Protective effects of (6R)-5,6,7,8-tetrahydro-l-biopterin on local ischemia/reperfusion-induced suppression of reactive hyperemia in rat gingiva

We herein investigated the regulatory mechanism in the circulation responsible for rat gingival reactive hyperemia (RH) associated with ischemia/reperfusion (I/R). RH was analyzed using a laser Doppler flowmeter. RH and I/R were elicited by gingival compression and release with a laser Doppler probe. RH increased in a time-dependent manner when the duration of compression was between 30 s and 20 min. This increase was significantly suppressed by N^ω-nitro-l-arginine-methyl-ester (l-NAME), 7-nitroindazole (7-NI), and 2,4-diamino-6-hydroxypyrimidine (DAHP). However, RH was markedly inhibited following 60 min of compression. This inhibition was significantly decreased by treatments with superoxide dismutase (SOD), (6R)-5,6,7,8-tetrahydro-l-biopterin (BH₄), and sepiapterin. The luminescent intensity of superoxide anion (O₂^•−)-induced 2-methyl-6-(4-methoxyphenyl)-3,7-dihydroimidazo-[1,2-a] pyrazine-3-one (MCLA) was markedly decreased by SOD and BH₄, but only slightly by sepiapterin. BH₄ significantly decreased O₂^•− scavenging activity in a time-dependent manner. These results suggested that nitric oxide (NO) secreted by the nitrergic nerve played a role in regulating local circulation in rat gingiva. This NO-related regulation of local circulation was temporarily inhibited in the gingiva by the I/R treatment. The decrease observed in the production of NO, which was caused by suppression of NO synthase (NOS) activity subsequent to depletion of the NOS co-factor BH₄ by O₂^•−, played a partial role in this inhibition.     

Effects of some divalent cations on nitrergic relaxations in the mouse corpus cavernosum

Acute effects of some divalent cations (Cd²⁺, Ni²⁺, Co²⁺, Zn²⁺, Mn²⁺ and Sn²⁺) were investigated on neurogenic and endothelium-dependent relaxations in the isolated mouse corpus cavernosum. Neither neurogenic nor endothelium-dependent relaxation was affected by cations at the concentrations used (up to 100 μ M ), except Cd²⁺. Although Cd²⁺ (20 and 40 μ M ) did not cause any significant alteration in the acetylcholine- (ACh) or sodium nitroprusside- (SNP) induced relaxation, it inhibited electrical field stimulation- (EFS) produced relaxation significantly. Zn²⁺ and selenium could not reverse this inhibitory action. Cd²⁺ did block the EFS-evoked guanethidine-sensitive contraction in the presence of N^G-nitro- L -arginine. Elevation of external Ca²⁺ content significantly reduced the inhibitions due to Cd²⁺ on the EFS-induced relaxation and on the EFS-evoked guanethidine-sensitive contraction. In the Ca²⁺-omitted medium, EFS-induced relaxation disappeared, while acetylcholine-elicited relaxation resisted. Verapamil was ineffective on the relaxation produced by EFS or acetylcholine. However, it significantly diminished phenylephrine-induced contractions. These findings suggest that unlike other cations at the concentrations used in the present study, Cd²⁺ may have an effect on an external Ca²⁺-dependent mechanism at the neuronal level, and this effect may be responsible for its acute inhibitory action on the neurogenic relaxation in the mouse corpus cavernosum.     

Minimum recovery time between reactive hyperemia stimulus in the repeated measurement of brachial flow-mediated dilatation

The ability to undertake repeat measurements of flow-mediated dilatation (FMD) within a short time of a previous measurement would be useful to improve accuracy or to repeat a failed initial procedure. Although standard methods report that a minimum of 10 min is required between measurements, there is no published data to support this. Thirty healthy volunteers had five FMD measurements performed within a 2-h period, separated by various time intervals (5, 15 and 30 min). In 19 volunteers, FMD was also performed as soon as the vessel had returned to its baseline diameter. There was no significant difference between any of the FMD measurements or parameters across the visits indicating that repeat measurements may be taken after a minimum of 5min or as soon as the vessel has returned to its baseline diameter, which in some subjects may be less than 5 min.     

前列环素在超声心动图检测冠状动脉反应性充血扩张中作用的实验研究

目的评价前列环素在超声心动图检测冠状动脉反应性充血扩张中的作用.方法健康成年杂种犬10条.应用超声心动图仪重点检测股静脉内注射环氧化酶抑制剂吲哚美辛以抑制前列环素合成前后反应性充血试验诱发的冠状动脉左前降支内径的百分变化率.结果静脉内注射吲哚美辛后,反应性充血试验诱发的冠状动脉左前降支内径的百分变化率[(8.53±2.26)%]较注射吲哚美辛前[(12.77±1.76)%]明显减低(P＜0.01).结论超声心动图观察到的血流介导性冠状动脉内径的变化与内皮来源的扩血管物质前列环素有关.     

