Ectopic expression of LEAFY COTYLEDON1-LIKE gene and localized auxin accumulation mark embryogenic competence in epiphyllous plants of Helianthus annuus x H. tuberosus.

BACKGROUND AND AIMS: The clone EMB-2 of the interspecific hybrid Helianthus annuus x H. tuberosus provides an interesting system to study molecular and physiological aspects of somatic embryogenesis. Namely, in addition to non-epiphyllous (NEP) leaves that expand normally, EMB-2 produces epiphyllous (EP) leaves bearing embryos on the adaxial surface. This clone was used to investigate if the ectopic expression of H. annuus LEAFY COTYLEDON1-LIKE (Ha-L1L) gene and auxin activity are correlated with the establishment of embryogenic competence. METHODS: Ha-L1L expression was evaluated by semi-quantitative RT-PCR and in situ hybridization. The endogenous level and spatial distribution of free indole-3-acetic acid (IAA) were estimated by a capillary gas chromatography-mass spectrometry-selected ion monitoring method and an immuno-cytochemical approach. KEY RESULTS: Ectopic expression of Ha-L1L was detected in specific cell domains of the adaxial epidermis of EP leaves prior to the development of ectopic embryos. Ha-L1L was expressed rapidly when NEP leaves were induced to regenerate somatic embryos by in vitro culture. Differences in auxin distribution pattern rather than in absolute level were observed between EP and A-2 leaves. More precisely, a strong IAA immuno-signal was detected in single cells or in small groups of cells along the epidermis of EP leaves and accompanied the early stages of embryo development. Changes in auxin level and distribution were observed in NEP leaves induced to regenerate by in vitro culture. Exogenous auxin treatments lightly influenced Ha-L1L transcript levels in spite of an enhancement of the regeneration frequency. CONCLUSIONS: In EP leaves, Ha-L1L activity marks the putative founder cells of ectopic embryos. Although the ectopic expression of Ha-L1L seems to be not directly mediated by auxin levels per se, it was demonstrated that localized Ha-L1L expression and IAA accumulation in leaf epidermis domains represent early events of somatic embryogenesis displayed by the epiphyllous EMB-2 clone.

Breath analysis in patients with end-stage renal disease: effect of haemodialysis.

BACKGROUND: There is no agreement about exhaled nitric oxide (FE(NO)) and its change after haemodialysis (HD) in end-stage renal disease (ESRD) patients. To comprehensively assess NO production in the respiratory system, NO metabolites in exhaled breath condensate (EBC) needs to be measured in addition to FE(NO), taking into account the influence on these markers of airway pH, which may be regulated by ammonia (NH3+), present in large amounts in the breath of ESRD patients and removed by HD. STUDY DESIGN: FE(NO) and NO metabolites (NOx, NO2-,NO3- ), pH and NH3+ in EBC were measured in 12 ESRD patients, before and after HD. Twelve healthy subjects acted as controls. RESULTS: FE(NO )values of ESRD patients were similar to normals, while EBC-NOx, NO2-, NH3+ and pH were significantly higher in ESRD patients compared to normals (EBC-NOx 12.3, range 11.1-41.9 microm vs. 9.4, range 4.6-10.9 microm, P = 0.007; NO2- 4.70, range 1.17-8.22 microm vs. 0.90, range 0.72-1.17 microm, P = 0.023; NH3+ 2340, range 1325-3922 microm vs. 660, range 406-872 microm, P < 0.001; pH 7.16, range 6.82-7.44 vs. 6.60, range 6.42-6.76, P = 0.004, respectively). HD caused a mild significant decrease of FE(NO), and normalization of NH3+, NOx, NO2- and pH. A significant positive relationship between EBC-pH and EBC-NH3+ before and after HD (r(2) = 0.65, P = 0.000) was observed, explaining higher than normal EBC-pH before HD, while no relationship was found between EBC-pH and FE(NO) or NO metabolites. CONCLUSION: Oxidative stress, and not EBC-pH, is the most probable cause of increased NO metabolites in ESRD patients before HD.

High-performance liquid chromatographic determination of plasma glycolic acid in healthy subjects and in cases of hyperoxaluria syndromes.

