Myoglobin with modified tetrapyrrole chromophores: Binding specificity and photochemistry

Complexes were prepared of horse heart myoglobin with derivatives of (bacterio)chlorophylls and the linear tetrapyrrole, phycocyanobilin. Structural factors important for binding are (i) the presence of a central metal with open ligation site, which even induces binding of phycocyanobilin, and (ii) the absence of the hydrophobic esterifying alcohol, phytol. Binding is further modulated by the stereochemistry at the isocyclic ring. The binding pocket can act as a reaction chamber: with enolizable substrates, apo-myoglobin acts as a 13²-epimerase converting, e.g., Zn-pheophorbide a' (13²S) to a (13²R). Light-induced reduction and oxidation of the bound pigments are accelerated as compared to solution. Some flexibility of the myoglobin is required for these reactions to occur; a nucleophile is required near the chromophores for photoreduction (Krasnovskii reaction), and oxygen for photooxidation. Oxidation of the bacteriochlorin in the complex and in aqueous solution continues in the dark.     

Temperature-dependent conformation change in spin-labeled hemoglobin

Hemoglobin was spin labeled at β-93(F9)-cysteine with N-oxy-2,2,6,6-tetramelhylpiperidinylmaleimide. The inward shift of the high-field hyperfine line (ΔH_XXX) position in the ESR spectra of the Spin label was measured aS a function of temperature. One can expect that an abrupt change in the microenvironment around the tightly bound spin label will be reflected in the function ΔH_XXX(T) as a discontinuity (break point). This was shown for aquo-, azido-. nitro- and oxyhemoglobin derivatives. The presented results suggest that the microenvironment around the tightly hound spin label in those methemoglobin derivatives that exhibit the mixed-spin state of the heme iron is prone to an abrupt change above a certain ligand-specific temperature. The change in microenvironment of the spin label is probably due to a temperature-dependent change in the tertiary structure of the protein.     

Genetic variants of hemoglobin in canine erythrocytes*

Genetic polymorphism of hemoglobin was found in the erythrocytes of dogs of seven Japanese native breeds by using starch gel electrophoresis. Analysis of parentage records of the dogs revealed that the phenotypic variation of hemoglobin is controlled by one autosomal locus with two codominant alleles, Hb^A and Hb^B. The allele Hb^A occurred only in Japanese native breeds except Shikoku. The frequency of Hb^A in the Japanese breeds was low and 0.08. All the dogs belonging to 25 European breeds and 5 oriental origin (except Japan) breeds examined in this experiments had the homozygous genotype constitution Hb^B/Hb^B.     

Weight-Based Insulin During and After Intravenous Insulin Infusion Reduces Rates of Rebound Hyperglycemia When Transitioning to Subcutaneous Insulin in the Medical Intensive Care Unit

ObjectiveHyperglycemia often occurs after the transition from intravenous insulin infusion (IVII) to subcutaneous insulin. Weight-based basal insulin initiated earlier in the course of IVII in the medical intensive care unit (MICU), and a weight-based basal-bolus regimen after IVII, can potentially improve post-IVII glycemic control by 48 hours.MethodsThis prospective study included 69 patients in MICU who were on IVII for ≥24 hours. Exclusions were end-stage renal disease, type 1 diabetes mellitus, and the active use of vasopressors. The intervention group received weight-based basal insulin (0.2-0.25 units/kg) with IVII and weight-based bolus insulin after IVII. The control group received current care. The primary end points were glucose levels at specific time intervals up to 48 hours after IVII.ResultsThere were 25 patients in the intervention group and 44 in the control group. The mean age of the patients was 59 ± 15 years, 32 (47%) were men, and 52 (78%) had prior diabetes mellitus. The 2 groups were not different (acute kidney injury/chronic kidney disease, pre-existing diabetes mellitus, illness severity, or nothing by mouth status after IVII), except for the steroid use, which was higher in the control group than in the intervention group (34% vs 12%, respectively). Glucose levels were not lower until 36 to 48 hours after IVII (166.8 ± 39.1 mg/dL vs 220.0 ± 82.9 mg/dL, P < .001). When controlling for body mass index, nutritional status, hemoglobin A1C, and steroid use, glucose level was lower starting at 12 to 24 hours out (166.87 mg/dL vs 207.50 mg/dL, P = .015). The frequency of hypoglycemia was similar between the 2 groups (5.0% vs 7.1%). The study did not reach target enrollment.ConclusionThe addition of weight-based basal insulin during, and basal-bolus insulin immediately after, IVII in MICU results in better glycemic control at 24 hours after IVII with no increased hypoglycemia.     

