Latent adeno-associated virus infection elicits humoral but not cell-mediated immune responses in a nonhuman primate model

Latent infection with wild-type (wt) adeno-associated virus (AAV) was studied in rhesus macaques, a species that is a natural host for AAV and that has some homology to humans with respect to the preferred locus for wt AAV integration. Each of eight animals was infected with an inoculum of 10(10) IU of wt AAV, administered by either the intranasal, intramuscular, or intravenous route. Two additional animals were infected intranasally with wt AAV and a helper adenovirus (Ad), while one additional animal was inoculated with saline intranasally as a control. There were no detectable clinical or histopathologic responses to wt AAV administration. Molecular analyses, including Southern blot, PCR, and fluorescence in situ hybridization, were performed 21 days after infection. These studies indicated that AAV DNA sequences persisted at the sites of administration, albeit at low copy number, and in peripheral blood mononuclear cells. Site-specific integration into the AAVS1-like locus was observed in a subset of animals. All animals, except those infected by the intranasal route with wt AAV alone, developed a humoral immune response to wt AAV capsid proteins, as evidenced by a >/=fourfold rise in anti-AAV neutralizing titers. However, only animals infected with both wt AAV and Ad developed cell-mediated immune responses to AAV capsid proteins. These findings provide some insights into the nature of anti-AAV immune responses that may be useful in interpreting results of future AAV-based gene transfer studies.

Sustained secretion of human alpha-1-antitrypsin from murine muscle transduced with adeno-associated virus vectors

Recombinant adeno-associated virus (AAV) vectors have been used to transduce murine skeletal muscle as a platform for secretion of therapeutic proteins. The utility of this approach for treating alpha-1-antitrypsin (AAT) deficiency was tested in murine myocytes in vitro and in vivo. AAV vectors expressing the human AAT gene from either the cytomegalovirus (CMV) promoter (AAV-C-AT) or the human elongation factor 1-alpha promoter (AAV-E-AT) were examined. In vitro in C2C12 murine myoblasts, the expression levels in transient transfections were similar between the two vectors. One month after transduction, however, the human elongation factor 1 promoter mediated 10-fold higher stable human AAT expression than the CMV promoter. In vivo transduction was performed by injecting doses of up to 1.4 x 10(13) particles into skeletal muscles of several mouse strains (C57BL/6, BALB/c, and SCID). In vivo, the CMV vector mediated higher levels of expression, with sustained serum levels over 800 micrograms/ml in SCID and over 400 micrograms/ml in C57BL/6 mice. These serum concentrations are 100,000-fold higher than those previously observed with AAV vectors in muscle and are at levels which would be therapeutic if achieved in humans. High level expression was delayed for several weeks but was sustained for over 15 wk. Immune responses were dependent upon the mouse strain and the vector dosage. These data suggest that recombinant AAV vector transduction of skeletal muscle could provide a means for replacing AAT or other essential serum proteins but that immune responses may be elicited under certain conditions.

A fluorescence video-endoscopy technique for detection of gene transfer and expression

The green fluorescent protein (GFP) has previously been adapted as a reported for gene transfer and expression in mammalian cells in culture and in tissue sections. Herein is described a new method for detecting GFP in situ within epithelia accessible to fiberoptic endoscopy by incorporating fluorescent filters for detection of GFP into an existing fiberoptic endoscopy system. This device was used to detect expression of GFP from adeno-associated virus (AAV; does of 3 x 10(7) IU) and adenovirus (Ad; does of l x 10(9) to 1 x 10(10) p.f.u.) vectors within the bronchial epithelium of New Zealand white rabbits. GFP expression was confirmed by fluorescence-activated cell sorting (FACS), direct fluorescence microscopy of cytospin preparations of brushed cells, and by fluorescence microscopy of fixed tissue sections. This reporter gene/detection system was then used to track the time course of expression of the AAV vector in the bronchial epithelium over the first 30 days after administration. The transduction frequency in the treated region of the epithelium peaked at around 50% at 21 days after transduction. Vector expression was still present at around 20% efficiency at 30 days after administration. This example indicates how this method could be used to reliably track gene transfer in living animals or patients.

