Long-term correction of murine phenylketonuria by viral gene transfer: liver versus muscle

Current therapy for phenylketonuria (PKU) consists of life-long dietary restriction of phenylalanine (Phe), which presents problems of adherence for patients. Alternative therapies under investigation include, among others, the use of gene therapy to provide copies of wild-type, non-mutant, phenylalanine hydroxylase (PAH) enzyme. Expression of PAH in both liver (the usual metabolic source of this enzyme) and skeletal muscle is under investigation. Liver gene therapy, using a viral vector based on the adeno-associated viruses (AAVs), provided effective clearance of serum Phe that was sustained for 1year in some mice. In order for PAH expression to be effective in skeletal muscle, the essential metabolic cofactor, tetrahydrobiopterin (BH4), must also be provided, either by supplementation or gene therapy. Both these approaches were effective. When transgenic PKU mice that constitutively expressed PAH in muscle were given intraperitoneal supplementation with BH4, this produced (transient) effective clearance of Phe to normal levels. In addition, use of an AAV vector containing the genes for PAH, and for two key synthetic enzymes for BH4, provided substantial and long-lasting correction (more than 1year) of blood Phe levels when injected into skeletal muscle of PKU mice. These two strategies provide promising treatment alternatives for the management of PKU in patient

Histopathological Effects on the Eye Development During Perinatal Growth of Albino Rats Maternally Treated with Experimental Phenylketonuria During Pregnancy

Phenylketonuria (PKU) is a genetic disorder that is characterized by an inability of the body to utilize the essential amino acid, phenylalanine. The disease results from a deficiency in phenylalanine hydroxylase, the enzyme catalyzing the conversion of phenylalanine to tyrosine. Although, this inborn error of metabolism was among the first in humans to be understood biochemically and genetically, little is known about the mechanisms involved in the pathology of PKU during neonatal brain development. Elevated concentrations of plasma phenylalanine were induced in pregnant rats by oral administration of 50mg/100g body weight alpha-methylphenylalanine plus phenylalanine supplementation at a dosage of 60mg/100g body weight two times daily after 6th day of onset of gestation till 14 & 16 days prenatal as well as at parturition. Treatment with alpha-methylphenylalanine resulted in significant reduction of retinal cell layers of prenatal fetuses and delivered newborns.   Histological abnormalities were detected manifested by either hyaline degeneration of lens structure or inducing lens cataract as well as comparative atrophy of retina associated with the development of Malignant polypoid mass in the ganglionic cell layers in contact with the lens

Breastfeeding Success among Infants with Phenylketonuria

Breast milk is the nutrition of choice for human infants (American Academy of Pediatrics, 2005; American Association of Family Physicians, 2008; Association of Women’s Health Obstetric and Neonatal Nurses, 2005; Canadian Paediatric Society, 2005; U.S. Preventive Services Task Force, 2008; World Health Organization, 2009). The literature on the benefits of breast milk and breastfeeding for infants and mothers has established multiple positive outcomes for infants (Hoddinott, Tappin, & Wright, 2008; Horta, Bahl, Martines, & Victora, 2007; Ip et al., 2007). Breast milk has advantages for infants that distinguish it from standard commercial infant formulas. These advantages include growth factors, hormones, immunological factors, and long-chain polyunsaturated fatty acids. For infants with phenylketonuria (PKU), breast milk has additional advantages over any standard commercial infant formula, such as a lower concentration of protein and a lower content of the amino acid, phenylalanine. Despite these benefits, some clinics encourage mothers of infants with PKU to breastfeed whereas others present breastfeeding as an unacceptable option. Although the possible risks and benefits of breastfeeding infants with PKU have been discussed, there is limited research and practice describing breastfeeding infants with PKU. As a result, breastfeeding infants with PKU is based more upon limited clinical experiences rather than upon evidence based practice that aims to apply the best scientific evidence gained from research to clinical decision making

Effect of Experimental Phenylketonuria on the Bone of Pregnant Mothers and Their Young During Perinatal Life and After Delivered Newborn of Albino Rats

