Nursing practice and global refugee migration: initial impressions from an Intergovernmental-Academic Partnership.

AIM: This report from the field describes impressions of the initial impact of bilateral, multi-sectoral field-based activities undertaken to strengthen International Organization for Migration/United Nations Migration Agency and US-based nurses' capacity to address complex clinical, social and cultural challenges experienced by refugees in resettlement. Authors comment on the defined and thorough health assessment process that refugees go through prior to resettlement, and focus on the essential nursing role in the health assessment process and continuum of care. The development of the interdisciplinary and collaborative partnership is described as well as next steps to move the partnership forward. BACKGROUND: In 2017, International Organization for Migration/United Nations Migration Agency and the University of Minnesota, guided by experts from the United States Centers for Disease Control and Prevention, began a unique bilateral Intergovernmental-Academic partnership to enhance the health care of refugees. A key component was to strengthen nursing care of refugees through the standardization of clinical practice and nursing leadership. SOURCES OF EVIDENCE: Listening sessions, direct interaction between International Organization for Migration/United Nations Migration Agency and US-based refugee resettlement stakeholders, patterns in resettlement. CONCLUSION AND IMPLICATIONS FOR NURSING AND HEALTH POLICY: The report highlights the potential public health impact of a bilateral and collaborative initiative that develops and bridges key points in the migration and health trajectory of people with refugee status. Separated by geography, context and scope of work, health professionals in different roles in varied worldwide settings with a spectrum of resources may not fully understand the work of each other. Project activities were a platform through which US-based and internationally based nurses established mutuality, reciprocity and equity as partners. By strengthening systems and resources, the partnership reinforces the abilities of nurses who engage in this important work, to optimize health and wellbeing of people with refugee status.

Inertial cavitation threshold of nested microbubbles.

Cavitation of ultrasound contrast agents (UCAs) promotes both beneficial and detrimental bioeffects in vivo (Radhakrishnan et al., 2013) [1]. The ability to determine the inertial cavitation threshold of UCA microbubbles has potential application in contrast imaging, development of therapeutic agents, and evaluation of localized effects on the body (Ammi et al., 2006) [2]. This study evaluates a novel UCA and its inertial cavitation behavior as determined by a home built cavitation detection system. Two 2.25 MHz transducers are placed at a 90° angle to one another where one transducer is driven by a high voltage pulser and the other transducer receives the signal from the oscillating microbubble. The sample chamber is placed in the overlap of the focal region of the two transducers where the microbubbles are exposed to a pulser signal consisting of 600 pulse trains per experiment at a pulse repetition frequency of 5 Hz where each train has four pulses of four cycles. The formulation being analyzed is comprised of an SF6 microbubble coated by a DSPC PEG-3000 monolayer nested within a poly-lactic acid (PLA) spherical shell. The effect of varying shell diameters and microbubble concentration on cavitation threshold profile for peak negative pressures ranging from 50 kPa to 2 MPa are presented and discussed in this paper. The nesting shell decreases inertial cavitation events from 97.96% for an un-nested microbubble to 19.09% for the same microbubbles nested within a 2.53 µm shell. As shell diameter decreases, the percentage of inertially cavitating microbubbles also decreases. For nesting formulations with average outer capsule diameters of 20.52, 14.95, 9.95, 5.55, 2.53, and 1.95 µm, the percentage of sample destroyed at 1 MPa was 51.02, 38.94, 33.25, 25.27, 19.09, and 5.37% respectively.

Respiratory and heart rate responses to tethered controlled frequency breathing swimming.

The purpose of this study was to investigate the respiratory and heart rate (fH) responses to tethered controlled frequency breathing (CFB) swimming. Controlled frequency breathing swimming is an aquatic training technique in which ventilatory rate is voluntarily reduced in order to induce systemic hypoxia during training. Nine elite college swimmers experienced with CFB were studied. The tethered swimming tests were discontinuous, with 4 min work bouts interspersed with equal duration rest periods. The resisting forces during tethered swimming were 5.63, 6.82, and 7.95 kg. Each subject was tested breathing every two (control), three, four, and five arm strokes. Subjects performed all four breathing frequencies at a constant arm stroke rate of 30/min during freestyle swimming. As ventilatory volume decreased due to CFB, O2 extraction and estimated tidal volume significantly increased (P less than .05) to maintain a constant O2 consumption for a given workload. Carbon dioxide production, respiratory exchange ratio, and fH did not change significantly in response to CFB. Estimated alveolar partial pressure of O2 (PAO2) decreased and PACO2 increased significantly during CFB. However, estimated saturation of arterial blood with O2 (SAO2) was essentially undiminished during CFB. These responses do not indicate hypoxia, but rather hypercapnia during CFB.

