Biotin recycling impairment in phenylketonuric children with seborrheic dermatitis

OBJECTIVE: To investigate the effect of a therapeutic diet on serum biotin levels and to explain the seborrheic dermatitis in phenylketonuric (PKU) patients on a "loose" diet. DESIGN: Forty-seven patients were divided into two groups: group A (n=21) demonstrated good compliance to a special diet and group B (n=26) were on a "loose" diet. Most of the patients in group B (20/26), who suffered from mild seborrheic dermatitis, were requested to return to phenylalanine (Phe)-restricted diet for at least 15 days. Seventy-nine healthy children of comparable age were used as controls. Biotin serum levels and plasma biotinidase activity were measured in patients as well as controls. In addition, biotinidase activity was evaluated in vitro after incubation with various concentrations of Phe. RESULTS: Biotin levels in group A patients (636+/-118 ng/L) were statistically significantly elevated (P < 0.01) compared with those of group B patients before (412+/-184 ng/L) and after (501+/-160 ng/L) 15 days on a Phe-restricted diet, as well as with those of controls (337+/-290 ng/L). Furthermore, biotinidase activities were decreased in group B patients (4.2+/-1.68 nmol/min/L) compared with those of group A patients (6.4+/-0.7 nmol/min/L) and controls (6.10+/-0.8 nmol/min/L). Additionally, biotinidase activities in the patients of group B were restored to normal (5.78+/-0.81 nmol/min/L), with a simultaneous remission of their skin lesions, after 15 days on a Phe-restricted diet. Moreover, the in vitro findings showed a 51% inhibition of biotinidase activity when incubated with Phe (20 mg/dL). CONCLUSIONS: It is suggested that the high biotin levels in group A patients reflect the intake of water-soluble biotin of vegetable origin. In contrast, the low biotinidase activity in group B patients may be attributed to their high Phe plasma levels, which acts as an enzyme inhibitor, as shown by the in vivo and in vitro results. Consequently, the observed seborrheic dermatitis in PKU children (group B) is associated with an impairment of biotin recycling.     

Comparison of the phenylalanine determination by ion exchange column chromatography and the guthrietest in treated phenylketonuric children (author''s transl)]

Simultaneous measurements of phenylalanine by ion exchange column chromatography and microbiologal inhibition test according to Guthrie were performed on 22 treated children with phenylketonuria within two years. The results coincide in 40,3% (229 of 569 estimations), in 15,8% the real phenylalanine concentration by the method of Guthrie were overestimated, in 43,9% underestimated. Bacterial inhibition assay is successful in routine screening of phenylketonuria in the newborn, but not suitable for dietary control of phenylketonuria.     

Left ventricular hypertrophy, blood pressure and ACE genotype in untreated hypertension

It has been suggested that the deletion polymorphism of the angiotensin-converting enzyme (ACE) genotype may be important in the development of left ventricular hypertrophy (LVH). In order to test this hypothesis we investigated the interaction between blood pressure (BP), LVH and ACE genotype in 86 previously untreated hypertensive patients. Each underwent two-dimensional and Doppler echocardiography and ACE genotyping. There were no significant differences in BP, the parameters of left ventricular structure (including left ventricular mass index) or diastolic function between the three genotype groups. Additionally, there were no significant differences in the relationship between systolic BP and left ventricular mass index among the three genotype groups (II genotype, r = 0.46, P = 0.02; ID genotype, r = 0.42, P = 0.01; DD genotype, r = 0.34, P = 0.10; F = 0.38). In contrast to some previous studies, we have found in this group of previously untreated hypertensive subjects no evidence to suggest that the deletion polymorphism of the ACE genotype is important in the development of LVH.     

Responses of phenylketonuric children on a continuous performance test.

Administered a task which required continuous attending to 11 phenylketonuric children and 11 nonphenylketonuric controls (matched for age, IQ, sex, and race). The phenylketonuric Ss made significantly fewer correct responses and more late responses than their matched controls. The performance of the phenylketonuric Ss also changed significantly over the sequence of stimulus presentations, with fewer correct responses toward the end. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

S-mephenytoin hydroxylation phenotype and CYP2C19 genotype among Ethiopians

Adequacy of peritoneal dialysis is predictive of outcome but the absolute evidence for setting optimal levels or targets is still lacking. The link between adequacy and nutrition is also tenuous and appears to be based on a mathematical relationship. The ability of standard continuous ambulatory peritoneal dialysis regimes to provide adequate dialysis may be limited in anuria and in large individuals.     

