Preparation of bioactive nanotitania ceramics with biomechanical compatibility

In this article, bioactive nanotitania ceramics with biomechanical compatibility was prepared by using an additive of hydroxyapatite or MgO as particle growth inhibitor. After sintering at 1000 degrees C, the particle size of nanotitania ceramics prepared by using HA as additive (HT) was much smaller than that prepared by using MgO as additive (MT). In simulated body fluid (SBF), HT could induce apatite formation in 4 days, while no apatite could be found on MT even after it was soaked in SBF for 14 days. After Ros17/28 osteoblasts were cultured on the materials for 1, 4, and 6 days, MTT results showed that the osteoblasts on the HT differentiated faster than that on the MT. Mechanical tests results showed that the bending and compressive strength of HT were 160 and 200 MPa, while those of MT were 70 and 88 MPa, respectively. These results demonstrated that it is suitable to prepare bioactive nanotitania ceramics, with biomechanical compatibility, by using HA as particle growth inhibitor.

[Effects of heat and noise environments on lipid peroxidation erythrocyte membrane in pilots]

OBJECTIVE

To investigate the effects of heat and noise environments on lipid peroxidation of erythrocyte membrane in pilots.

METHOD

Twenty-four pilots and twenty-one ground personnel (control group) served as the subjects. The pilots performed flying in heat and noise environments. Glutathione peroxidase (GSHpx) and malondialdehyde [correction of malondiadehyde] (MDA) levels in erythrocyte membrane were determined before flying (6:00 a.m.), immediately after flying (12:00 a.m.) and 8 hours after flying (8:00 p.m.) respectively with a spectrophotometer.

RESULT

Immediately after flying, GSHpx activity in pilot's erythrocyte membrane decreased significantly as compared with that in control group. Immediately after flying and 8 h after flying, MDA contents in pilots increased significantly as compared with that of control group.

CONCLUSION

Heat and noise environments might induce increase of lipid peroxidation reaction and decrease of antioxidant ability.

Effects of high temperature and noise on erythrocyte membrane ATPase activity in pilots during flight

Objective. To determine the effect of heat and noise on erythrocyte membrane ATPase activities in pilots during flying. Method. Twenty-four pilots performing bombing for 3 h (45-53 degrees C, 122-97 dB in the cabin) served as the subjects. 21 ground personnel served as control (27 degrees C in the room). Blood samples were taken from both groups before flying (6:00 a.m.), and immediately (12:00 a.m.) and 8 h (8:00 p.m.) after flying. Na(+)-K+ ATPase, and Ca2(+)-Mg2+ ATPase activities in erythrocyte membrane were determined with colorimetry. Result. The Na(+)-K+ ATPase activity in erythrocyte membrane at 6:00 a.m. in pilots was higher than that in control group at the same time (P<0.01). The Ca2(+)-Mg2+ ATPase activities in erythrocyte membrane at 12:00 a.m. and 8:00 p.m. in pilots were significantly higher, compared with those in control group at the same time (P<0.01). Conclusion. The ATPase values obtained in our study were all within normal range, and the daytime variation of both groups are the same. Exposure of human body to heat and noise for long time may be harmful, the higher ATPase activity is, the more catabolism of ATP will be. ATP exhaustion will lead to Ca2+ overload in erythrocyte thus stiffen the red cell membrane.

Strain complex of Schistosoma japonicum in the mainland of China

The present paper deals with studies on the characteristics of Schistosoma japonicum isolated from five localities in the mainland of China. The following items were observed and compared including morphometric data, susceptibility of six mammalian hosts, prepatent period, compatibility between larvae and snail hosts, size of hepatic granuloma produced by eggs, immunoreactions in experimental animals, sensitivity to praziquantel, SDS-PAGE protein pattern and its antigenicity analysis, DNA hybridization and genetic variation and differentiation by analysis with multilocus enzyme electrophoresis. By means of these multidisciplinary methods, from morphological to molecular level, the following conclusions may be drawn from our results. The evidence indicates firstly that S. japonicum in the mainland of China comprises a strain complex with several components of geographically distributed strains. At least four distinct strains exist, ie Yunnan, Guangxi, Sichuan and Anhui-Hubei. Characteristics of each strain are distinct and the results of these studies lead to discussion on the problem of the intraspecific and interstrain differentiation of S. japonicum in the mainland of China.

Sensitivity of different isolates of Schistosoma japonicum from China to praziquantel

Groups of C57BL inbred mice infected with each of the 4 different isolates, (Anhui, Hubei, Sichuan and Yunnan) of Schistosoma japonicum from the mainland of China were treated with praziquantel (PZQ) and the parasiticidal effects were compared. Worm reduction rate was recorded to assess systematically the sensitivity of 4 different isolates to PZQ in the mouse. Three dosage-levels of PZQ, ie 150, 230 and 310 mg/kg body weight in single doses were used. The worm development rates of control groups infected with schistosomes from Anhui, Hubei, Sichuan and Yunnan were 75.5, 81.8, 81.5, and 83.0%, respectively. At the dosage-level of 150 mg/kg, the worm reduction rates for the 4 different isolates were 36.0, 33.9, 25.5 and 35.6%, respectively. At the dosage-level of 230 mg/kg, the rates were 47.1, 46.0, 38.1 and 47.7%, while at the dosage-level of 310 mg/kg, they were 59.3, 58.6, 50.8 and 61.7%, respectively. The results indicated that the worm reduction rate of the Sichuan isolate was lower than that of the other three isolates, however, the differences were not statistically significant, suggesting that schistosomes of Anhui, Hubei, Sichuan and Yunnan isolates bear resemblance in drug response.

