Pyelonephritis Patients Research Articles

In vivo phase variation of Escherichia coli type 1 fimbrial genes in women with urinary tract infection.

Type 1 fimbriae, expressed by most Escherichia coli strains, are thought to attach to human uroepithelium as an initial step in the pathogenesis of urinary tract infections (UTI). Numerous reports using both in vitro and murine models support this role for type 1 fimbriae in colonization. Unfortunately, only a limited number of studies have directly examined the expression of fimbriae in vivo. To determine whether type 1 fimbrial genes are transcribed during an acute UTI, we employed a modification of an established method. The orientation (ON or OFF) of the invertible promoter element, which drives transcription of type 1 fimbrial genes, was determined by PCR amplification using primers that flank the invertible element, followed by SnaBI digestion. The orientation of the type 1 fimbrial switch was determined under three experimental conditions. First, E. coli strains from different clinical sources (acute pyelonephritis patients, cystitis patients, and fecal controls) were tested under different in vitro culture conditions (agar versus broth; aerated versus static). The genes in the more-virulent strains (those causing acute pyelonephritis) demonstrated a resistance, in aerated broth, to switching from OFF to ON, while those in fecal strains readily switched from OFF to ON. Second, bladder and kidney tissue from CBA mice transurethrally inoculated with E. coli CFT073 (an established murine model of ascending UTI) was assayed. The switches directly amplified from infected bladder and kidney tissues were estimated to be 33 and 39% ON, respectively, by using a standard curve. Finally, bacteria present in urine samples collected from women with cystitis were tested for type 1 fimbria switch orientation. For all 11 cases, an average of only 4% of the switches in the bacteria in the urine were ON. In 7 of the 11 cases, we found that all of the visible type 1 fimbrial switches were in the OFF position (upper limit of detection of assay, 98% OFF). Strains recovered from these urine samples, however, were shown after culture in vitro to be capable of switching the fimbrial gene to the ON position and expressing mannose-sensitive hemagglutinin. The results from experimental infections and cases of cystitis in women suggest that type 1 fimbrial genes are transcribed both in the bladder and in the kidney. However, those bacteria found in the urine and not attached to the uroepithelium are not transcriptionally active for type 1 fimbrial genes.

Renal 99Tcm-DMSA SPET and planar imaging

Previous studies have suggested that more defects are detected on SPET than on planar DMSA images. The aim of this study was to evaluate differences between planar and SPET imaging. Sixty-four kidneys from pyelonephritic patients were studied using both techniques. An automated algorithm for reorientation and centring of the SPET images was used to minimize inter-observer variability. Reduced uptake and contour defects showed different localization on planar and SPET imaging. Coincidence of defects on both types of image was low. We also noted a dependence on defect frequency content for detectability. Image contrast played a noticeable role in the detection of defects. Differences in contrast between SPET and planar images may be responsible for the variable success in the detection of defects. Contour defects are seen more frequently on tomographic slices, whereas reduced uptake defects are seen more frequently on planar images. A difference is also noted between the cortical and calyceal zones for differently contrasted lesions. SPET and planar DMSA images can potentially provide a different diagnosis of renal lesions.

Acute pyelonephritis focusing on perfusion defects on contrast enhanced computerized tomography(CT) scans and its clinical outcome.

