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Biomedical subjects

L Montgomery

Publications and source records attributed to L Montgomery.

32 records · Page 2Linked to original sources
PubMed1988

Enumeration and isolation of cellulolytic and hemicellulolytic bacteria from human feces.

The fibrolytic microbiota of the human large intestine was examined to determine the numbers and types of cellulolytic and hemicellulolytic bacteria present. Fecal samples from each of five individuals contained bacteria capable of degrading the hydrated cellulose in spinach and in wheat straw pretreated with alkaline hydrogen peroxide (AHP-WS), whereas degradation of the relatively crystalline cellulose in Whatman no. 1 filter paper (PMC) was detected for only one of the five samples. The mean concentration of cellulolytic bacteria, estimated with AHP-WS as a substrate, was 1.2 X 10(8)/ml of feces. Pure cultures of bacteria isolated on AHP-WS were able to degrade PMC, indicating that interactions with other microbes were primarily responsible for previous low success rates in detecting fecal cellulolytic bacteria with PMC as a substrate. The cellulolytic bacteria included Ruminococcus spp., Clostridium sp., and two unidentified strains. The mean concentration of hemicellulolytic bacteria, estimated with larchwood xylan as a substrate, was 1.8 X 10(10)/ml of feces. The hemicellulose-degrading bacteria included Butyrivibrio sp., Clostridium sp., Bacteroides sp., and two unidentified strains, as well as four of the five cellulolytic strains. This work demonstrates that many humans harbor intestinal cellulolytic bacteria and that a hydrated cellulose source such as AHP-WS is necessary for their consistent detection and isolation.

Adult↗
PubMed1987

Effects of feed intake and dietary urea concentration on ruminal dilution rate and efficiency of bacterial growth in steers.

Four multiple-fistulated steers (340 kg) were fed a diet containing 50% ground grass hay, 20% dry distillers grains, and 30% concentrate at two intakes (7.2 or 4.8 kg DM/d). Urea (.4 or 1.2% of the diet) was infused continuously into the steers' rumens. The experimental design was a 4 X 4 Latin square with a 2 X 2 factorial arrangement of treatments. Infusing urea at .4 or 1.2% of the diet resulted in ruminal NH3 N concentrations of 4.97 and 9.10 mg/dl, respectively. Feeding steers at high rather than low intake decreased ruminal and total tract digestibilities of organic matter, NDF, and ADF but did not increase ruminal escape of N. However, apparent N escape from the rumen calculated using purines, but not 15N, as a bacterial marker was higher when 1.2 vs. .4% urea was infused. Feeding at high rather than at low intake increased the total pool of viable bacteria per gram organic matter fermented in the rumen. Although ruminal fluid outflows and particulate dilution rates were greater when steers were fed at high than at low intakes, efficiencies of bacterial protein synthesis were unaffected by intake. The possibility of increased N recycling within the rumen with feeding at the higher intake is discussed.

Animal Feed↗
PubMed1986

Mechanisms of synergism between arteriolar embolization and hyperthermia in a rabbit V-2 model of solitary hepatic metastasis.

In a V-2 model of solitary hepatic metastasis, residual tumor was histologically identified in the treatment field in only three of 14 (21%) animals subjected to microsphere embolization of tumor arterioles plus focal (43 degrees C, 40 min) hyperthermia compared with seven of ten (70%) subjected to focal (43 degrees C, 40 min) hyperthermia alone (P less than or equal to 0.05), five of seven (71%) (P less than or equal to 0.05) treated by occlusion plus sham heating, and five of five (100%) (P less than or equal to 0.01) sham-treated controls. Prior occlusion tended to reduce the radiofrequency power required for heat up and steady-state temperature maintenance of tumors (P less than or equal to 0.09 and P less than or equal to 0.06, respectively) and reduced the cooling rate after heating compared to unoccluded tumors (P less than or equal to 0.02) but did not affect mean time to temperature, maximum and minimum temperature measured at the tumor-normal tissue interface, and animal core temperature compared with that of the hyperthermia alone treatment group. In ten other animals with hepatic V-2 tumors of comparable size subjected to focal hyperthermia plus or minus arteriolar embolization, temperatures were continuously monitored at four additional intratumor sites in a fixed geometric orientation around the heating probe. No significant differences were noted in maximum and minimum temperatures in comparably oriented probes over a 40-min heating period between the hyperthermia and the occlusion-hyperthermia treatment groups. In five other animals with solitary V-2 hepatic implants, comparable microembolization plus or minus focal tumor heating to 43 degrees C, 40 min, did not significantly reduce tumor interstitial pH compared with pretreatment values. This study reproduces previously observed synergism between arteriolar embolization and hyperthermia but suggests the mechanism may be unrelated to observable differences in intratumor pH and thermal profile and may result from other mechanisms, perhaps by mimicking the angioocclusive effects of hyperthermia itself.

