A gene for familial juvenile nephronophthisis (recessive medullary cystic kidney disease) maps to chromosome 2p.

Familial juvenile nephronophthisis (NPH) is a chronic autosomal recessive kidney disease responsible for 15% of end stage renal failure in children. NPH is frequently (16% of cases) associated with Leber amaurosis (termed Senior-Løken syndrome, SLS). Linkage analyses, performed in 22 multiplex NPH families (18 without and 4 with ocular abnormalities), have localized the gene to a region between D2S48 and D2S51 on chromosome 2p. This was confirmed using adjacent microsatellite markers, one of which (AFM220ze3 at the D2S160 locus) gave a lod score of 4.78 at theta = 0.05 in the 18 families with isolated NPH, whereas the same marker excluded linkage with SLS. These results demonstrate linkage of the purely renal form of NPH to chromosome 2p, and suggest that there may be genetic heterogeneity between NPH and SLS.

A novel gene encoding an integral membrane protein is mutated in nephropathic cystinosis.

Nephropathic cystinosis, an autosomal recessive disorder resulting from defective lysosomal transport of cystine, is the most common inherited cause of renal Fanconi syndrome. The cystinosis gene has been mapped to chromosome 17p13. We found that the locus D17S829 was homozygously deleted in 23 out of 70 patients, and identified a novel gene, CTNS, which mapped to the deletion interval. CTNS encodes an integral membrane protein, cystinosin, with features of a lysosomal membrane protein. Eleven different mutations, all predicted to cause loss of function of the protein, were found to segregate with the disorder.

Structural and photochemical properties of organosilver reactive intermediates MeAg2(+) and PhAg2(+).

Although there is growing interest in silver promoted carbon-carbon bond formation, a key challenge in developing robust and reliable organosilver reagents is that thermal and photochemical decomposition reactions can compete with the desired coupling reaction. These undesirable reactions have been poorly understood due to complications arising from factors such as solvent effects and aggregation. Here the unimolecular decomposition reactions of organosilver cations, RAg(2)(+), where R = methyl (Me) and phenyl (Ph), are examined in the gas phase using a combination of mass spectrometry based experiments and theoretical calculations to explore differences between thermal and photochemical decompositions. Under collision-induced dissociation conditions, which mimic thermal decomposition, both PhAg(2)(+) and MeAg(2)(+) fragment via formation of Ag(+). The new ionic products, RAg(+•) and Ag(2)(+•), which arise via bond homolysis, are observed when RAg(2)(+) is subject to photolysis using a UV-vis tunable laser OPO. Furthermore, comparisons between the theoretical and experimental UV-vis spectra allow us to unambiguously determine the most stable structures of PhAg(2)(+) and MeAg(2)(+) and to identify the central role of the silver part in the optical absorption of these species. The new photoproducts result from fragmentation in electronic excited states. In particular, potential energy surface calculations together with the fragment charges highlight the role of triplet states in these new fragmentation schemes.

Quantitative determination of the size dependence of surface plasmon resonance damping in single Ag@SiO(2) nanoparticles.

The optical extinction spectra of single silver nanoparticles coated with a silica shell were investigated in the size range 10-50 nm. Measurements were performed using the spatial modulation spectroscopy technique which permits independent determination of both the size of the metal nanoparticle under study and the width of its localized surface plasmon resonance (LSPR). These parameters can thus be directly correlated at a single particle level for the first time. The results show a linear increase of the width of the LSPR with the inverse diameter in the small size regime (less than 25 nm). For these nanoparticles of well-controlled environment, this can be ascribed to quantum confinement of electrons or, classically, to increase of the electron surface scattering processes. The impact of this effect was measured quantitatively and compared to the predictions by theoretical models.

Deletions in the COL4A5 collagen gene in X-linked Alport syndrome. Characterization of the pathological transcripts in nonrenal cells and correlation with disease expression.

