Improvement of Precision in Recombinant Adeno-Associated Virus Infectious Titer Assay with Droplet Digital PCR as an Endpoint Measurement

Recombinant adeno-associated virus (rAAV) has been utilized successfully for in vivo gene delivery for treatment of a variety of human diseases. To sustain the growth of recombinant AAV gene therapy products, there is a critical need for the development of accurate and robust analytical methods. Fifty percent tissue culture infectious dose (TCID50) assay is an in vitro cell-based method widely used to determine AAV infectivity, and this assay is historically viewed as a challenge due to its high variability. Currently, quantitative PCR (qPCR) serves as the endpoint method to detect the amount of replicated viral genome after infection. In this study, we optimize the TCID50 assay by adapting endpoint detection with droplet digital PCR (ddPCR). We performed TCID50 assays using ATCC AAV-2 reference standard stock material across 18 independent runs. The cell lysate from TCID50 assay was then analyzed using both qPCR and ddPCR endpoint to allow for direct comparison between the two methods. The long-term 1-year side-by-side comparison between qPCR and ddPCR as endpoint measurement demonstrated improved interassay precision when the ddPCR method was utilized. In particular, after the addition of a novel secondary set threshold for infectivity scoring of individual wells, the average infectious titer of 18 runs is 6.45E+08 with % coefficient of variation (CV) of 42.5 and 5.63E+08 with % CV of 34.9 by qPCR and ddPCR, respectively. In this study, we offer improvements of infectious titer assay with (1) higher interassay precision by adapting ddPCR as an endpoint method without the need of standard curve preparation; (2) identification of a second "set threshold" value in infectivity scoring that improves assay precision; and (3) application of statistical analysis to identify the acceptance range of infectious titer values. Taken together, we provide an optimized TCID50 method with improved interassay precision that is important for rAAV infectious titer testing during process development and manufacturing.

AB1137 CLASSIFICATION OF THE EARLY STAGE OF RAPIDLY DESTRUCTIVE COXOPATHY ACCORDING TO THE FEMORAL HEAD DESTRUCTION

Background:

Rapidly destructive coxopathy (RDC) is an unusual subset of osteoarthritis of the hip characterized by rapid chondrolysis with progressive loss of the joint space as the first manifestation of the disease. Because rapid progression of RDC makes it difficult to obtain sequential radiographs in its early stage, the process of disease progression in the early stage remains unclear. Although the pathogenesis of RDC is still unclarified, the potential causes of RDC include subchondral insufficiency fracture of the femoral head resulting from osteoporosis, pelvic posterior inclination in RDC as a mechanical factor, and increased serum levels of matrix metalloproteinase (MMP)-3 as a biological factor.

Objectives:

This study aimed to differentiate the process of disease progression in the early stage of RDC and provide its new classification system.

Methods:

This monocentric retrospective study included 42 female patients who met the criteria of RPOH, chondrolysis >2 mm during 12 months from the onset of hip pain based on a series of radiographs and computed tomography (CT). This study also included 9 female patients with osteoarthritis secondary to developmental dysplasia of the hip (DDH), who demonstrated chondrolysis >2 mm during 12 months from the onset of hip pain. Cortical thickness index (CTI) correlated with bone mineral density of the hip, pelvic tilt, and serum concentrations of matrix metalloproteinase (MMP)-3 were analyzed.

Results:

RDC were classified into two types based on the absence (type 1, n=17) and presence (type 2, n=25) of subsequent femoral head destruction shown by CT within 12 months after the onset of hip pain. MMP-3 significantly increased in RDC type 2 compared with type 1 and DDH. Increased posterior pelvic tilt was found in RDC type 2 compared with DDH. Logistic regression and receiver operating characteristic curve analyses indicated that MMP-3 may be associated with differentiation between RDC types 1 and 2. No difference was found in CTI between RDC types and DDH.

