Biomedical subjects

C B Luo

Publications and source records attributed to C B Luo.

34 records · Page 2Linked to original sources

PubMed1998

Endovascular embolization of arteriovenous fistulas of the external carotid artery.

BACKGROUND: External carotid arteriovenous fistulas (AVFs) are rare and most hospitals have limited experience with their management. This study was designed to evaluate the effectiveness and safety of endovascular embolization of AVFs of the external carotid artery under angiographic control. METHODS: A series of 13 patients with AVFs involving the branches of the external carotid artery, all treated with endovascular embolization, were reviewed. There were 10 males and three females ranging in age from nine to 46 years, with a mean of 27 years. The most frequent presenting symptoms were pulsatile tinnitus, followed by bruit and/or thrill, ocular problems, headache and a pulsatile mass in the neck. The middle meningeal artery was most often involved, followed by the internal maxillary artery and the occipital artery. The AVFs were caused by trauma in 10 patients and occurred spontaneously in three. N-butyl-2-cyanoacrylate was used to embolize the fistula in 11 patients and a detachable balloon was used in two. RESULTS: All the patients were cured and no significant complications were observed. No recurrence was noted after a clinical follow-up of three months to seven years (mean, 37 months). CONCLUSIONS: Endovascular embolization proved to be a safe and effective procedure. It should be the treatment of choice for repair of external carotid AVFs.

Adolescent↗

PubMed1998

Orbital invasion in nasopharyngeal carcinoma: evaluation with computed tomography and magnetic resonance imaging.

BACKGROUND: Ocular symptoms and tumor cranial nerve involvement are commonly observed in patients with nasopharyngeal carcinoma (NPC). These are primarily due to tumor invasion of the cavernous sinus and/or skull base, as direct tumor invasion of the orbit is very rare. This study was designed to assess computed tomography (CT) and magnetic resonance imaging (MRI) in documenting orbital invasion caused by NPC, with a special emphasis on the route of orbital extension. METHODS: A total of 562 patients with histopathologically prove NPC were examined using CT and/or MRI for tumor staging or post-treatment follow-up. We retrospectively reviewed CT and MRI findings to identify tumor invasion to orbital cavities and to evaluate the pathway of tumor spread. RESULTS: Eighteen patients had tumor extension into the orbital cavities. Seventeen patients had ocular complaints. Fourteen of 18 showed unilateral orbital involvement and four patients showed bilateral orbital involvement. The route from the pterygopalatine fossa and inferior orbital fissure into the orbital cavities was the most common pathway of NPC invasion (n = 13), followed by ethmoid sinus and/or sphenoid sinus into the orbits (n = 4). In one patient, the route of orbital invasion was difficult to determine due to massive tumor extension. CONCLUSION: Direct orbital invasion is rare in NPC. The pterygopalatine fossa and inferior orbital fissure are the most common routes of invasion, followed by invasion via the ethmoid and/or sphenoid sinuses. Coronal sections best show these findings on CT or MRI. Our study also shows that either CT or MRI provide essential information in documenting orbital invasion and determining the pathway of tumor spread.

Adult↗

PubMed1997

Differential expression of calretinin, calbindin D28K and parvalbumin in the developing human cerebellum.

Three calcium-binding proteins, calretinin, calbindin D28K and parvalbumin, were immunohistochemically localized in the human cerebellum at different developmental stages. Cells positive for calretinin were not detected during early development of the cerebellum until 21 weeks of gestation at which stage weak staining was found in Purkinje and basket cells of the cortex and in neurons of the dentate nucleus. Both the number of positive cells and the intensity of immunoreactivities were found to increase as the cerebellum became more mature. Calbindin D28K immunoreactivity was, however, detected early in development at 14 weeks of gestation. Positive cells were found in Purkinje, basket, stellate and granule cells of the cerebellar cortex and in neurons of fastigial, globose, emboliform and dentate nuclei. The number of positive cells and the staining intensity for calbindin in both the cerebellar cortex and deep nuclei decreased at more advanced developmental stages. At 21-31 weeks of gestation, positive staining was restricted to Purkinje and basket cells of the cortex. Parvalbumin immunoreactivity was also observed early in development at 14 weeks of gestation. Positivity was found in Purkinje, basket and stellate cells of the cerebellar cortex and in neurons of all the deep nuclei, with the highest number of positive cells in the fastigial nucleus followed by emboliform, globose and dentate nuclei. As the cerebellum became more mature, both the number of positive cells and the staining intensity for parvalbumin decreased in the cortex and deep nuclei. The results of the present study showed that among the three calcium-binding proteins examined, strong immunoreactivities for calbindin D28K and parvalbumin were found inthe human cerebellum early in development at 14 weeks of gestation, but there was a decrease in both the intensity and number of positive cells at more advanced stages. In contrast, calretinin positive cells were not detected until 21 weeks of gestation and the immunoreactivity increased as the cerebellum became more mature. A possible correlation between the developmentally regulated expression of the calcium-binding proteins and expression of different neurotransmitters during development is discussed.

