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R T Evans

Publications and source records attributed to R T Evans.

At least 37 records · Page 2Linked to original sources
PubMed1998

Serum CRP and IL-6 levels after trauma. Not predictive of septic complications in 31 patients.

We studied 31 blunt trauma victims, Injury Severity Score (ISS) mean 14 (9-57), for the pattern of release of C-reactive protein (CRP) and cytokine interleukin-6 (IL-6). Blood samples were taken on admission (within 6 hours of injury), as well as at 24 hours, and 3, 5 and 7 days. Serum CRP and IL-6 were measured by ELISA. Subsequent surgical events and sepsis were noted. Serum IL-6 levels on admission were considerably higher (median 135 pg mL-1) than our laboratory reference range (< 5 pg mL-1), slowly returning towards reference values during the study. Serum CRP levels were similar to laboratory normal values on admission (median 8.5 mg L-1 vs 7.5 mg L-1), reaching peak values (median 110 mg L-1) after 3 days. There was a correlation between IL-6 release and ISS but not between CRP and ISS. Patients undergoing surgery showed further increases in IL-6 and CRP levels postoperatively. Of 24 surgical patients, 9 developed postoperative sepsis. In blunt trauma patients, early assessment of the markers CRP or IL-6 were not useful for the diagnosis of sepsis. Levels of CRP following accidental or surgical trauma should be assessed with caution.

Adult↗
PubMed1994

Oral infection with Porphyromonas gingivalis and induced alveolar bone loss in immunocompetent and severe combined immunodeficient mice.

The suitability of a mouse model for host response in the induction of alveolar bone loss by Porphyromonas gingivalis was explored. The mouths of immunocompetent and severe combined immunodeficient (SCID) mice were infected with P. gingivalis ATCC 53977. P. gingivalis was not isolated from the mouths of these mice before infection, but was present at least 42 days after infection. P. gingivalis-specific IgG was present in sera from the infected, immunocompetent mice at the end of these experiments (42 days). Specific IgG was not present in sham-infected or uninfected immunocompetent mice, nor in any immunodeficient mice. Specific IgM was not present in any sera at 42 days. Infected, immunocompetent mice of two strains showed significant bone loss in comparison to sham-infected or uninfected immunocompetent mice (p < 0.05). Infected SCID mice, which are genetically lacking both B and T lymphocytes, also showed significant bone loss compared with sham-infected or uninfected SCID mice (p < 0.05). However, the degree of bone loss was greater in immunocompetent than immunodeficient mice: the relative amount of bone in infected mice was 77% of that in sham-infected immunocompetent mice, and 86% of sham values in SCID mice (p = 0.025). Thus oral infection of mice is a feasible model for studying the effects of host response on P. gingivalis-induced alveolar bone loss. Because bone loss was induced both in immunocompetent and SCID mice but was greater in immunocompetent mice, it appears that neither B nor T cells are absolutely necessary for bone resorption in response to P. gingivalis infection but they may significantly modulate the degree of resorption.

Alveolar Bone Loss↗
PubMed1994

Tetracyclines inhibit Porphyromonas gingivalis-induced alveolar bone loss in rats by a non-antimicrobial mechanism.

Tetracyclines have been widely used as adjuncts in periodontal therapy due to the antimicrobial efficacy of these drugs. Recently, their ability to inhibit host-derived matrix metalloproteinases (collagenase and gelatinase) and bone resorption in organ culture has also been invoked as a therapeutic rationale. The current study was undertaken to determine whether tetracyclines can inhibit alveolar bone loss in vivo due to a non-antimicrobial action of these drugs. Experimental periodontitis was induced by inoculating adult, male Sprague-Dawley rats with P. gingivalis (strain 381) following kanamycin/ampicillin pretreatment. Doxycycline, non-antimicrobial chemically-modified tetracycline (CMT-1) and vehicle alone were administered daily to 3 infected groups of rats (n = 6 rats per group; each group housed in a sterilized inflatable isolator) beginning 10 days after P. gingivalis inoculation. The control group (n = 6; non-infected rats) received only vehicle. After 5 weeks of daily drug administration by gastric intubation, the experiment was terminated and blood samples were taken from each animal to determine antibody levels against P. gingivalis. Plaque samples were collected from each group of animals before and after P. gingivalis inoculation and at the end of the experiment for microbiological examination. The jaws were removed from each rat, defleshed and then analyzed morphometrically and radiographically to assess bone loss. Serum antibody levels against P. gingivalis were significantly elevated in the 3 infected groups compared to the non-infected controls. This, together with the microbiologic findings, indicated that these groups of rats were infected with P. gingivalis.(ABSTRACT TRUNCATED AT 250 WORDS)

