Inhibition of aldosterone production by alpha-human atrial natriuretic polypeptide is associated with an increase in cGMP production

Synthetic alpha-human atrial natriuretic polypeptide caused rapid and marked inhibition of aldosterone production in dispersed rat adrenal capsular cells. The polypeptide also slightly, but significantly, decreased cAMP production in the adrenal dispersed capsular cells, while markedly stimulating cGMP production. The cGMP production was accelerated at the concentration of alpha-human atrial natriuretic polypeptide lower than the threshold level to stimulate aldosterone production. These findings suggest that alpha-human atrial natriuretic polypeptide possibly plays a regulatory role in aldosterone production and an additional role in natriuresis through inhibition of aldosterone production. The stimulation of cGMP production by alpha-human atrial natriuretic polypeptide may be involved in the inhibitory effect of this peptide on aldosterone production.     

Heat production during sleep

Heat production during sleep was studied by continuous indirect calorimetry with simultaneous electroencephalographic monitoring. Controlling for gross influences on heat production, comparisons of heat production during different sleep stages showed heat production in stage 4 sleep to be significantly lower than in other sleep stages. There appeared to be a gradation in heat production in non-rapid-eye-movement stages of sleep with stage 2 higher and stage 4 lower than stage 3. Heat production in stage 4 was less variable than in any other sleep stage. Both the level and variability of heat production was similar in stage 2 and rapid-eye-movement sleep. Heat production during the night was 9% lower than during resting wakefulness. The average heat production in stage 4 sleep was 14.4% lower than resting wakeful values.     

Differential effect of vasoactive intestinal peptide, somatostatin, and substance P on human IgE and IgG subclass production.

We studied the effect of vasoactive intestinal peptide (VIP), somatostatin (SOM), and substance P (SP) on IL-4-stimulated human IgE and IgG subclass production. VIP and SOM, but not SP, inhibited IgE production without affecting IgM or IgA production by mononuclear cells (MNC) from nonatopic donors from 10 pM to 10 nM. These neuropeptides also differentially modulated IgG subclass production. While IgG1 production was not affected by VIP, SOM, or SP, all of the neuropeptides enhanced IgG2 production. By contrast, SOM and SP, but not VIP, inhibited IgG3 production, whereas VIP and SP, but not SOM, enhanced IgG4 production. The effect by neuropeptides was specific since each peptide effect was specifically blocked by each antagonist. To achieve this effect, neuropeptides must be added at the start of the culture and be present throughout the entire culture period. The inhibition of IgE production was not mediated by known inhibitors of IgE production, IFN-gamma or PGE2, because the addition of anti-IFN-gamma mAb (10 micrograms/ml) or indomethacin (0.1 microM) did not overcome the inhibition of IgE production. In contrast to MNC, neuropeptides did not affect IgG subclass production in purified B cells. IgE production was not induced by IL-4 in purified B cells. Neuropeptides also failed to modulate IgG subclass production in cultures of B cells with either T cells or monocytes. However, they modulated IgE production and IgG subclass production in B cells in the presence of T cells and monocytes. In purified B cells, IL-4 plus anti-CD40 mAb induced IgE production which was not inhibited by VIP or SOM. However, VIP or SOM, but not SP, inhibited IgE production in B cells cultured with both T cells and monocytes. Finally, the mechanism of modulation of IgE and IgG4 production was dependent on IL-4-induced switching, since neuropeptides modulated IgG4 and IgE production in surface IgG4-negative (sIgG4-) and sIgE- B cells, respectively. In contrast, modulation of IgG2 and IgG3 production was not due to switching, since neuropeptides did not affect either IgG2 or IgG3 production in sIgG2- or sIgG3- B cells, respectively.     

