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Biomedical subjects

C Y Chai

Publications and source records attributed to C Y Chai.

At least 109 records · Page 6Linked to original sources
PubMed1995

Pressor effects elicited from the periaqueductal grey, and dorsal and ventrolateral medulla in cats are independent from cerebellar mechanisms.

Cats were anesthetized with chloralose (35 mg/kg, i.p.) and urethane (350 mg/kg, i.p.). In 5 cats, the pressor regions of periaqueductal grey (PAG) of the midbrain were stimulated electrically (rectangular pluses, 80 Hz, 0.5 ms, 100-150 microA). In another 6 cats, the pressor regions of both dorsal medulla (DM) and ventrolateral medulla (VLM) previously located by electrical stimulation in the same cat were stimulated by sodium glutamate (Glu, 0.25 M, 100 nl). After control stimulation, the superior, middle and inferior cerebellar peduncles on both sides were transected while the stimulating electrodes were maintained in the same position. Changes of systemic arterial pressure (SAP) and plasma norepinephrine (NE) and epinephrine (EP) following stimulations of the PAG, DM or VLM were compared before and after transections. It was found that the transection did not cause significant changes in the resting SAP and plasma NE and EP and also the induced pressor responses, namely the increases of above parameters. Findings suggest that the sympathetic vasomotor effect and adrenomedullary secretion resulted from stimulations of both DM and VLM and possibly PAG are independent from the cerebellar mechanism.

Animals↗
PubMed1994

A mixture of allogeneic and autologous microskin grafting of rabbit skin wounds with Biobrane overlay.

A mixture of allogeneic and autologous microskin grafts (10:1 expansion ratio) were transplanted and overlain with Biobrane, on to full-thickness skin wounds (8.0 x 5.0 cm in size) in 16 rabbits. They were divided into two groups: in group I, the expansion ratio of both allo- and autograft was 20:1; in group II, the expansion ratio of allo- and autograft was 15:1 and 30:1 respectively. On day 9, all wounds of group I and II were almost completely resurfaced with neoepithelium. There was no serious rejection reaction within the neoepithelium and the wounds were maintained completely resurfaced after day 9. There were scales on the epithelialized wound which were more numerous in group II than in group I. Histological examination revealed that these wounds were resurfaced with well-differentiated epithelium which contained two different histological patterns. They were identified as the survived transplanted allogeneic and autologous microskin grafts, each having their own characteristic histological features and different sex chromosome. Thus both the largely expanded allogeneic and autologous microskin grafts could proliferate together and contribute to the resurfacing of the wound. With this method, the rabbit skin wound could be resurfaced completely after the ninth postoperative day with markedly minimized amounts of autologous and allogeneic grafts.

Animals↗
PubMed1994

Activation of neurons in cardiovascular areas of cat brain stem affects spinal reflexes.

In 65 cats anesthetized with chloralose (40 mg/kg) and urethane (400 mg/kg), the effects of electrical stimulation and microinjection of sodium glutamate (0.25 M, 100-200 nl) in the pressor areas in the rostral brain stem on the evoked L5 ventral root response (EVRR) due to intermittent stimulation of sciatic afferents were compared to stimulating the dorsomedial (DM) and ventrolateral (VLM) medulla. In general, stimulating these rostral brain stem pressor areas including the diencephalon (DIC) and rostral pons (RP) produced increases in systemic arterial pressure (SAP). In most of the cases (85%) there were associated changes in the EVRR, predominantly a decrease in EVRR (72%). Stimulation of the midbrain (MB, principally in the periaqueductal grey) produced decreases in SAP and EVRR. Decreases in EVRR was observed in 91% of the DM and VLM stimulations in which an increase in SAP was produced. This EVRR inhibition was essentially unaltered after acute midcollicular decerebration. Increases in EVRR were also observed and occurred more often in the rostral brain stem than in the medulla. Since changes of both EVRR and SAP could be reproduced by microinjection of Glu into the cardiovascular-reactive areas of the brain stem, this suggests that neuronal perikarya in these areas are responsible for both actions. On some occasions, Glu induced changes in EVRR but not in SAP. This effect occurred more frequently in the rostral brain stem than in the medulla. The present data suggest that separate neuron population exist in the brain stem for the integration of SAP and spinal reflexes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

The increase of femoral arterial flow by stimulating the dorsal and ventral medulla in cats.

