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Biomedical subjects

J M Hayes

Publications and source records attributed to J M Hayes.

At least 55 records · Page 3Linked to original sources
PubMed1994

Effect of HLA matching on organ distribution among whites and African-Americans.

A total of 159 patients received renal cadaveric grafts under 2 different allocation systems. System 1, a local variance (i.e., a point system different from that of United Network for Organ Sharing [UNOS]), and system 2, the current UNOS point system, differed in the relative emphasis on waiting time and HLA match. The racial composition of the donor pools and recipient waiting lists was the same for both periods examined. The percentage of African-Americans transplanted did not differ significantly under the 2 allocation systems and, in fact, increased slightly, from 29.4% to 33.8%, under system 2, which attributed more weight to HLA match. A difference in the allocation of kidneys from African-American donors was seen. Under system 1, only 2 of 8 kidneys from African-American donors went to African-American recipients, while under system 2, 6 of 8 kidneys from African-American donors went to African-American recipients. These data suggest that the current UNOS point system does not provide any added disadvantage to non-whites and may, in fact, provide an incentive for minority groups to donate organs, in that HLA matching appears to promote intraracial transplantation.

Black People↗
PubMed1994

Nucleotide sequence of the Salmonella typhi groEL heat shock gene.

Heat shock proteins (HSP) have been shown to elicit a strong immune response during infection by a variety of pathogens. The HSP60 gene of Salmonella typhi was amplified using oligonucleotide primers based on the Escherichia coli groEL sequence. The nucleotide sequence of the amplified fragment was determined and used to predict the amino acid sequence of S. typhi GroEL. The E. coli and S. typhi proteins were found to be highly similar; however, several non-conservative substitutions near the carboxy-termini of the two polypeptides were found. Knowing the amino acid sequence of the S. typhi HSP60 homologue will enhance our knowledge of host immune recognition of HSP produced by bacterial pathogens.

Amino Acid Sequence↗
PubMed1994

Porphyrin and chlorin distributions in a Late Pliocene lacustrine sediment.

The tetrapyrroles in a highly immature Late Pliocene lacustrine sediment (Willershausen, Germany) show a simple distribution of both chlorin and porphyrin components as the free bases. The major components are C32 desoxophylloerythroaetioporphyrin (DPEP), a C33 bicycloalkano porphyrin, the chlorin analogue of the latter, and desoxophylloerythrin and its chlorin counterpart. The structure of the novel bicycloalkano chlorin was determined using a combination of two-dimensional phase-sensitive COSY NMR and nOe studies. Measurements of delta 13C and other data indicate that DPEP and the bicycloalkano porphyrin were derived from the chlorophyll(s) of photosynthetic organisms utilising a common source of CO2, probably diatoms. The occurrence of DPEP and other minor alkyl porphyrins indicates that the chlorophyll defunctionalisation pathway leading to these components can occur at low temperature and was probably biologically mediated, as was the condensation leading to the fused ring components.

Aluminum Silicates↗
PubMed1994

A molecular and isotopic study of the organic matter from the Paris Basin, France.

Thirteen Liassic sedimentary rocks of increasing depth and three petroleums from the Paris Basin were studied for 13C/12C isotopic compositions and biological markers, including steranes, sterenes, methylphenanthrenes, methylanthracenes, and triaromatic steroids. The isotopic compositions of n-alkanes from mature sedimentary rocks and petroleums fall in a narrow range (2%), except for the deepest Hettangian rock and the Trias petroleum, for which the short-chain n-alkanes are enriched and depleted in 13C, respectively. Most of the molecular parameters increase over the 2000-2500 m depth range, reflecting the transformation of the organic matter at the onset of petroleum generation. In this zone, carbonate content and carbon isotopic composition of carbonates, as well as molecular parameters, are distinct for the Toarcian and Hettangian source rocks and suggest a migration of organic matter from these two formations. Two novel molecular parameters were defined for this task: one using methyltriaromatic steroids from organic extracts; the other using 1-methylphenanthrene and 2-methylanthracene from kerogen pyrolysates. The anomalous high maturity of the Dogger petroleum relative to the maturity-depth trend of the source rocks is used to estimate the minimal vertical distance of migration of the organic matter from the source rock to the reservoir.

Alkanes↗
PubMed1994

Acquisition and processing of data for isotope-ratio-monitoring mass spectrometry.

