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Biomedical subjects

T A Evans

Publications and source records attributed to T A Evans.

18 recordsLinked to original sources
PubMed2006

The effect of bait design on bait consumption in termites (Isoptera: Rhinotermitidae).

The efficacy of baiting as a pest control method relies on the bait appealing to the pest species. In the case of wood-eating termites, bait stations should be designed to encourage termite presence and to maximize their consumption of bait matrix in order to expedite control in minimal time. A field experiment examined the effect of bait size (one large bait or four small baits of equivalent total size, with commensurate inspection and replacement schedules), compaction (tightly rolled or loosely folded) and composition (paper only or paper plus wood) on termite presence and on untreated bait paper removal rates over four months. All three factors were significant, with bait size the most important factor, followed by compaction and then composition. The least effective baits were small, compacted (rolled) paper-only baits with monthly inspections; these had the highest abandonment rate (70%) and had the least paper removed (mean of 24 g). The most effective baits were large, folded paper-plus-wood baits with inspections at two months; these had the lowest abandonment rate (20%) and had the highest paper removal (mean of 112 g). The more than four-fold difference between these baits types demonstrates that bait efficacy can be altered considerably merely by changing bait design without adding new ingredients to the bait matrix.

Animals↗
PubMed2004

Effect of an acute bout of soccer heading on postural control and self-reported concussion symptoms.

Our purpose was to determine if an acute bout of heading soccer balls adversely affected postural control and self-reported symptoms of cerebral concussion. Thirty-one college-aged soccer players were randomly placed into either a kicking group or a heading group. Subjects either kicked or headed 18 soccer balls over the course of 40 minutes. Subjects had their postural control assessed while standing on a force plate and completed a concussion symptoms checklist on three separate occasions: prior to, immediately following, and 24 hours after kicking or heading. There were no significant differences between the heading and kicking groups on the postural control measures prior to, immediately following, and 24 hours after kicking/heading. The heading group did, however, report significantly more concussion symptoms than the kicking group immediately after heading, but not 24 hours after heading. The number of previous concussions sustained by subjects did not influence the effects of heading. An acute bout of soccer heading appears to cause an increase in self-reported symptoms of cerebral concussion lasting less than 24 hours but no quantifiable deficits in postural control. Further research is needed to investigate the cumulative effects of soccer heading on postural control and other objective measures of brain function.

Adult↗
PubMed2004

Comparing mark-recapture and constant removal protocols for estimating forager population size of the subterranean termite Coptotermes lacteus (Isoptera: Rhinotermitidae).

Forager population sizes of colonies of Coptotermes lacteus(Froggatt) in New South Wales were estimated using two methods: mark-recapture and constant removal, in two disturbed habitats: a pine plantation and cleared farmland. Mark-recapture population estimates were unrealistic and unreliable: they could be improbably large, over 200 million foragers, and they varied enormously between samples for each colony without any pattern. The constant removal population estimates could also be unrealistic: they could be negative or quite different when calculated using regression and maximum likelihood methods. However, the unrealistic results could be predicted reliably, and explained by the lack of re-contact with the sampling devices (bait stations) - a violation of an assumption of the method. This happened more frequently in the plantation than in the farmland, probably because of the greater abundance of alternative food sources in the plantation. Of the two methods, constant removal provided reasonable forager population estimates, relative to direct counts, at least some of the time, plus a mechanism by which reliability could be tested, whereas mark-recapture provided neither. Further refinement and testing of constant removal methods are urged to provide a more reliable population estimation technique for termites.

Animals↗
PubMed2003

The influence of soil heterogeneity on exploratory tunnelling by the subterranean termite Coptotermes frenchi (Isoptera: Rhinotermitidae).

The exploration of sand-filled arenas by workers of an entire colony of the Australian, subterranean foraging, tree-nesting termite, Coptotermes frenchi Hill was investigated under laboratory conditions. The first experiment tested whether termite exploration of sand was influenced by the presence of gaps or objects in the sand. Gaps and objects were chosen to represent soil heterogeneity in the urban environment: gaps to represent tunnels dug by other animals, perspex strips to represent cables and pipes, and wood strips to represent roots. Termites always chose to explore gaps thoroughly before they began tunnelling in the sand. Significantly more and longer tunnels were excavated from the end of gaps at the far end of the arenas, and relatively little tunnelling occurred around and along objects. Termite density was significantly greater around and along wood compared with perspex blocks. The second experiment tested whether termite exploratory tunnelling was influenced by soil moisture. The termites tunnelled slowly in dry sand, but after discovering a patch of wet sand, increased tunnelling five-fold until it was completely explored, after which activity declined. Energy and water conservation may be behind these patterns of exploratory tunnelling as well as those seen in large field studies, but caution is urged when interpreting small scale laboratory experiments to explain large scale field data.