1. In chloralose-urethane anaesthetized cats, the dorsal cardiovascular reactive area (DCRA) in the parvocellular reticular nucleus dorsomedial to the facial nucleus, and the ventral cardiovascular reactive area (VCRA) ventromedial to the facial nucleus, were stimulated by microinjections of sodium glutamate (100-200 nmol) or electric current. 2. Stimulation of DCRA, with a long latency of 15-20 s, elicited a marked increase of blood flow in the contralateral femoral artery with little change to moderate increase in systemic arterial blood pressure (ABP). In the relatively dorsal portion of DCRA, however, a smaller increase of blood flow in the ipsilateral femoral artery was elicited. 3. On the other hand, stimulation of VCRA with a short latency (3-5s) evoked an increase of blood flow in both femoral arteries which was more prominent on the contralateral side. The responses were accompanied with decreases in the blood flow of other vascular beds with only a slight increase or minimal change in ABP. 4. The data suggest that DCRA and VCRA are both viscerotopically organized to alter the resistance of individual vascular beds for redistribution of blood flow.

Animals↗
PubMed1994

Imaging diagnosis of cavernous hemangioma of the rib--one case report and review of the literature.

Osseous hemangioma is a benign neoplasm, rarely located in the ribs. A 56-year-old female patient without specific complaint had a large extrapleural lesion on chest posteroanterior radiograph. Expansile destruction of left seventh rib and relatively fine trabeculation were noticed in the mass from plain roentgenogram and computed tomography (CT). Contrast enhancement in noncalcified component of the lesion was revealed. Pleural effusion, lung parenchymal or mediastinal abnormality were not identified. Resection of the lesion with part of the originating rib was carried out. The pathologic diagnosis was cavernous hemangioma. We present a case with a large rib hemangioma which often leads to difficulty in radiologically differential diagnosis with other common malignant rib tumors. We also review the literature about hemangioma and malignant neoplasms of the ribs.

Bone Neoplasms↗
PubMed1994

Sympathoadrenal reactions during asphyxia in hypoglycemia and hyperglycemia of cats.

In 26 cats anesthetized with alpha-chloralose and urethane, cardiovascular changes during asphyxia in hypoglycemia and hyperglycemia were studied. Systemic hypoglycemia (serum glucose decrease from 148 to 31 mg/100 ml) was produced by i.v. injection of insulin 20 U/kg, followed by continuous I.V. infusion of 10 U/kg/hr. Systemic hyperglycemia (serum glucose increase from 187 to 657 mg/100 ml) was produced by I.V. infusion of 25% glucose at a rate of 1.5 gm/kg/hr. During hypo- or hyperglycemia, resting mean systemic arterial pressure (MSAP) and heart rate did not change significantly. Brain transection at various levels, i.e., midcollicular decerebration, ponto-medullary or medulla-spinal transection progressively decreased the resting MSAP, but not the heart rate. The most apparent reduction was at the medulla-spinal junction. After induction of systemic hypo- or hyperglycemia, plasma catecholamine concentrations increased significantly. Further increase occurred during asphyxia. Increases of MSAP and plasma catecholamine concentrations during asphyxia were attenuated after midcollicular decerebration and decreased further after subsequent ponto-medullary and medulla-spinal transections. Increases in plasma catecholamines during asphyxia were greater in hypoglycemic than those in hyperglycemic state. The increase in plasma catecholamine persisted in hypoglycemic animals during asphyxia after midcollicular decerebration and ponto-medullary transections. As the terminal stage of asphyxia approached spasmodic contractions of urinary bladder occurred. Bladder contractions were abolished after intracerebroventricular (lateral) injection of insulin (0.25 unit/kg). In conclusion, asphyxia produced very marked cardiovascular and plasma catecholamine responses during hypo- or hyperglycemia and more so during the former condition. These reactions depend mainly on the neural mechanisms of medullary structures. Neural structures rostral to the midcollicular level are not essential.

Animals↗
PubMed1993

The interaction between locomotion, striatal dopamine and paramedian reticular nucleus in rats.

Either intact rats, sham-operated rats, or rats with lesions of the paramedian reticular nucleus (PRN) were exposed to cold (2 degrees C) or heat (36 degrees C) stress and their locomotor activity responses and striatal dopamine (DA) release were compared. At room temperature (22 degrees C), results analyzed revealed significant effects in the PRN-lesioned rats: increases in locomotion (including both horizontal and vertical motion), direction of turnings (including both clockwise and anticlockwise) or striatal DA release. In both the intact rats and the sham-operated rats, either cold or heat stress increased the locomotion, the direction of turnings and the striatal DA release. The increases in both vertical motion and striatal DA release following cold or heat stress were attenuated by PRN lesions. The data suggest that a PRN-striatal DA link existing in rat's brain which affects both the spontaneous and the thermal stress induced locomotor activities.

