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PubMed1994

Global contamination by persistent organochlorines and their ecotoxicological impact on marine mammals.

The present paper overviews the global contamination by persistent organochlorines and their ecotoxicological implications on marine mammals. The recent pattern of contamination by organochlorine residues in the coastal environment is prominent in tropical regions due to continuous usage in the low-latitude developing countries. The major emission source of organochlorines is probably the tropical belt and large quantities of volatilized contaminants are dispersed through the atmosphere on global terms. Reflecting this, a considerable contamination was observed in open ocean tropical waters as well as in the Arctic and nearby waters. The study of the mass transfer of organochlorines at the air-water interface suggests that the oceanic water bodies, particularly Arctic waters, act as a sink for persistent contaminants. In this regard, the marine mammals, particularly cetaceans, are one of the animal groups receiving high concentrations of persistent organochlorines arising out of a worldwide contamination. They can amplify much greater amounts of toxic contaminants through feeding and also pass them in large quantities from one generation to the next through lactation. Unfortunately, these animals have a smaller capacity for degradation of these contaminants due to the specific mode of cytochrome P-450 enzyme systems. These drug-metabolizing enzyme systems may be related to the possible effects of persistent organochlorines, particularly coplanar PCBs. Furthermore, the residue levels of these contaminants in marine mammals are unlikely to decline in the near future. Considering all these facts, it may be concluded that marine mammals are one of the most vulnerable and possible target organisms with regard to long-term toxicity of hazardous man-made chemicals in the future.

Animals↗
PubMed1989

Eclampsia as a possible risk factor for persistent trophoblastic disease.

Twenty cases of hydatidiform mole complicated by eclampsia with adequate postevacuation follow-up are identified in a review of the literature since 1866. The clinical presentation of each of these patients is reviewed with particular attention to the existence of known risk factors for persistent trophoblastic disease. After excluding 3 women with coexisting fetus and 2 others who were treated initially with a total abdominal hysterectomy, it was discovered that 14 of the remaining 15 women developed persistent trophoblastic disease. This frequency of persistent trophoblastic disease is greater than can be explained based on previously described risk factors and suggests that the occurrence of eclampsia may be an independent risk factor for persistent trophoblastic disease.

Adult↗
PubMed1989

Relationships between fertility, peak milk yields and lactational persistency in dairy cows.

Peak milk yield, lactational persistency and conception rates were studied using 5928 lactation records of high milk-producing cows at three California dairies. Log-linear analysis was used to study relationships between peak milk yield, lactational persistency, dairy of origin, lactation number and conception rates in 3850 completed lactations. Cows with peak milk yields greater than the median (38.2 kg milk per day) were less likely to have conceived in one or two breedings than cows with peak milk yields lower than or equal to the median. Cows with a higher than median (0.755) lactational persistency were less likely to have conceived in one or two breedings than cows with a lactational persistency lower than or equal to the median. Dairy of origin had a significant effect on the probability of conceiving in one or two breedings. Cows in the first lactation were more likely than those in subsequent lactations to conceive in one or two breedings. This retrospective study demonstrated that subfertility is associated with high peak lactational yields in high milk-producing California cows.

Journal Article↗
PubMed1993

Persistent hepatitis C viraemia without liver disease.

In viral infections persistence of the virus is not always associated with virus-induced disease. To find out if active hepatitis C virus (HCV) infection can persist without liver disease we selected four symptom-free individuals with antibodies to HCV but normal aminotransferase levels. They were followed up for 3 years by monthly serology and a liver biopsy was done. At presentation, all four had both antibodies to HCV and circulating HCV RNA. During follow-up their sera remained persistently positive for all HCV antibodies and RNA yet aminotransferase levels did not increase and liver biopsy was normal. These findings indicate that persistent hepatitis C viraemia is not invariably associated with liver damage.

Adult↗
PubMed1986

Possible immunoenhancement of persistent viremia by feline leukemia virus envelope glycoprotein vaccines in challenge-exposure situations where whole inactivated virus vaccines were protective.

