Biomedical subjects

J B Russell

Publications and source records attributed to J B Russell.

At least 19 recordsLinked to original sources

PubMed1992

The effect of pH on the heat production and membrane resistance of Streptococcus bovis.

Non-growing cultures of Streptococcus bovis JB1 which were incubated in 2-[N-moropholino] ethane-sulfonic acid (MES)-phosphate buffer (pH 6.8) and glucose (2 g/l) produced heat at a rate of 0.17 mW/mg protein, and this rate was proportional to the enthalpy change of the homolactic fermentation. Since the growth-independent heat production could be eliminated by dicyclohexylcarbodiimide (DCCD), an inhibitor of F1F0 ATPases, it appeared that virtually all of the energy was being used to counteract proton flux through the cell membrane. When the pH was decreased from 6.8 to 5.8, heat production and glucose consumption increased, the electrical potential (delta psi) declined, the chemical gradient of protons (Z delta pH) increased, and there was a small increase in total protonmotive force (delta p). Further decreases in pH (5.8 to 4.5) caused a marked decrease in heat production and glucose consumption even though there was only a small decline in membrane voltage. Based on the enthalpy of ATP (4 kcal or 16.8 kJ/mol), it appeared that 38% of the wattage was passing through the cell membrane. The relationship between membrane voltage and membrane wattage or glucose consumption was non-linear (non-ohmic), and it appeared that the resistance of the membrane to current flow was not constant. Based on the electrical formula, resistance = voltage2/wattage and resistance = voltage/amperage, there was a marked increase in membrane resistance when the pH was less than 6.0. The increase in membrane resistance at low pH allowed S. bovis to maintain its membrane potential and expend less energy when its ability to ferment glucose was impaired.

Cell Membrane↗

PubMed1992

Laser micromanipulation in the mouse embryo: a novel approach to zona drilling.

OBJECTIVE: To introduce the use of excimer lasers for penetration of the zona pellucida for micromanipulation purposes. DESIGN: Cryopreserved two-cell mouse embryos were thawed and exposed to the 248-nm line of a krypton fluoride excimer laser (Lambda Physik EMG 202, Goettingen, Germany) creating a 2 to 4-micron opening in the zona pellucida. SETTING: The Laser Ablation Laboratory at DuPont and the in Vitro Fertilization Laboratory at The Medical Center. INTERVENTIONS: The embryos were exposed in either phosphate-buffered solution (PBS) or modified human tubal fluid (HTF) with the laser power varying from 1 to 2 J/cm2 and cultured in Ham's F-10 medium (GIBCO, Grand Island, NY) with 0.4% bovine serum albumin. MAIN OUTCOME MEASURES: The outcome of each experiment was measured by blastocyst formation of laser-exposed embryos as compared with a set of unexposed control embryos handled in a similar fashion. RESULTS: Successful laser penetration of the zona pellucida was achieved using the 248-nm line of a krypton fluoride excimer laser. A higher blastocyst formation was found for embryos exposed in PBS. The higher optical absorption of the modified HTF partially inhibited embryo development. The blastocyst statistics increased 2.5-fold times by reducing the exposure of the embryos to ablation by-products. CONCLUSIONS: The use of a krypton fluoride excimer laser was introduced as a new method to open the zona pellucida of two-cell mouse embryos without interrupting blastocyst formation.

Animals↗

PubMed1992

Properties of a genetically reconstructed Prevotella ruminicola endoglucanase.

A pUC19-derived plasmid was constructed that coded for a hybrid cellulase with the Thermomonospora fusca E2 cellulose-binding domain at its C terminus joined to the Prevotella ruminicola 40.5-kDa carboxymethyl cellulase (CMCase). The hybrid enzyme was purified and characterized enzymatically. It bound tightly to cellulose, and its specific activities on carboxymethyl cellulose, amorphous cellulose, and ball-milled cellulose were 1.5, 10, and 8 times that of the 40.5-kDa CMCase, respectively. Furthermore, the modified enzyme gave synergism with an exocellulase in the degradation of filter paper, while the 40.5-kDa CMCase did not.

