Expression and mutation analysis of the p53 gene in astrocytoma

The role of p53 gene mutations in the formation or progression of human astrocytic tumors is controversial. We studied the distribution pattern of p53 immunoreactivity and analyzed p53 gene mutations to define the significance of p53 gene mutations in astrocytoma tumorigenesis or malignant progression. Twenty-three astrocytic tumors were evaluated with immunohistochemistry, single-strand conformation polymorphism (SSCP) analysis, and sequence analysis. We also searched MEDLINE to collect data on p53 gene mutation frequencies in astrocytic tumors in order to evaluate the association of p53 mutations and tumor grade. Strong immunoreactivity with a diffuse clustering pattern was found in three of five glioblastomas and seven of 12 anaplastic astrocytomas. Three of four low-grade astrocytomas were immunonegative. The p53 immunopositive cells in the only positively staining low-grade astrocytoma in our study appeared sparsely scattered. The results of immunostaining suggested that clonal expansion was associated with astrocytoma progression. Mutations of the p53 gene were detected in four of the 23 astrocytomas (one glioblastoma and three anaplastic astrocytomas). In the genetic data analysis, 76 of 367 astrocytomas had p53 gene mutations. A significantly greater p53 gene mutation frequency was found in anaplastic astrocytomas or glioblastomas than in the low-grade astrocytomas. The results of these immunohistochemical and genetic studies support the view that p53 gene mutation is associated with the malignant progression from low-grade to high-grade astrocytomas rather than with tumor initiation or promotion.

Hypothalamic juvenile pilocytic astrocytoma presenting with intracerebral hemorrhage

Hemorrhage of juvenile pilocytic astrocytomas is very rare. However, it is clinically important because a high probability of a fatal outcome exists if hemorrhage occurs outside the optic nerve. Hemorrhage of a hypothalamic juvenile pilocytic astrocytoma has been reported only once, from an autopsy examination. We present a successfully managed case. The patient, a 34-year-old man, presented with sudden loss of consciousness. Computed tomography (CT) and magnetic resonance imaging demonstrated an exophytic hypothalamic tumor with a hemorrhage. Craniotomy with total removal of the tumor and the hematoma was performed. Histopathologic examination revealed that the tumor was a juvenile pilocytic astrocytoma. Brain CT examination 18 months later revealed no evidence of tumor recurrence. The patient was well, without neurologic deficit, and had a normal social life as of the last follow-up examination 22 months after craniotomy.

Corticotrophin-releasing factor produces a long-lasting enhancement of synaptic efficacy in the hippocampus

We have previously demonstrated that intra-hippocampal injection of corticotrophin-releasing factor improved memory retention of an inhibitory avoidance learning in rats; while the electrophysiological effects corticotrophin-releasing factor produces on hippocampal neurons are largely uncharacterized. In the present study, we found that corticotrophin-releasing factor injected into the dentate gyrus of hippocampus produced a dose-dependent and long-lasting enhancement in synaptic efficacy of these neurons, as measured by an increase in the amplitude and slope of population excitatory postsynaptic potentials, as well as the amplitude of population spike. The onset of corticotrophin-releasing factor-induced potentiation was slow. It was observed approximately 40-60 min after corticotrophin-releasing factor administration and lasted for more than 5 h. This effect of corticotrophin-releasing factor was blocked by pretreatment with the cyclase-adenosine-3,5-monophosphate (cAMP) inhibitor Rp-adenosine-3,5-cyclic monophosphothiolate triethylamine (Rp-cAMPS) and partially blocked by the N-methyl-D-aspartate receptor antagonist MK-801. Further, pretreatment with corticotrophin-releasing factor receptor antagonist dose-dependently diminished tetanization-induced long-term potentiation, and corticotrophin-releasing factor and tetanic stimuli had an additive effect on hippocampal neuron excitation. Moreover, direct injection of corticotrophin-releasing factor increased cAMP level in the dentate gyrus. These results together suggest that corticotrophin-releasing factor-induced potentiation simulates the late phase of tetanization-induced long-term potentiation and cAMP seems to be the messenger mediating this effect. Moreover, corticotrophin-releasing factor-induced potentiation and long-term potentiation may share some similar mechanisms, and corticotrophin-releasing factor is probably involved in the neural circuits underlying long-term potentiation. Thus, corticotrophin-releasing factor may play an important role in modulating synaptic plasticity in the hippocampus.

