Alteration of phenytoin binding by glycosylation of albumin in IDDM.

We measured glycosylated albumin and hemoglobin and serum protein binding of phenytoin in 57 children and adolescents with insulin-dependent diabetes mellitus (IDDM). Serum was incubated with phenytoin to yield concentrations of 15 and 25 mg/L, and a serum ultrafiltrate was prepared from an aliquot of each sample. We observed a linear correlation between glycosylated albumin and the free fraction of phenytoin at serum phenytoin concentrations of 15 mg/L (r = .35, P = .03) and 25 mg/L (r = .40, P = .003). A better correlation existed between the free fraction of phenytoin and total albumin concentrations for both serum concentrations (r = .45, P = .005 for 15 mg/L; r = .56, P = 10-5) for 25 mg/L), whereas the best linear correlation resided between the free fraction of phenytoin and the concentration of nonglycosylated albumin (r = .54, P = .0005 for 15 mg/L; r = .63, P less than 10(-6) for 25 mg/L). There was no correlation between the free fraction of phenytoin and the concentration of glycosylated albumin. Incubation of solutions of glycosylated and nonglycosylated albumin demonstrated significantly lower binding to the glycosylated fraction (P = 8.1 X 10(-6)). These results indicate that glycosylation of albumin diminishes the affinity of the phenytoin binding site on albumin. This alteration may have clinical significance in that it may alter the disposition of phenytoin in patients with IDDM and produce free phenytoin serum concentrations that are not accurately reflected by total serum phenytoin concentrations.

OCEANOGRAPHY. Contrasting futures for ocean and society from different anthropogenic CO2 emissions scenarios.

The ocean moderates anthropogenic climate change at the cost of profound alterations of its physics, chemistry, ecology, and services. Here, we evaluate and compare the risks of impacts on marine and coastal ecosystems­and the goods and services they provide­for growing cumulative carbon emissions under two contrasting emissions scenarios. The current emissions trajectory would rapidly and significantly alter many ecosystems and the associated services on which humans heavily depend. A reduced emissions scenario­consistent with the Copenhagen Accord's goal of a global temperature increase of less than 2°C­is much more favorable to the ocean but still substantially alters important marine ecosystems and associated goods and services. The management options to address ocean impacts narrow as the ocean warms and acidifies. Consequently, any new climate regime that fails to minimize ocean impacts would be incomplete and inadequate.

Measuring Bacterial Production in Deep-Sea Sediments using 3H-Thymidine Incorporation: Ecological Significance.

Bacteria play a major role in the decomposition of organic matter arriving at the deep-sea floor, and hence there is a need to determine accurate rates of bacterial production associated with sediment particles. However, sediment-based procedures are not well defined and sampling deep-sea sediments is technically difficult, time consuming, and expensive, often only producing relatively small amounts of undisturbed sediment for analysis. We describe and test a small-scale method (requiring 0.25 ml sediment) for the examination of bacterial production in deep-sea calcium carbonate rich sediments. Time course experiments showed variation in the period of linear [3H]thymidine uptake between 1 and 3 hr depending on station depth. The average concentration of natural thymidine in deep-sea sediments was 0.61 nmol per 0.5 ml slurry sample. Isotope dilution was significant, ranging between 26 and 51%. There was substantial small-scale (0.2-1.0 m) variation in deep-sea benthic bacterial [3H]thymidine incorporation rates (39%). Deep-sea surficial sediment bacterial production (assuming zero isotope dilution due to its potential high variability) in surficial sediments of the deep NE Atlantic varied between 0.014 and 0.48 mg C g-1 d-1 (mean = 0.23 mg C g-1 d-1) over 3 locations of depths between 1,092 and 3,572 m and at 3 times. Bacterial biomass varied between 1.1 and 12 mg C g-1 (mean = 6.1 mg C g-1). Bacterial growth rate estimates in these deep-sea sediments varied between 0.003 and 0.13 d-1 (mean = 0.050 d-1) giving doubling times of 5.3-216 d (mean = 44.5 d); which are similar to those of bacteria inhabiting waters in the upper mixed layer (2-<40 m) of the water column (2.6-57.8 d). comparison with shallow and coastal sea sediments (0.13-116 d) indicates that deep-sea sediment bacteria in the NE Atlantic are able to grow at rates similar to those in shallow sediment systems given sufficient food. However, the range is broader for deep-sea sediment bacteria, which may indicate a more "feast" and "fast" life than their counterparts in shallower environments. waters >2,000 m cover 60% of the Earth's surface; thus bacterial production in deep-sea sediments must contribute an important fraction of oceanic and global bacterial production. It is therefore important to establish an accurate method of measuring bacterial production so that the full roles and controls of bacteria from this environment can be determined.

The effects of postoperative continuous passive motion on peripheral nerve repair and regeneration. An experimental investigation in rabbits.

