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PubMed1994

Relationships between broodiness expression laying persistency and concentrations of hormones during the first productive period in turkey hens (Meleagris gallopavo).

The changes in egg production, in broodiness index and in plasma concentrations of LH, prolactin, oestradiol and progesterone were monitored throughout the first period of laying in turkey hens. The hens were subsequently classified according to their ability to express broodiness (33%) and their laying persistency; 25% were out-of-lay by the end of the experiment. A high percentage (67%) of the hens that went out-of-lay had previously been identified as broody. Altogether, a significant (p < 0.05) physiological stage effect was found when comparing prolactin, oestradiol and progesterone data obtained from short and long laying persistency hens and this stage effect was also significant for oestradiol and progesterone data obtained from broody and non-broody hens. Otherwise, plasma LH concentrations decreased slightly but significantly throughout the laying year in all hens but no significant differences between physiological states were observed, although the decrease was more pronounced in the hens that went out-of-lay. Plasma progesterone concentrations remained stable throughout in laying hens but decreased significantly in broody and/or out-of-lay hens. Plasma prolactin concentrations were maximal between the 5th and 12th week of egg production and the levels observed in laying hens that did not become broody or had a long laying persistency were twice those measured in broody and/or out-of-lay hens. In the meantime, plasma oestradiol concentrations were lower and stable in laying hens, whereas they were higher during the first half of the productive period in broody and short laying persistency hens. These results suggest that, under our experimental conditions, the hormonal profiles of prolactin and oestradiol for a given hen during the first 10 weeks of the laying cycle may provide predictive information for future changes in its physiological status. The inverse relationship that was observed here between high early plasma concentrations of oestradiol and laying persistency is original. In addition, the relationship between the ability to express broodiness and high and low early plasma concentrations of oestradiol and prolactin, respectively, in hens submitted to preventive broody treatment has not been reported previously. Furthermore, it seems clear that high initial concentrations in prolactin, far from exerting any deleterious effects on egg production are closely associated with a longer persistency of egg laying.

Animals↗
PubMed1994

Medical aspects of the persistent vegetative state (1).

This consensus statement of the Multi-Society Task Force summarizes current knowledge of the medical aspects of the persistent vegetative state in adults and children. The vegetative state is a clinical condition of complete unawareness of the self and the environment, accompanied by sleep-wake cycles, with either complete or partial preservation of hypothalamic and brain-stem autonomic functions. In addition, patients in a vegetative state show no evidence of sustained, reproducible, purposeful, or voluntary behavioral responses to visual, auditory, tactile, or noxious stimuli; show no evidence of language comprehension or expression; have bowel and bladder incontinence; and have variably preserved cranial-nerve and spinal reflexes. We define persistent vegetative state as a vegetative state present one month after acute traumatic or nontraumatic brain injury or lasting for at least one month in patients with degenerative or metabolic disorders or developmental malformations. The clinical course and outcome of a persistent vegetative state depend on its cause. Three categories of disorder can cause such a state: acute traumatic and non-traumatic brain injuries; degenerative and metabolic brain disorders, and severe congenital malformations of the nervous system. Recovery of consciousness from a posttraumatic persistent vegetative state is unlikely after 12 months in adults and children. Recovery from a nontraumatic persistent vegetative state after three months is exceedingly rare in both adults and children. Patients with degenerative or metabolic disorders or congenital malformations who remain in a persistent vegetative state for several months are unlikely to recover consciousness. The life span of adults and children in such a state is substantially reduced. For most such patients, life expectancy ranges from 2 to 5 years; survival beyond 10 years is unusual.

Coma↗
PubMed1992

Visible persistence is reduced by fixed-trajectory motion but not by random motion.

Despite the sluggish temporal response of the human visual system, moving objects appear clear and without blur, which suggests that visible persistence is reduced when objects move. It has been argued that spatiotemporal proximity alone can account for this modulation of visible persistence and that activation of a motion mechanism per se is not necessary. Experiments are reported which demonstrate that there is a motion-specific influence on visible persistence. Specifically, points moving in constant directions, or fixed trajectories, show less persistence than points moving with the same spatial and temporal displacements but taking random walks, randomly changing direction each frame. Subjects estimated the number of points present in the display for these two types of motion conditions. Under conditions chosen to produce 'good' apparent motion, ie small temporal and spatial increments, the apparent number of points for the fixed-trajectory condition was significantly lower than the apparent number in the random-walk condition. The traditional explanation of the suppression of persistence based on the spatiotemporal proximity of objects cannot account for these results. The enhanced suppression of persistence observed for a target moving in a consistent direction depends upon the activation of a directionally tuned motion mechanism extended over space and time.

