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PubMed2006

Mapping of quantitative trait loci for lactation persistency traits in German Holstein dairy cattle.

A whole genome scan to map quantitative trait loci (QTL) for persistency of milk yield (PMY), persistency of fat yield (PFY), persistency of protein yield (PPY) and persistency of milk energy yield (PEY) was performed in a granddaughter design in the German Holstein dairy cattle population. The analysis included 16 paternal half-sib families with a total of 872 bulls. The analysis was carried out for the first lactation and for the first three lactations combined using univariate weighted multimarker regression. Controlling the false discovery rate across traits and data sets at a level of 0.15 and treating the four persistency traits as different traits revealed 27 significant QTL. A total of 12 chromosomes showed significant QTL effects on a chromosomewise basis. The DGAT1 effect was highly significant for PPY and protein yield. A haplotype analysis using results of previous studies of the same design revealed a co-segregation of various persistency QTL and QTL affecting health traits like dystocia and stillbirth and functional traits like non-return rate 90 and somatic cell score.

Animals↗
PubMed2004

Persistent sodium current in subicular neurons isolated from patients with temporal lobe epilepsy.

The persistent sodium current is a common target of anti-epileptic drugs and contributes to burst firing. Intrinsically burst firing subicular neurons are involved in the generation and spread of epileptic activity. We measured whole-cell sodium currents in pyramidal neurons isolated from the subiculum resected in drug-resistant epileptic patients and in rats. In half of the cells from both patients and rats, the sodium current inactivated within 500 ms at -30 mV. Others displayed a tetrodotoxin-sensitive slowly or non-inactivating sodium current of up to 53% of the total sodium current amplitude. Compared with the transient sodium current in the same cells, this persistent sodium current activated with normal kinetics but its voltage-dependent activation occurred 7 mV more hyperpolarized. Depolarizing voltage steps that lasted 10 s completely inactivated the persistent sodium current. Its voltage dependence did not differ from that of the transient sodium current but its slope was less steep. The voltage dependence and kinetics of the persistent sodium current in cells from patients were not different from that in subicular cells from rats. The current density and the relative amplitude contribution were 3-4 times greater in neurons from drug-resistant epilepsy patients. The abundant presence of persistent sodium current in half of the subicular neurons could lead to a larger number of neurons with intrinsic burst firing. The extraordinarily large amplitude of the persistent sodium current in this subset of subicular neurons might explain why these patients are susceptible to seizures and hard to treat pharmacologically.

Animals↗
PubMed2005

Fine root distribution and persistence under field conditions of three co-occurring Great Basin species of different life form.

Fine roots of an annual grass, a perennial grass and a perennial shrub were examined. Based on life histories and tissue composition, we expected the greatest root persistence for the shrub and shortest for the annual grass. Roots were observed with minirhizotrons over 2 yr for number, length and diameter changes. A Cox proportional hazard regression correlated root persistence with soil water, depth, diameter and date of production. In 2001, grass roots had similar persistence times, but shrub roots had the shortest. In 2002, the annual had the longest median root persistence, the perennial grass intermediate and the perennial shrub had the shortest. All species responded similarly to the magnitude of seasonal precipitation; root numbers increased with favorable soil moisture and disappeared with drying; fewer, thinner roots at greater soil depths were found in the drier year (2001). Root persistence increased with soil moisture, diameter and earlier appearance in the spring. Plasticity in root morphology and placement was influenced by water availability, yet persistence was surprisingly contrary to expectations.

Agropyron↗
PubMed2002

Persistent post-sclerotherapy pigmentation due to minocycline. Three cases and a review of post-sclerotherapy pigmentation.