Animals↗
PubMed2002

Tunnel specificity and forager movement in subterranean termites (Isoptera: Rhinotermitidae and Termitidae).

The movement of foragers of two species of Australian, subterranean, mound-building termites, Coptotermes lacteus (Froggatt) (Rhinotermitidae) and Nasutitermes exitiosus (Hill) (Termitidae), was investigated in their natural habitat using artificial feeding sites along trenches dug to mimic natural forager tunnels that radiate out from the central mound-nests. Termites were dyed by self-feeding on cardboard soaked with histological fat-stains on one or two trenches and then termites were collected from other feeding sites at two and four weeks after the fat-stains were placed. At two and four weeks after marking commenced, 60-75% of marked termites were found in trenches containing the marked paper, and 2-16% were found in trenches on the opposite side of the nest. The proportion of marked termites in a sample was three to eight times greater in the trenches containing the marked paper relative to other trenches. Although difficulties with fat-stains used as markers might explain some of the observed patterns, it is evident that C. lacteus and N. exitiosus foragers do not move randomly between feeding sites in their natural habitat.

Animals↗
PubMed2001

Estimating relative decline in populations of subterranean termites (Isoptera: Rhinotermitidae) due to baiting.

Although mark-recapture protocols produce inaccurate population estimates of termite colonies, they might be employed to estimate a relative change in colony size. This possibility was tested using two Australian, mound-building, wood-eating, subterranean Coptotermes species. Three different toxicants delivered in baits were used to decrease (but not eliminate) colony size, and a single mark-recapture protocol was used to estimate pre- and postbaiting population sizes. For both species, the numbers of termites retrieved from bait stations varied widely, resulting in no significant differences in the numbers of termites sampled between treatments in either the pre- or postbaiting protocols. There were significantly fewer termites sampled in all treatments, controls included, in the postbaiting protocol compared with the pre-, suggesting a seasonal change in forager numbers. The comparison of population estimates shows a large decrease in toxicant treated colonies compared with little change in control colonies, which suggests that estimating the relative decline in population size using mark-recapture protocols might to be possible. However, the change in population estimate was due entirely to the significantly lower recapture rate in the control colonies relative to the toxicant treated colonies, as numbers of unmarked termites did not change between treatments. The population estimates should be treated with caution because low recapture rates produce dubious population estimates and, in some cases, postbaiting mark-recapture population estimates could be much greater than those at prebaiting, despite consumption of bait in sufficient quantities to cause population decline. A possible interaction between fat-stain markers and toxicants should be investigated if mark-recapture population estimates are used. Alternative methods of population change are advised, along with other indirect measures.

Animals↗
PubMed1999

Increased inducible apoptosis in CD4+ T lymphocytes during polymicrobial sepsis is mediated by Fas ligand and not endotoxin.

Recent studies suggest that increased lymphocyte apoptosis (Ao) detected in peripheral blood T cells from burn patients appears to contribute to decreased lymphocyte immunoresponsiveness. However, while it is known that sepsis induces a marked depression in the splenocyte immune response (i.e. decreased interleukin-2, interferon-gamma production and proliferation) in response to the T-cell mitogen concanavalin A (Con A), it is unknown whether this depression is associated with an increase in inducible Ao and if so, which mediators control this process. To assess this, splenocytes were harvested from mice at 24 hr (a period associated with decreased Con A response) after the onset of polymicrobial sepsis [caecal ligation and puncture (CLP)] or sham-CLP (Sham) and then stimulated with 2.5 microg Con A/ml (24 hr). Septic mouse splenocytes stimulated with Con A, while not showing a change in their phenotypic make-up, did exhibit a marked increase in the percentage of splenocyte that were Ao+ which was associated with altered cytokine release. This appears to be due to an increase in the percentage of Ao+ cells in the CD4+ CD8- population and was associated with enhanced Fas antigen expression as well as an increase in mRNA for the Fas-FasL gene family. To determine if the changes in Ao are due to either endotoxin (a product of Gram-negative bacteria seen in CLP mice) or the expression of Fas ligand (FasL; a mediator of activation-induced lymphocyte Ao), a second set of studies examining Con A-inducible Ao was performed with splenocytes harvested from septic endotoxin-tolerant C3H/HeJ and the FasL-deficient C3H/HeJ-Fasl gld mice. The results show that increased splenocyte Ao detected following CLP is due to a FasL-mediated process and not to endotoxin. Thus the inadvertent up-regulation of FasL-mediated splenocyte Ao may contribute to the depression of splenocyte immune responses seen during polymicrobial sepsis.

