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Biomedical subjects

L M Pope

Publications and source records attributed to L M Pope.

At least 19 recordsLinked to original sources
PubMed2001

Postabortion psychological adjustment: are minors at increased risk?

PURPOSE: To assess whether younger adolescents experience greater adverse psychological outcomes after abortion than those aged 18-21 years, whether abortion places all adolescents at risk for negative sequelae, and what factors predict negative outcomes. METHODS: A total of 96 young women aged 14-21 years seeking counseling for unwanted pregnancies at four clinics completed questionnaires after counseling. These included the Beck Depression Inventory (BDI), an emotion scale, questions regarding sociodemographic and reproductive background, feelings about pregnancy, and decision-making. Sixty-three respondents were reinterviewed 4 weeks postabortion and completed the BDI, emotion scale, Spielberger State Anxiety Inventory, Rosenberg Self-esteem Scale, Impact of Events Scale, and Positive States of Mind Scale. Chi-squares and Student's t-tests were used to compare: (a) responses of adolescents under 18 years of age with those 18-21 years, (b) preabortion and postabortion responses, and (c) the current sample with other samples of adolescents. RESULTS: Adolescents under age 18 years were less comfortable with their decision, but showed no other differences compared with those aged 18-21 years. Both groups showed significant improvement in psychological responses postabortion. Postabortion scores did not differ significantly from those of other adolescent samples reported in the literature. Preabortion emotional state and perception of partner pressure predicted postabortion response. CONCLUSIONS: Despite its legal significance, age 18 years was not a meaningful cutoff point for psychological response to abortion in this sample. There was no evidence that abortion poses a threat to adolescents' psychological well-being.

Abortion, Legal↗
PubMed1995

Increased protein secretion and adherence to HeLa cells by Shigella spp. following growth in the presence of bile salts.

Growth of Shigella spp. in the presence of the bile salt deoxycholate or chenodeoxycholate enhanced the bacterial invasion of HeLa cells. Growth in the presence of other structurally similar bile salts or detergents had little or no effect. Deoxycholate-enhanced invasion was not observed when bacteria were exposed to deoxycholate at low temperatures or when chloramphenicol was added to the growth medium, indicating that bacterial growth and protein synthesis are required. Increased invasion is associated with the presence of an intact Shigella virulence plasmid and is correlated with increased secretion of a set of proteins, including the Ipa proteins, to the outer membrane and into the growth medium. The increased invasion induced by the bile salts appears to be due to increased adherence. The enhanced adherence was specific to Shigella spp., since the enteroinvasive Escherichia coli strains tested did not exhibit the effect in response to growth in bile salts.

Adhesins, Bacterial↗
PubMed1989

Gastrointestinal and systemic candidosis in immunocompromised mice.

Oral-intragastric inoculation of 6-day-old outbred Crl:CFW(SW) BR mice with Candida albicans can lead to colonization of the gastrointestinal (GI) tract. We have shown that in the absence of an immunocompromising treatment, Candida is primarily localized in the stomach and intestines of mice at 20 days post-inoculation. Cultures of homogenates of the esophagus of most animals tested, and homogenates of the liver, lungs, spleen and kidneys of all animals tested, proved negative for C. albicans. Previous histological examinations of the GI tract of these colonized, non-immunocompromised mice showed hyphal elements associated with the stratified, squamous epithelium of the stomach in the region of the cardial-atrium fold. In this study, mice were immunocompromised by intraperitoneal injection of cyclophosphamide and cortisone acetate 11-14 days after oral-intragastric challenge with C. albicans and then sacrificed 20 days post-challenge. A high density of invasive hyphae was observed in the same, cardial-atrium region of the stomach of these animals. Cultures of the homogenized stomach showed a 100-fold increase in colony forming units (c.f.u.) of C. albicans compared with stomach homogenates of infected but non-immunocompromised controls. In addition, homogenates of the esophagus and selected body organs of most immunocompromised mice examined were positive for C. albicans by plate culture. When the immunocompromising drug treatment was delayed 3-5 weeks after oral-intragastric challenge, proliferation of C. albicans in the stomach and intestines was still evident, although fewer mice showed systemic spread and lower numbers of c.f.u. were recovered from body organ homogenates. Abscesses which contained both C. albicans hyphae and yeast cells were frequently observed in the liver and occasionally in the lungs and kidneys of immunocompromised mice sacrificed 20 days post-inoculation. The frequent occurrence of abscesses in the liver simulates a clinical variant of this mycosis, referred to as focal hepatic candidosis, which has been recognized with increasing frequency in immunocompromised patients. We suggest that the animal model described here may be particularly useful both for exploring methods which may prevent dissemination of C. albicans from localized foci of colonization in the GI tract after exposure of the host to immunocompromising drugs, and for testing the efficacy of anti-Candida drugs in clearance of the pathogen from body organs with established fungal abscesses.