Clear correlation of genotype with disease phenotype in very-long-chain acyl-CoA dehydrogenase deficiency

Very-long-chain acyl-CoA dehydrogenase (VLCAD) catalyzes the initial rate-limiting step in mitochondrial fatty acid beta-oxidation. VLCAD deficiency is clinically heterogenous, with three major phenotypes: a severe childhood form, with early onset, high mortality, and high incidence of cardiomyopathy; a milder childhood form, with later onset, usually with hypoketotic hypoglycemia as the main presenting feature, low mortality, and rare cardiomyopathy; and an adult form, with isolated skeletal muscle involvement, rhabdomyolysis, and myoglobinuria, usually triggered by exercise or fasting. To examine whether these different phenotypes are due to differences in the VLCAD genotype, we investigated 58 different mutations in 55 unrelated patients representing all known clinical phenotypes and correlated the mutation type with the clinical phenotype. Our results show a clear relationship between the nature of the mutation and the severity of disease. Patients with the severe childhood phenotype have mutations that result in no residual enzyme activity, whereas patients with the milder childhood and adult phenotypes have mutations that may result in residual enzyme activity. This clear genotype-phenotype relationship is in sharp contrast to what has been observed in medium-chain acyl-CoA dehydrogenase deficiency, in which no correlation between genotype and phenotype can be established.     

Phenotype and genotype expression in pseudohomozygous factor VLEIDEN : the need for phenotype analysis

The presence of a DNA mutation is frequently used to define a disease or a risk state. Because DNA typing has become easy and convenient in contrast to protein characterization, it is generally assumed that a mutation if present (or not) at the DNA level will be also present (or not) in the corresponding protein. However, discrepancies between phenotype and genotype can occur. A point mutation in the coagulation factor V gene (G1691-->A, resulting in an Arg506-->Gln amino acid substitution in the factor V molecule [factor VLEIDEN], leading to activated protein C resistance) is the most common genetic risk factor for familial thrombophilia. A pseudohomozygous factor VLEIDEN phenotype would occur if a heterozygous individual for factor VLEIDEN also did not express the "normal" (non-Leiden) factor V allele. However, to date, no data have been available to confirm the presence of only the factor VLEIDEN form in the plasma of these individuals. Platelet mRNA from 2 presumed pseudohomozygous patients and their family members was isolated, the amplified partial cDNAs were sequenced or restricted, and the allelic bands were quantified. Both patients were found to be heterozygous for the G1691-->A substitution at both the DNA and mRNA levels. The presence of either the normal or mutated form of factor V in the patients' plasmas was investigated using a monoclonal antibody to factor V that recognizes an epitope located between residues 307 and 506 of the factor Va heavy chain. No normal factor V could be detected in the plasmas of the 2 propositi. The present data demonstrate absence of a correlation between genotype at position 1691 (at the DNA and mRNA levels) and the corresponding phenotype data found in the plasmas of patients with pseudohomozygous factor VLEIDEN. Overall, these data suggest the existence of heterogeneous genetic "lesions," which interfere with factor V expression, processing, secretion, and/or stability. Because the presence of the factor VLEIDEN molecule in plasma is directly related to pathology, identification and quantification of the circulating forms of factor V in plasma may be required for the diagnosis of individuals with activated protein C resistance.     