Alveolar Bone Loss↗
PubMed1994

Inactivation of the Porphyromonas gingivalis fimA gene blocks periodontal damage in gnotobiotic rats.

Fimbrial production by Porphyromonas gingivalis was inactivated by insertion-duplication mutagenesis, using the cloned gene for the P. gingivalis major fimbrial subunit protein, fimA. by several criteria, this insertion mutation rendered P. gingivalis unable to produce fimbrilin or an intact fimbrial structure. A nonfimbriated mutant, DPG3, hemagglutinated sheep erythrocytes normally and was unimpaired in the ability to coaggregate with Streptococcus gordonii G9B. The cell surface hydrophobicity of DPG3 was also unaffected by the loss of fimbriae. However, DPG3 was significantly less able to bind to saliva-coated hydroxyapatite than wild-type P. gingivalis 381. This suggested that P. gingivalis fimbriae are important for adherence of the organism to saliva-coated oral surfaces. Further, DPG3 was significantly less able to cause periodontal bone loss in a gnotobiotic rat model of periodontal disease. These observations are consistent with other data suggesting that P. gingivalis fimbriae play an important role in the pathogenesis of human periodontal disease.

Alveolar Bone Loss↗
PubMed1994

The effect of supplementary protein on in vivo metabolism of the mammary gland in lactating dairy cows.

Four lactating cows equipped with rumen and duodenal cannulas were fed a diet of grass silage and concentrates containing either 12.4 or 17.2% CP (DM basis) in a change-over design. Additional protein was supplied as white fish meal. Fish meal did not affect molar proportions of VFA in the rumen, but duodenal NAN supply was increased .69 g/g of N in supplementary feed. In Experiment 2, three lactating dairy cows that had been prepared with catheters across the mammary gland were fed the same diets using a switchback design. Blood samples were taken to determine changes in metabolite flux to the mammary gland. In both experiments, milk production and protein yield were nonsignificantly increased by addition of fish meal. Milk urea output was increased from 3.18 to 4.74 g/d by fish meal supplementation, reflecting increased arterial concentrations of urea. Concentrations of glucose, VFA, and BHBA in blood showed no substantial changes because of dietary supplementation of fish meal. Supply of essential AA increased 26% with fish meal supplementation, mammary uptake increased 34%, but milk protein output only increased 5%. The low efficiency of conversion of supplementary protein to milk protein appears to be related to the inability of the gland to utilize the additional AA.

Amino Acids↗
PubMed1992

Immunization with fimbrial protein and peptide protects against Porphyromonas gingivalis-induced periodontal tissue destruction.

In these studies we have attempted to show that cell surface structures are critical antigens for protection against P. gingivalis-induced periodontal destruction. Fimbrillin, and in particular a synthetic 20-amino-acid fimbrillin peptide, exerts a protective effect in gnotobiotic rats, thus identifying them as potentially useful in the development of a vaccine.

Alveolar Bone Loss↗
PubMed1992

Periodontopathic potential of two strains of Porphyromonas gingivalis in gnotobiotic rats.

