Hoxa11 and Hoxd11 regulate branching morphogenesis of the ureteric bud in the developing kidney.

Hoxa11 and Hoxd11 are functionally redundant during kidney development. Mice with homozygous null mutation of either gene have normal kidneys, but double mutants have rudimentary, or in extreme cases, absent kidneys. We have examined the mechanism for renal growth failure in this mouse model and find defects in ureteric bud branching morphogenesis. The ureteric buds are either unbranched or have an atypical pattern characterized by lack of terminal branches in the midventral renal cortex. The mutant embryos show that Hoxa11 and Hoxd11 control development of a dorsoventral renal axis. By immunohistochemical analysis, Hoxa11 expression is restricted to the early metanephric mesenchyme, which induces ureteric bud formation and branching. It is not found in the ureteric bud. This suggests that the branching defect had been caused by failure of mesenchyme to epithelium signaling. In situ hybridizations with Wnt7b, a marker of the metanephric kidney, show that the branching defect was not simply the result of homeotic transformation of metanephros to mesonephros. Absent Bf2 and Gdnf expression in the midventral mesenchyme, findings that could by themselves account for branching defects, shows that Hoxa11 and Hoxd11 are necessary for normal gene expression in the ventral mesenchyme. Attenuation of normal gene expression along with the absence of a detectable proliferative or apoptotic change in the mutants show that one function of Hoxa11 and Hoxd11 in the developing renal mesenchyme is to regulate differentiation necessary for mesenchymal-epithelial reciprocal inductive interactions.

Differential expression and function of cadherin-6 during renal epithelium development.

The cadherin gene family encodes calcium-dependent adhesion molecules that promote homophilic interactions among cells. During embryogenesis, differential expression of cadherins can drive morphogenesis by stimulating cell aggregation, defining boundaries between groups of cells and promoting cell migration. In this report, the expression patterns of cadherins were examined by immunocytochemistry and in situ hybridization in the embryonic kidney, during the time when mesenchymal cells are phenotypically converted to epithelium and the pattern of the developing nephrons is established. At the time of mesenchymal induction, cadherin-11 is expressed in the mesenchyme but not in the ureteric bud epithelium, which expresses E-cadherin. The newly formed epithelium of the renal vesicle expresses E-cadherin near the ureteric bud tips and cadherin-6 more distally, suggesting that this primitive epithelium is already patterned with respect to progenitor cell types. In the s-shaped body, the cadherin expression patterns reflect the developmental fate of each region. The proximal tubule progenitors express cadherin-6, the distal tubule cells express E-cadherin, whereas the glomeruli express P-cadherin. Ultimately, cadherin-6 is down-regulated whereas E-cadherin expression remains in most, if not all, of the tubular epithelium. Antibodies generated against the extracellular domain of cadherin-6 inhibit aggregation of induced mesenchyme and the formation of mesenchyme-derived epithelium but do not disrupt ureteric bud branching in vitro. These data suggest that cadherin-6 function is required for the early aggregation of induced mesenchymal cells and their subsequent conversion to epithelium.

The regulation of kidney development: new insights from an old model.

The embryonic kidney is an excellent model system in which to address many fundamental issues in developmental biology. Inductive interactions are required for proliferation and differentiation of the ureter epithelium and kidney mesenchyme. Recent studies implicate a receptor-type tyrosine kinase as a target of inductive signals in the developing ureter. In the mesenchyme, the early induction response requires at least two transcription factors, WT1 and Pax-2. Through the integrated application of in vitro culture models and gene targeting methods, the molecular mechanisms underlying kidney morphogenesis are becoming clearer.

An assessment of serum and urine soluble interleukin-2 receptor concentrations during renal transplant rejection.

During rejection, renal transplant recipients have increased concentrations of soluble interleukin-2 receptors (sIL-2R) in their serum and urine. However, the clinical application of this measurement in the diagnosis of rejection or the assessment of treatment efficacy is limited by the variance of the measurement in sample populations. We examined the serum and urine sIL-2R concentrations in 20 renal transplant recipients, 12 of whom experienced 13 episodes of allograft rejection. There was no statistical difference in the mean serum sIL-2R concentration at the time of rejection compared with the baseline value (2,817 +/- 801 v 1,943 +/- 255 U/mL). By contrast, the urinary excretion rate, expressed as units of sIL-2R per milligram creatinine, was 26.2 +/- 6.4 compared with 14.2 +/- 2.5 (P < 0.05). Furthermore, when urinary sIL-2R was expressed as a fractional excretion (FE), both the absolute measurement (4.4% +/- 1.7%) and the percent increase (+245%) at the time of rejection provided the greatest degree of discrimination of rejection from those values during allograft stability (1.2% +/- .2% and +2.5%, respectively; P < 0.005). We conclude that (1) serum and urine sIL-2R concentrations are affected by a number of factors during rejection; (2) FE calculations of sIL-2R improve discrimination of rejection from graft stability; and (3) serial measurement of sIL-2R excretion may be a useful adjunct to the diagnosis of rejection and, possibly, the subsequent assessment of response to immunotherapy.

