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1.
Vincent E. Vena Tri Huynh Lac Robert F. Wideman Jr. 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1990,160(1):7-16
Summary Mammalian glomerular filtration rate (GFR) autoregulation can be impaired by protocols that inhibit tubuloglomrular feedback, such as high sodium intake. Domestic fowl were fed diets containing either high sodium (0.39% Na: High-Na Group) or low sodium (0.03% Na: Low-Na Group). An arterial snare was used to reduce renal arterial perfusion pressure (RAPP) in a stepwise fashion to evaluate GFR autoregulation. Absolute sodium excretion, fractional sodium excretion (FENa), and ambient systemic arterial blood pressure were significantly elevated in the High-Na Group when compared with the Low-Na Group, and pressure natriuresis was abolished by the Low-Na diet. However, GFR autoregulatory profiles were identical in birds fed High-Na and Low-Na diets, suggesting that tubuloglomerular feed-back does not contribute significantly to avian GFR autoregulation. Filtering glomeruli were stained in vivo with alcian blue dye to determine if RAPP-induced reductions in GFR are associated with cessation of filtration (glomerular intermittency) by a portion of the nephron population. RAPP was held below the GFR autoregulatory range (experimental group) or was at ambient systemic arterial pressure (control group) during glomerular staining. Reducing RAPP below the autoregulatory range reduced GFR by 50%, but similar glomerular size distribution profiles were observed for experimental and control groups. These results indicate that sustained glomerular intermittency does not contribute to the decrease in GFR when RAPP is reduced below the autoregulatory range.Abbreviations
BW
body weight
-
C
control
-
E
excretion
-
FE
fractional excretion
-
FF
filtration fraction
-
GFR
glomerular filtration rate
-
PAH
p-amino hippuric acid
-
RAPP
renal arterial perfusion pressure
-
RPF
renal plasma flow
-
RT
reptilian-type
-
SNGFR
single nephron glomerular filtration rate
-
U
OSM
urine osmolarity
-
UFR
urine flow rate 相似文献
2.
《Chronobiology international》2013,30(5):301-308
Catheters were placed in the jugular vein and femoral artery of male Sprague-Dawley rats and connected to a specially designed perfusor for continuous constant infusion of 0.9% NaCl and a syringe to perform simultaneous and intermittent blood collections. This permitted continuous 24-h study of renal hemodynamics, estimated by inulin (Cin) and p-amino-hippuric acid (CPAH) clearances; Cin represents glomerular filtration rate and CPAH renal plasma flow. Animals were individually housed in metabolism cages in a controlled environment with light/dark 12:12 h. Urine was collected every 4 h (12:00, 16:00, 20:00, 24:00, 04:00, and 08:00) and blood sampled at the midpoint of urine collection periods. Urine and plasma sodium, potassium, inulin, and PAH were spectrophotometrically assessed. During continuous infusion of isotonic saline, Cin exhibited circadian changes with large decrease between 12:00 and 20:00 h (0.9 ± 0.2 ml/min) and acrophase at 00:30 h. Rhythmicity in CPAH was similar with the minimum between 16:00 and 20:00 h (2.5 ± 0.3 ml/min) and peak between 00:00 and 04:00 h (acrophase at 00:25 h). Water and electrolyte excretion were also circadian rhythmic with a similar nighttime enhancement and daytime minimum. Such circadian changes persisted during continuous 0.9% NaCl infusion for several consecutive days. The unanesthetized, unrestrained rat model enables investigations in renal chronopharmacology and chronotoxicology. 相似文献
3.