BACKGROUND: Post-sclerotherapy pigmentation, usually overlying the treated veins and independent of any drug ingestion, is common. This pigmentation is brown and represents haemosiderin and sometimes melanin as well. It usually slowly fades over a period of months, only uncommonly persisting for years. Cutaneous pigmentation due to minocycline ingestion is a known but rare adverse effect. It usually appears as a round or irregular shaped patch that is dark blue to black, representing minocycline moieties and iron complexes. Its persistence for years is common. Clinically and histopathologically, these two causes of pigmentation are quite distinct. In the absence of ulceration, minocycline pigmentation koebnerised by sclerotherapy has not previously been reported. AIMS: To determine the nature of the pigmentation appearing in three patients who had been taking minocycline at the time, or shortly after, they had received sclerotherapy. Clinically, although this pigmentation had the usual distribution observed after sclerotherapy, it was persistent and appeared dark blue to black. RESULTS: The persistent post-sclerotherapy linear pigmentation observed in all three patients had the characteistics of minocycline pigmentation. CONCLUSIONS: This is the first report of such minocycline-aggravated post-sclerotherapy pigmentation. Persistent post-sclerotherapy pigmentation caused by minocycline is a risk associated with ingestion of this drug. Patients need to be warned of this risk because, unlike post-sclerotherapy pigmentation that develops in the absence of drug ingestion, minocycline-aggravated post-sclerotherapy pigmentation may persist for years.

Adult↗
PubMed1992

Epidemiological and clinical characteristics of acute and persistent diarrhoea in rural Bangladeshi children.

A community-based longitudinal study of acute and persistent diarrhoea in 705 children less than five years old was carried out for a year in a rural area of Bangladesh. Diarrhoea morbidity data were collected from each study child every fourth day by home visit. Clinical features of diarrhoeal episodes and diarrhoeal management information were documented. The overall diarrhoeal incidence rate in the study children was 4.6 episodes per child per year. The incidence of persistent diarrhoea was 34/100 child-years. Persistent diarrhoea was positively associated with young age and more severe illness, characterized by the presence of clinical dehydration or blood in the stool in the first week. Use of ORT in the first week was positively associated and use of an antibiotic was negatively associated with the occurrence of persistent diarrhoea. Reduced breast-feeding and consumption of cow's milk at some time during the episode were also positively associated with persistence. This would suggest that appropriate fluid and dietary management for all episodes should be the goal. Children with more severe initial illness characterized by the presence of blood in the stool or clinical dehydration should have more careful follow-up to identify persistent episodes and adverse nutritional effects. Breastfeeding should be continued during acute diarrhoea, but the role of ORT, antibiotics and cow's milk deserves further investigation.

Acute Disease↗
PubMed1992

Epidemiology of persistent diarrhea and etiologic agents in Mirzapur, Bangladesh.

To determine the epidemiology and etiologic agents of persistent diarrhea we carried out an intensive diarrhea surveillance on children less than six years old in rural Bangladesh. From March 1987 to February 1989 we examined 363 children through diarrhea recall interviews and analyzed stool samples of all diarrhea cases for potential pathogens. Results showed that children had an average of two episodes per year and the incidence rate of diarrheal episodes defined as acute (< 14 d) and persistent (> or = 14 d) varied similarly with age. The peak incidence (episodes/child/year) of acute diarrhea (2.8) and persistent diarrhea (0.8) occurred in the 6-11 months age group. The data showed that an episode tended to be prolonged if the stool was loose/mucoid or bloody at onset. Aggregative adherent Escherichia coli was found significantly more often at onset in persistent than in acute episodes, whereas Shigella, Aeromonas, Giardia and toxigenic E. coli were isolated with less frequency in persistent than acute episodes. This suggests that other factors might be more important in the development of persistent diarrhea than specific pathogens.

Animals↗
PubMed1992

Persistent diarrhea in northeast Brazil: etiologies and interactions with malnutrition.

