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PubMed2007

Biochemical and molecular characterization of 18 patients with pyridoxine-dependent epilepsy and mutations of the antiquitin (ALDH7A1) gene.

Patients with pyridoxine dependent epilepsy (PDE) present with early-onset seizures resistant to common anticonvulsants. According to the benefit of pyridoxine (vitamin B(6)) and recurrence of seizures on pyridoxine withdrawal, patients so far have been classified as having definite, probable, or possible PDE. Recently, PDE has been shown to be caused by a defect of alpha-amino adipic semialdehyde (AASA) dehydrogenase (antiquitin) in the cerebral lysine degradation pathway. The accumulating compound piperideine-6-carboxylic acid (P6C) was shown to inactivate pyridoxalphosphate (PLP) by a Knoevenagel condensation. Pipecolic acid (PA) and AASA are markedly elevated in urine, plasma, and cerebrospinal fluid (CSF) and thus can be used as biomarkers of the disease. We have investigated 18 patients with neonatal seizure onset, who have been classified as having definite (11), probable (four), or possible (three) PDE. All patients had elevated PA and AASA in plasma (and urine) while on treatment with individual dosages of pyridoxine. Within this cohort, molecular analysis identified 10 novel mutations (six missense mutations, one nonsense mutation, two splice site mutations) within highly conserved regions of the antiquitin gene. Seven mutations were located in exonic sequences and two in introns 7 and 17. Furthermore, a novel deletion of exon 7 was identified. Two of the 36 alleles investigated require further investigation. A known mutation (p.Glu399Gln) was found with marked prevalence, accounting for 12 out of 36 alleles (33%) within our cohort. Pyridoxine withdrawal is no longer needed to establish the diagnosis of "definite" PDE. Administration of pyridoxine in PDE may not only correct secondary PLP deficiency, but may also lead to a reduction of AASA (and P6C) as presumably toxic compounds.

Aldehyde Dehydrogenase↗
PubMed1995

Anti-tumor and anti-angiogenic effects in mice of heparin conjugated to angiostatic steroids.

Heparin-steroid conjugates have been prepared by linking a non-anti-coagulating derivative of heparin, which binds to endothelial cells, to an angiostatic steroid, which suppresses endothelial cell division. One such conjugate, heparin adipic hydrazide (HAH) linked to cortisol, has previously been shown to inhibit both angiogenesis and the growth of solid tumors in mice. In the present study, heparin hydrazide (HH) was linked to tetrahydro S, tetrahydrocortisone and tetrahydrocortisol, which are devoid of glucocorticoid and mineralocorticoid activity and hence were predicted to have low toxicity to animals. The tetrahydro steroid conjugates were compared with the cortisol conjugate for therapeutic effectiveness against solid Lewis lung carcinoma growing in mice. HAH-cortisol reduced tumor growth by up to 75% whereas a simple mixture of HAH and cortisol was not significantly inhibitory. In contrast to HAH-cortisol, the 3 tetrahydro steroid conjugates did not significantly inhibit tumor growth. The differences in anti-tumor properties of the conjugates correlated with their ability to inhibit angiogenesis in a Matrigel implant model in mice. The tetrahydro steroid conjugates did not significantly inhibit angiogenesis whereas HAH-cortisol inhibited angiogenesis by greater than 90%. Therefore, HAH-cortisol is the most effective heparin-steroid conjugate so far developed.

Animals↗
PubMed2004

Attachment of hyaluronan to metallic surfaces.

Metal implants are in general not compatible with the tissues of the human body, and in particular, blood exhibits a severe hemostatic response. Herein we present results of a technique to mask the surface of metals with a natural biopolymer, hyaluronan (HA). HA has minimal adverse interactions with blood and other tissues, but attachment of bioactive peptides can promote specific biological interactions. In this study, stainless steel was cleaned and then surface-modified by covalent attachment of an epoxy silane. The epoxy was subsequently converted to an aldehyde functional group and reacted with hyaluronan through an adipic dihydrazide linkage, thus covalently immobilizing the HA onto the steel surface. Fluorescent labeling of the HA showed that the surface had a fairly uniform covering of HA. When human platelet rich plasma was placed on the HA-coated surface, there was no observable adhesion of platelets. HA derivatized with a peptide containing the RGD peptide sequence was also bound to the stainless steel. The RGD-containing peptide was bioactive as exemplified by the attachment and spreading of platelets on this surface. Furthermore, when the RGD peptide was replaced with the nonsense RDG sequence, minimal adhesion of platelets was observed. This type of controlled biological activity on a metal surface has potential for modulating cell growth and cellular interactions with metallic implants, such as vascular stents, orthopedic implants, heart valve cages, and more.

