Glycemic response to meals with a high glycemic index differs between morning and evening: a randomized cross-over controlled trial among students with early or late chronotype.

PURPOSE: Glycemic response to the same meal depends on daytime and alignment of consumption with the inner clock, which has not been examined by individual chronotype yet. This study examined whether the 2-h postprandial and 24-h glycemic response to a meal with high glycemic index (GI) differ when consumed early or late in the day among students with early or late chronotype. METHODS: From a screening of 327 students aged 18-25 years, those with early (n = 22) or late (n = 23) chronotype participated in a 7-day randomized controlled cross-over intervention study. After a 3-day observational phase, standardized meals were provided on run-in/washout (days 4 and 6) and intervention (days 5 and 7), on which participants received a high GI meal (GI = 72) in the morning (7 a.m.) or in the evening (8 p.m.). All other meals had a medium GI. Continuous glucose monitoring was used to measure 2-h postprandial and 24-h glycemic responses and their variability. RESULTS: Among students with early chronotype 2-h postprandial glucose responses to the high GI meal were higher in the evening than in the morning (iAUC: 234 (± 92) vs. 195 (± 91) (mmol/L) × min, p = 0.042). Likewise, mean and lowest 2-h postprandial glucose values were higher when the high GI meal was consumed in the evening (p < 0.001; p = 0.017). 24-h glycemic responses were similar irrespective of meal time. Participants with late chronotype consuming a high GI meal in the morning or evening showed similar 2-h postprandial (iAUC: 211 (± 110) vs. 207 (± 95) (mmol/L) × min, p = 0.9) and 24-h glycemic responses at both daytimes. CONCLUSIONS: Diurnal differences in response to a high GI meal are confined to those young adults with early chronotype, whilst those with a late chronotype seem vulnerable to both very early and late high GI meals. Registered at clinicaltrials.gov (NCT04298645; 22/01/2020).

Alignment between timing of 'highest caloric intake' and chronotype in relation to body composition during adolescence: the DONALD Study.

PURPOSE: Our aim was to assess alignment in timing of 'highest caloric intake' with individual chronotype and its association with body composition in adolescents. METHODS: We used repeatedly collected data from n = 196 adolescents (age 9-16 years, providing N = 401 yearly questionnaires) of the DONALD open cohort study. Chronotype was assessed by the Munich Chronotype Questionnaire from which midpoint of sleep (MSFsc) was derived. A sex- and age-specific diet-chrono-alignment score (DCAS) was calculated as the difference in hours between the chronotype-specific median timing of highest caloric intake of the studied population and the individual timing of 'highest caloric intake' or vice versa. Repeated-measures regression models were applied to study cross-sectional and longitudinal associations between the DCAS and body composition, e.g., Fat Mass Index (FMI) or Fat Free Mass Index (FFMI). RESULTS: DCAS ranged from -6:42 h to + 8:01 h and was not associated with body composition. Among adolescents with a later chronotype (N = 201) a 1 h increase in DCAS (later consumption of 'highest caloric intake' in comparison to the median intake of that group), increased FFMI by 1.92 kg/m2 (95% CI: 0.15, 3.69, p value = 0.04) over a median follow-up of 0.94 year. CONCLUSION: Alignment of energy intake with individual chronotype appears beneficial for FFMI among those with a late chronotype.

The association of chronotype and social jet lag with body composition in German students: The role of physical activity behaviour and the impact of the pandemic lockdown.

