钙调蛋白激酶II抑制剂KN-93对离体肥厚大鼠心脏电生理特性的影响

KN-93是钙调蛋白激酶II特异性抑制剂,被广泛应用于基础研究,且显现出良好的抗心律失常作用。然而关于KN-93对整体心脏电生理特性影响的研究较少,本研究旨在阐明KN-93对离体肥厚心脏电生理特性的影响,阐明KN-93抗心律失常的特性。方法：雄性SD大鼠40只,随机分为假手术组(Sham组)、心肌肥厚组(Hypertrophy,HY组)。缩窄腹主动脉制作心肌肥厚模型。手术6周后,超声心动图评价模型;运用Langendorff心脏离体灌流电生理技术检测整体心脏电生理特性,微电极阵列技术评价心脏传导情况。结果：手术6周后,左室后壁舒张末期厚度及室间隔舒张末期厚度明显增厚,提示心肌肥厚造模成功。与Sham组相比,HY组心室各部位的单向动作电位时程(APD90)显著延长(P均<0.01),有效不应期(ERP)也显著延长(P均<0.01);诱发动作电位电交替阈值中位数明显增大(P<0.01);传导的时间离散度明显增大(P<0.01),且室性心律失常的诱发率明显升高(P<0.05)。HY组使用CaMKII抑制剂KN-93后,APD90和ERP并无显著变化,APD电交替阈值也无明显改变,但传导的时间离散度明显减小(P<0.001),室性心律失常的诱发率减少(P<0.05)。结论：CaMKII抑制剂KN-93对离体肥厚大鼠心脏APD90、ERP、 APD电交替阈值均无明显影响,但能显著减小传导速度离散度;对传导的影响可能是KN-93抗心律的重要机制。     

葡萄糖浓度变化对乳鼠心肌细胞的影响及其机制的探讨

目的 观察不同浓度的葡萄糖培养对乳鼠心肌细胞形态及功能的影响,并初步探讨其机制.方法 建立乳鼠心肌细胞培养模型,随机分成低糖(5.5 mmol/L)组、高糖(25.5 mmol/L)组、间歇性高糖(5.5 mmol/L和25.5 mmol/L交替培养)组以及高糖(25.5 mmol/L)+蛋白激酶C(PKC)抑制剂Ro-31-8220(50 nmol/L)组,培养5 d后,观察心肌细胞搏动情况,测定心肌细胞直径,并应用Western blot检测心肌细胞PKC-α、PKC-β2、p-PKC-α、p-PKC-β2、核因子(NF)-κB和c-fos的蛋白表达水平.结果 不同浓度葡萄糖培养的心肌细胞在搏动频率、细胞直径以及PKC-α、PKC-β2、p-PKC-α、p-PKC-β2、NF-κB和c-fos的蛋白表达水平存在差异,其中高糖组心肌细胞搏动频率、细胞直径以及PKC-α、PKC-β2、p-PKC-α、p-PKC-β2、NF-κB和c-fos的蛋白表达水平显著高于低糖组[高糖组比低糖组:搏动频率(64.15±1.55)次/min比(57.22±1.91)次/min,细胞直径(20.11±0.91)μm比(17.18±0.82)μm,P均＜0.01],间歇性高糖组的上述指标则显著高于高糖[间歇性高糖组比高糖组:搏动频率(66.60±2.02)次/min比(64.15±1.55)次/min,细胞直径(22.39±0.92)μm比(20.11±0.91)μm,P均＜0.01]和低糖组[间歇性高糖组比低糖组:搏动频率(66.60±2.02)次/min比(57.22±1.91)次/min,细胞直径(22.39±0.92)μm比(17.18±0.82)μm,P均＜0.01],而PKC抑制剂Ro-31-8220则能逆转高糖所诱导的上述变化[高糖+PKC抑制剂Ro-31-8220组比高糖组:搏动频率(62.17±1.58)次/min比(64.15±1.55)次/min,细胞直径(18.41±0.78)μm比(20.11±0.91)μm,P均＜0.01].结论 高糖或间歇性高糖的环境能够导致心肌细胞肥大,搏动频率增加,同时影响心肌细胞PKC-α、PKC-β2、NF-κB和c-fos的表达和活性,而PKC抑制剂Ro-31-8220能够逆转高糖所诱导的上述变化.因此高糖特别是间歇性高糖可能通过PKC/NF-κB/c-fos途径诱导了心肌细胞结构和功能的改变,导致了糖尿病心肌损害.     

