A highly sensitive and simple reversed phase high performance liquid chromatographic (HPLC) method for the quantitative determination of free fatty acids in human serum is presented. The method is based on the direct derivatization of serum fatty acids with 6,7-dimethoxy-1-methyl-2(1H)-quinoxalinone-3-propionylcarboxylic acid hydrazide. The derivatization reaction proceeds in aqueous solution in the presence of pyridine and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide at 37 degrees C. The resulting derivatives are separated within 75 min on a reversed phase column (YMC Pack C8) with a gradient elution of aqueous acetonitrile and detected fluorimetrically. The detection limits are 2.5-5 fmol in a 10 microL injection volume. The sensitivity permits precise determination of free fatty acids in 5 microL serum. The method is simple and is without the conventional liquid-liquid extraction steps of serum fatty acids.

Chromatography, High Pressure Liquid↗

PubMedDate not supplied

Direct determination of free phenylacetic acid in human plasma and urine by column-switching high performance liquid chromatography with fluorescence detection.

A simple and highly sensitive column-switching high performance liquid chromatographic method with fluorescence detection for the determination of free phenylacetic acid (PAA) in human plasma and urine is described. The method is based on the direct derivatization of plasma and urine PAA with 6,7-dimethoxy-1-methyl-2(1H)-quinoxalinone-3-propionylcarboxylic acid hydrazide (DMEQ-hydrazide). The derivatization reaction proceeds in aqueous solution in the presence of pyridine and 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide at 37 degrees C. The resulting DMEQ derivative of PAA is separated from endogenous interfering substances by a column-switching chromatographic system consisting of a precolumn (YMC-Pack C4) for sample clean-up and an analytical column (L-Column ODS) for the complete separation of the derivative. The derivative is detected fluorimetrically at 445 nm with excitation at 367 nm. The detection limits (signal to noise ratio = 3) for PAA is 10 fmol in a 10 microL injection volume. The recoveries from plasma and urine are 75 and 96%, respectively. The present method is highly sensitive and simple compared to conventional liquid-liquid extraction procedures. The sensitivity allows the direct determination of free PAA in an extremely small amount (5 microL) of plasma and urine.

Adult↗

PubMedDate not supplied

Amiloride enhances atrial natriuretic factor stimulation of cGMP accumulation in rat glomeruli.

The effects of amiloride on ANF binding and ANF stimulation of cGMP were evaluated in rat glomeruli. Amiloride increased ANF binding to whole glomeruli and to glomerular membrane preparations. In contrast, amiloride enhanced ANF-stimulated cGMP accumulation only at 37 degrees C in whole glomeruli, but not at 4 degrees C in whole glomeruli or at 37 degrees C in membrane preparations. These data suggest that under physiological conditions amiloride augments ANF-stimulated intracellular cGMP accumulation. The discrepancies between amiloride augmentation of ANF binding and failure to increase ANF-stimulated cGMP accumulation may result from ANF receptor heterogeneity. This is the first report of an amiloride augmentation of ANF-stimulated cGMP accumulation in renal tissue.

Amiloride↗

PubMedDate not supplied

Phorbol and calcium decreased atriopeptin response in a human renal cell line.

We investigated regulation of atrial natriuretic factor (ANF)-stimulated cellular cGMP accumulation (ANF-s-cGMP) in an ANF-responsive human renal cell line, SK-NEP-1. Dose-response data indicated that the EC50 for ANF(99-126) was 1.1 x 10(-9) M. Brain natriuretic peptide (10(-6) M) increased cGMP to a level indistinguishable from that of ANF (10(-6) M). [Met-(O)]ANF was only half as potent as ANF, and atriopeptin I (10(-6) M) did not increase cGMP over basal levels. Preincubation of SK-NEP-1 cells with ANF, but not atriopeptin I (API), for two hours or longer, caused a concentration-dependent down-regulation of ANF-s-cGMP. Phorbol 12-myristate 13-acetate (PMA), a protein kinase C (PKC) activator, and A23187 and its 4-bromo derivative, calcium ionophores, inhibited ANF-s-cGMP in a dose-dependent manner. A23187 inhibition was calcium dependent and promoted net cGMP degradation. Thirty-six hour preincubation with PMA, a procedure used to down-regulate PKC, abolished acute PMA inhibition of ANF-s-cGMP without having an effect on ANF-s-cGMP or on 4-bromo-A23187 inhibition thereof. These data indicate that PKC activation specifically inhibited ANF-s-cGMP but that PKC was not required for ANF-s-cGMP in SK-NEP-1 cells. Thus structurally related ANF peptides, protein kinase C (PKC) activators, calcium ionophores are potential modulators of ANF-s-cGMP in cells from this human renal cell line.

Atrial Natriuretic Factor↗

PubMedDate not supplied

Improved production of poly(4-hydroxybutyrate) by Comamonas acidovorans and its freeze-fracture morphology.

