Probing spatiotemporal PKA activity at the ryanodine receptor and SERCA2a nanodomains in cardomyocytes.

Spatiotemporal regulation of subcellular protein kinase A (PKA) activity for precise substrate phosphorylation is essential for cellular responses to hormonal stimulation. Ryanodine receptor 2 (RyR2) and (sarco)endoplasmic reticulum calcium ATPase 2a (SERCA2a) represent two critical targets of ß adrenoceptor (ßAR) signaling on the sarcoplasmic reticulum membrane for cardiac excitation and contraction coupling. Using novel biosensors, we show that cardiac ß1AR signals to both RyR2 and SERCA2a nanodomains in cardiomyocytes from mice, rats, and rabbits, whereas the ß2AR signaling is restricted from these nanodomains. Phosphodiesterase 4 (PDE4) and PDE3 control the baseline PKA activity and prevent ß2AR signaling from reaching the RyR2 and SERCA2a nanodomains. Moreover, blocking inhibitory G protein allows ß2AR signaling to the RyR2 but not the SERCA2a nanodomains. This study provides evidence for the differential roles of inhibitory G protein and PDEs in controlling the adrenergic subtype signaling at the RyR2 and SERCA2a nanodomains in cardiomyocytes. Video abstract.

Monoamine oxidase A and organic cation transporter 3 coordinate intracellular ß1AR signaling to calibrate cardiac contractile function.

We have recently identified a pool of intracellular ß1 adrenergic receptors (ß1ARs) at the sarcoplasmic reticulum (SR) crucial for cardiac function. Here, we aim to characterize the integrative control of intracellular catecholamine for subcellular ß1AR signaling and cardiac function. Using anchored Förster resonance energy transfer (FRET) biosensors and transgenic mice, we determined the regulation of compartmentalized ß1AR-PKA signaling at the SR and plasma membrane (PM) microdomains by organic cation transporter 3 (OCT3) and monoamine oxidase A (MAO-A), two critical modulators of catecholamine uptake and homeostasis. Additionally, we examined local PKA substrate phosphorylation and excitation-contraction coupling in cardiomyocyte. Cardiac-specific deletion of MAO-A (MAO-A-CKO) elevates catecholamines and cAMP levels in the myocardium, baseline cardiac function, and adrenergic responses. Both MAO-A deletion and inhibitor (MAOi) selectively enhance the local ß1AR-PKA activity at the SR but not PM, and augment phosphorylation of phospholamban, Ca2+ cycling, and myocyte contractile response. Overexpression of MAO-A suppresses the SR-ß1AR-PKA activity and PKA phosphorylation. However, deletion or inhibition of OCT3 by corticosterone prevents the effects induced by MAOi and MAO-A deletion in cardiomyocytes. Deletion or inhibition of OCT3 also negates the effects of MAOi and MAO-A deficiency in cardiac function and adrenergic responses in vivo. Our data show that MAO-A and OCT3 act in concert to fine-tune the intracellular SR-ß1AR-PKA signaling and cardiac fight-or-flight response. We reveal a drug contraindication between anti-inflammatory corticosterone and anti-depressant MAOi in modulating adrenergic regulation in the heart, providing novel perspectives of these drugs with cardiac implications.

Endoscopic third ventriculostomy for hydrocephalus in children younger than 1 year of age.

OBJECTIVE: The purpose of this study is to assess the role of endoscopic third ventriculostomy (ETV) in the treatment of hydrocephalus in children under 1 year of age. The authors analyzed data of ETV in their institution. METHODS: Between January 1995 and December 2008, 52 ETV procedures were performed for the treatment of hydrocephalus in 49 infants (32 male and 17 female). Their age ranged from 6 days to just under 12 months (mean age 6.2 months). The cause of hydrocephalus was occlusive in 43 patients (aqueduct stenosis in 31, Chiari II malformation in eight, Dandy-Walker cyst in two, quadrigeminal lipoma in one, and cerebellopontine angle arachnoid cyst in one patient). Communicating hydrocephalus was caused by intraventricular hemorrhage, meningitis, and/or ventriculitis in six patients. RESULTS: The overall success rate was 69.4% with mean follow-up period of 68.2 months. Patients with aqueduct stenosis had a higher success rate of ETV which was 77.4%. Seven infants were born preterm, six of them required a permanent ventriculoperitoneal shunts (VPS; P = 0.003). Malfunctioned VPS was removed in two patients following ETV. There was one death from intracranial hemorrhage, two cerebrospinal fluid leaks, and one meningitis. CONCLUSION: Endoscopic third ventriculostomy can be considered a possible treatment procedure alternative to VPS for the treatment of occlusive hydrocephalus in infants. ETV was effective in full-term infants while the results in low birth weight, preterm infants were poor. Success of ETV is not only age dependent but also etiology dependent. Infants with occlusive hydrocephalus treated with VPS, who present with shunt failure, could be treated by ETV and removal of the shunt device.

