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11.
A comparison of the lipid-lowering and intestinal morphological effects of cholestyramine, chitosan, and oat gum in rats 总被引:2,自引:0,他引:2
C D Jennings K Boleyn S R Bridges P J Wood J W Anderson 《Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine (New York, N.Y.)》1988,189(1):13-20
Cholestyramine, chitosan, and oat gum are lipid-lowering compounds. Cholestyramine use in humans may contribute to colonic adenocarcinoma; chitosan and oat gum are being studied in the rat to determine their potential for human use. To compare these compounds, we fed three groups of 10 male Sprague-Dawley rats one of the substances at 5% of diet with 1% cholesterol and 0.2% cholic acid; two other groups were fed cellulose with and without 1% cholesterol and 0.2% cholic acid. All groups had similar food intake and weight gains. Cholesterol feeding increased total liver lipids almost 3-fold and liver cholesterol concentration almost 10-fold. Cholestyramine, oat gum, and chitosan all significantly lowered liver cholesterol with cholestyramine feeding yielding levels identical to the noncholesterol-fed basal group. Chitosan and oat gum lowered liver cholesterol moderately. Cholestyramine and chitosan both significantly lowered serum cholesterol compared to the cellulose group. Oat gum was less effective. Hemoglobin and serum iron were similar in all groups except the oat gum group, which had decreased serum iron. Histological examination of small and large bowel with morphometry revealed statistically significant increases in both proximal and distal small bowel and distal large bowel mucosal thickness in the cholestyramine-fed group. No changes were noted in the proximal large bowel. Neither chitosan nor oat gum produced mucosal change other than an increase in the distal small bowel with the oat gum diet. Chitosan may have lipid-lowering effects similar to those of cholestyramine without the deleterious changes in intestinal mucosa. 相似文献
12.
Direct determination of homovanillic acid release from the human brain, an indicator of central dopaminergic activity 总被引:2,自引:0,他引:2
G W Lambert G Eisenhofer H S Cox M Horne V Kalff M Kelly G L Jennings M D Esler 《Life sciences》1991,49(15):1061-1072
The plasma concentration of the dopamine (DA) metabolite, homovanillic acid (HVA), is used as an indicator of central nervous system dopaminergic activity. Using percutaneously inserted catheters we were able to obtain blood samples simultaneously from the right and left internal jugular veins. Veno-arterial HVA plasma concentration differences combined with adjusted organ plasma flows were used, according to the Fick Principle, to determine the HVA overflow from the brain. The HVA overflow from the liver was also measured. HVA overflow from the brain represented 12% of the total body HVA production. A similar amount was released from the liver, illustrating the limited validity of peripheral plasma HVA measurements as an indicator of central dopaminergic activity. HVA release from the human brain displayed a degree of asymmetry, the overflow into the left internal jugular vein being 36% greater than that into the right. Cerebral venous blood flow scans indicated that cortical cerebral regions drained preferentially into the right internal jugular; by inference the higher HVA overflow on the left originated from dopamine-rich subcortical brain areas. Since HVA in plasma may arise from the metabolism of DA existing either as a neurotransmitter or a norepinephrine (NE) precursor we measured the internal jugular vein plasma concentrations of NE, and its metabolite dihydroxyphenylglycol (DHPG), to determine whether they displayed a similar pattern of release to HVA. The overflow of both NE and DHPG into the right internal jugular vein was approximately double that on the left. Since the overflow of HVA did not parallel that of NE and DHPG it may be inferred that the origin of much of the subcortically produced HVA is from dopaminergic neurons and not from the metabolism of precursor DA in noradrenergic neurones or cerebrovascular sympathetic nerves. 相似文献
13.
