Level of vigilance influences licking frequency in rats

In rats, the basic licking rhythm is generated by the central pattern generator located in the brainstem. Nevertheless, the licking frequency can be regulated between about 7.5 and 4 Hz by changing the drinking conditions. If these conditions are kept constant, the licking frequency can be influenced only to a minor degree by factors such as deprivation level, type of solution, and phase of the session. The aim of our study was to compare the licking frequency of rats at different levels of vigilance. We investigated spontaneous licking of rats by an electrical lick sensor; parallel behavior monitoring was also performed. Animals kept in a stable environment and showing a lower level of vigilance licked at a rate of 5.96 Hz, fully vigilant rats licked significantly more rapidly at a frequency 6.57 Hz. The fastest rate of licking (6.49 Hz and 6.82 Hz, respectively) was encountered in alert rats under a mild stress caused by the presence of a second animal in the experimental box. The vigilance level is thus another factor affecting the licking rate of rats that should be taken into account in behavioral licking experiments.     

Anxiolytic effects of progesterone are sexually dimorphic

We evaluated the effects of progesterone administration to estrogen-primed rats on licking behavior during a lick suppression test. This test assesses the behavior of water-deprived rats to lick a drinking tube for water reinforcement that is paired to electric shock. Chlordiazepoxide (a commonly used tranquilizer) is very effective in increasing licking during this test. Normal females and neonatally castrated males displayed an increase in shock-punished responses in tests conducted after hormone injections. Normal males and neonatally androgenized females were unaffected. Our results suggest that ovarian steroids, and particularly progesterone, can modulate anxiety in females and feminized males. In addition, the anxiolytic effect of progesterone appears to be mediated by a mechanism different from that of Chlordiazepoxide.     

Pharmacological control of the immune response by blockade of the early hormonal changes following antigen injection.

Antigen injection into mice induces a rapid increase in blood levels of gonadotropins. Suppression of these hormonal changes by a combination of drugs acting on the neuroendocrine regulation as well as on cell membrane receptors results in a blockade of antibody synthesis and specific “tolerance.” In addition, remarkable suppression of transplantation immunity is achieved.     

Disturbance of motivated behavior in rats by epileptic afterdischarges

Nearly all epileptic seizures in patients are characterized by deranged consciousness. We started to study changes in motivated behavior (drinking in thirsty rats) as a possible analogue of compromised consciousness during and after epileptic seizures. Epileptic afterdischarges (ADs) were elicited by stimulation of the dorsal hippocampus and/or thalamus. Rats with implanted electrodes (deprived of water for 24 hours) were trained to lick water from a narrow tube. After pretraining ADs were elicited eight times in each animal and access to water was allowed during different phases of the AD. Stimulation did not affect licking if no AD was induced. If stimulation was successful, licking was stopped in nearly 70 % of stimulations and modified (biting the tube) in 30 %. Hippocampal ADs (characterized by serrated waves in the EEG and by an arrest of behavior with subsequent automatisms) completely blocked licking, signs of recovery appeared during the interval between the AD and recurrent AD and it progressed during recurrent ADs. Thalamic ADs abolished licking in 82% of cases and immediately after ADs normal licking reappeared in 49 % of these observations. Our results suggest that changes in motivated behavior might serve as an analogue of compromised human consciousness.     

Disruptive effects of lateral hypothalamic stimulation on the lick-interrupt cycle in rats

Consummatory licking at a water spout was compared with licking at a dry spout maintained by electrical hypothalamic stimulation in the same rats. Both forms of licking, recorded photoelectrically, were maintained on a fixed ratio 8 schedule. Duration of reinforcement delivery was equated [300 ms]. A computer analysis of the temporal distribution of licks in each 1024 ms period from onset of reinforcement revealed that lateral hypothalamic stimulation decreased the occurrence of licking and disrupted the normally synchronous pattern of this behaviour. An analysis of the effects of delivering lateral hypothalamic stimulation contingent on water-maintained licking revealed that this effect of stimulation was clearly current-dependent. It is proposed that differences in licking rates maintained by water and by electrical hypothalamic stimulation, respectively, are due to response interference in the latter case. This interference effect is also proposed to be a major factor underlying higher reward thresholds for self-stimulation when licking is the operant response.     

