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31.
Berner Bret Wilson Donald R. Guy Richard H. Mazzenga Gerard C. Clarke Frank H. Maibach Howard I. 《Pharmaceutical research》1988,5(10):660-663
The relationship between pK
a and skin irritation in man is studied for a homologous series of benzoic acid derivatives, which permeate through human skin at comparable rates (15–88 µg/cm2/hr). Skin irritation and pK
a are correlated for pK
a 4. Laser Doppler velocimetric assessment of skin blood flow, color meter readings, erythema, edema, and the primary irritation index are all linearly correlated and related to pK
a, erythema at 24 hr appears to be the most sensitive parameter to variation in pK
a when pK
a 4. 相似文献
32.
Expression of CDX2 and MUC2 in Barrett's mucosa 总被引:3,自引:0,他引:3
Steininger H Pfofe DA Müller H Haag-Sunjic G Fratianu V 《Pathology, research and practice》2005,201(8-9):573-577
Barrett's mucosa is a risk factor for esophageal adenocarcinoma and should be detected at an early stage. It is defined by the presence of columnar epithelium with goblet cells in the lower esophagus, but histologic diagnosis can be uncertain in the absence of distinct goblet cells. We investigated 55 biopsies from 48 patients with endoscopically plain Barrett's esophagus and performed immunohistochemistry for CDX2 and MUC2. In addition, alcian blue (pH 2,5)/PAS staining was done. In histologically unequivocal Barrett's mucosa, nuclear expression of CDX2 in goblet cells and many columnar cells, as well as cytoplasmic positivity for MUC2 in goblet cells, could be observed. Alcian blue (pH 2,5)/PAS stained acidic mucins in goblet cells and in some non-goblet columnar cells. In six cases, no definite Barrett's mucosa was present, and no expression of MUC2 could be observed. In these biopsies, there was granular cytoplasmic and/or focal nuclear staining for CDX2 in non-goblet columnar epithelial cells, indicating their intestinal differentiation. We suggest that this peculiar mucosa is the precursor of unequivocal Barrett's mucosa and would designate it early Barrett's mucosa. Alcian blue for acidic mucins is inconsistent in this epithelium and does not reliably indicate early intestinal differentiation. 相似文献
33.
M. Vandenbranden J.L. de Coen R. Jeener L. Kanarek J.M. Ruyschaert 《Molecular immunology》1981,18(7):621-631
Interactions between rabbit-γ-immunoglobulins and model membranes (lipid monalayers, planar lipid bilayers, liposomes) have been investigated. No significant interaction was observed with immunoglobulins. However, immunoglobulins dialysed first vs aqueous buffer having pH 2 or 3 and then dialysed against pH 7 buffer presumably adopt a new conformation which allows their bindings to model membranes. This binding is hydrophobic and the immunoglobulin region interacting with the lipid acyl chains is probably located in the heavy chain, as suggested by labelling in this region by a photosensitive probe previously incorporated into the lipid hydrophobic core. Cleavage at the hinge region by papain or pepsin, or heating above 38°C, induces the loss of the hydrophobic conformation responsible for hydrophobic bindings. The binding capacity of immunoglobulins heated above 38°C is restored after momentary dialysis at pH 2. The possible existence of two Ig isomers is discussed in relation to the mechanism of γ-immunoglobulin passage through the endoplasmic membrane and fixation into the plasma membrane. 相似文献
34.
Judith Ramsey Clare Austin Susan Wray 《Pflügers Archiv : European journal of physiology》1994,428(5-6):674-676
Changes in extracellular pH (pHo) induce changes in the intracellular pH (pHi) of cardiac myocytes that are slow and attenuated. Little however is known about the effects of changing pHo on the pHi of the coronary smooth muscle cells. We have therefore directly compared the effects of altering pHo on pHi of both coronary and cardiac myocytes. Carboxy-SNARF was used in single cells to measure pHi. Alteration of pHo caused corresponding changes in pHi that were large (70–80 % of pHo) and rapid in coronary myocytes compared to cardiac myocytes. In contrast, changes of pHi produced by weak acids or bases produced similar pHi responses in both types of cells. It is suggested that the differential effects of pHo on coronary and cardiac cells may be functionally significant, as it will allow rapid alteration of coronary perfusion to meet tissue needs, while maintaining cardiac output.Supported by the BHF and MRC 相似文献
35.
S. Coppola R. Caroppo E. Frömter 《Pflügers Archiv : European journal of physiology》1994,429(2):203-209
Following the technical approach described in the preceding publication we have investigated if, and how, stimulation of gastric HCl secretion affects the basolateral ion transport properties of oxyntopeptic cells of Rana catesbeiana stomach. To this end microdissected gastric glands were punctured with conventional or H+-sensitive glass microelectrodes and the effects of changing bath ion concentrations on the cell membrane potential (V
b) and cell pH (pHi) were determined. Except for a transient alkalinization, histamine (0.5 mmol/l) did not significantly affect V
b or pHi. The latter averaged 7.18±0.03 (mean±SEM, n=5) under resting conditions (0.1 mmol/l cimetidine) and 7.21±0.07 (n=5) in the presence of histamine. In addition, neither the initial velocity nor the final steady-state value of the cell alkalinization following a 101 reduction of bath Cl– concentration changed in the presence of histamine, and the same holds true for the cell acidification following a 101 reduction of bath HCO3
– concentration. These observations indicate that the basolateral Cl–/HCO3
– exchanger was not stimulated by histamine, and that no other base transporters were activated. By contrast, the V
b response to elevation of bath K
+ concentration decreased, and so did the initial depolarizing V
b response to bath Cl– substitution, while the secondary hyperpolarizing response increased. The latter observations are compatible with the notion that stimulation by histamine reduced a pH-insensitive part of the basolateral K+ conductance and reduced also the basolateral Cl– conductance. 相似文献
36.