Summary In steady state, attained by continuous aeration after oxygen saturation of water in a bubble column, vertical composition distribution of liquid and gas phases has been determined. It has been assumed that, as a result of absorption at the bottom of the column, desorption in the upper section and vertical dispersion of dissolved oxygen flux, a closed oxygen circulation is created. Determination of the axial dispersion coefficient from hydrodynamic and oxygen transfer data verifies the mathematical model proposed. The results allow conclusions to be drawn about supersaturation and desorption and other phenomena expected in biological systems.Abbreviations
C[-]
Dimensionless oxygen concentration Unit=0.21 bar oxygen partial pressure or dissolved oxygen level in equilibrium with latter
-
E[m2/s]
Axial dispersion coefficient
-
F[m2]
Horizontal cross-section area
-
k
L
a[s-1]
Overall oxygen transfer coefficient
-
u; u
2[m/s; cm/s]
Superficial velocity: related to state of bubbles leaving the sparger
-
x; x
atm[-]
Signal registered in the experiment; signal recorded in O2 saturated water, or water vapor saturated air stream, at temperature identical to the experiment under atmospheric pressure
-
y[m]
Water column height
- [s-1]
Dimensionless oxygen flux
Indices
a
asorption
-
d
desorption
-
g
gas
-
l
liquid
-
k
dispersion
-
m
measured value/in the case of hydrodynamically measured E/
Dedicated to Professor Dr. H. J. Rehm on the occasion of his 60th birthday 相似文献
4.
A design equation for immobilized glucose isomerase (IGI) packed bed reactor is developed assuming enzyme deactivation and substrate protection. The developed equation is used to simulate the performance of the reactor at various temperatures (50–80 °C). Enzyme deactivation is significant at high temperature. Substrate protection showed to have significant effect in reducing enzyme deactivation and increasing the enzyme half-life. Factors affecting the optimum operating temperature are discussed. The optimum operating temperature is greatly influenced by the operating period and to a lesser extent with both initial glucose concentration and glucose conversion.Two modes of reactor operation are tested i.e., constant feed flow rate and constant conversion. Reactor operating at constant conversion is more productive than reactor operating at constant flow rate if the working temperature is higher than the optimum temperature. Although at lower temperatures than the optimum, the two modes of operation give the same result.List of Symbols
a
residual enzyme activity
-
E [mg/l]
concentration of active enzyme
-
E
a
[kJ/mole]
activation energy
-
E
0
[mg/l]
initial concentration of active enzyme
-
k [Specific]
kinetic parameter
-
k
d
[h–1]
first order thermal deactivation rate constant
-
k
e
equilibrium constant
-
k
m
[mole/l]
apparent Michaelis constant
-
k
p
[mole/l]
Michaelis constant for product
-
k
s
[mole/l]
Michaelis constant for substrate
-
k
0
[Specific]
pre-exponential factor
-
Q [1/h]
volumetric flow rate
-
¯Q [1/h]
average volumetric flow rate
-
R [kJ/mol·k]
ideal gas constant
-
s [mole/l]
apparent substrate concentration
-
s [mole/l]
substrate concentration
-
s
e
[mole/l]
substrate concentration at equilibrium
-
s
0
[mole/l]
substrate concentration at reactor inlet
-
p [mole/l]
product concentration
-
p
e
[mole/l]
product concentration at equilibrium
-
P
r
[mole fructose/l·h]
reactor productivity
-
T [k]
temperature
-
t [h]
time
-
t
p
[h]
operating time
-
V [l]
reactor volume
-
v [mole/l·h]
reaction rate
-
v [mole/l]
reaction rate under enzyme deactivation and substrate protection
-
v
m
[mole/l·h]
maximum apparent reaction rate
-
v
p
[mole/l·h]
maximum reaction rate for product
-
v
s
[mole/l·h]
maximum reaction rate for substrate
-
x
substrate fractional conversion
-
x
e
substrate fractional conversion at equilibrium
Greek Symbols
effectiveness factor
-
mean effectiveness factor
-
substrate protection factor
-
[h]
residence time
-
[h]
average residence time
-
0
[h]
initial residence time 相似文献
5.
Infusion of prostaglandin E1 (PGE1) into the renal artery of anesthetized dogs (1.03 μg/min) caused increases in urine flow rate (V), renal plasma flow (RPF) and renin secretion rate without any change in mean arterial blood pressure (MABP), whereas infusion of prostaglandin F2α (PGF2α), (1.03 μg/min) caused no consistent change in V, RPF, or renin secretion rate. Infusion of prostaglandin E2 (PGE2) (1.03 μg/min) into the renal artery of “non-filtering” kidneys caused renin secretion rate to rise from 567.7 ± 152.0 U/min(M ± SEM) during control periods to 1373.6 ± 358.5 U/min after 60 minutes of infusion of PGE2 (P < 0.01), without significant change in MABP (P > 0.1). The data suggest that PGE1 and PGE2 play a role in the control of renin secretion. The data further suggest that PGE may control renin secretion through a direct effect on renin-secreting granular cells. 相似文献
6.