Animals↗
PubMed1993

Antagonistic effects of stimulation of the paramedian reticular nucleus in the rat medulla oblongata and of amphetamine on locomotor activity and striatal release of dopamine-like material.

The effects of stimulation of the paramedian reticular nucleus (PRN) in the rat medulla oblongata on both amphetamine-induced locomotor activity and striatal release of dopamine-like material were assessed. PRN stimulation (by intra-PRN injection of the excitatory amino acid, kainic acid) decreased vertical motion and total distance travelled, and increased postural freezing, in freely moving rats. On the other hand, a small dose (e.g. 1.25 mg/kg, i.p.) of amphetamine increased locomotor activity (including horizontal motion, vertical motion, total distance travelled and lines crossed counts), increased the number of turnings (both clockwise and anti-clockwise), induced locomotor stereotypy (including both gamma value and number of trip types), and inhibited postural freezing. The changes in activity induced by amphetamine administration were suppressed following PRN stimulation. In vivo voltammetric data revealed that electrical stimulation of the PRN decreased the release of dopamine-like material in the corpus striatum. This effect could be mimicked by intra-PRN injection of kainic acid in anesthetized rats. In contrast, i.p. administration of amphetamine increased the release of dopamine-like material in the corpus striatum. Furthermore, the enhanced release of dopamine-like material induced by amphetamine was attenuated by simultaneous stimulation of the PRN. The results reported here indicate that PRN stimulation decreases the striatal dopamine release and results in attenuation of the amphetamine-induced locomotor activity responses in rats.

Amphetamine↗
PubMed1993

Allogeneic microskin grafting of rabbits' skin wounds.

Allogeneic microskin grafts (expansion ratio of 10:1), overlain with Biobrane, were applied to 30 rabbits. There were two groups. In group I, the allogeneic donor microskin grafts were transplanted without specific management. In group II, the donor skin was treated with ultraviolet (312 nm) irradiation to depress Langerhans cells immediately before the transplantation. Histological examination of these grafted wounds in the early stage showed that these micrografts proliferated actively with increased mitotic figures and became regularly stratified under the conditions provided by the Biobrane. By day 9, these wounds in group I were almost resurfaced with neoepithelium. In group II, the rate of regeneration of the neoepithelium was slower than those of group I. Subsequently there was rejection with moderate mononuclear infiltration, hydropic degeneration and satellite necrosis of basal and suprabasal keratinocytes, and local destruction of epithelium. Grossly these reactions caused 'melting' of the neoepithelium and resulted in raw areas. These rejections were more severe about 2 weeks after transplantation and then subsided gradually. Mild cellular infiltration continued to prevent the formation of rete ridges and the dermoepidermal junction was smooth at all times. Langerhans cells could not be found in these grafted wounds using OKT-6 and S100 stain. In spite of the destruction caused by these rejections in both groups, 25 wounds were completely resurfaced with well-differentiated neoepithelium by day 21. This study revealed that the transplanted allogeneic microskin grafts could proliferate to form neoepithelium and resurface the skin wounds of rabbits.

Animals↗
PubMed1993

Effects of insulin on the cardiovascular integrating mechanisms of brain stem in cats.

In 65 cats anesthetized with alpha-chloralose and urethane, the effects of insulin on cardiovascular responses to stimulation of various structures in the brain stem were studied. The threshold dose of insulin injected intravenously that produced systemic hypoglycemia was 5-10 U/kg. Subthreshold hypoglycemic doses of insulin were used intracerebroventricularly (0.25 U/kg) or intracerebrally (2 mU in 200 nl). Sixty minutes after intravenous insulin, when serum glucose concentrations decreased from 158 to 43 mg/100 ml, pressor responses to stimulation of the periaqueductal gray of midbrain (PAG), locus coeruleus (LC), dorsal medulla (DM), ventrolateral medulla (VLM), and parvocellular reticular nucleus (PVC) decreased significantly. Depressor and bradycardiac response to stimulation of paramedian reticular nucleus or dorsal motor nucleus of vagus (DMV) decreased significantly as well. Thirty minutes after intracerebroventricular insulin, pressor responses of PAG, DM, and the bradycardiac response of DMV decreased significantly. Thirty minutes after intracerebral insulin, pressor responses and renal nerve activities of LC (but not PAG), VLM, DM, and PVC decreased significantly. A similar but faster onset (5 min) of depression of cardiovascular responses on stimulating the LC, VLM, DM, and PVC was observed in another six acutely midcollicular-decerebrate cats recovered from halothane anesthesia. These findings suggest that insulin directly inhibits the vasomotor structures of the brain stem and decreases the pressor responses to stimulation.

