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Biomedical subjects

J A Wolff

Publications and source records attributed to J A Wolff.

At least 19 recordsLinked to original sources
PubMed2001

Efficient expression of naked dna delivered intraarterially to limb muscles of nonhuman primates.

We have previously shown that the intraarterial delivery of naked plasmid DNA (pDNA) into the femoral artery of rats leads to high levels of foreign gene expression throughout the muscles of the hindlimb. The present study shows that the procedure can also enable high levels of foreign gene expression throughout the limb skeletal muscles in rhesus monkeys. The average luciferase expression in the target muscle was 991.5 +/- 187 ng/g for the arm and 1692 +/- 768 ng/g for the leg; compared with 780 ng/g in rat hindlimb. Large numbers of beta-galactosidase-positive myofibers were found in both leg and arm muscles, ranging from less than 1% to more than 30% in various muscles, with an average of 6.9%. The nonhuman primates tolerated the procedure without significant adverse effects in skeletal muscles, arteries, or other organs. Other studies in immunosuppressed rats indicated that stable expression is possible. These results suggest that the procedure is likely to enable efficient and stable gene expression in human muscle without substantial toxicity.

Animals↗
PubMed2000

The interactions of peptides with the innate immune system studied with use of T7 phage peptide display.

The icosahedral T7 phage (diameter approximately 65 nm) displaying random peptides at the carboxy-terminus of the phage coat proteins was used as a model for drug and gene delivery vehicles containing peptide ligands. We found that displayed peptides were recognized by natural antibodies and induced complement activation. Strikingly, the phage inactivation by complement was peptide-specific that implied the existence of numerous natural antibodies with different peptide specificity. Selection of phage that avoided inactivation by complement allowed the identification of peptides that protected the phage by binding to serum proteins. In rat blood, peptides with carboxy-terminal lysine or arginine residues protected the phage against complement-mediated inactivation by binding C-reactive protein. In human serum, a number of protective peptides with tyrosine residues were selected. The recognition of displayed peptides by natural antibodies appears to represent a universal mechanism for activation of complement at sites that contain identical or homologous proteins with exposed carboxy-termini.

Animals↗
PubMed1999

Layer-by-layer deposition of oppositely charged polyelectrolytes on the surface of condensed DNA particles.

DNA can be condensed with an excess of poly-cations in aqueous solutions forming stable particles of submicron size with positive surface charge. This charge surplus can be used to deposit alternating layers of polyanions and polycations on the surface surrounding the core of condensed DNA. Using poly-L-lysine (PLL) and succinylated PLL (SPLL) as polycation and polyanion, respectively, we demonstrated layer-by-layer architecture of the particles. Polyanions with a shorter carboxyl/backbone distance tend to disassemble binary DNA/PLL complexes by displacing DNA while polyanions with a longer carboxyl/backbone distance effectively formed a tertiary complex. The zeta potential of such complexes became negative, indicating effective surface recharging. The charge stoichiometry of the DNA/PLL/SPLL complex was found to be close to 1:1:1, resembling poly-electrolyte complexes layered on macrosurfaces. Recharged particles containing condensed plasmid DNA may find applications as non-viral gene delivery vectors.

Anions↗
PubMed1999

High levels of foreign gene expression in hepatocytes after tail vein injections of naked plasmid DNA.

We have previously shown that the intramuscular injection of naked plasmid DNA enables foreign gene expression in muscle. Further studies showed that the intravascular delivery of naked plasmid DNA enables high levels of expression not only in muscle but also in hepatocytes. For the liver, this technique required injection directly into the liver vessels (portal vein, hepatic vein, or bile duct) and occlusion of outflow. The present study now demonstrates that high levels of plasmid DNA expression in hepatocytes can be easily obtained by tail vein injections. The highest levels of expression are achieved by rapidly injecting the plasmid DNA in large volumes, approximately 2.5 ml. This technique has great potential for a wide variety of laboratory studies.

Animals↗
PubMed1999

Quantitative assessment of DNA condensation.

A fluorescent method is proposed for assessing DNA condensation in aqueous solutions with variety of condensing agents. The technique is based on the effect of concentration-dependent self-quenching of covalently bound fluorophores upon DNA collapse. The method allows a more precise determination of charge equivalency in titration experiments with various polycations. The technique's ability to determine the number of DNA molecules that are condensed together in close proximity is under further investigation.

DNA, Circular↗
PubMed1999

A nuclear localization signal can enhance both the nuclear transport and expression of 1 kb DNA.

