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PubMed1988

A model virus-cell system to study the persistence of African swine fever virus.

The persistence of African swine fever virus (ASFV) on Vero cells was induced by using 5-iodo-2'-deoxyuridine (IDU). After the persistence was established, several cycles of decreasing virus production were observed with intervals in which no virus could be detected. These latency-like periods could last from 15 to 25 days. After three and a half months the cells appeared to be "cured" and no virus was detected during almost three years. These "cured" cells (Vero-L) were more resistant to superinfection with the wild type virus, and when infected they always established persistence without drug addition characterized by a continuous virus production. The persistent virus isolated at passage 23rd from ASFV persistently infected Vero-L cells was different from wild type in a) the morphology of the plaque, b) its ability to replicate in Vero-L cells, and c) greater resistance to be inhibited by IDU in normal Vero cells (Vero-N). These results suggest that both, Vero cells and ASFV have changed during persistent infection.

African Swine Fever Virus↗
PubMed1976

Persistent infection of tissue culture cells by RNA viruses.

In this paper, the characteristics of cultured cells persistently infected with RNA viruses, other than leuko viruses are described. The roles that the host cell, interferon, virus mutants and defective interfering particles may play in the establishment and maintenance of persistent infection are discussed. It is proposed that the interaction of viruses with certain types of host cells can lead to persistent infection. The differences in virus-host interactions may be attributable to differences in membrane properties of various cells. Defective interfering particles may play a role in the establishment of persistent infections in cells which normally undergo lytic virus development. Mutant types of virus appear to be prominent in the virus released from persistently infected cells, but the role that various mutants play in the maintenance of persistent infections remains unclear.

Antibodies, Viral↗
PubMed1996

Do concomitant diseases and therapies affect the persistence of ulcer symptoms in the elderly?

Risk factors of slow healing were previously researched in a large sample of duodenal (DU) and gastric ulcer (GU) patients over 65 years of age; persistence of ulcer symptoms was proven the most reliable factor in predicting nonhealing ulcer, while ulcer size was of importance only for DU. We aimed to complete the analysis, with a more careful evaluation of concomitant diseases and therapies. Ranitidine 300 mg daily was given for four to eight weeks to 310 GU and 699 DU patients. Ninety-three patients dropped out of the study; 79/294 gastric ulcers and 138/635 duodenal ulcers were unhealed after four weeks. Cardiovascular, gastrointestinal, and pulmonary disorders were the most frequent concomitant diseases; NSAIDs, cardiovascular drugs, and antihypertensives were the most frequent concomitant therapies. Esophagitis was diagnosed in 15.5% of patients. Ulcer healing was the major determinant of persistence of ulcer symptoms; esophagitis emerged as an important adjunctive and independent factor. Use of hypoglycemic agents in the whole sample and smoking habit (in GU) may have also a role. With persistence of ulcer symptoms removed from the analysis, ulcer size was the most constant factor affecting ulcer healing. NSAID use, cardiovascular disorders, esophagitis (in GU), and concomitant therapy with cardiovascular drugs (in DU) also play a role. In conclusion, persistence of ulcer symptoms, the major indicator of slow ulcer healing in the elderly, is independently affected also by the presence of esophagitis. Use of hypoglycemic agents and smoking habit may also have a role in persistence of ulcer symptoms. NSAIDs, cardiovascular disorders, cardiovascular drugs, and esophagitis affect ulcer healing, for which the most constant indicators remained persistence of ulcer symptoms and ulcer size.

Aged↗
PubMed1999

Persistent perineal sinus after proctocolectomy for Crohn's disease.

