Roles of Baseline Intrinsic Capacity and its Subdomains on the Overall Efficacy of Multidomain Intervention in Promoting Healthy Aging among Community-Dwelling Older Adults: Analysis from a Nationwide Cluster-Randomized Controlled Trial.

BACKGROUND: Impaired intrinsic capacity (IC), which affects approximately 90% of older adults, is associated with a significantly heightened risk of frailty and cognitive decline. Existing evidence suggests that multidomain interventions have the potential to enhance cognitive performance and yield positive effects on physical frailty. OBJECTIVE: To examine roles of baseline IC and its subdomains on the efficacy of multidomain interventions in promoting healthy aging in older adults. DESIGN: a cluster-randomized controlled trial. SETTING AND PARTICIPANTS: 1,054 community-dwelling older adults from 40 community-based clusters across Taiwan. INTERVENTION: A 12-month pragmatic multidomain intervention of exercise, cognitive training, nutritional counseling and chronic condition management. MEASUREMENTS: Baseline IC was measured by 5 subdomains, including cognition (Montreal Cognitive Assessment, MoCA), sensory (visual and hearing impairment), vitality (handgrip strength or Mini-Nutritional Assessment-short form), psychological well-being (Geriatric Depression Scale-5), and locomotion (6m gait speed). Outcomes of interest were cognitive performance (MoCA scores) and physical frailty (CHS frailty score) over a follow-up period of 6 and 12 months. RESULTS: Of all participants (mean age:75.1±6.4 years, 68.6% female), about 90% participants had IC impairment at baseline (2.0±1.2 subdomains). After covariate adjustment using a generalized linear mixed model (GLMM), the multidomain intervention significantly prevented cognitive declines and physical frailty, particularly in those with IC impairment ≥ 3 subdomains (MoCA: coefficient: 1.909, 95% CI: 0.736 ~ 3.083; CHS frailty scores: coefficient = -0.405, 95% CI: -0.715 ~ -0.095). To assess the associations between baseline poor capacity in each IC subdomain and MoCA/CHS frailty scores over follow-up, a 3-way interaction terms (time*intervention*each poorer IC subdomains) were added to GLMM models. Significant improvements in MoCA scores were shown for participants with poorer baseline cognition (coefficient= 1.138, 95% CI: 0.080 ~ 2.195) and vitality domains (coefficient= 1.651, 95% CI: 0.541 ~ 2.760). The poor vitality domain also had a significant modulating effect on the reduction of CHS frailty score after the 6- and 12-month intervention period (6 months: coefficient= -0.311, 95% CI: -0.554 ~ -0.068; 12 months: coefficient= -0.257, 95% CI: -0.513 ~ -0.001). CONCLUSION AND IMPLICATIONS: A multidomain intervention in community-dwelling older adults improves cognitive decline and physical frailty, with its effectiveness influenced by baseline IC, highlighting the importance of personalized strategies for healthy aging.

Swallowing performance in older adults: Associated cognitive, neuroanatomical and demographic factors.

BACKGROUND: Swallowing problems are frequently seen in older adults, especially in individuals with cognitive impairment (CI). The brain plays a crucial role in both cognition and swallowing. Using magnetic resonance imaging (MRI) data, researchers identified regions associated with swallowing. However, it is not yet fully elucidated which factors influence the swallowing performance in older adults. OBJECTIVES: The current study investigated which factors, such as cognitive function, neuroanatomical factors (e.g., the cortical thickness and volume of specific brain regions) and demographical factors are associated with swallowing performance in older adults. Secondly, it was investigated whether there is a difference in neuroanatomical factors between individuals with and without CI. RESEARCH DESIGN AND METHODS: In total, 15 CI individuals (73.1 ± 9.1 years; 46.7% male) and 48 non-CI controls (69.0 ± 5.1 years; 29.2% male) were included. The repetitive saliva swallowing test (RSST) was performed, and an MRI scan was acquired from the participants. RESULTS: Multivariate linear regression analysis showed that the cortical thickness of the right supramarginal gyrus and female gender were positively associated, and a higher age was negatively associated with the RSST in older adults (p < .05). CI was not significantly associated with swallowing performance. Furthermore, it was found that the cortical volume differs more frequently between CI and non-CI than the cortical thickness. CONCLUSION: A thinner cortex of the right supramarginal gyrus and being an older female are associated with poorer swallowing performance. Secondly, cortical volume was more often found to differ between CI and non-CI individuals than cortical thickness.

