Variation In Metabolic Activity Research Articles

CYP2A6 genetic variation and potential consequences

Human cytochrome P450 2A6 ( CYP2A6) has been shown to have large interindividual and interethnic variability in levels of expression and activity. This is thought to be largely due to genetic polymorphisms. In recent years, 13 genetic variants ( CYP2A6*1 – *11 and the gene duplication, *1×2) of CYP2A6 have been identified and a number of these have been shown to result in altered CYP2A6 enzyme activity. For example, there are alleles which result in variants that are in inactive (e.g. due to a gene deletion), have decreased activity (e.g. altered enzyme structure or transcriptional activity) or have increased activity (e.g. due to gene duplications). The resulting interindividual variation in metabolic activity may affect the metabolism of CYP2A6 substrates including nicotine, cotinine (the major metabolite of nicotine), several tobacco-specific procarcinogens, coumarin and many toxins. The frequencies of the CYP2A6 alleles vary considerably among different ethnic populations, which may partially explain the interethnic variability found in CYP2A6-related metabolic activity (e.g. nicotine metabolism), behaviors (i.e. smoking) and disease (i.e. lung cancer). Investigations of the genetic variation of CYP2A6 and its resulting effects on metabolism and health consequences are still fairly early; this review summarizes what is presently known about CYP2A6, its genetic variants and their clinical consequences.

Estimating oxygen exchange across the air-water interface of a hypereutrophic lake

Patterns of estimates of oxygen flux (J) across the air–water interface of hypereutrophic Onondaga Lake, NY, U.S.A., are characterized for time scales ranging from diel to seasonal for an 8-month period. The analysis is supported by a high frequency (most often hourly) monitoring program, conducted with a robotic buoy, that included measurements of dissolved oxygen (DO), temperature, and fluorometric chlorophyll a in the lake's surface waters, vertical profiles of DO through the epilimnion, and wind speed and solar radiance. The magnitude and direction of J is demonstrated to vary dramatically at diel, day-to-day, and seasonal time scales. Thus, large errors in estimates of J may result from extrapolating flux calculations made from short-term data to longer time periods. The variations in J were driven by variations in metabolic activity and meteorology, and were mediated by departures from equilibrium DO concentrations and wind-driven turbulence. Extended periods of high J values are shown to coincide with intervals of large departures from equilibrium DO concentrations, but day-to-day differences are driven mostly by variations in wind. A distinct diel pattern of J estimates is manifested for average conditions, with substantially higher J values during daylight hours. This pattern reflects the common diel patterns of the drivers of both higher DO oversaturation and wind speed over those hours. It is demonstrated that the magnitude of J is substantial relative to net changes in the epilimnetic DO pool, and thus must be accommodated accurately in estimates of primary production and community respiration that are to be based on diel monitoring of DO in the water columns of productive lakes.

Improved attachment and spreading in primary cell cultures of the eastern oyster, Crassostrea virginica.

At present, establishment of a cell line from bivalve molluscs has been unsuccessful, and in vitro work is limited to primary cell cultures. We sought to improve attachment and spreading of cells of the eastern oyster, Crassostrea virginica, to aid primary cultures and to assist development of a bivalve cell line. Our objectives were to examine the effects of substrate on ventricle cell viability, attachment, and spreading by testing of collagen I, collagen IV, fibronectin, laminin, poly-D-lysine, and two types of uncoated tissue culture plates (Falcon and Corning). Experiments were conducted by incubating cells with the various substrates for 24 h and 5 d. An assay with a tetrazolium compound (MTS) was used to estimate cell numbers based on metabolic activity. Although differences in MTS assay values for substrate effect on cell viability were detected at 24 h and at 5 d (P > 0.0001), these were attributed to variations in metabolic activity due to different levels of attachment and spreading among treatments. Differences among treatments were detected in attachment and spreading at 24 h and 5 d (for all, P > 0.0001). At 24 h, poly-D-lysine induced the highest levels of attachment and spreading; no other factor performed better than the uncoated Falcon substrate, and collagen I performed most poorly. At 5 d, poly-D-lysine and the uncoated Corning substrate induced significantly higher levels of attachment and spreading than did the uncoated Falcons substrate, and collagen I performed most poorly. From these results, poly-D-lysine best promoted cell attachment and spreading. Fibronectin (at 24 h) and laminin (at 5 d) warrant further study. Along with improvements in medium composition, future work should involve screening of other attachment factors and combinations of factors, including those of bivalve origin.