Animals↗
PubMed1982

Relationship of N-arylacetamide metabolism and macromolecular binding to oncogenic transformation of C3H10T1/2CL8 cells.

The C3H10T1/2CL8 mouse embryo oncogenic transformation bioassay system detects a wide variety of chemical carcinogens. However, one carcinogen that does not transform C3H10T1/2CL8 cells is the liver carcinogen N-2-fluorenylacetamide (FAA). Previous reports indicate that an activated form of FAA, N-acetoxy-FAA (N-OAc-FAA), transforms these fibroblasts. In an effort to understand these results, the metabolism and binding to cellular macromolecules of FAA and N-OAc-FAA using C3H10T1/2CL8 cells was investigated. C3H10T1/2CL8 cells metabolized FAA to 7-hydroxy-FAA, 2-fluorenylamine and N-hydroxy-FAA (N-OH-FAA) at rates of 5.03, 2.22 and 3.33 pmol/h/10(6) cells, respectively. N-O-Ac-FAA was bound to the DNA and RNA in C3H10T1/2CL8 cells to the extent of 10.6 and 3.6 FAA residues/10(6) nucleotides, respectively, and to protein at 21.9 pmol FAA residues/mg protein. However, binding of FAA to DNA and RNA at similar concentrations to N-OAc-FAA was less than 0.3 and 0.6 residues/10(6) nucleotides, respectively. These results strongly indicate that the inability of FAA to transform C3H10T1/2CL8 cells residues in the cells' inability to metabolize it sufficiently to the proximate carcinogen N-OH-FAA and not an inherent insensitivity to its activated forms.

2-Acetylaminofluorene↗
PubMed1982

Cellulolytic and non-cellulolytic bacteria in rat gastrointestinal tracts.

Lactobacillus and Bifidobacterium species were the predominant organisms isolated from small intestinal (jejunal) contents of rats, and lactic acid was the only organic acid detected. The numbers of cellulolytic bacteria in small intestines were low (approximately 10(3)/g). The fermentation in ceca was different from that in intestines, as, in addition to small amounts of lactic acid, high concentrations of volatile fatty acids were detected. The mixed cecal microflora was able to digest cellulose (pebble-milled Whatman no. 1) and cabbage. High numbers of cellulolytic bacteria were found (0.5 X 10(8) to 12.2 X 10(8)/g; 6% of total viable bacteria). The predominant celluloytic organism isolated was Bacteroides succinogenes. Ruminococcus flavifaciens was isolated from a few animals. The kinds and numbers of the predominant non-cellulolytic organisms isolated from rat ceca were similar to those described by previous workers.

Actinomycetaceae↗
PubMed1982

Characterization of rat cecum cellulolytic bacteria.

Cellulose-degrading bacteria previously isolated from the ceca of rats have been characterized and identified. The most commonly isolated type was rods identified as Bacteroides succinogenes. These bacteria fermented only cellulose (e.g., pebble-milled Whatman no. 1 filter paper), cellobiose, and in 43 of 47 strains, glucose, with succinic and acetic acids as the major products. The only organic growth factors found to be required by selected strains were p-aminobenzoic acid, cyanocobalamine, thiamine, and a straight-chain and a branched-chain volatile fatty acid. These vitamin requirements differ from those of rumen strains of B. succinogenes, indicating the rat strains may form a distinct subgroup within the species. The mole percent guanine plus cytosine was 45%, a value lower than those (48 to 51%) found for three rumen strains of B. succinogenes included in this study. Cellulolytic cocci were isolated less frequently than the rods and were identified as Rumminococcus flavefaciens. Most strains fermented only cellulose and cellobiose, and their major fermentation products were also succinic and acetic acids. Their required growth factors were not identified but were supplied by rumen fluid.

Animals↗
PubMed1981

Identification of cocarcinogens and their potential mechanisms of action using C3H10T 1/2 CL8 mouse embryo fibroblasts.