Actinomycetales↗

PubMed1992

Resistance of proline-containing peptides to ruminal degradation in vitro.

Mixed ruminal bacteria utilized an enzymatic digest of casein at a rate faster than that for an enzymatic digest of gelatin, but neither amino acid source was completely utilized even when the incubation period was as long as 96 h. Since the reaction of ninhydrin with the residual nonammonia, nonprotein nitrogen was more than twofold stronger when the samples were hydrolyzed with 6 N HCl, it appeared that much of the residual nitrogen was from peptides. Approximately 66% of the nonammonia, nonprotein, ninhydrin-reactive material could not be recovered as amino acids, but there was a significant decrease in total amino acid nitrogen when the samples were pretreated with a C18 Sep-Pak column to remove peptides. The resistant peptides had an abundance of proline, and subsequent incubations showed that synthetic dipeptides which contained proline were hydrolyzed slowly. Lysine appears to be the amino acid which is most apt to limit ruminant production. Dipeptides containing proline and lysine were hydrolyzed at least fivefold slower than lysine-alanine. Methionine, another potentially limiting amino acid, was also degraded at a slower (2.5-fold) rate when it was present as part of a proline dipeptide.

Animals↗

PubMed1992

Energetics of arginine and lysine transport by whole cells and membrane vesicles of strain SR, a monensin-sensitive ruminal bacterium.

Strain SR, a monensin-sensitive, ammonia-producing ruminal bacterium, grew rapidly on arginine and lysine, but only if sodium was present. Arginine transport could be driven by either an electrical potential or a chemical gradient of sodium. Arginine was converted to ornithine, and it appeared that ornithine efflux created a sodium gradient which in turn drove arginine transport. There was a linear decline in arginine transport as pH was decreased from 7.5 to 5.5, and the cells did not grow at a pH less than 6.0. The Eadie-Hofstee plot was biphasic, and arginine could also be taken by a high-capacity diffusion mechanism. Because arginine was a strong inhibitor of lysine transport and lysine was a weak inhibitor of arginine transport, it appeared that both lysine and arginine were taken up by an arginine-lysine carrier which had a preference for arginine. The rate of lysine fermentation was always proportional to the extracellular lysine concentration, and facilitated diffusion was the dominant mechanism of lysine transport. When SR was grown in continuous culture on arginine or lysine, the theoretical maximal growth yield was similar (13 g of cells per mol of ATP), but the apparent maintenance energy requirement for arginine was greater than lysine (9.4 versus 4.4 mmol of ATP per g of cells per h). On the basis of differences in yield and maintenance energy, it appeared that active arginine transport accounted for approximately 40% of the total ATP.

Animals↗

PubMed1992

Glucose toxicity and inability of Bacteroides ruminicola to regulate glucose transport and utilization.

Ammonia-limited (3.5 mM ammonia) cultures of Bacteroides ruminicola B(1)4 had a high number of viable cells (greater than 10(9)/ml), but only when the concentration of glucose was not too high (10 mM or less). When the glucose concentration was increased from 10 to 50 mM, there was a marked decrease in viability (10(5)-fold or greater). Because there was little decline in pH and only a small increase in succinate and acetate as the glucose concentration was increased, it did not appear that end products were killing the cells. This conclusion was supported by the observation that reinoculated cultures grew in the spent medium which had been supplemented with ammonia. Unlabeled rhamnose did not inhibit [14C]-glucose uptake, and cultures which were selected with a low concentration of rhamnose tolerated high concentrations of glucose (50 mM). The glucose-resistant mutant transported glucose at a lower rate than the wild type, and the Vmax of glucose transport was fourfold lower. The wild type stored much more polysaccharide than the glucose-resistant mutant, but it is not clear if polysaccharide accumulation per se is responsible for the glucose toxicity. These results indicated that B. ruminicola B(1)4 is unable to regulate glucose transport and utilization when growth is limited by ammonia.

