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Biomedical subjects

H M Fales

Publications and source records attributed to H M Fales.

At least 55 records · Page 3Linked to original sources
PubMed1990

Brain concentrations of benzodiazepines are elevated in an animal model of hepatic encephalopathy.

Brain extracts from rats with hepatic encephalopathy due to thioacetamide-induced fulminant hepatic failure contained 4- to 6-fold higher concentrations of substances that inhibit radioligand binding to benzodiazepine receptors than corresponding control rat extracts. Both isocratic and gradient-elution HPLC indicated that this inhibitory activity was localized in 3-8 peaks with retention times corresponding to deschlorodiazepam, deschlorolorazepam, lorazepam, oxazepam, diazepam, and N-desmethyldiazepam. The presence of diazepam and N-desmethyldiazepam was confirmed by mass spectroscopy. Both mass spectroscopic and radiometric techniques indicated that the concentrations of N-desmethyldiazepam and diazepam in brain extracts from encephalopathic rats were 2-9 and 5-7 times higher, respectively, than in control brain extracts. While benzodiazepines have been identified previously in mammalian and plant tissues, this report demonstrates that concentrations of these substances are increased in a pathophysiological condition. These findings provide a rational basis for the use of benzodiazepine receptor antagonists in the management of hepatic encephalopathy in humans.

Animals↗
PubMed1990

Uric acid is a major antioxidant in human nasal airway secretions.

Airway mucosal surfaces are potentially subjected to a variety of oxidant stresses. Airway submucosal glands secrete a variety of compounds that may protect the airways from injury. Cholinergically induced nasal submucosal gland secretion has recently been found to contain a low molecular weight nasal antioxidant. In this report, the isolation and identification of this nasal secretory antioxidant are described. Concentrated, cholinergically induced human nasal secretions were fractionated through a 10-kDa sieve and subjected to DEAE anion-exchange chromatography. Fractions containing antioxidant activity were subjected to gel filtration with Bio-Gel P-2 gel (resolution range, 200-2000 Da). The resultant antioxidant fractions were then desalted by gel filtration over the same column equilibrated in HPLC-grade water, yielding only a single peak with antioxidant activity. The absorption spectrum of the purified antioxidant revealed peaks at 238 and 292 nm at pH 7. These peaks shifted to 230 and 280 nm in 0.1 M HCl and 226 and 296 nm in 0.1 M NaOH. Sodium borohydride reduction of the antioxidant had no effect on the UV absorption, whereas platinum-catalyzed hydrogenation ablated all absorption peaks. Uric acid had identical absorption peaks and showed the same chromatographic behavior as the nasal antioxidant activity on both gel filtration and DEAE columns. Uricase (which degrades uric acid) metabolized both uric acid and the purified antioxidant. Uric acid was shown to have antioxidant activity at concentrations greater than 1.5 microM. These data indicate that nasal secretions contain uric acid that serves as an antioxidant.

Antioxidants↗
PubMed1990

Oxysterols and alcoholic liver disease.

A new theory is presented implicating oxidative cholesterol metabolism and oxysterols as possible factors in the development of alcoholic liver disease. Our present studies have revealed the accumulation of cholesta-3,5-dien-7-one, 13.05 +/- 2.75 micrograms/g (n = 8), and cholesta-4,6-dien-3-one, 2.26 +/- 0.88 micrograms/g (n = 8) in fatty alcoholic liver, as compared with controls, 0.21 +/- 0.12 microgram/g (n = 7) and 0.3 +/- 0.33 microgram/g (n = 7), respectively. Acetaldehyde at 1 to 6 micromolar concentration in the blood and tissues of alcoholics cannot account for the extent of tissue damage, nor can it adequately explain liver steatosis characterized by accumulation of cholesterol and fatty acids and their esters in the liver of alcoholics known for their poor dietary habits. Oxysterols may be the primary cause for the development of alcoholic liver diseases and damage to accessory tissues. Significantly lower levels of 7-ketocholesterol in fatty liver, 6.8 +/- 3.5 micrograms/g (n = 8), as compared with control, 36.85 +/- 22.25 micrograms/g (n = 7), may be responsible for the increased cholesterol content of the alcoholic liver due to the inhibitory properties of this sterol on HMG-CoA reductase in cholesterol biosynthesis.

