共查询到20条相似文献,搜索用时 93 毫秒
1.
Barbara A. Froesch Rolf A. Stahel U. Zangemeister-Wittke 《Cancer immunology, immunotherapy : CII》1996,42(1):55-63
The anthracycline doxorubicin (DOX) is one of the most effective drugs for the treatment of small-cell lung cancer (SCLC),
but its clinical application is limited by unspecific side-effects like cardiotoxicity. In the present study doxorubicin was
conjugated to the monoclonal antibodies (mAb) SEN7, MOC31, and SWA11 via a novel acid-sensitive hydrazone linker. These mAb
recognize SCLC-associated antigens of cluster 1 (NCAM), cluster 2 (EGP-2/GA733-2), and cluster 4 (CD24) respectively. To assess
their potential therapeutic use against SCLC, the antigen-binding activities, the rates of internalization and the cytotoxic
effects of the immunoconjugates were examined on tumour cell lines. The preparation procedure preserved the antigen-binding
activities of the mAb and yielded immunoconjugates with average drug : mAb ratios of 7 : 1. The hydrazone linker was found
to be stable at neutral pH but to release doxorubicin under acidic conditions. In contrast to SEN7-DOX, MOC31-DOX and SWA11-DOX
were rapidly internalized into SCLC target cells upon binding to their specific cell-surface antigens. Accordingly, both immunoconjugates
proved to be highly cytotoxic agents, inhibiting thymidine incorporation by 50% at concentrations between 0.5 μM and 1 μM
and were 100-fold more selective than free doxorubicin. The results suggest that binding to selective cell-surface antigens,
rapid internalization and efficient release of doxorubicin from the mAb by acid hydrolysis are required for the selective
and potent function of the immunoconjugates. In particular, the use of MOC31-DOX for targeted cytotoxic therapy might be promising
because of the limited cross-reactivity of the mAb with normal human tissues and its recently demonstrated tumour localization
potential in SCLC patients.
Received: 22 September 1995 / Accepted: 23 November 1995 相似文献
2.
Düsman E Berti AP Mariucci RG Lopes NB Vicentini VE 《Radiation and environmental biophysics》2011,50(4):579-584
Iodine-131 (131I) is a radioisotope used for the diagnosis and treatment of thyroidal disorders such as hyperthyroidism and cancer. During
its decay, 131I emits beta particles and gamma rays; its physical half-life is 8 days, and it is accumulated preferentially in the thyroid
tissue. This study aimed to evaluate the cytotoxicity and mutagenicity of diagnostic and therapeutic doses of 131I using bone marrow cells of rats treated in vivo in a test system with a single dose by gavage. Concentrations of 5, 25,
50 and 250 μCi in 1 ml of water were used, and after 24 h, the animals were killed. Also, a concentration of 25 μCi/ml of
water was used, and the animals were killed after 5 days. The results showed that no concentration of 131I was cytotoxic and that all concentrations were mutagenic. As a result, there was no statistically significant difference
detected by the χ2 test in the induction of chromosomal aberrations between the different doses. Thus, the present study demonstrated a significant
increase in chromosomal aberration in bone marrow cells exposed to 131I regardless of the dose or the treatment time. 相似文献
3.