Animals↗
PubMed1998

Increased mucosal B-lymphocyte apoptosis during polymicrobial sepsis is a Fas ligand but not an endotoxin-mediated process.

Sepsis is reported to induce an increase in the rate of apoptosis (Ao), in immature lymphoid cells residing in hematopoietic tissues such as the thymus and bone marrow. Alternatively, secondary lymphoid tissue, such as the spleen exhibit little innate (unstimulated) Ao. However, it is unknown whether or not polymicrobial sepsis has any effects on the frequency of Ao in mucosal lymphoid tissue and what, if any, are the functional consequences of such a change. To assess this, Peyer's patch cells were harvested from C3H/HeN (endotoxin-sensitive) mice killed 12 or 24 hours after the onset of polymicrobial sepsis (cecal ligation and puncture [CLP]). The results indicate that the percentage of cells that were Ao+ as determined by flow cytometry were markedly increased at 24 hours, but not at 12 hours post-CLP. This correlates well with evidence of increased DNA fragmentation as well as histological changes observed both at a light and transmission electron microscopic level of the Peyer's patch Ao. Phenotypically, these changes were restricted to the B220+ (B-cell) population that also exhibited a marked increase of Fas/Apo-1 antigen expression. The functional consequence of this increased apoptosis appears to be associated with the endogenous stimulation (activation) of IgA production by mucosal B lymphocytes and increased nuclear c-Rel expression. Furthermore, we found that Peyer's patch lymphocytes isolated from C3H/HeJ-Faslgld (endotoxin-tolerant/Fas ligand- [FasL] deficient) as opposed to C3H/HeJ (endotoxin-tolerant) inbred mice did not exhibit increased Ao after CLP. These findings indicate that increased B-cell Ao appears to be a FasL-Fas antigen-mediated process, but is not due to endotoxin sensitivity. In conclusion, we speculate that the increased Fas-associated apoptosis detected in mucosal B cells (as opposed to splenic or bone marrow B cells) may be due to increased luminal antigens other than endotoxin, released due to gut barrier integrity breakdown during sepsis.

Animals↗
PubMed1998

Does hepatocellular injury in sepsis involve apoptosis?

Apoptosis (AO) is a process by which cells typically undergo a form of nonnecrotic cellular suicide. AO normally allows the host to selectively delete cells from a given tissue site without producing bystander injury associated with necrosis. However, inappropriate induction of AO has been associated with a variety of acute as well as chronic pathological states and may contribute to the therapeutic nonresponsiveness frequently encountered in the septic animal/patient's organ function. In this respect, while AO has been demonstrated in a variety of immune cell tissues of septic animals it is unclear if it is present in the septic liver. Therefore, it was the aim of our study to determine if AO is evident in hepatocytes of polymicrobial septic animals. To assess this, C3H/HeN male mice were subjected to polymicrobial sepsis (cecal ligation and puncture) or sham- CLP (Sham). Hepatocytes were then harvested at 4 h (early hyperdynamic phase) or 24 h (late hypodynamic state) later, and indices of AO were assessed [cell cycle analysis of Annexin V/propidium iodide (PI) staining for flow cytometric analysis, DNA extracted, and cell death ELISA]. Plasma glutamic pyruvic transaminase (GPT) was also colorimetrically assessed as well as total viable cell yield as an index of hepatocellular necrosis. The results indicate that indices of hepatocellular AO, as determined by cell cycle analysis and cell death ELISA, were markedly increased in polymicrobial septic mice at 24 h. However, while an increase in DNA fragmentation/degradation could be consistently detected, the pattern was typically faint. Similarly, although there was an increase in Annexin V staining it was not dissociated from that of PI (necrotic index). Alternatively, necrosis (as evidenced by increased GPT levels at both 4 and 24 h) preceded the induction of all the indices of AO. Taken together, these data suggest a role for both necrosis and apoptosis in the evolution of hepatocellular injury encountered in the polymicrobial septic animal/patient which may represent a unique pattern of cell death under such conditions.

Animals↗
PubMed1998

Septic arthritis of the knee following anterior cruciate ligament reconstruction: results of a survey of sports medicine fellowship directors.

