Pathogen adaptation to seasonal forcing and climate change

Many diverse infectious diseases exhibit seasonal dynamics. Seasonality in disease incidence has been attributed to seasonal changes in pathogen transmission rates, resulting from fluctuations in extrinsic climate factors. Multi-strain infectious diseases with strain-specific seasonal signatures, such as cholera, indicate that a range of seasonal patterns in transmission rates is possible in identical environments. We therefore consider pathogens capable of evolving their 'seasonal phenotype', a trait that determines the sensitivity of their transmission rates to environmental variability. We introduce a theoretical framework, based on adaptive dynamics, for predicting the evolution of disease dynamics in seasonal environments. Changes in the seasonality of environmental factors are one important avenue for the effects of climate change on disease. This model also provides a framework for examining these effects on pathogen evolution and associated disease dynamics. An application of this approach gives an explanation for the recent cholera strain replacement in Bangladesh, based on changes in monsoon rainfall patterns.     

Effects of eCG and FSH on ovarian response, recovery rate and number and quality of oocytes obtained by ovum pick-up in Holstein cows

The goal of the present study was to compare the ovarian response, oocyte yields per animal, and the morphological quality of oocytes collected by ultrasound guided follicular aspiration from Holstein cows treated either with FSH or eCG. Twenty four normal cyclic, German Holstein cows were randomly divided into two groups. Fourteen cows received 3000 IU eCG on day-4 prior to ovum pick-up (OPU) (day 0), 2 days later (day-2), 625 microg cloprostenol was administered. On day-1 GnRH was administered i.m. and 24h later OPU (day 0) was performed. In ten cows a total dose of 500 IU follicle stimulating hormone (Pluset) was administered intramuscularly in a constant dosage for 4 days with intervals of 12h, starting on day-5. Luteolysis was induced by application of 625 microg cloprostenol on day-2. On day-1 (24h after the last FSH treatment) GnRH was administered i.m. and 24h later OPU (day 0) was performed. Ovarian follicles were visualized on the ultrasound monitor, counted and recorded. All visible antral follicles were punctured. Recovered oocytes were graded morphologically based on the cumulus investment. Average follicle number in ovaries was higher in FSH group than eCG group (p<0.05). Oocyte yields per animal did not differ between FSH and eCG groups. The proportion of grade A oocytes was higher in the FSH group in the than eCG group (p<0.05). Likewise, rate of grade C oocytes in FSH group were lower than eCG group (p<0.05). In conclusion, these results suggest that ovarian response, follicle number in ovaries and oocyte quality are affected by the type of gonadotropin and FSH is better alternative than eCG for OPU treatment.     

Effects of Chronic Light/Dark Cycle on Iron Zinc and Copper Levels in Different Brain Regions of Rats

In this study, we aimed to investigate whether chronic shift in light/dark cycle alters brain trace element concentrations. For this purpose, 20 male Wistar albino adult rats were weighed and randomly divided into three groups. The first group (n?=?6) was the control and had been subjected to 12/12-h light/dark cycle for 30?days. The second group (n?=?7) was subjected to 6/18-h light/dark cycle for 15?days, and the third group (n?=?7) was also subjected to 6/18-h light/dark cycle for 15?days and then returned to normal 12/12-h light/dark cycle for 15?days. When light/dark cycle protocols were completed, tissue specimens of the frontal lobe, temporal lobe, and brain stem were collected. Iron (Fe), zinc (Zn), and copper (Cu) concentrations of the frontal lobe, temporal lobe, and brain stem were determined by an atomic absorption spectrophotometer. When compared with controls, Fe levels of the temporal lobe significantly increased in 6/18-h light/dark cycle group (p?相似文献   

Efficient Transformation of Oil Palm Protoplasts by PEG-Mediated Transfection and DNA Microinjection

Background

Genetic engineering remains a major challenge in oil palm (Elaeis guineensis) because particle bombardment and Agrobacterium-mediated transformation are laborious and/or inefficient in this species, often producing chimeric plants and escapes. Protoplasts are beneficial as a starting material for genetic engineering because they are totipotent, and chimeras are avoided by regenerating transgenic plants from single cells. Novel approaches for the transformation of oil palm protoplasts could therefore offer a new and efficient strategy for the development of transgenic oil palm plants.

Methodology/Principal Findings

We recently achieved the regeneration of healthy and fertile oil palms from protoplasts. Therefore, we focused on the development of a reliable PEG-mediated transformation protocol for oil palm protoplasts by establishing and validating optimal heat shock conditions, concentrations of DNA, PEG and magnesium chloride, and the transfection procedure. We also investigated the transformation of oil palm protoplasts by DNA microinjection and successfully regenerated transgenic microcalli expressing green fluorescent protein as a visible marker to determine the efficiency of transformation.

Conclusions/Significance

We have established the first successful protocols for the transformation of oil palm protoplasts by PEG-mediated transfection and DNA microinjection. These novel protocols allow the rapid and efficient generation of non-chimeric transgenic callus and represent a significant milestone in the use of protoplasts as a starting material for the development of genetically-engineered oil palm plants.     