Evaluation of Lipohypertrophy in Patients With Type 1 Diabetes Mellitus on Multiple Daily Insulin Injections or Continuous Subcutaneous Insulin Infusion

ObjectiveTo determine lipohypertrophy (LH) in patients with type 1 diabetes mellitus (T1DM) on multiple daily insulin injections (MDII) or continuous subcutaneous insulin infusion (CSII) and to reveal the factors associated with the development and severity of LH.MethodsSixty-six patients with T1DM treated with MDII (n = 35, 53%) or CSII (n = 31, 47%) for at least 1 year were included. LH localizations were detected with palpation and ultrasonography (USG).ResultsThe LH detection rate with USG was significantly higher than that by palpation in the whole group (P < .001). The LH was detected with USG in 30 (85.7%) patients in the MDII group and 22 (71.0%) patients in the CSII group (P = .144). Advanced LH was detected in 13 (37.1%) of the patients treated with MDII and in 3 (9.7%) of the patients treated with CSII. LH was more severe in the MDII group than in the CSII group (P = .013). Diabetes duration and length of infusion set use were significantly longer and body mass index, hypoglycemia, and complication rates were higher in patients with LH than those in patients without LH (P < .05). A positive correlation was found between LH severity and HbA1C and insulin dose (P < .05, for both). MDII as insulin administration method, incorrect rotation, and a history of ketosis were found to be the most related factors with LH severity in a multiple linear regression analysis (P < .05).ConclusionUSG might be an effective approach for detecting and evaluating the severity of LH. MDII might cause more severe LH than CSII in patients with T1DM. In this study, LH was found to be associated mostly with incorrect rotation technique and a history of ketosis.     

Detection of triclosan using 2-domain hemoglobin promoter of Daphnia magna

Triclosan has been widely used as an antimicrobial agent. However, triclosan was found to cause toxicity, including muscle contraction disturbances, carcinogenesis, and endocrine disorders. In addition, it was found to affect central nervous system function adversely and even have ototoxic effects. Conventional methods for detecting such triclosan can be performed easily. However, the conventional detection methods are inadequate in precisely reflecting the impact of toxic substances on stressed organisms. Therefore, a test model for the toxic environment at the molecular level through the organism is needed. From that point of view, Daphnia magna is being used as a ubiquitous model. D. magna has the advantages of easy cultivation, a short lifespan and high reproductive capacity, and high sensitivity to chemicals. Therefore, the protein expression pattern of D. magna that appear in response to chemicals can be utilized as biomarkers for detecting specific chemicals. In this study, we characterized the proteomic response of D. magna following triclosan exposure via two-dimensional (2D) gel electrophoresis. As a result, we confirmed that triclosan exposure completely suppressed D. magna 2-domain hemoglobin protein and evaluated this protein as a biomarker for triclosan detection. We constructed the HeLa cells in which the GFP gene was controlled by D. magna 2-domain hemoglobin promoter, which under normal conditions, expressed GFP, but upon triclosan exposure, suppressed GFP expression. Consequently, we consider that the HeLa cells containing the pBABE-HBF3-GFP plasmid developed in this study can be used as novel biomarkers for triclosan detection.     

Anemia in Patients With Diabetes and Prediabetes With Normal Kidney Function: Prevalence and Clinical Outcomes

ObjectiveAnemia is a known complication of diabetes mellitus (DM); however, its prevalence and prognostic relevance in patients with DM and pre-DM with normal kidney function have not been well defined. This study assessed the prevalence of anemia in patients with DM and pre-DM and evaluated its association with clinical outcomes during a 4-year follow-up period.MethodsThis retrospective analysis included patients with DM and pre-DM referred to the Meir Medical Center Endocrine Institute in 2015. Patients with an estimated glomerular filtration rate (eGFR) of <60 mL/min or any other recognized cause of anemia were excluded. The risk of developing microvascular or macrovascular complications or of death during the 4-year follow-up period was determined.ResultsA total of 622 patients (408 with DM and 214 with pre-DM) were included. The mean age of the patients was 64 ± 10.6 years, and 70% were women. The baseline hemoglobin A1C level was 7.1% ± 1.7% (54 mmol/mol), and the eGFR was 86.1 ± 15.3 mL/min. At the time of inclusion, 77 patients (19%) with DM and 23 (11%) with pre-DM had anemia (hemoglobin level 11.9 ± 0.8 and 11.8 ± 0.8 g/dL, respectively), compared with normal hemoglobin levels of 13.8 ± 0.9 and 13.7± 0.9 g/dL, respectively, in the others. A multivariable analysis demonstrated an inverse correlation between baseline hemoglobin (as a continuous variable) and mortality (P = .035), microvascular complications (P = .003), and eGFR decline (P < .001) but not between baseline hemoglobin and macrovascular complications (P = .567).ConclusionThis study found a significant prevalence of anemia unrelated to renal failure, both in patients with DM and pre-DM. Anemia in these patients is associated with the development of microvascular complications, eGFR decline, and mortality. These results underscore the need for intensive lifestyle and pharmacologic interventions in these patients.     