Methods are described for continuous monitoring of signals required for precise analyses of 13C, 18O, and 15N in gas streams containing varying quantities of CO2 and N2. The quantitative resolution (i.e. maximum performance in the absence of random errors) of these methods is adequate for determination of isotope ratios with an uncertainty of one part in 10(5); the precision actually obtained is often better than one part in 10(4). This report describes data-processing operations including definition of beginning and ending points of chromatographic peaks and quantitation of background levels, allowance for effects of chromatographic separation of isotopically substituted species, integration of signals related to specific masses, correction for effects of mass discrimination, recognition of drifts in mass spectrometer performance, and calculation of isotopic delta values. Characteristics of a system allowing off-line revision of parameters used in data reduction are described and an algorithm for identification of background levels in complex chromatograms is outlined. Effects of imperfect chromatographic resolution are demonstrated and discussed and an approach to deconvolution of signals from coeluting substances described.

Alkanes↗
PubMed1994

Isotope-ratio-monitoring gas chromatography-mass spectrometry: methods for isotopic calibration.

In trial analyses of a series of n-alkanes, precise determinations of 13C contents were based on isotopic standards introduced by five different techniques and results were compared. Specifically, organic-compound standards were coinjected with the analytes and carried through chromatography and combustion with them; or CO2 was supplied from a conventional inlet and mixed with the analyte in the ion source, or CO2 was supplied from an auxiliary mixing volume and transmitted to the source without interruption of the analyte stream. Additionally, two techniques were investigated in which the analyte stream was diverted and CO2 standards were placed on a near-zero background. All methods provided accurate results. Where applicable, methods not involving interruption of the analyte stream provided the highest performance (sigma = 0.00006 at.% 13C or 0.06% for 250 pmol C as CO2 reaching the ion source), but great care was required. Techniques involving diversion of the analyte stream were immune to interference from coeluting sample components and still provided high precision (0.0001 < or = sigma < or = 0.0002 at.% or 0.1 < or = sigma < or = 0.2%).

Alkanes↗
PubMed1994

Predictive isotopic biogeochemistry: hydrocarbons from anoxic marine basins.

Carbon isotopic compositions were determined for individual hydrocarbons in water column and sediment samples from the Cariaco Trench and Black Sea. In order to identify hydrocarbons derived from phytoplankton, the isotopic compositions expected for biomass of autotrophic organisms living in surface waters of both localities were calculated based on the concentrations of CO2(aq) and the isotopic compositions of dissolved inorganic carbon. These calculated values are compared to measured delta values for particulate organic carbon and for individual hydrocarbon compounds. Specifically, we find that lycopane is probably derived from phytoplankton and that diploptene is derived from the lipids of chemoautotrophs living above the oxic/anoxic boundary. Three acyclic isoprenoids that have been considered markers for methanogens, pentamethyleicosane and two hydrogenated squalenes, have different delta values and apparently do not derive from a common source. Based on the concentration profiles and isotopic compositions, the C31 and C33 n-alkanes and n-alkenes have a similar source, and both may have a planktonic origin. If so, previously assigned terrestrial origins of organic matter in some Black Sea sediments may be erroneous.

Bacteria↗
PubMed1994

Partial resolution of sources of n-alkanes in the saline portion of the Parachute Creek Member, Green River Formation (Piceance Creek Basin, Colorado).

Systematic variations in the 13C contents of individual extractable n-alkanes (C16-C29) can be modelled quantitatively and interpreted as indicating contributions from at least five distinct sources. These appear to be cyanobacterial (C16-C18, delta 13C = -37% vs PDB), phytoplanktonic (C16-C23, delta = -32%), chemoautotrophic bacterial (C20-C29, delta = -38%), phytoplanktonic or heterotrophic bacterial (C20-C29, delta = -30%), and vascular plants (C23-C29, delta = -29%). Hydrous pyrolysis of related kerogens yields large quantities of additional n-alkanes with different and much more uniform delta values. The latter materials are apparently derived from the thermolysis of aliphatic biopolymers whose presence in the Green River Oil Shale has been recognized visually.

Alkanes↗
PubMed1994

The effect of aromatization on the isotopic compositions of hydrocarbons during early diagenesis.