D. G. Butler M. Z. Alia Cadinouche 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1995,165(5):348-358
Renal function was observed in freshwater North American eels (Anguilla rostrata LeSueur) 2 weeks after the removal of the corpuscles of Stannius. There was a positive linear correlation between glomerular filtration rates and urine flow rates in both sham-operated and stanniectomized eels but there was no difference in slope or elevation between the two groups nor did urine flow rates ever exceed glomerular filtration rates. Osmolar clearance and free-water clearance were unchanged following stanniectomy. Plasma Ca2+ and K+ concentrations increased and plasma Mg2+, phosphate, Na+ and Cl- concentrations decreased following stanniectomy. Plasma ultrafilterable Ca increased and ultrafilterable Mg decreased after stanniectomy but neither changed relative to its total plasma concentration. Stanniectomy was followed by a decreased renal tubular reabsorption of Mg2+ relative to the amount filtered (C
Mg/C
In); the same applies to C
Na/C
In. Even though the filtered load of Ca increased in conjuction with the predictable hypercalcemia, there was no change in the fraction of filtered Ca reabsorbed. Net tubular secretion of phosphate was observed in both sham-operated and stanniectomized cels together with a slight increase in C
phos/C
In following stanniectomy. Some or all of these changes in plasma electrolytes and/or the modified renal transport of Na+, Mg2+ and possibly phosphate may be caused by the changes in cardiovascular function that were recently shown to follow stanniectomy.Abbreviations
CSX
Stanniectomized/stanniectomy
-
ER
endoplasmatic reticulum
-
FW
fresh water
-
GFR
glomerular filtration rate
-
Pi
inorganic phosphate
-
RAS
renin-angiotensin system
-
SHM
sham-operated
-
SW
sea water
-
UFR
urine flow rate
-
U/P ratio
urine/plasma ratio 相似文献
7.
B. D. S. Khalsa J. M. Goldinger S. K. Hong 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1984,154(2):119-123
Summary The renal handling of several organic anions has been investigated in the salamanderNecturus maculosus. Uptake ofP-aminohippurate (PAH) by theNecturus kidney slice was inhibited by iodoacetamide (IA), ouabain, removal of sodium from the medium (Table 1) and by probenecid, N-(4-azido-2-nitrophenyl)-2-aminoethyl sulfonate (NAP-taurine), and 4-acetamido-4-isothiocyano-2,2-disulfonic stilbene (SITS) (Fig. 4), all of which also inhibit PAH uptake in the mammalian kidney. The sulfonic anions, NAP-taurine and phenol red (PSP), were not actively taken up by the slice (Table 1), and PSP had no effect on PAH uptake. NAP-taurine, on the other hand, competitively inhibited PAH uptake (Fig. 5) withK
i=2.2×10–5 M. The maximum inhibitory effect was 50% of control uptake at NAP-taurine concentrations greater than 10–5 M, whereas a maximum of 80% inhibition was obtained with probenecid (Fig. 4). These results support the idea that theNecturus kidney is not able to actively secrete sulfonic anions. The interaction of NAP-taurine with the PAH uptake system may be due to structural features other than the sulfonic acid moiety. There appear to be two components of PAH uptake, one which is sensitive to NAP-taurine, and one which is not.Abbreviations
PAH
p-aminohippurate
-
PSP
phenolsulfophthalein (phenol red)
-
NAP
taurine N-(4-azido-2-nitrophenyl)-2-aminoethyl sulfonate
-
SITS
4-acctamido-4-isothiocyano-2,2-disulfonic stilbene
-
S/M
slice to medium ratio:IA iodoacctamide 相似文献
8.