To determine the incidence of joint sepsis following anterior cruciate ligament (ACL) reconstruction and the prevailing attitudes toward its treatment, we surveyed the directors of Sports Medicine Fellowship programs about their practices in treating and preventing this complication. Of the 74 surgeons surveyed, 61 (82%) responded. These 61 surgeons performed an average of 98 ACL reconstructions yearly; 31 (51 %) routinely used a drain after ACL surgery, 18 (30%) had treated an ACL infection within the past 2 years, and 26 (43%) had treated an infection within the past 5 years. There was no significant difference in the number of infections and the surgeons' case load, graft choice, or method of reconstruction. Fifty-two surgeons (85%) selected culture-specific intravenous (IV) antibiotics and surgical irrigation of the joint with graft retention as initial treatment for the infected patellar tendon autograft, and 39 (64%) chose this regimen to treat the infected allograft. For the resistant infection unresponsive to initial treatment, IV antibiotics with surgical irrigation and graft retention were also selected as the most common treatment combination for 25 (39%) of the 61 respondents. After graft removal, the earliest a revision procedure would be considered was 6 to 9 months. The results of this survey confirm the widely held belief that septic arthritis of the knee is a relatively rare complication following ACL reconstruction. Once an infection is encountered, culture-specific IV antibiotics and surgical joint irrigation with graft retention are recommended as initial treatment. Graft excision and hardware removal is considered only for those infections resistant to initial treatment and for the infected allograft.

Anterior Cruciate Ligament↗
PubMed1997

Factors responsible for peritoneal granulocyte apoptosis during sepsis.

Apoptosis (Ao), is a process by which cells undergo a form of non-necrotic cellular suicide, the control of which may have significant impact on host immunoresponsiveness to a septic challenge. The aim of this study was to determine (1) if Ao is evident in granulocytes harvested from the blood or peritoneum of septic animals and to what extent this was associated with cell activation and (2) whether the in vivo administration of the TNF inhibitor (TNFbp) alters this process. To assess the first aim, C3H/HeN male mice were subjected to polymicrobial sepsis [cecal ligation and puncture (CLP)] or sham-CLP (Sham) and sacrificed at 4 or 24 hr following CLP. Blood leukocytes and peritoneal exudate cells were harvested, stained with monoclonal fluorochrome-conjugated antibodies to granulocytes (Gr1), the activation marker ICAM-1, and either the cell cycle dye, 4',6-diamidino-2-phenylindole, or TUNEL assay (to assess the %Ao+), was used for two- and three-color flow cytometric analysis. Peritoneal exudate cells exhibited increased %Ao+ cells at both 4 and 24 hr post-CLP, while blood leukocytes showed a decrease in %Ao+ only at 24 hr. The increase in Ao in the peritoneum was evident only in the Gr1- cell population at 4 hr but was present in both Gr1+ and Gr1- cells at 24 h. Furthermore, the increase in the %Ao+ cells was associated with an increased % of ICAM-1 positive cells. To the extent that TNF affects the 24 hr induction of Ao in peritoneal exudate cells, mice were treated with either 250 micrograms TNFbp/mouse (s.c.) or vehicle control immediately following CLP. The results indicate that administration of TNFbp markedly decreased Gr1+ but not Gr1- cell Ao. Thus, not only does polymicrobial sepsis induce a marked early rise in phagocyte Ao associated with cell activation, but the increase in peritoneal granulocyte Ao, unlike macrophage Ao, is mediated by TNF and/or an agent released by TNF.

Animals↗
PubMed1995

Agility following the application of cold therapy.

Cold application is commonly used before strenuous exercise due to its hypalgesic effects. Some have questioned this procedure because of reports that cold may reduce isokinetic torque. However, there have been no investigations of actual physical performance following cold application. The purpose of this study was to determine if a 20-minute ice immersion treatment to the foot and ankle affected the performance of three agility tests: the carioca maneuver, the cocontraction test, and the shuttle run. Twenty-four male athletic subjects were tested during two different treatment sessions following an orientation session. Subjects were tested following a 20-minute 1 degrees C ice immersion treatment to the dominant foot and ankle and 20 minutes of rest. Following each treatment, subjects performed three trials of each agility test, with 30 seconds rest between each trial, and 1 minute between each different agility test. The order in which each subject performed the agility tests was determined by a balanced Latin square. A MANOVA with repeated measures was used to determine if there was an overall significant difference in the agility times recorded between the cold and control treatments and if the order of the treatment sessions affected the scores. Although the mean agility time scores were slightly slower following the cold treatment, cooling the foot and ankle caused no difference in agility times. Also, there was no difference resulting from the treatment orders. We felt that the slightly slower scores may have been a result of tissue stiffness and/or subject's apprehension immediately following the cold treatment. Cold application to the foot and ankle can be used before strenuous exercise without altering agility.