A liquid chromatographic procedure for the determination of glycolic acid in plasma is proposed. The system is based on pre-column derivatization of the alpha-keto acid by means of phenylhydrazine, coupled with the enzymatic oxidation of glycolate to glyoxylate. The phenylhydrazone formed is separated by reversed-phase liquid chromatography and detected by UV absorption. The measured within and between-batch CV imprecision was 2.6 and 11.3%, respectively, at 5.68 mumol/l glycolate concentration; the analytical recovery was 102.0 +/- 7.3% and the minimum detectable concentration of glycolate was 0.3 mumol/l. The reference interval for plasma glycolate was 4.51 to 12.20 mumol/l (n = 14). Results of determinations of plasma samples from uremic patients, patients with type I primary hyperoxaluria and patients with chronic renal failure secondary to systemic oxalosis are reported.

High-performance liquid chromatographic assay for L-glyceric acid in body fluids. Application in primary hyperoxaluria type 2.

We describe a liquid chromatographic technique to determine L-glycerate in body fluids. The method is based on the derivatisation of the L-glycerate by incubation with lactate dehydrogenase and nicotinamide-adenine dinucleotide in the presence of phenylhydrazine. Oxidation of L-glycerate forms beta-hydroxypyruvate which is converted in turn into the related phenylhydrazone. The UV-absorbing derivative is determined using reversed-phase high performance liquid chromatography. The sensitivity was 5 mumol/l and 50 microliters of sample were required. The imprecision relative standard deviation was 4.5% and the recovery was 96.5 +/- 6.8% for L-glycerate in plasma. L-Glycerate concentrations in urine and plasma were less than 5 mumol/l in both normal individuals and patients with glycolic aciduria. In a patient with systemic oxalosis and normal plasma glycolate, plasma L-glyceric acid was 887 mumol/l.

High-performance liquid chromatographic microassay for L-glutamate:glyoxylate aminotransferase activity in human liver. Application in primary hyperoxaluria type 1.

A rapid and sensitive liquid chromatographic technique to determine L-glutamate:glyoxylate and aminotransferase (EC 2.6.1.4) activity in human liver is described. Homogenised tissue was incubated for 60 min in the presence of substrates and the 2-oxoglutarate generated was converted into the corresponding phenylhydrazone which was determined using reversed-phase high-performance liquid chromatography. The procedure allowed the detection of the enzyme activity expressed by 7.5 micrograms of liver protein, it was more sensitive and less time-consuming than the spectrophotometric procedure previously used. No significant differences were found between normal controls and patients with primary hyperoxaluria. In an 8-month-infant with primary hyperoxaluria type 1, the enzyme activity was reduced to 16% of the average control values.

High-performance liquid chromatographic microassay for L-alanine:glyoxylate aminotransferase activity in human liver.

We examine the suitability of a rapid and sensitive liquid chromatographic technique to determine L-alanine:glyoxylate aminotransferase (AGT) activity in human liver. Homogenised tissue was incubated for 30 min in the presence of substrates and the generated pyruvate was converted into the corresponding phenylhydrazone which was determined using reversed-phase high-performance liquid chromatography (HPLC). The procedure allowed the detection of the enzyme activity expressed by 10 micrograms of liver protein and was rapid enough resulting more sensitive and less time-consuming than the previous colorimetric one. We found that AGT activity in two hyperoxaluria type 1 patients was reduced as compared with controls. Also, cirrhotic patients had very low enzyme activities, even in the absence of detectable disorders of oxalate metabolism and this was ascribed to abnormal liver morphology. This may represent a misleading drawback if diagnosis of type 1 primary hyperoxaluria (PH1) uniquely relies on AGT assay.

Biochemical approach to diagnosis and differentiation of primary hyperoxalurias: an update.

The hyperoxaluria syndromes can be differentiated by the assessment of associated abnormalities in generation and urine excretion of metabolically related molecules. Based on the experience gained in our laboratory during the last decade, we have developed a comprehensive diagnostic work-up, which includes measurements of oxalate, glycolate and L-glycerate in plasma, urine and dialysis fluids, and an assay for AGT activity on liver biopsy. The availability of reliable assays for each of these parameters is indispensable for the recognition and differentiation of hyperoxalurias. Patients suspected to have abnormalities in oxalate metabolism are first screened by analysing spot urines and serum, and subsequently are subjected to more extensive studies using properly pre-treated blood samples and 24-hour urine collection. AGT activity, in the case of PH1, is assayed on few milligrams liver specimen by using a sensitive chromatographic procedure. Pertinent biochemistries will also assist in the long-term medical follow-up of these patients and in view of the choice of renal replacement or transplantation strategies.

Renal stones: from metabolic to physicochemical abnormalities. How useful are inhibitors?