Young adults with a later chronotype are vulnerable for a discrepancy in sleep rhythm between work- and free days, called social jet lag (SJL). This study analysed (i) chronotype/SJL association with visceral fat/skeletal muscle mass, (ii) the attribution to physical activity behaviour, and (iii) chronotype-specific changes in physical activity behaviour in young adults during the Covid-19 pandemic lockdown. Chronotype and SJL were derived from the Munich-Chrono-Type-Questionnaire in 320 German students (age 18-25 years) from September 2019 to January 2020, 156 of these participated in an online follow-up survey in June 2020. Body composition was assessed by bioimpedance analysis at baseline. Multivariable linear regression analyses were used to relate chronotype/SJL to body composition; the contribution of self-reported physical activity was tested by mediation analysis. At baseline, a later chronotype and a larger SJL were associated with a higher visceral fat mass (P<0.05), this relation was notably mediated by the attention to physical activity (P<0.05). Chronotype (P = 0.02) but not SJL (P = 0.87) was inversely associated with skeletal muscle mass. During the pandemic lockdown, chronotype hardly changed, but SJL was reduced. Timing and physical activity behaviour remained in most participants and changes were unrelated to chronotype (all P>0.07). A later chronotype/higher SJL may increase the risk of a higher visceral fat mass even in this relatively healthy sample, which may be partly due to their physical activity behaviour. Despite a reduction in SJL during the pandemic lockdown, later chronotypes did not change their physical activity behaviour more than earlier chronotypes.

Relative validity of a glycemic index extended food-frequency questionnaire.

BACKGROUND AND AIMS: The dietary glycemic index (GI) and glycemic load (GL) are increasingly recognized as important for the prevention and management of diabetes mellitus. To extend the portfolio of assessment methods for large-scale epidemiological studies, we propose a GI-specific addition to an already established FFQ. METHODS AND RESULTS: The German version of the EPIC-FFQ was extended by GI-specific questions for major carbohydrate sources varying notably in GI (breakfast cereals, bread, pasta, rice, potato etc.). We performed relative validation analyses comparing the GI-extended FFQ to three to four 3-day weighted dietary records (3-d WDR) in 100 middle-aged individuals with diabetes mellitus participating in the German Diabetes Study (GDS). Level of agreement between the two methods was assessed by correlation and cross-classification analyses as well as Bland-Altman-Plots, conducted separately for women and men. Spearman correlation analysis for female participants suggested good agreement between the GI-extended FFQ and 3-d WDRs for energy adjusted dietary GL (r = 0.52, p = 0.0004). For both women and men, agreement with the estimations of dietary GI, GL (for men) and carbohydrates from low and higher-GI food sources from the GI-extended FFQ was acceptable (r: 0.28-0.45). Classification of the dietary GI and GL in the opposite quartile was <10% comparing the GI-extended FFQ and 3-d WDR. Bland-Altman plots suggested a tendency for an overestimation of the dietary GI from the GI-extended FFQ in the lower GI-ranges, particularly for men. CONCLUSION: Compared to the 3-d WDR, the GI-extended FFQ showed a moderate to good relative validity for parameters of carbohydrate quality.

Evaluation of the zone of keratinized tissue using exposed acellular dermal matrix over tooth extraction sites: a randomized controlled clinical trial.

BACKGROUND: The presence of an adequate zone of keratinized tissue has been associated with implant health. This study evaluated the zone of keratinized tissue using exposed acellular dermal matrix (ADM) over extraction sites. MATERIAL AND METHODS: Fifteen sites received ADM, and fifteen control sites received no biomaterial. All sites were sutured with no attempt to achieve primary closure. Initial measurements of buccal and lingual keratinized tissue were taken from the mucogingival line (MGL) to the most coronal gingival margins. Final measurements were taken from the buccal MGL to the lingual MGL 90 days after surgery. Gingival biopsies were taken before implant placement. RESULTS: Test and control groups exhibited a mean value of 4.40 ± 1.45 mm and 1.40 ± 1.40 mm, respectively. The newly formed tissue revealed similar histological aspect of normal keratinized tissue. CONCLUSION: Exposed ADM used over tooth extraction sockets can predictably be used to increase the zone of keratinized tissue.

Evaluation of a dense polytetrafluoroethylene membrane to increase keratinized tissue: a randomized controlled clinical trial.