Abortion, Induced↗

PubMed1997

Intracranial ganglioglioma: CT and MRI findings.

Thirteen cases of pathologically proved intracranial gangliogliomas were reviewed in order to define the characteristic computed tomography (CT) and magnetic resonance image (MRI)-features. All patients were evaluated with CT and four of them were studied by MRI. Six tumors were cystic dominant mixed masses with remarkable focal contrast enhancement (6/13, 46%); and seven were solid in nature with variable contrast enhancement (7/13, 54%). Nine of them contained calcification (9/13, 69%). The temporal lobe was affected in six patients (6/13, 46%); the posterior fossa in four patients; the frontal lobe in two; the remaining huge one in the frontal, temporal and basal ganglion. On MRI, the findings were similar to those of the CT. Gangliogliomas do not have a characteristic CT and MRI features. They may appear as pure cystlike tumors, cystic dominant mixed tumors with remarkable focal contrast enhancement, solid tumors with variable contrast enhancement or diffuse involving the brain parenchyma and/or subarachnoid spaces. However, radiologists should include ganglioglioma in the differential diagnosis when we find patient has a long-standing process as well as a calcified tumor in the temporal lobe with following characteristic; cystic dominant mixed tumor with remarkable focal contrast enhancement, or a solid mass without hemorrhage or significant surrounding edema.

Adolescent↗

PubMed1996

Immunohistochemical studies of GABA and parvalbumin in the developing human cerebellum.

The localization of GABA and parvalbumin was studied in the developing cerebellum of human fetuses from 16 to 28 weeks of gestation. The avidin-biotin complex immunohistochemical method combined with silver staining were used to reveal the presence of GABA- and parvalbumin-positive neurons and nerve fibres. As early as the 16th week of gestation, GABA immunopositivity was observed in the cerebellar cortex and the deep nuclei. GABA-positive neurons included Purkinje cells, stellate and basket cells of the cerebellar cortex and neurons in the deep nuclei. The gradient of immunoreactivity increased with the maturing cells, being weak at 16 weeks and becoming markedly pronounced at 28 weeks of gestation. GABA-immunopositive mossy fibres were observed in the granular cell layer at 16 weeks, and by 28 weeks, a robust fibre network was present in the cortex and deep nuclei. Immunohistochemical localization for parvalbumin indicates that weak immunoreactivity was observed in Purkinje cells, stellate and basket cells at 16 weeks of gestation, increasing in intensity with advancing age, notably in the Purkinje cells which had acquired an elaborate arbor of neurites at 28 weeks of gestation. In the deep nuclei, parvalbumin-positive cells and nerve fibres were observed throughout the 16 to 28 week period. These results indicate that GABA- and parvalbumin-positive neurons and fibres appeared as early as 16 weeks of gestation, expressing a high degree of immunoreactivity by the 28 week of fetal age.

Cerebellum↗

PubMed1995

Tyrosine hydroxylase- and dopamine-beta-hydroxylase-positive neurons and fibres in the developing human cerebellum--an immunohistochemical study.