Animals↗
PubMed1993

Glutamate activation of neurons in CV-reactive areas of cat brain stem affects urinary bladder motility.

To investigate the interaction between cardiovascular (CV)-reactive areas in the brain stem and urinary bladder (UB) motility, 48 adult cats of either sex were anesthetized intraperitoneally with alpha-chloralose (40 mg/kg) and urethan (400 mg/kg). The changes of UB motility and systemic arterial blood pressure (SAP) were produced by microinjection of sodium glutamate (0.5 M, 100-200 nl) into the pressor, depressor, or vagobradycardiac areas of the brain stem. Stimulation of these CV-reactive areas increased or decreased UB motility. Areas that produced an increase in UB motility listed in decreasing order of effectiveness are locus ceruleus-parabrachial nucleus in the pons, dorsal medulla, dorsal motor nucleus of vagus, and ventrolateral medulla. Areas eliciting a decrease in UB motility listed in decreasing order are gigantocellular tegmental field, parvocellular reticular nucleus, and ambiguus nucleus. Stimulation of other pressor sites in medulla also increased UB motility. Activation of the paramedian reticular nucleus, which consistently produced depressor responses, and activation of raphe nuclei, which produced depressor or pressor responses, consistently decreased UB motility. The integrity of the vagus nerve was not essential for the UB response to brain stimulation. These findings indicate that neuronal mechanisms for controlling UB and CV functions coexist at many sites in the brain stem. At those sites that commonly produce changes in UB motility, the type of UB response (excitation or inhibition) was in the same direction as the change of SAP. However, at some sites responses were inverse. It is not known whether the responses of the UB and CV system are controlled by common or separate populations of neurons at these sites.

Animals↗
PubMed1993

Study of the hemodynamic contributing factors of spontaneously hypertensive rats in the early stage of established hypertension.

The neural and nonneural factors contributing to maintain the hemodynamic status in 14 to 16 weeks old stroke prone spontaneously hypertensive rats (SHRSP) and spontaneously hypertensive rats (SHR) were compared with those of the age matched normotensive Wistar Kyoto (WKY) rats under chloralose-urethane anesthesia. The ascending aortic blood flow, arterial blood pressure and heart rate were measured under resting condition, ganglionic blockade by hexamethonium, 5 mg/kg i.v. and maximum vasodilation by hexamethonium and 0.07 mg/kg nitroprusside. The neural component (hexamethonium blockable component) was the major factor in the maintenance of resting blood pressure and total peripheral resistance index (TPRI) in the above three strains of rats. In contrast, the residual component after hexamethonium and nitroprusside administrations was the most important controlling factor for cardiac index (CI). In SHRSPs, the neural component of TPRI and residual component of CI were both significantly higher than those of WKYs by 75% and 47%, respectively. In SHRs, the residual component of CI was 52% higher than that of WKYs. These results suggest that both the increased neural component of TPRI and nonneural component of CI are important contributing factors for the blood pressure increase in the early stage of established hypertension in SHRSPs. On the other hand, in the age matched SHRs, the most important contributing factor for hypertension is the increased nonneural component of CI. Considering the differences between these two strains of hypertensive rats, the neural component of TPRI is the major factor responsible for the different levels of hypertension in SHRSPs and SHRs.

Animals↗
PubMed1993

Angiotensinogen mRNA and pressor reactions to angiotensin in brain stem areas of spontaneously hypertensive rats.

The role of angiotensin (ANG II) at the tissue level, particularly in the brain, remains imperfectly defined. We measured angiotensinogen (A degrees) mRNA in the brain stems, sensory and sympathetic ganglia, and blood vessels of Wistar-Kyoto (WKY) and stroke-prone spontaneously hypertensive rats (SHR-SP) by quantitative, liquid hybridization. We micro-injected ANG II and glutamate into the brain stems of these rats to gain insight into the functional significance of our findings. A. mRNA was found in the dorsolateral, dorsomedial, and ventrolateral pons, as well as in the dorsolateral, dorsomedial, and ventrolateral medulla of both strains. A degrees mRNA was 8-10 pg/micrograms total mRNA higher (p < 0.05) in the dorsomedial medulla (nucleus tractus solitarii) in WKY and SHR-SP (28.27 +/- 1.26 and 33.50 +/- 1.42 pg/micrograms RNA respectively) than in the other areas. SHR-SP had higher values (27.22 +/- 1.77 vs. 21.53 +/- 0.57 pg/micrograms mRNA) than WKY (p < 0.05) in the dorsolateral pons (locus coeruleus). A. mRNA was also identified in the optic nerves and chiasm, trigeminal and coeliac ganglia, arteries and veins. Injections of glutamate and ANG II into the dorsomedial, dorsolateral, and ventrolateral medulla increased blood pressure, while ANG II in the dorsal medial pons did not. We conclude that A degrees mRNA is produced to different degrees in brain stem areas which participate in blood pressure regulation. Medullary structures show more response to local ANG II than pontine structures. A degrees mRNA is located in sensory neural tissues as well as sympathetic ganglia. A degrees mRNA is present in both arteries and veins. These findings underscore the scope and complexity of ANG production in tissues.

