Screening of medicinal plants from Trinidad and Tobago for antimicrobial and insecticidal properties.

Antibacterial activity in 51 extracts from 29 plant species currently used in traditional medicine in Trinidad and the neighbouring Caribbean islands was tested for by the agar dilution streak method using six bacteria: Escherichia coli, Pseudomonas aeruginosa. Salmonella tophimurium, Staphylococcus aureus, Staphylococcus epidermidis and Enterococcus faecalis. The extracts from eight of the plants tested showed significant activity against one or more micro-organisms and the most susceptible bacterium was Staphylococcus aureus. In the bioassays for toxicity towards the Aedes aegypti mosquito the most effective plant extracts were from Justicia pectoralis, Manihot utilissima and Stachytarpheta jamaicensis.     

Development of HPLC analytical protocols for quantification of artemisinin in biomass and extracts

Quantification of artemisinin purity and amount in plant material and extracts to date has been characterized by a considerable inconsistency in values. This is likely to be due to the adoption of varied analytical procedures and use of inappropriate to the specific applications analytical techniques. In this paper we are attempting to further develop artemisinin analysis to the point where a universally acceptable reference method is available to the research and end-users communities. Thus, we have developed and validated an HPLC-RI method and optimized an HPLC-ELSD method. We used the gradient HPLC-UV method recommended by the current artemisinin monograph as a comparison for the method improvements presented herein, and show the limitations for its application scope. The data reported should help to allow more reliable laboratory analysis of artemisinin in both pure samples and in Artemisia annua extracts.     

The Actim Partus test to predict pre-term birth in asymptomatic high-risk women

The Actim Partus test has been shown to be a useful predictor of pre-term birth in symptomatic women, but limited research has been carried out in high-risk asymptomatic women. This is a pilot study to evaluate the use of this test as a direct comparator with the fetal fibronectin test. All asymptomatic high-risk women attending a pre-term surveillance clinic over a 9-month period, took an Actim Partus and fetal fibronectin test, between 23(+0)-24(+6) weeks' gestation. A total of 45 women were eligible. The positive and negative predictive values of the Actim Partus test for delivery at ≤ 37 weeks' gestation were 0% and 70%, respectively, compared with the fetal fibronectin test, with values of 67% and 79%, respectively. It was concluded that the Actim Partus test did not perform well as a predictor of pre-term birth in high-risk asymptomatic women.     

How accurate is model planning for orthognathic surgery?

The purpose of this study was to evaluate the accuracy of model surgery prediction after orthognathic surgery and to identify possible errors associated with the prediction process. The study included 46 patients who had undergone orthognathic surgical procedures; 22 in Group A who had had a Le Fort I osteotomy; and 24 in Group B who had had a Le Fort I osteotomy and mandibular setback surgery. The immediate postoperative and preoperative lateral cephalograms were analysed to calculate surgical changes; these were compared with those obtained from model surgery prediction and a statistical analysis was undertaken. The maxilla was more under-advanced and over-impacted anteriorly than predicted by model surgery. The amount of mandibular setback was more than that predicted by model surgery. None of the differences between prediction planning and actual surgical changes was statistically significant at p<0.05. Inaccuracy with the face bow recording, the intermediate wafer, and auto-rotation of the mandible in the supine or anaesthetized patient would appear to be the principal reasons for errors. Inaccuracies are associated with the transfer of prediction planning to model surgery planning and prediction, which should be eliminated to improve the accuracy and predictability of orthognathic surgery.     