低强度神经节丛刺激对正常心室电生理性质和急性心肌缺血室性心律失常发生的影响

目的 研究低强度神经节丛(GP)刺激对正常心室电生理性质和急性心肌缺血室性心律失常发生的影响.方法 体重18～25kg的正常成年杂种犬39只随机分为正常心脏组(n=12)和急性心肌缺血组(n=27,其中对照组12只,低强度GP刺激组15只),以2根多极电生理导管记录左、右心室局部电图,以自制Ag-AgC1电极记录左、右心室单相动作电位.在正常犬,分别在6h低强度GP刺激前和刺激后测量心室各部位有效不应期(ERP)、动作电位时限(APD),APD回复性质和APD交替以及血清乙酰胆碱和去甲肾上腺素浓度;在急性心肌缺血犬,比较室性心律失常的发生情况.结果 在正常犬,6h低强度GP刺激显著延长心室各部位ERP及APD(P＜0.05),但未改变其空间离散度;6h低强度GP刺激促进APD交替发生但不改变APD回复曲线斜率及其空间离散度;6h低强度GP刺激后血清去甲肾上腺素和乙酰胆碱水平均显著增加(P＜0.05).在急性心肌缺血犬,低强度GP刺激组室性心律失常的发生率显著低于对照组(P＜0.05).结论 低强度GP刺激不增加正常心脏室性心律失常的风险且有助于抑制急性心肌缺血心脏室性心律失常的发生.     

钙敏感受体对血管紧张素Ⅱ诱导大鼠心肌细胞肥大的作用

目的 观察钙敏感受体(CaSR)在血管紧张素Ⅱ(Ang Ⅱ)诱导心肌细胞肥大中的作用和可能机制.方法 用Ang Ⅱ处理原代新生大鼠心室肌细胞复制心肌肥大细胞模型;用CaSR激动剂氯化钆(GdCl3),GdCl3+蛋白激酶C(PKC)通路阻断剂(Ro318220)处理AngⅡ诱导的肥大心肌细胞分别作为GdCl3、Ro318220组.通过苏木素-伊红染色(HE)法测定细胞直径,考马斯亮蓝蛋白试剂盒测定蛋白含量来评价细胞肥大的情况;利用激光共聚焦显微镜检测心肌细胞内钙浓度([Ca2+]i;Western blot法检测CaSR和PKC通路的蛋白表达.结果 ①与对照组(0.1263±0.0443)比较,Ang Ⅱ组(0.1963±0.0375)和GdCl3组(0.2778±0.0564)CaSR蛋白表达明显增加(P均＜ 0.05),且GdCl3组明显高于AngⅡ组(P＜0.05).②与对照组(222.70±22.09)比较,Ang Ⅱ组(392.16±36.85)和GdCl3组(502.60±44.21)心肌细胞内[Ca2+]i显著增加(P均＜0.05);与Ang Ⅱ组比较,GdCl3组[Ca2+]i显著增加(P＜0.05).③与对照组比较,Ang Ⅱ可诱导心肌细胞肥大,GdCl3可促进Ang Ⅱ的诱导作用,而Ro318220可抑制GdCl3的作用;④与对照组(0.27±0.07、0.69±0.06、0.87±0.04)比较,Ang Ⅱ组PKCα、PKCε和PKCδ蛋白表达明显增加(0.60±0.16、1.02±0.13、1.20±0.18,P均＜0.05),GdCl3组PKCα、PKCε蛋白表达明显增加(0.82±0.16、1.34±0.12,P均＜0.05);与Ang Ⅱ组比较,GdCl3组PKCα、PKCε蛋白表达明显增加(P均＜ 0.05);与GdCl3组比较,Ro318220组PKCα、PKCε蛋白表达(0.41±0.10、0.85±0.14)明显减少(P均＜ 0.05).结论 PKC通路参与CaSR激活促进心肌细胞肥大的信号转导.     