Age-Related Differences in the Accuracy of Web Query-Based Predictions of Influenza-Like Illness

BackgroundWeb queries are now widely used for modeling, nowcasting and forecasting influenza-like illness (ILI). However, given that ILI attack rates vary significantly across ages, in terms of both magnitude and timing, little is known about whether the association between ILI morbidity and ILI-related queries is comparable across different age-groups. The present study aimed to investigate features of the association between ILI morbidity and ILI-related query volume from the perspective of age.MethodsSince Google Flu Trends is unavailable in Italy, Google Trends was used to identify entry terms that correlated highly with official ILI surveillance data. All-age and age-class-specific modeling was performed by means of linear models with generalized least-square estimation. Hold-out validation was used to quantify prediction accuracy. For purposes of comparison, predictions generated by exponential smoothing were computed.ResultsFive search terms showed high correlation coefficients of > .6. In comparison with exponential smoothing, the all-age query-based model correctly predicted the peak time and yielded a higher correlation coefficient with observed ILI morbidity (.978 vs. .929). However, query-based prediction of ILI morbidity was associated with a greater error. Age-class-specific query-based models varied significantly in terms of prediction accuracy. In the 0–4 and 25–44-year age-groups, these did well and outperformed exponential smoothing predictions; in the 15–24 and ≥ 65-year age-classes, however, the query-based models were inaccurate and highly overestimated peak height. In all but one age-class, peak timing predicted by the query-based models coincided with observed timing.ConclusionsThe accuracy of web query-based models in predicting ILI morbidity rates could differ among ages. Greater age-specific detail may be useful in flu query-based studies in order to account for age-specific features of the epidemiology of ILI.     

Dynamics and Variability of Early Morphogenesis in the Loach according to Observations of Individual Developmental Trajectories

The dynamics and variability of quantitative morphological characters (morphological variables), which undergo changes upon epiboly, were studied by means of vital observations and measurements of developing loach (Misgurnus fossilis L.) embryos within equal time intervals. None of morphological variables, which characterize the dynamics of blastoderm shape, had monotonous dependence on time. In each individual embryo, the intervals of changes in morphological variables in the “normal” direction corresponding to the change of their mean values during the normal course of epiboly alternated with arrests, as well as with the changes of morphological variables in the reverse direction. The dynamics of morphological variables in time, which reflect the sequence of morphological states of the same embryo, and those of individual variations (variations of morphological states of different embryos on the same temporal section) had identical structure. This suggests instability of individual trajectories of morphogenesis or, strictly speaking, their actual absence. It was shown for the first time on the basis of analysis of individual trajectories of morphogenesis that its dynamics corresponded to so-called “determined chaos,” which was previously discussed only as a theoretical possibility. The data obtained suggest that upon approach to the equatorial area of the embryo, the blastoderm marginal zone was elongated in the longitudinal direction and contracted across the axis of its movement. As a result, a positive feedback arises between the cooperated cell movement and the change of shape of the surface, over which the cells move. This leads, due to unstable radial symmetry of this movement, to the formation of embryonic shield.__________Translated from Ontogenez, Vol. 36, No. 3, 2005, pp. 211–221.Original Russian Text Copyright © 2005 by Cherdantsev, Tsvetkova.     

Excessive habit formation in schedule‐induced polydipsia: Microstructural analysis of licking among rat strains and involvement of the orbitofrontal cortex