神经生长因子对损伤脊髓组织一氧化氮生成的影响

目的探讨神经生长因子（NGF）对脊髓损伤保护作用的机制。方法采用Allen's方法以0.1N×2.5cm致伤大鼠T8脊髓,插入蛛网膜下腔导管,于术后即刻及2、4、8、12和24小时各注入NGF溶液,并与生理盐水组和正常对照组作比较。采用免疫组织化学法检测神经元固有型一氧化氮合酶（ncNOS）在脊髓中的表达。结果与正常对照组比较,大鼠伤后脊髓前角运动神经元出现ncNOS蛋白异常表达,NGF组ncNOS蛋白异常表达较生理盐水组明显减少。结论NGF能通过抑制脊髓损伤后ncNOS的异常表达来抑制一氧化氮（NO）过多释放所致的神经毒性作用,从而保护损伤的脊髓组织。     

Inhibition of L-arginine transport by reactive oxygen species in rat anococcygeus muscle

The effect of L-arginine on nitrergic transmission and its alteration with reactive oxygen species (ROS) were investigated. L-arginine potentiated the relaxation response induced by electrical field stimulation in rat anococygeus muscle. This effect was inhibited by L-lysine, a cationic amino acid using y+ L and y+ transport systems in a similar way with L-arginine. The neutral amino acid L-leucine, which uses only y+ L system as a transport mechanism, inhibited this potentiation at only low frequency stimulation. Electrolysis of the physiological solution did not change the responses to electrical field stimulation, but inhibited the potentiation elicited by L-arginine that was prevented in the presence of mannitol and N-acetyl-L-cysteine. In conclusion, L-arginine is transported via y+ system predominantly to potentiate the relaxation response to nitrergic nerve stimulation in rat anococcygeus muscle. ROS, primarily hydroxyl radicals inhibited L-arginine-induced potentiation probably by interacting with the y+ amino acid transport system.     

Cutaneous reactive hyperaemia is unaltered by dietary nitrate supplementation in healthy humans

The purpose of this study was to determine whether nitrate supplementation augments cutaneous reactive hyperaemia. Seven participants were tested pre‐ and postnitrate supplementation (25 ml beetroot juice); participants consumed one shot per day for 3 days. Participants were instrumented with two microdialysis fibres: control (Ringer's solution) and NO synthase inhibition (20 mM L‐NAME). Skin blood flow was measured via laser‐Doppler flowmetry (LDF). A blood pressure cuff was placed on the experimental arm and inflated to 250 mmHg for 5 mins to occlude arterial inflow. The cuff was released, and the resultant reactive hyperaemia was measured. Blood pressure was continuously measured via plethysmography from a finger on the non‐experimental arm. Cutaneous vascular conductance was calculated (LDF/MAP) and normalized to maximal vasodilatation (%CVC_max). Only diastolic blood pressure was reduced following nitrate supplementation (71 ± 2 vs. 66 ± 1 mmHg; P<0·05). There was no effect of nitrate supplementation on peak reactive hyperaemia at control (Pre: 52 ± 3 vs. Post: 57 ± 2%CVC_max) or L‐NAME (Pre: 52 ± 2 vs. Post: 59 ± 4%CVC_max) sites. There was no effect of nitrate supplementation on total reactive hyperaemia at either control (Pre: 4197 ± 943 vs. Post: 4523 ± 1040%CVC_max * sec) or L‐NAME (Pre: 5108 ± 997 vs. Post: 5694 ± 1002%CVC_max * sec) sites. These data suggest cutaneous reactive hyperaemia is unaffected by dietary nitrate supplementation in healthy humans.     

