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Biomedical subjects

J M Hayes

Publications and source records attributed to J M Hayes.

At least 127 records · Page 7Linked to original sources
PubMed1987

Isotopic compositions and probable origins of organic molecules in the Eocene Messel shale.

The sediments that now comprise the Messel shale accumulated 47 +/- 2 million years ago in anaerobic waters at the bottom of a lake. Subsequent depths of burial have not exceeded 300 m, nor has the temperature of the shale exceeded 40 degrees C. Contents of organic carbon reach 25%, and preservation of molecular structures has been excellent. Sixteen different geoporphyrins, including three derived from bacteriochlorophylls of the d series and thus indicative of the existence in the lake of an anaerobic photic zone, have been isolated and identified. Here, we show that the carbon isotopic compositions of these and other biomarkers allow identification of specific sources for some materials and reconstruction of carbon flows within the lake and its sediments. The 13C content of organic matter synthesized by lacustrine primary producers can be estimated from the observed 13C content of the geoporphyrins derived from their chlorophylls. Total organic material in the shale is depleted in 13C by six parts per thousand relative to that input. This difference cannot be explained by selective loss of components enriched in 13C, nor, as shown by isotopic compositions of other biomarkers, by inputs from land plants surrounding the lake or from methanogenic bacteria.

Bacteriochlorophylls↗
PubMed1987

Solvent exchange of buried water and hydrogen exchange of peptide NH groups hydrogen bonded to buried waters in bovine pancreatic trypsin inhibitor.

Solvent exchange of 18O-labeled buried water in bovine pancreatic trypsin inhibitor (BPTI), trypsin, and trypsin-BPTI complex is measured by high-precision isotope ratio mass spectrometry. Buried water is labeled by equilibration of the protein in 18O-enriched water. Protein samples are then rapidly dialyzed against water of normal isotope composition by gel filtration and stored. The exchangeable 18O label eluting with the protein in 10-300 s is determined by an H2O-CO2 equilibration technique. Exchange of buried waters with solvent water is complete before 10-15 s in BPTI, trypsin, and BPTI-trypsin, as well as in lysozyme and carboxypeptidase measured as controls. When in-exchange dialysis and storage are carried out at pH greater than or equal to 2.5, trypsin-BPTI and trypsin, but not free BPTI, have the equivalent of one 18O atom that exchanges slowly (after 300 s and before several days). This oxygen is probably covalently bound to a specific site in trypsin. When in-exchange dialysis and storage are carried out at pH 1.1, the equivalent of three to seven 18O atoms per molecule is associated with the trypsin-BPTI complex, apparently due to nonspecific covalent 18O labeling of carboxyl groups at low pH. In addition to 18O exchange of buried waters, the hydrogen isotope exchange of buried NH groups H bonded to buried waters was also measured. Their base-catalyzed exchange rate constants are on the order of NH groups that in the crystal are exposed to solvent (static accessibility greater than 0) and hydrogen-bonded main chain O, and their pH min is similar to that for model compounds. The pH dependence of their exchange rate constants suggests that direct exchange with water may significantly contribute to their observed exchange rate.

Aprotinin↗
PubMed1987

Graft versus host disease following transfusion of normal blood products to patients with malignancies.

A patient undergoing treatment with cytotoxic chemotherapy for Hodgkin's disease developed graft versus host disease (GVHD) following a transfusion of packed red cells. This is the 28th reported patient with a malignancy who did not have a bone marrow transplant and developed GVHD after transfusion of normal blood or blood products. All patients had received cytotoxic chemotherapy prior to acquiring GVHD. The underlying malignancies included lymphoma, acute leukemia, neuroblastoma, rhabdomyosarcoma, and glioblastoma. Twenty-three of the 28 patients died of GVHD. The incidence of transfusion-related GVHD in this patient population is low but the illness is often fatal as treatment is largely ineffective. Transfusion-related GVHD can be prevented by irradiating all blood products with 1500 rad prior to administration.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1987

Low temperature hydrothermal maturation of organic matter in sediments from the Atlantis II Deep, Red Sea.

