Potential relationship between genotype and clinical outcome in propionic acidaemia patients

Propionic acidaemia (PA) is an autosomal recessive disorder caused by mutations in either of the PCCA or PCCB genes which encode the alpha and beta subunits, respectively, of the mitochondrial enzyme propionyl-CoA carboxylase (PCC). In this work we have examined the biochemical findings and clinical outcome of 37 Spanish PA patients in relation to the mutations found in both PCCA and PCCB genes. We have detected 27 early-onset and 101 late-onset cases, showing remarkably similar biochemical features without relation to either the age of onset of the disease or the defective gene they have. Twenty-one of the patients have so far survived and three of them, now adolescents, present normal development. Different biochemical procedures allowed us to identify the defective gene in 9 PCCA deficient and 28 PCCB deficient patients. Nine putative disease-causing mutations accounting for 77.7% of mutant alleles were identified among PCCA deficient patients, each one carrying a unique genotypic combination. Of PCCB mutant alleles 98% were characterised. Four common mutations (ins/del, E168K, 1170insT and A497V) were found in 38/52 mutant chromosomes investigated, whereas the remainder of the alleles harbour 12 other different mutations. By examining the mutations identified both in PCCA and PCCB genes and the clinical evolution of patients, we have found a good correlation between certain mutations which can be considered as null with a severe phenotype, while certain missense mutations tend to be related to the late and mild forms of the disease. Expression studies, particularly of the missense mutations identified are necessary but other genetic and environmental factors probably contribute to the phenotypic variability observed in PA.

Usefulness of pleural complement activation products in differentiating tuberculosis and malignant effusions

OBJECTIVE

To determine whether measurement of the complement activation products SC5b-9 and C3a-desArg in pleural fluid can reliably differentiate tuberculous from malignant pleural effusions.

DESIGN

Twenty-four patients with tuberculous pleuritis, 29 with malignant pleural effusion, and 30 control subjects with transudates were enrolled in the study. SCSb-9 and C3a-desArg were measured in pleural fluid using commercial ELISA tests, and their performances were evaluated using receiver operating characteristic (ROC) analysis.

RESULTS

Patients with tuberculous pleuritis had higher mean levels of pleural SC5b-9 (5052 microg/L) and C3a-desArg (7436 microg/L) than those with malignant effusions (1048 and 2835 microg/L, respectively), whereas only SC5b-9 concentrations in the latter were comparable with controls. The area under the ROC curve (AUC) was 0.84 for SC5b-9 and 0.81 for C3a-desArg. Pleural SC5b-9 showed an accuracy of 80.8%, compared with 78.8% for C3a-desArg, when cut-off points of 1500 and 4500 microg/L, respectively, were used. Using a stepwise logistic regression model, the combination of pleural SCSb-9 > or =1500 microg/L, age < or =35 years, and pleural monocyte percentage > or =90% provided the highest accuracy for tuberculous pleurisy (88.5%, AUC 0.95).

CONCLUSION

This pilot study suggests that pleural SC5b-9 is clinically useful for differentiating tuberculous and malignant pleural effusions.

Overview of mutations in the PCCA and PCCB genes causing propionic acidemia

Propionic acidemia is an inborn error of metabolism caused by a deficiency of propionyl-CoA carboxylase, a heteropolymeric mitochondrial enzyme involved in the catabolism of branched chain amino acids, odd-numbered chain length fatty acids, cholesterol, and other metabolites. The enzyme is composed of alpha and beta subunits which are encoded by the PCCA and PCCB genes, respectively. Mutations in both genes can cause propionic acidemia. The identification of the responsible gene, previous to mutation analysis, can be performed by complementation assay or, in some instances, can be deduced from peculiarities relevant to either gene, including obtaining normal enzyme activity in the parents of many patients with PCCB mutations, observing combined absence of alpha and beta subunits by Western blot of many PCCA patients, as well as conventional mRNA-minus result of Northern blots for either gene or beta subunit deficiency in PCCB patients. Mutations in both the PCCA and PCCB genes have been identified by sequencing either RT-PCR products or amplified exonic fragments, the latter specifically for the PCCB gene for which the genomic structure is available. To date, 24 mutations in the PCCA gene and 29 in the PCCB gene have been reported, most of them single base substitutions causing amino acid replacements and a variety of splicing defects. A greater heterogeneity is observed in the PCCA gene-no mutation is predominant in the populations studied-while for the PCCB gene, a limited number of mutations is responsible for the majority of the alleles characterized in both Caucasian and Oriental populations. These two populations show a different spectrum of mutations, only sharing some involving CpG dinucleotides, probably as recurrent mutational events. Future analysis of the mutations identified, of their functional effect and their clinical relevance, will reveal potential genotype-phenotype correlations for this clinically heterogeneous disorder.