Schedule‐induced polydipsia (SIP) is an animal model of compulsive drinking that selects for individual differences and varies across rat strains. The aim of this study was to investigate excessive habit formation by analyzing the SIP licking microstructure among rat strains, and to compare the brain areas activated by SIP in different populations. Wistar, Long Evans and Roman High‐ and Low‐Avoidance rat strains were compared using a cluster analysis of 2 main variables, that is, frequency of licking (percentage of interpellet intervals with drinking episodes) and intensity of licking (mean number of licks per interpellet interval), and were found to exhibit high intensity and frequent licking (compulsive drinkers, CD), low intensity but frequent licking (habitual drinkers, HD), and low intensity and low‐frequency licking (low drinkers, LD). The Wistar strain showed a higher frequency and intensity of licking, and had the largest group of CD rats when compared with the other strains. Regarding the acquisition of SIP, CD rats showed a higher intensity of licking when compared with the HD and LD rats. Moreover, c‐Fos quantification revealed that rats in the CD group showed hyperactivity in the lateral orbitofrontal cortex and basolateral amygdala when compared with the LD group. Analyzing the SIP microstructure could be a valuable tool for understanding the role of excessive habit formation in the development of compulsive drinking and its underpinning neurobiological mechanisms.     

Comparing Observed with Predicted Weekly Influenza-Like Illness Rates during the Winter Holiday Break,United States, 2004-2013

In the United States, influenza season typically begins in October or November, peaks in February, and tapers off in April. During the winter holiday break, from the end of December to the beginning of January, changes in social mixing patterns, healthcare-seeking behaviors, and surveillance reporting could affect influenza-like illness (ILI) rates. We compared predicted with observed weekly ILI to examine trends around the winter break period. We examined weekly rates of ILI by region in the United States from influenza season 2003–2004 to 2012–2013. We compared observed and predicted ILI rates from week 44 to week 8 of each influenza season using the auto-regressive integrated moving average (ARIMA) method. Of 1,530 region, week, and year combinations, 64 observed ILI rates were significantly higher than predicted by the model. Of these, 21 occurred during the typical winter holiday break period (weeks 51–52); 12 occurred during influenza season 2012–2013. There were 46 observed ILI rates that were significantly lower than predicted. Of these, 16 occurred after the typical holiday break during week 1, eight of which occurred during season 2012–2013. Of 90 (10 HHS regions x 9 seasons) predictions during the peak week, 78 predicted ILI rates were lower than observed. Out of 73 predictions for the post-peak week, 62 ILI rates were higher than observed. There were 53 out of 73 models that had lower peak and higher post-peak predicted ILI rates than were actually observed. While most regions had ILI rates higher than predicted during winter holiday break and lower than predicted after the break during the 2012–2013 season, overall there was not a consistent relationship between observed and predicted ILI around the winter holiday break during the other influenza seasons.     

Interdependence between neuroendocrine programming and the generation of immune recognition in ontogeny

Sequential, chronologically, and quantitatively critical inoculation of different allogeneic hybrid cells into mice during the neonatal and perinatal period results in an indefinite prolongation of the perinatal stage during which tolerance can be readily induced. Consequently, a permanent specific tolerance to the sequentially inoculated alloantigens and a parallel alteration and retardation in the maturation of the developing endocrine system which normally controls immune differentiation are observed. The endocrine and immune parameters are altered only when the successive presentation of alloantigens is begun at birth, as this is a critical stage of development at which both the neuroendocrine (hypothalamic-pituitary) and the thymo-lymphatic systems are still highly undifferentiated. The phylogenetically and ontogenetically interlocked and interdependent thymo-lymphatic and neuroendocrine networks thus constitute a basic homoeostatic regulatory system in which signals of both endocrine and antigenic nature are detected and elaborated with consequent proper response in a homeostatic fashion. On the basis of these considerations and the experimental findings that support them, the generation of tolerance and immunity (recognition of self and nonself components of the body) appears to be a part of the definitive brain programming for neuroendocrine and immune functions in early ontogey. This would constitute an augmented interpretation of the concept of immune tolerance as “specific central failure of the mechanisms of response” originally put forth by Medawar (1956, Proc. Roy. Soc.146B, 1).     

