Asghar Ghasemi

Scientific knowledge generation can be conceptually divided into two complementary, distinct, and equally important phases: exploratory, in which hypotheses are generated to represent data patterns, and confirmatory (refutational), in which predictions based on these hypotheses are tested by collecting new data to provide evidence of practical/clinical utility. However, scientific publishing weights confirmatory research more heavily than exploratory research. The devaluation of exploratory research pressures authors to disguise their exploratory work as confirmatory, leading to questionable research practices (QRPs), including p-hacking (massaging data to yield statistically significant results), HARKing (hypothesizing after results are known), cherry-picking (selective outcome reporting), and fishing expeditions (data dredging). These bad research practices increase false-positive rates and jeopardize the credibility of scientific findings, leading to one of science's worst failings: the replication crisis. Radical reform in how science is conducted and published, including preregistration, redefining statistical thresholds, advancing research training, providing more room for exploratory research, and changing the wrong incentives in scientific practice, may partially solve the problem of blending and its associated QRPs. In conclusion, the distinction between exploratory and confirmatory research is crucial for better bench-to-bed translation of preclinical evidence. Tentative exploratory results must be confirmed before establishing clinical utility.

Introduction: Research is a purpose-directed activity. Although aims, goals, objectives, and targets are interrelated statements of purpose, they differ in hierarchy, scope, measurability, timeframe, and significance. This brief review clarifies these terms and describes the characteristics of a good research objective. Methods: Relevant papers were analyzed to delineate the definitions, interrelations, and distinctions among aims, goals, objectives, and targets in research projects. Results: The apparent purpose of a study (objectives and goals) addresses specific research questions, whereas its deeper purpose (aim) represents the underlying reason for conducting the study. Aims express ideals and long-term direction; goals outline the primary intent and problem to be addressed; objectives link intention to action by specifying how the research question will be answered; and targets indicate desired values of outcome indicators. A strong objective should be SMART (specific, measurable, achievable, relevant, and time-bound). Conclusion: Clear articulation of research purpose facilitates translation of findings into practice and enhances the overall quality of research.

Salivary nitrite (SNO₂), a marker of oral nitrate-reducing capacity and nitric oxide (NO) bioavailability, often impaired in type 2 diabetes (T2DM). This study aimed to investigate the associations between SNO₂ concentration, and metabolic, vascular, and renal parameters in patients with T2DM. Sixty-four adults with T2DM (53.9 ± 7.2 years, 45.3% men, diabetes duration 8.3 ± 6.2 years) participated in this cross-sectional study. Salivary NO₂ concentrations, glycemic parameters, blood pressure (BP) indices, renal function, lipid profiles, liver function, and systemic NO metabolites were measured. Participants with high- and low-SNO₂ (< and ≥ 69.3 µmol/L) were compared for cardiometabolic parameters. Compared with the low-SNO₂ group, participants with higher SNO₂ had lower HbA1c (6.2% vs. 6.9%, P = 0.040), fasting insulin (6.1 vs. 8.2 µU/mL, P = 0.007), HOMA-IR (2.1 vs. 3.3, P = 0.003), and C-peptide (1.3 vs. 1.7 ng/mL, P = 0.023), with higher QUICKI (0.34 vs. 0.32, P = 0.003). Fasting serum glucose was marginally lower (142 vs. 167 mg/dL, P = 0.069) in the high- compared to the low-SNO₂ group. Median serum nitric oxide metabolites (NOx) concentrations were higher in the high-SNO₂ group (51.1 vs. 29.1 µmol/L, P = 0.015). Salivary nitrate (NO₃) (694 vs. 463 µmol/L, P = 0.035) and NO₂ (153 vs. 20.6, P = 0.001) were also higher in the high- compared to low-SNO₂ group. No significant difference was observed in BP measures, lipid profile, and liver and renal function test across groups. High-SNO₂ levels were associated with greater glycemic control, insulin sensitivity, and NO bioavailability in patients with T2DM.