RDC type 2 hips developed partial (type 2A) and massive (type 2B) femoral head destruction within the first 12 months. Whereas partial destruction showed <20% collapse ratio, massive destruction demonstrated >40% collapse ratio. Increased posterior pelvic tilt was found in massive destruction. Femoral head destruction started earlier within the first 6 months in massive destruction compared with that in partial destruction. From receiver operating characteristic curve analysis, pelvic tilt differentiated the femoral head destruction types using the initial radiograph at the onset before first demonstration of femoral head destruction. No difference was found in CTI or MMP-3 between the two subtypes.

Conclusion:

Disease progression of RDC during 12 months after the onset of hip pain could be classified into two distinct types based on the absence (type 1) and presence (type 2) of femoral head destruction in association with MMP-3 and pelvic tilt as biological and mechanical factors, respectively. MMP-3 may be helpful to differentiate those two types in the early stage of RPOH. The extent of femoral head destruction could further differentiate RDC type 2 into two subtypes based on pelvic tilt.

Acknowledgments :

This study was supported by the Japan Hip Joint Foundation.

Disclosure of Interests:

None declared

Operative treatment of hip impingement caused by hypertrophy of the anterior inferior iliac spine

A 30-year-old man presented with pain and limitation of movement of the right hip. The symptoms had failed to respond to conservative treatment. Radiographs and CT scans revealed evidence of impingement between the femoral head-neck junction and an abnormally large anterior inferior iliac spine. Resection of the hypertrophic anterior inferior iliac spine was performed which produced full painless restoration of function of the hip.

Hypertrophy of the anterior inferior iliac spine as a cause of femoro-acetabular impingement has not previously been described.

Revision total hip replacement using the Kerboull acetabular reinforcement device with morsellised or bulk graft: results at a mean follow-up of 8.7 years

We retrospectively evaluated 42 hips which had undergone acetabular reconstruction using the Kerboull acetabular reinforcement device between September 1994 and December 1998. We used autogenous bone chips from the ilium and ceramic particle morsellised grafts, even in large acetabular bone defects, in the early stages of the study. Thereafter, femoral head allograft was used as bulk graft in patients with large acetabular defects. Ceramic blocks and the patients' contralateral femoral head were also used as bulk graft. The mean follow-up period was 8.7 years (4.3 to 12). Survivorship analysis was performed using radiological failure of the acetabular component, irrespective of whether it was revised, or not, as the end-point. The survival rate of the morsellised graft group (25 hips) and the bulk graft group (17 hips) at ten years was 53% (95% confidence interval (CI) 42.5% to 63.5%) and 82% (95% CI 72.4% to 91.6%), respectively. The mid-term results of revision total hip replacement with the Kerboull device were better when bulk graft was used in any size of bone defect.

PI3 kinase blockade by Ad-PTEN inhibits invasion and induces apoptosis in RGP and metastatic melanoma cells

BACKGROUND

Melanoma is an aggressive tumor with a propensity to rapidly metastasize. The PTEN gene encodes a phosphatase with an unusual dual specificity for proteins and lipids. Mutations of PTEN have been found in various human cancers, including glioblastoma, prostate, breast, lung, and melanoma. Here we investigate in vitro the effects of blocking PI3K signaling using adenoviral-delivered PTEN (Ad-PTEN) in cell lines derived from both early- and late-stage melanoma.

MATERIALS AND METHODS

Ad-PTEN transduced melanoma cell lines or normal cells were assayed for cell death, apoptosis, gene expression, invasion and migration, and regulation of angiogenesis.

RESULTS

The PTEN locus from RGP and metastatic melanoma cell lines was sequenced; no coding region mutations were found. Adenoviral transfer of PTEN into melanoma cells containing wild-type PTEN alleles led to tumor-specific apoptosis and growth inhibition, with coordinate inhibition of AKT phosphorylation. Ad-PTEN suppressed cell migration by metastatic melanoma cells with concomitant increase in the level of cell surface E-cadherin. Immunohistochemical and confocal analyses localized PTEN to the cytoplasm and demonstrated enrichment at the cell membrane. Ad-PTEN inhibited angiogenesis as demonstrated by the tube formation assay using human vascular endothelial cells.