Hydrocarbons and bulk organic matter of two sediment cores (No. 84 and 126, CHAIN 61 cruise) located within the Atlantis II Deep have been analyzed. Although the brines overlying the coring areas were reported to be sterile, microbial inputs and minor terrestrial sources the major sedimentary organic material. This input is derived from the upper water column above the brines. Both steroid and triterpenoid hydrocarbons show that extensive acid-catalyzed reactions are occurring in the sediments. In comparison with other hydrothermal (Guaymas Basin) or intrusive systems (Cape Verde Rise), the Atlantis II Deep exhibits a lower degree of thermal maturation. This is easily deduced from the elemental composition of the kerogens and the absence of polynuclear aromatic hydrocarbons of a pyrolytic origin in the bitumen. The lack of carbon number preference among the n-alkanes suggests, especially in the case of the long chain homologs, that the organic matter of Atlantis II Deep sediments has undergone some degree of catagenesis. However, the yields of hydrocarbons are much lower than those observed in other hydrothermal areas. The effect of lower temperature and poor source-rock characteristics appear to be responsible for the differences.

Alkanes↗
PubMed1987

Drug Information Center network: need, effectiveness, and cost justification.

During the past 15 years, the pharmacy profession has experienced much change. Certain pharmacy roles are being challenged and others are coming into existence. Today, health-care practitioners and health-care providers are seeking services not sought before from pharmacists in the area of rational therapeutics. This need for information extends to all pharmacy practice settings: institutional, independent pharmacies, chain stores, governmental agencies, and the pharmaceutical industry. In order to meet this demand for drug and toxicology information, however, the pharmacist must use resources outside the immediate area of his practice. The Drug Information Center (DIC) can be used as such a resource by pharmacists in their daily practice to provide the best possible care with regard to the rational use of drugs for their patients/clients. Specifically, our data indicate that in Tennessee, there is a need for providing drug and toxicology information; pharmacists perceive their role to be providers of drug information as well as drugs; the DIC plays an integral and necessary role as a back-up information resource and in teaching, service, research, and continuing education programs; and the programs provided by the DIC are cost effective and cost justifiable.

Cost-Benefit Analysis↗
PubMed1986

Secular variation in carbon isotope ratios from Upper Proterozoic successions of Svalbard and East Greenland.

Analyses of stratigraphically continuous suites of samples from Upper Proterozoic sedimentary successions of East Greenland, Spitsbergen and Nordaustlandet (Svalbard) provide an approximation to the secular variation in carbon isotope ratios during a geologically and biologically important period of change from around 900 million years ago to the beginning of the Cambrian period. Late Riphean carbonates and organic material show a stratigraphically useful pattern of enrichment in 13C relative to Phanerozoic or earlier Proterozoic samples. Isotopic compositions of isolated samples from other localities are consistent with a worldwide extended interval of enhanced organic burial and consequent net survival of oxidized material, probably O2, just before the initial radiation of metazoans.

Animals↗
PubMed1986

An industrial cause of carpal tunnel syndrome.

A retrospective study was done to determine why a meat packing plant in Illinois had such an unusually high incidence of carpal tunnel syndrome. In the past 12 years, 14.8% of employees at this plant have had a carpal tunnel release. Only two of 117 patients remained unimproved at an average follow-up of 37.4 months. The most consistent result after release was relief of the paroxysmal attacks of burning pain and paresthesia. Weakness of grip was the most significant postoperative complaint in 78%. Highly repetitive motions involving extreme wrist positions, especially flexion and ulnar deviation while grasping, are predominant in meat cutting and probably contribute to the development of carpal tunnel syndrome in this industry. Previous reports of industrial carpal tunnel syndrome have not approached the incidence identified in this study. Patient awareness and Workers' Compensation benefits may account for the high numbers seeking treatment.

Adult↗
PubMed1986

Sulfur isotope effects associated with protonation of HS- and volatilization of H2S.

The isotope effects associated with: (1) formation of H2S from HS- by protonation in aqueous solution; and (2) volatilization of H2S have been experimentally determined. Both isotopic distributions in closed systems at equilibrium and differential rates of volatilization of isotopic species in open systems were measured at 22 +/- 1 degrees C. It was found that, at equilibrium aqueous H2S is enriched in 34S by 2.0 - 2.7% relative to HS- and that H2S volatilized from solution is depleted in 34S by 0.5% relative to dissolved H2S. A small kinetic isotope effect accompanying volatilization of H2S was observed in the open-system experiments.

