Efficacy of Semaglutide in Overweight and Obese Patients with Type 1 Diabetes

Introduction: More than two-thirds of patients with type 1 diabetes (T1D) are overweight (OW) and/or obese (OB) in the USA and Western Europe, resulting in insulin resistance as in type 2 diabetes. None of the currently available glucagon like polypeptide 1 (GLP-1) analogs are approved for patients with T1D. A higher dose of semaglutide has been approved by the Food and Drug Administration (FDA) for subjects with body mass index (BMI) >27 kg/m2. We evaluated the real-world use of semaglutide in patients with T1D. Methods: This was a retrospective chart review study of 50 OW or OB patients with T1D who were initiated on semaglutide and followed for 1 year. The control group comprised of 50 computer-matched patients (for sex, race, weight, BMI, and diabetes duration) during a similar time period and were not on any weight loss medications. Results: Most patients (92%) were non-Hispanic white in both arms. Mean ± standard deviation (SD) age and duration of diabetes were 42 ± 11 and 27 ± 12 years, respectively. The continuous glucose monitors (CGM), insulin pump use, baseline BMI and body weight were also similar in the two groups. Baseline glycosylated hemoglobin (HbA1c) was insignificantly lower in the semaglutide group (7.6% vs. 8.2%, respectively; P = non-significant [NS]). Total daily insulin dose (TDD) and insulin dose per kg body weight were higher in the semaglutide group at baseline with no difference in basal or prandial insulin dose. There were significantly greater declines in mean (±SD), BMI (7.9% ± 2.6%), body weight (15.9 lbs ± 5.4 lbs), HbA1c, CGM glucose SD and coefficient of variation (CV), and increase in CGM time in range (TIR) in the semaglutide group compared to the control group with no difference in insulin dose changes, time above range (TAR), or time below range (TBR). Conclusions: We conclude that use of semaglutide in patients who are OW and/or OB with T1D was effective in lowering body weight and BMI, and improving glycemic metrics in this pilot real-world study. We strongly recommend performing prospective, large-randomized clinical trials with newer GLP-1 analogs like semaglutide and tirzepatide (twin-cretin) for subjects with T1D associated with OW and/or OB.

Phytase activity in Aspergillus fumigatus isolates

Extracellular phytase from Aspergillus fumigatus isolates was characterized and their genes were cloned and sequenced. Based on their banding pattern in SDS-PAGE all phytases were found to be glycosylated and have similar molecular mass. A correlation between lower optimum pH (4.0) and a higher optimum temperature (70 degrees C) was found in these enzymes. All enzymes characterized displayed a lower specific activity for phytic acid and were more susceptible to proteolytic degradation than the Aspergillus niger phytase that is now commercially available. DNA sequencing established almost no sequence variation in any of the genes and no correlation is evident between a specific amino acid sequence and any physicochemical and catalytic properties of the enzymes. Despite two of the isolates having identical deduced amino acid sequence, characterization of the enzymes encoded by these two identical genes revealed differences in both pH and temperature optimum. This suggests that differences in pH and temperature optimum in these four isolates of A. fumigatus may be due in part to subtle differences in posttranslational modification.

Effects of chemical denervation with 6-hydroxydopamine on myocardial responsiveness to isoproterenol in rabbits

This study examined the hypothesis that chemical denervation with 6-hydroxydopamine (6-OHDA) would increase myocardial responsiveness to isoproterenol. Five days previously, 15 New Zealand white rabbits were given 60 mg/kg 6-OHDA intravenously. Fifteen control rabbits received vehicle. Hemodynamic, coronary blood flow (CBF), and cardiac output measurements were obtained before and during isoproterenol infusion (0.5 microgram/kg/min for 15 min). Norepinephrine tissue content, beta-adrenoceptor number (Bmax) and affinity (Kd), cyclic AMP content and cyclic AMP-phosphodiesterase (PDE) activity were measured in the subepicardium (EPI) and subendocardium (ENDO). Myocardial norepinephrine content was significantly decreased from 1263 +/- 292 (EPI) and 874 +/- 221 ng/g tissue (ENDO) in the control to 148 +/- 33 (EPI) and 90 +/- 45 ng/g tissue (ENDO) in the denervated group. There were no significant changes in cyclic AMP-PDE activity or Bmax and Kd of beta-adrenoceptors. Cyclic AMP content was similar at baseline, but controls had a significantly larger increase (123-155%) during isoproterenol infusion when compared to the denervated group (27-37%). The denervated animals showed a smaller increase in cardiac output during isoproterenol infusion (from 203 +/- 30 to 235 +/- 26 ml/min), when compared to the control animals (from 135 +/- 18 to 216 +/- 42 ml/min). Baseline CBF was significantly higher in the EPI but not ENDO of the denervated group (185 +/- 20 ml/100 g/min in EPI and 150 +/- 8 in ENDO) compared to the control group (108 +/- 13 in EPI and 133 +/- 17 in ENDO). The relative increase in CBF during isoproterenol infusion was smaller in the denervated group (44-45%) than the control group (107-109%). Isoproterenol infusions of 0.1 and 2.5 micrograms/kg/min showed similarly depressed coronary blood flow responses in denervated animals. Thus, the chemically denervated animals did not have beta-adrenoceptor upregulation, exhibited a lesser increase in cyclic AMP with isoproterenol, and had a reduced functional and coronary blood flow response to isoproterenol. This occurred without any significant change in beta-adrenoceptor number or affinity, or in cyclic AMP-phosphodiesterase activity, indicating there may be receptor uncoupling or other changes in the signal transduction pathway.

