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PubMed1990

Response persistence of cat retinal ganglion cells to the temporally discrete presentation of sinewave gratings.

The neural basis of visible persistence is not well understood. In the present study the initial onset responses of cat retinal ganglion cells to the abrupt onset and offset of sinewave gratings were examined to determine if ganglion cells display a degree of response persistence that might account for the phenomenon of visible persistence. The responses of X and Y ganglion cell axons were tested using single-unit extracellular recording techniques. Both cell types displayed some degree of response persistence and over a limited range of short stimulus durations response persistence was inversely related to stimulus duration. These data suggest that neural persistence at the ganglion cell level may be the initial physiological basis for some types of visible persistence.

Animals↗

PubMedDate not supplied

Pathogenesis of persistent left superior vena cava with a coronary sinus connection.

The basis for persistence of the left superior vena cava (LSVC), usually associated with cardiac malformations, is poorly understood. We examined 351 staged, serially sectioned human embryos in the Carnegie Embryological Collection and 1208 specimens with congenital cardiovascular malformations in the Pathology Collection of the Johns Hopkins Hospital. A standardized questionnaire was answered for each embryo and autopsy case and a computer program was employed to tabulate concurrent anatomic features. In the normal embryos a symmetric venous system appeared with the heart tube at Carnegie stage 9; the sinoatrial junction translocated to the right and the relationship of the coronary sinus to the LSVC was established by stage 12. The LSVC was patent through stage 20 and subsequently underwent luminal obliteration by compression between the left atrium and the hilum of the left lung. Among the 1208 hearts with a congenital abnormality, 104 (9%) had a persistent LSVC with a coronary sinus connection. Statistically, significantly more frequent associations were found between persistent LSVC and atrioventricular canal defects, cor triatriatum, and mitral atresia and a significantly less frequent association was observed between persistent LSVC and atrial septal defect or patent foramen ovale as a primary defect. The normally late embryonic obliteration of the LSVC suggests that its persistence would be secondary to reduce cardiac compression or to blood flow redistribution at an early stage, and the malformations associated with persistent LSVC support that view. Identification of a persistent left superior vena cava with coronary sinus connection should suggest an associated malformation, especially atrioventricular canal, cor triatriatum, or mitral atresia.

Adolescent↗

PubMed2004

Efficiency of different selection criteria for persistency and lactation milk yield.

A conversion formula was developed to convert the genetic covariance matrices of daily yields and of random regression coefficients between 305-d and 335-d production periods under a random regression test day model. Five selection criteria were compared in terms of genetic improvement in persistency and lactation milk: 1) lactation estimated breeding value (EBVL), 2) P6 = 279Sigma(i=65) (D280 - Di), 3) ratio of daily estimated breeding value (EBV)(r280/65 = D280/D65), 4) ratio of partial lactation EBV (P280/65 = D66 approximately 28/D5 approximately 65), and 5) differential daily EBV (d65-280 = D65 - D280), where Di refers to EBV at days in milk (DIM) i. Fundamental differences among these 5 selection criteria were interpreted conceptually with a graph. Persistency, defined as k = (delta G65 - delta G280)/215, was the average daily rate of decline in selection gain from DIM 65 to 280, which is free from the effect of lactation milk on the rate of decline. Parameter k provides an objective measure of persistency, which increases when k < 0 and decreases when k > 0. Of the 5 selection criteria compared, d65-280 and P6 achieved greater persistency at the expense of genetic gain in lactation milk, whereas selection based on EBVL achieved the highest response in lactation milk, but was coupled with greatest decline in persistency. Selection on P280/65 or r280/65 improved both lactation milk and persistency and, thus, is recommended for simultaneous improvement of these 2 economically important traits. Further study of the relative economic values of persistency and lactation milk in order to combine both traits into an index for selection decision is warranted.

Animals↗

PubMed2004

Genetic relationships between persistency and reproductive performance in first-lactation Canadian holsteins.

