Search PubMed⌕ Search

Biomedical subjects

J Rogers

Publications and source records attributed to J Rogers.

At least 163 records · Page 9Linked to original sources
PubMed1998

Exercise-induced bronchospasm in high school athletes via a free running test: incidence and epidemiology.

BACKGROUND: Exercise-induced bronchospasm (EIB) affects up to 35% of athletes and up to 90% of asthmatics. Asthma morbidity and mortality have increased over the past several decades among residents of Philadelphia, PA. It is possible that a simple free running test for EIB may serve as a tool to study the factors contributing to recent trends in asthma, and to screen for asthma in athletes in the urban setting. OBJECTIVES: The purposes of this study were to (1) assess a free running test to screen for EIB, and (2) examine prevalence of and epidemiologic factors associated with EIB in high school athletes. DESIGN: Cross-sectional observational study on the incidence and risk factors for EIB. To validate our method and criteria for the diagnosis of EIB, a repeat test was performed on a portion of the athletes. In a randomized single-blinded fashion, 15 athletes who had demonstrated EIB initially received albuterol or placebo prior to a repeat exercise test. SETTING: Community high school athletic facilities. PARTICIPANTS: We studied 238 male high school varsity football players. INTERVENTION: All athletes underwent an acquaintance session with a questionnaire, followed by a 1-mile outdoor run (6 to 8 mins). MEASUREMENTS: Peak expiratory flow (PEF) measurements were determined prior to and 5, 15, and 30 min after exercise. Heart rates (HRs) and dyspnea scores were measured. EIB was defined as a decrease of 15% in PEF at any time point after exercise. Associations of EIB with demographic factors were assessed by univariate and multivariate analyses. RESULTS: Two hundred thirty-eight athletes participated: 92 European-Americans (EA), 140 African-Americans (AA), 5 Hispanics, and 1 Native American. Mean age was 16+/-1 years. Average HR postexercise was 156+/-24 beats/min. Twenty-four (10%) reported a history of treated asthma. The prevalence of EIB among the remaining 214 athletes was 19 of 214 (9%). The rate of EIB among AA athletes was higher than among EA athletes: (17/126 [13%] AA vs 2/82 [2%] EA, p = 0.01). During the validation portion of the study, the placebo-treated group (n = 7) demonstrated a consistent drop in PEF after exercise on repeat testing, with a 16+/-5% fall in PEF on initial testing and a 14+/-13 drop with placebo. In contrast, the fall in airflow in the albuterol-treated athletes (n = 8) following exercise reversed with albuterol treatment, from a 15+/-6% fall in PEF at initial testing to an increase in PEF of 6+/-9% from baseline following albuterol administration. A history of wheezing (p < 0.001), residence in a poverty area (p < 0.0001), race (p = 0.01), remote history of asthma (p < 0.001), and absolute water content of the air on the day tested (p = 0.04) were significantly associated with EIB. By stepwise regression, EIB was most closely associated with a history of wheezing (p = 0.001) and poverty area residence (p = 0.003). CONCLUSIONS: Our findings indicate a substantial rate of unrecognized EIB exists among urban varsity athletes, and suggest that active screening for EIB, especially for students residing in poverty areas, may be indicated to identify individuals at risk for EIB and asthma.

Albuterol↗
PubMed1998

Increased axon growth through astrocyte cell lines transfected with urokinase.

The ability of cells to migrate through tissues depends on their production of a variety of proteases, and the same may be true of growth cones. Urokinase (plasminogen activator) regulates much of the extracellular proteolytic activity, by activating other proteases and as a result of its own proteolytic activity. In order to evaluate the potential role of urokinase as a promoter of axon growth, we have used a plasmid expressing urokinase under a cytomegalovirus promoter to transfect an astrocyte cell line, Neu7, which we have previously shown to provide a poor environment for axon regeneration. Five transfected lines all showed greatly increased ability to promote axon regeneration in both monolayer and three-dimensional cultures. The critical change in the transfected cells was largely within the extracellular matrix, since extracellular matrix laid down by urokinase-secreting cells was more permissive to axon growth than matrix from the parent Neu7 line. The effect was due to urokinase since treatment of the transfected cells with the urokinase inhibitors B623 and B428 rendered both the cells and their matrix much less permissive to axon growth, but did not require plasminogen, since it was blocked neither by serum-free medium nor by plasmin inhibitors.

