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Biomedical subjects

D Spratt

Publications and source records attributed to D Spratt.

18 recordsLinked to original sources
PubMed2006

Incidence and behaviour of Tn916-like elements within tetracycline-resistant bacteria isolated from root canals.

INTRODUCTION: Tetracycline resistance is commonly found in endodontic bacteria. One of the most common tetracycline-resistance genes is tet(M), which is often encoded on the broad-host-range conjugative transposon Tn916. This study aimed to determine whether tet(M) was present in bacteria isolated from endodontic patients at the Eastman Dental Institute and whether this gene was carried on the transferable conjugative transposon Tn916. METHODS: The cultivable microflora isolated from 15 endodontic patients was screened for resistance to tetracycline. Polymerase chain reactions for tet(M) and for unique regions of Tn916 were carried out on the DNA of all tetracycline-resistant bacteria. Filter-mating experiments were used to see if transfer of any Tn916-like elements could occur. RESULTS: Eight out of 15 tetracycline-resistant bacteria isolated were shown to possess tet(M). Furthermore, four of these eight were shown to possess the Tn916-unique regions linked to the tet(M) gene. Transfer experiments demonstrated that a Neisseria sp. donor could transfer an extremely unstable Tn916-like element to Enterococcus faecalis. CONCLUSIONS: The tet(M) gene is present in the majority of tetracycline-resistant bacteria isolated in this study and the conjugative transposon Tn916 has been shown to be responsible for the support and transfer of this gene in some of the bacteria isolated.

Bacteria↗
PubMed2004

Cultivable microbial flora associated with persistent periapical disease and coronal leakage after root canal treatment: a preliminary study.

AIM: To identify the cultivable bacterial flora in root filled teeth with persistent periapical lesions and to locate their distribution within the root canal system using an in vitro sampling protocol. METHODOLOGY: Eight freshly extracted root filled teeth were collected from the Oral and Maxillo-facial Surgery Department, Eastman Dental Hospital. Seven teeth were associated with persistent apical periodontitis and also showed evidence of coronal leakage. Teeth were transferred to an anaerobic chamber immediately after careful extraction and sectioned transversely to give a crown (in all but one case) and two root segments (coronal and apical). Two samples were obtained from each segment, one from dentine and the other from the restoration or gutta-percha (GP) root filling (46 sites in total). The samples were dispersed, serially diluted and cultured on blood agar and fastidious anaerobic agar (with 5% defibrinated horse blood). The primary growth was subcultured to obtain pure isolates, which were identified by routine microbiological techniques and commercial enzyme tests. RESULTS: A total of 252 strains were isolated from all the teeth. Of all the isolates, the most prevalent bacteria were Gram-positive facultative anaerobes 189/252 (75%) with staphylococci (48/252, 19%), streptococci (44/252, 17%), enterococci (20/252, 8%) and Actinomyces species (20/252, 8%) being found in most of the teeth (6/8, 6/8, 5/8, 5/8 and 7/8, respectively). Of the obligate anaerobes (17%), peptostreptococci (7%) were also present in most teeth (7/8). A statistical association between bacterial flora and site (crown/coronal/apical) or surface (dental/GP/restoration) could not be shown. CONCLUSIONS: The predominant group of bacteria in root filled teeth with persistent apical periodontitis and coronal leakage was Gram-positive facultative anaerobes of which staphylococci followed by streptococci and enterococci were the most prevalent.

Adult↗
PubMed2002

An in vitro comparison of the bactericidal efficacy of lethal photosensitization or sodium hyphochlorite irrigation on Streptococcus intermedius biofilms in root canals.

AIM: To compare the bacterial killing of Streptococcus intermedius biofilms in root canals using lethal photosensitization with various combinations of photosensitizer concentration and laser light dose or 3% sodium hypochlorite (NaOCl) irrigation. METHODOLOGY: Extracted teeth (n = 35) with single canals were selected and the canals prepared to apical size 25 with a 10% taper. The teeth were autoclaved and the canals inoculated with Streptococcus intermedius in brain heart infusion broth and were incubated for 48 h to allow a biofilm to form. The teeth were then subjected to 3% NaOCl irrigation (n = 4) or lethal photosensitization using combinations of a range of toluidine blue O (TBO) photosensitizer concentrations (12.5, 25, 50, 100 microgram/mL-1) and light doses (60, 90, 120, 300, 600 s equivalent to energy doses of 2.1-21 J) using a 35-mW helium-neon low power laser targeted at the access cavity (n = 4 for each combination). Controls consisted of laser light only (TBO = 0 microgram/mL-1) (n = 4), TBO only (light dose = 0 s) (n = 4), and no treatment (positive control n = 17). Following treatment the canal contents were sampled with sterile paper points, the sample was dispersed in transport medium, serially diluted and cultured on blood agar to determine the number of colony forming units (CFU). RESULTS: The combination of 100 microgram/mL-1 TBO and 600 s (21 J) of laser energy achieved maximum reduction in recovered viable bacteria (5 log10 CFU). TBO at low concentrations (< or =50 microgram/mL-1) was not bactericidal but treatment with 100 microgram/mL-1 TBO alone reduced recovered viable bacteria by 3 log10 CFU. Laser light alone had limited bactericidal effect. No viable bacteria were recovered following treatment with 3% NaOCl. CONCLUSIONS: The combined use of a photosensitizing agent and a low power laser directed at the access cavity was bactericidal to S. intermedius biofilms in root canals but was unable to achieve total kill, unlike 3% NaOCl.