Juan Fuentes F. B. Eddy 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1997,167(6):438-443
Drinking in Atlantic salmon (Salmo salar) juveniles was investigated in fresh water and following transfer to sea water. There was a significant effect of fish size
on drinking, and smolts (20–30 g) imbibed about ten times less water than alevins of 0.2–0.3 g. Freshwater smolts drank at
a rate of 0.15 ± 0.03 ml · kg−1 · h−1 and administration of doses of 10 or 20 mg · kg−1 of papaverine (stimulator of the renin- angiotensin system RAS) or [Asn1, Val5]-Angiotensin II (0.4 μmol · kg−1) resulted in significant increases in drinking, while administration of the angiotensin converting enzyme inhibitor, enalapril
(50 mg · kg−1) had no effect on drinking. Transfer of Atlantic salmon smolts to 1/3, 2/3 and full strength sea water resulted in significant
increases in drinking to 1.06 ± 0.12, 1.24 ± 0.0.16 and 3.89 ± 0.28 ml · kg−1 · h−1, respectively. In sea water, stimulation of the endogenous RAS by administration of papaverine (20 mg · kg−1) resulted in a 20% increase in drinking, while administration of enalapril to doses of 50 and 200 mg · kg−1 lowered drinking to 1.99 ± 0.48 and 0.32 ± 0.06 ml · kg−1 · h−1, respectively. All treatments were without effect on blood plasma levels of Na+ and Cl− in fresh water, while in sea water smolts both stimulation and inhibition of drinking resulted in hemoconcentration of Na+ and Cl−. The role of the renin angiotensin system in control of drinking and hydromineral balance in Atlantic salmon is discussed.
Accepted: 27 February 1997 相似文献
4.
Philip O. Livingston Shengle Zhang Kenneth O. Lloyd 《Cancer immunology, immunotherapy : CII》1997,44(1):1-9
Resistance to chemotherapy is a major cause for failure in the treatment of lung cancer. Compared to conventional cytotoxic
drugs, immunotoxins act by different mechanisms and thus might be promising for the treatment of chemoresistant cancer. The
monoclonal antibody MOC31 recognises the epithelial glycoprotein-2 (EGP-2), a cell-surface antigen associated with small-cell
lung cancer (SCLC) and a major fraction of lung adenocarcinomas. An immunotoxin composed of MOC31 and a recombinant form of
Pseudomonas exotoxin A lacking the cell-binding domain (ETA252 – 613) was prepared, and its effect on lung cancer cell lines examined. MOC31-ETA252 – 613 was selectively cytotoxic to EGP-2-positive SCLC and adenocarcinoma cell lines inhibiting proliferation by 50% at concentrations
ranging from 0.01 nM to 0.3 nM. Moreover, the immunotoxin reduced the numberof clonogenic tumour cells from cultures by factors
of 104 and 105 during a 24-h and a 3-week exposure respectively. In athymic mice, the immunotoxin, which revealed a serum half-life of approximately
4 h, caused substantial regression of small (40 mm3) chemoresistant tumour xenografts and significantly delayed the growth of larger tumours (120 mm3). This finding indicates that MOC31-ETA252 – 613 may be useful for the treatment of lung cancer in the setting of chemoresistant minimal residual disease.
Received: 31 October 1996 / Accepted: 5 December 1996 相似文献
5.
Krzysztof J. Rakowski 《Trees - Structure and Function》1997,11(4):248-253
Eastern white pine (Pinus strobus L.) seedlings were pretreated with 12 h photoperiod to induce dormancy. Dormant plants were fumigated with 0.5 ppb (0.4 μg
m–3) or 2.0 ppb (1.6 μg m–3) hydrogen fluoride (HF) for 2 – 28 days. Plasma membranes were isolated from needles of treated and control seedlings to
determine their chemical composition and ATPase activity. For all analyses, only those plants which did not show needle necrosis
were selected. The amount of plasma membrane phospholipid expressed on a plasma membrane protein basis was higher after 2
days in the 0.5 ppb HF treatment as compared to controls. After 2 days of 2.0 ppb HF treatment as well as after 8 and 28 days
of both HF treatments phospholipid to protein ratios in fluoride treated seedlings were lower as compared to control levels.
A decrease in sterol levels could be observed after 2 days in both HF treatments. A large increase in the ratio of sterols
to proteins was observed in plasma membranes of eastern white pine seedlings treated with 0.5 ppb HF for 28 days. Increased
sterol to phospholipid ratios were observed after 8 and 28 days in 0.5 ppb and after 2 and 8 days of 2.0 ppb HF treatment.
A decrease in ATPase activity was observed after 8 days with both fluoride treatments. Drastic increase of ATPase activity
was observed after 28 days of HF treated plants. Observed changes of sterol and phospholipid levels after only 2 days of fumigation
suggest early fluoride effects on plasma membrane composition during plant dormancy.
