Impaired adipocyte glucose transport regulators in morbid obesity - Possible mechanisms contributing to metabolic dysfunction.

OBJECTIVE: Obesity is characterized by hypertrophy and pathological expansion of adipocytes with impaired insulin signaling causing insulin resistance (IR) and metabolic dysfunction. We recently reported decreased expression of glucose transporter-4 (GLUT4) in cultured adipocytes from visceral and abdominal subcutaneous fat depots from patients with morbid obesity and hyperinsulinemia (MOW) and with Type 2 diabetes (MODM). Subsequently, we wanted to study the molecular mechanisms of the glucose transport regulators, p85PI3K, Rab5 and Gapex5 in morbid obesity. PATIENTS AND METHODS: Primary in vitro adipocyte cultures were developed from surgical biopsies from visceral (Visc) and abdominal (Sub) and gluteal subcutaneous (Glut) fat depots from 20 lean adults and 36 adults with morbid obesity divided into two groups: 20 with MOW and 16 MODM). mRNA and protein expression (P) of p85PI3K, Rab5 and Gapex5 were studied with RT-PCR and Western Immunoblotting (WI), respectively. RESULTS: In Sub, the P of (1) p85PI3K and Gapex5 were increased in MODM and (2) Rab5 was decreased in MOW and MODM compared to the lean. In Glut, the P of p85PI3K, Rab5 and Gapex5 showed no difference between the lean and MODM. CONCLUSIONS: In Sub of MODM (1) reduced RAB5 may possibly contribute to IR and glucose transport dysfunction, (2) increased Gapex5 may be a response to decreased Rab5 in an attempt to increase glucose transport and (3) increased p85PI3K may enhance IR mediating lipid accumulation in MODM. In Glut of MODM, though, the expression of p85PI3K, Rab5 and Gapex5 seems to be similar to that found in lean individuals.

Impact of COVID-19 on new-onset type 1 diabetes mellitus - A one-year prospective study.

OBJECTIVE: A positive relationship between the recently emerged Corona Virus Disease-19 (COVID-19) and diabetes has been inferred, but not confirmed, in children. The aim of the present study was to investigate the possible impact of COVID-19 on new-onset Type-1 Diabetes Mellitus (T1DM) in a pediatric population. PATIENTS AND METHODS: This is a prospective study of all children and adolescents diagnosed with T1DM during the first year of the COVID-19 pandemic (March 2020-February 2021) in Western Greece (population coverage ≈1,000,000). The incidence and severity of T1DM, the age and sex of the participants and HbA1c and c-peptide concentrations at diagnosis were recorded and compared to those of the previous year (pre-COVID-19 year). RESULTS: 21 children aged 8.03±0.90 years old were diagnosed with T1DM in the COVID-19 year and 17, aged 9.44±3.72 years old, in the pre-COVID-19 year. A different seasonality pattern of new onsets was observed during the COVID-19 year compared to the previous year, with increasing trend from spring to winter (spring: 9.5% vs. 23.5%, autumn: 23.8% vs. 29.4%, summer: 19% vs. 11.8%, winter: 47.6% vs. 35.3%). Also, compared to the preceding year, HbA1c was significantly higher (p=0.012) and the incidence and severity of diabetic ketoacidosis greater (p=0.045, p=0.013, respectively). CONCLUSIONS: This is the first study to report a different seasonality pattern and increased severity of new-onset T1DM during the first year of the COVID-19 pandemic. Future research should further investigate the possible role of SARS-CoV-2 and the different pattern of overall infection incidence during the COVID-19 year.

Glucose tolerance and insulin sensitivity markers in children and adolescents with excess weight.