蛋白激酶C、内皮素与核因子-κB在糖尿病早期视网膜中的实验观察

目的观察糖尿病早期视网膜中蛋白激酶C(PKC)、内皮素(ET)系统与核因子-κB(NF-κB)的表达变化,并探讨PKC抑制剂对上述因子的影响。方法将SD大鼠分为正常对照(NC)组与糖尿病(DM)组,STZ诱导糖尿病大鼠模型。ELISA及Western blot检测视网膜PKC活性及亚型的表达,QRT-PCR检测不同时间点视网膜ETs和NF-κB p65基因表达及12周时PKC抑制剂对上述基因的影响。结果 12周时,DM组视网膜组织细胞膜PKC活性较NC组增加(t=6.36,P=0.00),细胞浆PKC活性无明显改变;PKC-α、PKC-β_1、PKC-β_2、PKC-δ蛋白表达均较NC组增多(t=5.69、4.71、4.10、3.753,P0.05),以PKC-β_2增加最明显,PKC-ε无改变;ETs及NF-κB p65 mRNA在不同时间点出现表达水平的上调,其中,ET-1及NF-κB出现最早;PKC抑制剂使视网膜ETs及NF-κB p65 mRNA表达呈浓度依赖性下降。结论 ETs及NF-κB的异常激活可能是PKC影响DR发生发展的作用机制之一。     

左心室M层起搏对犬跨室壁复极离散的影响

目的 研究心室M层起搏对犬跨室壁复极离散(TDR)的影响,探讨采用心室M层起搏技术防治跨室壁复极离散增大相关性心律失常的可行性.方法 制作犬左心室楔形心肌组织块模型,观察心内、外膜及M层起搏时,各层心肌动作电位时限(APD)及TDR的变化.结果 分别行心室肌内、外膜和M层起搏,心肌各层APD差异无统计学意义(P＞0.05)；但M层起搏时,TDR较外膜起搏明显减小[(34.9±5.4)ns对(71.5±6.1)ms,P＜0.01]；与内膜起搏相比差异无统计学意义[(34.9±5.4)ms对(35.9±5.4)ms,P＞0.05].结论 与心外膜起搏相比,M层起搏可有效减小TDR；但与心内膜起搏相比,差异无统计学意义.     

阻断神经元型Nav1.8通道对心脏交感神经节活性和心室电生理性质的影响

目的探讨阻断神经元型Nav1.8通道对正常犬心脏交感神经节活性和心室电生理性质的影响。方法16只健康成年犬(16~18kg)随机分为实验组(n=8)和对照组(n=8)。分离左侧心脏交感神经节,实验组向神经节内注射20mmol/L的Nav1.8通道特异性阻断剂(A-803467)0.1 ml,对照组向神经节内注射等体积的二甲基亚枫。在基础状态和药物注射60min后,分别记录左侧心脏交感神经节活性,并测定心室有效不应期(ERP)和动作电位时程(APD)。结果实验组在干预后心脏交感神经节的放电频率[(45±6)次/分vs(83±7)次/分,P0.05]和幅度[(0.03±0.01)mV vs(0.05±0.01)mV,P0.05]均显著降低,心室各部位ERP和APD_(90)显著延长,ERP离散度[(13±5)ms vs(21±4)ms,P0.05]和APD_(90)离散度[(22±10)ms vs(38±14)ms,P0.05]显著降低。而对照组以上指标无显著性改变(P0.05)。结论阻断Nav1.8通道可显著降低心脏交感神经节活性,提高心室电生理稳定性。阻断Nav1.8通道可能具有抑制室性心律失常的作用。     

