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Biomedical subjects

K Abeywickrama

Publications and source records attributed to K Abeywickrama.

13 recordsLinked to original sources
PubMed2003

Fungicidal and anti-aflatoxigenic effects of the essential oil of Cymbopogon citratus (DC.) Stapf. (lemongrass) against Aspergillus flavus Link. isolated from stored rice.

AIMS: To develop a natural fungicide against aflatoxigenic fungi, to protect stored rice, using the essential oil of lemongrass. METHODS AND RESULTS: Aspergillus flavus Link. was isolated from stored rice and identified as an aflatoxigenic strain. Lemongrass oil was tested against A. flavus and the test oil was fungistatic and fungicidal against the test pathogen at 0.6 and 1.0 mg ml(-1), respectively. Aflatoxin production was completely inhibited at 0.1 mg ml(-1). The results obtained from the thin layer chromatographic bioassay and gas chromatography indicated citral a and b as the fungicidal constituents in lemongrass oil. During the fumigant toxicity assay of lemongrass oil, the sporulation and the mycelial growth of the test pathogen were inhibited at the concentrations of 2.80 and 3.46 mg ml(-1), respectively. CONCLUSION: Lemongrass oil could be used to manage aflatoxin formation and fungal growth of A. flavus in stored rice. SIGNIFICANCE AND IMPACT OF THE STUDY: Currently, fungicides are not used to control fungal pests or mycotoxin production on stored rice. Rice treated with the essential oil of lemongrass could be used to manage fungal pests as well as the insect pests in stored rice. The essential oil is chemically safe and acceptable to consumers, as synthetic chemical fungicides can cause adverse health effects to consumers.

Aflatoxins↗
PubMed2002

Fungicidal activity of essential oils of Cinnamomum zeylanicum (L.) and Syzygium aromaticum (L.) Merr et L.M. Perry against crown rot and anthracnose pathogens isolated from banana.

AIMS: To develop a post-harvest treatment system against post-harvest fungal pathogens of banana using natural products. METHODS AND RESULTS: Colletotrichum musae was isolated and identified as the causative agent responsible for anthracnose peel blemishes while three fungi, namely Lasiodiplodia theobromae, C. musae and Fusarium proliferatum, were identified as causative agents responsible for crown rot. During the liquid bioassay, cinnamon [Cinnamomum zeylanicum (L.)] leaf, bark and clove [Syzygium aromaticum (L.)] oils were tested against the anthracnose and crown rot pathogens. The test oils were fungistatic and fungicidal against the test pathogens within a range of 0.03-0.11% (v/v). CONCLUSIONS: Cinnamon and clove essential oils could be used as antifungal agents to manage post harvest fungal diseases of banana. SIGNIFICANCE AND IMPACT OF THE STUDY: Cinnamon and clove essential oil could be used as alternative post-harvest treatments on banana. Banana treated with essential oil is chemically safe and acceptable to consumers. Benomyl (Benlate), which is currently used to manage fungal pathogens, can cause adverse health effects and could be replaced with volatile essential oils.

Antifungal Agents↗
PubMed1998

Effects of Fusarium moniliforme culture extracts and fumonisin B1 on DNA, RNA and protein synthesis by baby hamster kidney cells.

Baby hamster kidney cells (BHK-21) were exposed to culture filtrates of 4 Fusarium moniliforme isolates containing varying levels of fumonisin B1 (FMB1) and the effects upon RNA, DNA and protein synthesis were monitored. Cells were also grown on medium amended with FMB1 only for comparison. After 24 h incubation FMB1 (100 micrograms/100 ml medium) reduced protein synthesis by 4% and by 18% after 48 h. Culture filtrates containing the highest levels of FMB1 also caused the greatest inhibition in protein synthesis after 24 h but after 48 h protein synthesis levels were the same as controls even though the FMB1 level was 360 micrograms/100 ml. Only FMB1 reduced DNA synthesis, by 8% after 24 h but after 48 h DNA levels had increased by 40% over controls. The culture filtrates containing the highest levels of FMB1 (360 micrograms/100 ml) reduced DNA synthesis more than 50% after 24 h and 48 h. Culture filtrates containing lesser amounts of FMB1 in some instances stimulated DNA synthesis and inhibited it in others. There was also no correlation in the level of FMB1 with the inhibition of RNA synthesis by BHK cells. It appears that metabolites other than fumonisin produced by F. moniliforme in culture can affect and both stimulate and inhibit RNA, DNA and protein synthesis by BHK cells.