Activity of marine bacteria under incubated and in situ conditions

AME Aquatic Microbial Ecology Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials AME 20:213-223 (1999) - doi:10.3354/ame020213 Activity of marine bacteria under incubated and in situ conditions Evelyn B. Sherr*, Barry F. Sherr, Crystal T. Sigmon College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis, Oregon 97331-5503, USA *E-mail: sherrb@oce.orst.edu ABSTRACT: We evaluated the extent to which the average metabolic activity of open ocean bacterioplankton changed during 2 to 3 d incubations of 1 μm filtered seawater at in situ temperature. Indices of bacterial activity during incubation experiments were compared to those of in situ bacterioplankton, which were repeatedly sampled at each oceanic site. Indices included: total and cell-specific incorporation rates of tritiated leucine ([3H]-Leu) and thymidine ([3H]-TdR), ratio of Leu to TdR incorporation, and percentage of highly active cells as determined by detectable reduction of the fluorogenic dye, 5-cyano-2,3-ditolyl tetrazolium chloride (CTC). Patterns of change in metabolic activity were similar for experiments with water collected in 3 regions: midshelf, slope, and offshore, off the Oregon coast, USA, and incubated at in situ temperatures of 9.5 to 18°C. At the beginning of the experiments, cell-specific incorporation rates of [3H]-Leu and [3H]-TdR were lower compared to in situ rates, but after 19 to 28 h, incorporation rates of [3H]-Leu and [3H]-TdR increased dramatically, by more than an order of magnitude, compared to in situ activity. When scaled to the abundance of CTC positive (CTC+) cells, rates of Leu and TdR incorporation were 2.8- to 8.1-fold higher during the incubations compared to activity of in situ CTC+ cells. In this study, marine bacteria in 1 μm, incubated filtrate exhibited a much larger variation in metabolic activity than did in situ bacterioplankton. In addition, the proportion of CTC+ cells was closely related to cell-specific rates of Leu and TdR incorporation. KEY WORDS: Marine bacteria · Incubation · Metabolism · Cell-specific activity · CTC Full text in pdf format NextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in AME Vol. 20, No. 3. Publication date: December 30, 1999 Print ISSN: 0948-3055; Online ISSN: 1616-1564 Copyright © 1999 Inter-Research.

Microcalorimetric measurements carried out on isolated tumorous and nontumorous tissue samples from organs in the urogenital tract in comparison to histological and impulse-cytophotometric investigations

In this comparative study, microcalorimetric measurements were carried out on a total of 96 tumorous and nontumorous tissue samples taken from organs of the urogenital tract using a thermal activity monitor (TAM). Changes in the heat emission of the tissue samples were measured at 1-min intervals and graphically displayed as a function of time. The aim of the study was to compare the microcalorimetric results with impulse-cytophotometric and histological findings and provide evidence for the metabolic activity of tumorous and nontumorous tissue. In order to obtain the variation in metabolic activity, the maxima (Pmax) of the curves were determined as a value of the maximum thermal power of a tissue sample, the mean values (P) were determined by the mean thermal power and the contour integrals (W) were defined by the behavior of the energy reserves and their mobilization. The first part of the study was carried out to investigate whether tumorous and nontumorous tissue samples differ in general according to their metabolic activity. We discovered, using the parameters described above, that in general tumorous tissue exhibited a higher metabolic activity than nontumorous tissue samples. For example, both W and P in tumorous prostate tissue samples were eightfold higher and the (Pmax) value was 8.4-fold higher than in normal tissue. Additional investigations on testicle and kidney tissues were performed to find a possible correlation between microcalorimetric results and histological grading. We found that an increasing malignancy correlated with a higher metabolic activity of the tissue. Based upon these results we were able to differentiate the various histological gradings of these tumorous tissues by microcalorimetric measurements. The results show it is possible to differentiate between normal and tumorous tissue samples by microcalorimetric measurement based on the distinctly higher metabolic activity of malignant tissue. Furthermore, microcalorimetry allows a differentiation and classification of tissue samples into their histological grading. With the help of microcalorimetry, it might be possible in future to detect and record the metabolic processes of isolated tissue structures and changes in these activities as a result of medical intervention such as cytostatic treatment.