The type IV collagen alpha 5 chain (COL4A5) gene of 88 unrelated male patients with X-linked Alport syndrome was tested for major gene rearrangements by Southern blot analysis, using COL4A5 cDNA probes. 14 different deletions were detected, providing a 16% deletion rate in the COL4A5 gene in the patient population. The deletions are dispersed all over the gene with different sizes, ranging from 1 kb to the complete absence of the gene (> 250 kb) in one patient. In four patients with intragenic deletions, absence of the alpha 3 (IV) chain in the glomerular basement membrane was demonstrated by immunohistochemical studies. This finding supports the hypothesis that abnormalities in the alpha 5 (IV) chain may prevent normal incorporation of the alpha 3 (IV) chain into the glomerular basement membrane. Direct sequencing of cDNA amplified from lymphoblast mRNA of four patients with internal gene deletions, using appropriate combinations of primers amplifying across the predicted boundaries of the deletions, allowed us to determine the effect of the genomic rearrangements on the transcripts and, by inference, on the alpha 5 (IV) chain. Regardless of the extent of deletion and of the putative protein product, the 14 deletions occur in patients with juvenile-type Alport syndrome.

Performances of Wang-Landau algorithms for continuous systems.

The relative performances of different implementations of the Wang-Landau method are assessed on two classes of systems with continuous degrees of freedom, namely, two polypeptides and two atomic Lennard-Jones clusters. Parallel tempering Monte Carlo simulations serve as a reference, and we pay particular attention to the variations of the multiplicative factor f during the course of the simulation. For the systems studied, the Wang-Landau method is found to be of comparable accuracy as parallel tempering, but has significant difficulties in reproducing low-temperature transitions exhibited by the Lennard-Jones clusters at low temperature. Using a complementary order parameter and calculating a two-dimensional joint density of states significantly improves the situation, especially for the notoriously difficult LJ(38) system. However, while parallel tempering easily converges for LJ(31), we have not been able to get data of comparable accuracy with Wang-Landau multicanonical sampling.

Familial juvenile nephronophthisis.

Familial juvenile nephronophthisis (NPH) is an autosomal recessive interstitial nephritis leading to terminal renal failure around puberty. Associations with extrarenal symptoms have been reported, mainly with Leber amaurosis (termed Senior-Løken syndrome). By means of linkage analysis a gene NPH1 for the purely renal form of NPH has been localized to chromosome 2. Genetic heterogeneity has been shown between NPH and Senior-Løken syndrome and also within the group of isolated NPH cases. Further characterization of the NPH1 region led to the isolation of large homozygous deletions in approximately 70% of patients with NPH. The detection of these deletions by PCR represents a simple noninvasive method for precise diagnosis in the majority of patients suspected of having NPH.

Abnormal TSH, PRL and GH response to TSH releasing factor in chronic renal failure.

TSH, PRL and GH response to TSH releasing factor as well as basal T4 and T3 were evaluated in a group of patients with chronic renal failure undergoing chronic hemodialysis. Serum T4 and T3 were lower than normal. Basal TSH was normal as compared to control, but did not rise after TRF stimulation. Larger dosages of TRF did not correct this abnormal response. Basal PRL was higher than control and remained at the same level during the test. GH was stimulated by the TRF with a peak occurring 20 min after injection. This abnormal secretion was not blunted by T3 administration. TRF half-life measured in 3 patients was 4 min. These data indicate that 1) there is an abnormal response to TRF in chronic renal failure which does not seem to be due to an altered sensitivity to, or metabolism of TRF; and 2) there is an abnormal TSH secretion which may be responsible for the low T4 and T3 measured in these patients.

Inactive renin in infants and children: evidence for its physiological response to orthostasis in children.

The aim of this work was to investigate the presence of inactive renin (IR) in plasma of normal infants and children and nephrectomized children and to study the plasma IR response to stimulation of the renin-angiotensin system (orthostasis) in children. The study was performed in 10 normal infants (2 days to 1 yr old), 28 normal children (1-15 yr old), 8 nephrectomized children (8-14 yr old), and 7 normal adults (20-40 yr old). IR was calculated as the difference in renin activity in trypsin-treated (1500 micrograms/ml) plasma, e.g. total renin (TR), and in untreated plasma, e.g. active renin (AR). IR was not detectable in most infants in the supine position, but their AR values were high (8.8-30 ng/ml X h). Moreover, in some of these infants, trypsin appeared to degrade renin activity, since TR values were lower than AR values. IR was detectable in 3 infants and 27 children, but their AR values were in a lower range (0.3-10 ng/ml X h). Trypsin degradation of renin activity was not found in either children or adults. With increasing age (2 days to 40 yr), AR decreased while IR and the IR to TR ratio increased significantly (P less than 0.001). A significant (P less than 0.001) inverse relationship was found between the IR and AR values of subjects 2 days to 40 yr old. IR was detectable in all nephrectomized children and represented 25% of normal values, while AR was undetectable (less than 0.1 ng/ml X h). In children in the upright position, IR decreased and AR increased significantly (P less than 0.001) in a reciprocal manner. TR did not change. These data suggest 1) that trypsin degradation of renin activity and absence of trypsin-activated IR are specific to infants with high AR levels, and 2) that IR might be activated in vivo into AR, especially after changes in position in children. IR could be a prorenin playing a physiological role in children.