The role of Chironomidae in energy flow of a lotic ecosystem

Chironomid secondary production was estimated on a species-specific basis for 14 dominant taxa in a third-order woodland stream. Results from this study were used to provide an expalanation for the common observation that benthos secondary production in streams is insufficient to account for levels of fish production,i.e., the ALLEN paradox. Annual chironomid secondary production was 29.7 g dry mass m^–2 and accounted for 80% of the total aquatic insect secondary production. A contribution by chironomids this high has not been reported previously from similar streams and indicates that chironomids are an energetically important group available for fish consumption. Most studies examining chironomid secondary production group all taxa at the family level and calculate secondary production for the entire family using the size-frequency method. This approach violates assumptions of the size-frequency method and will result in inaccurate and unpredictable estimates of chironomid secondary production. The species-specific approach to estimate chironomid production used in this study, combined with non-chironomid production, yielded a benthos annual production rate that exceeded consumption necessary to support fish production.     

Stimulation of Cyclic GMP Production via a Nitrosyl Factor in Sensory Neuronal Cultures by Algesic or Inflammatory Agents

Abstract: Capsaicin stimulates cyclic GMP production via nitric oxide (NO) (or another nitrosyl factor) in dorsal root ganglion (DRG) neurons maintained in culture. The purpose of the present study was to characterize further capsaicin stimulation of cyclic GMP production in DRG cells maintained in culture, investigate other algesic and/or inflammatory agents for effects on cyclic GMP production, and examine cells responsible for NO production and cyclic GMP production. Capsaicin stimulation of cyclic GMP production in DRG cells was dose dependent, receptor mediated, and attenuated by hemoglobin. Prostaglandin E₂, substance P, and calcitonin gene-related peptide did not affect basal, capsaicin-stimulated, or bradykinin-stimulated cyclic GMP production. Other inflammatory or algesic agents, including serotonin, histamine, ATP, glutamate, aspartate, and NMDA, did not affect cyclic GMP production. Pretreatment of DRG cells with lipopolysaccharide increased basal cyclic GMP production in neuronal but not in nonneuronal cultures and facilitated stimulation of cyclic GMP production by l -arginine. Capsaicin pretreatment of neuronal DRG cultures, which destroys capsaicin-sensitive (small diameter) afferent neurons, attenuated capsaicin- and bradykinin-stimulated cyclic GMP production but did not affect basal or sodium nitroprusside-stimulated cyclic GMP production. These results indicate that capsaicin elicits production of a nitrosyl factor via capsaicin-sensitive (small diameter) neurons. Capsaicin evoked cyclic GMP production in nonneuronal DRG cultures in the presence but not in the absence of apposed neuronal DRG cultures. Overall, these findings suggest that specific exogenous (or endogenous) substances may stimulate production of a nitrosyl factor(s) by a subset of DRG neurons, and nitrosyl factors produced by these neurons may affect cyclic GMP production in neighboring neuronal or non-neuronal cells.     

Primary and Bacterial Production in Two Dimictic Indiana Lakes

The relationship between primary and bacterial production in two dimictic Indiana lakes with different primary productivities was examined during the summer stratification period in 1982. Primary production rates were calculated from rates of H¹⁴CO₃⁻ incorporation by natural samples, and bacterial production was calculated from rates of [³H-methyl]thymidine incorporation by natural samples. Both vertical and seasonal distributions of bacterial production in the more productive lake (Little Crooked Lake) were strongly influenced by primary production. A lag of about 2 weeks between a burst in primary production and the subsequent response in bacterial production was observed. The vertical distribution of bacterial production in the water column of the less productive lake (Crooked Lake) was determined by the vertical distribution of primary production, but no clear relationship between seasonal maxima of primary and bacterial production in this lake was observed. High rates of bacterial production in Crooked Lake during May indicate the importance of allochthonous carbon washed in by spring rains. Bacterial production accounted for 30.6 and 31.8% of total (primary plus bacterial) production in Crooked Lake and Little Crooked Lake, respectively, from April through October. High rates of bacterial production during late September and October were observed in both lakes. Calculation of the fraction of bacterial production supported by phytoplankton excretion implies an important role for other mechanisms of supplying carbon, such as phytoplankton autolysis. Several factors affecting the calculation of bacterial production from the thymidine incorporation rates in these lakes were examined.     

