ASK1 associates with troponin T and induces troponin T phosphorylation and contractile dysfunction in cardiomyocytes

There is increasing support for the idea that excessive production of proinflammatory mediators such as tumor necrosis factor (TNF) and reactive oxygen species (ROS) contribute to the pathogenesis of cardiac dysfunction. However, the mechanisms by which cytokine/ROS production mediates cardiac dysfunction have not been established. Given that apoptosis signal-regulating kinase 1 (ASK1) is highly expressed in cardiac muscle and that ASK1 is an important mediator in the signaling pathways induced by tumor necrosis factor, interleukin-1, and ROS, we used the yeast two-hybrid system with ASK1 as bait to identify ASK1 substrates from a human heart cDNA library. The cDNA encoding the cardiac troponin T (cTnT) was isolated. ASK1 specifically interacted with cTnT, but not cTnI, in vitro and in vivo via the C-terminal ASK1 domain. ASK1 specifically phosphorylated cTnT in vitro and in vivo. Mutations in cTnT (T194/S198) at an ASK1-phosphorylation consensus sequence significantly reduced phosphorylation by ASK1. ROS-induced ASK1 activation, cTnT phosphorylation, and contractile dysfunction in cardiomyocytes showed similar kinetics. Moreover, overexpression of constitutively active ASK1 induces cTnT phosphorylation and inhibits shortening and calcium transient in adult cardiomyocytes. We conclude that ASK1 plays an important role in regulation of cardiac contractile function by phosphorylating cTnT and may participate in cytokine/ROS-induced pathogenesis of cardiomyopathy and heart failure.     

Preparation and characterization of Pertussis toxin subunits

Pertussis toxin (PT), a typical A-B oligomer exotoxin of Bordetella pertussis, has been demonstrated to be an essential protective antigen for acellular pertussis vaccine against whooping cough. In order to investigate the associated functionality ascribed to its components, we have purified A and B oligomers for the activity study. The A oligomer (S1 subunit) of PT was expressed in E. coli B834 (DE3) harboring expression vector (pET-20b) with the insert of S1 coding region and purified by metal-chelating column. The B oligomer was isolated by a single-step purification procedure. Individually, recombinant S1 and B oligomer exhibited quite distinct biological activities in vivo. S1 subunit induced leukocytosis-promoting (LP) activity, but did not affect mouse body weight-gain. On the contrary, B oligomer reduced mouse body weight-gain but did not reveal LP activity. In vitro, the combination of S1 subunit and B oligomer could enhance the toxic activities as exhibited by native PT and showed an additive toxicity in CHO cell clustering test and hemagglutination assay.     

Characterization of cortical neuron outgrowth in two- and three-dimensional culture systems

To improve the ability of regeneration by grafting living cells or by adding growth factor to a lesion site, it is important to find good biomaterials for neuron survival and regeneration. This study focused on two- and three-dimensional cultures in a matrix using biomaterials such as agarose, collagen, fibrin, and their mixtures, because these are considered to be suitable biomaterials for neuron outgrowth. Cortical neurons were dissected from E17 rat embryos and cultured in agarose gel, collagen gel, fibrin glue, and mixtures of collagen and fibrin. Results showed that neurons cultured in collagen gel and fibrin glue had longer periods of survival (more than 3 weeks) and better neurite extension than those observed in agarose gels. As to the survival rate according to the MTT and lactate dehydrogenase assays, fibrin glue was the most suitable biomaterial for neuron survival among the biomaterials examined. With two-dimensional fibrin plating, neuron cells exhibited cell aggregation and stress fibers, but the same results were not observed with collagen gel. There were no differences in neurite extension and survival in the mixtures of collagen and fibrin. The results suggest that collagen and fibrin can provide a suitable substrate for a three-dimensional culture matrix for neuronal survival and differentiation.     

Serum hepatitis B virus DNA in healthy HBsAg-negative Chinese adults evaluated by polymerase chain reaction

Serum hepatitis B virus (HBV) DNA was assayed using polymerase chain reaction, in 107 HBsAg-negative normal Chinese subjects. The results showed that eight subjects (7.5%) had HBV DNA. In the subgroup with antibody to hepatitis B surface antigen (anti-HBs) and to hepatitis B core antigen (anti-HBc), 7.3% (5/68) were positive for HBV DNA; HBV DNA was not detected in six individuals with anti-HBs only and in nine with anti-HBc only. In four persons with anti-HBc and anti-HBe, one had HBV DNA. In 20 subjects negative for all hepatitis B serological markers, two (10%) were found to have HBV DNA. This study indicates that serological markers are not adequate to rule out HBV infection, and it further implies that present blood donor screening methods may need improving.     

