[The Effect of I155T, K156Q, K156E and N186K Mutations in Hemagglutinin on the Virulence and Reproduction of Influenza A/H5N1 Viruses].

The continued circulation of influenza A virus subtype H5 may cause the emergence of new potential pandemic virus variants, which can be transmitted from person to person. The occurrence of such variants is mainly related to mutations in hemagglutinin (HA). Previously we discovered mutations in H5N1 influenza virus hemagglutinin, which contributes to virus immune evasion. The purpose of this work was to study the role of these mutations in changing other, non-antigenic properties of the virus and the possibility of their maintenance in the viral population. Mutations were introduced into the HA gene of a recombinant H5N1 influenza A virus (VNH5N1-PR8/CDC-RG) using site-specific mutagenesis. The "variant" viruses were investigated and compared with respect to replication kinetics in chicken embryos, thermostability, reproductive activity at different temperatures (33, 37 and 40°C), and virulence for mice. Amino acid substitutions I155T, K156Q, K156E+V138A, N186K led to a decrease in thermal stability, replication activity of the mutant viruses in chicken embryos, and virulence for mice, although these effects differed between the variants. The K156Q and N186K mutations reduced viral reproduction at elevated temperature (40°C). The analysis of the frequency of these mutations in natural isolates of H5N1 influenza viruses indicated that the K156E/Q and N186K mutations have little chance to gain a foothold during evolution, in contrast to the I155T mutation, which is the most responsible for antigenic drift. The A138V and N186K mutations seem to be adaptive in mammalian viruses.

Variability of nonpathogenic influenza virus H5N3 under immune pressure.

Mutations arising in influenza viruses that have undergone immune pressure may promote a successful spread of mutants in nature. In order to evaluate the variability of nonpathogenic influenza virus A/duck/Moscow/4182-C/2010(H5N3) and to determine the common epitopes between it and highly pathogenic H5N1 avian influenza viruses (HPAIV), a set of escape mutants was selected due to action of MABs specific against A/chicken/Pennsylvania/8125/83(H5N2), A/Vietnam/1203/04(H5N1) and A/duck/Novosibirsk/56/05(H5N1) viruses. The complete genomes of escape mutants were sequenced and amino acid point mutations were determined in HA, NA, PA, PB1, PB2, M1, M2, and NP proteins. Comprehensive analysis of the acquired mutations was performed using the Influenza Research Database (https://www.fludb.org) and revealed that all mutations were located inside short linear epitopes, in positions characterized by polymorphisms. Most of the mutations found were characterized as substitutions by predominant or alternative amino acids existing in nature. Antigenic changes depended only on substitutions at positions 126, 129, 131, 145 and 156 of HA (H3 numbering). The positions 126, 145 and 156 were common for HA/H5 of different phylogenetic lineages of H5N1 HPAIV (arisen from A/goose/Guangdong/1/96) and low pathogenic American and Eurasian viruses. Additionally, mutation S145P increased the temperature of HA heat inactivation, compared to wild-type, as was proved by reverse genetics. Moreover, nonpathogenic A/duck/Moscow/4182-C/2010(H5N3) and H5N1 HPAI viruses have the same structure of short linear epitopes in HA (145-157) and internal proteins (PB2: 186-200, 406-411; PB1: 135-143, 538-546; PA: 515-523; NP: 61-68; M1: 76-84; M2: 45-53). These facts may indicate that H5 wild duck nonpathogenic virus could be used as vaccine against H5N1 HPAIV. Keywords: avian influenza virus; H5 hemagglutinin; escape mutants; genetic analysis; phenotypic properties; site-specific mutagenesis.

The Effect of I155T, K156Q, K156E and N186K Mutations in Hemagglutinin on the Virulence and Reproduction of Influenza A/H5N1 Viruses.