BACKGROUND: The presence of an adequate zone of keratinized tissue has been associated with implant health. This study evaluated the increasing of the zone of keratinized tissue using dense polytetrafluoroethylene (d-PTFE) membranes over extraction sites, without primary closure. MATERIALS AND METHODS: Fifteen sites received d-PTFE membranes. The control sites received no membranes. All cases were sutured with no attempt to achieve primary closure. Before surgery, initial measurements of buccal and lingual keratinized tissue were taken from the mucogingival line (MGL) to the most coronal gingival margins. Final measurements were taken from the buccal MGL to the lingual MGL, 60 and 90 days after extractions. RESULTS: In the test group, a mean increase in the zone of keratinized tissue of 7.06 ± 2.63 mm and 6.6 ± 2.84 mm was observed in 60 and 90 days, respectively. In the control group, a mean increase of 2.46 ± 1.59 mm and 1.40 ± 1.40 mm was observed in 60 and 90 days, respectively. CONCLUSION: Nonexpanded d-PTFE membranes can predictably be used to increase the zone of keratinized tissue in preparation to implant placement.

Guided bone regeneration using nonexpanded polytetrafluoroethylene membranes in preparation for dental implant placements--a report of 420 cases.

The biologic principle of guided bone regeneration has been successfully used to prevent bone loss in extraction sites. This study comprises 420 cases of alveolar ridge maintenance in preparation for dental implant placements. Nonexpanded polytetrafluoroethylene membranes were positioned over all extraction sites and left intentionally exposed. Lyophilized mineralized bone allografts were used to prevent membrane collapse when buccal bone walls were lost. Membranes were removed at week 4. At the time of implant placements, all sites presented soft tissue compatibility with keratinized gingiva. The mucogingival junction position seemed to be preserved. Exposed nonexpanded polytetrafluoroethylene membranes associated, or not, with bone graft provide tissue formation suitable for implant placement.

Manutenção do rebordo alveolar utilizando membranas de d-PTFE intencionalmente expostas - Relato de cem casos / Alveolar ridge maintenance utilizing intentionally exposed d-PTFE membranes - A report of one hundred cases

A técnica de Regeneração Óssea Guiada (ROG) tem sido utilizada para favorecer a cicatrização do alvéolo e para modificar significativamente o processo de reabsorção do rebordo alveolar. A membrana de Politetrafluoretileno denso (d-PTFE) apresenta a vantagem de impedir a penetração bacteriana, mesmo quando exposta, apresentando ótimos resultados clínicos, principalmente após a exodontia. Este trabalho apresenta casos de manutenção de rebordos alveolares que foram avaliados clinicamente no momento da instalação de implantes osseointegráveis. Cem rebordos alveolares, em regiões de molares e pré-molares inferiores, que foram submetidos à exodontia e imediata instalação de membranas de d-PTFE, foram avaliados. As membranas foram adaptadas entre as paredes ósseas preservadas e o tecido gengival vestibular e lingual, 3 mm a 5 mm apicalmente as margens ósseas dos alvéolos. Os alvéolos que apresentaram perda da parede óssea vestibular foram preenchidos com osso liofilizado para evitar o colapso da membrana. As membranas foram mantidas nos alvéolos por um período de 28 dias. Durante o período de manutenção da membrana sobre o alvéolo, não foi observada inflamação dos tecidos adjacentes. Previamente à instalação dos implantes, as áreas tratadas foram avaliadas clinicamente. Todos os sítios apresentaram gengiva queratinizada, além de formação óssea suficiente para instalação de implantes osseointegráveis.

The biologic principle of guided bone regeneration has been successfully used to enhance bone formation. The dense polytetrafluoroethylene membrane (d-PTFE) resists the incorporation of bacteria into its structure and can be left exposed in the mouth with a low risk of infection, showing excellent clinical results after tooth extraction. This study presents cases of alveolar ridge maintenance evaluated prior to dental implant placement. One hundred cases of alveolar ridge maintenance using intentionally exposed d-PTFE membranes, immediately after tooth extraction, in single molars or bicuspids lower teeth, were evaluated. All sites received a membrane which was trimmed and placed over the extraction socket to cover at least 3 mm to 5 mm of the surrounding bone. In cases where the buccal bone wall was lost, lyophilized bone was used to prevent membrane collapse. Membranes were kept in place for 28 days. No signs of infection were observed. Prior to implant placement, treated areas were clinically evaluated. All sites showed satisfactory bone formation and normal keratinized gingival tissues with suitable conditions for implant placement.