Animals↗
PubMed1998

Tumour volume: implications in T2/T3 glottic/supraglottic squamous cell carcinoma.

OBJECTIVE: In this study, tumour volume was investigated to determine if it predicts locoregional control of T2/T3 glottic/supraglottic laryngeal carcinoma treated with radiotherapy or surgery. The effect of radiotherapy dosage was also assessed in those patients treated with primary radiotherapy. The ability to identify a subset of patients suitable for primary radiotherapy and, hence, voice preservation based on pretreatment computerized axial tomography (CT) would be valuable. METHOD: The charts of 55 patients referred to the London Regional Cancer Centre (LRCC) between 1988 to 1994 were reviewed. Each presented with a previously untreated T2 or T3 squamous cell carcinoma (SCC) of either the glottic or supraglottic larynx. Tumour volume was calculated from pretreatment CT scans by observers unaware of the clinical data associated with each radiograph. Wilcoxon t test and univariate and multivariate Cox regression analyses were performed. RESULTS: Mean tumour volume differed between those patients treated with radiotherapy and those treated surgically (4.5 cm3 and 11 cm3, respectively; p < .01). Mean tumour volume also differed between T2 and T3 tumours in the primary radiotherapy group (3.8 cm3 and 9.3 cm3, respectively; p < .01). Tumour volume > 4.0 cm3 was a significant predicator of local failure in T2 laryngeal tumours treated with radiotherapy (p < .05). This volume effect was not abolished with increasing radiotherapy dosage. Tumour volume was not a significant predictor of local control in the T3 tumours treated with radiotherapy or when all tumours, irrespective of T stage, that were treated with radiotherapy were considered together. There was no similar volume effect found in the surgical group. CONCLUSIONS: Tumour volume > 4 cm3 predicts local failure in T2 laryngeal tumours treated with radiotherapy regardless of radiotherapy dosage. This volume effect is not seen in those tumours treated with surgery. Inclusion of tumour volume data may eventually augment our current classification system.

Adult↗
PubMed1997

Evidence for engraftment of human bone marrow cells in non-lethally irradiated baboons.

BACKGROUND: Prior to organ harvesting, an attempt was made to modulate the donor's immune responses against prospective xenogeneic recipients by infusion of "recipient-type" bone marrow. METHODS: For this purpose, baboons conditioned with total lymphoid irradiation were given 6 x 10(8) unmodified human bone marrow cells/kg body weight with no subsequent treatment. RESULTS: Animals survived until they were euthanized at 18 months. Using primers specific for human chorionic gonadotrophin gene, the presence of human DNA was confirmed by polymerase chain reaction in the blood of one animal for up to 18 months after cell transplantation; in the other animal, xenogeneic chimerism became undetectable in the blood at 6 months after bone marrow infusion. However, tissue samples obtained from both animals at the time they were euthanized had evidence of donor (human) DNA. Additionally, the presence of donor DNA in individually harvested colonies of erythroid and myeloid lineages suggested that infused human bone marrow cells had engrafted across the xenogeneic barrier in both baboons. CONCLUSIONS: Bone marrow transplantation from human to baboon leads to establishment of chimerism and modulation of donor-specific immune reactivity, which suggests that this strategy could be reproducibly employed to create "surrogate" tolerogenesis in prospective donors for subsequent organ transplantation across xenogeneic barriers.

Animals↗
PubMed1997

Thermodynamic and kinetic basis of interfacial activation: resolution of binding and allosteric effects on pancreatic phospholipase A2 at zwitterionic interfaces.