Diphenyleneiodonium acutely inhibits reactive oxygen species production by mitochondrial complex I during reverse, but not forward electron transport

We investigated the effects of diphenyleneiodonium (DPI) on superoxide production by complex I in mitochondria isolated from rat skeletal muscle. Superoxide production was measured indirectly as hydrogen peroxide production. In a conventional medium containing chloride, DPI strongly inhibited superoxide production by complex I driven by reverse electron transport from succinate. In principle, this inhibition could be explained by an observed decrease in the mitochondrial pH gradient caused by the known chloride-hydroxide antiport activity of DPI. In a medium containing gluconate instead of chloride, DPI did not affect the pH gradient. In this gluconate medium, DPI still inhibited superoxide production driven by reverse electron transport, showing that the inhibition of superoxide production was not dependent on changes in the pH gradient. It had no effect on superoxide production during forward electron transport from NAD-linked substrates in the presence of rotenone (to maximise superoxide production from the flavin of complex I) or antimycin (to maximise superoxide production from complex III), suggesting that the effects of DPI were not through inhibition of the flavin. We conclude that DPI has the novel and potentially very useful ability to prevent superoxide production from the site in complex I that is active during reverse electron transport, without affecting superoxide production during forward electron transport.     

Diphenyleneiodonium acutely inhibits reactive oxygen species production by mitochondrial complex I during reverse, but not forward electron transport

We investigated the effects of diphenyleneiodonium (DPI) on superoxide production by complex I in mitochondria isolated from rat skeletal muscle. Superoxide production was measured indirectly as hydrogen peroxide production. In a conventional medium containing chloride, DPI strongly inhibited superoxide production by complex I driven by reverse electron transport from succinate. In principle, this inhibition could be explained by an observed decrease in the mitochondrial pH gradient caused by the known chloride-hydroxide antiport activity of DPI. In a medium containing gluconate instead of chloride, DPI did not affect the pH gradient. In this gluconate medium, DPI still inhibited superoxide production driven by reverse electron transport, showing that the inhibition of superoxide production was not dependent on changes in the pH gradient. It had no effect on superoxide production during forward electron transport from NAD-linked substrates in the presence of rotenone (to maximise superoxide production from the flavin of complex I) or antimycin (to maximise superoxide production from complex III), suggesting that the effects of DPI were not through inhibition of the flavin. We conclude that DPI has the novel and potentially very useful ability to prevent superoxide production from the site in complex I that is active during reverse electron transport, without affecting superoxide production during forward electron transport.     

黄土高原-青藏高原过渡带农户生产系统的能值分析——以通渭-渭源-夏河样带为例

通渭-渭源-夏河样带位于黄土高原向青藏高原过渡的生态区,是我国典型农牧交错带。长期以来,不合理的农业生产结构带来生态、经济等一系列问题,制约了该地区草地农业的持续发展。为此,从能值角度分析区域农业生产结构,可为农(牧)户决策提供理论依据,为优化区域农业生产结构提供科学依据。收集研究区农户作物和家畜生产的投入-产出数据,用能值方法分析农户生产系统结构特征、农户生产决策行为及生产系统耦合作用,用结构方程模型(SEM)分析农户生产系统能量的组分间流动。研究发现,随海拔增高,农户作物生产活动减少,作物总产出能值递减;尽管作物生产主要投入和产出要素相同,但同一作物不同地点的同一要素投入、产出能值和能值收益率均存在显著差异(P0.05);同一地点不同作物的同一要素投入、产出能值和能值收益率均差异显著(P0.05);作物生产投入要素中,有机肥能值在通渭和渭源均有较高贡献;作物投入和产出能值的农户生产决策阈值自东向西递减,在能值投入初始增加时,夏河农户作物生产规模扩增最为迅速。家畜养殖规模、能值投入和产出自东向西递增;通渭和渭源,小麦秸秆和苜蓿作为中间投入,能值贡献率达到80%;夏河家畜生产投入要素中,补饲粮食能值贡献率高达90%;家畜投入和产出能值的农户生产决策阈值点自东向西递增;能值收益率随耦合度的增加呈指数上升,通渭和渭源能值收益率的增加速度,随耦合度的增加趋于缓慢,而夏河能值收益率增速随耦合度的增加而上升。调整作物生产内部粮、经、饲产品比例结构,加强作物生产与家畜生产耦合作用,优化天然草地利用方式,实现生态效益最大化;阈值点调控农户生产决策行为,实现该区域农业生产结构优化。     

