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Biomedical subjects

J R Roberts

Publications and source records attributed to J R Roberts.

At least 19 recordsLinked to original sources
PubMed2007

Comparative histopathology of two serotypes of infectious bronchitis virus (T and n1/88) in laying hens and cockerels.

The comparative and sequential histopathology of different tissues of unvaccinated laying hens and cockerels were studied in chickens exposed to T and N1/88 strain of infectious bronchitis virus (IBV). The Harderian gland and trachea of hens and cockerels in both T- and N1/88-infected groups were damaged to a similar extent. The cecum was unaffected for both strains of IBV in both hens and cockerels. The sequential histopathological changes in hens revealed that IBV multiplies initially in the Harderian gland, then in the tracheal mucosa and simultaneously in the kidney and regions of the oviduct such as the magnum, tubular shell gland, and shell gland pouch. In cockerels, IBV multiplies first in the Harderian gland, then simultaneously in the trachea and kidney. Overall, the severity and persistence of lesions were greater in the kidneys of T-infected hens as compared with N1/88-infected hens. However, pathological changes in the kidney were mild in T- and N1/88-infected cockerels.

Animals↗
PubMed2007

Histopathology of two serotypes of infectious bronchitis virus in laying hens vaccinated in the rearing phase.

The comparative histopathology of 2 different strains of infectious bronchitis virus (T and N1/ 88) in vaccinated hens was studied at 110 wk of age. The Harderian gland showed similar histopathology in T- and N1/88-infected hens. The trachea and kidney of challenged vaccinated hens were protected to a moderate extent, but the oviduct was protected to only a small extent. The severity and persistence of lesions were greater in tubular shell gland, shell gland pouch, and kidney of the T-infected hens, whereas, for the magnum, N1/88 had a greater effect.

Animals↗
PubMed2006

Effects of commercial enzyme preparations on egg and eggshell quality in laying hens.

1. Four different commercial enzyme products were added to standard commercial layer diets, based on barley, wheat or triticale. 2. Diets were fed to 4 different strains of commercial laying hen: ISA Brown, Hy-Line CB, Tegel SB2 and Tegel HiSex. 3. Diets were given for 5 weeks prior to measurements of egg and eggshell quality. 4. The inclusion of commercial enzyme products in the diets had no effect on egg weight. 5. Positive effects of the enzymes were: improved eggshell breaking strength, shell weight, percentage shell and shell thickness for the barley-based diet and increased eggshell breaking strength for two of the enzymes with the wheat-based diets. 6. Negative effects of the enzyme products were slightly lighter coloured eggshells and reduced albumen quality for the barley-based diet and for two enzymes with the wheat-based diet. 7. The addition of commercial enzyme preparations had no main effect on egg and eggshell quality for the triticale-based diet, except for effects on yolk colour. 8. Yolk colour was lower than control for enzyme 3 in all diets and for enzyme 4 with the barley- and wheat-based diets. 9. Further investigation is required to elucidate the specific enzyme components that influence egg quality.

Animal Feed↗
PubMed2006

Assessment of the impact sound in golf putting.

The influence of impact sound in putting on players' perceptions of "feel" is explored in this paper. Tests were conducted to investigate the impact sound characteristics of five different ball types using two different putter types. The first test studied the impact sound of purely the ball, while the second test investigated the influence of putter construction and impact location on impact sound for the different ball types. Trends were found between sound spectra peaks in the 2 - 4 kHz range and the compression values of the balls. In addition, frequency content was more dependent on putter type and impact location than on ball construction in the 0 - 2 kHz range. The final test employed a paired comparison technique to investigate players' perceptions of sharpness and loudness of impact sound, ball speed from the clubface and ball hardness. Relationships between the subjective data and the sound characteristics of the balls were then examined. It was found that the ball the players' perceived to have the sharpest and loudest sound, to feel the hardest and to come off the clubface the quickest also had the largest calculated values of loudness and sharpness and had a spectral peak at a higher frequency than the other balls.

Auditory Perception↗
PubMed2001

Induction chemotherapy increases perioperative complications in patients undergoing resection for non-small cell lung cancer.