Serum and urine soluble interleukin-2 receptor in idiopathic nephrotic syndrome.

Although a cellular immune pathogenesis is suspected in idiopathic nephrotic syndrome of childhood (INS), there is scant direct evidence of in vivo immune activation. In order to investigate cytokine cascade activation in INS, soluble interleukin-2 receptor (sIL-2R) in plasma and urine was characterized and its levels measured in INS patients during relapse. Immunochemically detectable sIL-2R had a molecular mass of 35-46 kDa in both serum and urine and the molecule appears to be excreted intact; the pI was 5.05. INS patients had elevated serum sIL-2R levels compared with adult normal controls (845 +/- 97 vs. 373 +/- 47 U/ml, P = 0.001) and were significantly higher than previously published age-matched controls. Urinary excretion of sIL-2R was 47.2 +/- 13 U/mg creatinine in patients. Both the sIL-2R excretion rate and the fractional excretion of sIL-2R were positively correlated with the excretion of albumin (P = 0.02 and 0.002, respectively). These increased serum and urine levels occurred whether relapse was or was not associated with an intercurrent illness. We conclude that: (1) despite increased sIL-2R excretion during INS relapse, serum levels are significantly elevated; (2) while the elevated urinary levels could result from enhanced intrarenal production, they more likely reflect the increased serum levels; (3) the elevated sIL-2R levels support an immune pathogenesis in INS.

Deregulation of Pax-2 expression in transgenic mice generates severe kidney abnormalities.

The Pax genes comprise a family of transcription factors active in specific tissues during embryonic development and are associated with at least three developmental mutations in mouse and man. In the developing kidney, Pax-2 is expressed in the induced mesenchyme, in the ureter epithelium, and in early epithelial structures derived from the mesenchyme. Pax-2 expression is repressed upon terminal differentiation of the renal tubule epithelium, but persists in the undifferentiated epithelium of human Wilms' tumours. We have produced a dominant gain-of-function mutation in transgenic mice by deregulating the expression of the mouse Pax-2 gene. The data obtained with four independently derived transgenic embryos and with one transgenic line demonstrate that deregulated Pax-2 expression results in histologically abnormal and dysfunctional renal epithelium with properties similar to congenital nephrotic syndrome. Thus, repression of Pax-2 is required for normal kidney development and persistent expression of Pax-2 may restrict the differentiation potential of renal epithelial cells.

Restoration of kidney function after prolonged renal artery occlusion.

An 11-month-old child developed renal artery occlusion (RAO) and anuric renal failure following an unsuccessful transluminal renal artery angioplasty of a solitary kidney. Despite the prolonged period of anuria, kidney viability was suspected based upon preservation of kidney length and the absence of glomerulosclerosis. At 19 months of age, revascularization of the kidney was performed. During the 7 months following revascularization, renal function gradually improved so that dialysis was no longer necessary. This improvement occurred in spite of significant tubular atrophy. Kidney viability may have been preserved, despite prolonged ischemia, as a result of the decreased renal oxygen consumption that existed during subfiltration glomerular perfusion pressures. The low normal blood erythropoietin level may have reflected the lack of renal hypoxia. The ability of the kidney to adapt to chronic ischemia underscores the importance of considering vascular reconstruction in all patients with RAO despite a long period of non-function.

Genetic aspects of antibody responses in chickens to different classes of antigens.

Six breeding groups of chickens, each characterized by a different haplotype of the B blood group system, were challenged with different classes of antigens, namely Newcastle disease vaccine (ND), infectious bronchitis vaccine (IB), infectious bursal disease viral agent (IBD), Salmonella pullorum antigen (P), and sheep red blood cells (SRBC). Parents were challenged at 20 weeks of age, and their offspring were challenged at 3 weeks of age. Blood samples were taken from the parents at 1 week after challenge, and from the offspring at 1, 2, 3, and 4 weeks after challenge for determination of antibody titers to each antigen. The offspring were also challenged at 8 weeks of age in the wing-web with Rous sarcoma virus (RSV). Tumor scores were taken weekly on individual chickens for the next 10 weeks. There were significant differences (P less than .01) between breeding groups of parents for antibody titer responses to ND, IB, P, and SRBC. There were significant differences (P less than .05) between the breeding groups of offspring for antibody titer responses to ND, IB, IBD, P, and SRBC. There were significant (P less than .01) differences between the breeding groups in the accumulative tumor scores over the 10-week period. The lines that cause regression of Rous sarcomas (R-lines) were significantly (P less than .01) superior in resisting tumor growth to those lines that allow progressive growth of tumors (Pr-lines). The only antigen to which the R-lines gave significantly (P less than .01) higher titers of antibody responses than the Pr-lines was SRBC.

Ascorbic acid uptake in guinea pig intestinal mucosa.