Female↗
PubMed1982

Molecular comparison of delta beta-thalassemia and hereditary persistence of fetal hemoglobin DNAs: evidence of a regulatory area?

The hematological phenotypes of several Mediterranean patients with delta beta-thalassemia and hereditary persistence of fetal hemoglobin have been characterized. Although clinical and hematological characteristics are essentially superimposable in all heterozygous delta beta-thalassemics, these patients show typical G gamma/A gamma ratios in their Hb F, ranging from approximately 0.07 in Sardinian to approximately 0.15 in Sicilian and approximately 0.35 in Spanish patients. A gamma Sardinian-(isoleucine-75 leads to threonine) is found in Spanish patients and accounts for all of the A gamma production in heterozygotes, indicating that persistent production of gamma chains occurs cis to the delta beta-thalassemia gene. The molecular heterogeneity of these conditions is demonstrated by restriction enzyme mapping of DNA; Sicilian and Calabrian patients show a deletion starting from the delta-globin intron and extending several kilobases 3' to the beta-globin gene; in Spanish patients the deletion starts approximately 2-3 kilobases 5' to the delta-globin gene and extends well beyond the beta-globin gene. Comparison of these deletions with previously described ones in Negro and in a new Southern Italian case of hereditary persistence of fetal hemoglobin suggests that the deletion of a region centered at a cluster of repetitive sequences approximately 3.5 kilobases 5' to the delta-globin gene may be critical for the persistent expression of high levels of gamma-globin in hereditary persistence of fetal hemoglobin compared to delta beta-thalassemia. The concept that the deletion or mutation of specific areas (rather than nonspecific changes brought about by large deletions in the globin cluster) is important in determining the persistent expression of gamma-globin genes is supported by the finding of a nondeletion type of delta beta-thalassemia in Sardinians.

Chromosome Deletion↗
PubMed1984

Inhibition of opiate receptor-mediated signal transmission by rabies virus in persistently infected NG-108-15 mouse neuroblastoma-rat glioma hybrid cells.

Acute and persistent rabies virus infection of mouse neuroblastoma-rat glioma hybrid cells (NG-108-15) results in a loss of the normal inhibiting function of opiates via the opiate receptor on hormone-stimulated adenylate cyclase activity. Previous studies of these persistently infected cells have shown a decrease in the affinity of the opiate receptors for agonists without any change in the number of these receptors. We now demonstrate that persistently infected cells are unable to couple the opiate receptors to the inhibitory regulatory protein Ni of the adenylate cyclase, as measured by the loss of stimulation of the GTPase activity of this protein. However, the unstimulated basal GTPase activities of the regulatory components Ni and Ns are unchanged in the persistently infected cells. These studies also reveal a disorder of the stimulation of the adenylate cyclase by GTP or fluoride via the stimulating regulatory G/F protein (Ns) in persistently infected cells, whereas direct stimulation of the catalytic subunit of the adenylate cyclase by forskolin remains unchanged. Therefore, there are different points of dysfunction caused by the persistent rabies infection in the signal pathway from the opiate receptor to the adenylate cyclase and from the stimulating Ns protein to the enzyme: (i) opiate receptor binding is reduced by a decrease of agonist affinity (previously published data), (ii) the stimulation of GTPase activity of the inhibiting regulatory component Ni of the adenylate cyclase system is inhibited, and (iii) the signal pathway from the stimulating regulatory component of the adenylate cyclase system to the unchanged activity of the catalytic subunit is defective.

Adenylyl Cyclases↗
PubMed1994

Immediate early gene expression associated with the persistence of heterosynaptic long-term depression in the hippocampus.

