Ethanol fermentation by ionically adsorbed Zymomomas mobilis: Environmental effects on cell immobilization

Batch ethanol fermentation by cells of Zymomomas mobilis ATCC 29191, ionically adsorbed on a DEAE-cellulose ion exchanger, was investigated in a stirred fermentor. Adsorption isotherms in different media were determined and used to interpret the effects of the environment on cell immobilization. Other factors affecting cell immobilization during an actual fermentation were studied. Mechanical agitation was found to cause detachment of cells from the ion exchange particles. The results suggest that the amount of cells adsorbed during a fermentation process is different from that found from adsorption isotherm data. Consequently, application of equilibrium adsorption data to actual fermentations should be done with caution.     

Roping injuries in the hand: mechanism of injury and functional results

Twenty-two patients with roping injuries to 38 digits, including 19 patients injured while team roping, are discussed. Ten digits in nine patients were successfully revascularized or replanted. Seven digits in three patients failed after initial success. One patient is included in both categories. The failure rate is 41 percent for all 17 digits. Average follow-up is 18 months. The dominant hand was injured in 83 percent of team roping injuries; the thumb is the most commonly injured digit. Average interphalangeal motion for thumb replants is zero; for revascularizations, it is 47 degrees. There was 43 percent return of pinch strength for thumb replants compared to 83 percent return for a single thumb revascularization. The most common mechanism of injury was catching the roping thumb in the "thumb up" position during dallying. There are good motion and pinch strength with thumb revascularizations provided tendons and the interphalangeal joint are intact. Reconstruction of the flexor pollicis longus in the replanted thumb gave poor results. Primary tenodesis or arthrodesis is recommended.     

Effect of dissolved oxygen on nitrogen fixation by A. vinelandii. I. Free cell cultures

As part of an investigation into the use of biological nitrogen fixation for fertilizer ammonia production, continuous culture studies of respiration and nitrogen fixation in the aerobic bacteria Azotobacter vinelandii under oxygen-limited conditions were conducted. Respiration and growth rates followed Monod forms with respect to dissolved oxygen concentration. However, specific nitrogen fixation rate and nitrogenase activity exhibited maximum values at dissolved oxygen concentrations of ca. 0.02 mM (10% of air saturation). These results suggest careful control of oxygen in the environment is necessary to optimize fixed nitrogen production by this organism.     

Effect of dissolved oxygen on nitrogen fixation by A. vinelandii. II. Ionically adsorbed cells

Continuous culture studies of Azotobacter vinelandii cells immobilized by ionic adsorption to Cellex E anion exchange resin were conducted under oxygen-limited conditions for comparison to free-cell cultures. Immobilization had little effect upon the specific respiration and sucrose consumption rates as compared to free cells. However, maxima in specific nitrogen fixation rate and nitrogenase activity as a function of dissolved oxygen occurred at a C(O(2) ) value of approximately 0.005 mM as opposed to 0.02 mM for free cells. Further, in contrast to free-cell culture, most of the fixed nitrogen appeared in the medium rather than within intact cells. There were strong indications that reproduction of bound cells often resulted in cell lysis accounting for the fixed nitrogen content in solution.     

Improvements in exercise performance: effects of carbohydrate feedings and diet

In an effort to determine the effects of carbohydrate (CHO) feedings immediately before exercise in both the fasted and fed state, 10 well-trained male cyclists [maximum O2 consumption (VO2 max), 4.35 +/- 0.11 l/min)] performed 45 min of cycling at 77% VO2 max followed by a 15-min performance ride on an isokinetic cycle ergometer. After a 12-h fast, subjects ingested 45 g of liquid carbohydrate (LCHO), solid carbohydrate confectionery bar (SCHO), or placebo (P) 5 min before exercise. An additional trial was performed in which a high-CHO meal (200 g) taken 4 h before exercise was combined with a confectionery bar feeding (M + SCHO) immediately before the activity. At 10 min of exercise, serum glucose values were elevated by 18 and 24% during SCHO and LCHO, respectively, compared with P. At 0 and 45 min no significant differences were observed in muscle glycogen concentration or total use between the four trials. Total work produced during the final 15 min of exercise was significantly greater (P less than 0.05) during M + SCHO (194,735 +/- 9,448 N X m), compared with all other trials and significantly greater (P less than 0.05) during LCHO and SCHO (175,204 +/- 11,780 and 176,013 +/- 10,465 N X m, respectively) than trial P (159,143 +/- 11,407 N X m). These results suggest that, under conditions when CHO stores are less than optimal, exercise performance is enhanced with the ingestion of 45 g of CHO 5 min before 1 h of intense cycling.(ABSTRACT TRUNCATED AT 250 WORDS)     

mtDNA diversity in rhesus monkeys reveals overestimates of divergence time and paraphyly with neighboring species

Reconstructions of the human-African great ape phylogeny by using mitochondrial DNA (mtDNA) have been subject to considerable debate. One confounding factor may be the lack of data on intraspecific variation. To test this hypothesis, we examined the effect of intraspecific mtDNA diversity on the phylogenetic reconstruction of another Plio- Pleistocene radiation of higher primates, the fascicularis group of macaque (Macaca) monkey species. Fifteen endonucleases were used to identify 10 haplotypes of 40-47 restriction sites in M. mulatta, which were compared with similar data for the other members of this species group. Interpopulational, intraspecific mtDNA diversity was large (0.5%- 4.5%), and estimates of divergence time and branching order incorporating this variation were substantially different from those based on single representatives of each species. We conclude that intraspecific mtDNA diversity is substantial in at least some primate species. Consequently, without prior information on the extent of genetic diversity within a particular species, intraspecific variation must be assessed and accounted for when reconstructing primate phylogenies. Further, we question the reliability of hominoid mtDNA phylogenies, based as they are on one or a few representatives of each species, in an already depauperate superfamily of primates.      