Received: 25 October 1995 / Accepted: 24 May 1996 相似文献
6.
M. E. Forster W. Davison M. Axelsson L. Sundin C. E. Franklin S. Gieseg 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1998,168(5):345-352
Two species of Antarctic fish were stressed by moving them from seawater at −1 °C to seawater at 10 °C and holding them for
a period of 10 min. The active cryopelagic species Pagothenia borchgrevinki maintained heart rate while in the benthic species Trematomus bernacchii there was an increase in heart rate. Blood pressure did not change in either species. Both species released catecholamines
into the circulation as a consequence of the stress. P. borchgrevinki released the greater amounts, having mean plasma concentrations of 177 ± 54 nmol · l−1 noradrenaline and 263 ± 131 nmol · l−1 adrenaline at 10 min. Plasma noradrenaline concentrations rose to 47 ± 14 nmol · l−1 and adrenaline to 73 ± 28 nmol · l−1 in T. bernacchii. Blood from P. borchgrevinki was tonometered in the presence of isoprenaline. A fall in extracellular pH suggests the presence of a Na+/H+ antiporter on the red cell membrane, the first demonstration of this in an Antarctic fish. Treatment with the β-adrenergic
antagonist drug sotalol inhibited swelling of red blood cells taken from temperature-stressed P. borchgrevinki, suggesting that the antiporter responds to endogenous catecholamines.
Accepted: 22 January 1998 相似文献
7.
K. Scheibner M. Hofrichter A. Herre J. Michels W. Fritsche 《Applied microbiology and biotechnology》1997,47(4):452-457
Within a screening program, 91 fungal strains belonging to 32 genera of different ecological and taxonomic groups (wood-
and litter-decaying basidiomycetes, saprophytic micromycetes) were tested for their ability to metabolize and mineralize 2,4,6-trinitrotoluene
(TNT). All these strains metabolized TNT rapidly by forming monoaminodinitrotoluenes (AmDNT). Micromycetes produced higher
amounts of AmDNT than did wood- and litter-decaying basidiomycetes. A significant mineralization of [14C]TNT was only observed for certain wood- and litter-decaying basidiomycetes. The most active strains, Clitocybula dusenii TMb12 and Stropharia rugosa-annulata DSM11372 mineralized 42 % and 36 % respectively of the initial added [14C]TNT (100 μM corresponding to 4.75 μCi/l) to 14CO2 within 64 days. Micromycetes (deuteromycetes, ascomycetes, zygomycetes) proved to be unable to mineralize [14C]TNT significantly.
Received: 8 August 1996 / Received revision: 16 December 1996 / Accepted: 20 December 1996 相似文献
8.
Light response characteristics of a morphologically diverse group of southern hemisphere conifers as measured by chlorophyll fluorescence 总被引:5,自引:0,他引:5
Unlike northern hemisphere conifer families, the southern family, Podocarpaceae, produces a great variety of foliage forms
ranging from functionally broad-, to needle-leaved. The production of broad photosynthetic surfaces in podocarps has been
linked qualitatively to low-light-environments, and we undertook to assess the validity of this assumption by measuring the
light response of a morphologically diverse group of podocarps. The light response, as apparent photochemical electron transport
rate (ETR), was measured by modulated fluorescence in ten species of this family and six associated species (including five
Cupressaceae and one functionally needle-leaved angiosperm) all grown under identical glasshouse conditions. In all species,
ETR was found to increase as light intensity increased, reaching a peak value (ETRmax) at saturating quantum flux (PPFDsat), and decreasing thereafter. ETRmax ranged from 217 μmol electrons · m−2 · s−1 at a PPFDsat of 1725 μmol photons · m−2 · s−1 in Actinostrobus acuminatus to an ETR of 60 μmol electrons · m−2 · s−1 at a PPFDsat of 745 μmol electrons · m−2 · s−1 in Podocarpus dispermis. Good correlations were observed between ETRmax and both PPFDsat and maximum assimilation rate measured by gas-exchange analysis. The effective quantum yield at light saturation remained
constant in all species with an average value of 0.278 ± 0.0035 determined for all 16 species. Differences in the shapes of
light response curves were related to differences in the response of non-photochemical quenching (q
n), with q
n saturating faster in species with low PPFDsat. Amongst the species of Podocarpaceae, the log of average shoot width was well correlated with PPFDsat, wider leaves saturating at lower light intensities. This suggests that broadly flattened shoots in the Podocarpaceae are
an adaptation to low light intensity.