Amino Acid Sequence↗
PubMed2004

Hyaluronic acid grafting mitigates calcification of glutaraldehyde-fixed bovine pericardium.

Pathologic calcification is the leading cause of the clinical failure of glutaraldehyde-fixed bovine pericardium used in bioprosthetic valves. A novel surface modification of glutaraldehyde fixed bovine pericardium was carried out with high molecular weight hyaluronic acid (HA). HA was chemically modified with adipic dihydrazide (ADH) to introduce hydrazide functional groups onto the HA backbone. Glutaraldehyde-fixed bovine pericardium (GFBP) was modified by grafting this HA to the free aldehyde groups on the tissue via the hydrazide groups. Following a 2-week subcutaneous implantation in osteopontin (OPN)-null mice, the calcification of HA-modified bovine pericardium was drastically reduced (by 84.5%) compared to positive controls (tissue without HA-modification) (p = 0.005). The calcification-mitigating effect of HA surface modification was also confirmed by microscopic analysis of explanted tissue stained with Alizarin Red S for calcium.

Animals↗
PubMed2006

Selectively crosslinked hyaluronic acid hydrogels for sustained release formulation of erythropoietin.

A novel sustained release formulation of erythropoietin (EPO) was developed using hyaluronic acid (HA) hydrogels. For the preparation of HA hydrogels, adipic acid dihydrazide grafted HA (HA-ADH) was synthesized and analyzed with (1)H NMR. The degree of HA-ADH modification was about 69%. EPO was in situ encapsulated into HA-ADH hydrogels through a selective cross-linking reaction of bis(sulfosuccinimidyl) suberate (BS(3)) to hydrazide group (pK(a) = 3.0) of HA-ADH rather than to amine group (pK(a) > 9) of EPO. The denaturation of EPO during HA-ADH hydrogel synthesis was drastically reduced with decreasing pH from 7.4 to 4.8. The specific reactivity of BS(3) to hydrazide at pH = 4.8 might be due to its low pK(a) compared with that of amine. In vitro release of EPO in phosphate buffered saline at 37 degrees C showed that EPO was released rapidly for 2 days and then slowly up to 4 days from HA-ADH hydrogels. When the hydrogels were dried at 37 degrees C for a day, however, longer release of EPO up to 3 weeks could be demonstrated. According to in vivo release test of EPO from HA-ADH hydrogels in SD rats, elevated EPO concentration higher than 0.1 ng/mL could be maintained from 7 days up to 18 days depending on the preparation methods of HA-ADH hydrogels. There was no adverse effect during and after HA-ADH hydrogel implantation.

Animals↗
PubMed1986

Heterogeneity of sodium-dependent excitatory amino acid uptake mechanisms in rat brain.

The pharmacologic and kinetic characteristics of sodium-dependent uptake of [3H]L-glutamate, [3H]D-aspartate, and [3H]L-aspartate into crude synaptosomal preparations of rat corpus striatum and cerebellum have been examined in vitro. In cerebellum the apparent Kts and Vmax for the three excitatory amino acids were identical whereas in striatal synaptosomes, the Vmax for [3H]L-glutamate was 30% greater (P less than or equal to .001) than for [3H]D-aspartate and 50% greater (P less than or equal to .001) than for [3H]L-aspartate. L-Amino adipic acid inhibited the uptake of the three amino acids in both regions of brain was 15- to 20-fold more potent in cerebellum than in striatum. In contrast, dihydrokainic acid inhibited transport processes in the corpus striatum but was without activity in cerebellar preparations. The neurotoxin kainic acid blocked only a portion (60%) of [3H]L-glutamate and [3H]D-aspartate uptake in cerebellum while completely inhibiting amino acid transport in corpus striatum. Three days post kainic acid lesion, [3H]D-aspartate uptake was attenuated more than [3H]L-glutamate uptake in the corpus striatum; destruction of corticostriatal afferents reduced [3H]L-glutamate to a greater extent than [3H]D-aspartate. Various lesions of the cerebellum affected excitatory amino acid transport processes to a similar extent. These results suggest that excitatory amino acid transport systems are pharmacologically distinct in different brain regions and may be heterogeneous within a single region.