CONCLUSIONS

These studies indicate that Ad-PTEN can inhibit tumor cells via multiple mechanisms and has pro-apoptotic, anti-metastatic, and anti-angiogenic properties. Thus, PI3K blockade via Ad-PTEN may be a promising approach for the treatment of early- and late-stage melanoma, even in tumors that do not harbor PTEN mutations.

Melanoma differentiation associated gene-7 (mda-7): a novel anti-tumor gene for cancer gene therapy

BACKGROUND

The mda-7 gene (melanoma differentiation associated gene-7) is a novel tumor suppressor gene. The anti-proliferative activity of MDA-7 has been previously reported. In this report, we analyze the anti-tumor efficacy of Ad-mda7 in a broad spectrum of cancer lines.

MATERIALS AND METHODS

Ad-mda7-transduced cancer or normal cell lines were assayed for cell proliferation (tritiated thymidine incorporation assay, Alamar blue assay, and trypan-blue exclusion assay), apoptosis (TUNEL, and Annexin V staining visualized by fluorescent microscopy or FACs analysis), and cell cycle regulation (Propidium Iodide staining and FACs analysis).

RESULTS

Ad-mda7 treatment of tumor cells resulted in growth inhibition and apoptosis in a temporal and dose-dependent manner. The anti-tumor effects were independent of the genomic status of p53, RB, p16, ras, bax, and caspase 3 in these cells. In addition, normal cell lines did not show inhibition of proliferation or apoptotic response to Ad-mda7. Moreover, Ad-mda7-transduced cancer cells secreted a soluble form of MDA-7 protein. Thus, Ad-mda7 may represent a novel gene-therapeutic agent for the treatment of a variety of cancers.

CONCLUSIONS

The potent and selective killing activity of Ad-mda7 in cancer cells but not in normal cells makes this vector a potential candidate for cancer gene therapy.

Biodistribution of an adenoviral vector carrying the luciferase reporter gene following intravesical or intravenous administration to a mouse

The biodistribution and resulting pattern of transgene expression were determined following intravesical administration of an adenoviral vector carrying the luciferase reporter gene (AdLuc). Female BALB/c mice were subjected to intravesical instillation of 1 x 10(9) or 5 x 10(9) plaque-forming units of AdLuc. After sacrifice, transgene expression was detected in tissues using luciferase assays; vector DNA was detected by vector-specific polymerase chain reaction. These experiments showed very little vector dissemination outside of the bladder by this route of administration. High-level expression of the vector transgene in the bladder was found to diminish by severalfold after 3 days. In a supporting study, vector dissemination and resulting transgene expression were determined following tail vein injection of 5 x 10(9) plaque-forming units of AdLuc. Vector was distributed to and expressed in every organ analyzed, with the highest concentration and level of expression observed in the liver.

Glenohumeral osteoarthritis following a "color test" during rotator cuff repair. A case report and a review of the literature

A case of glenohumeral osteoarthritis in a 35-year-old female following a color test during rotator cuff repair is described. The patients had a tear in the rotator cuff involving the supraspinatus muscle and rotator interval. A color test with a 0.4% aqueous solution of gentian violet was performed during the operation and the ruptured cuff was not tightly sutured. The patient developed glenohumeral osteoarthritis 25 months postoperatively. Plain film radiographs showed joint space narrowing and bone sclerosis of the humeral head, but there was no evidence of osteophytes. This pathology was thought to have been caused by the aqueous gentian violet solution.

Severe metallosis caused by shaving down of the stem neck due to outer cup impingement of a bipolar endoprosthesis. A case report. off

The authors report on a patient with severe metallosis caused by shaving down of the stem neck due to outer cup impingement. A primary arthroplasty was performed using an Omnifit bipolar endoprosthesis (Stryker) with an acetabular bone graft fixed by ceramic screws. At the time of revision surgery the synovium was stained black. Two ceramic screws were broken, but no scratch was observed on the metal surfaces of the outer cup and the inner head. The ultra-high molecular weight polyethylene (UHMWPE) of the inner-bearing collar was worn and flat. During the operation, a groove was observed at the stem neck where the outer cup impinges. An analysis of the black pseudocapsule by scanning electron microscopy with electron prove microanalysis (SEMEPMA) revealed that the pseudocapsule contained titanium metal particles. To our knowledge, metallosis caused by the same mechanism has only been reported in four joints, which were replaced by a Zimmer BHP bipolar endoprosthesis and Howmedica bicentric cup.