The main objective of this study was to estimate genetic relationships between lactation persistency and reproductive performance in first lactation. Relationships with day in milk at peak milk yield and estimated 305-d milk yield were also investigated. The data set contained 33,312 first-lactation Canadian Holsteins with first-parity reproductive, persistency, and productive information. Reproductive performance traits included age at first insemination, nonreturn rate at 56 d after first insemination as a virgin heifer and as a first-lactation cow, calving difficulty at first calving and calving interval between first and second calving. Lactation persistency was defined as the Wilmink b parameter for milk yield and was calculated by fitting lactation curves to test day records using a multiple-trait prediction procedure. An 8-trait genetic analysis was performed using the Variance Component Estimation package (VCE 5) via Gibbs sampling to estimate genetic parameters for all traits. Heritabilities of persistency, day in milk at peak milk yield and estimated 305-d milk yield were 0.18, 0.09 and 0.45, respectively. Heritabilities of reproduction were low and ranged from 0.03 to 0.19. The highest heritability was for age at first insemination. Heifer reproductive traits were lowly genetically correlated, whereas cow reproductive traits were moderately correlated. Heifers younger than average when first inseminated and/or conceived successfully at first insemination tended to have a more persistent first lactation. First lactation was more persistent if heifers had difficulty calving (r(g) = 0.43), or conceived successfully at first insemination in first lactation (r(g) = 0.32) or had a longer interval between first and second calving (r(g) = 0.17). Estimates of genetic correlations of reproductive performance with estimated 305-d milk yield were different in magnitude, but similar in sign to those with persistency (0.02 to 0.51).

Animals↗

PubMed2006

Lactase non-persistence and milk consumption in Estonia.

AIM: To define the frequency of the C/T-13910 variant associated with lactase persistence/non-persistence trait and to analyze the milk consumption of lactase non-persistent subjects in Estonia. METHODS: We genotyped 355 Estonians by polymerase chain reaction and direct sequencing. Milk consumption was analyzed by a questionnaire, specially developed to analyze milk consumption and abdominal complaints. RESULTS: The frequency of the genotype of the C/C-13910 (lactase non-persistence) was found to be 24.8% in native Estonians. No other single nucleotide polymorphisms covering the region of 400 bp adjacent to the C/T-13910 variant were found. Lactase non-persistence subjects were found to consume less milk than lactase persistence subjects. CONCLUSION: The frequency of lactase non-persistence defined by the C/C-13910 genotype confirms the results of the previous studies based on indirect methods of determining hypolactasia. Milk consumption of lactase non-persistence subjects is consistent with previously reported figures of adult-type hypolactasia in Estonia. However, lactase non-persistence does not prevent the intake of milk in many adults.

Adult↗

PubMedDate not supplied

Is abnormal focal steepening of the cornea related to persistent monocular diplopia?

PURPOSE: Some case reports have shown that abnormal focal steepening of the cornea appears to cause monocular diplopia by prismatic effect. The purpose of this study was to ascertain prospectively if the pattern of corneal distortion was related specifically to persistent monocular diplopia. METHODS: We selected 16 visually normal eyes (controls) and two groups of volunteers in which abnormal focal steepening of the cornea was expected to be found: 40 eyes of 20 volunteers who wore rigid gas-permeable contact lenses (RGP) for myopia and 10 eyes of seven patients with keratoconus. New charts that consisted of white dials on a black background were prepared for detection and measurement of secondary images. Any secondary image that could not be eliminated by any trial lens correction was defined as a persistent secondary image, using the charts. Corneal topography from all subjects was classified: round or oval, symmetric or asymmetric bowtie, abnormal focal steepening accompanied by contact lens-induced corneal warpage or keratoconus, or amorphous. We analyzed the relationship between the persistent secondary image and the corneal topographical patterns. RESULTS: A persistent secondary image was detected from seven eyes of RGP wearers and all keratoconus eyes. All corneal topographies of the seven RGP eyes with a persistent secondary image showed abnormal focal steepening related to contact lens-induced corneal warpage. The direction of the persistent secondary image was approximately consistent with the location of the focal steepening as seen on the corneal topography. CONCLUSION: Abnormal focal steepening of the cornea that appeared to produce a prismatic difference between two parts of the cornea was specifically related to persistent monocular diplopia.

Adolescent↗

PubMed2005

Late priming and variability of epitope-specific CD8+ T cell responses during a persistent virus infection.

