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PubMed2002

Endocrine profiles of cows undergoing extended lactation in relation to the control of lactation persistency.

We conducted an experiment in dairy cows investigating the effects of calving season, milking frequency and nutrition on lactation persistency. Cows calved in the Spring (n=12) or Winter (n=12). Commencing in lactation week 9 one udder-half of each cow was milked thrice-daily and half of each calving group received additional concentrate at a fixed rate of 3kg per day above that of the control cows. As reported elsewhere, between lactation weeks 9 and 33 persistency (measured as the slope of decline in milk yield) was significantly improved by frequent milking (P<0.001), by calving in the Winter (P<0.001) and by additional concentrate (P<0.05). The cows were rebred after week 33. When analysis of persistency was extended up to week 20 of the recurring pregnancy only the frequency effect remained significant. Persistency was unaffected by the pregnancy up until pregnancy week 20 but was then greatly reduced (P<0.001). In this paper we report hormone concentrations. GH was unaffected by nutrition but was consistently elevated in the Winter calving group relative to the Spring. IGF1 and prolactin were both unaffected by nutrition and calving season, IGF1 tended to increase as lactation progressed but changes in prolactin were related to time of year more than stage of lactation. Insulin was not affected by nutrition and was lower in Winter calvers, but only during early lactation. Prior to rebreeding, lactation persistency was correlated (slightly) with [GH] but not with [IGF1] or [insulin] and was correlated significantly with changes in GH, IGF1 (both positive) and insulin (negative). In conclusion, whilst bovine lactation persistency is plastic and amenable to beneficial manipulation, the details of its endocrine control remain to be elucidated.

Animals↗
PubMed2002

Molecular bases of long-term memories: a question of persistence.

The most distinctive attribute of long-term memory is persistence over time. New studies have uncovered many aspects of the molecular and cellular biology of synaptic plasticity, and the acquisition and consolidation of memory, which are thought to depend on synaptic plasticity. Much less, however, is known about the molecular and cellular biology of long-term memory persistence. Recent findings in the field are construed within the conceptual framework that proposes that consolidation and persistence of long-term memories require modulation of gene expression, which can culminate in synaptic remodeling. Whether modulation of gene expression, and particularly the ensuing morphological plasticity of the synapse, is permissive, causal or sufficient for the materialization and persistence of the long-term trace is, as yet, undetermined. How persistent is persistence? Renewed interest is focused on the possibility that some long-term memories consolidate anew with retrieval, and could, under certain conditions, become transiently shaky in this period of reconsolidation.

Animals↗
PubMed1999

Embolotherapy of persistent endoleaks after endovascular repair of abdominal aortic aneurysm with the ancure-endovascular technologies endograft system.

PURPOSE: Endoleak is a potential complication after endovascular repair of abdominal aortic aneurysm (AAA). It may result in continued growth of the aneurysm and potentially result in aneurysm rupture. The authors present their experience with embolotherapy in patients with persistent perigraft flow treated with the Ancure-Endovascular Technologies endograft system. MATERIALS AND METHODS: Between February 1996 and August 1998, 54 patients underwent successful repair of AAA with use of the Ancure system. All underwent operative angiography and discharge computed tomography (CT). Follow-up included CT at 6, 12, and 24 months, and CT was also performed at 3 months if an endoleak was present on the discharge CT. Persistent endoleak was defined as perigraft flow still present on the 6-month CT. Seven of 21 initial endoleaks persisted at 6 months. Six patients returned for embolization of the perigraft space and outflow vessels including lumbar arteries and the inferior mesenteric artery (IMA). RESULTS: Five of the six patients had leaks from the proximal (n = 1) or distal attachment sites (n = 4) of the Ancure system with outflow into lumbar arteries and/or the IMA; one leak was caused by retrograde IMA flow. The six patients underwent nine embolization procedures with only one minor complication. Follow-up CT showed complete resolution of endoleak and decrease in size of the aneurysm sac in all patients. CONCLUSIONS: Although endoleak is commonly seen initially with the Ancure system, persistent leak occurred in 13% of the patients in the study. Persistent flow in most patients arises from a graft attachment site combined with patent outflow vessels such as the IMA or lumbar arteries. Persistent endoleaks can be effectively and safely embolized with use of a combination of coil embolization of the perigraft space and embolization of outflow vessels. Such intervention resulted in a decrease in size of the aneurysm sac.

Aged↗
PubMed2002

Persistent air-leak following pulmonary resection.