Ammonia↗

PubMed1992

A net carbohydrate and protein system for evaluating cattle diets: I. Ruminal fermentation.

The Cornell Net Carbohydrate and Protein System (CNCPS) has a kinetic submodel that predicts ruminal fermentation. The ruminal microbial population is divided into bacteria that ferment structural carbohydrate (SC) and those that ferment nonstructural carbohydrate (NSC). Protozoa are accommodated by a decrease in the theoretical maximum growth yield (.50 vs .40 g of cells per gram of carbohydrate fermented), and the yields are adjusted for maintenance requirements (.05 vs .150 g of cell dry weight per gram of carbohydrate fermented per hour for SC and NSC bacteria, respectively). Bacterial yield is decreased when forage NDF is < 20% (2.5% for every 1% decrease in NDF). The SC bacteria utilize only ammonia as a N source, but the NSC bacteria can utilize either ammonia or peptides. The yield of NSC bacteria is enhanced by as much as 18.7% when proteins or peptides are available. The NSC bacteria produce less ammonia when the carbohydrate fermentation (growth) rate is rapid, but 34% of the ammonia production is insensitive to the rate of carbohydrate fermentation. Ammonia production rates are moderated by the rate of peptide and amino acid uptake (.07 g of peptide per gram of cells per hour), and peptides and amino acids can pass out of the rumen if the rate of proteolysis is faster than the rate of peptide utilization. The protein-sparing effect of ionophores is accommodated by decreasing the rate of peptide uptake by 34%. Validation with published data of microbial flow from the rumen gave a regression with a slope of .94 and an r2 of .88.

Ammonia↗

PubMed1992

A net carbohydrate and protein system for evaluating cattle diets: II. Carbohydrate and protein availability.

The Cornell Net Carbohydrate and Protein System (CNCPS) has a submodel that predicts rates of feedstuff degradation in the rumen, the passage of undegraded feed to the lower gut, and the amount of ME and protein that is available to the animal. In the CNCPS, structural carbohydrate (SC) and nonstructural carbohydrate (NSC) are estimated from sequential NDF analyses of the feed. Data from the literature are used to predict fractional rates of SC and NSC degradation. Crude protein is partitioned into five fractions. Fraction A is NPN, which is trichloroacetic (TCA) acid-soluble N. Unavailable or protein bound to cell wall (Fraction C) is derived from acid detergent insoluble nitrogen (ADIP), and slowly degraded true protein (Fraction B3) is neutral detergent insoluble nitrogen (NDIP) minus Fraction C. Rapidly degraded true protein (Fraction B1) is TCA-precipitable protein from the buffer-soluble protein minus NPN. True protein with an intermediate degradation rate (Fraction B2) is the remaining N. Protein degradation rates are estimated by an in vitro procedure that uses Streptomyces griseus protease, and a curve-peeling technique is used to identify rates for each fraction. The amount of carbohydrate or N that is digested in the rumen is determined by the relative rates of degradation and passage. Ruminal passage rates are a function of DMI, particle size, bulk density, and the type of feed that is consumed (e.g., forage vs cereal grain).

Animal Feed↗

PubMed1992

A net carbohydrate and protein system for evaluating cattle diets: III. Cattle requirements and diet adequacy.

