Biomedical subjects

J B Russell

Publications and source records attributed to J B Russell.

At least 109 records · Page 6Linked to original sources

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↗

PubMed1991

Effect of monensin and a protonophore on protein degradation, peptide accumulation, and deamination by mixed ruminal microorganisms in vitro.

Mixed ruminal bacteria (80 mg N/liter) degraded casein and soluble soy protein rapidly (.68 and .72 mg N/[liter.min], respectively), but ammonia was produced at a slower rate (.08 and .10 mg N/[liter.min], respectively). Because there was little increase in cell protein, ammonia production could not account for all the degraded protein. Large quantities of non-ammonia, non-protein nitrogen (NAN-NPN) accumulated, and this NAN-NPN reacted more strongly (2- to 14-fold) with ninhydrin after it was treated with 6 N HCl (110 degrees C, 24 h) or pronase E. Even after 96 h of incubation, 10% of the protein N was still found in the NAN-NPN pool. Monensin had little effect on protein degradation, but it caused a large decrease in ammonia production (P less than .05) and an increase in NAN-NPN (P less than .05). These results indicated that significant quantities of peptide N could not be degraded by ruminal microorganisms and that monensin could increase peptide flow from the rumen. Because 3,3',4',5-tetrachlorosalicylanide, a protonophore that inhibits both Gram-positive and Gram-negative bacteria, did not cause a greater decrease (P greater than .05) in ammonia than monensin, an ionophore that is primarily effective against Gram-positive bacteria, it seemed that the "protein sparing" of monensin could largely be explained by its inhibition of Gram-positive bacteria.

Ammonia↗

PubMed1991

Repeated ectopic pregnancy.

The literature concerning ectopic pregnancy is reviewed with regard to the information on multiple ectopic pregnancies. The epidemiology, causes, and treatments for multiple ectopic pregnancies are summarized. In addition, the results of radical and conservative surgical management procedures and medical management are discussed in the context of the fertility of patients with multiple ectopic pregnancies, and procedures appropriate for the infertile patient are discussed.

Adult↗

PubMed1990

ATPase-dependent energy spilling by the ruminal bacterium, Streptococcus bovis.

When the ruminal bacterium Streptococcus bovis was grown in batch culture with glucose as the energy source, the doubling time was approximately 21 min and the rate of bacterial heat production was proportional to the optical density (1.72 microW/micrograms protein). If exponentially growing cultures were treated with chloramphenicol, there was a decline in heat production, but the rate was greater than 0.30 microW/micrograms protein even after growth ceased. Since there was no heat production after glucose depletion, this growth-independent energy dissipation (spilling) was not simply due to endogenous metabolism. Stationary cells which were washed and incubated in nitrogen-free medium containing an excess of glucose produced heat at a rate of 0.17 microW/micrograms protein. Monensin and tetrachlorosalicylanilide (TCS), compounds which facilitate an influx of protons, caused a more than 2-fold increase in heat production. Dicyclohexylcarbodiimide (DCCD) virtually eliminated growth-independent heat production regardless of the mode of growth inhibition. Because DCCD had little effect on the glucose phosphotransferase system, it appeared that the combined action of proton influx and the membrane bound F1F0 proton ATPase was responsible for energy spilling.

Adenosine Triphosphatases↗

PubMed1990

When is polypectomy sufficient treatment for colorectal cancer in a polyp?

Eighty-seven patients with a carcinoma in a polyp were reviewed over a 12-year period. Ten histologic criteria were analyzed for an association with the presence of residual carcinoma. Four factors were identified as having prognostic value: size greater than 1.5 cm, sessility, cancer of at least 50% of the adenoma volume, and invasive carcinoma. Polypectomy alone is adequate treatment unless the carcinoma invades deeper to the muscularis mucosa and is associated with one or more of these characteristics.

Aged↗

PubMed1990

Low-affinity, high-capacity system of glucose transport in the ruminal bacterium Streptococcus bovis: evidence for a mechanism of facilitated diffusion.

The glucose phosphotransferase system (PTS) of Streptococcus bovis could not account for the glucose consumption of exponential cultures, and the kinetics of glucose transport were biphasic. A PTS-deficient mutant lost the high-affinity, low-capacity system but retained its ability to take up glucose at high substrate concentrations. The low-affinity, high-capacity system did not require a proton motive force or ATP and could not be driven by an artificial membrane potential in the presence or absence of sodium. Since low-affinity transport was directly proportional to the external substrate concentration and exhibited counterflow kinetics, it appeared that a facilitated-diffusion mechanism was responsible for glucose transport at high substrate concentrations.

Animals↗