Biomedical subjects

O Broberger

Publications and source records attributed to O Broberger.

At least 37 records · Page 2Linked to original sources

PubMed1979

Sodium excretion in relation to sodium intake and aldosterone excretion in newborn pre-term and full-term infants.

The importance of aldosterone for the control of salt balance has been examined in pre-term infants (gestational age 28--34 weeks) and in full-term infants. The post-natal age has varied from 2--21 days. Eight-hour urinary specimens have been analysed with regard to sodium, potassium and aldosterone. The daily sodium intake has been recorded following determination of milk intake and analyses of sodium in breast milk. Due to variations of sodium content of breast milk, the daily sodium intake in pre-term infants was lower than in full-term infants during the first 10 days of life. The sodium excretion was significantly higher in pre-term infants than in full-term infants during the first six days of life. During the first week of life the sodium balance is negative in pre-term infants and positive in full-term infants. Aldosterone excretion is high during the first week of life and increases further from the 2nd to the 3rd week of life in both pre-term and full-term infants. The correlation between aldosterone excretion and urinary potassium/sodium quotient is 0.87 in full-term infants, 0.57 in pre-term infants aged 13--20 days and does not exist in pre-term infants aged 2--10 days. It is suggested that the high sodium excretion in newborn pre-term infants can in part be explained by an unresponsiveness to aldosterone at this developmental stage.

Aldosterone↗

PubMed1979

Studies of renal urea cycle enzymes. I. Renal concentrating ability and urea cycle enzymes in the rat during protein deprivation.

Activities of renal urea enzymes were studied in normally fed (21% dietary protein) rats and rats deprived of protein (6% dietary protein) for 3 weeks. Protein deprivation resulted in growth retardation and defective urine concentrating ability. Compared to rats on an optimal diet containing 21% of protein, the protein starved animals had decreased concentrations of protein and urea in serum, reduced urinary excretion of urea and decreased levels of all five urea cycle enzyme activities in the liver. In the kidney, however, protein malnutrition resulted in a significant increase in arginase specific activity from 11.5 +/- 1.1 to 16.3 +/- 1.5 (M +/- SD) whereas the other urea cycle enzymes remained unchanged. It is postulated that this increase in renal arginase might be an early compensatory mechanism to preserve a net synthesis of urea in a situation involving arginine deficiency, thereby preserving an intact hypertonic gradient in the renal medulla.

Animals↗

PubMed1979

Studies of renal urea cycle enzymes. II. Human renal arginase activity and location of the adaptive changes of renal arginase in the protein deprived rat.

Rats fed 6% protein for 3 weeks with growth retardation and urinary concentration defect had 3 times higher arginase activity in the kidney cortex (10.8 +/- 28, M +/- SD) compared with controls fed 21% protein (3.3 +/- 0.9, M +/- SD). In the outer medulla there was a 50% increase of arginase activity whereas no change was observed in the inner medulla and papilla. Arginase activity in fresh human cortical tissue was of the same magnitude as in the rat. The results are in agreement with the hypothesis that intrarenal urea synthesis contributes to the maintenance of the intrarenal urea gradient in the protein deprived state. The response in the protein deprived rat might thus be an adaptation to a situation with substrate deficiency.

Adaptation, Physiological↗

PubMed1979

Vesicoureteric reflux and pyelonephritis. Long time effect on area of renal parenchyma.

The effect of gross vesicoureteric reflux in combination with urinary tract infection on the area of the renal parenchyma was analysed in 8, non-selected, girls during 3 to 6 years. A progressive significant decrease of the relative size of the kidneys with vesicoureteric reflux occurred as compared with that of kidneys with normal ureters. The decrease was mainly due to scars in the upper and lower poles. A positive correlation was found between the reduction of parenchyma and the number of episodes of pyelonephritis.

Adolescent↗

PubMed1978

Renal function in anorexia nervosa.

Renal function was examined in twelve patients, eight girls and four boys, with anorexia nervosa (AN) ranging in age from 12.6 to 18.2 years. The weight loss at the time of the study averaged 26%. Determinations were made of glomerular filtration rate (GFR), PAH clearance (CPAH) and urinary concentrating capacity. For references the same studies were also carried out in five healthy teenagers. Both GFR and CPAH were generally CPAH as shown by a significantly lower filtration fraction (FF) in AN. Indirect evidence suggests that the low FF could be attributed to reduced water permeability of the glomerular capillary. The urinary concentrating capacity following fluid deprivation was moderately depressed both before and after the administration of vasopressin. The concentrating defect in AN must therefore be primary of renal origin.

