PubMed Health⌕ Search

Biomedical subjects

J B Russell

Publications and source records attributed to J B Russell.

At least 145 records · Page 8Linked to original sources
PubMed1988

Enrichment and isolation of a ruminal bacterium with a very high specific activity of ammonia production.

When mixed ruminal bacteria were inoculated into semicontinuous cultures (25% transfer every other day) containing lactate, dulcitol, pectin, or xylose and Trypticase (1 g/liter) as the sole nitrogen source, the specific activity of ammonia production increased. The greatest enrichment was observed with lactate and xylose, and in these cases the specific rate of ammonia production was eightfold higher than that of the ruminal fluid control (approximately 35 nmol of ammonia per mg of protein per min). Isolates with different morphologies were obtained from each of the enrichments, but in no case did the specific activity of any isolate exceed that of the mixed ruminal bacteria. If Trypticase (15 g/liter) was used as the only energy and nitrogen source, there was an even greater increase in ammonia production, and two monensin-sensitive bacteria, a Peptostreptococcus species and a Clostridium species, were obtained. The Peptostreptococcus species was unable to grow on any of 25 carbohydrate or carbohydrate derivatives tested; but the Clostridium species was able to use glucose, maltose, fructose, cellobiose, trehalose, sorbitol, and salicin as energy sources. Neither organism was able to grow in the absence of an amino acid source, but growth rates on Trypticase were greater than 0.35/h. The specific activities of ammonia production were 346 and 427 nmol/mg of protein per min for strains of Peptostreptococcus and Clostridium, respectively. Megasphaera elsdenii and Bacteroides ruminicola, previously isolated ruminal ammonia producers, had specific activities of only 11 and 19 nmol of ammonia per mg of protein per min, respectively. The most probable number of Clostridium species in ruminal fluid was less than 10(3)/ml, but the Peptostreptococcus species was present at 10(8)/ml.(ABSTRACT TRUNCATED AT 250 WORDS)

Ammonia↗
PubMed1988

Sodium-dependent transport of neutral amino acids by whole cells and membrane vesicles of Streptococcus bovis, a ruminal bacterium.

Streptococcus bovis JB1 cells were able to transport serine, threonine, or alanine, but only when they were incubated in sodium buffers. If glucose-energized cells were washed in potassium phosphate and suspended in potassium phosphate buffer, there was no detectable uptake. Cells deenergized with 2-deoxyglucose and incubated in sodium phosphate buffer were still able to transport serine, and this result indicated that the chemical sodium gradient was capable of driving transport. However, when the deenergized cells were treated with valinomycin and diluted into sodium phosphate to create both an artificial membrane potential and a chemical sodium gradient, rates of serine uptake were fivefold greater than in cells having only a sodium gradient. If deenergized cells were preloaded with sodium (no membrane potential or sodium gradient), there was little serine transport. Nigericin and monensin, ionophores capable of reversing sodium gradients across membranes, strongly inhibited sodium-dependent uptake of the three amino acids. Membrane vesicles loaded with potassium and diluted into either lithium or choline chloride were unable to transport serine, but rapid uptake was evident if sodium chloride was added to the assay mixture. Serine transport had an extremely poor affinity for sodium, and more than 30 mM was needed for half-maximal rates of uptake. Serine transport was inhibited by an excess of threonine, but an excess of alanine had little effect. Results indicated that S. bovis had separate sodium symport systems for serine or threonine and alanine, and either the membrane potential or chemical sodium gradient could drive uptake.

Alanine↗
PubMed1988

Effects of additives on in vitro ruminal fermentation: a comparison of monensin and bacitracin, another gram-positive antibiotic.

Mixed ruminal bacteria (n = 4) were incubated in anaerobic media for 24 h in vitro with either hay, corn meal, protein hydrolyzate or hydrogen gas as the substrate. The ionophore monensin and the polypeptide antibiotic bacitracin were added to the incubation flasks at concentrations ranging from 0 to 10 or 40 mg/liter. As was expected, monensin decreased methane production, increased the ratio of propionate to acetate and decreased the deamination of amino acids. Monensin had little effect on methane production, however, if hydrogen gas was the fermentation substrate. Bacitracin, another gram-positive antibiotic with a distinctly different cellular target, was somewhat less potent than monensin, but it produced strikingly similar responses. This similarity of fermentation patterns suggested that monensin action in the rumen is probably due to its activity as a gram-positive antibiotic, and that any gram-positive antibiotic not suppressed by resistance may produce fermentation effects similar to those of monensin. The cellular action of monensin as an ionophore in membranes is probably little more than a means of inhibiting sensitive species. Many gram-positive antibiotics have little affect on ciliate protozoa or coccidia.

