Search PubMed⌕ Search

Biomedical subjects

J M Hayes

Publications and source records attributed to J M Hayes.

At least 109 records · Page 6Linked to original sources
PubMed1989

An isotopic study of biogeochemical relationships between carbonates and organic carbon in the Greenhorn Formation.

Carbon-isotopic compositions of total carbonate, inoceramid carbonate, micritic carbonate, secondary cements, total organic carbon, and geoporphyrins have been measured in 76 different beds within a 17-m interval of a core through the Greenhorn Formation, an interbedded limestone and calcareous shale unit of Cretaceous age (Cenomanian-Turonian) from the Western Interior Seaway of North America. Results are considered in terms of variations in the processes of primary production (which led to the biosynthesis of the molecular precursors of the geoporphyrins) and in secondary processes (those mediating the transformation of primary organic material into sedimentary total organic carbon). It is shown that the porphyrin isotopic record reflects primary isotopic variations more closely than the TOC isotopic record, and that, in these sediments, TOC is enriched in 13C relative to its primary precursor by 0.6 to 2.8%. This enrichment is attributed to isotope effects within the consumer foodweb and is associated with respiratory heterotrophy. Variations in this secondary enrichment are correlated with variations in the isotopic composition of marine carbonate. This correlation is attributed to effects of environmental changes on the marine foodweb. These may have included increased atmospheric oxygen associated with the Cenomanian-Turonian oceanic anoxic event. The isotopic fractionation associated with fixation of carbon by primary producers is observed to have varied by 1.5% during the interval of deposition. It is suggested that this change is due to a variation in the makeup of the community of primary producers and/or to a decrease in the atmospheric abundance of CO2 during the oceanic anoxic event.

Animals↗
PubMed1989

Origins of etioporphyrins in sediments: evidence from stable carbon isotopes.

In samples of the Julia Creek and Condor oil shales (Australia, Albian, and early Tertiary, respectively) etioporphyrin III is significantly depleted in 13C (4%) relative to porphyrins derived from chlorophylls. This isotopic difference suggests a large contribution from some independent source. The haem group found in cytochromes derived from microbial sources is the most likely candidate.

Australia↗
PubMed1989

Carbon isotope effects associated with autotrophic acetogenesis.

The carbon kinetic isotope effects associated with synthesis of acetate from CO2 and H2 during autotrophic growth of Acetobacterium woodii at 30 degrees C have been measured by isotopic analyses of CO2, methyl-carbon, and total acetate. Closed systems allowing construction of complete mass balances at varying stages of growth were utilized, and the effects of the partitioning of carbon between CO2 and HCO3- were taken account. For the overall reaction, total carbonate --> total acetate, isotope effects measured in replicate experiments ranged from -59.0 +/- 0.9% to -57.2 +/- 2.3%. Taking into account all measurements, the weighted mean and standard deviation are -58.6 +/- 0.7%. There is no evidence for intramolecular ordering in the acetate. The carbon isotopic composition of sedimentary acetate, otherwise expected to be near that of sedimentary organic carbon, is likely to be depleted in environments in which autotrophic acetogenesis is occurring.

Acetates↗
PubMed1989

Arthroscopic treatment of steroid-induced osteonecrosis of the humeral head.

Shoulder arthroscopy was performed on a 52-year-old man for the treatment of steroid-induced osteonecrosis of the humeral head. The removal of loose bodies and joint debridement has successfully improved the patient's functional status through relief of pain, improved range of motion, and elimination of locking. This case suggests another use of arthroscopy in the treatment of shoulder pathology.

Crohn Disease↗
PubMed1989

Renal transplant calculi. A reevaluation of risks and management.