Geological Phenomena↗
PubMed1985

Exchange of oxygen isotopes in carbon dioxide-phosphoric [correction of phosporic] acid systems.

The rate of exchange of isotopes of oxygen between solutions of concentrated phosphoric acid and CO2 was measured as a function of temperature, acid strength (pressure of water in equilibrium with the solution), pressure of CO2, and surface area of the reaction vessel. At 75 degrees C, significant exchange was found to occur even for the "anhydrous" phosphoric acids, those in which the nominal percentage of H3PO4 in solution is equal to or exceeds 100%. Exchange is much slower at 25 degrees C, but isotopic shifts as large as 0.1% can be observed in 95% H3PO4 at equilibration times approaching 1000 hr. Rates of exchange were found to be dependent upon the vapor pressure of water in equilibrium with the acid solutions. Exchange was found to occur primarily on the surface of the reaction vessel above the solution, with no dependence on total CO2 pressure. These observations indicate that phosphoric acids with nominal concentrations of H3PO4 approaching 105% are preferable for the minimization of exchange between CO2 samples and acid solutions during phosphorolyses of carbonate materials. Moreover, with such acids, significant time--temperature trade-offs are possible, allowing rapid preparation of CO2 at elevated temperatures.

Carbon Dioxide↗
PubMed1985

Isotope effects associated with the anaerobic oxidation of sulfite and thiosulfate by the photosynthetic bacterium, Chromatium vinosum.

The purple photosynthetic bacterium Chromatium vinosum, strain D, catalyzes several oxidations of reduced sulfur compounds under anaerobic conditions in the light: e.g., sulfide --> sulfur --> sulfate, sulfite --> sulfate, and thiosulfate --> sulfur + sulfate. Here it is shown that no sulfur isotope effect is associated with the last of these processes; isotopic compositions of the sulfur and sulfate produced can differ, however, if the sulfane and sulfonate positions within the thiosulfate have different isotopic compositions. In the second process, an observed change from an inverse to a normal isotope effect during oxidation of sulfite may indicate the operation of 2 enzymatic pathways. In contrast to heterotrophic anaerobic reduction of oxidized sulfur compounds, anaerobic oxidations of inorganic sulfur compounds by photosynthetic bacteria are characterized by relatively small isotope effects.

Anaerobiosis↗
PubMed1985

Experimental parameters affecting hypercoulometric response in gas-phase coulometry.

The response of an electron-capture detector designed for coulometric response was examined as a function of solute, pulse interval, carrier-gas type, solute amount, carrier-gas flow rate, and chromatographic-peak profile. For CCl3F, it was shown that the average numbers of electrons absorbed per molecule ranged from 1.0 to 4.1, varying primarily with pulse interval but also displaying a complex dependence on sample amount. Comparison of these results with theoretical expectations leads to the conclusion that a 1:1 "coulometric response" may not be observed under certain operating conditions. Because the specific conditions required depend on many variables, including, to some extent, sample amount, true coulometric operation of an electron-capture detector is difficult to establish and maintain. Effects which may contribute to the production of hypercoulometric response are critically discussed.

Calibration↗
PubMed1985

Isotopic analyses based on the mass spectrum of carbon dioxide.

Measurements of carbon and oxygen isotopic abundances are commonly based on the mass spectrum of carbon dioxide, but analysis of that spectrum is not trivial because three isotope ratios (17O/16O, 18O/16O, and 13C/12C) must be determined from only two readily observable ion-current ratios (45/44 and 46/44). Here, approaches to the problem are reassessed in the light of new information regarding the distribution of oxygen isotopes in natural samples. It is shown that methods of calculation conventionally employed can lead to systematic errors in the computed abundance of 13C and that these errors may be related to incorrect assessment of the absolute abundance of 17O. Further, problems arising during the analysis of samples enriched by admixture of 18O-labeled materials are discussed, and it is shown (i) that serious inaccuracies arise in the computed abundance of 17O and 13C if methods of calculation conventionally employed in the analysis of natural materials are applied to material labeled with 18O but (ii) that computed fractional abundances of 18O are always within 0.4% of the correct result. Methods for exact calculation of two isotope ratios when the third is known are presented and discussed, and a more exact approach to the computation of all three isotope ratios in natural materials is given.

Carbon Dioxide↗