Influence of nesting shell size on brightness longevity and resistance to ultrasound-induced dissolution during enhanced B-mode contrast imaging.

This study aims to bridge the gap between transport mechanisms of an improved ultrasound contrast agent (UCA) and its resulting behavior in a clinical imaging study. Phospholipid-shelled microbubbles nested within the aqueous core of a polymer microcapsule are examined for their use and feasibility as an improved UCA. The nested formulation provides contrast comparable to traditional formulations, specifically an SF6 microbubble coated by a DSPC PEG-3000 monolayer, with the advantage that contrast persists at least nine times longer in a mock clinical, in vitro setting. The effectiveness of the sample was measured using a contrast ratio in units of decibels (dB) which compares the brightness of the nested microbubbles to a reference value of a phantom tissue mimic. During a 40min imaging study, six nesting formulations with average outer capsule diameters of 1.95, 2.53, 5.55, 9.95, 14.95, and 20.51µm reached final contrast ratio values of 0.25, 2.35, 3.68, 4.51, 5.93, and 8.00dB, respectively. The starting contrast ratio in each case was approximately 8dB and accounts for the brightness attributed to the nesting shell. As compared with empty microcapsules (no microbubbles nested within), enhancement of the initial contrast ratio increased systematically with decreasing microcapsule size. The time required to reach a steady state in the temporal contrast ratio profile also varied with microcapsule diameter and was found to be 420s for each of the four smallest shell diameters and 210s and 150s, respectively, for the largest two shell diameters. All nested formulations were longer-lived and gave higher final contrast ratios than a control sample comprising un-nested, but otherwise equivalent, microbubbles. Specifically, the contrast ratio of the un-nested microbubbles decreased to a negative value after 4min of continuous ultrasound exposure with complete disappearance of the microbubbles after 15min whereas all nested formulations maintained positive contrast ratio values for the duration of the 40min trial. The results are consistent with two distinct stages of gas transport: in the first stage, passive diffusion occurs under ambient conditions across the microbubble monolayer within the first few minutes after formulation until the aqueous interior of the microcapsule is saturated with gas; in the second stage ultrasound drives additional gas dissolution even further due to pressure modulation. It is important to understand the chemistry and transport mechanisms of this contrast agent under the influence of ultrasound to attain better perspicacity for enhanced applications in imaging. Results from this study will facilitate future preclinical studies and clinical applications of nested microbubbles for therapeutic and diagnostic imaging.

Optical design of the atacama cosmology telescope and the millimeter bolometric array camera.

The Atacama Cosmology Telescope is a 6 m telescope designed to map the cosmic microwave background simultaneously at 145, 215, and 280 GHz with arcminute resolution. Each frequency will have a 32 by 32 element focal plane array of transition edge sensor bolometers. The telescope and the cold reimaging optics are optimized for millimeter-wave observations with these sensitive detectors. The design of each is described.

Release of vasopressin and oxytocin from isolated pituitary glands of adult and new-born rats.

