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This study was carried out in order to determine the effects of the inspiration of O2-enriched air on the size of myocardial infarction. In 15 anesthetized dogs, epicardial electrograms were recorded from 10 to 14 sites on the anterior surface of the left ventricle before and after intermittent occlusion of the left anterior descending coronary artery or one of its major branches. In each dog, one occlusion was carried out while the fraction of inspired oxygen (FIO2) was 0.20 and the other while the FIO2 was 0.40. With an FIO2 of 0.20 the average ST-segment elevation (ST) was 4.0 +/- 0.6 mV (SEM) and the number of sites exhibiting ST-segment elevations exceeding 2 mV (NST) 15 minutes following occlusion was 6.2 +/- 0.7 sites; comparable values following occlusion with an FIO2 of 0.40 were 1.8 +/- 0.4 mV (P less than 0.01) and 2.7 +/- 0.7 sites (P less than 0;01), reflecting reduction in acute myocardial ischemic injury; An FIO2 of 1.0 did not decrease myocardial injury further. In 24 other dogs, occlusion was maintained for 24 hours. In nine dogs in which FIO2 was increased from 0.20 to 0.40 30 minutes after occlusion, myocardial creatine phosphokinase activity (CPK) was less depressed in sites having comparable levels of ST-segment elevation at 15 minutes than in dogs that respired an FIO2 of 0.20 during the entire 24 hours. All (54) sites with ST-segment elevations greater than 3 mV in the 0.20 FIO2 group showed early signs of myocardial infarction, while only 49% of such specimens showed infarction in the 0.40 FIO2 group. Thus it is concluded that 0.40 FIO2 following an experimental coronary artery occusion decreases acute ischemic injury and reduces the eventual development of necrosis, as evaluated by enzymatic and histological techniques.
Circulation 1975 Sep
PMID:Reduction of infarct size by oxygen inhalation following acute coronary occlusion. 115 35

Platelet survival time was measured (autologous labelling with 51chromium) in 68 men with coronary artery disease (CAD). Survival was shortened slightly (3.2 +/- 0.04 days; mean +/- SEM) as compared to normal (3.7 +/- 0.04 days; N = 18; P less than 0.001), and 60% had shortened survival (less than 3.3 days). Thirty-seven had hyperlipoproteinemia (36 with Type IV and one with Type III) and platelet survival was shortened (3.1 +/- 0.10 days) and significantly different from survival of men with normal lipoproteins (3.3 +/- 0,12 days; P less than 0.05). Twenty-two with shortened platelet survival and CAD received either clofibrate or sulfinpyrazone. Clofibrate prolonged platelet survival (2.6 +/- 0.09 to 3.4 +/- 0,14 days; P less than 0.001) and ten of 12 had prolongation of survival. Sulfinpyrazone increased survival (2.8 +/- 0.12 to 3.6 +/- 0.21; P less than 0.001) and nine of ten had prolognation of platelet survival. Clofibrate lowered serum cholesterol and tryglyceride but alteration in lipids did not correlate with alteration of survival. Sulfinpyrazone did not alter lipids. Data suggest that survival is shortened in CAD and that clofibrate and sulfinpyrazone alter survival. Platelet suppressant agents may prove beneficial in reducing the extent and complications of atherosclerotic arterial injury.
Circulation 1975 Sep
PMID:Effects of clofibrate and sulfinpyrazone on platelet survival time in coronary artery disease. 115 47

Treatment with oral prednisone (15 mg every 6 h) for 1 day plus a 4-h glucose infusion at 2.8 mg/min kg body weight to 5 normal, healthy individuals raised their blood glucose to 137 +/- 4.5 mg per 100 ml (mean +/- SEM). In order to evaluate the effects of steroid-induced hyperglycemia on insulin responses, a model for the duplication of blood glucose concentration in serial studies was developed. During glucose infusion at 5.7 mg/min kg body weight, the fractional uptake of glucose at the end of infusion (KG) was 2.08 +/- 0.2%/min and the apparent volume of distribution (V) was 285 +/- 10.5 ml/kg. Further increase in the rate of glucose infusion did not affect KG and V. Based on these parameters, KG and V, the stable blood glucose achieved during the prednisone study (C) was duplicated both after short (4 h) and prolonged (28 h) glucose infusions (138 +/- 4.5 and 146 +/- 4.5 mg/100 ml, respectively) at rates calculated as the product of KG.C.V. The effects of prednisone treatment on insulin secretion were examined (1) during fasting, (2) at identical glucose concentrations during glucose infusions at constant rates, and (3) in response to glucose pulse (0.1 g/kg) during the infusions. During fasting, there was a significant elevation of mean blood glucose with prednisone (99 +/- 1.8 mg/100 ml) compared with that in the control study (88 +/- 1.7 mg/100 ml). The plasma IRI, however, remained unchanged (10 +/- 2.3 vs 10 +/- 1.6 muU/ml). During glucose infusions in the presence of similar blood glucose levels, the IRI was lower after prednisone treatment (18 +/- 1.5 muU/ml) than during the short and prolonged glucose infusions (42 +/- 5.1 and 63 +/- 7.0 muU/ml). The insulin response to the glucose pulse also was significantly lower during steroid treatment. Thus, prednisone apparently has an early inhibitory effect on the insulin response to glucose.
J Clin Endocrinol Metab 1975 Sep
PMID:Inhibitory effect of prednisone on insulin secretion in man: model for duplication of blood glucose concentration. 115 64

