Search PubMed⌕ Search

Biomedical subjects

C L Wells

Publications and source records attributed to C L Wells.

At least 55 records · Page 3Linked to original sources
PubMed1993

Oral infectivity and bacterial interactions with mononuclear phagocytes.

The purpose of this study was to clarify the association between the oral infectivity of a bacterial strain and its susceptibility to ingestion by mononuclear phagocytes or ability to survive within them. Ten bacterial strains tested--all of known oral infectivity--comprised Salmonella typhimurium, Listeria monocytogenes (three strains), Escherichia coli (two strains), Proteus mirabilis, Enterococcus faecalis, Bacteroides fragilis, and a Bacteroides sp. The phagocytic uptake of each strain was measured as the bacteria to phagocyte ratio after mononuclear phagocytes in mouse peritoneal exudate were permitted to ingest bacteria in vivo for 3 min. The three Listeria strains were the most susceptible to phagocytic uptake and the Salmonella strain was relatively resistant. The intracellular survival of each strain was studied during a subsequent 2 h in-vitro incubation of the mononuclear phagocytes that had been permitted to ingest bacteria in vivo. The strains with the best intracellular survival were Ent. faecalis and two of the three Listeria strains. The ability of S. typhimurium to survive intracellularly was intermediate but better than that of the two E. coli strains. Oral infectivity was not consistently correlated with susceptibility to ingestion by mononuclear phagocytes or ability to survive within them.

Animals↗
PubMed1993

High-resolution visualization by field emission scanning electron microscopy of Enterococcus faecalis surface proteins encoded by the pheromone-inducible conjugative plasmid pCF10.

Enterococcus faecalis can acquire antibiotic resistance and virulence genes by transfer of pheromone-inducible conjugative plasmids such as pCF10, which encodes tetracycline resistance. Two pCF10-encoded cell surface proteins, Sec10 and Asc10, have been previously shown to play an important role in the transfer of this plasmid. We used high-resolution, field emission scanning electron microscopy to visualize these proteins on the surfaces of a series of isogenic strains of E. faecalis. Immunogold labeling, using both 6- and 12-nm colloidal gold, unambiguously demonstrated the expression and distribution of Sec10 and Asc10 on the surface of the E. faecalis cells. On unlabeled E. faecalis cells which expressed either Sec10 or Asc10, the former appeared to be more readily detected. Immunogold labeling of E. faecalis cells expressing both Asc10 and Sec10 clearly demonstrated the abundance and intermixing of both proteins on the cell surface except at septal regions. Sec10 was observed to be distributed over the cell surface. At regions of cell-cell contact, fine strands representing Asc10 were observed directly attaching adjacent cells to one another.

Antibodies, Monoclonal↗
PubMed1993

Effect of LPS on epithelial integrity and bacterial uptake in the polarized human enterocyte-like cell line Caco-2.

Bacterial lipopolysaccharide (LPS) has been speculated to facilitate bacterial translocation by a mechanism involving physical disruption of the gut mucosal barrier. Polarized, cultured intestinal epithelial cells (Caco-2 cells) were used to study the effect of LPS on enterocyte structure, viability, and susceptibility to bacterial invasion. Varying concentrations of biologically active LPS were incubated with enterocytes for 1 and 16 hr. LPS had no noticeable effect on enterocyte viability or morphology, as measured by uptake of vital dyes, by distribution of cytoskeletal filamentous actin, and by visualization of subcellular ultrastructure. Transepithelial electrical resistance was similar in enterocyte cultures incubated with LPS for 1 hr, but there was a noticeable decrease after 16 hr, indicating a loss of epithelial integrity after prolonged exposure to LPS. The effect of LPS on bacterial uptake was studied using six strains of enteric bacteria with varying abilities to invade Caco-2 cells: Listeria monocytogenes, Salmonella typhimurium, Proteus mirabilis, Escherichia coli (2 strains), and Enterococcus faecalis. Electron microscopy showed enteric bacteria in intimate association with enterocyte apical microvilli, and internalized bacteria were consistently observed within cytoplasmic, membrane-bound vacuoles. Following a 1-hr incubation of individual strains of enteric bacteria with Caco-2 cells, numbers of viable intracellular bacteria varied significantly between individual bacterial strains, but numbers of intracellular bacteria were similar for each strain incubated with enterocytes exposed to 0, 10, and 100 micrograms LPS for 1 and 16 hr. Thus, although prolonged exposure to LPS might have some effect on enterocyte culture integrity (as measured by decreased electrical resistance), LPS had no discernible effect on enterocyte structure, viability, and susceptibility to bacterial invasion. These results suggested that LPS-induced bacterial translocation might not involve loss of epithelial viability, or facilitated entry of bacteria into intestinal epithelial cells.

