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Biomedical subjects

J M Hayes

Publications and source records attributed to J M Hayes.

At least 73 records · Page 4Linked to original sources
PubMed1993

Elevated dark-adapted thresholds in hypopigmented mice measured with a water maze screening apparatus.

In previous electrophysiological experiments from hypopigmented animals (mice, rats, rabbits), single-unit recordings from both retinal ganglion axons and cells in the superior colliculus have demonstrated an increase in threshold in the dark-adapted state which is roughly proportional to the ocular melanin concentration. In the present study we compared an albino mouse strain which is relatively resistant to light damage and the beige mouse mutant to their wild-type controls in a situation that involved unanesthetized, unrestrained mice as a control to the electrophysiological single unit experiments. We used a six-chambered water maze. Animals were trained to swim to an illuminated ramp until their performances leveled off (about 10 days). The animals were then dark-adapted for 24 h and tested after reducing the luminance level of the water maze. We found that the albino mice failed to find the ramp when the luminance fell to 1.58 x 10(-3) cd/m2 (p < or = .0001), the beige mice failed at 2.00 x 10(-4) cd/m2 (p < or = .0001), and the normally pigmented controls performed to 5.00 x 10(-5) cd/m2 (p < or = .0001). These results support our previous findings that the sensitivity defect in hypopigmented animals is proportional to the degree of ocular hypopigmentation.

Animals↗
PubMed1993

Carbon and nitrogen isotopic compositions of alkyl porphyrins from the Triassic Serpiano oil shale.

The carbon and nitrogen isotopic compositions of seven of the most abundant alkylporphyrins from the Serpiano oil shale (marine, Triassic) were determined. For the C31 and C32 butanoporphyrins, values of delta 13CPDB and delta 15NAIR averaged -24.0% and -3.1%. In contrast, the C31 and C32 methylpropanoporphyrins, DPEP, and a C30 13-nor etioporphyrin had delta 13C and delta 15N values averaging -27.5 and -3.3%, respectively. Carbon and nitrogen isotopic values for kerogen averaged -30.8 and -0.9, whereas those for total extract averaged -31.6, and -4.0%. The butanoporphyrins apparently derive from a biological source different from that giving rise to the other porphyrins, their 13C enrichment not being related to carbon isotopic fractionation accompanying diagenetic reactions. The delta 15N values for all the porphyrins indicate that the depletion of 15N observed in the kerogen is of primary origin. Consistent with the very high abundance of hopanoids and methyl hopanoids in the aliphatic hydrocarbon fraction, it is suggested that cyanobacterial fixation of N2 may have been the main cause of 15N depletion.

Biological Evolution↗
PubMed1993

A photoautotrophic source for lycopane in marine water columns.

Suspended particulate matter and recent sediments from diverse oceanic sites have been investigated for their contents of lycopane. Lycopane was present in all samples, including both oxic and anoxic water column and sediments. The highest concentrations in the water column were found in surface waters of the central Pacific gyre (1.5 ng/L) and in the anoxic waters of the Cariaco Trench (1.1 ng/L) and the Black Sea (0.3 ng/L). Vertical concentration profiles suggest that lycopane is probably algal in origin. Moreover, biogeochemical conditions in anoxic zones apparently result in a secondary production of lycopane from an as yet unidentified precursor. Compound-specific carbon isotopic analyses have been carried out on lycopane from water column and sediment samples. Isotopic compositions of lycopane range between -23.6% and -32.9% and are consistent with a photoautotrophic origin. We postulate that some lycopane is produced in surface waters of the ocean, while additional lycopane is produced in anoxic zones by anaerobic microbial action on an algal precursor.

Anaerobiosis↗
PubMed1993

Molecular and bulk isotopic analyses of organic matter in marls of the Mulhouse Basin (Tertiary, Alsace, France).

Contents of 13C in kerogens and carbonates in 21 samples from a core of the MAX borehole, Mulhouse Evaporite Basin, range from -27.3 to -23.5 and -3.7 to -1.8% vs PDB, respectively. Organic nitrogen in the same samples is enriched in 15N relative to atmospheric N2 by 12.2-15.7%. Hydrogen indices and delta values for kerogens vary systematically with facies, averaging 493 mg HC/g Corg and -25.7% in the most saline facies (dominated by inputs from aquatic sources) and 267 mg HC/g Corg and -23.7% in the least saline facies (50/50 aquatic/terrigenous). Values of delta were measured for individual aliphatic hydrocarbons from three samples representing three different organic facies. For all samples, terrigenous inputs were unusually rich in 13C, the estimated delta value for bulk terrigenous debris, apparently derived partly from CAM plants, being -22.5%. In the most saline facies, isotopic evidence indicates the mixing of 13C-depleted products of photosynthetic bacteria with 13C-enriched products of halotolerant eukaryotic algae. At lower salinities, a change in the producer community is marked by a decrease in the 13C content of algal lipids. The content of 13C in algal lipids increases in the least saline facies, due either to succession of different organisms or to decreased concentrations of dissolved CO2.

