Full text of DOI:10.1016/S0022-5347(05)67591-X

0022-5347/00/1636-1896/0
®
THE JOURNAL OF UROLOGY
Vol. 163, 1896–1900, June 2000
Copyright © 2000 by AMERICAN UROLOGICAL ASSOCIATION, INC.®
Printed in U.S.A.
RENAL FUNCTIONAL OUTCOME IN UNILATERAL HYDRONEPHROSIS
IN NEWBORN PIGS
ANNI ESKILD-JENSEN, HANNE CHRISTENSEN, MALENE LINDVIG, JØRGEN FRØKIÆR,
MICHAEL REHLING, HANS STØDKILDE JØRGENSEN, JENS CHRISTIAN DJURHUUS
AND TROELS MUNCH JØRGENSEN
From the Institute of Experimental Clinical Research and MR Research Center, University of Aarhus, and Departments of Clinical
Physiology and Nuclear Medicine, and Urology, Aarhus University Hospital-Skejby, Aarhus, Denmark
ABSTRACT
Purpose: We followed the course of neonatally induced, partial unilateral ureteral obstruction
in pigs and established whether early function or morphological evaluation of the hydronephrotic
kidney is predictive of outcome.
Materials and Methods: In 25 piglets unilateral partial ureteropelvic obstruction was induced
2 days after birth, while 11 underwent sham operation. Only obstructed kidneys with significant
dilatation at 4 weeks were included for further study. Renal function was assessed on renography
using 99mtechnetium-diaminetriaminepentaacetic acid differential uptake. According to the
plasma clearance of 99mtechnetium-diaminetriaminepentaacetic acid the glomerular filtration
rate was determined at ages 4, 12 and 24 weeks. Kidney morphology was studied in parallel by
magnetic resonance imaging.
Results: A total of 12 obstructed kidneys with grade 3 or 4 hydronephrosis fulfilled study
inclusion criteria. Of 6 kidneys with a functional share of 40% or greater at age 4 weeks 2
deteriorated to less than 40% at 24 weeks, while 4 of 6 with a share of less than 40% at age 4
weeks improved to greater than 40% at 24 weeks. The single kidney glomerular filtration rate at
4 weeks did not correlate with that at 12 or 24 weeks but the rate at 12 weeks correlated with that
at 24 weeks (r2 ϭ 0.8140, p Ͻ0.001). Neither relative volume of the obstructed kidney nor length
of the contralateral nonobstructed kidney correlated with functional share of the obstructed
kidney at any age.
Conclusions: Early evaluation of kidney function or volume, or contralateral kidney length did
not predict the outcome of neonatally induced unilateral hydronephrosis in pigs.
KEY WORDS: hydronephrosis, kidney, ureteral obstruction, swine, forecasting
Prenatal ultrasound identifies a large population of asymp- dilatation with a close resemblance to that in children. We
tomatic children with congenital dilatation of the upper uri- used a porcine model with polypapillary kidneys and predom-
nary tract. A recent study showed that only a minor fraction inately short looped nephrons similar to those of human
of these cases involve obstruction when defined as a decrease kidneys.13 Furthermore, in pig kidneys nephrons continue to
in function with time.1 However, to our knowledge there are form up to age 3 weeks.14 Therefore, we considered that
currently no exact methods to determine whether function of obstruction induced at age 2 days would mimic late prena-
a hydronephrotic kidney would or would not deteriorate. The tal obstruction in human fetuses. The animals in our study
routine methods of predicting whether a hydronephrotic kid- were followed until age 24 weeks, corresponding to early
ney would be functionally compromised are pelvic and cal- human adolescence. Parameters normally used for the clini-
iceal dimensions,2, 3 the Whitaker test,4 differential uptake cal assessment of congenital unilateral hydronephrosis were
on renography,2, 5, 6 drainage curve patterns and prolonged applied to describe and when possible predict the course and
half-time values on renography,7 and accelerated growth of outcome.
contralateral kidney length.8, 9
Indications for surgical intervention are controversial.