The effects of continuous passive motion (CPM) on nerve regeneration following nerve repair were investigated. In 26 rabbits, the medial popliteal nerve was transected and microsurgically repaired. Half of the animals were treated with cast immobilization and the rest with 70 degrees arc CPM. Both treatments were discontinued on day 14. After sacrifice on day 100, no animal showed separation at the suture line. Mean nerve conduction velocity was slightly slower in the CPM than in the immobilization group. Mean fibre density was also slightly less in the CPM group but the difference was not significant. Mean fibre diameters, fibre diameter distributions, and soleus-muscle wet weights were similar in the two groups.

Do learning style and learning environment affect learning outcome?

This study compared learning outcomes of students with different learning styles, as identified by the Kolb Learning Style Inventory indicators, in a traditional in-class environment with those taking the same course via distance education. The above-average scores were evenly distributed, 47% of the in-class group and 43% of the distance group. For three of the four learning styles, there was no relationship to learning outcome or environment. The Diverger group did show a relationship with above-average scores in the distance group (83%). The findings support that the classroom or distance environment did not influence learning outcome. Learning style did not appear to affect learning outcome in either group, except that the Diverger learning style may have a positive relationship to learning in the distance environment.

Multidisciplinary team dynamics in the production of problem-based-learning cases in issues related to older adults.

Two important goals in allied health education are to prepare future allied health professionals to function as members of interdisciplinary teams and to increase their awareness of issues related to the growing older adult population. The responsibility for achieving these goals rests on the faculty and administrators of allied health education programs, who may not themselves be proficient in either of these domains. A multidisciplinary team of health educators and administrators was brought together to produce six problem-based learning (PBL) cases related to older adults. Members of the team represented a variety of disciplines in health care, diverse philosophies of educational development, a variety of roles in allied health education, and differing levels of knowledge of issues related to older adults--parameters similar to those found in the members of an interdisciplinary healthcare team. The methods by which this multidisciplinary group functioned and the dynamics in attaining the goals of the project are presented.

Controls of the microbial loop: Nutrient limitation and enzyme production, location and control.

A major controlling factor for bacterial growth is their ability to hydrolyze high molecular weight molecules too complex to be transported directly across the cell's membrane. The utility of such an extracellular enzyme hydrolysis system, location of the enzymes (free or attached), environmental controls of enzyme production, and implications of multiple hydrolysis-uptake systems are explored in relation to free-living oceanic bacteria and bacteria attached to rapidly sinking aggregates.

Pentobarbital quantitation using immunoassays in Reye's syndrome patient serum.

Analysis of serum pentobarbital concentrations in 28 specimens from Reye's syndrome patients was conducted with modifications of three nonspecific immunoassay procedures originally designed to detect barbiturates in serum or urine. An adaptation of the urine enzyme-multiplied immunoassay technique (EMIT) Dupont aca barbiturate screen to the quantitation of serum pentobarbital is described. Replicate analysis of control specimens containing pentobarbital across a wide spectrum of concentrations revealed a between-day precision of less than 6%. Regression analysis revealed excellent agreement with a high-performance liquid chromatography (HPLC) method: (HPLC) = 0.98 (aca) - 0.07 (r = 0.97). Multiple linear regression analysis with a serum EMIT barbiturate screen and a urine fluorescence polarization immunoassay screen modified to quantitate pentobarbital in serum revealed excellent agreement among all methods, demonstrating that immunoassays offer a reliable approach to pentobarbital quantitation.

Bacteria in the cold deep-sea benthic boundary layer and sediment-water interface of the NE Atlantic.

This is a short review of the current understanding of the role of microorganisms in the biogeochemistry in the deep-sea benthic boundary layer (BBL) and sediment-water interface (SWI) of the NE Atlantic, the gaps in our knowledge and some suggestions of future directions. The BBL is the layer of water, often tens of meters thick, adjacent to the sea bed and with homogenous properties of temperature and salinity, which sometimes contains resuspended detrital particles. The SWI is the bioreactive interface between the water column and the upper 1 cm of sediment and can include a large layer of detrital material composed of aggregates that have sedimented from the upper mixed layer of the ocean. This material is biologically transformed, over a wide range of time scales, eventually forming the sedimentary record. To understand the microbial ecology of deep-sea bacteria, we need to appreciate the food supply in the upper ocean, its packaging, passage and transformation during the delivery to the sea bed, the seasonality of variability of the supply and the environmental conditions under which the deep-sea bacteria grow. We also need to put into a microbial context recent geochemical findings of vast reservoirs of intrinsically labile organic material sorped onto sediments. These may well become desorped, and once again available to microorganisms, during resuspension events caused by deep ocean currents. As biotechnologists apply their tools in the deep oceans in search of unique bacteria, an increasing knowledge and understanding of the natural processes undertaken and environmental conditions experienced by deep-sea bacteria will facilitate this exploitation.

Diel changes in the specific growth rate and mean cell volume of natural bacterial communities in two different water masses in the Irish sea.