Alkanes↗
PubMed1993

The transplantation of difficult donor kidneys and recipients: helpful surgical techniques.

Due to the current shortage of organ donors a coalescence of surgical techniques has been applied in an attempt to use all compatible organs that may have been discarded due to anatomical variations, disease or damage, and to transplant them into higher surgical risk recipients. Selected cases have been chosen that illustrate some of these techniques, and the various types of recipients and donor kidneys. Cases 1 and 2 illustrate applications of the orthotopic technique of renal transplantation, as well as reconstructive measures that may be necessary for success. Renal transplantation in perhaps one of the more commonly encountered difficult recipients, the patient with severe atherosclerotic vascular disease, is addressed by cases 1 and 3. The use of unusual donor organs, such as horseshoe kidneys and pediatric donor en block kidneys, is particularly pertinent in the attempt to transplant all viable organs and is demonstrated in cases 4 and 5. These cases illustrate the application of various surgical techniques in which either a difficult recipient or a damaged and/or diseased donor kidney may have otherwise precluded renal transplantation.

Adult↗
PubMed1993

Soluble HLA class I in the serum of transplant recipients.

BACKGROUND: Soluble HLA, Class I (S-HLA-I) has been found in serum, plasma, body fluids, peritoneal dialysates, and urine. S-HLA-I may be a product of membrane shedding, proteolysis, and/or alternate gene splicing. Previous assays to quantitate S-HLA-I were cumbersome, required radioisotope labeling procedures, or the purification of Class I antigen preceding antigen quantitation. The authors developed a solid-phase, enzyme-linked immunoassay that can be used to quantitate S-HLA-I and to study its relevance in transplantation. METHODS: A solid-phase enzyme-linked immunoassay employing monoclonal anti-Class I to catch S-HLA-I present in plasma and peroxidase-labeled monoclonal anti-beta 2-microglobulin (B2M) to quantitate bound S-HLA-I was employed. Values were correlated with rejection and infection episodes. Pre and postoperative determinations were made from the sera of liver, heart, and kidney recipients. Size chromatography was used to compare the molecular weight of S-HLA-I from baseline and peak serum concentrations obtained during rejection episodes (2 liver, 1 heart, 1 kidney), and from 1 kidney recipient with a wound infection. RESULTS: All 9 liver recipients and 12 heart recipients demonstrated a fall in S-HLA-I, or very low initial values, for the first 10 days and then a progressive increase in values substantially above preoperative concentrations. Values from renal recipients were more variable. There were temporary increases in S-HLA-I preceding or during 16 of 20 (80%) biopsy-proven rejections (all reversible), and in 9 of 11 (83%) episodes of infection (bacterial, viral, and fungal). In heart and liver rejection, as well as the wound infection, the sera contained increased S-HLA-I, which was almost all of the same molecular weight (approximately 52,000 daltons). In serum from the one patient with renal rejection, two additional S-HLA-I peaks occurred, one with a molecular weight near 1,000,000 daltons and the second at a molecular weight approximately 11,000 daltons suggesting cellular breakdown of the donor organ. CONCLUSION: In summary, different patterns of S-HLA-I concentrations occur after kidney transplantation. Most liver and heart recipients reached a steady state higher than preoperative levels. Transient increases in S-HLA-I occurred with rejection and infection. In one severe rejection episode, larger and smaller fractions of S-HLA-I were detected and may represent cell membrane breakdown.

Enzyme-Linked Immunosorbent Assay↗
PubMed1993

Late functional outcome in patients with tibia fractures covered with free muscle flaps.

The functional outcome and work capacity of patients treated with a free muscle flap to cover open grade III tibial fractures was assessed. The conditions of patients, eight with grade IIIB and six with grade IIIC isolated open tibia fractures, treated with a free muscle flap transfer less than 3 months after their injury, were retrospectively reviewed. Flap survival was 86%. Twelve of the 14 were contacted, with follow-up time averaging 7 years. Four of the 14 eventually had below-knee amputations and one of the 10 patients with a successful limb salvage died of unrelated causes. All nine surviving patients with salvaged limbs had healed fractures in an average of 15 months (range, 8-23). Six were initially infected, but drainage had stopped an average of 13.5 months after flap coverage. No wounds were draining at last follow-up observation. Those tibias that were initially infected have been drainage free for an average of 78 months. The average total hospital cost of reconstruction was $48,996.40. The functional outcome in 12 patients was assessed. Eight of the nine patients whose limbs were salvaged returned to work, six to jobs with demands similar to their preinjury occupation. Three of the four patients with limb amputations were also able to return to jobs similar to their preinjury occupation. Patients must be made aware of the expected course of reconstruction and anticipated final outcome. Despite rarely achieving normal function, returning to work is a reasonable goal.

