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At least 271 records · Page 15Linked to original sources
PubMed1983

[Changes in respiration after transection of the pons in decerebrate cats].

In decerebrate cats with intact nn. vagi, complete ablation of pneumotaxic center (PC) by transections of pons in vicinity of caudal border of medial parabrachial nucleus (NPBM) was not followed by a regular decrease of lungs ventilation (V), the latter consistently decreasing only after partial bilateral lesions of PC (either NPBM or Kölliker-Fuse nucleus). In partial PC lesions, changes of frequency of breathing as well as the inspiratory (TI) and expiratory (TE) durations were more obvious than after the complete PC ablation. Changes of breathing after pontine transections at NPBM caudal border were similar to those after vagotomy. The PC lesions are concluded to be able to disturb the respiration stronger than the complete PC ablations. After transections through caudal pontine levels, TI and TE prolongation was weaker than after more rostral transections due to lesions of apneustic mechanism.

Animals↗
PubMed1980

Hematomas of the pons.

Two cases of hematomas located in the latral portion of the pons that were erroneously diagnosed preoperatively as cerebellopontine angle tumors are presented. In both cases, the hematomas were evacuated successfully. Lateropontine hematomas must be included in the differential diagnosis of the cerebellopontine angle syndrome.

Adolescent↗
PubMedDate not supplied

[Solitary abscess in the region of the pons varolii].

An abscess in the region of pons varolii in a male 69 years of age with the erythrodermic form of mycosis fungoides is described. It is presumed that the source of the purulent infection were small skin excoriations from scratches due to excruciating skin itch. Long-term cytostatic and immunodepressant therapy promoted generalization of the infection and formation of the cerebral abscess.

Aged↗
PubMed1994

[A case of clinical Reye syndrome with symmetrical abnormal signal areas in the pons and thalami by MRI].

We report a two-year-old boy with clinical Reye syndrome. Brain CT disclosed symmetrical low-density areas in the pons and thalami, a part of which was recognized as being of high-intensity on both T1 and T2 weighted MRI. These lesions were suspected of being caused by vascular involvement, since the methemoglobin induced by bleeding may have contributed to the high-intensity regions. The lesions gradually disappeared within four months after the onset, and clinical symptoms also improved markedly without serious neurologic impairment. This case was characterized by the marked improvement in neurological and radiological findings in spite of the serious neurological involvement at onset.

Child, Preschool↗
PubMedDate not supplied

Ischemic and hemorrhagic necrosis of the pons with anatomical location similar to that of central pontine myelinolysis in a chronic alcoholic patient.

An autopsied case of recent ischemic and hemorrhagic necrosis of the pons is reported, in which the anatomical site of the lesion is similar to that observed in central pontine myelinolysis. The patient, a 46-year-old woman, was a chronic alcoholic who had been treated with large quantities of physiological saline and glucose solution at 5% during a period of nine days before death. On the fifth day of treatment she developed hypernatremia, which persisted for three days. From hyperglycemia on the day of admission, her serum glucose levels subsequently dropped to normal values and then rose again on the day of death. Examination of the brain revealed recent ischemic and hemorrhagic necrosis affecting the central portion of the upper two thirds of the pontine basis, in triangular, bilaterally symmetrical pattern, and extending into the tegmentum. There was no evidence of demyelination or degradation products of the myelin. No vascular alterations or thrombi were identified in the pontine vessels surrounding the lesion. The differential diagnosis of pontine infarct, central pontine myelinolysis, and Duret's hemorrhage is discussed. In analysing the possible etiology and pathogenesis of the lesion, it is suggested that osmotic vascular injuries induced by fluctuating levels of serum sodium and glucose may lead to edema and demyelination similar to that observed in central pontine myelinolysis and, rarely, to necrosis and hemorrhage, as in the present case.

Alcoholism↗
PubMed1993

[Angiographic occult vascular abnormalities in the area of the pons. Two case reports].