ObjectivesMany cases of acute pyelonephritis show renal perfusion defects on contrast enhanced computerized tomography (CT) imaging studies. The purpose of this study is to show the frequency of renal perfusion defects in uncomplicated acute pyelonephritis and to compare the clinical responses of patients who had perfusion defects or not.MethodsWe studied patients who had symptoms and signs of acute pyelonephritis through CT examinations with contrast enhancement. We identified 21 cases who had perfusion defects among 35 patients who had undergone CT imaging studies and compared the clinical data in the two groups of patients who had perfusion defects on CT (group 1) and who had not (group 2).ResultsNearly all patients had typical symptoms and signs of acute pyelonephritis such as high fever and chill, flank pain and costovertebral angle tenderness. Combined clinical problems were septic shock (one case, 4.8%) and disseminated intravascular coagulation (DIC) (one case, 4.8%) in group 1. Laboratory findings were not different between the two groups. All patients were treated with antibiotics and had successful recoveries. The duration of recovery of pyuria in group 1 (5.2±9.6 days) was not longer than that in group 2(3.1±2.9 days) (p>0.05). The length of defeverscence in group 1 (7.0±4.6 days) was longer than in group 2 (3.5±2.7 days) (p<0.05). There were no differences between group 1 and group 2 in the rate of predisposing factors. Thirteen of 21 cases (61.9%) in group 1 and five of 14 cases (35.7%) in group 2 had positive urine culture results which are relatively low probably due to the administration of antibiotics prior to our emergency room visit. Perfusion defects on CT were very frequent findings (60.0% of the clinical acute pyelonephritis patients). We classified CT findings of group 1 as focal unilateral (2 cases, 9.5%), multifocal unilateral (14 cases, 66.7%) and multifocal bilateral (5 cases, 23.8%), and there were no differences between the subgroups of group 1 in the duration of defeverscence.ConclusionThose patients who had perfusion defects on CT showed relatively severe clinical courses but responses to early antibiotics were very good. Contrast enhanced CT scans may be very sensitive for the detection of acute renal parenchymal inflammatory disease and for defining the extent of disease, but it is clinically not essential to perform in the early uncomplicated acute pyelonephritis because CT diagnosis does not change management. Clinical use of contrast enhanced CT scan may be appropriate in case of persistence of fever and leukocytosis for more than seven days despite antibiotic treatment.

Fever duration in hospitalized acute pyelonephritis patients

To study persistence of fever in treated pyelonephritis with respect to guidelines recommending investigation and modification of therapy after 2 to 3 days of fever. A retrospective chart review was made of 70 patients hospitalized for febrile pyelonephritis at a community hospital in Canada. Median duration of fever was 34 hours; persistence of fever at 48 and 72 hours was 26% and 13%, respectively. No patients had complications such as intrarenal or perirenal abscess. Prolonged fever was independently associated with increasing baseline creatinine (P = 0.0001), younger age (P = 0.027), and increasing total leukocyte count (P = 0.026). Results of ultrasonography and intravenous urograms were not predictors of fever duration. Fever in treated pyelonephritis can take 4 days to resolve, and routine urologic investigation after 2 to 3 days of fever may be unwarranted.

Urinary secretory immunoglobulin A and free secretory component in pyelonephritis

The immune defense mechanisms of mucosal surfaces involve secretory immunoglobulin A (sIgA) antibodies and, to a lesser degree, other specific and nonspecific immune factors. These antibodies are dependent on a secretory component (SC) for their transmission through the epithelium. This SC is also secreted without Ig as free SC (FSC). The kidney does produce these proteins; however, the ability of the lower urinary tract to secrete them has not been shown. Thus, an upper urinary tract infection should produce more urinary sIg and possibly more FSC than a lower tract infection. To demonstrate this, urine was obtained from normal controls (N = 33), cystitis patients (N = 22), and pyelonephritis patients (N = 27). Monoclonal antibodies binding to specific conformational epitopes were used in an enzyme-linked immunosorbent assay to detect the levels of sIgA and FSC in these groups. Previous sIgA measurements have been hampered by lack of specificity of the capture antibody. Urine creatinine was obtained to correct for the effect of diuresis. A one-tailed Student's t-test for nonparametric populations was performed to assess differences. The sIgA levels in the normal and cystitis groups were equivalent (1.4 μg/mg/mL and 1.3 μg/mg/mL, respectively; P = 0.32). When these two groups were compared with the pyelonephritis group (24.1 μg/mg/mL), a statistically significant difference was seen ( P = 0.012 and P = 0.011, respectively), with no overlap. There was a statistical difference in the levels of FSC in these same groups, but a large degree of overlap. Urinary level of sIgA as measured by this monoclonal antibody is a sensitive test to differentiate pyelonephritis from cystitis, but FSC levels are not predictive. This may be due to differential secretion of sIgA by upper and lower urinary tract mucosa when exposed to infectious agents.