PURPOSE: Persistent perineal sinus is a source of morbidity after proctocolectomy for Crohn's disease. This study examined the factors responsible for persistent sinus after proctocolectomy for Crohn's disease. We also assessed the outcome of surgical treatment for persistent perineal sinus. METHODS: The records of 145 patients who underwent proctocolectomy for Crohn's disease between 1970 and 1997 were reviewed. RESULTS: Persistent sinus occurred in 33 (23 percent) patients after proctocolectomy. Factors associated with a significantly greater risk of perineal sinus were younger age (P = 0.006), rectal involvement (P = 0.02), perianal sepsis (P = 0.0005), high fistulas (P = 0.04), extrasphincteric excision (P = 0.0004), and fecal contamination at operation (P = 0.0003). Multivariate analyses showed that age (P = 0.0001), rectal involvement (P = 0.007), and fecal contamination (P = 0.009) were significant independent predictive factors for perineal sinus. Fifty-six operations, including 24 radical excisions, two rectus abdominis flaps, four gracilis transpositions, and two omentoplasties were performed in 24 patients with persistent sinus, but only 9 achieved healing. Long sinuses (>10 cm) and sinuses presenting late (>12 weeks after proctocolectomy) were seldom cured by surgical treatment. CONCLUSION: Persistent perineal sinus is more likely to occur if an extrasphincteric dissection is needed because of extensive anorectal disease or if fecal contamination occurs at operation. Attempted surgical eradication of perineal sinus is often ineffective.

Adrenal Cortex Hormones↗
PubMed1976

Persistent infection with bovine herpesvirus-1 (infectious bovine rhinotracheitis virus) in cultured hamster cells.

Bovine herpesvirus-1 infection in hamster embryo cells was found to be dependent upon input multiplicity; productive infection was achieved at input multiplicities greater than one, while persistent infection was established when input multiplicities were about 0.5. This persistence was characterized by a noncyclic, minimal degree of cytopathic effect with a low level of released virus. Maintenance of the persistently infected cultures did not require external supportive measures. Subcultivation of the persistently infected cultures led to virus replication followed by CPE and then cell regrowth. With 3 to 4 weeks after subcultivation a persistent infection was re-established. The possible mechanism for the bovine herpesvirus persistence in hamster cells is discussed.

Animals↗
PubMed1999

Calcium metabolism in adolescents and young adults with type 1 diabetes mellitus without and with persistent microalbuminuria.

Alterations in calcium metabolism can be demonstrated in the course of insulin-dependent diabetes mellitus. In order to clarify if the presence of persistent microalbuminuria (MA) can affect the main parameters of calcium metabolism, we studied 22 diabetic adolescents and young adults with persistent MA and compared them with 24 patients without MA and 24 healthy controls. Mean values of serum calcium, phosphorus and magnesium were similar in diabetic children and young adults without persistent MA and in controls. In addition, the mean values of PTH and 25-OHD, 1,25 (OH)2D3 and OC did not differ between these diabetics and controls. Diabetics with persistent MA showed no significant difference from the values of either controls or the group of diabetics without persistent MA for the mean values of serum calcium, phosphorus and magnesium and PTH. In contrast, diabetics with persistent MA had significantly (p<0.01) lower 25-OHD (26.5+/-5.2 ng/ml) and 1,25 (OH)2D3 (24.7+/-5.6 pg/ml) as well as OC levels (9.8+/-2.5 ng/ml; p<0.001) than controls (38.1+/-4.9 ng/ml, 40.7+/-6.4 pg/ml and 16.5+/-5.8 ng/ml, respectively) and subjects with normoalbuminuria (36.0+/-4.5 ng/ml, 38.8+/-8.9 pg/ml and 14.5+/-3.2 ng/ml). In conclusion, our study suggests that abnormalities in 25-OHD, 1,25(OH)2D3 and OC can be present in diabetic adolescents and young adults with incipient nephropathy.

Adolescent↗
PubMed2000

Ecstasy (MDMA): a review of its possible persistent psychological effects.