Long-term depression (LTD) of synaptic efficacy is likely to be as important in memory processing as the more well-known long-term potentiation (LTP). The case for LTD serving as a memory mechanism, however, requires that it be shown to persist across days or weeks at least. Here we examined the persistence of heterosynaptic LTD in the medial and lateral perforant path inputs to the dentate gyrus in awake rats and correlated this persistence with the degree of immediate early gene expression as assessed immunohistochemically. Rats were chronically implanted with separate stimulating electrodes in the medial and lateral perforant paths and an extracellular field potential recording electrode in the dentate hilus. After recovery from surgery, either the medial or the lateral perforant path was tetanized with 400-Hz trains, and homosynaptic LTP and heterosynaptic LTD were followed across time. Heterosynaptic LTD was shown to occur readily in awake animals and to persist across days or weeks, depending on the stimulation protocol. The persistence of LTD and LTP was highly correlated within animals. Additional animals, given the same tetanization protocols, showed that the greatest immediate early gene expression occurred following that protocol which consistently gave the longest-lasting LTP and LTD. These data support the proposed role of LTD in memory processing but question whether immediate early genes are important for the persistence of LTP, LTD, or both.

Animals↗
PubMed1990

A voltage-dependent persistent sodium current in mammalian hippocampal neurons.

Currents generated by depolarizing voltage pulses were recorded in neurons from the pyramidal cell layer of the CA1 region of rat or guinea pig hippocampus with single electrode voltage-clamp or tight-seal whole-cell voltage-clamp techniques. In neurons in situ in slices, and in dissociated neurons, subtraction of currents generated by identical depolarizing voltage pulses before and after exposure to tetrodotoxin revealed a small, persistent current after the transient current. These currents could also be recorded directly in dissociated neurons in which other ionic currents were effectively suppressed. It was concluded that the persistent current was carried by sodium ions because it was blocked by TTX, decreased in amplitude when extracellular sodium concentration was reduced, and was not blocked by cadmium. The amplitude of the persistent sodium current varied with clamp potential, being detectable at potentials as negative as -70 mV and reaching a maximum at approximately -40 mV. The maximum amplitude at -40 mV in 21 cells in slices was -0.34 +/- 0.05 nA (mean +/- 1 SEM) and -0.21 +/- 0.05 nA in 10 dissociated neurons. Persistent sodium conductance increased sigmoidally with a potential between -70 and -30 mV and could be fitted with the Boltzmann equation, g = gmax/(1 + exp[(V' - V)/k)]). The average gmax was 7.8 +/- 1.1 nS in the 21 neurons in slices and 4.4 +/- 1.6 nS in the 10 dissociated cells that had lost their processes indicating that the channels responsible are probably most densely aggregated on or close to the soma. The half-maximum conductance occurred close to -50 mV, both in neurons in slices and in dissociated neurons, and the slope factor (k) was 5-9 mV. The persistent sodium current was much more resistant to inactivation by depolarization than the transient current and could be recorded at greater than 50% of its normal amplitude when the transient current was completely inactivated. Because the persistent sodium current activates at potentials close to the resting membrane potential and is very resistant to inactivation, it probably plays an important role in the repetitive firing of action potentials caused by prolonged depolarizations such as those that occur during barrages of synaptic inputs into these cells.

Action Potentials↗
PubMed1999

Class II HLA alleles and hepatitis B virus persistence in African Americans.

Persistence of hepatitis B virus (HBV) infection is likely due to the interplay of the virus and host immune response. Given its critical role in antigen presentation, allelic differences in the HLA complex may affect HBV persistence. In a prospectively followed African American cohort, molecular class I and class II HLA typing was done on 31 subjects with persistent HBV infection and 60 controls who cleared the infection. HBV persistence was significantly associated with two class II alleles, DQA1 *0501 (odds ratio [OR], 2.6; P=.05) and DQB1 *0301 (OR, 3.9; P=.01), the two-locus haplotype consisting of these same two alleles (OR, 3; P=. 005) and the three-locus haplotype, DQA1 *0501, DQB1 *0301, and DRB1 *1102 (OR, 10.7; P=.01). In addition, HBV persistence was associated with class II allelic homozygosity. Several class I associations with persistence were also noted but were not statistically significant after correction for multiple comparisons. These results underscore the importance of the class II-mediated immune response in recovery from HBV infection.