Cholesterol↗
PubMed1989

Alkylation of cyclomalto-oligosaccharides (cyclodextrins) with dialkyl sulfate-barium hydroxide: heterogeneity of products and the marked effect of the size of the macrocycle.

The alkylation of cyclomalto-oligosaccharides (cyclodextrins, CDs) with dialkyl sulfate-barium hydroxide has been claimed to yield 2,6-di-O-alkyl derivatives. Re-investigation by plasma desorption-m.s. of the products of laboratory methylation of alpha CD, beta CD, or gamma CD and ethylation of beta CD and several commercial preparations revealed them to be mixtures with broad and roughly symmetrical distributions of the degree of substitution. Recrystallization separated the components only partially. Analysis of the product of methylation of a mixture of CDs established the order of reactivity gamma much greater than alpha greater than or equal to beta. The reactivity of gamma CD thus resembles that of amylose.

Alkylation↗
PubMed1989

Sex pheromones in snakes.

The majority of pheromones identified to date are insect pheromones, which are volatile in nature. Identification of nonvolatile pheromones have been relatively rare, especially in vertebrates. Male and female garter snakes use pheromones to mediate sexual behavior. The female sex attractiveness pheromone of the Canadian red-sided garter snake, Thamnophis sirtalis parietalis, consists of a novel series of nonvolatile saturated and monounsaturated long-chain methyl ketones, whereas the male sex recognition pheromone contains squalene. These compounds were isolated, identified, and partially synthesized, and field tests show them to be biologically active.

Animals↗
PubMed1989

Comparison of 252Cf plasma desorption mass spectrometry and fast atom bombardment mass spectrometry in identification of simple monoglucosyl conjugates.

The fast atom bombardment (glycerol) and 252Cf plasma desorption mass spectra of 16 simple monoglucosyl conjugates have been compared. Plasma desorption mass spectrometry, in general, has been found to be the superior technique for characterizing these low molecular weight conjugates because of the relative absence of interfering matrix peaks.

Glucosides↗
PubMed1988

Isolation and characterization of a hydroxyacid-oxoacid transhydrogenase from rat kidney mitochondria.

A transhydrogenase that catalyzes the oxoacid-dependent oxidation of specific hydroxyacids has been found in rat kidney, liver, and brain. The hydroxyacids that have been found to be substrates for this enzyme are gamma-hydroxybutyrate, D-alpha-hydroxyglutarate, and L-beta-hydroxybutyrate. The oxoacids that are the best substrates for this enzyme are alpha-ketoglutarate and succinic semialdehyde; alpha-ketoadipate and oxalacetate are also substrates. This enzyme is located in the mitochondrial fraction of the cell and is not dependent on added NAD+ or NADP+.

3-Hydroxybutyric Acid↗
PubMed1988

2-Hydroxypropyldigitonin: synthesis and properties of preparations differing in degree of substitution.

Reaction of propylene oxide with digitonin in strong aqueous alkali yielded water soluble, nontoxic solubilizers of drugs and hormones, the molecular composition of which could be fully deduced from plasma desorption mass spectrometry data. Preparations with average degrees of substitution ranging from 0.7 to 4.5 were investigated, and all the distributions of degrees of substitution observed were relatively narrow and symmetrical; thus, the reactivity of primary and secondary hydroxyls of saponin and of its conversion products had to be quite similar. The effects of the average degree of substitution of 2-hydroxypropyldigitonins on the formation of micelles and on the solubilization of four drugs into aqueous solutions were found to be minor. On the other hand, the ability to hemolyze erythrocytes decreased sharply with an increasing average degree of substitution.

Animals↗
PubMed1988

Amorphous water-soluble cyclodextrin derivatives: 2-hydroxyethyl, 3-hydroxypropyl, 2-hydroxyisobutyl, and carboxamidomethyl derivatives of beta-cyclodextrin.