神经生长因子对大鼠急性颅脑损伤的保护作用

目的：观察神经生长因子（NGF）对实验性急性颅脑损伤后大鼠神经病学评分和脑组织中一氧化氮合成酶（NOS）含量的影响,并探讨其作用机制。方法：①将27只急性颅脑损伤大鼠随机分为3组,分别用NGF、胞磷胆碱钠（CS）和生理盐水（NS）治疗,于治疗前后检查动物的神经病学评分改变。②再将65只急性颅脑损伤大鼠随机分为3组,即实验组（30只）、对照组（30只）和正常组（5只）。实验组急性颅脑损伤后即刻肌肉注射神经生长因子,对照组则注射等量生理盐水。对照组和实验组大鼠分别在脑损伤后1h、3h、6h、8h、24h断头取脑,对大鼠急性颅脑损伤后脑组织中NOS含量进行检测。结果：①与治疗前比较,NGF和CS组治疗后神经病学评分均降低（P〈0.05）;与盐水对照组比较,NGF和CS组治疗后神经病学评分均降低（P〈0.05）。②大鼠脑皮质中NOS活性在伤后1h、3h较正常组显著升高（P〈0.01）。神经生长因子实验组与盐水对照组比较,NOS含量在脑损伤后1h、3h、6hNOS含量明显下降（P〈0.05）。结论：NGF可明显促进急性脑损伤大鼠神经功能的恢复;NGF可通过抑制急性脑损伤后NOS的升高,抑制了一氧化氮的毒性作用,从而保护了脑神经元。     

Controlled ingestion of kaolinite (5%) modulates enteric nitrergic innervation in rats

We have previously shown that kaolinite slowed down gastric emptying and intestinal transit and induced changes in enteric mechanical activities. As gastric emptying and intestinal transit have been shown to be regulated by nitric oxide (NO), the effect of an imposed ingestion of kaolinite on enteric nitrergic innervation was determined. Kaolinite has also been shown to increase plasmatic levels of leptin. Therefore, the responses of enteric neurons in the presence of leptin after kaolinite ingestion were determined, and a possible role of nitrergic neurons was evaluated in rats using organ bath technique. Our results showed that kaolinite modulates activities of enteric nerves at 14 days of ingestion. Exogenous l ‐NNA produced a decrease in nerve stimulation (NS)‐induced relaxation in both jejunum and colon of control groups. At 14 days of kaolinite ingestion, this effect of l ‐NNA was significantly reduced only in the jejunum. Although l ‐NNA did not affect NS‐induced contraction in jejunum and colon of control animals, it increased the amplitude of the NS‐induced contraction in the colon of rats at 14 days of kaolinite ingestion. Leptin inhibitory effects on ENS in the jejunum were also altered at 14 days of ingestion. These differences were masked in the presence of l ‐NNA. Our data give evidence that changes in mechanical activities induced by kaolinite might be due to alterations in inhibitory (nitrergic and/or other) innervation at 14 days of kaolinite ingestion and to modifications of leptin effects on the responses to intramural nerve stimulation.     

神经生长因子对急性脑梗死大鼠神经功能和一氧化氮合酶含量的影响

目的 观察神经生长因子（NGF）对实验性急性脑梗死大鼠的疗效，初步探讨可能的机制。方法 将24只制备成的脑梗死模型大鼠随机分为3组，分别用神经生长因子（NGF）、胞磷胆碱钠（CS）和生理盐水（NS）治疗，于治疗前后检查动物的神经病学评分改变；再将55只大鼠随机分为实验组（25只）、对照组（25只）和正常组（5只），实验组急性脑梗死后即刻肌肉注射NGF，对照组注射等量NS。对照组和实验组大鼠分别在脑梗死后1h、3h、6h、12h、24h断头取脑，检测脑组织中一氧化氮合酶（NOS）含量。结果 与治疗前比较，NGF组和CS组大鼠治疗后神经病学评分均低于NS组（P〈0．05）；脑梗死大鼠梗死区脑组织中NOS活性在梗死后1h、3h较正常组明显升高（P〈0．01）；实验组大鼠NOS含量在脑梗死后1h、3h、6h较对照组明显下降（P〈0．01）。结论 NGF可明显促进急性脑梗死大鼠神经功能的恢复，机制之一可能是通过抑制急性脑梗死后NOS的活性起到保护损伤脑神经元的作用。     

Combined measurement of perfusion,venous oxygen saturation,and skeletal muscle T2* during reactive hyperemia in the leg

Background

The function of the peripheral microvascular may be interrogated by measuring perfusion, tissue oxygen concentration, or venous oxygen saturation (SvO₂) recovery dynamics following induced ischemia. The purpose of this work is to develop and evaluate a magnetic resonance (MR) technique for simultaneous measurement of perfusion, SvO₂, and skeletal muscle T₂*.