Context: Reference values (RVs) are essential tools for medical decision-making, used to interpret an individual’s health status and playing a crucial role in patient care. In addition to age, sex, and inherent biological variability, multiple determinants, including ethnicity, genetic background, dietary habits, environmental factors, and lifestyle, which vary across different populations, play a significant role in the establishment of RVs. Thus, each population requires its own RVs to ensure their effectiveness. Evidence Acquisition: In this review, we summarize RVs reported in the Tehran Lipid and Glucose Study (TLGS) between 2010 and 2026, covering 20 analytes measured in apparently healthy participants, including 16 in adults and 4 in pediatrics. Relevant TLGS publications were identified, and their findings were compared with corresponding international data. Results: RVs were provided for 20 parameters, classified into three categories: (1) Glucose, insulin, insulin resistance/sensitivity indices, and lipid profile; (2) thyroid function tests [thyroid-stimulating hormone (TSH) and free thyroxine (T4)] and autoimmunity [thyroid peroxidase antibody (TPO-Ab)]; (3) other variables, including creatinine and minerals (serum zinc and magnesium), and serum nitric oxide metabolites. Conclusions: The RVs determined by the TLGS provide a population-specific framework for the Iranian population and may serve as a more accurate tool for classification and clinical interpretation than common global RVs. These data emphasize the importance of developing localized RVs to enhance diagnostic precision and improve population health outcomes.

Nitric oxide (NO) is a small, bioactive molecule with diverse physiological functions. It is generated both enzymatically by NO synthases (NOS) and non-enzymatically through the nitrate-nitrite-NO reduction pathway. Recent studies have renewed interest in nitrate-based regulation of NO, highlighting a compartmentalization model of nitrate homeostasis. In this model, excess NO is rapidly oxidized to nitrite, which is then oxidized to nitrate, a more stable species that limits oxidative damage. Nitrate is differentially distributed across tissues, allowing both storage and rapid mobilization to maintain NO availability. Human and animal studies show that nitrate concentrations in skeletal muscle, plasma, and liver are approximately 100, 35, and 10 nmol/g, respectively, corresponding to a skeletal muscle-to-plasma-to-liver ratio of ~3:1:0.3. The large skeletal muscle reservoir and its higher muscle-to-plasma gradient support the release of nitrate into the circulation when needed. In contrast, the liver-to-plasma ratio < 1 suggests active hepatic uptake of circulating nitrate. Together, these findings support a compartmentalized system in which nitrate storage and flux contribute to whole-body NO homeostasis. Understanding this model may have implications for exercise physiology, metabolic regulation, and liver pathophysiology – all conditions in which NO biology plays a critical role.

This study investigates the effect of pasteurized Bacteroides thetaiotaomicron (PB.t) and its extracellular vesicles (B.t-EVs) on metabolic parameters, diabetes- and inflammation-related gene expression, and microbiota composition in type 2 diabetes mellitus (T2DM). A total of forty-eight male Wistar rats were randomly divided into normal controls (NC, n=24) and T2DM-induced rats (n=24), and each group was further subdivided to receive phosphate-buffered saline (PBS), PB.t, or B.t-EVs by gavage daily for five consecutive weeks. The effects on obesity indices, glycemic markers, lipid profile, expression of diabetes- and inflammation-related genes in the liver and colon, and targeted changes in gut microbiota were assessed. Treatment with B.t-EVs and PB.t was associated with reductions in obesity indices (body weight, body mass index, and Lee index) and fasting blood glucose compared to the T2DM-PBS group; however, this reduction was significant only in T2DM-B.t-EVs rats (P≤0.0142). Both interventions yielded significant improvements in metabolic parameters, as demonstrated by decreased serum insulin, triglyceride, and total cholesterol levels, reduced homeostatic model assessment for insulin resistance (HOMA-IR), and improved glucose tolerance (all P≤0.0382). Both treatments reduced with downregulation of endocannabinoid system receptor 1 (CB1) expression and increased CB2 and phosphoinositide 3-kinase/protein kinase B (PI3K/Akt) gene expression in the liver (all P≤0.0018). In the colon, PB.t and B.t-EVs significantly downregulated interleukin (IL)-1β, IL-6, and CB1 genes. They also upregulated IL-4, IL-10, and CB2 genes (all P≤0.0004). Targeted microbiota analysis showed increased abundances of Bacteroidetes, Faecalibacterium prausnitzii, and B.t, accompanied by a reduced level of Firmicutes, Actinobacteria and Firmicutes/Bacteroidetes (F/B) ratio (P≤0.0492). Additionally, treatment with B.t-EVs increased the abundance of Clostridium cluster IV (P=0.0085). Histological findings indicated reduced pancreatic damage in the treated groups. Altogether, these results suggest that PB.t and B.t-EVs, as paraprobiotic and postbiotic candidates, may improve metabolic health, reduce inflammation, and modulate gut microbiota composition in T2DM.