Adult↗
PubMed1992

Carbon isotope evidence for the stepwise oxidation of the Proterozoic environment

The oxidation of the Earth's crust and the increase in atmospheric oxygen early in Earth history have been linked to the accumulation of reduced carbon in sedimentary rocks. Trends in the carbon isotope composition of sedimentary organic carbon and carbonate show that during the Proterozoic aeon (2.5-0.54 Gyr ago) the organic carbon reservoir grew in size, relative to the carbonate reservoir. This increase, and the concomitant release of oxidizing power in the environment, occurred mostly during episodes of global rifting and orogeny.

Atmosphere↗
PubMed1992

Recognition of paleobiochemicals by a combined molecular sulfur and isotope geochemical approach.

Study of organic matter in immature sediments from a Messinian evaporitic basin shows that consideration of structures, modes of occurrence, and carbon isotopic compositions of free and sulfur-bound carbon skeletons allow identification of biochemical precursors. Detailed information concerning biotic communities present during deposition of sediments can be retrieved in this way. Moreover, unprecedented biochemicals were recognized; these extend the horizon of biomarker geochemistry.

Animals↗
PubMed1992

The combined application of organic sulphur and isotope geochemistry to assess multiple sources of palaeobiochemicals with identical carbon skeletons.

Five immature sediments from a Messinian evaporitic basin, representing one evaporitic cycle, were studied using molecular organic sulphur and isotope geochemistry. It is shown that a specific carbon skeleton which is present in different "modes of occurrence" ("free" hydrocarbon, alkylthiophene, alkylthiolane, alkyldithiane, alkylthiane, and sulphur-bound in macromolecules) may have different biosynthetic precursors which are possibly derived from different biota. It is demonstrated that the mode of occurrence and the carbon isotopic composition of a sedimentary lipid can be used to "reconstruct" its biochemical precursor. This novel approach of recognition of the suite of palaeobiochemicals present during the time of deposition allows for identification of the biological sources with an unprecedented specificity.

Carbon↗
PubMed1992

An isotopic biogeochemical study of the Green River oil shale.

Thirty-five different samples from three different sulfur cycles were examined in this stratigraphically oriented study of the Shell 22x-l well (U.S.G.S. C177 core) in the Piceance Basin, Colorado. Carbon isotopic compositions of constituents of Green River bitumens indicate mixing of three main components: products of primary photoautotrophs and their immediate consumers (delta approximately -30% vs PDB), products of methanotrophic bacteria (delta approximately -85%), and products of unknown bacteria (delta approximately -40%). For individual compounds synthesized by primary producers, delta-values ranged from -28 to -32%. 13C contents of individual primary products (beta-carotane, steranes, acyclic isoprenoids, tricyclic triterpenoids) were not closely correlated, suggesting diverse origins for these materials. 13C contents of numerous hopanoids were inversely related to sulfur abundance, indicating that they derived both from methanotrophs and from other bacteria, with abundances of methanotrophs depressed when sulfur was plentiful in the paleoenvironment. gamma-Cerane coeluted with 3 beta(CH3),17 alpha(H),21 beta(H)-hopane, but delta-values could be determined after deconvolution. gamma-Cerane (delta approximately -25%) probably derives from a eukaryotic heterotroph grazing on primary materials, the latter compound (delta approximately -90%) must derive from methanotrophic organisms. 13C contents of n-alkanes in bitumen differed markedly from those of paraffins generated pyrolytically. Isotopic and quantitative relationships suggest that alkanes released by pyrolysis derived from a resistant biopolymer of eukaryotic origin and that this was a dominant constituent of total organic carbon.

Alkanes↗
PubMed1992

A novel directly coupled gradostat.

