A case series of spotted fever rickettsiosis with neurological manifestations in Sri Lanka

BACKGROUND

Spotted fever group (SFG) rickettsial infections are increasingly detected in Sri Lanka. We describe 17 patients with SFG who developed neurological manifestations.

METHODS

The cases were studied prospectively from 2008 at the Teaching Hospital, Peradeniya. An immunofluorescent antibody assay (IFA) was used to confirm the diagnosis.

RESULTS

All had an IFA IgG titer ranging from 1/64 to 1/4096 and a positive IFA IgM titer against Rickettsia conorii antigen; in 10 (59%) cases the IgG titers were ≥ 1/256 (definitive cases). The median age of the patients was 62 years (range 26-82 years); 10 were male and seven female. The median duration of fever was 12 days (range 4-35 days). Neurological manifestations on admission were drowsiness or confusion in 14 (82%) and a semi-comatose state in three (18%). Rigidity of the limbs occurred in 14 (82%), bradykinesia and resting tremors in 12 (71%), which persisted after defervescence, neck stiffness in seven (42%), weakness of the limbs in five (29%), deafness in two (12%), and stupor in three (18%). Electroencephalograms in three (18%) showed generalized slow waves. Cerebrospinal fluid examination showed a cellular reaction, predominantly lymphocytes, in three cases. Two patients died (fatality rate 12%).

CONCLUSION

We have documented for the first time the neurological features of SFG rickettsioses in the Central Province, Sri Lanka. These were predominantly extrapyramidal features in patients of older age.

Synthesis and biological activity of new potential antimalarial: 1H-pyrazolo[3,4-b]pyridine derivatives

The appearance of drug resistant Plasmodium falciparum malaria necessitates the search for novel antimalarial agents. Using the classical ring-bioisosterism concept as a strategy to develop new potential drugs, 1H-pyrazolo[3,4-b]pyridine 4-aminomethanol compounds were designed and synthesized as isosteres of the classical quinoline antimalarial mefloquine. The hydrochloride form of these compounds were tested for in vitro antimalarial activity against chloroquine-sensitive (Sierra Leone D-6) and resistant (Indochina W-2) clones of P. falciparum. The results described herein indicated that 1-H-pyrazolo[3,4-b]pyridine system represents a bioisosteric framework to quinoline system in the antimalarial activity.

Evaluation of four Narcissus cultivars as potential sources for galanthamine production

Galanthamine, an alkaloid present in the Amaryllidaceae is currently undergoing clinical trials for the treatment of Alzheimer's. Common daffodils, Narcissus spp., contain galanthamine and other alkaloids. Four commercial Narcissus cultivars were evaluated as potential sources of galanthamine. Planting depths, planting densities, bulb size or flower bud removal did not affect galanthamine content.

Metabolically activated steviol, the aglycone of stevioside, is mutagenic

Stevioside, a constituent of Stevia rebaudiana, is commonly used as a noncaloric sugar substitute in Japan. Consistent with reports in the literature, we have found that stevioside is not mutagenic as judged by utilization of Salmonella typhimurium strain TM677, either in the presence or in the absence of a metabolic activating system. Similar negative results were obtained with several structurally related sweet-tasting glycosides. However, steviol, the aglycone of stevioside, was found to be highly mutagenic when evaluated in the presence of a 9000 X g supernatant fraction derived from the livers of Aroclor 1254-pretreated rats. Expression of mutagenic activity was dependent on both pretreatment of the rats with Aroclor 1254 and addition of NADPH; unmetabolized steviol was not active. The structurally related species, isosteviol, was not active regardless of metabolic activation. Similarly, chemical reduction of the unsaturated bond linking the carbon-16 and -17 positions of steviol resulted in the generation of two isomeric products, dihydrosteviol A and B, that were not mutagenic. In addition, ent-kaurenoic acid was found to be inactive. It is therefore clear that a metabolite of an integral component of stevioside is mutagenic; structural features of requisite importance for the expression of mutagenic activity include a hydroxy group at position 13 and an unsaturated bond joining the carbon atoms at positions 16 and 17. A potential metabolite of steviol, steviol-16 alpha,17-epoxide, was synthesized chemically and found to be ineffective as a direct-acting mutagen. Thus, although stevioside itself appears innocuous, it would seem prudent to expeditiously and unequivocally establish the human metabolic disposition of this substance.