Tracheal reconstruction using irradiated homologous grafts in rabbits

Management of tracheal stenosis is troublesome and challenging. Numerous techniques have been used in the past with varying success. The technique of irradiated homograft tracheal cartilage transplantation shows promise for the future in the area of tracheal reconstruction.     

Antagonism of diazepam hyperphagia by propranolol in rats

The effects of adrenergic beta-receptor blockers on the hyperphagia produced by diazepam were studied in free-feeding rats. The hyperphagia produced by 1.0 mg/kg subcutaneous (s.c.) diazepam, was antagonised by dl-propranolol (6.0 mg/kg s.c.) and 1-propranolol (6.0 mg/kg s.c.), but not by d-propranolol (6.0 mg/kg s.c.). Intracerebroventricular administration of dl-propranolol (50, 100, and 200 μg) failed to antagonise this hyperphagia. Other specific β₁ and β₂ blockers, metoprolol (10.0 mg/kg s.c.), and butoxamine (10.0 mg/kg s.c.) also did not antagonise this hyperphagia. It is suggested that some intrinsic property other than β-blockade, tranquilising, or local anesthetic activity is responsible for this antagonism caused by s.c. administration of dl- or l-propranolol.     

Effect of spermine on membranolytic effect of vitamin A in rats

The effect of spermine on membranolytic effect of vitamin A has been studied on mitochondrial membrane integrity by examining phospholipase A2 activity and membrane phospholipids. Spermine arrest the vitamin A induced activity of mitochondrial phospholipase A2. The function of vitamin A in vision is fairly well understood. Though the part that vitamin A plays in vision is of high significance; vitamin A deficient animal not only become blind but eventually die. This indicates that vitamin A plays an indispensable role in general metabolism. The mechanism of absorption, transport and storage of vitamin A have been intensively studied [1, 8, 9]. Administration of vitamin A in large doses for prolonged periods is found to be toxic. This toxicity is termed as hypervitaminosis A. Excess of vitamin A to animals have been found to cause membrane labilization of various cellular organelles, e.g. mitochondria, lysosomes and release their contents. Alternations in membrane functions of liver mitochondria have also been observed in rats given excess of vitamin A. Polyamines have been shown to stabilize membrane structure against lysis or swelling for several microorganism and mammalian subcellular fractions [2, 4, 5, 7]. The stability of mitochondrial and lysosomal membranes are in reciprocal relationship with the activity of endogenous phospholipases bound to these membranes [4, 11]. Polyamines were shown to inhibit phospholipase A2 activity of heart mitochondria [12]. Phospholipase A2 detaches the fatty acid from the position of phosphatidyl choline, and the lysolecithin formed has a detergent effect that can produce membrane destabilization. The mechanism of inhibition by polyamines appears to be related to the effect of basic proteins as phospholipase digestion.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of interaction of heavy metals on (Na+ -K+) ATPase and the uptake of 3H-DA and 3H-NA in rat brain synaptosomes

The effect of interaction of Mn2+, Pb2+ and Cd2+ on (Na+ -K+) ATPase and uptake of labelled dopamine (3H-DA) and labelled noradrenaline (3H-NA) were studied in vitro in rat brain synaptosomes. The inhibition of (Na+ -K+) ATPase by Pb2+ and Cd2+ alone was concentration dependent, however, Mn2+ had almost no effect on the activity of this enzyme. Interaction of Cd2+ with either Pb2+ or Mn2+ was most powerful in inhibiting the activity of synaptosomal transport ATPase. Lower concentrations of Pb2+ increased while higher concentrations inhibited synaptosomal uptake of 3H-DA and 3H-NA. Lower concentrations of Cd2+ increased the uptake of 3H-DA while at concentrations of 100 microM, the uptake was inhibited, this metal had strong inhibitory effect on the uptake of 3H-NA. Mn2+ had inhibited the uptake of labelled amines. Interaction of Mn2+ with Pb2+ or Cd2+ produced inhibition on the uptake of 3H-DA and 3H-NA. The results of the uptake of biogenic amines in the presence of metal ions apparently had no correlation with the activity of (Na+ -K+) ATPase which is involved in the active transport of cations across cell membranes.     

Regional wall motion improvement after coronary thrombolysis with recombinant tissue plasminogen activator: importance of coronary angioplasty

To evaluate functional recovery in 20 consecutive patients with acute myocardial infarction who received recombinant tissue-type plasminogen activator, serial two-dimensional echocardiograms were performed before and immediately after tissue plasminogen activator administration and at 1 and 10 days postinfarction. Tissue plasminogen activator was administered intravenously (17 patients) or by intracoronary infusion (3 patients) after angiographic confirmation of total occlusion. Reperfusion, documented by angiography, occurred in 13 of the 20 patients. The mean time from onset of chest pain to thrombolysis was 5.1 +/- 1.1 hours. Echocardiograms were evaluated for regional function with a visual semiquantitative scoring system by two independent observers who had no knowledge of patient identity, temporal sequence, therapy or effect of therapy. There was no immediate or 24 hour improvement in wall motion. At day 10 compared with pretreatment, 28 of 33 reperfused infarct zone segments versus 6 of 20 nonreperfused infarct segments demonstrated improved wall motion (p = 0.01). This improvement did not relate to time from onset of chest pain to successful thrombolysis. Of reperfused infarct zone segments in the distribution of coronary artery balloon dilation, 19 of 23 segments exhibited improvement versus 7 of 17 (reperfused, no angioplasty) and 6 of 20 (nonreperfused, no angioplasty) segments (p = 0.001). Infarct zone segments reperfused at the time of ongoing chest pain demonstrated functional recovery compared with segments reperfused in the absence of chest pain (18 of 23 versus 10 of 20, respectively; p = 0.05). Thus, in this uncontrolled series, there was echocardiographically detectable improvement in function of reperfused infarct segments 10 days after coronary thrombolysis with recombinant tissue plasminogen activator.