Six human fetuses of gestational ages 16-28 weeks were employed. The immunocytochemical avidin-biotin-peroxidase complex method combined with the silver Bodian technique was used to evaluate the presence of tyrosine hydroxylase and dopamine-beta-hydroxylase neurons and afferent and efferent fibres in the cerebellum during development. Our results illustrated that by 16-18 weeks, immunoreactivity of the Purkinje cells and the granule cells was evident. By 23 weeks, the positive Purkinje cells were tightly packed together and the perinuclear granules began to extend into the processes. The positive cells next to Purkinje cells were the basket cells and stellate cells. By 26-28 weeks, all positive cells increased in number and size. Mossy and climbing fibres appeared early in development (16-18 weeks of gestation) and were seen synapsing with the positive granule cells. At the same time, some parallel fibres were observed. At later stages, the tyrosine hydroxylase- and dopamine-beta-hydroxylase-positive Purkinje cells were surrounded by abundant climbing fibres, while parallel fibres were also evident in the molecular layer. In the deep cerebellar nuclei, positive tyrosine hydroxylase and dopamine-beta-hydroxylase neurons were present by 16-18 weeks of development. Those in the dentate nucleus were more polymorphic but smaller in size. Some afferent fibres were also spotted around 16-18 weeks of gestation and their numbers increased later. Positive efferent fibres were present by 26 weeks. All these observations point to an early presence of tyrosine hydroxylase and dopamine-beta-hydroxylase components in cerebellar development.

Avidin↗

PubMed1994

Distribution of neuropeptide Y in the developing human spinal cord.

The distribution of neuropeptide Y at different levels of the spinal cord of 23 human fetuses aged from 10-41 weeks of gestation was studied using immunocytochemical staining. Neuropeptide Y-immunoreactive neurons were identified at all levels of the spinal cord examined as early as 10 weeks of gestation. These cells were localized in the superficial layers (laminae I and II of Rexed) of the dorsal gray matter. As the age of the fetuses increased, their cell number increased and the region containing positive neurons extended from the superficial to deep layers (laminae III and VI). Immunoreactive fibers started to appear in fetuses at 10 weeks of gestation. They were found not only in the gray and white matters, but also in the pia mater lining the spinal cord. As the fetuses aged, the neuropeptide Y-immunoreactive fibers became mostly concentrated in the intermediate zones of the thoracic and sacral segments corresponding to the developing autonomic centers. Our results suggest that neuropeptide Y may play a role in the early development of the autonomic system.

Embryonic and Fetal Development↗

PubMed1993

An immunohistochemical study of neuropeptide Y positive sites in the developing human hippocampal formation.

Neuropeptide Y (NPY)-positive sites were evaluated by immunohistochemistry in the hippocampal formation of human fetuses aged from 15 to 41 weeks of gestation. Immunopositive cells and fibers were identified in the hippocampus as early as 15 weeks of gestation. These cells were localized in the polymorphic and pyramidal layers and their numbers increased with the age of the fetuses. NPY-positive cells were observed to be closely apposed to blood vessels and some NPY fibers, present mainly in the polymorphic layer, would infiltrate the alveus.

Binding Sites↗

PubMed1993

Habenulo-interpeduncular descending pathways and their relationship to enkephalin- and somatostatin-immunoreactive neurons in the interpeduncular nucleus of human fetuses.

The interpeduncular nucleus of six human fetuses aged 15 (one specimen), 26 (one specimen), 38 (one specimen) and 40 (three specimens) gestation weeks was studied by immunohistochemistry for enkephalin and somatostatin localization and immunohistochemistry coupled with silver staining. Enkephalin-positive and somatostatin-positive cells were detected, the former initially at 15 weeks gestation and the latter at 26 weeks gestation. They appeared to receive long afferents from the habenular region and projected short efferents to adjacent cells devoid of enkephalin and somatostatin positivity. We postulate that these enkephalin- and somatostatin-positive neurons function as modulatory interneurons in the habenulo-interpeduncular and related pathways.

Enkephalins↗

PubMed1992

Acetylcholinesterase-containing neurons, substance P and enkephalin fibers in the ventral horns of developing human embryos and fetuses.