Diel changes in the specific growth rates of natural bacterial communities as a whole and of different groups within the communities were followed over 2 days during July 1982, in stratified waters in the vicinity of a shallow sea tidal mixing front in the Irish Sea. Waters well above (4 m) and below (60 m) the thermocline were enclosed in dialysis bags and incubated in situ. The results show that there were periods of altered growth rates of the whole bacterial community and synchronous cell division of morphological groups. An increase in mean cell volume within both 4 and 60 m communities preceded an increase in specific growth rates, with a resultant decrease in the mean cell volume. Above the thermocline the whole bacterial community, as well as the rod and coccoid forms, doubled in number once a day. The doubling time of the whole bacterial community at 60 m was 2 days and slower than that at 4 m. This was due to a slower doubling time (3 days) for the coccoid forms. Rod forms at the two depths had a similar doubling time (1 day). The time of day when maximum division rate occurred was also different in the two water masses. At 4 m more coccoid forms divided during the night, whereas at 60 m more divided during the day. Conversely, at 4 m more rod forms divided during the day, whereas at 60 m more divided at night.These data indicate that the bacterial community and members of the community may be adapted to exploit the diurnal rhythms of dissolved organic carbon (DOC) release by other organisms and that portions of the bacterial community may therefore be more active at certain times of the day. The diurnal growth of the bacterial community may thus vary between different water masses and largely reflects the differences in the chemical and biological characteristics of the two water masses investigated.

Rapid protein determinations on ultrafiltrates prepared for free phenytoin quantification.

Ultrafiltration techniques for the separation of bound and free ligand are dependent on minimal amounts of protein-bound drug leakage through the membrane devices. A dye-impregnated test strip protein assay (Chemstrip-9) provides a rapid, visual assessment of membrane protein leakage. The test strips are sensitive to 200 mg/L of albumin in ultrafiltrates and do not react with as much as 4 mg/L of phenytoin.

Alpha-tocopherol protects against a reduction in adenosylcobalamin in oxidatively stressed human cells.

Excretion of methylmalonic acid by vitamin E-deficient patients and decreased labeling of adenosylcobalamin (AdoCbl) from cyanocobalamin in vitamin E-deficient rats suggest an interaction of vitamins E and B-12. We studied this interaction in two human cell culture systems: foreskin fibroblasts and a hepatoma cell line (HepG2). We measured radiolabeling of AdoCbl and methylcobalamin from [57Co]hydroxycobalamin for 6 d in the presence and absence of linoleate (an oxidative stressor) and alpha-tocopherol. In both cell types, labeling of AdoCbl was lower in the presence of linoleate unless alpha-tocopherol was present. The decrease was accentuated by peroxidized linoleic acid; AdoCbl synthetic rate was inversely associated with thiobarbituric acid-reactive compound concentration. Subcellular partitioning of labeled cobalamin revealed less in mitochondria in the linoleate-stressed cells that were not treated with alpha-tocopherol. We conclude that lipoperoxidation reduces mitochondrial AdoCbl formation and that alpha-tocopherol exerts a protective effect in oxidatively stressed cells. We suggest that this subcellular deficiency in AdoCbl may be one mechanism by which vitamin E deficiency leads to neurologic injury. The mechanism seems primarily to involve an alteration in intracellular cobalamin distribution with perhaps a minor effect upon enzymes of AdoCbl synthesis.

Prefabrication of skin flaps using vein grafts: an experimental study in rabbits.

Prefabrication provides a new method for creating donor sites which are not limited by natural vascular territories. There are several methods for prefabrication, and these include implantation of greater omentum, blood vessels or muscle flaps. Based on the concept that an arterio-venous (A-V) shunt results in sufficient neovascularisation to support a free flap, we used a rabbit model to investigate the characteristics of these flaps. Prefabrication of an abdominal wall donor site was performed using the left epigastric vein in 20 male New Zealand white rabbits. An 8 x 10 cm skin flap was elevated 10 days after prefabrication, either as an island or a free flap. Survival of the skin flaps exceeded 93% and was independent of position of the vascular pedicle, direction of blood flow, or nature of the flap (island or free flap). Angiograms showed a very rich neovascularisation within the prefabricated flap.

Microanalytical high-performance liquid chromatography assay for cefpirome (HR 810) in serum.

We report a microanalytical high-performance liquid chromatography method for quantitation of cefpirome (HR 810) from serum. The drug was extracted from 0.05 ml of serum with 0.2 ml of isopropanol containing beta-hydroxypropyltheophylline, the internal standard. Separations were performed on a C18 column at ambient temperature with detection at 240 nm. The mobile phase consisted of acetate buffer (0.05 M sodium acetate) containing tetrabutylammonium hydroxide and methanol (pH 5.1; 70:30, vol/vol). The method was linear to 500 micrograms of cefpirome per ml and had a sensitivity of 0.6 micrograms/ml. Analytical recovery was greater than 86%, and the between-day coefficient of variation was less than 4.2%. The stability for 1 week at 4 to 8 degrees C and for 30 days at -20 degrees C was documented. Interference with commonly used antibiotics, analgesics, methylxanthines, and anticonvulsants was not found. The small sample volume and ease of preparation make this method suitable for use in pediatric pharmacokinetic investigations of cefpirome.