Despite intensive studies in the last decades many aspects of nephrolithiasis still remain to be elucidated. Supersaturation with respect to lithogenic substances explains stones composed of cystine, uric acid, struvite, and calcium stones secondary to systemic diseases. In this subset there is a clear separation between patients and controls, and stone activity is well related to alterations in the physicochemistry of the urine environment. The understanding of the mechanisms of idiopathic calcium nephrolithiasis, on the other hand, is controversial, because we are still unable to establish clear-cut cause-effect relations between metabolic and physicochemical abnormalities and stone formation. Recent studies have been centered on the kidney, not only as the end organ of biochemical derangements due to systemic or environmental factors, but also as a complex laboratory where some events conduct to and others defend from lithogenesis. Many of these phenomena occur in the proximal tubule. Molecular biology has explained some types of hypercalciuria, which are due to genetic mutations altering tubular function, and similar results are expected for hypocitraturia and hyperoxaluria. The latter is conducive to stone formation through several mechanisms including supersaturation, oxidative stress on tubular cells, and interference with some natural inhibitors. The long list of inhibitors includes ionic and macromolecular moieties, some being produced within the nephron in response to lithogenic insults, and some affecting not only crystallization but also crystal cell adherence. Crystal trapping is believed to anticipate a renal stone. However, much has still to be clarified on their actual role in calcium nephrolithiasis, by what mechanisms they act, if patients and controls differ in the excretion and structure of some inhibitors, and whether differences are genetically determined.

Molecular analysis of the AGXT gene in Italian patients with primary hyperoxaluria type 1 (PH1).

Specimens were collected from 22 Italian patients with primary hyperoxaluria type 1 (PH1). Ten of them had already been analyzed by molecular biology. To clarify the molecular characteristics of the AGXT gene disease responsible for PH1, DNA samples were examined for known mutations by hybridisation of PCR products with Sequence Specific Oligonucleotides (PCR-SSO). We planned to identify new mutations of the AGXT gene by heteroduplex analysis followed by direct sequencing. We had already standardized a) the conditions for the amplification of the 11 exons of AGXT, b) the PCR-SSO technique and c) the heteroduplex analysis of amplified products. Preliminary results demonstrated that the AGXT mutations described in previous studies were found only in 40% of the examined Italian patients with PH1. The remaining 60% of mutations should be characterised in future studies.

Solubility and structure of N-carboxymethylchitosan.

N-Carboxymethylchitosan from crab and shrimp chitosans was obtained in water-soluble form by proper selection of the reactant ratio, i.e. using equimolar quantities of glyoxylic acid and amino groups. HPLC determinations of glyoxylic and glycolic acids, in conjunction with NMR analysis, permitted identification of the structure of the product, which is partly N-mono-carboxymethylated (0.3), N,N-dicarboxymethylated (0.3) and N-acetylated depending on the level of deacetylation of the starting chitosan (0.08-0.15). The preparation can be made successfully even in the presence of large concentrations of glycolic acid. The use of enzymes exerting hydrolysing activity on the high-molecular-weight fractions helps to avoid gel formation during storage and precipitate formation on addition of anti-microbial agents.

[Kinetics of oxalate in hemodialysis]. / Cinetica dell'ossalato in emodialisi.

Regular dialysis treatment (RDT) does not obviate hyperoxalemia of chronic renal failure (CRF). However, there is emerging evidence suggesting that current dialysis prescription is not always associated with progressive oxalate accumulation. In view of the controversy still concerning this issue we have investigated on plasma profiles and dialysis kinetics of oxalate in patients on RDT. Oxalate was determined by ion chromatography on serum ultrafiltrates and on the whole dialysate in 23 stable patients on RDT for end-stage renal failure unrelated to primary hyperoxaluria. Nine patients were on traditional hemodialysis (HD) and 14 on soft hemodiafiltration (HDF). Plasma profiles showed that dialysis patients were virtually always hyperoxalemic. Dialysis reduced plasma oxalate by more than 60%. There was a post-dialysis oxalate rebound averaging 9.6% at 30 minutes from the end of dialysis. Oxalate dialyzer clearances were mildly higher on HDF than on HD, and were lower than both urea and creatinine clearances, irrespective of the dialysis technique. Distribution space of oxalate was 21.5 1, that is 37.3% of dry body weight, and was quite similar to estimates obtained in normal subjects and in patients with CRF by alternative isotope dilution methods. Oxalate appearance rate averaged 337 +/- 69 mumol/24 h and was not different from the daily oxalate excretion assessed in 40 healthy subjects. Oxalate appearance was significantly related to urea generation and protein catabolic rates. From our results we conclude that, unless metabolic generation of oxalate is increased, current dialysis programs should prevent progressive oxalate accumulation in the majority of the patients.