Abscess↗
PubMed1988

Morphological aspects of gastrointestinal tract invasion by Candida albicans in the infant mouse.

The infant mouse has proved to be a useful model for examination of various aspects of gastrointestinal and systemic candidosis. Oral-intragastric inoculation of 5-6-day-old mice with yeast of a virulent strain of Candida albicans (CA30) resulted in systemic spread within 30 min after challenge. Histological examinations of the gastrointestinal (GI) tract have shown that the highest frequency of invasion of the mucosa by yeast cells occurred in the region of the jejunum 1-3 h after inoculation. Results of ultrastructural examinations of sites where the fungus invaded the bowel wall suggested that C. albicans yeast cells are capable of progressive extracellular digestion of the intestinal mucus barrier and microvillus layer, followed by intracellular invasion of columnar epithelial cells. Minimal disruption of cytoplasmic contents of the host epithelial cells appears to result from invasion and transmigration of the pathogen. The infant mouse model is suggested to be well suited for localization of extracellular products of C. albicans yeast in vivo which may play pivotal roles in the invasion of host tissue during GI candidosis.

Animals↗
PubMed1982

Comparative studies of gastrointestinal colonization and systemic spread by Candida albicans and nonlethal yeast in the infant mouse.

Studies of host-parasite interactions involved in gastrointestinal and systemic candidosis have been hampered by the lack of suitable animal models which mimic the disease in humans. The infant mouse has proved to be a realistic and useful model for studies of candidosis. Oral-intragastric inoculation of infants leads to systemic spread and lethality without use of compromising procedures. Not all species or strains of Candida inoculated via this route are lethal to the infant mouse nor do they demonstrate the same degree of persistence. Certain strains of C. albicans display long term colonization of the GI tract and such persistently infected mice resemble the situation in humans with C. albicans as a common, but quantitatively minor, component of the flora of the alimentary tract. The infant mouse model thereby has the potential of providing an excellent tool for experimental modification of the GI flora which reflects the situation in debilitated and compromised humans that leads to alterations of the host-pathogen balance favoring development of candidosis. This paper provides additional evidence for the validity of the infant mouse model for investigations of gastrointestinal and systemic candidosis by comparing colonization and systemic spread of two strains of C. albicans (Ca 30 and NS 33), C. guilliermondii, Saccharyomyces cerevisiae and latex beads.

Animals↗
PubMed1981

Persistence and spread of Candida albicans after intragastric inoculation of infant mice.

Infant mice have been shown previously to be a useful model for the study of gastrointestinal (GI) and systemic candidosis. In this study, the virulence of four strains of Candida albicans was compared in intragastrically inoculated infants and in adult mice inoculated intravenously. The four strains differed in their ability to kill both infant and adult mice. A smaller inoculum was required to kill adult mice inoculated intravenously. Neonates could not be inoculated intravenously. The ability of the strains to spread systemically from and to persist for long periods of time in the digestive tract was also examined in intragastrically inoculated infants. The yeast cells spread to liver, lungs, kidneys, and spleen within 30 min postinoculation. Yeast were not detectable in the lungs or in blood from the pleural cavity up to 15 min post-inoculation, thus making it unlikely that systemic spread resulted from faulty inoculation or from aspiration. The region where C. albicans crossed the GI tract of infant mice was visualized histologically in the upper third of the small intestine. The four strains varied in their ability to persist for long periods in the GI tract, in the rate at which they appeared systemically, and in ability to kill infant mice. Three of the four strains colonized the gut for up to 10 weeks postinoculation without use of any compromising agents.

Animals↗
PubMed1981

Intestinal colonization of neonatal animals by Campylobacter fetus subsp. jejuni.

Neonatal mice (2.3 to 2.8 g) were inoculated intragastrically with different human isolates of Campylobacter fetus subsp. jejuni. At weekly intervals thereafter, mice were sacrificed and dilution plate counts were performed on segments of the gastrointestinal tract. Mice were uniformly colonized by some strains for 2 weeks, whereas other strains were being cleared at that time. One strain (BO216) persisted in some mice for 3 weeks. The greatest number of organisms (10(7)) was recovered from the cecum and large intestine. The small intestine had from 10(2) to 10(5) colony-forming units. Colonization of the stomach was not found consistently. One strain killed 13% of the infected mice. Deaths occurred between 1 and 5 days postinfection. Two other strains killed a smaller percentage of challenged animals, and two additional strains killed none. Retarded weight gain was noticed in some, but not all, of the infected mice. The intestines of neonatal rats and rabbits were colonized much the same as those of mice, whereas hamsters were resistant to colonization. Preweanling mice, up to about 6.5 to 7.0 g, could be colonized with C. fetus subsp. jejuni after intragastric challenge, but weanling mice of larger weight (9.8 g) and young adult mice (18.3 g) could not. Scanning electron photomicrographs of the lower ileum showed campylobacters in and below the dried mucous gel that lines the intestines. The use of this model for additional studies is discussed.