1. Pituitary glands of adult rats of both sexes, of lactating female and of new-born rats, incubated in a Locke solution, release both oxytocin and vasopressin. The amount of hormones released, during a measured period of incubation, is related to the actual hormone content of the gland.2. Increasing the concentration of KCl in the incubation medium, with CaCl(2) present and in concentration of at least 2.2 mM, produces an enhanced release of both hormones from pituitary glands of adults, but does not affect the release of hormones from glands of new-born animals.3. Addition of ouabain to the incubation medium produces a marked increase of the release of the hormones from glands of both adult and new-born rats. This is accompanied by an extrusion of K ion and an influx of Na ion. The effect of ouabain on the hormone release and the shift of ions can be reversed by subsequent addition of adenosine triphosphate.4. The increased release of hormones produced by ouabain, in glands from new-born rats, is unaffected by the presence or absence of CaCl(2). In adults, however, the effect of ouabain, though present, is reduced in the absence of CaCl(2).5. It is suggested that in glands from adult animals, the hormones must be freed from their attachment on the protein-carrier, neurophysin and that this can be achieved by the entry of calcium ion into the cell. The subsequent secretion of the ;freed' hormones appears to be accompanied by a shift of ions across the cell membrane.6. In glands from neonates up to 3 weeks old, the absence of neurophysin, or its poor capacity for binding the hormones, explains the inability of calcium to operate in the same way as in the glands of adults. There is evidence suggesting that the secretion of the neurohypophysial hormones in the new-born animal consists mainly of their diffusion from the cells, without previous elution of the hormones as in adults.

Inhibition of compensatory renal growth in rats.

1. Compensatory renal hypertrophy in unilaterally nephrectomized rats was measured by estimation of dry weight, protein content, RNA and DNA changes and rate of oxygen consumption. Inulin clearances (= GFR) and water and solute excretions were estimated in animals given by stomach tube either 5 ml. water or 5 ml. 0.6% NaCl solution/100 g body wt.2. Kidneys removed when animals were unilaterally nephrectomized were homogenized in 0.25 M sucrose and fractions containing mitochondria or microsomes were obtained by centrifugation. Renal cortex and medulla were similarly treated.3. Intraperitoneal injections of microsomes and/or supernatant fluid from a kidney homogenate or from the renal cortex usually inhibited compensatory growth of the contralateral kidney and prevented any increase of its protein content.4. Injections of microsomes and/or supernatant fluid from the renal medulla had no significant effect on the rate of compensatory hypertrophy.5. After I.P. injection of microsomes and supernatant fluid from a homogenate from the renal cortex there was no rise of the RNA/DNA ratio in the contralateral kidney and the rate of oxygen uptake of its cortex decreased, while that of anaerobic glycolysis increased.6. Injections of microsomes and supernatant fluid from kidney homogenate did not affect glomerular filtration rate which increased as in control unilaterally nephrectomized rats.7. In unilaterally nephrectomized rats, injected with microsomes and supernatant fluid from a kidney homogenate, there was a decrease of osmolal clearance, in spite of the raised glomerular filtration rate. The decrease of osmolal clearance lasted for several days, and was most pronounced when the animals had been given by stomach tube 5 ml. 0.6% NaCl solution/100 g body wt.

Water uptake by Bufo melanostictus, as affected by osmotic gradients, vasopressin and temperature.

1. The rate of water uptake across the skin was studied in the live toad, Bufo melanostictus. When toads were kept in distilled water at 29 degrees C the uptake of water amounted to 16.9 +/- 1.3 mul./cm(2)/hr; when bathed in sucrose or urea solutions, the water uptake diminished with increasing osmotic pressure. There was no water uptake observed when toads were kept in 200 m-osmolar sucrose or urea.2. Intramuscular injections of vasopressin increased the rate of water uptake from distilled water. There was a good relation between doses and responses over various time intervals. A dose of 4 m-u. vasopressin/g body wt. doubled the rate of water uptake over a period of 1 hr. The same dose of vasopressin doubled the rate of water uptake when the toads were kept in solutions of sucrose or urea of different osmolarity.3. The rate of water uptake when the toads were bathed in sodium chloride solutions was consistently 8 mul./cm(2)/hr greater than when bathed in sucrose or urea solutions of equal osmolarity. There was no water uptake when the sodium chloride solution was 285 m-osmolar.4. Vasopressin (4 m-u./g) injected intramuscularly doubled the rate of water uptake from sodium chloride solutions of different osmolarity.5. With solutions of potassium chloride, sodium nitrate, and potassium nitrate, in concentrations up to 150 m-osmoles/l., the rate of water uptake was found to be the same as with solutions of sodium chloride of the same osmolarity. Similarly, it was doubled by injection of vasopressin (4m-u./g).6. The effect of temperature on the rate of water uptake before and after injection of vasopressin was investigated in toads kept in distilled water, sucrose, or sodium chloride solutions. For temperatures between 20 and 37 degrees C, vasopressin (4 m-u./g) reduced the activation energy involved in the process of water uptake by 4000 cal.7. The results agree with the view that water uptake follows a diffusion process which is facilitated by vasopressin, possibly as a result of increasing the size or number of available pores.