Dra-related X adhesins of gestational pyelonephritis-associated Escherichia coli recognize SCR-3 and SCR-4 domains of recombinant decay-accelerating factor

Bacterial adhesins are important virulence factors that allow colonization of the human urogenital tract by Escherichia coli. Adhesins of the Dr family have been found to be more frequently expressed in strains associated with symptomatic urinary tract infections. Because of the high frequency of symptomatic urinary tract infections during pregnancy, we screened E. coli isolates from 64 gestational pyelonephritis patients for the expression of Dr and X adhesins to address their potential virulence roles in this population. Using PCR and primers for the afaB gene, we detected dra-related operons in 17 isolates (27%). On the basis of the lack of hemagglutination of Dr(a-) erythrocytes containing a point mutation in the decay-accelerating factor (DAF) short consensus repeat-3 (SCR-3) domain, 12 of these strains were categorized as classical Dr adhesins. The hemagglutination of O erythrocytes by Dr+ strains was blocked or reduced by a monoclonal antibody to the DAF SCR-3 domain. The remaining five dra-positive strains agglutinated Dr(a-) erythrocytes. Monoclonal antibody to the DAF SCR-3 domain failed to block O-erythrocyte hemagglutination. Adhesins in these strains did not fulfill criteria for Dr hemagglutinins because of the undefined receptor specificities and were categorized as X. E. coli strains bearing dra-related X adhesins bound to DAF cDNA-transfected Chinese hamster ovary cells. Three of these dra-related X-adhesin-bearing E. coli strains failed to attach to the SCR-3 delta deletion transfectant, which suggested that binding sites were located in the SCR-3 domain but outside the region blocked by the monoclonal anti-SCR-3 immunoglobulin G. The binding sites of the remaining two dra-related X adhesin strains were localized to the SCR-4 domain, as the attachment was shown to be abolished on an SCR-4 delta mutant but unaffected by an SCR-3 delta deletion. The heterogeneity in the binding sites of E. coli DAF (Dr) family adhesins from gestational pyelonephritis isolates may reflect the ability of the adhesins to evolve to recognize alternate peptide epitopes for efficient colonization.

Colicin 24, a New Plasmid-Borne Colicin from a Uropathogenic Strain of Escherichia coli

A new colicin, as defined by cross-immunity tests against the colicin reference set, has been identified from a uropathogenic Escherichia coli isolate (strain 2424), collected from a pyelonephritis patient at Christchurch Hospital. This toxin, colicin 24, is active against E. coli and Salmonella typhimurium , and the genes involved in colicin 24 production, transport, and immunity were found to reside on a 43.54-kb conjugative plasmid, p24-2. Mutagenesis using mini-Tn 10 has identified two consecutive Eco R1 fragments on p24-2 that contain all the colicin 24 determinants. A 25.14-kb BamHl- HindIII fragment containing this region was cloned from a mutant with a normal colicin phenotype into pBR322 to form the recombinant plasmid pGOB34. Subcloning of pGOB34 has resulted in an 8.7-kb fragment containing all the colicin 24 determinants being cloned into pUC18 to form pGOB342.

Medical histories of children with acute pyelonephritis compared with controls

The medical history of infants and preschool children with their first known episode of pyelonephritis was obtained by questionnaire and compared with that of controls matched for age, sex and living area. Previous infection, medical consultation and antibiotic treatment were registered significantly more often in the patients. Furthermore a high proportion of cases had recently received antibiotic therapy, primarily penicillin V. Urinary tract infections were reported more often among first degree relatives of the cases. Exclusive breast-feeding was significantly shorter in the pyelonephritis patients, according both to the questionnaire and to the records from the Child Health Centers. The two populations were not shown to differ in birth weight or length, neonatal history, number of hospitalizations, previous episodes of fever or frequency of atopic disease in the families.

Urinary N-acetyl-beta-D-glucosaminidase activity in acute pyelonephritis patients with spinal cord injuries

The urinary N-acetyl-beta-D-glucosaminidase (NAG) activities were determined in acute pyelonephritis patients with spinal cord injuries. The urinary NAG activity was significantly elevated in 23 of 31 cases (74%) compared with normal controls. Out of 7 acute pyelonephritis patients without spinal cord injuries, 4 patients (57%) showed significantly elevated urinary NAG activities. The urinary NAG activities were within normal range in 20 patients with acute simple cystitis and 11 patients with chronic complicated cystitis. Out of 6 patients with urethritis, only one case (17%) showed a significantly higher level of urinary NAG activity. Significantly higher levels in urinary NAG activities were observed in 6 of 9 patients (67%) with acute prostatitis and 5 of 9 patients (56%) with acute epididymitis. In patients with spinal cord injuries, having frequent urinary tract infections and complicated pathophysiological conditions, urinary NAG is one of the helpful laboratory findings for the diagnosis of acute pyelonephritis.

Relevance of vesico-ureteric reflux in development of lipid A antibodies in recurrent urinary tract infections in children--a preliminary study.