Adult↗
PubMed1993

Cell-mediated immune deficiency and malnutrition are independent risk factors for persistent diarrhea in Bangladeshi children.

A community-based longitudinal study was carried out at Matlab, Bangladesh, to investigate the magnitude of the problem of persistent diarrhea; 705 children aged < 5 y were followed, yielding 7300 child-months of observation in 1 y. Morbidity data were collected every fourth day by home visit, anthropometric status was determined monthly, and cell-mediated immune status was assessed every 3 mo. The incidence of persistent diarrhea was 34 episodes per 100 child-years; rates were highest in infancy and declined through the remainder of childhood. In a logistic-regression model, weight-for-height status and immune status were significant predictors of persistent diarrhea. Compared with those at zero Z score, children with weight-for-height at -2 would have a 3.5 times increased risk of persistent diarrhea. Compared with immunocompetent children, immunodeficient children had about twice the risk of developing persistent diarrhea. Thus, nutritional status and cell-mediated immune status were important independent risk factors for persistent diarrhea.

Bangladesh↗
PubMed1990

AZT demonstrates anti-HIV-1 activity in persistently infected cell lines: implications for combination chemotherapy and immunotherapy.

A sensitive and quantitative focal immunoassay has been used to measure the effects of three different therapeutic agents on tissue culture cells infected with human immunodeficiency virus (HIV). The effects of the drugs were studied on both acutely and persistently infected CD4+ cell lines. The three agents, azidothymidine (AZT), interferon-alpha (IFN-alpha), and an anti-HIV envelope antibody coupled to ricin A chain, were tested alone and in combination. AZT was found to have its greatest effect during early stages of the infection, but also had an action on persistently infected T cell lines. The effect of AZT on persistently infected cells was seen within 24 h, increased with extended exposure to the drug, and persisted after its removal. IFN-alpha had variable effects on acutely infected cells but suppressed chronic infection. Combinations of the therapeutic agents were studied. Using a model that allowed for treatment during both acute and persistent stages of infection, the most effective combination in suppressing HIV infection was the continual use of both AZT and IFN-alpha at the highest tolerable doses. Knowledge of the efficacy of AZT on persistently infected cells will allow for the most effective design of clinical protocols.

Cell Line↗
PubMed1994

Persistence of type-specific human papillomavirus infection among cytologically normal women.

Determinants of genital human papillomavirus (HPV) persistence in 393 women initially cytologically normal were investigated by testing them for HPV DNA twice over a median interval of 14.9 months. At each visit, interview information was obtained and a cervicovaginal lavage sample was collected for polymerase chain reaction-based HPV testing. Twenty-six percent of the women were HPV-positive at the first sampling. Data on HPV type was available for 86 HPV-positive women (84%); 35 of these women (41%) had persistent type-specific HPV detection. Persistence decreased with time between samplings. Women aged > or = 30 years had a higher percentage of persistence (65%) than those < or = 24 years (32%, P = .02). The percentage of persistence was higher among women infected with HPV types known to be cancer-associated (45%) than among those infected with other types (24%, P = .11). These findings were independent of each other and of timing between samplings. Although based on a prevalent cohort, these results are concordant with previous suggestions that HPV infection is usually transient and that cervical cancer may arise from within the subset of women with persistent HPV infection.

Adolescent↗
PubMed1991

Epidemiologic, clinical, and laboratory characteristics of acute vs. persistent diarrhea in periurban Lima, Peru.

Longitudinal studies of acute and persistent diarrhea in 677 children less than 3 years old were conducted for 27 months in an underprivileged, periurban community near Lima, Peru. Incidence rates and accurate durations of diarrhea were obtained by twice-weekly community-based surveillance and clinical and laboratory features of diarrheal episodes were documented. Study children had an overall incidence of diarrhea of 8.1 episodes per child-year and an incidence of persistent (greater than 14 days) diarrhea of 0.25 episodes per child-year. Episodes of longer duration were associated with young age (0-5 months) and more severe illness (greater than or equal to 6 diarrheal stools per day) in the first week. None of the laboratory tests performed in the first week of illness (fecal leukocytes, blood, reducing substances, pH, or fat) proved of value to identify episodes that would become persistent. Although steatorrhea was commonly present in the acute phase of the illness, it became less frequent by the third or subsequent week of illness in the persistent diarrheas. These results suggest that there are no clinical or laboratory features of acute diarrhea that are strongly predictive of the subset of diarrheas that persist. Thus, it is important that all diarrheal episodes should have appropriate fluid and dietary management and follow-up to detect the persistent diarrheas that may need special intervention.

