Microindentation Hardness of Protein Crystals under Controlled Relative Humidity

Vickers microindentation hardness of protein crystals was investigated on the (110) habit plane of tetragonal hen egg-white lysozyme crystals containing intracrystalline water at controlled relative humidity. The time evolution of the hardness of the crystals exposed to air with different humidities exhibits three stages such as the incubation, transition, and saturation stages. The hardness in the incubation stage keeps a constant value of 16 MPa, which is independent of the humidity. The incubation hardness can correspond to the intrinsic one in the wet condition. The increase of the hardness in the transition and saturation stages is well fitted with the single exponential curve, and is correlated with the reduction of water content in the crystal by the evaporation. The saturated maximum hardness also strongly depends on the water content equilibrated with the humidity. The slip traces corresponding to the (11 ̅0)[110] slip system around the indentation marks are observed in not only incubation but also saturation stages. It is suggested that the plastic deformation in protein crystals by the indentation can be attributed to dislocation multiplication and motion inducing the slip. The indentation hardness in protein crystals is discussed in light of dislocation mechanism with Peierls stress and intracrystalline water

Solution Structures of Cytosolic RNA Sensor MDA5 and LGP2 C-terminal Domains : Identification of the RNA Recognition Loop in RIG-I-LIKE Receptors

The RIG-I like receptor (RLR) comprises three homologues: RIG-I (retinoic acid-inducible gene I), MDA5(melanoma differentiation-associated gene 5), and LGP2 (laboratory of genetics and physiology 2). Each RLR senses different viral infections by recognizing replicating viral RNA in the cytoplasm. The RLR contains a conserved C-terminal domain (CTD), which is responsible for the binding specificity to the viral RNAs, including double-stranded RNA (dsRNA) and 5'-triphosphated single-stranded RNA (5'ppp-ssRNA). Here, the solution structures of the MDA5 and LGP2 CTD domains were solved by NMR and compared with those of RIG-I CTD. The CTD domains each have a similar fold and a similar basic surface but there is the distinct structural feature of a RNA binding loop; The LGP2 and RIG-I CTD domains have a large basic surface, one bank of which is formed by the RNA binding loop. MDA5 also has a large basic surface that is extensively flat due to open conformation of the RNA binding loop. The NMR chemical shift perturbation study showed that dsRNA and 5'ppp-ssRNA are bound to the basic surface of LGP2 CTD, whereas dsRNA is bound to the basic surface of MDA5 CTD but much more weakly, indicating that the conformation of the RNA binding loop is responsible for the sensitivity to dsRNA and 5'ppp-ssRNA. Mutation study of the basic surface and the RNA binding loop supports the conclusion from the structure studies. Thus, the CTD is responsible for the binding affinity to the viral RNAs

Acute exacerbation of chronic osteomyelitis triggered by aggravation of type 2 diabetes mellitus: a case report

Abstract Background Osteomyelitis is an infection in a bone. Acute osteomyelitis is observed mainly in the long leg bones of children and is usually treated with antibiotics. On the other hand, in adults, subacute or chronic osteomyelitis is more common. Antibiotics therapy is not necessarily effective for chronic osteomyelitis, and sometimes a surgical operation is performed for its remission. Furthermore, in classification of osteomyelitis by cause, type 2 diabetes mellitus is one of most common conditions associated with osteomyelitis. It isCase presentation well known that a variety of complications are induced in patients with type 2 diabetes mellitus due to chronic hyperglycemia, inflammatory reaction, and immunodeficiency, especially when glycemic control is poor. Case presentation A 58-year-old Japanese man had acute exacerbation of chronic osteomyelitis triggered by aggravation of type 2 diabetes mellitus. He had acute osteomyelitis in his right lower leg in his babyhood. After this episode, he did not experience any pain in his leg for approximately 50 years; he felt acute pain in his right lower leg at the age of 50 when his glycemic control was very poor. He then started undergoing medical therapy for type 2 diabetes mellitus and, after an improvement in glycemic control, his pain was gradually mitigated. However, he did not take medicine for approximately 8 months at the age of 58. After the interruption, glycemic control became very poor and he felt the similar acute pain again in the same area. After improving glycemic control, his pain was gradually mitigated again as observed at the age of 50. Conclusions Here we report a case of chronic osteomyelitis under poorly controlled diabetic conditions. Interestingly, chronic osteomyelitis was observed at the same position where acute osteomyelitis was observed in his babyhood. In addition, chronic osteomyelitis was repeatedly observed, and it seemed that its acute exacerbation was closely associated with aggravation of type 2 diabetes mellitus. We should bear in mind that type 2 diabetes mellitus is one of the major risk factors of osteomyelitis and that acute exacerbation of chronic osteomyelitis could be triggered by a disturbance of glycemic control in patients with type 2 diabetes mellitus

Drug fever and acute inflammation from hypercytokinemia triggered by dipeptidyl peptidase‐4 inhibitor vildagliptin

Abstract A 69‐year‐old man started taking the dipeptidyl peptidase‐4 inhibitor, vildagliptin. One week later, C‐reactive protein and plasma immunoglobulin E levels were markedly elevated, and the vildagliptin was stopped. After the patient's laboratory findings were normalized, we decided to restart vildagliptin with the patient's agreement. The next day, he had a high fever, and C‐reactive protein and procalcitonin levels were elevated. Although we failed to find a focus of infection, we started antibiotics therapy. Two days later, the high fever had improved, and the C‐reactive protein level had decreased. A drug lymphocyte stimulation test showed a positive result for vildagliptin. We examined various kinds of cytokine and infection markers just before and after the treatment with vildagliptin. Finally, we diagnosed the patient with vildagliptin‐induced drug fever, probably based on the increase of various inflammatory cytokine levels and the response to this. Taken together, we should be aware of the possibility of vildagliptin inducing drug fever and/or acute inflammation

Hypoinsulinemic hypoglycemia triggered by liver injury in elderly subjects with low body weight: case reports

Hypoglycemia is induced by many causes, especially over-dose of insulin or oral hypoglycemic agents in diabetic subjects. In such a case, hyperinsulinemic hypoglycemia is usually observed. On the other hand, it is important to classify secondary hypoglycemia and hypoinsulinemic hypoglycemia. Liver injury-induced hypoglycemia is one of the causes of hypoinsulinemic hypoglycemia but rarely observed in clinical practice. Herein, we experienced similar 2 cases of non-diabetic hypoinsulinemic hypoglycemia. Both of them were elderly subjects with low body weight. Furthermore, it is likely that hypoinsulinemic hypoglycemia in both subjects was triggered by severe liver injury, at least in part, due to possible limited liver glycogen store. In elderly subjects with low body weight and/or malnutrition, metabolism in the liver is reduced and glycogen accumulation is decreased. Such alteration brings out acute and marked liver injury, which finally leads to the onset of severe hypoglycemia. It is known that not only liver injury but also multiple organ failure could be induced due to extreme emaciation in subjects. It is likely that in elderly subjects with low body weight and/or malnutrition, multiple organ failure including liver failure could be induced due to the similar reason. Therefore, we should be very careful of such subjects in order to avoid the development of multiple organ failure which leads to life-threatening situations. In conclusion, we should keep in mind the possibility of hypoinsulinemic hypoglycemia when we examine severe liver injury, especially in elderly or starving subjects with low body weight and limited liver glycogen stores