Air leaks are an unavoidable complication of pulmonary resection. The definition of a persistent air leak is arbitrary and may even be irrelevant in solving the problem. Persistent air leaks are more common in patients with severe COPD, and preoperative interventions are ineffective in reducing their prevalence. Meticulous surgical technique and care in handling and resection of the pulmonary parenchyma are essential in preventing persistent air leaks. Buttressing parenchymal staple lines and creating a pleural tent or pneumoperitoneum should be reserved for patients at risk for persistent air leaks. The use of currently available sealants is ineffective for the treatment of this complication. To stop persistent air leaks, early cessation of suction and placing chest tubes to an underwater seal is more effective than continuous suction. The management of persistent air leaks may require provocative chest tube clamping and permissive chest tube removal or patient discharge from the hospital with a chest tube and a Heimlich valve.

Chest Tubes↗
PubMed2002

Chlamydia trachomatis genes whose products are related to energy metabolism are expressed differentially in active vs. persistent infection.

The Chlamydia trachomatis genome encodes glycolysis and pentose phosphate pathway enzymes, two ATP/ADP exchange proteins, and other energy transduction-related components. We asked if and when chlamydial genes specifying products related to energy transduction are expressed during active vs. persistent infection in in vitro models and in synovia from Chlamydia-associated arthritis patients. Hep-2 cells infected with K serovar were harvested from 0-48 h post-infection (active infection). Human monocytes identically infected were harvested at 1, 2, 3, 5 days post-infection (persistent). RNA from each preparation and from synovial samples PCR-positive/-negative for Chlamydia DNA was subjected to RT-PCR targeting (a) chlamydial primary rRNA transcripts and adt1 mRNA, (b) chlamydial mRNA encoding enzymes of the glycolysis (pyk, gap, pgk) and pentose phosphate (gnd, tal) pathways, the TCA cycle (mdhC, fumC), electron transport system (cydA, cydB), and sigma factors (rpoD, rpsD, rpoN). Primary rRNA transcripts and adt1 mRNA were present in each infected preparation and patient sample; controls were negative for chlamydial RNA. In infected Hep-2 cells, all energy transduction-related genes were expressed by approximately 11 h post-infection. In monocytes, pyk, gap, pgk, gnd, tal, cydA mRNA were present in 1-2-day-infected cells but absent at 3 days and after; cydB, mdhC, fumC were expressed through 5 days post-infection. RT-PCR targeting mRNA from sigma factor genes indicated that lack of these gene products cannot explain selective transcriptional down-regulation during persistence. Analyses of RNA from synovial tissues mirrored those from the monocyte system. These data suggest that in the first phase of active chlamydial infection, ADP/ATP exchange provides energy required for metabolism; in active growth, glycolysis supplements host ATP. In persistence host, rather than bacterially produced, ATP is the primary energy source. Metabolic rate in persistent C. trachomatis is lower than in actively growing cells, as judged from assays for relative chlamydial primary rRNA transcript levels in persistent vs. actively growing cells.

Adenosine Triphosphate↗
PubMed2003

Psychoendocrine antecedents of persistent first-episode major depression in adolescents: a community-based longitudinal enquiry.

BACKGROUND: This longitudinal study investigated whether patterns of cortisol and DHEA that precede the onset of an episode of major depression influence time to recovery in a community ascertained sample of adolescents meeting DSM-IV criteria for major depression. METHOD: Sixty adolescents aged 12 to 16 at high risk for psychiatric disorders were followed for 24 months. At 12 months, 30 had experienced an episode of major depression and 30 had not. The second follow-up repeated the psychiatric evaluations with all participants completing the Kiddie-SADS Schedule for Schizophrenia and Affective Disorders. Hormone characteristics and self-reports completed at entry (the Mood and Feelings questionnaire and the Ruminations scale) together with intervening undesirable life events in the 12 months prior to onset, were used to determine the best pattern of psychosocial and endocrine features to predict persistent major depression. RESULTS: Compared to the never depressed (N = 30) and remitted adolescents (N = 19), persistently depressed cases (N = 11) had a raised morning cortisol/DHEA ratio at entry. Only persistent cases had higher levels of self-reported depressive symptoms and ruminations at entry compared to never depressed. There was no difference in exposure to undesirable life events before onset of disorder between remitted and persistent groups. Logistic regression techniques showed that only the cortisol/DHEA ratio predicted persistence. CONCLUSIONS: In community adolescents at high risk for psychiatric disorder persistent major depression may be distinguished from sporadic forms by the 08.00 h salivary cortisol/DHEA ratio prior to onset.

Adolescent↗
PubMed1985

Multiple-dose vials: persistence of bacterial contaminants and infection control implications.