Received: 15 April 1996 / Accepted: 30 September 1996 相似文献
9.
Characteristics of dipeptide transport in pig jejunum in vitro 总被引:4,自引:0,他引:4
Winckler C Breves G Boll M Daniel H 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1999,169(7):495-500
Characteristics of dipeptide transport in pig jejunum were investigated in vitro by applying the Ussing-chamber technique
and mucosal uptake studies. Addition of both glycyl-l-glutamine and glycyl-l-sarcosine (20 mmol · l−1) to the mucosal buffer solution significantly increased the short-circuit current by 2.60 ± 0.15 and 1.57 ± 0.20 μeq · cm−2 · h−1, respectively. Concentration-dependent changes in short-circuit current followed Michaelis-Menten kinetics with similar affinity
constants for both dipeptides. From unidirectional flux rates for radiolabelled glycyl-l-sarcosine, a net flux rate for glycyl-l-sarcosine of 49.8 ± 6.7 nmol · cm−2 · h−1 was calculated. In mucosal uptake experiments, the apical influx of 14C-labelled glycyl-l-sarcosine into isolated porcine mucosa was pH dependent and significantly inhibited by glycyl-l-glutamine. Moreover, RT-PCR studies with primers derived from rabbit PepT1 identified two PCR fragments of identical size
to rabbit PepT1 from pig intestinal mRNA preparations. In conclusion, our studies revealed key features of mammalian intestinal
peptide transporters and give evidence for a PepT1-like transporter in the pig jejunum that could significantly contribute
to the overall amino acid absorption from the gut.
Accepted: 30 June 1999 相似文献
10.
Moro D Bradshaw SD 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1999,169(8):538-548
A laboratory study investigated the metabolic physiology, and response to variable periods of water and sodium supply, of
two arid-zone rodents, the house mouse (Mus domesticus) and the Lakeland Downs short-tailed mouse (Leggadina lakedownensis) under controlled conditions. Fractional water fluxes for M. domesticus (24 ± 0.8%) were significantly higher than those of L. lakedownensis (17 ± 0.7%) when provided with food ad libitum. In addition, the amount of water produced by M. domesticus and by L. lakedownensis from metabolic processes (1.3 ± 0.4 ml · day−1 and 1.2 ± 0.4 ml · day−1, respectively) was insufficient to provide them with their minimum water requirement (1.4 ± 0.2 ml · day−1 and 2.0 ± 0.3 ml · day−1, respectively). For both species of rodent, evaporative water loss was lowest at 25 °C, but remained significantly higher
in M. domesticus (1.1 ± 0.1 mg H2O · g−0.122 · h−1) than in L. lakedownensis (0.6 ± 0.1 mg H2O · g−0.122 · h−1). When deprived of drinking water, mice of both species initially lost body mass, but regained it within 18 days following
an increase in the amount of seed consumed. Both species were capable of drinking water of variable saline concentrations
up to 1 mol · l−1, and compensated for the increased sodium in the water by excreting more urine to remove the sodium. Basal metabolic rate
was significantly higher in M. domesticus (3.3 ± 0.2 mg O2 · g−0.75 · h−1) than in L. lakedownensis (2.5 ± 0.1 mg O2 · g−0.75 · h−1). The study provides good evidence that water flux differences between M. domesticus and L. lakedownensis in the field are due to a requirement for more water in M. domesticus to meet their physiological and metabolic demands. Sodium fluxes were lower than those observed in free-ranging mice, whose
relatively high sodium fluxes may reflect sodium associated with available food.
