糖尿病肾病患者血清TRPM7、Sirtuin-1与钙磷代谢、颈动脉钙化的相关性

目的 探讨糖尿病肾病（DN）患者血清瞬时受体电位通道7(TRPM7)、沉默调节蛋白-1(Sirtuin-1)与钙磷代谢、颈动脉钙化的相关性。方法 选取2020年12月—2022年11月成都大学附属医院收治的97例DN患者作为DN组,另取同期在该院就诊的120例2型糖尿病患者作为对照组。采用实时荧光定量聚合酶链反应检测血清TRPM7的表达,酶联免疫吸附试验检测血清Sirtuin-1水平。采用Pearson法分析DN患者血清TRPM7、Sirtuin-1水平与钙磷代谢的相关性,并通过多因素Logistic逐步回归模型分析DN患者颈动脉钙化的危险因素。结果 DN组血肌酐、尿素氮、血清TRPM7、血磷、颈动脉钙化率高于对照组（P <0.05）。DN组Sirtuin-1、血钙低于对照组（P <0.05）。Pearson相关性分析结果显示,DN患者血清TRPM7与血钙呈负相关（r=-0.247,P=0.000）,与血磷呈正相关（r=0.415,P=0.000）;DN患者血清Sirtuin-1与血钙呈正相关（r=0.367,P=0.000）,与血磷呈负相关（r=-0.505,P=0.00...     

Anion channels in a leaky epithelium

We have used the patch-clamp technique to characterize three anion channels in the ventricular membrane of the choroid plexus epithelium from Necturus. The most frequently occurring channel had a nonlinear IV-curve. The conductance in excised patches with 112 mM chloride at both sides was 28 pS at 0 mV, increasing towards positive membrane potentials. The selectivity ratios were P _NaP _Cl 0.1 and . SITS and furosemide (1 mM) on the inside reduces chloride flux to 0.15 and 0.37 times the control value. In attached patches, the most commonly observed channel had a conductance of 7.5 pS. The single-channel current for this channel reversed direction at 15 mV hyperpolarization, indicating accumulation of chloride to a factor of 1.8 above equilibrium. External stimulation of the tissue by theophylline, IBMX and dbcAMP, or by hypotonic shock did not increase the activity of this channel. In very few excised patches, we have observed a chloride channel with a conductance of 7 pS with 112 mM chloride at both sides. The 7 pS channel appears to be identical to a 2 pS channel found in attached patches. The 2 pS channel was not normally active in attached patches but was activated in 28% of the patches by external stimulation. Finally, in few excised patches we have found a 375 pS channel which inactivates within seconds when membrane potential is stepped from 0 mV to a value that differs more than 10–20 mV from zero. The channel did not conduct gluconate but and P _NaP _Cl 0.1. Internal SITS and furosemide (1 mM) reduced chloride flux to 0.3 and 0.5 times the control value. The channel was never seen in attached patches. The current carried through these channels can not account for the transepithelial steady state Cl^–-flux measured by microelectrodes. KCl exit from the cell is suggested to be carried by KCl-cotransport or by channels that are too small to be seen in patch-clamp experiments.     

Reciprocal interactions between α2-adrenoceptor agonist and neuropeptide Y binding sites in the nucleus tractus solitarius of the rat

Summary Interactions between a ₂-adrenoreceptor agonist and neuropeptide Y (NPY) binding sites have been studied in the rat medulla oblongata (MO) using biochemical binding techniques as well as quantitative autoradiography. Tritiated para-amino clonidine (³H-PAC; ₂-adrenoceptor agonist), idazoxan (³H-IDA; ₂-adrenoceptor antagonist) and iodinated neuropeptide Y (¹²⁵I-NPY) were used as radioligands. (1) Neuropeptide Y (NPY; 10^–8M) but not bovine pancreatic polypeptide (BPP) nor peptide YY (PYY 10nM) increased the K_D value of³H-PAC binding sites. However, intraventricular administration of a high dose of NPY (1.25nmol) did not change the³H-PAC binding characteristics in MO membrane preparations of these animals. (2) GTP 10^–4 lowered the affinity of³H-PAC binding. NPY (10 nM) had no additional effect, nor did NPYinfluence the GTP induced shift in potency of clonidine to displace³H-IDA from its binding sites. (3) In the autoradiographical experiments NPY (10nM) significantly reduced³H-PAC binding (2nM) in the nucleus tractus solitarius (NTS) area by 35%. (4) When clonidine, either given centrally in vivo (3.75nmol) or in vitro (10 nM) the binding of¹²⁵I-NPY was reduced (34 and 24%, respectively) in the NTS. When the monoamine receptors were irreversibly blocked in vivo by N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ, 10 g i.e. 24h)¹²⁵I-NPY (0.5 nM) binding was increased by 137% in the NTS. This effect of EEDQ was prevented by pretreatment with the ₂-adrenoreceptor antagonist idazoxan.These results provide support for a direct intramembrane interaction between the ₂-receptor and the NPY receptor within the NTS and may be of importance in central cardiovascular regulation.     