The continued circulation of influenza A virus subtype H5 may cause the emergence of new potential pandemic virus variants, which can be transmitted from person to person. The occurrence of such variants is mainly related to mutations in hemagglutinin (HA). Previously we discovered mutations in H5N1 influenza virus hemagglutinin, which contributes to virus immune evasion. The purpose of this work was to study the role of these mutations in changing other, non-antigenic properties of the virus and the possibility of their maintenance in the viral population. Mutations were introduced into the HA gene of a recombinant H5N1 influenza A virus (VNH5N1-PR8/CDC-RG) using site-specific mutagenesis. The "variant" viruses were investigated and compared with respect to replication kinetics in chicken embryos, thermostability, reproductive activity at different temperatures (33, 37 and 40°C), and virulence for mice. Amino acid substitutions I155T, K156Q, K156E+V138A, N186K led to a decrease in thermal stability, replication activity of the mutant viruses in chicken embryos, and virulence for mice, although these effects differed between the variants. The K156Q and N186K mutations reduced viral reproduction at elevated temperature (40°C). The analysis of the frequency of these mutations in natural isolates of H5N1 influenza viruses indicated that the K156E/Q and N186K mutations have little chance to gain a foothold during evolution, in contrast to the I155T mutation, which is the most responsible for antigenic drift. The A138V and N186K mutations seem to be adaptive in mammalian viruses.

Evaluation of lipid peroxidation processes in patients with chronic parenteral viral hepatitis and HIV co-infection depending on degree of inflammatory process activity in the liver.

AIM: To evaluate of parameters of lipid peroxidation - antioxidant defense changes in women of fertile age with chronic viral hepatitis (CVH) and with HIV (human immunodeficiency virus) infection, depending on the degree of inflammatory process activity in the liver. MATERIALS AND METHODS: 99 women of reproductive age were examined, of them 44 patients with chronic parenteral viral hepatitis, 27 patients with HIV co-infection (HIV + hepatitis B and/or C) and 28 practically healthy women (control group). RESULTS: Patients with CVH in combination with HIV-infection with the presence of minimal and low degree of inflammatory activity in comparison with patients with CVH-monoinfection had a higher content of lipid peroxidation products (an increase in the content of diene conjugates and ketodienes and conjugated trienes), reduced values of total antioxidant activity, superoxide dismutase activity, as well as the concentration of fat-soluble vitamins α-tocopherol and retinol. In the group with CVH and HIV with moderate and high degree of activity, similar, but even more pronounced changes in the system of lipid peroxidation were observed. CONCLUSION: The presence of co-infection - CVH in combination with HIV infection with minimal and low, as well as moderate and high inflammatory activity, is characterized by more intensive lipid peroxidation processes and a pronounced lack of antioxidant factors than with CVH-monoinfection.

Relaxin-3 inputs target hippocampal interneurons and deletion of hilar relaxin-3 receptors in "floxed-RXFP3" mice impairs spatial memory.

Hippocampus is innervated by γ-aminobutyric acid (GABA) "projection" neurons of the nucleus incertus (NI), including a population expressing the neuropeptide, relaxin-3 (RLN3). In studies aimed at gaining an understanding of the role of RLN3 signaling in hippocampus via its Gi/o -protein-coupled receptor, RXFP3, we examined the distribution of RLN3-immunoreactive nerve fibres and RXFP3 mRNA-positive neurons in relation to hippocampal GABA neuron populations. RLN3-positive elements were detected in close-apposition with a substantial population of somatostatin (SST)- and GABA-immunoreactive neurons, and a smaller population of parvalbumin- and calretinin-immunoreactive neurons in different hippocampal areas, consistent with the relative distribution patterns of RXFP3 mRNA and these marker transcripts. In light of the functional importance of the dentate gyrus (DG) hilus in learning and memory, and our anatomical data, we examined the possible influence of RLN3/RXFP3 signaling in this region on spatial memory. Using viral-based Cre/LoxP recombination methods and adult mice with a floxed Rxfp3 gene, we deleted Rxfp3 from DG hilar neurons and assessed spatial memory performance and affective behaviors. Following infusions of an AAV(1/2) -Cre-IRES-eGFP vector, Cre expression was observed in DG hilar neurons, including SST-positive cells, and in situ hybridization histochemistry for RXFP3 mRNA confirmed receptor depletion relative to levels in floxed-RXFP3 mice infused with an AAV(1/2) -eGFP (control) vector. RXFP3 depletion within the DG hilus impaired spatial reference memory in an appetitive T-maze task reflected by a reduced percentage of correct choices and increased time to meet criteria, relative to control. In a continuous spontaneous alternation Y-maze task, RXFP3-depleted mice made fewer alternations in the first minute, suggesting impairment of spatial working memory. However, RXFP3-depleted and control mice displayed similar locomotor activity, anxiety-like behavior in light/dark box and elevated-plus maze tests, and learning and long-term memory retention in the Morris water maze. These data indicate endogenous RLN3/RXFP3 signaling can modulate hippocampal-dependent spatial reference and working memory via effects on SST interneurons, and further our knowledge of hippocampal cognitive processing. © 2017 Wiley Periodicals, Inc.