Acute Disease↗
PubMed1999

Persisting dysphagia after uvulopalatoplasty performed with steel scalpel.

OBJECTIVES/HYPOTHESIS: The aim of the present study was to determine the incidence of postoperative persisting dysphagia after uvulopalatoplasty performed with conventional steel scalpel (UPP) and to videoradiographically evaluate the oral and pharyngeal phases of swallowing in patients reporting persisting dysphagia. The hypothesis to be tested was that patients treated with UPP would demonstrate a lower incidence of persisting dysphagia than previously found after uvulopalatoplasty performed with laser technique (LUPP). STUDY DESIGN: Retrospective. METHODS: Sixty-eight of 76 consecutive patients treated with UPP answered a questionnaire concerning outcome and late complications after the operation. The patients who reported postoperative dysphagia were additionally interviewed at a minimum of 1 year postoperatively, and the oral and pharyngeal phases of swallowing were videoradiographically examined in those with persisting dysphagia. RESULTS: The incidence of persisting dysphagia after UPP was 29%. Videoradiographically 71% of the dysphagic patients showed a deviant pharyngeal swallowing pattern. CONCLUSION: The incidence of persisting dysphagia after UPP did not differ from that reported after laser uvulopalatoplasty. Dysphagia after UPP was mostly associated with videoradiographic signs of deviant pharyngeal swallowing function. Patients should be informed that there is a risk of developing dysphagia after uvulopalatoplasty.

Adult↗
PubMed1997

Carotid endarterectomy in the presence of a persistent hypoglossal artery: case report.

OBJECTIVE AND IMPORTANCE: A persistent hypoglossal artery, one of the embryonic carotid-basilar anastomoses that can fail to regress in the embryo and can be observed past birth, is one of the only congenital anatomic variations of the internal carotid artery (ICA) that can complicate the performance of carotid endarterectomy. When associated with atherosclerotic carotid artery disease, the recognition and intraoperative management of a persistent hypoglossal artery is important. CLINICAL PRESENTATION: A 72-year-old man presented with a symptom of transient right hemisphere ischemia, and although ultrasonography indicated a right ICA stenosis (and no other abnormality), angiography also demonstrated that the atherosclerotic plaque extended into the origin of a large right persistent hypoglossal artery arising 1.5 cm from the origin of the ICA. In this patient, the persistent hypoglossal artery was the only arterial supply to the basilar artery. INTERVENTION: The patient underwent a right ICA endarterectomy, and intraoperative angiography was necessary to ensure that the persistent hypoglossal artery was the vessel shunted during the arterial repair. CONCLUSION: Recognition of the primitive carotid-basilar anastomoses is important to surgeons who perform carotid endarterectomy and is not possible with ultrasonography alone. Intraoperative angiography enables the surgeon to accurately catheterize a persistent hypoglossal artery with a carotid shunt.

Basilar Artery↗
PubMed1976

Persistent herpes simplex virus infections established in two Burkitt lymphoma derived cell lines.

Examination of P3HR-I cells (Epstein-Barr virus [EBV] producer) persistently infected with the MAL strain of herpes simplex virus type I (HSV-I) suggested that only a few cells were actively producing a virus indistinguishable from HSV-I (MAL) despite the presence of immunofluorescent HSV-I antigens associated with the majority of cells. EBV-specific immunofluorescence was not altered in HSV-I persistently infected P3HR-I cells. HSV-I persistently infected cells, labelled for 72 h with 14C-thymidine, incorporated approx. 8% of the label into cell associated HSV-I DNA as resolved by caesium chloride gradients. Values greater than 8% of the total were suggested by hybridization of gradient fractions with 3H-HSV-I DNA. To determine whether the establishment of HSV persistent infections in Burkitt lymphoma derived cells was a general phenomenon, six strains of HSV-I (MAL, KOS, Patton, Syn R, BF and SYN V) and two strains of type 2 (333 and MS) were used to infect the P3HR-I and Raji (EBV non-producer) cell lines derived from Burkitt lymphomas. In P3HR-I cells, persistent infections were established with all strains of HSV-I but not with HSV-2. In Raji cells, persistent infections were established with all strains of HSV-I, except Syn V, and with both strains of HSV-2. No external support was required to maintain these infections.

