Vitamin D-dependent calcium-binding proteins (CaBPs) in human fetuses: comparative distribution of 9K CaBP mRNA and 28K CaBP during development

The vitamin D-dependent calcium-binding protein (CaBP) cholecalcin or calbindin, has been used as a molecular marker of 1,25-dihydroxyvitamin D3 action. Mammals possess two CaBPs: a 9,000 mol wt (9K CaBP) and a 28,000 mol wt (28K CaBP). The distinct localization of each protein in the rat has been previously described with the aid of specific radioimmunoassays developed for each CaBP. Antibodies raised against the rat 28K CaBP can be used to detect this protein in a number of mammalian species including humans. In contrast, antibodies against rat 9K CaBP do not cross react with human 9K CaBP, but human 9K CaBP mRNA can be analyzed using a cDNA probe for rat 9K CaBP mRNA. Such a cross-hybridization between the rat cDNA probe and human CaBP mRNA was demonstrated by Northern analysis. We have documented the distribution and evolution of 28K CaBP and 9K CaBP mRNA in human tissues during fetal development from 14 to 32 wk of gestation. 28K CaBP was only present in kidney and cerebellum, and not detectable in duodenum. There was a 2-fold increase of 28K CaBP in the cerebellum between 14 and 24 wk of gestation. The 9K CaBP mRNA was unevenly distributed in human fetal tissues. 9K CaBP mRNA was present in classical vitamin D target tissues such as duodenum and placenta; high levels of 9K CaBP mRNA also were found in thymus and lung.(ABSTRACT TRUNCATED AT 250 WORDS)

Urinary excretion of N-acetyl-glucosaminidase and beta-2-microglobulin as early markers of gentamicin nephrotoxicity in neonates

A prospective study in 16 healthy and 16 gentamicin-treated neonates was undertaken to compare the urinary excretion of proximal tubular markers such as beta 2-microglobulin (beta 2-m) and total N-acetyl-beta-D-glucosaminidase (NAG) and its isoenzymatic form NAGB. beta 2-m excretion was not related to postnatal age in control full-term neonates; it was significantly increased in gentamicin-treated full-term neonates. The urinary excretion of the lysosomal markers, total NAG and NAGB, rose significantly with postnatal age in control group. fMean values for total NAG and NAGB were significantly higher in the treated group but the isoenzymatic profile (NAGB/total NAG X 100) was not modified by gentamicin treatment.

Histology and microradiography of early post-natal molar tooth development in vitamin-D deficient rats

The role of vitamin D on tooth-germ development was studied. The molars of vitamin D-deficient rats were compared with those of vitamin D-replete controls. The deficiency disturbed enamel and dentine mineralization and decreased their matrix secretion. Morphogenesis was affected; teeth were flattened and the whole of the epithelio-mesenchymal junction rippled. Where this irregularity was maximal, the inner dental epithelium and stratum intermedium were intermingled and the adjoining sub-odontoblast cells were mixed with poorly polarized odontoblasts. The cytodifferentiation of both central and sub-odontoblastic cells was inhibited. Thus vitamin D has a role in the early events of tooth development: morphogenesis, histodifferentiation and cytodifferentiation of pulp cells as well as in enamel and dentine mineralization.

Evidence for the presence of Calbindin-D 28K (CaBP-28K) in the tibial growth cartilages of rats

The distribution of the vitamin-D dependent calcium-binding protein (Calbindin-D 28K) (CaBP-28K) in the tibial growth plate cartilage of the rat has been studied immunohistochemically using an antibody raised against rat renal CaBP-28K. The protein was detected mainly in the nuclei of chondrocytes and occasionally in the juxtanuclear cytoplasm. The distribution was not uniform throughout the growth plate, but concentrated in the proliferatively active chondrocytes of the resting and proliferative zones. These findings raise the possibility that CaBP-28K may be involved in the mitotic activity of the chondrocytes, acting as a regulator of the proliferative process, perhaps via intranuclear calcium.