Activation and inhibition of rat neuronal nicotinic receptors by ABT-418

1. ABT-418 appeared to function as a relatively broad spectrum activator of neuronal nicotinic receptors, expressed in Xenopus oocytes, with little cross reactivity to the mammalian muscle receptor subtype. However, the relative potencies of ABT-418 at the various subtypes differed from those acetylcholine (ACh). For example, ACh was most potent at alpha 3 beta 2 (EC50 approximately 30 microM) and least potent at alpha 2 beta 2 (EC50 approximately 500 microM). ABT-418 was most potent at alpha 4 beta 2 and alpha 2 beta 2 (EC50 approximately 6 microM and 11 microM, respectively) and least potent at alpha 3 beta 4 (EC50 approximately 188 microM). 2. In addition to activating neuronal receptors, ABT-418 exhibited complex properties, including the inhibition of ACh responses. 3. The current responses elicited by relatively high concentrations of ABT-418 on the alpha 4 beta 2 receptor subtype were protracted beyond the application interval. The coapplication of ABT-418 with either of the use-dependent inhibitors bis(1,2,2,6,6-tetramethyl-4-pipendimyl)sebacate (BTMPS) or tetramethyl-pipenidine (TMP) eliminated the late protracted phase of the currents with only small effects on the initial activation phase. When the reversible inhibitor TMP was washed from the bath, the previously inhibited late current reappeared, suggesting that the observed mixed agonist-antagonist effects of ABT-418 and (+/-)-epibatidine on alpha 4 beta 2 were due to a concentration-dependent noncompetitive inhibition, an effect similar to that obtained for (-)-nicotine. 4. The inhibition of alpha 4 beta 2 receptors by ABT-418 was voltage-dependent. When high concentrations of ABT-418 were applied under depolarizing conditions, additional late currents could be observed under conditions which suggested that a build up of ABT-418 in an unstirred layer over the surface of the oocyte was occurring. This may have been due to the dissociation of the drug from channel blocking sites on the receptors themselves, or alternatively, from the plasma membrane of the cells.

Stability and compatibility of admixtures of intravenous ciprofloxacin and selected drugs

The stability and compatibility of ciprofloxacin with selected drugs in intravenous admixtures were studied. Ciprofloxacin 2 mg/mL in 5% dextrose was combined with each of 22 other drugs at concentrations commonly used in clinical practice. Each combination was maintained at room temperature (approximately 22 degrees C) in constant fluorescent light. Immediately after preparation and at 6 and 24 hours, each admixture was examined visually in normal fluorescent room light and the pH value was determined. For samples lacking visible precipitates or having pH changes of not more than 1 unit, ciprofloxacin concentration was assayed by using high-performance liquid chromatography. When combined with ciprofloxacin, 14 of the study drugs did not alter the concentration of ciprofloxacin, including amikacin sulfate, atracurium besylate, aztreonam, cimetidine hydrochloride, dobutamine hydrochloride, fluconazole, gentamicin sulfate, metronidazole (intravenous, ready to use), midazolam hydrochloride, norepinephrine bitartrate, pancuronium bromide, potassium chloride, tobramycin sulfate, and vecuronium bromide. There were five drugs that were determined to be incompatible with ciprofloxacin because of precipitate formation (amphotericin B, ampicillin sodium/sulbactam sodium, cefuroxime sodium, piperacillin sodium, and sodium bicarbonate). Incompatibility with ciprofloxacin based on pH changes of more than 1 unit was found with four drugs: ampicillin sodium/sulbactam sodium, ceftazidime, metronidazole hydrochloride (powder only), and ticarcillin disodium/clavulanate potassium. Intravenous ciprofloxacin 2 mg/mL admixed in 5% dextrose was stable and compatible with 14 of the 22 test drugs for up to 24 hours at room temperature. The other eight drugs should not be combined with ciprofloxacin.