Electrophysiological studies were performed in 16 patients before and 30 min after intravenous administration of ouabain (0.1 mg/kg). P-A interval (mean+/-SEM) was 40+/-2.1 ms before and 44+/- 1.5 ms after ouabain (P less than 0.001). Atrial effective and functional refractory periods (ERP and FRP) were measured in all patients during sinus rhythm and during driving at equivalent paced rates in 12 patients. The mean atrial ERP and FRP during sinus rhythm were, respectively, 244+/-10.5 and 307+/-11.0 ms before and 253+/-9.7 and 318+/-11.4 ms after infusion of ouabain (NS). Mean atrial ERP and FRP during driving were, respectively, 231+/-15.3 and 264+/-14.9 ms before and 266+/-18.6 and 296+/-19.7 ms after ouabain (P less than 0.01 and P less than 0.01). Mean sinus cycle length and sinus recovery times were, respectively, 887+/-31.2 and 1,113+/-38.7 ms before and 905+/-38.2 and 1,008+/-30.7 ms after infusion of ouabain (NS and P less than 0.005). Calculated sinoatrial conduction times before and after ouabain were 90+/-6.8 and 110+/-8.5 ms, respectively (P less than 0.005). In summary, ouabain produced depression of intraatrial conduction as manifested by increase in P-A interval and atrial effective and functional refractory periods. Ouabain significantly increased calculated sinoatrial conduction time without significant effect on spontaneous sinus cycle length.
J Clin Invest 1975 Sep
PMID:The electrophysiological effects of ouabain on sinus node and atrium in man. 115 73

The early differentiation of the connective tissue was investigated in the perinotochordal zone of 2-3 day-old chick embryos. After characterizing the different tissue components by transmission electron microscopy, their arrangement and distribution were examined by SEM. The results are discussed with regard to the role of the extracellular material in embryonic tissue interactions.
Experientia 1975 Sep 15
PMID:[The early differentiation of the perinotochordal connective tissue. A scanning and transmission electron microscopic study on chick embryos (author's transl)]. 117 54

Ethacrynic acid infused i.v. in anesthetized dogs after inhibiting sympathetic mechanisms of renin release increased renal blood flow rate (RBF) by 54% and practically abolished autoregulation of RBF; renin release increased from 0.8 +/- 0.9 (mean +/- SEM) to 16.4 +/- 3.7 mug/min (P less than 0.05). Without infusion of ethacrynic acid; constriction of the renal artery to a pressure below the range of autoregulation reduced renovascular resistance markedly and renin release rose to 27.2 +/- 5.5 mug/min (P less than 0.05). During arterial constriction, ethacrynic acid had no additional effect on renovascular resistance or renin release averaging 28.4 +/- 6.7 mug/min. Infusion of ethacrynic acid and saline at control pressure increased sodium excretion to about one-half of the filtrate and reduced rein release which did not, however, return to control. Infusion of hypertonic saline during autoregulated vasodilatation induced by arterial constriction had a similar effect, but again renin release continued to exceed control. We propose that ethacrynic acid increases renin release through a hemodynamic mechanism triggered by afferent arteriolar dilation and inhibits renin release by greatly increasing the delivery of sodium to the distal convoluted tubules.
Kidney Int 1975 Sep
PMID:Influence of ethacrynic acid on intrarenal renin release mechanisms. 117 75

Studies were conducted in four normal and six diabetic children to assess the role of adrenergic blockade on basal and arginine-stimulated growth hormone and glucagon secreation. Each subject had, on three separate occasions, infusion of arginine alone or in conjunction with alpha (phentolamine) or beta (propranolol) adrenergic blockade. Clinically, there was evidence of adequate blockade by each agent. Basal hormone growth levels were not significantly different in the two groups (1.3 +/- 0.2 to 2.1 +/- 1.0 ng/ml in normal subjects; 3.0 +/- 1.1 to 6.0 +/- 3.1 ng/ml in diabetics (mean +/- 1 SEM)) but the peak growth hormone after arginine was significantly greater in the diabetic children than control subjects (34.3 +/- 7.2 versus 12.3 +/- 3.1); in both groups alpha-blockade suppressed the growth hormone response, whereas beta-blockade had no significant effect. Basal glucagon concentrations were similar in both groups (147 +/- 31 to 214 +/- 21 pg/ml in normal subjects; 100 +/- 20 to 124 +/- 17 pg/ml in diabetics on three different occasions) despite the coexistent hyperglycemia of the diabetics. Neither basal nor maximally stimulated glucagon secretion was significantly affected by alpha or beta blockade in the juvenile diabetic or control children. The results suggest that sympathetic overactivity via alpha receptors may contribute to the hypersecretion of growth hormone in juvenile diabetes and that the alpha or beta adrenergic receptor alone does not appear to modulate basal or arginine stimulated glucagon secretion.
Pediatr Res 1975 Sep
PMID:Effect of adrenergic blockade on glucagon and growth hormone secretion in normal and diabetic children. 120 24