Chyluria associated with renal vasculitis.

Chyluria is usually associated with abnormal retrograde or collateral flow of lymph from intestinal lymphatics into lymphatics of the kidney, ureter or bladder. Chyluria has been described in patients with lymphoma, carcinoma, trauma, abscess, tuberculosis, filariasis, pregnancy and stenoses of the thoracic duct. In this case report we describe a patient who presented with chyluria associated with severe hyperlipidemia due to nephrotic syndrome induced by microscopic polyangiitis. Laboratory, histological and radiological examination did not show evidence of filarial infestation, tuberculous infection or malformation of the lymphatic system. Treatment with corticosteroids and cyclophosphamide resulted in improvement of hyperlipidemia and disappearance of chyluria.

Instrumented forceps for measurement of nerve compression forces.

Compression (or crushing) is used to induce nerve injury in test rats to study nerve degeneration and regeneration. The compression forces could be applied using a variety of techniques developed by several investigators. The lack of precise control of the applied compression may be the source of significant variations among observations. In this study, a Mosquito and dressing forceps were used. The Mosquito forceps was calibrated to determine the tip load corresponding to the clamping position. The dressing forceps was modified, instrumented with strain gauges and calibrated to directly measure the force applied at its tip. These two forceps were used to induce known and controlled nerve compression in 75 male Wistar rats (280-300g). The applied forces were of the order of 40N and 20N, for the Mosquito and dressing forceps, respectively.

Progressive interstitial fibrosis and nephrotic syndrome associated with antituberculous therapy.

We describe a patient who developed renal failure during antituberculous therapy. The condition was characterized by an initial phase of acute tubular necrosis and nephrotic syndrome which ultimately progressed to end-stage renal disease with severe interstitial fibrosis, despite adequate period of drug withdrawal. At that time, tuberculous infection was inactive and there was no evidence of amyloidosis or renal vein thrombosis.

Identification of sensory neurons supplying receptors in lingual muscles of the rat: histochemical and retrograde labeling study with horseradish peroxidase.

Sensory innervation of lingual musculature was studied in young adult Wistar rats using retrograde labeling by horseradish peroxidase (HRP) and combined silver impregnation and acetylcholinesterase (AchE) methods. Intra-lingual injection of HRP resulted in labeling of neuronal somata in the trigeminal, superior vagal, and second cervical spinal (C2) ganglia. When HRP was directly applied to the proximal stump of severed hypoglossal nerve, labeling occurred only in the cervical and superior vagal ganglia. Morphometric analysis revealed that the labeled neurons were of the small-sized category in all ganglia. However, in the trigeminal and C2 ganglia, labeling occurred also among the medium-sized neurons. Combined silver and AchE preparations from lingual muscles revealed the absence of typical muscle spindles. Instead, there were free and spiral nerve terminals in the interstitium, and epilemmal knob-like or bouton-like endings surrounding non-encapsulated muscle fibers. These terminals showed AchE -ve reaction in contrast to the motor ones. Few ganglionic cells were scattered along the hypoglossal nerve with uniform AchE +ve reaction in their perikarya. This indicates that medium-sized neurons in the trigeminal and C2 ganglia, and probably sensory neurons along the hypoglossal nerve mediate lingual muscle sensibility perceived by atypical sensory terminals.

Fiber contribution from the mesencephalic nucleus of the trigeminal nerve to the trochlear nerve in the cat: a histological quantitative study.