Although the entry of DNA into the nucleus is a crucial step of non-viral gene delivery, fundamental features of this transport process have remained unexplored. This study analyzed the effect of linear double stranded DNA size on its passive diffusion, its active transport and its NLS-assisted transport. The size limit for passive diffusion was found to be between 200 and 310 bp. DNA of 310-1500 bp entered the nuclei of digitonin treated cells in the absence of cytosolic extract by an active transport process. Both the size limit and the intensity of DNA nuclear transport could be increased by the attachment of strong nuclear localization signals. Conjugation of a 900 bp expression cassette to nuclear localization signals increased both its nuclear entry and expression in microinjected, living cells.

Amino Acid Sequence↗
PubMed1998

Self-assembly of DNA-polymer complexes using template polymerization.

The self-assembly of supramolecular complexes of nucleic acids and polymers is of relevance to several biological processes including viral and chromatin formation as well as gene therapy vector design. We now show that template polymerization facilitates condensation of DNA into particles that are <150 nm in diameter. Inclusion of a poly(ethylene glycol)-containing monomer prevents aggregation of these particles. The DNA within the particles remains biologically active and can express foreign genes in cells. The formation or breakage of covalent bonds has until now not been employed to compact DNA into artificial particles.

3T3 Cells↗
PubMed1998

Renal transplantation in a patient with methylmalonic acidaemia.

Renal insufficiency is frequently reported in mutase-deficient methylmalonic acidaemia. We present a case report of a patient with mut- methylmalonic acidaemia who developed chronic tubulointerstitial nephropathy during adolescence. At 24 years of age, she developed end-stage renal failure and underwent renal transplantation. Both plasma and urine methylmalonic acid levels decreased significantly with improved renal function following transplantation. Complications included cyclosporin toxicity and development of diabetes. Renal, metabolic, and clinical status remained improved at 3 years after the kidney transplant.

Adult↗
PubMed1998

DNA vector chemistry: the covalent attachment of signal peptides to plasmid DNA.

The nuclear entry of exogenous DNA in mammalian cells is critical for efficient gene transfer. A novel technique was developed for the covalent attachment of cationic peptides to double-stranded DNA using a cyclo-propapyrroloindole cross-linker. The attachment of the SV40 large T antigen nuclear localization signal peptide induced the nuclear accumulation of the conjugated DNA in digitonin-permeabilized cells via the classical pathway for the nuclear transport of karyophilic proteins. Increased nuclear uptake of the modified DNA, however, did not occur after it was microinjected into the cytoplasm of cultured cells. This demonstration that the covalent modification of DNA with a signal peptide alters its behavior and interaction with other cellular factors portends the potential of DNA vector chemistry to enhance the efficiency of cellular gene transfer.

Antigens, Polyomavirus Transforming↗
PubMed1998

Metabolic engineering as therapy for inborn errors of metabolism--development of mice with phenylalanine hydroxylase expression in muscle.

Treatment of many inherited liver enzyme deficiencies requires the removal of toxic intermediate metabolites from the blood of affected individuals. We propose that circulating toxins can be adequately cleared and disease phenotype influenced by enzyme expressed in tissues other than the liver. Phenylalanine hydroxylase (PAH) activity was constitutively expressed in skeletal and cardiac muscle of transgenic mice which carried the PAH cDNA under the transcriptional control of the mouse muscle creatine kinase promoter. Muscle PAH-expressing mice were bred to liver PAH-deficient, hyperphenylalaninemic mice to yield progeny that lack PAH activity in liver but express PAH in muscle. These mice exhibited hyperphenylalaninemia at baseline, but serum phenylalanine levels decreased significantly when the mice were supplemented with tetrahydrobiopterin (BH4), a required cofactor for PAH. This is the first demonstration that a liver-specific enzyme, when expressed in a heterologous tissue and supplied with necessary cofactors, can effectively clear toxic metabolites from the circulation of individuals with inherited enzyme deficiency. This result suggests that gene therapy targeted to heterologous tissues, such as muscle, will be effective in the treatment of selected inborn errors of metabolism.

Animals↗
PubMed1997

Expression of naked plasmid DNA injected into the afferent and efferent vessels of rodent and dog livers.