Methods

Perfusion, Intravascular Venous Oxygen saturation, and T₂* (PIVOT) is comprised of interleaved pulsed arterial spin labeling (PASL) and multi-echo gradient-recalled echo (GRE) sequences. During the PASL post-labeling delay, images are acquired with a multi-echo GRE to quantify SvO₂ and T₂* at a downstream slice location. Thus time-courses of perfusion, SvO₂, and T₂* are quantified simultaneously within a single scan. The new sequence was compared to separately measured PASL or multi-echo GRE data during reactive hyperemia in five young healthy subjects. To explore the impairment present in peripheral artery disease patients, five patients were evaluated with PIVOT.

Results

Comparison of PIVOT-derived data to the standard techniques shows that there was no significant bias in any of the time-course-derived metrics. Preliminary data show that PAD patients exhibited alterations in perfusion, SvO₂, and T₂* time-courses compared to young healthy subjects.

Conclusion

Simultaneous quantification of perfusion, SvO₂, and T₂* is possible with PIVOT. Kinetics of perfusion, SvO₂, and T₂* during reactive hyperemia may help to provide insight into the function of the peripheral microvasculature in patients with PAD.     

神经生长因子对大鼠脑缺血再灌注损伤的保护作用

目的：探讨神经生长因子（NGF）对大鼠脑缺血再灌注损伤的保护作用及其机制。方法：采用大脑中动脉内栓线阻断法（MCAO）造成大鼠局灶性损伤模型，同时给予NGF治疗。观测神经评分改变，计算脑组织梗死灶，测定脑组织含水量以及一氧化氮合酶（NOS）活动的变化。结果：NGF治疗组神经评分明显降低（P〈0.05）；与脑缺血再灌注组比较，NGF治疗组脑缺血梗死区缩小，脑组织含水量和NOS活性明显降低（P〈0．05）。结论：NGF具有保护脑缺血再灌注损伤的作用，可能与抑制NOS的活性有关。     

Effects of chronic treatment with a nitric oxide donor on nerve conduction abnormalities and endoneurial blood flow in streptozotocin-diabetic rats

Abstract. This study examined the ability of nitrova-sodilator treatment with isosorbide dinitrate to prevent the development of reduced nerve conduction velocity and nutritive blood flow in streptozotocin-induced diabetes mellitus in rats. Two month untreated diabetes caused approximately 23% and 13% reductions in sciatic motor and saphenous nerve sensory conduction velocity ( P < 0.001). Isosorbide dinitrate treatment provided 64.6 and 67.6% protection for motor and sensory nerves, respectively ( P < 0.01). Sciatic endoneurial nutritive blood flow was measured by microelectrode polarography and a hydrogen clearance technique. After 1 month untreated diabetes, flow was reduced by 41.9% ( P < 0.001). Isosorbide dinitrate treatment for 1 month in non-diabetic and diabetic rats significantly increased blood flow ( P < 0.01). When between-group variations in blood pressure were taken into account, vascular conductance increased by 29% and 31% in non-diabetic and diabetic rats, respectively ( P < 0.01). Thus, nitrovasodilator treatment improves nerve perfusion and function in experimental diabetes, probably by compensating for reduced endothelium-derived nitric oxide release or action.     

Nitric oxide in vascular biology

Summary.  Nitric oxide is a highly versatile heterodiatomic molecule that effects a variety of actions in the vasculture. Originally identified as a principal determination of vascular tone, nitric oxide has since been recognized to exert anti thrombotic, antiproliferative, and anti-inflammatory effects in the vasculture. At higher concentrations and in the setting of other oxidants, nitric oxide can promote vascular pathology. In this review, we summarize the molecular mechanisms of nitric oxides actions in vascular biology and pathology.     

一氧化氮在超声心动图检测冠状动脉反应性充血扩张中的作用

目的评价一氧化氮(NO)在超声心动图检测冠状动脉反应性充血扩张中的作用。方法健康成年杂种犬12条。应用超声心动图仪分别观察记录基础状态反应性充血试验前后、冠状动脉内注射NO合成抑制剂LNAME时反应性充血试验前后的二维图像。测量冠状动脉左前降支内径(LADd)并计算内径百分变化率。结果基础状态下,反应性充血试验后LADd明显增宽[由(2.23±0.19)mm增为(2.52±0.24)mm,P<0.01],内径百分变化率为(13.10±3.59)%。冠状动脉内注射LNAME时,反应性充血试验前、后LADd与基础状态反应性充血试验前LADd相比差异无显著性意义,内径百分变化率为(1.07±2.97)%,较基础状态显著减小(P<0.001)。结论超声心动图观察到的血流介导性冠状动脉内径的变化与内皮来源的扩血管物质NO有关,超声心动图可用于检测冠状动脉内皮依赖性扩张功能。     

Nitric oxide, a double edged sword in cancer biology: searching for therapeutic opportunities