目的在生物型人工肝支持系统(BAL)中,设计一种能够精确控制溶解氧(D0)与酸碱度(pH)的控制方案.方法根据肝细胞培养过程中所需要的物料衡算,采用比例积分(PI)算法结合开关量控制、预测控制等方案,通过工控机构建关联控制系统,使得D0与pH的值相互关联.结果DO控制范围0%~200%,精度达到±5%;pH控制范围6~8,精度达到±0.05.结论经实验证实,本控制方案工作稳定,无静态误差,解决了培养过程中DO与pH相互影响的问题,可用于BAL中对肝细胞培养环境的控制. 相似文献
37.
Rheogenic sodium-bicarbonate cotransport in the peritubular cell membrane of rat renal proximal tubule 总被引:19,自引:0,他引:19
K. Yoshitomi B. -Ch. Burckhardt E. Frömter 《Pflügers Archiv : European journal of physiology》1985,405(4):360-366
The mechanism of bicarbonate transport across the peritubular cell membrane was investigated in rat kidney proximal tubules in situ by measuring cell pH and cell Na+ activity in response to sudden reduction of peritubular Na+ and/or HCO
3
–
. The following observations were made: 1. sudden peritubular reduction of either ion concentration produced the same transient depolarizing potential response; 2. bicarbonate efflux in response to peritubular reduction of bicarbonate was accompanied by sodium efflux; 3. sodium efflux in response to peritubular sodium removal was accompanied by cell acidification indicating bicarbonate efflux; 4. all aforementioned phenomena were inhibited by SITS (10–3 mol/l) except for a small SITS-independent sodium efflux and depolarization which occurred in response to peritubular sodium removal and was not accompanied by cell pH changes; 5. bicarbonate efflux and accompanying potential changes in response to reduction of peritubular bicarbonate virtually vanished in sodium-free solutions. From these observations we conclude that bicarbonate efflux proceeds as rheogenic sodium-bicarbonate cotransport with a stoichiometry of bicarbonate to sodium greater than 1. The question which of the charged species of the bicarbonate buffer system moves cannot yet be decided. Attempts to determine the stoichiometry from the SITS-inhibitable initial cell depolarization and from the SITS-inhibitable initial fluxes suggest a stoichiometry of 3 HCO
3
–
: 1 Na+. In addition to sodium-dependent bicarbonate flux, evidence was obtained for a sodium-independent transport system of acids or bases which is able to regulate cell pH even in sodium-free solutions. 相似文献
38.
Histidine-rich protein genes and their transcripts in Plasmodium falciparum and P. lophurae 总被引:2,自引:0,他引:2
M Wallach D F Cully L O Haas W Trager G A Cross 《Molecular and biochemical parasitology》1984,12(1):85-94
The presence of histidine-rich protein (HRP) related genes and gene products in Plasmodium falciparum was demonstrated using a synthetic pentahistidine-encoding oligonucleotide and a cloned HRP cDNA probe prepared from the avian parasite P. lophurae. In Northern blotting experiments, two knobby clones of P. falciparum were found to contain a 3500 nucleotide RNA species that hybridized with the oligonucleotide and HRP cDNA probes. As this component had the expected size for an mRNA encoding an 80-90 kDa protein and was absent from two knobless clones of P. falciparum, we concluded that it represented a 'knob protein' mRNA. Using the restriction enzyme EcoRI, three identical cross-hydribizing HRP gene fragments were found in the DNA of both knobby and knobless clones of P. falciparum. These fragments differed in size from those present in P. lophurae. These results suggest that the absence of knob protein mRNA in knobless clones is not due to loss of the corresponding gene(s). 相似文献
39.
Using the ELISA technique we have been able to quantify antibodies directed against actin and to follow the kinetics of antibody production. Specific anti-actin antisera have been raised in rabbits by immunization with chemically modified white muscle rabbit actin. Two or three dinitrophenyl groups linked per actin molecule were sufficient to break natural tolerance, while linkage of three phosphorylcholine groups to actin was not. 相似文献
40.
Kotaro Kaneko Paul H. Guth Jonathan D. Kaunitz 《Pflügers Archiv : European journal of physiology》1992,421(4):322-328
Intracellular pH (pHi) and viability of gastric surface cells of the rat stomach in response to luminal acidification, and the role of Na+/H+ exchange in maintaining pHi homeostasis were studied in vivo using a fluorescent microscopic technique. pHi was measured during superfusion with buffers of pH 1.2–7.4. When the pH of the superfusate was 7.4, baseline pHi was unchanged. Superfusion with pH 3 buffer rapidly decreased pHi to 6.7, with subsequent recovery to baseline pHi within 15 min despite continuing acid exposure. Superfusion with buffers of pH 1.7 and 1.2 decreased pHi continuously to below 6.2 with no recovery observed. Despite the relentless decline in pHi during superfusion with pH-1.2 and –1.7 solutions, over 75% of the surface cells were still viable, as measured by exclusion of the vital dye propidium iodide. We then examined the role of Na+/H+ exchange in the regulation of pHi. Superfusion with amiloride did not affect recovery of pHi from intracellular acidification induced by a NH4Cl prepulse. Exposure to the potent, lipophilic Na+/H+ exchange inhibitor 5-(N,N-hexaniethylene)-amiloride (HMA), either in the superfusate or by close arterial perfusion, decreased baseline pHi from 7.1 to 6.8. Close arterial perfusion of HMA additionally attenuated the recovery of pHi to baseline during superfusion with pH 3 buffer. We conclude that luminal protons permeate into the cytoplasm of gastric surface cells, where they are eliminated by an Na+/H+ exchanger, most probably localized to the basolateral membrane. 相似文献