RATIONALE: Recreational use of "ecstasy" (3,4-methylenedioxymethamphetamine; MDMA) has become increasingly widespread. Until recently, however, little was known about the possible persistent psychological effects of extensive use of this drug. OBJECTIVE: The aim of the present review is to evaluate recent empirical evidence concerning the persistent psychological sequelae of recreational ecstasy use. METHODS: The methodologies of open trial studies of recreational ecstasy users are evaluated and reports of the presence or absence of persistent psychological problems are related to the extent of past exposure to ecstasy. RESULTS: There is growing evidence that chronic, heavy, recreational use of ecstasy is associated with sleep disorders, depressed mood, persistent elevation of anxiety, impulsiveness and hostility, and selective impairment of episodic memory, working memory and attention. There is tentative evidence that these cognitive deficits persist for at least 6 months after abstinence, whereas anxiety and hostility remit after a year of abstinence. The possibility that some of these psychological problems are caused by ecstasy-induced neurotoxicity is supported by preclinical evidence of MDMA-induced neurotoxicity and behavioural deficits, evidence of depleted serotonin in heavy ecstasy users, and by dose-response relationships between the extent of exposure to ecstasy and the severity of cognitive impairments. CONCLUSIONS: An increasing number of young, heavy ecstasy users are at significant risk of persistent cognitive impairments and disturbances of affect and personality. Some of these problems may remit after abstinence, but residual neurotoxicity and decline of serotonergic function with age may result in recurrent psychopathology and premature cognitive decline.

Affect↗
PubMed2000

Relaparotomy in peritonitis: prognosis and treatment of patients with persisting intraabdominal infection.

Some patients are prone to persisting intraabdominal infection regardless of initial eradication of the source of infection. Our aim was to characterize patients who had to undergo relaparotomy for persisting abdominal sepsis using simple clinical parameters and to define those patients who are susceptible to benefit of aggressive surgical treatment by early and repeated reoperations to control multiple organ dysfunction syndrome (MODS) caused by ongoing intraabdominal infection. Persisting abdominal sepsis was the cause of death in all of our patients who had to undergo relaparotomy. Controlling persisting abdominal sepsis should achieve a reduction in the tremendously high mortality rate. Performing a case-control study, we retrospectively reviewed 523 consecutive patients with secondary peritonitis treated from 1986 to 1996 and focused our attention on 105 patients, in whom standard surgical treatment of secondary peritonitis failed and who had to undergo relaparotomy for persisting abdominal sepsis (study group). Overall, there was no significant difference in the postoperative mortality rate between "planned relaparotomy" and "relaparotomy on demand" (54.5% versus 50. 6%). Equally clear risk estimations were given preoperatively by both the Acute Physiology and Chronic Health Evaluation (APACHE) II and the Goris scores. There was a significant difference between patients of the control group and patients of the study group with regard to preoperative APACHE II score, Goris score, age >70 years, albumin <30 g/L, extent of peritonitis, and outcome (p = 0.0001). Reexploration performed more than 48 hr after the initial operation resulted in a significantly higher mortality rate (76.5% versus 28%; p = 0.0001). However, the time of reoperation had no significant impact on survival in patients with an APACHE II score of > or = 26, because physiologic derangement is such that only a few patients could benefit from reoperation. The lowest mortality rate (9%) was achieved in patients who underwent reoperation on demand within 48 hr. We conclude that patients >70 years of age with secondary peritonitis extending over the entire abdomen and a greater degree of physiologic compromise (serum albumin levels <30 g/L, preoperative APACHE II scores >20, and existing organ failure measured by the Goris score) are at high risk for developing persistent intraabdominal infection. Our data show that timely relaparotomy provides the only surgical option that significantly improves outcome. However, aggressive surgical treatment has reached its limit in patients whose source of infection could not be controlled at the initial operation. To improve overall survival the decision to perform a relaparotomy on demand after an initially successful eradication of the source of infection must be made within 48 hr, at least before MODS emerges.

Abdomen↗
PubMed1998

Poor induction of interferon-induced 2',5'-oligoadenylate synthetase (2-5 AS) in cells persistently infected with mumps virus is caused by decrease of STAT-1 alpha.