BACKGROUND: Neoadjuvant chemotherapy before resection is the standard of care for stage IIIA non-small cell lung cancer in many institutions. Further, neoadjuvant therapy is being studied in earlier stage lung cancer and may be applied more broadly in the future. There is little information about the effect of preoperative chemotherapy on the perioperative complications and mortality after lung resection. METHODS: All patients undergoing anatomic resection after neoadjuvant chemotherapy by a single surgeon at a single institution were compared with patients undergoing similar resections without preoperative chemotherapy. Complications were analyzed as life-threatening (pneumonia, emergency surgery, transfer to the intensive care unit, or intubation), major (prolonging hospital stay but not necessarily dangerous), and minor. The incidence of life-threatening complications, major complications, reintubation, tracheostomy, and mortality were analyzed to determine whether neoadjuvant chemotherapy might have an effect on these complications. Mortality was defined as hospital mortality. Two-tailed Student's t test was used to analyze differences in means and chi2 to determine differences in proportions. Differences less than 0.05 were considered significant. RESULTS: Thirty-four patients underwent resection after neoadjuvant chemotherapy, and 67 patients underwent resection without preoperative therapy. No differences between the two groups in age, pulmonary function, or comorbid diseases were found. The patients receiving chemotherapy did have a more advanced stage (2.52 versus 1.55, p < 0.0001). Striking increases were found in incidence of life-threatening complications (6.0% versus 26.5%, p = 0.0036), major complications (19.4% versus 47.1%, p = 0.0037), reintubation (3.0% versus 17.6%, p = 0.0093), and tracheostomy (0% versus 11.8%, p = 0.0042) in those patients who received preoperative chemotherapy. There was no hospital mortality. However, 2 (neoadjuvant) patients died within 90 days after discharge from the hospital of pneumonia and pulmonary embolus. This difference was also significant (0% versus 5.89%, p = 0.045). CONCLUSIONS: Neoadjuvant carboplatin and Taxol increased the perioperative life-threatening complications in this cohort of patients compared with a similar cohort undergoing operations by the same surgeon in the same institution. The most common life-threatening complication in patients receiving induction chemotherapy was the failure to respond to antibiotics given for pneumonia. Strategies to prevent these complications will be important, especially if chemotherapy before resection becomes the standard for earlier stages of non-small cell lung cancer.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2001

Pesticides in children.

Children are exposed to a wide range of pesticides, including insecticides, herbicides, fungicides, and rodenticides. They differ from adults in their exposures and responses to exposures. Acute and chronic toxicity are discussed, and important chronic effects, such as carcinogenesis, endocrine disruption, and neurodevelopment effects are reviewed. The state of laws and regulations are also discussed. Recommendations are made to pediatricians regarding treatment and advising families regarding avoidance of pesticide exposures and their effects.

Child↗
PubMed2001

Strain-related differences of nonspecific respiratory defense mechanisms in rats using a pulmonary infectivity model.

A number of animal studies have assessed pulmonary host defense mechanisms by inoculating the lungs with the bacterial agent, Listeria monocytogenes. Most studies use only a single strain of the animal to be tested; however, strain-related differences in responsiveness to pulmonary toxicants have been well documented. It was the goal of this current investigation to measure the pulmonary defense responses of two different strains of rats in a lung infectivity model. Fischer 344 (F344) and Sprague-Dawley (SD) rats were instilled intratracheally with 5 x 10(3) or 5 x 10(5) L. monocytogenes, and the effect on mortality, lung injury and inflammation, pulmonary bacterial clearance, and alveolar macrophage (AM) function was determined at 3, 5, and 7 days after bacteria treatment. Pulmonary inoculation with the higher (5 x 10(5) L. monocytogenes) dose proved to be highly pneumotoxic to the F344 rats as evidenced by an increase in mortality and more severe lung injury and inflammation when compared with the SD rats. After intratracheal instillation with the lower (5 x 10(3) L. monocytogenes) dose, pulmonary bacterial clearance was slowed and an increase in pulmonary responsiveness was observed for the F344 rats as compared to the SD rats. Specifically, the total number of neutrophils recovered from the lungs and tumor necrosis factor-alpha secreted by AMs were elevated for the F344 group throughout the 7 days, while cellular chemiluminescence, an index of reactive oxygen species production, and lung albumin and lactate dehydrogenase, indicators of injury, were increased at 3 and 5 days after bacterial instillation. This study demonstrated that respiratory defense function was compromised in F344 rats as evidenced by elevated mortality, slowed pulmonary bacterial clearance, and altered AM function. F344 rats may then represent a sensitive model for the examination of respiratory defense mechanisms after bacterial challenge.

Albumins↗
PubMed2001

Time required for blood lead levels to decline in nonchelated children.