MATERIALS AND METHODS
They have been set empirically at an initial renographic
Included in our study were 36 female Danish Landrace
functional share of less than 30%,7 35%10, 11 or 40%.5, 6 Pelvic
piglets weighing between 1.10 and 2.25 kg. in which obstruc-
size is also used as an indication for surgery and early pye-
tion was induced at day 2 of life. Preoperatively all animals
loplasty was recommended by Dhillon when hydronephrosis
underwent magnetic resonance imaging (MRI) to exclude
exceeded 50 mm. in renal anteroposterior diameter.2 Re-
those with visible signs of congenital abnormalities of the
cently another approach was suggested based on the renal
kidneys and urinary tract. None of the animals had any
counterbalance phenomenon described by Hinman more
visible abnormality. The study complied with the Danish
than 75 years ago.12 Briefly, Koff et al proposed that deteri-
regulations for care and use of experimental animals.
oration should be assessed by measuring changes in length of
Piglets were pre-anesthetized using midazolam and azap-
the contralateral kidney.8
eronum, and intravenous access was established. They were
We evaluated the development of kidney function and mor-
subsequently intubated and ventilated with a gas mixture of
phology in a morphologically well-defined model of induced
oxygen and nitrous oxide at a ratio of 2:1. Anesthesia was
maintained with 1.2% isoflurane. Using sterile technique a
2.5 to 3 cm. flank incision was made on the left side. The
muscle layers were divided and the peritoneum was gently
Accepted for publication January 14, 2000.
Supported by the University of Aarhus, the Danish Medical Re-
search Council, Novo Nordic Center for Growth and Regeneration,
The Madsen Foundation and King Christian the 10th Foundation.
1896

RENAL FUNCTIONAL OUTCOME IN UNILATERAL HYDRONEPHROSIS
1897
pushed medial. A total of 11 and 25 piglets were then ran- are visualized, while grade 4 hydronephrosis represents
domized to sham operation and partial ureteral obstruction, grade 3 with parenchymal thinning.
Renal length and volume are presented as the average of 3
independent measurements obtained by 2 individual inves-
tigators. Relative volume was calculated for each obstructed
or sham operated kidney using the formula (left kidney vol-
ume/volume of left kidney ϩ volume of right kidney) x 100.
Intra-observer and interobserver variance was calculated for
kidney length at ages 4, 12 and 24 weeks, and presented as
the mean difference plus or minus standard error of mean
(SEM) as well as mean observer difference in the percent of
mean kidney length separately per age.
Body weight, functional share, glomerular filtration rate,
single kidney glomerular filtration rate, relative kidney vol-
ume and renal length are expressed as the mean plus or
minus SEM/kg. body weight. Body weight, functional share,
glomerular filtration rate, single kidney glomerular filtration
rate, relative kidney volume and renal length were tested for
normalcy and compared using 1-way analysis of variance
with p Ͻ0.05 considered statistically significant. Correla-
tions of the single kidney glomerular filtration rate at various
ages, functional share, and kidney volume and length were
analyzed by linear regression.
respectively. Obstruction was created using the method of
Ulm and Miller15 by embedding the ureter in the psoas
muscle. In the sham operated group the ureter was left
nonimplanted outside the muscle. The abdominal muscular
layers and skin were then closed.
Included in further study were only 12 of the 25 pigs with
an obstructed kidney, in which MRI revealed pelvic ectasia at
age 4 weeks. At ages 4, 12 and 24 weeks isotope evaluation
and MRI were performed using a standard hydration regi-
men of 15 ml./kg. per hour of isotonic saline administered for
1 hour before evaluation and 10 ml./kg. per hour during the
whole study. Subjects remained lightly sedated with ket-
amine and midazolam given intravenously. Intravenous ac-
cess for blood sampling was obtained by inserting an indwell-
ing intravenous 0.45 ϫ 0.85 mm. or 18 gauge, 600 mm.
double lumen catheter in a central vein via a superficial
abdominal vein. A catheter was placed transurethrally in the
bladder and urine was obtained for culture.
Kidney function was assessed using combined ␥ camera
renal scintigraphy and plasma clearance techniques in re-
sponse to a bolus injection of 100 MBq. 99mtechnetium-
diethylenetriaminepentaacetatic acid
(
99mTc-DTPA). Dy-
RESULTS
namic renal scintigraphy was performed using a ␥ camera
and an on-line computer. Regions of interest over the kidneys
and background were defined, and time activity curves were
generated. Functional share was calculated as the uptake
ratio of each kidney during the second and third minutes of
the background subtracted integral of a 99mTc-DTPA dy-
namic time activity curve.