Summary Irradiation of the principal photosystem II light-harvesting chlorophyll-protein antenna complex, LHC II, with high light intensities brings about a pronounced quenching of the chlorophyll fluorescence. Illumination of isolated thylakoids with high light intensities generates the formation of quenching centres within LHC II in vivo, as demonstrated by fluorescence excitation spectroscopy. In the isolated complex it is demonstrated that the light-induced fluorescence quenching: a) shows a partial, biphasic reversibility in the dark; b) is approximately proportional to the light intensity; c) is almost independent of temperature in the range 0–30°C; d) is substantially insensitive to protein modifying reagents and treatments; e) occurs in the absence of oxygen. A possible physiological importance of the phenomenon is discussed in terms of a mechanism capable of dissipating excess excitation energy within the photosystem II antenna.Abbreviations chla
chlorophyll a
- chlb
chlorophyll b
- F0
fluorescence yield with reaction centers open
- Fm
fluorescence yield with reaction centres closed
- Fi
fluorescence at the plateau level of the fast induction phase
- LHC II
light-harvesting chlorophyll a/b protein complex II
- PS II
photosystem II
- PSI
photosystem I
- Tricine
N-[2-hydroxy-1,1-bis(hydroxymethyl)ethyl]glycine 相似文献
14.
Immunochemical analysis of the types Ia and Ib group B streptococcal polysaccharides 总被引:5,自引:0,他引:5
R E Schifferle H J Jennings M R Wessels E Katzenellenbogen R Roy D L Kasper 《Journal of immunology (Baltimore, Md. : 1950)》1985,135(6):4164-4170
The types Ia and Ib group B streptococcal type-specific polysaccharides have remarkable immunologic differences despite a great deal of structural similarity. Although these two complex polysaccharides differ only by a single glycosidic linkage, they are antigenically distinct. Furthermore, terminal sialic acid residues appear to be critical to the immunodeterminant on the type Ia polysaccharide, whereas the antigenicity of the type Ib polysaccharide does not show this dependence on sialic acid. In the current investigation we defined better the immunodeterminant of these polysaccharides. With homologous rabbit antiserum, the type Ia native and core polysaccharides demonstrated partial serologic identity, whereas the type Ib native and core polysaccharides demonstrated complete serologic identity. Surprisingly, the type I degalactosylated polysaccharide, degraded structure, was capable of reacting with a population of antibodies present in type Ia antiserum similar to the complete type Ia native polysaccharide, although demonstrating a reduced level of immunodeterminant expression. Unlike the reactions of the type Ia polysaccharides with homologous rabbit antiserum, the Ib native and core polysaccharides were able to react with identical populations of antibodies in type Ib-specific antiserum. A minor population of antibodies was demonstrated in the type Ib antiserum, which was reactive with the degalactosylated polysaccharide. That a population of antibodies reactive toward the degalactosylated polysaccharide is present in both type Ia and type Ib antisera suggests that the Iabc cross-reacting determinant is due to the presence of serum antibodies reactive with this trisaccharide repeating unit, which is shared by both the type Ia and the type Ib native and core polysaccharides. 相似文献
15.
Effect of herpes simplex virus types 1 and 2 on surface expression of class I major histocompatibility complex antigens on infected cells 总被引:13,自引:8,他引:5 下载免费PDF全文
S R Jennings P L Rice E D Kloszewski R W Anderson D L Thompson S S Tevethia 《Journal of virology》1985,56(3):757-766
Cytotoxic T lymphocytes (CTL) generated in C57BL/6 (H-2b) mice in response to infection with the serologically distinct herpes simplex virus type 1 (HSV-1) or type 2 (HSV-2) were cross-reactive against target cells infected with either serotype. However, HSV-2-infected cells were shown to be much less susceptible to CTL-mediated lysis, and analysis through the use of HSV-1 X HSV-2 intertypic recombinants mapped the reduced susceptibility to a region contained within 0.82 to 1.00 map units of the HSV-2 genome. The study reported here was undertaken to determine the possible reasons for the reduced susceptibility of HSV-2-infected cells to lysis by CTL. Competition for the specific lysis of labeled HSV-1-infected cells by either HSV-1- or HSV-2-infected, unlabeled inhibitor cells and frequency analysis of the CTL precursor able to recognize HSV-1- and HSV-2-infected cells suggested that the reduced susceptibility of HSV-2-infected cells to lysis could be explained, at least in part, by reduced levels of target cell recognition. A determination of the surface expression of the critical elements involved in target cell recognition by CTL following infection with HSV-1 or HSV-2 revealed that all the major HSV-specific glycoprotein species were expressed. Infection with both HSV-1 and HSV-2 caused a reduction in the expression of the class I H-2 antigens. However, this reduction was much greater following infection with HSV-2. This suggested that one important factor contributing to reduced lysis of HSV-2-infected cells may be the altered or reduced expression of the class I H-2 self-antigens. 相似文献
16.