The serum titres of IgG and IgM antibodies to lipid A were measured in 24 children with chronic pyelonephritis (PN), 55 with recurrent lower urinary tract infections (LUTI), 13 with gram-negative sepsis (S), and in 50 control children using an enzyme-linked immunosorbent assay (ELISA). Children ranged in age from 1 month-17 years. Patients with PN were differentiated by the presence or absence of an acute infectious episode and/or vesico-ureteric reflux (VUR). During an acute episode in PN and LUTI, IgG titres were significantly higher than in controls, but only PN patients with an acute infectious episode also had significantly elevated IgM titres. Overall, children with LUTI showed a significantly lower frequency of detectable IgG lipid A antibodies (27%) than in PN (63%). In PN children with VUR not accompanied by an infectious episode, lipid A antibody was found at relatively low titres, while an episode not accompanied by VUR displayed significantly elevated IgG titres, and an episode accompanied by VUR showed elevation of both IgG and IgM anti-lipid A antibody titres.

Association between fever and the antibody response to Tamm-Horsfall protein in urinary tract infection.

The usefulness of measuring serum antibodies to Tamm-Horsfall protein (THP) for diagnosing the level of acute urinary tract infections in adult women was evaluated. There was a significant (p less than 0.001) elevation of IgG and IgA anti-THP in pregnant and non-pregnant women with acute pyelonephritis compared to women with acute cystitis. The changes in anti-THP antibody titre among patients with acute pyelonephritis varied considerably, limiting the value of determining such antibodies for diagnostic purposes. Patients with febrile infections of non-renal origin demonstrated an antibody response comparable to the pyelonephritis patients. One explanation for these results could be that fever is associated with transient rental tubular damage, thus exposing THP to the immune system. Polyclonal antibody activation seems less likely since neither an IgM antibody response to THP, nor an increase in antibody titre to poliovirus could be demonstrated.

Antireflux in adults: a long-term follow-up.

The long-term results after antireflux operation in 47 adults are presented. Reflux was eliminated in all but 3 cases. Preoperatively most patients complained of urinary tract infection with or without fever, but sometimes investigation for hypertension or urolithiasis also led to the diagnosis. Postoperatively 70% of the patients are free of symptoms and infection. Renal scarring in pyelonephritic patients seems to stop after intervention. In all patients with a normal preoperative creatinine level, this level stays normal after the intervention. However, in 6 of 7 patients with a creatinine level of greater than 1.5 mg% before operation, the intervention could not stop the evolution toward terminal renal failure.

P-fimbriated clones among uropathogenic Escherichia coli strains.

A total of 237 Escherichia coli strains isolated from the urine of patients with various forms of urinary tract infection or from feces of healthy children were analyzed for O group, possession of K1 capsule, type 1 fimbriae, P fimbriae, X adhesin, and production of hemolysin. Some of the strains were also analyzed for K and H antigens, outer membrane protein pattern, and plasmid content. P fimbriation, hemolysin production, and certain O groups were found to be significantly correlated with pyelonephritogenicity. Possession of type 1 fimbriae or of K1 capsule or plasmid content did not significantly correlate with virulence. Outer membrane protein patterns in 139 strains of the more common O groups were analyzed. Only one to three patterns, which varied between serotypes, were usually found within any one O group. Distinctive groups (clones) were found when the strains were grouped according to complete serotype, fimbriation, hemolysin production, and outer membrane protein pattern; also, the mean number of plasmids was typical of the strains in a given clone. Seven clones associated with pyelonephritis were found; together they accounted for 57% of the O serotypable strains from the pyelonephritis patients. The seven clones were P fimbriated but differed in their serotypes as follows: O1:K1:H7, O4:K12:H1, O4:K12:H5, O6:K2:H1, O16:K1:H6, or O18ac:K5:H7. All O1:K1:H7 strains observed fell into two clones according to the presence or absence of type 1 fimbriae and hemolysin production. One clone associated with cystitis was also found; this consisted of O6:K13:H1 strains lacking P fimbriae. Not a single representative of these eight clones was found among the fecal strains from the healthy children. They are proposed to represent virulent clones with special ability to cause human urinary tract infection.