Germ-free rats were monoinfected with Porphyromonas gingivalis strains 381 or A7A1-28 for 42 or 84 days. Both strains induced substantial destruction of alveolar bone and soft tissue when compared to non-infected controls, but the patterns were different. Strain A7A1-28 was associated with increased activity of host collagenase and gelatinase at 42 days, whereas the activity was elevated to a lesser extent at 84 days. Strain 381 showed a moderate increase in host proteinase activity at 42 days, and this remained unchanged until day 84. Strain A7A1-28 was associated with more bone loss than strain 381 by a morphometric analysis that detects horizontal bone loss in the maxilla. Strain 381 was associated with more bone loss than strain A7A1-28 by a radiographic method that detects vertical intrabony defects in the mandible. Infection with one strain gave rise to serum and salivary antibodies strongly reactive to the infecting strain and moderately reactive to antigens from the other strain. This indicates that some antigenic similarity exists between the strains and that there are also strain or perhaps serotype differences in antibody responses induced by infection. Thus two strains of P. gingivalis differing in antigenicity and pathogenicity in the mouse model of the subcutaneous abscess cause substantial periodontal destruction in the germ-free rat. The disease pattern is, however, different, with strain A7A1-28 inducing mostly horizontal bone loss and strain 381 mostly vertical.

Alveolar Bone Loss↗
PubMed1992

Periodontal bone loss in Porphyromonas gingivalis-infected specific pathogen-free rats after preinoculation with endogenous Streptococcus sanguis.

Anaerobic Gram-negative bacteria dominate in periodontitis locations, while Gram-positive bacteria characterize healthy sites. A well-established Gram-positive flora might therefore inhibit the colonization of Gram-negative pathogens. The purpose of the present investigation was to examine whether endogenous S. sanguis could prevent, or reduce, periodontal bone loss in rats infected with a virulent P. gingivalis strain. Sixty specific pathogen-free Wistar rats were divided into 6 groups. Doxycycline was administered in the drinking water for 2 weeks to the groups A, B, C, and D to suppress the preexisting microflora in the mouth. Rats in groups A and C were subsequently inoculated with an S. sanguis strain, isolated from one of the rats, once a day for 5 d. Infection with P. gingivalis 381 was then carried out for 5 d in groups A, B, and E. Group F was not treated with doxycycline nor infected with bacteria and served as untreated control. Six weeks after the P. gingivalis inoculation, the rats were killed. Periodontal bone levels were assessed radiographically and morphometrically, and serum antibody against P. gingivalis 381 was determined by a fluorescence immunoassay. Periodontal bone support, determined radiographically, was reduced in group B (doxycycline-treated, P. gingivalis-inoculated) compared with the other groups. In contrast, the morphometric determination showed no differences between the groups. In group B antibody levels against two different P. gingivalis 381 cell surface antigens were significantly elevated.(ABSTRACT TRUNCATED AT 250 WORDS)

Alveolar Bone Loss↗
PubMed1992

Immunization with Porphyromonas (Bacteroides) gingivalis fimbriae protects against periodontal destruction.

Adhesive fimbriae from Porphyromonas gingivalis are cell surface structures which may be important in the virulence of this oral pathogen and thus may serve as a critical or target antigen. Immunization with highly purified 43-kDa fimbrial protein protected against periodontal tissue destruction when tested in the P. gingivalis-infected gnotobiotic rat model. A similarly highly purified 75-kDa cell surface component did not provide protection. Heat-killed whole-cell and sonicated cell surface extracts which contain the 43-kDa protein as well as the 75-kDa component were protective also. This study indicates that the fimbrial protein may serve as a model for the development of effective vaccines against periodontitis, a major human oral disease.

Alveolar Bone Loss↗
PubMed1991

Asymmetry in periodontal bone loss of gnotobiotic Sprague-Dawley rats.

In five consecutive experiments involving 78 gnotobiotic rats, significant bone loss was seen in the maxillae of those mono-infected with strains of Porphyromonas gingivalis. No significant bone loss was seen in the mandibles, and when data from both jaws were combined, the significant loss in the maxillae was occasionally concealed. It is recommended, therefore, that the levels of maxillary and mandibular bone in rats be analysed separately. A possible lateral bias of periodontal bone level was investigated in the same rats. In a highly significant number of cases the right-hand side was more severely affected than the left. This asymmetry was found in both germ-free and infected rats, and consequently could not be ascribed to P. gingivalis infection. Asymmetry of bone loss may contribute to the total random variation in bone level in rats and should be accounted for in future studies of experimental periodontitis in this model.

Alveolar Bone Loss↗
PubMed1991

Periodontal bone level and gingival proteinase activity in gnotobiotic rats immunized with Bacteroides gingivalis.

