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Biomedical subjects

R Nielsen

Publications and source records attributed to R Nielsen.

At least 109 records · Page 6Linked to original sources
PubMed1990

Isotonic secretion via frog skin glands in vitro. Water secretion is coupled to the secretion of sodium ions.

In isolated frog skin at least three different types of cells are engaged in the transepithelial ion and water transport; these are the granular cells, the mitochondria-rich cells and the glandular cells. The experiments presented were carried out on isolated frog skin bathed in Cl- or NO3- Ringer's solution, where the active transepithelial Na+ uptake via the granular cells was blocked by amiloride. Transepithelial current and water flow were measured. When a negative current was passed across the skins (the skins were clamped at -100 mV), the current was mainly carried by a net influx of Cl- via the mitochondria-rich cells. The current had no effect on the transepithelial water movement. This finding indicates that there is nearly no coupling between the Cl- flux and the movement of water via the mitochondria-rich cells. Prostaglandin E2 activates the glandular cells of the exocrine glands in the skin. When prostaglandin E2 was added under these experimental conditions (the skins were clamped at -100 mV, with amiloride in the apical bathing solution, and the glandular secretion of ions was blocked by the use of NO3- Ringer's solution), then the transepithelial current became more negative. This change in current was mainly due to an increase in the Na+ efflux via the glands. Thus PGE2 increase the Na+ conductance of the skin glands. Together with this increase in the Na+ efflux a highly significant increase in the water secretion was observed. The water movement (secretion) across the skin was under these conditions coupled to the PGE2-induced efflux of Na+, and when one Na+ was pulled from the basolateral to the apical solution via this pathway 215 molecules of water followed. This must be due to electro-osmosis (friction between ions and water) or current-induced local osmosis.

Animals↗
PubMed1990

Effect of 12-O-tetradecanoyl phorbol 13-acetate on solute transport and production of cAMP in isolated frog skin.

In the present study we have examined the action of the phorbol diester tetradecanoyl phorbol acetate, an activator of protein kinase C, on the transepithelial transport of sodium, chloride and water and the production of cAMP in the isolated frog skin epithelium (Rana esculenta). Addition of tetradecanoyl phorbol acetate to the mucosal solution resulted initially in an increase in the short-circuit current, which was followed by a progressive decrease. If the short-circuit current was first activated by addition of the antidiuretic hormone, arginine vasotocin, then the addition of tetradecanoyl phorbol acetate resulted only in a pronounced inhibition. The changes in the short-circuit current were the result of changes in the active influx of Na+. The effect of tetradecanoyl phorbol acetate on the intracellular potential measured under short-circuited conditions (Vscc) was time-dependent. Just after addition of tetradecanoyl phorbol acetate to the mucosal solution, Vscc depolarized; this was followed by a slight hyperpolarization, after which Vscc continued to decline. The inhibition of the Na+ transport by tetradecanoyl phorbol acetate was associated with a decline in the response to the antidiuretic hormone (arginine vasotocin), but the ability of arginine vasotocin to increase the cellular level of cAMP and to stimulate the osmotic water flow was not affected by the presence of tetradecanoyl phorbol acetate. In skin halves in which the short-circuit current was stimulated with arginine vasotocin, addition of tetradecanoyl phorbol acetate resulted in a dose-dependent inhibition of the short-circuit current, but only minor changes in Vscc were observed. The results presented suggest that the addition of tetradecanoyl phorbol acetate to the isolated frog skin first increases and then decreases the arginine vasotocin-sensitive sodium permeability of the apical membrane. This might be due to a stimulating effect of tetradecanoyl phorbol acetate on both the activation and deactivation (turnover) of the sodium channels.

Animals↗
PubMed1990

Brown-bowel syndrome. Review of the literature and presentation of cases.

Four cases of brown-bowel syndrome (BBS) are presented. BBS is found in malabsorptive conditions secondary to diseases involving the liver, pancreas, and gastrointestinal tract. Morphologically, BBS is characterized by deposition of lipofuscin in the tunica muscularis, and electron microscopy shows degradation of smooth-muscle cell mitochondria. It is probable that BBS is a manifestation of vitamin E deficiency causing smooth-muscle cell 'mitochondrial myopathy'. Normal bowel function is retained, causing bowel hypotonia, and an aggravation of the underlying disease occurs. On suspicion of BBS, diagnosis is obtained in full-wall biopsy specimens of the intestine.

Aged↗
PubMed1990

Nonoperative treatment of Neer type II distal clavicle fractures: a prospective study.

The first prospective series of nonoperatively treated Neer type II fractures of the lateral third of the clavicle with concomitant rupture of the coracoclavicular ligaments is reported. Among ten patients with an average follow-up of 14.3 months, there were seven healed fractures and three nonunions. None of the three patients with a nonunion desired surgery. Six of the seven patients with healed fractures were satisfied. Eight of the ten patients returned to full activities, although all three patients with nonunions experienced at least occasional discomfort in the affected shoulder. Based on the results in this series of patients, the authors conclude that nonoperative treatment is an effective alternative to surgical management of Neer type II distal clavicle fractures.

Adolescent↗
PubMed1990

New diagnostic techniques: a review of the HAP group of bacteria.

Pasteurella haemolytica, Pasteurella multocida, Haemophilus somnus, Haemophilus parasuis and Actinobacillus pleuropneumoniae cause considerable economic loss in the cattle and swine industries. The literature relating to diagnostic procedures for these infections is reviewed. Both conventional and newer techniques are appraised in relation to the identification and classification of isolates, and to serological testing.

