levels is useful to assess the activity of IP.

Thymidine-phosphorothioate oligonucleotides induce activation and apoptosis of CLL cells independently of CpG motifs or BCL-2 gene interference.

We compared antisense phosphorothioate oligonucleotides (PS-ODN) that target BCL-2 such as Genasense (G3139-PS), with other PS-ODN or phosphodiester-ODN (PO-ODN) in their relative capacity to induce apoptosis of chronic lymphocytic leukemia (CLL) B cells in vitro. Surprisingly, we found that thymidine-containing PS-ODN, but not PO-ODN, induced activation and apoptosis of CLL cells independent of BCL-2 antisense sequence or CpG motifs. All tested thimidine-containing PS-ODN, irrespective of their primary sequences, reduced the expression of Bcl-2 protein and increased the levels of the proapoptotic molecules p53, Bid, Bax in CLL cells. Apoptosis induced by thymidine-containing PS-ODN was preceded by cellular activation, could be blocked by the tyrosine-kinase inhibitor imatinib mesylate (Gleevec), and was dependent on ABL kinase. We conclude that thymidine-containing PS-ODN can activate CLL cells and induce apoptosis via a mechanism that is independent of BCL-2 gene interference or CpG motifs.

Ionizing radiation enhances therapeutic activity of mda-7/IL-24: overcoming radiation- and mda-7/IL-24-resistance in prostate cancer cells overexpressing the antiapoptotic proteins bcl-xL or bcl-2.

Subtraction hybridization applied to terminally differentiating human melanoma cells identified mda-7/IL-24, a cytokine belonging to the IL-10 gene superfamily. Adenoviral-mediated delivery of mda-7/IL-24 (Ad.mda-7) provokes apoptosis selectively in a wide spectrum of cancers in vitro in cell culture, in vivo in human tumor xenograft animal models and in patients with advanced carcinomas and melanomas. In human prostate cancer cells, a role for mitochondrial dysfunction and induction of reactive oxygen species in the apoptotic process has been established. Ectopic overexpression of bcl-xL and bcl-2 prevents these changes including apoptosis induction in prostate tumor cells by Ad.mda-7. We now document that this resistance to apoptosis can be reversed by treating bcl-2 family overexpressing prostate tumor cells with ionizing radiation in combination with Ad.mda-7 or purified GST-MDA-7 protein. Additionally, radiation augments apoptosis induction by mda-7/IL-24 in parental and neomycin-resistant prostate tumor cells. Radiosensitization to mda-7/IL-24 is dependent on JNK signaling, as treatment with the JNK 1/2/3 inhibitor SP600125 abolishes this effect. Considering that elevated expression of bcl-xL and bcl-2 are frequent events in prostate cancer development and progression, the present studies support the use of ionizing radiation in combination with mda-7/IL-24 as a means of augmenting the therapeutic benefit of this gene in prostate cancer, particularly in the context of tumors displaying resistance to radiation therapy owing to bcl-2 family member overexpression.

Liquid chromatography/mass spectrometry analysis of small-scale glycopeptidolipid preparations to identify serovars of Mycobacterium avium-intracellulare complex.

AIMS: The antigenic glycopeptidolipids (GPLs) from Mycobacterium avium-intracellulare complex (MAC) are grouped into 28 serovars on the basis of the variable oligosaccharide sequences and the core structures. To facilitate the identification of MAC serovars by employing liquid chromatography/mass spectrometry (LC/MS), the diversity in fatty acyl moieties and the number of acetyl groups of GPLs should be characterized. METHODS AND RESULTS: Employing a small-scale preparation method, sufficient quantities of intact GPLs could be obtained from several colonies of MAC within 4 h. Tandem mass spectrometry of GPLs showed the presence of common fragment ion at m/z 1048 in the main molecular species of all reference strains. It revealed that the acyl moieties had similar diversity among all serovars. Furthermore, intact GPLs had mainly one or two acetyl groups. This allowed us to determine the masses of each serovar based on intact GPLs and to classify 16 isolates from patients by LC/MS. CONCLUSIONS: The present serotyping method using LC/MS analysis improved the precision of measurements and shortened the procedure time compared with conventional thin-layer chromatography or the seroagglutination test method. SIGNIFICANCE AND IMPACT OF THE STUDY: This proposed method proves useful for identifying serovars of MAC for epidemiological and pathogenic research purposes.

The histone deacetylase inhibitor MS-275 induces caspase-dependent apoptosis in B-cell chronic lymphocytic leukemia cells.