Bacterial secondary production and it relation with primary production in the Embalse del Río III Reservoir,Argentina

During an annual period the bacterial biomass (epifluorescence) and secondary production (methyl-³H-thymidine incorporation), as well as biomass (Chlorophyll) and algal primary production (incorporation of NaH¹⁴CO₃) were studied in the Embalse del Río III Reservoir, Argentina. The relations between these variables and their responses to seasonal changes in water temperature were analyzed. A close relationship in seasonal patterns of algal primary production and bacterial secondary production was observed, with the estimated rates of bacterial production similar to that obtained by other authors in eutrophic lakes. Bacterial production was 17 to 46% of the primary production, thus, at 60% assimilation efficiency, the bacterioplankton would consume 28 to 77 % of the total fixed carbon. Seasonal trends in algal primary production and bacterial secondary production were mainly affected by temperature.     

PPD-induced immunoglobulin production in human peripheral blood lymphocytes. I. Necessary conditions for inducing the response.

The ability of PPD to induce Ig production in human PBL was investigated. PPD proved to be a good B cell activator for inducing polyclonal Ig production in PBL from healthy Japanese. Comparative studies of this response with PWM-induced Ig production showed that the cellular mechanisms involved in the two responses were different. First, PBL from an atypical individual with a deficient IgM production to PWM responded normally to PPD with IgM production as well as IgG production. Secondly, in IgG production, the effects of the two mitogens (PPDand PWM) were additive. An analysis of the cellular requirements in PPD-induced Ig production clearly demonstrated that T cells played a role in this response as well as in the PWM-induced response. However, the head-to-head comparative study on the titration curves of helper T cells in the two responses showed that PWM-induced helper activity was 2 to 5 times more effective than PPD-induced helper activity. Moreover, PPD-induced helper activity was shown to be more sensitive to ionizing radiation than was PWM-induced helper activity. Thus, this system of PPD-induced Ig production may provide a useful tool for understanding the human antibody production system as well as the PWM-induced response.     

Relationship between hybridoma growth and monoclonal antibody production.

Factors affecting cell growth and antibody production in a mouse hybridoma were investigated. Antibody was produced during the growth and decline phases of a batch culture with an increase in the specific rate of antibody production during the decline phase. The specific rate of antibody production was also increased in cells arrested by 2 mM thymidine, suggesting that cell proliferation and antibody production can be uncoupled. Reduced serum concentrations resulted in lower cell growth rates but increased antibody production rates. However, this trend was reversed in hybridomas which had been arrested by thymidine, since the highest antibody production rate was associated with high serum concentrations. Likewise, in proliferating cells, the optimum pH for antibody production (pH 6.8) was lower than the optimum pH for cell growth (pH 7.2), whereas in thymidine-blocked cells, the highest antibody production rate was at pH 7.2. High antibody production rates and product yields were also associated with low growth rates in continuous cultures. The possibility that antibody was under cell cycle control was investigated in synchronized hybridoma cultures. Antibody production occurred during G1 and G2 with a decline in the M phase and evidence of a further decline in the S phase. Thus antibody production was not restricted to the G1 and S phase in this hybridoma.     