With the improved control of acute diarrheal illness mortality with oral rehydration therapy, persistent diarrhea is now emerging as a major cause of childhood mortality in tropical developing areas like the impoverished populations in Brazil's Northeast. "Graveyard surveillance" in the rural community of Guaiuba in northeastern Brazil revealed fully half of the 70% diarrhea mortality was due to persistent diarrheal illnesses. Furthermore, 11% of 14 or more diarrheal illnesses per child per year in an urban slum in Fortaleza persisted beyond 14 days, a definition that clearly identified the high risk children for heavy diarrhea burdens. Not only did heavy diarrhea burdens ablate the key "catch-up" growth seen in severely malnourished children and in children following previous diarrheal illnesses, but malnutrition significantly predisposed children to a greater incidence and duration of diarrhea as well as a greater incidence of persistent diarrhea. Etiologic studies of 37 children presenting with persistent diarrhea to Hospital das Clinicas in Fortaleza revealed that Cryptosporidium (in 13%) and enteroadherent E. coli (36% with aggregative, 29% with diffuse and 13% with localized adherence to HEp-2 cells) were the predominant potential pathogens found in the stool or upper small bowel. These findings suggest that persistent diarrhea is emerging as an important health problem in Brazil's Northeast, that it identifies a high risk child for heavy diarrhea burdens, that important interactions occur with malnutrition and that Cryptosporidium and enteroadherent E. coli warrant further study as potential etiologies of this major cause of morbidity and mortality.

Animals↗
PubMed1992

A persistent sodium current in rat ventricular myocytes.

1. The tight seal, whole-cell, voltage-clamp technique was used to record currents from single ventricular myocytes acutely dissociated from adult rat hearts. Subtraction of currents recorded in the presence and absence of tetrodotoxin (TTX, 50 microM) revealed a small, persistent, inward current following a much larger, transient, inward current. 2. Both currents were sodium currents because they reversed close to the sodium equilibrium potential and were depressed when choline was substituted for extracellular sodium. 3. The persistent sodium current could be recorded when the transient current had been inactivated with conditioning depolarization. Only slight inactivation of the persistent current occurred during depolarizing pulses lasting up to 900 ms. 4. A lower concentration of TTX (0.1 microM) blocked the persistent sodium current while having little effect on the transient sodium current. 5. The persistent sodium current was activated at more negative potentials than the transient sodium current. It cannot have been a window current because it was recorded at positive potentials when the transient current was completely inactivated. 6. Because the persistent and transient sodium currents had a different voltage dependence and sensitivity to TTX, it was concluded that different channels are responsible for the two currents.

Animals↗
PubMed2004

Bacterial persistence as a phenotypic switch.

A fraction of a genetically homogeneous microbial population may survive exposure to stress such as antibiotic treatment. Unlike resistant mutants, cells regrown from such persistent bacteria remain sensitive to the antibiotic. We investigated the persistence of single cells of Escherichia coli with the use of microfluidic devices. Persistence was linked to preexisting heterogeneity in bacterial populations because phenotypic switching occurred between normally growing cells and persister cells having reduced growth rates. Quantitative measurements led to a simple mathematical description of the persistence switch. Inherent heterogeneity of bacterial populations may be important in adaptation to fluctuating environments and in the persistence of bacterial infections.

Adaptation, Physiological↗
PubMed1971

Persistent cultural systems.

I have indicated here some features of a kind of entity which I have called a cultural identity system, and I have focused on a variety of this general type-the persistent system. In general terms it is best described as a system of beliefs and sentiments concerning historical events. I suggest using the term "a people" for the human beings who, at any given time, hold beliefs of this kind. These are phenomena with which we have been long familiar, but they have not been systematically studied by any but a few investigators. I have emphasized that a persistent system is a cumulative cultural phenomenon, an open-ended system that defines a course of action for the people believing in it. Such peoples are able to maintain continuity in their experience and their conception of themselves in a wide variety of sociocultural environments. I hold that certain kinds of identifiable conditions give rise to this type of cultural system. These may best be summarized as an oppositional process involving the interactions of individuals in the environment of a state or a similar large-scale organization. The oppositional process frequently produces intense collective consciousness and a high degree of internal solidarity. This is accompanied by a motivation for individuals to continue the kind of experience that is "stored" in the identity system in symbolic form. The persistent identity system is more stable as a cultural structure than are large-scale political organizations. When large-scale states disintegrate, they often appear to decompose into cultural systems of the persistent type. Large-scale organizations also give rise to the kind of environment that can result in the formation of new persistent systems. It is possible that, while being formed, states depend for their impetus on the accumulated energy of persistent peoples. A proposition for consideration is that states tend to dissipate the energy of peoples after transforming that energy into state-level integrations, and then regularly break down in the absence of mechanisms for maintaining human motivations in the large-scale organizations that they generate.