On the basis of two case reports of occult vascular malformation of the pons that had been followed since the first clinical manifestation, clinical picture, diagnosis using modern imaging methods (especially magnetic resonance imaging--MRI) and therapy of this disease are discussed. In addition to a precise localization diagnosis based on typical scans of varying signal intensity, particularly after bleeding, MRI also allows a preoperative qualitative identification of the lesion and provides important information about the dynamics of the process. Further experience with this uncommon clinical category will improve the early diagnosis and selection of an adequate therapy because the technique of stereotactic radiotherapy (gamma-knife) appears to be most suitable.

Adult↗
PubMed1993

Distribution of cortico-visual neurons projecting to the pons in the cat. A retrograde labelling study with rhodamine latex microspheres.

Injections of the low diffusion retrograde tracer rhodamine latex microspheres were made in the pontine grey matter of the cat in order to study the cortical convergence to the pons. We found a different distribution of cells in the convex surface of the brain hemisphere making ventral or dorsolateral injections. In the first case, cells were grouped in the top of the gyri. In the second case, cells were more frequent in the bottom of the sulci. Our results show a possible retinotopic organization of this projection.

Animals↗
PubMed1995

Morphology of neurons in the superficial layers of the rabbit's superior colliculus projecting ipsilaterally to the pons.

The superior colliculus (SC) is a laminar structure which can be separated into superficial and deep layers according to morphological and functional criteria. The superficial layers are interconnected with many nuclei, most of which process visual information. Also, these layers are known to project to the pontine grey. The topography of the projection is well established in many mammals but little is known about the morphology of the cells of origin of the projection. The pons of two adult albino rabbits were injected with Rhodamine latex microspheres and the retrogradely labeled cells in the SC were intracellularly filled with Lucifer yellow. The distribution of the labeled cells was organized into two bands. The upper one (71% of the cells) was located in the middle third of the stratum griseum superficiale (SGS). The lower band was less dense (29% of the cells) and located in the lower third of SGS and in the upper layers of the stratum opticum. Neurons corresponding to the upper band were preferentially vertically oriented. In particular, 47% were vertical fusiform, 23.5% globular/pyriform, 17.7% horizontal and 11.8% stellate in their morphology. Neurons corresponding to the lower band did not present so clear polarization. Thus, 57.1% were stellate, 28.6% were horizontal and 14.3% globular/pyriform. On the basis of their morphology, we consider that the cells of origin of the tectopontine projection form a particular population in the SC.

Animals↗
PubMed1997

Vascularization of the brain in guinea pig III. Vascular architecture of the medula oblongata, pons, and cerebellum.

The blood vessels of the medulla oblongata and pons are arranged into anterior (medial), lateral, and posterior groups. Particular part of the brain receive also blood from several sides (medial, lateral, posterior) what secures rich capillary net and vascular loops. Venous blood is drained by veins running in the same directions. The richest capillary nets are found within brain stem nuclei. The cerebellum is supplied by three cerebellar arteries.

Animals↗
PubMed1988

Raphe nucleus of the pons containing omnipause neurons of the oculomotor system in the monkey, and its homologue in man.

Omnipause neurons take part in the generation of saccadic eye movements. They lie around the midline in the caudal pontine reticular formation, in an area usually ascribed to the nucleus raphe pontis (rp). In this study of the monkey (Macaca fascicularis and M. mulatta), we describe four series of experiments aimed at establishing that omnipause neurons lie within a distinctive cytoarchitectonic entity, which we call the nucleus raphe interpositus (rip): (1) cytoarchitectural study, (2) recording-lesion experiments to establish in which cell group omnipause neurons lie, (3) cytochrome oxidase distribution in the omnipause region and neighboring structures, and (4) neuroanatomical tracing experiments to demonstrate afferents to the omnipause region. In the detailed cytoarchitectural study of the midline structures in the caudal pons and rostral medulla, a distinctive group of neurons (rip) adjoining the ventrocaudal border of rp and dorsal to the nucleus raphe magnus (rm) is described. The striking features of rip are the uniformly arranged, narrow row of the cells either side of the midline, and the extensive horizontally oriented dendritic trees of its neurons. The abducens rootlets (NVI) pass through the reticular formation at the same rostrocaudal level as rip and form a reliable landmark for its location. Cytochrome-oxidase-stained sections demonstrated additional differences between rip and adjacent cell groups: in rip the neurons and their extensive dendrites stained strongly, but not the surrounding neuropile, whereas in rp both the neurons and the neuropile stained darkly, so that individual neurons were difficult to see. Unlike rp, rip coincides with the location of omnipause neurons, and lesions marking the sites of individual omnipause units lay within its boundaries. Tritiated leucine was injected into superior colliculus (sc), which is known to have monosynaptic connections with omnipause neurons. Labelled axons and patterns of silver grains taken to indicate the presence of terminal branching were found in and around rip, but no significant labelling was seen in rp or rm. It is concluded that the omnipause neurons lie within the rip in the monkey. These functional and morphological differences between rip and the adjacent raphe nuclei are used to justify its characterization as an independent cell group in the monkey. In order to relate these findings to man, cytochrome oxidase experiments were carried out on the human brainstem, and the pattern of staining at the level of the abducens rootlets was correlated with the cytoarchitecture.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMedDate not supplied