Poor induction of interferon-induced 2',5'-oligoadenylate synthetase (2-5AS) has been demonstrated in cells persistently infected with mumps virus as compared with uninfected cells. As for the number of interferon (IFN) receptors and the level of IFN regulatory factors (IRF-1 and IRF-2) mRNAs, there was little difference between them. Therefore, it is suggested that the IFN-alpha signaling system is ineffective in the persistently infected cells. Components of IFN-stimulating gene factor 3 alpha (ISGF-3 alpha), STAT-1 alpha (p91) and STAT-2 (p113), were investigated in human amnion (FL), human nasopharyngeal cancer (KB), human T-lymphoid (HUT 78), and human B-lymphoid (Akata) cells persistently infected with mumps virus. STAT-1 alpha, but not STAT-2, disappeared in these persistently infected cells, and this factor was not restored by treatment of these cells with IFN. However, no difference was observed between the levels of STAT-1 alpha mRNA transcript in persistently infected and uninfected control cells. It is reasonable to infer that the poor induction of 2-5AS activity is due to the decrease of STAT-1 alpha in correlation with the IFN-signal transduction pathway. Furthermore, induction of other IFN-stimulated genes (ds-RNA activated protein kinase, PKR, and MxA protein) was also reduced in the cells persistently infected with mumps virus.

2',5'-Oligoadenylate Synthetase↗
PubMed1988

Visible persistence in paranoid schizophrenics.

A visual temporal integration (i.e., visible persistence) task was performed by normal controls and paranoid schizophrenics. The task evaluated the critical duration (CD), which approximates the duration of peripheral persistence duration and post-CD persistence, which is possibly more associated with central processes. Subjects were required to report when temporally modulated spatial frequency patterns, which are known to have characteristic temporal processing rates, were pulsing "on-off" with a distinct "off" period. The dependent measure was the duration of visible persistence. An analysis of groups X spatial frequency duration (50, 75, 150, 300 msec) X spatial frequency (high, medium, low), with repeated measures on the last two variables, revealed that the second-order interaction was significant (p less than 0.05). Schizophrenics had shorter visible persistence only for the 300-msec presentation for the high spatial frequency pattern. Also, the CD of schizophrenics did not conform to the duration of normals on the high spatial frequency. The results are discussed in terms of the role high spatial frequencies plays in visual information processing and how shorter visible persistence by paranoid schizophrenics may reflect a premature termination of information necessary for synthesis into accurate percepts.

Adolescent↗
PubMed1984

Visible persistence as a function of spatial frequency, number of cycles and retinal area.

Using a variety of measures it has been shown that processing time increases with increasing spatial frequency. Long and Sakitt (1981) [Vision Res. 21, 1387-1393] investigated duration of visible persistence as a function of both spatial frequency and number of cycles present. They concluded that number of cycles and not spatial frequency is the crucial variable in determining duration of visible persistence. The present paper investigates this issue in three experiments. Experiments 1 and 2 determined duration of visible persistence with spatial frequencies of 2, 4, 8 and 10 c/deg while holding both number of cycles and grating area constant in a dark surround and in a light surround. Stimulus durations of 50 and 300 msec were used in Experiments 1 and 2 respectively. The results at each stimulus duration showed an increase in duration of visible persistence with increasing spatial frequency similar to that found in most previous reports. This increase was less with a 300 than with a 50 msec stimulus duration. Whether the gratings were presented in a light or a dark surround had no significant effect. Experiment 3 showed that at 2 c/deg duration of visible persistence increased with increasing size of the grating stimuli when all stimulus sizes fell within the area of spatial summation. This effect was greater in a dark than in light surround. It is concluded that visible persistence does increase with spatial frequency. Previous results inconsistent with this conclusion are explained in terms of spatial summation.

Afterimage↗
PubMed1985

Visual persistence from brief letters and pictures.

The visual persistence from briefly presented letters and pictures was assessed by the popular probe-matching procedure over a range of background and target luminance levels and for several color conditions. It was determined that the fading visible persistence measured in this way increased with increasing target luminance and with decreasing background luminance. For small foveal presentations, photopically-matched targets of differing wavelength produced equivalent persistences; but for larger, parafoveal presentations, scotopically-matched targets of differing wavelength produced equivalent persistences. This was true for both letter and picture targets. Results were discussed in terms of an early sensory locus to such persistence effects. The strong consistency of these findings to some previous work and the apparent inconsistency with other work were treated in terms of different kinds of visual persistence effects assessed by different experimental methods.

