Inotropic response of the salvaged myocardium after acute coronary occlusion

We determined the response of the reperfused myocardium to inotropic stimulation with dobutamine hydrochloride. The middle part of the left anterior descending coronary artery (LAD) was occluded in 15 greyhounds for 3 hours. Group 1 (N = 8) was reperfused for 3 hours in the beating, working heart. Group 2 (N = 7) was put on cardiopulmonary bypass (CPB) for 1 hour, received 500 ml of potassium cardioplegia in the aortic root and in the area of ischemia through an internal mammary-LAD graft, and the LAD was reperfused off CPB for 3 hours. After 3 hours of reperfusion, dobutamine was given at 10 micrograms/kg/min for 20 minutes. Regional myocardial function was determined with subendocardial ultrasonic crystals in the area of ischemia and in the base of the heart; segmental contractility was determined from the ratio of peak left ventricular pressure to end-systolic segment length; and global contractility was determined by the slope of the ventricular pressure wave at a developed pressure of 40 mm Hg. Measurements were made prior to LAD occlusion (control), at the end of 3 hours of reperfusion (6 hours from the beginning of occlusion), and after 20 minutes of dobutamine infusion. Dobutamine infusion improved segmental function in all animals compared with 3 hours of reperfusion. The study shows that the reperfused myocardium responds favorably to inotropic stimulation after 3 hours of occlusion and 3 hours of reperfusion, and that the contractile response both to reperfusion and to inotropic stimulation is greatly affected by the method of reperfusion.     

Comparison of transferrin receptor-mediated endocytosis and drug- induced endocytosis in human neonatal and adult RBCs

Neonatal RBCs can undergo receptor-mediated endocytosis; normal adult RBCs cannot. Previously, we showed that drug-induced endocytosis, which can occur in adult RBCs exposed to amphipathic cations like primaquine, is greatly enhanced in all density-defined fractions of neonatal RBCs. To investigate the similarities and differences between receptor- mediated endocytosis and drug-induced endocytosis, we characterized transferrin receptor-mediated endocytosis in neonatal RBCs and compared it with drug-induced endocytosis. Primaquine drug-induced endocytosis is dependent on RBC ATP levels, is invariably preceded by stomatocytosis, and is inhibited by vanadate. In contrast, receptor- mediated endocytosis of transferrin is not preceded by stomatocytosis, is not nearly so dependent on ATP levels as is drug-induced endocytosis, and is not inhibited by vanadate. Furthermore, receptor- mediated endocytosis is quantitatively blocked by preincubation of neonatal RBCs with sodium cyanide, whereas cyanide does not inhibit drug-induced endocytosis in either adult or neonatal RBCs. Morphologic observation of the neonatal RBCs established the fact that only puckered RBCs that exhibited brilliant cresyl blue staining reticulum were capable of undergoing receptor-mediated endocytosis of transferrin. These characteristics identify them as motile R-1 reticulocytes. Reticulocytes in normal adult RBCs were incapable of exhibiting this phenomenon. Thus, receptor-mediated endocytosis, a property of motile reticulocytes in neonatal RBCs, differs from drug- induced endocytosis in its energy requirements, response to inhibitors, and morphologic concomitants.     

HPLC-MAXPLOT UV检测法测定血清中丹那唑及其代谢产物

本文建立了同时测定人体血清中丹那唑(Ⅰ)及其主要代谢产物2-羟甲基妊娠素(Ⅱ)和其它代谢产物妊娠素(Ⅲ)的高效液相色谱法。方法用YWG C18柱并以甲醇—水(74:26)作为流动相,应用紫外最大吸收作图法(maxplot)检测技术,以UV 285,240nm分别测定Ⅰ,Ⅱ和Ⅲ。使原型药和代谢产物都达到较高检测灵敏度。同时对方法的专一性、准确性和精密度等方面进行了评价,并应用于临床监测。     

Depth of intraspinal wire penetration during passage of sublaminar wires

A major concern with the use of sublaminar wires for segmental spinal instrumentation is the risk of neurologic compromise associated with repeated passage of wires through the epidural space. Because of the inability to visualize the wire tip during its sublaminar passage, the surgeon is unable to appreciate the depth of wire penetration (DOWP). The purpose of this investigation was to determine, through direct measurement, the depth of intraspinal penetration during the passage of sublaminar wires. Using their model, the authors have been able to define the optimal parameters for safe wire passage. Careful attention to maintaining contact between the wire tip and the under-surface of the lamina, using a wire of optimal configuration, will result in minimal DOWP and reduce the possibility of neurologic compromise.     

Use of synthetic oligonucleotides in the characterization of antithrombin III Northwick Park (393 CGT----TGT) and antithrombin III Glasgow (393 CGT----CAT)

Antithrombin III (ATIII) Northwick Park is caused by a single amino acid substitution, Arg 393---Cys and antithrombin III Glasgow is caused by Arg 393----His. Examination of the genetic code and the sequence of normal antithrombin III revealed that these amino acid substitutions could arise from the substitution of either two nucleotides or a single nucleotide at codon 393 of the antithrombin III gene. In two families, detection of the ATIII variants by genetic linkage analysis was not possible owing to lack of informative RFLP markers. Consequently, we synthesized two 22-base-long oligonucleotides specific for the single- base substitutions in the region of codon 393 and demonstrated by oligonucleotide hybridization that the molecular defect of ATIII Northwick Park is caused by the CGT----TGT mutation at codon 393 and that ATIII Glasgow is caused by the CGT----CAT mutation at codon 393. These oligonucleotide probes should prove useful as an alternative method for early detection of the ATIII variants.     

Power spectral analysis and cortical coupling of EEG for young and old normal adults

Power spectral analysis and cortical coupling were computed on eyes closed EEG recorded from 80 normal volunteers: 20 females and 20 males aged 25-35 years and 20 females and 20 males aged 55-70 years. Recordings were from Fz, Cz, C3, Pz and Oz areas. The results indicate that with increased age there was a greater uniformity of EEG activity across the brain. Magnitude of EEG power was significantly less variable across recording sites for the old than for the young. In addition, cortical coupling values were reliably higher for the older subjects indicating a greater congruity among EEG patterns. The EEG power and cortical coupling measures were significantly correlated and thus may indicate an underlying mechanism common to both. The results support a theory of decreased central inhibitory function in old age and may reflect an age-related breakdown of functional autonomy of cortical areas. Gender had no significant effect on either EEG power or cortical coupling.