Body composition and nutrient reserves of arctic caribou

We determined seasonal changes in body mass and composition of arctic caribou (Rangifer tarandus granti) in relation to age and reproductive status. Chemical composition was determined for 37 caribou calves from the Central Arctic Herd ranging from 1 to 134 days of age and for 15 adult females collected from the same herd in October, May, and July. Body composition of 5 fetuses from the Central Arctic Herd, 13 calves from the Porcupine Herd, and 10 captive male reindeer (R. t. tarandus) was determined for comparison. Between October 1989 and May 1990, body fat and protein of adult females declined by maxima of 45 and 29%, respectively; an additional 32% of fat was lost between May and July. Mobilization of large amounts of fat and protein suggests winter undernutrition. Chemical composition and growth patterns of calves did not differ between the herds. The growth rate of Central Arctic Herd calves was high during the first 28 d post partum (402 g/d), but both growth rate and fatness declined between 4 and 6 weeks of age (to 306 and −18.3 g/d, respectively), perhaps in response to insect harassment. Birth masses of males and females did not differ, but by autumn, male calves were 9.1 kg heavier than females. Chemical components (water, fat, protein, ash) were highly correlated with body mass, ingesta-free body mass, and carcass mass. Percentages of fat and water were inversely related, but the intercept decreased with age. Marked seasonal hypertrophy of liver and kidneys was noted in caribou, suggesting the presence of mobilizable protein reserves. Seasonal changes in organ masses may also reflect variations in metabolic activity and nutrient intake.

Metabolic activity and proliferation of CHO cells in hydroxyethyl methacrylate-methyl methacrylate (HEMA-MMA) microcapsules.

To better understand encapsulated cell behaviour, Chinese Hamster Ovary (CHO) fibroblasts were encapsulated in HEMA-MMA microcapsules and short-term (<2 wks) proliferation and changes in metabolic activity were investigated in vitro. CHO cells were observed to undergo rapid proliferation in the first week following encapsulation after which a growth arrest was obtained at approximately 3500 cells/capsule. The cell growth was localized in aggregates in the capsule core, resulting in high local cell density but low cell density in the whole capsule interior (approximately 10(7) cells/mL). The total metabolic activity, as determined by the MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium) assay, within the microcapsules increased in the first week, with no significant change afterwards. A broad variation in metabolic activity among the individual capsules was obtained. Supplementing the cell suspension with 20% Ficoll 400 during the encapsulation process resulted in significantly higher morphological uniformity among the individual capsules (with reduced capsule wall thickness and eccentricity); however, this did not change the extent of heterogeneity in metabolic activity. We conclude that viability and proliferation ability (at least to a limited extent) of CHO cells are maintained in HEMA-MMA microcapsules. The local cell growth and subsequent growth arrest remain issues to be addressed in order to obtain better utilization of the microcapsule core volume. Alternatively, small diameter (< 400 microns as opposed to the present approximately 750 microns diameter) capsules are necessary.

Regional variation in adipose tissue lipoprotein lipase activity: association with plasma high density lipoprotein levels

The associations of adipose tissue lipoprotien lipase (AT-LPL) activity with body fatness and plasma lipoprotein levels were studied in the light of the recently described regional differences in AT-LPL activity. In this regard, heparin-releasable LPL activity was measured in abdominal and femoral adipose tissues of 29 pre-menopausal women. Body fatness variables were all positively correlated with abdominal and femoral AT-LPL activities expressed per 10(6) cells. However, abdominal and femoral AT-LPL activities expressed per unit of cell surface displayed divergent association patterns with body fatness and plasma lipoprotein levels. Indeed, only abdominal AT-LPL activity remained significantly correlated with body fatness variables after adjustment for fat cell surface. Furthermore, whereas abdominal AT-LPL activity tended to be negatively correlated with plasma HDL-cholesterol levels, femoral AT-LPL activity was positively correlated with plasma HDL2-cholesterol (r = 0.40, P less than 0.05) concentration and with the HDL2-cholesterol/HDL3-cholesterol ratio (r = 0.49, P less than 0.01). These results demonstrate the importance of taking into account the regional variation in metabolic activity of adipose tissue when studying its associations with body fatness, and with plasma lipoprotein levels. The lack of association between abdominal AT-LPL activity and plasma HDL2-cholesterol levels lead us to suggest that AT-LPL activity may not be causally related with plasma HDL levels.

