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M J Bennett

Publications and source records attributed to M J Bennett.

At least 127 records · Page 7Linked to original sources
PubMed1996

Structural and functional analysis of cationic transfection lipids: the hydrophobic domain.

Cationic lipids (cytofectins) have gained widespread acceptance as pharmaceutical polynucleotide delivery agents for both cultured cell and in vivo transfection, and the cytofectins DOTAP and DC-Cholesterol are being tested in clinical human gene therapy trials. This study reports the effects of modifications in the hydrophobic domain of a prototypic cytofectin (DORI), including modifications in lipid side-chain length, saturation, and symmetry. A panel of related compounds was prepared and analyzed using DNA transfection, electron microscopy, and differential scanning calorimetry (DSC). Lipid formulations were prepared with dioleoylphosphatidylethanolamine (DOPE) as unsonicated preparations and sonicated preparations. Transfection analyses were performed using cultured fibroblasts, human bronchial epithelial, and Chinese hamster ovarian cells as well as a mouse model for pulmonary gene delivery. In general, cytofectins containing dissymmetric hydrophobic domains were found to work as well or better than the best symmetric analogs. Optimal side-chain length and symmetry varied with cell type. Compounds with phase transitions (Tc) above and below physiological temperature (37 degrees C) were tested for DNA transfection activity. In contrast to previous reports, cytofectin Tc was not found to be predictive of transfection efficacy. Pulmonary treatment with free DNA was found to be at least as effective as treatment with commonly used cytofectin:DNA complexes. However, cytofectins that incorporate a hydroxyethylammonium moiety in the polar domain were found to enhance in vivo gene delivery relative to free DNA.

3T3 Cells↗
PubMed1996

Acute fatty liver of pregnancy, hemolysis, elevated liver enzymes, and low platelets syndrome, and long chain 3-hydroxyacyl-coenzyme A dehydrogenase deficiency.

BACKGROUND: The similarity of the hepatic pathology in acute fatty liver of pregnancy (AFLP) to that seen in children with inherited disorders of intramitochondrial fatty acid oxidation (FAO) suggests that there may be a genetic basis for some cases of AFLP. OBJECTIVE: The purpose of this study was to examine patients with AFLP and their offspring to determine if there were women with AFLP who were heterozygous for the FAO defect, long chain 3-hydroxyacyl CoA dehydrogenase (LCHAD) deficiency. METHODS: We evaluated 12 women previously diagnosed with AFLP. Provocative fasting studies and skin biopsies for examination of their cultured skin fibroblasts were performed to search for a generalized defect in FAO both in vivo and in vitro. Cultured skin fibroblasts from AFLP patients, their children, and their husbands were also examined specifically for LCHAD activity. RESULTS: Of 12 women with a previous episode of AFLP, eight had reduced LCHAD activity consistent with being heterozygous for LCHAD deficiency. The eight heterozygotes had a total of nine pregnancies complicated by AFLP. In seven of those nine pregnancies, the women developed severe preeclampsia and hemolysis, elevated liver enzymes, and low platelets (HELLP) syndrome. Of the nine offspring delivered from these pregnancies, four were confirmed to be affected with homozygous LCHAD deficiency. Three other deceased infants were presumed to be LCHAD-deficient based on clinical findings, postmortem examination, and confirmed heterozygote parents. The remaining two infants delivered after pregnancies complicated by AFLP had LCHAD activity in the heterozygous range and are healthy at 18 and 24 months of age. Consistent with the known autosomal recessive nature of this defect, five tested husbands of LCHAD heterozygous women with a history of AFLP and affected infants also showed reduced LCHAD activity. CONCLUSIONS: These studies indicate that a significant subgroup of women with AFLP are heterozygous for LCHAD deficiency and that careful observation of their offspring for signs of this disorder is warranted. Severe preeclampsia appears to increase the risk of AFLP in LCHAD heterozygous women.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1995

Mitochondrial damage results in a reversible increase in lysosomal storage material in lymphoblasts from patients with juvenile neuronal ceroid-lipofuscinosis (Batten Disease).