Between January 1977 and March 1988, 10 of 892 renal transplant recipients formed urinary tract calculi posttransplantation. The presenting symptoms were predominantly those of azotemia due to obstruction and/or hematuria. Factors predisposing to stone formation included a reconstructive urologic procedure at the time of transplantation (n = 4) or a surgical complication (n = 4), necessitating the placement of a ureteral stent and/or nephrostomy tube, secondary hyperparathyroidism (n = 5), hyperuricosuria (n = 4), and hypercalciuria (n = 1). Four patients passed their stones spontaneously; 1 patient underwent ureterolithotomy, 3 patients underwent endourologic stone extraction, 1 patient was treated with a combination of surgical and endourologic procedures, and 1 patient underwent extracorporeal shock wave lithotripsy as monotherapy. While the management of these patients can be challenging, awareness of predisposing factors, proper application of all currently available urologic techniques, and attention to certain guidelines of management can aid in minimizing morbidity from this rare urologic complication of renal transplantation.

Adolescent↗
PubMed1989

Carbon isotope fractionation by thermophilic phototrophic sulfur bacteria: evidence for autotrophic growth in natural populations.

Purple phototrophic bacteria of the genus Chromatium can grow as either photoautotrophs or photoheterotrophs. To determine the growth mode of the thermophilic Chromatium species, Chromatium tepidum, under in situ conditions, we have examined the carbon isotope fractionation patterns in laboratory cultures of this organism and in mats of C. tepidum which develop in sulfide thermal springs in Yellowstone National Park. Isotopic analysis (13C/12C) of total carbon, carotenoid pigments, and bacteriochlorophyll from photoautotrophically grown cultures of C. tepidum yielded 13C fractionation factors near -20%. Cells of C. tepidum grown on excess acetate, wherein synthesis of the Calvin cycle enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase ribulose bisphosphate carboxylase) was greatly repressed, were isotopically heavier, fractionation factors of ca. -7% being observed. Fractionation factors determined by isotopic analyses of cells and pigment fractions of natural populations of C. tepidum growing in three different sulfide thermal springs in Yellowstone National Park were approximately -20%, indicating that this purple sulfur bacterium grows as a photoautotroph in nature.

Bacteria↗
PubMed1989

Geochemical and isotopic evidence for paleoredox conditions during deposition of the Devonian-Mississippian New Albany Shale, southern Indiana.

The upper part of the New Albany Shale is divided into three members. In ascending order, these are (1) the Morgan Trail Member, a laminated brownish-black shale; (2) the Camp Run Member, an interbedded brownish-black and greenish-gray shale; and (3) the Clegg Creek Member, also a laminated brownish-black shale. The Morgan Trail and Camp Run Members contain 5% to 6% total organic carbon (TOC) and 2% sulfide sulfur. Isotopic composition of sulfide in these members ranges from -5.0% to -20.0%. C/S plots indicate linear relationships between abundances of these elements, with a zero intercept characteristic of sediments deposited in a non-euxinic marine environment. Formation of diagenetic pyrite was carbon limited in these members. The Clegg Creek Member contains 10% to 15% TOC and 2% to 6% sulfide sulfur. Isotopic compositions of sulfide range from -5.0% to -40%. The most negative values occur in the uppermost Clegg Creek Member and are characteristic of syngenetic pyrite, formed within an anoxic water column. Abundances of carbon and sulfur are greater and uncorrelated in this member, consistent with deposition in as euxinic environment. In addition, DOP (degree of pyritization) values suggest that formation of pyrite was generally iron limited throughout Clegg Creek deposition, but sulfur isotopes indicate that syngenetic (water-column) pyrite becomes an important component in the sediment only in the upper part of the member. At the top of the Clegg Creek Member, a zone of phosphate nodules and trace-metal enrichment coincides with maximal TOC values. During euxinic deposition, phosphate and trace metals accumulated below the chemocline because of limited vertical circulation in the water column. Increased productivity would have resulted in an increased flux of particulate organic matter to the sediment, providing an effective sink for trace metals in the water column. Phosphate and trace metals released from organic matter during early diagenesis resulted in precipitation of metal-rich phosphate nodules.

Carbon↗
PubMed1989

Mixed-mode therapy: kinetic analysis and acute clinical evaluation.