Animals↗
PubMed1986

Putative glutamate receptors in membranes obtained from heads of Drosophila melanogaster.

The specific binding of L-[3H]-glutamic acid (GLU) was examined in membrane preparations derived from heads of Drosophila melanogaster. L-[3H]-GLU bound to the membrane preparation with biphasic kinetics in a reversible and saturable way. The specific binding was inhibited by Cl- and Ca2+ ions. Saturation analysis of the data fit a model of two independent binding sites with dissociation constants (KD) of 29 nM and 249 nM and corresponding binding site densities (Bmax) of 5.7 and 24.6 pmol/mg protein. A series of excitatory amino acid receptor agonists and antagonists were tested as inhibitors of L-[3H]-GLU specific binding. Some compounds almost totally abolished the specific binding, whereas others reduced the binding to 45% over the concentration range used. Among the first type of inhibitors, L-GLU was the most potent, D-aspartate (D-ASP) and D-GLU were 10 times less effective than L-GLU, whereas quisqualic acid had the lowest potency. Among the second type of inhibitors, glutamate diethyl ester, D-alpha-amino adipate, and N-methyl-D-aspartate showed the highest potency, and DL-2-amino-4-phosphonobutyrate was the less effective. Kainic acid and gamma-amino butyric acid were not able to modify at any concentration used the specific binding of L-[3H]-GLU. These data suggest the presence of putative GLU receptors in the brain of Drosophila.

Animals↗
PubMed2001

Simultaneous optimization based on artificial neural networks in ketoprofen hydrogel formula containing O-ethyl-3-butylcyclohexanol as percutaneous absorption enhancer.

The influence of the amounts of additives including 1-O-ethyl-3-n-butylcyclohexanol (OEBC), diisopropyl adipate (DIA), and isopropanol (IPA) on the penetration rate (R(p)) of ketoprofen from hydrogels through rat skin in vivo was investigated. Skin irritation evoked by the application of hydrogels was evaluated based on a microscopic observation of skin cross-sections. Both optimization techniques incorporating an artificial neural network (ANN) and a second-order polynomial regression analysis were applied to the optimization of ketoprofen hydrogel formulations. Findings indicated that the R(p) and total irritation score (TIS) of the skin were predicted quantitatively as a function of quantities of OEBC, DIA, and IPA, employing ANN. In contrast, the prediction ability of the polynomial regression equation was somewhat poorer compared with that of ANN. The observed results of R(p) and TIS in the optimal formulation coincided well with the predictions in the simultaneous optimization technique incorporating ANN.

Animals↗
PubMed1982

Antitumor agents XLV: Bisbrusatolyl and brusatolyl esters and related compounds as novel potent antileukemic agents.

A series of new bisbrusatolyl and brusatolyl esters and related compounds were synthesized and tested for in vivo antileukemia activity against a quassinoid sensitive strain of P-388 lymphocytic leukemia in BDF1 mice. The bisbrusatolyl malonate, succinate, glutarate, adipate, and sebacate were as active or more active than brusatol. The C-3 esters of brusatol and bruceantin were also found to be as active or more active than brusatol or bruceantin in general. The free hydroxyl groups at C-11 and C-12 as well as the enone double bond in ring A of both bisbrusatolyl and brusatolyl esters are required for antileukemic activity. The presence of a double bond in the ester side chain contributes to the enhanced activity of these esters.

Animals↗
PubMed1983

Antitumor agents LXII: synthesis and biological evaluation of podophyllotoxin esters and related derivatives.

Synthetic esters of the C-4 hydroxyl group of podophyllotoxin (I) were prepared. In addition, esters were synthesized using the diol system of tetrahydropyranyl podophyllol (XV), produced by reducing the lactone ring of tetrahydropyranyl podophyllotoxin with lithium aluminum hydride. Six compounds, the acrylate (IV), 3,3-dimethyl acrylate (V), phenoxyacetate (IX), and ethyl adipate (XI) of I as well as podophyllol (XIV) and tetrahydropyranyl podophyllol dimesylate (XVIII), showed significant activity when tested using the P-388 lymphocytic leukemia screen at 3 mg/kg/day. None of the esters showed higher activity than that shown by the parent molecule I when tested at the same dosage level.

Animals↗
PubMed1994

Influence of pH and plasticizers on drug release from ethylcellulose pseudolatex coated pellets.