MRI revealed normal appearing kidneys in all pigs in our
study before obstruction was induced. A total of 12 animals
fulfilled our study criteria at age 4 weeks with grade 3 or 4
hydronephrosis on gadolinium enhanced MRI (fig. 1). One
animal with obstruction that died of cardiac arrest while
under anesthesia during the 24-week evaluation investiga-
The glomerular filtration rate was calculated as the total tion is included in the study at ages 4 and 12 weeks. Except
plasma clearance of 99mTc-DTPA based on 17, 0.7 ml. blood
for 1 positive culture in a sham operated pig no urinary tract
infections were detected at any time in any animal during the
study period.
Body weight did not differ significantly in obstructed and
sham operated pigs during the study. At ages 2 days, and 4,
samples obtained during 240 minutes after injection. After
each blood sample was obtained the catheter was flushed
with 1 ml. saline. Samples were centrifuged and plasma was
counted in a well crystal scintillation detector to a statistical
accuracy of 1%. For calculating the area under the curve the
detector was fitted with 3 exponential functions using the peel-
ing off technique. Single kidney glomerular filtration rate was
calculated using the formula, glomerular filtration rate ϫ func-
tional share of the left and right kidney, respectively.
At age 4 weeks the kidneys were divided into 2 groups
depending on the fractional uptake of 99mTc-DTPA and de-
rived functional share. The 2 groups comprised kidneys with
a functional share of 40% or greater and less than 40%,
respectively, while the third group included kidneys from
sham operated pigs.
Renal volume and length were measured by MRI. The pigs
were placed supine in the 1.5 Tesla magnet. To cover each
kidney we planned axial slices 3 mm. thick with interscan
spacing 0 mm. and field of view 16 to 28 cm. depending on
age. A 2-dimensional spin echo sequence with echo time 25
msec., repetition time 400 msec. and 256 ϫ 192 was applied.
After image reconstruction in the renal area the medulla and
whole kidney were measured semiautomatically by 2 inde-
pendent observers. Total kidney volume including the intra-
renal pelvis is presented as cm.3/kg. body weight. Renal
length estimated by measuring the kidney longitudinally
from the upper to the lower pole is presented as cm./kg. body
weight.
By calculating relative kidney volume each pig served as
its own control for kidney size and, thereby, hydronephrosis.
In accordance with Society for Fetal Urology recommenda-
tions the extrarenal pelvis was not included in volume esti-
mation since it is believed that a prominent extrarenal pelvis
may be determined to be wide yet not reflect obstruction.4
Hydronephrosis grade at 4 weeks was estimated using
gadolinium-enhanced images according to Society for Fetal
FIG. 1. Representative MRI of hydronephrotic kidney at age 4
Urology guidelines.16 In grade 3 hydronephrosis all calices weeks.

1898
RENAL FUNCTIONAL OUTCOME IN UNILATERAL HYDRONEPHROSIS
12 and 24 weeks mean body weight was 1.79 Ϯ 0.07 kg. of obstructed kidneys with an initial functional share of 40%
versus 1.78 Ϯ 0.08 (p ϭ 0.93), 3.93 Ϯ 0.23 versus 4.19 Ϯ 0.42 or greater and less than 40% at 4 weeks, respectively. The
(p ϭ 0.58), 21.4 Ϯ 1.27 versus 24.3 Ϯ 3.10 (p ϭ 0.34) and
37.2 Ϯ 1.83 versus 39.8 Ϯ 4.02 (p ϭ 0.54), respectively. At 4
weeks average renal functional share in the obstructed group
was significantly decreased compared to that in the sham
operated group (39% Ϯ 4% versus 50% Ϯ 1%, p ϭ 0.01). At 12
and 24 weeks functional share of the obstructed and sham
operated kidneys did not differ significantly (43% Ϯ 3% ver-
sus 50% Ϯ 1%, p ϭ 0.05 and 43% Ϯ 4% versus 49% Ϯ 2%,
p ϭ 0.15, respectively). No significant difference was ob-
served in functional share of obstructed kidneys at ages 4, 12
and 24 weeks (p ϭ 0.65).
course and value of relative kidney volume did not correlate
with the initial functional share or functional course of ob-
structed kidneys. The 2 obstructed kidneys with an initial
functional share of 40% or greater that decreased to less than
40% were no different from those in which it remained
greater than 40% (fig. 4, A). The single obstructed kidney
with an initial functional share of less than 40% that did not
improve to greater than 40% had a large relative volume at
all ages but we noted no clear difference from kidneys that
improved to 40% or greater (fig. 4, B).