The pharmaceutical usefulness of natural, crystalline cyclodextrins can be improved by chemical conversions into water-soluble, amorphous mixtures of their derivatives. Reaction of beta-cyclodextrin with 2-chloroethanol, 3-chloropropanol, isobutylene oxide, or iodoacetamide yielded the title compounds. Distributions of the substitution degree were close to symmetrical and relatively narrow. The average substitution degrees increased with the amount of alkylating reagent used in the preparation. The number of components (half-width of distribution) increased with increasing average substitution degree. Further, distributions of the substitution degree were measured in glucose derivatives after hydrolysis of 2-hydroxyethyl, 2-hydroxypropyl, and 2-hydroxyisobutyl-beta-cyclodextrin. The results show an uneven distribution of substituents around the cyclodextrins, suggesting that growth of oligoglycol side chains and/or clustering of substituents on one glucose residue occurs.

Chemical Phenomena↗
PubMed1988

Crisamicin C, a new isochromanequinone antibiotic. Isolation, structure determination, and biosynthesis.

Micromonospora purpureochromogenes subsp. halotolerans was found to produce crisamicin C, a novel antibiotic, together with crisamicin A. Crisamicin C was purified by silica gel column chromatography and its physico-chemical properties, structure and biosynthesis were studied. Crisamicin C, mp 260 degrees C (dec), showed UV maxima at 392 (epsilon 9,497), 261 (epsilon 32,959) and 232 nm (epsilon 24,623) in CH3CN, and gave an IR spectrum with absorbances at 1782 (lactone), 1705 and 1655 (quinone) cm-1. Crisamicin C plasma desorption mass spectrometry (PD-MS) m/z 615.9 [M + H)+, hydroquinone) was 16 amu higher than crisamicin A PD-MS m/z 600 [M + H)+, hydroquinone) suggesting that the two antibiotics differ by one additional oxygen in crisamicin C. Analysis of 1H and 13C NMR spectra, in comparison with those of crisamicin A, indicated that crisamicin C was the 4'a, 10'a epoxide derivative of crisamicin A. Carbon-thirteen labeled acetate feeding experiments were used to confirm the positions of the epoxide and other structural features. Crisamicin C was a more potent antibiotic than crisamicin A, but shared the same spectrum of antimicrobial activity (Gram-positive only).

Anti-Bacterial Agents↗
PubMed1987

Reaction of cyclodextrins with propylene oxide or with glycidol: analysis of product distribution.

Reaction of cyclomalto-hexaose, -heptaose, or -octaose with propylene oxide in strong aqueous alkali gave products in which distribution of the degrees of substitution was relatively narrow and nearly symmetrical, and increased with the average degree of substitution. When an equimolar mixture of cyclomalto-hexaose, heptaose, or -octaose was used, the average degrees of substitution of all three carbohydrates were close to each other. These findings indicate that the reactivities of the hydroxyl groups of cyclomalto-hexaose, -heptaose, or -octaose, and of all their (2-hydroxypropyl) ethers formed in the reactions, are quite similar. Reaction of cyclomaltoheptaose with glycidol also yielded a product having a narrow distribution of degree of substitution, but which was slightly skewed towards the higher degrees. Thus, as it proceeds, this etherification leads to products having higher reactivity towards the epoxide.

Cyclodextrins↗
PubMed1987

Detection of trehalose monomycolate in Mycobacterium leprae grown in armadillo tissues.

Trehalose-6-monomycolate (TMM) was isolated from the lipids of armadillo-derived Mycobacterium leprae. Only meagre amounts of this glycolipid were recovered, but its structure was unequivocally established. Only alpha-mycolates were detected in the TMM by 252Cf plasma desorption mass spectrometry. Electron impact mass spectrometry showed the alpha branch to be principally C20. Trehalose dimycolate (cord factor) was not detectable. Since we have also found TMM in M. lepraemurium and in every Mycobacterium species so far examined, we suggest that this glycolipid is truly ubiquitous amongst mycobacteria.