CYP2C19 genotype and phenotype determined by omeprazole in a Korean population

Omeprazole (20 mg orally) was given to 103 healthy Korean subjects and blood was taken 3 h after administration. The plasma concentration ratio of omeprazole and hydroxyomeprazole, used as an index of CYP2C19 activity, was bimodally distributed. Thirteen subjects (12.6%) were identified as poor metabolizers (PMs) with an omeprazole hydroxylation ratio of 6.95 or higher. Among the 206 CYP2C19 alleles, CYP2C19*2 and CYP2C19*3 were found in 43 alleles (21%) and 24 alleles (12%), respectively. Twelve subjects (12%) carried two defect alleles (*2/*2, *2/*3 or *3/*3), 43 subjects (42%) were heterozygous for a mutated (*2 or *3) and a wild type (*1) allele, and the remaining 48 subjects (47%) were homozygous for the wild type allele. The distributions of the metabolic ratio between these three genotype groups were significantly different (Kruskal-Wallis test: p < 0.0001). The genotypes of 19 additional Korean PMs has been identified in a previous mephenytoin study. From a total of 32 PMs, 31 were genotypically PMs by analysis of the CYP2C19*2 and *3 alleles and only one PM subject was found to be heterozygous for the *1 and *2 alleles. At present it cannot be judged whether this subject has a defective allele with a so-far unidentified mutation or a true wild type allele. We thus confirm a high incidence (12.6%) of PMs of omeprazole in Koreans and of the 32 Korean PMs 97% could be identified by the genotype analysis.     

Stable and inheritable changes in genotype and phenotype of albino melanocytes induced by an RNA-DNA oligonucleotide

Experimental strategies have been developed to correct point mutations using chimeric oligonucleotides composed of RNA and DNA. We used these RNA-DNA oligonucleotides to correct a point mutation in mouse tyrosinase, a key enzyme for melanin synthesis and pigmentation. Melanocytes derived from albino mice contain a homozygous point mutation (TGT-->TCT) in the tyrosinase gene, resulting in an amino acid change from Cys-->Ser. Correction of this point mutation results in the restoration of tyrosinase activity and melanin synthesis, thus changing the pigmentation of the cells. Upon transfection of the RNA-DNA oligonucleotide to albino melanocytes, we detected black-pigmented cells and isolated multiple single clones. All black-pigmented clones exhibited a correction of the point mutation in a single allele of the tyrosinase gene. A full-length tyrosinase was detected by an antityrosinase antibody, and the enzymatic activity was restored in all converted black-pigmented clones. Only degraded fragments were detected in albino cells due to proteolytic cleavage of mutant tyrosinase. The phenotype and genotype of converted black-pigmented clones was stable. These results demonstrate a permanent and stable gene correction by the RNA-DNA oligonucleotide at the level of genomic sequence, protein, and phenotypic change by clonal analysis.     

Effect of bacterial association on the phenotype and genotype of an Entamoeba histolytica clonal population

A several-times-cloned population of Entamoeba histolytica trophozoites (clone MAVIII) was cultured under axenic (MAVIIIax), monoxenic (MAVIIImx) and polyxenic (MAVIIIpx) conditions. Clones MAVIIIax and MAVIIImx presented similar virulence in vitro, but differed in their virulence in vivo, whereas MAVIIIpx trophozoites were neither virulent in vitro or in vivo. The MAVIII clones maintained their zymodeme and exhibited three unusual glucose phosphate isomerase bands, absent in other E. histolytica strains studied. Similar patterns were shown by the three MAVIII clones in the signature of a 482-bp DNA fragment from the M17 gene (which encodes for a variable immunodominant antigen), obtained by low stringency single specific primer PCR technique. However, MAVIII clones displayed genotypic variability in the patterns obtained by the random amplified polymorphic DNA technique using total DNA as template. Results suggest that monomorphism is kept in certain regions of the genome, mainly in those carrying protein encoding genes, but a high polymorphism is present in total DNA of cloned trophozoites cultured under different conditions, confirming the plasticity of the E. histolytica genome.     

Cancer phenotype correlates with constitutional TP53 genotype in families with the Li-Fraumeni syndrome

The Li-Fraumeni cancer predisposition syndrome is associated with germline TP53 mutations in the majority of families. We have investigated cancer incidence in 34 Li-Fraumeni families, according to their constitutional TP53 mutation status. Families with germline missense mutations in the core DNA binding domain showed a more highly penetrant cancer phenotype than families with other TP53 mutations or no mutation. Cancer phenotype in families carrying such mutations was characterized by a higher cancer incidence and earlier ages at diagnosis, especially of breast cancer and brain tumours, compared with families carrying protein truncating or other inactivating mutations (P=0.03 for all cancers, P=0.006 for breast cancers, P=0.05 for brain tumours). Proband cancers showed significantly younger ages at diagnosis in those with missense mutations in the DNA binding domain than in those with protein inactivating mutations (P=0.031). In individuals with the former type of mutation, there was a significantly lower proportion of tumours which showed loss of the wild-type TP53 allele (P=0.004). These results are consistent with observations in experimental systems which demonstrate that certain mutations exhibit gain of function and/or dominant-negative properties. Our results support an enhanced oncogenic potential for such mutations in human populations.     

