Search

This study evaluated responses of the systemic endocrine stress (cortisol) and growth (IGF-I, GH) axes, as well as those of inflammatory mediators (prostaglandin [E.sub.2] [[PGE.sub.2]] and tumor necrosis factor [Alpha] [TNF[Alpha]]), to active infection with Salmonella typhimurium. Eighteen crossbred barrows were penned individually with ad libitum access to feed and water. After an acclimation period, jugular catheters were placed in all animals. Control pigs received sterile broth orally (CON, n = 7), whereas the treated pigs (S.TYP, n = 11) received 3 x [10.sup.9] cfu of S. typhimurium orally. Plasma was collected at 6-h intervals from -48 to 120 h. Body weights, feed intake, and rectal temperatures also were monitored. Rectal temperatures were elevated in S.TYP pigs (P [is less than] .01) relative to CON pigs by 12 h, peaked at 42 h (P [is less than] .001), and remained elevated throughout the remainder of the study. Feed intake was reduced maximally in S.TYP pigs at 48 h (P [is less than] .001) and remained reduced through 120 h after the challenge. Daily body weight gain also was reduced during the 2 wk following infection (P [is less than] .001). Plasma cortisol concentrations increased (P [is less than] .05) at 18 h after the challenge in S.TYP pigs and remained elevated generally until 60 h after infection. A marked suppression of plasma IGF-I occurred in S.TYP pigs beginning at 30 h after infection (P [is less than] .001), and it remained lower through 108 h. Plasma GH was not affected consistently by treatment, nor did infection alter plasma TNF[Alpha] and [PGE.sub.2]. Taken together, the results reveal that infectious processes produce profound alterations in the endocrine stress and the somatotropic axis, and this may occur in the absence of significant changes in systemic proinflammatory mediators. Key Words: Diseases, Hydrocortisone, Insulin-like Growth Factor, Pigs, Prostaglandins, Tumor Necrosis Factor

The objective of this research was to provide an integrated look at systemic adrenal, somatotropic, and immune responses of growing pigs to challenge with lipopolysaccharide (LPS). Weaned pigs were challenged intraperitoneally with 100 [micro]g/kg BW of LPS or sterile saline, and rectal temperature and blood data were collected for 72 h. Daily feed intake also was monitored. Plasma was analyzed for concentrations of cortisol, tumor necrosis factor [Alpha] (TNF[Alpha]), the acute phase protein haptoglobin, growth hormone (GH), insulin-like growth factor I (IGF-I), and prostaglandin [E.sub.2] ([PGE.sub.2]). As expected, LPS decreased feed intake, stimulated a febrile response, and activated the hypothalamic-pituitary-adrenal (HPA) axis as demonstrated by increased cortisol levels. Cortisol reached maximum elevation 2 h after treatment (P [is less than] .001) and remained elevated through 12 h (P [is less than] .001). Circulating TNF[Alpha] was increased by LPS at 2 and 4 h after treatment (P [is less than] .001), and an apparent (not statistically significant) increase in haptoglobin also occurred in challenged animals. The LPS injection suppressed IGF-I by 2 h following treatment (P [is less than] .01), and circulating IGF-I remained reduced relative to controls through 44 h. Overall, GH was increased in LPS-treated pigs (P [is less than] .05), although the treatment x time interaction was not significant. Plasma [PGE.sub.2] was increased transiently at 2 h (P [is less than] .05) and then subsequently suppressed at 4, 8, and 12 h following LPS (P [is less than] .05). This study provides a comprehensive view of systemic effects of LPS on components of the HPA, growth, and immune axes. In addition, these are the first data to document changes in circulating [PGE.sub.2] in unrestrained animals during the early hours of the acute phase response to LPS. Key Words: Disease Models, Hydrocortisone, Insulin-like Growth Factor, Pigs, Prostaglandins, Tumor Necrosis Factor