Aspartat-aminotransferase-aktivitäten im nierengewebe bei experimenteller und menschlicher chronischer pyelonephritis

Question: This study belongs to a series of comparative biochemical and semiquantitative-histological investigations in renal tissue fractions of pyelonephritis patients (human PN) and of different types of experimental pyelonephritis (experimental PN). The experiments aim at more detailed knowledge on the interrelationship of intermediary cell metabolism and histopathological changes during the different phases of human and experimental PN. The results concerning acid and alkaline phosphatase activities as well as concerning glutaminase I and glutamic dehydrogenase activities were earlier reported (Exp. Path. vols. 8, 9, 10 and 12). In the present study the author has analyzed the activities of aspartate aminotransferase (E.C.2.6.1.1. AspAT) the synonym of which is glutamic oxaloacetic transaminase (GOT).

THE IMMUNE RESPONSE TO URINARY TRACT INFECTIONS IN CHILDHOOD

Determination of antibodies to E. Coli O antigen by indirect hemagglutination for detection of acute pyelonephritis was investigated in sequences of sera from 94 girls with their first known attack of symptomatic urinary tract infection. Using O antigen from the infecting bacterial strain or a standard strain increased antibody titres were found among pyelonephritis patients in 89% in unreduced sera (mainly 19 S antibodies) and in 81% in reduced sera (mainly 7 S antibodies) compared to a control material of 643 healthy children. Significant changes of these antibody titres occurred in 74 and 39% respectively. Analysis of maximal titres as well as titre changes in both unreduced and reduced sera showed diagnostically significant changes in two or more of these four parameters in 89% of patients with pyelonephritis. In contrast one parameter with such changes was found among the cystitis patients in only 5%. Employing a pool of 8 common O antigens, increased antibody titres were detected in 76% of patients with pyelonephritis. A larger pool of 68 antigens was no better and had a low capacity to detect 7 S antibodies. Optimal time for blood sampling was 2 to 3 weeks after onset of symptoms.

Serum anti-Escherichia coli antibodies and urinary β-glucuronidase for the diagnosis and control of evolution of urinary infection during pregnancy

Asymptomatic bacteriuria was found in 6.3 per cent of our patients. Prematurity was not found in treated asymptomatic bacteriuric or pyelonephritic patients. Urinary β-glucuronidase and serum antibodies against the O-antigen of Escherichia coli are higher than normal in 37 and 48 per cent, respectively, of asymptomatic bacteriuric patients. It has been demonstrated that high levels of urinary β-glucuronidase or serum antibodies are coincident with infection of the kidney; thus, one-third to one-half of the patients with asymptomatic bacteriuria are, in fact, clinically inapparent pyelonephritis, which can be detected through the estimation of urinary β-glucuronidase or serum antibodies. High levels of β-glucuronidase and antibodies were also found in 56 and 64 per cent, respectively, of pyelonephritic patients. Higher than normal antibody titers decrease after treatment; when the titers are low, they will probably remain steady.

Hypertension with Renal Impairment: Influence of Intensive Therapy

The influence of effective blood pressure control upon renal function has been examined in a group of 83 patients with severe hypertension and renal impairment. Twenty-seven patients (32.5 per cent) died or were transferred to a dialysis programme within six months of referral. Mean creatinine clearance in this group was 3.6 ml/min and all but two patients had a creatinine clearance of less than 8 ml/min. By contrast, initial mean creatinine clearance in patients who survived more than six months was 28.9 ml/min. A highly significant fall in clearance, associated with poor blood pressure control by conventional agents, could be demonstrated in the 30 patients who had had creatinine clearance measured upon first presentation. This fall was reversed with effective blood pressure control in the 35 patients who were considered to have primary hypertension, and who survived more than six months. In these, clearance rose from 35.1 to 50.5 ml/min. Change of a similar order could be demonstrated in chronic pyelonephritic patients. Follow-up of 56 (67.5 per cent) patients who survived more than six months was extended up to 43 months and confirmed that the improvement in renal function was maintained. Chronic glomerulonephritic patients showed a deterioration in renal function at six months despite good blood pressure control. In most patients there was an initial fall in creatinine clearance with blood pressure control: this was not seen in patients who were in congestive cardiac failure in whom improvement in cardiac function apparently nullifies the fall in renal perfusion pressure. It is concluded that the prognosis of patients with primary hypertension and renal impairment is good when effective blood pressure control is maintained if the initial creatinine clearance exceeds 8 ml/min and if there is no intrinsic, progressive renal disease.