Synaptonemal complex karyotyping in spermatocytes of the Chinese hamster (Cricetulus griseus)

Relative length is a constant and distinctive characteristic for each autosomal SC, despite variations in absolute length from cell to cell. Arm ratio is distinctive for each SC except for two of the three sub-acrocentrics, and serves, together with relative length, for identification. The constancy of relative length and arm ratios indicates biological stability and lack of physical distortion in these spread preparations. There is a 11 relationship between relative lengths of autosomal SCs and mitotic autosomes; their arm ratios are also similar. These close parallels provide strikingly similar SC and somatic karyotypes. Variability was observed in sub-acrocentric arm ratios and in lengths of unpaired X and Y axes, correlated with the presence of constitutive heterochromatin. — Utilizing progressive differentiations of the X and Y chromosomes for staging, it is demonstrated that autosomal SCs decrease in length from late zygotene to mid-pachytene, and then increase at late pachytene. Within a nucleus, synchrony of length changes is maintained. It is concluded that the factors governing autosomal SC length are regular for any given bivalent from cell to cell, and may be related to those that control somatic autosome length relationships. — The X and Y axes differ quantitatively as well as qualitatively from autosomal SCs. The SC portion of the X and Y is constant in length through most of pachytene; the unpaired axes shorten and lengthen, but not in proportion to autosomal SCs. X and Y relative lengths and arm ratios vary throughout pachytene and do not maintain proportionality with somatic values. The evidence suggests, but does not prove, that the long arm of the X is paired with the short arm of the Y. — Twists occur in autosomal SCs at increasing frequencies throughout pachytene but cannot account for length changes. The number of twists per SC is directly proportional to SC length. Intertwining of SCs is random and proportional to SC length. End-to-end associations of autosomal SCs appear to be random; however, the ends of the X and Y are less often involved in such connections. — The length of axial material in all chromosomes at pachytene, expressed as an equivalent length of DNA double helix, represents 0.013% of the diploid DNA complement.     

Phase diagram of lipid A from Salmonella minnesota and Escherichia coli rough mutant lipopolysaccharide

We have reported here on the structural polymorphism of lipid A, the “endotoxic principle” of bacterial lipopolysaccharide. For lipid A of rough mutant lipopolysaccharide from Salmonella minnesota and Escherichia coli, the three-dimensional supramolecular structures were determined with x-ray diffraction utilizing synchrotron radiation. The investigations were performed in the water concentration range 10 to 95% by weight, at [lipid A]:[Mg²⁺] molar ratios from 1:0 to 0.1:1, and in the temperature range from 20 to 70°C. These data were correlated with measurements of the β→α phase behaviour which was monitored with differential scanning calorimetry and Fourier-transform infrared spectroscopy. We found that the transition temperature of the acyl chains ranges—in the absence of Mg²⁺—from 45°C at high to 56°C at low water content, and—at an equimolar content of Mg²⁺—from 52°C at high to 59°C at low water concentrations. In the gel phase—in which the lipid A acyl chains are more disordered than those from saturated phospholipids—cubic phases are adopted at high water content (>60%) and at high [lipid A):[Mg²⁺] molar ratios. At low water contents, lamellar states are assumed exclusively. In the liquid crystalline state of lipid A, the hexagonal H_II, state is adopted under all conditions. The structural variability of lipid A is highest at high water concentrations, and structural changes may be induced by only slight changes in temperature, water content, and Mg²⁺ concentration. Under physiological conditions, however, the lipid A assemblies exhibit a strong preference to cubic structures.     

Production of antisera specific to aldosterone: effect of hapten density and of carrier proteins

In order to investigate the influence of hapten density and of carrier proteins on the immunological characteristics of antisera, 4 groups of rabbits were injected with different aldosterone-carboxymethoxime protein conjugates. Six animals immunized with an aldosterone rabbit serum albumin (RSA) conjugate carrying 15 steroid molecules (RSA-2 conjugate) showed markedly higher antibody titers than rabbits injected with a RSA conjugate carrying 8 aldosterone molecules (RSA-1 conjugate). Low antibody titers were found in 8 animals immunized with an aldosterone bovine gamma globulin (BGG) conjugate showing a molar incorporation of 15. In a group of rabbits which was first injected with the RSA-1 conjugate and re-immunized with the RSA-2 conjugate the magnitude of antibody production was not enhanced. No differences in antibody sensitivity or specificity were observed between the 4 groups. It was concluded from these experiments a) that the density of haptenic groups depending on the molar incorporation of haptens and on the molecular weight of the carrier protein had influenced the magnitude of antibody production, b) that hapten density or carrier proteins had no effect on antibody sensitivity or specificity, c) that the magnitude of antibody production cannot be altered by re-immunizing with a more potent antigen.     