We have previously demonstrated reduced phospholipid fatty acid content in blood cells and cultured skin fibroblasts from patients with JNCL. This has led to an experimental treatment regimen consisting of dietary supplementation with polyunsaturated fatty acids (PUFAs). In order to study the effects of PUFA supplementation in vitro, we have developed a laboratory model based upon cultured lymphoblast cell lines. We have transformed lymphocytes from four JNCL patients in whom disease linkage to chromosome 16 was informative. Cells from patients and controls were cultured with and without antibiotic (50 micrograms/ml gentamycin) and with and without PUFA supplementation. None of the control cells demonstrated significant storage under any of the above conditions. In gentamycin treated cells, we observed that many of the mitochondria were damaged. In addition, cells from patients incubated with gentamycin demonstrated large accumulations of autofluorescent storage material. Disease cells grown in the presence of antibiotic and PUFAs did not demonstrate a significant accumulation of storage material; this suggests a direct relationship between mitochondrial damage and storage of autofluorescent material. Moreover, it appears that this storage (but not mitochondrial damage) is reversed by the addition of PUFAs.

Anti-Bacterial Agents↗
PubMed1995

Erythrocyte membrane reacylation in juvenile neuronal ceroid-lipofuscinosis: measurement of membrane-bound carnitine palmitoyl transferase, acyl-CoA synthetase, and lysophospholipid: acyl-CoA acyltransferase activities.

In order to study the biochemical mechanisms responsible for the membrane fatty acid deficiency in juvenile neuronal ceroid-lipofuscinosis, we have analyzed the reacylation pathway in isolated erythrocyte membranes in 5 patients. We studied membrane carnitine palmitoyl transferase, and developed a combined assay to study acyl-CoA synthetase and lysophospholipid acyl-CoA acyltransferase activities. There were no significant differences between control and patient membranes, suggesting that abnormalities in these 3 putative candidate enzymes are not responsible for the disease.

1-Acylglycerophosphocholine O-Acyltransferase↗
PubMed1995

Intact alpha-subunit is required for membrane-binding of human mitochondrial trifunctional beta-oxidation protein, but is not necessary for conferring 3-ketoacyl-CoA thiolase activity to the beta-subunit.

We have studied the activities of alpha and beta subunit enzymes of the beta-oxidation trifunctional protein complex in a patient who does not process the alpha-subunit. Long-chain 3-ketoacyl-CoA thiolase, the beta-subunit enzyme, was transported into the mitochondrial matrix, where it expressed normal levels of activity, but was not translocated to the membrane. Thus, intact alpha-subunit is required for trifunctional protein membrane translocation, but is not necessary for conferring activity of the beta-subunit.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1995

The molecular basis of pediatric long chain 3-hydroxyacyl-CoA dehydrogenase deficiency associated with maternal acute fatty liver of pregnancy.

Mitochondrial long chain fatty acid beta-oxidation provides the major source of energy in the heart. Deficiencies of human beta-oxidation enzymes produce sudden, unexplained death in childhood, acute hepatic encephalopathy, skeletal myopathy, or cardiomyopathy. Long chain 3-hydroxyacyl-CoA dehydrogenase [LCHAD; long-chain-(S)-3-hydroxyacyl-CoA:NAD+ oxidoreductase, EC 1.1.1.211] catalyzes the third step in beta-oxidation, and this activity is present on the C-terminal portion of the alpha subunit of mitochondrial trifunctional protein. We used single-stranded conformation variance analysis of the exons of the human LCHAD (alpha subunit) gene to determine the molecular basis of LCHAD deficiency in three families with children presenting with sudden unexplained death or hypoglycemia and abnormal liver enzymes (Reye-like syndrome). In all families, the mothers had acute fatty liver and associated sever complications during pregnancies with the affected infants. The analysis in two affected children revealed a G to C mutation at position 1528 (G1528C) of the alpha subunit of the trifunctional protein on both alleles. This is in the LCHAD domain and substitutes glutamine for glutamic acid at position 474 of mature alpha subunit. The third child had this G1528C mutation on one allele and a different mutation (C1132T) creating a premature termination codon (residue 342) on the second allele. Our results demonstrate that mutations in the LCHAD domain of the trifunctional protein alpha subunit in affected offspring are associated with maternal acute fatty liver of pregnancy. This is the initial delineation of the molecular basis of isolated LCHAD deficiency.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1995

3D domain swapping: a mechanism for oligomer assembly.

3D domain swapping is a mechanism for forming oligomeric proteins from their monomers. In 3D domain swapping, one domain of a monomeric protein is replaced by the same domain from an identical protein chain. The result is an intertwined dimer or higher oligomer, with one domain of each subunit replaced by the identical domain from another subunit. The swapped "domain" can be as large as an entire tertiary globular domain, or as small as an alpha-helix or a strand of a beta-sheet. Examples of 3D domain swapping are reviewed that suggest domain swapping can serve as a mechanism for functional interconversion between monomers and oligomers, and that domain swapping may serve as a mechanism for evolution of some oligomeric proteins. Domain-swapped proteins present examples of a single protein chain folding into two distinct structures.