Animals↗
PubMed1997

Randomised trial of basiliximab versus placebo for control of acute cellular rejection in renal allograft recipients. CHIB 201 International Study Group.

BACKGROUND: Currently available immunosuppressive regimens for cadaver-kidney recipients are far from ideal because acute-rejection episodes occur in about 30% to 50% of these patients. In the phase III study described here we assessed the ability of basiliximab, a chimeric interleukin (IL)-2 receptor monoclonal antibody, to prevent acute-rejection episodes in renal allograft recipients. METHODS: 380 adult recipients of a primary cadaveric kidney transplant were randomly allocated, in this double-blind trial, to receive a 20 mg infusion of basiliximab on day 0 (day of surgery) and on day 4, to provide IL-2-receptor suppression for 4-6 weeks (n=193), or to receive placebo (n=187). Both groups received baseline dual immunosuppressive therapy with cyclosporin and steroids throughout the study. The primary outcome measure was incidence of acute-rejection episodes during the 6 months after transplantation. Safety and tolerability were monitored over the 12 months of the study. FINDINGS: 376 patients were eligible for intention-to-treat analysis (basiliximab, n=190; placebo, n=186). No significant differences in patient characteristics were apparent. The incidence of biopsy-confirmed acute rejection 6 months after transplantation was 51 (29.8%) of 171 in the basiliximab group compared with 73 (44.0%) of 166 in the placebo group (32% reduction; 14.2% difference [95% Kaplan-Meier CIs 3% to 24%], p=0.012). The incidence of steroid-resistant first rejection episodes that required antibody therapy was significantly lower in the basiliximab group (10% vs 23.1%, 13.1% difference [5.4% to 20.8%], p<0.001). At weeks 2 and 4 post-transplantation, the mean daily dose of steroids was significantly higher in the placebo group (p<0.001 with one-way analysis of variance). The incidence of graft loss at 12 months post-transplantation was 23 (12.1%) of 190 in the basiliximab group and 25 (13.4%) of 186 in the placebo group (1.3% difference [-5% to 9%], p=0.591). The incidence of infection and other adverse events was similar in the two treatment groups. The acute tolerability of basiliximab was excellent, with no evidence of cytokine-release syndrome. 14 deaths (basiliximab n=9; placebo n=5; -2.0% difference [-6% to 2%], p=0.293) occurred during the 12-month study and a further three deaths (basiliximab n=1; placebo n=2) occurred within the 380-day cut-off period. One post-transplantation lymphoproliferative disorder was recorded in each group. INTERPRETATION: Prophylaxis with 40 mg basiliximab reduces the incidence of acute rejection episodes significantly, with no clinically relevant safety or tolerability concerns.

Acute Disease↗
PubMed1992

Cytotoxicity of Fusarium species mycotoxins and culture filtrates of Fusarium species isolated from the medicinal plant Tribulus terrestris to mammalian cells.