Liquid chromatographic determination of fenbendazole residues in pig tissues after treatment with medicated feed

Fenbendazole (FBZ) is an anthelmintic widely used in farm animals to treat parasitic infestations. In pigs, it is administered in the food. The aim of this study was to validate an analytical method for the determination of FBZ and its metabolites in pig tissues. This method is based on oxidation of FBZ and its sulfoxide metabolite to the sulfone metabolite (FBZSO2). The limit of quantitation for this method is 20 ng FBZSO2/g for all tissues. The maximum residue limits (MRLs) established for FBZ and its metabolites in pig tissues are 50 ng/g for muscle, fat, and kidney and 500 ng/g for liver. This method is based on a liquid-liquid extraction followed by an oxidation with peracetic acid and a cleanup procedure based on 2 liquid-liquid extractions. Determination is achieved by high-performance liquid chromatography with ultraviolet detection. The present method is adjusted to the MRL established for FBZ and its metabolite residues. The analysis of the residues shows that after 72 h posttreatment, no FBZSO2 was detected in muscle, fat, and kidney and that liver levels were below the MRL.

Thiamphenicol disposition in pigs

Pharmacokinetic parameters of thiamphenicol (TAP) were determined after intravenous (i.v.) and intramuscular (i.m.) administration of 30 mg kg-1 of TAP in pigs. Plasma drug concentrations were determined by high performance liquid chromatography (HPLC) Intravenous TAP kinetics were fitted to a bi-exponential equation, with a first rapid disposition phase followed by a slower disposition phase. Elimination half-life was short, at 59.3 (29.4) minutes; volume of distribution at steady state was 0.62 (0.24) 1 kg-1; and plasma clearance was 13.4 (4.5) ml min-1 kg-1. After i.m. administration, the peak plasma concentration (Cmax= 4.1 microg ml-1) was reached in about 60 minutes; these concentrations are lower than those reported in other species. The TAP elimination half-life after i.m. administration, 250.2 (107.1) minutes was longer after than i.v. administration, probably due to the slow rate of absorption from the muscle. The mean bioavailability value for i.m. administration was 76 (12) per cent.

A new beta 2 microglobulin mutation found in a melanoma tumor cell line

Beta2 microglobulin mutations are an important mechanism for HLA class I total loss, (phenotype No. I) and have been described in colon carcinomas, melanomas and lymphomas. We describe a new beta2 microglobulin mutation detected in the melanoma cell line GR-34. The new mutation reported here was identified as a deletion of 4 bases (TTCT) in the highly repetitive sequence CTCTCTCTTTCT located in the leader sequence of the beta2 microglobulin gene at codon 15-16 of exon 1. The mutation produces a frameshift in the open reading frame sequence with the appearance of a stop codon at position 42. We also demonstrate that the second beta2 microglobulin gene is deleted. Comparisons with beta2 microglobulin mutations in other tumor cell lines suggest a mutation hot spot in exon 1.

Feasibility of DNA based methods for prenatal diagnosis and carrier detection of propionic acidaemia

Propionic acidaemia (PA) is an autosomal recessive disease caused by a genetic deficiency of propionyl-CoA carboxylase (PCC). Defects in the PCCA and PCCB genes that code for the alpha and beta subunits of PCC, respectively, are responsible for PA. A proband with PA was previously shown to carry the c1170insT mutation and the private L519P mutation in the PCCB gene. Here we report the prenatal diagnosis of an affected fetus based on DNA analysis in chorionic villus tissue. We have also assessed the carrier status in this PCCB deficient family, which was not possible with biochemical analysis.