Anthropology, Cultural↗
PubMed1975

Distribution and persistence of Staphylococcus and Micrococcus species and other aerobic bacteria on human skin.

The districution of Staphylococcus and Micrococcus species and associated coryneform bacteria, Acinetobacter, Klebsiella, Enterobacter, Bacillus, and Streptomyces on skin was determined during October 1971 from samples collected on persons living in North Carolina and New Jersey. Persistence of these organisms on skin was estimated in temporal studies conducted during the period from June 1971 to June 1972 on persons living in North Carolina. Staphylococci and coryneforms were the most predominant and persistent bacteria isolated from the nares and axillae. Staphylococci, coryneforms, micrococci, and Bacillus were the most predominant and persistent bacteria isolated from the head, legs, and arms. Acinetobacters were most frequently isolated during the warmer months of the years. Staphylococcus aureus and S. epidermidis were the most predominant and persistent staphylococci isolated from the nares, whereas S. epidermidis and S. hominis were the most predominant and persistent staphylocicci isolated from the axillae, head, legs, and arms. S. capitis was often isolated from the head and arms and S. haemolyticus was often isolated from the head, legs, and arms. S. simulans, S. xylosus, S. cohnii, S. saprophyticus, S. warneri, and an unclassified coagulase-positive species were only occasionally isolated from skin. Micrococcus luteus was the most predominant and persistent Micrococcus isolated from skin and preferred regions of the head, legs, and arms. M. varians was the second most frequent Micrococcus isolated. M. lylae, M. sedentarius, M. roseus, M. kristinae, and M. nishinomiyaensis were only occasionally isolated from skin. M. lylae was most frequently isolated during the colder months of the years.

Acinetobacter↗
PubMed2006

Transcriptional response patterns of Chlamydophila psittaci in different in vitro models of persistent infection.

The obligatory intracellular bacterium Chlamydophila psittaci is the causative agent of psittacosis in birds and humans. The capability of this zoonotic pathogen to develop a persistent phase is likely to play a role in chronicity of infections, as well as in failure of antibiotic therapy and immunoprophylaxis. To elucidate three different in vitro models for transition of C. psittaci to persistence (iron depletion, penicillin G treatment, and gamma interferon [IFN-gamma] exposure), a set of 27 genes was examined by mRNA expression analysis using quantitative real-time PCR. While the phenotypical characteristics were the same as in other chlamydiae, i.e., aberrant morphology of reticulate bodies, loss of cultivability, and rescue of infectivity upon removal of inducers, the transcriptional response of C. psittaci to persistence-inducing factors included several new and distinctive features. Consistent downregulation of membrane proteins, chlamydial sigma factors, cell division protein, and reticulate body-elementary body differentiation proteins from 24 h postinfection onward proved to be a general feature of C. psittaci persistence. However, other genes displayed considerable variations in response patterns from one model to another, which suggests that there is no persistence model per se. In contrast to results for Chlamydia trachomatis, late shutdown of essential genes in C. psittaci was more comprehensive with IFN-gamma-induced persistence, which is probably due to the absence of a functional tryptophan synthesis operon.

Animals↗
PubMed1981

Attachment defect in mouse fibroblasts (L cells) persistently infected with Chlamydia psittaci.