Kittens immunized with purified native FeLV-gp70 or -gp85 envelope proteins developed ELISA, but not virus neutralizing, antibodies in their serum to both whole FeLV and FeLV-gp70. Kittens vaccinated with envelope proteins and infected with feline sarcoma virus (FeSV) developed smaller tumors than nonvaccinates, but a greater incidence of persistent retroviremia. Similarly, FeLV-gp70 and -gp85 vaccinated kittens were more apt to become persistently retroviremic following virulent FeLV challenge exposure than nonvaccinates. Kittens vaccinated with inactivated whole FeLV developed smaller tumors after FeSV inoculation and had a lower incidence of persistent retroviremia than nonvaccinates. The protective effect of inactivated whole FeLV vaccine against persistent retroviremia was also seen with FeLV challenge-exposed cats. Protection afforded by inactivated whole FeLV vaccine was not associated with virus neutralizing antibodies, although ELISA antibodies to both whole FeLV and FeLV-gp70 were induced by vaccination.

Animals↗
PubMed1990

Persistence of parvovirus H-1 DNA in human B- and T-lymphoma cells.

Persisting DNA of parvovirus H-1 could be demonstrated in cells of two human lymphoma cell lines, the Burkitt lymphoma cell line BL2 and the T-cell leukemia cell line Jurkat which survived infection with parvovirus H-1. Persistence of H-1 DNA rendered the cells resistant to a second H-1 infection. This resistance to H-1 superinfection persisted even after loss of H-1 DNA occurring after approximately 150-200 cell generations. Resistance to H-1 superinfection was accompanied by reduced uptake of infectious particles and by a block of H-1 DNA replication. This suggests that persistent H-1 infection leads to modifications of cellular functions involved in the permissivity for H-1.

Burkitt Lymphoma↗
PubMed1993

Establishment of persistent reovirus infection in SC1 cells: absence of protein synthesis inhibition and increased level of double-stranded RNA-activated protein kinase.

In the present study we report the establishment and characterization of an SC1 cell line persistently infected by reovirus. We observed that a significant percentage of SC1 cells was resistant to cell lysis upon infection with non-defective reovirus stocks. The apparent resistance of SC1 cells to the virus-induced inhibition of protein synthesis is probably an important factor favoring the establishment of such a persistence. The remaining cells, obtained following reovirus infection at a high multiplicity of infection, were kept as a continuous cell line and shown to have normal growth rate. They also released a high titer of virus that did not appear to differ from the original stock in neither infectivity nor genomic pattern. Electron microscopic examination further confirmed the presence of well-developed viral inclusions in the persistently infected cells. These cells were resistant to viral superinfection and exhibited a high constitutive level of the double-stranded RNA-activated protein kinase that might be involved in this resistance. We suggest that this cell line might be an interesting, and possibly more natural system than most previously used cell lines, for the continuing study of virus-host cell interactions during establishment of viral persistence using the much-studied model of reovirus infection.

Animals↗
PubMed1993

Variabilities in the antigenic structure of persisting tick-borne encephalitis virus strains.

Antigenic variants in the E protein from persisting tick-borne encephalitis (TBE) virus strains were analyzed using monoclonal antibodies (MAbs) to an analogous protein of the reference Sofyin strain. MAbs to sequential epitopes demonstrated their ability to differentiate persisting TBE virus strains from Sofyin and from each other. Two MAbs (2H3 and 13D6) showed a higher neutralizing activity in the interaction with persisting TBE virus variants as compared to the Sofyin strain. Based on the obtained data, a comparison was made of topologically identical epitopes from the E protein of reference and persisting virus strains. The possibility of increasing the neutralizing activity of MAbs through alterations in the primary structure of sequential antigenic sites is discussed.

Animals↗
PubMed1996

Risk for diabetes and persistent impaired glucose tolerance among middle-aged Finns.