Interaction between clonidine and physostigmine in normal rats and in rats after sinoaortic denervation

Summary Clonidine (3–30 g · kg^–1, i.v.) induced a fall in mean arterial pressure in rats after sinoaortic denervation but not in sham-operated animals. Moreover, sinoaortic denervation reduced the bradycardic action of this antihypertensive drug. Pressor and tachycardic response to physostigmine (60 g · kg^–1, i.v.) were greater in denervated than in sham-operated rats. The increase of mean arterial pressure was 26.2 ± 2.2 mm Hg in sham-operated rats (n = 12) and 53.8 ± 2.0 mm Hg in denervated rats (n = 12, P < 0.005).Pretreatment with 3 g · kg^–1 (i. v.) of clonidine did not alter the pressor response to physostigmine (60 g · kg^–1) in either of the two groups; 10 and 30 g · kg^–1 of clonidine reduced the physostigmine-induced increase of mean arterial pressure in sham-operated rats but enhanced the pressor response in denervated animals. Furthermore, an ineffective dose of physostigmine (30 g - kg^–1 i.v.) induced a pressor response after pretreatment with clonidine (10 gg · kg^–1) in denervated rats.Clonidine (10 g · kg^–1) did not affect the pressor effect of 1,1 dimethyl-4-phenylpiperazinium iodide (DMPP: 50 g · kg^–1 i.v.) or phenylephrine (4 g · kg ^–1, i.v.) in either group.The anticholinergic effect of clonidine in sham-operated rats may be explained by an inhibitory action on the release of acetylcholine in several brain structures but the facilitatory effect of clonidine observed in denervated animals is not clear. The results did not suggest a peripheral involvement in this facilitatory effect. Send offprint requests to M. A. Enero at the above address     

Role of histamine receptor in mesencephalic nucleus dorsalis raphe in cardiovascular regulation

Summary The effects of microinjection of histamine and its antagonists into mesencephalic nucleus dorsalis raphe, were investigated on mean arterial pressure and heart rate in cats to elucidate the nature and role of histaminergic receptors in cardiovascular regulation. Microinjection of histamine (5 and 10 g) into nucleus dorsalis raphe elicited both inhibitory and excitatory cardiovascular responses respectively. On the other hand, microinjection of H₂-receptor blocker, cimetidine (10 g) resulted in hypertension and tachycardia while H₁-receptor antagonist, mepyramine (10 g) microinjection evoked hypotension and bradycardia. Furthermore, local pretreatment with cimetidine and mepyramine blocked the inhibitory and excitatory cardiovascular responses of graded doses of histamine microinjection. These H₁ and H₂ receptors are localized in nucleus dorsalis raphe since microinjection of histamine into adjoining neural structures did not evoke any cardiovascular change. Furthermore, both the inhibitory and excitatory cardiovascular responses to histamine microinjection could not be observed in animals with spinal cord transection and in animals pretreated with p-chlorophenylalanine while they could be observed in bilateral cervical vagotomized animals. Thus, it appears that these cardiovascular responses to microinjection of histamine into nucleus dorsalis raphe, are due to modulation of serotonergic bulbospinal influence on sympathetic preganglionic neurones in the spinal cord. Moreover, the excitatory cardiovascular responses of high dose of histamine (10 g) seem to result from a local release of noradrenaline since they were blocked by prior microinjection of guanethidine and piperoxan into nucleus dorsalis raphe. A release of noradrenaline in turn, modulates the activity of the neurones of the nucleus by acting on adrenoceptors and thereby alters the activity of sympathetic preganglionic neurones. These adrenoceptors appear to be of ₁ type (Saxena et al. 1985, 1987) since phenylephrine microinjection evoked excitatory cardiovascular responses could be blocked by piperoxan. Send offprint requests to K. K. Tangri at the above address     