Compensatory renal growth after unilateral nephrectomy in the new-born rat.

1. The right kidney in a series of control rats aged between 5 days and 115 days was weighed. The kidney weight/body weight ratio was greater in young than in older rats, but decreased linearly with increasing age.2. After unilateral nephrectomy of rats 5 days old, the remaining kidney underwent compensatory growth. The rate and extent of this growth were greater than in adult rats.3. The concentrations of RNA and DNA in the renal cortex and medulla of rats 5 days old were higher than in adult animals. The concentrations of the two nucleic acids fell with age, and reached adult levels after approximately 6 weeks.4. After unilateral nephrectomy of rats 5 days old, the concentrations of RNA and DNA in the medulla were not significantly different from those in control animals. In the cortex, however, there was a delayed increase in the RNA/DNA ratio, which reached a level some 12% higher than that in control rats. This increase was smaller than that observed in unilaterally nephrectomized adult rats.5. The cortical Q(O2) of the remaining kidney of unilaterally nephrectomized new-born rats was elevated by some 20% within 1 day of unilateral nephrectomy. Cortical Q(O2)'s remained higher than those of control animals for 3-4 weeks.6. Since after unilateral nephrectomy, the increase in renal mass in new-borns was greater than that in adults, whereas the degree of cortical cellular hypertrophy (as estimated by the RNA/DNA ratio) was smaller than in adults, it is likely that in new-born animals a significant contribution to compensatory growth comes from cellular hyperplasia.

Rates of oxygen consumption and of anaerobic glycolysis in renal cortex and medulla of adult and new-born rats and guinea-pigs.

1. Rates of oxygen uptake and of anaerobic glycolysis were estimated in slices from the renal cortex and medulla (a) of adult rats and guinea-pigs, (b) of new-born (1-, 5- and 21-day-old) rats and of guinea-pigs of 1, 12, 21, 24 and 120 hr age.2. In the adult rat, Q(O2) values for the cortex were 12.55 +/- 0.20 (22) and for the medulla: 8.56 +/- 0.17 (22) mul./hr.mg dry weight, while in the new-born rat (24 hr old) they were 10.99 +/- 0.46 (12) and 9.33 +/- 0.18 (9) mul./hr.mg dry weight respectively.3. Values for Q(CO2) (N2) (anaerobic glycolysis) in the 14 hr old new-born rat were in the renal cortex 9.65 +/- 0.35 (5) and in the medulla 7.39 +/- 0.43 (5) mul./hr.mg dry weight; while in the adult they were 2.25 +/- 0.08 (16) and 5.76 +/- 0.14 (16) mul./hr.mg dry weight, respectively.4. In the adult guinea-pig values for Q(CO2) (N2) were of the same order as in the adult rat, though the rate of O(2) uptake was for the cortex 8.12 +/- 0.22 (12) and for the medulla 5.02 +/- 0.23 (11) mul./hr.mg dry weight.5. Though the Q(O2) values in the renal cortex and medulla were smaller in the 1 hr old new-born guinea-pig, they were already increasing in the 12 hr old neonate.6. The results are discussed in the light of enzyme changes occurring during the process of maturation of the nephron as indicated by histochemical observations.

Mechanism of compensatory renal hypertrophy.