Animals↗
PubMed1988

History and development of hysteroscopy.

The hysteroscope has evolved over the last two centuries. The first scientist to conduct light into the human body was Bozzini in 1805. The hysteroscope as we know it today is similar to the early cystoscope described and presented in 1877 by Nitze. The instruments and technique of endoscopy underwent advances by people such as Heineberg (1914), Rubin (1925), Mickulicz-Radecki (1927), and Norment (1949). Vulmiere applied cold light fiberoptics, and Marleschki (1965) introduced the early form of the contact hysteroscope. Edström and Fernström introduced the use of a solution of a high-molecular-weight dextran from beet sugar as a distending medium, and Hamou (1980) designed a 4-mm microcolpohysteroscope for histologic diagnosis in the reproductive tract.

Endoscopy↗
PubMed1987

Serum prolactin response to embryo transfer during human in vitro fertilization and embryo transfer.

Serum prolactin (PRL) concentrations around the time of embryo transfer (ET) have not been studied, despite the fact that transient hyperprolactinemia regularly occurs in response to laparoscopy for oocyte recovery and ET itself may be stressful enough to induce a PRL rise. Hyperprolactinemia might compromise luteal support for implantation and contribute to the limited success of ET. We measured serum PRL concentrations in 10 normoprolactinemic women immediately before, during, and after ET and compared the PRL response around ET to that induced by laparoscopy as a measure of the competency of the stress-prolactin axis. Nine of ten patients demonstrated a significant PRL response to surgery. The mean (+/- SEM) intraoperative PRL concentration (124.0 +/- 19.6 ng/ml) was significantly higher than the preoperative level (12.3 +/- 2.4 ng/ml) (P less than 0.01). Three hours after surgery PRL levels had decreased (44.8 +/- 11.5 ng/ml) but remained above baseline. All subjects were normoprolactinemic 48 hr after laparoscopy. Serum PRL concentration did not change significantly in response to ET, with levels of 10.4 +/- 1.7, 12.4 +/- 1.1, and 10.6 +/- 1.8 ng/ml immediately before, during, and 3 hr after ET, respectively. While laparoscopy for in vitro fertilization--embryo transfer commonly induces hyperprolactinemia, the PRL rise is transient, with no carryover to the time of ET. Embryo transfer itself does not induce a significant PRL rise.

Embryo Transfer↗
PubMed1987

Weight of babies conceived in vitro.

Recent studies suggested that infants delivered after in vitro fertilization and embryo transfer IVF-ET had low birth weights. To assess further the relationship between birth weight and EGA in these offspring, a review was made of all infants delivered at our institution from May 1, 1983 to July 15, 1986. Forty-five infants in 39 deliveries were identified. Seventeen of 37 (46%) were delivered vaginally, 20 by cesarean section. Forty-two infants were delivered at term (after 36 weeks). The six sets of twins delivered at 254 +/- 7 days (mean, 36 weeks). Eighteen of 39 deliveries (46%) delivered at or beyond 40 weeks EGA. The mean weight at delivery for the term infants was 3225 +/- 90 g. Thirty-eight infants were size appropriate for dates as assessed by the Lubchenco scale, while the weight in the remaining seven infants exceeded the 90th percentile for their gestational age. We conclude that infants conceived through IVF-ET are not predisposed per se to a low birth weight or delivery at an early gestational age. However, prior studies suggesting lower birth weights for IVF infants may have resulted in part from early delivery due to patient pressure and anxiety.

Birth Weight↗
PubMed1987

Effects of vitamin D3, 25-hydroxyvitamin D3, and 24,25-dihydroxyvitamin D3 on parathyroid hormone secretion.