Development of advanced photon calibrator for Kamioka gravitational wave detector (KAGRA).

The Kamioka Gravitational wave detector (KAGRA) cryogenic gravitational-wave observatory has commenced joint observations with the worldwide gravitational wave detector network. Precise calibration of the detector response is essential for accurately estimating parameters of gravitational wave sources. A photon calibrator is a crucial calibration tool used in laser interferometer gravitational-wave observatory, Virgo, and KAGRA, and it was utilized in joint observation 3 with GEO600 in Germany in April 2020. In this paper, KAGRA implemented three key enhancements: a high-power laser, a power stabilization system, and remote beam position control. KAGRA employs a 20 W laser divided into two beams that are injected onto the mirror surface. By utilizing a high-power laser, the response of the detector at kHz frequencies can be calibrated. To independently control the power of each laser beam, an optical follower servo was installed for power stabilization. The optical path of the photon calibrator's beam positions was controlled using pico-motors, allowing for the characterization of the detector's rotation response. Additionally, a telephoto camera and quadrant photodetectors were installed to monitor beam positions, and beam position control was implemented to optimize the mirror response. In this paper, we discuss the statistical errors associated with the measurement of relative power noise. We also address systematic errors related to the power calibration model of the photon calibrator and the simulation of elastic deformation effects using finite element analysis. Ultimately, we have successfully reduced the total systematic error from the photon calibrator to 2.0%.

Severe myocardial bridge presenting as paroxysmal atrioventricular block.

Chest pain complicated with electrocardiographic changes is not an uncommon scenario in emergency departments, which should be examined cautiously. We describe a 51-years-old man with a myocardial bridge of coronary artery presenting with simultaneous Mobitz type I atrioventricular block on electrocardiography. Echocardiography excluded valvular abnormality and systolic/diastolic dysfunction. Coronary angiography confirmed the diagnosis of a myocardial bridge at the middle segment of the left anterior descending artery, involving the most dominant septal perforator branch with marked systolic compression. The patient underwent coronary artery bypass grafting surgery and was followed up uneventfully at the outpatient department with medical treatment of diltiazem and clopidogrel. The present case is being reported to highlight that clinicians should be alert to such a congenital abnormality as a potential cause of repeated myocardial infarction and conduction abnormality.

Predicting New-Onset Diabetes Mellitus by Component Combinations of Premorbid Metabolic Syndrome among Older Adults in Taiwan.

Metabolic syndrome (MS) was conceptualized to identify people at risk for cardiovascular disease and type 2 diabetes; however, the epidemiology of MS and its combinations of components in older adults remains unclear. Data from the Senior Health Examination Program of the New Taipei City Government in Taiwan in 2014 were obtained for this study. All participants aged 65 years or older and those with a prior history of cardiovascular disease, cerebrovascular disease, or diabetes mellitus were excluded. 29,164 senior citizens were retrieved for this study, and 12,331 (41.28%) of the participants were male. Female participants were more likely to have MS (42.7% vs.31.3%, p <0.001). Female participants with MS were older than those without MS (73.15±6.5 vs. 72.10±6.14 years, p <0.001). Conversely, male participants with MS were younger than those without MS (72.93±6.70 vs. 73.52±6.98 years, p <0.001). The most common combination of MS components was the triad of high blood glucose, high blood pressure and central obesity (25.2% of all participants with MS). Age-related changes in MS component combinations were noted only when central obesity was present. The strongest MS component combination for new-onset diabetes mellitus was high blood glucose, hypertriglyceridemia, reduced HDL-C and central obesity (HR: 5.42, P<0.001). In conclusion, not all component combinations of MS were of the same prognostic impact or the risk for new-onset diabetes mellitus. Further study is needed to develop individualized intervention programs for MS based on risk profiles of older adults is needed.

