Vascular Trunk Research Articles

Tetralogy of Fallot. Development of hypoplastic pulmonary arteries after palliation.

Thirty-one patients with tetralogy of Fallot were studied angiographically before and after palliation with Blalock-Taussig operation (n = 9), Brock operation (n = 12), or enlargement of the right ventricular outflow tract with extracorporeal circulation (ECC) (n = 10). The relative diameter of the pulmonary vascular ring (PVR), pulmonary trunk (PT), and right and left pulmonary arteries (RPA, LPA) were measured before and 24.8 +/- 20.9 months after palliation. Using correlation analysis, the magnitude of growth of the pulmonary artery system was inversely related to its initial size. Mean pressure in the pulmonary artery after palliation as well as the period between date of surgery and recatheterization did not correlate significantly with growth. After Blalock-Taussig operation, the ipsilateral pulmonary artery predominantly increased in size without significant growth of PVR and PT. Brock operation and enlargement of the right ventricular outflow tract with ECC, improving the flow in the pulmonary vascular system centrally, induced a significant, symmetrical growth of the pulmonary vascular system and, therefore, are our methods of choice for palliation in patients with tetralogy of Fallow combined with hypoplastic pulmonary arteries.

Homocyst(e)ine Accumulation in Pigs Fed Diets Deficient in Vitamin B-6: Relationship to Atherosclerosis

The early onset of atherosclerotic lesions in homocystinuric individuals has implicated homocyst(e)ine in the development of atherosclerosis. Two trials were conducted in which diets totally or partially deficient in vitamin B-6 were fed to pigs to investigate the accumulation of homocyst(e)ine in the plasma and the development of vascular lesions. In one trial plasma free homocyst(e)ine levels were 179 and 43 µmol/liter in deficient and adequate pigs, respectively, on day 24, while cysteine levels were 39 and 155 µmol/liter. The concentration of plasma protein-bound homocysteine and cysteine reflected the plasma-free values. Because pigs deficient in pyridoxine could be used only over short time intervals, pigs in trial 2 received 0, 0.03, 0.3 or 3 mg (i.e., 0, 2, 20 or 200% of allowance) of supplemental pyridoxine · HCl per kilogram diet. After 12 weeks pigs deficient and adequate in vitamin B-6 were injected intravenously with Evan's blue dye and the vascular trunk perfused with 2% glutaraldehyde. The aorta and major organs were removed and examined for vascular lesions. Grossly no significant lesions were seen. Light microscopy revealed occasional foci of intimal degeneration and mural thickening in the renal arterioles of pigs deficient in vitamin B-6. An area of focal medial necrosis was observed in one of the pigs deficient in vitamin B-6. Pigs fed diets containing 0.03 mg pyridoxine · HCl per kilogram diet had homocyst(e)ine concentrations not different from pigs fed diets with no added pyridoxine. Animals fed diets containing 0.3 mg pyridoxine · HCl per kilogram had homocyst(e)ine concentrations slightly higher than controls fed 3.0 mg/kg. Feed intake and weight gain increased with increasing pyridoxine in the diet. Swine offer an excellent vascular model for humans. Diets partially deficient in vitamin B-6 which cause the homocyst(e)ine concentration to increase, but allow better growth and feed consumption than diets totally deficient in pyridoxine, could be fed to pigs to study homocyst(e)ine-induced vascular damage over extended period of time.

A new approach to electromagnetic blood flow determination by means of catheter in an external magnetic field.

Maximal reduction in transverse catheter dimension has been achieved for the purpose of creating an intravascular electromagnetic flow sensor capable of percutaneous introduction into the vascular system. The electrodes are mounted on a flexible frame which collapses as it passes through a small branch blood vessel and expands to span the diameter of the main vascular trunk when entering it. Unlike the catheter flow sensors developed previously, which are velometers, i.e., sensors of fluid velocity, the present one is capable of measuring the volume rate of flow in branch blood vessels as well as in the major sections of the vascular tree. The magnetic field is provided by a large air core electromagnet placed externally to the animal or patient. A special circuit utilizing two electrodes and three leads permits reduction of the unwanted quadrature signal to zero. A standard sine wave electromagnetic flow meter channel designed for use with conventional electromagnetic flow transducers is adequate for flow measurements as well as for power supply to the large magnet. Illustrations of the performance of the apparatus in vitro and in vivo are presented.

FLORAL DEVELOPMENT AND VASCULATURE IN HYDROCLEIS NYMPHOIDES (BUTOMACEAE)

The flower of Hydrocleis nymphoides consists of three sepals which arise in spiral succession, three simultaneously arising petals, numerous stamens and staminodia which arise in centrifugal order, and six carpels. A residual apex remains at maturity. The first‐formed members of the androecium are stamens and the later‐formed members are staminodia which develop below the stamens and which become outwardly displaced during expansion of the receptacle. The androecium is supplied by branching vascular trunk bundles. The carpels are completely open but the ventral margins are slightly conduplicately appressed basally. A single dorsal bundle provides the stigmatic area with vascular tissue, and a network of small placental bundles supplies the numerous laminar ovules. There are no clearly defined ventral bundles. It is suggested that Hydrocleis nymphoides is neither the most primitive nor the most advanced member of the family. A pattern of phylogenetic reduction in the androecium and receptacle is suggested for the entire family.

Age changes in the blood supply to molar teeth of rats.

Abstract1. Rats, varying in age from one month to over one year, were used to study the changes in the vascular supply to the molar teeth and periodontium as a result of aging. The blood vessels were demonstrated by the saline‐India‐gelatin perfusion method. The jaws and teeth were fixed in a formol‐acetic acid‐alcohol solution, decalcified, dehydrated, and embedded in nitro‐cellulose in the usual manner. The embedded specimens were sectioned at 100–250 μ, cleared by the Spalteholz method and mounted unstained.2. In immature animals (younger than four months) the pulpal terminal vascular capillary networks were located at the predentin border. As the animals became progressively older, there was a gradual “withdrawal” of the terminal capillary plexuses from the odontoblastic zone so that at eight months of age, all the vascular terminals were restricted in location to the pulpal‐odontoblastic border.3. In the young animal the vessels supplying the periodontal ligament passed gingivally paralleling the bony surface of the membrane with the cemental side being devoid of vessels. During the process of aging, the above basic pattern was altered in the following manner: (a) The apposition of cellular cementum on the apical third of the root was accompanied by the presence of capillary terminals in or adjacent to the layer of cellular cementum. (b) There was a progressive decrease and eventually a loss of the interseptal vessels and their perforating branches. (c) Vascular twigs originating from the main periodontal vascular trunk were found in areas of cemental resorption indicating their need in the process of repair.