Effects of muscle blood flow on muscle energy metabolism and contractility

Energy metabolism and contractility of rat’s femoral triceps muscles were investigated by varying blood flow levels with ligation of the femoral artery. The triceps were stimulated electrically to produce equivalent conditions as exercise loading, and phosphorus nuclear magnetic resonance (³¹P-NMR) spectra and muscle tension levels were monitored. The ratio of inorganic phosphate (Pi) to ‘Pi+phosphocreatine (PCr)’, i.e. Pi/(Pi+PCr), was obtained from ³¹P-NMR spectra. This ratio was related to the reduction of blood flow ratio (BFR) during and after the stimulation period, whereas before starting the stimulation, there was no significant correlation. These findings indicate: (i) muscle energy metabolism during decreased blood flow is influenced by the stimulation (loading) given to the muscle; and (ii) changes of muscle energy metabolism due to decreased muscle blood flow during the loading is evaluable by measuring ³¹P-NMR spectra. Muscle tension reached the plateau 8 min after starting the stimulation, regardless of BFR, but muscle tension ratio decreased as BFR became lower. This indicates that decreased blood flow diminishes muscle contractility, and then lowers muscle function levels. Our findings indicate that muscle blood flow plays an important role in muscle function, and blood flow and muscle function levels are evaluable by measuring ³¹P-NMR spectra of the muscle.     

Nonlinearity identified by neural network models inP CO 2 control system in humans

The nonlinearity included in the P_{CO 2} control system in humans is evaluated using the degree of nonlinearity based on a difference of residuals. An autoregressive moving average (ARMA) model and neural networks (linear and nonlinear) are employed to model the system, and three types of network (Jordan, Elman and fully interconnected) are compared. As the Jordan-type linear network cannot approximate respiratory data accurately, the other two types and the ARMA model are used for the evaluation of the nonlinearity. The results of the evaluation indicate that the linear assumption for the P_{CO 2} control system is invalid for three subjects out of seven. In particular, strong nonlinearity was observed for two subjects.     

Alteration of regional cerebral blood flow to thyrotropin-releasing hormone therapy in acute encephalitis and encephalopathy during childhood.

BACKGROUND: Thyrotropin-releasing hormone (TRH) is now used as a therapeutic agent for various neurological disorders. Animal study has shown that TRH was attributable to increased cerebral blood flow (CBF). AIMS: There have been occasional reports that TRH therapy was effective for improving symptoms of persistent disturbance of consciousness after acute encephalitis or encephalopathy during childhood. To determine whether TRH has an effect on increasing CBF to patients who have consciousness disturbance caused by acute encephalitis or encephalopathy, and to determine the optimal method of administration. METHODS: Sixteen patients aged 0.7-10.9 years (mean age, 3.2+/-3.1 years) who presented with persistent disturbance of consciousness resulting from acute encephalitis or encephalopathy and were treated with TRH. Regional CBF (rCBF) was measured by single photon emission computed tomography before and after TRH therapy. The alteration rates of rCBF were compared between the divided two groups concerning the dose levels, dosing periods, and treatment lags. RESULTS: The alteration rates of rCBF of the high dose group were higher than those of the low dose group. Differences in the dosing periods and treatment lags did not cause any significant difference of the alteration rates of rCBF. CONCLUSION: The study showed that higher alteration rates of the CBF were observed in the higher dosing group, and TRH have the potency of increasing CBF. TRH therapy would have the potential for effective treatment of persistent consciousness disturbance caused by childhood acute encephalitis or encephalopathy.     

Vasoactive intestinal peptide in the anterior pituitary is increased in hypothyroidism

Vasoactive intestinal peptide (VIP) and PRL have been reported to be colocalized in rat lactotropes. To determine whether induced hypothyroidism, known to reduce pituitary PRL concentration, also reduces pituitary concentration of VIP, rats were treated with antithyroid drugs for 3 weeks. Pituitary PRL concentration in male rats (micrograms/mg protein) was markedly reduced by this treatment (9.4 +/- 1.0 vs. 2.3 +/- 0.4 when extracted at pH 1.1, 17.9 +/- 3.0 vs. 3.4 + 0.4 when extracted at pH 7.4, 21.8 +/- 3.3 vs. 6.7 + 1.3 when extracted at pH 10.0). Contrary to expectation, pituitary VIP concentration was markedly increased in hypothyroidism; in males from 169.5 +/- 20.3 to 834.0 +/- 82.2 pg/mg protein, and in females (whose pituitary PRL had been similarly reduced) from 103.1/I +/- 34.1 to 771.6 +/- 100.9 pg/mg protein. Serum PRL was significantly reduced in hypothyroid males (7.4 +/- 1.6 vs. 28.9 +/- 12.2 ng/ml) whereas in females, serum PRL was not significantly altered (41.4 +/- 11.6 vs. 38.8 +/- 14.3 ng/ml). The effect of hypothyroidism was reversed by administration of T4 in physiological doses. The authenticity of pituitary immunoreactive VIP was further established by demonstrating chromatographic patterns by Sephadex G-50 gel exclusion and reverse phase HPLC separations identical to synthetic VIP. Immunohistochemically reactive VIP cells could not be demonstrated in normal pituitaries, but the marked increase in VIP in hypothyroid animals made it possible to visualize a population of VIP immunoreactive stellate cells which appear to be distinct from hypothyroid lactotropes and thyrotropes.     