Almost all the cells in populations of mouse fibroblasts (L cells) persistently infected with the 6BC strain of Chlamydia psittaci were immune to superinfection with high multiplicities of C. psittaci, whether or not the L cells contained visible chlamydial inclusions. As ascertained by experiments with 14C-labeled C. psittaci, immunity to superinfection resulted from the failure of added chlamydiae to attach to persistently infected host cells. However, when exogenous C. psittaci was introduced into persistently infected L cells by centrifuging the inoculum onto host cell monolayers or by pretreating the monolayers with diethylaminoethyl-dextran, these chlamydiae produced expected numbers of infectious progeny. Persistently infected L cells were associated in an unknown way with a C. psittaci population that entered the host cells only with the aid of centrifugation or pretreatment with diethylaminoethyl-dextran. Inclusion-free, persistently infected L cells appeared to present at least two separate hindrances to chlamydial activity: blockage of the attachment of exogenous elementary bodies to persistently infected host cells and prevention of the initiation of chlamydial multiplication by means of a normal developmental cycle in the absence of added C. psittaci.

Animals↗
PubMed1981

Characterization of herpes simplex virus persistence in a human T lymphoblastoid cell line.

Persistent, dynamic-state infection with herpes simplex virus (HSV) type 1 has been maintained in human T lymphoblastoid (CEM) cells for many months after initial infection with the wild-type virus (HSV0) (input virus/cell multiplicity of 1.0). Persistently infected cells grew as well as uninfected cells, except during occasional periods of crisis (increased viral replication and cytopathic effect). Cells could survive the crisis when they were maintained for twice the usual time interval (8 to 10 rather than 4 to 5 days) before subculture. Interferon was not detectable in the cultures. HSV0 was compared with HSVp1, a small plaque-forming isolate from persistently infected CEM cells. Primary infection of CEM cells with HSV0 at a low input multiplicity (0.01) led to abortive replication, whereas infection with HSVp1 at the same multiplicity resulted in either rapidly lytic or persistent infection depending upon the time interval of subculture. Approximately 55% of plaque-purified clones of HSVp1, as compared with only 5% of HSV0 clones, displayed temperature-sensitive growth in Vero cells. Defective interfering virus was not detectable in uncloned HSVp1 by interference assay. Persistently infected cultures "cured" by treatment with HSV antiserum or incubation at 39 degrees C were resistant to reinfection with HSV but permissive for vesicular stomatitis virus replication, suggesting that these treatments modulated a shift from the dynamic-state of the static-state, latent infection. These studies provide a model for characterization of HSV persistence and latency in a highly differentiated human cell line.

Antibodies, Viral↗
PubMed1983

Inhibition of onset of overt multiplication of Chlamydia psittaci in persistently infected mouse fibroblasts (L cells).

When monolayers of mouse fibroblasts (L cells) persistently infected with Chlamydia psittaci (strain 6BC) were dispersed in medium 199 and plated out in new flasks, the monolayers that grew out consisted almost exclusively of inclusion-free host cells that retained full resistance to superinfection with C. psittaci (covert infection). After a delay that was inversely proportional to the initial density of the newly transferred L cell population, the percentage of host cells containing visible chlamydial inclusions increased rapidly (overt infection), and most of the L cells were destroyed by extensive chlamydial multiplication (wipeout), leaving only a few survivors to start new persistently infected monolayers. When persistently infected L cell populations grown in medium 199 were transferred to Eagle minimal essential medium, the onset of overt multiplication was strongly suppressed although covert multiplication of C. psittaci continued unabated, as shown by host cell retention of resistance to superinfection and the prompt resumption of overt multiplication after transfer back into medium 199. The difference(s) between the two media responsible for the different expression of the persistently infected state was not determined. A single dose of 100 U of penicillin G per ml of medium 199 given at the time persistently infected monolayers were divided almost completely suppressed the appearance of visible signs of chlamydial infection for several weeks, although resistance to superinfection was retained at all times. The same amount of penicillin given 7 days after replating did not prevent the occurrence of the first expected wipeout, but there was a long period of inclusion-free L cell growth between the first wipeout and the second. It was concluded that covert multiplication of C. psittaci in persistently infected L cells may continue indefinitely without the appearance of visible signs of infection. The transition between covert and overt chlamydial multiplication appears to be a penicillin-sensitive, multistep process that is regulated, at least in part, by the host cell density and the composition of the growth medium.

Animals↗
PubMed1984

Acquired resistance to facultative intracellular bacteria: relationship between persistence, cross-reactivity at the T-cell level, and capacity to stimulate cellular immunity of different Listeria strains.