[Evaluation of the pro- and antioxidant status of women with HIV or coinfection]. / Otsenka pro- i antioksidantnogo statusa u zhenshchin s VICh i koinfektsiei.

AIM: To reveal the specific features of changes in the parameters of lipid peroxidation - antioxidant defense and the status of the reproductive system in women of fertile age with monoinfection (HIV) or coinfection (HIV and hepatitis B and/or C). SUBJECTS AND METHODS: 81 reproductive-aged women were examined and divided into 3 groups: 1) 28 apparently healthy women (controls); 2) 26 patients with HIV monoinfection; and 3) 27 patients with HIV coinfection (HIV + hepatitis B and/or C) who had not previously received antiretroviral therapy. RESULTS: The HIV coinfection group showed the higher values of primary (conjugated dienes) and secondary (ketodienes and conjugated trienes) lipid peroxidation products in the presence of lower superoxide dismutase activity and obvious α-tocopherol deficiency than the control and HIV monoinfection groups. HIV coinfection in reproductive-aged women was accompanied by the high frequency of luteal phase deficiency. CONCLUSION: HIV coinfection is characterized by a more pronounced oxidative stress, antioxidant factor deficiency, and the high frequency of luteal phase deficiency in the patients.

Sex-Specific Effects of Chronic Administration of Relaxin-3 on Food Intake, Body Weight and the Hypothalamic-Pituitary-Gonadal Axis in Rats.

The present study examined the effects of chronic central administration of relaxin-3 (RLN3) on food intake, body weight and fat mass in intact and sterilised male and female rats, as well as on hypothalamic-pituitary-gonadal (HPG) axis activity in intact male and female rats that received i.c.v. infusions of RLN3 (400 pmol/day) or vehicle during a 14-day period. The intact RLN3-injected rats displayed a higher body weight than the vehicle-treated groups, and this increase was statistically significantly stronger in female rats compared to male rats. In addition, feed efficiency and gonadal white adipose tissue weight were higher in female RLN3-injected rats. Chronic i.c.v. administration of RLN3 activated the HPG axis in intact male rats, whereas inhibition of the HPG axis was observed in intact female rats. RLN3 significantly increased the plasma levels of luteinising hormone and follicular-stimulating hormone in male rats but not in female rats. Conversely, hypothalamic expression of gonadotrophin-releasing hormone mRNA was decreased by RLN3 in female rats but not in male rats. In addition, the plasma levels of oestradiol were significantly decreased by RLN3 administration in female rats. Consequently, intact RLN3-injected female rats failed to display phasic inhibition of eating during oestrus. Sex-specific effects of RLN3 on food intake and body weight were also observed in ovariectomised female and orchidectomised male rats, suggesting that the sex-specific effects of RLN3 on energy metabolism are independent on the differential effects of RLN3 on HPG axis activity in male and female rats.