胺碘酮慢性作用对兔心室肌细胞L型钙通道电流和跨壁动作电位相关性研究

目的 从单个心室肌细胞L型钙通道电流时间常数(τ)和组织块跨壁动作电位复极90%时程(APD90),探讨胺碘酮慢性作用抗心律失常的可能细胞电生理机制.方法 健康兔口服胺碘酮80 mg·kg-1·d-1共4周,记录离体兔带血管心室肌组织块跨膜心室肌细胞动作电位后分离心室肌细胞,记录单细胞L型钙通道电流τ,比较对照组、胺碘酮组及索他洛尔组干预下τ与APD90比值(τ/APD90)变化.结果 对照组τ为(98±8)ms(n=10)、APD90为(220±10)ms(n=5)、τ/APD90为0.44±0.03.与对照组相比,胺碘酮组τ明显延长[为(164±8)ms,n=8,P＜0.05],APD90亦明显延长[为(321±12)ms,n=5,P＜0.05],τ/APD90较对照组增加(分别为0.51±0.03与0.44±0.03,P＜0.05).索他洛尔(3×10-5mmoL/L)组与对照组相比,τ明显延长[为(128±7)ms,n=8,P＜0.05],但因APD90延长较著[为(405±13)ms,n=4,P＜0.01],使τ/APD90较对照组明显减少(分别为0.32±0.05与0.44±0.03,P＜0.05).索他洛尔+胺碘酮组的τ为(150±12)ms、APD90为(355±11)ms(n=4),与索他洛尔组比较,τ/APD90增加(为0.44±0.02,P＜0.05),与对照组相比,差异无统计学意义(P＞0.05).结论 心室肌细胞膜L型钙通道电流的τ/APD90大小与胺碘酮慢性作用相关,这为胺碘酮慢性作用的安全性提供了一种可能解释.     

程序电刺激时心室复极离散度的研究

了解程序电刺激 (PES)时心室复极离散度的变化 ,探讨PES诱发室性快速心律失常 (VTA)的可能机制。采用单相动作电位 (MAP)标测技术测定 10例无器质性心脏病的阵发性室上性心动过速患者接受PES时的心室复极离散度。结果 :S1 S1 刺激 ( 5 0 0ms)时的动作电位时程 (APD)的离散度 (APDd)与窦性心律时无明显差异 ( 34± 10msvs38± 9ms ,P >0 .0 5 )。随S1 S2 间期缩短 ,各标测点S2 的APD逐渐缩短 ,且与S1 S2 间期呈正相关 ,但激动时间 (AT)及其离散度 (ATd)、APDd、复极时间离散度 (RTd)逐渐延长 ;S1 S2 间期缩短至有效不应期 (ERP) +30ms后 ,S2 的APDd、RTd大于窦性心律及S1 S1 刺激时 (APDd :5 1± 8msvs 38± 9ms或 34± 10ms,P <0 .0 5 ;RTd :39± 10msvs2 4± 7ms,P<0 .0 5 ) ,但ATd无明显增大。心室内各点有效不应期离散度为 31± 14ms,ERP APD平均为 0 .89± 0 .0 8。认为在无器质性心脏病者PES可使心室复极离散度增大 ,但不增加传导差异 ,不易诱发VTA     

慢性砷中毒大鼠肾脏蛋白激酶C-α表达的研究

目的 探讨蛋白激酶C(PKC)-α在慢性砷中毒大鼠肾脏的表达及作用.方法 将60只清洁级SD大鼠按体质量随机分为高砷(10.0 mg/kg)、低砷(0.4mg/kg)组和对照(蒸馏水)组,采用自由饮水方式进行染毒,每10天称体质量1次,调节给药量.连续染毒4个月,测血砷、尿砷.取大鼠肾脏用免疫组织化学SABC法,观察肾脏PKC-α阳性细胞并计数,采用Biomias图像分析软件测定其平均灰度值.结果 高砷组和低砷组的SD大鼠肾脏近端小管PKC-α阳性细胞计数[(3.62±1.90)、(10.07±3.22)个/视野]、肾小球PKC-α阳性细胞计数[(3.62±1.90)、(10.07±3.22)个/视野]均低于对照组[(60.00±9.63)、(18.57±2.71)个/视野,P均＜0.05),高砷组和低砷组的大鼠尿砷[(7366.62±1086.50)、(1744.31±300.12)μg/L]、血砷[(31.59±9.24)、(16.58±2.08)μg/L]均高于对照组[(18.97±3.58)、(18.97±3.58)μg/L,P均＜0.05].高砷组和低砷组的SD大鼠肾脏近端小管、肾小球PKC-α阳性细胞平均灰度值(142.79±11.16、122.15±5.91)均高于对照组(114.33±6.70,P均＜0.05).结论 砷可使SD大鼠肾脏PKC-α阳性细胞表达减少,PKC-α在慢性砷中毒大鼠肾脏抑制细胞凋亡的调控作用被减弱.     