Bacterial Physiological Phenomena↗
PubMed1992

Selective gut decontamination reduces nosocomial infections and length of stay but not mortality or organ failure in surgical intensive care unit patients.

Suppression of the gut luminal aerobic flora to reduce nosocomial infections was tested in a prospective, randomized, double-blind, placebo-controlled clinical trial in patients in a surgical intensive care unit who had persistent hypermetabolism. Forty-six patients were randomized to receive either norfloxacin, 500-mg suspension every 8 hours, together with nystatin, 1 million units every 6 hours, or matching placebo solutions administered through a nasogastric tube within 48 hours of surgical intensive care unit admission. Selective gut decontamination with the experimental therapy or placebo solutions continued for at least 5 days or until the time of surgical intensive care unit discharge. Patients were monitored with routine surveillance cultures for the development of nosocomial infections, as defined by criteria from the Centers for Disease Control. All other therapy was given as clinically indicated, including systemic antibiotics. The selective gut decontamination group experienced a significant reduction in the incidence of nosocomial infections and a reduced length of stay. However, these results were not associated with a concomitant decrease in progressive multiple organ failure syndrome, adult respiratory distress syndrome, or mortality.

Adult↗
PubMed1992

Aerobic power of competitive paraplegic road racers.

The purpose of this study was to determine peak aerobic power and associated physiological responses in highly competitive spinal cord injured (SCI) paraplegic road racers. Seven (6 male and one female) active paraplegic (lesions T4-T12) road racers and 9 healthy untrained able-bodied males performed continuous graded arm crank ergometer tests to exhaustion for determinations of peak power output (PO), oxygen uptake (VO2), pulmonary ventilation (VE), heart rate (HR), and respiratory exchange ratio (RER). Compared to able-bodied subjects, male paraplegic road racers elicited significantly (p less than or equal to .05) higher mean (+/- SD) peak levels of PO (141.6 +/- 8.8 vs 111.4 +/- 27.7 W), absolute VO2 (2.72 +/- .52 vs 2.22 +/- .381/min), and VO2 per unit of body weight (43.06 +/- 7.4 vs 30.33 +/- 4.3 ml/kg/min). Although peak HR (180.3 +/- 9.5 vs 173.2 +/- 8.5 bpm) and VE (92.8 +/- 17.2 vs 74.6 +/- 20.3 l/min) tended to be higher for male paraplegic road racers than able-bodied subjects, the differences were not statistically significant. The female paraplegic road racer achieved the highest peak levels of PO (119 W) and VO2 (1.99 l/min; 38.0 ml/kg/min) reported to date for wheelchair-dependent women. These data suggest that intense physical training via wheelchair propulsion can markedly enhance upper body cardiovascular fitness in SCI paraplegics. However, the correlational analysis between 10 km time and peak VO2 was nonsignificant (p greater than .05) indicating that factors other than peak upper body aerobic power may influence wheelchair road racing performance.

Adult↗
PubMed1992

Effect of age and menopausal status on cardiorespiratory fitness in masters women runners.

Forty-nine trained masters women endurance runners (mean = 42 km.wk-1) between the ages of 35 and 70 yr (mean = 46.4 +/- 8.3) were tested on a treadmill to examine cardiorespiratory fitness (VO2max and VO2 submax) in relation to age, training, and menopausal status. Although VO2max was lower with increasing age, no age group differences occurred in VO2 submax at 5.4 km.h-1, 8% treadmill grade. The younger runners (35-39 and 40-44 yr) had significantly higher VO2max than the other 5-yr competitive age groups (45-49, 50-55, 55-70 yr) (P < 0.01). HR max did not differ across age, but HR submax was higher with increasing age. Premenopausal, transitional, and post-menopausal women were not significantly different on any exercise variable when age and/or training differences among the groups were statistically controlled. A decrease in VO2max of 0.58 ml.kg-1 x min-1 x yr-1 was determined (r = -0.62). It was concluded that 1) these highly trained women runners had higher cardiorespiratory fitness than previously reported for women of comparable age, 2) menopausal status did not effect cardiorespiratory fitness when age and training were accounted for, and 3) regular physical training seems to prevent age-related changes in HR max in women, but not age-related changes in maximal oxygen uptake.

Adult↗
PubMed1992

Intestinal bacterial flora, intestinal pathology, and lipopolysaccharide-induced translocation of intestinal bacteria.