Bacteroides gingivalis is associated with various forms of periodontal disease. To assess the role of the immune response in modulating B. gingivalis-associated periodontal disease, the effect of immunization of B. gingivalis-induced periodontal bone loss was evaluated in gnotobiotic rats. Male Sprague-Dawley rats immunized with various doses of whole cells or sham-immunized with incomplete Freund's adjuvant were monoinfected with B. gingivalis in carboxymethylcellulose by gavage. Two additional groups served as either sham-immunized or untreated germ-free controls. Forty-two days after infection, all rats were killed, periodontal bone level was assessed morphometrically and radiographically, and gingival proteinase (mammalian collagenase and acid cathepsin) activity was assessed biochemically. B. gingivalis was present in oral samples from all monoinfected rats, and no contaminating bacteria were detected in any oral or fecal sample. Animals immunized with B. gingivalis cells had elevated serum and saliva antibodies to whole cells and partially purified fimbriae from B. gingivalis. Infected sham-immunized rats had significantly more periodontal bone loss than noninfected controls, whereas the periodontal bone level in infected rats immunized with 10(10) B. gingivalis cells was similar to that of the noninfected controls. The activities of gingival collagenase and cathepsin B and L were high in sham-immunized infected rats and low in all other animal groups. In conclusion, it is possible to reduce B. gingivalis-induced periodontal tissue loss in gnotobiotic rats by immunization.

Alveolar Bone Loss↗
PubMed1990

A 2-year quantitative assessment of Chlamydia trachomatis in a sexually transmitted diseases clinic population by the MicroTrak direct smear immunofluorescence test.

The MicroTrak direct smear immunofluorescence test was used to determine the prevalence of Chlamydia trachomatis elementary bodies (EBs) in groups of patients in various clinical categories, most of whom were seen in a clinic for sexually transmitted diseases (STD). Overall, 8138 adequate specimens were tested, of which 14.3% were found to contain chlamydial EBs. Of the samples from patients seen in the STD clinic, over 70% were from women and 14.9% of these were positive, as were 15.7% of those from men. EBs were detected in 27% of samples from infants and in 7.0% of those from adults with conjunctivitis. EBs were detected most often in men with nongonococcal urethritis (40.2%), infants with conjunctivitis (30%) and contacts of chlamydiae-positive patients (24.5%) and least often in 'prostatitis' (2.9%) and patients tested to determine the success of treatment (2.7%). Over 40% of samples from both the male urethra and the cervix contained 10 or fewer EBs, highlighting the importance of recognizing small numbers and the sensitivity required of other detection procedures.

Adult↗
PubMed1990

Albumin-adjusted calcium concentration in serum increases during normal pregnancy.

Concentrations of total calcium and albumin were measured in serum specimens from 41 women at intervals before, during, and after 42 pregnancies. The albumin concentration decreased but the calcium decreased more slowly, so that the albumin-adjusted calcium concentration increased from conception to term. These findings, taken in conjunction with published observations of hypercalciuria, increased concentrations of 1,25-dihydroxycholecalciferol and calcitonin in serum, and decreased concentrations of intact parathyrin in serum, strongly suggest that maternal ionized calcium increases throughout normal pregnancy.

Adult↗
PubMed1989

Studies of the effect of recombinant human-alpha 1 interferon on experimental parainfluenza type 3 virus infections of the respiratory tract of calves.

The effect of the administration of recombinant human interferon on the severity of clinical disease and the extent of pneumonic lesions in calves infected experimentally with bovine parainfluenza 3 (PI3) virus was studied in two experiments. In the first, three pairs of calves aged seven to 10 days were used; one of each pair was injected intramuscularly with 10(6) units of interferon/kg bodyweight for three consecutive days, and the other was left untreated. On the day after the first injection of interferon all the calves were challenged with PI3 virus, a different dose being administered to each pair. There was no evidence of any protective effect from the treatment with interferon. The second experiment used eight, six-week-old calves; four were inoculated in the same way with interferon and all the calves were challenged with the same dose of PI3. Again, there was no evidence of a reduction either in the severity of clinical disease or in the extent of lung consolidation in the calves treated with interferon.

Animals↗