1. Adult rats were unilaterally nephrectomized and the weight of the remaining kidney up to 42 days after the operation compared with that of rats of comparable weight which underwent a sham operation.2. After unilateral nephrectomy the rate of renal hypertrophy varied with the protein content of the diet: it was faster when animals were fed on a high protein diet (22% casein) and lowest in animals fed on a low protein diet (7% casein).3. In rats fed on a standard diet (18% casein), after unilateral nephrectomy there was a sharp increase in glomerular filtration rate (G.F.R.), as measured by inulin clearance estimations; this was accompanied by an enhanced oxygen uptake and by an increase of RNA/DNA ratios in the renal cortex. Changes in rate of oxygen uptake and of RNA/DNA ratios in the medulla were negligible.4. A marked increase in mitotic activity of cells of the cortex occurred only 48 hr after the operation. It lasted for about 2 days. No significant changes in mitotic activity of cells in the medulla were observed.5. After its initial marked rise glomerular filtration rate in the renoprival kidney settled down to about 30-40% above its pre-operative level, and remained at that level for the whole period of observation (6 weeks), while the increase of oxygen uptake returned to its control level in some 10-14 days. RNA/DNA ratios in the cortex remained high, but did not increase further.6. The increase of RNA/DNA ratios in the renal cortex was correlated with a steady increase in the dry weight of the renoprival kidney.7. Water and solutes excretion were restored to normal in about 3-5 days after the operation.8. Though the increase in glomerular filtration rate may be the prime mover in the mechanism of compensatory renal hypertrophy, it does not explain why there is an increase in the size of tubules.

The isolation of hyaluronic acid and chondroitin sulphate from kidneys and their reaction with urinary hyaluronidase.

1. Extracts of the cortex and the medulla of fresh kidneys from pigs, sheep and dogs were analysed for the presence of acid mucopolysaccharides.2. Acid mucopolysaccharides were found in the kidneys of the three species and were evenly distributed between cortex and medulla.3. The acid mucopolysaccharides isolated from either the medulla or the cortex of kidneys contained equal amounts of sulphated and nonsulphated fractions; these could be identified as chondroitin sulphate and hyaluronic acid, respectively.4. Urinary hyaluronidase was isolated from urine and estimated by means of turbidity measurements.5. Urine hyaluronidase depolymerizes the acid mucopolysaccharides extracted from either the cortex or the medulla of the kidneys from pig, sheep and dog.6. The enzymic activity of urine hyaluronidase could be expressed as units/mg of protein. The optimum pH activity of the enzyme is at about 4.0.

Water diuresis in the domestic fowl.

1. The exteriorization of ureters in domestic fowls allows the collection of urine uncontaminated by faeces.2. When water is administered by stomach tube to a fowl, water is stored in the crop, from which it is slowly released into the proventriculus.3. Immediately after water gavage, there is a sharp rise of urine flow accompanied by an increase in endogenous creatinine excretion and a fall in the osmolarity of the urine. This initial increase in urine flow is of short duration, and is followed by a normal curve of diuresis with a peak at about 90 min after hydration.4. The first rise in urine flow following the filling of the crop appears to be of reflex origin, as distension of the crop with paraffin produces an enhanced excretion of urine and of creatinine.5. Changes in urine flow and in creatinine excretion are closely correlated.6. After water deprivation for 18 hr, the urine is slightly hyptertonic to blood. The maximum urine concentration observed was of the order of 600 m-osmole/l.

Changes in renal cyclic nucleotide content as a possible trigger to the initiation of compensatory renal hypertrophy in rats.

1. Cyclic adenosine 3', 5'-monophosphate (cyclic AMP) and cyclic guanosine 3', 5'-monophosphate (cyclic GMP) have been estimated in the kidneys of rats.2. Ten minutes after unilateral nephrectomy there was a threefold increase of cyclic GMP in the remaining kidney, which was accompanied by a moderate fall of cyclic AMP.3. The changes in cyclic nucleotides in the remaining kidney after unilateral nephrectomy were of short duration.4. When an anephric rat was cross-circulated with a normal litter-mate, there was an increase of cyclic GMP concentration in the kidneys of the latter, which reached its maximum 10 min after the establishment of the cross circulation.5. In experiments where one kidney of a litter-mate was transplanted to the neck of another rat, unilateral nephrectomy was not followed by changes of the level of cyclic nucleotides in either the transplanted or the remaining kidney. Bilateral nephrectomy, however, resulted in a marked increase of cyclic GMP in the transplanted kidney.6. The clamping of the blood vessels to one kidney for periods up to 10 min had the same effect as unilateral nephrectomy on the concentration of cyclic GMP in the remaining kidney. When the clamp was removed and the circulation restored, the concentrations of cyclic nucleotides returned to preoperative levels in both kidneys.

