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Biomedical subjects

W A Brown

Publications and source records attributed to W A Brown.

At least 19 recordsLinked to original sources
PubMed2005

Reflection absorption infrared spectroscopy and temperature programmed desorption investigations of the interaction of methanol with a graphite surface.

Reflection absorption infrared spectroscopy (RAIRS) and temperature programmed desorption (TPD) have been used to investigate the adsorption of methanol (CH(3)OH) on the highly oriented pyrolytic graphite (HOPG) surface. RAIRS shows that CH(3)OH is physisorbed at all exposures and that crystalline CH(3)OH can be formed, provided that the surface temperature and coverage are high enough. It is not possible to distinguish CH(3)OH that is closely associated with the HOPG surface from CH(3)OH adsorbed in multilayers using RAIRS. In contrast, TPD data show three peaks for the desorption of CH(3)OH. Initial adsorption leads to the observation of a peak assigned to the desorption of a monolayer. Subsequent adsorption leads to the formation of multilayers on the surface and two TPD peaks are observed which can be assigned to the desorption of multilayer CH(3)OH. The first of these shows a fractional order desorption, assigned to the presence of hydrogen bonding in the overlayer. The higher temperature multilayer desorption peak is only observed following very high exposures of CH(3)OH to the surface and can be assigned to the desorption of crystalline CH(3)OH.

Journal Article↗
PubMed2004

Use of oesophagogastroscopy to assess the response of oesophageal carcinoma to neoadjuvant therapy.

BACKGROUND: Approximately 25 per cent of patients with oesophageal cancer who undergo neoadjuvant chemoradiotherapy have no evidence of tumour in the resected specimen (complete pathological response). Those who do not respond have a poor 5-year survival compared with complete responders, regardless of whether or not they undergo surgery. Selecting for surgery only those who have a response to neoadjuvant therapy has the potential to improve overall survival as well as to rationalize the management of non-responders. This study assessed the accuracy of oesophagogastroscopy in this setting. METHODS: A prospective database of 804 patients undergoing oesophageal resection for carcinoma was reviewed. Endoscopic assessment of the response to neoadjuvant therapy in 100 consecutive patients was compared with the pathological assessment of response. The survival for each level of response was compared. RESULTS: At endoscopy 30 patients were considered to have had a complete response. This was confirmed pathologically in 15 patients. Survival was improved in those with a pathologically confirmed complete response (3-year survival rate 62.4 (s.e. 12.9) per cent) compared with non-responders (16.3 (s.e. 6.6) per cent). Those with microscopic residual disease also had an improved 3-year survival rate (46.3 (s.e. 12.2) per cent); however, oesophagogastroscopy failed to identify this subset. CONCLUSION: Oesophagogastroscopy may be useful in the assessment of tumour response to neoadjuvant therapy. However, owing to its poor accuracy patients should not be excluded from further therapeutic intervention on the basis of this assessment alone.

Adenocarcinoma↗
PubMed2004

Hydrolysis of lactose in whey permeate for subsequent fermentation to ethanol.

Fermentation of lactose in whey permeate directly into ethanol has had only limited commercial success, as the yields and alcohol tolerances of the organisms capable of directly fermenting lactose are low. This study proposes an alternative strategy: treat the permeate with acid to liberate monomeric sugars that are readily fermented into ethanol. We identified optimum hydrolysis conditions that yield mostly monomeric sugars and limit formation of fermentation inhibitors such as hydroxymethyl furfural by caramelization reactions. Both lactose solutions and commercial whey permeates were hydrolyzed using inorganic acids and carbonic acid. In all cases, more glucose was consumed by secondary reactions than galactose. Galactose was recovered in approximately stoichiometric proportions. Whey permeate has substantial buffering capacity-even at high partial pressures (>5500 kPa[g]), carbon dioxide had little effect on the pH in whey permeate solutions. The elevated temperatures required for hydrolysis with CO2-generated inhibitory compounds through caramelization reactions. For these reasons, carbon dioxide was not a feasible acidulant. With mineral acids reversion reactions dominated, resulting in a stable amount of glucose released. However, the Maillard browning reactions also appeared to be involved. By applying Hammet's acidity function, kinetic data from all experiments were described by a single line. With concentrated inorganic acids, low reaction temperatures allowed lactose hydrolysis with minimal by-product formation and generated a hexose-rich solution amenable to fermentation.