Network regulation of the immune response: modulation of suppressor lymphocytes by alternative signals including contrasuppression

In the preceding paper we demonstrated that comparison of alternative designs for the immune network can be used to examine the functional significance of specified interactions in normal immune responses. In this paper we examine mathematically the functional significance of three interactions affecting the production of suppressor lymphocytes involved in regulation of normal immune responses. The interactions examined in detail are 1) antigenic stimulation of the production of suppressor lymphocytes, 2) idiotypic stimulation of the production of suppressor lymphocytes, and 3) antigenic inhibition of the production of suppressor lymphocytes (i.e., contrasuppression). The results of our analysis suggest that an immune system with only antigenic stimulation of suppressor production is less effective than a system with both antigenic and idiotypic stimulation of suppressor production on the basis of all of the criteria examined in this study. In turn, the latter system is less effective than a system with only idiotypic stimulation of suppressor production. Furthermore, a system with both idiotypic stimulation and antigenic inhibition of suppressor production can be equal or superior to a system with only idiotypic stimulation of suppressor production on the basis of the same criteria. Similar conclusions hold for the comparison of systems in which regulation by the suppressor lymphocytes of interest is exerted upon production of effector molecules rather than upon production of effector lymphocytes, and also for the comparison of systems in which interactions affecting the production of suppressor factors are of interest.     

On the regulation of rat testicular steroidogenesis. Short term effect of luteinizing hormone and cycloheximide in vivo and Ca2+ in vitro on steroid production in cell-free systems.

An attempt has been made to correlate the rapid effect of luteinizing hormone on testicular steroid production in vivo with testicular steroid concentrations and in vitro steroid production rates in testis tissue preparations. Within 20 min after intravenous administration of 25 mug luteinizing hormone, increases were observed in testosterone concentrations in testicular venous plasma and in whole testis tissue and in pregnenlone concentrations isolated testis mitochondrial fractions. Testosterone production by whole testis homogenates and pregnenolone production by isolated mitochondrial fractions were significantly increased within 5 min after in vivo administration of luteinizing hormone. Injection of cycloheximide 10 min prior to luteinizing hormone prevented the stimulating effect of luteinizing hormone to steroid levels in testicular venous plasma and testis tissue and on steroid production rates by preparations of rat testis tissue. Cycloheximide treatment of control animals did not significantly alter testosterone concentrations and testosterone production rates vitro, although mitochondrial pregnenolone concentrations and production rates were decreased. Testosterone production by whole testis homogenates as well as the pregnenolone production by isolated mitochondrial fractions obtained from luteinizing hormone treated testes and control glands showed a biphasic time curve A period (5-10 min) of high steroid production was followed by a period lower steroid production. Addition of 25 mug luteinizing hormone or 10(-8)--10(-5) M adenosine 3':5'-monophosphate (cyclic AMP) to the incubation medium had no effect pregnenolone production by isolated mitochondrial fractions. Administration of leuteinizing hormone in vivo markedly enhance the stimulating effect of Ca2+ on testosterone production by whole testis homogenates and on pregnenolone production by isolated mitochondrial fractions.     

On ecosystem production

We have discussed some aspects of the production and efficiency of energy use in aquatic ecosystems. Ecosystem production is defined as the difference between the gross total primary production and total expenditures for metabolic processes in all organisms of the ecosystem. We have obtained equations showing the dependence of ecosystem production on the average depth of a waterbody and the share of the primary production of phytoplankton in the total production. The mean value of the coefficient of ecosystem efficiency in some waterbodies (53%) indicates that aquatic ecosystems use energy efficiently. The efficiency of the energy use increases with an increase in the biomass turnover rate. High production in the ecosystem can be obtained if its structure is simpler.     

Effect of sub-inhibitory concentrations of antibiotics on the virulence of Staphylococcus aureus

The production of virulence factors by various bacteria can be influenced by sub-inhibitory concentrations of antibiotics. The effect of six antibiotics on the production of representative extracellular enzymes and toxins produced by Staphylococcus aureus was investigated. The production of the virulence determinants coagulase, protein A, alpha and delta haemolysin was monitored in the presence of ciprofloxacin, enoxacin, chloramphenicol, gentamicin, tetracycline and methicillin. The protein synthesis inhibitors reduced the production of coagulase and protein A, and almost completely inhibited the production of the haemolysins. Haemolysin production was also reduced by ciprofloxacin and enoxacin, but these antibiotics had little effect on the production of coagulase and protein A. Methicillin stimulated the production of alpha and delta haemolysins but had no effect on the production of coagulase and protein A.     