Differential effects of central administration of relaxin-3 on food intake and hypothalamic neuropeptides in male and female rats.

Relaxin-3 (RLN3) is an orexigenic neuropeptide that produces sex-specific effects on food intake by stronger stimulation of feeding in female compared with male rats. This study determined which hypothalamic nuclei and associated neuropeptides may be involved in the sex-specific orexigenic effects of RLN3. Relaxin-3 (800 pmol) or vehicle was injected into the lateral ventricle of female and male rats. Food and water intake were measured after the first injection, and rats were euthanized after the second injection to determine the mRNA expression of the hypothalamic neuropeptides. Food but not water intake showed sex-specific effects of RLN3. Stimulation of food intake by RLN3 was significantly higher in female than in male rats. No effect of RLN3 injection was found on c-fos mRNA expression in the arcuate, dorsomedial and ventromedial hypothalamic nuclei. Increased c-fos mRNA expression was observed in the paraventricular hypothalamic nucleus (PVN) in both sexes and in the lateral hypothalamic area (LHA) in female rats. Relaxin-3 injections led to a sex-nonspecific increase in the expression of oxytocin mRNA in the magnocellular PVN. Conversely, RLN3-induced expression of anorexigenic neuropeptide arginine vasopressin (AVP) was significantly higher in the parvocellular PVN in male compared with female rats. Finally, RLN3 administration significantly increased the expression of orexin (ORX) mRNA in the LHA in female but not in male rats. Stronger expression of anorexigenic AVP in the PVN in male rats and increased expression of ORX in the LHA in female rats may contribute to stronger orexigenic effects of RLN3 in female rats compared with male rats.

Note: Sample chamber for in situ x-ray absorption spectroscopy studies of battery materials.

In situ x-ray absorption spectroscopy (XAS) provides element-specific characterization of both crystalline and amorphous phases and enables direct correlations between electrochemical performance and structural characteristics of cathode and anode materials. In situ XAS measurements are very demanding to the design of the experimental setup. We have developed a sample chamber that provides electrical connectivity and inert atmosphere for operating electrochemical cells and also accounts for x-ray interactions with the chamber and cell materials. The design of the sample chamber for in situ measurements is presented along with example XAS spectra from anode materials in operating pouch cells at the Zn and Sn K-edges measured in fluorescence and transmission modes, respectively.

Sex differences in the effects of chronic stress and food restriction on body weight gain and brain expression of CRF and relaxin-3 in rats.

This study investigated sex-specific effects of repeated stress and food restriction on food intake, body weight, corticosterone plasma levels and expression of corticotropin-releasing factor (CRF) in the hypothalamus and relaxin-3 in the nucleus incertus (NI). The CRF and relaxin-3 expression is affected by stress, and these neuropeptides produce opposite effects on feeding (anorexigenic and orexigenic, respectively), but sex-specific regulation of CRF and relaxin-3 by chronic stress is not fully understood. Male and female rats were fed ad libitum chow (AC) or ad libitum chow and intermittent palatable liquid Ensure without food restriction (ACE), or combined with repeated food restriction (60% chow, 2 days per week; RCE). Half of the rats were submitted to 1-h restraint stress once a week. In total, seven weekly cycles were applied. The body weight of the RCE stressed male rats significantly decreased, whereas the body weight of the RCE stressed female rats significantly increased compared with the respective control groups. The stressed female RCE rats considerably overate chow during recovery from stress and food restriction. The RCE female rats showed elevated plasma corticosterone levels and low expression of CRF mRNA in the paraventricular hypothalamic nucleus but not in the medial preoptic area. The NI expression of relaxin-3 mRNA was significantly higher in the stressed RCE female rats compared with other groups. An increase in the expression of orexigenic relaxin-3 and misbalanced hypothalamic-pituitary-adrenal axis activity may contribute to the overeating and increased body weight seen in chronically stressed and repeatedly food-restricted female rats.

[Features of the functioning of the thyroid gland in HIV-infected].