Phenylketonuria (PKU) is a genetic disorder that is characterized by an inability of the body to utilize the essential amino acid, phenylalanine. The disease results from a deficiency in phenylalanine hydroxylase, the enzyme catalyzing the conversion of phenylalanine to tyrosine. Although, this inborn error of metabolism was among the first in humans to be understood biochemically and genetically, little is known about the mechanisms involved in the pathology of PKU during neonatal development. Elevated concentrations of plasma phenylalanine were induced in pregnant rats by oral administration of 50mg/100g body weight alpha-methylphenylalanine plus phenylalanine supplementation at a dosage of 60mg/100g body weight two times daily after the 6th day of onset of gestation till 14 & 16 days of gestation as well as at parturition. Treatment with alpha-methylphenylalanine/ phenylalanine resulted in a significant decrease of accumulated body weight gain during pregnancy as well as exhibited marked growth retardation of prenatal fetuses and delivered newborn. The growth retarded fetuses was manifested by decreased body weight, malformed both fore- & hindlimb, oedematous skin & superficial hematomas widely spread in different parts of the body. Ossification of bones was greatly altered. Skeletal abnormalities restricted mainly in skull, sternebrae, lumbar, caudal vertebrae and distal phalanx of both fore- & hindlimb. Histological examination of femoral bone revealed varieties of histopathological abnormalities which illustrated and discussed. These results suggested that exposure of the fetus to high plasma concentrations of phenylalanine cause deformities of bone

Assessment of Metabolic Parameters For Autism Spectrum Disorders

Autism is a brain development disorder that first appears during infancy or childhood, and generally follows a steady course without remission. Impairments result from maturation-related changes in various systems of the brain. Autism is one of the five pervasive developmental disorders (PDD), which are characterized by widespread abnormalities of social interactions and communication, and severely restricted interests and highly repetitive behavior. The reported incidence of autism spectrum disorders (ASDs) has increased markedly over the past decade. The Centre for Disease Control and Prevention has recently estimated the prevalence of ASDs in the United States at approximately 5.6 per 1000 (1 of 155 to 1 of 160) children. Several metabolic defects, such as phenylketonuria, are associated with autistic symptoms. In deciding upon the appropriate evaluation scheme a clinician must consider a host of different factors. The guidelines in this article have been developed to assist the clinician in the consideration of these factors

Breastfeeding Infants with Phenylketonuria in the United States and Canada

Objective: This study described the prevalence and duration of mothers’ breastfeeding infants with phenylketonuria (PKU) and explored factors related to duration of breastfeeding as a surrogate for breastfeeding success. Subjects and Methods: Descriptive analysis as performed from an international Internet survey of mothers (n = 103) who met the inclusion criteria: (1) at least 21 years of age, (2) able to read and write in English, (3) child with PKU, and (4) living in the United States or Canada. Results: Of the 103 mothers, 89 (86%) initiated breastfeeding immediately following delivery, whereas 14 (14%) chose bottle feeding. In comparison to breastfeeding after delivery, significantly fewer mothers breastfed after diagnosis (McNemar’s v2 = 30.33, p \u3c 0.001; n = 72 vs. n = 89). Breastfeeding duration ranged from less than 1 month to 24 months with one modal duration category (n = 20, 22%) at less than 1 month. The timing of the addition of commercial infant formula to supplement breastfeeding or expressed mothers’ milk was associated with a shorter duration of breastfeeding among infants with PKU: v2 (42, n = 73) = 88.13, p \u3c 0.001. Conclusions: PKU is treated with phenylalanine (Phe) restriction. Breastfeeding infants with PKU is challenging in part because Phe intake is difficult to determine precisely. We studied breastfeeding duration in infants with PKU and factors associated with success. Further research should identify the unique needs of mothers’ breastfeeding infants with PKU to guide the development of interventions specific to these mothers to support their efforts to continue breastfeeding after the diagnosis of PKU

