Meta Analysis of the Correlation between Periodontal Health and Cognitive Impairment in the Older Population.

OBJECTIVE: To explore the correlation between periodontal health and cognitive impairment in the older population to provide the evidence for preventing cognitive impairment from the perspective of oral health care in older adults. METHODS: A comprehensive search was conducted in PubMed, Embase, the Cochrane Library, the Web of Science, the China National Knowledge Infrastructure, Wanfang Data, the China Science and Technology Journal Database, and the China Biomedical Literature Database, to include both cross-sectional and longitudinal cohort studies on the association between periodontal health and cognitive impairment in older adults. The search was completed in April 2023. Following quality assessment and data organization of the included studies, meta-analysis was performed using Review Manager 5.4. RESULTS: Twenty-two studies involving a total of 4,246,608 patients were included to comprehensively assess periodontal health from four dimensions (periodontitis, tooth loss, occlusal support, and masticatory ability), with the outcome variable of cognitive impairment (including mild cognitive impairment, Alzheimer's disease and all-cause dementia). Meta-analysis showed that, compared to those of periodontally healthy older adults, the risk of cognitive impairment in older adults with poor periodontal health, after adjusting for confounders, was significantly greater for those with periodontitis (OR=1.45, 95% CI: 1.20-1.76, P<0.001), tooth loss (OR=1.80, 95% CI: 1.50-2.15, P<0.001), compromised occlusal support (OR=1.87, 95% CI: 1.29-2.70, P=0.001), and reduced masticatory ability (OR=1.39, 95% CI: 1.11-1.75, P=0.005). The risk of cognitive impairment was higher in older adults with low-dentition than in those with high-dentition. Subgroup analysis revealed older individuals with fewer remaining teeth were at a higher risk of developing cognitive impairment compared to those with more remaining teeth, as shown by the comparison of number of teeth lost (7-17 teeth compared to 0-6 teeth) (OR=1.64, 95% CI: 1.13-2.39, P=0.01), (9-28 teeth compared to 0-8 teeth) (OR=1.13, 95% CI: 1.06-1.20, P<0.001), (19-28 teeth compared to 0-18 teeth) (OR=2.52, 95% CI: 1.32-4.80, P=0.005), and (28 teeth compared to 0-27 teeth) (OR=2.07, 95% CI: 1.54-2.77, P<0.001). In addition, tooth loss in older adults led to a significantly increased risk of mild cognitive impairment (OR=1.66, 95% CI: 1.43-1.91, P<0.001) and all-cause dementia (OR=1.35, 95% CI: 1.11-1.65, P=0.003), although the correlation between tooth loss and the risk of Alzheimer's disease was not significant (OR=3.89, 95% CI: 0.68-22.31, P=0.13). CONCLUSION: Poor periodontal health, assessed across four dimensions (periodontitis, tooth loss, occlusal support, and masticatory ability), represents a significant risk factor for cognitive impairment in older adults. The more missing teeth in older adults, the higher risk of developing cognitive impairment, with edentulous individuals particularly susceptible to cognitive impairment. While a certain degree of increased risk of Alzheimer's disease was observed, no significant association was found between tooth loss and the risk of developing Alzheimer's disease. Enhancing periodontal health management and delivering high-quality oral health care services to older adults can help prevent cognitive impairment.

Efficacy of suprascapular nerve blocks for management of hemiplegic shoulder pain: a systematic review and meta-analysis.