MS-275 is a histone deacetylase (HDAC) inhibitor that has been reported to mediate its cytotoxic effect through generation of reactive oxygen species (ROS) in proliferating hematopoietic cell lines. We examined efficacy of MS-275 in nonproliferating chronic lymphocytic leukemia (CLL) cells from patients. In these cells, MS-275 demonstrated an in vitro LC(50) that was one log lower than for normal mononuclear cells. Following MS-275 treatment, histones H3 and H4 showed increased acetylation and HDAC enzymatic activity was reduced. Caspase-8, -9, and -3 were activated, and caspase substrates PARP and BID were cleaved. Additionally, FLICE-inhibitory protein (FLIP) was downmodulated following MS-275 incubation. MS-275 treatment caused detectable ROS generation after 15 h of incubation, which was blocked by the caspase inhibitor Z-VAD-fmk. Overexpression of Bcl-2 protein protected against MS-275-induced apoptosis. These data demonstrate that MS-275 is a promising therapy for the treatment of CLL, but that in contrast to previous reports, ROS generation does not precede commitment to apoptosis. Similar to many other therapeutic targets, MS-275-mediated apoptosis is reduced by overexpression of Bcl-2, justifying strategies to combine HDAC inhibitors with Bcl-2 antagonists.

Febrile ulceronecrotic Mucha-Habermann disease: a case report and a review of the literature.

This report describes the case of a 76 year old man who suffered from febrile ulceronecrotic Mucha-Habermann disease (FUMHD). Despite this patient's typical clinical and histological findings, the fulminating course led to death. Polymerase chain reaction (PCR) analysis of the skin lesions showed that the infiltrating cells were monoclonal in origin and were from an aberrant clone. FUMHD is a very rare, febrile variant type of pityriasis lichenoides et varioliformis acuta, and is characterised by necrotic cutaneous ulcerations associated with high fever and systemic manifestations. Including this present case, only 18 cases of FUMHD have been reported. FUMHD can occur in both adults and children, although there are several differences between the manifestations of the disease in the two groups. One major difference is prognosis: all cases resulting in fatality are of the adult type, whereas no fatal cases have been reported among children. The aberrant clone detected by PCR may be responsible for host responses, resulting in the severe symptoms observed in this disorder.

Synthetic triterpenoids activate a pathway for apoptosis in AML cells involving downregulation of FLIP and sensitization to TRAIL.

Acute myelogenous leukemia (AML) remains a deadly disease for most adult patients, due primarily to the emergence of chemoresistant cells. Defects in apoptosis pathways make important contributions to chemoresistance, suggesting a need to restore apoptosis sensitivity or to identify alternative pathways for apoptosis induction. Triterpenoids represent a class of naturally occurring and synthetic compounds with demonstrated antitumor activity, including 2-cyano-3,12-dioxoolean-1,9-dien-28-oic acid (CDDO) and its methyl ester (CDDO-m). We explored the effects of CDDO and CDDO-m in vitro on established AML cell lines (HL-60, U937, AML-2) and on freshly isolated AML blasts. CDDO and CDDO-m reduced the viability of all AML cell lines tested in a dose-dependent manner, with effective doses for killing 50% of cells (ED(50)) within 48 h of approximately 1 and 0.5 muM, respectively. CDDO or CDDO-m also induced substantial increases in cell death in five out of 10 samples of primary AML blasts. Cell death induced by CDDO and CDDO-m was attributed to apoptosis, based on characteristic cell morphology and evidence of caspase activation. Immunoblot analysis demonstrated proteolytic processing of caspase-3, -7, and -8, but not caspase-9, suggesting the involvement of the 'extrinsic' pathway, linked to apoptosis induction by TNF-family death receptors. Accordingly, CDDO and CDDO-m induced concentration-dependent reductions in the levels of FLIP protein, an endogenous antagonist of caspase-8, without altering the levels of several other apoptosis-relevant proteins. Reductions in FLIP were rapid, detectable within 3 h after exposure of AML cell lines to CDDO or CDDO-m. CDDO and CDDO-m also sensitized two of four leukemia lines to TRAIL, a TNF-family death ligand. The findings suggest that synthetic triterpenoids warrant further investigation in the treatment of AML, alone or in combination with TRAIL or other immune-based therapies.

Cutaneous eruptions in coma patients with nontraumatic rhabdomyolysis.

BACKGROUND: Rhabdomyolysis has been described most commonly after muscle injury but may also result from coma due to alcohol intake or drug abuse. Its clinical findings usually occur as muscular pain and swelling, but these symptoms are also seen in as many as 60% of patients with nontraumatic rhabdomyolysis. The diagnosis of slight nontraumatic rhabdomyolysis is often difficult to establish clinically. Few previous studies have reported cutaneous symptoms in nontraumatic rhabdomyolysis. OBJECTIVE: We attempted to elucidate a relationship between nontraumatic rhabdomyolysis and cutaneous eruption. METHODS: We studied 7 patients who were diagnosed as having massive to slight nontraumatic rhabdomyolysis with a cutaneous eruption in pressure areas at the first visit to our hospital between March 28, 1988, and June 27, 1998. RESULTS: They revealed wine-red-colored urine and elevated serum myogenic enzyme. Two patients complained of muscle pain. In all patients, cutaneous eruptions including well-demarcated erythema, bullae and deep ulcers were observed in areas of pressure. The pathological findings of 5 cutaneous eruptions revealed necrosis of sweat ducts and glands in the dermis. CONCLUSIONS: The pathogenesis of nontraumatic rhabdomyolysis and the cutaneous eruptions in coma patients has not been elucidated, but these conditions are due to similar factors; pressure and hypoxia are considered to be important causative factors for both. Cutaneous eruptions in the coma patient may be an important clinical symptom of nontraumatic rhabdomyolysis.