Polycyclic aromatic hydrocarbons with varying degrees of aromatization were isolated from the Eocene Messel Shale (Rheingraben, Germany). The high abundances of these compounds and their structural resemblances to cyclic triterpenoid lipids are consistent with derivation from microbial rather than thermal processes. Compounds structurally related to oleanane contain from five to nine double bonds; those within a series of aromatized hopanoids contain from three to nine. All are products of diagenetic reactions that remove hydrogen or methyl groups, and, in several cases, break carbon-carbon bonds to open rings. Aromatized products are on average depleted in 13C relative to possible precursors by l.2% (range: l.5% enrichment to 4% depletion, n = 9). The dependence of 13C content on the number of double bonds is not, however, statistically significant and it must be concluded that there is no strong evidence for isotopic fractionation accompanying diagenetic aromatization. Isotopic differences between series (structures related to ursane, des-A-ursane, des-A-lupane, des-A-arborane, and possibly, des-A-gammacerane are present) are much greater, indicating that 13C contents are controlled primarily by source effects. Fractionations due to chromatographic isotope effects during HPLC ranged from 0.1 to 2.8%.

Carbon Isotopes↗
PubMed1994

A molecular and carbon isotopic study towards the origin and diagenetic fate of diaromatic carotenoids.

Pyrolysates of high-molecular-weight sedimentary fractions of the Duvernay Formation (Western Canada Basin) are dominated by 1,2,3,4- and 1,2,3,5-tetramethylbenzene, which, generated via beta-cleavage, indicate the presence of diaromatic carotenoids in the macromolecular aggregates. This was substantiated by desulphurization of sulphur-rich aggregates of the polar fraction, which released (partly) hydrogenated carotenoids. Furthermore, these components were important constituents of the aromatic hydrocarbon fractions and related oils. Apart from renieratane and isorenieratane, 1H NMR analysis established the aromatic substitution pattern of the most abundant component present, which was identified as a diaromatic compound with an unprecedented 2,3,6-/3,4,5-trimethyl aromatic substitution pattern. Molecular and isotopic analyses of both soluble and insoluble fractions of organic matter revealed relationships between diagenetically-derived carotenoids found in bitumen and related oils and their precursors incorporated into high-molecular-weight fractions. Aryl isoprenoids, important components in extracts and oils, were apparently derived from thermal cracking of bound diaromatic carotenoids rather than cleavage of free carotenoids as previously suggested. Furthermore, products derived from diaromatic carotenoids were substantially enriched in 13C relative to n-alkanes of algal origin. Together with the characteristic carotenoids, this isotopic enrichment provides evidence of significant contributions from photosynthetic green sulphur bacteria (Chlorobiaceae), which fix carbon via the reversed tricarboxylic acid (TCA) cycle. In spite of the prominence of these molecular signals, the overall isotopic composition of the organic matter indicated that only a very small portion of the preserved organic carbon was derived from the biomass of photosynthetic green sulphur bacteria.

Canada↗
PubMed1994

Long-term results of renal transplantation into the valve bladder.

Between 1970 and 1990 renal transplantation was performed in 16 patients with a history of posterior urethral valves. While 10 patients had undergone supravesical urinary diversion before the development of end stage renal disease, all but 1 transplant were drained to the unaugmented native bladder. The 2 and 5-year graft survival rates were 70% and 59%, respectively. Of the 15 surviving patients 11 have allografts that are functioning at a mean of 86 months after transplantation with a mean serum creatinine of 2.0 mg./dl. Urological complications occurred in 19% of the transplants. No detrimental effect of the valve bladder on long-term allograft survival or function was apparent. With appropriate treatment of vesical dysfunction, these patients can be expected to have graft function comparable to the general transplant population despite use of the unaugmented native bladder.

Adolescent↗
PubMed1994

Photosynthetic fractionation of 13C and concentrations of dissolved CO2 in the central equatorial Pacific during the last 255,000 years.