The Cornell Net Carbohydrate and Protein System (CNCPS) has equations for predicting nutrient requirements, feed intake, and feed utilization over wide variations in cattle (frame size, body condition, and stage of growth), feed carbohydrate and protein fractions and their digestion and passage rates, and environmental conditions. Independent data were used to validate the ability of the CNCPS to predict responses compared to National Research Council (NRC) systems. With DMI in steers, the CNCPS had a 12% lower standard error of the Y estimate (Sy.x) and three percentage units less bias than the NRC system. For DMI in heifers, both systems had a similar Sy.x but the NRC had four percentage units less bias. With lactating dairy cows' DMI, the CNCPS had a 12% lower Sy.x. Observed NEm requirement averaged 5% under NRC and 6% under CNCPS predicted values at temperatures above 9 degrees C but were 18% over NRC and 9% under CNCPS at temperatures under 9 degrees C. Energy retained was predicted with an R2 of .80 and .95 and a bias of 8 and 4% for the NRC and CNCPS, respectively. Protein retained was predicted with an R2 of .75 and .85 with a bias of 0 and -1% for NRC and CNCPS, respectively. Biases due to frame size, implant, or NEg were small. Body condition scores predicted body fat percentage in dairy cows with an R2 of .93 and a Sy.x of 2.35% body fat. The CNCPS predicted metabolizable protein allowable ADG with a bias of 1.6% with a Sy.x of .07 kg compared to values of -30% and .10 kg, respectively for the NRC system.

Animal Feed↗

PubMed1992

Osteoid osteoma of the distal phalanx of the finger: a diagnostic challenge.

Osteoid osteomas of the distal phalanx of fingers are uncommon. An extensive review of the literature indicates that the diagnosis of osteoid osteoma of the distal phalanx is often delayed for several months to years (average 34.3 months). Pain is the most common finding (92 percent), followed by swelling and clubbing (75 percent). Relief of pain by aspirin was indicated in 10 patients (42 percent). Multiple operations were done in 7 patients prior to the appropriate diagnosis and treatment. A typical case report is presented to illustrate the difficulties in diagnosis and treatment of this benign bone tumor. A better awareness of this tumor may prevent unwanted delays in diagnosis and unnecessary operations.

Adult↗

PubMed1991

A re-assessment of bacterial growth efficiency: the heat production and membrane potential of Streptococcus bovis in batch and continuous culture.

Glucose-limited, continuous cultures (dilution rate 0.1 h-1) of Streptococcus bovis JB1 fermented glucose at a rate of 3.9 mumol mg protein-1 h-1 and produced acetate, formate and ethanol. Based on a maximum ATP yield of 32 cells/mol ATP (Stouthamer 1973) and 3 ATP/glucose, the theoretical glucose consumption for growth would have been 2.1 mumol mg protein-1 h-1. Because the maintenance energy requirement was 1.7 mumol/mg protein/h (Russell and Baldwin 1979), virtually all of the glucose consumption could be explained by growth and maintenance and the YATP was 30. Glucose-limited, continuous cultures produced heat at a rate of 0.29 mW/mg protein, and this value was similar to the enthalpy change of the fermentation (0.32 mW/mg protein). Batch cultures (specific growth rate 2.0 h-1) fermented glucose at a rate of 81 mumol mg protein-1 h-1, and produced only lactate. The heat production was in close agreement with the theoretical enthalpy change (1.72 versus 1.70 mW/mg protein), but only 80% of the glucose consumption could be accounted by growth and maintenance. The YATP of the batch cultures was 25. Nitrogen-limited, glucose-excess, non-growing cultures fermented glucose at a rate of 6.9 mumol mg protein-1 h-1, and virtually all of the enthalpy for this homolactic fermentation could be accounted as heat (0.17 mW/mg protein). The nitrogen-limited cultures had a membrane potential of 150 mV, and nearly all of the heat production could be explained by a futile cycle of protons through the cell membrane (watts = amperes X voltage where H+/ATP was 3).(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗

PubMed1991

The use of transvaginal ultrasound to aspirate bilateral hydrosalpinges prior to in vitro fertilization: a case report.

Transvaginal ultrasound has recently been introduced diagnostically for follicular monitoring, early pregnancy localization (1), pelvic structure identification, early fetal development (2), detection of ovarian enlargement in postmenopausal women (3), and detection of endometrial carcinoma (4). Transvaginal ultrasound has had a major impact on patient monitoring and treatment for in vitro fertilization and embryo transfer (IVF/ET). Therapeutically transvaginal ultrasound has been introduced for oocyte retrieval and selective pregnancy reduction. The purpose of this paper is to present the therapeutic use of transvaginal ultrasound to aspirate large bilateral hydrosalpinges which complicated embryo transfer during an in vitro fertilization cycle.