Effects of red blood cell aggregation on the blood flow in a symmetrical stenosed microvessel.

In order to figure out whether red blood cell (RBC) aggregation is beneficial or deleterious for the blood flow through a stenosis, fluid mechanics of a microvascular stenosis was examined through simulating the dynamics of deformable red blood cells suspended in plasma using dissipative particle dynamics. The spatial variation in time-averaged cell-free layer (CFL) thickness and velocity profiles indicated that the blood flow exhibits asymmetry along the flow direction. The RBC accumulation occurs upstream the stenosis, leading to a thinner CFL and reduced flow velocity. Therefore, the emergence of stenosis produces an increased blood flow resistance. In addition, an enhanced Fahraeus-Lindqvist effect was observed in the presence of the stenosis. Finally, the effect of RBC aggregation combined with decreased stenosis on the blood flow was investigated. The findings showed that when the RBC clusters pass through the stenosis with a throat comparable to the RBC core in diameter, the blood flow resistance decreases with increasing intercellular interaction strength. But if the RBC core is larger and even several times than the throat, the blood flow resistance increases largely under strong RBC aggregation, which may contribute to the mechanism of the microthrombus formation.

[Effects of direct antiviral agent on the frequency of peripheral blood mononuclear cells and their activating factors sCD14s and CD163 in patients with chronic hepatitis C].

Objective: To explore the effects of direct antiviral agent (DAAs) on the frequency of peripheral blood mononuclear cells and their activating factors sCD14s and CD163 in patients with chronic hepatitis C. Methods: Data of 15 treatment-naive chronic hepatitis C patients and 10 healthy controls were collected. Patients with chronic hepatitis C were treated with DAAs for 12 weeks. Blood samples were collected at 0, 4 and 12 weeks respectively, and blood samples of healthy controls were used as controls. Flow cytometry was used to detect the frequency of classical CD14(++)CD16(-) mononuclear cells and pro-inflammatory CD14(+)CD16(+) mononuclear cells in peripheral blood. Serum sCD14s and sCD163 were detected by enzyme-linked immunosorbent assay. The comparison between the two groups was performed by t-test. The comparison between multiple groups was performed by analysis of variance, and further pairwise comparison was performed by LSD-t test. Results: Prior DAAs treatment, peripheral blood CD14(+)CD16(+) mononuclear cell frequency (18.49% ± 1.54% vs. 10.65% ± 0.83%), serum sCD14s [(64 407.38 ± 5778.49) pg/ml vs. (28 370.76 ± 2 357.68 ) pg/ml] and sCD163 [(22 853.80 ± 4 137.61) pg/ml vs. (2 934.41 ± 223.31) pg/ml] were all higher than healthy controls (P < 0.05), while the frequency of CD14(++)CD16(-) mononuclear cells in peripheral blood was lower than healthy controls (59.14%±0.54% vs. 72.75%±1.31%, P < 0.01). During DAAs treatment, CD14(+)CD16(+) mononuclear cells frequency, serum sCD14 and sCD163 were all decreased significantly. After 12 weeks of treatment, CD14(+)CD16(+) mononuclear cells had decreased to nearly normal level (12.42% ± 1.60% vs. 10.65% ± 0.83%, P > 0.05), and serum sCD14 and scd163 were still higher than those of healthy controls [sCD14: (44 390.06 ± 3 330.17) pg / ml vs. (28 370.76 ± 2 357.68) pg/ml, Scd163: (11 494.79 ± 1 836.97) pg / ml vs. (2 934.41 ± 223.31) pg / ml, P < 0.01], while the frequency of CD14(++)CD16(-)mononuclear cells had gradually increased during the course of treatment and neared healthy control level after 12 weeks of treatment. There was no statistically significant difference between the two groups (71.54) % ± 2.99% vs. 72.75% ± 1.31%, P > 0.05). Conclusion: DAAs therapy can reduce the activation of peripheral blood mononuclear cells in patients with chronic hepatitis C.