Carbon isotopically based estimates of CO2 levels have been generated from a record of the photosynthetic fractionation of 13C [is equivalent to epsilon(p)] in a central equatorial Pacific sediment core that spans the last approximately 255 ka. Contents of 13C in phytoplanktonic biomass were determined by analysis of C37 alkadienones. These compounds are exclusive products of Prymnesiophyte algae which at present grow most abundantly at depths of 70-90 m in the central equatorial Pacific. A record of the isotopic composition of dissolved CO2 was constructed from isotopic analyses of the planktonic foraminifera Neogloboquadrina dutertrei, which calcifies at 70-90 m in the same region. Values of epsilon(p), derived by comparison of the organic and inorganic delta values, were transformed to yield concentrations of dissolved CO2 [is equivalent to c(e)] based on a new, site-specific calibration of the relationship between epsilon(p) and c(e). The calibration was based on reassessment of existing epsilon(p) versus c(e) data, which support a physiologically based model in which epsilon(p) is inversely related to c(e). Values of PCO2, the partial pressure of CO2 that would be in equilibrium with the estimated concentrations of dissolved CO2, were calculated using Henry's law and the temperature determined from the alkenone-unsaturation index U(K/37). Uncertainties in these values arise mainly from uncertainties about the appropriateness (particularly over time) of the site-specific relationship between epsilon(p) and 1/c(e). These are discussed in detail and it is concluded that the observed record of epsilon(p) most probably reflects significant variations in delta pCO2, the ocean-atmosphere disequilibrium, which appears to have ranged from approximately 110 microatmospheres during glacial intervals (ocean > atmosphere) to approximately 60 microatmospheres during interglacials. Fluxes of CO2 to the atmosphere would thus have been significantly larger during glacial intervals. If this were characteristic of large areas of the equatorial Pacific, then greater glacial sinks for the equatorially evaded CO2 must have existed elsewhere. Statistical analysis of air-sea pCO2 differences and other parameters revealed significant (p<0.01) inverse correlations of delta pCO2 with sea surface temperature and with the mass accumulation rate of opal. The former suggests response to the strength of upwelling, the latter may indicate either drawdown of CO2 by siliceous phytoplankton or variation of [CO2]/[Si(OH)4] ratios in upwelling waters.

Animals↗
PubMed1994

Simultaneous transplantation of the heart and kidney.

BACKGROUND: Multiple organ transplants have become frequent. Combined heart-and-kidney grafting has been reported recently and we have pursued this in selected cases. AIMS: To devise a protocol for simultaneous heart-and-kidney transplantation, review our clinical experience with the procedure and the causes of cardiac and renal disease in this group. METHODS: Seven patients with advanced cardiac failure (LV ejection fraction < 0.29 units; five with IDCM), and chronic renal failure (serum creatinine > 375 mumol/L) due to a variety of causes, were accepted for combined heart-and-kidney transplantation. Four males, of mean age 33 years, underwent the procedure. Each received his organs from a single cadaveric donor with ABO blood group compatibility and a negative 'current' lymphocytotoxic cross-match, but without regard to HLA-antigen matching. Cardiac ischaemic time averaged 3 hours 40 minutes, the renal first warm time was 0 minutes in all cases, and renal cold and second warm ischaemic times averaged 5 hours 17 minutes and 52 minutes respectively. The heart was grafted first and the kidney second in a procedure which averaged seven hours. Immunosuppression was achieved by induction with antithymocyte globulin, thence steroids, azathioprine and cyclosporin A. RESULTS: No patient required post-operative dialysis. One patient had early urological complications requiring operative correction, but no serious opportunistic infections were observed. Early cardiac rejection on biopsy (ISHT grade 3a) was seen in three patients at four-ten weeks and responded promptly to increased steroids, but severe steroid-resistant rejection of both heart and kidney contemporaneously occurred in one of these three at 19 months and required a course of muromonab-CD3. All four patients developed hypertension. Mean creatinine clearance was 1.23 +/- 0.22 mL/second (74 +/- 13 mL/minute) at last follow-up. All four recipients were alive, well and rehabilitated 5, 20, 28 and 35 months after grafting. Two patients died while waiting for the double procedure and another patient eventually died after being taken off the dual waiting list and receiving a renal transplant only. CONCLUSIONS: In experienced hands, combined heart-and-kidney transplantation is feasible and offers a compelling therapeutic solution in the treatment of advanced cardiac and renal failure. IDCM is a frequent cause of the heart failure in this group.

Adolescent↗
PubMed1994

Carbon isotope effects associated with aceticlastic methanogenesis.

The carbon isotope effects associated with synthesis of methane from acetate have been determined for Methanosarcina barkeri 227 and for methanogenic archaea in sediments of Wintergreen Lake, Michigan. At 37 degrees C, the 13C isotope effect for the reaction acetate (methyl carbon) --> methane, as measured in replicate experiments with M. barkeri, was - 21.3% +/- 0.3%. The isotope effect at the carboxyl portion of acetate was essentially equal, indicating participation of both positions in the rate-determining step, as expected for reactions catalyzed by carbon monoxide dehydrogenase. A similar isotope effect, - 19.2% +/- 0.3% was found for this reaction in the natural community (temperature = 20 degrees C). Given these observations, it has been possible to model the flow of carbon to methane within lake sediment communities and to account for carbon isotope compositions of evolving methane. Extension of the model allows interpretation of seasonal fluctuations in 13C contents of methane in other systems.