The primary aim of this study was to clarify the mechanism and significance of lipopolysaccharide (LPS)-induced translocation of intestinal bacteria. Female Swiss Webster mice were purchased from two different animal suppliers. Twenty-four hours following parenteral LPS, mice from both suppliers had noticeable morbidity and mortality. However, intestinal pathology, gram-negative bacterial overgrowth, and increased bacterial translocation was noted in mice purchased from one supplier but not the other. Mice with increased translocation also had overgrowth of cecal gram-negative bacilli, i.e., 10(10) per gram of cecum following parenteral LPS; in contrast, mice without LPS-induced bacterial translocation had 1,000- to 10,000-fold fewer cecal gram-negative bacilli. Additional groups of mice with increased bacterial translocation were also sacrificed two and 6 hr after parenteral LPS; morbidity and intestinal pathology were evident without a corresponding increase in bacterial translocation. Separate groups of these mice were also injected with platelet activating factor, resulting in intestinal pathology similar to that noted with parenteral LPS, but no increase in bacterial translocation. Thus parenteral LPS was consistently associated with morbidity and mortality but not with intestinal pathology, enteric bacterial overgrowth, or increased bacterial translocation.

Animals↗
PubMed1991

Relative contributions of host and microbial factors in bacterial translocation.

To study the relative contributions of host and microbial factors in bacterial translocation, germfree mice were mono-associated with either Proteus mirabilis, Escherichia coli, or Enterococcus faecalis. Germfree mice included T-cell-deficient nude mice and normal littermates, natural killer cell-deficient beige mice and normal littermates, and triply immunodeficient mice with beige, T-cell, and B-cell mutations and their littermates. Each bacterial species colonized the cecum in similarly high numbers. Bacteria were recovered from the mesenteric lymph node of every mouse in inconsistent numbers, eg, greater numbers of P mirabilis and E coli were recovered from T-cell-deficient nude mice than from their normal littermates, but the opposite was observed with E faecalis. Comparing the three bacterial species resulted in relatively consistent observations, eg, the incidence of E faecalis translocation to the liver was greater than that of E coli or P mirabilis translocation. Thus, the identity of the translocating microbe significantly affected the recovery of viable translocating bacteria.

Animals↗
PubMed1991

Dietary omega-3 fatty acids decrease mortality and Kupffer cell prostaglandin E2 production in a rat model of chronic sepsis.

We tested the hypothesis that substitution of omega-3 fat for dietary omega-6 fat would reduce mortality and decrease Kupffer cell prostaglandin E2 (PGE2) production in a rat model of chronic sepsis. Rats were fed via gastrostomy for 12 days with isonitrogenous, isocaloric diets containing 15% of calories as either safflower oil (omega-6) or a 10:1 mixture of menhaden oil (omega-3) and safflower oil. After five days of feeding, animals received an intra-abdominal abscess of defined bacterial content. Survivors were killed on post-laparotomy day 6 in conjunction with liver perfusion and protease liver digestion for Kupffer cell isolation. Kupffer cell PGE2 production was measured by radioimmunoassay after 18 hours of cell culture and again after stimulation with 0 LPS, 10 ng/ml LPS, and 10 micrograms/LPS. Mortality was decreased in menhaden oil-fed animals compared with safflower oil-fed animals (16% vs. 35%). Kupffer cell PGE2 production was decreased in menhaden oil-fed animals at 18 hours (354 +/- 54 vs. 570 +/- 95 pg/0.1 ml; p = 0.09) and after stimulation with 10 micrograms/ml LPS (140 +/- 41 vs. 288 +/- 45 pg/0.1 ml; p = 0.03) compared with safflower oil-fed animals.

Animals↗
PubMed1991

Localization of translocating Escherichia coli, Proteus mirabilis, and Enterococcus faecalis within cecal and colonic tissues of monoassociated mice.

Normal bacteria can translocate (migrate) across an intact intestinal mucosa, but the anatomical site of bacterial translocation has not been defined. Gastrointestinal (GI) cross-sections were obtained from mice monoassociated with high cecal concentrations of Escherichia coli, Proteus mirabilis, or Enterococcus faecalis. As previously reported (C. L. Wells, R. P. Jechorek, and K. J. Gillingham, Arch. Surg. 126:247-252, 1991), these mice had viable translocating bacteria recovered from mesenteric lymph nodes and livers. No abnormal GI histology was noted. Immunofluorescence was used to localize GI bacteria, and similar observations were made with each of the three bacterial species. Smaller numbers (P less than 0.01) of bacteria were observed in stomach and small intestinal tissues than in cecal and colonic tissues, suggesting that the preferred site of tissue penetration for intestinal E. coli, P. mirabilis, and E. faecalis might be the cecum or colon as opposed to the stomach or small intestine.