Heme-based sensors: theoretical modeling of heme-ligand–protein interactions

Heme proteins are uniquely adapted to bind the important diatomic molecules O(2), NO and CO. An increasing number of heme proteins are being discovered that sense these molecules and thereby regulate a variety of biochemical responses. The interactions of diatomic molecules with heme, and with the surrounding protein, are therefore of great interest. Recent theoretical modeling, using density functional theory, captures many features of these interactions, as exemplified by the well-characterized heme protein myoglobin. Important details, however, especially the mutual influence of the bound diatomic molecule and the proximal ligand, remain to be clarified.     

Expert Roundtable on Continuous Glucose Monitoring

ObjectiveThe objective of this study was to define an expert opinion on continuous glucose monitoring (CGM) in persons with type 2 diabetes mellitus, including its advantages, barriers, and best clinical practices for initiation, patient-clinician communication, and data management.MethodsA series of virtual discussions was held to recommend improvements to clinical practice and design clinical tools for primary care clinicians. Participants included endocrinologists, primary care physicians, physician assistants, advanced practice nurses, and diabetes care and education specialists.ResultsThe expert panels recommended CGM as a supplement to blood glucose monitoring and hemoglobin A1c for managing diabetes in persons with diabetes (PWDs). CGM can help predict potential pitfalls in glycemic management, including hypo and hyperglycemic excursions, which directly influence lifestyle changes, medication initiation, and dosing decisions. A toolkit was designed with practical guidance on the integration of CGM into clinical practice, interpretation of results, clinical guidelines, a patient action plan, and other useful management tools.ConclusionThis review summarizes the findings from a roundtable discussion with endocrinology and primary care clinicians, a discussion of the advantages and challenges of CGM, and clinical approaches to improving the care of PWDs. CGM offers more detailed tracking of glucose levels than blood glucose monitoring or hemoglobin A1c, and it can detect asymptomatic hypoglycemia. Specialized education of providers, the cost to patients and providers, and data management are barriers to the widespread adoption of CGM for PWDs.     

Basal Insulin Degludec and Glycemic Control Compared to Aspart Via Insulin Pump in Type 1 Diabetes (BIGLEAP): A Single-Center,Open-Label,Randomized, Crossover Trial

ObjectiveWe compared the efficacy of the second-generation basal insulin degludec (IDeg) to that of insulin aspart via pump using continuous glucose monitoring in patients with well-controlled type 1 diabetes.MethodsIn this 40-week, single-center, randomized, crossover-controlled trial, adults with well-controlled type 1 diabetes (hemoglobin A1C of <7.5% [<58 mmol/mol]) (N = 52) who were using an insulin pump and continuous glucose monitoring were randomized to 1 of 2 treatments for a 20-week period: a single daily injection of IDeg with bolus aspart via pump or a continuous subcutaneous insulin infusion (CSII) with aspart, followed by crossover to the other treatment. The primary endpoint was time in range (70-180 mg/dL) during the final 2 weeks of each treatment period.ResultsFifty-two patients were randomized and completed both treatment periods. The time in range for IDeg and CSII was 71.5% and 70.9%, respectively (P = .553). The time in level 1 hypoglycemia for the 24-hour period with IDeg and CSII was 2.19% and 1.75%, respectively (P = .065). The time in level 2 hypoglycemia for the 24-hour period with IDeg and CSII was 0.355% and 0.271%, respectively (P = .212), and the nocturnal period was 0.330% and 0.381%, respectively (P = .639). The mean standard deviation of blood glucose levels for the 24-hour period for IDeg and CSII was 52.4 mg/dL and 51.0 mg/dL, respectively (P = .294). The final hemoglobin A1C level for each treatment was 7.04% (53 mmol/mol) with IDeg, and 6.95% (52 mmol/mol) with CSII (P = .288). Adverse events were similar between treatments.ConclusionWe observed similar glycemic control between IDeg and insulin aspart via CSII for basal insulin coverage in patients with well-controlled type 1 diabetes.