Ayurvedic medicine, which uses decoctions made of medicinal plants, is used to cure diseases in many Asian countries including Sri Lanka. Although proper storage facilities for medicinal plants are unavailable in Sri Lanka, neither the potential for growth of toxigenic fungi nor their ability to produce mycotoxins in stored medicinal plants has been investigated. We isolated three Fusarium species, F. culmorum, F. acuminatum and F. graminearum from the medicinal plant Tribulus terrestris. Culture extracts of the 3 Fusarium spp. were cytotoxic to mammalian cell lines BHK-21 and HEP-2. Three toxic metabolites produced by Fusarium spp; T-2 toxin, zearalenone, and diacetoxyscirpenol were also cytotoxic to the mammalian cell lines. The 3 Fusarium spp. grown on rice media produced zearalenone. Plant material destined for medicinal use should be stored under suitable conditions to prevent growth of naturally occurring toxigenic fungi prior to its use.

Animals↗
PubMed1991

Toxigenic Aspergillus flavus and aflatoxins in Sri Lankan medicinal plant material.

The fungal flora of 6 Asian medicinal plants, Aerva lanata (Linn.) Juss. Alyssicarpus vaginalis D.C., Tribulus terrestris Linn. Adhatoda vasica Nees., Centella asciatica (L.) Urb., Cardiospermum halicacabum Linn. was determined. After surface disinfection Aspergillus spp. were most frequently observed. Aspergillus flavus, isolated from Alyssicarpus vaginalis and Aerva lanata produced aflatoxins in culture. Aflatoxin B1 was also detected in a sample of Aerra lanata at a level of 0.5 micrograms/g. Plant material destined for medicinal use should be stored carefully prior to its use to prevent growth of naturally occurring toxigenic mold fungi.

Aflatoxins↗
PubMed1990

Efficacy of low-dose cyclosporin A in psoriasis: results of dose-finding studies.

The efficacy of cyclosporin A (CyA) in severe psoriasis was analysed in 457 adult patients included in five European multicentre dose-finding studies. Initial CyA doses were 1.25 mg/kg/day in 33 patients, 2.5-3 mg/kg/day in 285 and 5 mg/kg/day in 139. After 3 months of treatment, the reduction of the Psoriasis Area and Severity Index (PASI) score was 35 +/- 6% with 1.25 mg/kg/day of CyA, 57 +/- 2% with 2.5 mg or 3 mg/kg/day and 86 +/- 2% with 5 mg/kg/day (P less than 0.001). The rates of success, defined by a PASI score reduction greater than or equal to 75% or a score less than or equal to 8, were 24%, 52% and 88%, respectively. There were no differences in age, initial severity or duration of psoriasis. The improvement was maintained for 9 months or more in the majority of patients receiving continuous CyA therapy.

Adolescent↗
PubMed1990

Renal function and blood pressure in psoriatic patients treated with cyclosporin A.

Serum creatinine and blood pressure were measured in patients who had severe psoriasis and who were treated with cyclosporin A (CyA) in initial doses of 1.25 mg (n = 34), 2.5 or 3 mg (n = 314), or 5 (n = 215) mg/kg/day. Of the 563 patients involved, 201 were treated for more than 3 months, and 100 received CyA continuously for 12 months or more. Sixty-eight additional patients were included as controls and received placebo (n = 42) or etretinate (n = 26). At doses of 2.5 and 5 mg/kg/day, CyA induced slight but significant dose-dependent increases in serum creatinine and blood pressure. Creatinine increases of 50% or more over baseline values were detected in 4% of the patients receiving 2.5 mg/kg/day and in 13% of those receiving 5 mg/kg/day. After an initial rise during the first weeks of treatment, mean creatinine level remained stable over 1 year provided that the CyA dose was reduced whenever creatinine levels increased by 30% or more over baseline. The incidence of hypertension was 10.6% and did not vary whether the CyA dose was 2.5 or 5 mg/kg/day. The first elevated blood pressures were recorded early after starting CyA therapy (median: 1 month). However, 3 months after stopping treatment, the increases in creatinine as well as in blood pressure were reversible and the levels did not significantly differ from baseline values.

Adolescent↗
PubMed1989

Specific effect of CV 205-502, a potent nonergot dopamine agonist, during a combined anterior pituitary function test.