Expression of bcl-2, p53 and Ki-67 in arsenical skin cancers

To investigate the regulation of apoptosis and proliferation in arsenic-induced skin cancers, we examined the expression of bcl-2, p53, and Ki-67 using immunohistochemical staining. Thirty patients with Bowen's disease (BD), ten with basal cell carcinoma (BCC), eight with squamous cell carcinoma (SCC) and eleven of perilesional normal skin (PLN) of the non-sun exposure sites from endemic area were examined. The results showed that: 1) bcl-2 was expressed in all of the BCC homogeneously, in none of the SCC, and in 12/30 of the BD focally or homogeneously; 2) p53 was expressed in all of the arsenical skin cancers with a labelling index of 75 +/- 14% of BD, 50 +/- 17% of BCC, 61 +/- 15% of SCC, and also in all of the perilesional normal skin with a labelling index of 55 +/- 24%; 3) Ki-67 was expressed in all of the skin cancers with labelling index of 58 +/- 17% of BD, 12 +/- 7% of BCC, 47 +/- 21% of SCC, and in 9/11 of PLN with a labelling index of 41 +/- 24%. Expression of bcl-2 in BCC or BD is related to the phenotype of germinative basal cell. The constant expression of bcl-2 i early dysplastic cells of BD and the earliest expression of P53 in the basal cells of perilesional normal skin indicate that the initial step of arsenic-induced carcinogenesis is from the basal germinative cells. There is no mutual relationship between bcl-2, p53 or Ki-67 expression in any type of the arsenical skin cancers, but there is a positive correlation between p53 and Ki-67 expression identified in perilesional normal skin. BD had the highest labelling index of p53 and Ki-67.

Prognostic evaluation in supratentorial astrocytic tumors using p53, epidermal growth factor receptor, c-erbB-2 immunostaining

Molecular pathology may play an important role in predicting the tumor prognosis, particularly p53, epidermal growth factor receptor (EGFR), and c-erbB-2. We investigated six variables (age, sex, histopathological grade, p53, EGFR, and c-erbB-2) to identify the role of such factors in predicting the outcome of patients with supratentorial astrocytic tumors. Thirty-seven tumors were studied including 9 well-differentiated astrocytomas (WHO grade 2), 19 anaplastic astrocytomas (WHO grade 3), and 9 glioblastomas multiforme (WHO grade 4). In univariate analysis, no statistical significance was found for the prognostic value of the sex (p = 0.2188), age (p = 0.5530), p53 immunostain (p = 0.2194), and c-erbB-2 immunostain (p = 0.4203). A significant correlation with the prognosis was found with respect to the histopathological grade (p = 0.0049) and EGFR expression (p = 0.0284). In multivariate analysis, the histopathological grade was shown to be significant independent variable (p = 0.0152). In WHO grade 2 and 3 astrocytomas, expression of p53 or EGFR was associated with poorer patient outcome. In glioblastomas, expression of p53 was also associated with poorer prognosis. Our studies suggested that conventional histological assessment of supratentorial astrocytic tumors remains the best guide to prognosis. Although no statistical significance was found between the immunostains and survival in variant grades of astrocytomas, there was a trend between p53 or EGFR proteins expression and the decrease of survival time.

A single minute lesion around the ventral respiratory group in medulla produces fatal apnea in cats

In 35 adult cats anesthetized with intraperitoneal chloralose and urethane, the ventrolateral medulla was explored by microinjection of kainic acid (KA, 24 mM, 200 nl) with metal electrode-tubing or glass micropipette to determine regions which elicit persistent apnea. Persistent apnea is defined as: (1) In spontaneously breathing cats, termination of respiration over 3 min with a decrease of the mean systemic arterial pressure (MSAP) to 25 mm Hg. (2) In animals under artificial ventilation and paralyzed by gallamine, cessation of bilateral phrenic nerve (PNA) activities over 25 min. The apnea producing area was located dorsal to the rostral pole of the lateral reticular nucleus, ventromedial to the ambiguous nucleus and immediately caudal to the retrofacial nucleus. Functionally, this region includes the rostral part of the ventral respiratory group (rVRG) encompassing the pre-BOtzinger area. We define this region as the VRG apnea producing area (VRG-Apa). Fatal apneusis was observed under following conditions: (1) Persistent apnea was produced after a single KA microinjection in one side of the VRG-Apa (5 animals). Microinjection of sodium glutamate (0.25 M, 70-200 nl) in the same area produced only brief apnea, while microinjection of kynurenic acid (0.1 M, 200 nl) showed little effect on the respiration but slightly increased the SAP. (2) Positioning an electrode nearby but not in the VRG-Apa with or without KA injection did not produce apnea. But when a second electrode insertion to the opposite VRG-Apa immediately produced persistent apnea even without KA injection (6 animals). (3) Midsagittal division of the medulla 0-5 mm rostral to the obex produced persistent silence of PNA on both sides in artificial ventilated animals (7 animals), while similar division 0-5 mm caudal to the obex (4 animals) produced a brief but reversible quiescence of PNA. In conclusion, findings of the present study support the existence of a restricted region of VRG-Apa. VRG-Apa on both sides are closely connected, and integrity of both VRG-Apa is essential for normal respiration.