We also noted no difference in mean length of kidneys
contralateral to the obstructed and control kidneys at 4, 12
and 24 weeks (1.65 Ϯ 0.09 cm./kg. versus 1.57 Ϯ 0.14, p ϭ
0.61, 0.44 Ϯ 0.02 versus 0.42 Ϯ 0.03, p ϭ 0.53 and 0.28 Ϯ 0.01
versus 0.26 Ϯ 0.02, p ϭ 0.42, respectively). To determine
whether changes in the functional share of obstructed kid-
neys were associated with the length of the contralateral
nonobstructed kidney we compared these 2 parameters.
Mean length of the contralateral kidney did not correlate
with functional share of the obstructed kidney at 4, 12 or 24
weeks (r2 ϭ 0.2145, p ϭ 0.13; r2 ϭ 0.0781, p ϭ 0.38 and r2 ϭ
0.0459, p ϭ 0.53, respectively). Mean image modality intra-
observer variance was 0.25 Ϯ 0.08 cm. or 2.4% of mean
kidney length at 4 weeks, 0.22 Ϯ 0.04 cm. or 2.2% at 12 weeks
and 0.16 Ϯ 0.02 cm. or 2.4% at 24 weeks. Mean interobserver
variance was 0.31 Ϯ 0.08 cm. or 2.9% of mean kidney length
at 4 weeks, 0.29 Ϯ 0.05 cm. or 2.9% at 12 weeks and 0.17 Ϯ
0.02 cm. or 2.6% at 24 weeks.
Figure 2 shows the functional share of all obstructed kid-
neys and the average in sham operated kidneys at ages 4, 12
and 24 weeks. Of the 6 obstructed kidneys with a functional
share of 40% or greater at 4 weeks 2 deteriorated from 44%
and 40% at 4 weeks to 26% and 34% at 12 weeks, further
decreasing at 24 weeks to 17% and 22%, respectively (fig. 2,
A). In 1 obstructed kidney the functional share decreased
from 49% at 4 weeks to 43% at 24 weeks, while in the
remaining 3 in this group it was stable. Of the 6 obstructed
kidneys with an initial functional share of less than 40% 4
improved to greater than 40% at 12 and 24 weeks (fig. 2, B),
1 deteriorated from 39% at 4 weeks to 35% at 12 and 32% at
24 weeks, and 1 was lost before the 24-week evaluation but
function improved from 7% at 4 weeks to 31% at 12 weeks.
At age 4 weeks the mean single kidney glomerular filtra-
tion rate was significantly decreased in obstructed versus
sham operated kidneys (1.07 Ϯ 0.13 versus 1.73 Ϯ 0.14 ml.
per minute per kg., p Ͻ0.01). At 12 and 24 weeks the mean
single kidney glomerular filtration rate did not differ in ob-
structed and sham operated kidneys (1.27 Ϯ 0.12 versus
1.30 Ϯ 0.12 ml. per minute per kg., p ϭ 0.85 and 0.76 Ϯ 0.08
versus 0.85 Ϯ 0.07, p ϭ 0.41, respectively). The mean single
kidney glomerular filtration rate in obstructed pigs at 4
DISCUSSION
The major findings in our study were that the individual
functional course of obstructed kidneys was not predicted by
early renographic evaluation, the initial single kidney glo-
merular filtration rate, relative kidney volume or length of
the contralateral nonobstructed kidney. We noted no corre-
lation of relative kidney volume or contralateral kidney
length with functional share at any age. Determining renal
function in early life does not predict functional development.
Functional share is considered by some to be a decisive factor
in the appropriate management of unilateral hydronephro-
sis.3, 5–7, 10, 11 The threshold for surgical intervention is arbi-
trarily chosen at a functional share of less than 30% to 40%.
Therefore, we categorized obstructed kidneys with grade 3 or
4 hydronephrosis into 2 groups based on a functional share of
40% or greater and less than 40% on renography at age 4
weeks. Of the 6 obstructed kidneys with an initial functional
weeks did not correlate with that at 12 or 24 weeks (r2
ϭ
0.1201, p ϭ 0.26 and r2 ϭ 0.0005, p ϭ 0.99, respectively, fig.
