Background: Severe acute respiratory syndrome (SARS) has claimed 349 lives with 5,327 probable cases reported in mainland China since November 2002. SARS case fatality has varied across geographical areas, which might be partially explained by air pollution level.
Some vagal afferent nerves are thought to mediate autonomic responses evoked by noxious oesophageal stimuli and participate in the perception of pain originating in the oesophagus. However, the vagal nociceptive nerve phenotypes implicated in this function have yet to be identified. In this study, nociceptive fibres were defined by the capacity to discriminate noxious mechanical stimuli (wide range of oesophageal distension with pressure up to 100 mmHg) and detect noxious chemical stimuli (the activators of capsaicin receptor TRPV1). Using immunohistochemical techniques with retrogradely labelled oesophagus-specific neurones and performing extracellular recordings from the isolated vagally innervated oesophagus, we show that in the guinea-pig, the vagus nerves supply the oesophagus with a large population of nociceptive-like afferent nerve fibres. Vagal nociceptive-like fibres in the guinea-pig oesophagus are derived from two embryonically distinct sources: neurones situated in the nodose vagal ganglia and neurones situated in the jugular vagal ganglia. Nodose (placode-derived) nociceptive-like fibres are exclusively C-fibres sensitive to a P2X receptors agonist and rarely express the neuropeptide substance P. In contrast, jugular (neural crest-derived) nociceptive-like fibres include both A-fibres and C-fibres, are insensitive to P2X receptors agonist and mostly express substance P. The non-nociceptive vagal tension mechanoreceptors are distinguished from nociceptors by their saturable response to oesophageal distension and by the lack of TRPV1. These tension mechanoreceptors are exclusively A-fibres arising from the nodose ganglion. We conclude that the vagus nerves supply the guinea-pig oesophagus with nociceptors in addition to tension mechanoreceptors. The vagal nociceptive-like fibres in the oesophagus comprise two distinct subtypes dictated by the ganglionic location of their cell bodies.
Hepatocellular carcinoma (HCC) is one of the major cancers in China. Accordingly, the mortality rates in 1990 (per 100 000) were 20.10 in certain cities and 24.32 in certain counties. More than 90% of HCC cases and 70% of controls were infected with the hepatitis B virus (HBV) (Odds Ratio (OR) = 10-50). In the same group of patients, 8-27% of those with HCC and 0-1 1% of the healthy controls were also infected with hepatitis C (HCV) (OR = 2.11-17.29). There appears to be some correlation between HBV markers and the OR. The government requires that 85% of infants be immunized with HBV vaccine. In 1992, there were 3 million infants inoculated with HB vaccines. Matoxins have been found as contaminants in food, particularly in corn, peanut oil, soya sauce and fermented soya beans. The intake of aflatoxin B, (AFB,) by people of ten different villages correlated with HCC mortality rates (r = 0.55; P < 0.05). The concentration of AFB,-albumin adducts is an indicator of individual exposure to aflatoxins. These adducts are higher in hyperendemic HCC areas and cases. Most people have now changed their staple food and eat rice instead of corn. Six large epidemiological studies have confirmed that people who drink pond-ditch water experience higher HCC mortality rates than people who drink deep-well water. Recent research has found that the bluegreen algal toxin microcystin (MCYST) was a contaminant of pond-ditch water. MCYST is a strong promoter of HCC and will induce severe intrahepatic haemorrhages and liver necrosis. More than 80% of people in Qidong County have already changed their sources of water from pond-ditches to deep wells. Therefore, a combined strategy of the prevention of hepatitis, control of crops and control of drinking water is advocated for the primary prevention of HCC in China.
A vesicle system is described that possesses a pH-induced "breathing" feature and consists of a three-layered wall structure. The "breathing" feature consists of a highly reversible vesicle volume change by a factor of ca. 7, accompanied by diffusion of species into and out of the vesicles with a relaxation time of ca. 1 min. The triblock copolymer poly(ethylene oxide)(45)-block-polystyrene(130)-block-poly(2-diethylaminoethyl methacrylate)(120) (PEO(45)-b-PS(130)-b-PDEA(120)) was synthesized via ATRP. Self-assembly into vesicles was carried out at a pH of ca.10.4. The vesicle wall was shown by cryo-TEM to consist of a sandwich of two external ca. 4 nm thick continuous PS layers and one ca. 17 nm thick PDEA layer in the middle. As the pH decreases, both the vesicle size and the thickness of all three layers increase. The increase of the thickness of the intermediate PDEA layer arises from the protonation and hydration, but the swelling is constrained by the PS layers. The increase of the thickness of the two PS layers is a result of an increasing incompatibility and an accompanying sharpening of the interface between the PS layers and the PDEA layer. Starting at a pH slightly below 6, progressive swelling of the PDEA layer with decreasing pH induces a cracking of the two PS layers and also a sharp increase of the vesicle size and the wall thickness. By pH 3.4, the vesicle size has increased by a factor of approximately 1.9 and the wall shows a cracked surface. These changes between pH 10.4 and 3.4 are highly reversible with the relaxation time of ca. 1 min and can be performed repeatedly. The change in the wall structure not only increases dramatically the wall permeability to water but also greatly expands the rate of proton diffusion from practically zero to extremely rapid.
Two natural macromolecules, chitosan and ovalbumin, were used to produce nanogels by a new, green, and convenient method. Chitosan and ovalbumin solutions were mixed; the pH of the resulting solution was adjusted; and the solution was successively stirred and heated. After that, ovalbumin gelled forming nanospheres. The chitosan chains are supposed to be partly trapped in the nanogel core upon heating because of the electrostatic attractions between chitosan and ovalbumin, while the rest of the chitosan chains should form the shell of the nanogels. The nanogels did not change the size distribution after long-time storage and did not dissociate in the pH range of 2-10.5. The dispersibility, size, and hydrophobicity/hydrophilicity of the nanogels are pH-dependent. The nanogels are good candidates for cosmetic and pharmaceutical applications.
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