L. A. Decosterd A. Karagiannis J. -M. Roulet N. Blaz M. Appenzeller T. Buclin P. Vogel J. Biollaz 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1997,703(1-2)
PAH (N-(4-aminobenzoyl)glycin) clearance measurements have been used for 50 years in clinical research for the determination of renal plasma flow. The quantitation of PAH in plasma or urine is generally performed by colorimetric method after diazotation reaction but the measurements must be corrected for the unspecific residual response observed in blank plasma. We have developed a HPLC method to specifically determine PAH and its metabolite NAc-PAH using a gradient elution ion-pair reversed-phase chromatography with UV detection at 273 and 265 nm, respectively. The separations were performed at room temperature on a ChromCart® (125 mm×4 mm I.D.) Nucleosil 100-5 μm C18 AB cartridge column, using a gradient elution of MeOH–buffer pH 3.9 1:99→15:85 over 15 min. The pH 3.9 buffered aqueous solution consisted in a mixture of 375 ml sodium citrate–citric acid solution (21.01 g citric acid and 8.0 g NaOH per liter), added up with 2.7 ml H3PO4 85%, 1.0 g of sodium heptanesulfonate and completed ad 1000 ml with ultrapure water. The N-acetyltransferase activity does not seem to notably affect PAH clearances, although NAc-PAH represents 10.2±2.7% of PAH excreted unchanged in 12 healthy subjects. The performance of the HPLC and the colorimetric method have been compared using urine and plasma samples collected from healthy volunteers. Good correlations (r=0.94 and 0.97, for plasma and urine, respectively) are found between the results obtained with both techniques. However, the colorimetric method gives higher concentrations of PAH in urine and lower concentrations in plasma than those determined by HPLC. Hence, both renal (ClR) and systemic (ClS) clearances are systematically higher (35.1 and 17.8%, respectively) with the colorimetric method. The fraction of PAH excreted by the kidney ClR/ClS calculated from HPLC data (n=143) is, as expected, always <1 (mean=0.73±0.11), whereas the colorimetric method gives a mean extraction ratio of 0.87±0.13 implying some unphysiological values (>1). In conclusion, HPLC not only enables the simultaneous quantitation of PAH and NAc-PAH, but may also provide more accurate and precise PAH clearance measurements. 相似文献
9.
Juliet R. Roberts 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1991,161(6):620-625
Summary Renal function was measured in an Australian parrot, the galah (Cacatua roseicapilla), which is distributed across the most arid regions of the continent. Renal function was assessed by the constant infusion technique in hydrated galahs, and in both hydrated and dehydrated birds by means of osmotic minipumps. The glomerular filtration rate (GFR) of the galah is similar to calculated values for a bird of its size. However, effective renal plasma flow tended to be low and therefore filtration fraction was high. Water deprivation for a period of 5 days caused a decrease in body weight and an increase in plasma osmolality and haematocrit. The GFR declined steadily such that weight-specific GFR on the fifth day of water deprivation was 68% of control values. The water deprivation produced a 2.6-fold elevation of plasma arginine vasotocin (AVT) levels, with an overall sensitivity of release of AVT of 0.16±0.02 pg·ml-1 per mOsm·kg-1. The galah possesses renal mechanisms which enable it to conserve significant amounts of water during times of water stress.Abbreviations
AVT
arginine vasotocin
-
EDTA
ethylene diamine tetra-acetate
-
GFR
glomerular filtration rate
-
P
AVT
plasma arginine vasotocin
-
PAH
para-amino hippuric acid
-
SNGFR
single nephron glomerular filtration rate 相似文献
10.
S. Lüthje P. Van Gestelen M. C. Córdoba-Pedregosa J. A. González-Reyes H. Asard J. M. Villalba M. Böttger 《Protoplasma》1998,205(1-4):43-51
Summary The occurrence of a vitamin-K-like substance (naphthoquinone group) and flavins (flavin mononucleotide and flavin adenine dinucleotide) is demonstrated in plasma membranes isolated from maize (Zea mays L.) roots, on the basis of high-pressure liquid chromotography and spectral analysis. At least three NAD(P)H dehydrogenases could be purified to homogeneity from this plant material. Two of these proteins (25 and 30 kDa) reduce hexacyanoferrate III and quinones, while the third (41 kDa) reduces oxalacetic acid but not hexacyanoferrate III in the presence of NADH. Low-temperature spectra demonstrate the occurrence of a b-type cytochrome in plasma membranes isolated from maize roots. The latter compound could be reduced by ascorbic acid (E0 > +80 mV) and shows an -band maximum at 559 nm (at –196 °C). NADH-dependent cytochromeb reduction could be observed only in the presence of detergent and increased after preincubation with vitamin K3 (menadione). On the basis of the presented data a possible function of naphthoquinones in plasma membrane electron transfer is discussed.Abbreviations Brij 58
polyoxyethylene 20 cetyl ether
- Coenzyme
Q10 ubiquinone-50
- duroquinone
tetramethyl-p-benzoquinone
- E0
standard redox potential
- Na2EDTA
ethylenediaminetetraacetic acid disodium salt
- HEPES
N-[2-hydroxyethyl]piperazine-N[2-ethane-sulfonic acid]
- juglone
5-hydroxy-1,4-naphthoquinone
- PMSF
phenylmethylsulfonyl fluoride
- vitamin
K1 2-methyl-3-phyty 1-1,4-naphthoquinone
- vitamin K3
2-methyl-1,4-naphthoquinone 相似文献
11.