3, A and B). However, the mean single kidney glomerular
filtration rate at 12 weeks correlated with that at 24 weeks
(r2 ϭ 0.8140, p Ͻ0.001, fig. 3, C). This finding suggests that
function at age 12 weeks predicts function at 24 weeks. Mean
relative volume of the obstructed kidneys was significantly
higher than that of sham operated kidneys at 4, 12 and 24
weeks (65.1% Ϯ 1.8% versus 48.1% Ϯ 2.3%, p Ͻ0.0001; 63.5%
Ϯ 3.0% versus 52.8% Ϯ 0.8%, p Ͻ0.01, and 60.5% Ϯ 3.5%
versus 51.6% Ϯ 0.5%, p ϭ 0.03, respectively). Relative kidney
volume did not correlate with functional share at 4, 12 or 24
weeks (r2 ϭ 0.1814, p ϭ 0.19; r2 ϭ 0.1203, p ϭ 0.30, and r2 ϭ
0.4703, p ϭ 0.02, respectively).
Figure 4 shows the individual course of the relative volume share of less than 40% 4 improved to normal at 12 and were
FIG. 2. Functional share of obstructed (solid lines) and average share of sham operated (broken lines) kidneys at age 4 versus 4, 12 and
24 weeks. A, 40% or greater. B, less than 40%.

RENAL FUNCTIONAL OUTCOME IN UNILATERAL HYDRONEPHROSIS
1899
the finding that early functional share does not predict func-
tional outcome. Koff and Campbell,17 and Ulman et al18
nonoperatively followed 104 neonates with congenital grade
3 or 4 hydronephrosis regardless of the initial functional
share. During a mean followup of 6.5 years 22% of patients
had a deteriorating functional share and/or increasing hydro-
nephrosis, which was an indication for surgical intervention.
Koff and Campbell noted an initial functional share of 40% or
less in 16 kidneys, including 1 in which functional share
deteriorated and 14 in which it improved to greater than 40%
during a mean followup of 21 months.17 Deteriorating renal
function was observed in 6 of 39 kidneys with an initial func-
tional share of greater than 35% by Cartwright et al during a
mean followup of 18 months10 and in 14 of 100 with an initial
share of greater than 40% by Ransley et al during a mean
followup of 1 to 6 years.6 However, these studies were of shorter
duration than ours and longer followup may detect more dete-
riorating kidneys.
In our study functional share stabilized from ages 12 to 24
weeks, although in the 2 kidneys with deteriorating function
the share decreased further, indicating that after the initial
unstable phase a state of equilibrium is generally achieved.
This observation is supported by Ulman et al, who performed
pyeloplasty due to decreasing function or increasing hydro-
nephrosis within the initial 14 months of life.19 In other
studies the majority of pyeloplasties were performed within
the initial 3 years of life.2, 6 However, to our knowledge no
group followed children long enough to document whether
nonoperated kidneys remain stable. In our study the pigs
were followed until age 24 weeks, corresponding to early
adulthood in humans.
To distinguish children who would benefit from surgery
from those in whom dilatation is inconsequential Dhillon
suggested pelvic size as a predictor of functional outcome.2 In
our study total kidney volume, including that of the intrare-
nal pelvis, was used to describe the degree of hydronephrosis.
The ideal parameter may have been a measure of the pelvis
or parenchyma. Unfortunately we realized during analysis
that intrarenal structures with a high water content, such as
papillae and possibly part of the inner medulla, were not
reliably distinguished from the pelvis by noncontrast en-
hanced MRI. Therefore, we substituted a pelvic estimate
with a measure of the whole kidney, including the intrarenal
pelvis.
In our long-term study there was a tendency toward an
association of a large intrarenal pelvis expressed as a large
obstructed kidney and a low functional share at all ages.
However, a large kidney did not correlate with decreased
function or later functional outcome. As in our study,
Josephson did not note any correlation of functional impair-
ment with degree of pelvic enlargement in neonatal ob-
structed rat kidneys.19 Our results are also supported by
those of Takla et al,11 and Freedman and Rickwood5 who
observed no correlation of initial postnatal hydronephrosis
grade with the likelihood of surgical resolution, as indicated
by impaired renal function or drainage, or the incidence of
impaired renal function, respectively, in patients with pre-
natally diagnosed hydronephrosis. However, our findings
contradict the observations of Dhillon, who followed 36 chil-
dren with initially good hydronephrotic kidney function.2
Seven kidneys had decreasing function after 1 year of obser-
vation and all had a minimum of 20 mm. of initial dilatation.