Animals↗
PubMed1987

The brain's own clonidine: purification and characterization of endogenous clonidine displacing substance from brain.

An endogenous clonidine-like substance was isolated from bovine brain and characterized by its chemical and pharmacological properties. The clonidine displacing substance (CDS) is a noncatecholamine, nonpeptide compound. It is devoid of NH2-group, is thermostable, and has a molecular weight of 587.8 +/- 2 daltons. CDS binds selectively to alpha 2-adrenergic receptors in rat brain membranes as measured by displacement of specifically bound [3H]clonidine, an alpha 2-adrenergic agonist, and [3H]rauwolscine, an alpha 2-antagonist, with no affinity for alpha 1-adrenergic receptors. In physiological studies CDS mimics clonidine's action as an inhibitor of the electrically induced twitch response and as a partial agonist of the epinephrine-induced platelet aggregation. At the central nervous system CDS antagonizes clonidine action, increases mean arterial pressure when injected into the nucleus reticularis lateralis of rats, and reduces the hypotensive effect upon intracisternal injection. CDS, which interacts at alpha 2-adrenergic receptors and increases mean arterial pressure upon intracerebral injection, may represent a neuroregulator that plays an important role in cardiovascular events.

Animals↗
PubMed1986

Predominant osmotically active organic solutes in rat and rabbit renal medullas.

The mechanism that concentrates the urine to an osmolality several times that of systemic plasma results in high concentrations of solutes (particularly NaCl and urea) in extracellular fluid of renal medulla, but not in the labyrinth of the renal cortex. Intracellular and extracellular osmolality must be equal in animals, but the known intracellular levels of Na and K salts and urea in renal medullas are much too low to balance the high extracellular osmolality. The purpose of these studies was to identify the other intracellular osmolytes that must be present. Cortexes and medullas from rabbit and rat kidneys were analyzed by proton nuclear magnetic resonance, mass spectrometry, and chemical assays to determine the identity and amount of organic solutes. Large amounts of glycerophosphorylcholine, betaine, sorbitol, and inositol were found in both species localized almost exclusively to the inner medulla. In rabbits during antidiuresis glycerophosphorylcholine, betaine, and sorbitol were present in the inner medulla, at concentrations of 21.1, 34.8, and 20.8 mumol/g wet weight, respectively, but were not detected in the cortex. Inositol was present in rabbit inner medulla at 10.7 mumol/g wet weight and was also present in the cortex, but at lower concentration. None of the above metabolites was present in measurable amounts in urine or peripheral plasma. The accumulation in the cells of the inner medulla of relatively large amounts of betaine, sorbitol, glycerophosphorylcholine and inositol during antidiuresis suggests that they may play a significant role in the maintenance of intracellular osmotic balance.

Animals↗
PubMed1986

Separation of the components of commercial digitonin using high-performance liquid chromatography and centrifugal countercurrent chromatography. Identification of the products by californium-252 plasma desorption mass spectrometry.

Commercial digitonin has been separated into its components using high-performance liquid chromatography and centrifugal countercurrent chromatography. The individual glucosides have been identified by californium-252 plasma desorption mass spectrometry, occasionally supplemented by hydrolysis and analysis of the liberated sugars and aglycones. Mass spectra of commercial digitonin that have appeared in the literature are discussed in the light of their complex nature. A new glycoside of molecular weight 1035 is described and a structure proposed.

Californium↗
PubMed1986

Californium-252 plasma desorption mass spectrometry of skin lipids. Positive and negative ions formed by attachment processes.

Californium-252 plasma desorption mass spectra have been run on a series of typical lipids found in skin, including a fatty acid, a methyl and wax ester, a mono-, di- and triglyceride and an anhydride, in a effort to discover the nature of peaks caused by fingerprint contamination of the sample holders. The triglyceride was identified as the source, and peaks found by reattachment of abundant fragment ions to the original lipid were noted in several cases.

Californium↗