[Chronic renal insufficiency in the child. Etiology, development and prognosis]

Our study concerned 147 children with chronic renal failure (CRF) (creatinine clearance less than 50 ml/min/1.73 m2). Its goal was to analyse the distribution of primary renal diseases, natural history of renal failure (RF) according to etiology, and long term survival. Renal diseases responsible for RF were: malformations of the urinary tract (38%), glomerular pathology (26%), hereditary renal diseases (20%), isolated renal hypoplasias (11%), and miscellaneous (5%). Corticoresistant nephrosis accounted for 34% of glomerular diseases and nephronophtisis 63% of hereditary renal diseases. On the whole, RF was related with an uropathy or renal hypoplasia in half of cases and with congenital renal disease in almost 3/4 of cases. The natural history varied according to primary renal disease: slow deterioration after a period of relative stability for uropathy or renal hypoplasias, slow and regular deterioration for nephronophtisis, rapid deterioration for glomerular diseases.

[Optimum choice of antibiotic treatment in neonatal infections due to group B streptococci]

Morbidity and mortality among neonates with group B streptococcal infections remain high. As delays in bacterial killing may be responsible for these poor results, there is a need for studies into killing kinetics. We investigated antimicrobial sensitivity and killing effect time lags for penicillin, ampicillin and mezlocillin, alone and in combination with gentamicin or amikacin, against 20 strains of group B streptococci isolated in cultures of blood and cerebrospinal fluid from neonates. A culture of each strain (10(5) germs/ml) was exposed to the antibiotics individually or in combination. Antibiotics were used in the concentrations achieved clinically. Surviving bacteria were counted after 2 h 30, 4 h 30 and 24 h. incubation. Mean killing curves showed that the time interval until onset of a killing effect was 24 hours with either penicillin or ampicillin alone, against 4 h 30 with penicillin-amikacin or ampicillin-gentamicin. The most rapid killing effect (2 h 30) was observed with mezlocillin alone and ampicillin-amikacin. No antagonism was found between mezlocillin and aminoglycosides. Choice of the best antibiotic treatment for group B streptococcal infections should be based on both the rapidity of the in vitro killing effect and the antibiotic's diffusion into the site of the infection.

Vitamin-D-dependent calcium-binding protein (CaBP-9K) in rat growth cartilage

The presence of vitamin-D-dependent calcium-binding protein (CaBP-9K) in tibial growth-plate cartilage was immunohistochemically demonstrated using a specific antibody to rat duodenal CaBP-9K. The protein was found to be mainly localized in the cytoplasm of maturing chondrocytes. In hypertrophic chondrocytes, CaBP-9K concentrations decreased, and the protein was found in the cytoplasmic processes. No CaBP-specific immunoreactivity was seen in the hypertrophic chondrocytes of the lower calcified hypertrophic zone; in contrast, the protein was found in the extracellular lateral edges of longitudinal septa, i.e. where matrix vesicles are preferentially localized and where cartilage mineralization is initiated. These findings suggest that vitamin D has a direct function in this tissue. It also seems likely that CaBP-9K is an indicator of chondrocyte maturation, and that it is involved in the matrix vesicle-associated process of cartilage calcification.

Sequential echocardiographic study prior and during antihypertensive therapy in children with severe hypertension

This study was performed to assess myocardial involvement in 18 children with severe hypertension (HT), using two dimensional (2D) guided M mode echocardiography, prior and during therapy. All patients but 2 had renal or renovascular disease. Septal diastolic thickness (SDT) was utilized as a serial marker. Except for one case, all patients had increased SDT initially (1.03 +/- .26 cm/m2, p less than .01 vs normal). Evolution under therapy allowed subdivision of patients: Group I: 12 patients showed left ventricular (LV) hypertrophy regression, within a follow-up period of 20 +/- 9 months (final SDT: .78 +/- .12 cm/m2 vs initial 1.09 +/- .28, p less than .01). Blood pressure (BP) was normalized in 9 patients, and borderline in 3. Therapy consisted on acebutolol (n = 10), captopril (n = 1), and renal artery surgery (n = 1). Group II: LV hypertrophy was unchanged (n = 3) or increased (n = 3), within a follow-up period of 19 +/- 8 months, with persistent severe (n = 3) or mild (n = 3) HT, under acebutolol (n = 5). Treatment was changed to captopril with subsequent normal BP and echocardiogram improvement (n = 3). In the overall population, final SDT was significantly correlated to the final BP (r = .69, p less than .01). In conclusion, echocardiographic follow-up allowed serial non invasive assessment of LV hypertrophy in our severely hypertensive pediatric population. At first echocardiogram, LV hypertrophy was present in all patients but one. Antihypertensive therapy allowed simultaneous decrease of BP and LV hypertrophy in 12 patients, 10 under acebutolol.