Auditory and olfactory abilities of settlement-stage larvae of the coral trout Plectropomus leopardus (Pisces: Serranidae) were tested electrophysiologically to determine if these senses are sufficiently developed to aid larvae in detection of settlement habitats on coral reefs. Plectropomus leopardus larvae detected sounds from 100 to 2000 Hz with hearing most sensitive at the frequencies of 100, 200 and 600 Hz. The olfactory response of P. leopardus was similar for the two amino acids tested and for the water conditioned by conspecifics. Auditory and olfactory abilities of P. leopardus are well developed at settlement-stage, and apparently sufficient to detect auditory and olfactory cues from reefs. [ABSTRACT FROM AUTHOR]

Competition between winter-sown wheat and Viola arvensis Murray or Papaver rhoeas L. was studied in two experiments in two successive years. The effects of varying crop and weed density were modelled in terms of weed biomass over time, weed seed production and crop yield. Biomass model parameters, representing maximum weed biomass and intra- and interspecific competition, were obtained for different assessment dates, enabling biomass levels to be predicted during the two growing seasons. Weed biomass declined, and its maximum level was reached earlier, with increasing crop density. Intraspecific competition was higher in the absence than in the presence of crop, increasing with time and with weed density. Halving the wheat population increased June biomass of V. arvensis by 74% and of P. rhoeas by 63%. Crop yield losses with increasing weed density were greater with low than with medium and high crop populations. P. rhoeas was significantly more competitive than V. arvensis in both years. Weed biomass in 1989 responded more to reductions in crop density following the milder winter of 1988/89 than in the previous year; however crop yields were less affected in 1989 due to summer drought, restricting late weed growth and competition. Weed seed production was related to weed biomass; the progressive lowering of crop density increased seed production, and both species were very prolific in the absence of crop. By combining models, seed production could be derived for a given competitive effect on the crop. Threshold weed populations, based on low weed levels that are not economic to control, could then be equated with the accompanying weed seed production. [ABSTRACT FROM AUTHOR]

An abstract of the conference paper "Optimizing expression of functional HIV envelopes in rVSV-ΔG vaccine vectors," by K. J. Wright and colleagues is presented.

An abstract of the conference paper "Viral vector delivery of Env trimer immunogens," by C. L. Parks and colleagues is presented.

This study evaluated the time course of systemic cytokine concentrations in an acute model of pneumonia in pigs challenged intranasally with Actinobacillus pleuropneumoniae. Feed intake and serum cortisol were measured as overt clinical and systemic markers of disease onset, respectively, and serum tumor necrosis factor-alpha, interleukin-1beta, and interferon-gamma as representative systemic inflammatory markers. Crossbred barrows (n = 15), approximately 5 wk of age, were used in the study. Pigs were housed in an environmentally controlled facility at 25 degrees C and under continuous illumination in pens measuring approximately 1.5 m2. Pigs had free access to water and an unmedicated diet. Approximately 1 wk prior to disease challenge, pigs were fitted nonsurgically with venous catheters. At challenge, pigs were given 5 x 10(8) CFU Actinobacillus pleuropneumoniae intranasally (n = 8) or a similar volume of sterile growth media intranasally (Control; n = 7). Feed intake was estimated by the change in feeder weight at 12-h intervals from -12 to 72 h relative to the time of disease challenge. Blood sampling began 12 h prior to challenge and continued until 72 h after challenge. Pigs were sampled at -12, -6, and 0 h, then at 90-min intervals until 12-h post-challenge, continuing at 3-h intervals until 24-h post-challenge, then again at 6-h intervals until 72 h after challenge. Serum was harvested and frozen until assayed for cortisol, tumor necrosis factor-alpha, interleukin-1beta, and interferon-gamma. Feed intake was reduced in Actinobacillus pleuropneumoniae pigs during the intervals 0 to 12 h (P < 0.001), 24 to 36 h (P < 0.001), 48 to 60 h (P <0.05), and 60 to 72 h (P < 0.05). TheActnobacillus pleuropneumoniae-challenged pigs had elevated serum cortisol from 180-min to 18-h post-challenge (P < 0.001) and also at 36 (P < 0.05), 42 (P < 0.001), and 60 (P < 0.05) h following infection. Circulating cytokines were not affected by disease challenge. Thus, in this experimental model of pneumonia, weaned pigs demonstrated expected behavioral and endocrine characteristics of disease in the absence of significant changes in circulating inflammatory cytokines.