Biofilms↗
PubMed1994

Kt/V, nutritional parameters, serum cortisol, and insulin growth factor-1 levels and patient outcome in hemodialysis.

Despite many technical advances in dialysis care, morbidity and mortality in chronic hemodialysis patients in the United States remains high. In this study, we analyzed the effects of Kt/V, nutritional parameters (serum albumin level, triceps skin-fold thickness, mid-arm muscle circumference, and normalized protein catabolic rate), and predialysis serum cortisol and insulin growth factor-1 levels on predicting morbidity and mortality. The cohort studied consisted of 52 patients recruited from a single outpatient dialysis facility. Cox proportional hazards modeling indicated that only Kt/V predicted subsequent mortality (P = 0.02), while both predialysis cortisol levels (P = 0.03) and Kt/V (P = 0.03) predicted hospitalization. Kaplan-Meier analysis demonstrated that the ability of cortisol levels to predict hospitalization was largely confined to the group with values greater than 22 micrograms/dL predialysis. High serum cortisol levels were correlated with low serum albumin levels and a trend toward low triceps skin-fold thickness and higher normalized protein catabolic rate, suggesting a catabolic state. Both predialysis serum cortisol and insulin growth factor-1 levels were higher than those in age- and sex-matched normal human controls. These results demonstrate the importance role of Kt/V in predicting subsequent hospitalization rates and mortality, and that high predialysis serum cortisol levels correlate with a high hospitalization rate.

Adult↗
PubMed1993

Onchocerca-like lesions induced by the filarioid nematode Cercopithifilaria johnstoni, in its natural hosts and in the laboratory rat.

Histo-pathological analysis of the eyes, ears, skin and associated skeletal muscles of the back of 14 animals infected with a filarioid worm with dermal microfilariae, Cercopithifilaria johnstoni: seven Rattus fuscipes, of which four were naturally infected, two marsupials, Perameles nasuta and Isodon macrourus, and five R. norvegicus. This filarioid nematode induces skin and eye lesions in all the infected animals. These lesions are similar to those described earlier with other filarioid species with dermal microfilariae, such as Monanema martini and Onchocerca volvulus; the pathogeny is similar: microfilariae live inside the lymphatic vessels and their accidental exit gives rise to a localized inflammatory reaction leading to fibrosis. C. johnstoni is particularly interesting because it may be adapted to the laboratory rat, and because the ocular lesions are severe.

Animals↗
PubMed1992

Broiler weight gain and carcass composition when fed diets varying in amino acid balance, dietary energy, and protein level.

Three experiments were conducted with broiler chicks where diet composition varied with respect to dietary protein, energy, and essential amino acid (EAA) balance. Birds fed diets varying widely in EAA balance and protein and energy levels performed differently with respect to percentage carcass fat and protein. The absolute carcass protein deposition remained relatively constant between treatments, but body fat content varied depending on level of energy intake. Although abdominal fat content varied with level of dietary protein and energy, these values did not correlate well with total carcass fat deposition. Carcass fat deposition correlated well with dietary energy intake, which in turn appeared to be influenced by birds eating to satisfy their EAA requirement. With diets of similar EAA balance, birds appeared to have similar EAA intakes rather than similar energy intakes. Birds fed diets with similar EAA levels, but varying widely in level of nonessential amino acids, energy, or both consumed similar amounts of feed and deposited similar amounts of carcass protein. The present data suggest that level and balance of EAA can have a significant effect on feed intake, thereby influencing weight gain and carcass composition.

Adipose Tissue↗
PubMed1990

Weight gain, carcass yield, and composition of large white male turkeys reared to 28 weeks of age on growing and finishing diets with varying levels of dietary protein.

