Mathematical Model for The Transmission of Lymphatic Filariasis and Its Applications

We have constructed a stochastic transmission model for lymphatic filariasis caused by Wuchereria bancrofti, and have analyzed its prevalence using computer simulations. In Pondicherry, India, where Wuchereria bancrofti has been spreading, the Vector Control Research Centre has carried out an integrated vector control strategy against malaria and filariasis for five years (1981~1985) with good results reported. Our study was aimed at evaluating the effect of vector control in the context of Pondicherry, and in particular the continuous effect for the post-control period. In this paper, we have used the LYMFASIM model proposed by Plaisier et al., the carrying capacity model by Rochet and the population dynamics model by us. In the LYMFASIM model and the carrying capacity model, we have modified the quantities of parameters in order to fit the models to the parasitological, entomological and epidemiological data in Pondicherry. We have combined the improved LYMFASIM model with the other models. Through simulations of our combinated model, we have compared the prevalence rate in the human population as well as the mean number of L3-larvae in the mosquito population, with and without vector control. As a result, the simulations show that the prevalence rate would be restrained for a long time even if only a small continuous effect of the vector control remains in the post-control period. However, the mean number of L3-larvae would recovered within a short time comparatively. This is because of the differences in life spans between human and mosquito as well as the incubation periods between the adult worm in the human host and L3-larvae in the mosquito vector

Studies on the transmission model of HIV/AIDS among commercial sex workers in Thailand

In 1990s, there were rapid increases in the number of HIV epidemics and AIDS cases in Thailand, Southeast Asia. In particular the risk of HIV infection was very high among female prostitutes who played a large part in the transmission of HIV infection. We formulated a mathematical model for the transmission of HIV in prostitutes. We carried out the model simulations to analyze the incipient spread of HIV infection and the effect of AIDS prevention methods in prostitutes. The simulation of our model indicates that even if the effect of AIDS prevention methods such as the recommendation of condom use for commercial sex workers would block the transmission at rate by 70%, the elimination of the HIV epidemic is still beyond attainment

Simulations on Prevalence of Echinococcus multilocularis in Hokkaido on the Basis of Vole Population Dynamics

In our study, we have investigated the influence of the intermediate host population density on the prevalence of Echinococcus multilocularis in the definitive host using a mathematical model of transmission. For the vole population (intermediate host) in Hokkaido, a model of population dynamics has been constructed in this paper which follows the seasonal and annual fluctuations. In the northeastern area, the vole density appears to fluctuate periodically with a 4 year cycle. The prevalence of Echinococcus multilocularis in the fox population (definitive host) can be affected by the density of vole through the fox ingesting infectious voles. Therefore we have prepared a food habit function of foxes and the logistic distribution has been proposed. The simulations which have been carried out using the mathematical model for transmission of Echinococcus multilocularis together with the vole dynamics have indicated that the prevalence in foxes is correlated and synchronized with the population dynamics of vole. In addition they have also made us recognize that it is necessary to introduce a suitable food habit function into the transmission model

A model for the transmission of Echinococcus multilocularis in Hokkaido, Japan

A mathematical model for Echinococcus multilocularis transmission would be useful to estimate its prevalence and manage control strategies. We propose a mathematical model which quantitatively describes the transmission of E. multilocularis in Hokkaido, Japan. The model takes into account the influence of the dynamics of both the definitive and the intermediate host populations, which show large scale seasonal variations as they are wild animals. The simulations based on the model clarify the mechanism for the seasonal transmission of E. multilocularis quantitatively, notwithstanding a lack of seasonal prevalence data. At present, human alveolar echinococcosis is prevalent throughout the mainland of Hokkaido. The risk of being infected with alveolar echinococcosis in the human population has been investigated by analyzing the seasonal fluctuation of parasite egg dispersal in the environment, which should be necessary for planning more suitable preventive measures against E. multilocularis.</p

Increased expression of kisspeptin and GnRH forms in the brain of scombroid fish during final ovarian maturation and ovulation

BACKGROUND: Kisspeptins (Kiss) are prime players in the control of reproductive function through their regulation of gonadotropin-releasing hormone (GnRH) expression in the brain. The experimental scombroid fish, chub mackerel (Scomber japonicus) expresses two kiss (kiss1 and kiss2) and three gnrh (gnrh1, gnrh2, and gnrh3) forms in the brain. In the present study, we analyzed expression changes of kiss and gnrh mRNAs in the brain and corresponding GnRH peptides in the brain and pituitary during final ovarian maturation (FOM) and ovulation. METHODS: Female fish possessing late vitellogenic oocytes were injected with GnRH analogue to induce FOM and ovulation. Fish were observed for daily spawning activities and sampled one week post-injection at germinal vesicle migration (GVM), oocyte hydration, ovulation, and post-ovulatory time periods. Changes in relative mRNA levels of kiss and gnrh forms in the brain were determined using quantitative real-time PCR. Changes in GnRH peptides in the brain and pituitary were analyzed using time-resolved fluoroimmunoassay. RESULTS: Both kiss1 and kiss2 mRNA levels in the brain were low at late vitellogenic stage and increased significantly during the GVM period. However, kiss1 mRNA levels decreased during oocyte hydration before increasing again at ovulatory and post-ovulatory periods. In contrast, kiss2 mRNA levels decreased at ovulatory and post-ovulatory periods. Levels of gnrh1 mRNA in the brain increased only during post-ovulatory period. However, levels of gnrh2 and gnrh3 mRNAs were elevated during GVM and then, decreased during oocyte hydration before increasing again at ovulatory period. During post-ovulatory period, both gnrh2 and gnrh3 mRNA levels declined. Peptide levels of all three GnRH forms in the brain were elevated during GVM and oocyte hydration; their levels were significantly lower during late vitellogenic, ovulatory, and post-ovulatory periods. In contrast, pituitary GnRH peptide levels did not show any significant fluctuations, with the GnRH1 peptide levels being many-fold higher than the GnRH2 and GnRH3 forms. CONCLUSION: The results indicate increased expression of multiple Kiss and GnRH forms in the brain and suggest their possible involvement in the regulation of FOM and ovulation in captive female chub mackerel