Animals↗
PubMed1981

SEM studies of adherence of candida albicans to the gastrointestinal tract of infant mice.

In our earlier investigations it has been shown that the gastrointestinal (GI) tract of the infant mouse (4-5 days old) can be colonized following a single intragastric challenge with Candida albicans. This makes it possible to investigate the sequence of events which occur during colonization of the GI tract by this opportunistic yeast. Two strains of C. albicans, CA 30 and NS 33, which were shown in earlier studies to differ markedly in their ability to persist in the GI tract were examined. The SEM was used to reveal the location of the yeast and their structural association with the surface of tissues of the gut at early times after intragastric inoculation. Animals were sacrificed after challenge, the GI tract was removed from each mouse and subdivided into the stomach, upper intestine, mid-intestine, ileum, cecum and large bowel. The number of colony forming units was determined by homogenizing these segments and plating them out on sabouraud's dextrose agar. The microenvironment of each segment was preserved by freezing samples in liquid nitrogen prior to processing for the SEM. The distribution and level of counts of the strains studied in the GI tract were comparable during the three week period. Both strains of C. albicans associated with the secreting epithelium and the keratinized epithelium of the stomach. Yeast also associated with the mucus layer and the epithelial surface throughout the GI tract. Those yeast adhering to the epithelial surfaces of the GI tract were frequently covered by a layer of mucus which may aid in colonization.

Animals↗
PubMed1979

Age-dependent changes in the rate of myofibrillar protein degradation in humans as assessed by 3-methylhistidine and creatinine excretion.

1. Urinary excretion of 3-methylhistidine and creatinine have been measured in normal male and female humans ranging in age from pre-term neonates to 68 years to assess changes in the rate of muscle protein degradation and in muscle mass. 2. The 3-methylhistidine excretion by six adult men was measured before and after subjects were transferred to meat-free diets. It was established that a meat-free diet should be eaten for a minimum of 3 days before urine collection to eliminate exogenous sources of 3-methylhistidine. 3. The 3-methylhistidine/creatinine excretion ratio declined about twofold between normal full-term birth and maturity. The ratio in pre-term neonates was higher than for full-term neonates. 4. The variability of 3-methylhistidine/creatinine ratios between individual untime urine samples within a subject is similar to the variability between different subjects with total daily collections. 5. The 3-methylhistidine content of human muscle averaged 3.63 +/- 0.06 micromol/g for subjects aged between 4 and 65 years with protein accounting for 20.4 +/- 0.8% of muscle weight. These values are used to relate 3-methylhistidine excretion to muscle protein degradation. 6. It is concluded that control groups must be matched by age and sex to the group being examined. Where creatinine excretion is not perturbed it can be used as a reference base for comparisons of 3-methylhistidine excretion to indicate the average fractional degradation rates of muscle protein.

Adolescent↗
PubMed1979

Muscle protein degradation in premature human infants.

1. Myofibrillar protein degradation has been measured by the rate of 3-methylhistidine excretion in premature infants weighing between 635 g and 1295 g. Analyses were made in conjunction with 1--3 day nitrogen balance studies. 2. In 56 balance studies in 36 infants, total muscle protein breakdown varied between 0.70 and 2.58 (mean 1.05) g day-1 kg-1 body weight while the percentage of total muscle protein degraded each day was between 3.3 and 8.3 (mean 4.8). 3. Both total and fractional rates of protein breakdown showed highly significant negative correlations with nitrogen retention but no relationship to total energy input. 4. Protein degradation was higher than average in infants who were losing weight at the time of the balance study, lower in infants who were gaining weight and higher in those who died within 2 weeks of the analysis. 5. Myofibrillar protein breakdown was not different between infants fed orally and those receiving total parenteral nutrition. 6. Generally the effects of nitrogen and evergy status on muscle protein degradation in the premature infants are different from changes reported in adult human beings or adult rats. We suggest that this difference may be a consequence of the very limited energy reserves of the premature infant.