Adsorption↗
PubMed1980

Persistent Theiler's murine encephalomyelitis virus infection in mice depends on plaque size.

Theiler's murine encephalomyelitis virus (TMEV) is an enteric pathogen of mice which causes acute and chronic neurological disorders in the natural host. When brain-derived stocks of TMEV isolates are adapted to cell culture they predominantly form either large or small plaques. In this study the type of central nervous system (CNS) infection (acute versus chronic) and the associated disease occurring in mice inoculated intracerebrally with large and small plaque strains of TMEV was investigated. Large and small plaque strains of TMEV were found to vary in virulence, type of neurological disease produced and ability to establish persistent CNS infection in mice. Two large plaque strains, GDVII and FA viruses, were highly virulent, produced acute encephalitis, but were cleared from the nervous systems of surviving animals. Therefore, it appears that these large plaque variants do not cause persistent CNS infection in mice. In contrast, five small plaque strains, DA, WW, TO4, Yale and BeAn8386 viruses, were relatively avirulent, usually produced no illness during the first month after inoculation, but readily established persistent CNS infection in mice. Persistently infected mice later developed demyelinating disease. Having identified strains of TMEV that differ regarding their ability to persist, we now hope to be able to exploit this difference in elucidating the basic mechanism(s) of TMEV persistence.

Animals↗
PubMed1981

Establishment of persistent infection in mouse cells by Sindbis virus and its temperature-sensitive mutants.

The ability of wild-type (wt) Sindbis virus and six temperature-sensitive (ts) mutants to establish persistent infection in mouse L cells and a line of mouse embryo (ME) cells was determined. The wt established persistent infection in both ME cells and L cells at 39 degrees C. At 30 degrees C the wt established persistent infection in L cells but not ME cells, which did not recover from the initial infection. For the ts mutants, both cell lines survived the initial infection at 39 degrees C (the restrictive temperature) but the virus was eventually eliminated. At 30 degrees C (the permissive temperature) in L cells all mutants established persistent infection. In ME cells at 30 degrees C, RNA- mutants (unable to synthesize virus-specified RNA at 39 degrees C) established persistent infection whereas the cells did not recover from infection with RNA+ mutants (able to synthesize virus-specified RNA at 39 degrees C). The wt virus was less cytopathic in L cells than in BHK or ME cells. Interferon was produced by both L and ME cells at 30 degrees C and 39 degrees C, but its activity could not be detected in either cell line at 30 degrees C. It is proposed that establishment of persistent infection is dependent on reduced cytopathogenicity in the early stage of infection, and that further evolution of the virus then occurs to a less cytopathic form. Elimination of the virus at 39 degrees C is probably due to the action of interferon.

Animals↗
PubMed1981

Persistent infection of Vero cells with Tacaribe virus.

Persistently infected cultures have been established from Vero cells surviving primary infection with Tacaribe virus (Vero-T). The growth rate and morphological characteristics of the persistently infected cells were indistinguishable from normal Vero cells. Virus release declined during the first 6 passages, a cyclical pattern was observed between passages 6 and 16, and subsequently no virus infectivity could be detected. Co-cultivation with normal RK-13 or Vero cells enhanced virus yield from virus-producing cultures of Vero-T cells (passage 15), but the addition of susceptible cells had no effect on non-producer Vero-T cultures (passage 19). Only a small proportion (less than 1%) of the persistently infected cells tested during the first 16 passages produced infectious virus. The virus released during the early stages of persistence was temperature-sensitive if grown at 40 degree C, more thermolabile at 50 degree C than parental virus, and unable to initiate a persistent infection in Vero cells. Vero-T cells consistently showed refractoriness to homotypic Tacaribe virus superinfection and a selective graded resistance to other arenavirus replication. The possible use of viral susceptibility of persistently infected cultures as marker of antigenic relationship among Tacaribe complex viruses if considered.

Animals↗