Nitric oxide (NO) is a pleiotropic molecule critical to a number of physiological and pathological processes. The last decade has witnessed major advances in dissecting NO biology and its role in cancer pathogenesis. However, the complexity of the interactions between different levels of NO and several aspects of tumor development/progression has led to apparently conflicting findings. Furthermore, both anti-NO and NO-based anticancer strategies appear effective in several preclinical models. This paradoxical dichotomy is leaving investigators with a double challenge: to determine the net impact of NO on cancer behavior and to define the therapeutic role of NO-centered anticancer strategies. Only a comprehensive and dynamic view of the cascade of molecular and cellular events underlying tumor biology and affected by NO will allow investigators to exploit the potential antitumor properties of drugs interfering with NO metabolism. Available data suggest that NO should be considered neither a universal target nor a magic bullet, but rather a signal transducer to be modulated according to the molecular makeup of each individual cancer and the interplay with conventional antineoplastic agents.     

Multicenter,open-label evaluation of hyperemia associated with use of bimatoprost in adults with open-angle glaucoma or ocular hypertension

This month-long multicenter, open-label study evaluated the onset and progression of hyperemia associated with bimatoprost 0.03% once daily in 39 patients with open-angle glaucoma or ocular hypertension. Current glaucoma medication(s) was either replaced with or augmented by bimatoprost. Previous users of bimatoprost were excluded. Primary outcome measures were mean hyperemia scale scores (ciliary, conjunctival, and episcleral, graded on a seven-point scale) and incidence of hyperemia. Secondary outcome measures were fluorescein staining, patient assessment of ocular redness (take-home diary), and patient and investigator evaluations. Patients were asked how troubled they were by their ocular redness. Investigators were asked if they would continue the patient on bimatoprost despite the hyperemia. Overall, the frequency and severity of hyperemia peaked approximately 1 day after the first instillation of bimatoprost and decreased consistently throughout the study, returning to near-baseline levels by day 28. At day 1, 84.6% of patients were hardly troubled or not troubled by their ocular redness; only 15.4% were somewhat or moderately troubled. Investigators indicated that they would continue bimatoprost therapy in 92.3% of the patients. Hyperemia did not represent a significant safety concern.     

Inducible nitric oxide synthase: Regulation,structure, and inhibition

A considerable number of human diseases have an inflammatory component, and a key mediator of immune activation and inflammation is inducible nitric oxide synthase (iNOS), which produces nitric oxide (NO) from l -arginine. Overexpressed or dysregulated iNOS has been implicated in numerous pathologies including sepsis, cancer, neurodegeneration, and various types of pain. Extensive knowledge has been accumulated about the roles iNOS plays in different tissues and organs. Additionally, X-ray crystal and cryogenic electron microscopy structures have shed new insights on the structure and regulation of this enzyme. Many potent iNOS inhibitors with high selectivity over related NOS isoforms, neuronal NOS, and endothelial NOS, have been discovered, and these drugs have shown promise in animal models of endotoxemia, inflammatory and neuropathic pain, arthritis, and other disorders. A major issue in iNOS inhibitor development is that promising results in animal studies have not translated to humans; there are no iNOS inhibitors approved for human use. In addition to assay limitations, both the dual modalities of iNOS and NO in disease states (ie, protective vs harmful effects) and the different roles and localizations of NOS isoforms create challenges for therapeutic intervention. This review summarizes the structure, function, and regulation of iNOS, with focus on the development of iNOS inhibitors (historical and recent). A better understanding of iNOS’ complex functions is necessary before specific drug candidates can be identified for classical indications such as sepsis, heart failure, and pain; however, newer promising indications for iNOS inhibition, such as depression, neurodegenerative disorders, and epilepsy, have been discovered.     

牙龈鳞癌中WWOX基因的表达及其临床意义

目的：研究WWOX基因在牙龈鳞癌组织中的表达及意义。方法：应用免疫组化SP法检测70例牙龈鳞癌组织中WWOX基因的表达,并与临床病理指标结合进行分析。结果：牙龈鳞癌组织中ww0X基因的阳性率为27．14％。WWOX基因的表达与牙龈鳞癌的病理分级、淋巴结转移有相关性（P〈0．05）,与临床分期明显相关（P〈0．05）。WWOX基因在牙龈鳞癌中的表达呈负相关性。结论：WWOX基因参与牙龈鳞癌的发生发展过程,可作为评估牙龈鳞癌生物学行为的一项指标,用于识别高危转移和不良预后者及为判断其生物学特性提供可靠的指标。