[Real-world study of paritaprevir/ritonavir-ombitasvir combined with dasabuvir for the treatment of chronic hepatitis C 1b genotype infection in China].

Objective: To evaluate the real-world safety and curative effect of ombitasvir combined with dasabuvir for the treatment of chronic hepatitis C 1b genotype infection in non-cirrhotic or compensated cirrhotic patients. Methods: A real-world research method was adopted, and the research was conducted at three medical centers of mainland China. Non- cirrhotic or compensated cirrhotic patients with HCV genotype 1b infection who were initially treated with IFN/PEG-IFN-alpha combined with ribavirin, and ombitasvir combined with dasabuvir for 8 or 12 weeks were taken. Sustained virological response (SVR) and the incidence of adverse events during treatment and follow-up were evaluated after 12 weeks of drug withdrawal at OBV/PTV/r 25/150/100mg once daily and DSV 250mg, twice daily. Median and range were used for description of non-normally distributed data. Results: 80 cases of GT1b were included in this study. Of these 88.8% (71/80) were newly diagnosed, 12.5% (10/80) were compensated cirrhotic, 97.5% (78/80) received 12 weeks treatment, and 2.5% (2/80) received 8 weeks treatment. The rate of HCV RNA negative at EOT (end of treatment) was 100% (64/64). A total of 67 patients completed the treatment within 12 weeks, and 43 patients returned to the hospital for further consultations, and SVR12 was 100%(43/43). No patient discontinued the drugs because of an adverse event during treatment. Conclusion: In the real world, Ombitasvir combined with dasabuvir for the treatment of chronic hepatitis C 1b genotype infection in China has 100% rates of EOT and SVR12 with well- tolerability and safety.

Synchronous renal cell carcinoma and pheochromocytoma presenting as acute decompensated heart failure.

We report a 49-year-old woman who presented with a hypertensive crisis and acute heart failure and reduced left ventricular systolic function. An abdominal ultrasonography revealed a huge lobulated heterogeneous mass at the lower pole of the right kidney and a mass over the left suprarenal area, which were further delineated by magnetic resonance imaging. The patient underwent laparoscopic right radical nephrectomy and left adrenalectomy. Histopathological analysis confirmed the diagnoses of clear cell renal cell carcinoma of the right kidney with metastasis to the lung; and atypical pheochromocytoma of the left adrenal gland. Target therapy was initiated, which resulted in stabilization of the patient's tumors and the recovery of her heart function. To avoid a delayed diagnosis and catastrophic outcome, clinicians should consider such rare causes of acute decompensated heart failure.

Effects of red yeast rice prescription (LipoCol Forte) on adverse outcomes of surgery.

