Prospects for gene transfer for clinical heart failure

Congestive heart failure is an inexorable disease associated with unacceptably high morbidity and mortality. Preclinical results indicate that gene transfer using various proteins is a safe and effective approach for increasing function of the failing heart. In the current review, we provide a summary of cardiac gene transfer in general and summarize findings using adenylyl cyclase 6 as therapeutic gene in the failing heart. We also discuss the potential usefulness of a new treatment for congestive heart failure, paracrine-based gene transfer.

[Clinical analysis of facial nerve palsy in middle ear and mastoid surgery in 23 cases]

OBJECTIVE

To investigate the cause, the prevention and the therapy of facial nerve palsy(FNP) which induced by the operation of middle ear and mastoid surgery.

METHOD

A series of 1032 cases undergone middle ear and mastoid surgery were reviewed between 1976 and 1991.

RESULT

23 cases FNP were identified. All were incomplete and peripheral. 13 cases of them were performed decompression of facial nerve. 6 cases were cure, 4 cases on the mend and 3 cases no effect after operation. 10 cases were treated by conservation, 5 cases were cure, 3 cases on the mend and 2 cases no effect.

CONCLUSION

If the facial paralysis occurs during the operation, which means that facial nerve is damaged, except hard-stuff reason. Exploration should be done at once. If facial paralysis occurs later, conservative therapy should be selected at first. If facial paralysis is still not on the mend 1 month of postoperation, one should be done exploration of facial nerve.

Intracoronary delivery of adenovirus encoding adenylyl cyclase VI increases left ventricular function and cAMP-generating capacity

BACKGROUND

We tested the hypothesis that intracoronary injection of a recombinant adenovirus encoding adenylyl cyclase type VI (AC(VI)) would increase cardiac function in pigs.

METHODS AND RESULTS

Left ventricular (LV) dP/dt and cardiac output in response to isoproterenol and NKH477 stimulation were assessed in normal pigs before and 12 days after intracoronary delivery of histamine followed by intracoronary delivery of an adenovirus encoding lacZ (control) or AC(VI) (1.4x10(12) vp). Animals that had received AC(VI) gene transfer showed increases in peak LV dP/dt (average increase of 1267+/-807 mm Hg/s; P=0.0002) and cardiac output (average increase of 39+/-20 mL. kg(-1). min(-1); P<0.0001); control animals showed no changes. Increased LV dP/dt was evident 6 days after gene transfer and persisted for at least 57 days. Basal heart rate, blood pressure, and LV dP/dt were unchanged, despite changes in cardiac responsiveness to catecholamine stimulation. Twenty-three hour ECG recordings showed no change in mean heart rate or ectopic beats and no arrhythmias. LV homogenates from animals receiving AC(VI) gene transfer showed increased AC(VI) protein content (P=0.0007) and stimulated cAMP production (P=0.0006), confirming transgene expression and function; basal LV AC activity was unchanged. Increased cAMP-generating capacity persisted for at least 18 weeks (P<0.0002).

CONCLUSIONS

Intracoronary injection of a recombinant adenovirus encoding AC provides enduring increases in cardiac function.

[An experimental study on inhibitory effect of xinjierkang granules on virus myocarditis]

OBJECTIVE

To investigate the inhibitory effect of Xinjierkang(XJEK) granules on virus myocarditis.

METHODS

Using a model mouse of virus myocarditis induced by coxsackie virus B3m (CVB3m) and mouse toxic myocarditis induced by adriamycin, a model of arrhythmia induced by BaCl2 and CHCl3, a model of inflammation caused by egg white and agar, along with a dynamic test of cardiac blood flow and an inhibitory test of CVB3m in vitro.

RESULTS

XJEK granules are efficacious in inhibiting CVB3m both in vitro and in vivo, protecting and curing virus myocarditis and toxic myocarditis in mice, reducing mouse death rate, serum level of LDH, AST and CK, titer of neutralizing antibodies, virus concentration of heart, and improving the abnormal ECG, pathological and ultrastructural damage of myocadium. The granules are also good for anti-inflammation, anti-myocardial ischemia, anti-arrhythmia, as well as for strengthening myocardiac contraction and increasing the serum IgG level.

CONCLUSION

Xinjerkang granules possess an inhibitory effect on virus myocarditis and toxic myocarditis.

Cardiac-directed adenylyl cyclase expression improves heart function in murine cardiomyopathy

BACKGROUND

We tested the hypothesis that increased cardiac myocyte adenylyl cyclase (AC) content increases cardiac function and response to catecholamines in cardiomyopathy.

METHODS AND RESULTS

Transgenic mice with cardiac-directed expression of AC type VI (ACVI) were crossbred with mice with cardiomyopathy induced by cardiac-directed Gq expression. Gq mice had dilated left ventricles, reduced heart function, decreased cardiac responsiveness to catecholamine stimulation, and impaired beta-adrenergic receptor (betaAR)-dependent and AC-dependent cAMP production. Gq/AC mice showed improved basal cardiac function in vivo (P=0.01) and ex vivo (P<0.0005). When stimulated through the betaAR, cardiac responsiveness was increased (P=0.02), and cardiac myocytes showed increased cAMP production in response to isoproterenol (P=0.03) and forskolin (P<0.0001).

CONCLUSIONS

Increasing myocardial ACVI content in cardiomyopathy restores cAMP-generating capacity and improves cardiac function and responsiveness to betaAR stimulation.