Due to sporadic infections attributed to contaminated multiple-dose medication vials (MDV), some authorities have suggested discarding all MDV within 24 hours. We inoculated 11 commonly used medications with suspensions of 10 bacterial species previously associated with contaminated parenteral solutions and determined microbial persistence at both room and refrigerator temperature. At 22 degrees C, atropine, curare, folic acid, NPH insulin and triamcinolone did not allow microbial persistence beyond 4 hours. Lidocaine and heparin were sterile by 24 hours. Regular insulin, immune serum globulin, and myochrysine allowed persistence for up to 7 days. At 4 degrees C, bacterial persistence was significantly prolonged for all medications including those MDV requiring refrigeration. No organisms proliferated; however, F. meningosepticum and P. maltophilia were particularly persistent at both temperatures. The risk of persistent MDV contamination appears to be dependent upon specific pharmaceutical, microbe and storage temperature interactions. Recommendations for the refrigeration of MDV medications may require reevaluation on a product-by-product basis.

Bacteria↗
PubMed2005

Incidence and persistence of classical swine fever in free-ranging wild boar (Sus scrofa).

Although veterinary authorities aim to limit persistence of classical swine fever (CSF) in wild boar (Sus scrofa), to avoid potential transmission to pigs, factors influencing CSF transmission and persistence are not clearly understood. Here we analyse incidence and persistence in a CSF epidemic that occurred in the French Vosges Forest. Higher incidence was found in large forests compared to smaller isolated ones, being highest near the starting point of the epidemic, but poorly related to the local density. We hypothesize that the spatial and social structure of wild boar populations may be responsible for this variability of incidence over space. Persistence was highest near the starting point of the epidemic and where initial density was highest. We hypothesize that persistence was favoured by the abundance of young wild boar, itself encouraged by CSF. Our results allow us to propose management measures aimed at limiting CSF persistence.

Animal Husbandry↗
PubMed1999

Persistence of the left superior caval vein: can it potentiate obstructive lesions of the left ventricle?

Recent evidence has suggested that persistence of the left superior caval vein is associated with a high incidence of obstructive lesions of the left heart. To shed more light on this issue 1085 patients with congenital heart disease were studied retrospectively, with the aim of estimating the prevalence of a persistent left superior caval vein and its associated anomalies, focusing attention on obstructive lesions in the left and right ventricles. Patients with isomerism of the atrial appendages, or hypoplastic left heart syndrome, were excluded. A persisting left superior caval vein was present in 57 patients (5.2%). The overall incidence of obstructive lesions of the left heart was higher in patients with than in those without a persistent left superior caval vein (31.6 versus 7.8%,p < 0.001). Relative hypoplasia of the left ventricle was also higher in patients with persistent left superior caval vein (14 versus 0.8%, p < 0.001). The obstructive lesions found in the left heart, compared with the number in those without a left caval vein, were: mitral stenosis, 5.2 versus 0.7%; subaortic stenosis, 5.3 versus 0.9%; aortic coarctation, 17.5 versus 5.8% (p < 0.01); all of these in association, 3.5 versus 0.4%. In contrast, the incidence of obstructive lesions of the right heart was similar in the two groups of patients. It is concluded that persistence of the left superior caval vein can perturb the normal development of the left ventricle, being strongly associated with obstructions to left ventricular inflow and outflow.

Aortic Coarctation↗
PubMed2003

Leaching potential of persistent soil fumigant residues.

Persistent fumigant residues in soil resulting from agricultural pest-control practices may be released into water and leached to groundwater. In this study, the leaching potential of persistent soil fumigant residues was evaluated, and the effect of dissolved organic matter (DOM) and ammonium thiosulfate (ATS) amendment was investigated. A silt loam soil was incubated separately with the fumigants 1,3-dichloropropene (1,3-D), chloropicrin (CP), and methyl isothiocyanate (MITC) at 240-990 mg kg(-1) for 35 d, followed by 48 h of evaporation. The soil was packed into stainless steel columns (1.4 cm x 10 cm) and leached with water, 5 mM ATS, and DOM solution (DOC 250 mg L(-1)) by gravity. Residues of 1,3-D, CP, and MITC in the evaporated soil were 5.61, 11.38, and 1.83 mg kg(-1), respectively. Concentrations of 1,3-D, CP, and MITC in column effluents ranged from 0.05 to 0.73, 0.16 to 0.81, and 0.05 to 0.27 mg L(-1), respectively, when the soil was leached with 10 pore volumes of water. DOM did not promote the leaching of persistent fumigant residues, and ATS remarkably reduced the amount of 1,3-D and CP yet notably increased MITC recovered in the effluents. The results suggest that the leaching of persistent fumigant residues through soil to water is significant, and movement of fumigants in soil is not facilitated by DOM. Amending soil with ATS through irrigation is an effective method to remove persistent residues of halogenated fumigants. To reduce groundwater pollution risks posed by fumigation, persistent soil fumigant residues have to be considered.

