Azygos continuation of the inferior vena cava: sonographic demonstration of the renal artery ventral to the azygos vein as a clue to diagnosis.

OBJECTIVE: The purpose of this report is to describe the relationship between the renal artery and the azygos vein in patients with congenital infrahepatic interruption of the inferior vena cava with azygos continuation. CONCLUSION: Using abdominal sonography, we showed that in patients with interruption of the inferior vena cava with azygos continuation, the renal artery is ventral to the azygos vein. Because this malformation is frequently associated with cardiac and situs anomalies, awareness of the anatomic relationship between the renal artery and the azygos vein can aid in diagnosis and may substitute for more expensive and invasive diagnostic procedures.

Physical therapy for the patient with acquired immunodeficiency syndrome.

Treatment of HIV-infected patients has come a long way since the not-so-long-ago beginning of the AIDS epidemic. Implementation of new drug therapies has increased longevity of a patient's life after being diagnosed with the virus. Because HIV-related illnesses are consequently becoming more chronic in nature, patients commonly experience potentially debilitating CNS, PNS, or musculoskeletal problems during the course of the disease. As a result, these patients require delicate care from a number of different health care providers. A multidisciplinary team approach must be used within the podiatrist's treatment regimen. This team must include the physiatrist overseeing the physical therapist, to provide complete and optimal care to improve the patient's functional independence and quality of life. The conditions associated with HIV infection are insidious, slow, and crushing in nature. The medical community can help the patient with HIV infection and AIDS remain on his or her feet. By doing this, costs, both social and economic, can be lowered. The podiatrist must have a strong knowledge of the pathology of AIDS. He or she must use PT along with other disciplines: podiatric medicine, orthotic therapy, and general podiatric care. PT is effective in treating conditions of the lower extremities that affect the CNS, PNS, musculoskeletal system, and, lastly, rheumatologic effects of HIV infection.

Active calcium uptake by islet-cell endoplasmic reticulum.

Active calcium uptake was demonstrated in a subcellular fraction of islets which was enriched in endoplasmic reticulum. Calcium uptake was stimulated by ATP in a magnesium-dependent manner. The rate of calcium accumulation was sustained by oxalate (10 mM) and uptake was prevented or reversed by addition of the calcium ionophore A23187. This calcium uptake process was not affected by azide or ruthenium red. Direct comparison of calcium uptake by endoplasmic reticulum-enriched and plasma membrane-enriched fractions indicated that the uptake was not due to contamination of the fraction with plasma membrane vesicles. These factors as well as the purity of the fraction indicate that the calcium uptake system resides in the endoplasmic reticulum. The properties of the islet endoplasmic reticulum calcium uptake system are similar to properties reported for endoplasmic reticulum derived from other cell types. These properties include stimulation by potassium and a Km for ionized calcium of 1.5 +/- 0.3 microM. The islet-cell endoplasmic reticulum may play a critical role in cellular calcium homeostasis and contribute to the regulation of insulin secretion.

Temporal changes in islet polymerized and depolymerized tubulin during biphasic insulin release.

In the present study, a colchicine binding assay was used to measure changes in islet polymerized and depolymerized tubulin at intervals characterizing the biphasic pattern of glucose-induced insulin release i.e., 2.5, 5.5, 10.5, and 30.5 min. At 2.5 min during the rapid onset of insulin release, a significant increase from 24% to 33% in polymerized tubulin content was observed. This increase in polymerized tubulin was followed by a reduction that temporally correlated with the disappearance of first phase release. Second phase release was also associated with a shift in equilibrium favoring tubulin polymerization at longer incubation periods. The effect of cytochalasin B on the equilibrium between polymerized and depolymerized tubulin was evaluated at a submaximal glucose concentration of 16.5 mM. Under these conditions, cytochalasin B increased polymerized tubulin content in a manner that parallels its enhancing effect on insulin release. These results indicate that the rapid events associated with the biphasic pattern of insulin release are temporally correlated with changes in polymerized tubulin.

Characterization of the uptake of the methylxanthines theophylline and caffeine in isolated pancreatic islets and their effect on D-glucose transport.