However, overall mean pelvic diameter was 23 mm. (range 15
to 50) and 9 of 17 children in whom dilatation improved
spontaneously also had initial dilatation greater than 20 mm.
Serial measurements of the length of the contralateral
nonobstructed kidney were suggested by Koff et al as a diag-
FIG. 3. Glomerular filtration rate (GFR) of single obstructed kid-
neys. A, at age 4 versus 12 weeks. B, at 4 versus 24 weeks. C, at 12
versus 24 weeks. BW, body weight.
stable at 24 weeks, while 2 of the 6 obstructed kidneys with
a share of greater than 40% deteriorated to less than 40%.
To our knowledge few clinical studies describe the natural nostic test for obstruction in cases of unilateral hydronephro-
history of this condition. Except for the series of Koff et sis.8 In children Koff et al noted that kidneys contralateral to
al17, 18 most exclusively involve kidneys with an initial func- hydronephrotic kidneys with a decreasing functional share
tional share of greater than 35% to 40%. Our study supports had accelerated length growth and were significantly longer

1900
RENAL FUNCTIONAL OUTCOME IN UNILATERAL HYDRONEPHROSIS
FIG. 4. Relative volume of obstructed kidneys (solid lines) and average volume of sham operated kidneys (dashed line) at 4, 12 and 24
weeks. A, functional share 40% or greater. Bold lines represent 2 obstructed kidneys with initial 40% or greater functional share at 4 weeks
that decreased to less than 40%. B, functional share less than 40%. Bold line represents 1 obstructed kidney that did not improve to greater
than 40% functional share.
than normal for age, whereas those contralateral to hydro-
nephrotic kidneys with an increasing functional share had a
decreased length growth rate. We observed no association of
length of the contralateral nonobstructed kidney with func-
tional share of the obstructed kidney at any age. These find-
ings confirm those of Brandell et al, who in a retrospective
study detected no correlation of single measurements of renal
length with the presence or absence of obstruction in hydro-
nephrotic kidneys judged by furosemide renography and hy-
dronephrosis grade.9
management of hydronephrosis diagnosed by prenatal ultra-
sound. J Urol, 144: 584, 1990
7. Kass, E. J. and Fink-Bennett, D.: Contemporary techniques for
the radioisotopic evaluation of the dilated urinary tract. Urol
Clin North Am, 17: 273, 1990
8. Koff, S. A., Peller, P. A., Young, D. C. et al: The assessment of
obstruction in the newborn with unilateral hydronephrosis by
measuring the size of the opposite kidney. J Urol, 152: 596,
1994
9. Brandell, R. A., Brock, J. W., III, Hamilton, B. D. et al: Unilat-
eral hydronephrosis in infants: are measurements of con-
tralateral renal length useful? J Urol, 156: 188, 1996
10. Cartwright, P. C., Duckett, J. W., Keating, M. A. et al: Managing
apparent ureteropelvic junction obstruction in the newborn.
J Urol, 148: 1224, 1992
11. Takla, N. V., Hamilton, B. D., Cartwright, P. C. et al: Apparent
unilateral ureteropelvic junction obstruction in the newborn:
expectations for resolution. J Urol, 160: 2175, 1998
12. Hinman, F.: Renal counterbalance: an experimental and clinical
study with reference to the significance of disuse atrophy.
J Urol, 9: 289, 1923
13. Terris, J. M.: Swine as a model in renal physiology and nephrol-
ogy: an overview. In: Swine in Biomedical Research. Edited by
M. E. Tumbleson. New York: Plenum Press, pp. 1673–1709,
1986
CONCLUSIONS
Our study shows that the early measurement of functional
share, single kidney glomerular filtration rate, volume of the
obstructed kidney or length of the contralateral nonob-
structed kidney in our model did not differentiate kidneys
with later decreasing function from those with insignificant
hydronephrosis. After the initial phase renal function stabi-
lizes compared with that in sham operated kidneys regard-
less of the initial functional level, although kidneys with
decreasing function deteriorate further.
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