Accepted: 16 August 1999 相似文献
11.
We tested whether treatment with an inhibitor of nitric oxide synthesis (N
G-methyl-L-arginine, MeArg) can ameliorate interleukin-2(IL-2)-therapy-induced capillary leak syndrome in healthy or tumor-bearing mice
without compromising the antitumor effects of IL-2 therapy. Healthy or C3-L5-mammary-adenocarcinoma-bearing C3H/HeJ mice were
treated with one or two rounds of various doses of IL-2 (ten injections, i. p., every 8 h) or MeArg (ten injections s. c.,
every 8 h) or their combination. In an additional experiment, MeArg was given chronically in the drinking water, rather than
s. c. to healthy mice subjected to one round of therapy as above. Mice were killed 1 h after their last IL-2 injection to
measure the water content of the lungs and pleural cavities (markers of capillary leakage), NO production (given by NO2
– and NO3
– levels in the serum and pleural effusion), as well as the effect of therapies on the primary tumor size and number of spontaneous
lung metastatic nodules. Results revealed that all doses of IL-2 (7500 – 35 000 Cetus U/injection), as well as both rounds
of IL-2 therapy, caused capillary leakage. However, no pleural effusion was seen after the second round in any of the IL-2-treated
groups. MeArg therapy, given subcutaneously (5 – 20 mg kg–1 injection–1 in healthy and 20 mg kg–1 injection–1 in tumor-bearing mice), did not ameliorate IL-2-induced capillary leakage in either group of mice, and did not compromise
antitumor effects of IL-2. However, subcutaneous MeArg therapy alone reduced the growth of the primary tumors, the occurrence
of spontaneous lung metastases and the amount of tumor-induced pulmonary edema. When MeArg therapy was given orally (1 mg/ml
drinking water), a substantial drop in NO production, as well as reduction in capillary leakage was noted in IL-2-treated
healthy mice. These findings suggest that NO inhibitors could be a valuable adjunct to IL-2 therapy of cancer and infectious
diseases.
Received: 23 October 1995 / Accepted: 22 November 1995 相似文献
12.
S. M. E. Guirguis J. C. Yee D. F. Stiffler 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1997,167(5):328-334
The skin of intact, free-swimming Xenopus laevis transports Ca2+ inwardly in a manner that is proportional to the external [Ca2+] up to about 0.3 mmol · l−1, saturates above 0.3 mmol · l−1, and is opposed to the electrochemical gradient. Efflux is relatively constant at external concentrations between 0.016 and
0.6 mmol · l−1; net flux which is negative below 0.125 mmol · l−1 becomes positive above this external [Ca2+]. Allometric analysis suggests that both Ca2+ influx and efflux scale to the 2/3 power approximately like surface area. There were no significant differences in influx
between summer and fall animals; however, efflux was greater in the fall and this resulted in a change from positive balance
in the summer to negative balance in the fall. Isolated skins were shown to support a Ca2+ uptake rate of nearly 30 nmol · cm−2 · h−1. The phenylalkylamine verapamil in the apical bathing solution significantly inhibited this at 25 μmol · l−1. The benzothiazepine diltiazem was also effective at 50 μmol · l−1 while the dihydropyradine nifedipine was ineffective up to 100 μmol · l−1. The inorganic ion La3+ was effective at blocking Ca2+ uptake at 300 μmol · l−1; Ni2+ was also effective at 500 μmol · l−1 but Co2+ was ineffective up to 500 μmol · l−1. These results suggest that apical calcium channels in Xenopuslaevis skin have properties similar to mammalian L-channels and fish gill Ca2+ channels.
Accepted: 23 January 1997 相似文献
13.
