Alterations of load-induced p38 MAP kinase activation in failing rat hearts.

Hemodynamic load-induced cardiac p38 mitogen-activated protein kinase (MAPK) activation was studied in normotensive control Dahl rats (n = 10) and hypertensive Dahl rats with heart failure (n = 16). The isolated heart from each animal was stretched on a Langendorff apparatus at an equivalent diastolic wall stress, and the p38-MAPK activity of the left ventricular (LV) myocardium was analyzed by immunoprecipitation-kinase assay. Compared to the control hearts, the stretch-induced p38-MAPK activities were significantly decreased, and inversely correlated with the LV diameter (r = -0.73, P < 0.01). Chronic treatment with an angiotensin II AT1-receptor antagonist, valsartan (10 mg/kg/day), ameliorated cardiac function and remodeling process in the failing hearts, which was associated with an improvement of the p38-MAPK activities. Thus, the mechano-signal transduction of p38-MAPK pathway is downregulated in the failing hearts, along with progressive ventricular remodeling. The data also suggest that the beneficial effects of the AT1-receptor antagonists are potentially mediated by the restoration of cardiac growth-related signal transduction.

Stage-specific differential activation of mitogen-activated protein kinases in hypertrophied and failing rat hearts.

Mitogen-activated protein kinases (MAPKs) are involved in the early development of cardiac hypertrophy, but their roles in chronic left ventricular hypertrophy (LVH) are unclear. We studied the angiotensin (Ang) II-induced cardiac MAPK activation of the hypertensive Dahl salt-sensitive (DS) rats in the subacute developing LVH stage, the chronic compensated LVH stage, and the congestive heart failure (CHF) stage. In the isolated, coronary-perfused heart preparation, Ang II infusion (1x10(-6)mol/l) activated extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK) and p38-MAPK in the LV myocardium. No substantial differences were observed in the Ang II-induced ERK activation between the normotensive control DS rats and the hypertensive DS rats in either stage. In contrast, the Ang II-induced activation of JNK and p38-MAPK was augmented in the subacute LVH stage of the hypertensive DS rats, but then progressively attenuated in the chronic LVH and CHF stages. Chronic treatment with an angiotensin converting enzyme inhibitor, temocapril (20 mg/kg/day), ameliorated the responsiveness of the JNK/p38-MAPK activation, suggesting that the decreased JNK/p38-MAPK activation is a consequence of negative feedback regulation for the activated cardiac renin-angiotensin system in chronic LVH and CHF. Thus, the Ang II-induced activation of multiple cardiac MAPK pathways are differentially regulated, depending on the stages of chronic hypertrophic process. The JNK and p38-MAPK activation may be involved in the early development of adaptive LVH. However, the responsiveness of the cardiac JNK/p38-MAPK pathways progressively decreased in chronic LVH and CHF under the chronic activation of tissue renin-angiotensin system.

Cardiac calcineurin during transition from hypertrophy to heart failure in rats.

We studied an alteration of calcineurin expression in the heart and its modification by cyclosporin A and an ACE inhibitor, temocapril, using Dahl salt-sensitive (DS) rats with hypertensive left ventricular hypertrophy (LVH) and congestive heart failure (CHF). Calcineurin protein expression in the LV myocardium was increased in the LVH stage, but then decreased during CHF transition. Chronic cyclosporin A treatment (10 mg/kg/day), which inhibits calcineurin activity, could not block the increases of LV weight and dimensions and did not improve the LV systolic function during the CHF transition. In contrast, chronic temocapril treatment (20 mg/kg/day) restored the downregulation of calcineurin expression, but progression of the hypertrophic process was inhibited. Therefore, cardiac calcineurin is increased in the hypertensive LVH and may be involved in the development of the adaptive hypertrophic process. However, calcineurin expression is downregulated during CHF transition and may no longer play a major role in the pathogenesis of myocardial hypertrophy in the failing hearts.

Electrophysiological brainstem dysfunction in a child with Leigh disease.

We evaluated brainstem dysfunction in a girl with Leigh disease. Neuroradiological and neurophysiological tests included brain magnetic resonance imaging, [123I]IMP single-photon emission computed tomography (SPECT), auditory brainstem responses (ABRs), short-latency somatosensory evoked potentials (SSEPs), electrically elicited blink reflexes (BRs) and all night polysomnography (PSG). The basal ganglia and midbrain contained areas of low accumulation on [123I]IMP SPECT images. Serial analysis of ABRs and SSEPs showed progressive disturbances of the brainstem wave components. The R2 components of the BRs were impaired. All night PSG revealed disturbances in both the tonic and phasic components of REM sleep. These findings suggested the multimodality tests in combination with neuroradiologic examinations are useful for assessing brainstem dysfunction in patients with Leigh disease.

Vomiting attack with ACTH and ADH discharge improves startle epilepsy.

A 15-year-old boy with sequelae of perinatal asphyxia experienced intractable startle-induced epileptic seizures, which were transiently suppressed with episodic vomiting. His vomiting was associated with adrenocorticotropin and antidiuretic hormone discharge, and the alteration of urinary catecholamine excretion, which might modulate epileptic seizures. Because startle-induced epileptic seizures are resistant to conventional antiepileptic therapy, this case is informative for the treatment of startle epilepsy.

An unusual form of vitamin D-dependent rickets in a child: alopecia and marked end-organ hyposensitivity to biologically active vitamin D.

A 12-yr-old female patient with an unusual form of vitamin D dependency and alopecia is described. She was a product of consanguineous mating and developed signs and symptoms suggesting vitamin D dependency early in life. Neither 150 microgram/day (6 microgram/kg.day) 1 alpha-hydroxyvitamin D3 nor 5 microgram/day (0.2 microgram/kg.day) 1,25-dihydroxyvitamin D3 proved to have an effect on her abnormal serum chemistry. Seven million international units per day (about 2 x 10(5) IU/kg.day) of native vitamin D restored her serum chemistry to normal and brought about marked improvement on skeletal radiographs, when her serum 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, and 24,25-di-hydroxyvitamin D were 4250, 4.8, and 35 ng/ml, respectively. Even with the high serum levels of vitamin D metabolites, her intestinal 47Ca absorption rate remained in the lower normal range and urinary calcium excretion was decidedly low. Association of hypoparathyroidism was ruled out. These results suggest that the patient has extreme and-organ (intestine) hyposensitivity, probably of congenital origin, to the biologically active metabolites of vitamin D.