Control of persistently infecting viruses requires that antiviral CD8(+) T cells sustain their numbers and effector function. In this study, we monitored epitope-specific CD8(+) T cells during acute and persistent phases of infection by polyoma virus, a mouse pathogen that is capable of potent oncogenicity. We identified several novel polyoma-specific CD8(+) T cell epitopes in C57BL/6 mice, a mouse strain highly resistant to polyoma virus-induced tumors. Each of these epitopes is derived from the viral T proteins, nonstructural proteins produced by both productively and nonproductively (and potentially transformed) infected cells. In contrast to CD8(+) T cell responses described in other microbial infection mouse models, we found substantial variability between epitope-specific CD8(+) T cell responses in their kinetics of expansion and contraction during acute infection, maintenance during persistent infection, as well as their expression of cytokine receptors and cytokine profiles. This epitope-dependent variability also extended to differences in maturation of functional avidity from acute to persistent infection, despite a narrowing in TCR repertoire across all three specificities. Using a novel minimal myeloablation-bone marrow chimera approach, we visualized priming of epitope-specific CD8(+) T cells during persistent virus infection. Interestingly, epitope-specific CD8(+) T cells differed in CD62L-selectin expression profiles when primed in acute or persistent phases of infection, indicating that the context of priming affects CD8(+) T cell heterogeneity. In summary, persistent polyoma virus infection both quantitatively and qualitatively shapes the antiviral CD8(+) T cell response.

Animals↗

PubMed2006

Costimulation requirements for antiviral CD8+ T cells differ for acute and persistent phases of polyoma virus infection.

The requirement for costimulation in antiviral CD8+ T cell responses has been actively investigated for acutely resolved viral infections, but it is less defined for CD8+ T cell responses to persistent virus infection. Using mouse polyoma virus (PyV) as a model of low-level persistent virus infection, we asked whether blockade of the CD40 ligand (CD40L) and CD28 costimulatory pathways impacts the magnitude and function of the PyV-specific CD8+ T response, as well as the humoral response and viral control during acute and persistent phases of infection. Costimulation blockade or gene knockout of either CD28 or CD40L substantially dampened the magnitude of the acute CD8+ T cell response; simultaneous CD28 and CD40L blockade severely depressed the acute T cell response, altered the cell surface phenotype of PyV-specific CD8+ T cells, decreased PyV VP1-specific serum IgG titers, and resulted in an increase in viral DNA levels in multiple organs. CD28 and CD40L costimulation blockade during acute infection also diminished the memory PyV-specific CD8+ T cell response and serum IgG titer, but control of viral persistence varied between mouse strains and among organs. Interestingly, we found that CD28 and CD40L costimulation is dispensable for generating and/or maintaining PyV-specific CD8+ T cells during persistent infection; however, blockade of CD27 and CD28 costimulation in persistently infected mice caused a reduction in PyV-specific CD8+ T cells. Taken together, these data indicate that CD8+ T cells primed within the distinct microenvironments of acute vs persistent virus infection differ in their costimulation requirements.

Acute Disease↗

PubMed2003

Persistent and nonpersistent Listeria monocytogenes contamination in meat and poultry processing plants.

Contamination analysis of persistent and nonpersistent Listeria monocytogenes strains in three meat processing plants and one poultry processing plant were performed in order to identify factors predisposing to or sustaining persistent plant contamination. A total of 596 L. monocytogenes isolates were divided into 47 pulsed-field gel electrophoresis (PFGE) types by combining the restriction enzyme patterns of AscI (42 patterns) and ApaI (38 patterns). Persistent and nonpersistent strains were found in all plants. Nonpersistent PFGE types were found mostly at one sampling site, with the processing environment being the most common location, whereas the persistent strains were found at several sampling sites in most cases. The processing machines were frequently contaminated with persistent L. monocytogenes PFGE types, and it was of concern that surfaces having direct contact with the products were contaminated. The role of the processing machines in sustaining contamination and in contaminating the products appeared to be important because the final product of several processing lines was contaminated with the same L. monocytogenes PFGE type as that found in the processing machine. The proportion of persistent PFGE types in heat-treated products was eight times higher than in the raw products, showing the importance of the persistent PFGE types as contaminants of the final heat-treated products. The contamination status of the processing lines and machines appeared to be influenced by the compartmentalization of the processing line, with poor compartmentalization increasing L. monocytogenes contamination. The separation of raw and post-heat treatment areas seemed especially important in the contamination status of post-heat treatment lines.

Animals↗

PubMed2002

Persistent median artery in the carpal tunnel: color Doppler ultrasonographic findings.