Three layer functional model and energy exchange concept of aging process

Relying on a certain degree of abstraction, we can propose that no particular distinction exists between animate or living matter and inanimate matter. While focusing attention on some specifics, the dividing line between the two can be drawn. The most apparent distinction is in the level of structural and functional organization with the dissimilar streams of ‘energy flow’ between the observed entity and the surrounding environment. In essence, living matter is created from inanimate matter which is organized to contain internal intense energy processes and maintain lower intensity energy exchange processes with the environment. Taking internal and external energy processes into account, we contend in this paper that living matter can be referred to as matter of dissipative structure, with this structure assumed to be a common quality of all living creatures and living matter in general. Interruption of internal energy conversion processes and terminating the controlled energy exchange with the environment leads to degeneration of dissipative structure and reduction of the same to inanimate matter, (gas, liquid and/or solid inanimate substances), and ultimately what can be called ‘death.’ This concept of what we call dissipative nature can be extended from living organisms to social groups of animals, to mankind. An analogy based on the organization of matter provides a basis for a functional model of living entities. The models relies on the parallels among the three central structures of any cell (nucleus, cytoplasm and outer membrane) and the human body (central organs, body fluids along with the connective tissues, and external skin integument). This three-part structural organization may be observed almost universally in nature. It can be observed from the atomic structure to the planetary and intergalactic organizations. This similarity is corroborated by the membrane theory applied to living organisms. According to the energy nature of living matter and the proposed functional model, the decreased integrity of a human body's external envelope membrane is a first cause of the structural degradation and aging of the entire organism. The aging process than progresses externally to internally, as in single cell organisms, suggesting that much of the efforts towards the restoration and maintenance of the mechanisms responsible for structural development should be focused accordingly, on the membrane, i.e., the skin. Numerous reports indicate that all parts of the human body, like: bones, blood with blood vessels, muscles, skin, and so on, have some ability for restoration. Therefore, actual revival of not only aging tissue of the human body's membrane, but the entire human body enclosed within, with all internal organs, might be expected. We assess several aging theories within the context of our model and provide suggestions on how to activate the body's own anti-aging mechanisms and increase longevity. This paper presents some analogies and some distinctions that exist between the living dissipative structure matter and inanimate matter, discusses the aging process and proposes certain aging reversal solutions.     

Unusual responses of nocturnal pineal melatonin synthesis and secretion to swimming: Attempts to define mechanisms

Abstract: The effect of swimming at night on rat pineal melatonin synthesis was compared with that of light exposure at night. Rats were forced to swim at 0030 hr (lights out at 2000 hr) and sacrificed by decapitation 15 and 30 min later, immediately after swimming. Other groups of animals were exposed to white light (650μW/cm²) for 15 and 30 min at same time. Swimming caused a rapid and highly significant drop in the melatonin content in the pineal gland; however, the activity of N-acetyltransferase (NAT), the supposed rate limiting enzyme in the melatonin production, was not changed. Despite the drop in pineal melatonin levels, serum concentrations of the indole remained elevated in the rats that swam. In contrast, melatonin levels in the pineal and serum of light exposed rats fell precipitously, accompanied by a significant suppression of NAT activity. Since we anticipated that the strenuous exercise associated with swimming may induce release of artrial natriuretic peptide (ANP) from the heart, which in turn could cause the release of pineal melatonin, in a second study we injected physiological saline intravenously to stretch the cardiac muscle and release ANP. Three milliliters of normal saline was injected during the day into the jugular vein of anesthetized rats that were pretreated with isoproterenol to stimulate pineal melatonin production. Animals were killed 15 min after the saline injection, and pineal NAT activity and pineal melatonin levels were measured. The saline injections caused no alteration in the elevated levels of either NAT or melatonin. These data suggest that the disparity in pineal NAT activity (which was high) and pineal melatonin (which was low), in animals swum at night, may not be caused by ANP which is released during strenuous exercise such as swimming.     

