Sickled erythrocytes, hyphema, and secondary glaucoma: V. The effect of vitamin C on erythrocyte sickling in aqueous humor.

In vivo incubations of Hgb SC erythrocytes showed significantly more sickling in anterior chambers characterized by high concentrations of ascorbic acid than in anterior chambers with low concentrations of ascorbic acid (normal guinea pigs compared with scorbutic guinea pigs and normal guinea pigs compared with normal rats). Low concentrations of ascorbic acid, however, did not completely eliminate intracameral sickling. Because acetazolamide raises the concentration of aqueous humor ascorbate, it should be used with considerable discretion when treating hyphema and secondary glaucoma caused by sickle cells. Methazolamide may be more desirable.     

Sickled erythrocytes, hyphema, and secondary glaucoma: VI. The relationship between intracameral blood cells and aqueous humor pH, PO2, and PCO2.

Injection of Hgb SC blood into rabbit anterior chambers resulted in lowering of aqueous humor pH and PO2 and elevation of aqueous humor PCO2. These effects appear to contribute to the sickling of erythrocytes that occurs in aqueous humor.     

Sickled erythrocytes, hyphema, and secondary glaucoma: II. Injected sickle cell erythrocytes into human, monkey, and guinea pig anterior chambers: the induction of sickling and secondary glaucoma.

Injection of sickle cell erythrocytes (SS, SC, Sthal, and AS) into the anterior chambers of living human, monkey, and guinea pig eyes resulted in conversion of erythrocytes to the sickled configuration. Immune responses did not appear to play an important role in influencing this phenomenon. The number of cells sickled was directly related to the concentration of hemoglobin S. In human and monkey eyes, the severity of elevated IOP appeared to be related to the type of cells injected and their concentration of hemoglobin S. Even the ordinarily benign genotype of sickle cell trait demonstrated sickling in the anterior chamber and elevation of the IOP.     

Sickled erythrocytes, hyphema, and secondary glaucoma: I. The diagnosis and treatment of sickled erythrocytes in human hyphemas.

Four patients with sickle cell hemoglobinopathies (one SC, three AS) and hyphemas were found to have more erythrocytes sickled in their anterior chambers than in their circulating venous blood. Intraocular pressure was severely elevated, despite relatively small amounts of intracameral blood. Systemic hypotensive agents were not always successful in reducing IOP, and in patients with sickle cell hemoglobinopathy, are probably contraindicated in high or repeated dose regimens. Moderate elevation of IOP in sickle cell hemoglobinopathy patients may produce rapid deterioration of visual function, perhaps because of a greater than usual effect on vascular perfusion in the central retinal artery and optic nerve. Early anterior chamber paracentesis may be the best treatment for this type of hyphema-induced secondary glaucoma.     

Sickled erythrocytes, hyphema, and secondary glaucoma: III. Effects of sicle cell and normal human blood samples in rabbit anterior chambers.

When injected into rabbit anterior chambers, human sickle cell erythrocytes cause more intense and prolonged effects than do nonsickling erythrocytes. The consequences of injected sickle cell trait erythrocytes are not less severe than those of injected SC, SS, and Sthal erythrocytes. Regardless of hemoglobin composition, blood with a higher hematocrit value causes more severe complications than blood with a lower hematocrit value.     

Effect of bilirubin on rabbit cerebral arteries in vivo and in vitro.