Evaluation of methods of archwire ligation on frictional resistance

The aim of the study was to investigate the effect of elastomeric type and stainless steel (SS) ligation on frictional resistance using a validated method. To assess the validity of the new test system to measure mean frictional forces, SS and TMA wires, each with dimensions of 0.017 x 0.025 and 0.019 x 0.025 inches, were used in combination with a self-ligating Damon II bracket or a conventional preadjusted edgewise premolar SS bracket without ligation. Four types of elastomeric module, purple, grey, Alastik or SuperSlick, and a pre-formed 0.09 inch SS ligature were then assessed as methods of ligation using preadjusted edgewise premolar SS brackets. The specimens were tested on a Nene M3000 testing machine, with a crosshead speed of 5 mm/minute and each test run lasted for 4 minutes. Each bracket/wire combination with each method of ligation was tested 10 times in the presence of human saliva and the mean frictional force was recorded. The mean frictional forces were compared using three-way analysis of variance. The Damon II self-ligating bracket and unligated conventional SS bracket produced negligible mean frictional forces with any of the wires tested. For the 0.017 x 0.025 SS, 0.019 x 0.025 SS or 0.019 x 0.025 inch TMA wires, SS ligatures produced the lowest mean frictional forces. With the 0.017 x 0.025 TMA wire, purple modules produced the lowest mean frictional force. There was no consistent pattern in the mean frictional forces across the various combinations of wire type, size and ligation method. Under the conditions of this experiment, the use of passive self-ligating brackets is the only method of almost eliminating friction.     

Neurocysticercosis in children: clinical findings and response to albendazole therapy in a randomized, double-blind, placebo-controlled trial in newly diagnosed cases

The clinical findings of neurocysticercosis, diagnosed primarily on the basis of computed tomography (CT), and response to albendazole therapy in a randomized, double-blind, placebo-controlled trial were studied in 72 newly diagnosed children aged 1.5-12 years admitted to hospital in New Delhi, India, during March to July 2000. The lesions by initial CT were mostly single with perilesional oedema, and were located in the parietal lobes. The most common clinical finding was partial seizure (79.2%). The outcome of the albendazole trial was assessed through changes in CT lesions and status of seizure after 6 months of follow-up; about 55% of the lesions had disappeared and about 80% of the children were seizure-free. The frequency of healing of CT lesions in the albendazole-treated group and placebo group was 54.2% and 55.2%, respectively, and the frequency of a seizure-free state in the albendazole-treated group and placebo group was 87.5% and 77.5%, respectively; the differences were not statistically significant. Changes in lesions by CT and the recurrence of seizures after 6 months of follow-up were not related to the number of lesions by initial CT and albendazole was not beneficial in neurocysticercosis in children with ring-enhancing lesions in CT.     

Prolidase, a potential enzyme target for melanoma: design of proline-containing dipeptide-like prodrugs

Bioinformatics tools such as Perl, Visual Basic, Cluster, and TreeView were used to analyze public gene expression databases in order to identify potential enzyme targets for prodrug strategies. The analyses indicated that prolidase might be a desirable enzyme target based on its differential expression in melanoma cancer cell lines and its high substrate specificity for dipeptides containing proline at the carboxy terminus. RT-PCR expression of prolidase and hydrolytic activity against N-glycyl-l-proline (GLY-PRO), a standard substrate of prolidase, determined in tumor cell lines, exhibited a high correlation (r(2) = 0.95). These results suggest the possibility of targeting prolidase with prodrugs of anticancer agents for enhanced selectivity. The feasibility of such a scenario was tested by (a) synthesizing prodrugs of melphalan that comprised linkage of the carboxy terminus of the l-phenylalanine moiety of melphalan to the N-terminus of l and d stereoisomers of proline and (b) determining their bioconversion and antiproliferative activities in SK-MEL-5 cells, a melanoma cancer cell line with high expression levels of prolidase. The results of hydrolysis studies of the l- and d-proline prodrugs of melphalan, designated as prophalan-l and prophalan-d, respectively, indicated a approximately 7-fold higher rate of activation of prophalan-l compared to prophalan-d in SK-MEL-5 cell homogenates. Prophalan-l exhibited cytotoxicity (GI(50) = 74.8 microM) comparable to that of melphalan (GI(50) = 57.0 microM) in SK-MEL-5 cells while prophalan-d was ineffective, suggesting that prolidase-specific activation to the parent drug may be essential for cytotoxic action. Thus, melphalan prodrugs such as prophalan-l that are cleavable by prolidase offer the potential for enhanced selectivity by facilitating cytotoxic activity only in cells overexpressing prolidase.