OBJECTIVE: To compare the efficacy of suprascapular nerve block (SSNB) with other treatment modalities for management of HSP in terms of relieving pain and improving range of motion of shoulder joints. MATERIALS AND METHODS: An electronic search was carried out in PubMed, CENTRAL, SCOPUS and EMBASE databases using a series of relevant keywords, along with a manual search. Randomized clinical trials comparing the efficacy of SSNB with placebo injections, intra-articular injections (IAI), ultrasound and Pulsed RF were identified. The outcomes assessed were pain relief measured with visual analogue scale and improvement in the range of motion (ROM) at the end of the follow-up period. The meta-analysis was carried out for quantitative analysis of outcome data. RESULTS: Eight randomized clinical trials were included. The quality of the included trials was low to moderate. SSNB showed improved pain relief at the end of 1 month, compared to placebo (normal saline injections) with mean difference (MD) 1.20 95% CI [0.59,1.80], p<0.0001. When compared to Pulsed radio-frequency (RF), the pain relief at the end of 1 month and 3 months was greater for patients treated with Pulsed RF than SSNB. No significant improvement in the range of motion for flexion, external and internal rotation was observed between SSNB and inter-articular injections. CONCLUSIONS: SSNB is more effective in pain relief than placebo injections and ultrasound, but similar to pulsed RF. Similar effectiveness in ROM improvement was observed with SSNB and intra-articular injections.

ELF magnetic field inhibits gap junctional intercellular communication and induces hyperphosphorylation of connexin43 in NIH3T3 cells.

The effects of extremely low frequency (ELF) magnetic field on gap junctional intercellular communication (GJIC), protein levels, and phosphorylation of connexin43 (Cx43) were studied in NIH3T3 cells. The suppression of GJIC by 24 h, 50 Hz, 0.8 mT ELF magnetic field, 2 h, 3 ng/ml 12-O-tetradecanoylphorbol-13-acetate (TPA), or ELF combined with TPA treatment was confirmed by the fluorescence recovery after photobleaching (FRAP) analysis with a confocal microscope. The results showed that ELF or TPA exposure induced 50-60% inhibition of GJIC (P < 0.01). ELF combined with TPA enhanced the inhibition of GJIC. Western blot analysis using Cx43 specific antibodies showed obviously decreasing non phosphorylated Cx43 (P(0)) induced by ELF and/or TPA exposure. On the other hand, cells treated with ELF and/or TPA displayed a hyperphosphorylated Cx43 band (P(3)). However, there was no obvious changes in the level of Cx43 protein. The results implied that the P(3) band appeared to result from phosphorylation of P(0). But it remains possible that upon the ELF exposure P(0) is converted to P(1), P(2) or both and that P(3) is formed from P(1) or P(2) resulting in the observed hyperphosphorylation pattern. From the present study, we conclude that ELF magnetic field inhibits GJIC and the main mechanism is the hyperphosphorylation of Cx43.

Effects of 50 Hz magnetic fields on gap junctional intercellular communication.

To explore whether the extremely low frequency (ELF) electromagnetic fields (EMFs) may act as cancer promoters or be synergistic with 12-O-tetradecanoylphorbol-13-acetate (TPA) in cancer promotion, an experiment was conducted on the effects of 50 Hz magnetic fields (MFs) on gap junctional intercellular communication (GJIC) of Chinese hamster lung (CHL) cells. Lucifer dye was loaded into CHL cells by iontophoretic injection, and the number of dye-coupled cells (DCC) 5 min after the injection was adopted as the index of GJIC. The effects of TPA at different concentrations and magnetic fields at different intensities, combined with 5 ng/ml TPA, were studied. The results showed that the suppression of TPA on GJIC was dependent on TPA concentration; the threshold concentration of TPA for CHL cells was between 1 and 5 ng/ml. After exposure to 0.8 mT magnetic field for 24 h, the number of DCC decreased to 6.08 +/- 1.59, whereas the number of DCC in the control group was 9.84 +/- 2.27 (P < .05). When the cells were exposed at 0.2, 0.4, and 0.8 mT for 24 h, combined with 5 ng/ml TPA treatment during the last 1 h, the number of DCC decreased to 5.52 +/- 1.53, 5.00 +/- 1.22, and 4.00 +/- 1.29, respectively, which were significantly lower than the values for the group treated with 5 ng/ml TPA alone (6.38 +/- 1.39). It is suggested that certain intensities of 50 Hz magnetic field might act as cancer promoters, be additive with other promoters in cancer promotion, or both.

The effects of 50 Hz magnetic field exposure on dimethylbenz(alpha)anthracene induced thymic lymphoma/leukemia in mice.