Clinical studies on the antibody response to E coli O-antigens in infants and children with urinary infection, using a passive haemagglutination technique.

SummaryEarlier investigations have shown that the passive haemagglutination reaction is a specific and reliable tool in demonstrating humoral antibodies to different bacterial species.In the first part of this survey some methodologic investigations are presented. It was found that the antibodies in the sera were partly or completely inactivated during storage at +4°C for about a month, while the activity was unchanged after at least six months at ‐20°C. The limiting concentration, necessary for sensitization of the erythrocytes used in the reaction, was found to be around 60 million bacteria for different 0‐antigens.Four different sources of antigen were used during this investigation. Originally the infecting urinary bacteria from the patients were employed. Further studies compared this source with the faecal coli flora, with Kunin's common enterobacterial antigen and with a polyvalent antigen, consisting of a mixture of the eight E. coli 0‐types most frequently encountered in urinary tract infections. The reason for these investigations were partly that some source other than urinary bacteria had to be used in the controls and in suspected cases of pyelonephritis without urinary excretion of bacteria, and partly that the preparation of individual antigens for each patient makes the method too complicated and time‐consuming for use as a clinical routine procedure.These studies revealed, that the faecal bacterial antigens gave results similar to the urinary ones in about half of the cases. The common enterobacterial antigen could not be used as a substitute for the homologous homologous antigens since practically no antibodies were observed to this antigen in the sera. The polyvalent antigen was found to be a valuable substitute for the infecting strains, as equal titres could be demonstrated in those cases, where the homologous urinary strains belonged to one or another of the types, included in the antigen pool. By means of this antigen it was also found that some patients, lacking antibody response to the bacterial strains, found in their urine, did have antibodies in elevated titres against the polyvalent antigen. This might be due to a continuous antigen stimulation from earlier infections. If this is proved, the finding indicates that determination of the coli antibody titre is a valuable tool in the detection of occult chronic pyelonephritis. However, further studies are necessary to permit definite conclusions.A material of controls was studied and it was found, that almost all children above the age of about two months have agglutinating antibodies to E. coli in their serum.A series of patients with uncomplicated first‐time urinary tract infections with and without renal involvement were followed longitudinally. The findings showed that almost all of the patients above the age of three months with pyelonephritis had a sharp increase in the antibody titre, while those without functional impairment of the kidneys had titres within the limit of the control cases. It is thus possible to differentiate between cases of pyelonephritis and cases of lower urinary tract infections by means of this method. Elevated coli antibody titres were not found in pyelonephritic patients below the age of two months. The reason for this is discussed.A comparison between the antibody titre courses in patients with and without recurrences after their first episode revealed that the initial antibody response in the former group was not less than in the latter group.The rapid decrease (within 90 days) of the antibody titres found in most of the patients after treatment of the infections indicates that the homologous antigens were effectively eliminated by the treatment.Determinations of the coli antibody titre were performed in some patients, whose clinical symptoms were suggestive of pyelonephritis, but in whom the usual urinary findings were absent or inconclusive. In eight out of thirteen of these a course of the antibody titre, similar to that observed in patients with overt pyelonephritis, was demonstrated and it is therefore regarded as most likely, that these patients were in fact suffering from pyelonephritis.Further, the clinical use of antibody titrations in different types of urinary tract infections or their sequelae are illustrated by patients with recurrent urinary tract infection, renal hypertension and asymptomatic bacteriuria. The findings in some of these patients may indicate, that determination of antibodies to E. coli is a useful instrument in the detection of some of those patients who are at risk for contracting chronic pyelonephritis.

The Radiorenocystogram in Chronic Pyelonephritis

The Hippuran-I131 renocystogram is a reliable external method for detecting functional differences between kidneys (1). Chronic pyelonephritis is especially suitable for investigation with this procedure because it characteristically causes more tissue damage and functional suppression of one kidney than the other (2, 3). While a group of pyelonephritic patients was being studied with serial renocystograms to determine if functional disturbances could be improved by specific treatment, the following observations were made. First, renogram abnormalities associated with this disease are: reduction in the slopes of the tubular segments, delayed onset of excretion, and excretion segments which descend from peak levels at disproportionately slow rates. Second, differences between left and right renal tracings may be accentuated if fluids are restricted eight to twelve hours before the test, whereas they are usually minimized and occasionally concealed if the patient is well hydrated. Third, these aberrations i...