The clinical presentation and genotype of protein C deficiency with double mutations of the protein C gene

BackgroundSevere protein C (PC) deficiency is a rare heritable thrombophilia leading to thromboembolic events during the neonatal period. It remains unclear how individuals with complete PC gene (PROC) defects develop or escape neonatal stroke or purpura fulminans (PF).ProcedureWe studied the onset of disease and the genotype of 22 PCâ deficient patients with double mutations in PROC based on our cohort (n = 12) and the previous reports (n = 10) in Japan.ResultsTwentyâ two patients in 20 unrelated families had 4 homozygous and 18 compound heterozygous mutations. Sixteen newborns presented with PF (n = 11, 69%), intracranial thromboembolism and hemorrhage (n = 13, 81%), or both (n = 8, 50%), with most showing a plasma PC activity of <10%. Six others first developed overt thromboembolism when they were over 15 years of age, showing a median PC activity of 31% (range: 19â 52%). Fifteen of the 22 patients (68%) had the five major mutations (G423VfsX82, V339M, R211W, M406I, and F181V) or two others (E68K and K193del) that have been reported in Japan. Three of the six lateâ onset cases, but none of the 16 neonatal cases, had the K193del mutation, which has been reported to be the most common variant of Chinese thrombophilia. A novel mutation of A309V was determined in a family of two patients with late onset.ConclusionsThe genotype of doubleâ PROC mutants might show less diversity than heterozygous mutants in terms of the timing of the onset of thrombophilia (newborn onset or late onset).Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/137364/1/pbc26404_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/137364/2/pbc26404.pd

Leptin Is an Important Endocrine Player That Directly Activates Gonadotropic Cells in Teleost Fish, Chub Mackerel

Leptin, secreted by adipocytes, directly influences the onset of puberty in mammals. Our previous study showed that leptin stimulation could promote the secretion of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from pituitary cells in primary culture and ovarian development in chub mackerel. This study aimed to elucidate the detailed mechanism of leptin-induced effects on gonadotropin hormone-producing cells. We produced recombinant leptin using silkworm pupae and investigated the effects of leptin on FSH and LH secretion and gene expression in the primary culture of pituitary cells from chub mackerel. The presence or absence of co-expression of lepr mRNA, FSH and LH b-subunit mRNA in gonadotropic cells was examined by double-labeled in situ hybridization. The addition of leptin significantly increased the secretion and gene expression of FSH and LH from male and female pituitary cells in primary culture. In contrast, gonadotropin-releasing hormone 1 affected neither FSH secretion in cells from females nor fshb and lhb expression in cells from males and females. The expression of lepr was observed in FSH- and LH-producing cells of both males and females. The results indicate that leptin directly regulates gonadotropin synthesis and secretion and plays an important role in the induction of puberty in teleost fish

The Roles of Kisspeptin System in the Reproductive Physiology of Fish With Special Reference to Chub Mackerel Studies as Main Axis

Kisspeptin, a novel neuropeptide product of the Kiss1 gene, activates the G protein-coupled membrane receptor G protein-coupled receptor 54 (now termed Kiss1r). Over the last 15 years, the importance of the kisspeptin system has been the subject of much debate in the mammalian research field. At the heart of the debate is whether kisspeptin is an absolute upstream regulator of gonadotropin-releasing hormone secretion, as it has been proposed to be the master molecule in reproductive events and plays a special role not only during puberty but also in adulthood. The teleostean kisspeptin system was first documented in 2004. Although there have been a number of kisspeptin studies in various fish species, the role of kisspeptin in reproduction remains a subject of controversy and has not been widely recognized. There is an extensive literature on the physiological and endocrinological bases of gametogenesis in fish, largely derived from studying small, model fish species, and reports on non-model species are limited. The reason for this discrepancy is the technical difficulty inherent in developing rigorous experimental systems in many farmed fish species. We have already established methods for the full life-cycle breeding of a commercially important marine fish, the chub mackerel (cm), and are interested in understanding the reproductive function of kisspeptins from various perspectives. Based on a series of experiments clarifying the role of the brain–pituitary–gonad axis in modulating reproduction in cm, we theorize that the kisspeptin system plays an important role in the reproduction of this scombroid species. In this review article, we provide an overview of kisspeptin studies in cm, which substantially aids in elucidating the role of kisspeptins in fish reproduction