Simulation of water molecules inside gold nanotubes of various sizes and temperatures.

This study investigates the behavior of water molecules inside Au nanotubes by molecular dynamics. Different sizes of Au nanotubes under three temperatures for three levels of density of Au nanotube have been studied. The structure of each thermodynamic state is analyzed through the characterization of the hydrogen-bond network. An observation of the water molecule distribution reveals that the adsorption of water molecules creates shell-like formation of water near the Au nanotube wall, and such formations are found to be more pronounced within an Au nanotube. Au atoms of different sizes have an affinity for water molecules at different temperatures.

Profile of gelatinolytic capacity of raw goat milk and the implications for milk quality.

Both endogenous and exogenous proteinases occur in milk, and they can have beneficial or detrimental effects on dairy production. Because the lactation length of dairy goats is shorter and the somatic cell count (SCC) of goat milk is generally greater compared with dairy cows, the objectives of the present study were to investigate the prevalence of major proteinases in raw goat milk, their association with SCC and production stage, and their effects on milk quality. Milk samples were collected from individual goats in consecutive weeks for different durations, covering regular lactation, late lactation, and post-milk stasis. Long-term (monthly) or short-term (weekly) fluctuations of milk fibrinolytic and gelatinolytic capacities of individual goats were revealed chronologically on fibrin and gelatin zymograms, respectively. In a separate trial involving milk samples from 23 goats at random production stages, the percentage of ultracentrifuge force-precipitable casein of total milk protein was calculated to represent milk quality and was assessed to evaluate its correlation with the corresponding proteolytic capacities. The results for regular milk indicate that gelatinase B was more abundant than gelatinase A when they first appeared at SCC of approximately 1 x 10(6)/mL. During the last month before milk stasis, both gelatinases A and B were found to be prevalent and prominent in milk regardless of the broad SCC range recorded there. Fibrinolytic activity and the active form of gelatinase A were only regularly detected in post-stasis secretions and were scarce before stasis. The results of the milk quality trial indicate that milk of relatively high proteinase capacity tended to have a low casein ratio. Correlation analysis confirmed a significant relationship between gelatinase capacity of goat milk and production stage, SCC, or casein ratio. It is suggested that an elevation of gelatinolytic capacity of goat milk coincides with an increase in somatic cell number accompanying the extension of lactation length, which is unfavorable for the production of a more desirable quality of goat milk.

Contribution of somatic cell-associated activation of plasminogen to caseinolysis within the goat mammary gland.

Functional regression of the mammary gland is partly reflected by proteolysis of milk protein and tissue protein. The involvement of the plasminogen activation system in degradation of milk protein and mammary tissue damage has been demonstrated under inflammatory conditions. In this study, mammary secretion from 23 dairy goats primarily grouped as lactation (milking twice daily) or involution (milking once daily or less) was used to determine the ratio of gravity-precipitated casein to total milk protein (casein ratio) as an index of caseinolysis, and activities of components of plasminogen activation system as well as their expressions on somatic cells. Based on the casein ratio, lactation goats were subcategorized as very active (71.8 +/- 1.0%) or less active (29.9 +/- 1.0%) in mammary function; involution goats were subcategorized as gradual (21.7 +/- 1.0%) or acute (5.9 +/- 0.2%) involution. This result suggests that caseinolysis occurred during regular lactation as well as during involution. On the other hand, activities of components of the plasminogen activation system in mammary secretion were increased along with the decreasing casein ratio, in contrast to the similar activities of their counterparts in circulation throughout various mammary statuses. Correlation analysis between casein ratio and activities of plasminogen activation system of goat milk indicated a significant negative relationship for plasmin (r = -0.64), plasminogen (r = -0.69), and urokinase-type plasminogen activator (uPA; r = -0.78) during involution but not during lactation. As for the cellular components of plasminogen activation system, there was an increase in immunoreactivity on somatic cells toward both monoclonal antibodies of human uPA and human uPA receptor under involution conditions suggesting their upregulation relative to lactation condition. Collectively, these results suggest that plasminogen activation system within the mammary gland differentially contribute to milk caseinolysis along the various stages of goat lactation. Meanwhile, a somatic cell-mediated local elevation of plasmin activity may be committed to extensive caseinolysis during involution.

Vector competence of Culex pipiens molestus (Diptera: Culicidae) from Taiwan for a sympatric strain of Japanese encephalitis virus.

Laboratory strains of Culex pipiens molestus Forskal and Culex tritaeniorhynchus Giles from northern Taiwan were compared for their susceptibility to the Sanhsia MQ1-2 (SH) strain of Japanese encephalitis (JE) virus isolated from Taiwan. After feeding on a sweetened blood-virus mixture, viral titers in Cx. p. molestus during the 14-d incubation period ranged from a minimum of 2.9 log10PFU (plaque forming units) per mosquito on day 3 after ingestion to a maximum of 4.65 log10PFU at day 8 and in Cx. tritaeniorhynchus from 2.6 on day 10-5.18 log10PFU per mosquito on day 13. Although virus titer in Cx. p. molestus was lower than in Cx. tritaeniorhynchus at the end of the experiment, this difference was not statistically significant. The median infective dose (ID50) for Cx. p. molestus was 2.83 log10PFU and for Cx. tritaeniorhynchus was 1.02 log10PFU per mosquito, and this difference also was not significant. There also was no significant difference between the median infective dose for transmission (TID50) per mosquito for Cx. p. molestus (5.34 log10PFU) and Cx. tritaeniorhynchus (4.59 log10PFU). We concluded that Cx. p. molestus is an effective laboratory vector of JE virus.