[Mineral balance during hemodialysis and hemodiafiltration]. / Studio del bilancio minerale in emodialisi ed in emodiafiltrazione.

Keeping calcium (Ca) balance in equilibrium is one of the main goals in dialysis patients, and the dialysis schedule by itself can affect mineral metabolism. The aim of this paper is to evaluate Ca and magnesium (Mg) balances on different Quf in patients on RDT. Twenty-one patients [7 on hemodialysis (HD), 14 on hemodiafiltration (HDF)] were studied. Ca and Mg balances were assessed by measuring Ca and Mg in whole dialysis fluid. One patients on HDF was observed for three dialysis sessions, on different Quf, and negative values were observed for Quf above 70 ml/min. Mg balance was always negative. We conclude that an accurate survey of Ca balance is mandatory in high-efficiency dialysis, when high fluxes may produce adverse effects on mineral metabolism.

Care of the adult patients with cystic fibrosis.

Although no therapeutic breakthrough has taken place, the life expectancy of patients with cystic fibrosis (CF) has dramatically increased in the last 20 yrs. Nowadays, more than 80% of the patients outlive 18 yrs of age, with a mean survival age approaching 28 yrs. These favourable results are due mainly to early diagnosis and continuous treatment in specialized centres. The main therapeutic items are: prevention and early treatment of lung infections, mainly due to Pseudomonas aeruginosa, drainage of bronchial secretions (postural drainage, forced expiratory techniques, positive-expiratory-pressure mask, autogenic drainage,...), substitutive therapy with pancreatic enzymes and hypercaloric diet. Thus cystic fibrosis is increasingly a disease which involves adults, with many related problems, which span from the difficulties of prescribing an effective antibiotic therapy in cases with multiple resistances, to combining the need for a long daily physiotherapy schedule with school or a working life. Sexual problems and related psychological troubles are an important issue in the management of cystic fibrosis in adult patients, and are accordingly treated.

[LithoRisk: A software for calculating and visualising nephrolithiasis risk profiles]. / LithoRisk: software per il calcolo e la visualizzazione dei profili di rischio di calcolosi renale.

BACKGROUND: The pathogenesis of nephrolithiasis, based on the anomalies of the urinary environment, demands metabolic and physicochemical assessment for the medical management of patients. Standard metabolic protocols include the measurement of pertinent urine chemistry values and the calculation of the extent of saturation in stone-forming salts. However, patients are often given fragmentary and hard-to-consult reports and so this weakens the strength of the therapeutic recommendations. This paper introduces LithoRisk, a dedicated software which graphically represents risk profiles of stone formation, including the extent of saturation. METHODS: LithoRisk uses the results of 24-h urine chemistry values widely available in hospital laboratories, i.e., sodium, potassium, calcium, magnesium, ammonia, phosphate, sulphate, citrate, oxalate, chloride, pH and urine volume. Uric acid and cystine are optional. The relative supersaturation (beta), estimated according to our own ab initio calculation, is given in a scale whereby beta=1 is saturation, beta < 1 under - and beta > 1 oversaturation. LithoRisk is available as a CD-ROM and can be loaded on Windows 95/98/Millenium/XP. Colour or laser printers are suitable for printed records. RESULTS: LithoRisk is easily loaded on any PC by following video instructions. Once the loading of the program is completed a grey icon LithoRisk appears on the Desktop. The program can be opened by clicking twice on the icon. The patients data page first appears on the screen and is followed by the evaluation page for the input of variables. This generates the graph representing the diagnostic lithorisk profile, which is drawn as a line connecting different values, according to a specific scale and related to an arbitrary normal point. Normal values are shown as green lines, whereas abnormal ones are red. The beta values for calcium oxalate and phosphate, uric acid and cystine are instantaneously calculated and reported on the graph. CONCLUSIONS: LithoRisk produces a complete, unique and easy to understand report that includes all relevant parameters, it therefore expresses the overall risk of stone formation. It requires the results of chemistry tests done on the same 24-h urine collection, and carried out using suitable preservatives. If the tests for unusual parameters, i.e. sulphate and ammonia, are unavailable, one can use default values with minimal alterations on beta calculation. In spite of being arbitrary, the normal thresholds values are based on widely accepted literature data. The risk profile recognises the most relevant abnormalities and enables the establishment of individual targets aimed at reducing the propensity towards stone formation.

Primary hyperoxaluria: report of an Italian family with clear sex conditioned penetrance.