Hyperplasia and tumors of the parathyroid glands

Zusammenfassung Die verschiedenen Formen des Hyperparathyreoidismus werden überwiegend von Hyperplasien und Adenomen der Nebenschilddrüsen verursacht. Während früher die Diagnose des Pathologen (meist schon im intraoperativen Gefrierschnitt) für das chirurgische Vorgehen maßgebend war, wird das Operationsausmaß heute überwiegend durch die wesentlich verbesserte präoperative Diagnostik bestimmt (bildgebende Verfahren) und durch den nach der Entfernung der vergrößerten Nebenschilddrüse(n) intraoperativ gemessenen Abfall des Parathormons kontrolliert. Nichtsdestotrotz sollte dem Pathologen die morphologische Differenzialdiagnose der Hyperplasie, des Adenoms und Karzinoms der Nebenschilddrüsen geläufig sein.

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Development of fungal mycelia as a skin substitute: characterization of keratinocyte proliferation and matrix metalloproteinase expression during improvement in the wound-healing process

SACCHACHITIN membranes, prepared from the waste residue of the fruiting body of Ganoderma taugae, were used in our previous study to enhance skin wound healing in animal models. In the present study, the effects of the membrane on the growth of keratinocytes and the activity of matrix metalloproteinases (MMPs), as well as on the healing of skin wounds in humans, were estimated. Fresh human foreskin was employed as the source of the keratinocyte culture, and a modified keratinocyte-SFM medium supplemented with 0.2 ng/mL of recombinant epidermal growth factor and 30 microg/mL bovine pituitary extract was used to enhance the successful growth of keratinocytes under an atmosphere of 5% CO2, at 37 degrees C. The results indicated that 0.01% SACCHACHITIN enhanced the proliferation of keratinocytes in the culture on the fourth and fifth days, and cells showed neither morphological alteration nor disordered proliferation. This evidence clearly indicated that SACCHACHITIN was not cytotoxic to and was safe for the growth of keratinocytes. Thus, SACCHACHITIN might play a positive role in the proliferation and differentiation of keratinocytes around wounds and in accelerated wound healing of epidermal tissue. In addition, microscopic observations during the growth of keratinocytes showed that normal proliferation and differentiation took place along the margin of the SACCHACHITIN membrane. This indicates that SACCHACHITIN is possibly cytocompatible with keratinocytes. Electrophoretic analysis and inhibition tests for the binding effect of SACCHACHITIN on MMPs showed that SACCHACHITIN reduced MMPs in extracellular matrix degradation and facilitated establishment of an extracellular matrix around wounds; these effects resulted in rapid wound healing. SACCHACHITIN was used as a skin dressing for patients who had skin chronicle ulcer, which had not healed for over 7 months. Preliminary clinical observations showed that the wound improved and began to heal. An analysis of MMPs by ELISA in tissue of the wound indicated a significant decrease in MMP levels.     

Status of hepatitis B virus DNA in hepatocellular carcinoma: a study based on paired tumor and nontumor liver tissues

To investigate the hepatitis B virus (HBV) DNA status in the liver when hepatocellular carcinoma (HCC) has developed, 35 paired nontumorous and tumorous liver tissues from 27 hepatitis B surface antigen (HBsAg)-seropositive and 8 HBsAg-negative patients with HCC were studied by Southern blot analysis. The hybridization patterns of HBV DNA were different in the nontumor and tumor parts in 26 (96.3%) of the 27 HBsAg-positive patients. In the nontumor parts, integration of HBV DNA into the host genome was significantly less when compared to the tumor parts (15/27 vs. 25/27, P less than 0.05), whereas free replicative viral forms were significantly more frequent (17/27 vs. 7/27). The integrated HBV DNA in the nontumor parts showed discrete band patterns in the majority of cases (13/15). Hepatitis B e antigen (HBeAg) was significantly associated with the expression of free replicative forms of HBV DNA in the tumor tissues. An integrated HBV DNA sequence was detected in the tumor part of one HBsAg-negative patient, but not in her nontumor counterpart. Our observation that discrete integrated HBV DNAs are present in the nontumor part, representing subclinical clonal expansion that precedes the development of HCC, suggests the risk of future new tumor growth from these cell clones.     

Novel neuritic clusters with accumulations of amyloid precursor protein and amyloid precursor-like protein 2 immunoreactivity in brain regions damaged by thiamine deficiency.