Among 183 middle-aged Finnish subjects with impaired glucose tolerance (IGT) defined according to the 1985 World Health Organization (WHO) criteria) who were retested on average 2.1 years after the first examination, diabetes developed in 14 (7.7%), persistent IGT in 54 (29.5%), and IGT was transient in 115 (62.8%). The odds ratio for diabetes was 4.4 (95% Confidence Interval (CI): 1.3-15.3) among subjects with a body mass index (BMI) of 30 kg/m2 or more, compared with those with a BMI of less than 30 kg/m2. The increase in BMI during the follow-up period was also an independent risk predictor for diabetes. The odds ratios of having persistent rather than transient IGT were 3.0 (95% CI: 1.2-7.8) and 4.3 (95% CI: 1.5-12.6), among subjects with fasting insulin levels of 8.1-12.9 mU/1 and 13.0 mU/1 or more, respectively, compared with subjects with a fasting insulin level of no more than 8.0 mU/1. the degree of glucose intolerance and the diagnosis of hypertension at the initial examination were predictive of persistent IGT. It is evident from the present data that fasting hyperinsulinaemia forms an essential basis of persistence of IGT and diabetes, and that obesity plays a precipitating role for the deterioration from IGT to diabetes. Efforts to prevented diabetes should be focused on ways to reduce insulin resistance and obesity.

Blood Pressure↗
PubMed1995

Determinants of persistent compliance with screening for colorectal cancer.

Mass population screening for colorectal cancer is currently being evaluated by means of randomized controlled trials. These trials point to the likelihood that, if implemented, the level of both initial and sustained compliance will prevent the full potential of screening being realised. The paper opens by reviewing the evidence on determinants of compliance, both initial and longer term, although little empirical evidence on adherence to repeated screening is currently available. The paper then presents the results of a survey of persistent compliers and non-compliers within the English screening trial, in order to identify those characteristics most closely associated with persistent compliance behaviour. Persistent compliers are found, inter alia, to be of higher socio-economic classes than persistent non-compliers, to have more personal and family experiences of illness and to visit their dentists more regularly. The results suggest that generalized attempts at compliance enhancement would be ineffectual against the prevailing background characteristics of the non-compliant population, and that the more overt targeting of efforts in this respect is to be preferred.

Aged↗
PubMed1993

Neurogenesis persists in the subependymal layer of the adult mouse brain.

Neurogenesis of olfactory bulb granule cells is known to persist in adult rats where, in some strains, the bulbs grow throughout life. In mice, bulb growth ceases early in adulthood and here we ask if granule cell neurogenesis persists after the bulbs have stopped growing. By injecting adult mice with bromodeoxyuridine (BrdU) and allowing short and long survival times, we found that new cells form in the subependymal layer and that they migrate subsequently into the olfactory bulbs where they acquire the nuclear morphology of granule cells and express neuron-specific markers. Using [3H]thymidine, we found that most of these adult-generated granule neurons persist within the bulbs for at least 16 weeks. This shows the persistence of neurogenesis and neuronal migration in adult animals in which the olfactory bulbs have stopped growing.

Animals↗
PubMed1990

Induction, blockade and restoration of a persistent hypersensitive state.

A new model of chronic hypersensitivity was developed in the rat by daily intraplantar administration of either prostaglandin E2 dopamine or isoprenaline, for a period of 2 weeks. Like other hyperalgesic mediators, dibutyryl-cAMP, when applied to the paws, caused an acute effect but did not produce persistent hypersensitivity. The persistent hypersensitive state was not affected by a typical non-steroidal anti-inflammatory drug (indomethacin), was temporarily inhibited by a centrally acting analgesic (morphine), was partially inhibited by a protein synthesis inhibitor (cycloheximide) and abolished by a single dose of peripherally acting analgesics such as dipyrone or N-methyl morphine. Once the residual hypersensitivity had been abolished with dipyrone or N-methyl morphine, a small dose of prostaglandin E2, dopamine or Interleukin-1 beta, which in normal animals causes a mild and short lived effect, restored the persistent hypersensitive state. This ability to restore the persistent effect was not observed with intraplantar administration of dibutyryl-cAMP. Our results suggest the existence of a peripheral trace of inflammatory pain, a phenomenon which may be associated with stimulation of neuronal adenylate cyclase and protein synthesis. This concept may explain part of the puzzle of chronic inflammatory pain and lead to the development of new analgesics.

