[Research on the pathogeny of black tooth stain and association between black tooth stain and primary dentition caries in children].

PURPOSE: To investigate the relationship between polymorphism of cytochrome P450, family 2, subfamily A, polypeptide 6(CYP2A6) and periodontitis, the expression of inflammatory cytokines in 123 Han smokers. METHODS: From October 2018 to October 2019, a total of 123 smokers with periodontitis were selected as the experimental group, and 125 non-smokers as the control group. The general data of the patients were collected, including age, gender, body mass index (BMI), chewing and brushing habits, as well as molar condition; plaque index (PLI), gingival bleeding index (BI), periodontal probing depth (PD) and attachment loss (AL) were detected. CYP2A6 was amplified by PCR. The level of interleukin (IL)-17, IL-1, IL-6, IL-23 and tumor necrosis factor-α (TNF-α) in GCF was detected by enzyme-linked immunosorbent assay(ELISA). SPSS 25.0 software package was used for statistical analysis of the data. RESULTS: There was significant difference in gender, PLI, IL-17, IL-1, IL-6, IL-23, TNF-α level in GCF between the two groups(P＜0.05). All samples were amplified by PCR. Among them, 23 were not amplified, which were identified as CYP2A6 deletion type (CYP2A6del), including 5 in the experimental group and 18 in the control group; 225 were amplified and identified as CYP2A6 wild type(CYP2A6wt), including 118 in the experimental group and 107 in the control group. There was significant difference in CYP2A6 genotype between the two groups(P＜0.05). In the experimental group, the level of IL-1 and PLI of different CYP2A6 genotypes was significantly different(P＜0.05); and in the control group, the level of IL-17 and PLI of different CYP2A6 genotypes was also significantly different(P＜0.05). CONCLUSIONS: There are differences in CYP2A6 genotype between smokers and non-smokers in Han population with periodontitis, but the relationship between CYP2A6 genotype and inflammatory cytokines is not clear.

Blunted effect of the Kv channel inhibitor on pulmonary circulation in Tibetan sheep: a model for studying hypoxia and pulmonary artery pressure regulation.

OBJECTIVE: The aim of this study was to assess the effect of 4-aminopyridine, a Kv channel inhibitor, on the pulmonary circulation of Tibetan sheep. It has been reported that chronic hypoxia downregulates the 4-aminopyridine (4AP)-sensitive Kv channel (which governs the membrane potential (Em) of pulmonary vascular smooth muscle cells in pulmonary vessels) without a change in 4AP sensitivity. METHODOLOGY: Pulmonary haemodynamic indices and blood gas analyses were measured in six young male animals in an altitude chamber that was adjusted to simulated altitudes of 0 m, 2260 m, and 4500 m. Drip infusion of 4AP, 10 mg/h for 3 h, was started and continued during the study. RESULTS: With the increase in altitude mean pulmonary artery pressure increased and mean PaO(2) decreased. 4AP had no effect on the levels of mean PPA, mean pulmonary artery wedge pressure, cardiac output, and mean PaO(2), mean PaCO(2), and mean pH at any altitude but tended to alter heart rate and mean arterial pressure at altitudes of 2260 m and 4500 m. CONCLUSION: It is concluded that the 4AP-sensitive Kv channel does not play a role in pulmonary vascular tone in high-altitude active Tibetan sheep. Their pulmonary vascular oxygen sensing appears not to involve Kv channels.

Cardiopulmonary hemodynamics of blue-sheep, Pseudois nayaur, as high-altitude adapted mammals.

The blue-sheep, pika, and yak live in the Tibetan highlands at an altitude of 6,100 m and are typical mammals adapted to high-altitudes. These animals have a long history of habitation at high-altitudes and are considered to be "animals completely adapted to high-altitudes" because of their physiological and morphological traits that are well adapted to high-altitude environments. To evaluate the physiological characteristics of high-altitude adaptation in the blue-sheep, changes in the pulmonary hemodynamics during exposure to simulated-altitudes at 0, 2,300, and 4,500 m were examined by means of a climatic chamber in Qinghai Province, China (altitude 2,300 m). Seven blue-sheep inhabiting the mountains (3,000 m) of Qinghai Province, China, were compared with 5 pigs raised in the same area as controls. The primary items of measurement were the body weight (BW), systemic arterial pressure (Psa), pulmonary artery pressure (Ppa), hematocrit (Ht), left ventricular weight (LVW), right ventricular weight (RVW), and blood gas profile. The principal findings of this study are: (1) Ht, an index of right ventricular hypertrophy (RVW/LVW), and oxygen consumption (Vdot;O(2)) were significantly lower in the blue sheep compared with the pigs; (2) When the animals were exposed to simulated-altitudes at 0, 2,300, and 4,500 m, Ppa increased significantly in tandem with altitude elevation in both species, but the increases were significantly smaller in the blue-sheep; and (3) Ppa/Psa, an index of the right ventricular load, increased with the altitude in both species, but the increases were smaller in the blue sheep. From these observations, low Ht and RVW/LVW and significant attenuation of hypoxic pulmonary vasoconstriction (HPV) in the blue-sheep is considered to be characteristics of animals completely adapted to high-altitudes, such as the pika.