The original bidirectional compound chemostat (gradostat) described by Lovitt and Wimpenny has been simplified by making a more compact apparatus in which chemical gradients are established by diffusion between adjacent culture chambers. The experimental model (diffusion coupled (DC) gradostat) consisted of five chambers whose contents could be agitated by turbines rotating in the horizontal plane on a common shaft. Two biological experiments were designed to reveal the value of the DC gradostat. A methylotroph (Methylophilus methylotrophus) grown in a methanol gradient showed expected changes in cell viability as a function of position in the five vessel array. Cells of two species of photosynthetic bacteria (Rhodobacter capsulata and Rhodopseudomonas marina/agilis) with different salt sensitivities could be mixed and subsequently separated by the DC gradostat operating with a NaCl gradient of 0-3% w/v.

Bacteria↗
PubMed1992

Clean intermittent catheterization and urinary diversion in the management of renal transplant recipients with lower urinary tract dysfunction.

Renal transplant recipients with lower urinary tract dysfunction may be managed by urinary diversion or clean intermittent catheterization. To evaluate the comparative problems associated with each mode of therapy we studied 13 patients managed by clean intermittent catheterization (group 1, 6 patients) or urinary diversion (group 2, 7 patients). All 6 and 2 of 7 recipients in groups 1 and 2, respectively, had a neuropathic bladder. Mean followup was 3.7 +/- 1.5 (group 1) and 5.7 +/- 4.9 (group 2) years. Three allografts were lost in group 2 due to rejection (2) and death (1). Two patients each in groups 1 and 2 had febrile urinary tract infections requiring hospitalization and intravenous antibiotics. Complications related to urinary diversion developed in 4 patients in group 2. The serum creatinine at 1 and 3 years, number of hospital days per patient, total number of rejection episodes and number of patients employed in a full-time job following transplantation were similar in both groups. In summary, clean intermittent catheterization appears to have more morbidity in immunosuppressed transplant versus nontransplant patients but it may be preferable in renal transplant recipients due to the overall simplicity, positive psychological effect and comparable morbidity to other forms of management.

Adult↗
PubMed1992

Fractionation of carbon isotopes by phytoplankton and estimates of ancient CO2 levels.

Reports of the 13C content of marine particulate organic carbon are compiled and on the basis of GEOSECS data and temperatures, concentrations, and isotopic compositions of dissolved CO2 in the waters in which the related phytoplankton grew are estimated. In this way, the fractionation of carbon isotopes during photosynthetic fixation of CO2 is found to be significantly correlated with concentrations of dissolved CO2. Because ancient carbon isotopic fractionations have been determined from analyses of sedimentary porphyrins [Popp et al., 1989], the relationship between isotopic fractionation and concentrations of dissolved CO2 developed here can be employed to estimate concentrations of CO2 dissolved in ancient oceans and, in turn, partial pressures of CO2 in ancient atmospheres. The calculations take into account the temperature dependence of chemical and isotopic equilibria in the dissolved-inorganic-carbon system and of air-sea equilibria. Paleoenvironmental temperatures for each sample are estimated from reconstructions of paleogeography, latitudinal temperature gradients, and secular changes in low-latitude sea surface temperature. It is estimated that atmospheric partial pressures of CO2 were over 1000 micro atm 160 - 100 Ma ago, then declined to values near 300 micro atm during the next 100 Ma. Analysis of a high-resolution record of carbon isotopic fractionation at the Cenomanian-Turonian boundary suggests that the partial pressure of CO2 in the atmosphere was drawn down from values near 840 micro atm to values near 700 micro atm during the anoxic event.

Atmosphere↗
PubMed1992

Lipoprotein(a) levels in chronic renal disease states, dialysis and transplantation.

Lipoprotein(a) is an independent risk factor for cardiovascular disease. Lipoprotein(a) levels were measured in 196 patients (103 Male [M]: 93 Female [F]) with chronic renal diseases and in 116 controls. Median levels of Lipoprotein(a) [Lp(a)] were found to be significantly elevated in patients with untreated chronic renal disease (285,285 mg/L; M,F; range 30-1675 mg/L) and in those treated with continuous ambulatory peritoneal dialysis (320, 603; M,F; range 50-1450) compared with controls (70,51; M,F; range 1-750; p less than 0.01 Males, p less than 0.001 Females). Lp(a) levels in patients treated by haemodialysis (133,35; M,F; range 5-685) and renal transplantation (100,95; M,F; range 10-1700) were not significantly different from controls. Lipoprotein(a) levels correlated inversely with serum albumin in the combined dialysis group (r = -0.34, p less than 0.001), and with urinary protein loss in the combined transplant and chronic renal diseases groups (r = 0.29, p less than 0.01). This correlation of Lp(a) with protein metabolism suggests a similarity with changes in other apolipoprotein-B containing lipoproteins in nephrosis. These findings may be relevant to the increased risk of atherosclerosis in patients with chronic renal disease and to their optimum mode of renal replacement therapy.

Aged↗