Afterimage↗
PubMed1993

On the confounding effects of phosphor persistence in oscilloscopic displays.

Phosphor persistence has been a source of confounding in studies of temporal integration in vision. We examined the confounding by assessing the effects of the persistence of two commonly-used phosphors (P15 and P31) on performance of a temporal-integration task. In one experiment we eliminated the visibility of phosphor persistence by closing two mechanical shutters upon display termination. In a second experiment we estimated the duration of phosphor persistence by displaying the image behind closed shutters which opened upon display termination. No detectable persistence was every produced by P15 phosphor. By contrast, P31 phosphor produced persistence that lasted several hundred milliseconds even when a veiling light was projected on the screen. We ascribe the earlier instances of confounding to inadequate interpretation of the technical data on phosphor decay.

Humans↗
PubMed1994

Effect of the ISI on the visible persistence of a stimulus in apparent motion.

The persistence of briefly flashed stimuli undergoing a horizontal apparent motion is assessed as a function of the temporal interval (inter-stimulus interval or ISI) between successive locations. The main result is that the duration of persistence is increased when the ISI is reduced (within the range 1-15 msec). An increase of persistence also occurs when the spatial separation (delta chi) between successive presentations of the moving stimulus becomes larger, a well established result which is replicated here. In both cases, the elevation of persistence suggests that inhibitory processes, which are assumed to underlie the persistence-suppression, have become less efficient. According to the data, it seems that the spatio-temporal parameters of motion, and not the speed as such, are responsible for the strength of inhibition. Namely, optimal inhibition, and thus suppression, would need a minimum amount of time to take place, and would improve with proximity (i.e. with smaller delta chi). Finally, a persistence-suppression decrease is observed when the angular size of the flashed stimuli is reduced (i.e. when higher spatial frequencies become more predominant). A model of transient-on-sustained inhibition accounts well for these results.

Afterimage↗
PubMed1996

Efficient induction of persistent and prenatal parvovirus infection in rats.

Parvoviruses are prevalent and disruptive infectious agents of laboratory rats. Risks to rat-based research from infection are increased by the persistence of virus in immune rats and by prenatal transmission of infection. The mechanisms leading to viral persistence and prenatal infection are poorly understood and have been difficult to study for lack of reliable and humane induction methods. We report here protocols for inducing persistent and prenatal infection without causing clinical disease using the UMass strain of rat virus (RV), a common rat parvovirus. Infant rats inoculated by the oronasal route at 6 days of age had greater than 90% prevalence of persistent infection. RV-UMass also induced intrauterine infection in pregnant rats inoculated by the oronasal route. Inoculation of dams at gestation day 9 frequently caused severe disease in the fetuses whereas inoculation at gestation day 12 caused primarily asymptomatic fetal infection that persisted post partum RV-UMass infection facilitates study of parvoviralhost interactions that are relevant to laboratory rats and which also may improve understanding of persistent and prenatal human parvovirus infection.

Animals↗
PubMed1989

Persistent albuminuria as an index of diabetic nephropathy in type 2 diabetic patients in Osaka, Japan-incidence, risk factors, prognosis and causes of death.

A group of 1196 type 2 (non-insulin-dependent) diabetic patients was followed for a mean of 10 years to determine the incidence of persistent albuminuria, its associated risk factors and prognosis, as well as causes of death in patients. None of the patients studied had albuminuria on entry. The mean annual incidence rate of persistent albuminuria per 1000 person-years in the patients was higher in males than in females (18.42 and 12.57, respectively). Development of persistent albuminuria was associated with age at entry, duration of known diabetes, systolic blood pressure, fasting glucose level, presence of diabetic retinopathy and type of treatment. Among 193 patients who developed persistent albuminuria during the observation period, 66 (34.2%) died before the end of the observation period, with a mean survival period (+/- SD) of 3.0 +/- 3.1 years after the onset of persistent albuminuria, indicating an extremely poor prognosis. Renal disease was the predominant cause of death in patients who developed persistent albuminuria, followed by heart disease and cerebrovascular disease.