Animals↗
PubMed2001

Symptom reduction and suicide risk in patients treated with placebo in antidepressant clinical trials: a replication analysis of the Food and Drug Administration Database.

The assumption that depressed patients who are assigned to placebo in antidepressant clinical trials are exposed to substantial morbidity and mortality has not been based on research data. Because of worldwide concern about placebo use and the implications of our earlier findings of no increased suicide risk in placebo-treated patients, we conducted a replication study in a new patient sample. We assessed suicide risk and symptom reduction among placebo-treated patients participating in antidepressant clinical trials for two recently approved antidepressants, venlafaxine ER and citalopram, which were unavailable during our previous study. Among 23,201 participant patients, 32 committed suicide and 172 attempted suicide. Rates of suicide and attempted suicide did not differ significantly among the placebo- and drug-treated groups. Based on patient exposure years, annual rates of suicide and attempted suicide were 0.5 and 6.7% with placebo, 0.9% with active comparator (rates for attempted suicide are unavailable), and 0.6 and 6.3% with investigational antidepressants. Symptom reduction was 47.9% with investigational drugs (n = 1172), 47.5% with active comparators (n = 161), and 35.5% with placebo (n = 606). These data may inform discussions about the use of placebo in antidepressant clinical trials.

Adult↗
PubMed2001

Inhibition of beta-catenin translocation in rodent colorectal tumors: a novel explanation for the protective effect of nonsteroidal antiinflammatory drugs in colorectal cancer.

In a rodent colorectal cancer model, nonsteroidal antiinflammatory drugs reduce tumor mass by increasing the rate of tumor cell apoptosis and decreasing proliferation. We have examined beta-catenin as a potential target for these agents in colorectal cancer. Carcinogen-treated rats were treated for 23 weeks with a range of nonsteroidal antiinflammatory drugs. Control animals received vehicle alone. Intracellular beta-catenin was examined using immunohistochemistry. In tumors from untreated animals, staining was seen in the cytoplasm and nucleus (median 24% of nuclei). The frequency of nuclear beta-catenin staining correlated directly with the volume of tumor and inversely with the rate of apoptosis. In tumors from treatment groups, the cytoplasmic staining for beta-catenin was unchanged; however, nuclear staining was absent except in the celecoxib group, where it was reduced to a median of 14%. Colorectal tumors from animals treated with NSAIDs show reduced levels of nuclear beta-catenin immunoreactivity.

1,2-Dimethylhydrazine↗
PubMed2001

Non-steroidal anti-inflammatory drugs with activity against either cyclooxygenase 1 or cyclooxygenase 2 inhibit colorectal cancer in a DMH rodent model by inducing apoptosis and inhibiting cell proliferation.