OBJECTIVE: To determine the time for a decline in blood lead to less than 10 microg/dL in nonchelated children who are enrolled in case management. STUDY DESIGN: Retrospective analysis of venous blood lead data of lead-poisoned children followed in a case management program designed to decrease lead exposure. Children were excluded if their blood lead had not yet declined to less than 10 microg/dL, if they received chelation therapy, or if they had not received follow-up for more than 15 months. We calculated the time between peak elevation of lead and decline to less than 10 microg/dL. Data were categorized based on the child's peak blood lead and season in which their peak blood lead occurred. Data were analyzed using ANOVA and linear regression. Kaplan-Meier survival analysis was used to describe data in population form. RESULTS: 579 patients were included in the analysis. Blood leads of 25-29, 20-24, 15-19, and 10-14 microg/dL required 24.0, 20.9, 14.3, and 9.2 months, respectively, to decline to less than 10 microg/dL. For continuous data, a linear relationship was described by the following equation: Time (# of months required to achieve a blood lead less than 10 microg/dL) = 0.845 x peak lead; p < 0.0001. Kaplan-Meier curves complement the findings in a population-based fashion. CONCLUSIONS: The mean time for blood lead to decline was linearly related to the peak in blood lead. The time for 50% of the blood lead to decline to less than 10 microg/dL was not linear and varied with peak lead.

Chelation Therapy↗
PubMed2001

Cadmium-induced cell transformation and tumorigenesis are associated with transcriptional activation of c-fos, c-jun, and c-myc proto-oncogenes: role of cellular calcium and reactive oxygen species.

The molecular mechanisms of carcinogenesis by cadmium were studied using BALB/c-3T3 cell transformation and nude mouse tumorigenesis models. BALB/c-3T3 cells transformed with cadmium chloride were subcutaneously injected into nude mice to develop tumors and the cell lines derived from these tumors were used in the present study. The proto-oncogenes c-fos and c-jun were overexpressed in 100% (10 out of 10) of the cell lines, while a statistically significant overexpression of c-myc was observed in 40% (4 out of 10) of the cell lines. Analysis of tumor cells stained with fluorescent dyes specific for reactive oxygen species revealed that these cells possessed markedly higher levels of superoxide anion and hydrogen peroxide compared with the nontransformed cells. Similarly, the intracellular calcium level was higher in the tumor cells compared with the nontransformed cells. Overexpression of the proto-oncogenes in these cells was blocked by treating the cells with superoxide dismutase, catalase, and 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetra acetoxy methyl ester (BAPTA/AM), which are scavengers of superoxide anion, hydrogen peroxide, and calcium, respectively. This confirmed that the overexpression of the proto-oncogenes in the tumor cells required elevated intracellular levels of reactive oxygen species and calcium. In addition to the scavengers of reactive oxygen species and calcium, inhibitors specific for transcription (actinomycin D), protein kinase C (RO-31-8220), and MAP kinase (PD 98059) also blocked the cadmium-induced overexpression of the proto-oncogenes in the tumor cells. Exposure of the nontransformed BALB/c-3T3 cells to 20 microM cadmium chloride for 1 h caused elevated intracellular levels of superoxide anion, hydrogen peroxide, and calcium, with corresponding increases in the expression levels of c-fos, c-jun, and c-myc. As in the case of the tumor cells, treating the nontransformed cells with the various modulators prior to their exposure to cadmium chloride resulted in inhibition in the expression of the proto-oncogenes. Based on these data, we conclude that the cadmium-induced overexpression of cellular proto-oncogenes is mediated by the elevation of intracellular levels of superoxide anion, hydrogen peroxide, and calcium. Further, the cadmium-induced overexpression of the proto-oncogenes is dependent on transcriptional activation as well as on pathways involving protein kinase C and MAP kinase.

3T3 Cells↗
PubMed2001

Effect of age on respiratory defense mechanisms: pulmonary bacterial clearance in Fischer 344 rats after intratracheal instillation of Listeria monocytogenes.

STUDY OBJECTIVES: To examine the lung defense mechanisms of both young and aged rats before and after pulmonary challenge with a bacterial pathogen. DESIGN: Male Fischer 344 rats, either 2.5 months or 20 months of age, were intratracheally inoculated with 5 x 10(3), 5 x 10(4), or 5 x 10(5) Listeria monocytogenes, and the effects on mortality, lung inflammation, pulmonary bacterial clearance, alveolar macrophage (AM) function, and T-lymphocyte characterization were determined. MEASUREMENTS AND RESULTS: In noninfected control animals, the older rats had lower numbers of AMs on lavage and a lower percentage of total T, CD4+, and CD8+ cells. No difference was observed between noninfected young and old rats in AM function, assessing both chemiluminescence and nitric oxide (NO) production. After bacterial challenge, aged rats exhibited an increase in mortality, pulmonary infection, and edema, and lung lesions, which were more extensive than those observed in the younger rats. Interestingly, AM chemiluminescence was enhanced, while AM NO, a highly important antibacterial defense product, was abrogated in the aged rats as compared to the young rats. CONCLUSIONS: This study demonstrated that advanced age is associated with alterations in lung defense mechanisms and increased susceptibility to pulmonary bacterial infection marked by elevated mortality, slowed pulmonary bacterial clearance, and altered AM function, specifically a decrease in NO production. These observations are indicative of reduced pulmonary defense function in an older population of rats.