Genetic and phenotypic aspects of phenylalanine hydroxylase deficiency in Spain: molecular survey by regions

We present an extensive study of the genetic diversity of phenylalanine hydroxylase deficiency in the Spanish phenylketonuria population. We have analysed 195 PKU patients by DGGE analysis identifying 67 different mutations which represent 89% of the total mutant chromosomes. Seventeen mutations first described in Spain have not yet been detected elsewhere; ten of these are reported here for the first time. The clinical significance of this high genetic heterogeneity was examined by analysing the genotype-phenotype correlations, mainly focusing on the mild hyperphenylalaninaemia (MHP) phenotype. The genotypes found in a group of 93 MHP patients, the largest analysed so far, are described in detail, as well as the relative frequencies of the MHP mutations identified. From the total pool of mutations, 27 can be considered severe, 18 can be defined as mild and 13 as associated with MHP. The prevalent mutations correspond to one severe mutation (IVS10nt-11), one MHP mutation (A403V) and two mild mutations (165T and V388M). The high frequency of mutations with a low degree of severity can explain the relatively higher prevalence of MHP and mild PKU phenotypes in Spain compared with NOrthern European populations. We have looked at the geographical distribution in Spain of the more common mutations, finding evidence of local mutation clustering, which could be the result of differences in the ethnic background and/or of genetic drift within each region.

Genetic heterogeneity in propionic acidemia patients with alpha-subunit defects. Identification of five novel mutations, one of them causing instability of the protein

The inherited metabolic disease propionic acidemia (PA) can result from mutations in either of the genes PCCA or PCCB, which encode the alpha and beta subunits, respectively, of the mitochondrial enzyme propionyl CoA-carboxylase. In this work we have analyzed the molecular basis of PCCA gene defects, studying mRNA levels and identifying putative disease causing mutations. A total of 10 different mutations, none predominant, are present in a sample of 24 mutant alleles studied. Five novel mutations are reported here for the first time. A neutral polymorphism and a variant allele present in the general population were also detected. To examine the effect of a point mutation (M348K) involving a highly conserved residue, we have carried out in vitro expression of normal and mutant PCCA cDNA and analyzed the mitochondrial import and stability of the resulting proteins. Both wild-type and mutant proteins were imported into mitochondria and processed into the mature form with similar efficiency, but the mature mutant M348K protein decayed more rapidly than did the wild-type, indicating a reduced stability, which is probably the disease-causing mechanism.

Pharmacokinetics of thiamphenicol in dogs

OBJECTIVE

To determine pharmacokinetic parameters of thiamphenicol (TAP) after IV and IM administration in dogs.

ANIMALS

6 healthy 2- to 3-year-old male Beagles.

PROCEDURE

IN a crossover design study, 3 dogs were given TAP IV, and 3 dogs were given TAP IM, each at a dosage of 40 mg/kg of body weight. Three weeks later, the same dogs were given a second dose by the opposite route. At preestablished times after TAP administration, blood samples were collected through a catheter placed in the cephalic vein, and TAP concentration was determined by use of a high-performance liquid chromatography. Results-Kinetics of TAP administered IV were fitted by a biexponential equation with a rapid first disposition phase followed by a slower disposition phase. Elimination half-life was short (1.7+/-0.3 hours), volume of distribution at steady state was 0.66+/-0.05 L/kg, and plasma clearance was 5.3+/-0.7 ml/min/kg. After IM administration, absorption was rapid. Peak plasma concentration (25.1+/-10.3 microg/ml) was reached about 45 minutes after drug administration. The apparent elimination half-life after IM administration (5.6+/-4.6 hours) was longer than that after IV administration probably because of the slow absorption rate from the muscle. Mean bioavailability after IM administration was 96+/-7%.

CONCLUSION

The pharmacokinetic profile of TAP in dogs suggests that it may be therapeutically useful against susceptible microorganisms involved in the most common infections in dogs, such as tracheobronchitis, enterocolitis, mastitis, and urinary tract infections.