[Value of chlormethine in children with corticoid-dependent or partially corticoid-sensitive nephrosis, in steroid poisoning]

Mechlorethamine was administered at a low dose (0.8 mg/kg) to 27 children presenting with steroid dependent or partially responsive nephrotic syndrome, with signs of steroid toxicity. This drug induced a fast decrease of proteinuria (average delay: 7 days). It led to long lasting remission (average follow-up 34 months) in 16 cases (59%). Relapse occurred in 11 children (41%) most often (9 of 11 cases) in the first 7 months. However the evolutive pattern was clearly improved in 5 of these cases. Altogether, mechlorethamine allowed to stop corticosteroid therapy or, at least, to reduce the given dose, with a decrease of the signs of steroid toxicity, in 78% of the cases. In 6 cases (22%) evolution was almost not improved. One may hope that this dosage of mechlorethamine will not be gonadotoxic. This should be checked later on.

Presence of immunoreactive vitamin D-binding protein in rat yolk sac endodermal cells

The visceral yolk sac is, in the rat, an organ which possesses true placental functions. We recently showed that yolk sac is involved in the control of metabolism and action of vitamin D in the fetoplacental unit, since its endodermal cells contain a 24-hydroxylase for vitamin D metabolites and the 1,25-dihydroxyvitamin D receptor. In the present work, by using indirect immunoperoxidase staining, we demonstrate that an immunoreactive vitamin D-binding protein (DBP) is present in this yolk sac throughout embryonic and fetal development. It is mainly located at the apex of the endodermal cells. Immunoprecipitation studies of radioactive proteins synthesized in vitro by yolk sac explants showed that yolk sac DBP, in contrast to alpha-fetoprotein, is not synthesized in situ by yolk sac. This result, combined with the location of DBP at the apex of the endodermal cells which face the uterus, strongly suggests that yolk sac DBP is of maternal origin. The concomitant presence in the endodermal cells of this DBP, of the 1,25-dihydroxyvitamin D receptor, and of the system hydroxylating vitamin D metabolites in position 24, certainly has considerable physiological significance.

Regulation of rat yolk sac 25-hydroxy- and 1,25-dihydroxyvitamin D3 24-hydroxylase activities

The yolk sac of the pregnant rat which functions as a true placenta is a target organ for vitamin D. This tissue can hydroxylate in position 24 both 25-hydroxy- and 1,25-dihydroxyvitamin D3 (25-OHD3 and 1,25-(OH)2D3). The present report describes an in vitro model for the study of 1,25-(OH)2D3 action on the further metabolism of 25-OH[3H]D3 and 1,25-(OH)2[3H]D3 by yolk sac. The tissue explants were preincubated with 1,25-(OH)2D3 for 18 h in a serum-free culture medium. Physiological concentrations of 1,25-(OH)2D3 were the most effective in stimulating (7.5-fold) the 1,25-(OH)2D3 24-hydroxylase, while the 25-OHD3 24-hydroxylase stimulation (4-fold) required a 1,25-(OH)2D3 concentration of 10(-7) M. The stimulating effect of 1,25-(OH)2D3 on the 1,25-(OH)2D3 24-hydroxylase was temperature-dependent, and, since its was inhibited by actinomycin D and cycloheximide, required de novo protein synthesis. 1,24,25-(OH)3D3, 25-OHD3, and 24,25-(OH)2D3 were 10- to 1000-fold less potent than 1,25-(OH)2D3 in inducing the 1,25-(OH)2D3 hydroxylase. Our results strongly suggest that 1,25-(OH)2D3 regulated the 1,25-(OH)2D3 24-hydroxylase by a receptor-mediated process. Furthermore, 1,25-(OH)2D3 at 10(-9) M induced within 4 h an increase of its own degradation and the formation of an as yet unidentified major 1,25-(OH)2[3H]D3 metabolite. We conclude that the yolk sac can participate in the regulation of 1,25-(OH)2D3 concentration in the fetoplacental unit.