Adolescent↗

PubMed1978

Renal functional adaptation in the remnant kidney in patients with renal agenesis and in patients nephrectomized in childhood.

The renal response to volume expansion was determined in four patients with renal hypertrophy due to unilateral renal agenesis (URA) and in four patients with renal hypertrophy due to nephrectomy (Nz). Four healthy controls were also studied. The studies were performed during water diuresis and following i.v. infusion of isotonic saline solution. Conventional clearance techniques were used. GFR and PAH clearence were increased to about the same extent in Nz and in URA. Fractional Na+ excretion was highest in the Nz group and lowest in the control group. It was higher in the Nz group than in the URA group. Fractional water excretion (V/GFR) and free water clearance (CH2O) were also determined and the results indicate that the high fractional excretion of Na+ from the hypertrophied kidney can be attributed to reduced fractional reabsorption of filtrated Na+ both in the proximal and the distal tubules. The fractional Na+ reabsorption in the distal tubule appears to be higher in URA than in Nz. It is concluded that glomerular tubular balance for Na+ is more similar to that found in healthy controls if the stimulus to hypertrophy occurs prenatally than if it occurs postnatally.

Adaptation, Physiological↗

PubMed1978

Relationship between area and function of the kidney in well defined childhood nephropathies.

Length, parenchymal area planimetrically determined and volume of the kidney were estimated at urography and related to glomerular filtration rate in patients with different nephropathies. The results demonstrate that the size of the kidney is an excellent index of renal function in patients with pyelonephritic scarring secondary to urinary tract infection and vesicoureteral reflux. It is also a good index in patients with obstructive hydronephrosis but a poor index in patients with glomerulonephritis.

Adolescent↗

PubMed1977

Renal growth and function in patients nephrectomized in childhood.

Eight patients nephrectomized in childhood were studied with regard to growth and function of the remaining kidney. The age of the patients ranged between 8 1/2 and 31 years and the follow-up period was from 1 to 20 years. In most of the patients, repeated renal size determinations were made on postoperative urograms. Normal values for kidney size in childhood are also presented. The structural hypertrophy continued for at least three years after nephrectomy and was most pronounced in patients nephrectomized before three years of age. When more than three years had passed after nephrectomy the remaining kidney was 35-65% larger than normal. Healthy young adults and children with a previous history of urinary tract infection served as controls for function studies. The balance between glomerular and tubular function was well preserved in nephrectomized patients. The renal surface area showed the same relation to GFR and to reabsorption of bicarbonate in nephrectomized patients as in controls. It is therefore concluded that the increase in kidney function following unilateral nephrectomy is, at least in early life, primarily due to structural enlargement.

Adolescent↗

PubMed1977

Renal hemodynamics in the perinatal period. A study in lambs.

The perinatal changes in renal hemodynamics have been studied in lambs. Eleven of the lambs were exteriorized, but maintained on placental circulation (fetal lambs). Eight of the lambs were delivered with cesarean section and studied immediately after clamping of the cord (newborn lambs). Nine lambs were delivered spontaneously and studied during the first 9 days of life. Renal blood flow (RBF) was determined by the microsphere method using a sample drawn from the iliac artery as the reference flow. The filtering capacity of the nephrons was evaluated after ferrocyanide injection and dissection of the nephrons. Total RBF did not seem to change much at birth but increased in relation to kidney weight during the first postnatal week. Clamping of the cord did, however, result in a change in intrarenal blood flow distribution, so that in the newborn lambs relatively more of the blood flow was perfusing the outer cortical region. During the first postnatal week there was a slight, but insignificant further relative increase in outer cortical blood flow. The relative increase in outer cortical blood flow at birth was accompanied by an increased frequency of filtering superficial nephrons from 22 to 77%. Practically all juxtamedullary nephrons were filtering before birth. Three days postnatally 98% of the superficial and 100% of the juxtamedullary nephrons were filtering.

Animals↗

PubMed1977

A comparative study of the response to an oral NaCl and NaHCO3 load in newborn preterm and full term infants.

Previous recommendations on salt tolerance of newborn infants have mainly been based on knowledge of the capacity of newborn infants to excrete NaCl. Since tolerance to NaHCO3 can hardly be predicted from knowledge of tolerance of NaCl, a comparative study of Na+ excretion following equivalent doses of NaCl and NaHCO3 has been carried out. Forty-nine full term infants aged 0-2 days and 3-7 days were given either an oral load of NaCl or NaHCO3. Ten preterm infants (gestational age 30-35 weeks, postnatal age 2-18 days) were given both NaCl and NaHCO3 after a 2-day interval. The average urinary Na+ excretion 1-5 hr after the load was higher in all full term infants studied, but the difference was significant only in 3-to 7-day-old infants. In 7 of the 10 preterm infants the urinary Na+ excretion was higher following the NaHCO3 load than following the NaCl load. The mean difference between the tests averaged 1 mmol Na+/1.73 m2/hr and was significant. A somewhat higher daily allowance of NaHCO3 (15 mmol/kg/24 hr) than of NaCl (12 mmol/kg/24 hr) is therefore recommended.