C57BL/6 mice were infected with different strains of Listeria sp., and bacterial survival in spleens was assessed. Six strains (EGD, NCTC 5348, ATCC 19113, ATCC 19114, NCTC 10527, and ATCC 19116) were able to persist in spleens (persistent strains), whereas with five other strains (ATCC 19111, ATCC 19119, ATCC 33090, ATCC 33091, and ATCC 14870), only few if any bacteria were demonstrable after infection with up to 10(8) organisms (nonpersistent strains). Immunization of mice with persistent listeriae induced strong immune responses as determined in vitro (antigen-induced proliferation and interleukin production) and in vivo (protection and delayed-type hypersensitivity), whereas immunization with nonpersistent bacteria resulted in weaker responses. On the other hand, T lymphocytes from mice immunized with live organisms of the persistent strain EGD were stimulated equally well by heat-killed listeriae of all strains. Furthermore, three T-cell clones which were able to adoptively mediate antibacterial protection in vivo could be stimulated by heat-killed organisms of persistent as well as nonpersistent Listeria strains. It is concluded that both persistent and nonpersistent listeriae express antigenic epitopes which are recognized by protective T cells, although nonpersistent strains are not effective in inducing cellular immune responses due to rapid elimination in the host.

Animals↗
PubMed1985

Persistent infection of L cells with an ovine abortion strain of Chlamydia psittaci.

L cells inoculated at multiplicities of infection greater than or equal to 1 inclusion-forming unit of the abortigenic chlamydial strain B577 were destroyed within 10 to 15 days. Upon continued incubation in fresh medium, a few surviving cells repopulated the flasks, and the reemerging cultures remained persistently infected. The persistent state was characterized by cycles of repopulation with a low ratio of infected cells and cycles of extensive cytopathic changes in which greater than 90% of the cells had chlamydial inclusions and which could be delayed or even terminated by penicillin treatment. Immunofluorescence and superinfection during the period of repopulation revealed that the persistently infected cells could adsorb chlamydiae but their multiplication was arrested. This nonpermissive state could be terminated by the specific action of cycloheximide. L cells spontaneously cured from a persistent infection exhibited no change in susceptibility to chlamydiae when compared with normal L cells. However, chlamydiae derived from L cells after 7.5 months of persistence destroyed L-cell monolayers more rapidly and at lower multiplicities of infection than the wild type. This state of chlamydia-host cell interaction could not be established with the arthropathogenic strain LW613 because chlamydial infectivity was lost after the first cytolytic burst of infection in the cell cultures. The persistence described for the strain B577-L-cell system appears to differ from previously described models involving other chlamydial strains.

Abortion, Septic↗
PubMed1998

Expression of Anaplasma marginale major surface protein 2 variants during persistent cyclic rickettsemia.

Anaplasma marginale is an intraerythrocytic rickettsial pathogen of cattle in which infection persists for the life of the animal. Persistent A. marginale infection is characterized by repetitive rickettsemic cycles which we hypothesize reflect emergence of A. marginale antigenic variants. In this study, we determined whether variants of major surface protein 2 (MSP-2), a target of protective immunity encoded by a polymorphic multigene family, arise during persistent rickettsemia. By using a quantitative competitive PCR to identify rickettsemic cycles, msp-2 transcripts expressed in vivo were isolated from peak rickettsemia of sequential cycles. Cloning and sequencing of msp-2 cDNA revealed that genetic variants of MSP-2 emerge representing a minimum of four genetic variant types in each cycle during persistent infection. Two-color immunofluorescence using variant-specific antibody showed that emergence of MSP-2 variants resulted in expression of a minimum of three antigenic types of MSP-2 within one rickettsemic cycle. Therefore immune control of each cycle would require responses to an antigenically diverse A. marginale population. These findings demonstrate that polymorphic MSP-2 variants emerge during cyclic rickettsemia in persistent A. marginale infection and suggest that emergent variants play an important role in persistence.

Amino Acid Sequence↗