Isolation and identification of the cyanotoxin cylindrospermopsin and deoxy-cylindrospermopsin from a Thailand strain of Cylindrospermopsis raciborskii (Cyanobacteria)

A strain of Cylindrospermopsis (Cyanobacteria) isolated from a fishpond in Thailand was examined for its taxonomy based upon morphology and 16S rRNA gene sequence. It was also examined for production of the hepatotoxic cyanotoxin called cylindrospermopsin (CYN) and deoxycylindrospermopsin (deoxy-CYN). The strain (CY-Thai) was identified as C. raciborskii (Woloszynska) Seenaya and Subba Raju based upon morphological examination which was confirmed by 16S rRNA gene sequences and phylogenetic comparisons based upon its 16S rRNA gene. The alkaloid heptatotoxin CYN was confirmed using mouse bioassay, HPLC and HPLC-MS/MS while deoxy-CYN was confirmed using HPLC-MS/MS. The mouse bioassay gave a minimum lethal dose at 250 mg dry weight cells/kg body weight within 24 h and 125 mg/kg at 72 h, with signs of poisoning the same as in literature reports for CYN. HPLC chromatographic comparison of the CY-Thai toxin with standard CYN gave the same retention time and an absorbance maximum at 262 nm. HPLC-MS/MS confirmed the presence of CYN (M + H 416) and deoxy-CYN (M + H 400). The CYN content in strain CY-Thai was estimated at 1.02 mg/g and approximately 1/10 of this amount for deoxy-CYN. This is the first report from Asia of a CYN, deoxy-CYN producing Cylindrospermopsis raciborskii. (C) 2001 Elsevier Science Ltd. All rights reserved.

Riddling and invariance for discontinuous maps preserving Lebesgue measure

In this paper we use the mixture of topological and measure-theoretic dynamical approaches to consider riddling of invariant sets for some discontinuous maps of compact regions of the plane that preserve two-dimensional Lebesgue measure. We consider maps that are piecewise continuous and with invertible except on a closed zero measure set. We show that riddling is an invariant property that can be used to characterize invariant sets, and prove results that give a non-trivial decomposion of what we call partially riddled invariant sets into smaller invariant sets. For a particular example, a piecewise isometry that arises in signal processing (the overflow oscillation map), we present evidence that the closure of the set of trajectories that accumulate on the discontinuity is fully riddled. This supports a conjecture that there are typically an infinite number of periodic orbits for this system.

Multiple maps and activity-dependent representational plasticity in the anterior Wulst of the adult barn owl (Tyto alba)

In the present study we addressed the issue of somatosensory representation and plasticity in a nonmammalian species, the barn owl. Multiunit mapping techniques were used to examine the representation of the specialized receptor surface of the claw in the anterior Wulst. We found dual somatotopic mirror image representations of the skin surface of the contralateral claw. In addition, we examined both representations 2 weeks after denervation of the distal skin surface of a single digit. In both representations, the denervated digital representation became responsive to stimulation of the adjacent, mutually functional, digit. The mutability and multiple representations indicates that the Wulst provides the owl with sensory processing capabilities analogous to those in mammals.

Pseudo-randomness of round-off errors in discretized linear maps on the plane

We analyze the sequences of round-off errors of the orbits of a discretized planar rotation, from a probabilistic angle. It was shown [Bosio & Vivaldi, 2000] that for a dense set of parameters, the discretized map can be embedded into an expanding p-adic dynamical system, which serves as a source of deterministic randomness. For each parameter value, these systems can generate infinitely many distinct pseudo-random sequences over a finite alphabet, whose average period is conjectured to grow exponentially with the bit-length of the initial condition (the seed). We study some properties of these symbolic sequences, deriving a central limit theorem for the deviations between round-off and exact orbits, and obtain bounds concerning repetitions of words. We also explore some asymptotic problems computationally, verifying, among other things, that the occurrence of words of a given length is consistent with that of an abstract Bernoulli sequence.