Background: Type 2 diabetes mellitus (T2DM) is a prevalent disorder with significant complications and mortality. Gut microbiota plays a role in metabolic homeostasis, and dysbiosis may contribute to inflammation and insulin resistance (IR). Objectives: This study aimed to investigate the effect of Bacteroides thetaiotaomicron on glycemic and IR markers, lipid profiles, and the expression of diabetes- and inflammation-related genes, as well as the abundance of targeted gut microbiota in a rat model of T2DM. Methods: Thirty-two male Wistar rats were randomly assigned to normal control groups or a high-fat diet/streptozotocin-induced T2DM group. Each group received 5-week oral B. thetaiotaomicron (1×109 CFU/mL) or phosphate-buffered saline (PBS). Anthropometric and metabolic measures were compared pre- and post-intervention. Expression of diabetes-related genes (PI3K, Akt) in the liver, inflammation-related genes (IL-6, IL-10, IL-1β, IL-4) in the colon, cannabinoid receptors (CB1, CB2) in both tissues, and changes in gut microbiota composition were evaluated using quantitative PCR. Results: Compared to the T2DM-PBS group, administration of B. thetaiotaomicron to T2DM rats led to significant reductions in body weight (BW) (8%), Body Mass Index (BMI) (21%), Lee index (10%), fasting blood glucose (FBG) (16%), insulin (46%), homeostatic model assessment of IR (HOMA-IR) (56%), triglycerides (TG) (34%), total cholesterol (TC) (29%), and low-density lipoprotein cholesterol (25%) (all P ≤ 0.012). This intervention was associated with reduced expression of CB1 (1.81-fold) and increased expression of PI3K (4.91-fold), Akt (3.55-fold), and CB2 (2.26-fold) (all P < 0.0001). Furthermore, expression of IL-1β (1.76-fold), IL-6 (2.10-fold), and CB1 (1.64-fold) was significantly down-regulated, whereas expression of other inflammation-related genes including IL-4 (2.43-fold), CB2 (1.47-fold), and IL-10 (4.6-fold) was up-regulated (all P ≤ 0.0009). Moreover, significant changes in targeted gut microbiota were observed (a reduction in the abundance of Bacillota and Actinomycetota and an increase in Bacteroidota, Faecalibacterium prausnitzii, B. thetaiotaomicron, and Clostridium cluster IV). Conclusions: Bacteroides thetaiotaomicron improved anthropometric measures, glycemic indices, IR, lipid profiles, and regulated the expression of diabetes- and inflammation-related genes, along with modification of gut microbiota composition in a T2DM rat model.

Background: Obesity and type 2 diabetes (T2D) are associated with nitric oxide (NO) deficiency. L-citrulline (Cit), a substrate for NO synthesis, has been suggested as a treatment for obesity and T2D. Objectives: This study aims to determine the effects of Cit on body weight, food intake, and water consumption in obese T2D male and female rats. Methods: The T2D was induced using a high-fat diet (HFD) and a low dose of streptozotocin (STZ). Obese male (n = 30) and female (n = 30) rats with T2D were divided into five groups (n = 6/group) that received Cit (0, 1, 4, 7, and 10 g/L in drinking water for 8 weeks). Body weight, food intake, and water consumption were measured every week. Serum Cit and nitrite+nitrate (NOx) concentrations were measured at weeks 0, 4, and 8, and serum fasting glucose was measured at week 8. Results: Compared to non-treated T2D rats, Cit-treated male rats had lower body weight (11.3%, 13.0%, and 11.6% at doses of 4, 7, and 10 g/L), lower food intake (4.7% and 5.5% at doses of 4 and 7 g/L), and water consumption (7% at dose 7 g/L). In female rats, Cit decreased body weight (7.2%, 8%, and 7.3% at doses of 4, 7, and 10 g/L), food intake (4.0% and 5.0% at doses of 4 and 7 g/L), and water consumption (5% and 6.6% at doses of 4 and 7 g/L; all P < 0.001). The body weight and food intake-lowering effects of Cit were higher in T2D male rats than females (all P < 0.05), but decreased water consumption was comparable between sexes. A Cit dose of 7 g/L was most effective in reducing all measured parameters in both sexes. Conclusions: The Cit decreased body weight, food intake, and water consumption in obese T2D male and female rats. These effects were sex- and dose-dependent.