The effect of bilirubin on vasoreactivity was examined in the exposed rabbit basilar artery (diameter, 1045 +/- 17 microns; n = 18) and its cortical branches (diameter, 265 +/- 11 microns; n = 43) in vivo. Vasoconstriction induced by uridine triphosphate (UTP; 10(-5) to 10(-3) mol/L) was observed in vivo before and after a 60-minute application of supersaturated bilirubin (10(-4) mol/L). Bilirubin was dissolved in modified artificial cerebrospinal fluid (pH 7.4) or in physiological salt solution (pH 7.6). The latter was spectrophotometrically estimated to contain a higher concentration of free bilirubin because of the formation of less colloid. After treatment with bilirubin in artificial cerebrospinal fluid, the effect was minimal in the basilar arteries (n = 7), whereas the diameter of the branches was reduced by 9.6 +/- 1.5% (n = 23) and UTP-induced vasoconstriction was potentiated. After application of bilirubin in physiological salt solution, the basilar arteries contracted slightly (-2.1 +/- 0.9%; n = 6) and the UTP-induced vasoconstriction in the branches was attenuated (n = 12). After a 60-minute incubation of basilar artery with bilirubin in physiological salt solution in vitro, isometric tension recordings showed a diminution in KCl- and UTP-induced vasoconstrictions. Acetylcholine- and sodium nitroprusside-induced relaxations were also attenuated. It is suggested that bilirubin may exert different effects depending on the size of arteries and the concentration of free bilirubin. The constrictor and potentiating effects of bilirubin could be caused by the impairment of the relaxation mechanism. When the toxic effect of bilirubin becomes severe, the constrictor mechanism is also damaged.     

The quality of washed autotransfused erythrocytes. The elimination of plasma hemoglobin, osmotic fragility and survival rate of retransfused erythrocytes

Intraoperative transfusion has until recently been understood to mean full retransfusion of the blood removed by a suction pump without significant changes due to external influences, which considerably limited its utilization. Intraoperative transfusion can only be performed without decisive disadvantages when the blood can be suctionally removed in large amounts and immediately retransfused. In recent years, the Cell Saver has provided a system which can also prepare soiled blood for retransfusion. Extensive orthopedic surgery entails large blood losses due to oozing from expanded wound areas; only rarely does acute bleeding occur. Because of intensive tissue contact, the suctioned blood has been soiled with activated clotting factors, lytic enzymes, free haemoglobin from damaged red cells, cleaning solutions, and other undesired elements. With the Cell Saver system, it is possible to remove the plasma and recover 70-80% of the intact red cells sufficiently freed from stroma and free haemoglobin. The osmotic fragility of these cells served as a measure of integrity and membrane stability. They were compared to red cells withdrawn preoperatively and showed an identical osmotic relationship. Determining the survival rate of the retransfused cells in vivo shows that they provide a high-quality and in most cases, a sufficient replacement of blood loss. Even after 6 days, over 70% were found in the circulating blood. Premature, disproportionate elimination, which could be dangerous for the patient, does not occur.     

The effect of silicon nitride ceramic on rabbit skeletal cells and tissue. An in vitro and in vivo investigation

This article presents a morphologic assessment of the effect of silicon nitride ceramic (Si3N4) on rabbit marrow stromal cells and their differentiation when grown in vitro and in vivo. In vitro marrow stromal cells (MSC) attached initially to upper portions of ceramic discs. However, at four weeks, cells only attached to disc edges. Fresh marrow or first passage MSC, inoculated into diffusion chambers with and without Si3N4, formed cartilage, bone, and fibrous tissue after being implanted intraperitoneally for five weeks. Tissue differentiated adjacent to Si3N4 but not within the pores. In contrast, Si3N4 implants inserted into femoral marrow cavities were surrounded initially by woven bone and within three months by mature bone that had permeated implants with a pore size of 255 +/- 64 microns. Plugs having a pore diameter of 170 +/- 45 microns mainly contained vascularized fibrous tissue with occasional foci of osteoid or bone in the peripheral pores. In a pilot experiment, three femoral segmental Si3N4 endoprostheses were implanted in three adult rabbits, and the osseous reactions were monitored during their natural life. Each implant was enclosed by a stable cuff of bone within four months of implantation and remained unchanged during the rest of the animal's life. Autopsies confirmed these roentgenographic observations, and tissue appositional to each prosthesis was morphologically normal. Si3N4 has the potential of an important ceramic for use in osseous reconstruction.     