BACKGROUND: The influence of red yeast rice (RYR) on perioperative outcome remains unknown. AIM: We aimed to compare the complications and mortality after surgery between patients treated with and without RYR prescription. DESIGN: In this surgical cohort study of 3.6 million surgical patients who underwent major inpatient surgeries, 2581 patients who used RYR prescription pre-operatively were compared with 25 810 non-RYR patients selected by matching for age and sex. METHODS: Patients' demographics and medical conditions were collected from the claims data of the National Health Insurance in Taiwan. Complications and mortality after major surgeries in association with RYR prescription were investigated by calculating adjusted odds ratios (ORs) and 95% confidence intervals (CIs) by multiple logistic regression. RESULTS: Compared with patients without RYR prescription, patients prescribed RYR had lower risks of post-operative bleeding (OR 0.36, 95% CI 0.15-0.89), pneumonia (OR 0.54, 95% CI 0.36-0.83), stroke (OR 0.66, 95% CI 0.47-0.92) and 30-day in-hospital mortality (OR 0.37, 95% CI 0.15-0.92). Decreased risk of intensive care (OR 0.64, 95% CI 0.54-0.77), shorter length of hospital stay (P < 0.001) and lower medical expenditures (P = 0.0008) during the index surgical admission were also noted for patients with RYR prescription compared to those for patients without RYR prescription. CONCLUSIONS: This study showed a potentially positive effect of RYR on outcomes after major surgeries. However, patient non-compliance for taking medication should be noted. Our findings require future prospective studies to validate RYR prescription for improving perioperative outcomes.

Activating natural killer (NK) cytotoxicity of canine CD5-CD21- cells requires low surface CD5 density NK cells.

Natural killer (NK) cells play a crucial role in regulating immune functions. Few studies have characterized canine NK cells. We previously demonstrated that canine peripheral blood lymphocytes (PBLs) with a low surface CD5 density (CD5lo) are considered a critical NK population. Natural killer cells in most mammals do not express T-cell markers, but canine CD5lo cells express surface molecules, such as CD3 T-cell receptors. These features make canines unique models for the study of comparative immunology in NK cells. In this study, we discovered that CD5lo and CD21 double-negative (CD5lo-ne/CD2-) cells were originally low in NK cytotoxicity and their NK cytotoxicity was highly activated when co-cultured with CD5lo NK cells. The cytotoxicity was not activated when co-cultured with other cell types, such as high surface CD5 density (CD5hi) cells. The CD5lo-negative (CD5lo-ne) population comprises CD5- and CD5hi cells. CD5-cells were low in NK cytotoxicity initially or after culturing with interleukin-2 (IL-2) without CD5lo cells; however, the addition of CD5lo cells in a similar medium markedly enhanced the NK activity. By contrast, CD5hi cells were always NK inactive, irrespective of them being cultured with CD5lo cells or not. We further verified that only the CD5-CD21- cells, which were separated from CD5-CD21+ cells in the entire CD5- population, showed activated NK activity through CD5lo cell induction. This study is the first to reveal that canine NK cells enhanced NK-inert cells to become NK-cytotoxic cells. Additionally, it is concluded that in beagles, except for CD5lo cells, CD5-CD21- cells show NK activity.

Meta-analysis of brain mechanisms of chewing and clenching movements.

Functional magnetic resonance imaging (fMRI) is widely used for investigating brain activation patterns associated with chewing and clenching movements. Whether studies consistently identify similar brain loci engaged in these movements remains unknown. We investigated the consistency with which specific brain loci were reported to be activated during teeth-occluding movements, using the activation likelihood estimation (ALE) meta-analysis. Twenty fMRI studies that used fMRI to investigate brain activation during a chewing or clenching task in healthy participants were included. Data from the selected studies were pooled, and ALE methods were used to estimate the likelihood of finding a locus associated with the movements. We found that (i) The bilateral primary motor cortex/supplementary motor area/thalamus, the right primary somatosensory cortex (S1)/secondary somatosensory cortex and the posterior cerebellum (lobule VI) have been identified as reliable loci that show consistently activation when teeth occlude. (ii) The right S1 showed a significant likelihood of activation associated with both chewing and clenching, while the left S1 showed a greater likelihood of activation in chewing than in clenching. (iii) Both younger and older participants showed a significant likelihood of activation in the cerebellum. No significant cluster was identified in the contrast analysis. The fMRI studies reliably identified the sensorimotor cortex, the thalamus and the cerebellum as brain loci associated with chewing and clenching and illustrated a differential activation pattern between chewing and clenching. These findings support the use of fMRI as a potential tool for assessing brain activation patterns related to oral sensorimotor functions in humans.

