Effect of ischemic preconditioning on radiation damage to the submandibular gland in rats.

To investigate the effects of radiation on rat submandibular glands and the possible protective effects of ischemic preconditioning, the submandibular glands of Wistar rats were subjected to in situ radiation after ischemic preconditioning. The glands were exposed to X-radiation at a single dose of 20 Gy. Ischemic preconditioning was achieved by three min of ischemia and three min of reperfusion, repeated three times before irradiation. Salivary secretion, histological changes, alterations in tight junctions, and the levels of oxidative stress, pro-inflammatory cytokines, and water secretion proteins mediated by the muscarinic acetylcholine M3 subtype receptor were determined at 1 and 12 weeks post-irradiation. In glands subjected to irradiation only, the secretion, superoxide dismutase activity, tight junction width, acinar cell number, and M3 receptor and aquaporin-5 levels were lower at 1 and 12 weeks than seen in the ischemically preconditioned irradiated glands. In contrast, tumor necrosis factor-α, malondialdehyde, myeloperoxidase activity, and the expression of the tight junction protein claudin-4 were significantly higher in the irradiated only glands. Our study revealed that radiation caused a series of injury-stress responses, especially damage to the water secretion pathway mediated by the M3 receptor that ultimately led to hyposecretion, which might play an important role in the dysfunction of the irradiated only glands. Ischemic preconditioning reduced the radiation-induced injury to submandibular glands and ameliorated salivary hyposecretion.

[Comparison of Malaria Diagnosis between County and Provincial Laboratories in Guizhou Province].

Malaria cases reported by county laboratories were further tested in the provincial laboratory in Guizhou province by using PCR test and microscopy. The consistency between PCR and microscopic results in the provincial laboratory was set as the basis for evaluation of microscopic results in county laboratories. In 89 samples, 24 were identified by PCR to be positive for malaria, among which 15 were infected with P. falciparum, 7 with P. vivax, and 2 with P. ovale; all were imported cases. And 21 samples had consistent identifications by PCR test and microscopic examination in the provincial laboratory. The total coincidence rate between county and provincial laboratories was 79.8%(67/84), and the undetected and error rates in county laboratories were 9.5%(2/21) and 23.8% (15/63), respectively. The Kappa value between county and provicial diagnosis was 0.6, being at the medium-to-high level of consistency.

[Single-tube Single-run Multiplex PCR Detects Mixed Samples with Four Species of Plasmodium].

OBJECTIVE: To establish a single-tube single-run multiplex PCR technique that can detect single or mixed samples with four species of Plasmodium. METHODS: Folding primers were designed based on the fast nested PCR. The reaction component concentrations were optimized and the primers were selected based on the annealing temperature. The established single-tube single-run folding-primer multiplex PCR (FP-PCR) was tested for its sensitivity and specificity to detect single-species and mixed samples with P. vivax, P. falciparum, P. ovale (including P. ovale wallikeri) and/or P. malariae. RESULTS: In all the seven experimental repeats, FP-PCR successfully detected single-species infection for all the four species, with the detection limit reaching or close to 1 parasite/µl blood. For mixed infections with 2-4 species at different densities with the highest being 100 times of the lowest, FP-PCR identified all the species in each combination in 57 out of 84 tests. Further, in 10 dried blood samples on filter paper from healthy subjects, no FP-PCR amplification was found, except weak formation of dimers. CONCLUSION: FP-PCR is a simple and sensitive method for detecting both single-species and mixed infections with human Plasmodium, and can be applied for malaria diagnosis, screening and monitoring.

Effect of ionizing radiation on the secretion of the paracellular pathway in rat submandibular glands.

OBJECTIVES: This study aims to investigate the effects of ionizing radiation on the secretion of the paracellular pathway in rat submandibular glands (SMGs) and reveal the changes in the tight junction (TJ) protein claudin-4. METHODS: A total of 24 Wistar rats were randomly divided into control and irradiation groups. The irradiation groups were further divided into 1, 4, and 12 weeks groups after irradiation. One-time 20 Gy irradiation was given to the SMG area on the experimental side of the irradiation group. At 1, 4, and 12 weeks after irradiation, the secretion of SMGs was measured using the Schirmer's test. The pathological changes in the gland tissues were observed under light microscopy after hematoxylin⁃eosin (HE) staining. The changes in the TJ ultrastructure were observed under transmission electron microscopy. The immunofluorescence staining and Western blot were used to detect the expression levels of muscarinic acetylcholine M3 receptor, aquaporin 5 (AQP5), and claudin-4 protein. RESULTS: At 1, 4, and 12 weeks after irradiation, the secretion of SMGs in the irradiation group was significantly decreased and lower than that in the control group (P<0.01). At 1 week, the interstitial edema was observed in SMG tissues. Nuclear pyknosis, decreased number of acinar cells, and small focal necrosis with inflammatory infiltration were also observed over time. However, these changes were most evident at 12 weeks after irradiation. In the irradiation group, the TJ ultrastructure of glands at different times appeared to be fuzzy, collapsed, and had decreased electron density. Moreover, the width of TJs was remarkably decreased (P<0.01). The expression levels of M3 and AQP5 were decreased in a time-dependent manner, and the fluorescence intensity was significantly reduced after irradiation. However, the expression levels and fluorescence intensity of claudin-4 were enhanced in different degrees. CONCLUSIONS: The changes in the TJ structure, the upregulation of the claudin-4 expression, and the damage in the paracellular pathway were involved in the hyposecretion of SMGs after irradiation.

[Tag primer-nested/ multiplex PCR for detection of Plasmodium falciparum and Plasmodium vivax].

OBJECTIVE: To establish a sensitive, simple to use and low noise nested/multiplex PCR for simultaneously detection of Plasmodium falciparum (Pf) and Plasmodium vivax (P.v). METHODS: The tag primer amplification technique, software Primer Premier 5.0, NCBI-BLAST web resources and the matrix test were used to optimize the nested/multiplex PCR for detection of P.f and P.v with filter paper blood samples taken from malaria patients diagnosed by microscopy, and the results of the optimized nested/multiplex PCR and microscopy were evaluated. RESULTS: The sensitivity of the optimized PCR, determined by the examination of imitative filter paper blood samples, was about 1-2 parasites / microl for P.f and 5-10 parasites / microl for P.v. Primer-dimer and other PCR noise were removed. When 71 field filter paper blood samples taken from microscopically diagnosed patients (24 P.f, 47 P.v) were examined, the concordance between the optimized PCR and microscopy was 875% for Pf and 100% for P.v. CONCLUSION: The nested/multiplex PCR optimized by tag primer amplification technique is simple, with low noise and being able to detect Pf and P.v simultaneously. It is more sensitive in detecting cases with low parasitaemia and more accurate in identifying Plasmodium species than microscopy.