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Biomedical subjects

O Ortiz

Publications and source records attributed to O Ortiz.

49 records · Page 3Linked to original sources
PubMed1975

Resolution of the potassium ion pump in muscle fibers using barium ions.

When frog sartorius muscles recover from Na enrichment in the presence of external K, net K entry into the fibers occurs by both passive movement and active inward transport via a K pump. Under normal conditions, it has not been possible to experimentally distinguish these processes. Fractionation into the flux components must be accomplished from inferences concerning the K conductance or permeability during a period of rapid Na extrusion. The best estimates indicate that 60-80% of the K entry occurs via the K pump. In the presence of Ba ions, the membrane permeability to K is very much reduced. Under these conditions, Na-enriched muscles underwent a normal recovery in the presence of external K, and the amount of inward K movement due to the K pump rose to over 90% of the total K entry. The characteristics of the K pump studied by this means were: (a) essentially complete inhibition by 10(-4) M ouabain, (b) inhibition by [Na]omicron, (c) activation by [K]omicron according to a rectangular hyperbola in the absence of [Na]omicron, (d) linear activation by [Na]iota over a wide range in concentration, (e) zero or undetectably low pumping rate as [Na]iota leads to 0, (f) the number of Na ions actively transported per K ion actively transported is 1.4-1.7 normally and 1.1 in the presence of Ba.

Animals↗
PubMed1972

Further evidence for a potassium-like action of lithium ions on sodium efflux in frog skeletal muscle.

1. The efflux of labelled sodium as well as net sodium and lithium changes were studied in aged high sodium sartorius muscles of the South American frog Leptodactilus ocelatus.2. In the presence of 2.5 mM potassium in the media, the replacement of external sodium with lithium or magnesium resulted in an increase in sodium efflux. The magnitude of such increase was always larger in lithium.3. With the absence of potassium in the media, the response of sodium efflux to replacement of external sodium varied with the cation used as a substitute. In lithium Ringer there was always a noticeable increase, whereas in magnesium there was always a marked reduction. The same results were observed when calcium was substituted for magnesium.4. The replacement of 60 mM external sodium with sucrose did not prevent the stimulating effect of 5 mM potassium on sodium efflux, nor the inhibitory action of 10(-4)M ouabain. This indicates that neither sucrose by itself, nor the lowering of the ionic strength, modified to an appreciable extent the function of the sodium pump.5. Net sodium extrusion took place against an electrochemical gradient in potassium-free - 50 mM sodium - mM lithium Ringer. About 75% of this efflux was ouabain sensitive.6. Muscles made both sodium and lithium rich and incubated in potassium-free - 60 mM sodium - 50 mM lithium Ringer also showed net sodium extrusion against an electrochemical gradient, which was 85% ouabain sensitive. This extrusion took place even under conditions where the changes in free energy favouring lithium entry were always lower than the changes in free energy opposing sodium going out. This indicates that a sodium-lithium exchange by a counter-transport process is unlikely.7. External potassium reduced the ouabain sensitive lithium influx in muscles incubated in lithium Ringer. The values found were 5.90 +/- 0.39 mu-mole/g.hr and 2.66 +/- 0.43 mumole/g.hr in potassium-free and 15 mM potassium respectively. At the same time potassium had no effect on the ouabain-insensitive lithium uptake.8. Muscles incubated in potassium-free-magnesium Ringer had a residual sodium efflux which could not be accounted for by passive movement. About 40% of it was abolished by 10(-4)M ouabain. This ouabain-sensitive part could be a consequence of some stimulation of the sodium pump by potassium leaking out of the cells. If this is correct it should be inhibited by external sodium and should not contribute to the total sodium efflux in potassium-free sodium media.9. Magnesium was used as the reference cation to study the sodium-stimulated sodium efflux under potassium-free conditions. The total sodium efflux amounted to 0.668 hr(-1) (rate constant) and was 71% ouabain sensitive.10. The present experiments demonstrated that lithium ions have a direct stimulating effect on sodium efflux in high sodium skeletal muscle, and strongly support the notion that this effect is produced by an activation of the sodium pump through a potassium-like action.