The active vitamin D metabolite 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] causes marked suppression of both pre-proparathyroid hormone messenger RNA (pre-proPTH mRNA) and parathyroid hormone (PTH) secretion. These effects are dose dependent and reversible when tested in an in vitro primary tissue culture cell system using normal bovine parathyroid cells. In the current studies, the precursors of 1,25(OH)2D3 and the related metabolite 24,25-dihydroxyvitamin D3 [24,25(OH)2D3], were used in the same culture system to test for possible regulatory effects. The results were compared with identically prepared cells exposed to 1,25(OH)2D3. In short-term studies (30-120 minutes), none of the vitamin D-related compounds produced any effect on PTH secretion. In long-term studies (24-48 hours, using primary tissue culture in the presence of test agents), neither vitamin D3 nor 25(OH)D3 affected PTH secretion or pre-proPTH mRNA over the concentration range 10(-11)-10(-7) M. On the other hand, 24,25(OH)2D3 produced significant suppression of both pre-proPTH mRNA (77% of control, P less than .01) and PTH secretion (75% of control, P less than .005) at 10(-7) M. By comparison, 10(-11) M 1,25(OH)2D3 produced levels of suppression (25-30%) of both pre-proPTH mRNA and PTH secretion comparable to 10(-7) M 24,25(OH)2D3, while even greater suppression (40-50%) occurred at 10(-9)-10(-7) M 1,25(OH)2D3. From these studies, we conclude that vitamin D3 and 25(OH)D3 do not have significant effects on PTH synthesis and secretion over the range of doses tested.(ABSTRACT TRUNCATED AT 250 WORDS)

24,25-Dihydroxyvitamin D 3↗
PubMed1987

Outcome of in vitro fertilization in women with low response to ovarian stimulation.

The occurrence of low-response (LR) cycles (defined as peak estradiol levels less than 300 pg/ml) in an in vitro fertilization program using a 3 ampule/day human menopausal gonadotropin regimen were retrospectively reviewed. LR occurred in 51 of 564 patients (9%). The LR serum estradiol levels were categorized into four different patterns that were further analyzed for outcome in these initial cycles, as well as for their predictive value of response in subsequent in vitro fertilization cycles. Changing the stimulation protocol to a combination of clomiphene citrate and human menopausal gonadotropin did not improve the ovarian response in this group of LR patients, and their chance to complete a subsequent normal-response treatment cycle was 32%. Suggestions are made to predict outcome and govern management of women with previous LR cycles.

Adult↗
PubMed1987

The effect of polyploidy on embryo cleavage after in vitro fertilization in humans.

The effect of polyploidy on the early development of human embryos is unknown. This study compares the early development of 90 polyploid and 275 diploid human embryos conceived in vitro. Between May 1983 and January 1986, 3081 oocytes were recovered during 631 cycles of laparoscopy for in vitro fertilization (4.9 oocytes/cycle); 1924 oocytes (62.4%) fertilized. There were 90 oocytes with more than two pronuclei (4.7% of fertilized oocytes), identified in 72 cycles (11.4% of cycles). In these cycles, the proportion of diploid oocytes (n = 275) that cleaved (cleavage rate) (92.7%) was significantly greater than the proportion of polyploid oocytes (n = 90) that cleaved (65.5%) (P less than 0.001). The cleavage rate for all diploid oocytes (n = 1834) was 90.4%. There was no significant difference in the stage of development (number of blastomeres; mean +/- standard deviation [SD]) on the day of embryo transfer between diploid (4.3 +/- 2.1) and polyploid (4.1 +/- 2.1) embryos that cleaved, but a plot of the frequency distribution of cleavage stages revealed that significantly more polyploid than diploid embryos had an uneven number of blastomeres at that time (33% versus 8%, respectively; P less than 0.001). Polyploidy confers an immediate developmental disadvantage; one third of polyploid embryos fail to cleave, and those that do divide demonstrate more asynchronous divisions.

Blastomeres↗
PubMed1987

A paired analysis of in vitro fertilization and cleavage rates of first- versus last-recovered preovulatory human oocytes exposed to varying intervals of 100% CO2 pneumoperitoneum and general anesthesia.