A Schmidt M Bayerle-Eder H Pleiner C Zeisner M Wolzt G Mayer L Schmetterer 《Nitric oxide》2001,5(4):370-376
There is evidence for an interaction between nitric oxide (NO) and endothelin (ET) at the level of the renal vasculature. We hypothesized that acute renal effects of systemic NO synthase inhibition (NG-monomethyl-l-arginine, L-NMMA) may be blunted by coadministration of a specific ET(A) receptor antagonist (BQ-123) in healthy humans. Fifteen healthy young male subjects participated in this randomized, double-blind, placebo-controlled 3-way crossover study. These sodium-repleted volunteers received L-NMMA alone, or BQ-123 alone, or L-NMMA with a subsequent coinfusion of BQ-123. Renal plasma flow (RPF) and glomerular filtration rate (GFR) were determined with the PAH and inulin clearance method, respectively. Mean arterial pressure (MAP) and pulse rate were measured noninvasively at baseline and every 15 min after the start of the study period. L-NMMA alone reduced RPF (-22%, P < 0.001) and GFR (-8%, P < 0.009) and increased MAP (+10%, P < 0.001). BQ-123 alone did not affect these parameters. However, coinfusion of BQ-123 blunted the effects of L-NMMA on RPF (P < 0.001), GFR (P < 0.001), and MAP (P = 0.006). Peripheral and renal hemodynamic effects of acute systemic NO synthase inhibition are at least partially reversed by ET(A) receptor blockade with BQ-123. This indicates a functional antagonism between specific ET(A) receptor antagonist and NO synthase inhibitors at the level of the renal vasculature. 相似文献
12.
Martin Schwaiblmair Christian Faul Wolfgang von Scheidt Thomas M Berghaus 《Respiratory research》2012,13(1):18
Background
As differences in gas exchange between pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH) have been demonstrated, we asked if cardiac output measurements determined by acetylene (C2H2) uptake significantly differed in these diseases when compared to the thermodilution technique.Method
Single-breath open-circuit C2H2 uptake, thermodilution, and cardiopulmonary exercise testing were performed in 72 PAH and 32 CTEPH patients.Results
In PAH patients the results for cardiac output obtained by the two methods showed an acceptable agreement with a mean difference of -0.16 L/min (95% CI -2.64 to 2.32 L/min). In contrast, the agreement was poorer in the CTEPH group with the difference being -0.56 L/min (95% CI -4.96 to 3.84 L/min). Functional dead space ventilation (44.5 ± 1.6 vs. 32.2 ± 1.4%, p < 0.001) and the mean arterial to end-tidal CO2 gradient (9.9 ± 0.8 vs. 4.1 ± 0.5 mmHg, p < 0.001) were significantly elevated among CTEPH patients.Conclusion
Cardiac output evaluation by the C2H2 technique should be interpreted with caution in CTEPH, as ventilation to perfusion mismatching might be more relevant than in PAH. 相似文献13.