Trabecular outflow facility and formation rate of aqueous humor during anesthesia with sevoflurane-nitrous oxide or sevoflurane-remifentanil in rabbits

In the present study, we examined the effect of sevoflurane and remifentanil on intraocular pressure (IOP) and fluid dynamics. Twenty-eight rabbits were anesthetized with halothane, and IOP was measured via a 25-gauge needle in the anterior chamber. Rabbits were then assigned to one of four groups, and halothane was replaced with sevoflurane 1% (n = 7), 2% (n = 7), 3% (n = 7), or 1% + remifentanil 0.65 microg kg(-1) x min(-1) i.v. (n = 7). In all groups, a series of intraocular infusions was made into the anterior chamber, and IOP, trabecular outflow facility, the rate of aqueous humor formation, and intraocular compliance were determined. With sevoflurane only, intraocular compliance decreased (55 +/- 14, 39 +/- 22, 31 +/- 17 nL/mm Hg; P < 0.05) as the concentration of sevoflurane increased. With sevoflurane 1% + remifentanil, intraocular compliance was significantly increased (100.1 +/- 30.5 nL/mm Hg; P < 0.05) compared with sevoflurane 1%, 2%, or 3%. Trabecular outflow facility, rate of aqueous humor formation, and IOP did not differ among groups, and IOP was similar to values obtained during halothane anesthesia. Implications: The dose-related effects of sevoflurane on intraocular compliance did not produce significant intraocular pressure differences. Adding remifentanil to sevoflurane increased intraocular compliance. Sevoflurane or sevoflurane + remifentanil causes a decrease in intraocular pressure compared with the average of previously reported values in awake rabbits, and the magnitude of the decrease is similar to that previously reported in rabbits anesthetized with ethyl urethane, pentobarbital, or halothane alone or in combination with propofol, cocaine, or lidocaine.     

In vitro and in vivo analysis of the inability of fetal rabbit wounds to contract.

Fetal rabbit wounds that are sutured show excellent repair without obvious scarring. In contrast, an unsutured wound in a rabbit fetus does not close, and it appears that the process of wound contraction does not occur. Experiments were carried out to illustrate the mechanisms responsible for the noncontraction of open fetal rabbit wounds. Results showed that the lack of wound contraction was not an artifact caused by rapid fetal growth. With regard to the ability of cultured fetal fibroblasts to show cytoplasmic muscle-induced cell contraction, we found that, in cultured fetal fibroblasts, cell contraction was induced by adenosine triphosphate. Contractile abilities of fetal-derived fibroblasts were equivalent to those of adult-derived fibroblasts. The fetal fibroblasts also demonstrated the generation of superior contractile activity when examined in a fibroblast-populated collagen lattice model. Finally, the ability of amniotic fluid to alter wound contraction was addressed by means of the fibroblast-populated collagen lattice in vitro model. Increasing concentrations of amniotic fluid inhibited fetal fibroblast lattice contraction. Therefore, rabbit amniotic fluid contains an inhibitor that may be partially responsible for the noncontraction of fetal rabbit wounds in utero.     

Longitudinal in vivo and in vitro time-course study of chronic cerebrovasospasm in the rabbit basilar artery

Subarachnoid hemorrhage (SAH) was induced by multiple injections of autologous blood into the prepontine cistern in the rabbit. Long-lasting angiographic narrowing was recorded over a period of nine days after SAH. Papaverine (PPV) reversed angiographic narrowing in the first three days after SAH. Vasospasm was refractory to PPV from day five to day nine after SAH. PPV —refractoriness (in vivo) was positively correlated with decreased vessel wall distensibility (in vitro). Arterial segments showed spontaneous increases in tone in the first two days after SAH. Other alterations observed include a marked gradual reduction in the capacity of the vessel wall to contract, reduction in constrictor nerve influences on vascular tone, and impaired acetylcholine — induced vasorelaxation. Tonic contraction to the maximum dose of serotonin was increased in acute spasm and decreased in chronic spasm. It is suggested that the initial cause of arterial narrowing after SAH is the action of vasoactive substances released in the close vicinity of the arterial wall; this then leads to abnormal tone, tissue damage, and structural changes.     