Adult↗

PubMed1991

Succinate transport by a ruminal selenomonad and its regulation by carbohydrate availability and osmotic strength.

Washed cells of strain H18, a newly isolated ruminal selenomonad, decarboxylated succinate 25-fold faster than Selenomonas ruminantium HD4 (130 versus 5 nmol min-1 mg of protein-1, respectively). Batch cultures of strain H18 which were fermenting glucose did not utilize succinate, and glucose-limited continuous cultures were only able to decarboxylate significant amounts of succinate at slow (less than 0.1 h-1) dilution rates. Strain H18 grew more slowly on lactate than glucose (0.2 versus 0.4 h-1, respectively), and more than half of the lactate was initially converted to succinate. Succinate was only utilized after growth on lactate had ceased. Although nonenergized and glucose-energized cells had similar proton motive forces and ATP levels, glucose-energized cells were unable to transport succinate. Transport by nonenergized cells was decreased by small increases in osmotic strength, and it is possible that energy-dependent inhibition of succinate transport was related to changes in cell turgor. Since cells which were deenergized with 2-deoxyglucose or iodoacetate did not transport succinate, it appeared that glycogen metabolism was providing the driving force for succinate uptake. An artificial delta pH drove succinate transport in deenergized cells, but an artificial membrane potential (delta psi) could not serve as a driving force. Because succinate is nearly fully dissociated at pH 7.0 and the transport process was electroneutral, it appeared that succinate was taken up in symport with two protons. An Eadie-Hofstee plot indicated that the rate of uptake was unusually rapid at high substrate concentrations, but the low-velocity, high-affinity component could account for succinate utilization by stationary cultures.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1991

Resistance of Streptococcus bovis to acetic acid at low pH: relationship between intracellular pH and anion accumulation.

Streptococcus bovis JB1, an acid-tolerant ruminal bacterium, was able to grow at pHs from 6.7 to 4.5, and 100 mM acetate had little effect on growth rate or proton motive force across the cell membrane. When S. bovis was grown in glucose-limited chemostats at pH 5.2, the addition of sodium acetate (as much as 100 mM) had little effect on the production of bacterial protein. At higher concentrations of sodium acetate (100 to 360 mM), production of bacterial protein declined, but this decrease could largely be explained by a shift in fermentation products (acetate, formate, and ethanol production to lactate production) and a decline in ATP production (3 ATP per glucose versus 2 ATP per glucose). YATP (grams of cells per mole of ATP) was not decreased significantly even by high concentrations of acetate. Cultures supplemented with 100 mM sodium acetate took up [14C]acetate and [14C]benzoate in accordance with the Henderson-Hasselbalch equation and gave similar estimates of intracellular pH. As the extracellular pH declined, S. bovis allowed its intracellular pH to decrease and maintained a relatively constant pH gradient across the cell membrane (0.9 unit). The decrease in intracellular pH prevented S. bovis from accumulating large amounts of acetate anion. On the basis of these results it did not appear that acetate was acting as an uncoupler. The sensitivity of other bacteria to volatile fatty acids at low pH is explained most easily by a high transmembrane pH gradient and anion accumulation.

Acetates↗

PubMed1991

Intracellular pH of acid-tolerant ruminal bacteria.

Acid-tolerant ruminal bacteria (Bacteroides ruminicola B1(4), Selenomonas ruminantium HD4, Streptococcus bovis JB1, Megasphaera elsdenii B159, and strain F) allowed their intracellular pH to decline as a function of extracellular pH and did not generate a large pH gradient across the cell membrane until the extracellular pH was low (less than 5.2). This decline in intracellular pH prevented an accumulation of volatile fatty acid anions inside the cells.

Animals↗

PubMed1991

Role of sodium in the growth of a ruminal selenomonad.