Aging↗
PubMed2000

Modeling and functional analysis of the interaction between von Willebrand factor A1 domain and glycoprotein Ibalpha.

Binding of the von Willebrand factor (vWF) A1 domain to the glycoprotein (GP) Ib-IX-V complex mediates platelet adhesion to reactive substrates under high shear stress conditions, a key event in hemostasis and thrombosis. We have now used the known three-dimensional structure of the A1 domain to model the interaction with the GP Ibalpha sequence 271-279, which has previously been implicated in ligand binding. Docking procedures suggested that A1 domain residues in strand beta3 and preceding loop (residues 559-566) as well as in helix alpha3 (residues 594-603) interact with Asp residues 272, 274, 277 and sulfated Tyr residues 278 and 279 in GP Ibalpha. To verify this model, 14 mutant A1 domain fragments containing single or multiple side chain substitutions were tested for their ability to mediate platelet adhesion under flow. Each of the vWF residues Tyr(565), Glu(596), and Lys(599) proved to be strictly required for A1 domain function, which, in agreement with previous findings, was also dependent on Gly(561). Moreover, an accessory functional role was apparent for a group of positively charged residues, including Arg at positions 629, 632, 636 and Lys at positions 643 and 645, possibly acting in concert. There was, however, no evidence from the model that these residues directly participate in forming the complex with GP Ibalpha. These results provide a partial model of the vWF-GP Ibalpha interaction linked to the manifestation of functional activity in platelet adhesion.

Amino Acids↗
PubMed2000

Cutaneous glands in the Australian hylid Litoria caerulea (Amphibia, Hylidae).

Ultrastructure of cutaneous glands is described in the Australian hylid Litoria caerulea. Three main types of glands could be distinguished in both ventral and dorsal skin: mucous, serous or granular, and lipid glands. Both mucous, and to some extent, serous glands show a PAS-positive reaction. Some of the granular-serous glands react to lipid staining. In addition, a very large gland confined to the dorsal skin of the head reacts to lipid staining. Apparently more than one type of dermal gland is involved in lipid secretion. The subject of skin lipid secretion is discussed in relation to the ecophysiological adaptations of this xeric-inhabiting frog.

Animals↗
PubMed2000

Induction chemotherapy before surgery for early-stage lung cancer: A novel approach. Bimodality Lung Oncology Team.

OBJECTIVE: This phase II trial assessed the feasibility, as measured by response rate, toxicity, resectability rate, and surgical morbidity and mortality rates, of perioperative paclitaxel and carboplatin chemotherapy in patients with early-stage non-small cell lung carcinoma. METHODS: All patients required negative mediastinoscopy results and adequate medical parameters to undergo induction chemotherapy and an operation. Superior sulcus patients were excluded. Chemotherapy consisted of paclitaxel 225 mg/m(2) over 3 hours and carboplatin (area under the curve = 6) every 21 days for 2 cycles preoperatively. Three postoperative cycles of chemotherapy were planned for patients undergoing complete resection. RESULTS: Between June 1996 and July 1998, 94 patients were entered into the study. Sixty-five (69%) were men, and the median age was 64 years (range, 34-79 years). After induction chemotherapy, 53 of 94 (56%; 95% confidence interval, 46%-67%) had a major objective response, 88 (94%) underwent surgical exploration, and 81 (86%; 95% confidence interval, 78%-92%) underwent complete resection. Reasons for not undergoing an operation included disease progression (n = 3), clinically unresectable status (n = 1), death (n = 1), and patient lost to follow-up (n = 1). Two postoperative deaths occurred. Six (6%; 95% confidence interval, 0%-13%) pathologic complete responses were observed. Ninety (96%) patients received the planned preoperative chemotherapy versus 45% receiving postoperative chemotherapy. No unexpected chemotherapy or surgical morbidity occurred. The 1-year survival is currently estimated at 85%, and the median survival has not yet been reached. CONCLUSIONS: Induction chemotherapy with paclitaxel and carboplatin is feasible and produces a high response rate with acceptable morbidity and mortality rates in early-stage non-small cell lung carcinoma. A prospective randomized trial comparing 3 cycles of induction chemotherapy and surgery with surgery alone in early-stage non-small cell lung carcinoma is planned.

Adult↗