The cocarcinogenic action of five agents which increase microsomal mixed-function oxidase activity in vivo was examined in the C3H10T 1/2 CL8 transformation assay. The compounds studied were benz(a)anthracene, 5,6-benzoflavone, phenobarbital, pregnenolone-16 alpha-carbonitrile, and Aroclor 1254. After a 48-hr pretreatment with the agent, the cells were then treated with benzo(a)pyrene [B(a)P] and the agent for an additional 24 hr. All agents except for Aroclor 1254 increased B(a)P-mediated transformation in C3H10T 1/2 CL8 cells. Benz(a)anthracene, 5,6-benzoflavone, phenobarbital, and pregnenolone-16 alpha-carbonitrile also increased the overall metabolism of B(a)P in C3H10T 1/2 CL8 cells to 9,10-dihydro-9,10-dihydroxybenzo(a)pyrene; 7,8-dihydro-7,8-dihydroxybenzo(a)pyrene, 9-hydroxybenzo(a)pyrene, and 3-hydroxybenzo(a)pyrene. Growth studies indicated that all four agents had no stimulatory effect which might have explained the increases in transformation frequency. This suggests that these agents exert their cocarcinogenic action via increases in the enzyme-mediated pathways of B(a)P metabolism.

Animals↗
PubMed1981

A comparison of three liquid-ventilation cooling garments during treadmill exercise.

Tests were performed on five male subjects to compare the heat transfer performance and physiological effects of three different cooling garments when used under a sealed, impermeable garment which simulated a space suit. The mean exercise metabolic rate while walking at 0.9 m/s (2 mph) was 464 +/- 33 W. An equilibrium condition was never reached during the uncooled suited control runs and the subjects lost a mean of 1.12 +/- 0.15 kg (2.5 +/- 0.3 lb)--approximately 2% of body weight--during exercise. The mean weight loss was 0.35 +/- 0.10 kg (0.8 +/- 0.2 lb) with an Apollo-type garment; 0.26 +/- 0.11 kg (0.57 +/- 0.24 lb) with the full-body cooling patch (garment 2); and 0.52 +/- 0.12 kg (1.15 +/- 0.26 lb) with the partial-coverage cooling patch (garment 3). Impedance plethysmography data showed an increase in leg blood flow when the working muscles were not cooled by liquid flow (garment 3), and the arm blood flow remained unchanged whether or not there was liquid cooling to the arms.

Adult↗
PubMedDate not supplied

Survey and workshop initiative on community nurses' knowledge of the Internet.

Information technology in the nursing profession has been in existence for years, but only now with the growing presence of the Internet is it viewed as a possible platform to help meet the need for nurses' continuing educational development. For this to happen, it is important to know qualified nurses' experience with the Internet. In the United Kingdom, there is little understanding of whether community nurses have experience in using the Internet and if they do, how they use it. This article reports the findings of a survey questionnaire, taken in 1998, that was designed to target a random sample of 100 community nurses in Aberdeen, Scotland, to gauge awareness and attitudes toward the use of electronic sources of information for continuing education purposes. The response rate for the questionnaire was 83% (n = 83). A series of workshops was also undertaken, exploring the potential of the Internet and its access. A total of 52 people attended the workshops. One of the main aims of the workshops was to demystify the image of the computer, breaking down barriers for those with little or no experience in this field. The major findings of the survey and workshops indicate that although many respondents were interested in the potential benefits of the Internet to access information, there was little use made of and limited access to computer equipment.

Adult↗
PubMedDate not supplied

Neonatal outcome after active perinatal management of the very premature infant between 23 and 27 weeks' gestation.

OBJECTIVE: To record the effect of aggressive perinatal management on neonatal outcome in the very premature infant. METHODS: A retrospective chart review of 114 infants born between 23 and 27 weeks' gestation, managed by one perinatal transport service at one hospital between July 1989 and December 1993. Fetuses > 23 weeks' gestation were considered viable and were managed with tocolytics, antibiotics, and surfactant at the discretion of the treating physician. Morbidity and mortality rates in the first 6 months, including stillbirths were analyzed. A major neurologic condition was defined as ultrasonographic evidence of grade 3 or 4 intraventricular hemorrhage or periventricular leukomalacia. RESULTS: Both neonatal mortality rate and the incidence of stillbirths decreased with advancing gestational age. Of 24 infants born at 23 weeks' gestation, 33% were stillborn and 13% were alive at 6 months. This survival rate improved to 48% for infants delivered at 24 weeks' gestation, and to 68%, 75%, and 71% for those delivered at 25, 26, and 27 weeks' gestation, respectively. The percentage of infants who survived without a major neurologic condition increased with advancing gestational age at delivery from 13% at 23 weeks' gestation to 40% at 24 weeks, 48% at 25 weeks, 70% at 26 weeks, and 71% at 27 weeks. The incidence of retinitis of prematurity, respiratory complications, and days spent in the hospital decreased with greater gestational age. CONCLUSIONS: An active plan of management for all gestations of > 23.9 weeks seems appropriate.

Adolescent↗