In the article analyzed the current literature, devoted to the peculiarities of functioning of the thyroid gland in patients with HIV infection. Based on the analysis of literature data bases demonstrated the structure of thyroid function disorders in HIV-infected, as well as the mechanisms of the pathogenesis of these disorders. In the structure of thyroid function is dominated by hypothyroidism, euthyroid pathological syndrome, Graves' disease, for which the opportunistic infections are triggers immune activation. It should be noted that the step of acquired immunodeficiency syndrome is accompanied by the development of inflammatory and neoplastic processes in the thyroid gland. Convincingly demonstrated the negative impact of highly active antiretroviral therapy in HIV-positive for the development of thyroid dysfunction, in connection which the expediency of forming risk groups and the timely correction of the projected thyroid diseases.

[Current problems in the combined therapy of lung cancer].

The paper describes the general experience of modern lung cancer treatment methods application. Neoadjuvant therapy was shown to improve the long-term results of stage III patients increasing the 5-year overall survival by 7,8% (p=0,012). The special diagnostic algorithm for treatment results evaluation including autofluorescence spectrometry with 97,1% sensitivity and 88,3% specificity was developed. The adjuvant external-beam radiotherapy in patients with mediastinal lymph nodes metastases was shown to increase the 5-year overall survival (14,7% versus 19,7%) (p=0,01). The combination of endotracheobronchial surgery with chemoradiotherapy allowed to increase the median survival time of patients with inoperable lung cancer to 17 months. Isolated lung chemoperfusion was shown to increase the overall (p=0,019) and relapse-free (p=0,005) survival in patients with lung metastases.

Sucrose modifies c-fos mRNA expression in the brain of rats maintained on feeding schedules.

Food intake is regulated according to circadian activity, metabolic needs and the hedonic value of food. Rodents placed on a fixed feeding schedule show behavioral and physiological anticipation of mealtime referred to as food-anticipatory activity (FAA). FAA is driven by the food-entrainable oscillator (FEO), whose anatomical substrate is not yet known. Recent data have shown that restricted feeding schedules for regular chow and daily limited access to palatable food in free-feeding rats activate distinct brain regions during FAA. The combination of a deprivation regimen and scheduled access to palatable food may give rise to a more global anticipatory mechanism because the temporal cycles of energy balance would be strongly modulated by the incentive properties of palatable food; however, the neuronal response to this combined treatment is not yet known. The present study investigated how adding palatable sucrose to feeding schedules affects the pattern of brain c-fos mRNA expression during FAA (0-3 h) and 1 h following feeding. The rats maintained on scheduled chow access increased their daily chow intake, while the rats maintained on scheduled sucrose and chow mainly increased their daily sucrose intake. Adding sucrose to scheduled feeding displaced c-fos mRNA expression from the dorsomedial and paraventricular hypothalamic nuclei and posterior lateral hypothalamus (LH) to the prefrontal cortex, lateral septum, nucleus accumbens and anterior LH. During refeeding, the rats on scheduled sucrose demonstrated higher activation of the nucleus of the solitary tract. The present results suggest that palatable sucrose combined with restricted feeding schedules activate a distinct neuronal network compared to neuronal activation produced by scheduled access to regular chow. These data provide evidence that the brain may contain different food-oscillatory systems and that food palatability may shift the neuronal activity from the medial hypothalamus to the limbic and reward-related areas even at the negative metabolic state.

Palatable high-energy diet decreases the expression of cannabinoid type 1 receptor messenger RNA in specific brain regions in the rat.