[Hepatoportal sclerosis associated with portal vein thrombosis in children: report of 3 cases]

Hepatoportal sclerosis is the term used to name a clinicopathological condition responsible for non-chirrotic portal hypertension. A three cases report of children with hepatoportal sclerosis is presented associated with portal vein thrombosis. The first two patients presented as main complaint upper digestive hemorrhage and the third one was admitted for investigation of hepatosplenomegaly. The ultrasonographic exam revealed alterations indicative of extrahepatic portal vein thrombosis in the three cases. The patients underwent liver biopsy for they had presented altered liver enzymes. The main histological findings were: subintimal sclerosis, portal fibrosis and telangiectases of the intrahepatic venous branches, consistent with the diagnosis of hepatoportal sclerosis. The three patients showed good evolution, being the hemorrhage controlled in the first two cases through esclerotherapy of esophageal varices.

The development of hypercalcemia in a patient with an ovarian tumor producing parathyroid hormone-related protein

Hypercalcemia developed in a 34-year-old woman with a clear cell carcinoma of the ovary. Osseous involvement with the tumor cells was not present. Primary hyperparathyroidism was absent. Operative partial resection of the metastatic supraclavicular lymph node, followed by radiation therapy, decreased her serum calcium concentrations. This case belongs to the category of humoral hypercalcemia of malignancy (HHM). Detection of a significant quantity of immunoreactive parathyroid hormone-related protein (PTH-rP) in the metastatic lymph node suggested that the HHM of the patient was induced by PTH-rP produced by the tumor. From a review of 17 cases of ovarian tumors showing HHM-like morbidity, it was found that clear cell carcinoma and cystadenocarcinoma were the major types of ovarian tumors associated with HHM.

The antiviral effect of phorbol ester and calcium ionophore A23187 is not mediated by interferons

Phorbol myristate acetate (PMA) and the calcium ionophore, A23187, produce a dose-dependent inhibition of vesicular stomatitis virus (VSV) replication in FL cells, with maximum inhibition when cells are pretreated with 1 ng/ml of PMA or 0.5 microM A23187. No interferon (IFN) activity was detected in culture supernatants from cells treated with these agents, and addition of anti-human IFN antibodies did not prevent the inhibition of VSV replication that they caused. However, their antiviral activities were inhibited by actinomycin D or cyclohexamide treatment. Thus, the antiviral activities of PMA and A23187 involve de novo synthesis of protein but are not mediated through the production of IFN.

Structure and organization of the hepatitis C virus genome isolated from human carriers

Hepatitis C virus (HCV) is a major causative agent of posttransfusion non-A, non-B hepatitis, which often develops into malignant chronic diseases, including liver cirrhosis and hepatocellular carcinoma. We have cloned from human carriers overlapping cDNAs (9,416 bp) covering the entire coding region of the HCV genome. The latter encodes a 3,010-amino-acid polyprotein. In addition, there are 332 and 54 bases of 5' and 3' noncoding sequences, respectively. Our HCV strain has a 77% nucleic acid identity to the HCV strain cloned by workers at Chiron Corporation. The hydrophobicity profile of the putative polyprotein is similar to those of flaviviruses, but it has limited amino acid homology to polyproteins of flaviviruses and other viruses, indicating that HCV is at most distantly related to flaviviruses.

Effect of glucose on antiviral activity of interferon

Glucose was found to impair the antiviral activity of rabbit interferon (IFN) in RK-13 cells. This impairment was dependent on the glucose concentration: A pronounced impairment was observed at the concentration of 30 mg of glucose/ml, the maximum concentration which produced neither morphological changes of cells nor diminution of overall macromolecular synthesis. Maximal impairment was seen when glucose was added to the IFN-treated RK-13 cells early during the development of antiviral activity. Furthermore, glucose decreased the extent of induction of 2',5'-oligoadenylate synthetase by IFN. Of six different monosaccharides examined, only fructose had the same anti-IFN effect as glucose.