P. Becker Azman Asmat Julaihi Mohamad Misli Moksin Melvin T. Tyree 《Trees - Structure and Function》1997,11(7):432-435
In contrast with previous reports, we observed high transpiration rates in mangrove trees. Maximum sap velocities and mean
daytime sap flow rates were estimated from heat pulse velocity in entire, field grown trees of Avicennia cf. alba Blume and Rhizophora apiculata Blume. Results were within the range of values measured by identical techniques for trees in lowland dipterocarp and tropical
heath forests with a similar climate in Brunei Darussalam (north Borneo). High stomatal conductance (400 mmol m –
2 s –
1) was also measured for well insolated leaves of A. cf. alba, with midday water potentials reaching about – 3 MPa in both species.
Received: 11 September 1996 / Accepted: 27 January 1997 相似文献
14.
Jeffrey S. Barrett Susan J. Fisher R. L. Wahl 《Cancer immunology, immunotherapy : CII》1997,44(3):173-178
To optimize the regional delivery advantage with i. p. administration of monoclonal antibody (mAb) for radioimmunotherapy,
it may be possible to delay the rate and extent of mAb absorption from the peritoneal cavity by simply altering the position
of a patient after radioantibody administration. It has been shown that the hydrostatic pressure against the diaphragm plays
a major role in the rate of egress of radioantibodies from the peritoneal cavity and that fluid removal from the peritoneal
cavity can be altered by posture. The current study examined postural effects in normal rats following the i. p. injection
of 125I-5G6.4 murine IgG2a anticarcinoma antibody (45 μCi). A 10-ml injection volume of the radioantibody solution was administered
to rats restrained in either a supine or inclined (reverse Trendelenburg; feet down at a 45° angle) position. Pharmacokinetic
analysis confirmed that the appearance of the radioantibody into the systemic circulation was delayed in the inclined group.
The time to peak blood concentration was prolonged from 14.7 (supine) to 19.2 (inclined) hours (P = 0.005). All other pharmacokinetic parameters were equivalent across the treatment groups. The mean half-life of 166 h,
mean blood clearance of 9 ml/min, and mean steady-state volume of distribution of 36 ml were consistent with previous experience
with this radioantibody in the rat. The intrinsic absorption profile indicated that the mean percentage absorption from the
peritoneal cavity to the blood stream was greater in the supine animals from 4 h after i. p. injection until absorption was
complete. By 10 h after injection, absorption from the peritoneal cavity was essentially complete in the supine-dosed animals,
while those restrained in an inclined position had cleared only 50% of the total absorbed dose. Hence, the regional delivery
advantage afforded by intraperitoneal administration of the radioantibody may be further exploited by maintaining an inclined
position throughout the absorption phase, a strategy that may be applicable to radioimmunotherapy of patients.
Received: 26 July 1996 / Accepted: 27 January 1997 相似文献
15.
Hans Gesser William R. Driedzic Francisco Tadeu Rantin José Carlos de Freitas 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1997,167(7):474-480
Isometric force development of electrically paced preparations isolated from the systemic heart of Octopus vulgaris were utilized to examine the regulation of contractility by Ca2+. Increases in extracellular Ca2+, to the physiological level, resulted in enhancement of twitch force. For instance, at 36 beats · min−1 an increase in Ca2+ from 3 to 9 mmol · l−1 resulted in a threefold increase in twitch force development. When steady-state contraction at 12 beats · min−1 was followed by a rest period of either 5 or 10 min, the first contraction always exhibited either an increase in twitch
force or stayed unchanged such that post-rest twitch force was about 133% of the last value in the steady-state train. Ryanodine
(12.5 μmol · l−1), which is considered to be a specific inhibitor of the Ca2+ storage and release capabilities of the sarcoplasmic reticulum (SR), was applied to further assess Ca2+ handling. Twitch force fell to about 22% of the preteatment level in preparations paced at either 12 or 36 beats · min−1. In all preparations the frequency transition from 12 to 36 beats · min−1 was associated with an increase in resting tension. The␣increase␣was 37 ± 14% prior to ryanodine treatment and was significantly
elevated to 127 ± 33% following treatment. When steady-state contraction at 36 beats · min−1 was followed by a rest period of 10 s, the first contraction was not significantly different from the last beat in the train
prior to ryanodine; however, with ryanodine treatment, post-rest twitch force development significantly decreased. Twitch
force development was regular at pacing rates of up to 300 beats · min−1. Twitch force was maintained up to rates of 84 beats · min−1 but␣decreased thereafter and reached a value of about 10% at 300 beats · min−1. Resting tension increased substantially as frequency was elevated from 12 to 36 beats · min−1 and then gradually increased as frequency was further elevated to 180 beats · min−1. In conclusion, the Octopus ventricle is dependent upon extracellular Ca2+ for contraction. A post-rest potentiation of force development, the negative impact of ryanodine, and the ability to respond
regularly at high pacing rates imply a strong reliance on the SR in Ca2+ cycling based on criteria established for vertebrate hearts.