Comparison of adeno-associated virus pseudotype 1, 2, and 8 vectors administered by intramuscular injection in the treatment of murine phenylketonuria

Phenylketonuria (PKU) is caused by hepatic phenylalanine hydroxylase (PAH) deficiency and is associated with systemic accumulation of phenylalanine (Phe). Previously we demonstrated correction of murine PKU after intravenous injection of a recombinant type 2 adeno-associated viral vector pseudotyped with type 8 capsid (rAAV2/8), which successfully directed hepatic transduction and Pah gene expression. Here, we report that liver PAH activity and phenylalanine clearance were also restored in PAH-deficient mice after simple intramuscular injection of either AAV2 pseudotype 1 (rAAV2/1) or rAAV2/8 vectors. Serotype 2 AAV vector (rAAV2/2) was also investigated, but long-term phenylalanine clearance has been observed only for pseudotypes 1 and 8. Therapeutic correction was shown in both male and female mice, albeit more effectively in males, in which correction lasted for the entire period of the experiment (>1 year). Although phenylalanine levels began to rise in female mice at about 8-10 months after rAAV2/8 injection they remained only mildly hyperphenylalaninemic thereafter and subsequent supplementation with synthetic tetrahydrobiopterin resulted in a transient decrease in blood phenylalanine. Alternatively, subsequent administration of a second vector with a different AAV pseudotype to avoid immunity against the previously administrated vector was also successful for long-term treatment of female PKU mice. Overall, this relatively less invasive gene transfer approach completes our previous studies and allows comparison of complementary strategies in the development of efficient PKU gene therapy protocols

Genome Sequencing Technologies and Nursing

Background Advances in DNA sequencing technology have resulted in an abundance of personalized data with challenging clinical utility and meaning for clinicians. This wealth of data has potential to dramatically impact the quality of healthcare. Nurses are at the focal point in educating patients regarding relevant healthcare needs; therefore, an understanding of sequencing technology and utilizing these data are critical. Aim The objective of this study was to explicate the role of nurses and nurse scientists as integral members of healthcare teams in improving understanding of DNA sequencing data and translational genomics for patients. Approach A history of the nurse role in newborn screening is used as an exemplar. Discussion This study serves as an exemplar on how genome sequencing has been utilized in nursing science and incorporates linkages of other omics approaches used by nurses that are included in this special issue. This special issue showcased nurse scientists conducting multi-omic research from various methods, including targeted candidate genes, pharmacogenomics, proteomics, epigenomics, and the microbiome. From this vantage point, we provide an overview of the roles of nurse scientists in genome sequencing research and provide recommendations for the best utilization of nurses and nurse scientists related to genome sequencing

Protective Effect of Recombinant Adeno-Associated Virus 2/8-Mediated Gene Therapy from the Maternal Hyperphenylalaninemia in Offsprings of a Mouse Model of Phenylketonuria

Phenylketonuria (PKU) is an autosomal recessively inherited metabolic disorder caused by a deficiency of phenylalanine hydroxylase (PAH). The accumulation of phenylalanine leads to severe mental and psychomotor retardation, and the fetus of an uncontrolled pregnant female patient presents with maternal PKU syndrome. We have reported previously on the cognitive outcome of biochemical and phenotypic reversal of PKU in a mouse model, Pahenu2, by the AAV serotype 2-mediated gene delivery of a human PAH transgene. However, the therapeutic efficacy had been limited to only male PKU mice. In this study, we generated a pseudotyped recombinant AAV2/8-hPAH vector and infused it into female PKU mice through the hepatic portal vein or tail vein. Two weeks after injection, complete fur color change to black was observed in female PKU, as in males. The PAH activity in the liver increased to 65-70% of the wild-type activity in female PKU mice and to 90% in male PKU mice. Plasma phenylalanine concentration in female PKU mice decreased to the normal value. In addition, the offsprings of the treated female PKU mice can rescue from the harmful effect of maternal hyperphenylalaninemia. These results indicate that recombinant AAV2/8-mediated gene therapy is a potential therapeutic strategy for PKU