Proposal of standardized methods and reference for assaying recombinant human tumor necrosis factor

Two assay methods for recombinant human tumor necrosis factor (rH-TNF) were developed, one a biological L-cell assay and the other an enzyme-linked immunosorbent assay. The accuracy and reproducibility of each and the correlation between the two were studied. As a result of this investigation, the two assay methods were found appropriate for standardization of rH-TNF. A freeze-dried reference was prepared, and examination of its potency and stability showed it to be suitable for use as a reference standard for rH-TNF assays.

[Comparison of experimental diabetes induced by streptozotocin and cyproheptadine]

It is generally accepted that Diabetes mellitus is caused by the endocrinological functional disturbance of the pancreas, decreasing available insulin for carbohydrate metabolisms. Diabetes mellitus is not necessarily related to hypoinsulinemia, and some senile subjects show diabetic symptoms although the insulin levels in their blood are within the normal range. Therefore, in order to examine the cause of Diabetes mellitus, the glucose tolerance test is usually given as a routine laboratory method to monitor the pancreatic endocrine functions. The pattern of decreasing glucose level in blood will tell us what is the cause of the disease. In testing the effects of anti-diabetic drugs, experimental diabetic conditions have been prepared by various methods, and recently streptozotocin (STZ) and cyproheptadine (CPH) have been successfully used to induce diabetic conditions of various degrees. In the present study, degree of disturbance of the pancreatic functions by STZ and CPH were compared, and in addition, disturbance of organs other than the pancreas was also examined biochemically. When a high dose of STZ was given, irreversible disfunction of glucose level normalizing and insulin secreting abilities was observed. Serum GOT, GPT, lysosomal enzyme activities and lysosomal enzyme activity in the liver and pancreas decreased in high dose STZ administered rats. Low dose STZ disturbed the pancreatic endocrine function less than that in high dose STZ, and the blood glucose level normalizing function was reversibly disturbed. Insulin secretion decreased, and normalized on discontinuation of low dose STZ administration. Low dose STZ also disturbed organs other than the pancreas as in high dose STZ.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacokinetic study of a human recombinant interferon (Re-IFN-alpha A) in cynomolgus monkeys by 2'-5' oligoadenylate synthetase assay

We evaluated 2'-5'Oligoadenylate (2-5 A) synthetase assay for pharmacokinetic study of human interferon (IFN) in cynomolgus monkeys. The enzyme was induced in primary cultures of cynomolgus monkey kidney (PMK) cells as well as in FL cells in response to human recombinant IFN-alpha A treatment. The enzyme activity increased with IFN dose and, in parallel with the enzyme elevation, developed the antiviral state of the cells. The enzyme activity induced in the peripheral blood lymphocytes peaked at 6 to 12 hr after iv or im administration. The peak level of the enzyme activity depended on the IFN concentration of the blood and the activity rapidly decreased as serum IFN was cleared from the blood. These results indicate that human recombinant IFN-alpha A induces 2-5 A synthetase in monkey cells both in vitro and in vivo, and that the enzyme assay can be used to quantitatively monitor the host response after IFN administration.

[Changes of lysosomal enzyme activities in experimental type I and type IV allergic models]

Experimental allergy was induced in animals: asthma, a Type I allergy, was induced in guinea pigs by sensitizing them with alpha-amylase (inhalation), and experimental allergic encephalomyelitis (EAE), a Type IV allergy, was induced in rats. Pulmonary, brain and serum lysosomal enzyme activities were measured in normal and allergic conditions. beta-Glucuronidase (beta-G) and arylsulfatase (AS) activities were determined by the fluorescent technique. During the asthmatic attack, pulmonary lysosomal enzyme activities were not different from that in the normal state in guinea pigs. However, brain lysosomal enzyme activities were elevated markedly on the 1 st day of EAE induction. Brain beta-G activity was elevated on the 2nd day, and AS activity had a tendency to be increased. On the other hand, serum lysosomal enzyme activity was not altered significantly. In the experimental allergy, lysosomal enzyme activity was altered in Type IV, but not in Type I.