Journal Article↗
PubMed1992

Modification of the bicinchoninic acid protein assay to eliminate lipid interference in determining lipoprotein protein content.

The bicinchoninic acid (BCA) assay method for the determination of protein has been investigated for its utility in measuring the protein content of plasma lipoproteins. Although other methods, principally those based on the method of Lowry et al. (1951, J. Biol. Chem. 193, 265-275) have been extensively used for this purpose, the tolerance of the BCA method to many commonly encountered detergents and buffers offers a definite advantage over the Lowry-based methods. In this study, lipoprotein protein values obtained by the BCA method were compared to a standard modification of the Lowry et al. procedure since this assay forms the basis of much of the relevant literature. The standard BCA assay was found to overestimate the protein content of very low density lipoprotein by approximately 70% and low density lipoprotein by approximately 30%; high density lipoprotein values compared favorably. Overestimations by the BCA assay paralleled the relative phospholipid content of the lipoprotein fractions. This apparent lipid effect was eliminated by the addition of 2% sodium dodecyl sulfate to samples prior to the analysis. In the presence of this detergent, BCA assay measurements for these three lipoprotein fractions were 97, 90, and 98%, respectively, of the reference assay values.

Humans↗
PubMed1980

Aldosterone-induced hypertension: effects of a kininase inhibitor.

A synthetic orally active angiotensin I converting enzyme inhibitor Captopril (Squibb), (D-2-methyl-3-mercaptopropanoyl-L-Proline), was administered to three groups of hypertensive animals. The animals were made hypertensive by uninephrectomy, daily injections of 5 ug/100 g body weight d-aldosterone (Sigma) in wheat germ oil and substitution of 0.9% NaCl for the drinking water. Captopril was given to pregnant and nonpregnant animals during the developmental phase of hypertension and to nonpregnant animals with established (4 weeks of treatment) hypertension. The agent attenuated the hypertension in both the pregnant and nonpregnant animals when given while hypertension was developing. Captopril was effective in reducing established aldosterone-NaCl hypertension to normotensive levels.

Aldosterone↗
PubMed1975

Evidence for 5- and 6-coordinated magnesium in bacterio-chlorophyll a from visible absorption spectroscopy.

The visible absorption spectrum of bacteriochlorophyll a (Bchl) in the 560-620 nm (yellow) region can be used to establish the coordination state of the central Mg atom. Five-coordinated Mg species absorb near 580 nm, whereas 6-coordinated Mg species are red-shifted to about 610 nm. Five-coordination is confirmed to be the principal coordination state of Mg in self-aggregated bacteriochlorophyll. The equilibrium constant for the reaction Bchl - Py + Py equilibrium Bchl - Py2 has been determined from computer-assisted analyses of spectral data, where Py represents pyridine. The spectral criteria for the coordination state of Mg in bacteriochlorophyll advanced here are shown to be applicable to both in vitro and in vivo systems. Similar spectral behavior is exhibited by chlorophylls a and b, and a band at 633 nm is shown to be associated with the presence of 6-coordinated Mg in chlorophyll a.

Bacteriochlorophylls↗
PubMedDate not supplied

Perception of oral health needs by Southeast Iowa non-dental health care providers.

The purposes of this dental study were to identify, among non-dental health care providers and administrators, (1) those reasons assessed to be most persuasive in adopting selected dental preventive practices, (2) barriers perceived to be present for their clients to obtain dental services, and (3) practices which would make dental services more available to their clients. A nine-item dental care/attitude survey was completed by 82% (n = 68) of the health care and social services providers/administrators attending one of the United Way of East Central Iowa group meetings. The results of this survey indicated that, for these respondents, the most persuasive reasons for adopting preventive dental practice behaviors were based on susceptibility to disease and social and esthetic benefits. Further, the results of this survey showed that female respondents gave significantly higher scores than males to the importance of social benefits (self-worth and employment marketability), health benefits, and the importance that authority figures (dentists and physicians) placed on the behavior. Fifty-one percent of the respondents knew of patients who had problems obtaining dental services. The main reasons given for clients' access problems were the lack of money, the lack of insurance, and the lack of transportation.

Administrative Personnel↗