[Molecular approach to the action of vitamin D in man]

Some applications to man of specific markers of the molecular action of vitamin D (1.25(OH)2D3 receptors and antibodies to hormone-dependent proteins (CaBP and cDNA] are reported in this study. On case of type II vitamin-dependent rickets was characterized by 1.25(OH)2D3 plasma level greater than 250 pg/ml and a ten-fold decrease of the number of binding sites of the hormone in cultured skin fibroblasts. We propose that CaBP 28K and/or 9K-containing cells, such as Purkinje's cells and chondroblasts may be targets for vitamin D action. Detection in fetuses, from the 20th week of gestation, of CaBP 9K messenger RNA in the duodenum and sternum and presence of CaBP 28K and 9K in the chondroblasts of the upper extremity of tibia, suggest that vitamin D acts on the nucleus of its target-cells during fetal development. Finally, discovery of the gene of CaBP 9K in man opens the prospect of studies which will improve the understanding of the mechanism of action of vitamin D.

Urokinase treatment of pulmonary artery thrombosis complicating the pediatric nephrotic syndrome

Two pediatric patients with severe pulmonary thrombosis complicating a lipoid nephrosis were treated with urokinase administered either as a continuous infusion or in massive bolus doses. Both patients recovered but one died suddenly 2 yr later after recurrence of the nephrotic syndrome and probably new massive pulmonary thrombosis. These patients had severe abnormalities of hemostasis and fibrinolysis, which favored thrombosis and complicated fibrinolytic treatment.

Impact of cefotaxime on the fecal flora in children

A differential quantitative analysis was used to study the effect of cefotaxime on the fecal flora in 26 hospitalized children ranging from two days to four years of age. Fecal specimens were obtained before, during and after therapy. This study was evaluated in comparison to 41 patients of the same age and from the same environment without antibiotic treatment or signs of infection. The fecal flora of the control group showed qualitative and quantitative stability. Two groups of species were distinguished: a group in which the upper limit was less than or equal to 10(7) bacteria/g of stool (Klebsiella, Enterobacter, other enterobacteria, Staphylococcus, Pseudomonas) and a group with less than or equal to 10(10) bacteria/g of stool (anaerobes, Escherichia coli, Streptococcus D). This stability of the control group of subjects allowed us to interpret the variations of microbial concentrations during and after cefotaxime treatment. In previous studies, we showed in the newborn a substantial risk of septicemia of intestinal origin when overgrowth occurred, especially with Klebsiella. With cefotaxime there was a decrease or a disappearance in 65% of E. coli and a slight decrease of Klebsiella and Enterobacter. This fact was of great interest in the treatment of endogenous secondary septicemia. We observed an appearance of Pseudomonas (nine Pseudomonas aeruginosa, two Pseudomonas putida, one Pseudomonas fluorescens) in 12 cases among the 26 children treated.(ABSTRACT TRUNCATED AT 250 WORDS)

Long-term outcome of children with malformative uropathies

125 cases of severe malformative uropathies, 42 urethral valves (V), 52 degree III vesicoureteral refluxes (VUR), 18 ureterovesical junction stenoses (UVJ), 13 pyeloureteral junction stenoses (PUJ), were studied for a period of 12 years. Based on the hypothesis that prognosis depends on the number of residual nephrons, we used the glomerular filtration rate (GFR) as our basic reference. 62% of our cases had an initial GFR below 50 ml/min/1.73 m2 and 30% had GFR's below 25. Early diagnosis and intervention are important for improvement of GFR. Of the 32% who improved, most were diagnosed in the first year of life, and the exceptional few after 2 years. The extent of initial renal damage is also a limiting factor. Improvement was rarely seen when the initial GFR was below 30 ml/min/1.73 m2. There was a correlation between the initial and final GFR levels. Renal degradation (28% of cases) is most influenced by follow up time. The average age of end stage renal failure (ESRF) onset was 11 years 4 months, but is earlier for V than for VUR. Onset is even earlier when initial damage is more severe. As normal GFR does not exclude later degradation of renal function, another indicator of the risk of this type of evolution should be adopted.