The presence of the acetylcholinesterase neurons and substance P-like and enkephalin-like fibers in the various nuclear columns of the ventral horns of the spinal cords was studied in the developing human by acetylcholinesterase histochemistry and substance P and enkephalin immunohistochemistry. Acetylcholinesterase-positive neurons initially appeared in the lateral neuronal columns and eventually were also observed in the medial columns as well as the median columns at various levels of the spinal cord by 10 weeks' gestation. Acetylcholinesterase-positive neurons in the lower sacral levels were not detected until 11-12 weeks' gestation. Diffused substance P- and enkephalin-like fibers were demonstrated as early as 10 weeks' gestation but did not align with any particular nuclear column until after 15 weeks' gestation. These fibers further increased in length and adopted reticular branching patterns and many of these tended to surround the cell bodies of the nuclear columns. Possible interaction of acetylcholinesterase neurons and substance P and enkephalin fibers would commence by 15 weeks' gestation.

Acetylcholinesterase↗

PubMed1992

Immunohistochemical localization of enkephalin and substance P in the nucleus caudalis of the spinal trigeminal V in the medulla oblongata of the human fetus.

The distribution of enkephalin-positive neurons, substance P-positive and enkephalin-positive fibers was studied in the nucleus caudalis of the trigeminal spinal V in the medulla oblongata regions of developing humans (12 weeks gestation to 40 weeks gestation). Enkephalin-positive neurons were identified in all the subnuclei of the nucleus caudalis as early as 12 weeks of gestation and increased in number as the fetus aged. Substance P-positive neurons were absent in this area throughout development. On the other hand, substance P-positive and enkephalin-positive fibers were present in all the subnuclei, again commencing as early as 12 weeks of gestation. These fibers tended to be linked to each other in the different subnuclei and to the reticular formation in this area and to increase significantly in quantity by the latter quarter of pregnancy. These results show the early presence of these neurons and fibers in the first trimester of development.

Abortion, Spontaneous↗

PubMed1991

Immunohistochemical localization of substance P, enkephalin and serotonin in the developing human retina.

The localization of substance P (SP), enkephalin (ENK) and serotonin (5-HT) in the retinae of 12 human embryos/fetuses ranging in age from 6-30 weeks was determined immunohistochemically using the PAP method. At the 6 week stage [crown rump length (CRL) unknown due to incomplete specimen], the developing retina consisted of a single undifferentiated cell mass from which immunoreactive cells were absent. By 90 mm CRL (10th week of gestation), the retina was composed of an outer neuroblastic layer, an inner plexiform layer and an innermost layer of ganglion cells. At this stage, SP, ENK and 5-HT positive cells were detected solely in the outer neuroblastic layer. By 140 mm CRL (17 weeks), the retina consisted of cell layers similar in number and type to those of the adult retina. In specimens 140-216 mm CRL (gestation ages 17-24 weeks), SP, ENK and 5-HT neurons were present in the outer nuclear, inner nuclear and inner plexiform layers. In addition, 5-HT positive neurons and fibers were evident in the outer plexiform layer. By 285-295 mm CRL (26-30 weeks), neurons in the ganglion cell layer and the fovea were also SP and ENK positive. In earlier specimens, the cell bodies alone were immunopositive and not until 142 mm CRL (17 weeks) were positive processes observed. Finally, the presence of SP, ENK and 5-HT immunopositive structures occurred in a sequence from outer to inner layers of the developing human retina.

Embryo, Mammalian↗

PubMed1990

Development and localization of enkephalin and substance P in the nucleus of tractus solitarius in the medulla oblongata of human fetuses.

The presence of enkephalin and substance P-positive neurons and fibers were studied by immunohistochemistry (peroxidase-antiperoxidase or avidin-biotin-peroxidase complex methods) in 26 human fetuses ranging from 11 weeks of gestation to 40 weeks of gestation. Enkephalin-positive neurons were localized in the commissural, medial and intermediate subnuclei as early as 11-12 weeks' gestation. Positive enkephalin fibers were localized around 12 weeks' gestation and in many subnuclei, notably the medial, commissural, intermediate, ventrolateral, ventral and dorsolateral subnuclei. Substance P-positive neurons were localized in the commissural and medial subnuclei around gestation age 13 weeks. Positive substance P fibers appeared even earlier, around 11 weeks of gestation in many subnuclei, notably the medial, intermediate, ventral, ventrolateral and dorsolateral subnuclei. Increase in both enkephalin- and substance P-positive fibers was evident in the later stages of development (e.g. around 26 weeks of gestation). The importance of the early appearance of enkephalin and substance P neurons and fibers of the pain pathways in the major subnuclei connecting with the cardiovascular, gastrointestinal and respiratory functions in the human has to be stressed.