OBJECTIVE: To describe the ultrasonographic and color Doppler ultrasonographic findings in 2 patients with carpal tunnel syndrome associated with a persistent median artery and to report the frequency of this anatomic variation in healthy volunteers. METHODS: Two patients with the clinical appearance of carpal tunnel syndrome and 100 wrists and distal forearms of 50 asymptomatic volunteers were examined with ultrasonography and color Doppler ultrasonography. The frequency and size of a persistent median artery and its relationship to median nerve anatomy in the carpal tunnel were evaluated. RESULTS: A large persistent median artery of 3 mm in diameter was found in the affected hands in both patients with carpal tunnel syndrome. Findings were confirmed at surgery. Among the asymptomatic volunteers, a persistent median artery could be found in 13 (26%, 10 [20%] unilateral and 3 [6%] bilateral), with a mean diameter of 1.1 mm (range, 0.5-1.7 mm). In 10 (63%) of 16 hands, the persistent median artery was associated with high division of the median nerve or a bifid nerve configuration in the carpal tunnel. CONCLUSIONS: A persistent median artery is a common condition in healthy individuals and in most cases is related to median nerve variations such as high division or a bifid nerve. Because a persistent median artery has a superficial course close to the transverse carpal ligament, preoperative diagnosis of this anatomic variation may be of clinical importance.

Adult↗

PubMed1979

Chronic persistent hepatitis and unconjugated hyperbilirubinemia.

The authors studied 12 patients with chronic persistent hepatitis and persistent or intermittent mild unconjugated hyperbilirubinemia. Maximum serum total bilirubin concentration ranged from 2.1 to 3.6 mg/dl. Hemolysis was not evident. Hepatic bilirubin UDP-glucuronyltransferase activity assayed in each patient ranged from 0.16 to 0.39 U (mean +/- SEM = 0.27 +/- 0.02) compared to 0.68-1.99 (1.35 +/- 0.08) in 23 normals, 0.78-2.28 (1.41 +/- 0.05) in 53 patients with acute hepatitis, 0.34-1.74 (0.81 +/- 0.09) in 16 patients with anicteric chronic persistent hepatitis, and 0-0.62 (0.24 +/- 0.03) in 33 patients with Gilbert's syndrome. The mean UDP-glucuronyltransferase activity was significantly lower in anicteric chronic persistent hepatitis compared to normals, but higher than in Gilbert's syndrome. The incidence of unconjugated hyperbilirubinemia among first degree relatives was 0:32 in icteric chronic persistent hepatitis compared to 24:85 (28%) in Gilbert's syndrome. These results show that the likely cause for the unconjugated hyperbilirubinemia associated with chronic persistent hepatitis is an acquired depression of hepatic bilirubin UDP-glucuronyltransferase activity. The data suggest that the enzyme defect is related to chronic persistent hepatitis.

Adult↗

PubMed2000

Persistent activity and the single-cell frequency-current curve in a cortical network model.

Neurophysiological experiments indicate that working memory of an object is maintained by the persistent activity of cells in the prefrontal cortex and infero-temporal cortex of the monkey. This paper considers a cortical network model in which this persistent activity appears due to recurrent synaptic interactions. The conditions under which the magnitude of spontaneous and persistent activity are close to one another (as is found empirically) are investigated using a simplified mean-field description in which firing rates in these states are given by the intersections of a straight line with the f-I curve of a single pyramidal cell. The present analysis relates a network phenomenon - persistent activity in a 'working memory' state - to single-cell data which are accessible to experiment. It predicts that, in networks of the cerebral cortex in which persistent activity phenomena are observed, average synaptic inputs in both spontaneous and persistent activity should bring the cells close to firing threshold. Cells should be slightly sub-threshold in spontaneous activity, and slightly supra-threshold in persistent activity. The results are shown to be robust to the inclusion of inhomogeneities that produce wide distributions of firing rates, in both spontaneous and working memory states.

Action Potentials↗

PubMed2001

Persistent hyperparathyroidism after kidney transplantation requiring parathyroidectomy.