Animals↗
PubMed1991

Effects of physical exercise on pregnancy outcomes: a meta-analytic review.

In this study, using meta-analysis the findings of all individual reports on the effects of exercise training on pregnancy outcomes were pooled to determine the effects of such training on the pregnant woman and her fetus. Meta-analysis is a statistical technique used to summarize the results of experimental studies that address a common problem. Results show that women who exercised during their pregnancies did not differ from sedentary women for any of the outcome variables measured: maternal weight gain (P = 0.07), infant birth weight (P = 0.20), length of gestation (P = 0.67), length of labor (P = 0.14), and APGAR scores (P = 0.59). Many of the exercise programs exceeded, without apparent adverse effects, the recommended limitations set by the American College of Obstetricians and Gynecologists. Overall, an exercise program using any of a variety of exercise modes that is performed for an average of 43 min.d-1, 3 times.wk-1, at a heart rate of up to 144 bpm, does not appear to be associated with adverse effects to the mother or fetus in a healthy normal pregnancy. However, these findings should be cautiously applied owing to the nature of the currently available data base. Recommendations or precautions for programs of greater intensities can not be made at this time.

Adult↗
PubMed1991

Body composition and sexual maturation in premenarcheal athletes and nonathletes.

The purpose of this study was to compare premenarcheal athletes (A) and nonathletes (NA) in terms of body composition and sexual maturation and to discern the relationship between these variables. Percent body fat (%BF) was determined by the three-component system of Siri utilizing body density from hydrostatic weighing and total body water measured by deuterium oxide dilution. Sexual maturation was self-assessed using the system described by Marshall and Tanner. ANOVAs and polynomial regression analysis revealed that both the A (N = 73) and NA (N = 53) showed similar values and linear increases (P less than 0.001) in height (HT), weight (WT), breast (B) and pubic hair (PH) development from 7 to 15 yr but not in %BF (XA = 15.7 +/- 4.6; XNA = 20.5 +/- 6.4 (P less than 0.001]. The NA exhibited a quadratic curve (P less than 0.01) in %BF over age, while the A showed a negative linear relationship (P less than 0.001) with age. Scheffe post hoc tests revealed significant differences (P less than 0.03, A less than NA) at 11 and 12-15 yr. When %BF was compared to maturation, the A were found to have less fat (P less than 0.01) at stages 1 and 4 of PH and at stages 2, 3, and 4 of B. There were no significant differences between A and NA in the age at which B2, 3, or 4 or PH2, 3, or 4 occurred. Both groups exhibited similar and significant correlations between age, HT, WT, B, and PH development but not %BF.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Effect of immersion on residual volume of able-bodied and spinal cord injured males.

This study compared residual lung volumes (RV) (oxygen dilution technique) of able-bodied (AB) and spinal cord injured (SCI) males on dry land in air (RVA) and immersed to the neck in water (RVW). The effects of significant differences in RV on calculations of body density (Db) and percent body fat (%BF) were also assessed. The subjects were eight AB, eight paraplegic (PARA), and eight quadriplegic (QUAD) males, ranging in age from 18 to 51 yr. There was a 0.99 correlation (P less than 0.001) between RVA and RVW for AB subjects but no significant correlations between RVA and RVW for the PARA or QUAD groups. RVA in the QUAD group was significantly higher than in the PARA or AB group (P less than 0.003). There were no differences in RVW among the three groups. In the QUAD group, RVA was significantly larger than RVW (P less than 0.001), but there were no significant differences between RVA and RVW for the PARA or AB subjects. Db and %BF did not differ significantly among the PARA or AB groups when calculated at RVA and RVW. However, for QUAD, both Db and %BF differed significantly (P less than 0.001) when calculated at RVA and RVW. It was concluded that, for the purpose of hydrostatic weighing, residual lung volume of quadriplegic persons should be measured with the subject immersed in water.

Adipose Tissue↗
PubMed1990

Oxygen as an antibiotic. The effect of inspired oxygen on bacterial clearance.

Previous experimentation with the guinea pig skin injection model showed that altering the fraction of inspired oxygen had a significant effect on infectious necrosis. Using the same model, we performed quantitative bacterial cultures to determine the number of viable injected bacteria 24 and 48 hours after injection. Animals were randomized to receive 12%, 21%, and 45% inspired oxygen. A significant decrease in bacterial number was seen at 45% inspired oxygen between 24 and 48 hours, and a significant decrease occurred at 48 hours between 12% and 45% inspired oxygen. These results demonstrated a prominent role for oxygen in bacterial clearance and host defense.