CDC2-CDC28 Kinases↗
PubMed1995

Cholesterol enhances cationic liposome-mediated DNA transfection of human respiratory epithelial cells.

Cationic liposome transfection reagents are useful for transferring polynucleotides into cells, and have been proposed for human pulmonary gene therapy. The effect of adding cholesterol to cationic lipid preparations has been tested by first formulating the cationic lipid N-[1-(2,3-dioleoyloxy)propyl-N-[1-(2-hydroxy)ethyl]-N,N-dimethyl ammonium iodide (DORI) with varying amounts of dioleoylphosphatidylethanolamine (DOPE) and cholesterol. Cholesterol was found to enhance lipid-mediated transfection in both the respiratory epithelial cells and mouse fibroblasts. These findings will facilitate nucleic acid transfection of many cell types including differentiated epithelial cell monolayers, and therefore may be useful for examining gene regulation in various cell types and for developing pulmonary gene therapy.

3T3 Cells↗
PubMed1995

Heterozygosity for long-chain 3-hydroxyacyl-coenzyme A dehydrogenase deficiency and deterioration in liver function in a newborn infant infected with human immunodeficiency virus.

A child with perinatally acquired human immunodeficiency virus infection had rapidly progressive hepatic dysfunction, as had her older sibling who died. Urinary organic acid studies revealed 3-hydroxydicarboxylic aciduria, and cultured skin fibroblasts had reduced activity of 3-hydroxy-coenzyme A dehydrogenase. The introduction of a low fat diet resulted in marked improvement in clinical status and reversal of the liver disease. This case illustrates the necessity of metabolic evaluation in patients with liver dysfunction, even when other causes of liver dysfunction are present.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Clinical and biochemical characterization of short-chain acyl-coenzyme A dehydrogenase deficiency.

OBJECTIVE: We identified two additional patients with short-chain acyl-coenzyme A (CoA), further characterized the clinical and biochemical features of this defect, and compared it with other fatty acid oxidation defects. DESIGN: We have measured the in vitro short-chain acyl-coenzyme A dehydrogenase (SCAD) activity in six affected persons with the electron-transfer flavoprotein-linked assay in the presence and absence of anti-medium-chain acyl-CoA dehydrogenase antibody. Urine organic acids, acylglycines, acylcarnitines, and radiolabeled substrate catabolism by skin fibroblasts were also examined. RESULTS: All patients had some neurologic abnormalities, including hypotonia, hypertonia, or seizures. None of the patients had episodes of hypoglycemia; in the only patient tested, fasting ketogenesis was not impaired. Four patients were initially seen in the neonatal period, two with profound metabolic acidosis and two with mild acidemia; the other two cases were recognized in infancy. Enzymatic analysis of cultured skin fibroblasts demonstrated approximately 10% activity of SCAD when compared with control fibroblasts. Gas chromatography and mass spectrometry of urine revealed that ethylmalonic acid was present in all samples but not always at elevated concentrations; methylsuccinic acid and butyrylglycine were sporadically elevated. n-Butyrylcarnitine was often found in urine and plasma. Radiolabeled substrate metabolism was reduced to 40% to 60% of control values. CONCLUSIONS: Because affected persons do not consistently excrete characteristic metabolites, the diagnosis of this enzymatic deficiency is difficult. It is necessary to collect and analyze several urine and plasma specimens when the diagnosis is being considered in patients with neurologic abnormalities suggestive of this disorder.

Acyl-CoA Dehydrogenase↗
PubMed1995

Transient organic aciduria and persistent lacticacidemia in a patient with short-chain acyl-coenzyme A dehydrogenase deficiency.

A neonate with signs of neurologic dysfunction was noted to have elevated blood lactic acid levels. Organic acid analysis revealed transient elevations in ethylmalonate, methylsuccinate, butyrylglycine, and butyrylcarnitine. Enzyme assay in cultured skin fibroblasts confirmed short-chain acyl coenzyme. A dehydrogenase deficiency. The intermittent nature of the characteristic metabolic markers for this deficiency make diagnosis difficult. The apparent rarity of the disorder may be the result of underdiagnosis.

Acidosis, Lactic↗
PubMed1995

Two alpha subunit donor splice site mutations cause human trifunctional protein deficiency.

