Transport of the thyroid hormones across the feline gut wall.

Intestinal absorption of radioiothyroxine (T4*) and of radiotriiodothyronine (T3*) was studied in normal cats (n = 5 for T4* and n = 6 for T3*). Absorption was localized by a series of studies comparing the time-activity data for plasma and fecal T4* or T3* radioactivity after i.v. administration with data obtained in the same cats after administration by the oral, jejunal, midileal, and cecal routes. Data were analyzed using a multicompartmental model to account for longitudinal gut transit, metabolic loss, and reversible and irreversible binding, as well as absorption. The relative importance of the gut as a site for T4* or T3* residence at steady state was determined from T4* (n = 6) and T3* (n = 3) content of gut wall and contents at the end of tracer infusion to steady state. Secretion of T4* and T3* from the general pool into the various parts of the gut was calculated from the steady-state data by fitting them to the model using its steady-state parameters. Secretion parameters were adjusted in this fitting process, which established the rate and sites of T4* and T3* secretion into the gut. Overall, feline absorption of T4* and T3* is low compared with absorption in human subjects. Gentamicin treatment enhanced T3* absorption, but general wasting (weight loss associated with time under study) had no effect on either T4* or T3* absorption. The most important site for absorption of both T4* and T3* is the jejunum-upper ileum bowel segment. However, when the mass of gut wall in each segment is taken into account, absorption rate is highest at the duodenum and decreases distally. Secretion of both T4* and T3* is most active into the duodenum, presumably largely through the bile. In addition, there is active secretion of both T4* and T3* into the ileum and of T4* into the colon. These studies indicate that T4* and T3* absorption and secretion balance to make the gut an important locale for both hormones. Because of the cat's relatively low T4 and T3 absorption rates, much of the gut contents are destined for excretion. However, an active secretion-reabsorption loop for both T4* and T3* is present.

Bedside computers in the surgical intensive care unit.

User "friendly" computers are becoming available for increased usage in the medical arena. The Surgical Intensive Care Unit (SICU) has a large number of items to identify, quantify, manage, and record frequently, often on a continuing basis. At the Palo Alto Veterans Hospital, a program has been developed (A.S.) to change ventilator requirements as an aid to medical staff. Fewer laboratory studies such as blood gas determinations are required. Trending of information is critical in making appropriate plans of care. Twenty patients with a variety of surgical problems have been evaluated by utilizing a bedside computer.

Use of indium-111-labeled autologous leukocytes in differentiating pancreatic abscess from pseudocyst.

Pancreatic abscess is very difficult to diagnose and the differentiate from pancreatic pseudocyst based on clinical findings, laboratory studies and roentgenographic examinations. Eight patients diagnosed as having a pancreatic mass by ultrasonography or computed tomography also underwent indium-111-labeled autologous leukocyte scanning (10 scans) for suspected intraabdominal sepsis. This scan detects migration of labeled leukocytes into abscesses or areas of inflammation. Four patients had abscess and positive scans, and four patients had pseudocyst and negative scans. There was one false-positive scan in a patient with a recurrent pancreatic mass after drainage of an abscess. Since pancreatic abscess requires prompt drainage, and since it may be preferable to delay drainage of a pseudocyst, the differentiation of these two conditions is important. This test appears very effective in diagnosing pancreatic abscess and differentiating it from a pseudocyst.

Canine gastric sling fibers: contractile properties.

The contractile properties of canine sling fibers and the longitudinal and circular muscles were characterized and compared. The longitudinal and circular muscles developed spontaneous contractions, but the sling fibers developed no spontaneous phasic contractions. The cholinergic receptors of all three muscles were excitatory. The alpha- and beta-adrenergic receptors of the longitudinal and circular muscles were inhibitory, but the sling fiber alpha-adrenergic receptors were excitatory and the beta receptors inhibitory. Large concentrations of atrophine induced contractions of all three muscles. Some of the contractile properties of the sling fibers are more similar to those of the distal esophageal circular muscle than to those of the gastric longitudinal and circular muscles. The sling fibers together with the esophageal circular muscle may play an important role in the gastroesophageal sphincter mechanism.

The effects of ischemia on the electrical and contractile activities of the canine small intestine.

The effects of ischemia on the electrical and contractile activites of the small bowel were studied in dogs. Ischemia due to arterial occlusion abolished the contractile activity and made the regular rhythm of the pacesetter potential (PP) irregular. Revascularization within 3 hours restored the contractile activity and the PP rhythm. With longer periods of ischemia, revascularization did not restore contractile activity, and the PP pattern remained irregular or slow.

Electrical, contractile, and radiographic studies of the stomach after proximal gastric vagotomy.

The effects of proximal gastric vagotomy on the gastric electrical and contractile activities and on gastric emptying of solid food were studied in dogs. Proximal gastric vagotomy produced only minimal alteration of the electrical activity and did not significantly alter the response of the electrical and contractile activities to vagal stimulation (insulin) and local stimulation (food). Barium meal studies showed no delay in gastric emptying time after proximal gastric vagotomy but significant delay after truncal vagotomy. The findings support the clinical impression that gastric motility and empyting (solid) remain relatively normal after proximal gastric vagotomy.