Expression of biologically active atrial natriuretic factor following intrahepatic injection of a replication-defective adenoviral vector in dogs

Serum atrial natriuretic peptide (ANP) as an objective indicator for the diagnosis of neurogenic shock: animal experiment and human case report

In forensic medicine, the diagnosis of death due to neurogenic shock is considered to be an aporia, as lacking objective indicators and presenting atypical symptoms in autopsy. Medico-legal disputes and complaints occasionally result from this ambiguity. To explore potential objective indicators of neurogenic shock, we set up a model of neurogenic shock by applying an external mechanical force on the carotid sinus baroreceptor in rabbits. The serum atrial natriuretic peptide (ANP) level was measured by radioimmunoassay in the control group (n = 8), survival group (n = 15) and death group (n = 5) both before and after the insult. The serum ANP level showed a significant increase after the insult in the death group compared with the serum obtained before the insult (P = 0.006), while the serum ANP level after the insult in the survival group and control group was not statistically significant compared with the serum obtained before the insult (P = 0.332 and P = 0.492, respectively). To verify the repeatability of the model and the postmortem behavior of serum ANP, five healthy adult rabbits underwent the same procedure as the experimental group. The mortality rate was consistent with the former experiment (20 %). There were no significant changes in serum ANP level in vitro and in vivo (within 48 and 24 h, respectively). But there was a significant decrease in serum ANP level at 48 h postmortem in vivo (P = 0.001). A female patient who expired due to neurogenic shock during a hysteroscopy was reported. Neither fatal primary disease nor evidence for mechanical injuries or intoxication was found according to the autopsy. The serum ANP level was assayed as a supplementary indicator and was found to be three-fold higher than the normal maximum limit. Combined with the animal experiment, this case highlights that serum ANP has the potential to be an objective indicator for the diagnosis of death due to neurogenic shock.

Adenovirus-mediated atrial natriuretic protein expression in the lung protects rats from hypoxia-induced pulmonary hypertension

Endogenous as well as exogenous atrial natriuretic peptide (ANP) attenuates the development of chronic hypoxic pulmonary hypertension (CHPH) in rats. We built a recombinant adenovirus type 5 containing ANP cDNA under the control of the Rous sarcoma virus long terminal repeat (Ad.ANP). The efficiency of this vector in delivering the ANP gene was first examined in rat primary cultures of pulmonary vessel smooth muscle cells (SMCs) in comparison with Ad.beta GAL. Conditioned medium collected from Ad.ANP-infected cells (1000 TCID(50)/cell) contained 5 x 10(9) M immunoreactive ANP and elicited relaxation of isolated rat pulmonary arteries preconstricted with phenylepinephrine. To examine the effects of adenovirus-mediated ANP expression in the CHPH rat lung, Ad.ANP or Ad.beta GAL was administered via the tracheal route. Immunoreactive ANP was detected in bronchoalveolar fluid as early as 4 days and until 10-17 days after Ad.ANP administration (5 x 10(8) TCID(50)). Lung ANP immunostaining was mainly localized in bronchial and alveolar epithelial cells. As compared with Ad.beta GAL-treated controls, rats given Ad.ANP (5 x 10(8) TCID(50)) on the day before a 2-week exposure to hypoxia (10% O(2)) had lower values for pulmonary artery pressure (32.1 +/- 1.93 vs. 35.5 +/- 2 mmHg, p < 0.01) and Fulton's index (0.52 +/- 0.089 vs. 0.67 +/- 0.12, p < 0.001) and less severe right ventricular hypertrophy and distal vessel muscularization. These results suggest that induction of ANP expression in the lung may hold promise in the treatment of pulmonary hypertension.