Acetates↗
PubMed1994

Isotopic biogeochemistry of the Oxford Clay Formation (Jurassic), UK.

A total of 165 samples was obtained from the Oxford Clay Formation at seven different sites. Nearly all were from the Peterborough Member (Lower Oxford Clay), but seven were from the Stewartby and Weymouth Members (Middle and Upper Oxford Clay respectively). Five samples from the underlying Kellaways Formation were also examined. Stratigraphic relationships were estimated on the basis of ammonite subzones and results from all locations can be placed along a single stratigraphic scale. The following were determined for all samples: abundance and isotopic composition of organic carbon, abundances of carbonate carbon and total sulphur, and the Rock-Eval pyrolysis parameters hydrogen index, oxygen index and Tmax. For a subset of eight samples selected to be representative of geochemical and apparent palaeoenvironmental variations, soluble organic compounds were extracted and the isotopic composition of pristane, phytane, and long-chain n-alkanes determined by isotope-ratio-monitoring gas chromatograph mass spectrometry. Concentrations of organic carbon in samples from the Peterborough Member ranged from 0.5 to 16.6 % and delta values of total organic carbon (TOC) ranged from -27.7 to -23.1% v. PDB. Shales dominated by epifaunal bivalve assemblages have high concentrations of TOC and values of H index approaching 800, indicating preservation of hydrogen-rich organic material. Conversely, shell beds and calcareous and silty clay beds have lower abundances of TOC and values of H index dropping below 100, indicating extensive oxidation of the organic matter. Isotopic composition of pristane and phytane in the Peterborough and Stewartby Members average -31.7%, those in the Weymouth Member average -29.8. Values of delta for long-chain n-alkanes average -28%. Together these results indicate delta values for primary inputs as follows: terrestrial vascular plants, -23.5%; Peterborough Member algae, -28.2; Stewartby Member algae, -29.1%; Weymouth Member algae, -26.6% Comparison of primary delta values to those of TOC indicates that in some cases secondary processes enriched TOC relative to primary inputs by as much as 4%. Paleontological evidence in these same beds indicates development of extensive food-webs and supports attribution of this isotopic enrichment to heterotrophic reworking.

Alkanes↗
PubMed1994

Nitrogen isotopic analyses by isotope-ratio-monitoring gas chromatography/mass spectrometry.

Amino acids containing natural-abundance levels of 15N were derivatized and analyzed isotopically using a technique in which individual compounds are separated by gas chromatography, combusted on-line, and the product stream sent directly to an isotope-ratio mass spectrometer. For samples of N2 gas, standard deviations of ratio measurement were better than 0.1% (Units for delta are parts per thousand or per million (%).) for samples larger than 400 pmol and better than 0.5% for samples larger than 25 pmol (0.1% 15N is equivalent to 0.00004 atom % 15N). Results duplicated those of conventional, batchwise analyses to within 0.05%. For combustion of organic compounds yielding CO2/N2 ratios between 14 and 28, in particular for N-acetyl n-propyl derivatives of amino acids, delta values were within 0.25% of results obtained using conventional techniques and standard deviations were better than 0.35%. Pooled data for measurements of all amino acids produced an accuracy and precision of 0.04 and 0.23%, respectively, when 2 nmol of each amino acid was injected on column and 20% of the stream of combustion products was delivered to the mass spectrometer.

Amino Acids↗
PubMed1993

A 6,000-year sedimentary molecular record of chemocline excursions in the Black Sea.

The Black Sea is the world's largest anoxic basin; it is also a contemporary analogue of the environment in which carbonaceous shales and petroleum source beds formed. Recently, Repeta et al. reported that anoxygenic photosynthesis may be an important component of carbon cycling in the present Black Sea, owing to a shoaling of the chemocline and consequent penetration of the photic zone by anaerobic waters in the past few decades. It has been suggested that this was due to an anthropogenic decrease in freshwater input to the Black Sea, although natural causes were not ruled out. Here we report the distributions of sequestered photosynthetic pigments in eight core samples of sediments from the Black Sea ranging in age from zero to 6,200 years before the present. Our results show that photosynthetic green sulphur bacteria (Chlorobiaceae [correction of Clorobiaceae]) have been active in the Black Sea for substantial periods of time in the past. This finding indicates that the penetration of the photic zone by anaerobic waters is not a recent phenomenon, and suggests that natural causes for shoaling of the chemocline are more likely than anthropogenic ones.

Bacteria↗