Allyl Compounds↗
PubMed2000

Persistence of volatile compounds in the breath after their consumption in aqueous solutions.

The persistence of volatile compounds in the breath was monitored after their consumption in aqueous solutions. Factors studied were variation in volatile release patterns between panelists, effect of adding hydroxy propyl methyl cellulose (HPMC), and differences among compounds. For any given compound, the extent of volatile persistence was broadly similar for all panelists. Adding HPMC at concentrations in excess of c did not substantially affect persistence. The largest differences in persistence were observed when compounds were compared (>20-fold). The differences were modeled using a quantitative structure property relationship approach, based on the persistence data from 41 compounds. Major components of the model were terms that described the hydrophobicity and vapor pressure of a molecule. The model was validated with a test set, which showed that there was a significant correlation between persistence predicted by the model and the actual values observed.

Adult↗
PubMed2001

High levels of urinary eosinophil protein X in young asthmatic children predict persistent atopic asthma.

Levels of urinary eosinophil protein X (U-EPX) and eosinophil counts were measured in 32 children (12-36 months of age) who were hospitalized for acute asthma, and the U-EPX levels were measured in 20 healthy children of the same age. The ability of these parameters to predict persistent asthma (at least one wheezing episode during the last 6 months) and atopic asthma (a positive skin-prick test [SPT]), was evaluated at a follow-up 2 years later. On admission, levels of U-EPX were higher in children with asthma (median: 120 microg/mmol of creatinine; quartiles: 67-123 microg/mmol of creatinine) than in controls (60 microg/mmol of creatinine, 38-74 microg/mmol of creatinine; p< 0.001). The U-EPX level was higher in those with persistent atopic asthma at follow-up (173 microg/mmol of creatinine, 123-196 microg/mmol of creatinine, n = 16), than in those with persistent non-atopic asthma (73 microg/mmol creatinine, 46-105 microg/mmol of creatinine, n = 8; p< 0.05), and higher than in those with transient asthma (no symptoms at follow-up) (106 microg/mmol creatinine; 42-167 microg/mmol of creatinine, n = 8; p< 0.05). By multiple logistic regression analysis, U-EPX was the only parameter able to predict persistent atopic asthma; eosinophil counts, parental atopy, age or gender could not. Parental atopy was the only parameter predictive for persistent asthma, regardless of atopic status. In conclusion, levels of U-EPX, but not eosinophil counts, measured in young children hospitalized with acute asthma can predict the persistence of atopic asthma 2 years later.

Antiviral Agents↗
PubMed2000

Relative persistence of behavior: a fundamental measure of relative reinforcing effects.

Relative persistence of behavior is measured in terms of rates of behavior at a higher schedule value divided by rates of behavior at a lower schedule value and then multiplied by 100 to express the result as a percentage. Relative persistence of behavior is a direct function of reinforcer size over a broad range of values. In 1 study, food was the reinforcer; however, in most studies of persistence, drug reinforcers were used, and the drugs were taken orally or intravenously. A variety of reinforcing drugs were studied: barbiturates, opioids, psychomotor stimulants, a dissociative anesthetic, and alcohol. Both ratio and interval schedules were used to study relative persistence of behavior in human participants, male and female rhesus monkeys (Macaca mulatta), and rats. Thus, studies of persistence are based on results of an extensive set of conditions. The results support the proposition that relative persistence of behavior is a fundamental measure of relative reinforcing effects.

Animals↗
PubMed1991

Effects of display luminance, stimulus meaningfulness, and probe duration on visible and schematic persistence.

Partial report performance is conceived of as consisting of two independent sources of information: visible persistence and schematic persistence. Following the work of Di Lollo and Dixon (1988), these two sources of information were separated experimentally by varying interstimulus interval and stimulus onset asynchrony independently. In the present experiment we asked whether visible persistence and schematic persistence would be affected by display luminance, stimulus meaningfulness, or probe duration. The results were fit accurately by an extension of the Di Lollo and Dixon independent-decay model in which display luminance affected visible persistence but stimulus meaningfulness and probe duration affected neither form of persistence directly.