Human propionyl-CoA carboxylase beta subunit gene: exon-intron definition and mutation spectrum in Spanish and Latin American propionic acidemia patients

Propionyl-CoA carboxylase (PCC) is a mitochondrial biotin-dependent enzyme composed of an equal number of alpha and beta subunits. Mutations in the PCCA (alpha subunit) or PCCB (beta subunit) gene can cause the inherited metabolic disease propionic acidemia (PA), which can be life threatening in the neonatal period. Lack of data on the genomic structure of PCCB has been a significant impediment to full characterization of PCCB mutant chromosomes. In this study, we describe the genomic organization of the coding sequence of the human PCCB gene and the characterization of mutations causing PA in a total of 29 unrelated patients-21 from Spain and 8 from Latin America. The implementation of long-distance PCR has allowed us to amplify the regions encompassing the exon/intron boundaries and all the exons. The gene consists of 15 exons of 57-183 bp in size. All splice sites are consistent with the gt/ag rule. The availability of the intron sequences flanking each exon has provided the basis for implementation of screening for mutations in the PCCB gene. A total of 56/58 mutant chromosomes studied have been defined, with a total of 16 different mutations detected. The mutation spectrum includes one insertion/deletion, two insertions, 10 missense mutations, one nonsense mutation, and two splicing defects. Thirteen of these mutations correspond to those not described yet in other populations. The mutation profile found in the chromosomes from the Latin American patients basically resembles that of the Spanish patients.

Determination of indomethacin residues in poultry by high-performance liquid chromatography

A HPLC method using a C18 column and UV detection (254 nm) is described for the determination of indomethacin residues in chicken tissues (liver, muscle and fat). Drug extraction from tissue homogenate in phosphate buffer (pH 3.5) was performed with dichloromethane. Mobile phase was acetonitrile-acetic acid (0.5% in water) (50:50). Indomethacin detection limit was 20 ng/g for the studied tissues. After administration of an oral dose of indomethacin (2 mg/kg), only three of the eight poultry studied showed drug tissue levels, in those cases the levels were below 50 ng/g.

Three novel splice mutations in the PCCA gene causing identical exon skipping in propionic acidemia patients

Propionyl-CoA carboxylase (PCC) is a mitochondrial, biotin-dependent enzyme involved in the catabolism of branched chain amino acids, odd chain fatty acids, and other metabolites. PCC consists of non-identical subunits, alpha and beta, encoded by the PCCA and PCCB genes, respectively. Inherited deficiency of PCC due to mutations in either the PCCA or the PCCB gene results in propionic acidemia (PA), a clinically heterogeneous disorder with a severe, often lethal, neonatal form, and a mild, later onset form. To characterize PCCA gene mutations responsible for PCC deficiency, we analyzed RT-PCR products obtained from cultured fibroblasts from Spanish PCC-alpha deficient patients. In three patients, smaller than normal PCR products were observed, and sequence analysis revealed the deletion of a 54-bp exon in the cDNA. Sequencing of genomic DNA from these three patients led to the identification of three novel mutations in the PCCA gene, two short deletions and one small insertion, adjacent to short direct repeats, and all of them affecting the consensus splice sites of the skipped exon. These mutations, 1771IVS-2del9, 1824IVS+3del4, and 1824IVS+3insCT, are the cause of the aberrant splicing of the PCCA pre-mRNA and result in an in-frame deletion of 54 nucleotides in the cDNA, probably leading to an unstable protein structure which is responsible for the lack of activity leading to PCC deficiency in these patients.

Determination of cloxacillin in milk and blood of dairy cows by high-performance liquid chromatography

A rapid and sensitive high-performance liquid chromatographic method is described for the determination of cloxacillin residues in milk and serum. Only a clean-up step after deproteinization is necessary before the analysis. The chromatographic system involves the use of a C18 column and ultraviolet absorbance detection at 225 nm. The mobile phase was acetonitrile-0.02 M KH2PO4 (21:79) at pH 5. Recoveries for cloxacillin were 83.5 and 75.7% in serum and milk, respectively. Detection limits (10 ng/ml in milk and 50 ng/ml in serum) were below the stipulated European Union maximum residue limits for cloxacillin. Thus, the described method showed the same accuracy, precision and sensitivity as the microbiological assays but without interferences caused by other drugs commonly used in therapy. Analysis of different blood and milk samples obtained at different times from dairy cows treated with an intramammary dose of cloxacillin benzatine showed undetectable cloxacillin levels both in milk and blood samples.