BACKGROUND: Standard non-steroidal anti-inflammatory drugs (NSAIDs) reduce the risk of colorectal cancer by 40-60% but the mechanism by which this occurs is uncertain. Selective cyclooxygenase 2 inhibitors are potentially ideal chemopreventive agents as they are less toxic than standard NSAIDs. No study has compared the efficacy of these drugs at clinically relevant doses in a tumour model. AIMS: To assess the efficacy of a range of NSAIDs with varying activity against the two cyclooxygenase isoforms in a rodent colorectal carcinogen model at anti-inflammatory doses and to explore the effect of NSAIDs on the rate of tumour apoptosis and proliferation. METHODS: Colorectal tumours were induced in six week old Sprague-Dawley rats with five weekly doses of 1,2 dimethylhydrazine. Test agents were: indomethacin 2 mg/kg/day, meloxicam 0.6 mg/kg/day, celecoxib 6 mg/kg/day, and sulindac sulphone 40 mg/kg/day. Sulindac was tested at its chemoprotective dose of 20 mg/kg/day. After 23 weeks the number and volume of tumours per animal were recorded. Histology was performed. Tumour apoptosis was quantified on haematoxylin-eosin sections. Tumour proliferation was quantified using an immunohistochemical stain for bromodexoyuridine incorporation. RESULTS: Test agents effectively reduced the number and volume of tumours developing in the treatment period. In all groups there was an increase in the rate of tumour apoptosis and a reduced rate of proliferation. CONCLUSIONS: These data suggest that the chemopreventive effect of NSAIDs is independent of their cyclooxygenase inhibitory profile. One potential mechanism for their action may be through induction of apoptosis and inhibition of proliferation.

Adenocarcinoma↗
PubMed2001

Symptom reduction and suicide risk among patients treated with placebo in antipsychotic clinical trials: an analysis of the food and drug administration database.

OBJECTIVE: The assumption that psychotic patients assigned to placebo in clinical trials of antipsychotics are exposed to substantial morbidity and mortality is not based on data about what actually happens to such patients. This study assesses symptoms and risks of suicide and suicide attempts in psychotic patients assigned to receive placebo in clinical trials. METHOD: The authors used the Food and Drug Administration database to assess suicides, suicide attempts, and psychotic symptom reduction in clinical trials of three new antipsychotics. RESULTS: Among 10,118 participating patients, 26 committed suicide and 51 attempted suicide. Rates of suicide and attempted suicide did not differ significantly between the placebo-treated and the drug-treated groups. Annual rates of suicide and attempted suicide based on patient exposure years were 1.8% and 3.3%, respectively, with placebo; 0.9% and 5.7% with an established antipsychotic; and 0.7% and 5.0% with a new antipsychotic. Symptom reduction was 16.6% with new antipsychotics (N=1,203), 17.3% with established antipsychotics (N=261), and 1.1% with placebo (N=462). CONCLUSIONS: These data may help inform discussions about the use of placebo in antipsychotic clinical trials.

Antipsychotic Agents↗
PubMed2000

Modeling of biological processes using self-cycling fermentation and genetic algorithms.

Self-cycling fermentation (SCF) was coupled with a genetic algorithm (GA) to provide a simple system for evaluating biological models. The SCF provided the necessary system excitation and data "richness" required to completely define the fitted biological models. The solution scheme based on the GA avoided the computational difficulties often associated with calculus-based nonlinear regression techniques, resulting in rapid and accurate convergence. After validating the mathematical approach, data from the SCF obtained under denitrifying conditions were fitted successfully to an established model using the GA. Finally, data obtained in the SCF for the removal of phenol were used to compare multiple models. This work suggests that the SCF, in conjunction with the GA, provides a coherent system that can facilitate the characterization of biological systems.

Algorithms↗
PubMed2000

Symptom reduction and suicide risk in patients treated with placebo in antidepressant clinical trials: an analysis of the Food and Drug Administration database.

The assumption that depressed patients who are assigned to placebo in antidepressant clinical trials are exposed to substantial morbidity and mortality is not based on research data. We assessed suicides, suicide attempts, and depressive symptom reduction in studies of 7 new antidepressants using the Food and Drug Administration database. Among 19,639 participating patients, 34 committed suicide (0.8% per year), and 130 attempted suicide (2.9% per year). Rates of suicide and attempted suicide did not differ significantly among the placebo- and drug-treated groups. Annual rates of suicide and attempted suicide were 0.4% and 2.7% with placebo, 0.7% and 3.4% with active comparators, and 0.8% and 2.8% with investigational antidepressants, respectively. Symptom reduction was 40.7% with investigational drugs (n = 4,510), 41.7% with active comparators (n = 1,416), and 30.9% with placebo (n = 2,805). These data may help inform discussions about the use of placebo in antidepressant clinical trials.