Knowledge regarding hepatitis B mother-to-child transmission among healthcare workers in South China.

To determine the knowledge regarding hepatitis B virus (HBV) mother-to-child transmission (MTCT) and its prevention and treatment among healthcare workers (HCWs) in Guangdong Province, China, an HBV endemic area. An HBV knowledge questionnaire was administered to 900 HCWs from the 3rd Affiliated Hospital of Sun Yat-Sen University and 2 rural hospitals in Guangdong Province. The 27 items in the questionnaire fell into 3 sections: HBV MTCT general knowledge, respondents' practices of preventing HBV MTCT and awareness of the resources of preventing HBV MTCT. The data collected were coded and analysed using SPSS software version 20. In total, 503 of 900 HCWs responded to the survey (response rate: 55.9%). Eighty-four individuals responded correctly to all of the knowledge questions: 58 were doctors, and 26 were nurses (P < .05). Doctors more often performed practices than nurses (t = 3.591, P < .01). Participants from the infectious disease department demonstrated a significantly higher proportion of correct answers and resource utilization than other specialties (χ2  = 14.052, 7.998, P < .01). In terms of the average knowledge score, t test or ANOVA showed that there were significant differences between the specialty groups (t = 3.110, P < .01), hospital level groups (t = 2.337, P < .05) and age groups (F = 3.020, P < .05). Respondents' initiative increased with hospital level and age (t = 2.993, 7.493, P < .01). A considerable percentage of HCWs has misconceptions about HBV MTCT. Healthcare workers, in particular nurses, those working in noninfectious disease departments or township hospitals and younger medical staff, lack systematic and comprehensive knowledge about HBV MTCT and are in urgent need of HBV-related training.

Antrodia cinnamomea reduces obesity and modulates the gut microbiota in high-fat diet-fed mice.

BACKGROUND: Obesity is associated with gut microbiota dysbiosis, disrupted intestinal barrier and chronic inflammation. Given the high and increasing prevalence of obesity worldwide, anti-obesity treatments that are safe, effective and widely available would be beneficial. We examined whether the medicinal mushroom Antrodia cinnamomea may reduce obesity in mice fed with a high-fat diet (HFD). METHODS: Male C57BL/6J mice were fed a HFD for 8 weeks to induce obesity and chronic inflammation. The mice were treated with a water extract of A. cinnamomea (WEAC), and body weight, fat accumulation, inflammation markers, insulin sensitivity and the gut microbiota were monitored. RESULTS: After 8 weeks, the mean body weight of HFD-fed mice was 39.8±1.2 g compared with 35.8±1.3 g for the HFD+1% WEAC group, corresponding to a reduction of 4 g or 10% of body weight (P<0.0001). WEAC supplementation reduced fat accumulation and serum triglycerides in a statistically significant manner in HFD-fed mice. WEAC also reversed the effects of HFD on inflammation markers (interleukin-1ß, interleukin-6, tumor necrosis factor-α), insulin resistance and adipokine production (leptin and adiponectin). Notably, WEAC increased the expression of intestinal tight junctions (zonula occludens-1 and occludin) and antimicrobial proteins (Reg3g and lysozyme C) in the small intestine, leading to reduced blood endotoxemia. Finally, WEAC modulated the composition of the gut microbiota, reducing the Firmicutes/Bacteroidetes ratio and increasing the level of Akkermansia muciniphila and other bacterial species associated with anti-inflammatory properties. CONCLUSIONS: Supplementation with A. cinnamomea produces anti-obesogenic, anti-inflammatory and antidiabetic effects in HFD-fed mice by maintaining intestinal integrity and modulating the gut microbiota.

[Safety and efficacy of DCV-based DAAs therapy for chronic HCV infection in China].

