Short- and Long-Term Effects on the Ciliary Body and the Aqueous Outflow Pathways of High-Intensity Focused Ultrasound Cyclocoagulation

Several physical methods can be used to coagulate the ciliary body and decrease intra-ocular pressure in patients with glaucoma. The study described here investigated the short- and long-term effects of high-intensity focused ultrasound (HIFU) cyclocoagulation on the aqueous humor production structures and outflow pathways. Thirty-four rabbit eyes were sonicated with a ring-shaped probe containing six miniaturized HIFU transducers. Light, scanning electron and transmission electron microscopy and corrosion casts were performed. In the affected regions, the epithelium of the ciliary processes was degenerated or necrotic and sloughed off. Examinations performed several months afterward revealed involution of the ciliary processes. Vascular corrosion cast revealed focal interruption of the ciliary body microvasculature. In most animals, a sustained fluid space was seen between the sclera, the ciliary body and the choroid, likely indicating an increase in the aqueous outflow by the uveoscleral pathway. These results suggest that HIFU cyclocoagulation has a dual effect on aqueous humor dynamics.     

Ergonovine maleate provocative test for coronary arterial spasm

Ergonovine maleate was evaluated as a provocative agent for inducing coronary spasm during coronary arteriography. The study group consisted of 98 patients with either mild fixed obstructions of coronary luminal diameter (less than 50 percent) or normal coronary arteriograms. The test was considered positive if the drug precipitated severe coronary spasm. A positive ergonovine test occurred in 10 of 11 patients with Prinzmetal's variant angina (P < 0.02). Two of these patients had a transmural myocardial infarction in the distribution of the spastic artery. Ergonovine tests were negative in (1) the 15 control patients with no clinically suspected coronary artery disease (P < 0.001), (2) 63 of 66 patients with angina-like chest pain (P < 0.001), and (3) all 6 patients with myocardial infarction and no history of Prinzmetal's variant angina (P < 0.05). No major complications occurred as a result of this test.Thus, ergonovine maleate test is a safe, sensitive and specific method for reproducing coronary spasm in patients with Prinzmetal's variant angina and no major coronary obstructions. The results suggest that coronary spasm can be implicated as a cause of myocardial infarction in patients with normal coronary arteriograms who also have Prinzmetal's variant angina. Coronary spasm was not demonstrated in patients who had normal coronary arteriograms and a history of myocardial infarction as an isolated clinical event. Also, coronary spasm could not be demonstrated in the majority of patients who had angina-like chest pain and no major coronary obstruction.     

Dialysis Access Graft Thrombolysis: Randomized Study of Pulse-Spray Versus Continuous Urokinase Infusion

Purpose: To compare pulse-spray to continuous-infusion thrombolysis with high-dose urokinase in thrombosed dialysis access grafts. Methods: A prospective randomized controlled trial was performed. From August 1992 to September 1993, 30 thrombosed polytetrafluoroethylene (PTFE) grafts in 24 patients were included, 15 grafts in each group. The success of thrombolysis, mean time to thrombolysis, mean urokinase dose, and 60-day patency rate were evaluated. Results: In the pulse-spray group, the mean time to thrombolysis was 72 min with a mean urokinase dose of 560,000 U. The 60-day patency rate was 71%. In the continuous-infusion group, the mean infusion time to thrombolysis was 55 min with a mean dose of 479,000 U. The 60-day patency rate was 73%. Conclusion: No statistically significant difference was found between the two techniques in the mean time to thrombolysis, the mean urokinase dose used, or the 60-day patency rate.     

Rubral lateropulsion due to vertebral artery dissection in a patient with Klippel-Feil syndrome

BACKGROUND: Neurologic deficits in patients with Klippel-Feil syndrome usually are attributed to direct compression of neuronal structures or hypoperfusion secondary to compression of the vertebral arteries by bony abnormalities. OBJECTIVE: To describe a 38-year-old woman with known Klippel-Feil syndrome who developed lateropulsion. RESULTS: The results of magnetic resonance imaging were consistent with rubrothalamic stroke. The cerebral angiogram confirmed vertebral artery dissection at the level of her previously observed bony abnormality. CONCLUSIONS: Hypermobility adjacent to fused vertebrae subjects the vertebral artery to increased shear forces. Thus, Klippel-Feil syndrome may be a predisposing factor for vertebral artery dissection. Moreover, to our knowledge, this case represents the second known case of rubral lateropulsion.     