Adult↗
PubMed2006

Interleukin-10 determines viral clearance or persistence in vivo.

Persistent viral infections are a major health concern. One obstacle inhibiting the clearance of persistent infections is functional inactivation of antiviral T cells. Although such immunosuppression occurs rapidly after infection, the mechanisms that induce the loss of T-cell activity and promote viral persistence are unknown. Herein we document that persistent viral infection in mice results in a significant upregulation of interleukin (IL)-10 by antigen-presenting cells, leading to impaired T-cell responses. Genetic removal of Il10 resulted in the maintenance of robust effector T-cell responses, the rapid elimination of virus and the development of antiviral memory T-cell responses. Therapeutic administration of an antibody that blocks the IL-10 receptor restored T-cell function and eliminated viral infection. Thus, we identify a single molecule that directly induces immunosuppression leading to viral persistence and demonstrate that a therapy to neutralize IL-10 results in T-cell recovery and the prevention of viral persistence.

Animals↗
PubMed2026

Microbiome features associated with persistent intestinal carriages of Escherichia coli ST131 in a Southeast Asian cohort study.

Escherichia coli sequence-type 131 (ST131) is the dominant global extraintestinal pathogen capable of asymptomatic intestinal carriage and sustained household transmission, challenging infection control. Despite its clinical significance, the ecological determinants of gut persistence remain poorly understood. We performed shotgun metagenomics on fecal samples to investigate gut microbiome features associated with ST131-positive samples, distinct host carrier statuses (persistent, intermittent and non-carriers) and household risks in a study of a Southeast Asian cohort. Here, we show that ST131 carriage was associated with compositional shifts without reducing species alpha-diversity. Regression analyses identified depletion of commensal taxa and the 1,5-anhydrofructose degradation pathway in ST131-positive samples. Persistent carriers exhibited highly perturbed microbiome enriched with pathobionts, aerobactin- and lipopolysaccharide (LPS)-biosynthesis pathways. Comparing household risk groups to control, revealed that biotin biosynthesis and 1,5-anhydrofructose degradation may influence ST131 co-colonization through both direct and indirect mechanisms. Machine learning analyses identified metabolic pathways as stronger discriminators of persistent carriage than taxonomic features. Genomic-resolved analysis of clinical ST131 isolates revealed conserved genes for iron-acquisition, LPS and antibiotic resistance determinants. Overall, while commensals and metabolism may influence initial ST131 colonization, persistent carriage is associated with specific microbial and metabolic adaptations, providing potential targets to limit intestinal ST131 persistence.

Humans↗
PubMed2006

Cutaneous human papillomaviruses persist on healthy skin.

Cutaneous human papillomaviruses (HPVs) are frequently found in healthy skin and have also been implicated in non-melanoma skin cancer. For genital HPV types, a persistent infection with one of the high-risk types is a prerequisite for the development of cervical cancer. However, there is only limited data on whether infections with cutaneous HPV types persist over time. Serial forehead swab samples collected from 63 volunteers (42 healthy individuals and 31 renal transplant recipients (RTRs)), sampled 6.3 years (range: 5.0-7.0 years) apart, were analyzed for HPV using general primer PCR, cloning, and sequencing. Among the healthy individuals, the prevalences of HPV were 69% (29/42) at enrolment and 71% (30/42) at follow-up. Among the individuals positive at baseline, 48% (14/29) had a persistent infection. Among the RTRs, 71% (15/21) were positive for HPV at enrolment and 90% (19/21) at follow-up. A persistent infection was detected in 33% (5/15). In total, HPV was detected in 44 of the samples collected at baseline and the same virus was found at follow-up in 43% (19/44). Persistence was not significantly associated with age, sex, immunosuppressive treatment, history of warts, or genus of HPV. We conclude that cutaneous HPV infections commonly persist over several years on healthy skin.

Base Sequence↗
PubMed1983

Recovery and persistence of stuttering among relatives of stutterers.

Recovery and persistence of stuttering were examined in the first-degree relatives of a large group of adult persistent stutters. The percentage of recovered individuals reported in these families supports the hypothesis that recovered and persistent stuttering are not independent disorders. Sex and type of relative were significant variables in the distributions of recovery and persistence of stuttering. Handedness in male subjects and birth order did not distinguish between recovered and persistent stutterers. Female recovered stutterers had significantly earlier ages of stuttering onset than the other groups (male recovered stutterers and male and female persistent stutterers). Female recovered stutterers also tended to recover earlier than male recovered stutterers, and the durations of stuttering symptoms were similar in both sexes.

Adolescent↗