The fiber connections between the trigeminal mesencephalic nucleus and tract and the trochlear nerve root of 15 cats were examined after silver impregnation of the pontomescencephalic region of the brains. The results revealed that: (a) some of the mesencephalic root fascicles join the trochlear root, (b) some of the mesencephalic root cells contribute their processes to the trochlear root, and (c) some mesencephalic cells are found amidst the fibers of the trochlear nerve during its intrabulbar course. The fibers of the trochlear nerve were counted at certain preselected sites before and after crossing the mesencephalic nucleus. The statistical data obtained indicated that the trigeminal mesencephalic root contributes 4-10% of the fibers of the trochlear nerve, before it crosses the mesencephalic nucleus.

A fascial canal for the great saphenous vein: gross and microanatomical observations.

The course of the great saphenous vein in a fascial canal derived from the deep fascia of the lower extremity is described. The fascial canal is absent in 15% of the cases. In 85% of the cases, the sheath surrounding the great saphenous vein is continuous from the thigh to the leg and supports the vein from the hydrostatic pressure of the blood, being absent only in the uppermost and the lowermost quarters of the vein in the thigh and the leg, respectively. Thus, up to one quarter of the vein is ensheathed in 30%, up to one half in 45% and up to three quarters in 10% of the cases studied. The absence of this fascial envelope of the vein, in whole or in part, may be involved in the pathogenesis or the complications of the varicosities of the great saphenous vein along with the well-known aggravating factors.

Effect of nonionizing radiation on the Purkinje cells of the uvula in squirrel monkey cerebellum.

Pregnant squirrel monkeys were exposed to 2450-MHz (CW) microwaves at an equivalent power density of 10 mW/cm2 (SAR 3.4 mW/g) for three hours daily in a cavity-cage module. The exposure began when pregnancy was determined by a hormonal method, and continued through of offspring's first 9.5 months. After irradiation, the brain of the offspring were fixed with formaldehyde, and the inferior vermis of each cerebella was removed and processed for histologic observations. Purkinje cell density in the uvula was determined in sagittal serial section. There was no significant difference between control and experimental animals in the number of Purkinje cells per mm of Purkinje cell line (linear density), as well as in the density of Purkinje cells in the Purkinje cell layer.

Effect of nonionizing radiation on the Purkinje cells of the rat cerebellum.

In one experiment, Sprague Dawley rats (16-21 days of gestation) and their offspring were exposed to 100-MHz (CW) electromagnetic radiation at 46 mW/cm2 (SAR 2.77 mW/g) for 4 h/day for 97 days. In another experiment, the pregnant rats were irradiated daily from 17 to 21 days of gestation with 2450-MHz (CW) microwaves at 10 mW/cm2 (SAR 2 m W/G) for 21 h/day. In a third experiment, 6-day old rat pups were irradiated 7 h/day for five days with 2450-MHz radiation at 10 mW/cm2. Equal numbers of animals were sham irradiated in each group. Quantitative studies of Purkinje cells showed a significant and irreversible decrease in rats irradiated during fetal or fetal and early postnatal life. In animals exposed postnatally, and euthanized immediately after irradiation, significant decrease in the relative number of Purkinje cells was apparent. However, restoration apparently occurred after forty days of recovery.

Some quantitative histological observations on the growing cerebellum of the albino rat. (Dimensions of the cortical layers and white core and relative number of Purkinje cells).

The cerebella of 38 Sprague Dawley rats of various ages have been studied histologically by sectioning in certain parasagittal planes. The age groups were chosen from the early postnatal developmental stage (6, 11 and 16 days), around puberty (41, 46 and 51 days) and maturity (210 days). The sections yielded quantitative data with regard to the dimensions in parasagittal sections, of the entire cerebellum, the cerebellar cortex, the white core, the molecular layer and the granular layer, as well as, the differential and proportional growth of these layers at the above ages. The relative number of Purkinje cells per mm2 of sectional area of the cortex was also determined. The information presented in this study is of indicative value of the pattern of the growing cerebellum and of the ages in which the various layers and the relative number of Purkinje cells assume adult values.