Effect of haemodilution on transfusion requirements in liver resection

Between April, 1988, and February, 1989, 22 consecutive patients underwent liver resection (17 hepatectomy, 5 segmentectomy) with intraoperative haemodilution to avoid blood transfusion. The results were compared with those of 22 patients who underwent liver resection without haemodilution between February, 1987, and April, 1988, and who were matched for the nature of the tumour and the type of liver resection. Age, preoperative haematocrit and haemoglobin concentration, and intraoperative blood loss did not differ between the groups who did and did not undergo haemodilution. There was no abnormal bleeding during liver transection in haemodiluted patients. No allogeneic blood products at all were needed in a significantly greater proportion of the group with haemodilution than of the group without (19 [86%] vs 6 [27%]). The two groups also showed significant differences in the total requirements of allogeneic packed red cells (haemodilution 9 units, no haemodilution 84 units) and fresh frozen plasma (9 vs 119 units). Although the haematocrit was slightly but significantly lower in the group who underwent haemodilution than in those who did not on postoperative days 1 and 8, the differences had disappeared by the second postoperative month. Postoperative complication rates, abnormal results in liver biochemical tests, and lengths of hospital stay were the same in patients with and without haemodilution. Intraoperative haemodilution in patients undergoing liver resection reduced requirements for all blood products, further lowering the risks associated with liver resection.

Increased nephrotoxicity of gentamicin in pyelonephritic rats

Multiple factors may increase the nephrotoxic potential of aminoglycosides. We studied gentamicin susceptibility of kidneys infected with E. coli. Several parameters of renal function, histological changes on light and electron microscopy, and drug levels in renal parenchyma were compared in pyelonephritic and normal rats treated with low doses (10 mg/kg/Q8 hr for 3 days), or high doses (60 mg/kg/day for 14 days), of gentamicin. A significant increase (P less than 0.01) in beta-galactosidase and protein excreted in urine over a period of 17 days associated with severe changes in diuresis and osmolality was noted in the infected treated rats (low doses) compared with normal, treated, infected or control animals. Histological modifications compatible with gentamicin nephrotoxicity were more persistent in the infected treated animals. A significant decrease in 14C inulin (P less than 0.01) and 3H-PAH clearance and secretion (P less than 0.02) was observed in the infected treated rats receiving high doses of antibiotics. Cellular necrosis and tubular desquamation also were more severe in this group. Gentamicin levels in the cortex and medulla of infected animals were significantly higher than in the normals (P less than 0.01) and might have been responsible for the increased toxicity noted in the pyelonephritic animals. Infected kidneys appeared to be more susceptible to the nephrotoxic potential of gentamicin.

Arginine regulation of gramicidin S biosynthesis

Several amino acids are known to affect the gramicidin S producer Bacillus brevis ATCC 9999 with respect ot growth, soluble gramicidin S synthetase formation, antibiotic production, or a combination of these. Our studies confirmed that arginine has paradoxical effects on the B. brevis fermentation; it markedly increased growth and antibiotic production, yet decreased the soluble heavy gramicidin S synthetase activity. We found that arginine did not repress heavy gramicidin S synthetase. The amino acid stimulated growth and increased specific antibiotic production presumably by supplying a limiting precursor (ornithine) for gramicidin S synthesis. Although the amino acid decreased the specific activity of the soluble heavy gramicidin S synthetase, it markedly increased the particulate enzyme activity which persisted hours after the soluble heavy gramicidin S synthetase disappeared. One percent arginine was the optimum level for growth and gramicidin S production. After growth in 1% arginine, heavy synthetase activity in the particulate fraction more than doubled. We propose that arginine leads to the soluble enzyme becoming membrane bound and more stable in vivo. Although we found arginine capable of inhibiting the action of soluble heavy gramicidin S synthetase, this was not the mechanism involved in the lowering of soluble heavy gramicidin S synthetase specific activity.

[Biological changes in 88 cases of Basedow's disease treated by radioactive iodine]

Biological abnormalities, in particular increased T3 and sometimes TSH, are frequently found in thyrotoxic patients treated with radioactive iodine and subsequently enthyroid. A high T3, associated with an increase in FT4 and a low TSH precedes a relapse. An increase in TSH may indicate progression towards hypothyroidism; even if FT4 and T3 levels are within normal limits. Caution must be exercised before affirming that an increased TSH with a high T3 and normal FT4 is indicative of thyroid equilibrium. At all events, the risk of hypothyroidism despite the use of small doses of radioactive iodine is such that the classical limit for the treatment of patients with thyrotoxicosis should be increased beyond the age of 40. In patients with a high TSH despite being clinically euthyroid, the use of thyroid extract in low dosage (50 mg/day) would appear to be desirable in avoiding the subsequent development of hypothyroidism.