Contralateral recurrent cerebellar hemangioblastoma--a case report

Hemangioblastomas are regarded as benign neoplasms. They may recur in 3 to 10% of cases after apparently total excision. The opposite site recurrence is not found in the reported literature. A case is described in which, after successful removal of a cerebellar hemangioblastoma followed by two years of freedom from symptoms, developed a new growth of cerebellar hemangioblastoma contralaterally again. The histology of the tumor tissue is in no way different from that of a conventional hemangioblastoma. This case gives us some insights into the biological multipotentiality of cerebellar hemangioblastoma. We stress that close observation is absolutely necessary for this unique group of tumors, even after total removal.

The role of CD8+ cells and CD11a in the rejection-reaction of the allogeneic microskin grafting

By using histological tissue sections and immunohistochemical stains, the rejection-reaction of the allogeneic microskin grafting of rabbit-skin wounds was studied. The results revealed that the rejection started early in the days following transplantation. In the second week following transplantation, severe graft rejection with epithelial destruction was noted. In addition, an increase of CD8+ cells and expression of the adhesion molecule-CD11a-were also noticed and persisted throughout the days following transplantation. These findings suggest that the CD8+ cells and CD11a may play a major role in the rejection of allogeneic skin grafting.

Role of dopamine uptake in NMDA-modulated K(+)-evoked dopamine overflow in rat striatum: an in vivo electrochemical study

An involvement of dopamine uptake in the N-methyl-D-aspartate (NMDA)-modulated dopaminergic transmission in rat striatum was studied using the technique of in vivo electrochemical detection. Microinjection of potassium (K+) evoked dopamine overflows from the dopamine-containing nerve terminals in the striatum. While application of NMDA did not evoke any dopamine overflow, co-application of NMDA and K+ induced larger dopamine overflows than those by K+ alone. Furthermore, dynamic analysis showed that the rate of clearance (Tc) was reduced by NMDA. Indeed, our uptake study demonstrated an NMDA-induced inhibition of dopamine clearance. The time course of electrochemical signals evoked by microinjection of exogenous dopamine was increased and Tc was reduced following NMDA application. In order to delineate the effects of NMDA on K(+)-evoked dopamine overflows and/or on dopamine uptake, nomifensine, a dopamine uptake inhibitor was used. Application of nomifensine potentiated K(+)-evoked dopamine overflows. Co-administration of NMDA further augmented dopamine overflows by the K+ and nomifensine mixture. Taken together, our data suggest that NMDA concomitantly potentiated dopamine overflows in response to depolarizing stimuli and attenuated dopamine uptake. The increment by NMDA of K(+)-evoked dopamine overflows may partially result from an attenuated dopamine uptake in rat striatum.

Attenuation of cardiac but not vascular component in baroreflex of spontaneously hypertensive rats

The cardiac and vascular components of the baroreceptor reflex in spontaneously hypertensive rat (SHR) and stroke-prone spontaneously hypertensive rat (SHRSP) were compared against their counterparts in normotensive Wistar Kyoto rat (WKY). SHR, SHRSP and WKY of 12-16 weeks old were chronically instrumented for intra-arterial recording of blood pressure. Intravenous injections of phenylephrine and nitroprusside were used to challenge their baroreflex. The products of blood pressure change and the half time required for the pressure to return to the control value were used as the quantitative estimation of the blood pressure stabilizing capability. The cardiac component of the baroreflex was obtained from the change in the blood pressure stabilizing capability after blockade of beta and muscarinic receptors by atenolol and atropine, respectively. The vascular component was obtained by subtracting the cardiac component from the total stabilizing capability which was the difference after blockade with a ganglionic transmission blocker, hexamethonium. We found the cardiac component of the baroreflex of the hypertensive rats was significantly less sensitive than that of the WKY. In contrast, the vascular component of the baroreflex of the three strains did not differ significantly. Therefore, we concluded that the 12-16 week old SHRs were able to maintain a stable blood pressure due to the intact vascular component of the baroreflex.