A variety of reporter genes within plasmid constructs were injected into the afferent and efferent vessels of the liver in mice, rats, and dogs. Efficient plasmid expression was obtained following delivery via the portal vein, the hepatic vein, and the bile duct. The use of hyperosmotic injection solutions and occlusion of the blood outflow from the liver substantially increased the expression levels. Combining these surgical approaches with improved plasmid vectors enabled uncommonly high levels of foreign gene expression in which over 15 microg of luciferase protein/liver was produced in mice and over 50 microg in rats. Equally high levels of beta-galactosidase (beta-Gal) expression were obtained, in that over 5% of the hepatocytes had intense blue staining. Expression of luciferase or beta-Gal was evenly distributed in hepatocytes throughout the entire liver when either of the three routes were injected. Peri-acinar hepatocytes were preferentially transfected when the portal vein was injected in rats. These levels of foreign gene expression are among the highest levels obtained with nonviral vectors. Repetitive plasmid administration through the bile duct led to successive events of foreign gene expression. The integration of these findings into laboratory and clinical protocols is discussed.

Animals↗
PubMed1997

Functional methionine synthase deficiency due to cblG disorder: a report of two patients and a review.

Functional methionine synthase deficiency due to abnormal methylcobalamin metabolism causes megaloblastic anemia, moderate to severe developmental delay, lethargy, and anorexia in association with homocystinuria. Patients with this disorder of cobalamin metabolism can be classified into two separate groups, cblE or cblG, primarily on the basis of complementation analysis with cultured skin fibroblasts. We describe two unrelated boys, ages 3 and 5 years, with the cblG defect in methylcobalamin synthesis. Both children presented with severe developmental delay, lethargy, anorexia, and megaloblastic anemia. The diagnosis of homocystinuria was delayed in each case due to difficulties with detection of small amounts of homocystine in physiologic samples. The clinical course of cblG disease is favorably altered by treatment with intramuscular hydroxycobalamin. Megaloblastosis in the presence of adequate supplies of cobalamin and folate in the blood must alert the clinician to the possibility of functional methionine synthase deficiency and should prompt a careful search for associated biochemical hallmarks, including homocystinuria/emia.

5-Methyltetrahydrofolate-Homocysteine S-Methyltran↗
PubMed1997

Mice with genetic gamma-glutamyl transpeptidase deficiency exhibit glutathionuria, severe growth failure, reduced life spans, and infertility.

A mouse mutant with glutathionuria was discovered by screening for amino acidurias in the progeny of ethylnitrosourea-mutagenized mice. Total glutathione concentration was increased in both blood and urine but decreased in liver homogenates from affected mice. Glutathionuric mice exhibited lethargy, severe growth failure, shortened life spans and infertility. gamma-Glutamyl transpeptidase activity was deficient in kidney homogenates of glutathionuric mice. The glutathionuric phenotype in these mice is inherited as an autosomal recessive trait. This mouse mutant will be a useful animal model for the study of gamma-glutamyl transpeptidase physiology and glutathione metabolism.

Animals↗
PubMed1997

Naked DNA transport and expression in mammalian cells.

The tremendous promise of gene therapy is stymied by inefficient gene transfer. Non-viral methods of transferring genes directly into tissues in situ have great potential for solving this problem. One attractive approach for non-viral direct gene transfer is the use of naked DNA. Previously, it was thought that naked DNA was able to express in only muscle and at low efficiency. We have recently found that naked DNA delivered intraportally can express at high levels in hepatocytes. Other non-viral methods of gene transfer are under development and these include ternary complexes of histone protein and liposomes. Besides trial-and-error approaches, the mechanism of the nuclear entry of plasmid DNA, a critical step, has been under intense study. It is anticipated that further advances in the efficiency of direct, non-viral gene transfer will enable its use in clinical settings in the near future.

Animals↗
PubMed1997

A longitudinal study of cognitive functioning in patients with classical galactosaemia, including a cohort treated with oral uridine.

Existing longitudinal data on patients with classical galactosaemia suggests that neurocognitive functioning is impaired and, in isolated case reports, may show a decline in performance over time. The present study explored whether there are long-term changes in cognitive abilities in patients with galactosaemia and whether oral uridine can improve neurocognitive performance. Thirty-five patients (18 males, 17 females), 29 of whom received oral uridine powder at 150 mg/kg per day (divided dose, three times daily), were evaluated over a 2-5-year period with the Woodcock-Johnson Revised Cognitive Abilities Test, three academic achievement tests, and the Beery Test of Visual Motor Integration. Results showed that the uridine cohort and a comparison group that received only dietary restriction made small gains in cognitive performance over the treatment period and the size of the gains did not differ significantly. Seven subjects who started uridine prior to the age of 14 months did not differ significantly in their cognitive test scores at an average age of 3.5 years from a group of older children who had begun treatment at 4.5 years of age. These results provide no support for any developmental or uridine-treatment-related change in cognitive functioning for this sample of galactosaemic subjects.

Achievement↗