A general kinetic model for catalysis by interfacial enzymes is developed. It couples the Michaelis-Menten catalytic turnover cycle at the interface with that in the aqueous phase through the distribution equilibria between the interface and the surrounding aqueous phase. Analysis under two limiting conditions fully describes the steady-state kinetics of hydrolysis and resolves the allosteric effects from apparent modes of interfacial activation in terms of the primary rate and equilibrium parameters for pig pancreatic phospholipase A2 (PLA2). One limit is observed in dispersions of anionic phospholipid vesicles, in which intervesicle exchange of enzyme, substrate, and hydrolysis products is absent and reaction occurs only on vesicles containing enzyme. A complete analysis at this highly processive limit, called kinetics in the scooting mode, has been published [Berg et al. (1991) Biochemistry 30, 7283]. Here is reported the analysis in the other limit, PLA2-catalyzed hydrolysis of zwitterionic micelles of short-chain phosphatidylcholines, at which substrate and products are in rapid exchange. Hydrolysis occurs either in bulk aqueous solution with phospholipid monomers or at the micellar interface. Above the critical micelle concentration (cmc), the hydrolysis rate shows a hyperbolic dependence on the bulk substrate concentration present as micelles. This dependence, characterized by the fitting parameters KMapp and VMapp, is analyzed in terms of the primary rate and equilibrium constants. The kinetic analysis is based on the assumption that the microscopic steady-state condition is satisfied because substrate replenishment in the micro-environment of the enzyme is fast relative to the catalytic turnover time. Added NaCl and anionic interface increase the hydrolysis rate in zwitterionic micelles dramatically. The overall interfacial rate enhancement is attributed to three factors: (a) promotion of PLA2 binding by net anionic charge of the interface, (b) enhancement of substrate affinity of PLA2 at the interface (Ks* allostery), and (c) stimulation of the rate-limiting chemical step (kcat* allostery).

Allosteric Regulation↗
PubMed1997

Gossypol modification of Ala-1 of secreted phospholipase A2: a probe for the kinetic effects of sulfate glycoconjugates.

Gossypol is shown to covalently modify secreted phospholipase A2 (PLA2) in the aqueous phase, but not at the interface. A rapid initial noncovalent binding of gossypol is followed by a slow covalent modification of the alpha-amino group of Ala-1 by stoichiometric amounts of gossypol. The rate of modification increases in the presence of calcium, but occupancy of the substrate binding site does not alter the rate. Pancreatic PLA2 is modified at the alpha-amino group of the N terminus to form a Schiff base, which can be stabilized by reduction with borohydride. Residual activity of the gossypol-modified PLA2 from several different sources is about 10%, indicative of impaired catalytic turnover. The half-time for the inactivation is about 10 min, and it is more than 100-fold longer for PLA2 at the interface. Gossypol promotes binding of PLA2 to the interface, and the binding of PLA2 to the interface promotes only the noncovalent binding of gossypol, but not the covalent modification. Gossypol, in conjunction with spectroscopic and kinetic protocols, is used to characterize the kinetic effects of sulfated glycoconjugates, heparin and artery wall proteoglycans, with human inflammatory and pancreatic PLA2.1 The conjugates do not interfere with the binding of PLA2 to the interface or with the catalytic cycle at the interface. The conjugates do not influence the kinetics of modification of PLA2 by gossypol in the aqueous phase, and the enzyme at the interface is not modified in the presence of the conjugates. The conjugates bind to PLA2 at the interface with only a modest effect on the interfacial catalytic turnover without dislodging the bound enzyme. Complex kinetic effects induced by the conjugates are shown to be due to sequestration of PLA2 in the aqueous phase as a high-molecular mass complex, which dissociates with added NaCl.

Alanine↗
PubMed1997

Cisplatin inhibits protein synthesis in rabbit reticulocyte lysate by causing an arrest in elongation.