Recognition of mitochondrial protein precursor lacking arginine at position -2 by mitochondrial processing peptidase: processing of bovine cytochrome P450(SCC) precursor.

Mitochondrial processing peptidase (MPP) specifically cleaves off the N-terminal presequence of the mitochondrial protein precursor. Previous studies demonstrated that Arg at position -2 from the cleavage site, which is found among many precursors, plays a critical role in recognition by MPP. We analyzed the structural elements of bovine cytochrome P450 side-chain cleavage enzyme precursor [pre-P450(SCC)], which has Ala at position -2, for recognition by MPP. Replacement of Ala position -2 of pre-P450(SCC) with Arg resulted in an increase in the cleavage rate. Replacement with Gly caused a reduction in the cleavage rate and the appearance of an additional cleavage site downstream of the authentic site. A pre-P450(SCC) mutant with Met at position -2 retained cleavage efficiency equal to that of the wild type. These results indicate that -2 Ala of pre-P450(SCC) is recognized by MPP as a determinant for precise cleavage, and that the amino acid at -2 is required to have a straight methylene chain for interaction with the S(2) site. The preference for distal basic residues, a hydrophobic residue at +1, and hydroxyl residues at +2 and +3, was almost the same as those of the precursors with Arg at -2, indicating that the recognition mechanism of pre-P450(SCC) by MPP is essentially the same as that of the precursors with Arg at position -2.

Glu(191) and Asp(195) in rat mitochondrial processing peptidase beta subunit are involved in effective cleavage of precursor protein through interaction with the proximal arginine.

Mitochondrial processing peptidase (MPP), consisting of alpha and beta subunits, recognizes a large variety of N-terminal extension peptides of mitochondrial precursor proteins, and generally cleaves a single site of the peptide including arginine at the -2 position (P(2)). We obtained evidence that Glu(191) and Asp(195) of rat beta subunit interact with P(2) arginine of precursor protein through ionic and hydrogen bonds, respectively, using recombinant MPP. Mutation to alanines at Glu(191) and Asp(195) reduced processing activity toward precursors with P(2) arginine, but resulted in no loss of activity toward P(2) alanine precursors. Charge-complementary mutation demonstrated that MPP variants with beta Arg(191) exhibited compensatory processing activity for the precursor with acidic residue at the P(2) position. Thus, Glu(191) and Asp(195) are substrate-binding sites required for cleavage of extension peptides through interaction with P(2) arginine.

Interaction between sarcomere and mitochondrial length in normoxic and hypoxic rat ventricular papillary muscles.

We hypothesized that the mitochondrial length may be altered according to changes in the sarcomere length, and that this relationship may be affected by exposure to hypoxia. Rat ventricular papillary muscles were isolated and immersed in normoxic or hypoxic solutions for 10 min. Sarcomeres of various lengths were obtained by fixing the papillary muscles in a slack or stretched state, or after exposure to a contracture solution containing saponin and CaCl(2). The mitochondrial length measured using electron microscopy significantly correlated to the length of the adjacent sarcomere in both the normoxic (n=767) and hypoxic (n=1145) groups (P<.0001). The slope of the regression line, however, was significantly less steep, and its intercept was significantly larger in the hypoxic group than in the normoxic group (analysis of covariance). When we analyzed the mitochondrial lengths among the three sarcomere-length subgroups (<1.5, 1.5-2.0, and >2.0 microm), the mitochondrial length was significantly shorter in the hypoxic condition than in the normoxic condition at sarcomere lengths greater than 2.0 microm. Staining for desmin, the major muscle-type intermediate filament, the longitudinal system of which connects the mitochondria with the Z bands of sarcomeres, showed a clear cross-striation pattern in both papillary muscles with and without the exposure to hypoxia, suggesting that desmin was preserved after the exposure to hypoxia. These data indicate that the mitochondrial length changes according to changes in the sarcomere length, suggesting the possible role of mitochondria as an internal load against myocyte contraction. It is also suggested that mitochondria exposed to hypoxia may be more resistive to both compression and stretch in a longitudinal direction than those in the normoxic condition.