Rickets and alopecia with resistance to 1,25-dihydroxyvitamin D: two different clinical courses with two different cellular defects.

UNLABELLED: Two unrelated patients, aged 22 months and 31 months, with alopecia and rickets resistant to 1,25-dihydroxyvitamin D (1,25-(OH)2D] (vitamin D-dependency type II) presented with similar biochemical and radiologic features. They were treated with large doses of vitamin D3 derivatives [25-hydroxyvitamin D3 (25-(OH)D3), 1,25-(OH)2D3, and 1 alpha-hydroxyvitamin D3] for 28 months and 6 yr, respectively. In both patients, serum 1,25-(OH)2D levels remained high (approximately 10- to 100-fold normal) during the different therapeutic regimens. Circulating 1,25-(OH)2D and 24,25-dihydroxyvitamin D levels at various stages of the disease suggested in these children disturbances in the regulation of 25-hydroxyvitamin D (25(OH)D) 1 alpha- and 24-hydroxylase systems. In one child, all therapeutic trials were unsuccessful. Studies of her cultured skin fibroblasts showed low capacity (10% normal) for saturable (presumably receptor mediated) nuclear uptake of tritiated 1,25-(OH)2D3; the uptake process of nucleus associated 1,25-(OH)2D3 was normal in apparent affinity for 1,25-(OH)2D3 and in sedimentation velocity of nucleus-associated hormone. In the second child, correction of biochemical abnormalities, healing of rickets, and catch-up growth were obtained during similar therapeutic trials up to the age of 6 yr when a relapse occurred. This relapse has persisted for 2 yr in spite of similar or higher circulating concentrations of 25-(OH)D and 1,25-(OH)2D than those obtained previously when she was responsive to therapy. In her cultured skin fibroblasts, saturable high affinity nuclear uptake of 1,25(OH)2D was unmeasurable. IN CONCLUSION: 1) distinct patterns of clinical response can occur in patients with the syndrome of vitamin D-dependency type II, and can be associated with differing abnormalities in interaction of 1,25-(OH)2D3 with cultured skin fibroblasts; 2) aggravation of the resistance to 1,25-(OH)2D3 may occur during long term therapy in some patients.

Biological parameters in major depression: effects of paroxetine, viloxazine, moclobemide, and electroconvulsive therapy. Relation to early clinical outcome.

BACKGROUND: Clinical and pharmacologic studies report a relative or absolute serotonergic deficiency in major depression; however, the variability of clinical characteristics of illness has led to controversial results. In the present work, we looked for a possible relationship between i) biochemical values that indirectly reflect aminergic neurons activity and clinical characteristics and ii) their evolution and the early clinical outcome under antidepressive therapies (ATs). METHODS: Platelet serotonin content, platelet monoamine oxydase activity, and urinary biopterins were measured in 27 depressed patients before and during four different ATs (paroxetine, viloxazine, moclobemide, or electroconvulsive therapy). Depressive symptomatology and its evolution under ATs were quantified using three clinical rating scales. RESULTS: A severe symptomatology, high serotonin (5-HT) platelet content, and high or low urinary B could represent risk factors leading to a smaller or delayed response to an AT. Furthermore, the early improvement under ATs was negatively correlated to pretreatment 5-HT platelet content. CONCLUSIONS: Determination of 5-HT level could be useful in the choice of an AT.

Berger's disease in children. Natural history and outcome.