The mechanism through which cisplatin (cis-diamminedichloroplatinum) inhibits protein synthesis in rabbit reticulocyte lysate was characterized. Cisplatin and transplatin caused a progressive slowing in the rate of protein synthesis culminating in the complete arrest of translation. Inhibition was dependent upon the aquation of the compounds. Addition of eukaryotic initiation factor eIF-2, eIF-2B, cAMP, MgGTP, or dithiothreitol neither prevented nor reversed the inhibition induced by cisplatin, indicating that the mechanism of cisplatin-induced translational inhibition is distinct from the inhibition induced by other toxic heavy metal ions (Hurst, R., Schatz, J. R., and Matts, R. L. (1987) J. Biol. Chem. 262, 15939-15945; Matts, R. L., Schatz, J. R., Hurst, R., and Kagen, R. (1991) J. Biol. Chem. 266, 12695-12702). Analysis of the polyribosome profile of cisplatin-inhibited reticulocyte lysate indicated that cisplatin arrests the elongation stage of protein synthesis. Agarose gel electrophoresis and Northern blot analysis indicated that mRNA and rRNA become crosslinked to form very high-molecular-weight adducts upon extraction of the RNA from polyribosomes of cisplatin-treated lysates. Diethyldithiocarbamate, which reduces the cytotoxicity of cisplatin in vivo, protects protein synthesis in reticulocyte lysate from inhibition by cisplatin. The data suggest that extensive derivatization of reticulocyte lysate RNA by cis- and transplatin results in the arrest of translating ribosomes. Since arrest of translational elongation is a well-defined mechanism of action of several families of toxins, we suggest that it may contribute to the cytotoxic action of cisplatin observed in certain populations of cells.

Animals↗
PubMed1997

Cognitive bladder training in the community.

Following a study trip sponsored through a Cow & Gate scholarship award, the author of this article introduced a cognitive bladder training programme for children with daytime wetting problems. This article looks at how the programme was introduced and describes the components of the programme including educational tools, motivation and bio-feedback. As a result of the programme district-wide, multidisciplinary management guidelines have been introduced.

Biofeedback, Psychology↗
PubMed1997

Phospholipase A2 engineering. Structural and functional roles of the highly conserved active site residue aspartate-99.

The aspartate-99 of secreted phospholipase A2 (PLA2) has been proposed to be critical for the catalytic mechanism and interfacial activation of PLA2. Aspartate-99 connects the catalytic machinery (including the catalytic diad, the putative catalytic waters W5 and W6, and the calcium cofactor) to the hydrogen-bonding network. The latter involves Y52, Y73, the structural water, and the N-terminal region putatively required for the interfacial activation. A triple mutant of bovine pancreatic PLA2 with substitutions aspartate plus adjacent tyrosine residues (Y52,73F/D99N) was constructed, its X-ray structure was determined, and kinetic characteristics were analyzed. The kinetic properties of the D99N mutant constructed previously were also further analyzed. The X-ray structure of the Y52,73F/D99N mutant indicated a substantial disruption of the hydrogen-bonding network including the loss of the structural water similar to that seen in the structure of the D99N mutant published previously [Kumar, A., Sekharudu, Y. C., Ramakrishnan, B., Dupureur, C. M., Zhu, H., Tsai, M.-D., & Sundaralingam, M. (1994) Protein Sci. 3, 2082-2088]. Kinetic analysis demonstrated that these mutants possessed considerable catalytic activity with a k(cat) value of about 5% compared to WT. The values of the interfacial Michaelis constant were also little perturbed (ca. 4-fold lower for D99N and marginally higher for Y52,73F/D99N). The results taken together suggest that the hydrogen-bonding network is not critically important for interfacial activation. Instead, it is the chemical step that is perturbed, though only modestly, in the mutants.

Amino Acid Sequence↗
PubMed1997

Simian T-lymphotropic virus type 1 (STLV-1) infection in wild yellow baboons (Papio hamadryas cynocephalus) from Mikumi National Park, Tanzania.

Serum and peripheral blood leukocytes from wild yellow baboons (Papio hamadryas cynocephalus) were tested for the presence of STLV-1-specific antibodies and proviral DNA. Fourteen of 30 sera tested positive by radioimmunoprecipitation assay (RIPA) with HTLV-1. Among 36 DNA samples tested by PCR 15 were positive by double nested PCR for a fragment of the STLV-1 env gene, the most sensitive assay among PCR tests employed. Of 30 animals that were tested both serologically and by PCR in only 1 case were the results discordant (PCR-positive, antibody-negative). The DNA sequences from env (378 bp), pol (212 bp), and LTR (705 bp) were determined for 5, 5, and 2 Mikumi STLV-1 isolates, respectively. The DNA sequences of Mikumi STLV-1 isolates were virtually identical and phylogenetic analysis revealed that they were clearly distinct from previously published baboon STLV-1 sequences, including those STLV-1 isolates presumed to be from yellow baboons. The results of this study suggest that reliable placement of individual STLV-1 within the PTLV-1 phylogeny requires genomic sequences of STLV-1 isolates from wild animals whose taxonomic identity and geographical origin are firmly established and that the LTR is the genomic region of STLV-1 which is the most informative for cladistic analysis of these viruses.