In laboratory rodents, a palatable high-energy diet (PHED) is usually consumed in a higher quantity than a standard laboratory diet, leading to the development of an obese phenotype. The central effects of PHED are not fully understood. Nonetheless, the long-term consumption of PHED can decrease cannabinoid type 1 receptor (CB1R) protein density in particular brain regions. However, little is known about the diet-dependent regulation of the brain expression of CB1R mRNA. The present study aimed to investigate the effects of the long-term consumption of PHED and short-term (12 h) food deprivation on the brain expression of CB1R mRNA. For 13 weeks, rats were fed a standard laboratory chow or PHED presented as a free choice of chow, shortcake biscuits and pork spread. In total, the food intake of PHED rats was higher than that of chow-fed animals. Expectedly, PHED rats demonstrated higher body weight than chow-fed animals. The difference in body weight between PHED- and chow-fed rats was as result of the fat but not the lean mass. PHED-fed rats had significantly higher plasma levels of leptin and insulin and significantly higher levels of expression of suppressor of cytokine signalling 3 (SOCS-3) in the arcuate hypothalamic nucleus. The long-term consumption of PHED significantly decreased the levels of CB1R mRNA expression in the cingulate (Cg) cortex, ventromedial hypothalamic nucleus and the descending/autonomic divisions of the parvocellular hypothalamic nucleus (PVH), the ventrolateral parvocellular PVH and, to a lesser extent, the dorsomedial parvocellular PVH. Acute food deprivation decreased the levels of CB1R transcript in the Cg and ventrolateral parvocellular PVH. Altogether, the present results demonstrate that long-term PHED leads to an increase in the hypothalamic expression of SOCS-3 mRNA and a decrease in expression of CB1R mRNA in the Cg cortex and specific hypothalamic regions.

[Epidemic process of rubella during mass vaccination of children].

AIM: To reveal features of rubella epidemic process during start of mass immunization and to determine rubella virus genotypes circulating in Saint-Petersburg. MATERIALS AND METHODS: Official data on rubella morbidity during 1995-2007 and number of vaccinated against rubella children and adults were used in this study. During 2006-2008 males aged 17-20 years with rubella diagnosis were eligible for laboratory test on rubella. Nasopharyngeal swabs and blood specimenswere tested by PCR and virus isolation on cell culture (PK13). Genotyping of isolates was performed on the basis of 600 nucleotide sequence of E1 gene from 8731 to 9653 n.p. RESULTS: It was shown that mass vaccination of children and young women against rubella during 4 years resulted in 3-fold drop of rubella incidence inwhole population, which diminishes the probability of infection in pregnant women and born of children with congenital rubella syndrome. In age structure of rubella morbidity the proportion of children aged 3-6 and 7-14 years decreased by 1.5-fold. Epidemic process loss the features of autoregulating system (periodicity and seasonal incidence peaks). Results of genotyping showed that isolates belonged to genotype 1E. High degree of homology (97.7-99.6%) to isolates from Barnaul and Belorussia was demonstrated. CONCLUSION: Issues on isolates' origin and success of measures on elimination of endemic rubella could be resolved by further studies on isolation and genotyping of rubella virus strains in Saint-Petersburg and North-East region of Russian Federation in the whole.

[Lymphocyte reaction and humoral immune response to brain specific protein in children with pathology of the central nervous system]. / Reaktsiia limfotsitov i gumoral'nyi immunnyi otvet na mozgospetsificheskii belok u detei s patologiei tsentral'noi nervnoi sistemy.

Blood lymphocyte reaction to brain specific protein (BSP) in vitro and anti-brain antibodies (AB) levels were studied in newborns and infants with perinatal central nervous system (CNS) damages of various severity. A relationship between severity of CNS damages and a lymphocyte reaction to BSP as well as immuno-regulative index (IRI) changes. A combination of high AB to BSP levels with IRI elevation after cells incubation with BSP was found to be a favorable prognostic sign. In contrast, IRI reduction combined with higher AB levels appeared to be an unfavorable one.

Activation of the central nervous system in obese Zucker rats during food deprivation.