This study compares the in vitro fertilization and cleavage rates of paired first- and last-recovered preovulatory human oocytes that were exposed to a 100% CO2 pneumoperitoneum and general anesthesia. In 305 consecutive cycles of laparoscopy, 1741 oocytes (5.7/cycle) were recovered. The exact time of aspiration (T) was recorded for each oocyte. The time interval (T1 to T2) between recovery of first and last oocytes ranged from 0 to 38 minutes and represented differences in the exposure time of first and last oocytes to the CO2 pneumoperitoneum and to general anesthesia. For all cycles (n = 305) without regard for T1 to T2, last-recovered oocytes fertilized less often than first-recovered eggs (P = 0.06; McNemar's test). When T1 to T2 was short (less than or equal to 5 minutes), first- and last-recovered oocytes fertilized at comparable rates (70.8% and 74.0%). When only cycles with T1 to T2 greater than 5 minutes were considered (n = 209), the difference in fertilization rates between first and last oocytes (68.5% versus 56.4%) was highly significant (P less than 0.01; McNemar's test). Pairing negated differences due to patient, cycle, or semen variables and first- and last-recovered oocytes had comparable maturity scores (4.0 +/- 0.5 versus 4.3 +/- 0.8). There were no significant differences in cleavage rates for first- and last-recovered oocytes that fertilized, regardless of the exposure interval (T1 to T2). We conclude that exposure to a 100% CO2 pneumoperitoneum and/or general anesthesia may adversely affect oocyte quality.

Anesthesia, General↗
PubMed1987

The etiology of ectopic pregnancy.

The cause of ectopic pregnancy is associated with two major categories: the integrity of the oviduct and the quality of the fertilized ovum. Several conditions that alter the tubal transport system include inflammatory insults, intrauterine devices, surgical manipulation, tubal ligations, salpingitis isthmica nodusa, DES exposure, and induced abortions. Risk factors that may theoretically alter ovum quality or the hormonal environment include ovulation induction, fertilization in vitro, delayed ovulation, and transperitoneal ovum migration. As we continue to investigate the fallopian tube and the fertilized ovum as unique entities, our knowledge will increase about the cause of ectopic gestations.

Abortion, Induced↗
PubMed1987

Effect of extracellular pH on growth and proton motive force of Bacteroides succinogenes, a cellulolytic ruminal bacterium.

The utilization of cellulose or cellobiose by Bacteroides succinogenes S85 was severely inhibited at pH values of less than 5.7. Since low pH inhibited the utilization of both cellobiose and cellulose, changes in cellulase activity could not explain the effect. At an extracellular pH of 6.9, the pH gradient (delta pH) across the cell membrane was only 0.07 U. As extracellular pH declined from 6.9 to 5.7, intracellular pH decreased to a smaller extent than extracellular pH and delta pH increased. Below pH 5.7, there was a linear and nearly proportional decrease in intracellular pH. B. succinogenes took up the lipophilic cation tetraphenylphosphonium ion (TPP+) in the presence of cellobiose, and uptake was sensitive to the ionophore valinomycin. As pH was decreased with phosphoric acid, the cells lost TPP+ and electrical potential, delta psi, decreased. From extracellular pH 6.9 to 5.7, the decrease in delta psi was compensated for by an increase in delta pH, and the proton motive force ranged from 152 to 158 mV. At a pH of less than 5.7, there was a large decrease in proton motive force, and this decrease corresponded to the inhibition of cellobiose utilization.

Animals↗
PubMed1987

Transport and phosphorylation of disaccharides by the ruminal bacterium Streptococcus bovis.

Toluene-treated cells of Streptococcus bovis JB1 phosphorylated cellobiose, glucose, maltose, and sucrose by the phosphoenolpyruvate-dependent phosphotransferase system. Glucose phosphorylation was constitutive, while all three disaccharide systems were inducible. Competition experiments indicated that separate phosphotransferase systems (enzymes II) existed for glucose, maltose, and sucrose. [14C]maltose transport was inhibited by excess (10 mM) glucose and to a lesser extent by sucrose (90 and 46%, respectively). [14C]glucose and [14C]sucrose transports were not inhibited by an excess of maltose. Since [14C]maltose phosphorylation in triethanolamine buffer was increased 160-fold as the concentration of Pi was increased from 0 to 100 mM, a maltose phosphorylase (Km for Pi, 9.5 mM) was present, and this activity was inducible. Maltose was also hydrolyzed by an inducible maltase. Glucose 1-phosphate arising from the maltose phosphorylase was metabolized by a constitutive phosphoglucomutase that was specific for alpha-glucose 1-phosphate (Km, 0.8 mM). Only sucrose-grown cells possessed sucrose hydrolase activity (Km, 3.1 mM), and this activity was much lower than the sucrose phosphotransferase system and sucrose-phosphate hydrolase activities.

