Human brain hexokinase: Determinants of mitochondrial binding and mechanism of nucleotide release

Adenosine 5‘ – triphosphate (ATP) can release hexokinase I (HKI) from its binding site on the outer mitochondrial membrane, but the mechanism of ATP release of HKI from mitochondria is unclear. ATP binds to the C–terminal half of HKI as a substrate and to the N–terminal half near the membrane binding element. ATP may also bind to the voltage dependent anion channel (VDAC), the integral membrane component that putatively targets HKI to the mitochondrion. The fluorescent nucleotide analogue 2‘,3‘ – O–(2,4,6–trinitrophenyl) adenosine 5 ‘ –diphosphate (TNP–ADP) binds with high affinity to the C–terminal half of HKI (Kd = 0.79 ± 0.09 μM) and to VDAC (Kd = 1.3 ± 0.1 μM), but not to the N–terminal half of HKI (Kd \u3e 50 μM). ATP competes with TNP–ADP for binding sites on HKI (KA = 190 ± 20 μM) and VDAC (KA = 550 ± 40 μM), but CTP does not displace TNP–ADP from either HKI or VDAC. Other trinitophenyl nucleotides (TNP–ATP, TNP–AMP, and TNP–CTP) bind with high affinity to HKI and VDAC. ATP and trinitrophenyl nucleotides individually release wild–type HKI from mitochondria; however, CTP is ineffective as an agent of release. ATP and ADP–TNP release the truncated N–domain of HKI from mitochondria, excluding nucleotide binding to either the N– or C–half of HKI in the release mechanism. Results here are consistent with a release mechanism caused by the binding of ATP or TNP–ADP to VDAC

Acute Effects of Subcutaneous Injection of Glucagon and/or Oral Administration of Glycerol on Blood Metabolites and Hormones of Holstein Dairy Cows Affected with Fatty Liver Disease

To study the effects of the subcutaneous injection of glucagon and/or oral administration of glycerol on blood metabolites and hormones of Holstein dairy cows induced with fatty liver disease, twenty multiparous cows were fed a dry cow ration supplemented with 12 kg of cracked corn during the dry period to increase the likelihood of fatty liver disease development. Cows with a body condition score (BCS) of ≥ 3.5 points (0-5 scale) were randomly assigned to one of four treatment groups--saline, glucagon, glucagon plus glycerol, and glycerol. Following treatment, serial blood samples were collected to determine the effect of glucagon and/or glycerol on blood composition. Glucagon injection alone increased postpartal plasma glucose, glucagon, and insulin and decreased plasma NEFA and TAG. Glucagon plus glycerol treatment increased and sustained postpartal plasma glucose and insulin and decreased postpartal plasma NEFA and TAG. Administration of glycerol alone increased plasma glucose and decreased plasma NEFA during the postpartal period. Early postpartal treatment of cows with glucagon and/or glycerol increased plasma glucose and decreased plasma NEFA. This response would suggest that these treatments would decrease the likelihood of fatty liver disease in dairy cows

Acute Effects of Postpartal Subcutaneous Injection of Glucagon and/or Oral Administration of Glycerol on Blood Metabolites and Hormones and Liver Lipids and Glycogen of Holstein Dairy Cows Induced with Fatty Liver Disease

The effects of subcutaneous injection of glucagon and/or oral administration of glycerol on blood metabolites and hormones of Holstein dairy cows induced with fatty liver disease was studied. Twenty multiparous cows were fed a dry cow ration supplemented with 6 kg of cracked corn during the dry period to increase the likelihood of fatty liver disease development. Cows with a body condition score of ≥ 3.5 points (1-5 scale) were assigned randomly to one of four treatment groups--saline, glucagon, glucagon plus glycerol, and glycerol. Following treatment, serial blood samples were collected to determine the effect of glucagon and/or glycerol on blood composition. Glucagon injection alone increased postpartal plasma glucose, insulin, glucagon, and plasma urea nitrogen and decreased plasma nonesterified fatty acids (NEFA). Glucagon plus glycerol treatment increased and sustained postpartal plasma glucose, insulin and decreased postpartal plasma NEFA. Administration of glycerol alone increased plasma triacylglycerol (TAG) and decreased plasma NEFA during the postpartal period. Early postpartal treatment of cows with glucagon and/or glycerol increased plasma glucose and decreased plasma NEFA. This response would suggest that these treatments with glucagon and/or glycerol would decrease the likelihood of fatty liver disease in dairy cows

Human brain hexokinase: Determinants of mitochondrial binding and mechanism of nucleotide release

Adenosine 5‘ – triphosphate (ATP) can release hexokinase I (HKI) from its binding site on the outer mitochondrial membrane, but the mechanism of ATP release of HKI from mitochondria is unclear. ATP binds to the C–terminal half of HKI as a substrate and to the N–terminal half near the membrane binding element. ATP may also bind to the voltage dependent anion channel (VDAC), the integral membrane component that putatively targets HKI to the mitochondrion. The fluorescent nucleotide analogue 2‘,3‘ – O–(2,4,6–trinitrophenyl) adenosine 5 ‘ –diphosphate (TNP–ADP) binds with high affinity to the C–terminal half of HKI (Kd = 0.79 ± 0.09 μM) and to VDAC (Kd = 1.3 ± 0.1 μM), but not to the N–terminal half of HKI (Kd > 50 μM). ATP competes with TNP–ADP for binding sites on HKI (KA = 190 ± 20 μM) and VDAC (KA = 550 ± 40 μM), but CTP does not displace TNP–ADP from either HKI or VDAC. Other trinitophenyl nucleotides (TNP–ATP, TNP–AMP, and TNP–CTP) bind with high affinity to HKI and VDAC. ATP and trinitrophenyl nucleotides individually release wild–type HKI from mitochondria; however, CTP is ineffective as an agent of release. ATP and ADP–TNP release the truncated N–domain of HKI from mitochondria, excluding nucleotide binding to either the N– or C–half of HKI in the release mechanism. Results here are consistent with a release mechanism caused by the binding of ATP or TNP–ADP to VDAC.</p