The affinities of Factor XIII (FXIII), Factor XIIIa (FXIIla), and cellular transglutaminase (Tg) for fibrinogen (Fgn), fibrin (Fbn), and fibronectin (Fn) were compared using a solid-phase binding assay. Initial rates of binding were as follows: FXIII bound Fbn 3-fold more than Fgn. FXIII did not bind Fn till 20 min. Increasing the ligands concentrations and binding time, resulted in weak binding of FXIII to Fn. FXIIla bound Fbn 2-fold more than Fgn and 28-fold more than Fn. Tg bound Fn 130-fold more than either Fgn or Fbn. At equilibrium, the extent of binding was determined to be as follows: FXIII bound Fbn 3–15-fold more than Fgn and 8-fold more than Fn. FXIIIa bound Fgn and Fbn equally and 12–25-fold more than Fn. FXIIla bound Fgn or Fbn 2-fold and 25-fold greater than FXIII-Fbn and FXIII-Fgn interactions, respectively. Tg bound about equally to Fgn and Fbn and 10–20-fold less than Fn. The K
d
s for FXIIla binding to Fn, Fgn, and Fbn were 100, 23, and 19 nM, respectively. The K
d
for Tg binding to Fn was 6.5 nM. The binding hierarchies are: [Tg-Fn]>[FXIIIa-Fgn]=[FXIIIa-Fbn]>[FXIII-Fbn]>[FXIIIFgn]=[FXIIIa-Fn]>[Tg-Fbn]=[Tg-Fgn]>[FXIII-Fn]. Such hierarchies could regulate the cross-linkings by FXIIIa and Tg during hemostasis, wound healing, and cell adhesion.Abbreviations Tg
cellular transglutaminase
- FXIII
coagulation factor XIII
- FXIIla
factor XIIIa (thrombin-activated FXIII)
- Fgn
human plasma fibrinogen
- Fn
human plasma fibronectin
- Fbn
human plasma fibrin (thrombin-cleaved fibrinogen)
- ECM
extracellular matrix 相似文献
14.
H. J. Toutain J. P. Sarsat A. Bouant D. Hoet D. Leroy V. Moronvalle-Halley 《Cell biology and toxicology》1996,12(4-6):289-298
The dog is the non-rodent species the most often used in preclinical drug safety evaluation. In this study, we established a new system of precision-cut dog renal cortical slices, evaluated their biochemical, functional, and morphological integrity, and determined the effects of cisplatin (cis-diamminedichloroplatinum (II), CDDP), a very potent nephrotoxic antineoplastic agent used to treat a variety of solid tumors, on the viability and histopathology of slices. Precision-cut renal cortical slices were made perpendicular to the cortical-papillary axis. Slices were incubated in DMEM/Ham's F12 culture medium containing 1 g/L glucose, 2 mmol/L glutamine, and 2 mmol/L heptanoic acid at 37°C in an atmosphere of 5% CO2-70% O2-25% N2 in dynamic organ culture. Our results showed that slices maintained ATP and GSH content, protein synthesis, Na+-dependent uptake of glucose inhibited by phlorizin, PAH (p-aminohippuric acid) uptake inhibited by probenecid, and TEA (tetraethylammonium) uptake inhibited by mepiperphenidol for at least 6 h of culture, and morphological integrity up to 24 h. After 6 h of exposure, CDDP induced vacuolation and cell necrosis in the epithelial tubular cells of slices with a concentration-related increase in extension but not in severity. The development of the lesions started in the proximal tubules and extended to the distal tubules. The location and the extension of the lesions confirmed the observations in dog kidneys after in vivo treatment with CDDP by the intravenous route. The concentration-related decrease in slice viability after 6 h exposure to CDDP was in keeping with the extension of the histopathological lesions in the renal parenchyma. The slice viability was unaffected up to 0.63 mmol/L CDDP. At 1.25 and 2.5 mmol/L CDDP, slice viability fell by 35% and 75%, respectively. These results suggest that precision-cut dog renal cortical slices in culture may be suitable for addressing the specific nephrotoxicity issues encountered in this species.Abbreviations CDDP
cis-diamminedichloroplatinum (II)
- FIS
freshly isolated slices
- GSH
glutathione
- GSSG
glutathione disulfide
- Hepes
4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid
- MGP
methyl--D-glucopyranoside
- MTT
3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide
- PAH
p-aminohippuric acid
- PBS
phosphate-buffered saline
- TEA
tetraethylammonium 相似文献
15.