The effects of glaucoma medications on Tenon's capsule and conjunctiva in the rabbit

Glaucoma filtering surgery fails most frequently due to fibrosis at the episcleral-conjunctival/Tenon's capsule interface. Sherwood et al have suggested that chronic topical antiglaucoma medications increase conjunctival inflammatory cells, which could increase the likelihood of fibrosis and subsequent bleb failure. In a pilot study in a rabbit model, we placed timolol, pilocarpine, and epinephrine, or a combination of all three, in one eye of 24 animals twice daily for 7 months. The fellow eye received distilled water. Microscopic examination revealed no statistically significant change in the number of acute or chronic inflammatory cells, fibroblasts, or goblet cells in the treated as compared with the control eyes. A longer duration of drug administration, or drug administration followed by surgical intervention, may be required to produce an effect on the conjunctiva and Tenon's capsule, if such an effect exists.     

The comparative effects of the argon, Nd: YAG, and argon-pumped dye lasers on human platelets and erythrocytes in vitro

The effects of three lasers, Argon, Nd:YAG, and Argon-pumped Dye, on three types of platelet preparations were evaluated. Either EDTA or buffered citrate served as anticoagulants. Platelets separated from plasma and suspended in buffer showed no decrease in counts following lasering, but morphologic damage was evident with transmission electron microscopy (TEM). In platelet-rich plasma, a fall in counts was noted for the Argon and the YAG (at high energy only) but was absent when the Dye laser was employed. Morphologic damage (TEM), however, was noted with all three lasers. When whole blood preparations were used, more marked changes in both RBCs and platelets were seen in samples collected in EDTA compared with citrated samples. Morphologic damage (TEM) to platelets and RBCs occurred with all three lasers. An artifactual increase in "platelet counts," the appearance of spherocytes, and an increase in plasma Hb indicated RBC injury. Both platelets and erythrocytes were sensitive to variations in power (wattage) despite constant total energy delivery.     

The effects of 5HT(1) agonists on erection in rats in vivo and rabbit corpus cavernosum in vitro

We have examined the effects of the selective 5-HT(1a) and 5-HT(1b) agonists 8-hydroxy-2-(di-n-propylamino)tetralin (8-OHDPAT) and 7-trifluoromethyl-4-(4-methyl-1-piperazinyl)-pyrrolo[1,2-a]quinoxaline (CGS12066b), respectively on erection in rats in vivo and rabbit corpus cavernosum in vitro. Apomorphine (0.1 mg/kg) induced 3.1+/-0.4 erections in vehicle-pretreated animals. At the highest doses tested 8-OHDPAT (0.4-0.64 mg/kg) and CGS12066b (1.0-10.0 mg/kg) significantly reduced apomorphine erection to 0.9+/-0.3 erections and 0.5+/-0.2 erections respectively. The nonselective 5-HT agonist metachlorophenylpiperazine (m-CPP; 0.1 mg/kg) elicited characteristic increases in cavernous nerve activity (CNA) and intracavernous pressure responses (ICP) in anesthetized rats. 8-OHDPAT (0.64 mg/kg) and CGS12066b (1.0 mg/kg) failed to elicit CNA or ICP responses. CGS12066b reduced ICP responses resulting from the direct stimulation of the cavernous nerve whereas 8-OHDPAT did not. CGS12066b reduced the CNA and ICP responses to m-CPP administration whereas 8-OHDPAT potentiated m-CPP induced CNA and ICP responses. In isolated rabbit corpus cavernosum (CC) 8-OHDPAT and CGS12066b both failed to alter noradrenergic induced contraction and non-adrenergic non-cholinergic relaxation. Our results indicate that selective 5-HT(1a) and 5-HT(1b) agonists have different effects in different models of erection.     