Experimental thiamine deficiency (TD) is a classical model of a nutritional deficit associated with a generalized impairment of oxidative metabolism and selective cell loss in the brain. In rats, TD-induced cell degeneration is accompanied by an accumulation of amyloid precursor protein (APP)/amyloid precursor-like protein 2 (APLP2) immunoreactivity in abnormal neurites and perikarya along the periphery of, or scattered within, the lesion. Prompted by these data and our previous findings of a genetic variation in the development of TD symptoms, we extended our studies to mice. C57BL/6, ApoE knockout, and APP YAC transgenic mice received thiamine-deficient diet and pyrithiamine injections. Unlike rats, APP/APLP2-immunoreactive neurites in all strains of mice were sparsely scattered within damaged areas and did not delimit the thalamic lesion. In addition, abnormal clusters of intensely immunoreactive neurites occurred only in areas of damage including the thalamus, mammillary body, and inferior colliculus. The clusters appeared as either irregular clumps or round or oval rosettes that strikingly resembled the neuritic component of Alzheimer amyloid plaques. However, immunostaining using various antisera to synthetic amyloid beta-protein (A beta 1-40) and thioflavine S histochemistry failed to show evidence of a component of A beta Neither APP/APLP2-immunoreactive clusters nor amyloid plaques were observed in the brain from patients with Wernicke-Korsakoff syndrome, the clinical manifestation of TD in man. Our results demonstrate species (i.e., genetic) differences in the response to TD-induced damage and support a role for APP and APLP2 in the response to brain injury. This is the first report that chronic oxidative deficits can lead to this novel pathology.     

Recombinant hepatitis delta antigen from E. coli promotes hepatitis delta virus RNA replication only from the genomic strand but not the antigenomic strand

Hepatitis delta antigen (HDAg) of hepatitis delta virus (HDV) typically consists of two related protein species. The small HDAg (S-HDAg) is a 24-kDa protein of 195 amino acids and the large HDAg (L-HDAg) is a 27-kDa protein with an additional 19 amino acids at its C-terminus. These two proteins have distinct functions in the HDV life cycle. We have developed conditions for expressing S-HDAg and L-HDAg in E. coli as soluble proteins to facilitate large-scale purification. These proteins were purified to homogeneity and shown to be biologically active. Transfection of the purified recombinant S-HDAg together with HDV genomic RNA resulted in viral RNA replication. Surprisingly, the purified S-HDAg could not initiate replication from the antigenomic-sense HDV RNA, even though the latter led to RNA replication when transfected with an mRNA encoding the S-HDAg. These results suggest that initiation of HDV RNA synthesis from the antigenomic RNA may require a form of HDAg that is modified in mammalian cells; in contrast, RNA synthesis from the genomic RNA could be initiated by the recombinant S-HDAg from E. coli. Interestingly, the purified L-HDAg appeared as multiple protein species, including one corresponding to S-HDAg, probably as a result of degradation. The partially proteolyzed L-HDAg also initiated HDV RNA replication under the same conditions. These results add to the mounting evidence that genomic- and antigenomic-strand HDV RNA syntheses are carried out by different mechanisms.     

Selective decline in protein F1 phosphorylation in hippocampus of senescent rats

Certain forms of neuronal plasticity have been found to be expressed through alterations in brain protein phosphorylation, and its regulation by protein kinase activity. Of interest in this regard is the possibility that the decline in neuronal plasticity and cognitive function that occurs in advanced age may result in part from altered phosphorylation of specific proteins. As a first attempt to identify age-related changes in phosphoproteins, we assayed in vitro phosphorylation of proteins in hippocampus, cerebellum, entorhinal cortex, and frontal cortex from Fischer-344 rats of 5 months, 11 months, and 25 months of age. Compared to the middle-aged animals, the aged rats showed a selective 46% decline in phosphorylation of the 47 kDa protein (F1) in hippocampus, with no change in the phosphorylation of other proteins measured in this structure. Aged animals also showed decreased phosphorylation relative to young animals. No age-related change was observed in any protein band for the other brain areas examined. Since protein F1 is phosphorylated by protein kinase C (PKC), the cytosolic and membrane distribution of this enzyme was compared across age groups. The activity of PKC in hippocampus did not change across age. The explanation of this age-related decline in protein F1 phosphorylation is likely to be a decline in the substrate protein itself. The results are discussed in terms of protein F1's possible role in age-related decline of hippocampal synaptic plasticity.