Human pancreatic growth hormone-releasing factor stimulates release of growth hormone in conscious unrestrained male rabbits

The effect on GH secretion of GH-releasing factor (GRF), a 44-amino acid peptide recently isolated from a human pancreatic tumor (hpGRF), was examined in conscious male rabbits. During a 6-h period (1030-1630 h) of the control study individual rabbits exhibited pulsatile GH release with a surge at 1030-1200 h, a trough at 1200-1400 h, and a second peak at 1400-1630 h. Intravenous bolus injections of 1 and 10 micrograms hpGRF caused significant and dose-related increases in plasma GH during both the period of the trough (1300 h) and the surge (1530 h), although the GH responses were obviously higher during the latter than the former period. Passive immunization with anti-somatostatin (SRIF) sheep serum resulted in a prompt increase in plasma GH immediately after an injection of the antiserum. When 0.1, 1, and 10 micrograms hpGRF were successively injected iv at 1215, 1345, and 1515 h, respectively, maximum levels of plasma GH after hpGRF in anti-SRIF sheep serum-treated rabbits were significantly higher than in animals given normal sheep serum. The plasma GH responses to 10 micrograms hpGRF, given iv only once at 1515 h in normal sheep serum-treated animals, were not different from those to 10 micrograms hpGRF injected at 1515 h after the prior administration either of the smaller hpGRF dose (0.1 micrograms, 1215 h; 1 microgram, 1345 h), nor of the large dose (10 micrograms, 1100 h). These findings suggest the following: 1) that the secretion of GH is pulsatile in conscious, unrestrained male rabbits; 2) that hpGRF is a potent secretagogue for GH release in rabbits as well as other species; 3) that the magnitude of plasma GH response to hpGRF is different according to timing of the injection during the course of pulsatile GH secretion but is not influenced by the prior administration of hpGRF (no priming effect); and 4) that the responsiveness of plasma GH to hpGRF is affected by circulating endogenous SRIF.     

Involvement of Rho-kinase in prostaglandin F2alpha-stimulated interleukin-6 synthesis via p38 mitogen-activated protein kinase in osteoblasts

We have previously reported that prostaglandin F(2alpha) (PGF(2alpha)) stimulates interleukin-6 (IL-6), a potent bone resorptive agent, through p44/p42 mitogen-activated protein (MAP) kinase in osteoblast-like MC3T3-E1 cells. In the present study, we investigated whether Rho-kinase is implicated in the PGF(2alpha)-stimulated IL-6 synthesis in MC3T3-E1 cells. PGF(2alpha) time-dependently induced the phosphorylation of myosin phosphatase targeting subunit (MYPT-1), a Rho-kinase substrate. Y27632, a specific Rho-kinase inhibitor, significantly reduced the PGF(2alpha)-stimulated IL-6 synthesis as well as the MYPT-1 phosphorylation. Fasudil, another inhibitor of Rho-kinase, suppressed the PGF(2alpha)-stimulated IL-6 synthesis. Y27632 and fasudil failed to affect the PGF(2alpha)-induced phosphorylation of p44/p42 MAP kinase. SB203580 and BIRB0796, potent inhibitors of p38 MAP kinase, suppressed the IL-6 synthesis induced by PGF(2alpha). While SP600125, an inhibitor of stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK), failed to reduce the synthesis. Y27632 as well as fasudil attenuated the PGF(2alpha)-induced phosphorylation of p38 MAP kinase. These results strongly suggest that Rho-kinase regulates PGF(2alpha)-stimulated IL-6 synthesis via p38 MAP kinase activation in osteoblasts.     