Comparison of estrogen receptor DNA binding in untreated and acquired antiestrogen-resistant human breast tumors

Preliminary studies have suggested that measuring the ability of immunoreactive 67-kDa estrogen receptor (ER) to bind DNA and form in vitro complexes with its cognate estrogen response element (ERE) might serve to identify breast tumors most likely to respond to antiestrogens like tamoxifen. Data from two different surveys of untreated primary breast tumors confirmed that only 67% (74 of 111) of ER-positive tumors express a receptor capable of forming ER-ERE complexes by gel-shift assay, with tumors of lower ER content having significantly reduced ER DNA-binding frequency (56%) relative to those of higher ER content (82%; P = 0.007). In contrast to these untreated tumors, a panel of 41 receptor-positive breast tumors excised after acquiring clinical resistance to tamoxifen during either primary (n = 26) or adjuvant therapy (n = 15) showed a significantly greater ER DNA-binding frequency, with nearly 90% capable of forming ER-ERE complexes (P < 0.02). To assess experimentally whether ER DNA-binding function is altered during the development of antiestrogen resistance, nude mouse MCF-7 tumor xenografts were analyzed before and after the acquisition of in vivo resistance to either tamoxifen or a pure steroidal antiestrogen, ICI 182,780. Tamoxifen-resistant MCF-7 tumors retained full expression of 67-kDa DNA-binding ER, and despite a markedly reduced ER content in the ICI 182,780-treated tumors, the expressed ER in these antiestrogen-resistant tumors exhibited full ability to form ER-ERE complexes. These findings indicate that breast tumors with acquired antiestrogen resistance continue to express ER of normal size and DNA-binding ability and suggest that the failure of antiestrogens to arrest tumor growth during emergence of clinical resistance results from an altered gene-regulatory mechanism(s) other than ER-ERE complex formation.     

Cross-validation of an index of premorbid intellectual functioning in children.

Attempted to cross-validate the results of C. R. Reynolds and T. B. Gritbin's (1979) index of premorbid intellectual functioning in children. For a clinically relevant sample of 76 nonimpaired and 23 organically impaired children, WISC-R IQs predicted by the index correlated at only minimal and nonsignificant levels with actual IQs. The index's ability to discriminate between the 2 groups was similarly found to be extremely limited. (1 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Thirty years of research on congenital glucose and galactose malabsorption: from phenotype to genotype

Intestinal absorption of glucose plays a key role in water economy as attested by the congenital and selective glucose and galactose malabsorption which is expressed as severe watery diarrhea just after birth, leading to life-threatening dehydration. This syndrome, transmitted on an autosomal recessive mode, is the consequence of a functional defect of the glucose-sodium cotransporter at the luminal membrane of the enterocyte of the small intestine. In one family, this defect was associated with a missense mutation at position 92 of the SGLT1 gene coding for the cotransporter. The mutant RNA reproduced the transport defect after injection in xenopus oocytes. These results confirm the genetic origin of the congenital defect; in addition they indicate that the study of the relationship between phenotype and genotype of congenital defects of intestinal transport may help in the understanding of basic intestinal functions in relation with human nutrition.     

Behavioral treatment and normal educational and intellectual functioning in young autistic children.

Autism is a serious psychological disorder with onset in early childhood. Autistic children show minimal emotional attachment, absent or abnormal speech, retarded IQ, ritualistic behaviors, aggression, and self-injury. The prognosis is very poor, and medical therapies have not proven effective. This article reports the results of behavior modification treatment for two groups of similarly constituted, young autistic children. Follow-up data from an intensive, long-term experimental treatment group (n?=?19) showed that 47% achieved normal intellectual and educational functioning, with normal-range IQ scores and successful first grade performance in public schools. Another 40% were mildly retarded and assigned to special classes for the language delayed, and only 10% were profoundly retarded and assigned to classes for the autistic/retarded. In contrast, only 2% of the control-group children (n?=?40) achieved normal educational and intellectual functioning; 45% were mildly retarded and placed in language-delayed classes, and 53% were severely retarded and placed in autistic/retarded classes. (31 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cognitive functions and the antioxidant system in phenylketonuric patients.