This study was carried out to investigate the pattern of neuronal activations that occur in the obese fa/fa Zucker rat during food deprivation. The functional activation of neurons was estimated in lean and obese Zucker rats either fed ad libitum or food-deprived for 3, 6, 12, and 24 hours by assessing the expression of the immediate early gene c-fos. To identify the neurons instigating the activation of the hypothalamic-pituitary-adrenal axis in food-deprived obese rats, the retrograde tracer cholera toxin B subunit was injected in the parvocellular division of the paraventricular hypothalamic nucleus of obese rats and colocalized with c-fos mRNA during food deprivation. The expression of c-fos was barely detectable in food-deprived lean rats as well as in lean and obese animals fed ad libitum. However, 3 hours of food deprivation were sufficient to significantly induce c-fos in the paraventricular thalamic nucleus of obese rats. In addition, 6 and 12 hours of food deprivation resulted in the activation of regions that are similarly stimulated in "neurogenic" stresses. These regions include the parvocellular division of the paraventricular hypothalamic nucleus, the lateral septum, the basolateral amygdala, and some areas of the cortex. The highest number of neurons projecting to the parvocellular division of the paraventricular hypothalamic nucleus and revealing c-fos mRNA was, however, located in the paraventricular thalamic nucleus. In summary, the present results demonstrate in the obese fa/fa Zucker rats, that food deprivation leads to brain activations, which are in large part, similar to those induced by a "neurogenic" stress and that the paraventricular thalamic nucleus is involved in this response. These changes could contribute to the development of hyperphagia and obesity.

Kinetics of elementary steps of electron transfer in nitrogenase in the presence of a photodonor.

The kinetics of transfer of two electrons from a photodonor (a system containing eosin and NADH or 4;,5;-dibromofluorescein and NADH) to Fe-protein (Av2) and the kinetics of transfer of the first and second electrons from Av2 to Mo-Fe-protein (Av1) were studied by kinetic laser spectroscopy of nitrogenase from Azotobacter vinelandii. The effects of the substrates of nitrogenase (nitrogen, acetylene, and protons) on the intramolecular electron transfer in nitrogenase were studied. Analysis of the effect of photodonor excitation radiation intensity on the rate of electron transfer was used to determine the transfer rate constants for the first (k1) and second (k2) electrons from Av2 to Av1. In the presence of MgATP, two electrons are sequentially transferred from Av2 to Av1, and no delay between these reactions was detected. The first electron transferred from Av2 to Av1 is not targeted to the substrate; k1 = 154 +/- 15 sec-1 at 23 degrees C for the system 4;,5;-dibromofluorescein-NADH; k2 = 53 +/- 5 sec-1, 95 +/- 9 sec-1, and 24 +/- 2 sec-1 at 23 degrees C in the presence of nitrogen, acetylene, and argon, respectively. An unidentified slow step (k3 = 18 +/- 2 sec-1 at 23 degrees C) may be associated with electron transfer within Av1.

The corticotropin-releasing hormone system in the regulation of energy balance in obesity.

The view that energy balance is regulated has gained acceptance in recent years. An important role in this regulation is played by brain circuitries involved in the control of energy intake (food intake) and energy expenditure (thermogenesis) that are capable of integrating peripheral signals, produced by perturbations of adipose tissue mass, into messages to effectors of food intake and energy expenditure, so as to prevent substantial variations in the level of energy reserves. More than one neurosystem has been reported to genuinely participate in the regulation of energy balance. Among them is the corticotropin-releasing hormone (CRH) system. This system, with its numerous clusters of brain neurons, its closely related peptide urocortin, its two receptor types and its binding protein, all generally widely distributed throughout the brain, forms a network of neuronal pathways capable of interacting with the circuitries controlling food intake and energy expenditure. In addition, CRH and urocortin's anorectic and thermogenic actions appear to be coordinated to optimize energy losses. Finally, the CRH system seems to demonstrate a certain degree of plasticity in obesity and in response to food deprivation that is consistent with its action on food intake and thermogenesis. The observations have been made that food deprivation and obesity can blunt the expression of the CRH type 2alpha receptor in the ventromedial hypothalamic nucleus and can induce the expression of the CRH-binding protein (a CRH-inactivating protein) in brain areas involved in the anorectic and thermogenic actions of CRH.