Adenylylcyclase increases responsiveness to catecholamine stimulation in transgenic mice

BACKGROUND

The cellular content of cAMP generated by activation of adenylylcyclase (AC) through the beta-adrenergic receptor (betaAR) is a key determinant of a cell's response to catecholamine stimulation. We tested the hypothesis that increased AC content, independently of betaAR number, increases responsiveness to catecholamine stimulation in vivo.

METHODS AND RESULTS

Transgenic mice with cardiac-directed expression of ACVI showed increased transgene AC expression but no change in myocardial betaAR number or G-protein content. When stimulated through the betaAR, cardiac function was increased, and cardiac myocytes showed increased cAMP production. In contrast, basal cAMP and cardiac function were normal, and long-term transgene expression was not associated with abnormal histological findings or deleterious changes in cardiac function.

CONCLUSIONS

The amount of AC sets a limit on cardiac beta-adrenergic signaling in vivo, and increased AC, independent of betaAR number and G-protein content, provides a means to regulate cardiac responsiveness to betaAR stimulation. Overexpressing an effector (AC) does not alter transmembrane signaling except when receptors are activated, in contrast to receptor/G-protein overexpression, which yields continuous activation and has detrimental consequences. Our findings establish the importance of AC content in modulating beta-adrenergic signaling in the heart, suggesting a new target for safely increasing cardiac responsiveness to betaAR stimulation.

Post-transcriptional regulation associated with control of human CD8A expression of CD4+ T cells

Lack of expression of a cell surface protein can occur by means of transcriptional and/or post-transcriptional mechanisms. Expression of the CD8A gene has been shown to be regulated by post-transcriptional mechanisms when 1) CD4(-)CD8(lo) thymocytes are blocked from differentiating into CD4(+)CD8(+) cells by TCR crosslinking and 2) upon activation of mature CD8(+) T cells. We demonstrate in this paper that there is also post-transcriptional regulation of CD8A expression in a CD4(+)CD8(-) T-cell line Jurkat. On the basis of northern blotting, mRNA for CD8A was not seen to be present in the Jurkat cells, but the gene was observed to be transcriptionally active in nuclear run-on analysis. In addition, we provide evidence that post-transcriptional mechanisms also contribute to the regulation of CD8A expression in mature CD4(+)CD8(-) T cells, challenging the assumption that the regulation is due solely to transcriptional mechanisms.

Functional importance of the cyclic AMP response element-like decamer motif in the CD8 alpha promoter

Expression of the CD8 gene is highly regulated during lymphocyte differentiation and in a tissue-specific manner. We characterized the human CD8 alpha promoter region to determine whether tissue specificity resides within the promoter and to define important regulatory elements. A set of six fragments 5' of the CD8 alpha gene were linked to a luciferase reporter gene. The luciferase activity was then measured in a transient transfection assay. We found that CD8 alpha promoter activity can be detected from a 146-bp fragment upstream of the translation start site, but not from a 133-bp fragment. The cyclic AMP response element (CRE)-like site within the 10 bp from -143 to -133 is critical for promoter activity. Mutation of the CRE/decamer in the context of a 429-bp fragment causes loss of activity. Tissue specificity does not reside in the 146-bp fragment because this fragment directs expression in both T and non-T cell lines. Fragments longer than 146 bp are generally expressed less well in the cell lines suggesting the potential existence of negative regulatory elements upstream of -146. Using a CRE/decamer-containing oligomer as a probe in an electrophoresis mobility shift assay, three retarded bands formed by proteins binding to the DNA were detected using nuclear extracts from two T cell lines. Two of the three bands contain proteins of the CRE-binding protein (CREB)/activating transcription factor (ATF) family. Because the CRE-binding protein/activating transcription factor proteins play a role in the expression of many other T cell-specific genes, our work strengthens the hypothesis that the CRE motif is important for regulating the expression of T cell-specific genes.

Functional importance of the cyclic AMP response element-like decamer motif in the CD8 alpha promoter

Expression of the CD8 gene is highly regulated during lymphocyte differentiation and in a tissue-specific manner. We characterized the human CD8 alpha promoter region to determine whether tissue specificity resides within the promoter and to define important regulatory elements. A set of six fragments 5' of the CD8 alpha gene were linked to a luciferase reporter gene. The luciferase activity was then measured in a transient transfection assay. We found that CD8 alpha promoter activity can be detected from a 146-bp fragment upstream of the translation start site, but not from a 133-bp fragment. The cyclic AMP response element (CRE)-like site within the 10 bp from -143 to -133 is critical for promoter activity. Mutation of the CRE/decamer in the context of a 429-bp fragment causes loss of activity. Tissue specificity does not reside in the 146-bp fragment because this fragment directs expression in both T and non-T cell lines. Fragments longer than 146 bp are generally expressed less well in the cell lines suggesting the potential existence of negative regulatory elements upstream of -146. Using a CRE/decamer-containing oligomer as a probe in an electrophoresis mobility shift assay, three retarded bands formed by proteins binding to the DNA were detected using nuclear extracts from two T cell lines. Two of the three bands contain proteins of the CRE-binding protein (CREB)/activating transcription factor (ATF) family. Because the CRE-binding protein/activating transcription factor proteins play a role in the expression of many other T cell-specific genes, our work strengthens the hypothesis that the CRE motif is important for regulating the expression of T cell-specific genes.