Thermostable extracellular protease of Bacillus stearothermophilus: factors affecting its production

A strain of protease-producing Bacillus stearothermophilus has been isolated. Glycerol was the best carbon source for production whereas yeast extract was the best nitrogen source. The bacterium could grow up to 70°C but optimum protease production was at 60°C. Best initial pH for protease production was 5. Alkaline pH inhibited production. The enzyme was stable at 60°C for 18 h and was inhibited by EDTA, PMSF and HgCl₂.The authors are with the Enzyme and Microbial Technology Group, Faculty of Science and Environmental Studies, Universiti Pertanian Malaysia, 43400 UPM Serdang, Selangor, Malaysia     

Timing of enteral feeding in cerebral malaria in resource-poor settings: a randomized trial

Background

Early start of enteral feeding is an established treatment strategy in intubated patients in intensive care since it reduces invasive bacterial infections and length of hospital stay. There is equipoise whether early enteral feeding is also beneficial in non-intubated patients with cerebral malaria in resource poor settings. We hypothesized that the risk of aspiration pneumonia might outweigh the potential benefits of earlier recovery and prevention of hypoglycaemia.

Method and Findings

A randomized trial of early (day of admission) versus late (after 60 hours in adults or 36 hours in children) start of enteral feeding was undertaken in patients with cerebral malaria in Chittagong, Bangladesh from May 2008 to August 2009. The primary outcome measures were incidence of aspiration pneumonia, hypoglycaemia and coma recovery time. The trial was terminated after inclusion of 56 patients because of a high incidence of aspiration pneumonia in the early feeding group (9/27 (33%)), compared to the late feeding group (0/29 (0%)), p = 0.001). One patient in the late feeding group, and none in the early group, had hypoglycaemia during admission. There was no significant difference in overall mortality (9/27 (33%) vs 6/29 (21%), p = 0.370), but mortality was 5/9 (56%) in patients with aspiration pneumonia.

Conclusions

In conclusion, early start of enteral feeding is detrimental in non-intubated patients with cerebral malaria in many resource-poor settings. Evidence gathered in resource rich settings is not necessarily transferable to resource-poor settings.

Trial Registration

Controlled-Trials.com ISRCTN57488577     

Is there any role of thrombin activatable fibrinolysis inhibitor in the development of a hypercoagulable state in gastric cancer

ABSTRACT: BACKGROUND: The purpose of this study was to investigate plasma levels of thrombin activatable fibrinolysis inhibitor (TAFI) and TAFI's relationship with coagulation markers (prothrombin fragment 1 + 2) in gastric cancer patients. METHODS: Thirty-three patients with gastric adenocarcinoma and 29 healthy control subjects were prospectively enrolled in the study. Patients who had a history of secondary malignancy, thrombosis related disease, oral contraceptive use, diabetes mellitus, chronic renal failure or similar chronic metabolic disease were excluded from the study. A fasting blood sample was drawn from patients to determine the plasma levels of TAFI and Prothrombin Fragment 1 + 2 (F 1 + 2). In addition, data on patient age, sex, body mass index (BMI) and stage of disease were recorded. The same parameters, except stage of disease, were also recorded for the control group. Subsequently, we assessed the difference in the levels of TAFI and F 1 + 2 between the patient and control groups. Moreover, we investigated the relation of TAFI and F 1 + 2 levels with age, sex, BMI and stage of disease in the gastric cancer group. RESULTS: There were no statistical differences in any demographic variables (age, gender and BMI) between the groups (Table 1). The mean plasma TAFI levels of the gastric cancer group (69.4 [PLUS-MINUS SIGN] 33.1) and control group (73.3 [PLUS-MINUS SIGN] 27.5) were statistically similar (P = 0.62). The mean plasma F 1 + 2 level in the gastric cancer group was significantly higher than for those in the control group (549.7 [PLUS-MINUS SIGN] 325.3 vs 151.9 [PLUS-MINUS SIGN] 67.1, respectively; P < 0.001). In the gastric cancer group, none of the demographic variables (age, gender and BMI) were correlated with either TAFI or F 1 + 2 levels. Also, no significant associations were found between the stage of the cancer and either TAFI or F 1 + 2 levels. CONCLUSION: In our study, TAFI levels of gastric cancer patients were similar to healthy subjects. The results of our study suggest that TAFI does not play a role in pathogenesis of the hypercoagulable state in gastric cancer patients.     

Selective separation of human serum albumin with copper(II) chelated poly(hydroxyethyl methacrylate) based nanoparticles

Poly(hydroxyethyl methacrylate) (PHEMA) nanoparticles with an average size of 300 nm in diameter and with a polydispersity index of 1.156 were produced by surfactant free emulsion polymerization. Specific surface area of the PHEMA nanoparticles was found to be 996 m²/g. Metal-chelating ligand 3-(2-imidazoline-1-yl)propyl(triethoxysilane) (IMEO) was covalently attached to the PHEMA nanoparticles. IMEO content was 0.97 mmol IEMO/g. The morphology and properties of these nanoparticles were characterized with scanning electron microscopy, Fourier transform infrared spectroscopy and atomic force microscopy. The Cu²⁺-chelated PHEMA–IMEO nanoparticles were used in the adsorption-elution studies of human serum albumin (HSA) in a batch system. Maximum HSA adsorption amount of the Cu²⁺ chelated nanoparticles was 680 mg HSA/g. The PHEMA–IMEO–Cu²⁺ nanoparticles exhibited a quite high adsorption capacity and fast adsorption rate due to their high specific surface area and the absence of internal diffusion resistance.