Effects of exteriorization of the ureters on the water metabolism of the domestic fowl.

1. Six domestic fowls were operated for exteriorization of the ureters.2. Three weeks after the operation their food and water intake was compared with that of six unoperated control fowls of similar weight.3. Water intake was calculated from the amount of water drunk, the metabolic water and the water content of the food eaten; while water loss was estimated from the water content of urine and faeces excreted and from evaporation.4. Fowls with exteriorized ureters drank more than the control birds. The excess of water drunk by these birds approximated the amount of water lost in the urine.

Absence of compensatory renal hypertrophy in baboons.

1. The weights of kidneys of fifteen adolescent and forty-six adult male baboons were estimated. In contrast with what has been described in other mammals, in the majority of baboons (thirty-nine out of fifty-seven) the left kidney was heavier than the right.2. The medulla/cortex ratio was of the order of 1.8. The maximum urinary concentration, after 36 hr of food and water deprivation, averaged 1050 +/- 80 m-osmole/kg H(2)O.3. Unilateral nephrectomy was performed in twelve baboons with body weight ranging from 5 to 14 kg. In six animals, the left kidney was removed and the right kidney in the others.4. In two baboons, the left kidney was transplanted to the left iliac artery and vein, the ureters being left intact. After a few weeks, the right kidney was taken out, and the animals were kept under observation, one for a further 3 months and the other for a further 4 months.5. In none of the animals, whether after simple unilateral nephrectomy or after unilateral nephrectomy following transplant of one kidney, did the renoprival kidney show any significant enlargement.6. After unilateral nephrectomy, the health of the animals remained excellent, all the baboons increasing in body weight. The ability to concentrate urine by the renoprival kidney was not impaired.7. In contrast with what has been described in mice and rats, in unilaterally nephrectomized baboons no significant changes in the concentration of either RNA or DNA in renal cortex and medulla of the contralateral kidney were observed.8. After unilateral nephrectomy in baboons, there was a marked increase of oxygen uptake in slices from the cortex, but not from the medulla. In contrast with what had been observed in rats where the enhanced rate of oxygen uptake returned to pre-operative values, in baboons no decrease was observed, the rate of oxygen uptake remaining high during the whole period of observation.9. In the limit of time of observation (maximum 4 months) there was no evidence that unilateral nephrectomy resulted in compensatory hypertrophy of the contralateral kidney.

Compensatory hypertrophy of the contralateral kidney after unilateral ureteral ligation.

1. The ligation of one ureter is accompanied by compensatory hypertrophy of the contralateral kidney.2. The rate of growth of the contralateral kidney after ligation of the opposite ureter is similar to that observed after unilateral nephrectomy.3. Ligation of one ureter produced ipsilateral hydronephrosis.4. The development of hydronephrosis was accompanied by a marked increase of DNA, suggesting hyperplasia, and of the rate of anaerobic glycolysis, while the rate of oxygen uptake decreased, especially in the cortex.5. During compensatory hypertrophy of the contralateral kidney, after ligation of the opposite ureter, there were increases of RNA/DNA ratios and of oxygen uptake, especially marked in the cortex, and in every respect similar to those observed after unilateral nephrectomy.6. Ligation of one ureter resulted in an increase of glomerular filtration rate of the contralateral kidney similar to that observed after unilateral nephrectomy.7. The mechanisms of contralateral renal hypertrophy after ligation of one ureter and after unilateral nephrectomy are discussed. It is suggested that in both cases the prime mover to compensatory hypertrophy is the increase of glomerular filtration rate.

Water uptake by the crab-eating frog Rana cancrivora, as affected by osmotic gradients and by neurohypophysial hormones.