Effects of glutamate, glucose, phosphate, and alkali metal ions on cephamycin C production by Nocardia lactamdurans in defined media

A High cephamycin C producing strain of Nocardia lactam-durans was used to study cell growth and antibiotics production in defined media. Batch fermentations in shake flasks and stirred tanks showed that antibiotic production occurred during cell growth and the production rate rapidly decline as the growth slowed. Glutamate served as a primary substrate during this phase. Later, ammonia was utilized along with a remainder of the glucose. Rapid antibiotic production occurred in this phase. Increased glutamate promoted higher growth, a rise in ammonium ion concentration, and a marked reduction in antibiotic titers. An increase of the glucose concentration along with the glutamate concentration balanced to the medium; no ammonium ion rise occurred and a peak specific antibiotic titer comparable to the control medium was obtained. In a phosphate-limited medium, cell growth equivalent to the control medium and increased antibiotic titers were obtained. In these experiments, adjustment of Na(+) and K(+) ion concentration equal to that in the control medium was found to be important. Based on carbon and nitrogen balances, the activity of the key nitrogen metabolism enzymes, and the published literature, a two-stage model of regulation is suggested.     

Eccentric exercise induces transient insulin resistance in healthy individuals.

Euglycemic-hyperinsulinemic clamps were performed on six healthy untrained individuals to determine whether exercise that induces muscle damage also results in insulin resistance. Clamps were performed 48 h after bouts of predominantly 1) eccentric exercise [30 min, downhill running, -17% grade, 60 +/- 2% maximal O2 consumption (VO2max)], 2) concentric exercise (30 min, cycle ergometry, 60 +/- 2% VO2max), or 3) without prior exercise. During the clamps, euglycemia was maintained at 90 mg/dl while insulin was infused at 30 mU.m-2.min-1 for 120 min. Hepatic glucose output (HGO) was determined using [6,6-2H]glucose. Eccentric exercise caused marked muscle soreness and significantly elevated creatine kinase levels (273 +/- 73, 92 +/- 27, 87 +/- 25 IU/l for the eccentric, concentric, and control conditions, respectively) 48 h after exercise. Insulin-mediated glucose disposal rate was significantly impaired (P less than 0.05) during the clamp performed after eccentric exercise (3.47 +/- 0.51 mg.kg-1.min-1) compared with the clamps performed after concentric exercise (5.55 +/- 0.94 mg.kg-1.min-1) or control conditions (5.48 +/- 1.0 mg.kg-1.min-1). HGO was not significantly different among conditions (0.77 +/- 0.26, 0.65 +/- 0.27, and 0.66 +/- 0.64 mg.kg-1.min-1 for the eccentric, concentric, and control clamps, respectively). The insulin resistance observed after eccentric exercise could not be attributed to altered plasma cortisol, glucagon, or catecholamine concentrations. Likewise, no differences were observed in serum free fatty acids, glycerol, lactate, beta-hydroxybutyrate, or alanine. These results show that exercise that results in muscle damage, as reflected in muscle soreness and enzyme leakage, is followed by a period of insulin resistance.     

Phenotypic Switching Induced by Damaged Matrix Is Associated with DNA Methyltransferase 3A (DNMT3A) Activity and Nuclear Localization in Smooth Muscle Cells (SMC)

Extracellular matrix changes are often crucial inciting events for fibroproliferative disease. Epigenetic changes, specifically DNA methylation, are critical factors underlying differentiated phenotypes. We examined the dependency of matrix-induced fibroproliferation and SMC phenotype on DNA methyltransferases. The cooperativity of matrix with growth factors, cell density and hypoxia was also examined. Primary rat visceral SMC of early passage (0–2) were plated on native collagen or damaged/heat-denatured collagen. Hypoxia was induced with 3% O₂ (balanced 5% CO₂ and 95% N₂) over 48 hours. Inhibitors were applied 2–3 hours after cells were plated on matrix, or immediately before hypoxia. Cells were fixed and stained for DNMT3A and smooth muscle actin (SMA) or smooth muscle myosin heavy chain. Illumina 450 K array of CpG sites was performed on bisulfite-converted DNA from smooth muscle cells on damaged matrix vs native collagen. Matrix exquisitely regulates DNMT3A localization and expression, and influences differentiation in SMCs exposed to denatured matrix +/− hypoxia. Analysis of DNA methylation signatures showed that Matrix caused significant DNA methylation alterations in a discrete number of CpG sites proximal to genes related to SMC differentiation. Matrix has a profound effect on the regulation of SMC phenotype, which is associated with altered expression, localization of DNMTs and discrete changes DNA methylation.