Aging↗

PubMed1976

Effect of vesicoureteral reflux on renal function in children with recurrent urinary tract infection.s.

The functional damage caused by vesicoureteral reflux (VUR) has been examined by unilateral clearance studies in 22 children with recurrent urinary tract infection (UTI) and representing 23 kidneys with large VUR. 7 kidneys with small to moderate VUR and 14 kidneys without VUR. Inulin clearance, Na+ excretion and glucose reabsorption were determined. In kidneys without or with small and moderate VUR, UTI had no effect on renal function if treated. In kidneys with large VUR extending into the pelvis and dilating the ureter, there was a gradual deterioration of glomerular filtration rate (GFR) that was accelerated after the age of 6 yr. Before puberty more than 50% of renal function was lost despite strict medical care of the UTI. If this functional loss was unilateral, hyperfunction of the contralateral kidney was generally observed. Maximal glucose reabsorption was depressed in proportion to GFR. In kidneys with unilaterally low GFR, the fractional Na+ excretion was consistently increased as compared to the contralateral kidney with normal GFR. This adaptive increase in Na+ excretion must therefore be of intrarenal origin.

Adolescent↗

PubMed1975

Development of renal control of salt and fluid homeostasis during the first year of life.

This study describes the development of renal control of salt and water homeostasis. Twenty-three infants aged 3 weeks to 13 months were studied with respect to glomerular filtration rate (GFR) using single injection technique, ability to excrete an oral salt load, ability to excrete water, and diluting capacity. GFR developed exponentially, salt excretion linearly, water excretion was unchanged and diluting capacity actually decreased. A hypothesis is presented for the theoretical basis of this functional development taking into account the interdependence of the functional parameters studied. This theory might well explain the high incidence of hypernatremic dehydration in infants.

Administration, Oral↗

PubMed1975

Renal control of sodium and fluid balance in newborn infants during intravenous maintenance therapy.

Changes in accumulated fluid and sodium balance during intravenous maintenance fluid therapy has been studied in 38 newborn infants with different clinical disorders and gestational ages 28-42 weeks. The results from the infants born before 36 weeks of gestation (preterm) have been compared with the result from infants born after 36 weeks. Three different saline infusions 10, 20 and 40 mEq Na1/2/1000 ml 5.5% glucose have been given. The infusion rate has in preterm neonates been 3.3 ml/kg and hour and in the more full-term neonates been 3.6 ml/kg and hour. The study lasted for 5-8 hours. Urine was collected by spontaneous voidings in plastic bags. The balances were calculated as the difference between the amount given intravenously, and the amount excreted in the urine. In the more full-term neonates Na1/2 balance became increasingly negative with the 10 mEq solution, just balanced with the 20 mEq solution and increasingly positive with the 40 mEq solution. A different response was found in the preterm neonates. The natriuresis was higher and the sodium balances were increasingly negative with both the 10 and 20 mEq solutions. With the 40 mEq solution the negative balance tended to level off. The fluid balances were fairly well maintained in all infants regardless of the sodium concentration in the infusate.

Blood Proteins↗

PubMed1975

Changes in renal hemodynamics and sodium excretion during saline infusion in lambs.

The renal response to a progressive isotonic extracellular volume (ECV) expansion was studied in 13 lambs of two age groups (5-28 days and 48-57 days). Changes in renal hemodynamics induced by the ECV expansion were followed. Intrarenal blood flow was determined by the microsphere method. For determination of the glomerular filtration rate (GFR) standard clearance techniques were used. Recordings were made during control conditions and when normal saline had been infused in amounts up to 4.5% of the body weight. During the infusion there was an increase in sodium excretion both in absolute values and in relationship to GFR. The increase was, however, much less pronounced in the younger lambs. The GFR did not change significantly during saline infusion. The cortical blood flow increased only in the older lambs. As a consequence the quotient between GFR and cortical blood flow decreased in the older lambs. The possibility of a causal relationship between the fall in filtration fraction so obtained and the more pronounced natriuretic response in the older lambs is discussed. The inner to outer cortical blood flow ratio increased more in the younger lambs during saline infusion. The functional significance of an age related blood flow redistribution is, however, not clear.

Age Factors↗

PubMed1974