Accepted: 19 January 1997 相似文献
16.
J.-P. Schnitzler Tim P. Jungblut Carmen Feicht Matthias Köfferlein Christian Langebartels W. Heller Heinrich Sandermann Jr. 《Trees - Structure and Function》1997,11(3):162-168
Cultivation of Scots pine (Pinus sylvestris L.) seedlings under simulated global radiation including the UV-B band (280 – 320 nm; 220 mW m–2 UV-BBE) led to increased formation of the diacylated flavonol glucosides 3″,6″-di-p-coumaroyl-astragalin and 3″,6″-di-p-coumaroyl-isoquercitrin in primary and cotyledonary needles, respectively. 3″,6″-Di-p-coumaroyl-astragalin was also the main constitutive diacylated flavonol glucoside in both needle types. This compound predominantly
accumulated in primary needles upon UV-B irradiation, and reached concentrations of 2.4 μmol g–1 fresh weight (fw). Its concentration was only weakly affected in cotyledonary needles. 3″,6″-Di-p-coumaroyl-isoquercitrin was mainly induced in cotyledonary needles with maximum concentrations of 0.8 to 0.9 μmol g–1 fw, but was virtually unaffected in primary needles under the same irradiation conditions. Pulse labelling with L-(U-14C)phenylalanine revealed that these metabolites were formed de novo. Phenylalanine ammonia-lyase (EC 4.3.1.5) and chalcone
synthase (EC 2.3.1.74) were only slightly induced by the UV-B treatment. The results described here represent the first report
on UV-B-induced flavonoid biosynthesis in a conifer species.
Received: 5 December 1995 / Accepted: 20 March 1996 相似文献
17.
Shoot tips from in vitro-grown, cold-hardened stock plants of white poplar (Populus alba L.) were successfully cryopreserved at –196 °C by one-step vitrification. After preculturing at 5 °C for 2 days on hormone-free
MS medium containing different sucrose concentrations, and loading for 20 min with 2 m glycerol and 0.4 m sucrose, shoot tips were treated with the PVS2 vitrification solution and plunged directly into liquid nitrogen. Best survival
rate (90%) was obtained when shoot tips were precultured on 0.09 m sucrose, hormone-free MS medium, vitrified by exposure to PVS2 solution for 60 min at 0 °C and, following cryopreservation,
rewarmed at 40 °C and washed in 1.2 m sucrose solution for 20 min. Regrowth was improved by plating shoot tips on a gelled MS medium containing 1.5 μm N6-benzyladenine plus 0.5 μm gibberellic acid, while shoot rooting was achieved on MS medium containing 3 μm indole-3-butyric acid. Following this procedure, almost 60% rooted shoots were obtained from cryopreserved shoot tips.
Received: 1 February 1999 / Revision received: 3 May 1999 · Accepted: 21 May 1999 相似文献
18.
We tested the effects of injections of small doses of131I (150 μCi) into female rats on brain development in their offspring. The brains of rats whose embryogenesis was influenced
by incorporated131I were studied with the use of an immunohistochemical technique (monoclonal antibodies to nuclear antigen of cell proliferation).