Paraoxonase (PON 1) as a biomarker of susceptibility for organophosphate toxicity.

Paraoxonase (PON1) is an A-esterase capable of hydrolysing the active metabolites (oxons) of a number of organophosphorus (OP) insecticides such as parathion, diazinon and chlorpyrifos. PON1 activity is highest in liver and plasma, and among animal species significant differences exist, with birds and rabbits displaying very low and high activity, respectively. Human PON1 has two polymorphisms in the coding region (Q192R and L55M) and five polymorphisms in the promoter region. The Q192R polymorphism imparts different catalytic activity toward some OP substrates, while the polymorphism at position -108 (C/T) is the major contributor to differences in the level of PON1 expression. Animal studies have shown that PON1 is an important determinant of OP toxicity, with animal species with a low PON1 activity having an increased sensitivity to OPs. Administration of exogenous PON1 to rats or mice protects them from the toxicity of OPs. PON1 knockout mice display a high sensitivity to the toxicity of diazoxon and chlorpyrifos oxon, but not paraoxon. In vitro assayed catalytic efficiencies of purified PON(192) isoforms for hydrolysis of specific oxon substrates accurately predict the degree of in vivo protection afforded by each isoform. Low PON1 activity may also contribute to the higher sensitivity of newborns to OP toxicity.

Animals↗
PubMed1985

Volume comparisons in the cerebellar complex of primates. I. Ventral pons.

Volumes of the ventral pons (VPo) were measured in 82 brains of primates, Scandentia, and Insectivora, and the relative size of the VPo was expressed by size indices. The reference line was through the prosimian average; the mean index of prosimians was set at 1. The taxonomic groups arranged in a sequence of ascending mean VPo indices were: Insectivora (0.04), prosimians (1.00), monkeys (2.55), apes (4.48) and man (9.44). Thus, the VPo of man is more than 9 times larger than that of isoponderous average prosimians, and more than 230 times larger than that of isoponderous "basal' insectivores. The indices may reflect trends and extent of VPo evolution in primate phylogeny.

Animals↗
PubMed2002

Abrupt onset of sensorineural hearing loss and tinnitus in a patient with capillary telangiectasia of the pons.

Capillary telangiectasia is often found incidentally on magnetic resonance imaging and may be associated with minor neurologic symptoms, but there has been little evidence about whether such lesions are responsible for these symptoms. Here we report a case of capillary telangiectasia of the right mid pons, which was associated with the abrupt onset of tinnitus and sensorineural hearing loss. Examination of the auditory brain stem responses showed abnormalities of waves III and IV on the left and bilateral prolongation of the interwave intervals. Optokinetic nystagmus showed slight left-right asymmetry.

Adult↗
PubMed1997

Computed tomography-guided stereotactic aspiration and biopsy of a cystic metastatic adenocarcinoma of the pons.

We herein report a case of adenocarcinoma of the right main bronchus disseminated to the pons, left cerebral peduncle, and liver. Computed tomography-guided Cosman-Robert-Wells stereotactic aspiration of the cystic pontine lesion was performed through a transoccipital, transtentorial route and a catheter inserted in the cyst cavity that was connected to a subgaleal Ommaya reservoir for further aspiration and decompression. The choice of this approach to the lesion is briefly discussed.

Journal Article↗