Six potential plasticizers for an ethylcellulose (EC) pseudolatex coating system (Aquacoat) were evaluated at three levels (25, 30, and 35%) to study the influence of these additives on the release of a model compound, propranolol hydrochloride, from pellets in two different media, dilute HCl and phosphate buffer, pH 7.4. For the majority of the plasticizers, the release rate decreased when larger amounts of plasticizer were incorporated into the coating. However, for the plasticizers dibutyl sebacate and dibutyl adipate, no further reduction in the release rate was observed following dissolution testing in dilute HCl when the level of plasticizer was increased from 30 to 35%. This suggests that the saturation capacity of these plasticizers in the film coating had been exceeded. The media pH was found to influence the dissolution characteristics of the coatings. Faster release rates as well as earlier curve inflection points and T50% values were observed for plasticizers evaluated in phosphate buffer. All plasticizers used were independent of pH. Correlation of the dissolution results with properties of free films indicated that slower release (more complete film formation) is associated with softer and weaker films with greater elongation.

Buffers↗
PubMed1995

Enhancing effects of lipophilic vehicles on skin penetration of methyl nicotinate in vivo.

Vehicle effects may be caused by thermodynamic effects and by specific (penetration enhancing) effects. To investigate the effects of various lipophilic vehicles on drug penetration, an in vivo permeability study was conducted with methyl nicotinate as the model drug. The drug was dissolved in the respective vehicles at concentrations that provide equal drug escaping tendencies. Drug solutions were applied to the upper arms of volunteers with a glass chamber system. To avoid drug depletion effects, drug disappearance rates were measured under steady-state conditions by the difference method. Enhancement factors were calculated from the steady-state flux values (i.e., drug disappearance rates per area unit) and compared with results from non-steady-state experiments. Significant enhancing effects (p < 0.01) were observed with dibutyl adipate, caprylic/capric acid triglycerides containing 5% phospholipids, isopropyl myristate, and mineral oil. Caprylic/capric acid triglycerides, cetearyl isooctanoate, and the standard vehicle dimethicone 100 were without effect on drug penetration. The explanation for the observed enhancing effects may be an interaction of the lipophilic liquids with the lipid bilayers of the stratum corneum that leads to a decrease of the barrier resistance.

Adult↗
PubMed2004

Transformation of biodegradable polyesters into cyclic oligomers under continuous flow using an enzyme-packed column.

The enzymatic degradation of typical chemically synthesized biodegradable plastics, such as poly(butylene adipate) and poly(epsilon-caprolactone), to a repolymerizable cyclic oligomer under continuous flow using an enzyme column was studied, directed towards green chemical recycling. It was confirmed that both polymers were quantitatively transformed into the corresponding cyclic oligomers by passage through the column packed with immobilized lipase from Candida antarctica (Novozym 435) at 40 degrees C using a toluene solution. Compared to the batch treatment in a flask, a short reaction time and a low reaction temperature occurred for complete transformations of the polyesters by continuous flow through the enzyme column. The degradation activity of the enzyme column was maintained for at least six months at 40 degrees C. Conceptual scheme of the continuous degradation equipment using the enzyme column.

Biocompatible Materials↗
PubMed2006

Characterization of typical chemical background interferences in atmospheric pressure ionization liquid chromatography-mass spectrometry.

The structures and origins of typical chemical background noise ions in positive atmospheric pressure ionization liquid chromatography/mass spectrometry (API LC/MS) are investigated and summarized in this study. This was done by classifying chemical background ions using precursor and product ion scans on most abundant background ions to draw a family tree of the commonly occurring chemical background ions. The possible structures and the origins of the major chemical background noise are clearly revealed in the family trees. In agreement with some suggestions in the literature, the chemical background ions studied so far can be classified mainly as either ions of contaminants (or their degradation fragments) or cluster-related ones. A significant contribution from the contaminants (airborne, from tubing and/or solvents) from plasticizer additives (phthalates, phenyl phosphates, sebacates and adipates, etc.) and silicones is concluded. These ions of contaminants can also serve as nuclei for the clustering of HPLC solvent or additives, such as water and acetic acid, thereby leading to a second family of background ions. This study explains the persistence of some chemical background noise even under fairly strong declustering conditions in API LC/MS. One of the other interesting conclusions is that there is a clear difference in structures between the chemical background ions and the protonated analytes generated under atmospheric pressure ionization. This conclusion will contribute to the on-going research efforts to exclusively remove or reduce the interference of chemical background noise in API LC/MS.

Journal Article↗
PubMed2003

Identification and fragmentation study of plasticizers with post-source decay matrix-assisted laser desorption/ionization mass spectrometry.