Astrocytes provide protection and trophic support to neurons, but like neurons are vulnerable to oxidative stress. Decreased function of astrocytes resulting from oxidative stress could contribute to neurodegeneration. Our goal is to understand the intracellular events associated with oxidative stress in astrocytes. Because nitric oxide (NO) has been implicated as a contributor to oxidative stress in the brain, we examined in this study whether NO contributed to oxidative stress in astrocytes. Stimulation of NO decreases superoxide levels, preserves mitochondrial membrane potential, and decreases mitochondrial swelling in astrocytes treated with peroxide. Chelation of NO is associated with increased cell death, mitochondrial swelling, and loss of mitochondrial membrane potential, in response to peroxide treatment. Peroxide treatment increased intracellular calcium and the peroxide-induced changes in intracellular calcium were not altered in response to NO. Iron-loading increases peroxide-induced oxidative stress in astrocytes, but induction of NO limited the iron effect, suggesting an interaction between iron and NO. These data suggest endogenously produced NO protects astrocytes from oxidative stress, perhaps by preserving mitochondrial function., (Copyright 1999 Wiley-Liss, Inc.)

The antimicrobial and cytotoxic effects of Kri 1 paste, an iodoform-based primary tooth filling material, were compared with zinc oxide-eugenol (ZOE), using in vitro techniques. Antimicrobial evaluation involved measuring inhibition zones of Streptococcus faecalis on brain heart agar. Cytotoxicity evaluation involved direct cell-medicament contact experiments of 4-hr and 24-hr duration using fresh and set medicaments, and indirect cell-medicament contact experiments of 24-hr duration using fresh and set medicaments. ZOE produced a greater zone of bacterial inhibition than Kri 1 paste. Kri 1 paste cytotoxicity remained high regardless of the amount of setting time in the 4-hr direct contact experiment, while ZOE cytotoxicity decreased with setting time. Both Kri 1 paste and ZOE had high cytotoxicity regardless of setting time in the 24-hr direct cell-medicament contact test. ZOE cytotoxicity decreased to control levels after only 1 day of setting in the indirect contact experiments, compared with greater than 7 days for Kri 1 paste. The results suggest ZOE has better antimicrobial activity than Kri 1 paste. ZOE also has lower cytotoxicity, although prolonged cell-medicament contact may result in both medicaments having similarly high cytotoxicity.

The intraoperative development of tissue-space emphysema in a child undergoing restorative treatment under general anesthesia is presented. Emphysema development seems to be concomitant with the use of compressed air around patent root canals, complicated by tissue destruction due to movement of canal irrigants/medicaments into the periapical tissues and by secondary infection. Several recommendations for the prevention of tissue-space emphysema are presented including the use of a rubber dam, judicious use of compressed air, and maintenance of canal irrigants and medicaments within the root canal. Treatment recommendations vary from palliative care with follow up in cases of facial emphysema to immediate medical attention in cases of pharyngeal or mediastinal emphysema.

A study was conducted to determine if a four-hour emergency medical technician-defibrillation (EMT-D) course could produce student skills equivalent to a "standard" ten-hour EMT-D course. Two matched groups of EMTs were established, one of which was instructed by a four-hour course (study group) while the other (control group) entered a "standard" ten-hour course. On both written and practical testing, one week and 18 months after the completion of the course, the study group was comparable to the control group. These results indicate that the more cost-effective four-hour course can be used, thus encouraging the widespread availability of cardiac defibrillation by EMTs.