Production of poly(4-hydroxybutyrate) [P(4HB)] by Comamonas acidovorans JCM10181 was studied by introducing additional copies of its PHA synthase gene and the beta-ketothiolase gene. A multi-copy-number broad-host-range plasmid vector, pJRD215, was modified to contain the strong hybrid trc promoter in order to express these genes in the wild-type C. acidovorans. Increased copy-number of genes resulted in significant increase in the activities of corresponding enzymes, which could further be increased by inducing with isopropyl-beta-D-thiogalactopyranoside (IPTG), indicating that the expression is under the transcriptional control of the trc promoter. P(4HB) biosynthesis in the recombinant C. acidovorans increased 2-fold to constitute more than 60 wt% of the dry cell weight. No significant decrease in the number-average molecular weights of P(4HB) in the recombinant strain was observed when compared with that of the wild-type. Freeze-fracture electron microscopy of intracellular P(4HB) granules revealed almost similar fracture morphology to the well-known mushroom-type deformation shown by polyhydroxyalkanoates with medium-chain-length monomers.

Acetyl-CoA C-Acyltransferase↗

PubMedDate not supplied

Properties and biodegradability of ultra-high-molecular-weight poly[(R)-hydroxybutyrate] produced by a recombinant Escherichia coli.

Ultra-high-molecular-weight poly[(R)-3-hydroxybutyrate] (P(3HB)) (Mw = 3-11 x 10(6)) was produced from glucose by a recombinant Escherichia coli XL1-Blue (pSYL105) harboring Ralstonia eutropha H16 polyhydroxyalkanoate (PHA) biosynthesis genes. Morphology of ultra-high-molecular-weight P(3HB) granules in the recombinant cells was studied by transmission electron microscopy. The recombinant E. coli contained several P(3HB) granules within a cell. Freeze-fracture morphology of ultra-high-molecular-weight P(3HB) granules showed the needle-type as that of P(3HB) granules in R. eutropha. Both the P(3HB) granules in wet cells and wet native granules isolated from the recombinant cells proved to be amorphous on the X-ray diffraction patterns. Mechanical properties of ultra-high-molecular-weight P(3HB) films were markedly improved by stretching over 400%, resulting from high crystallinity and highly oriented crystal regions. Biodegradability of the films of ultra-high-molecular-weight P(3HB) was tested with an extracellular polyhydroxybutyrate depolymerase from Alcaligenes faecalis T1. The rate of enzymatic erosion of P(3HB) films was not dependent of the molecular weight but was dependent of the crystallinity. In addition, it is demonstrated that all ultra-high-molecular-weight P(3HB) films were completely degraded at 25 degrees C in a natural river freshwater within 3 weeks.

Acyltransferases↗

PubMedDate not supplied

Structure and enzymatic degradation of poly(3-hydroxybutyrate) copolymer single crystals with an extracellular PHB depolymerase from Alcaligenes faecalis T1.

Lamellar single crystals of four random copolymers of (R)-3-hydroxybutyrate with different hydroxyalkanoates: poly(3-hydroxybutyrate-co-8 mol%-3-hydroxyvalerate) (P(3HB-co-8%-3HV)), poly(3-hydroxybutyrate-co-10 mol%-4-hydroxybutyrate) (P(3HB-co-10%-4HB)), poly(3-hydroxybutyrate-co-8 mol%-3-hydroxyhexanoate) (P(3HB-co-8%-3HH)) and poly(3-hydroxybutyrate-co-10 mol%-6-hydroxyhexanoate) (P(3HB-co-10%-6HH)), were grown from dilute solutions of chloroform and ethanol. All single crystals have lath-shaped morphology and the second monomer units seem to be excluded from the P(3HB) crystal, on the basis of the electron diffraction diagrams. The enzymatic degradation of P(3HB-co-8%-3HH) and P(3HB-co-10%-6HH) single crystals was investigated with an extracellular PHB depolymerase from Alcaligenes faecalis T1. Adsorption of an extracellular PHB depolymerase, examined using an immuno-gold labelling technique, demonstrated a homogeneous distribution of enzyme molecules with a low concentration on the crystal surfaces. Enzymatic degradation of single crystals progressed from the edges and ends of crystals to yield narrow cracks along their long axes and the small crystal fragments. Lamellar thicknesses of single crystals and molecular weights of copolymer chains remained unchanged during the enzymatic hydrolysis. The above results support the hypothesis that the hydrophobic adsorption of the enzyme contributes to increase the mobility of molecular chains of single crystals and generate the disordered chain-packing regions. The active-site of PHB depolymerase takes place preferentially at the disordered chain-packing regions of crystal edges and ends with endo-exo enzymatic hydrolysis behaviour, termed processive degradation.

Adsorption↗

PubMedDate not supplied

Crystallization behavior and thermal properties of melt-crystallized poly[(R)-3-hydroxybutyric acid-co-6-hydroxyhexanoic acid] films.