Role of ischemia-reperfusion on myocardial cyclic AMP and cyclic AMP phosphodiesterase: effects of amrinone on regional myocardial force and shortening

This study tested the hypothesis that a reperfused ischemic myocardial region of the dog heart would be unable to increase its function in response to amrinone, a specific cyclic AMP phosphodiesterase (cAMP-PDE) inhibitor, due to loss of cAMP-PDE activity in the region. The global contractility (+dp/dtmax), regional percent shortening (ultrasonic crystals), and developed force (miniature force gauge) were measured on a continuous basis throughout a 6-hour experiment and regional blood flow (radioactive microspheres) in open-chest pentobarbital-anesthetized mongrel dogs. The left anterior descending coronary artery (LAD) was isolated and ligated for 2 hours and allowed to reperfuse for 4 hours. This myocardial region was compared to a nonischemic region supplied by the circumflex artery. At the end of the 4-hour reperfusion period, 9 dogs were treated with amrinone (5 mg/kg) and three dogs were not treated with amrinone. The hearts were rapidly excised and frozen in liquid nitrogen. Cyclic AMP and cAMP-PDE activity was determined in homogenates of myocardial tissue. Blood flow decreased during occlusion in the LAD region and returned toward control with reperfusion. Flow increased nonsignificantly with amrinone. the basal cyclic AMP content of the two regions was not different. The cAMP-PDE activity was reduced 24% in the LAD region compared to the control region. There were no ischemia-induced changes in the enzyme characteristics. These experiments demonstrated increased global function in the ischemic reperfused myocardium after amrinone was administered (dP/dtmax: 2092 +/- 538 to 3277 +/- 688 mmHg/sec).(ABSTRACT TRUNCATED AT 250 WORDS)

Relationship between adenylate cyclase activity and regional myocardial energetics in experimental left ventricular hypertrophy

The aim of this study was to examine the responsiveness of the hypertrophied left ventricle to beta-adrenergic stimulation in a pressure overload model produced by valvular aortic stenosis and characterized by reduced beta-adrenoceptor number. The study was designed to correlate changes in global and regional cardiac work and energetics in response to isoproterenol with adenylate cyclase activity. Eleven anesthetized dogs with left ventricular hypertrophy and 11 controls were studied at rest and during 0.5 and 1.0 micrograms/kg/min isoproterenol infusion. We measured regional work from segment length and force changes with ultrasonic dimension crystals and miniature force gauges in addition to arterial and left ventricular blood pressure and cardiac output. Regional myocardial oxygen consumption was calculated from O2 extraction using microspectrophotometry and blood flow using radioactively labeled microspheres. Adenylate cyclase activity was assayed at baseline and after stimulation with forskolin. Isoproterenol significantly increased heart rate, dP/dtmax, cardiac output, and external work to similar levels in control and hypertrophied animals. Similarly, regional work increased from 463 +/- 115 to 995 +/- 584 g x mm/min for controls and from 392 +/- 156 to 1175 +/- 577 for hypertrophied dogs with high dose isoproterenol. Regional O2 consumption also increased to similar levels (20.3 +/- 14.7 vs 16.2 +/- 6.3 ml O2/min/100 g) in both groups. Adenylate cyclase activity was lower in hypertrophy at baseline (23.9 +/- 7.3 vs 62.9 +/- 14.2 pM/min/mg protein for controls), but was the same as for controls with forskolin stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)