Aging↗
PubMed1979

Systemic and gastrointestinal candidiasis of infant mice after intragastric challenge.

Systemic and gastrointestinal infection can be established in infant mice after intragastric challenge with Candida albicans. Differences in virulence of the six strains tested were noted. As early as 3 h after infection, some but not all livers, spleens, and kidneys contained C. albicans, but the peak number of colony-forming units in these organs was seen at 6 h. The early colonization of the organs could not be attributed to aspiration of the inoculum since about 90% of lungs and livers tested yielded no colony-forming units at 10 to 15 min postinfection. In animals with systemic infections, lungs, livers, kidneys, and spleens showed similar numbers of colony-forming units within the organs during the first 6 h postinfection- and then the number declined progressively up to 72 h. The gastrointestinal tract was colonized throughout a 20-day period of study. Counts made at intervals beyond day 1 yielded between 10(5) and 10(6) colony-forming units in the stomach, ileum, and cecum. Preparatory techniques for scanning electron microscopy preserved the yeast, intestinal mucus layer, and epithelial surface and made it possible to visualize the association between the pathogen and host tissues within the digestive tract.

Administration, Oral↗
PubMed1970

Outer layers of the Azotobacter vinelandii cyst.

Ruthenium red stained a capsule external to the exine of the Azotobacter cyst. The central body is therefore surrounded by three layers, the intine, the exine, and the capsule, all containing acid mucopolysaccharide. Vesicles that appear to originate from the contracting cell membrane of the central body may account for the lipid content of the intine. The exine is composed of laminated sheets that tend to fragment into hexagonal pieces.

Azotobacter↗
PubMed1969

Endogenous encystment of Azotobacter vinelandii.

When young cells of Azotobacter vinelandii are impinged on membrane filters, washed free of carbon substrate, and placed on a mineral salts basal medium, the culture will proceed to encyst although at a slower rate than if n-butanol were supplied as a substrate. The endogenous cysts are depleted in polybeta-hydroxybutyrate and have a narrower intine but show an increased resistance to desiccation and are susceptible to lysis by chelating agents. Membrane-supported cells reveal details of the encystment process such as the formation of a zone within the capsule prior to exine formation and the early deposition of exine structures.

Azotobacter↗
PubMed1969

Electron microscopy and viability of lysostaphin-induced staphylococcal spheroplasts, protoplast-like bodies, and protoplasts.

The cell walls of a selected isolate of Staphylococcus aureus FDA 209P were observed undergoing progressive disintegration when exposed to lysostaphin (1 unit/ml) in 24% NaCl solution. Electron micrographs of ultrathin sections of test cells after exposure to lysostaphin for 2 min showed only superficial evidence of lytic damage. However, an average of 89% of these cells were osmotically fragile, and 21% were damaged beyond their capacity to regenerate cell walls and to grow as normal staphylococci. The 68% (average) of the osmotically fragile cells which retained the capacity to revert to normal staphylococci were designated spheroplasts. Neither perforations of the cell walls nor separation of the cell walls from the plasma membranes were observed in the micrographs of these 2-min spheroplasts. Thus, it appears that the osmotic fragility of these and possibly all lysostaphin-induced staphylococcal spheroplasts results from the hydrolysis of a critical number of the pentapeptide cross-linkages of the murein of the cell wall. Electron micrographs of cells exposed to lysostaphin for 5 to 10 min showed perforations and more extensive damage, including the separation of walls from the plasma membranes and the disintegration of large sections of the walls. Smaller numbers of spheroplasts (21 and 8%) were recovered from these 5- and 10-min preparations; those recovered probably represent cells which were attacked more slowly than the majority by the lytic enzyme. The nonrevertible, osmotically fragile cells that retained segments of cell wall were designated protoplast-like bodies. After 20-min exposure to lysostaphin, all of the cell wall was digested away from most of the cells, and true staphylococcal protoplasts were produced. These lysostaphin-induced, osmotically fragile forms appear to have different osmotic properties from the staphylococcal "protoplasts" reported by other investigators and should serve as the basis for a variety of fundamental investigations.

Anti-Bacterial Agents↗
PubMed1969

Ultrastructure of Nitrobacter agilis grown under autotrophic and heterotrophic conditions.

Nitrobacter agilis, grown through seven transfers heterotrophically in the absence of nitrite, was examined in the electron microscope. The ultrastructure of such cells closely resembled that of autotrophically grown N. agilis. It was thus futher established that the organisms growing heterotrophically were indeed N. agilis and, therefore, that N. agilis is a facultative autotroph. Acetate incorporation into poly-beta-hydroxybutyrate was confirmed cytologically.

Acetates↗