Embryonic and Fetal Development↗

PubMed1990

Localization of acetylcholinesterase positive neurons and substance P and enkephalin positive fibers by histochemistry and immunohistochemistry in the sympathetic intermediate zone of the developing human spinal cord.

Localization of acetylcholinesterase positive neurons and substance P and enkephalin fibers were studied by histochemistry and immunohistochemistry in the intermediate sympathetic zone of the spinal cords of 39 human embryos/fetuses from gestation ages five to 40 weeks. Acetylcholinesterase positive neurons were observed in the nucleus intermediolateralis pars principalis as early as the fifth week of gestation. By the ninth to 13th weeks of gestation, positive neurons were also seen in the nuclei intermedialis pars funicularis, intercalatus spinalis and intercalatus pars paraependymalis. Increase in amount of these positive acetylcholinesterase neurons was demonstrated till term. Substance P and enkephalin fibers were initially observed by the eighth gestation week in the intermediolaterlis pars principalis nucleus and positive fibers were then detected in the nucleus intermedialis pars funicularis as well as the nucleus intercalatus spinalis by the 14th week of gestation. By the 26th week of gestation, all the major nuclei intermediolateralis par principalis, intermedialis pars funicularis, intercalatus spinalis and intercalatus pars paraependymalis has substance P and enkephalin fibers. Initial demonstration of acetylcholinesterase positive neurons appeared to be at an earlier stage than that of our substance P and enkephalin positive fibers.

Acetylcholinesterase↗

PubMed1988

Localization of substance P and enkephalin by immunohistochemistry in the spinal cord of human fetus.

The peroxidase-antiperoxidase method was used to study the distribution of substance P and enkephalin during development of the spinal cords of human fetuses. Thirty-seven cases were collected, ranging from 5- to 40-weeks-old (fetal ages). Both types of transmitters were present initially around the fifth week in the mantle layer of the base of the dorsal horn, around the tenth week at the anterior gray and the intermediate gray and around the sixth week at the marginal layer at the base of the ventrolateral funiculus. Substance P- and enkephalin-positive sites at the marginal layers at the base of the dorsolateral funiculus were evident in the same area at 5-6 weeks. The positive fibers in the dorsal horn were initially located in the superficial layers. By the eleventh week, the positive sites spread to other surface layers at the lateral sides of the dorsal horns bilaterally at all spinal levels above the sacral. In the sacral levels adjacent to the conus medullaris, the spreading to surface layers was not apparent bilaterally until the seventeenth week. By weeks 18-26 the positive sites penetrated deeper in the dorsal horn and by week 27 assumed the adult path. The enkephalin cell bodies were present in the Rexed layers I and II of the dorsal horn and the substance P-positive sites were apparent in the dorsal ganglia of the 28-40-week-old fetuses.

Enkephalins↗

PubMedDate not supplied

Neurotransmitters and neuropeptides in the developing human central nervous system. A review.

This is a review on the ontogenesis of major neurotransmitters and neuropeptides in the developing human central nervous system. In general, the molecules under study appeared early in development, usually in the first trimester. Cholinergic neurons were found to be present around the time of neuropeptide formation. The newly formed neuropeptidergic fibers extended towards the cholinergic centers where both might interact. In the major centers of the central nervous system, neuropeptides were also noted to colocalize with various neurotransmitters. For example, in the facial nucleus, enkepahlin and substance P fibers coexisted with cholinergic and catecholaminergic neurons, suggesting complex interactions. In the interpeduncular nucleus, peptidergic neurons acting as interneurons clearly modulated the afferent input to this nucleus. In the hippocampus and in sensory organs such as the retina, there were indications that neuropeptides and gamma-amino butyric acid coexisted. We hypothesize that interactions of neurotransmitters and peptides in neurons and fibers early in development play an indispensable role in the morphogenesis of the human central nervous system.

Central Nervous System↗