Human trifunctional protein catalyzes three steps in mitochondrial beta-oxidation of fatty acids, including the long chain 3-hydroxyacyl-CoA dehydrogenase step. Deficiency of this heterocomplex, which contains 4 alpha and 4 beta subunits, causes sudden unexplained infant death, a Reye-like syndrome, cardiomyopathy, or skeletal myopathy. We determined the molecular basis of this deficiency in a patient with neonatal presentation and later sudden death using reverse transcription and PCR amplification of his alpha subunit mRNA. We demonstrated a universal deletion of exon 3 (71 bp) in his mRNA. This deletion causes a frameshift and very early premature termination. Amplification of genomic DNA demonstrated that the patient was a compound heterozygote with two different mutations in the 5' donor splice site following exon 3: a paternally inherited G to A transversion at the invariant position +1 and a maternally inherited A to G mutation at position +3. Both allelic mutations apparently cause exon 3 skipping, resulting in undetectable levels of alpha subunit protein, and complete loss of trifunctional protein. This is the initial molecular characterization of trifunctional protein deficiency.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1995

Inborn errors of metabolism diagnosed in sudden death cases by acylcarnitine analysis of postmortem bile.

Fatty acid oxidation (FAO) disorders represent a frequently misdiagnosed group of inborn errors of metabolism. Some patients die at the first episode of fasting intolerance and, if appropriate investigations are not undertaken, often meet the criteria of sudden infant death syndrome (SIDS). To expand existing protocols for the postmortem diagnosis of FAO and other metabolic disorders, we tested the hypothesis that analysis for acylcarnitine in bile, a specimen readily available at autopsy, may be utilized for diagnostic purposes. Using electrospray/tandem mass spectrometry, we analyzed for acylcarnitine postmortem bile specimens from two infants with long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency, one infant with glutaryl-CoA dehydrogenase deficiency, and 17 uninformative SIDS cases as controls. The affected cases, and none of the controls, showed marked accumulation of C10-C18 acylcarnitines or glutarylcarnitine (acyl/free carnitine ratio: 5.2, 2.7, and 1.9, respectively; controls 0.2 +/- 0.1). In one patient, all other diagnostic methods were uninformative, suggesting that bile acylcarnitine profiling could lead to identification of previously overlooked cases.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1995

The cost of implementation of the Clinical Laboratory Improvement Amendments of 1988--the example of pediatric office-based cholesterol screening.

OBJECTIVE: To measure the additional costs of office-based laboratory testing due to the implementation of the Clinical Laboratory Improvement Amendments of 1988 (CLIA '88), using cholesterol screening for children as an example. METHODS: Four- to ten-year-old children who received their well child care at one of seven participating pediatric practices were screened for hypercholesterolemia. The average number of analyses per day and days per month were derived from the volume of testing completed by the practices. Nurses and technicians time in the screening process were measured and personnel costs were calculated based on salary and fringe benefit rates. Costs of supplies, analyzing control samples, instrument calibration, and instrument depreciation were included. Costs estimates of screening were then completed. CLIA '88 implementation costs were derived from appropriate proficiency testing and laboratory inspection programs. RESULTS: In six practices completing a low volume of testing, 2807 children (5 to 6 children per week) were screened during the observation period, while 414 (about 25 children per week) were screened in one high-volume practice implementing universal screening over a 4-month period. For the six low-volume practices, the cost of screening was $10.60 per child. This decreased to $5.47 for the high-volume practice. Estimated costs of CLIA '88 implementation, including additional proficiency testing and laboratory inspection, added $3.20 per test for the low-volume practices, and $0.71 per test for the high-volume testing. CONCLUSIONS: Implementation of CLIA adds significantly to the cost of office-based chemistry laboratory screening. Despite these additional expenses, the cost of testing is still within a reasonable charge for laboratory testing, and is highly sensitive to the volume of tests completed.

Calibration↗
PubMed1994

Long-chain 3-hydroxyacyl-coenzyme A dehydrogenase (L-CHAD) deficiency in a patient with the Bannayan-Riley-Ruvalcaba syndrome.

Bannayan-Riley-Ruvalcaba syndrome (BRRS) is an autosomal dominant condition of macrocephaly in combination with lipomas/hemangiomas, hypotonia, developmental delay, and a lipid myopathy. The etiology of the lipid storage myopathy has been unclear. We describe a black boy with findings of BRRS who also has a defect in long-chain fatty acid oxidation expressed in cultured skin fibroblasts as a deficiency of long-chain-L-3-hydroxyacyl-CoA dehydrogenase (L-CHAD). He also has an abnormal brain MRI and increased size of both lower limbs. We present this child because of his unusual combination of findings, and postulate that L-CHAD deficiency may be the cause of the lipid myopathy in BRRS.

3-Hydroxyacyl CoA Dehydrogenases↗