Administration, Inhalation↗
PubMed1990

Relationship between intestinal microecology and the translocation of intestinal bacteria.

It is now well known that endogenous bacteria can translocate from the intestinal tract and cause many of the complicating infections seen in severely ill, hospitalized patients. Of the hundreds of bacterial species in the intestinal tract, relatively few aerobic/facultative species appear to translocate with any frequency. Van der Waaij and colleagues (1971, 1972a, 1972b) originally proposed that, by a process termed 'colonization resistance', strictly anaerobic bacteria prevented the intestinal overgrowth and subsequent translocation of these potentially pathogenic aerobic/facultative bacteria. Selective antimicrobial decontamination, designed to maintain colonization resistance, has been effective in reducing the incidence of infectious morbidity in high risk patients. However, the mechanisms controlling bacterial translocation remain unclear, but appear to depend on host factors, as well as on factors inherent in the microbe itself. There is both clinical and experimental evidence supporting the concept that strictly anaerobic bacteria do not readily translocate. Bacteria that are able to survive within macrophages (e.g., Salmonella species and Listeria monocytogenes) translocate easier than others, and there is recent experimental evidence that normal intestinal bacteria may translocate to the draining mesenteric lymph node within host phagocytes. There is also evidence that anaerobic bacteria translocate along with facultative species in situations associated with intestinal epithelial damage, i.e., burn trauma, oral ricinoleic acid, and acute mesenteric ischemia. In contrast, recent experimental evidence demonstrates that facultative bacteria can translocate across a histologically intact intestinal epithelium, and that the ileal absorptive cell may be at least one portal of entry prior to transport into deeper tissues. It is anticipated that further clarification of the routes and mechanisms involved in bacterial translocation will provide new insights into the treatment and prevention of a significant proportion of the infectious morbidity seen in severely ill, hospitalized patients.

Animals↗
PubMed1990

Physiologic responses of elite paraplegic road racers to prolonged exercise.

The purpose of this study was to determine cardiopulmonary and selected metabolic responses in spinal cord injured (SCI) paraplegics during prolonged arm crank exercise (ACE). Six male and one female elite SCI paraplegic (T4-12 lesions) road racers performed 40 continuous minutes of ACE at 60% of peak ACE oxygen uptake (VO2). Blood samples (30 ml) were collected via antecubital venipuncture at rest and minutes 20 and 40 of ACE for determinations of hemoglobin, hematocrit, serum free fatty acid (FFA), and blood lactate (LA) concentrations. No significant differences were observed over time for VO2 or pulmonary ventilation. Heart rate recorded at minutes 30 and 40 was significantly elevated above HR at minutes 10 and 20 of ACE indicating the presence of an upward drift in HR in paraplegics performing prolonged ACE. Compared to rest, LA concentration was significantly higher at minute 20 and remained relatively stable thereafter. A significant increase in FFA concentration at minute 40 combined with a significant decline in the respiratory exchange ratio suggested a preference for lipid substrate utilization by exercising muscle as ACE continued. The data indicate that the autonomic sympathetic nervous system impairment associated with paraplegia had no apparent adverse effects on cardiopulmonary or metabolic adjustments to prolonged ACE in these well-trained subjects.

Adult↗
PubMed1990

Evidence for the translocation of Enterococcus faecalis across the mouse intestinal tract.

The pathogenesis of Enterococcus (Streptococcus) faecalis was studied in mice with E. faecalis intestinal overgrowth (10(9) - 10(10) per gram of cecum) induced by metronidazol and streptomycin treatment coupled with oral inoculation of E. faecalis. E. faecalis was recovered from the mesenteric lymph nodes, liver, and spleen; mortality was noted in 8 (13%) of 62 mice after 14 days of E. faecalis intestinal overgrowth. Light, immunofluorescent, and electron (scanning and transmission) microscopy of ileal tissue was used in an attempt to localize E. faecalis translocating across intestinal tissue. Dense coccal bacteria were observed in the intestinal lumen, and the epithelium appeared intact. Coccal bacteria were observed adherent to the microvillus border of the entire villous epithelium, including the deeper regions of the intestinal crypts. Immunofluorescence localized E. faecalis within columnar epithelial cells, lamina propria, submucosa, and muscularis externa (including the lumen of small vessels). Transmission electron microscopy localized coccal bacteria within vacuoles in the cytoplasm of intact epithelial cells. These results indicated that E. faecalis could translocate across an intact intestinal tract and cause systemic infection and death. In this model, the intestinal epithelial cell appeared to be a portal of entry in the pathogenesis of systemic E. faecalis infection.

Animals↗