Animals↗
PubMed1987

Regulation of beta-glucosidase in Bacteroides ruminicola by a different mechanism: growth rate-dependent derepression.

Bacteroides ruminicola B(1)4, a predominant ruminal and cecal bacterium, was grown in batch and continuous cultures, and beta-glucosidase activity was measured by following the hydrolysis of p-nitrophenyl-beta-glucopyranoside. Specific activity was high when the bacterium was grown in batch cultures containing cellobiose, mannose, or lactose (greater than 286 U/g of protein). Activity was reduced approximately 90% when the organism was grown on glucose, sucrose, fructose, maltose, or arabinose. The specific activity of cells fermenting glucose was initially low but increased as glucose was depleted. When glucose was added to cultures growing on cellobiose, beta-glucosidase synthesis ceased immediately. Catabolite repression by glucose was not accompanied by diauxic growth and was not relieved by cyclic AMP. Since glucose-grown cultures eventually exhibited high beta-glucosidase activity, cellobiose was not needed as an inducer. Catabolite repression explained beta-glucosidase activity of batch cultures and high-dilution-rate chemostats where glucose accumulated, but it could not account for activity at slow dilution rates. Maximal beta-glucosidase activity was observed at a dilution rate of approximately 0.35 h-1, and cellobiose-limited chemostats showed a 15-fold decrease in activity as the dilution rate declined. An eightfold decline was observed in glucose-limited chemostats. Since inducer availability was not a confounding factor in glucose-limited chemostats, the growth rate-dependent derepression could not be explained by other mechanisms.

Animals↗
PubMed1987

Effect of hydrophobicity of utilization of peptides by ruminal bacteria in vitro.

When mixed ruminal bacteria were incubated with a pancreatic casein hydrolysate and free amino acids of a similar composition, rates of ammonia production were much greater for peptides than for amino acids. The pancreatic digest of casein was then fractionated with 90% isopropyl alcohol. Hydrophobic peptides which dissolved in alcohol contained an abundance of phenolic and aliphatic amino acids, while the hydrophilic peptides which were precipitated by alcohol contained a large proportion of the highly charged amino acids. The Km values of the mixed ruminal bacteria for each fraction were similar (0.88 versus 0.98 g/liter), but the Vmax of the hydrophilic peptides was more than twice that of the hydrophobic peptides (18 versus 39 mg of NH3 per g of bacterial protein per h). Pure cultures of ruminal bacteria had a similar preference for hydrophilic peptides and likewise utilized peptides at a faster rate than free amino acids. Since peptide degradation rates differed greatly, hydrophobicity is likely to influence the composition of amino acids passing unfermented to the lower gut of ruminant animals.

Amino Acids↗
PubMed1987

Relative contributions of ruminal bacteria and protozoa to the degradation of protein in vitro.

Mixed ruminal microorganisms from a cow fed timothy hay and concentrate supplement (50:50) were incubated with various protein sources for 15 h (no carbohydrates or growth), and deamination was studied under enzyme-limiting substrate-excess conditions (n = 3). Addition of amphotericin (10 micrograms/ml) killed protozoa and decreased (P less than .05) ammonia production from killed bacteria but it had no effect (P greater than .05) on casein deamination. Monensin (5 micrograms/ml) also killed protozoa; however, it decreased (P less than .05) casein deamination to a much greater extent than amphotericin. Antibacterial antibiotics (penicillin G, polymixin B, cephalosporin C and streptomycin) greatly reduced (P less than .05) ammonia formation from casein. Isolated bacteria always produced more ammonia than isolated protozoa, but the difference was less with heat-treated, particulate proteins. Heated soybean protein was as soluble as heated casein but it was deaminated (P less than .05) at a faster rate by bacteria. Nonammonia-nonprotein N accumulation was greater (P less than .05) with the protozoa than bacteria. When incubations containing bacteria or protozoa were compared with combinations of protozoa and bacteria, the combinations always caused a synergistic increase in ammonia and decrease (P less than .05) in nonammonia-nonprotein N. These results suggest: soluble proteins were primarily degraded by bacteria; protozoa could contribute to the degradation of insoluble, particulate proteins; protozoa were limited in their ability to assimilate peptides (or amino acids); low molecular weight products could be fermented more readily by bacteria and monensin was toxic to protozoa, but decreases in ammonia were primarily due to action of monensin on bacteria.

Animals↗