Animals↗
PubMed1997

An exploration of why preschoolers perform differently than do adults in audiovisual speech perception tasks.

Preschoolers' perception of audiovisual speech is considerably less influenced by visual information than adults'. We test the hypothesis that experience correctly producing consonants plays a role in developing the underlying representation which mediates the perception of visible speech. We divided preschoolers into two groups: those who made substitution errors and those who did not. Using a newly developed methodology, we tested substituters, nonsubstituters, and adults in an auditory-only condition, a visual-only condition, and an audiovisual condition. There were no differences among groups in the auditory-only condition. Overall, children still showed less visual influence than adults. Among the children, substituters were poorer at lip-reading in the visual-only condition and showed less visual influence on the incongruent audiovisual tokens than did nonsubstituters. These results support our hypothesis that experience correctly producing consonants plays a role in the elaboration of the underlying representation.

Adult↗
PubMed1997

Port site electrosurgical (diathermy) burns during surgical laparoscopy.

BACKGROUND: Direct and capacitive coupling of diathermy current have been reported as causes of occult injury during surgical laparoscopy. METHODS: In order to determine the incidence of electrosurgical injury adjacent to metal and plastic cannulas, skin biopsies at 19 port sites used for monopolar electrosurgery were analyzed for coagulative necrosis. Prior to surgery the cannulas were randomized to either metal or plastic. RESULTS: Coagulative necrosis was observed at nine electrosurgery port sites compared to only one control (chi2 = 4.872; df = 1; 0.05 > p > 0.02). Plastic cannulas afforded no greater protection from skin burns than metal cannulas. CONCLUSIONS: Burns may be the result of direct or capacitive coupling to metal cannulas or capacitive coupling to the skin edge across plastic cannulas. The potential exists for burns to other tissues also in close proximity to a cannula used for electrosurgery.

Biopsy↗
PubMed1997

Active surveillance after orchiectomy for nonseminomatous testicular germ cell tumors: late relapse may occur.

OBJECTIVES: To review the outcome of men with Stage I nonseminomatous germ cell tumors managed with a policy of active surveillance following orchiectomy. METHODS: The clinical records of all men with Stage I nonseminomatous germ cell tumors seen at Royal Prince Alfred Hospital, Australia between 1982 and 1995 were reviewed. Data were obtained concerning the histologic type of tumor, levels of serum tumor markers, relapse and subsequent treatment, and survival. RESULTS: Seventy-seven patients were entered into the active surveillance protocol between 1982 and 1995. With a minimum follow-up of 2 years, 27 (35%) have relapsed, with a median time to relapse of 5 months. Two late relapses occurred at 37 and 57 months after diagnosis. Relapses occurred most commonly in the retroperitoneal lymph nodes, with the lungs the second most common site. Following treatment with chemotherapy and surgery, all patients achieved complete remission, with 1 patient subsequently relapsing and ultimately dying of progressive tumor. One other patient died of acute myeloid leukemia, thought to be secondary to chemotherapy. Overall, 75 patients (97%) remain alive and free of disease. CONCLUSIONS: Active surveillance is a safe and effective approach to the management of Stage I nonseminomatous germ cell tumors. Although most relapses occur within the first 2 years, late relapses may occur.

Adolescent↗
PubMed1997

Nephrogenic adenoma of the bladder in renal transplant and non-renal transplant patients: a review of 22 cases.