Animals↗
PubMed1981

Improvement in the persistence of microbial asparaginase and glutaminase in the circulation of the rat by chemical modifications.

Three enzymes used in cancer chemotherapy (asparaginases from Escherichia coli and Erwinia carotovora and glutaminase from Achromobacter) were each reacted with four amino specific reagents (ethyl acetimidate, O-methylisourea, succinic anhydride, and formaldehyde/sodium borohydride). The half-lives of the modified enzymes measured in the blood of rats showed that guanidation, acetimidation and reductive alkylation were more likely to increase the persistence of the native enzymes than succinylation. However, the improvement in the persistence of any one enzyme after any one modification could not be predicted from the results with the others. It was concluded that changes in persistence caused by each modification were due to the different effects on the tertiary structure of each native enzyme. The advantages of chemical modification for increasing the persistence of enzymes over other methods such as encapsulation or aggregation are discussed.

Alcaligenes↗
PubMed1988

Transmission of bovine virus diarrhoea virus (BVDV) by artificial insemination (AI) with semen from a persistently-infected bull.

Twelve heifers that did not have antibodies to bovine virus diarrhoea virus (BVDV) were inseminated with semen from a bull that was persistently infected with the virus and contained 10(4.0)-10(6.5) TCID50 0.1 ml-1. All 12 became infected, as indicated by seroconversion within 2 weeks of insemination. Four control heifers were inseminated with virus-free semen. The virus was not transmitted to these animals in spite of close contact with the heifers inseminated with the infected semen. All the heifers became pregnant and gave birth to clinically normal calves at term. However, one calf was born persistently infected with BVDV. After the birth of this persistently-infected calf the control heifers and their calves seroconverted. The study demonstrates that BVDV may be transmitted in cattle by artificial insemination (AI). Therefore entry of persistently-infected animals into AI centres should be prevented.

Animals↗
PubMed1995

Risk factors which predict persistent cancer in the abnormal larynx following definitive irradiation.

Laryngeal abnormalities following definitive irradiation for carcinoma of the larynx are common. The objective of this study was to identify risk factors for persistent cancer in such patients who were found to have abnormal larynges following definitive irradiation. A retrospective evaluation of 185 consecutive patients undergoing primary irradiation for a glottic or supraglottic laryngeal squamous carcinoma treated between 1976 and 1990 at the Affiliated Hospitals of the Medical College of Wisconsin was performed. From chart review, data concerning site, stage, intent of treatment, smoking history, treatment dose, fraction size, failure patterns, and outcome were obtained. In addition, worrisome signs and symptoms including ulceration, dysphasia, odynophagia, airway distress, aphonia, blood, pain, oedema, aspiration, and pneumonia were recorded. Univariate association with failure and a persistently abnormal laryngeal examination was assessed using the Mantel-Haenszel test. The odds ratio was used to estimate relative risk associated with dichotomous risk factors. Disease-free and overall survival were estimated using Kaplan-Meier methodology. The log rank test was used to compare survival as defined by the levels of various risk factors. Two-year disease-free survival was 83% (T1 = 93%, T2 = 72%, T3/T4 = 66%). Primary failure was associated with the presence of an abnormal examination (P = 0.001), tracheotomy (P = 0.001), symptom index (P = 0.002), aphonia (P = 0.003), advanced T stage (P = 0.03), and lower total dose (P = 0.03). Of 151 patients who survived 6 months disease-free with an intact larynx, an abnormal examination was seen in those with advanced T stage (P = 0.002), supraglottic primary (P = 0.003), symptom index (P = 0.008), eventual failure at the primary site (P = 0.008), continued smoking (P = 0.01), and higher total dose (P = 0.01). The symptom index (total signs and symptoms of airway distress, aphonia, ulceration, pain, oedema, dysphagia, blood production, aspiration, pneumonia, and odynophagia) was correlated with primary failure and continued smoking. Of 37 patients with continually normal examinations, only 1 (3%) failed at the primary site. Of 102 who survived 6 months but with an abnormal examination, 22 (22%) eventually developed a primary failure. Persistently abnormal larynges are common after radiation therapy, yet not all harbour cancer. Risk factors for persistent cancer include stage, airway, total dose, and symptom index. Patients whose larynges return to normal after radiation rarely fail at the primary site.