Actinobacillus↗
PubMed1989

Thermal function of a clothing ensemble during work: dependency on inner clothing layer fit.

A tight-fitting crewneck undergarment (U) and a loose-fitting shirt (S) were studied as part of a commonly used clothing ensemble (Itot = 0.22 m2 K W-1). Ten clothed male subjects performed standardized packing work (VO2 = 0.761 min-1) at three climatic conditions, 20 degrees C and Va = 0.45 m s-1 (0-30 min), at 5 degrees C and Va = 0.39 m s-1 (30-60 min) and at 5 degrees C and Va = 1.23 m s-1 (76-90 min). From 60-75 min the subjects rested at 20 degrees C. The physiological and subjective responses varied with the environment from slightly warm to cool. U resulted in warmer responses than S: torso and upper arm skin temperatures were higher at both 5 degrees C and 20 degrees C, evaporation rate was higher at 20 degrees C, mean skin temperature was higher during work at 20 degrees C, sweating tended to begin earlier and skin wettedness to be higher with U than with S. No differences were observed in core temperature, heart rates, and subjective thermal evaluations. It was concluded that a tight-fitting inner layer (U) compared to a loose-fitting one (S) allows for less cooling of the skin in both a cool and a slightly warm environment.

Adult↗
PubMed1989

Effect of thermal conditions on the acceptability of respiratory protective devices on humans at rest.

The physiological and subjective responses of six sedentary subjects wearing half-facepiece respirators were observed over a wide range of room and respirator air conditions. Room air and dew-point (Ta:Tdp) temperatures were 25:11 degrees, 30:13 degrees, and 35:16 degrees C in still air. Respirator air temperatures were maintained independently of room conditions at 27 degrees, 30 degrees, 33 degrees, and 36 degrees C with relative humidity levels of 47% and 73%. Physiological measurements included local skin and dew-point temperatures. Subjective judgments of acceptability, thermal sensation, degree of discomfort, sense of skin moisture, and difficulty of breathing were recorded separately for the thermal environment in the room and inside the respirator. Respirator temperatures cooler than 33 degrees C were always comfortable and 100% acceptable; respirator air temperatures above 33 degrees C or higher humidity levels decreased respirator acceptability. Acceptability of the respirator environment decreased as lip temperature increased above 34.5 degrees C or when respirator dew-point temperature increased above 20 degrees C. Increased respirator air temperature and humidity often made breathing seem "slightly hard." The respirator conditions influenced the subjects' judgment of the acceptability of the surrounding thermal environment.

Adult↗
PubMed1989

Successful fibrin seal closure of a contaminated fistula. Case report.

In a 43-year-old woman, a large, contaminated fistula, initially with vesicointestinal communication, was successfully closed by application of fibrin seal. The course of three sealing attempts indicated that local pretreatment with antibiotics may have been important for the final result. At 4-year follow-up examination there was no recurrence of the fistula.

Adult↗
PubMed1988

Reduction of shoulder dislocations under interscalene brachial blockade.

Even under short sedation, reduction of shoulder dislocations is often difficult, because of the reflectory contraction of the muscles around the humeroglenoidal joint in response to pain. Administration of interscalene brachial blockade produces analgesia and complete relaxation of the muscles of the shoulder joint. We report on ten consecutive shoulder dislocations which were reduced while the patients were under interscalene brachial blockade. In all cases, reduction was easy and free from complications.

Adolescent↗
PubMed1988

Calcium modulates transepithelial potassium secretion across isolated frog skin.

1. Transepithelial K+ movements across isolated frog skin consist of four components: (i) a passive component; (ii) an active inward transport of K+ which occurs via the epithelial cells; (iii + iv) two active outward-directed components, one via the skin glands, the other via the epithelial cells. 2. Incubation of frog skin in gluconate Ringer's solution activates the K+ secretion via the epithelial cells. 3. A decrease in the Ca2+ activity of the epithelial cells increases the K+ permeability of the apical membrane and reduces the K+ permeability of the basolateral membrane.

Animals↗
PubMed1988

Trifluoperazine stimulated sodium transport through the apical surface of isolated frog skin.

When added to the apical solution of isolated frog skin, the calmodulin antagonist trifluoperazine (TFP)* stimulated the short-circuit current (SCC) in a dose-dependent manner. The increase in SCC was due to an enhanced active transepithelial Na transport. After addition of TFP (15 microM) the intracellular voltage depolarized, showing that TFP acts by increasing the sodium (Na) permeability of the apical membrane. The TFP-induced increase in SCC was not accompanied by an increase in prostaglandin E2 release from the skins as observed by basolateral addition of TFP. When the apical Na concentration in fast-flow experiments was changed from 0 to 50 mM, the SCC increased promptly and then reclined. The presence of TFP in the apical solution abolished this recline. The apparent inhibition constant for amiloride changed in the presence of TFP from 1.42 +/- 0.12 microM to 0.38 +/- 0.05 microM (n = II) and TFP abolished the inhibition of SCC caused by high apical Na concentrations. These observations indicate that TFP acts by abolishing the Na self-inhibition of the Na channels. Calmidazolium and chlorpromazine stimulated the SCC to the same degree and in the same concentration range as TFP, suggesting that the effect of TFP was not mediated by the Ca2+-calmodulin complex.

Amiloride↗