Does the tissue engineering architecture of poly(3-hydroxybutyrate) scaffold affects cell-material interactions?

A critical element in tissue engineering involves the fabrication of a three-dimensional scaffold. The scaffold provides a space for new tissue formation, supports cellular ingrowth, and proliferation and mimics many roles of the extracellular matrix. Poly(3-hydroxybutyrate) (PHB) is the most thoroughly investigated member of the polyhydroxyalkanoates (PHAs) family that has various degrees of biocompatibility and biodegradability for tissue engineering applications. In this study, we fabricated PHB scaffolds by utilizing electrospinning and salt-leaching procedures. The behavior of monkey epithelial kidney cells (Vero) and mouse mesenchymal stem cells (mMSCs) on these scaffolds was compared by the MTS assay and scanning electron microscopy. Additionally, this study investigated the mechanical and physical properties of these scaffolds by measuring tensile strength and modulus, dynamic contact angle and porosity. According to our results, the salt-leached scaffolds showed more wettability and permeability, but inferior mechanical properties when compared with nanofibrous scaffolds. In terms of cell response, salt-leached scaffolds showed enhanced Vero cell proliferation, whereas both scaffolds responded similarly in the case of mMSCs proliferation. In brief, nanofibrous scaffolds can be a better substrate for cell attachment and morphology.     

Use of aminoguanidine, a selective inducible nitric oxide synthase inhibitor, to evaluate the role of nitric oxide in periapical inflammation

The purpose of this study was to evaluate the effects of aminoguanidine (AG) as a selective inhibitor of inducible nitric oxide synthase (iNOS) on the degree of inflammatory response in periapical lesions in the canine teeth of cats. Root canals from 52 cat canine teeth were exposed to the oral cavity and sealed after 7 days. One day before pulp exposure, cats were administered either AG (experimental group) or normal saline (control group), which was continued on a daily basis until the day of sacrifice. Animals were sacrificed at 28 days after pulp exposure. Inflammatory response in the periapical zones was analyzed histologically. The degree of periapical inflammation in the AG group was significantly lower than that in the control group (P < 0.05). Selective iNOS inhibitors such as AG thus reduce the intensity of inflammatory responses in periapical lesions.     

Vagal stimulation promotes atrial electrical remodeling induced by rapid atrial pacing in dogs: evidence of a noncholinergic effect

Background: Atrial electrical remodeling (AER) is one of the mechanisms by which atrial fibrillation (AF) begets AF. It is known that vagal activity increases the propensity for AF. However, vagal effects on AER have not been fully investigated. Methods: Adult mongrel dogs were divided in four groups: group I, rapid atria pacing (RAP); group II, RAP plus vagal nerve stimulation (VNS); group III, RAP and VNS with atropine (0.2 mg/kg/h, intravenous), and group IV, group III plus vasoactive intestinal polypeptide (VIP) antagonist ([D‐p‐Cl‐Phe⁶, Leu¹⁷]‐VIP, 0.125 μg/kg/h). VNS was performed bilaterally through vagosympathetic trunks to achieve second‐degree AV block or sinus rate slowing of >30 beats per minute. Atrial effective refractory periods (AERPs) were determined in the coronary sinus and right atrial appendage every hour at drive cycle lengths (DCLs) 350 ms, 300 ms, and 250 ms. Results: During 5 hours RAP with or without VNS, AERP shortened progressively from baseline at both pacing sites and at all DCLs (P < 0.01). Furthermore, RAP‐induced AERP shortening was more pronounced with VNS (P < 0.01). With atropine, the AERP shortening during VNS was blunted (P < 0.01), but was still significantly more pronounced than that in group I (P < 0.05). However, VNS effect on AERP shortening was eliminated completely with the combination of atropine and VIP antagonist (P = 0.15 vs group I). Conclusion: Increased vagal activity promotes RAP‐induced AER, which could not be totally accounted for by cholinergic effect but could be blocked by the combination of atropine and VIP antagonist. Vagally released VIP may have important role in the vagal promotion of AER. (PACE 2011; 34:1092–1099)