Carcinoma, Squamous Cell↗
PubMed2004

Identifying predictors of persistent non-alcohol or drug-related risky driving behaviours among a cohort of young adults.

This study sought to identify adolescent risk factors that predicted persistent risky driving behaviours among young adults. It was part of a longitudinal study of a birth cohort (474 males and 459 females). The potential predictors were self-reported data obtained at ages 15, 18, 21 years (academic qualifications, personality, mental health, anti-social behaviour and driving behaviour). The risky driving behaviour outcomes were obtained at ages 21 and 26 years and included driving fast for thrills, taking deliberate risks for fun, excessive speed, dangerous overtaking, and close following (tailgating). Persistent risky drivers were defined as those who often, or fairly often engaged in a behaviour at both ages. A minority of males and very few females were classified as persistent risky drivers. Among the males, the factors that predicted at least one, or more of the outcomes were the personality trait of low constraint (i.e. low scores for control, harm avoidance, and traditionalism), aggressive behaviour, and cannabis dependence. These are characteristics to be borne in mind when developing programmes for young drivers that aim to deter the development of persistent risky driving behaviour.

Accidents, Traffic↗
PubMed2006

A new response-time measure of object persistence in the tunnel effect.

The recognition of information about an object is facilitated by a preview of the information concerning that object. This facilitation is regarded as evidence for the representational persistence of the object. It is not known, however, if such facilitation is obtained even under the tunnel effect, in which a moving object is temporarily occluded. This facilitation may be a new way to measure the representational persistence of a moving object in the tunnel effect. We addressed this question by a "same-different" judgment task of a target symbol (" composite function" or "+"), drawn within the moving object, before and after encountering the occluder. Response times (RTs) were shorter when the object reappeared with spatial continuity at the proper place than it reappeared at the improper place, as in Experiments 1 and 3. Thus, facilitation was obtained even in the tunnel effect. When the occluder was invisible and deletion/accretion cues along the contour of the occluder were either removed (Experiment 2) or given improperly (Experiment 4), no facilitation was found. These results clearly indicate that the facilitated recognition was caused by amodal integration of the persisting representation from the unoccluded and modal phases. The present study demonstrates that the facilitated recognition (RT measurement) can be used to investigate the representational persistence in the tunnel effect.

Depth Perception↗
PubMed2004

Angiotensin-converting enzyme inhibitors as adjunctive therapy in patients with persistent atrial fibrillation.

OBJECTIVES: The purpose of the current study was to assess the effect of angiotensin-converting enzyme inhibitor (ACEI) therapy in facilitating cardioversion from persistent atrial fibrillation (AF) and maintaining sinus rhythm. BACKGROUND: Pharmacologic therapy and electrical cardioversion for AF are often unsuccessful in maintaining long-term sinus rhythm. METHODS: The current study, a 1-year, prospective follow-up, comprised 47 patients with persistent AF undergoing electrical cardioversion. Patients receiving ACEI were compared with those receiving other medications. The study end point was the number of defibrillation attempts required for atrial defibrillation and the number of hospital admissions. A secondary end point was change in signal-averaged P-wave duration (SAPD) 1 year after successful electrical cardioversion. RESULTS: Of those admitted and requiring electrical defibrillation, the number of defibrillation attempts required for successful cardioversion was significantly less in the ACEI group (P <.001). The incidence rate ratio for admissions comparing recipients of ACEI with others was 0.14 (P =.03). Patients receiving ACEI therapy had significantly lower SAPD at 1 year when compared with the no-ACEI group (135 ms +/- 3 vs 150 ms +/- 2, P =.002). CONCLUSIONS: The use of long-term ACEI therapy facilitated electrical defibrillation in patients with persistent AF. ACEI therapy also reduced SAPD, suggesting amelioration of the arrhythmogenic substrate. Furthermore, we confirmed that SAPD is prolonged in patients with persistent AF.

Angiotensin-Converting Enzyme Inhibitors↗