MENS-associated increase of muscular protein content via modulation of caveolin-3 and TRIM72.

Microcurrent electrical neuromuscular stimulation (MENS) is known as an extracellular stimulus for the regeneration of injured skeletal muscle in sports medicine. However, the effects of MENS-associated increase in muscle protein content are not fully clarified. The purpose of this study was to investigate the effects of MENS on the muscular protein content, intracellular signals, and the expression level of caveolin-3 (Cav-3), tripartite motif-containing 72 (TRIM72) and MM isoenzyme of creatine kinase (CK-MM) in skeletal muscle using cell culture system. C2C12 myotubes on the 7th day of differentiation phase were treated with MENS (intensity: 10-20 microA, frequency: 0.3 Hz, pulse width: 250 ms, stimulation time: 15-120 min). MENS-associated increase in the protein content of myotubes was observed, compared to the untreated control level. MENS upregulated the expression of Cav-3, TRIM72, and CK-MM in myotubes. A transient increase in phosphorylation level of Akt was also observed. However, MENS had no effect on the phosphorylation level of p42/44 extracellular signal-regulated kinase-1/2 and 5'AMP-activated protein kinase. MENS may increase muscle protein content accompanied with a transient activation of Akt and the upregulation of Cav-3 and TRIM72.

Changes of SM muscles after STG harvest.

Semimembranosus (SM) muscle as well as Semitendinosus-Gracilis (STG) tendon have the same role in knee flexion and tibial internal rotation. Because STG tendons are generally used for anterior cruciate ligament (ACL) reconstruction, some compensational changes in SM muscle might have been induced. The purpose of this study was to investigate the changes of SM muscle affected by harvesting STG tendons. 10 Wistar-strain male rats were divided into control (C) and STG-dissected (STG) groups. Left STG tendons including the distal half of muscle portions were dissected in group STG and only skin incision was performed in group C. 4 weeks after the treatments, fiber types classification and ultrastructural observations were performed. In group STG the decrease of type IIa (fast-twitch fiber with high oxidative capacity) was observed in deep layers of SM muscle (p<0.01). In ultrastructural observations, the increase in lipid droplets and mitochondria and the irregularity of Z disc were observed in deep layers. These morphological changes indicated that the mechanical loading might increase in SM muscle after harvesting of STG. Because of minor injuries in SM muscle, hamstring strength exercise at early stage of rehabilitation program should be carefully performed following ACL reconstruction using STG tendons in clinical practice.

Role of patellar tendon on the population of muscle fiber types and the contractile properties of single glycerinated muscle fibers in quadriceps muscles of rats.

The role of the patellar tendon (PT) in the contractile properties of quadriceps muscle was investigated. After PT resection (partial or complete), PT reconstruction, or a sham operation, rats were forced to run on a rodent treadmill. The histochemical and mechanical characteristics of the vastus medialis (VM) and vastus lateralis (VL) muscles were examined 2, 4, and 8 weeks after treatment. There were no significant changes in either fiber type population or the contractile properties of glycerinated single muscle fibers from VM and VL 2 and 4 weeks after partial PT resection. Complete PT resection caused a decrease in the population of type I fibers in VM, while the running training after PT reconstruction increased the population of type I fibers in VM. For both the PT resection and PT reconstruction groups, the Hill coefficient, an indicator of the Ca2+ sensitivity of myofilaments, was calculated from the pCa-tension relationship of glycerinated single muscle fibers. In the PT reconstruction group, the Hill values for fibers isolated from VM were significantly decreased by running training, but the Hill values for VL were not. The effect of running training on the Ca2+ sensitivity of myofilaments in muscle fibers with PT reconstruction was different from that in muscle fibers without PT treatment. Both resection and partial resection of the PT in this animal model had heterogeneous effects on the contractile properties of quadriceps muscles; we presume that, clinically, we must give careful consideration to PT treatment.

[The effects of anterior cruciate ligament resection and subsequent running training on muscles around the knee joint in rat].

The purpose of this study was to evaluate the effects of running training on the muscles in rat after resection of the anterior cruciate ligament (ACL). The biochemical and histochemical changes were analyzed in the muscles around the knee joint from which the ACL was dissected, and the rats were subsequently forced to undergo endurance running. After ACL resection, the wet weights of all muscles around the knee joint decreased but an increase was found in the number of slow-twitch fibers, especially in the vastus lateralis and vastus medialis muscles. The activities of glycolytic and oxidative enzymes in all muscles tended to decrease following resection. Rats which had undergone ACL resection were put through training in the form of appropriate endurance running, causing significant increases in the wet weights of all muscles, except for the vastus medialis, and a decrease in the number of slow-twitch fibers in the vastus medialis. In addition, all the enzyme activities tended to decrease following training. Therefore, the influences of ACL resection and subsequent running training were clearly demonstrated in the vastus medialis muscle. These changes may have been caused by joint instability and sensory reflex dysfunction by deafferentation from the ACL mechanoreceptor (joint-ligament receptor). To maintain knee muscle function, stability of the joint and restoration of the skeletomotor system from the ACL and the muscles around the knee joint is necessary.

Vanished islets with pancreatitis in acute-onset insulin-dependent diabetes mellitus in an adult.