红壤丘陵区粮食生产的生态成本

人类的生产活动必然对资源与环境造成影响,以红壤丘陵区的湖南省祁阳县为研究对象,应用经济学和生态学方法,对粮食生产中的生态成本进行了研究。结果表明:2008年该区粮食生产生态损失总价值相当于当年农业总产值的4.85%;早、中、晚稻生态成本已分别达到3.18、2.44、3.02元/kg,而出售单价分别为1.76、1.90、1.84元/kg,高成本低收益的情况对该区域的可持续发展产生着不利影响;在当前生产力水平条件下,适度提高化肥、农药、农业机械、农膜、劳动力的投入,提高水稻产量,扩大家庭种植规模,可降低生产单位水稻的生态成本。     

Calorimetric study on human erythrocyte glycolysis. Heat production in various metabolic conditions.

The heat production of human erythrocytes was measured on a flow microcalorimeter with simultaneous analyses of lactate and other metabolites. The heat production connected with the lactate formation was about 17 kcal (71 kJ) per mol lactate formed which corresponded to the sum of heat production due to the formation of lactate from glucose and the heat production due to neutralization. The heat production rate increased as the pH of the suspension increased, corresponding to the increase in lactate formation. Glycolytic inhibitors such as fluoride and monoiodoacetate caused a decrease in the rate of heat production, whereas arsenate induced a large transient increase in heat production associated with a transient increase in lactate formation. Decrease in pyruvate concentration was usually associated with increase in heat production, although the decreased pyruvate concentration was coupled with formation of 2,3-bisphosphoglycerate. When inosine, dihydroxyacetone or D-glyceraldehyde was used as a substrate, an increase in the heat production rate was observed. Addition of methylene blue caused an oxygen uptake which was accompanied by a remarkable increase in heat production rate corresponding to about 160 kcal (670 kJ) per mol oxygen consumed. The value for heat production in red cells in the above-mentioned metabolic conditions was considered in relation to earlier known data on free energy and enthalpy changes of the different metabolic steps in the glycolytic pathway.     

The Organization of Craft Production at Vijayanagara, South India

This article examines the production of two classes of goods, textiles and ceramics, in the medieval South Indian empire of Vijayanagara. A general model for the organization of specialized craft production is presented in which productive organization is linked to political/administrative regulation of product manufacture, distribution, and use. Three modes of productive organization are defined: administered production, centralized production, and noncentralized production. Historic documentation is used to examine Vijayanagara textile production, and a centralized productive organization is proposed. Vijayanagara ceramic manufacture is assessed through archeological and ethnographic data, and a noncentralized production system is proposed.     

Spatial distribution of nectar production in a natural Echium vulgare population: Implications for pollinator behaviour

The distribution of trait values in many populations is not homogenous but creates a mosaic of patches. This may lead to differences in selection on the patch level compared to selection on the population level. As an example we investigated the spatial distribution of nectar production and its effects on pollinator behaviour in a natural population of Echium vulgare. Nectar production per flower, number of flowers and total nectar production showed a hierarchy and spatial aggregation as expressed by Gini coefficients and significant Moran's I values. Plants in patches of high nectar production received significantly more pollinator visits and had a significant emanating effect on pollinator visits of neighbouring plants. The same was true for plants in patches with high number of flowers. To disentangle these effects a path analysis was applied, which suggested that the direct effect of nectar production per flower although present, seems to be small compared to the effect of the number of flowers. Nectar production per flower affected pollinator visits mainly indirectly by way of total nectar production, which includes the effect of number of flowers. Assuming a minor pollinator-mediated selection for number of flowers, pollinator-mediated selection for total nectar production equals that for nectar production per flower. If so, the observed spatial structure of nectar production and its emanating effect on pollinator behaviour is of importance for natural selection. Plants of low nectar production occurring close to patches of plants with high nectar production benefited from the enhanced pollinator service of their neighbours while saving costs of increased nectar production. Consequently, plants with low nectar production may have a selective advantage at patch level while plants with high nectar production may have a selective advantage at population level. Results presented stress the importance of small-scale patterns for ecological relationships and evolutionary change.