Densitometric analysis of cytochrome oxidase in ischemic rat brain

Elevated brain lactate during incomplete ischemia is thought to contribute to the irreversibility of cell damage by interference with mitochondrial respiratory function, that should be evident in reduced cytochrome oxidase (CO) activity. In this study changes in the density of CO staining in a stroke model in the rat were assessed. Brains were analyzed subsequent to 30 min of ischemia followed by 30 min of reperfusion. The effects of postischemic treatment with sodium dichloroacetate (DCA) — a compound used to decrease lactate, were also evaluated. Examination of lateral cortex, hippocampus, and corpus striatum showed different intensities of CO in a distribution consistent with known regional variations in metabolic activity of the forebrain. Known laminar staining patterns in lateral cortex and areal patterns in the hippocampus were also confirmed. Comparable regions in ischemic forebrain were stained less densely for CO than controls. Image analysis demonstrated that the density of CO: (a) was greater in lateral cortex than hippocampus in control; (b) in ischemics was reduced by an equal degree in cortex and hippocampus; (c) lacked regional uniformity in ischemic rats; and (d) was not changed by DCA treatment in the majority of cases of ischemia. Our results suggest that lactate may not be the major determinant of ‘selective vulnerability’. Despite elevated lactate levels in lateral cortex when compared to hippocampus in a previous study, the proportionate decrease in CO activity in lateral cortex and hippocampus was equal. However, there was a considerable decrease in CO activity subsequent to high brain lactate and some ischemic hemispheres appeared to respond to DCA treatment. Therefore, the role of excessive lactate in the exacerbation of ‘selective vulnerability’ warrants further evaluation. CO histochemistry can be used successfully to determine the distribution of pathology and the quality of fixation of ischemic forebrain. Densitometric measurements allowed comparative assessment of degrees of injury and the effects of treatment in discrete anatomical regions. This kind of analysis may allow localization of pathology within specific cellular circuits.

Unilateral odor deprivation: effects on the development of staining for olfactory bulb succinate dehydrogenase

Littermate rat pups underwent either unilateral surgical occlusion of the right external naris or sham surgery on postnatal Day 1. At 4-, 8-, 12-, 20- or 30-days postpartum, olfactory bulb sections were histochemically reacted to reveal either succinate dehydrogenase (SDH) or cytochrome oxidase (CO) activity. Microdensitometry was used to determine levels of staining in glomeruli and the external plexiform layer at standardized locations within the bulb. In experimental subjects asymmetries in left/right bulb SDH staining patterns were detected as early as Day 4, suggesting that the deprivation procedure resulted in quite rapid changes in the metabolic function of olfactory bulb cells. Control animals did not exhibit left/right differences in bulb staining, but inter-glomerular and regional variations in staining were observed throughout the early developmental period. Understanding these early variations in metabolic activity may be important for a complete understanding of olfactory bulb maturation.

Histochemical demonstration of sensory maps in the rat and mouse cerebral cortex

The variations in metabolic activity of two mitochondrial enzymes (succinate dehydrogenase and cytochrome oxidase) have been mapped histochemically in rat and mouse brains prepared in such a manner as to reveal the whole surface of the neocortex in one plane. In each species the enzymes appear to outline the complete body representation map in the somatosensory cortex as well as the primary visual and auditory areas.

Biomass and activity of benthic fauna on the fladen ground (northern North Sea)

During May 1983 the abundance and biomass of macrobenthos and meiobenthos populations, as well as the metabolic activity (shipboard incubated and in situ measured respiration, and potential respiration activity by ETS) were studied in the Fladen Ground area. Macrofauna showed an abundance of 4500 specimens per m 2; the corresponding biomass was 10.7 g ash-free dry weight per m 2. The bivalve Arctica islandica, with 12 specimens per m 2 contributed 7.2 g to this biomass. Average meiofauna numbers, 0.9·10 6 per m 2 were low; a meiofaunal biomass of only 0.3 g was estimated. Depending on the method applied, large variations in metabolic activity were found. Results from shipboard incubation experiments probably present a large underestimate. The in situ bell-jar experiments showed an average oxygen uptake of 1010 μmol O 2·m −2·h −1, equalling a carbon demand of 7.3 gC·m −2·month −1 in May. ETS measurements gave a 3 times higher estimate. Taking into account that macrofaunal and meiofaunal abundance and biomass, as well as bottom temperatures, show minimum values in spring, an annual carbon mineralization by the benthic system of 50 to 70 gC·m −2 is suggested. This would mean that about one third of the total primary produced organic matter is channelled into the benthic system.

Species difference in circadian [ 14C]2-deoxyglucose uptake by suprachiasmatic nuclei

Hamsters exhibited a circadian variation in metabolic activity determined by [ 14C]2-deoxyglucose uptake in the suprachiasmatic nuclei, as has been previously reported for rats. The 13-line ground squirrel, a diurnal rodent, did not show a circadian variation in metabolic activity. The data are consistent with the hypothesis that there is a basic difference in the functional organization of the suprachiasmatic nuclei in nocturnal and diurnal animals.