Summary [2-13C]-L-lysine, [3,4-13C2]-L-lysine and [5,6-13C2]-L-lysine are prepared from simple, commercially available, highly enriched starting materials as [2-13C]-glycine, ethyl [1,2-13C2]-bromo acetate, and [1,2-13C2]-acetonitrile. The introduction of the chiral center is based on a general method starting from the bis-lactim ether of cyclo-(D-Val-Gly). The synthesis of (2R)-[5-13C]-3,6-diethoxy-2,5-dihydro-2-isopropylpyrazine is described. The availability of our method for the preparation of specifically enriched bis-lactim ethers allows the synthesis of a great variety of site specific isotopically labelled (L- and D-)-amino acids. Moreover, intermediate 4-[(2R,5S)-3,6-diethoxy-2,5-dihydro-2-isopropyl-5-pyrazinyl]butyronitrile is a valuable precursor in the synthesis of L--aminoadipic acid. The synthetic scheme in this publication makes both L-lysine and L--aminoadipic acid13C- or15N-labelled at any position, easily available. The isotopomers of lysine are obtained on a preparative scale in good yields, with 99%13C and high enantiomeric purity (>97% e.e.). Three isotopomers are characterized using various spectroscopic techniques,e.g.,1H NMR,13C NMR and Mass spectrometry. 相似文献
16.
Renal plasma clearances (C) of 14C-tetraethylammonium (TEA) and p-aminohippurate (PAH) as estimates of arterial renal plasma flow (ARPF) were evaluated in anesthetized rats during control conditions and during intravenous glucose infusion. Venous renal blood flow was measured directly by means of a servo-controlled pump, keeping the renal venous pressure constant. Arteriovenous extraction fractions (E = 1 - P(renal venous)/P(renal arterial)) for PAH averaged 88.3 +/- (SE) 0.8% in control rats and 82.0 +/- 0.9% in glucose-infused rats (p less than 0.001); E(TEA) averaged 92.0 +/- 0.6 and 90.1 +/- 0.6%, respectively (p less than 0.05). Under both experimental conditions, (C/E)PAH did not differ significantly from ARPF, while (C/E)TEA underestimated ARPF; the rate of extraction of TEA exceeded the rate of excretion by 15-20%, probably due to accumulation of TEA in renal tissue. It is concluded that, when corrected for E, C(PAH) is in general a more accurate estimate for ARPF than C(TEA). However, under conditions involving changes in plasma glucose levels C(TEA) may provide a better estimate of the effective renal plasma flow than C(PAH). 相似文献
17.
D. M. F. Prazeres F. A. P. Garcia J. M. S. Cabral 《Bioprocess and biosystems engineering》1994,10(1):21-27
The enzymatic hydrolysis of olive oil using Chromobacterium viscosum lipase B encapsulated in reversed micelles of AOT in isooctane was carried out in a continous reversed micellar membrane bioreactor. A tubular ceramic membrane installed in an ultrafiltration module was used to retain the lipase and separate the products from the reaction media. Water filled micelles were supplemented to the reactor together with the substrate/solvent solution to compensate for the permeation of reversed micelles. The influence of substrate concentration, residence time and water content in the productivity and conversion of the system were investigated. A linear relationship between productivity and conversion degree was found for each substrate concentration tested. Operational stability of the bioreactor was tested in a long term operation confirming the high stability of this catalytic system.List of Symbols
a(S
0
), b(S
0
)
parameters of Eq. (3)
- [AOT] mM
AOT concentration
-
C
c
mM
concentration in the concentrate
-
C
p
mM
concentration in the permeate
-
E
t
mg
total amount of lipase
- [lipase] mg/cm3
overall lipase concentration
- [OIL] mM
olive oil concentration
- [OLEIC] mM
oleic acid concentration in the permeate
-
P mol/(min · mg)
oleic acid productivity
-
Q
in
cm3/min
inlet flow rate
-
Q
out
cm3/min
outlet flow rate (equal to permeate flow rate)
-
Q
r
cm3/min
recirculation flow rate
-
W
o
ratio of water to AOT molar concentrations
-
X
steady state conversion degree in the permeate stream
-
T °C
temperature
-
rejection coefficient 相似文献
18.