The authors studied the relationship between the antioxidant system and cognitive functions in a group of 36 early and continuously treated phenylketonuric (PKU) patients (mean age=9.7 years) and 29 controls. The authors measured antioxidant cofactors and free radical damage markers in plasma (selenium, retinol, tocopherol, coenzyme Q10, malondialdehide) and antioxidant enzymes in red blood cells (glutathione peroxidase, catalase, superoxide dismutase). The authors used neuropsychological tests to screen for several cognitive functions. PKU patients showed significantly lower values of selenium, coenzyme Q10, and catalase, and significantly higher levels of malondialdehide. PKU patients showed a significantly negative correlation between plasma selenium concentrations and several Conner's Continuous Performance Test measures (more omission errors, fluctuating attention and inconsistency of response times, and slowing reaction time as the test progressed). Selenium deficiency was thus associated with a worsened performance on the Conner's Continuous Performance Test among PKU patients. In conclusion, it is important not only to control blood Phe levels in PKU but also other nutritional components such as selenium. Selenium status seems to be associated with attention functions in these PKU patients. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Aromatic hydrocarbon receptor polymorphism: development of new methods to correlate genotype with phenotype

BACKGROUND: Non-steroidal anti-inflammatory drugs can reduce the risk of colorectal cancer. Reportedly, mRNA expression of cyclooxygenase-2 (COX-2) is elevated in human colorectal cancers compared with accompanying normal mucosa. The present study was undertaken to establish a simple analytical procedure to quantify COX-2 expression levels and to characterize COX-2 expression levels in human colorectal cancers, adenomas and hyperplastic polyps. METHODS: The combination of PCR using common primers designed in the highly conserved regions and fluorescence-based single-strand conformation polymorphism (F-SSCP) analysis of the products is used for quantitative determination of the proportions of COX-2 mRNA in human colorectal cancers, adenomas, hyperplastic polyps and accompanying normal mucosa. RESULTS: The present F-SSCP analysis was a simple and powerful method for quantitative determination of the proportions of COX-2 mRNA. The proportion of COX-2 mRNA was higher in cancer tissues than in accompanying normal mucosa in 46 of the 50 cancers. There was no significant correlation between the increase of the COX-2 proportion and tumor location or stages. The enhanced COX-2 expression was also observed in colorectal adenomas. On the other hand, the proportion of COX-2 mRNA in hyperplastic polyps was not significantly different from that in normal mucosa. CONCLUSIONS: The proportion of COX-2 to COX-1 expression was elevated in most human colorectal cancers and adenomas, but not in hyperplastic polyps. Therefore, the increased proportion of COX-2 expression might be an early event in the carcinogenesis of colorectal cancer.     

Circadian blood pressure changes in untreated children with kidney disease and conserved renal function

Ambulatory blood pressure monitoring over 24 h was applied in 31 children with kidney disease, aged 3-19 (median 11) years, in the absence of renal insufficiency and without antihypertensive therapy. Median creatinine clearance was 112 ml/min/1.73m2. Ambulatory blood pressure monitoring revealed that eight patients (26%) were hypertensive during the daytime, compared to 62% through casual recordings obtained in the office and 38% when blood pressure was taken at home. Nocturnal hypertension was detected by ambulatory monitoring in six patients, two of whom had normal blood pressure in the daytime. Median nocturnal dipping was 13% for systolic and 21% for diastolic blood pressure, i.e. similar to healthy children. Rhythm analysis recognized a distorted circadian pattern for systolic and/or diastolic blood pressure in eight patients. In conclusion, ambulatory blood pressure monitoring allows the evaluation of hypertension more reliably than casual recordings in the office. Nocturnal hypertension, as a major risk factor for renal deterioration, is detected in a similar proportion as daytime hypertension in almost 20% of untreated children with kidney disease and normal renal function.