Antidepressive Agents↗
PubMed2000

Comparison of testing saliva and serum for detection of antibody to human immunodeficiency virus in Jamaica, West Indies.

BACKGROUND: In Jamaica the reported incidence of AIDS increased from 0.1/100000 in 1985 to 20.2/100000 in 1995. Here there is great reluctance to have voluntary blood testing and, indeed, any blood testing. Since only enzyme-linked immunoassay (EIA) was available for screening serum HIV-1 and 2 antibody, it was considered that a non-invasive saliva screening EIA could be an advantageous alternative. OBJECTIVE: this study was designed to evaluate the OraScreen HIV Rapid Test, a new, simple saliva screening EIA for anti-HIV-1&2 and to compare its sensitivity and specificity with a standard serum anti-HIV screening EIA in current use in Jamaica. STUDY DESIGN: specificity and sensitivity of HIV antibody assays were compared in matched serum and saliva samples obtained from 257 volunteers from a family planning clinic and from visa applicants, representing a low risk population (Group I), and from 52 volunteers known to be HIV infected (Group II). RESULTS: in Group I, 257 volunteers of unknown HIV status, one was positive for anti-HIV-1 in both serum and saliva. One other was seropositive but negative on saliva testing; confirmatory Western Blot (WB) testing on this serum was negative and this subject was tabulated as blood HIV negative. Fifty-one of the known seropositive volunteers (Group II) were saliva antibody positive. One saliva sample was inadequate and this individual was excluded from the study. Serum samples from three others in Group II were grossly haemolysed but their saliva samples were antibody positive. CONCLUSION: With the exclusion of one subject whose saliva sample was inadequate, the OraScreen HIV Rapid Test showed 100% specificity identifying 256/256 HIV antibody negative individuals, and 100% sensitivity by identifying 52/52 infected individuals as HIV antibody positive.

Enzyme-Linked Immunosorbent Assay↗
PubMed2000

5-aminosalicyclic acid and olsalazine inhibit tumor growth in a rodent model of colorectal cancer.

The ability of 5-aminosalicylic acid and olsalazine to inhibit colonic aberrant crypts and tumors was investigated in 1,2-dimethylhydrazine-treated rats. The effect of these drugs on the rates of tumor apoptosis and proliferation was studied as potential mechanisms for their action. 5-Aminosalicylic acid reduced the number of aberrant crypt foci by over one third, while olsalazine had no effect on this parameter. However, both agents effectively reduced tumor number and load, increased the rate of tumor apoptosis, and reduced the rate of tumor cell proliferation. In conclusion, 5-aminosalicylic acid and olsalazine are both ultimately effective chemopreventive agents in this model; however, only 5-aminosalicylic acid inhibited the formation of aberrant crypt foci. The inhibitory effect of these agents in tumors is related to the inhibition of proliferation and the induction of apoptosis.

Aminosalicylic Acids↗
PubMed2000

Non-steroidal anti-inflammatory drugs with different cyclooxygenase inhibitory profiles that prevent aberrant crypt foci formation but vary in acute gastrotoxicity in a rat model.