Seaworth J. F.; Jennings T. J.; Howell L. L.; Frazier J. W.; Goodyear C. D.; Grassman E. D. 《Journal of applied physiology》1985,59(4):1145-1151
This study evaluated effects of various anti-G inflation pressures on cardiac volumes and the relationship of these volume changes to mean arterial pressure changes. Ventricular volumes were calculated using two-dimensional echocardiography. An anti-G suit was inflated to 2, 4, and 6 psi in the standing and supine positions for 10 male subjects. In the supine position, mean arterial pressure increased from base line for all three inflation pressures (P = 0.05). The end-diastolic volume increased after 2-psi inflation (P = 0.03). Cardiac output or stroke volume did not change. After standing, mean arterial pressure (P = 0.002), end-diastolic volume (P = 0.002), and stroke volume (P = 0.05) fell after suit deflation. Peripheral vascular resistance fell in the 2- and 4-psi inflation profiles. In the standing protocol, mean arterial pressure, end-diastolic volume, stroke volume, and cardiac output rose with all three inflation pressures (P less than 0.05). After reclining, heart rate increased (P = 0.02) and mean arterial pressure fell (P less than 0.05) in the 4- and 6-psi inflation profiles after suit deflation. Increases in mean arterial pressure are caused by increases in cardiac preload and cardiac output after inflation of the anti-G suit while subjects were standing. Increased cardiac preload was not consistently seen after inflation while subjects were supine. Changes in end-diastolic volume and mean arterial pressure were dependent on the pressure used to inflate the anti-G suit. 相似文献
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The effects of fasting and refeeding on the concentration of uncoupling protein in brown adipose tissue mitochondria have been investigated in mice. Fasting mice for 48 h led to a large decrease in the total cytochrome oxidase activity of the interscapular brown fat pad. Mitochondrial GDP binding and the specific mitochondrial concentration of uncoupling protein also fell on fasting. After 24 h refeeding both GDP binding and the mitochondrial concentration of uncoupling protein were normalized, but there was no alteration in the total tissue cytochrome oxidase activity. Fasting appears to induce a selective loss of uncoupling protein from brown adipose tissue mitochondria, which is rapidly reversible on refeeding. 相似文献
20.
Functional analysis of the effect of monoclonal antibodies on monkey liver phenylalanine hydroxylase. 总被引:3,自引:2,他引:1 下载免费PDF全文
An analysis of the effect of eleven monoclonal antibodies on the functional characteristics of monkey liver phenylalanine hydroxylase is presented. These eleven antibodies have been found to react with eight distinct regions on the phenylalanine hydroxylase protein. PH1 antibody inhibits enzyme activity, is dependent on phenylalanine for its binding, and appears to be related to structural changes occurring during phenylalanine activation of the enzyme activity. PH2 and PH3 antibodies stimulate enzyme activity, their binding is inhibited by lysolecithin and this group apparently is recognizing structures involved in lysolecithin activation of the enzyme activity. PH5, PH10, PH12 and PH6 recognise sites on phenylalanine hydroxylase affected by lysolecithin activation. 相似文献