Single injections of131I in the above dose were shown to noticeably suppress the cell proliferative activity in a few structures of the brain of
newborn rats. The most significant drop in the proliferative index in the external layers of the cerebellum was observed after131I injections performed on the 16th day of embryogenesis (when the embryonal thyroid gland begins its functioning). 相似文献
19.
The use of amiloride to uncouple branchial sodium and proton fluxes in the brown trout, Salmo trutta
I. D. Nelson W. T. W. Potts H. Huddart 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1997,167(2):123-128
Resting proton, ammonium and sodium fluxes in Salmo trutta were 492.6 ± 19.5 (n = 29); 122.9 ± 34.2 (n = 28) and 277.1 ± 18.5 (n = 50) μmol · kg−1 · h−1, respectively. The resting transepithelial potential was found to be composed of three successive potentials, the outermost
averaging −7.36 ± 0.19mV, the second, −14.3 ± 1.4 mV and the third −37 ± 1.7 mV. Amiloride inhibits the proton, ammonium and
sodium fluxes in a dose-dependent manner at concentrations of 0.5 mmol · 1−1 and 0.1 mmol · l−1, but at 0.01 mmol · l−1, proton and ammonium fluxes remained at control levels whilst the sodium was reduced to 70.59 ± 7.29 μmol · kg−1 · h−1. The trans-epithelial potential was effected in a bi-phasic manner by 0.5 mmol · l−1 amiloride. An initial hyperpolarisation of ca. 6 mV was followed by a sustained depolarisation of ca. 14 mV (towards zero)
which persisted until the amiloride was washed off the gill. The initial hyperpolarisation was thought to reflect a rapid
inhibition of a positive inward sodium current and the subsequent depolarisation was due to the inhibition of a positive outward
current (proton) which would abolish the transepithelial potential. However, at 0.01 mmol · l−1 only the hyperpolarisation was seen, due to the inhibition of only the inward sodium current. Acetazolamide (0.1 mmol · l−1) was found to have no significant effect on the proton, ammonium and sodium fluxes. These results indicate that the proton
and sodium fluxes across the gill of the freshwater trout are not tightly linked. While this suggests that the trout gill
resembles the model of Ehrenburg et al. (1985) of sodium uptake in frog skin, the apical potentials measured in the pavement
epithelial cell(s) are too low to account for sodium uptake unless the activity of the sodium in the cells is very low.
Accepted: 8 August 1996 相似文献
20.
Induction of accessory cell function of human alveolar macrophages by inhalation of human natural interleukin-2 总被引:1,自引:0,他引:1
Gernot Zissel Walter E. Aulitzky J. Lorenz Christoph Huber J. Müller-Quernheim 《Cancer immunology, immunotherapy : CII》1996,42(2):122-126
Accessory function allows antigen-presenting cells to produce sufficient secondary signals for optimum T cell proliferation
and interleukin-2 (IL-2) production. Alveolar macrophages are inferior accessory cells compared to monocytes (PBM). We report
here that the accessory index (AI) of alveolar macrophages and PBM of patients with lung metastases of solid tumors treated
with inhalations of human natural IL-2 (hnIL-2) increased following its administration (P<0.005). The accessory index was significantly elevated from baseline values after 2 weeks of inhalation of 300 000 IU hnIL-2/day
(8.2±10.2 compared to 1.1±1; P<0.001). The inhalation of 150 000 IU also induced increases in the index (AI = 2.3±1.9), however, without reaching statistical
significance. In addition at 300 000 IU IL-2/day a significant increase in the accessory index was observed for PBM (4±2.5;
P<0.05). The indices of PBM and alveolar macrophages prior to inhalation showed a significant negative correlation with the
age of the patients (r
s = – 0.5; r
s = – 0.8, respectively; P<0.03 for all comparisons). Our data demonstrate that the inhalational application of hnIL-2 enhances the accessory function
of alveolar macrophages and, to lesser extent, the accessory index of PBM, indicating the occurrence of pharmacological immunostimulation.
Received: 16 August 1995 / Accepted: 4 January 1996 相似文献