The ruminal selenomonad strain H18 grew rapidly (mu = 0.50 h-1) in a defined medium containing glucose, ammonia, purified amino acids, and sodium (95 mM); little if any ammonia was utilized as a nitrogen source. When the sodium salts were replaced by potassium salts (0.13 mM sodium), there was a small reduction in growth rate (mu = 0.34 h-1), and under these conditions greater than 95% of the cell nitrogen was derived from ammonia. No growth was observed when the medium lacked sodium (less than 0.35 mM) and amino acids were the only nitrogen source. At least six amino acid transport systems (aspartate, glutamine, lysine, phenylalanine, serine, and valine) were sodium dependent, and these systems could be driven by an electrical potential (delta psi) or a chemical gradient of sodium. H18 utilized lactate as an energy source for growth, but only when sodium and aspartate were added to the medium. Malate or fumarate was able to replace aspartate, and when these acids were added, sodium was no longer required. Glucose-grown cells accumulated large amounts of polysaccharide (64% of dry weight), and when the exogenous glucose was depleted, this material was converted to acetate and propionate as long as sodium was present. When the cells were incubated in buffers lacking sodium, succinate accumulated and exogenous succinate could not be decarboxylated. Because sodium had little effect on the transmembrane pH gradient at pH 6.7 to 4.5, it did not appear that sodium was required for intracellular pH regulation.

Amino Acids↗

PubMed1991

Electrogenic L-malate transport by Lactobacillus plantarum: a basis for energy derivation from malolactic fermentation.

L-Malate transport in Lactobacillus plantarum was inducible, and the pH optimum was 4.5. Malate uptake could be driven by an artificial proton gradient (delta pH) or an electroneutral lactate efflux. Because L-lactate efflux was unable to drive L-malate transport in the absence of a delta pH, it did not appear that the carrier was a malate-lactate exchanger. The kinetics of malate transport were, however, biphasic, suggesting that the external malate concentration was also serving as a driving force for low-affinity malate uptake. Because the electrical potential (delta psi, inside negative) inhibited malate transport, it appeared that the malate transport-lactate efflux couple was electrogenic (net negative) at high concentrations of malate. De-energized cells that were provided with malate only generated a large proton motive force (greater than 100 mV) when the malate concentration was greater than 5 mM, and malate only caused an increase in cell yield (glucose-limited chemostats) when malate accumulated in the culture vessel. The use of the malate gradient to drive malate transport (facilitated diffusion) explains how L. plantarum derives energy from malolactic fermentation, a process which does not involve substrate-level phosphorylation.

Culture Media↗

PubMed1991

A Bacteroides ruminicola 1,4-beta-D-endoglucanase is encoded in two reading frames.

Escherichia coli transformed with a plasmid containing a Bacteroides ruminicola endoglucanase (carboxymethyl cellulase [CMCase]) gene produced three immunologically cross-reacting CMCases which had molecular weights of 40,500, 84,000, and 88,000, while B. ruminicola produced CMCases with molecular weights of 82,000 and 88,000. The two B. ruminicola enzymes (purified from culture supernatants) had different N-terminal amino acid sequences, but each enzyme was encoded by the same gene (three independent clones had the same DNA sequence). The 88,000-molecular-weight CMCase (88K CMCase) gene appeared to contain two open reading frames which overlapped for 18 bp and were -1 out of frame, and each open reading frame contained several stop codons near the overlap region. The two 88K CMCase open reading frames had enough DNA to produce a protein of 106K, but the mobility of the enzyme in sodium dodecyl sulfate gels gave a value which was 20% lower. On the basis of the -1 frame shift and the large deviation in theoretical versus actual size, it appears that an unusual event (e.g., ribosomal hopping or RNA splicing) is involved in either the translation or the transcription of the 88K B. ruminicola CMCase gene. The 82K CMCase was completely encoded in the second reading frame, and its size was in agreement with the DNA sequence.

Amino Acid Sequence↗