Iontophoresis for anesthesia during pulsed dye laser treatment of port-wine stains

Port-wine stains (PWS) are benign, congenital vascular malformations found in approximately 0.3% of newborns. PWS may be effectively treated with the flashlamp pulsed dye laser (FPDL) at 585 nm. However, laser therapy of vascular lesions often produces pain. We performed a prospective double-blind, placebo-controlled evaluation of the iontophoresis of lidocaine 5% with epinephrine 1:50,000 and mepivacaine 2% with epinephrine 1:50,000. Thirty-six patients with facial PWS were included in the study; 13 of them were treated with lidocaine 5% with epinephrine, another 13 were treated with mepivacaine 2% with epinephrine, and the other 13 were treated with preservative-free 0.9% NaCl. The pain was graded by the patient on a visual analog scale from 0 to 10, comparing the iontophoretically treated area with an adjacent area treated without anesthesia. Pain evaluation by patients demonstrated a significant decrease in the pain of pulsed dye laser impulses using the iontophoresis of lidocaine 5% with epinephrine. No change in the efficacy of pulsed dye laser treatment of PWS or important side effects were observed in our patients. Iontophoresis of lidocaine 5% with epinephrine is a safe and effective method of local anesthesia for pulsed dye laser and it is more effective than the iontophoresis of mepivacaine 2% with epinephrine.

Relationship between mutation genotype and biochemical phenotype in a heterogeneous Spanish phenylketonuria population

Genotyping of the phenylalanine hydroxylase (PAH) gene offers a new tool for characterizing patients with phenylketonuria (PKU), refining the diagnosis and aiding in the prediction of the clinical outcome and in the implementation of a more adequate treatment. The primary goal of this work was the detailed study of the different allele combinations and the metabolic phenotypes in Spanish PKU patients in order to understand better the clinical heterogeneity of PAH deficiency in our population. The results show that the disease phenotype is a consequence of a combination of mutations at the PAH locus and this observation is valid throughout the spectrum of clinical and biochemical varieties found in Spanish PKU patients. A stronger correlation was found between the predicted residual activity, when known from previous in vitro studies of the mutant proteins, and the Phe tolerance than between the predicted residual activity and the inverse of Phe levels at diagnosis. The observed genotype-phenotype correlations and the available data on the in vitro residual activity of the mutant proteins has enabled the estimation of the severity of most of the mutations found in Spain. This study includes relevant data for clinicians and pediatricians adding to the present knowledge which relates allelic PAH genotypes to biological phenotypes.

Complications of 585-nm pulsed dye laser therapy

BACKGROUND

Port-wine stains (PWS) are a congenital, progressive ectasia of the superficial cutaneous vascular plexus that occur in 0.3%-0.5% of children at birth. They should be considered a disease with physical and psychologic complications. Treatment with the flashlamp pulsed dye laser (FPOL) has proven to be effective. Because treatment results in selective vascular injury, the risk of complications is minimal. The purpose of this study was to determine the cutaneous side-effects and complications and their frequency in patients with PWS treated with the FPDL. Eighty-nine patients who had been treated with the FPDL for PWS were included in this study.

METHODS

Patients were treated at 3-month intervals using slightly overlapping pulses with fluences of 6.0-9.0 J/cm2. Treating physicians were responsible for evaluating the patients. All patients were reviewed and side-effects and complications were recorded.

RESULTS

Pigmentary changes were the most frequently observed complications. Hyper- and hypopigmentation appeared in 16.8% and 2.4% of patients, respectively. Cutaneous depressions occurred in 2.2% of patients. One patient developed a hypertrophic scar, and another patient presented with transient cutaneous pustulosis. All these changes usually resolved spontaneously and completely in a few months.

CONCLUSIONS

Most of the side-effects and complications produced by the FPDL are usually transitory, and it is essentially a very secure technique.