The uptake of theophylline and caffeine was determined in isolated pancreatic islets employing a dual isotope procedure with sucrose as an extracellular marker. Islets rapidly accumulated caffeine and theophylline with apparent dissociation constants of approximately 23 and 6 mM, respectively. Theophylline inhibited the uptake of caffeine and caused displacement of caffein from islets. These results indicated a competition by theophylline and caffeine for a common site (binding and/or transport carrier). In addition, theophylline and caffeine inhibited D-glucose transport in a dose-dependent manner and within the limits of the experimental system, this inhibition appeared to be non-competitive. (Bu)2cAMP under similar experimental conditions exerted no effect on D-glucose transport. These results present evidence for a rapid uptake of theophylline and caffeine in pancreatic islets, which is compatible with their immediate cellular effects. In addition, these results demonstrate a direct effect by theophylline and caffeine on D-glucose transport which appears independent of their ability to alter intracellular cAMP levels.

Ninhydrin inhibition of glucose-induced insulin release.

Ninhydrin, a compound which shares chemical properties strikingly similar to alloxan was found to mimic basically the inhibitory effect of alloxan on glucose-induced insulin release. Exposure of pancreatic islets for five minutes to 85 mumol/l ninhydrin produced approximately ninety percent inhibition of subsequent glucose-induced insulin release without altering basal secretion. Both D-glucose and D-mannose provided substantial protection against the inhibitory effect of ninhydrin, and the alpha anomer of D-glucose was more effective than the beta anomer in preventing ninhydrin inhibition of insulin release. Evidence for a common site of inhibition by ninhydrin and alloxan in the insulin release process is discussed.

Effect of anomers of D-glucose on alloxan inhibition of insulin release in isolated perifused pancreatic islets.

The in vitro inhibition of insulin released by alloxan (20 mg/100 ml) in collagenase isolated rat islets is preferentially prevented by alpha D-glucose at a concentration of 1.0 mg/ml, while at a higher anomer concentration (1.5 mg/ml) both alpha and beta D-glucose provide equal protection. The ability of alpha D-glucose compared with beta D-glucose to stimulate insulin release, in vitro, showed a similar dose-related response, as observed in the alloxan protective studies. Although, both alpha and beta D-glucose compete with mutorated D-glucose for transport into islet cells, neither anomer produced a significantly different degree of inhibition in the transport process. The shared alpha stereospecificity for D-glucose in protection against alloxan and in stimulating insulin secretion in these in vitro studies, suggest a common site of interaction which may involve the beta-cell membrane.

Effect of methylxanthines on alloxan inhibition of insulin release.

Isloated rat islets were maintained in vitro in a perifusion system, exposed to alloxan (20 mg/100 ml) for 5 minutes in the presence of agents which affect cAMP metabolism and subsequently stimulated with glucose. The rate of insulin secretion was monitored throughout the period of perifusion. Exposure to alloxan alone produces complete inhibition of glucose-induced insulin release [18] whereas concomitant exposure to carreine and theophylline for this brief interval provided almost complete protection of the islets from the inhibitory action of alloxan. Glucagon, cAMP and CBcAMP did not protect the islets form alloxan. Pre-treatment of the islets with either theophylline or glucagon and DBcAMP did not provide protection. These findings indicate that the protective action of theophylline and carreine against alloxan is unrelated to the effect of these agents on cAMP metabolism in the beta cell.

Isolation and properties of secretory granules from rat islets of Langerhans. I. Isolation of a secretory granule fraction.

A method has been devised for the isolation of a secretory granule fraction from isolated rat islets of Langerhans. The islets were homogenized in buffered sucrose, and the homogenate was separated into nuclear, mitochondrial, secretory granule, and microsomal fractions by differential centrifugation. The secretory granule fraction was purified by differential centrifugation in discontinuous sucrose density gradients. A greater degree of purification could be achieved by the use of two successive gradients of this type, although the final yield was greatly reduced. Biochemical and morphological characterization of the fractions was obtained; the secretory granule fraction contained both insulin and glucagon. The limiting membranes of the granules remained intact and the general appearance of the granules was similar to that seen within the whole islet cells.