Effects of glucagon, glycerol, and glucagon plus glycerol on gluconeogenesis, lipogenesis, and lipolysis in periparturient Holstein cows

The objective of this study was to investigate the effect of daily glucagon subcutaneous injections of 15 mg and oral administration of 400 mL glycerol during the first 14 d postpartum on the rates of gluconeogenesis in liver and lipogenesis and lipolysis in adipose tissues obtained from dairy cows with fatty liver syndrome (FLS). To induce FLS, 16 multiparous cows with body condition score of ≥ 3.5 (1-5 scale) cows were daily fed dry-cow ration plus 6 kg of cracked corn during the last 6 weeks of dry period. Cows were assigned equally and randomly to 4 treatment groups: saline, glycerol, glucagon, and glucagon plus glycerol. Liver and adipose tissue slices were incubated with 10 nM glucagon and 1 nM tumor necrosis factor-alpha (TNF-α). Glucose synthesis rates from propionic acid and alanine were measured in liver, and glycerol release rates and fatty acid synthesis rates were measured in adipose tissues. Glucagon injections and glycerol oral administration did not affect the rates of gluconeogensis or lipolysis. Lipogenesis rates tended to decrease with glucagon and glycerol treatments. Incubation of adipose and liver tissues with TNF-α and glucagon did not affect glucose synthesis rates or fatty acid breakdown or synthesis in adipose tissue. We conclude that glucagon and glycerol treatments alleviate the symptoms of FLS by long-term effects rather than direct effects on liver or adipose metabolic pathways.</p

Acute Effects of Subcutaneous Injection of Glucagon and/or Oral Administration of Glycerol on Blood Metabolites and Hormones of Holstein Dairy Cows Affected with Fatty Liver Disease

To study the effects of the subcutaneous injection of glucagon and/or oral administration of glycerol on blood metabolites and hormones of Holstein dairy cows induced with fatty liver disease, twenty multiparous cows were fed a dry cow ration supplemented with 12 kg of cracked corn during the dry period to increase the likelihood of fatty liver disease development. Cows with a body condition score (BCS) of ≥ 3.5 points (0-5 scale) were randomly assigned to one of four treatment groups--saline, glucagon, glucagon plus glycerol, and glycerol. Following treatment, serial blood samples were collected to determine the effect of glucagon and/or glycerol on blood composition. Glucagon injection alone increased postpartal plasma glucose, glucagon, and insulin and decreased plasma NEFA and TAG. Glucagon plus glycerol treatment increased and sustained postpartal plasma glucose and insulin and decreased postpartal plasma NEFA and TAG. Administration of glycerol alone increased plasma glucose and decreased plasma NEFA during the postpartal period. Early postpartal treatment of cows with glucagon and/or glycerol increased plasma glucose and decreased plasma NEFA. This response would suggest that these treatments would decrease the likelihood of fatty liver disease in dairy cows.</p

Caring for patients with rare diseases during the COVID-19 pandemic

Rare diseases frequently attack and weaken the immune system, increasing the patient’s vulnerability to develop severe conditions after viral infections, such as COVID-19. Many patients with rare diseases also suffer from mental retardation and disability. These rare disease phenotypes do not emerge in older people who are susceptible to COVID-19 infection, but present at a very young age or at birth. These factors must be taken in consideration when caring for this vulnerable patient population during a pandemic, such as COVID-19. Patients with a rare disease have to take their regular medication continuously to control their condition and frequently, the medications, directly or indirectly, affect their immune system. It is important for this patient population, if infected with COVID-19 or another severe form of infection, to adjust the treatment protocol by specialists, in consultation with their own medical team. Special awareness and educational programs, understandable for mentally retarded patients, must be developed to educate them about social distancing, curfew, sanitization, and sensitization to the disease and quarantine. The COVID-19 pandemic highlighted the importance to reconsider the care required by patients with a rare disease during a pandemic or disaster, a program that should be adopted by the World Health Organization and governmental institutions for consideration

Acute Effects of Postpartal Subcutaneous Injection of Glucagon and/or Oral Administration of Glycerol on Blood Metabolites and Hormones and Liver Lipids and Glycogen of Holstein Dairy Cows Induced with Fatty Liver Disease

The effects of subcutaneous injection of glucagon and/or oral administration of glycerol on blood metabolites and hormones of Holstein dairy cows induced with fatty liver disease was studied. Twenty multiparous cows were fed a dry cow ration supplemented with 6 kg of cracked corn during the dry period to increase the likelihood of fatty liver disease development. Cows with a body condition score of ≥ 3.5 points (1-5 scale) were assigned randomly to one of four treatment groups--saline, glucagon, glucagon plus glycerol, and glycerol. Following treatment, serial blood samples were collected to determine the effect of glucagon and/or glycerol on blood composition. Glucagon injection alone increased postpartal plasma glucose, insulin, glucagon, and plasma urea nitrogen and decreased plasma nonesterified fatty acids (NEFA). Glucagon plus glycerol treatment increased and sustained postpartal plasma glucose, insulin and decreased postpartal plasma NEFA. Administration of glycerol alone increased plasma triacylglycerol (TAG) and decreased plasma NEFA during the postpartal period. Early postpartal treatment of cows with glucagon and/or glycerol increased plasma glucose and decreased plasma NEFA. This response would suggest that these treatments with glucagon and/or glycerol would decrease the likelihood of fatty liver disease in dairy cows.</p