The clinical course and outcome of 91 children less than 15 years of age at onset and followed for at least 1 year have been retrospectively analyzed. The course has been characterized by recurrent macroscopic hematuria in 74 patients, by proteinuria-microscopic hematuria and a single episode of macroscopic hematuria occurring either at onset or a few months later in 8, by proteinuria-microscopic hematuria in 7, and by proteinuria only in 1. Lastly, one patient showed rapidly progressive renal failure. Four groups were identified by light microscopy: minimal glomerular changes (26), focal and segmental glomerulonephritis (41), pure mesangial proliferation (3) and proliferative glomerulonephritis with crescents (21). A good correlation was found between the glomerular lesions observed by light microscopy and the outcome. In this series we have not observed a dramatic clinical deterioration suggesting a transformation from one histologic type to another, as reported by others. None of the 70 patients belonging to the first three groups has impaired renal function but two with focal and segmental glomerulonephritis have developed hypertension. Although the clinical course is benign, many patients have, at the last observation, an abnormal urinalysis characterized by microscopic hematuria and/or mild proteinuria; the proteinuria is over 1 g/24 h in six patients with focal and segmental glomerulonephritis. Ten patients remained in clinical remission for several years, but mesangial IgA deposits were still present in the only patient who had a repeat biopsy while in remission. In contrast, none of the patients with proliferative glomerulonephritis with crescents has had a prolonged remission. Six patients developed terminal renal failure 0.7, 0.11, 2, 4, 8 and 10 years after onset. Two additional patients are in moderate chronic renal failure with hypertension 10 and 12 years after onset. Most children show a persistent nephropathy, (in five proteinuria is over 1 g/24 h), and two of them have developed hypertension. Therapeutic trials using drugs with side-effects should, therefore, be used only in this group of patients.

Plasma and muscle free amino acids in children at the early stages of renal failure.

Plasma and muscle free amino acid analyses have been performed on four groups of children with different levels of renal failure. Mean plasma creatinine of the groups 1 to 4 was respectively 1.3, 2.3, 3.3, and 4.9 mg/100 ml. Significant but different alterations of plasma and muscle amino acid pattern were found in the four groups of patients. In plasma, aspartic acid, citrulline, OH-proline, 1- and 3-methyl histidine were regularly increased, while threonine, valine, phenylalanine, isoleucine, leucine, tryptophane, tyrosine, and tyrosine/phenylalanine ratio were generally decreased. In muscle, glutamine was usually increased and alanine, valine and valine/glycine ratio decreased; significant increase of total amino acid content was only noted in group 4. Some amino acid alterations became worse with renal failure such as 3-methylhistidine increase or tyrosine/phenylalanine decrease, but group 3 patients had the greatest number of individual amino acid alternations. This group of patients also had the highest protein intake. Relationship between growth velocity and muscle amino acid pattern was found, a poor growth rate was associated with an increase of nonessential and essential amino acids with the exception of valine.

Optimal dietary substitution of racemic ketoanalogues for isoleucine in growing normal and uremic rats.

Dietary ketoanalogues (KAs) were shown to replace their essential amino acids with a 50% efficiency for valine and leucine. We determined the optimal concentration of the racemic KA of isoleucine (KMVA) in uremic and control rats: nutrition responses were compared between a diet containing optimal isoleucine concentration and diets containing various KMVA concentrations. Isomolar replacement of isoleucine produced anorexia, stunting, and poor nitrogen balance. Doubling KMVA partially improved these indices. Tripling KMVA lessened urea production and improved growth up to that obtained with the isoleucine diet in uremic but not in control rats (20% lower). A further KMVA increase produced no further benefit. Among plasma branched-chain amino acids, only alloisoleucine was affected; it increased with increasing KMVA concentration, being maximum after tripling KMVA. Racemic KMVA could replace isoleucine with a 35% efficiency but supported no growth acceleration in uremic rats and no maximal growth in control rats. Plasma alloisoleucine rose without adverse nutrition effects.

Efficiency of substitution of 2-ketoisocaproic acid and 2-ketoisovaleric acid in the diet of normal and uremic growing rats.

Effects of various intakes of the ketoanalogues of leucine (KICA) and valine (KIVA) on growth, nitrogen, and urea excretion were examined and compared to those of an optimal intake (A) of the corresponding amino acids. Diet KICA and KIVA contents varied from 1 to 4 times A. In controls, growth was significantly reduced with equimolar substitution, corrected with twice A, and unchanged at higher levels. Doubling KICA corrected growth except with substantial anorexia. In uremic rats fed KIVA, growth was corrected at twice A. Low-KICA diets reduced plasma-leucine level; higher KICA diets normalized plasma leucine and revealed branched-chain amino acid (BCAA) antagonism. Changes in 2-ketoacids were unrelated to those of BCAA. In uremia, KICA decreased plasma and urinary urea without changing nitrogen retention. Ketoacid substitution for amino acids was 50% efficient in normal rats and not altered by uremia. BCKAs, specifically KICA, could modify urea metabolism.

Insulin and growth hormone secretion in dialyzed children: influence of dietary manipulation.