Drug-induced vasodilation: In vitro and in vivo study on the effects of lidocaine and papaverine on rabbit carotid artery

Flap ischemia is often encountered during pedicled and free tissue transfer. In this study, the vascular effects of varying doses of lidocaine, papaverine, and a combination of the two agents were evaluated and compared in an in vitro and in vivo model in the rabbit carotid artery. In the in vitro study, 14 rings from the rabbit carotid artery were bathed in Krebs-Ringers solution and stretched progressively to an optimal tension of 3.7–4.2 grams. Their isometric contractile activity was measured. The specimens were precontracted with norepinephrine (1 μM), and a dose response curve was established by adding cumulatively either lidocaine (to 7 arterial rings) or papaverine (to 7 arterial rings) at increasing concentrations. In the in vivo study, microvascular anastomoses were performed bilaterally in the rabbit carotid artery in 30 animals using 9–0 nylon suture and standard microsurgical techniques. In each animal, one side was treated with heparinized sodium chloride and served as the control. The other side was treated blindly, during and after the anastomoses, with a topical application of 1 ml of either lidocaine 2% (n = 5), lidocaine 20% (n = 5), papaverine (30 mg/ml, n = 5), lidocaine 2% combined with papaverine (30 mg/ml, n = 5), or lidocaine 20% combined with papaverine (30 mg/ml, n = 5). For 30–60 minutes after the procedure, blood flow changes in the vessels were continuously monitored with a transonic doppler applied to both carotid arteries. The 20% lidocaine group was flushed with saline at the end of the first hour and monitored for an additional 60 minutes. Papaverine elicited a concentration-dependent relaxation of norepinephrine precontracted carotid artery rings in vitro. Lidocaine elicited a biphasic response, with low concentrations (10⁻⁶–10⁻⁴ M) increasing the norepinephrine-induced contraction and high concentrations (10⁻⁴–10⁻² M) relieving this contraction. Microsurgical anastomosis produced a significant decrease of blood flow through the rabbit carotid artery as measured by the transonic doppler. Drug application did not alter the systemic blood pressure of the animals. Topical application of lidocaine 2% did not significantly change the blood flow after microvascular anastomosis. Topical application of lidocaine 20%, papaverine (30 mg/ml), or lidocaine (2% or 20%) combined with papaverine significantly increased the blood flow in the rabbit carotid artery. In the lidocaine 20% group, the blood flow remained significantly increased after the drug was flushed with heparinized saline solution. These results demonstrate that topical lidocaine 20%, papaverine, and lidocaine 2% or 20% combined with papaverine significantly increase blood flow in the rabbit carotid artery after microvascular anastomosis. The data confirm the use of papaverine and lidocaine 20%, alone or in combination, as spasmolytics during clinical microsurgery. This suggests that lidocaine 2% alone is not the ideal drug to relieve vascular constriction, and further studies on the clinical use of low concentrations of topical lidocaine in microsurgery is warranted. © 1998 Wiley-Liss, Inc. MICROSURGERY 18:90-96 1998     

降钙素在体内和体外实验中对兔关节炎关节软骨的保护作用

[目的]研究降钙素(calcitonin,CT)对骨性关节炎关节软骨的保护作用.[方法]32只6个月龄新西兰大白兔,雌雄各半,行右膝关节前交叉韧带切断术.术后1周将动物随机分为实验组和对照组.实验组皮下注射鲑鱼降钙素5 IU/(kg·d),连续6周;对照组则给予等剂量盐水.术后7周处死动物.取股骨内髁制成切片行HE、番红-固绿和MMP-3免疫组化染色.取膝关节软骨行胶原酶消化法提取软骨细胞进行体外培养,于第Ⅱ代融合90%后提取mRNA,采用实时荧光定量PCR方法检测MMP-3,aggrecan的表达.HE切片Mankin评分.番红-固绿和MMP-3免疫组化染色切片用图像分析仪测量平均灰度值.PCR结果记录Ct值.[结果]实验组关节软骨的组织学Mankin评分结果,番红-固绿和MMP-3免疫组化染色平均灰度值测量结果低于对照组(P＜0.05);实验组体外培养软骨细胞的MMP-3的RNA含量低于对照组(P＜0.05),aggrecan的RNA含量高于对照组(P＜0.05).[结论]降钙素5 IU/(kg·d)皮下注射能够增加体外培养软骨细胞分泌的aggrecan的含量以及下调MMP-3的表达;可能通过体内明显减轻兔膝关节软骨基质的降解,减少MMP-3的表达而保护软骨.