The hormone synthesis of hyperfunctioning thyroid nodules in euthyroid patients.

ABSTRACT Among fifty consecutive patients operated on for non-toxic goitre, ten were shown to have solitary, hyperfunctioning thyroid nodules. Seven days before operation the patients were given a tracerdose of Na125I orally; all had an increased iodine discharge from the thyroid gland and elevated [125I]PBI. Chromatography of the sera revealed 125I peaks corresponding only to the T4 and T3 bands. Total 1251 concentration ratio nodular/paranodular tissue varied between 11.1 and 0.4 indicating a great variation in metabolic activity in "hot" nodules in the different goitres. The thyroid tissue was chromatographically investigated; the [125I]MIT/DIT ratio of the "hot" nodules was not negatively correlated to the 127I concentration of the tissue as is the case for "cold" adenomata. Significantly more [125I]T4 and [125I]T3 were found in the nodules compared to paranodular tissue. In contrast to simple non-toxic goitre the [125I]T3/T4 ratio in the "hot" nodules was lower than in paranodular tissue in spite of a lower 127I concentration in the former. Thus the hormone synthesis of "hot" nodules was unrelated to tissue iodine concentration.

An interpretation of the results of measurements of the uptake of 32P in human tumours.

Abstract Continuous uptake measurements have been made following a single oral administration of 32P-orthophosphate, using Geiger counters implanted in normal and malignant human tissues and the resulting recordings have been analysed statistically using a computer. After the initial equilibration period the experimental data are described satisfactorily by a single exponential function whose parameters may be modified by hormone administration. Fluctuations in radioactivity occur whose variance is significantly greater for tumours than for normal resting tissue. The data have been examined for possible periodicities; both normal and malignant tissue exhibit increased variance at low frequencies but in only one out of 14 cases (breast tumours) is a regular cycle apparent, the rhythm being circadian. The two most likely causes of the observed fluctuations in radioactivity are changes in blood flow or variations in metabolic activity within the tissue volume being measured. When the blood only was labelled ...

Physiological and Biochemical Effects of Atmospheric Oxidants on Plants

Photochemically produced oxidants in the atmosphere cause injury to plants primarily through inhibition of basic metabolic processes. Plants vary in their response to the oxidants and this variation must be dependent in part on the variation in metabolic activity with age or environmental conditions for growth, to a large degree not understood. Data are presented in this paper to show: (1) The changes in permeability of leaf tissue to exogenous substrate and in catabolic utilization of this substrate after exposure of plants to ozone but before visible symptoms appear; (2) The change in leaf carbohydrates as a result of exposure to ozone; (3) The protective effect of red light (700 mμ) during exposure of bean plants to peroxyacetyl nitrate (PAN); (4) The correlation of sulfhydryl (SH) content in bean leaf tissue with age of plants and light regime; and (5) Effect of light regime and age of plants on incorporation of C14 from C14-PAN by bean leaf tissue.

Semen characteristics and fertility in the bull

1. Certain characteristics of bull semen have been examined at four artificial insemination centres in England. One hundred and twenty-one samples of semen, comprising 168 ejaculates from seventysix bulls of seven breeds, were examined. The semen from 119 tested samples was subsequently used to inseminate 4604 cows.The following semen characteristics were studied: volume of ejaculate; concentration of spermatozoa; incidence of dead spermatozoa; incidence of morphologically abnormal spermatozoa; initial fructose concentration; resistance of spermatozoa to temporature shock; methylene-blue reduction; O2uptake; fructose utilization; visual evaluation of motility; impedance change frequency; and fertilizing capacity (conception rate).A clinical examination was made of the reproductive organs of each bull.2. Variations in the concentration of living spermatozoa and in the incidence of dead spermatozoa were found to account for most of the variations in the metabolic activity of semon: they also largely explained differences in physical activity as assessed by visual estimation of motility or by impedance change frequency.3. Although the rates of methylene-blue reduction, O2uptake and fructolysis showed a close correlation with the numbers of living spermatozoa present, O2uptake and fructolysis per living cell decreased with increasing cell concentration.4. Variations in metabolic activity showed no correlation with variations in the morphological characteristics of the spermatozoa, except in the case of spermatozoa with bent tails. These forms occurred in some samples as a result of staining treatment, but their incidence was positively correlated with the O2uptake and fructolysis per living cell.5. There was evidence that highly active spermatozoa are more resistant to temperature shock than less active spermatozoa.