A mixed therapeutic modality was devised in which patients with chronic renal failure were treated with a combination of continuous ambulatory peritoneal dialysis (CAPD; two daily 4-hour exchanges per day; 16 h dry belly) and hemodialysis (1 session per week). Kinetic modeling analysis indicated that a time-averaged urea concentration equivalent to CAPD could be obtained with a Kt/V value of 1.2-1.6, depending on patient parameters, for the single-weekly hemodialysis. The therapy format was acutely evaluated in a 2-week clinical trial on 4 patients. Excursions in small-solute concentration were virtually equivalent to those predicted from theory. Adequate fluid removal was obtained in the 2 CAPD exchanges and blood pressure was well controlled. As a result of the success of the acute trials, and since this format may offer potential lifestyle advantages to patients who possess dual access, a chronic trial of mixed-mode therapy seems advised.

Aged↗
PubMed1989

The post-Paleozoic chronology and mechanism of 13C depletion in primary marine organic matter.

Carbon-isotopic compositions of geoporphyrins have been measured from marine sediments of Mesozoic and Cenozoic age in order to elucidate the timing and extent of depletion of 13C in marine primary producers. These results indicate that the difference in isotopic composition of coeval marine carbonates and marine primary photosynthate was approximately 5 to 7 permil greater during the Mesozoic and early Cenozoic than at present. In contrast to the isotopic record of marine primary producers, isotopic compositions of terrestrial organic materials have remained approximately constant for this same interval of time. This difference in the isotopic records of marine and terrestrial organic matter is considered in terms of the mechanisms controlling the isotopic fractionation associated with photosynthetic fixation of carbon. We show that the decreased isotopic fractionation between marine carbonates and organic matter from the Early to mid-Cenozoic may record variations in the abundance of atmospheric CO2.

Atmosphere↗
PubMed1988

Detection of CCl4-induced oxidation of hepatic tissue in vivo by oxygen-18 tracing.

Oxidation of rat hepatic tissue was measured as incorporation of oxygen-18 (18O) from 18O2 following exposure to carbon tetrachloride (CCl4). Anesthetized rats were injected with CCl4 and allowed to breathe 18O2 for 1 hr, and then livers were homogenized, fractionated, and dried. The dried fractions were pyrolyzed to CO by an oxygen elemental analyzer, the CO was oxidized to CO2, and isotope ratio mass spectrometry was used to determine the abundance of 18O in the CO2. Rats that breathed 18O2 (21% in N2) for 1 hr had significant incorporation of 18O into lipids, solutes, and macromolecules of the liver. Injection with CCl4 increased incorporation of 18O into all liver fractions, although this increase was significant only in the lipid fraction. Rats pretreated with phenobarbital and then given CCl4 had significantly increased 18O in all liver fractions although it was greatest in the lipid fraction. About 5 mumol of 18O per gram of dry liver was incorporated in phenobarbital/CCl4-treated rats, of which 60% was in the water-soluble fraction, 17% in the lipids, and 16% in the macromolecules. Piperonyl butoxide administration abolished the CCl4-induced 18O incorporation. Thus, 18O incorporation appeared to provide a measure of oxidation in all tissue fractions following in vivo CCl4-induced liver injury.

Animals↗
PubMed1988

Sulfur isotope effects associated with oxidation of sulfide by O2 in aqueous solution.

Normal sulfur isotope effects averaging epsilon = -5.2 +/- 1.4% (s.d.) were consistently observed for the oxidation of sulfide in aqueous solution. Reaction products were sulfate, thiosulfate and sulfite at pH 10.8-11 in distilled water; S0 was formed in two experiments with synthetic seawater at pH 8-9.5. Because the -5.2% normal isotope effect differs significantly from the previously measured +2% inverse effect associated with anaerobic oxidation of sulfide by photosynthetic bacteria, stable sulfur isotopic measurements are potentially useful for distinguishing aerobic vs. anaerobic sulfide oxidation in marine and freshwater sulfureta.