Animals↗
PubMedDate not supplied

Ultrasound in the diagnosis of roundworms in gallbladder and common bile duct. Report of four cases.

Four patients who complained of symptoms and signs compatible with biliary tract disease and in whom the diagnosis of gallbladder (three cases) and common bile duct ascariasis (one case) was made sonographically are reported. In two patients with gallbladder ascariasis, cholecystectomy corroborated the presence of the round-worms, and was curative. The third patient was a pregnant woman (32nd gestational week) who took piperazine citrate, and a second sonogram performed 29 days later was completely normal. The fourth patient with common bile duct ascariasis underwent choledochotomy with extraction of one ascaris lumbricoides from the common duct, and a T tube was left in place for 15 days. All patients received antiparasitics and had a favorable outcome. Ultrasonography is an important noninvasive diagnostic procedure in the work-up of these patients, who usually describe a clinical picture suggesting gallstone disease: this is especially true in the presence of pregnancy.

Adult↗
PubMedDate not supplied

Popliteal artery thrombosis in a patient with Cogan syndrome: treatment with thrombolysis and percutaneous transluminal angioplasty.

A 31-year-old woman with Cogan syndrome (a rare form of systemic vasculitis) was evaluated for a cold, painful left foot with diminished pulses. Arteriography demonstrated thrombosis of the left popliteal artery with evidence of vasculitis. Thrombolytic therapy was begun with initial success but eventual rethrombosis. After reinitiating thrombolytic therapy combined with intraarterial vasodilator therapy, successful angioplasty was performed with sustained results at 6-month follow-up.

Adult↗
PubMedDate not supplied

The sacrum: pathologic spectrum, multimodality imaging, and subspecialty approach.

The sacrum is a structure that is imaged by both general and subspecialty radiologists. A wide variety of disease processes can involve the sacrum either focally or as part of a systemic process. Plain radiographs, although limited in evaluation of the sacrum, should be carefully examined when abnormalities of the sacrum are suspected. Cross-sectional imaging, particularly computed tomography and magnetic resonance (MR) imaging, plays a crucial role in identification, localization, and characterization of sacral lesions. Congenital lesions of the sacrum, including sacral agenesis and meningocele, are optimally imaged with MR. The most common sacral neoplasm is metastatic disease. Primary neoplasms of the sacrum, which include giant cell tumor, chordoma, and teratoma, are infrequent. Infection of the sacrum or sacroiliac joint is most often due to contiguous spread from a suppurative focus. A wide variety of arthritic disorders such as ankylosing spondylitis and osteoarthritis can involve the sacroiliac joints as part of a localized or systemic process. Sacral fractures related to acute trauma or repetitive stress are difficult to diagnose and treat. Knowledge of these abnormalities and familiarity with the imaging of these processes will allow radiologists of all subspecialties to contribute to the diagnosis and management of sacral disorders.

Diagnosis, Differential↗
PubMedDate not supplied

[Experimental renal insufficiency in rabbits produced by the intrarenal injection of cyanoacrylic ester].

Through a percutaneous intrarenal injection of 2 ml cyanoacrylic ester to each kidney, acute renal failure was induced in 10 experimental rabbits. Seven of the animals died as a consequence of uremia before a period of 64 hours. The other three remained alive for 96 hours although suffering from stable renal failure. Cyanoacrylic ester solidifies immediately after injection, leading to a hardened body which fills the renal pelvis, ureters and also the renal vessels. Each injection induces hydronephrosis and necrotic-hemorrhagic lesions, and infarcts in the case of vascular injection. With this simple technique immediate acute renal failure can be obtained experimentally without causing trauma or involving extrarenal structures.

Acrylates↗
PubMedDate not supplied

Delayed deterioration after head trauma due to traumatic aneurysm.

Closed head trauma is fairly common in our industrialized society. A small percentage of affected patients develop traumatic intracranial aneurysms, which rupture an average of three weeks following injury resulting in sudden neurological deterioration. The case of a patient with a traumatic aneurysm is presented. A high index of suspicion is necessary to diagnose these lesions, for which surgical treatment is recommended.

Adolescent↗