The immunoneuroendocrine role of melatonin

Abstract: A tight, physiological link between the pineal gland and the immune system is emerging from a series of experimental studies. This link might reflect the evolutionary connection between self-recognition and reproduction. Pinealectomy or other experimental methods which inhibit melatonin synthesis and secretion induce a state of immunodepression which is counteracted by melatonin. In general, melatonin seems to have an immunoenhancing effect that is particularly apparent in immunodepressive states. The negative effect of acute stress or immunosuppressive pharmacological treatments on various immune parameters are counteracted by melatonin. It seems important to note that one of the main targets of melatonin is the thymus, i.e., the central organ of the immune system. The clinical use of melatonin as an immunotherapeutic agent seems promising in primary and secondary immunodeficiencies as well as in cancer immunotherapy. The immunoenhancing action of melatonin seems to be mediated by T-helper cell-derived opioid peptides as well as by lymphokines and, perhaps, by pituitary hormones. Melatonin-induced-immuno-opioids (MHO) and lymphokines imply the presence of specific binding sites or melatonin receptors on cells of the immune system. On the other hand, lymphokines such as -γ-interferon and interleukin-2 as well as thymic hormones can modulate the synthesis of melatonin in the pineal gland. The pineal gland might thus be viewed as the crux of a sophisticated immunoneuroendocrine network which functions as an unconscious, diffuse sensory organ.     

Melatonin and photoperiodic time measurement: Seasonal breeding in the sheep

Abstract: Well-established circadian physiology supports the view that photoperiodic time measurement utilizes the coincidence between the presence of light and a photosensitive phase of a 'biological clock' to alter reproductive status—the so-called external coincidence model of seasonal breeding. In this review, we examine the mechanism whereby photoperiod interacts with presumed suprachiasmatic nuclei activity to allow endogenous melatonin to normally synchronize reproductive activity to the optimal time of year. The Romney Marsh sheep is particularly explored as an experimental model. It is suggested that the on/off activity of seasonal reproduction may be a robust mechanism able to be predictably manipulated by the judicious use of the light/dark cycle and exogenous melatonin, but firmly based on circadian principles.     

Response of rat pineal melatonin to calcium, magnesium, and lithium is circadian stage dependent

Abstract: Herein we documented the response of pineal melatonin production to electrolytes known to be effective on pineal function in view of a possible circadian stage dependence. We studied the release of melatonin by perifused rat pineal glands at 2 different circadian stages corresponding to the middle of the light and dark periods, i.e., respectively, 7 and 19 HALO (Hours After Light Onset, L:D = 12:12). The initial efflux rates were, as expected, much higher in the perifusates of glands removed from rats sacrificed during the dark phase than of those removed during the light phase. After 3 hr of perifusion, melatonin release reached similar levels which were found constant up to the 8th hr of perifusion, whatever the circadian stage. Perifusion of the glands with physiological concentrations for the rat of calcium (5.2 mmol/1) and magnesium (1.34 mmol/1) resulted in a stimulatory effect on the pineal glands removed from rats sacrificed in the middle of the dark period (19 HALO), whereas no effects were observed on the pineal glands removed from rats sacrificed during the light (7 HALO). Lithium (0.28 and 0.55 mmol/1) was ineffective on melatonin release in pineal glands removed 7 and 19 HALO. Our results show differences in the initial efflux rates of melatonin and in the response of perifused pineal glands to calcium and magnesium according to the circadian stage.     

Conservative management of perforated duodenal diverticulum： A case report and review of the literature

Duodenal diverticula are a relatively common condition. They are asymptomatic, unless they become complicated, with perforation being the rarest but most severe complication. Surgical treatment is the most frequently performed approach. We report the case of a patient with a perforated duodenal diverticulum, which was diagnosed early and treated conservatively with antibiotics and percutaneous drainage of secondary retroperitoneal abscesses. We suggest this method could be an acceptable option for the management of similar cases, provided that the patient is in good general condition and without septic signs.     

Changes in connexin43, the gap junction protein of astrocytes, during development of the rat pineal gland

Abstract: The abundance of gap junctions between rat pineal astrocytes formed by connexin43 (Cx43) was studied during development. Levels and distribution of Cx43 were measured by immunoblotting and indirect immunofluorescence, respectively. The amount of Cx43 in cells located within the gland was low until about the 7th postnatal day and increased to adult values between the 14th and 21st days postpartum. Although astrocytes, recognized by their vimentin immunoreactivity, were scarce before birth, they were abundant by the 7th postnatal day suggesting that the low levels of Cx43 found at this age corresponded to a low expression of this protein. Localization of the immunoreactivity to Cx43 and vimentin showed a close correlation, indicating that mature or immature pineal astrocytes form gap junctions made of Cx43. Since Cx43 levels attained their adult values at about the time the innervation and the functional state of the gland reached maturity (2–3 weeks after birth), it is proposed that astrocyte gap junctions are involved in the function of the adult rat pineal gland.