Bacteria, Anaerobic↗
PubMed1988

Experience with percutaneous transluminal angioplasty for renal artery stenosis at the Cleveland Clinic.

From April 1979 to June 1985 percutaneous transluminal angioplasty was attempted in 68 patients at our clinic to treat renovascular hypertension and/or to preserve renal function. The etiology of renal artery disease was atherosclerosis in 55 patients, fibrous dysplasia in 6, renal transplant arterial stenosis in 5 and postoperative saphenous vein graft stenosis in 2. A successful clinical outcome, defined as a decrease in blood pressure and/or improvement in renal function, was achieved in 12 patients (26.1 per cent) with atherosclerotic renal artery disease, 3 (75 per cent) with fibrous dysplasia, 2 (100 per cent) with saphenous vein graft stenosis and all 5 with transplant renal arterial stenosis (100 per cent). Improved results were observed in patients with nonostial atherosclerotic lesions compared to ostial lesions. There were 23 complications (33.8 per cent) after percutaneous transluminal angioplasty and all but 1 occurred with atherosclerosis. Of these complications 13 (19 per cent) were considered major. Since the beginning of 1983, however, only 3 complications occurred among 32 procedures (9.4 per cent) and only 1 of these was of major significance. When technically feasible, percutaneous transluminal angioplasty can provide effective treatment for selected patients with renal artery stenosis.

Angioplasty, Balloon↗
PubMed1988

The use of single pediatric cadaver kidneys for transplantation.

We have reviewed our experience with 126 single pediatric cadaver kidneys (donor ages 9 months to 16 years) transplanted over a 10-year period. There were 17 donors aged 0-2 years, 55 donors aged 0-6 years, 34 donors aged 7-12 years, and 37 donors aged 13-16 years. One-year patient and graft survival was 88.2%/76.5%, 91%/74%,88.3%/69.1%, and 94.4%/80.6% for the respective groups. One-year patient and graft survival for an adult donor control group was 93%/69%. The percentage of recipients requiring dialysis in the early posttransplant period was 70.6%, 54.5%, 52.9%, 51.4%, and 52.4% for all groups, respectively. The time to reach a nadir creatinine was similar in all groups (24-30 days). While the functional outcome was comparable to cadaver transplantation utilizing adult donor kidneys, a higher incidence of infections and technical complications were encountered in the young-donor-age groups. Overall, there were 12 ureteral complications (8 fistulas, 4 stenoses), 3 bladder fistulas, and 4 renal artery stenoses. The urologic complication rate in kidneys from donors 0-2 years of age was 23.5% (all ureteral fistulas) versus 5% in the kidneys from adult donors. Only one graft was lost due to a technical complication. We conclude that, while cadaver kidneys from donors in the young age groups may be utilized successfully for transplantation, a higher incidence of urologic complications may be associated with their use. Careful harvesting and intraoperative techniques may minimize complications when utilizing kidneys from these donors.

Adolescent↗
PubMed1988

34S/32S fractionation in sulfur cycles catalyzed by anaerobic bacteria.

Stable isotopic distributions in the sulfur cycle were studied with pure and mixed cultures of the anaerobic bacteria, Chlorobium vibrioforme and Desulfovibrio vulgaris. D. vulgaris and C. vibrioforme can catalyze three reactions constituting a complete anaerobic sulfur cycle: reduction of sulfate to sulfide (D. vulgaris), oxidation of sulfide to elemental sulfur (C. vibrioforme), and oxidation of sulfur to sulfate (C. vibrioforme). In all experiments, the first and last reactions favored concentration of the light 32S isotope in products (isotopic fractionation factor epsilon = -7.2 and -1.7%, respectively), whereas oxidation of sulfide favored concentration of the heavy 34S isotope in products (epsilon = +1.7%). Experimental results and model calculations suggest that elemental sulfur enriched in 34S versus sulfide may be a biogeochemical marker for the presence of sulfide-oxidizing bacteria in modern and ancient environments.

Desulfovibrio vulgaris↗