Objective: To evaluate the efficacy and safety of DCV-based DAAs therapy for chronic HCV infected Chinese patients. Methods: An open-label, non-randomized, prospective study was designed. Fifty-two patients with chronic HCV infection were enrolled. Among them, there was one patient after liver transplantation, 2 patients after kidney transplantation, 3 patients with hepatocellular carcinoma, and 4 patients with HBV infection. Thirteen cases with chronic hepatitis C (one compensated cirrhosis) who were negative for resistance-related variants [NS5A RAS (-)] of gene 1b and NS5A were treated with daclatasvir (DCV) + asunaprevir (ASV) for 24 weeks. Twenty-five cases of CHC (six compensated cirrhosis) with GT 1b, 2a, 3a, 3b, 6a were treated with DCV + SOF ± RBV for 24 weeks. 8 cases with decompensated cirrhosis of gene 1b and NS5A RAS(-) were given DCV + SOF + RBV regimen for 12 weeks. Six cases with decompensated cirrhosis, of gene 2a, 1b, 2a, 3a, 3b, were given DCV + SOF + RBV regimen for 24 weeks. HCV RNA, blood routine test, liver and kidney function, and upper abdominal ultrasound/MRI were measured at baseline, 4 weeks of treatment, end of treatment, and 12 weeks of follow-up. The incidence of adverse events and laboratory abnormalities during treatment were recorded. A t-test was used to compare the measurement data between two groups, and analysis of variance was used to compare the measurement data between multiple groups. Results: Sixteen patients (100%) achieved SVR12 after treatment, with 0% recurrence rate. Rapid virological response (RVR) of the four treatment regimens were 76.92%, 54.17%, 87.50%, and 83.33%, respectively, and 32 patients achieved 100% virological response after the completion of treatment. The incidence of adverse events of chronic hepatitis C with cirrhosis and decompensated cirrhosis was 62.5% and 64.29%, respectively. The most common adverse event was fatigue in CHC (25.00%), and elevated indirect bilirubin in decompensated cirrhosis (42.86%). No serious adverse drug events, deaths or adverse reactions occurred. Conclusion: DCV-based DAAs regimen is promising option for the treatment of HCV genotypes, compensated cirrhosis, decompensated cirrhosis, hepatocellular carcinoma, and HCV infection after liver/kidney transplantation in china. Above all, it has high SVR12 with good tolerability and safety profile.

Blazar spectral variability as explained by a twisted inhomogeneous jet.

Blazars are active galactic nuclei, which are powerful sources of radiation whose central engine is located in the core of the host galaxy. Blazar emission is dominated by non-thermal radiation from a jet that moves relativistically towards us, and therefore undergoes Doppler beaming. This beaming causes flux enhancement and contraction of the variability timescales, so that most blazars appear as luminous sources characterized by noticeable and fast changes in brightness at all frequencies. The mechanism that produces this unpredictable variability is under debate, but proposed mechanisms include injection, acceleration and cooling of particles, with possible intervention of shock waves or turbulence. Changes in the viewing angle of the observed emitting knots or jet regions have also been suggested as an explanation of flaring events and can also explain specific properties of blazar emission, such as intra-day variability, quasi-periodicity and the delay of radio flux variations relative to optical changes. Such a geometric interpretation, however, is not universally accepted because alternative explanations based on changes in physical conditions-such as the size and speed of the emitting zone, the magnetic field, the number of emitting particles and their energy distribution-can explain snapshots of the spectral behaviour of blazars in many cases. Here we report the results of optical-to-radio-wavelength monitoring of the blazar CTA 102 and show that the observed long-term trends of the flux and spectral variability are best explained by an inhomogeneous, curved jet that undergoes changes in orientation over time. We propose that magnetohydrodynamic instabilities or rotation of the twisted jet cause different jet regions to change their orientation and hence their relative Doppler factors. In particular, the extreme optical outburst of 2016-2017 (brightness increase of six magnitudes) occurred when the corresponding emitting region had a small viewing angle. The agreement between observations and theoretical predictions can be seen as further validation of the relativistic beaming theory.