A detailed investigation of the most commonly used plasticizers, such as phthalate, adipate and trimellitate esters, using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) and post-source decay (PSD) MALDI-TOFMS/MS is described. It is shown that PSD MALDI-TOFMS/MS is capable of unambiguous determination of the different types of plasticizers. The determination of the types of plasticizers from different PVC samples by PSD MALDI-TOFMS/MS, without the need for solvent extraction, is also demonstrated. The fragmentation mechanisms of these plasticizers cationized with protons and sodium ions are also reported.

Journal Article↗
PubMed1999

Comparison of methods of immobilization to enzyme-linked immunosorbent assay plates for the detection of sugar chains.

The immobilization of carbohydrates for solid-phase assays, including enzyme-linked immunosorbent assay (ELISA), is difficult because they are hydrophilic. We developed four new methods for the immobilization of oligosaccharides. ELISA plates were first coated with methyl vinyl ether-maleic anhydride copolymer (MMAC) and an excess of active anhydride groups was introduced. They were subsequently reacted, in four different ways, to bind oligosaccharides. In method 1, the anhydride groups were reacted with hydrazide groups, in the presence of adipic acid dihydrazide, and then coupled to the reducing ends of sugar chains by reductive amination. In method 2, the anhydride groups were reacted with p-aminophenyl glycoside obtained by reduction with p-nitrophenyl glycoside. In method 3, the anhydride groups were reacted with 1, 6-hexamethylenediamine. Aminooxy groups were coupled to the amino groups introduced and then aminooxyacetic acid with carbodiimide and ligated to oligosaccharides by oxime formation. In method 4, stereospecifically aminated oligosaccharides reacted with the anhydride groups. We compared, in solid-phase assays systems, the ability of lectins to detect oligosaccharides immobilized with either one of these four new methods or one of the two methods previously described. Detection of sugars with lectins is useful because, in most cases, they recognize sugars stereospecifically. The immobilization method should therefore be carefully selected to avoid changing the configuration and substitution in C-1.

Carbohydrates↗
PubMed1999

Conversion of lysine to N(epsilon)-(carboxymethyl)lysine increases susceptibility of proteins to metal-catalyzed oxidation.

Metal-catalyzed oxidation (MCO) of proteins leads to the conversion of some amino acid residues to carbonyl derivatives, and may result in loss of protein function. It is well documented that reactions with oxidation products of sugars, lipids, and amino acids can lead to the conversion of some lysine residues of proteins to N(epsilon)-(carboxymethyl)lysine (CML) derivatives, and that this increases their metal binding capacity. Because post-translational modifications that enhance their metal binding capacity should also increase their susceptibility to MCO, we have investigated the effect of lysine carboxymethylation on the oxidation of bovine serum albumin (BSA) by the Fe(3+)/ascorbate system. Introduction of approximately 10 or more mol CML/mol BSA led to increased formation of carbonyls and of the specific oxidation products glutamic and adipic semialdehydes. These results support the view that the generation of CML derivatives on proteins may contribute to the oxidative damage that is associated with aging and a number of age-related diseases.

Aging↗
PubMed1998

A simple and rapid method for measuring unconjugated capsular polysaccharide (PRP) of Haemophilus influenzae type b in PRP-tetanus toxoid conjugate vaccine.

The authors developed a simple and rapid method for quantitation of free capsular polysaccharide of Haemophilus influenzae type b (polyribosyl ribitol phosphate, PRP) in PRP-tetanus toxoid conjugate vaccine based on acid precipitation of tetanus toxoid (TT). Acid hydrolysis of PRP during the assay was not detected. The conditions used in the assay did not precipitate unconjugated PRP or adipic acid dihydrazide derivatized PRP. The method was highly reliable, reproducible and sensitive. The accuracy of the assay was confirmed by spiking known amounts of unconjugated PRP to PRP-TT conjugate preparations. A PRP-TT preparation, incubated at 37 degrees C for 6 months showing most of the PRP as unconjugated (87% determined by this method), was not immunogenic in mice for the PRP component even after two injections. In contrast, the same preparation held at 4 degrees C for 20 months, showing 17% unconjugated PRP, induced IgG antibodies to PRP which were boosted after second injection. Therefore, this method is very useful to evaluate the stability of PRP-TT conjugate vaccine. The assay may be useful for characterizing other polysaccharide-protein conjugate vaccines.

Animals↗