On the reversibility of the B1 2r−B1 2s couple in cobalamins

The cobalt(II)—cobalt(I) interconversion in a number of vitamin B_{1 2} derivatives was investigated by cyclic voltammetry. Particular attention was focused on the factors determining whether the interconversion is reversible. When the lower axial coordination position is occupied by a strong ligand, such as the benzimidazole nucleotide in “base on” cobalamins, the cobalt(II)—cobalt(I) interconversion is irreversible due to a slow reduction of the cobalt(II). However, when the lower axial coordination position is free of a strong ligand, as in most cobinamides or in “base off” cobalamins, the cobalt(II)—cobalt(I) interconversion is nearly perfectly reversible. Possible implications of the observations to B_{1 2}-dependent enzymes are briefly discussed.     

A High Throughput In Vivo Assay for Taste Quality and Palatability

Taste quality and palatability are two of the most important properties measured in the evaluation of taste stimuli. Human panels can report both aspects, but are of limited experimental flexibility and throughput capacity. Relatively efficient animal models for taste evaluation have been developed, but each of them is designed to measure either taste quality or palatability as independent experimental endpoints. We present here a new apparatus and method for high throughput quantification of both taste quality and palatability using rats in an operant taste discrimination paradigm. Cohorts of four rats were trained in a modified operant chamber to sample taste stimuli by licking solutions from a 96-well plate that moved in a randomized pattern beneath the chamber floor. As a rat’s tongue entered the well it disrupted a laser beam projecting across the top of the 96-well plate, consequently producing two retractable levers that operated a pellet dispenser. The taste of sucrose was associated with food reinforcement by presses on a sucrose-designated lever, whereas the taste of water and other basic tastes were associated with the alternative lever. Each disruption of the laser was counted as a lick. Using this procedure, rats were trained to discriminate 100 mM sucrose from water, quinine, citric acid, and NaCl with 90-100% accuracy. Palatability was determined by the number of licks per trial and, due to intermediate rates of licking for water, was quantifiable along the entire spectrum of appetitiveness to aversiveness. All 96 samples were evaluated within 90 minute test sessions with no evidence of desensitization or fatigue. The technology is capable of generating multiple concentration–response functions within a single session, is suitable for in vivo primary screening of tastant libraries, and potentially can be used to evaluate stimuli for any taste system.     

An albumin–butyrylcholinesterase for cocaine toxicity and addiction: Catalytic and pharmacokinetic properties

Butyrylcholinesterase (BChE, EC 3.1.1.8) is important in human cocaine metabolism despite its limited ability to hydrolyze this drug. Efforts to improve the catalytic efficiency of this enzyme have led to a quadruple mutant cocaine hydrolase, “CocH”, that in animal models of addiction appears promising for treatment of overdose and relapse. We incorporated the CocH mutations into a BChE–albumin fusion protein, “Albu-CocH”, and evaluated the pharmacokinetics of the enzyme after i.v. injection in rats. As assessed from the time course of cocaine hydrolyzing activity in plasma, Albu-CocH redistributed into extracellular fluid (16% of estimated total body water) with a t_1/2 of 0.66 h and it underwent elimination with a t_1/2 of 8 h. These results indicate that the enzyme has ample stability for short-term applications and may be suitable for longer-term treatment as well. Present data also confirm the markedly enhanced power of Albu-CocH for cocaine hydrolysis and they support the view that Albu-CocH might prove valuable in treating phenomena associated with cocaine abuse.     