OBJECTIVES: To review diagnoses of nephrogenic adenoma and in particular to evaluate its association with transitional cell carcinoma (TCC) of the bladder and its relationship to renal transplantation. METHODS: A retrospective review of 22 cases of nephrogenic adenoma (NA) diagnosed between 1989 and 1996 was conducted, 7 of which were in renal transplant patients. Data collected in each case included demographic details, predisposing factors, associated urologic pathology, mode of presentation, cystoscopic finding, management, and follow-up. RESULTS: There was a 3:1 predominance of men. Mean follow-up was 21.4 months (range 3 to 50). Six patients (27%) had one or more recurrences. All 22 patients had some form of previous bladder insult or surgery, including recurrent urine infections, urinary tract instrumentation, placement of ureteric stents, cystodiathermy, and open bladder surgery. Six cases were associated with TCC of the bladder, of which 4 had NA lesions directly over or close to the site of previous fulguration. In 4 patients, there was a temporal relationship between the administration of intravesical doxorubicin hydrochloride or bacille Calmette-Guérin (BCG) and the onset of NA lesions. One case was associated with an inverted papilloma that had not been described before. In 7 renal transplant cases, 3 lesions were found contralateral to the side of the ureterovesical anastomosis. All 22 cases were benign histologically, but one NA was found within a low-grade baldder TCC. Nineteen cases were followed up regularly with no malignant transformation. Three patients were lost to follow-up. CONCLUSIONS: This study has demonstrated an association between NA and bladder cancer. Patients with NA, especially those treated with intravesical chemotherapy or BCG, should have regular cystoscopies. Fulguration or transurethral resection appear to be sufficient treatment. No renal transplant patients had vesical TCC and NA simultaneously. Neither immunosuppression nor ureterovesical anastomosis appeared to be a significant predisposing factor in the transplant patients.

Adenoma↗
PubMed1997

Homoeopathy and the treatment of alcohol-related problems.

This paper discusses the use of homoeopathy in the work of a community alcohol team, focusing on the application of homoeopathy for treating sleep disorder in alcohol-dependent clients. This work is placed in the context of the historical use of homoeopathy for treating 'alcoholism' and of the increasing use of complementary therapies in mainstream health care and in drug and alcohol agencies. Issues of research methodology and measurement of outcomes are examined. Examples of some specific homoeopathic treatments, together with a case report, are given to illustrate the potential uses of this form of therapy. It is concluded that homoeopathy can provide a valid and effective therapy to help clients break the cycle of dependence on alcohol. A number of further research questions arise and much clinical and research work needs to be done by those attempting to bring complementary therapies into drug and alcohol treatment.

Alcoholism↗
PubMed1997

Zamifenacin (UK-76, 654) a potent gut M3 selective muscarinic antagonist, reduces colonic motor activity in patients with irritable bowel syndrome.

BACKGROUND: Zamifenacin is a new potent gut M3 selective muscarinic antagonist developed for possible use in irritable bowel syndrome. METHODS: In this multicentre, double-blind, parallel group, placebo-controlled study, the effect of a single dose of zamifenacin 10 mg or 40 mg on both fasting (30 min) and fed (60 min) colonic motor activity was assessed in 36 patients with irritable bowel syndrome (aged 25-68 years; 19 male). Colonic motility was recorded using a five-channel solid-state catheter introduced by colonoscopy to a depth of 35 cm in an unprepared colon. RESULTS: Zamifenacin 40 mg profoundly reduced colonic motility, particularly after the meal (P < 0.05). This was reflected by a significant reduction in the mean amplitude of contractions, number of contractions, percentage duration of contractions, activity index and the motility index (P < 0.05). A smaller reduction in all the motility parameters was obtained with 10 mg zamifenacin, but these changes were not statistically significant. Three patients each on placebo and zamifenacin reported side-effects, but these were mild and transient. CONCLUSION: A single 40 mg dose of zamifenacin significantly reduces colonic motility in irritable bowel syndrome patients without significant antimuscarinic effects. The results of this study confirm that the concept of developing selective antimuscarinic agents may be a promising approach to the treatment of irritable bowel syndrome. Not only would such compounds benefit from not having the usual side-effects of anticholinergics but they might also offer much more in the way of dose flexibility.

Adult↗