INTRODUCTION: Successful kidney transplantation (KT) is believed to cure secondary hyperparathyroidism, but persistent disease has emerged in a significant number of allograft recipients. Parathyroidectomy (PTX) is ultimately required in some of these patients. AIM: To provide an in-depth analysis of 42 patients who required surgical treatment for persistent hyperparathyroidism after successful renal transplantation and to identify risk factors for PTX present at the time of transplantation. DESIGN: Retrospective case controlled study. METHODS: Charts of 1332 kidney allograft recipients, transplanted between 1989 and 2000, were reviewed. Patients requiring a PTX after a first successful kidney transplantation (serum creatinine < 2.5 mg/dl) were identified. Their charts were checked for various demographic, clinical and biochemical variables. The data were compared with data obtained from a control group closely matched for time of transplantation. RESULTS: Persistent hyperparathyroidism after successful KT requiring PTX occurred in 55 (4.1%) patients. Because of insufficient follow-up data only 42 recipients were eligible for further analysis. The age of the patients was 52 +/- 2.1 years (mean +/- SEM). The time between transplantation and PTX was 416 +/- 61 days. The mean serum creatinine at the time of PTX amounted to 1.6 +/- 0.1 mg/dl. Persistent hypercalcemia, albeit asymptomatic in most patients, was the main indication for PTX. Enlarged parathyroid glands were visualised by ultrasonography in 74% of the cases. Subtotal parathyroidectomy was the procedure of choice. The operative morbidity was negligible and the incidence of persistent or recurrent hyperparathyroidism was low, being 15%. In comparison to the control group, the patients with persistent hyperparathyroidism had a significant longer duration of pre-transplantation dialysis treatment (36.3 vs. 23.0 months, p < 0.01) and significant higher values of intact parathyroid hormone (iPTH) (268.1 vs. 96.0 ng/l, p < 0.001), total serum calcium (10.6 vs. 9.4 mg/dl, p < 0.001), and serum alkaline phosphatases (185.5 vs. 132.0 U/L, p < 0.001) at the time of transplantation. No relationship with the mode of dialysis treatment was observed. CONCLUSION: Persistent hyperparathyroidism requiring PTX after successful KT is a common clinical problem. Patients who spent a long time on dialysis and/or patients with a high pre-transplant level of iPTH, serum calcium and alkaline phosphatases are especially at risk.

Alkaline Phosphatase↗

PubMed1975

Changes of the cell type of BHK-21 lines by persistent Sindbis virus.

Persistent infection by Sindbis virus (SV) can be induced in cultures of BHK-21 cells. In a persistently infected cell line only 5% of the cells produced virus. Virus titers in the medium reached 10(5) PFU per ml. A persistent infection could be eliminated from cultures by seeding at most 100 cells per bottle. Compared with the original line decontaminated lines differed in several properties. After infection with SV ten times less virus was released into the medium, and an infection persisted without producing periodic cell destructions as observed in establishing a persistent infection in the original line. In decontaminated lines plaques formed by different viruses were either not visible or smaller than those in normal cells. Persistently infected as well as decontaminated lines had lost three chromosomes. The altered cell type of persistently infected lines apparently originated by selection of a cell mutant which was not destroyed by SV. Results suggested that a small number of cells susceptible to the virus continuously arises from the population of altered cells, and that virus infection is transmitted and maintained in the cultures by these sensitive cells.

Animals↗

PubMed2002

Human papillomavirus persistence and nutrients involved in the methylation pathway among a cohort of young women.

Persistent oncogenic human papillomavirus (HPV) infection is associated with cervical dysplasia. Cofactors, such as nutrient status, may be required for the progression of HPV infection to neoplasia. HPV DNA methylation patterns in vitro have been shown to be associated with viral transcriptional activity. Folate, vitamin B12, vitamin B6, and methionine may function to prevent cervical cancer through their role in DNA methylation. This study was conducted to examine the relationship of dietary intake of folate, vitamin B12, vitamin B6, and methionine, as well as circulating levels of folate and vitamin B12 to HPV persistence. Oncogenic HPV status was determined at baseline and at approximately 3 and 9 months postbaseline. Multivariate logistic regression analysis was used to determine the adjusted odds ratios for persistent HPV infection associated with each tertile of individual nutrient among 201 women with a persistent or intermittent HPV infection. Circulating vitamin B12 levels were inversely associated with HPV persistence (P for trend, 0.037) after adjusting for age, age at first intercourse, marital status, cigarette smoking status, race, and body mass index. In addition, women with circulating levels in the highest tertile (>493.2 pg/ml) of vitamin B12 were less likely to have a persistent infection (adjusted odds ratio = 0.4; 95% confidence interval = 0.17-0.96). No significant associations were observed between HPV persistence and dietary intake of folate, vitamin B12, vitamin B6, or methionine from food alone or from food and supplements combined or from circulating folate. These data suggest a role for circulating vitamin B12 in early cervical carcinogenesis.