The insulin and growth hormone responses to arginine and the growth hormone response to insulin were studied in 10 children undergoing chronic hemodialysis 1) under usual dietary prescription and 2) after 7 days of dietary manipulation (DM) decreasing mean carbohydrate intake from 48 to 36% and increasing lipid intake from 42 to 54% (percent of total energy) with the polyunsaturated/saturated fatty acids ratio being increased from 0.2 to 2. Mean fasting insulin and growth hormone were significantly decreased after DM: 10.3 +/- 3 muunits/ml and 19.9 +/- 3.5 ng/ml before and 4.3 +/- 0.8 muunits/ml and 9.3 +/- 2.4 ng/ml after DM. The mean arginine-induced insulin peak and the growth hormone peaks after arginine and insulin remained very high after DM. There was no decrease of mean plasma triglycerides: 214 +/- 30 mg/dl before and 237 +/- 26 mg/dl after DM. However, two children who had the greatest decrease in carbohydrate intake exhibited a decrease of triglycerides and of arginine-induced insulin secretion. The percent variation of insulin area after DM was significantly correlated with the percent variation of plasma triglycerides.

Craniosynostosis and kidney malformation in a case of Hennekam syndrome.

Hennekam syndrome is a rare autosomal recessive syndrome which was described for the first time in 1989. Here, we present a girl with intestinal lymphangiectasia, severe lymphedema of limbs, seizures, mild mental retardation, and facial anomalies consistent with the diagnosis of Hennekam syndrome. In addition, she had an ectopic kidney and craniosynostosis of the coronal suture, 2 manifestations not previously reported in this syndrome. While the molecular basis of Hennekam syndrome remains, as yet, unknown, this report illustrates its variable clinical expression.

Dark cells of cystinosis: occurrence in renal allografts.

Twenty-four biopsies of renal allografts, generally cadaveric, from 20 patients with cystinosis were examined by light, polarization, phase contrast, and electron microscopy. The unusual dark cells previously reported in the native kidneys and livers of patients with cystinosis were observed in 12 of the 24 biopsies. The cells were present in the interstitium in all of these 12 biopsies, in glomeruli in one biopsy, and in the tubular lumen in two biopsies. They were evident by light and electron microscopy in stained and unstained ultrathin sections, and could be discerned solely in Epon sections. The dark appearance resulted from the presence of dark, fine granular material in the cytoplasm and nucleus and in cytoplasmic inclusions. The cells were judged to be macrophages. They were present as early as 3 months following transplantation and bore no relationship to interstitial crystals or inflammation. The dark cells have two important implications: cystine storage may not be limited to lysosomes, and dark cells are a morphologic alternative to the traditional identifying configuration of cystine in tissues, namely crystals.

Enterovirus in sudden unexpected deaths in infants.

BACKGROUND: Conventional approaches to virus detection failed to provide convincing evidence of a viral etiology in sudden unexplained deaths in infants (SUDI). Many viruses may not have been detected by the routinely used methods; among them enteroviruses (EV) have seldom been found in SUDI. METHODS: In this study EV were sought directly in stools, in pharyngeal and tracheal samples and in myocardial and lung tissues, by using a nested PCR; they were also sought indirectly by detecting IgM antibodies with a new capture immunoassay. Twenty-four SUDI cases were divided into two groups: Group I, certainly associated with; or Group II, not associated with clinical, biologic or histologic signs of viral infection. RESULTS: EV were found in stools but their prevalence was not significantly different between Group I and Group II (20 and 22.2%, respectively). On the contrary EV were detected in respiratory tract and/or lung samples in 53.8% of infants of Group I and in none of Group II. Anti-EV IgM antibodies were detected in 55.5% of infants of Group I and in none of Group II. CONCLUSIONS: These results indicate that EV infection may be specifically associated with the subgroup of SUDI with viral signs, raising the question of its role in this condition.

Polarizability of KC60: evidence for potassium skating on the C60 surface

We present the first measurement of the polarizability and the permanent dipole moment of isolated KC60 molecules by molecular beam deflection technique. We have obtained a value of 2506+/-250 A(3) for the polarizability at room temperature. The addition of a potassium atom enhances by more than a factor of 20 the polarizability of a pure C60 molecule. This very high polarizability and the lack of observed permanent dipole show that the apparent polarizability of KC60 is induced by the free skating of the potassium atom on the C60 surface, resulting in a statistical orientation of the dipole. The results are interpreted with a simple model similar to the Langevin theory for paramagnetic systems.