Cellular accumulation of ascorbic acid was investigated in vitro in distal intestinal mucosa of guinea pig. With 14C-ascorbic acid present at 8 microM/L in the bathing media, tissue/media (T/M) concentration ratios of at least 5 were routinely achieved. Recently absorbed ascorbic acid appeared to be free in solution in the cellular fluid in that it diffused from tissue exposed to poisons with a disappearance half-time of approximately 10 minutes. Ascorbic acid uptake was highly dependent on the presence of sodium in the bathing media; total Tris substitution resulted in a 97% decrease in uptake. Also, metabolically depleted tissue did not accumulate ascorbic acid against a concentration gradient. Uptake of 14C-ascorbic acid from a bathing solution concentration of 8 microM/L was reduced 67% in the presence of 0.8 mM/L nonlabeled ascorbic acid. Recently absorbed 14C-ascorbic acid moved more rapidly back into the lumen when the luminal solution contained nonlabeled ascorbic acid (5 mM) than when it contained mannitol (5 mM). This demonstration of counter transport substantiates a carrier mechanism in the brush border.

Isolation of high and low molecular weight components from chicken sera that have Rous sarcoma virus neutralizing activity.

Blood sera components from Arkansas regressor line (R-line) and progressor line (Pr-line) chickens are compared for the first time for Rous sarcoma virus neutralizing activity. Sera was fractionated by Sephadex G-100 filtration into a high molecular weight fraction I (HMW-I) and a low molecular weight fraction II (LMW-II) component (HMW-I greater than 14,000 daltons, LMW-II less than 5,000 daltons). Both fractions from each line of chickens exhibit activity against Rous sarcoma virus (RSV) judged by a wing web assay. Both HMW-I (principally antibodies) and LMW-II neutralized RSV when obtained from hyperimmune R-chickens and Pr-chickens with large progressing tumors. However, HMW-I and LMW-II obtained from R- or Pr-chickens before challenge contain so RSV neutralizing activity. The novel low molecular weight fraction II disappeared from the sera of R-line chickens 2 weeks after tumor regression, whereas the HMW-I persisted after tumor regression.

The use of ultrasonography in the diagnosis of calculous gallbladder disease.

During a 12-month period from September 1976 to September 1977, 114 patients in a community hospital had ultrasonography as part of their diagnostic work-up for suspected gallbladder disease. While 65 per cent had an additional study, such as an oral cholecystogram or intravenous cholangiogram, 35 per cent had ultrasonography as the only study to make the diagnosis. All patients in this group had laparotomy and cholecystectomy to confirm or disprove the diagnosis of calculous gallbladder disease. The overall accuracy rate of ultrasonography for calculous gallbladder disease was 90 per cent, which compares favorably with the standard oral cholecystogram. Ultrasonography has some distinct advantages in certain clinical situations such as acute cholecystitis, jaundice, pancreatitis and pregnancy. A review of our clinical experience in the everyday use of ultrasonography for calculous biliary disease has been discussed, and guidelines for the use of ultrasonography as part of the diagnostic armamentarium for gallbladder disease are presented.

Acute mesenteric infarction.

Twenty-three cases of mesenteric infarction were reviewed retrospectively. Of note are high surgical mortality and frequent misdiagnosis. Patients are generally older than 60, and have severe, poorly localized pain and nonspecific physical findings. Laboratory studies of value include evidence of hemoconcentration and leukocytosis. Roentgenographic findings are equally nonspecific unless late in the course. Recommended operative procedures depend on the etiology of the infarction. Hyperalimentation may be of benefit early in the postoperative course to provide both nutrition and a chance for adaptation.

The interaction between Mycobacterium bovis (BCG) and genotype of chicken in increasing the percentage of regression of Rous sarcomas.

Four breeding groups of chickens were inoculated in the wing-web with Rous sarcoma virus at 8 weeks of age. Treated birds were given a single dose of live organisms of a mile strain of Mycobacterium bovis of variety Calmette Guerin (BCG) as a subcutaneous inoculation adjacent to the emerging tumor. Control birds received no BCG. The breeding groups of chickens included a line selected for ability to cause a high percentage of spontaneous regression of tumors, a susceptible line with a very low level of regression of tumors, and the two reciprocal crosses between these lines. Treatment with BCG greatly enhanced the percentage of regression in the line selected for regression and in the two reciprocal crosses, but was ineffective in the low regression line. Bursectomy of chicks from the low regression line did not permit BCG treatment to increase regression of Rous sarcomas.

Malignant hyperthermia associated with enflurane anesthesia.

Malignant hyperthermia is induced by potent inhalation anesthetics. Enflurane must be added to the list of those anesthetic agents (such as halothane and succinylcholine) that are associated with this condition. The patient in our study was a young woman with no history of prior exposure to general anesthetics, and no family history of complications following administration of anesthetics. The other possible causes of hyperthermia in the patient were investigated and eliminated, and the condition was finally associated with enflurane. Enflurane should not be used in patients with a family history of this rare but often lethal disorder.