Adenovirus-mediated transfer of the atrial natriuretic peptide gene in rat pulmonary vascular smooth muscle cells leads to apoptosis

Atrial natriuretic peptide (ANP) exhibits relaxant and growth-inhibiting effects on vascular smooth muscle cells (VSMCs). To obtain ANP gene expression in VSMCs, we built a recombinant adenovirus containing the ANP cDNA controlled by the adenovirus major late promotor (AdMLP-ANP). After pulmonary VSMC treatment with AdMLP-ANP at a multiplicity of infection ranging from 5 to 100 TCID(50)/cell, immunoreactive ANP was detectable in the cell culture medium at a level that reached 101 +/- 27 pmol/well after 2 days. The newly expressed ANP was biologically active, as evidenced by its ability to induce cyclic guanosine monophosphate accumulation in target cells and to mimic the effect of exogenous ANP (10(-8) to 10(-7) mol/L). Cell growth and survival of AdMLP-ANP-infected cells were decreased and were associated with the promotion of VSMC apoptosis. These effects, which occurred at a multiplicity of infection of 10 to 100 TCID(50)/cell, were observed neither in cells infected with the control adenoviral constructs (AdMLP-betaGAL and AdMLP-gD) nor in cells treated with exogenous ANP (10(-7) to 10(-6) mol/L). These results showing VSMC apoptosis in response to ANP gene expression may have important implications for the prevention of vascular remodeling by gene therapy.

Short-term efficiency and safety of gene delivery into canine kidneys

BACKGROUND

Gene delivery of biologically active molecules to the kidney may have potential therapeutic applications in renal and cardiovascular diseases. Recombinant adenovirus is one of the most efficient vectors for in vivo gene delivery. However, in vivo toxicity at the site of administration has to be evaluated for the successful use of adenovirus-mediated gene transfer. The aim of this study was to document precisely the short-term safety of different routes of intra-renal adenoviral administration and to compare their transduction efficiency.

METHODS

Dog puppies were injected with an adenoviral vector expressing the beta-galactosidase reporter gene in both kidneys via three different routes, i.e. intra-renal-ureteral route (IU) and intra-renal-arterial route with (IAC) or without (IA) clamping of the renal vein. Toxicity of viral administration was assayed on day 4 at both physiological and histological levels. Renal samples were monitored for the presence of nuclear beta-galactosidase-expressing cells.

RESULTS

All renal physiological parameters (glomerular filtration rate, effective renal plasma flow, and electrolyte excretion fractions) remained stable whatever the route of viral administration. No histological lesion was detected in any of the haematoxylin-eosin-stained kidney sections, and there was no evidence of ischaemia-reperfusion injury in the kidneys subjected to venous clamping. Efficient transgene expression was obtained in dog kidneys following IAC and IU injection of adenoviral vectors. Gene transfer via the IAC route induced gene expression predominantly in the cortical interstitial cells. Retrograde IU adenoviral injection resulted in reduced transduction efficiency compared with the IAC route, with transgene expression occurring mainly in the distal tubular and pyelic epithelial cells.

CONCLUSIONS

The two major findings of this study were (i) the absence of acute histological and functional renal alteration following intra-arterial and intra-ureteral injections of adenoviral vectors in both kidneys of healthy dogs, and (ii) the efficiency of transgene expression with specific cellular targeting according to the route of administration.

Mechanical unloading versus neurohumoral stimulation on myocardial structure and endocrine function In vivo

BACKGROUND-Mechanical load and humoral stimuli such as endothelin (ET) and angiotensin II (Ang II) are potent modulators of cardiac structure and endocrine function, specifically gene expression and production and release of atrial natriuretic peptide (ANP). We define the contribution of mechanical load compared with neurohumoral stimulation in vivo with specific focus on myocardial and circulating ANP during chronic myocardial unloading produced by thoracic inferior vena caval constriction (TIVCC). METHODS AND RESULTS-TIVCC was produced by banding the IVC for 10 days in 7 dogs, whereas in the 6 control dogs, the band was not constricted. TIVCC was characterized by a decrease in cardiac output, right atrial pressure, and left ventricular (LV) end-diastolic diameter and marked activation of ET and Ang II in plasma and atrial and ventricular myocardium. Despite neurohumoral stimulation, LV mass index and myocyte diameters in unloaded hearts decreased, reflecting myocyte atrophy. The total number of myocytes in the LV remained unchanged. Atrial stores of ANP increased, but plasma ANP did not change, in association with a trend toward ANP gene expression to decrease in unloaded hearts. CONCLUSIONS-Chronic mechanical unloading of the heart results in myocardial atrophy and lack of activation of ANP synthesis despite marked neurohumoral stimulation by the growth promoters ET and Ang II.