Lung mechanics in rachitic rats

Lung mechanics was studied at 50 days of age in 7 rachitic rats born from mothers deprived of vitamin D. They were compared with 7 control rats raised in the same conditions but fed a diet supplemented with vitamin D. The animals were anesthetized, tracheotomized, and paralyzed. Quasi-static pressure-volume curves of the respiratory system and of the lungs were obtained. Body weight of the rachitic rats was within the range of the control rats, but dry lung weight (LW) was significantly lower (p less than 0.01). Lung volumes in absolute terms and when normalized for LW were significantly lower than in the control rats. Chest wall compliance (Ccw) of the rachitic rats was within the range of values of the control rats, except for 2 animals with an infinite Ccw. Analysis of the pressure-volume curves of the lungs of the rachitic rats compared with those in the control animals showed a significant decrease in lung compliance (CL) and in CL/LW (p less than 0.01), indicating a decrease in lung distensibility. The more severe the rickets (according to microradiographic criteria of the tibia), the lower the CL/LW. It is speculated that decrease in lung distensibility may be related to abnormal lung growth caused by disturbed alveolar formation and lung connective tissue development. These abnormalities could be due to vitamin D deficiency acting on the growing lung, as on the growing bones, by a mechanism involving proteoglycans.

Hemolytic-uremic syndrome: an analysis of the natural history and prognostic features

Sixty-seven children with hemolytic-uremic syndrome (HUS) were admitted between 1974 and 1981. Of these, 52 (78%) were aged less than 3 years. All children had acute renal failure and 48 (72%) required peritoneal dialysis. The etiology in twenty cases varied from bacterial and viral infections (7 and 5 cases, respectively) to renal irradiation with chemotherapy (2) and preexisting glomerulopathy (1). 5 (7%) children died during the acute phase of the illness. Long-term follow-up (mean 3 years 3 months) of 56 cases showed that 37 children (60%) had so far experienced no functional sequelae and 8 (13%) only mild sequelae while 3 (5%) were on iterative hemodialysis, 3 had severe chronic renal failure and high blood pressure (HBP) and 5 (8%) had HBP and normal kidney function. While the recovery rate was approximately 60% in all age groups, the mortality rate and serious after-effects were twice as frequent (42%) in children over 3 years of age as in those less than 3. Renal histology (total of 37) showed 12 cases of cortical necrosis, 22 of glomerular thrombotic microangiopathy (TMA) and 3 arterial TMA. Prognosis was poor for all cases of arterial TMA and 58% of those exhibiting cortical necrosis.

[Influence of amoxicillin combined with clavulanic acid on the fecal flora in children]

The effect of an amoxycillin-clavulanic acid combination on the intestinal bacterial ecosystem was studied by differential quantitative analysis of the fecal flora in 11 hospitalized pediatric patients aged 8 months to 4 years. The antibiotic combination was given orally to 7 patients and intravenously to 4. The modifications in the intestinal flora are more important with oral route than intravenous route. After treatment, an increase in ampicillin-resistant E. coli with overgrowth of Klebsiella were found. Our previous studies have shown that this microbial overgrowth carries a risk of secondary septicemia. A strain of amoxycillin-resistant Serratia marcescens emerged but did not pullulate . The other aerobic or anaerobic bacteria were not significantly modified. Most strains which emerged after therapy remained susceptible to the combination. Yeasts emerged in two patients. Thus, the amoxycillin-clavulanic acid combination results in intestinal Klebsiella overgrowth, requiring monitoring of the intestinal bacterial ecosystem.

[Influence of cefoperazone on the fecal flora in children]

A differential quantitative study was used to evaluate the effects of parenteral cefoperazone upon children's fecal flora. Fecal specimens were obtained from 16 patients, before, during and after therapy. Cefoperazone therapy was associated with major changes in fecal flora. There was marked reduction or suppression to undetectable levels of Enterobacteria, Staphylococci and Streptococci in 13 patients. During therapy, yeasts were selected or acquired in 7 cases. 5 to 10 days after cefoperazone was discontinued, the fecal flora was virtually the same as before treatment. Thus, cefoperazone should prove very useful in the treatment of septicemia due to intestinal overgrowth.