P. Gundorova A. A. Stepanova T. V. Bushueva E. Yu. Belyashova R. A. Zinchenko S. S. Amelina S. I. Kutsev A. V. Polyakov 《Russian Journal of Genetics》2017,53(6):712-718
To date, the efficacy of the phenylalanine hydroxylase (PAH) cofactor is proved for the treatment of both BH4-dependent hyperphenylalaninemia and phenylketonuria patients with mutations in the PAH gene. Since the patient’s response depends on the presence of residual PAH enzyme activity, it is advisable to search for mutations in the PAH gene to identify the potential responders and nonresponders to therapy. Four hundred thirty-five phenylketonuria patients from 13 regions of the Russian Federation were genotyped in order to identify responders and nonresponders to tetrahydrobiopterin (BH4) therapy. According to the results of this study, the number of probable nonresponders to the BH4 treatment exceeds 50% owing to a higher overall allelic frequency of “severe” PAH gene mutations. Responder patients with two “mild” mutations in the PAH gene were identified (1.6%). 相似文献
19.
Summary. Pseudodipeptides H-Phe[CH2O]Phe-OH, H-Tyr[CH2O] Asp-OH and H-Pro[CH2O]-D-Thr-OH were synthesized using the intramolecular Williamson reaction via substituted morpholin-3-one ring with the nitrogen atom protected with bulky Boc group. This protection and the substituent at C5 position induced the stereospecific alkylation at the C2 position introducing the side chain of the C-terminal amino acid mimetic. In the first pseudodipeptide a quenching of the enolate with benzaldehyde was followed by dehydration and corresponding double bond was hydrogenated with high stereospecific purity. In the other pseudodipeptides, this alkylation was carried out directly by tert-butyl 2-bromoacetate or acetaldehyde. However, in the latter reaction an R configuration of C3 substituent in conjugated lactame ring was determined using a NOE NMR. Consequently, after opening this ring by acidic hydrolysis, the C-terminal part of corresponding pseudodipeptide possessed the side-chain of D-Thr mimetic, contrary to former one. Synthesized pseudodipeptides were introduced into HIV protease inhibitors and into peptides with oostatic activity. 相似文献
20.
R. W. Wilson E. W. Taylor 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1993,163(1):38-47
Acutely lethal (24 h) exposure of adult rainbow trout (Oncorhynchus mykiss) to 4.9 mol copper·l-1 in fresh water (pH 7.9, [Ca2+]0.8 mEq·l-1) caused a rapid decline of plasma Na+ and Cl- and arterial O2 tension, and initially a pronounced tachycardia. The internal hypoxia probably resulted from histopathologies observed in the gills of fish exposed to copper, such as cell swelling, thickening and curling of the lamellae, and haematomas. Copper cannot therefore be considered purely as an ionoregulatory toxicant during acutely lethal conditions. Mortality during exposure to copper could not simply be explained by the plasma ionic dilution, nor by the internal hypoxia, since arterial O2 content remained relatively unchanged. Secondary to the ionoregulatory and respiratory disturbances were a number of deleterious physiological responses which included a massive haemoconcentration (haematocrit values as high as 60%) and a doubling of the mean arterial blood pressure. The time-course of these changes suggest that cardiac failure was the final cause of death. In this respect copper exposure resembles low pH exposure in freshwater trout (Milligan and Wood 1982). Copper and H+ appear to be similar in both the primary site of their toxic action (the gills) and the secondary physiological consequences which result from acutely lethal exposures. Furthermore, the acute toxicity syndrome observed may be common to many metals which cause ionoregulatory and/or respiratory problems in freshwater fish.Abbreviations
C
aO2
arterial oxygen content
- FR
water flow rate
- Hb
haemoglobin
- Hct
haematocrit
- H
m
+
net metabolic acid load
- IU
international unit
- MABP
mean arterial blood pressure
- MCHC
mean corpuscular haemoglobin content
-
MO2
rate of oxygen consumption
-
P
aCO2
arterial carbon dioxide tension
-
P
aO2
arterial oxygen partial pressure
-
T
amm
total ammonia (=NH3+NH
4
+
)
-
TCO2
total carbon dioxide
-
TOC
total organic carbon
- %Hb–O2
percentage of haemoglobin saturated with oxygen 相似文献