OBJECTIVE: Type 2 diabetes mellitus (T2DM) and obesity are alarmingly increasing in children and adolescents. Hence, predictors for early metabolic abnormalities in childhood are urgently needed. We investigated glucose tolerance in children and adolescents with obesity, markers of insulin sensitivity between males and females and the potential association between the parameters measured during an OGTT (glucose, insulin, c-peptide) and prediabetes or stages of puberty. PATIENTS AND METHODS: Glucose tolerance in 89 children and adolescents with excess weight, aged 4-19 years, from Western Greece was studied. A 3-hour OGTT was performed and fasting glucose (FG), fasting insulin (FI), 1/FI, FG/FI, Homeostatic Model Assessment of Insulin Resistance (HOMA-IR), Quantitative insulin sensitivity check index (QUICKI), ISI Matsuda index and Insulinogenic index (IGI30), were also calculated. RESULTS: No significant differences were observed in glucose values between males and females. Insulin and c-peptide concentrations were higher in the girls at several time points. FG/FI was significantly higher in the boys. Girls with obesity may be at higher risk for future insulin resistance. CONCLUSIONS: Better surveillance of pubertal girls with obesity is crucial and can be achieved using additional information provided by an OGTT, since they appear to be at a higher risk for beta-cell exhaustion. During the OGTT, not only are the baseline and 2-hour glucose and insulin measurements useful for predicting future metabolic risks and development of T2DM in children and adolescents with obesity, but additional time measurements may also be helpful.

Development of papillae on colonies of two isopolyauxotrophic strains of Saccharomyces cerevisiae allelic in RAD6 during adenine starvation.

Papilla formation on colonies of two isopolyauxotrophic strains (ade2 his3 leu2 trp1 ura3) allelic in RAD6 was compared in order to find proper conditions for selecting mutants of Saccharomyces cerevisiae with altered starvation-induced mutability. The most promising for this purpose appeared to be culturing low numbers of colonies on suboptimal plates with a growth-limiting amount of adenine at 28 degrees C for 20 d. Inactivation of the RAD6 gene which suppresses the level of starvation-associated mutagenesis markedly enhanced papilla formation under these conditions. Formation of almost all papillae on 20-d-old colonies of BJC3 was caused by mutation. Most of the papillae (75%) were white Ade+ revertants. Three groups of these papillae were distinguished (Ade+, Ade+Rad6+ and Ade+Trp+). Both, Ade+Rad6+ and Ade+Trp+ double reversions were very probably caused by a suppressor mutation. The less frequent red papillae had the same auxotrophic markers and UV sensitivity as BJC3 but their outgrowth in liquid media was greater. It appears that creation of these papillae is caused by mutation affecting the cell response to growth limitation by low concentrations of adenine.

The involvement of the RAD6 gene in starvation-induced reverse mutation in Saccharomyces cerevisiae.

The accumulation of Ade+ revertants during adenine starvation and Trp+ revertants during tryptophan starvation in haploid polyauxotrophic strains of Saccharomyces cerevisiae occurs in a time-dependent manner. Accumulation of revertants is enhanced in Rad6- strains, suggesting that starvation-induced reversion is influenced by some of the RAD6 gene functions. The higher frequency of adaptive reversions in Rad6- strains is somewhat influenced by, but does not totally depend on, the genetic background. Therefore, the RAD6 gene product is involved in maintaining a low level not only of spontaneous mutation but also of starvation-induced reversion. The starvation-induced Ade+ and Trp+ reversions both appear to be adaptive. The analysis of growth characteristics and the genotype of revertants shows a difference between early and late-appearing revertants. These results support the hypothesis that the adaptivity of starvation-induced reversion is based on the selective fixation of random mutations, and particularly on transcription-enhanced repair and/or mutagenesis processes.

Accumulation of Ade(+) reversions in isoauxotrophic strains ofSaccharomyces cerevisioe allelic inRAD6 during adenine starvation.

A comparative method based on an analysis of accumulation of starvation-induced Ade(+) reversions and cell death during adenine starvation was developed and exploited for estimating the role ofRAD6 in the starvation-induced reversions. It was shown that inactivation ofRAD6 function inSaccharomyces cerevisioe markedly enhances the accumulation of Ade(+) reversions, and therefore it is likely that this gene is taking part in maintaining the low level of starvation-induced mutations in yeast cells.

Uracilless death and papillae formation in rad6-1 polyauxotrophic strains of Saccharomyces cerevisiae.

Both uracilless death and papillae formation during uracil starvation are markedly more extensive in rad6-1 than in RAD6 strains. Osmotic stabilization with 1 mol/L glucitol improves the growth of rad6-1 polyauxotrophic strains in supplemented minimal medium and partially suppresses both the uracilless death and cannibalistic growth of papillae on colonies.