Rare left colic artery variation of the gut arterial system.

Most variations of the abdominal blood supply are related to branching of the coeliac trunk and superior mesenteric artery. This case details a remarkable variation in the branching pattern of the left colic artery (LCA) observed during routine cadaveric dissection of an 84-year-old male donor. An anomalous common trunk, originating from the common hepatic artery, gave rise to three branches: 1) an accessory posterior pancreaticoduodenal artery to the head of the pancreas and adjacent duodenum, 2) the dorsal pancreatic artery anastomosing with branches of the splenic artery, and 3) the LCA. The LCA descended between the splenic vein and superior mesenteric artery to supply the left colic flexure and form a collateral route with the middle colic artery by contributing to the marginal artery of Drummond. Knowledge of this variation is clinically relevant for surgical and radiological procedures in the abdomen.

A unique case of extrarenal calyces and associated vascular variations in an adult female cadaver.

The following urogenital and vascular anomalies were observed in the left kidney of an 81-year-old female cadaver during routine dissection: three extrarenal calyces; an accessory renal artery originating directly from the abdominal aorta; and a circumaortic renal vein. The typical renal anatomical structures were identified, from anterior to posterior, as the renal vein, renal artery, and ureter appearing near the hilum of the left kidney. After closer examination, three extrarenal calyces were observed exiting from the hilum of the left kidney to form the pelvis, then narrowed and became the ureter which descended 21.5 cm to empty into the bladder. The accessory renal artery originated from the lateral aspect of the abdominal aorta 7.3 cm below the aortic origin of the left renal artery. A corresponding accessary renal vein, identified as a circumaortic vein, left the hilum 4.5 cm below the left renal vein and travelled posterior to the abdominal aorta to drain into the inferior vena cava. Extrarenal calyces are rare among urogenital tract variations. They can be associated with embryological abnormalities such as renal ectopia, horseshoe kidney or malrotation as well as clinical manifestations such as pelviureteric junction obstruction and hydronephrosis. Compression of the accessory renal artery can cause decreased blood flow to the inferior pole of the left kidney, thereby causing fibrosis, atrophy, or renal failure. The retro-aortic path of the circumaortic renal vein has been associated with posterior nutcracker phenomenon, haematuria, left renal vein thrombus formation, and renal vein hypertension. This unique combination of a collecting system anomaly and extrarenal vessel variations could have significant implications in abdominal surgery.

Cerebrospinal fluid rhinorrhea: a review of the literature.

CSF rhinorrhea may be spontaneous or traumatic, the majority of cases being traumatic and presenting within the first three months. Spontaneous leaks imply an underlying abnormality which must be identified prior to treatment. Diagnosis and identification of the site of the leak is often inaccurate, even with meticulous care given to placing and removing the nasal pledgets. Once the leak is identified, medical or surgical treatment may be attempted. Recurrent leaks are common and serial operative procedures have been reported to stop even small leaks.

Extracranial approaches to the repair of cerebrospinal fluid rhinorrhea.

This paper presents a review of the extracranial evaluation and treatment of cerebrospinal fluid (CSF) rhinorrhea. Diagnosis with attention to a careful history and physical with maneuvers which exacerbate drainage and thorough physical exam along with imaging techniques are discussed. The common etiologies of CSF rhinorrhea including trauma, spontaneous leakage, tumor, and iatrogenic injury are included. Management consists of conservative measures including the avoidance of straining maneuvers which increases intracranial pressure. Periodic drainage of CSF via lumbar puncture or continuous drainage via flow-regulated systems may also be of benefit in attempts of conservative management. Failure of conservative management, constant leakage, pneumocephalus, and recurrent meningitis are indicators for surgical repairs. Ethmoid-cribiform plate region repairs are generally approached by external ethmoidectomy and the development of mucoperiosteal flaps from various donor sites which are then rotated to the leak area to seal the defect. Frontal sinus leaks are usually repaired via an osteoplastic flap technique with direct repair of the dural defect or the use of fascial graft tucked under the bony defect, then obliterated with abdominal fat. CSF rhinorrhea presents a diagnostic and surgical challenge to the otolaryngologist. After diagnosis and localization, operative repair using extracranial approaches is accepted as the initial method of intervention in these cases.

N6-substituted 9-methyladenines: a new class of adenosine receptor antagonists.

A series of 15 N6-substituted 9-methyladenines have been assessed as antagonists of A2-adenosine receptor-mediated stimulation of adenylate cyclase in membranes of human platelets and rat PC12 cells and of A1-adenosine receptor-mediated inhibition of adenylate cyclases in membranes of rat fat cells and as inhibitors of binding of N6-R-[3H]phenylisopropyladenosine to A1-adenosine receptors in rat brain membranes. N6 substitution can markedly increase the potency of 9-methyladenine at A1 receptors, while having lesser effects or even decreasing potency at A2 receptors. Effects of N6 substituents on adenosine receptor activity of the 9-methyladenines are reminiscent of effects of N6 substituents on activity of adenosine, suggesting that N6 substituted 9-methyladenines bind to adenosine receptors in the same orientation as do N6-substituted adenosines. N6-Cyclopentyl-9-methyladenine with Ki values at the A1 receptors of 1.3 microM (fat cells) and 0.5 microM (brain) is at least 100-fold more potent than 9-methyladenine (Ki 100 microM, both receptors), while at the A2 receptors KB values of 5 microM (platelets) and 25 microM (PC12 cells) make it 5-fold more potent and equipotent, respectively, compared to 9-methyladenine (KB 24 microM, both receptors). N6-Cyclopentyl and several other N6-alkyl and N6-cycloalkyl analogs are selective for A1 receptors while 9-methyladenine is the most A2 receptor selective antagonist. The N6-R- and N6-S-(1-phenyl-2-propyl)-9-methyladenines, analogous to N6-R- and N6-S-phenylisopropyladenosines, exhibit stereoselectivity at both A1 and A2 receptors. Marked differences in potency of certain N6-substituted 9-methyladenines at the A2 receptors of human platelets and rat PC12 cells provide evidence that these are not identical receptors.