Angiotensin II↗
PubMed1993

Leiomyosarcoma, leiomyomatosis in von Recklinghausen's disease: report of case.

A 48-year-old female patient with von Recklinghausen's disease was admitted to Kaohsiung Medical College Hospital due to massive hematochezia. The emergent mesentery arteriography revealed multiple hypervascular small intestinal lesions but no contrast extravasation. The endoscopic examination revealed a blood-filled small intestine with normal colonic mucosa. Laparotomy was carried out and multiple extraluminal masses on antimesenteric side of the small intestine were found. Segmental resection of the small intestine resulted in resolution of her symptom. The largest mass was diagnosed as leiomyosarcoma, and the others were diagnosed as leiomyoma. Histologically, differential diagnosis between leiomyosarcoma and leiomyoma is not clear cut, because it is based on a number of differentiating features. Surgical resection is the treatment of choice for intestinal leiomyosarcoma. The long-term follow-up of this patient is mandatory.

Diagnosis, Differential↗
PubMed1993

Holoprosencephaly and trisomy 13 in a fetus with maternal early gestational amphetamine abuse--a case report.

We report a congenital anomalous fetus with holoprosencephaly, prenatally diagnosed by sonography and MR scan at the twenty-sixth week during the gestational period. Chromosome analysis by amniocentesis revealed trisomy 13 (47,XY,+13). The diagnosis was confirmed by autopsy. After induction, external examination showed a proboscis-like nose on the normal nose position. The right foot showed polydactylia with wide separation of the fifth and sixth toes. We found that the mother was an abuser of amphetamine at an early gestational age. The teratogenic effect of D-amphetamine on animals has been noted, but no previous clinical case of a congenital anomalous fetus and maternal abuse of amphetamine has been reported. This case report is the first to reveal holoprosencephaly and trisomy 13, with maternal early gestational abuse of amphetamine.

Abnormalities, Drug-Induced↗
PubMed1993

Neurons in the pressor sites of dorsal and ventrolateral medulla mediate pressor actions of the periaqueductal grey of midbrain.

In 14 cats anesthetized with chloralose (40 mg/kg) and urethane (400 mg/kg) the pressor area in the ventrolateral periaqueductal grey (PAG) of midbrain was activated by rectangular pulses. The induced increases of systemic arterial pressure (SAP) and plasma norepinephrine (NE) and epinephrine (EPi) were compared before and after destructing portion of cell bodies (sparing passing fibers) in the pressor sites of dorsal (DM) and rostral ventrolateral medulla (VLM) by microinjection of kainic acid. Destruction on VLM or DM reduced the PAG-induced pressor responses and increases in plasma NE and EPi. The reduction of pressor responses, however, was more predominant following VLM than DM destruction. On the other hand, the decrease in plasma NE, was slightly more apparent following DM than VLM destruction.

Animals↗
PubMed1993

Effects of reducing sympathetic activities on acute myocardial ischemia in cats.

The importance of the sympathetic nervous system in the genesis of ventricular arrhythmias associated with acute myocardial ischemia (AMI) was assessed in urethane-chloralose anesthetized cats. AMI was created by a ligation of the left anterior descending coronary artery. All control cats developed ventricular tachyarrhythmia (VT), ventricular fibrillation (VF), bradycardia and hypotension, resulting in 50% mortality. In other groups the paramedian reticular nucleus (PRN) was intermittently stimulated to inhibit the sympathetic nervous system. Both sides of the stellate ganglia (SG) or adrenal glands (AG) were removed to exclude direct effects of cardiac sympathetic nerve or indirect effects of circulatory catecholamines from the adrenal medulla on the heart, respectively. AMI did not affect plasma norepinephrine (NE) and epinephrine (EPI) concentrations in all groups. However, NE concentration was higher in SG removed but lower in AG removed group. Removal of SG and stimulation of PRN significantly reduced arrhythmia score and the incidence of VT, VF and mortality. Removal of AG appeared to be less effective. These findings suggest that cardiac sympathetic innervation is more important than neural and adrenal catecholamine secretions in the plasma.

Acute Disease↗