Adolescent↗

PubMed1992

Mortality associated with acute watery diarrhea, dysentery and persistent diarrhea in rural North India.

Mortality associated with diarrhea was investigated in a longitudinally followed cohort of children under 6 years of age in rural North India. During the followup, 1663 episodes of diarrhea and 23 diarrhea-related deaths were recorded in 1467 children followed up for 20 months. The case fatality rate was 0.56% for acute watery diarrhea, 4.27% for dysentery, and 11.94% for non-dysenteric persistent diarrhea. Most of the episodes lasted less than a week; 5.2% became persistent (duration 14 days). The case fatality rate was similar in episodes of 1 and 2 weeks duration (0.64% and 0.8%) and increased to 13.95% for persistent episodes. Of the total 86 persistent episodes, 22.1% were dysenteric; the case fatality rate for such dysenteric persistent episodes was 21.1% and for watery persistent diarrhea 11.4%. Diarrheal attack rates were similar among different nutritional groups, but diarrheal case fatality rates progressively increased with increasing severity of malnutrition; these were 24 times higher in children with severe malnutrition (7.48%) compared to those normally nourished (0.31%). With availability and use of oral rehydration therapy, dysentery and persistent diarrhea emerge as major causes of diarrhea-related mortality, with underlying malnutrition as a key associated factor.

Asia↗

PubMed2002

The two paradigms of persistence.

Persistence refers to the extent to which an individual pursues reinforcement that is no longer available. The most common generalization regarding persistence is the partial reinforcement extinction effect, which states that partial, rather than continuous, reinforcement creates the greatest level of persistence. Although the partial reinforcement effect is the most common effect in humans, exceptions exist, namely the generalized and the reversed partial reinforcement effect. Since the 1930s, psychologists have used 2 general paradigms for studying persistence in humans: the experimental paradigm and the cognitive/individual differences paradigm. For the experimental paradigm, the primary independent variable is the schedule of reinforcement used to establish the behavior prior to the removal of reinforcement. Explanations of persistence from the experimental perspective depend on associative principles derived from various theories of learning. By contrast, the cognitive/individual differences paradigm treats persistence as a function of trait variables, including locus of control and self-esteem, or general cognitive processes, such as cognitive dissonance or social cognition. In this article, the author reviews the status of the current literature on persistence and recommends directions for future research.

Cognition↗

PubMed2002

Characterization and E protein expression of mutant strains during persistent infection of KN73 cells with Japanese encephalitis virus.

OBJECTIVE: To study the character of mutants originating from Japanese encephalitis viruses and the relationship between the characterization of mutant strains and E protein expression. METHODS: Persistent infection was established with standard strains of Japanese encephalitis viruse, known as parental viruse, in a human hepatoma cell line, KN73. Cells were subcultured weekly using trypsinization techniques. Cell-associated viruses of persistently infected cells were collected by a freeze and thaw method. Virus titers were examined by plaque method using baby hamster kidney (BHK) cells. Indirect immunofluorescence assays were used to examine E and NS3 protein antigens. Western blot analysis was used to test expression of E and NS3 proteins. RESULTS: In the early phase (24 - 36 h) post-infection, virus titer in culture fluid from KN73 cells infected with parental viruses were 10(6) PFU/ml. They were 10(3 - 4) PFU/ml in the late phase (3 years) post-infection. The titer of cell-associated viruse was 10(2 - 3) PFU/ml. A virus super-infection assay found that virus titers in culture fluid from persistently infected KN73 cells acutely super- infected with parental viruses were much lower than that of culture fluids in acutely infected normal KN73 at the same phase. Indirect immunoflurescence assay revealed that the quantity of viral antigens in persistently infected KN73 cells was lower than that in acutely infected KN73 cells with parental viruses. Western blot analyses indicated that the molecular weights of E and NS3 proteins were 53 kD and 73 kD, respectively. Expression of NS3 protein in persistently infected KN73 cells was stable but expression of E protein was markedly suppressed. CONCLUSIONS: The virulence and reproduction of viruses obtained from persistently infected KN73 cells, which have some features of DI viruses and were involved in persistent infection, was lower than that of parental viruses. These mutants may have be related to the decrease in E protein expression.

Carcinoma, Hepatocellular↗