Characterization of the A1 adenosine receptor-adenylate cyclase system of cerebral cortex using an agonist photoaffinity ligand.

Endogenous adenosine acting via A1 adenosine receptors is capable of inhibiting adenylate cyclase activity and neurotransmitter release in the brain. In this report, we describe the synthesis and attributes of a new series of A1 adenosine receptor agonists. One of these, [125I]N6-2-(4-amino-3-iodophenyl)ethyladenosine, can be used as a radioligand and another, [125I]N6-2-(4-azido-3-iodophenyl)ethyladenosine, as a photoaffinity probe. The unlabeled ligand, N6-2-(4-aminophenyl)ethyladenosine, and its iodinated product are full agonists, inhibiting cyclic AMP production in rat cerebral cortex membranes to the same extent as the prototypic A1 agonist N6-R-1-phenyl-2-propyladenosine. These new ligands are not substrates for adenosine deaminase. The new photoaffinity azide described here labels an Mr 38,000 protein that displays all the pharmacological characteristics expected of the A1 adenosine receptor. This is the same molecular-weight protein previously described using a cross-linking radioligand. This new azide compound demonstrates a 15-fold higher efficiency of incorporation, making it the photoaffinity probe of choice for tissues containing low concentrations of A1 adenosine receptors.

Dog coronary artery adenosine receptor: structure of the N6-aryl subregion.

Previous structure-coronary vasoactivity correlations of the N6-alkyladenosine analogues of N6-[(R)-1-phenyl-2-propyl]adenosine, 1, support the hypothesis that the coronary artery A2 adenosine receptor contains an N6 region of specialized structure. The part of this receptor region that binds the 2-propyl moiety of 1 determines stereoselectivity and contributes to coronary vasoactivity. The present study uses 92 adenosine analogues containing an aryl group in the N6 substituent to test the hypothesis that the N6 receptor region contains an aryl subregion that binds the phenyl moiety of 1 and thereby contributes to its coronary vasoactivity. N6-Aralkyladenosines are often more potent than their alkyl congeners. Two methylene residues seem to provide optimum separation of the aryl group from N6. Among adenosines with semirigid N6 substituents, N6-[(1R,2S)-trans-2-phenylcyclohexyl]adenosine was uniquely active, evidence that when 1 occupies the receptor, the axis of the propyl C-1 to phenyl C-1 bond is nearly in the plane described by N6 and propyl C-1 and C-2. The torsion angle around this bond is unknown. Replacing the phenyl group of N6-2-phenethyladenosine with a thienyl or a 3-pyridyl group raises activity. The structure-activity relationships of the N6-(arylethyl)-, the N6-(arylmethyl)-, and the N6-phenyladenosines differ strinkingly from each other. Taken together, such results support the idea that the N6 region of the dog coronary artery A2 adenosine receptor includes an aryl subregion.

The A1 adenosine receptor. Identification of the binding subunit by photoaffinity cross-linking.

Adenosine modifies the catalytic activity of adenylate cyclase through both inhibitory (A1 or Ri) as well as stimulatory (A2 or Ra) cell surface receptors. We developed 125I-labeled N6-2-(4-aminophenyl)ethyladenosine as a selective ligand to probe the structure of A1 receptors. The binding of this radioligand to rat cerebral cortex or adipocyte membranes is saturable, reversible, and of high affinity (KD approximately 2 nM). A1 receptor agonists antagonize binding stereoselectivity and with a potency order appropriate for A1 receptors. The heterobifunctional cross-linking reagent N-succinimidyl-6-(4-azido-2-nitrophenylamino)hexanoate covalently couples the radioligand to a protein of Mr = 38,000 in both tissues as demonstrated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography. Inhibition of covalent labeling by adenosine analogs exhibited the stereoselectivity and potency order typical of A1 receptor ligands. Guanine nucleotides reduced both specific binding and covalent incorporation of the radioligand, evidence that the radioligand is an A1 receptor agonist. These results suggest that the A1 receptor binding subunit of both brain and adipocytes resides on a protein of Mr = 38,000. The new radioligand should prove useful in studying the structure and regulation of A1 receptors.

An abdominal left ventricular assist device: preclinical studies.

An abdominally positioned left ventricular assist device (ALVAD) has been evaluated in our most recent series of 25 calves weighing 99 plus or minus 12 kg. The ALVAD is a pneumatically actuated bladder pump, positioned subdiaphragmatically and connected between the left ventricular apex and the infrarenal abdominal aorta. The mean survival time in the calves was 41 days and the longest 65 days. The major effects of the pump are reduction of all indices of left ventricular work and increases in systemic perfusion. In the awake, unanesthetized calf, left ventricular pressure, dP/dt, and stroke work were decreased while peak aortic pressure, stroke volume, and cardiac output increased. These effects were corroborated at cardiac catheterization two to four weeks postoperatively; left ventriculograms also showed increases in ejection fraction. These data demonstrate the ALVAD's effectiveness in assuming left ventricular function and support over extended periods. The device has been developed for short-term postoperative clinical use in patients with reversible left ventricular failure.