We report an autopsy case of acute-onset insulin-dependent diabetes mellitus, type I, that occurred in an adult. The patient died 3 days after the clinical onset of diabetes. Hyperglycemia, ketonuria, and hyperamylasemia were observed at admission. The pathologic examination of the pancreas showed a markedly decreased number of islets, and residual islets were small and shrunken. Diffuse inflammatory cell infiltrates, which were found in islets and also in acini, were mainly T lymphocytes. Shrunken islets were composed of insulin cells, glucagon cells, somatostatin cells, and pancreatic polypeptide cells. A decreased number of zymogen granules in acini were prominent [corrected]. This case suggested that pan-pancreatitis, destroying whole islets and acini, can initiate insulin-dependent diabetes mellitus.

Somatostatinoma syndrome accompanied by overproduction of pancreatic polypeptide.

A case of somatostatin and pancreatic polypeptide (PP) producing tumor of the pancreas is presented. A 65-year-old woman was admitted for the evaluation of the tumor in the right upper quadrant of the abdomen. Clinical abnormalities included diabetic glucose intolerance, pancreatic insufficiency and marked dilatation of gallbladder. Marked high concentration of plasma PP and low levels of plasma insulin and glucagon were observed before operation. Plasma insulin concentrations in response to oral glucose tolerance test and arginine infusion were markedly low. A large quantity of somatostatin (4,300 ng/g ww) as well as PP (1,340 ng/g ww) was detected in the tumor, and somatostatin cells and PP cells were determined by immunofluorescence studies. After operation, pancreatic insufficiency and glucose intolerance were improved, and the patient made a favorable progress.

Morphometrical quantitation of pancreatic endocrine cells in patients with carcinoma of the pancreas.

A morphometrical study of the tumor-free pancreatic regions has been performed in 18 patients with carcinoma of the pancreas, who were divided into three groups, i.e., diabetics, patients exhibiting impaired glucose tolerance (IGT) and normoglycemics. Tissues were stained for A, B, D and PP cells by immunocytochemistry and, for comparative purposes, the results were expressed as the number of cells/mm2. The diabetic and the IGT groups presented reduced A and B cell populations, with B cell counting lower in diabetics than in the IGT group. In addition, an inverse correlation was found between the number of B cells and the fasting plasma glucose (FPG) values, which suggests that the destruction of B cells may be the primordial cause of the glucose abnormality found in those patients. Possibly, a destructive process and fibrosis, similar to those occurring in chronic pancreatitis, are implicated in the reduction of such endocrine cells.

Immunologic aspects of the nonobese diabetic (NOD) mouse. Abnormalities of cellular immunity.

Experiments were performed on 12-wk-old nonobese diabetic (NOD) mice to investigate the immunologic background of the condition, using ICR mice as controls. The results indicate the following: (1) absolute decreases in number of T lymphocytes, (2) depression of natural killer activity, (3) normal responsiveness in delayed type hypersensitivity and functional depression of killer T cells against allogeneic tumors, (4) diminished resistance to herpes virus infection, and (5) enhanced production of polyclonal antibodies to T cell-dependent antigens. These features are similar to those noted in other autoimmune diseases of man and in their experimental models in laboratory animals. Elucidation of the pathogenetic mechanism of autoimmune diabetes mellitus in NOD mice, therefore, may contribute to the diagnosis, treatment, and prevention of a wide variety of autoimmune diseases.

Remission of insulin resistant diabetes in two patients with anti-insulin receptor antibodies.

Since Kahn et al. reported in 1976 insulin resistant diabetes due to anti-insulin receptor antibodies, an unusual form of diabetes mellitus (type B) has been found in many countries. We had two diabetic patients with anti-insulin receptor antibodies, associated with either acanthosis nigricans or systemic lupus erythematosus. Remission occurred 15 months after the onset of insulin resistant diabetes. One patient unfortunately died of acute pneumonia and the other has been followed up. The anti-insulin receptor antibodies were measured according to the method of Omori and Hirata by using the pellet of human placental membrane. The anti-insulin receptor antibodies in both cases diminished as remission occurred. Reverse hemolytic plaque assay (PFG) detected immunoglobulin-producing cells. In Case 2, the plaque forming cells were twenty times as many as the normal value. Immunosuppressive therapy with cyclophosphamide reduced the immunoglobulin secreting cells as remission occurred. The patients with insulin resistance (type B) should be treated with enough insulin inspite of the presence of insulin resistance. Besides, cyclophosphamide, 6-mercaptopurine and prednisolone should be used with caution. Plasma exchange is a treatment to be tried. It is important to note that spontaneous remission may occur more than half a year after the onset of insulin resistant diabetes.

Insulinopenic diabetes after rodenticide (Vacor) ingestion: a unique model of acquired diabetes in man.

A clinical syndrome, characterized by acute diabetic ketoacidosis associated with a toxic neuropathy, developed in five men who intentionally ingested a recently introduced rodenticide (Vacor) containing N-3-pyridylmethyl-N'-p-nitrophenyl urea (RH-787). A 7-yr-old boy, who accidentally ingested this poison, died within 14 h. Marked insulinopenia, without a reduction in glucagon levels, suggested a specific beta-cytotoxic effect, which was supported after autopsy in three cases by histopathologic evidence of extensive beta cell destruction. Lethal effects in rats prevented investigation of RH-787's diabetogenicity in vivo; however, studies in isolated rat islets confirmed a direct inhibitory effect, which was prevented by concomitant incubation with nicotinamide, suggesting a mechanism of action similar to that of streptozotocin. We detected islet cell-surface antibodies in two of four patients studied. These findings indicate that this nongenetic, acquired form of insulinopenic diabetes, which has persisted in the surviving patients for up to 3 yr, presents a unique opportunity to test in man the concept that hyperglycemia and the accompanying metabolic consequences of insulinopenia can induced diabetic microangiopathy in the absence of genetic predisposition.