Spike responses of sympathetic vertebral nerve activities during stimulation of the pressor dorsomedial and rostral ventrolateral medulla differ in cats

In this study, we developed a differential integrator unit containing a window discriminator (WPI-121) and three integrators (sample/hold, Gould) to characterize the difference in spikes involved in sympathetic vertebral nerve activity (VNA) and integrated VNA (Int. VNA) during stimulation of the dorsomedial (DM) and rostral ventrolateral (RVLM) medullar. The upper level (UL) in the window discriminator was set at a value, 80% of the VNA amplitude above the zero. The low level (LL) was set at a value 10% above the zero. The number of VNA spikes above the UL in the window discriminator was defined as Fa, while the number of VNA spikes within the UL and LL as Fw. In 26 cats anesthetized with urethane and alpha-chloralose, results showed that electrical stimulation and microinjections of glutamate (Glu, 0.25 M, 50 nl) or glycine (Gly, 1.0 M, 50 nl) at the same point in DM or RVLM increased both systemic arterial pressure (SAP) and Int. VNA. However, the increase of Int.VNA on DM stimulation was contributed by increases of both Fa and Fw, while on RVLM stimulation the increase of Int.VNA was mainly contributed by the increase of Fa, against a decrease of Fw. As compared to Glu, stimulation of DM by Gly produced more increase in Fw, while stimulation of RVLM by Gly produced more decrease in Fw. During RVLM stimulation the VNA was usually transferred to a huge synchronized oscillation. These findings suggest that although stimulations of the sympathetic-pressor neurons in DM and RVLM produce similar increases in SAP and VNA, the nature of these neurons is different.

GABAergic inhibition of neonatal rat phrenic motoneurons

Phrenic motoneurons (PMNs) receive intermittently glutaminergic inspiratory drives and GABAergic inhibition in adult mammals. Since gamma-amino-butyric acid (GABA) might act as an excitatory amino acid in early stages of development, we here investigated if GABA(A) receptors inhibit PMNs in neonates. Using in vitro neonatal rat brainstem-spinal cord preparation, local application of GABA and muscimol (a GABA(A) receptor agonist) to the vicinity of PMNs consistently reduced the inspiratory activity of C4 ventral roots. Under whole-cell patch-clamp conditions and in the presence of 0.5 microM TTX to block synaptic transmission, muscimol (10 microM) decreased whole-cell input resistance, and surprisingly, when PMNs were voltage-clamped at their resting membrane potential, muscimol induced depolarizing-inward, rather than hyperpolarizing-outward membrane current. Our findings indicate that GABA(A) receptors mediate a depolarizing blockade of the glutaminergic excitatory inputs to neonatal rat PMNs.

The depressor caudal ventrolateral medulla: its correlation with the pressor dorsomedial and ventrolateral medulla and the depressor paramedian reticular nucleus

The functional correlation of the depressor caudal ventrolateral medulla (CVLM) with the two pressor regions, i.e. rostral ventrolateral medulla (RVLM) and dorsomedial medulla (DM), and with another inhibitory region, i.e. the paramedian reticular nucleus (PRN), were studied in cats anesthetized intraperitoneally with chloralose (40 mg/kg) and urethane (400 mg/kg). Systemic arterial pressure (SAP), heart rate (HR) and the sympathetic vertebral nerve activity (VNA) were recorded. The correct location of CVLM, RVLM or DM was determined by their specific responses, i.e. decreases of SAP, HR and VNA, for CVLM increases of these parameters for RVLM and DM, elicited first by electrical stimulation (80 Hz, 0.5 ms, 50-100 microA) then followed by microinjection of glutamate (Glu, 0.25 M, 70 nl). The depressor action of PRN was produced by electrical stimulation only. It was found that the depressor responses caused by the CVLM stimulation were greatly reduced 2 h after lesioning either the RVLM or DM by microinjection of kainic acid (KA, 24 mM, 200 nl) ipsilateral to the side of CVLM stimulation. The CVLM responses were further reduced after the remaining side of RVLM or DM was lesioned. The reduction of the CVLM-depressor responses was more apparent after the RVLM than DM lesioning. Data suggest that the CVLM-depressor responses are mediated through inhibition of the sympathetic-pressor neurons in both RVLM and DM with predominance of the former. Lesioning the PRN by KA and/or combination with DC electrolytic lesion reduced the CVLM-induced depressor responses. In turn, lesioning the CVLM by KA reduced the PRN-induced depressor responses. The reduction in the later manipulation was more apparent in the PRN-depressor responses than the CVLM-depressor responses. Data suggest that part of the PRN depressor action is mediated through activation of the CVLM.