Failure of dengue-2 virus antibody to interfere with the isolation of dengue-2 virus from Aedes aegypti (Diptera: Culicidae).

When isolating dengue virus (DEN) from mosquitoes collected in endemic areas, pools may contain both anti-dengue antibodies from freshly engorged females and virus from DEN infected females. To determine if these antibodies may interfere with virus isolation, we simulated the isolation procedure using Aedes aegypti (L.) that we infected with the 16,681 strain of dengue type 2 virus by intrathoracic inoculation. At 7 d postinfection, we allowed females to engorge on immunized or normal mouse blood. Virus in a mixture of anti-dengue-2 antibodies and dengue-2 virus became inactive after incubation at 37 degrees C for 1 h, but remained infective without incubation. Therefore, at ambient conditions antibodies would not interfere with virus isolation from field-collected Ae. aegypti from endemic areas. In addition, DEN antibodies enhanced virus replication when inoculated into Ae. aegypti, but not C6/36 cells. The mechanism for this in vitro antibody enhancement of infection remains unclear.

Isolation of Japanese encephalitis virus from mosquitoes collected in Northern Taiwan between 1995 and 1996.

Mosquito collections were carried out from May to October in 1995 and 1996 at Yingko and Sanhsia of Taipei County and Chunan of Miaoli County. A grand total of 13,576 mosquitoes consisting of 13 species in 407 pools were processed and inoculated into Aedes albopictus clone C6/36 cell cultures. One hundred thirty seven pools of these showed the presence of viral antigens in the infected C6/36 cell lysates which were identified by the indirect fluorescent antibody test using a monoclonal antibody against Japanese encephalitis (JE) virus. The postive pools, were divided into 97, 20, 1, 8, 1, 1, 7, and 2 pools from Culex tritaeniorhynchus Giles, Aedes albopictus Skuse, Aedes vexans nocturnus (Theobald), Armigeres subalbatus (Coquillett), Culex annulus Theobald, Culex fuscanus Wiedemann, Culex quinquefasciatus Say, and Culex sitiens Wiedemann respectively. The dominant species collected at night was Culex tritaeniorhynchus, while Aedes albopictus was the dominant species collected in daytime. Besides the pigpens, avian habitats are also a dominate source of JE virus in this study.

Susceptibility of three laboratory strains of Aedes albopictus (Diptera: Culicidae) to Japanese encephalitis virus from Taiwan.

The susceptibility of 3 laboratory strains of Aedes albopictus (Skuse) (Sanhsia [SH], Yungho [YH], Liyang [LY], and 1 strain of Culex tritaeniorhynchus Giles from northern and central Taiwan were compared for susceptibility to the MQ1-2 strain of Japanese encephalitis (JE) virus. The median infective dose (MID50) by intrathoracic inoculation was 0.23, 0.76, 1.60, and -0.03 log10 WMICLD50 (50% weanling mice intracranial lethal dose) with Ae. albopictus SH, YH, LY, and Cx. tritaeniorhynchus, respectively. After feeding on a sweetened blood-virus mixture, the oral MID50 was 2.03, 4.32, and 4.98 log10 WMICLD50 for SH, YH, and LY, respectively, and 1.02 log10 WMICLD50 for Cx. tritaeniorhynchus. The SH Ae. albopictus strain transmitted virus to normal mice after 14 d. with an average transmission rate of 45%. Based on these results, the SH strain was the most susceptible and important potential vector among 3 Ae. albopictus strains for the sympatric MQ1-2 strain of JE.

[Studies on the susceptibility of two northern Taiwan strains of Aedes albopictus mosquitoes to Japanese encephalitis virus].

Aedes albopictus is a dominant mosquito species in northern Taiwan. In laboratory, the vector competence of 2 geographical strains of Aedes albopictus mosquitoes to NT 113 strain of Japanese encephalitis virus was examined. The mosquito infection dose50 (MI-D50) of Sanhsia (SH) strain by intrathoracic (i.t.) inoculation was shown to be -1.1 log WMICLD50 (weanling mice intracerebrum lethal dose), while that of Yungho (YH) strain was -2.0 log WMICLD50. The infection dose for 50% mosquitoes transmission (MTID50) by i.t. inoculation was 3.5 log with SH strain but no transmission occurred with YH strain. By feeding sweetened blood-virus mixture, the MID50 with SH strain was 2.7 log though YH strain did not attain 50% infection rate. By viremic mouse blood feeding, the highest infection rate for both strains was about 30%. No evidence of virus transmission was demonstrated by oral infection.