Magnetic resonance imaging in a case of mumps postinfectious encephalitis with asymptomatic optic neuritis

A 5-year-old male patient with asymptomatic optic neuritis and mumps postinfectious encephalitis or acute disseminated encephalomyelitis is reported. Magnetic resonance imaging (MRI) with a short inversion time inversion recovery sequence was valuable in detecting clinically silent lesions of the unilateral right optic nerve in addition to visual evoked potentials. Evidence of concurrent optic neuritis was useful for detecting more extensive neurological involvement, leading to the diagnosis of mumps postinfectious encephalitis. A systmatic MRI study should be performed in children with mumps encephalitis, regardless of appreciable clinical deficits.     

Attainment of normal height in severe juvenile hypothyroidism.

Prolonged juvenile hypothyroidism results in a permanent loss in height that is related to the duration of thyroxine deficiency before adequate thyroxine replacement treatment. A 13 year old girl with severe juvenile hypothyroidism was studied prospectively. She had an undetectable serum thyroxine concentration, a height SD score of -6.6 SD, and a bone age of 5.8 years. The enlarged pituitary gland involuted with thyroxine treatment to produce an empty sella. In addition to thyroxine the girl was treated with a gonadotrophin releasing hormone agonist to avoid the progression of puberty for 18 months and with growth hormone to achieve normal adult height.     

Choice and administration sequence of antiepileptic agents for status epilepticus and frequent seizures in children

We investigated the sequence of the administration, the efficacy and the safety of antiepileptic drugs (AED) given intravenously for the treatment of status epilepticus and frequent seizures in children. Our institute has a recommended sequence of AED administration for treatment of status epilepticus: the first-line agent is diazepam (0.3 - 0.5 mg/kg administered intravenously, once or twice). The second-line drugs include midazolam (0.15 - 0.4 mg/kg intravenously, once or twice, and if necessary, followed by continuous infusion at 0.06 - 0.18 mg/kg/hour), lidocaine (1 - 2 mg/kg intravenously, once or twice, and if necessary, followed by continuous infusion at 2 - 4 mg/kg/hour) and phenytoin (10 - 20 mg/kg, infused slowly). For those patients who previously experienced a seizure which was refractory to diazepam but responsive to the second-line agent, it was recommended to use the second-line agent as a first-line agent. When seizures were refractory to the first and second-line agents, thiopental was administered (3 - 10 mg/kg intravenously, and if necessary, followed by continuous infusion at 2 -5 mg/kg/hour). The etiologies of 177 occasions of status epilepticus and frequent seizures were categorized into two groups:epilepsy (n = 95) and situation-related seizures (n = 82). Situation-related seizures included febrile seizures (n = 44), acute encephalopathy/encephalitis (n = 31) and benign infantile convulsions (n = 7). The ages of the patients ranged from 0.1 to 18.4 years (average +/- SD:3.69 +/- 3.15 years). Diazepam was administered as the first-line drug on 157 of 177 occasions (88.7%). On 116 occasions the second-line agents were administered. Midazolam and lidocaine were injected as the second-line agent on 54 (46.6%), and on 33 (28.4%) occasions, respectively, although both midazolam and lidocaine injections were off-label use for seizure control in Japan. Thiopental was used as the third to fifth-line agent. Effective ratios (effective occasions/total occasions) of each drug were the following: thiopental 19/21 (90.4%), midazolam 57/99 (57.6%), lidocaine 25/60 (41.7%), phenytoin 16/41 (39.0%), diazepam 59/164 (36.0%). Thiopental was statistically more effective than midazolam, lidocaine, diazepam or phenytoin (p < 0.01), and midazolam was statistically more effective than diazepam (p < 0.01) or phenytoin (p < 0.05). Administration of thiopental caused complications more frequently than the other agents (p < 0.01): The complications by thiopental were severe in some cases requiring intratracheal intubations and artificial ventilation. From the viewpoint of both efficacy and safety, midazolam should be recommended as one of the first-line agents for status epilepticus.     

Application of a Live Varicella Vaccine to the Immunosuppressive Children and the Incibence of a Case of Herpes Zoster after Vaccination

A live varicella vaccine was applied to 13 susceptible children to varicella virus. Three were receiving steroid therapy, and one of them was treated with both steroid and anticancer drugs. Immunosuppressive therapy and anticancer medication were not suspended before and after vaccination. Serological responses were observed in 11 of 13 vaccinated children by fluorescent antibody to membrane antigen (FAMA) test 6 to 7 weeks after Vaccination. Mild rash appeared as only a clinical reaction in 3 of the vaccinated children. However, 3 and a half months later, a vaccinee with acute myeloblastic leukemia, developed herpes zoster. Our observation suggested a possibility of contracting zoster in immune compromised hosts after vaccination with a live varicella vaccine.