Plateau potentials evoked by climbing-fibre stimulation are restricted to the Purkinje cell dendrites of the cat

The present study investigated the duration of afterdepolarizations in Purkinje cell somata following climbing-fibre activation. Intracellular recordings revealed that, in cells with membrane potentials more negative than -50 mV and with normal spike-generating capabilities, climbing-fibre activation resulted in somatic responses with short afterdepolarizations. As the cell deteriorated and the resting membrane potential became more positive, the duration and form of the climbing-fibre response resembled the plateau potentials recorded from proximal dendrites. The absence of plateau potentials in undamaged Purkinje cell somata was confirmed by extracellular recording of test spike amplitudes following evoked climbing-fibre responses.     

Qualitative difference between the cytotoxic T lymphocyte responses to melanocyte antigens in melanoma and vitiligo

Vitiligo is a skin disorder characterized by depigmented macules secondary to melanocyte loss. An unusual facet is its relation to melanoma: cytotoxic T lymphocytes directed to melanocyte antigens are found in both conditions and imply a breakdown of tolerance, yet the resulting immune reaction is the opposite. The mechanisms at the basis of these opposite effects are not known. Here, we performed a direct comparison of whole melanocyte-specific T cell populations in the two diseases. We demonstrate that neither precursor frequencies of Melan-A/MART-1-specific T lymphocytes nor their status of activation differ significantly. However, by using a tetramer-based T cell receptor down-regulation assay, we documented a higher affinity of vitiligo T cells. We calculated that the peptide concentration required for 50% of maximal receptor down-regulation differed by 6.5-fold between the two diseases. Moreover, only vitiligo T cells were capable of efficient receptor down-regulation and IFN-gamma production in response to HLA-matched melanoma cells, suggesting that this difference in receptor affinity is physiologically relevant. The differences in receptor affinity and tumor reactivity were confirmed by analyzing Melan-A/MART-1-specific clones established from the two diseases. Our results suggest that the quality, and not the quantity, of the melanocyte-specific cytotoxic responses differs between the two pathologies.     

The induction of baboon glycodelin expression by progesterone is not through Sp1

Glycodelin is a major secretory product of the uterine glandular epithelial cells of the human and non-human primate during the late luteal phase of the menstrual cycle and early pregnancy. Since progesterone levels are elevated during these periods we sought to determine how progesterone modulates glycodelin gene expression. Co-transfection of various deletions of the baboon glycodelin promoter with the progesterone receptor (PR) into Ishikawa cells, a human endometrial cell line, revealed that full progesterone responsiveness is retained within the region -119/+48. In COS-1 cells, a kidney cell line, progesterone failed to elevate luciferase levels when various deletion constructs and the PR were co-transfected. Mutation of the Sp1 site in the -67/+48 region lowered basal expression but did not affect the ability of progesterone to increase expression of the luciferase reporter in Ishikawa cells. These findings suggest that Sp1 sites are not involved in the progesterone regulation of the baboon glycodelin gene. We propose that progesterone induces a factor that regulates glycodelin gene expression in the uterus since we failed to obtain a similar response in a non-uterine cell line.     

Autoantibodies to heat shock protein 90 in the human natural antibody repertoire

The present study demonstrates the presence of natural autoantibodies of the IgG isotype directed against heat shock protein 90 (HSP90). The binding properties of affinity-purified anti-HSP antibodies were compared with those of natural antibodies specific for other self antigens, including anti-thyroglobulin and anti-myoglobin autoantibodies, by using semiquantitative immunoblotting, with solubilized proteins from normal liver tissue as antigens, and cross-blot analysis using purified self proteins. Affinity-purified anti-HSP90 antibodies were polyreactive and the non-HSP90-specific fraction of normal IgG was depleted in its natural autoantibody content. We further observed that self antigens including HSP, myosin, tubulin and aldolase with highly conserved structures show similar patterns of binding with natural antibodies, and form a well-defined cluster as demonstrated by cluster analysis of immunoreactivity data, whereas the less-conserved self and non-self antigens remained unclustered. The results favor the hypothesis that HSP90 belongs to a subset of highly conserved and immunodominant self antigens that are the primary target for natural autoantibodies in normal human IgG.