Neurochemical plasticity of the carotid body in hypertension.

The carotid body (CB), a main peripheral arterial chemoreceptor, has lately been implicated in the pathophysiology of various cardiovascular disorders. Emerging experimental evidence supports a causal relationship between CB dysfunction and augmented sympathetic outflow which is the common hallmark of human sympathetic-related diseases, including essential hypertension. To gain insight into the neurotransmitter profile of chemosensory cells in the hypertensive CB, we examined the expression and cellular localization of some classical neurotransmitters, neuropeptides, and gaseous signaling molecules as well as neurotrophic factors and their receptors in the CB of spontaneously hypertensive rats, a common animal model of hypertension. Our immunohistochemical experiments revealed an elevated catecholamine and serotonin content in the hypertensive CB compared to normotensive controls. GABA immunostaining was seen in some peripherally located glomus cells in the CB of SHR and it was significantly lower than in control animals. The density of substance P and vasoactive intestinal peptide-immunoreactive fibers was diminished whereas that of neuropeptide Y-immunostained nerve fibers was increased and that of calcitonin gene-related peptide-containing fibers remained almost unchanged in the hypertensive CB. We have further demonstrated that in the hypertensive state the production of nitric oxide is impaired and that the components of the neurotrophin signaling system display an abnormal enhanced expression. Our results provide immunohistochemical evidence that the altered transmitter phenotype of CB chemoreceptor cells and the elevated production of neurotrophic factors modulate the chemosensory processing in hypertensive animals which contributes to autonomic dysfunction and elicits sympathetic hyperactivity, consequently leading to elevated blood pressure.

Histochemical and immunohistochemical localization of nitrergic structures in the carotid body of spontaneously hypertensive rats.

The carotid body (CB) is a multipurpose metabolic sensor that acts to initiate cardiorespiratory reflex adjustments to maintain homeostasis of blood-borne chemicals. Emerging evidence suggests that nitric oxide increases the CB chemosensory activity and this enhanced peripheral chemoreflex sensitivity contributes to sympathoexcitation and consequent pathology. The aim of this study was to examine by means of NADPH-diaphorase histochemistry and nitric oxide synthase (NOS) immunohistochemistry the presence and distribution of nitrergic structures in the CB of spontaneously hypertensive rats (SHRs) and to compare their expression patterns to that of age-matched normotensive Wistar rats (NWRs). Histochemistry revealed that the chemosensory glomus cells were NADPH-d-negative but were encircled by fine positive varicosities, which were also dispersed in the stroma around the glomeruli. The NADPH-d-reactive fibers showed the same distributional pattern in the CB of SHRs, however their staining activity was weaker when compared with NWRs. Thin periglomerular, intraglomerular and perivascular varicose fibers, but not glomus or sustentacular cells in the hypertensive CB, constitutively expressed two isoforms of NOS, nNOS and eNOS. In addition, clusters of glomus cells and blood vessels in the CB of SHRs exhibited moderate immunoreactivity for the third known NOS isoenzyme, iNOS. The present study demonstrates that in the hypertensive CB nNOS and eNOS protein expression shows statistically significant down-regulation whereas iNOS expression is up-regulated in the glomic tissue compared to normotensive controls. Our results suggest that impaired NO synthesis could contribute to elevated blood pressure in rats via an increase in chemoexcitation and sympathetic nerve activity in the CB.

Sex estimation by size and shape of foramen magnum based on CT imaging.

Foramen magnum (FM) has a well-protected position, which makes it of particular interest in forensic research. The aim of the study is to assess the sex differences in size and shape of FM, develop discriminant functions and logistic regression models based on the FM measurements, compare the accuracy results of the measurements obtained through different measuring approaches, and establish the most reliable variables for sex estimation in Bulgarian adults. Head CT scans of 140 Bulgarian adults were used in the study. The segmentation of the skulls was performed in the software InVesalius. The length, breadth, circumference, and area were measured based on the 3D coordinates of definite landmarks and semi-landmarks. The circumference and area were calculated regarding the foramen as a 2D and 3D structure. Two additional variables (λ2 and λ3) corresponding to the least square errors along the length and breadth directions at the fitting of the 3D coordinates to a plane were examined for their sex discriminating ability. The FM shape was classified based on the values of the FM index. The significance of the sex differences was assessed. Discriminate function analysis and binary logistic regression were conducted. Significant sex differences were established in the FM size and shape. The eigenvalue λ3 is the best discriminating parameter applying discriminant function analysis. The acceptance of FM as a 2D or 3D structure does not provide substantial information for its sex discrimination. The measurements of FM do not offer sufficiently high predicting rates for sex estimation in the Bulgarian population.

Immunohistochemical localization of angiotensin AT1 receptors in the rat carotid body.

The carotid body (CB) is a major peripheral arterial chemoreceptor that initiates respiratory and cardiovascular adjustments to maintain homeostasis. Recent evidence suggests that circulating or locally produced hormones like angiotensin II acting via AT1 receptors modulate its activity in a paracrine-autocrine manner. The aim of this study was to examine the immunohistochemical localization of AT1 receptor in the CB of adult rats and to compare its expression in vehicle-treated animals, and after the long-term application of its selective blocker losartan. Immunohistochemistry revealed that a subset of CB glomeruli and the vast majority of neurons in the adjacent superior cervical ganglion (SCG) were strongly AT1 receptor-immunoreactive. In the CB immunostaining was observed in the chemosensory glomus cells typically aggregated in cell clusters while the nerve fibers in-between and large capillaries around them were immunonegative. Exogenous administration of losartan for a prolonged time significantly reduces the intensity of AT1 receptor immunostaining in the CB glomus cells and SCG neurons. Our results show that AT1 receptors are largely expressed in the rat CB under physiological conditions, and their expression is down-regulated by losartan treatment.