CV 205-502, an octahydrobenzo[g]quinoline, is a dopamine agonist compound that is not an ergot or ergoline derivative. To investigate the site of action of CV 205-502, three groups of five men were given single daily doses of CV 205-502 (0.04, 0.06, or 0.08 mg/day, doses that suppress plasma PRL by 60-80% for 24 h) for 5 days; on day 6 a combined anterior pituitary function test using iv administration of four hypothalamic releasing hormones (TRH, 200 micrograms; GHRH, 100 micrograms; CRH, 100 micrograms; LHRH, 100 micrograms) was performed. One month later the challenge tests were repeated to obtain control values. The following hormones were measured by RIA in plasma: TSH, ACTH, cortisol, PRL, GH, LH, FSH, and testosterone. With the exception of plasma PRL levels, basal and releasing hormone-stimulated values were similar after CV 205-502 administration and after the 1-month washout period. Basal plasma PRL was lower after CV 205-502 administration, and the response to TRH was attenuated by all three doses of CV 205-502 (the mean percent inhibition values were 76%, 93%, and 94%, respectively). All three doses of CV 205-502 were well tolerated, and another group of men well tolerated 0.1 mg daily. The results confirm that CV 205-502 is a potent dopamine agonist, which directly inhibits lactotropic cells but has no effect on other pituitary cell types.

Adult↗
PubMed1987

Testing equality of relative survival patterns based on aggregated data.

The relative survival rate is defined as the ratio of the survival rate observed in a patient group under consideration to the survival rate expected in a group of people similar to the patient group at the beginning of the follow-up interval, with respect to all possible factors (e.g., age and sex) affecting survival, except the disease under study. Survival from cancer and other chronic diseases is often measured by this quantity, which is adjusted for the effect of mortality attributable to competing risks of death. In this paper, maximum likelihood ratio tests are constructed on the basis of aggregated data for testing the equality of relative survival rates between patient groups against proportional hazards and general alternative hypotheses. The tests are applied to the Finnish nationwide data on colon cancer patients with nonlocalized tumors as reported to the Finnish Cancer Registry. Simulation studies show that the maximum likelihood ratio tests compare favorably with alternative methods proposed earlier. Moreover, the maximum likelihood ratio tests are more extensive in coverage and are based on more applicable alternative hypotheses than the other test statistics. Finally, an extension to proportional hazards regression models of the relative survival rates is suggested.

Biometry↗
PubMedDate not supplied

Toxicity of chlorinated phenoxy acids in combination with 2,3,7,8-tetrachlorodibenzo-p-dioxin in C57BL/6 male mice.

Male C57BL/6 mice were given feed containing various concentrations of 2,4,-dichlorophenoxyacetic acid (2,4-D),2,4,5-trichlorophenoxyacetic acid (2,4,5-T), and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) to provide daily doses of approximately 40 mg/kg 2,4,-D, 40 mg/kg 2,4,5-T, and 2.4 micrograms/kg TCDD (group II): 40 mg/kg 2,3-D, 40 mg/kg 2,4,5-T, and 0.16 micrograms/kg TCDD (group III); and 20 mg/kg 2,4-D, 20 mg/kg 2,4,5-T, and 1.2 micrograms/kg TCDD (group IV). The chemical mixtures were chosen to approximate the concentrations of the components of Herbicide Orange. Controls (group I) were given a diet with only the corn oil vehicle added to the feed. In the treated animals, liver enlargements, hepatocellular toxicity, and reduced thymus size were found an body weight gain was significantly less than that of the control animals. Significant of complete recovery from liver and thymus toxicity was observed when the mice were returned to a control diet. The thymic toxicity and hepatotoxicity seemed to be related to TCDD levels, while the decrease in body weight gain was more closely associated with phenoxy acid concentrations. All effects attributed to the mixture were elicited by individual compounds in the mixture in previous studies.

2,4,5-Trichlorophenoxyacetic Acid↗