Review of Modern Babylon? Prostituting Children in Thailand by Heather Montgomery

Johnson reviews Modern Babylon?: Prostituting Children in Thailand by Heather Montgomery.

Histological analysis of gallbladder diseases in relation to opisthorchiasis in endemic areas of Thailand

Chronic gallbladder disease frequently accompanies infection with the liver fluke, Opisthorchis viverrini, in Northeast Thailand. However, the pathology and pathogenesis of the gallbladder disease have not been described. Accordingly, gallbladder specimens from 187 consecutive patients who had undergone cholecystectomy at a referral hospital in an endemic area in Thailand were histologically characterized in relation to O. viverrini infection. The infection was assessed by the presence of parasite eggs in the bile and/or antibody response to the liver fluke. The average level of parasite-specific IgG was significantly higher in patients with Opisthorchis eggs in the bile than those without (P < 0.001). The main histopathologic features of the gallbladder included inflammation, mucosal atrophy/or hyperplasia, goblet cell metaplasia, mucous gland hyperplasia, Rokitansky-Aschoff sinus formation, dysplasia and fibrosis. The fibrosis was strongly associated with elevated levels of Opisthorchis-specific antibody (P < 0.001) but not with the presence of parasite eggs. Other pathologic features did not vary in frequency or severity with parasitological status. Our results show that severe fibrosis of the gallbladder is a more common histologic feature of cholecystitis among those with O. viverrini infection compared to those without infection. The close relationship between parasite-specific IgG and severe fibrosis suggests that specific immune response to the parasite play an important role in the pathogenesis of the fibrotic change. (C) 2003 Elsevier B.V. All rights reserved.

The prevalence of childhood obesity in primary school children in urban Khon Kaen, Northeast Thailand

Childhood obesity is a serious public health problem because of its strong association with adulthood obesity and the related adverse health consequences. The published literature indicates a rising prevalence of childhood obesity in both developed and developing countries. However no data exists on the prevalence in Northeast Thailand, one of the poorest regions of the country and one that has experienced a recent economic transition. The objective of this study was to estimate the prevalence of obesity in seven to nine year old children in urban Khon Kaen, Northeast Thailand. A cross-sectional school based survey was conducted to determine the prevalence of obesity in children of urban Khon Kaen, Thailand. Multi-staged cluster sampling was used to select 12 school clusters of 72 children each between the ages of 7 and 9 years, in primary school grades 1, 2 and 3 from government, private and demonstration schools. A total of 864 seven to nine year old school children were studied. Anthropometric measurements of standing height and weight were taken for all subjects to the nearest tenth of a centimetre and tenth of a kilogram respectively. Childhood obesity was defined as a weight-for-height Z-score above 2.0 standard deviations of the National Center for Health Statistics/World Health Organisation reference population median. The prevalence of childhood obesity was 10.8% (95% CI: 7.6, 13.9). Obesity was significantly more prevalent in boys than girls. The biggest difference was observed between the three school types, with the highest prevalence of obesity found at teacher training demonstration schools and the lowest at the government schools. This study provides the first data on childhood obesity prevalence in Northeast Thailand. The prevalence of 10.8 per cent is lower than that found in two other urban areas of Thailand but slightly higher than expected for this relatively poor region. If this prevalence rate increases, as observed in other countries in economic transition, the incidence of non-communicable diseases associated with obesity is also likely to increase, thus raising cause for concern and reason for intervention to both control and prevent obesity during childhood.

Partial regularity of minimizers of a functional involving forms and maps

We discuss the partial regularity of minimizers of energy functionals such as (1)/(p)integral(Omega)[sigma(u)dA(p) + (1)/(2)delu(2p)]dx, where u is a map from a domain Omega is an element of R-n into the m-dimensional unit sphere of Rm+1 and A is a differential one-form in Omega.