BACKGROUND: Standard non-steroidal anti-inflammatory drugs (NSAIDs) reduce the risk of colorectal cancer; however, their use as preventive agents is limited by their inherent toxicity. Drugs that selectively inhibit cyclooxygenase-2 (COX-2) may be useful in this setting as they are supposedly less toxic. No study has directly compared the ability of standard NSAIDs and selective COX-2 inhibitors to inhibit colorectal cancer at clinically relevant doses. METHODS: Aberrant crypt foci (ACF) were induced in Sprague-Dawley rats by using 1,2-dimethylhydrazine (DMH). Test agents or vehicle were then administered for 3 weeks, twice daily through orogastric gavage. At the end of this period, the number and multiplicity of ACF were determined. The agents tested at equivalent anti-inflammatory doses were: sulindac and indomethacin (standard NSAIDs), meloxicam (selective COX-2 inhibitor), celecoxib (specific COX-2 inhibitor) and sulindac sulfone (no known COX activity). Acute gastrotoxicity of NSAID in rats was compared by using quantitative histology. RESULTS: All test agents reduced the number of ACF. There was a 42% reduction with indomethacin, 46% with sulindac, 46% with meloxicam, 22% with celecoxib and 36% with sulindac sulfone. Only the COX-2 inhibitors caused no significant gastrotoxicity in rats. CONCLUSIONS: Cyclooxygenase-2 inhibitors are potentially ideal chemopreventive agents as they inhibit ACF and are not gastrotoxic.

Acute Disease↗
PubMed2000

Patient compliance is critical for equivalent clinical outcomes for breast cancer treated by breast-conservation therapy.

OBJECTIVE: To determine the compliance with a standard breast-conservation therapy (BCT) program in a predominantly indigent, minority population of patients with early breast cancer (stage I and II) served by a rural state institution in the South; to compare the clinical outcomes of this group with those reported in clinical trials; and to examine the socioeconomic factors that may have contributed to the rate of compliance. SUMMARY BACKGROUND DATA: Disease-free survival and overall survival in early breast cancer treated by BCT versus modified radical mastectomy are reported to be equivalent in prospective randomized trials. However, patients enrolled in clinical trials may not be representative of patients living in the various diverse communities that make up the United States. The authors' hypothesis is that patients enrolled in clinical trials at the national level may not be representative of indigent patients in the rural South and that clinical trial results may not be directly applicable. METHODS: A retrospective review of 55 women with early-stage breast cancer treated from 1990 to 1995 was performed. Clinical data, compliance with treatment and clinical follow-up, and recurrence rates were examined. Statistical analysis performed include the Fisher exact test, Kaplan-Meier survival analysis, and log-rank test. RESULTS: Full compliance (defined as completion of the entire course of radiation therapy and clinical follow-up) with the BCT program was observed in only 36% of patients. Fifteen of the 35 noncompliant patients did not complete radiation therapy. A significantly higher local failure rate was observed: 8 of these 15 patients (53%) have had local failure. In contrast, patients who were either in full compliance with the BCT program or were deficient only in that they missed part of their clinical follow-up had local failure rates of 5% (1/20) and 10% (2/20), respectively. Age, race, stage of cancer, economic status (measured by availability of medical insurance), distance of patient's residence from the hospital, and education level were evaluated as potential predictors of compliance. None predicted patient compliance, although a trend toward higher compliance was noted in patients with a higher education level, as determined by literacy testing. CONCLUSIONS: Compliance with the BCT protocol at the authors' institution was worse than reported in clinical trials, and noncompliance translated into a significant increase in the local failure rate. Factors examined suggest that literacy may play a role in predicting compliance. Although BCT should be discussed with all breast cancer patients, the judicious application of clinical trial data to an institution's local population is warranted.

Breast Neoplasms↗
PubMed1999

A simple laboratory method for inducing anger: a preliminary investigation.

To facilitate the experimental study of anger, we developed a simple laboratory method to induce anger. This anger induction (AI) is similar in format to the Velten Mood Induction Procedure for depression (VMIP-D), and involves reading descriptors of anger experience, recalling relevant personal memories, and evoking the mood suggested by the sentence/memory. We administered the AI and VMIP-D to 81 undergraduate men and women and collected mood ratings before, during, and after each mood induction. The AI exhibited good sensitivity and specificity in that it induced moderate to greater increases in anger (>1 SD change) in 68% of the sample, significant decreases in happiness, and minimal changes in other emotions. Mood responses to the AI and VMIP-D were influenced by gender and order of presentation. Uses and limitations of this method are discussed.

Adult↗