We report the clinical and genetic study of a primary hyperoxaluria type I (PH1) family with two sisters homozygous for p.Gly170Arg who are still asymptomatic at age 29 and 35, and two brothers, also homozygous for the same mutation, who are affected since age 27 and 30. The clear sex difference observed in this family and in others reported in the literature fits well with the prevalence of males over females in the Italian registry. In the KO model of PH1, only male mice develop renal stones, suggesting that the sex difference may affect both oxalate production and stone formation. A likely mechanism is the sex-related expression of glycolate oxidase shown in experimental animals. The stable isotope method recently developed by Huidekoper and van Woerden for in vivo assessment of the endogenous oxalate production could help to clarify the issue in humans.

High-performance liquid chromatographic microassay for methyl ethyl ketone in urine as the 2,4-dinitrophenyl-hydrazone derivative.

We report a high-performance liquid chromatographic procedure for determining methyl ethyl ketone in urine. The method is based on pre-column derivatization with 2,4-dinitrophenylhydrazine and liquid-liquid extraction of the derivative. The analyte is chromatographically separated from other urine constituents in less than 12 min and is detected by UV absorption at 360 nm. Peak height and concentration are linearly related. The relative standard deviation assessed for within-day imprecision was 3.2% at the 2.21 mg/l level. The mean analytical recovery from urines spiked with 1.0 mg/l ketone was 96.0 +/- 6.1%. The simple sample handling, the small volume of urine required and the short amount of time taken for the whole procedure make it suitable for routine biomonitoring of exposure to methyl ethyl ketone in industrial workers. The concentration in urine from nine non-exposed controls was less than 0.1 mg/l. The concentrations measured in urine samples from 60 exposed workers ranged from 0.1 to 1.1 mg/l and from 0.3 to 3.6 mg/l at the before- and the end-shift collections, respectively.

Rapid high-performance liquid chromatographic determination of urinary N-(1-methylethyl)-N'-phenyl-1,4-benzenediamine in workers exposed to aromatic amines.

A procedure has been developed for determining N-(1-methylethyl)-N'-phenyl-1,4-benzenediamine in urine by using high-performance liquid chromatography. The method uses chloroform extraction for partial clean-up of the urine sample. The separation is carried out on a reversed-phase column using 65 mmol/l aqueous ammonium acetate in acetonitrile (30:70, v/v) as the mobile phase. The column effluent is monitored at 290 nm with an ultraviolet detector. The analyte is separated from other normal urine constituents in less than 4 min. Peak height and concentration are linearly related. Coefficients of variation assessed for within-day reproducibility were 5.9 and 3.7% at concentrations of 22.3 and 92.1 micrograms/l, respectively. The mean analytical recovery from urine samples spiked with known amounts of amine was 89.7 +/- 6.8%. The request of only a small volume of urine and the simple pre-treatment procedure makes it suitable for the routine monitoring of the exposure of rubber vulcanization workers to aromatic amines.

Ion-chromatographic determination of L-tartrate in urine samples.

We propose using ion chromatography to determine tartrate concentration in urine. A 100-microL sample of urine is diluted and injected into the chromatograph. Tartrate is eluted within 11.5 min as a distinct and well-resolved peak. The sensitivity of the standard procedure (signal-to-noise ratio, 3/1) is 30 mumol/L. The intra-run and interrun coefficients of variation are 2.5% and 4.1%, respectively. Mean analytical recovery of known amounts of added tartrate ranges between 94.2% and 104.0%. We investigated the specificity of the procedure by analyzing urine containing added dicarboxylic acids structurally related to tartrate. The reliability of the procedure makes it suitable for investigating tartrate metabolism, e.g., the potential role of tartrate as an inhibitor of crystallization in calcium nephrolithiasis.

The clinical significance of assessment of serum calcium oxalate saturation in the hyperoxaluria syndromes.

Estimating calcium oxalate saturation (beta CaOx) in body fluids is proposed as a simple and reproducible procedure to assess the risk of systemic oxalosis in several clinical conditions associated with oxalate retention. beta CaOx was computerized from the measured concentrations of main serum ions. Accurate assay of serum oxalate was crucial for reliability of beta CaOx estimates. However, beta CaOx also depended upon changes of calcium and magnesium concentrations. Patients with end-stage renal failure (ESRF) due to primary or enteric hyperoxaluria had beta CaOx greater than saturation, whereas this happened in only 10 of 25 and two of 24 of those with oxalosis-unrelated ESRF. Bony content of oxalate measured in some of these patients was consistent with these results. In patients with maintained renal function beta CaOx was inversely related to glomerular filtration rate, but the slope was steeper in patients with than in those without hyperoxaluria and beta CaOx reached saturation at earlier stages of renal insufficiency.