Male, Large White turkeys were reared to 28 wk of age on diets that varied in protein level after 16 wk of age. The diet composition had little effect on weight gain and feed utilization for birds evaluated at 20, 24, and 28 wk of age. The yield and composition of carcass parts were also affected very little by the dietary treatment. Body weight gain over time was fairly consistent to 28 wk of age. Feed utilization declined, especially between 24 and 28 wk of age. Age had a significant effect on the meat yield of the carcass parts. The percentage yield of breast meat was markedly increased from 20 to 28 wk of age, while the percentage yield of thigh and drumstick meat was reduced. While the absolute yield of edible protein increased with age, there was a noticeable increase in fat deposition, especially in the breast and thigh meat with birds that were 28 wk old versus 24 wk old.

Animal Feed↗
PubMed1990

Factors influencing the response of broiler chickens to calcium supplementation of canola meal.

The present study was undertaken to investigate whether broiler chicks fed canola meal, as compared with diets of soybean meal, would respond to a higher level of supplemental calcium. Supplementing canola basal diets and soybean-meal basal diets with additional sulfur from sodium sulfate resulted in little or no change in broiler performance. However, supplementing diets with organic sulfur (cystine) caused a marked decrease in weight gain and feed intake, more severe with a canola diet than with a soybean-meal diet and which could be partially alleviated by increasing the calcium supplementation. A significant cystine-by-calcium interaction showed that feed intake dropped markedly, especially at the higher levels of calcium, as the levels of cystine supplementation increased. Part of the reduced performance, sometimes noted when diets supplemented with canola meal are used, may be due to a reduction in feed intake resulting from an interaction between dietary calcium and sulfur.

Animal Feed↗
PubMed1989

Weight gain and breast yield of large white male turkeys fed diets varying in protein content.

Large White male turkeys were reared in floor pens to 20 wk of age. Diet changes were made every 4 wk, with dietary energy levels kept similar for diets within a period, and changes made in protein levels. Although significant differences in weight were noted at 4 and 8 wk, these diminished with age such that at 20 wk no significant differences were noted. Feed intakes paralleled weight gains. A sample of birds was taken every 4 wk for a measurement of breast meat (excluding skin) and composition. Although changes in dietary protein levels did not affect weight gains to 20 wk of age, breast protein yields were significantly reduced by lowered dietary protein levels. Breast meat varied from 15% of live weight at 4 wk of age to 23% at 20 wk. Protein composition of breast meat varied between 90 and 95% (DM basis), and was estimated to be in excess of 50% of edible carcass protein. With such a high level of edible carcass protein coming from breast meat, it is suggested that yield of breast protein be used as a parameter in determining optimum protein and amino acid requirements of heavy weight turkeys.

Amino Acids, Essential↗
PubMed1987

Rearing early maturing pullets.

A number of experiments were undertaken using White Leghorn pullets to determine the effect of diet and growing treatment on 16-wk body weight and carcass composition. Irrespective of the level of dietary energy, body weight gain and carcass composition appeared to be closely correlated with energy intake of the pullets. Diets as low as 15% protein with and without methionine supplementation resulted in 16-wk body weights similar to those of animals fed diets containing 21% protein, suggesting that protein is not a critical nutrient influencing weight gain of pullets. Pullets fed ad libitum every other day from 12 to 16 wk of age were significantly lighter at 16 wk than pullets full fed a regular grower diet or the regular diet diluted with 20% oat hulls. Pullets must achieve a certain body weight and carcass composition in order to trigger the onset of production. Dietary energy, not protein, appears to be the critical nutrient involved.

Animals↗
PubMed1986

Gonadotropin-releasing hormone (GnRH) physiology in men and women.

The combined approach used in studies of GnRH secretion provided a complimentary array of techniques with which to establish the program of amplitude (dose) and frequency of GnRH secretion in the physiologic state. Normative data in men and women were useful in formulating frequency estimates, which could then be applied to the task of replacement of GnRH in deficient (IHH) individuals. Comparison of the results of therapy with these 'ablation-replacement' models then allowed to arrive closer to the true amplitude or dose of exogenous GnRH required to duplicate the physiologic ideal. In addition to providing insight into the neuroendocrine control of reproduction, these applications provided treatment of various reproductive disorders in men and women. Further expansion of the efforts into other potential defects of endogenous GnRH secretion will ultimately uncover those disorders amenable to therapy.

Adolescent↗
PubMed1982

Management of stage I carcinoma of the uterus.

In an attempt to limit the use of adjuvant irradiation in the management of stage I endometrial carcinoma to high-risk patients only, a protocol was developed that utilizes grading and degree of myometrial invasion as indicators of high risk. From 1974 to 1977, 140 patients at Rochester General Hospital were treated according to this protocol. All patients had total abdominal hysterectomy and bilateral salpingooophorectomy. Adjuvant irradiation was given only to the patients who had grade 3 curettings or greater than one third myometrial invasion. In this series only 20.7% required irradiation. There were no vaginal or pelvic recurrences and the 5-year tumor-free survival rate was 93%.

Adenocarcinoma↗