1. The rate of water uptake across the skin was investigated in live Rana cancrivora, an euryhaline frog which has been reported to tolerate sea water. When they were exposed to distilled water at 29 degrees C, the rate of water uptake was 8.4 +/- 0.4 mul./cm(2).hr; when bathed in solutions ranging from 30 to 570 m-osmole/l., irrespective of whether the solute was sucrose, urea or NaCl, the rate of fluid uptake during the first day was inversely related to the osmolarity of the solution. No appreciable fluid movement was observed when the bathing solution had an osmolar concentration of 270 m-osmole/l.2. The rate of fluid uptake was not affected by injections of vasopressin, oxytocin or of extracts of amphibian or rat pituitary glands, irrespective of whether R. cancrivora were bathed in distilled water or in solutions of NaCl or sucrose.3. In Bufo melanostictus, in contrast with R. cancrivora, injections of neurohypophysial extracts produced a marked increase of the rate of fluid uptake.4. In the laboratory, R. cancrivora could be acclimatized stepwise to tolerate NaCl solutions up to 700 m-osmole/l. for 7 days.5. After 24 hr exposure either to distilled water or to NaCl solutions from 100 to 670 m-osmole/l., the osmolar concentration of the plasma of R. cancrivora was always higher than that of the bathing fluid. In R. pipiens or R. temporaria plasma osmolar concentration was higher than that of the bathing fluid only when the latter did not exceed 300 m-osmole/l.6. Under all conditions investigated, the osmolar concentration of the urine of R. cancrivora was always lower than that of the plasma.7. The amounts of pressor and oxytocic activities of pituitary glands of R. cancrivora kept in distilled water or in NaCl solutions up to 300 m-osmole/l. were 8.9 +/- 0.8 and 1.8 +/- 0.3 m-u./gland, irrespective of sex or body weight within the range 30-50 g. After 3 days exposure to hypertonic NaCl solutions, the amounts of pressor and oxytocic activities were 14.7 +/- 1.2 and 3.1 +/- 0.3 m-u./gland. In both instances the pressor/oxytocic ratio was 4.9. Pituitary glands of R. temporaria similarly showed increased pressor and oxytocic activities after exposure to NaCl solutions of 300-360 m-osmole/l.

Effect of neurohypophysial hormones on fluid movement across isolated bladder of Rana cancrivora, Rana temporaria and Bufo melanostictus.

1. The rate of fluid movement across the wall of isolated amphibian urinary bladder was estimated using hemi-bladders of the tropical euryhaline Rana cancrivora, the temperate R. temporaria and the tropical Bufo melanostictus.2. The rate of water outflow across the bladder walls was: Rana cancrivora, 4.8 mul./cm(2).hr; R. temporaria, 7.2 mul./cm(2).hr; Bufo melanostictus, 3.7 mul./cm(2).hr.3. When neurohypophysial peptides were added to the serosal solution the rates of water outflow were increased; dose-response curves were prepared relating the augmented rate of fluid movement to the concentration in the bathing fluid of vasopressin, oxytocin or vasotocin.4. The potencies of the peptides in respect of bladders of each species were:Vasopressin, B. melanostictus:Rana temporaria:R. cancrivora, 500:20:1.Oxytocin, R. temporaria:B. melanostictus:Rana cancrivora, 100:5:1.5. The ratio of sensitivity of the bladder of each species to the presence of the different peptides was:R. cancrivora, vasotocin:oxytocin:vasopressin, 1000:5:1.R. temporaria, oxytocin:vasopressin, 15:1. Bufo melanostictus, oxytocin:vasopressin, 1:30.6. The effect of extract of the pituitary gland of Rana cancrivora was examined on R. cancrivora bladder. It had a dose-response curve similar to the dose-response curve of vasotocin.7. The vasotocin content of the pituitary gland of R. cancrivora was estimated(a) from the dose-response curves using R. cancrivora bladder,(b) by a three-point assay using R. cancrivora bladder and(c) by its effect on water uptake across the skin of Bufo melanostictus. One pituitary gland of Rana cancrivora was found to contain about 0.1 mug vasotocin.8. The urinary bladder of R. cancrivora was less responsive to neurohypophysial peptides than the bladder of R. temporaria or Bufo melanostictus.9. The hormonal content of the pituitary gland of Rana cancrivora was smaller than that found in other amphibians.