Directed evolution of the lambda receptor of Escherichia coli through affinity chromatographic selection

Two low-resolution three-dimensional maps of the structure of crystalline ribosomes from the oocytes of the lizard, Lacerta sicula, have been obtained by electron microscopy and image processing. One map, derived from sheets contrasted with gold-thioglucose, shows the whole ribosome in outline. The other map, based on sheets embedded in glucose, shows predominantly the RNA in the ribosome.The distribution of RNA-rich and protein-rich regions within the ribosome was assessed by comparing both maps. The RNA forms a dense central core, while the ribosomal protein is located mainly at the periphery and constitutes most of the ribosome surface. The RNA appears to be accessible at several sites on the surface. The two subunits of the ribosome are not resolved, indicating that they are in close contact with one another. The subunit interface cuts through a region of the ribosome that is particularly rich in RNA.     

The effects of adrenalectomy and corticosterone replacement on induction of maternal behavior in the virgin female rat

Maternal behavior of the sensitized virgin rat is affected by approach-avoidance systems as well as by hypothalamic-pituitary-adrenal (HPA) axis, which is also activated during stress. The present experiments investigated the effects of adrenalectomy and of varying corticosterone concentrations on the onset and expression of maternal behavior in sensitized virgin rats. In the first experiment, latency to onset of maternal behavior and time spent licking once maternal were positively related to endogenous levels of corticosterone. However, few rats showed licking. In the second experiment, virgin rats were adrenalectomized or given sham surgeries before being sensitized and being given 0, 25, 100, 300, or 500 microg/mL of corticosterone in their drinking water. In the third experiment, virgin rats were adrenalectomized or given sham surgeries and given either control or corticosterone time-release pellets after being sensitized. Maternal behavior was then tested. Adrenalectomy increased licking in the second experiment and time over pups in the third experiment. Corticosterone replacement reduced licking in the second experiment and both licking and time over pups in the third experiment. In conclusion, exogenous corticosterone had an inhibitory effect on the expression of maternal behavior in the sensitized virgin rat, unlike the facilitatory effect previously found in the postpartum rat.     

Wikipedia Usage Estimates Prevalence of Influenza-Like Illness in the United States in Near Real-Time

Circulating levels of both seasonal and pandemic influenza require constant surveillance to ensure the health and safety of the population. While up-to-date information is critical, traditional surveillance systems can have data availability lags of up to two weeks. We introduce a novel method of estimating, in near-real time, the level of influenza-like illness (ILI) in the United States (US) by monitoring the rate of particular Wikipedia article views on a daily basis. We calculated the number of times certain influenza- or health-related Wikipedia articles were accessed each day between December 2007 and August 2013 and compared these data to official ILI activity levels provided by the Centers for Disease Control and Prevention (CDC). We developed a Poisson model that accurately estimates the level of ILI activity in the American population, up to two weeks ahead of the CDC, with an absolute average difference between the two estimates of just 0.27% over 294 weeks of data. Wikipedia-derived ILI models performed well through both abnormally high media coverage events (such as during the 2009 H1N1 pandemic) as well as unusually severe influenza seasons (such as the 2012–2013 influenza season). Wikipedia usage accurately estimated the week of peak ILI activity 17% more often than Google Flu Trends data and was often more accurate in its measure of ILI intensity. With further study, this method could potentially be implemented for continuous monitoring of ILI activity in the US and to provide support for traditional influenza surveillance tools.     

Ingestive Pattern Changes in Blinded Rats

Eating and drinking patterns were examined in intact and blinded adult male Sprague-Dawley rats fed a choice among isocaloric casein, sucrose/dextrin, and vegetable shortening/soybean oil diets. Weekly mean intake of all nutrients was altered in blinded rats, with increased lipid intake and decreased water intake in rats blinded for 2 weeks, lower carbohydrate but higher protein and water intakes in rats blinded for 4 weeks, while 2 weeks later blinded rats maintained high intakes of protein and water. The amplitudes of the daily rhythms for each nutrient behaved similarly to the weekly intakes. Delayed daily time of peak intake for all nutrients over successive weeks after blindness were found, indicating that the timing of peak intake free-runs. 24 h profile indicated time of day variations of nutrient intake tending to be less marked over successive weeks of blindness. Free-running animals maintained the link between carbohydrate intake and hypothalamus serotonin.