Melt-crystallized films of poly[(R)-3-hydroxybutyric acid-co-10mol% 6-hydroxyhexanoic acid] (P[(R)-3HB-co-6HH]) were prepared by isothermal crystallization at various temperatures for 3 days, and subsequently stored at room temperature after the films formed well-developed and volume-filled spherulites. The lamellar morphologies and properties of melt-crystallized films were characterized by means of wide-angle X-ray diffraction, small-angle X-ray scattering, differential scanning calorimetry, transmission electron microscopy, and atomic force microscopy. The melting endotherm of P[(R)-3HB-co-6HH] films was composed of a broad peak starting around room temperature and of a sharper peak starting above the isothermal crystallization temperature. The stacking of flat-on lamellae with lamellar periodicity of 8-10 nm was detected on the surface of P[(R)-3HB-co6HH] films after the primary crystallization at 110 degrees C. On storage at room temperature above the Tg (-5 degrees C) of copolyester, thin crystals of 1-4 nm thickness appeared on the surface of P[(R)-3HB-co-6HH] films crystallized at 110 degrees C. These results suggest that long sequences of (R)-3HB units in a random copolyester form relatively thick P[(R)-3HB] crystalline lamellae during the primary crystallization process at a given crystallization temperature, while shorter sequences of (R)-3HB units, which are incapable of crystallizing at a given crystallization temperature, form relatively thin crystalline lamellae during the subsequent crystallization process at room temperature.

Calorimetry, Differential Scanning↗

PubMedDate not supplied

Internal echo histogram examination has a role in distinguishing malignant tumors from benign masses in the breast.

We analyzed the histograms of reflecting ultrasound (US) from the internal areas of the masses of 50 lesions in the breast. The central average of gravity and the ratio between lower and higher width in the histograms were compared as the parameters. Statistical significance were found in both parameters between malignant tumors and benign masses (P<.001, P<.01). Therefore, analysis of histograms based on reflecting US was useful in making differential diagnoses of malignant tumors and benign masses in the breast.

Breast Neoplasms↗

PubMedDate not supplied

Percutaneous radiofrequency lesioning of sensory branches of the obturator and femoral nerves for the treatment of hip joint pain.

BACKGROUND AND OBJECTIVES: The sensory innervation of the hip joint includes the sensory articular branches of the obturator and femoral nerves. In this report, we retrospectively evaluated 14 cases in which hip joint pain was treated by percutaneous radiofrequency lesioning of sensory branches of obturator and/or femoral nerves. METHODS: Fourteen patients who had hip joint pain and underwent percutaneous radiofrequency lesioning of sensory branches of obturator and/or femoral nerves were studied. In all cases, intra-articular hip joint block or articular branch block of obturator nerve with local anesthesia was transiently effective. Radiofrequency lesioning was performed at 75 degrees C to 80 degrees C for 90 seconds using an RFG-3B generator and Sluijter-Mehta cannulae kit (Radionics, Burlington, MA) for the obturator nerve in 9 patients and for both the obturator and femoral nerves in 5 patients. To assess pain intensity, a visual analog scale (VAS) was used. RESULTS: The VAS scores before and after the radiofrequency lesioning were 6.8 +/- 0.9 and 2.7 +/- 1.3, respectively. Twelve patients (86%) reported at least 50% relief of pain for 1 to 11 months. There were no side effects or motor weakness observed. CONCLUSIONS: Percutaneous radiofrequency lesioning of sensory branches of the obturator and femoral nerves is an alternative treatment in patients with hip joint pain, especially in those where operation is not applicable.

Adult↗

PubMedDate not supplied

Involvement of the pineal body in the Bi-Digital O-Ring Test.

As an interesting exception to the general clinical application of the Bi-Digital O-Ring Test (BDORT), the test could not be performed successfully in diagnosing a patient who suffered from cancer of the pineal body. The following examinations were attempted using the BDORT: 1) The thymus representation area, 2) the distal forearm during compression of the upper arm, 3) surface representations of diseased areas that had previously been identified by the indirect method with slide preparations of pineal body or lung cancer tissue, 4) holding of oncogene c-fos Ab2 and integrin alpha 5 beta 1. Results suggest that the failure of the BDORT might be due to the absence of pineal body function. It is suggested that the sensor for the BDORT might exist in the pineal body since 1) BDORT cannot be successfully performed when the eyes are closed, and the pineal body is sensitive to light; 2) electromagnetic resonance might stimulate this sensor; and 3) N-acetyltransferase, the enzyme that converts serotonin to methylserotonin in the pineal body, might be inhibited by activation of this sensor. As a result, serotonin levels might be increased by activation of this sensor, which might then inhibit finger flexor muscle contraction needed to maintain an O-ring in BDORT.

Adenocarcinoma↗