Adult↗
PubMed1991

Disturbed secretion of atrial natriuretic peptide in patients with persistent atrial standstill: endocrinologic silence.

Persistent atrial standstill is a very rare pathophysiologic condition whose diagnosis is established when both electrical and mechanical silence of the atria are confirmed. To test the hypothesis that secretion of atrial natriuretic peptide is disturbed in patients with persistent atrial standstill, the response of atrial natriuretic peptide secretion and other neurohormonal factors during exercise was investigated in three patients with a rate-responsive ventricular demand (VVI) pacemaker implanted for confirmed persistent atrial standstill. The results were compared with those observed in eight normal subjects and patients with a rate-responsive VVI (Group A) or atrial demand (AAI) (Group B) pacemaker implanted for confirmed sick sinus syndrome. Patients in Group A displayed significant elevation of alpha-human atrial natriuretic peptide secretion both before and during exercise (122.5 +/- 14.8 and 207.5 +/- 8.3 pg/ml, respectively) compared with those in Group B (55 +/- 14.1 and 116.4 +/- 51.5 pg/ml, respectively) and the normal subjects (18.9 +/- 9.8 and 30.8 +/- 19.2 pg/ml, respectively). This indicated development of a nonphysiologic increase in atrial volume or pressure overload, or both, in rate-responsive VVI pacing because of lack of atrioventricular synchrony. However, patients with persistent atrial standstill had undetectable (less than 10 pg/ml) or almost undetectable secretion of atrial natriuretic peptide as well as lower levels of cyclic guanosine monophosphate in the circulation both before and during exercise. Changes in plasma catecholamines during exercise were similar in patients with persistent atrial standstill compared with the other groups. This study indicates that "endocrinologic silence" accompanies electrical and mechanical silence of the atria, which may constitute a third diagnostic clue to persistent atrial standstill.

Adult↗
PubMed1995

Chronic fatigue: risk factors for symptom persistence in a 2 1/2-year follow-up study.

BACKGROUND: The prolonged disability of patients suffering from chronic fatigue may be due to sustaining factors that are independent of the cause and subject to intervention. This study reexamined a cohort of patients with chronic fatigue to define medical and psychiatric predictors of persistent symptoms. METHODS: Seventy-eight patients with chronic fatigue present for 6 months or more (not required to meet the Centers for Disease Control case definition for chronic fatigue syndrome [CFS]) completed a self-report, follow-up questionnaire to measure the overall improvement or worsening of their condition at a mean of 2.5 years after their initial examination. At the time of initial evaluation, patients underwent a structured psychiatric examination, physical examination, laboratory studies, and self-report measures of psychological distress and functional disability. The psychiatric examination queried the patient about 28 somatic symptoms that are separate from those associated with CFS. Discriminant analysis was used to determine which variables present at the initial examination were significant predictors of persistent symptoms and disability at 2.5 years. RESULTS: The factors most important at the time of initial presentation in predicting persistent illness were: (1) more than eight medically unexplained physical symptoms separate from those associated with CFS case definition; (2) lifetime history of dysthymia; (3) duration of chronic fatigue symptoms greater than 1.5 years; (4) less than 16 years of formal education; and (5) age older than 38 years. None of the results of the initial physical examination, or immunologic, general laboratory, or viral antibody measurements were significant in predicting persistence of symptoms. Recovery rates for those who met the criteria for CFS by either of two case definitions were lower than the rate of noncases, but the differences were not statistically significant. The five aforementioned variables formed a significant discriminative function, correctly classifying 78% of those who recovered and 74% of those with persistent symptoms. CONCLUSIONS: At initial examination, patients with chronic fatigue, more than eight medically unexplained physical symptoms (excluding symptoms in the case criteria for CFS), a lifetime history of dysthymic disorder, longer than 1.5 years of chronic fatigue, less than 16 years of formal education, and who were older than 38 years were the most likely to have persistence of symptoms of chronic fatigue at the 2.5-year follow-up.

Adult↗