Parasitological and histopathological studies on rhesus monkeys infected with Chinese mainland strain of Schistosoma japonicum

Fifteen rhesus monkeys were infected by cutaneous exposure each with 200 or 300 cercariae of Schistosoma japonicum. The dynamic distribution of schistosomula in the skin showed that 77-90% of them were found in the connective tissue, while 10-23% migrated in the hair follicles and sebaceous glands at different time intervals after cercarial penetration. Dead schistosomula recovered from the skin varied from 8.7% to 28.7%. The average rate of adult worm recovery was 74.4% and 61.3% in the 6th and 15th weeks of infection, thereafter the rate decreased to 32.3% and 9.0% in the 19th and 42nd weeks, respectively. The mean length of mature pair-worms was 13.2 +/- 2.3 mm in male and 18.0 +/- 1.9 mm in female 6 weeks of worm age. Afterwards the body length of females and their sexual gland diminished markedly. The mean prepatent period was 35.0 +/- 0.6 days. The average size of mature eggs in the feces was 86.6 +/- 5.4 x 64.3 +/- 3.6 microns, and the peak of eggs passage in the feces occurred between 7th and 15th weeks after infection, later on the number of eggs markedly decreased. Skin reaction to the primary infection was slight. The pathological changes observed in liver were chiefly cellular infiltration of portal spaces and the lesions produced by egg granulomas. The mean volume of single-egg granulomas of the productive stage in liver was 22.7 +/- 10.5 mm3 x 10(-3). The most intensive damages in the gastro-intestinal tract were observed in the large intestine.(ABSTRACT TRUNCATED AT 250 WORDS)

Compatibility between Oncomelania hupensis and different isolates of Schistosoma japonicum in China

Oncomelania hupensis from six localities were used for infection with different isolates of Schistosoma japonicum in the mainland of China, ie Anhui in the east, Hubei in the center, Guangxi in the south, Sichuan in the West, Yunnan in the southwest and Fujian in the southeast. Snails from Anhui and Hubei were readily infected with the local isolate of S. japonicum and cross infection also took place readily between the snails and the schistosomes from these two places. Snails from Sichuan and Yunnan were refractory to infection with schistosome isolates from Hubei and Anhui, but the isolates from Sichuan and Yunnan were able to develop in snails from Hubei and Anhui. Though the Guangxi isolate developed readily in both Anhui and Guangxi snails, the average precercarial period in the former was significantly longer than in the latter. None of the other snails from Sichuan, Yunnan and Fujian became infected. On the other hand, snails from Guangxi infected with Anhui parasites also had a longer precercarial period than that in Anhui snails. Snails from Fujian were readily infected with the isolates from Anhui and Yunnan. The present results suggest that there might be different geographic strains of S. japonicum and their Oncomelania snail hosts in the mainland of China.

Characteristics of different isolates of Schistosoma japonicum from China in the final hosts

The present paper deals with the susceptibility of common laboratory animals, such as mouse, rat, hamster, jird, rabbit and rhesus monkey, to infection with different isolates of Schistosoma japonicum in the mainland of China under laboratory conditions. With the exception of the rat, all the animals under study were permissive hosts for different isolates though their worm recovery rates varied. The mean body length of pair-worms of the Yunnan isolate was considerably smaller than that of the Anhui, Hubei, Guangxi and Sichuan isolates, and the percentage of male specimens with 7 testes in the Yunnan isolate was also significantly less than that in the other 4 isolates. Judging from the egg index (width/length x 100), the eggs of the Sichuan isolate were broad and short in shape, giving a high index; those of Guangxi and Hubei isolates were oblong, giving the lowest index; the other two isolates from Yunnan and Anhui, lay between these two extremes. The mean prepatent periods were longer in mice, hamsters and rhesus monkeys infected with Yunnan and Guangxi isolates, than those with Sichuan isolate. A dendrogram of the 5 isolates of S. japonicum was constructed on the basis of similarity coefficients by means of fuzzy cluster analysis on the biological characters mentioned above. Our results provide evidence of the existence of different strains of S. japonicum in the mainland of China as shown by comparative studies of their characteristics in the final hosts.

Penetration of Schistosoma japonicum cercaria into host skin

The anterior part of Schistosoma japonicum cercaria is a specialized head organ which can slightly stretch out and retract. There are three different types of large unicellular glands in cercarial body, consisting of one head gland, 2 pairs of pre- and 3 pairs of postacetabular glands. These glands differ in position, gross feature, histochemistry and functions. Both polysaccharase and protease activities are demonstrated in the secretions from these glands. Mode of cercarial penetration is described in detail and the penetration is effected by a combination of lytic secretions and mechanical movements. The schematic representation of the process of cercarial penetration is presented. The dynamic distributions of schistosomula in skin at different time intervals after skin penetration in various mammalian hosts are shown. Some newly transformed schistosomula die while penetrating into the skin of 7 mammalian species and the mortality rate varies with the host species, and that can also be affected by the age of cercariae following emergence from the snail. Some physiological aspects between cercariae and newly transformed schistosomula are compared. In contrast to cercariae, schistosomula are saline-adapted and water-intolerant. They were modified histochemically and antigenically.