The principal distance, D, from the centre of perspective in the SEM optical projection to the tilt axis of the specimen stage must be accurately determined before photogrammetric evaluation of stereoscopic pairs of micrographs can proceed. A precise procedure for measuring D is described in which the specimen stage X micrometer is used to measure the width of the field scanned for a particular width of the CRT, when the specimen stage is moved along the electron beam axis by amounts measured with the stage Z micrometer. The Z micrometer is calibrated with an external dial gauge. A plot of field width against Z extrapolated to zero gives the location of the perspective centre. In SEM photogrammetry, it is usual to leave the lens currents unchanged whilst recording the stereo-pairs. The values of D measured with a constant final lens current show that the perspective centre is located close to the final aperture in its conventional position. Previous determinations of D for Stereoscans have used a changing lens current to keep the specimen in focus at varying Z, and found a virtual centre several millimetres above the final aperture. The value of D so obtained should only be used if the micrographs were recorded with dynamic or automatic focusing systems.
J Microsc 1975 Sep
PMID:Determination of the principal distance and the location of the perspective centre in low magnification SEM photogrammetry. 124 52

The effects of 4-aminopyridine (4-AP) and tetraethylammonium (TEA) on the outward potassium currents in the rapidly and slowly adapting stretch receptor neurons (SRNs) of the crayfish (Pacifastacus leniusculus) were studied using a two micro-electrode voltage-clamp technique. The leakage current was not affected by either 4-AP or TEA. External 4-AP blocked the peak outward current in a dose-dependent manner (1:1 stoichiometry) with an apparent dissociation constant (Kd) of 2.3 +/- 0.2 mM (mean +/- SEM) in the slowly and 1.4 +/- 0.2 mM in the rapidly adapting SRN, the block being voltage dependent. External application of TEA resulted in a block of the steady state current enhancing the transient characteristics of the current response. The block appeared to deviate from a 1:1 stoichiometry and the apparent Kd for TEA was 9.6 +/- 3.4 mM with a cooperativity factor n = 0.43 +/- 0.03 in the slowly adapting SRN and 34.5 +/- 9.2 mM and 0.37 +/- 0.03 respectively in the rapidly adapting SRN. Low Ca2+, apamin and charybdotoxin, which are known to block Ca(2+)-dependent K-currents, had no effects on the outward current as was also the case with catechol. It is concluded that the different effects of TEA and 4-AP on the outward current in the two types of SRNs can be explained by the presence of at least two, probably heteromultimeric, channel populations having similar sensitivity to 4-AP but different sensitivity to TEA. One channel has a high affinity (Kd = 0.8-1.6 mM) for TEA and the other a low affinity (Kd = 173-213 mM) for TEA. The low-affinity channel seems to dominate in the slowly adapting SRN while both channels are equally common in the rapidly adapting SRN. Further, the present results do not support the existence of a macroscopic Ca(2+)-dependent K+ current in the SRNs.
Acta Physiol Scand 1992 Sep
PMID:Block of potassium outward currents in the crayfish stretch receptor neurons by 4-aminopyridine, tetraethylammonium chloride and some other chemical substances. 127 41

To determine alpha-fetoprotein (AFP) in human saliva, a highly sensitive sandwich enzyme immunoassay for saliva AFP was developed. AFP standards and saliva samples were added into the wells of a polystyrene plate coated with goat IgG antibody against human AFP. After incubation, the wells were washed and horseradish peroxidase-labelled antibody was added. The enzyme activity specifically bound to the well was assayed using 3,3',5,5'-tetramethylbenzidine and hydrogen peroxide as substrate. The reaction was stopped by addition of 2 M sulphuric acid and the AFP concentration was determined from the absorbance at 450 nm. The minimum detectable concentration was 8 ng/L. The recovery of AFP mixed with human saliva was 91.1-102.4%. The within-assay and between-assay coefficients of variation were 6.5-8.9% and 7.6-10.8%, respectively. The assay correlated well with a radioimmunoassay for human AFP (r = 0.985, n = 13, P less than 0.001). The mean concentration of AFP in normal human saliva was 14.3 ng/L (SEM = 4.9 ng/L, n = 10) and significantly higher levels of saliva AFP were observed in hepatocellular carcinoma patients with positive serum AFP (mean 1367.8 ng/L, SEM 595.4 ng/L, n = 6; P less than 0.001). Strong correlation was observed between saliva AFP and serum AFP (r = 0.978, P less than 0.01, n = 13).
Ann Clin Biochem 1992 Sep
PMID:Highly sensitive sandwich enzyme immunoassay for alpha-fetoprotein in human saliva. 128 27


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