Analysis of the phenylalanine hydroxylase gene in the Spanish population: mutation profile and association with intragenic polymorphic markers

The aim of this study was to characterize the phenylketonuria (PKU) alleles in the Spanish population, by both identifying the causative mutations and analyzing the RFLP haplotypes and the VNTR and short-tandem-repeat alleles associated with the phenylalanine hydroxylase (PAH) gene. We have investigated 129 independent mutant chromosomes, using denaturing gradient gel electrophoresis (DGGE) and direct sequencing. Ninety percent of the alleles were identified, and a total of 40 different mutations were detected. The mutational spectrum includes seven previously unreported mutations: P122Q, D129G, P147S, D151G, A165T, S196fs, and P407S. Seven mutations represent 43% of the Spanish PKU alleles, the most common being IVS10nt-11g-->a (14.7%), I65T (8.5%), and V388M (6.2%). The remaining 33 mutations are rare. The mutation profile and relative frequencies are markedly different from those in northern Europe, also showing unique features compared with those in other, southern European populations. The association analysis with polymorphic markers in the PAH gene provides valuable information for population-genetic studies and investigation of the origins of the mutations. This study may serve as reference in the analysis of the contemporary distributions and frequencies of the PKU mutations in related populations, with particular relevance in Latin American countries.

Evaluation of agreement among dermatologists in the assessment of the color of port wine stains and their clearance after treatment with the flashlamp-pumped dye laser

BACKGROUND

Color classification and its subjective clearance evaluation in response to treatment are essential in the management of patients with port wine stains (PWS). But color perception by physicians is not an objective measurement so that it can change among observers. Agreement among physicians is essential for the reliability of the color classification and the clinical assessment of the response to laser treatment.

OBJECTIVE

The purpose of our study was to determine the reliability of the clinical color classification of port wine stains and of their color change or clearance in response to laser treatment. The study was not designed to evaluate the outcome of laser treatment in PWS or the factors that could predict the final response.

METHODS

We used the kappa index to evaluate the proportion of agreement in color and clearance perception among dermatologists. Six dermatologists classified the initial color of PWS in 80 patients. Three of them also assessed the amount of clearance achieved after treatment with the flashlamp-pumped dye laser. These three dermatologists were usually dedicated to treat patients with PWS, while the other three were not.

RESULTS

The kappa index showed a substantial agreement in both cases. No difference in the initial color perception was observed between the group of dermatologists specialized in PWS and the other three dermatologists.

CONCLUSION

These results favor the reliability of the clinical method in the assessment of PWS before and after laser treatment. So, although subjective, color perception by physicians can be used in the study of laser treatment outcome in PWS and its related factors, and the results of different authors can be compared.

Simultaneous determination, in calf urine, of twelve anabolic agents as heptafluorobutyryl derivatives by capillary gas chromatography-mass spectrometry

A method to determine twelve anabolic hormones (diethylstilbestrol, hexestrol, dienestrol, 17 beta-estradiol, 19-nortestosterone, testosterone, 1-dehydrotestosterone, 17 alpha-methyltestosterone, progesterone, estrone, 17 alpha-ethynilestradiol, and trenbolone) is presented. Urine samples were extracted with octadecylsilica columns and clean-up was performed in two steps with basic alumina and silica solid-phase extraction cartridges. The extracts obtained were derivatized with heptafluorobutyric anhydride and analyzed by GC-MS. Stability of derivatives was good and compounds having keto groups produced enol derivatives that were stable also. SIM mode was applied to increase the sensitivity and, when possible, the higher m/z ions were selected to improve identification. Repeatability of the chromatographic analysis was evaluated on the basis of area repeatability, and the coefficient of variation obtained was lower than 13%. Absolute recoveries were in the range 35-60% (dehydrotestosterone and estrone < 20%) with coefficients of variation between 14 and 37% for the whole procedure. [2H3]Testosterone and [2H8]diethylstilbestrol were evaluated to improve quantitative data. The recovery of [2H3]testosterone was found to be equal to or slightly higher than that of the other hormones, but the recovery of [2H8]diethylstilbestrol was lower than any other. [2H3]Testosterone was the most suitable for use as an internal standard, as its addition at the beginning of analytical procedure, corrected recovery results and greatly improved precision. Corrected recoveries from urine ranged from 72-110%, and coefficients of variation ranged from 6-15%, except for testosterone which yielded slightly higher values. The limit of detection was 0.5 ng/ml for all the compounds studied.