Heterotopic gastrointestinal cyst mimicking chronic cholecystitis: a case report.

INTRODUCTION: Heterotopic gastric mucosa is described almost everywhere in the gastrointestinal tract, from the oral cavity to the rectum. The occurrence of heterotopic gastric tissue in the gallbladder is rare. A choristoma can be defined as a new growth developing from a displaced anlage not normally present in the anatomical site where it developed. We present an extremely uncommon case of a cyst (choristoma) attached to the gallbladder, which contained gastric and intestinal mucosa. CASE PRESENTATION: A 33-year-old woman was hospitalized with clinical symptoms of chronic cholecystitis. The laboratory findings were within the normal range. Abdominal ultrasonography revealed a thickened gallbladder wall and a stone in the cystic duct was suspected. In the course of laparoscopic cholecystectomy, a cyst was visualized in the vicinity of the duct and the gallbladder neck. Microscopic examination of the removed cyst revealed evidence of gastric, duodenal and small-intestinal mucosa. The immunohistochemical study revealed many endocrine cells, which were positive for several endocrine cell markers such as chromogranin, serotonin, gastrin and so on. It can be inferred that the observed cyst had arisen from the foregut early in the development of the gastrointestinal tract. CONCLUSION: The presence of endocrine cells together with epithelial cells supports the hypothesis that these had developed simultaneously, and that the endocrine cells had probably supported the development of the epithelial cells by the release of hormones and growth factors. To the best of the authors' knowledge, this report is the first to report a gastrointestinal cyst choristoma with endocrine cells in the region of the cystic duct and gallbladder.

Ultrastuctural immunocytochemistry of calcium-binding proteins in rapidly-adapting avian mechanoreceptors.

The localization of the calcium-binding proteins (CaBPs) calbindin-D28K (CB) and parvalbumin (PV) in avian rapidly-adapting Herbst and Grandry sensory corpuscles was studied with the use of immunocytochemistry and monoclonal antibodies. Strongest immunostaining was detected in cells of the capsule in both receptor types. Staining was more pronounced in the vicinity of endoplasmic reticulum and mitochondria in the perinuclear regions, whereas staining was distinct in pinocytotic vesicles in peripheral cytoplasmic lamellae. Fibroblasts and macrophages in the subcapsular space of Herbst receptors also showed strong immunostaining in organelles in perinuclear regions. Modified Schwann cells in both receptor types revealed moderately-expressed immunostaining, which was more pronounced in perinuclear regions. The various parts of the receptor nerve fibers showed weak to strong staining. The physiological roles of the investigated CaBPs may be associated with cytoplasmic calcium ion (Ca++) storage, which is necessary for either active metabolism in the immunostained structures and/or their transfer to sensory axonal regions where Ca++ channels are present.

The influence of carbon dioxide concentration on the neurite outgrowth of mouse embryonic cortical neurons in vitro / La influencia de la concentración de dióxido de carbono en el crecimiento in vitro de neuritas de las neuronas corticales embrionarias del ratón

The carbon dioxide (CO2) concentration of the incubation medium in nerve cell culturing has always been a matter of debate and is usually adjusted in a somewhat empirical manner. In the many laboratory protocols and manuals published to date, the data concerning this aspect differ. The goal of this study was thus to follow up the neurite outgrowth of cortical neurons in dissociated primary cultures obtained from seventeen-day-old embryonic mouse brains incubated in 90% air and 10% CO2, and in 95% air and 5% CO2 respectively. We recorded the density and confluence of the neuronal distribution in vitro on the second, third and fifth day after establishing the cultures. Morphological evaluation to demonstrate viable cells was carried out by applying immunocytochemistry for microtubule-associated protein-2 due to its ubiquity in neurons. The results showed that neuronal survival, the rate of neurite outgrowth and the establishment of intercellular networks and synaptic contacts were more pronounced in cortical cultures raised in 10% CO2-containing incubation medium than in 5% CO2-containing incubation medium. From these results, it can be inferred that CO2 at a higher concentration plays a significant role in influencing the metabolic activities of embryonic cortical neurons in vitro, thus probably determining their synaptogenesis and viability (AU)

La concentración de dióxido de carbono (CO2) del medio de incubación en el cultivos de células nerviosas siempre ha sido debatible y normalmente es ajustada de una manera un tanto empírica. En los muchos protocolos y manuales de laboratorio que han sido publicados hasta la fecha, los datos relativos a este aspecto difieren. Por tanto, nuestro objetivo en el presente trabajo ha sido de llevar a cabo un seguimiento del crecimiento de neuritas de neuronas corticales in cultivos primarios disociados obtenidas de los cerebros de ratones embrionarios de 17 días de edad incubadas en 90 por ciento aire y 10 por ciento CO2 y en 95 por ciento aire y 5 por ciento CO2 respectivamente. Registramos la densidad y confluencia de la distribución neuronal in vitro en el segundo, tercer y quinto día después de establecer los cultivos. La evaluación morfológica encaminada a demostrar células viables fue llevada a cabo aplicando métodos inmunocitoquímicos para la proteína-2 asociada a los microtúbulos debido a su ubicuidad en las neuronas. Los resultados revelaron que la supervivencia neuronal, la velocidad de crecimiento de las neuritas así como el establecimiento de redes intercelulares y contactos sinápticos eran más pronunciados en los cultivos corticales derivados del medio que contenía una concentración de CO2 del 10 por ciento que con el que contenía 5 por ciento CO2. De estos resultados, se puede deducir que, a concentraciones mayores, el CO2 juega un papel significativo en influir en las actividades metabólicas de las neuronas corticales embrionarias in vitro, así probablemente determinando su sinaptogénesis y viabilidad. (AU)