Several epidemiological investigations have suggested an increased incidence of lymphoma, leukemia, and brain tumor in residents living near power transmission lines. However, some observers failed to confirm such a positive correlation. To evaluate the effects of extremely low frequency (ELF) magnetic fields on leukemogenesis, an experimental animal model was used, in which thymic lymphoma/leukemia was induced by dimethylbenz(alpha)anthracene (DMBA) injected subcutaneously into the interscapular region of newborn mice within 24 h after birth. Beginning at the second week of age, 165 mice were exposed to 50 Hz magnetic field at 1 mT, 3 h/day, 6 days/week for 16 weeks, and 155 animals exposed to sham conditions. All surviving animals were killed by cervical dislocation at the age of 32 weeks and were examined pathologically. The results showed that the incidences of advanced thymic lymphoma, complicated with lymphomatous leukemia, were 21.8 and 23.9% in the two groups, respectively, without statistically significant differences. But dense metastatic infiltration by lymphoma cells into liver in the field exposure group greater (50%) than that in the sham-exposure group (16.2%) was observed (chi 2 = 9.847, P < 0.01). To determine whether ELF acts as a tumor promoter, further experiments are required.

Pulsed magnetic field from video display terminals enhances teratogenic effects of cytosine arabinoside in mice.

Eighty-nine Swiss Webster mice were randomly divided into four groups: a control group, a pulsed magnetic field (PMF) group, a cytosine arabinoside (ara-C, a teratogen) group, and a combined PMF + ara-C group. Mice in the PMF and PMF + ara-C groups were irradiated with a PMF (a sawtooth waveform with 52 microseconds rise time, 12 microseconds decay time, and 15.6 kHz frequency) at a peak magnetic flux density of 40 microT for 4 hours daily on days 6-17 of gestation. The mice in the ara-C and the PMF + ara-C groups were injected intraperitoneally on day 9 of gestation with 10 mg/kg of ara-C. The incidence of resorption and dead fetuses was not affected by PMF but was increased by ara-C injection. The malformation incidence of cleft palate (CP) and/or cleft lip (CL) was significantly higher in all three of the treated groups than in the control group (P < 0.05). If, however, statistical analyses had been done on litters rather than on individual fetuses, they would show that the incidence of CP and/or CL in the PMF group is not significantly greater than that in the control group. A significantly higher incidence of CP and/or CL was found in the PMF + ara-C group (49%) than the ara-C alone group (26.1%). These data suggest that PMF might enhance the development of ara-C-induced CP and/or CL. The incidence of minor variations in skeletal development, including reduction of skeletal calcification and loss of skeleton, was not statistically significant in the PMF group.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of 2.45-GHz microwave radiation and phorbol ester 12-O-tetradecanoylphorbol-13-acetate on dimethylhydrazine-induced colon cancer in mice.

The purpose of this study was to investigate the effects of 2.45 GHz microwave (MW) radiation on dimethylhydrazine (DMH)-induced colon cancer in mice. The subjects were 115 Balb/c mice 4 weeks of age. The animals were divided into group A (control), group B (DMH), group C (DMH+MW), and group D [DMH + 12-O-tetradecanoylphorbol-13- acetate (TPA)]. Radiation (10 mW/cm2) was delivered dorsally with the E field parallel to the mouse's long body axis in an anechoic chamber. Radiations were administered 3 hr daily, 6 days per week, over a period of 5 months. The average SAR was estimated to be 10-12 W/kg. During the course of radiation treatments, DMH was injected once per week. The tumor promoter TPA was administered once per week for 10 weeks, from the third week on, after the initial treatment. The incidence of tumors did not significantly differ between the three test groups (groups B, C, and D; P > 0.25). However, the number of tumors, the size of the tumors, and the incidence of protuberant and infiltrative types in tumor-bearing animals were higher in group D compared to groups B and C (P < 0.05). No difference was found between groups B and C (P > 0.25). The study indicates that 2.45 GHz microwave radiation at 10 mW/cm2 power density did not promote DMH-induced colon cancers in young mice. The study also showed that TPA could accelerate colon tumor production if a tumor was initiated.