Vagal innervation of the gastrointestinal tract arises from dorsal motor nucleus while that of the heart largely from nucleus ambiguus in the cat

The origin of medullary cells that form the cardiac vagal branch and the vagal branches in the lower thorax innervating the gastrointestinal (GI) tract was studied using horseradish peroxidase (HRP), a retrograde transport tracer in the cat. The distributions of parasympathetic postganglionic neurons of the heart were studied with acetylcholinesterase histochemistry. Intracardiac ganglionic neurons were found mainly in the connective tissue surrounding the base of the pulmonary arteries and in an area in and dorsal to the interatrial septum. Following injection of HRP into the subepicardum where most of the cardiac postganglionic neurons reside, 91% of the labelled neurons were found bilaterally distributed in the nucleus ambiguus (NA). A small population of labelled neurons was found in the dorsal motor nucleus of the vagus (DMV) and an intermediate zone (IZ) between the two nuclei. When HRP was injected into the left or right cardiopulmonary vagus branch, labelled neurons were found exclusively in the ipsilateral NA, DMV and IZ with a predominance in the NA. In the thorax, after they course around the heart, the left and right thoracic vagus nerves divides into a left and a right branch, respectively. The left branch of the left thoracic vagus joins the left branch of the right thoracic vagus to form the anterior vagus nerve at 3 cm above the diaphragm. The right branch of the right thoracic vagus nerve joins the right branch of the left thoracic vagus to form the posterior vagus nerve. After application of HRP into the right or the left branch of the left thoracic vagus, HRP labelled cells were found in the left DMV. Similarly, after application of HRP into the left or the right branch of the right thoracic vagus, labelled cells were found in the right DMV. On the other hand, when HRP was injected into the anterior vagus, labelled neurons were found bilaterally in the DMV. This suggests that all rostral branches of the thoracic vagus have their origin in the ipsilateral DMV, and intermixing occurs only at the caudal level near the diaphragm. Findings of the present experiments suggest that parasympathetic preganglionic neurons innervating the GI tract are located exclusively in the DMV while those of the heart are located mainly in the NA. Within the DMV, GI vagal neurons were found medially from the level 0-2.5 mm rostral to the obex. In contrast, cardiac vagal neurons were found in the lateral edge of the DMV at the level 0-1 mm rostral to the obex.

Radiation-induced muscle damage in rats after fractionated high-dose irradiation

Muscle damage in the legs of male Wistar rats after exposure to high-dose radiation was evaluated by observations of biopsied tissue made with light and transmission electron microscopy. Both legs of about 40 mature male Wistar rats were exposed to 80 Gy 6 MV X rays from a linear accelerator given in 40 fractions of 2 Gy. At intervals starting from the first day to 12 months after irradiation, serial muscle biopsies were obtained by sacrificing the rats on different days according to the experimental design. The irradiated gastrocnemius muscle displayed a progressive structural change that began immediately after the completion of the exposures. Morphological changes in irradiated muscles were characterized by hemorrhage, lymphocytic infiltration and obvious vascular destruction. Increased amounts of collagen between the muscle fibers were present even at 12 months after irradiation. There were significant changes in the number, size and structure of mitochondria in the muscle cells from the first day until 1 year after irradiation. Even 12 months after the final exposure, no recovery of muscle tissue was seen by light and transmission electron microscopy.

Striatal dopamine dynamics are altered following an intranigral infusion of iron in adult rats

In vivo electrochemical detection was employed to examine iron-induced oxidative injury on dopamine dynamics in the nigrostriatal system of urethane-anesthetized rats. Seven days after an intranigral infusion of iron, oxidative stress was confirmed by an elevated lipid peroxidation in lesioned substantia nigra (SN). Local application of potassium (K+) evoked dopamine releases from the dopamine-containing nerve terminals in the striatum. Both amplitude and rate of clearance (Tc) of evoked dopamine releases were lower in striatum with lesioned SN; however, the time course parameters of dopamine release in the lesioned group were not different from those of the intact group, indicating a reduction in dopamine clearance. Indeed, iron-induced oxidative stress attenuated the effect of nomifensine, a high-affinity dopamine uptake blocker, on dopamine clearance. In striatum with intact SN, the amplitude and time course parameters of signals by exogenous dopamine were increased and Tc was decreased by nomifensine. In contrast, nomifensine did not significantly alter the dopamine signals of the lesioned group. Taken together, in addition to the increased lipid peroxidation in SN, our in vivo electrochemical data demonstrates that iron-induced oxidative injury attenuates K+-evoked dopamine release and dopamine uptake in the ipsilateral striatum. The diminished nomifensine effect implies a lack of high-affinity dopamine uptake sites.

Prostatic carcinoma with brain metastasis presenting as a tumor hemorrhage

Adenocarcinoma of the prostate commonly metastasizes to the lymph nodes and bones, with occasional visceral deposits, however, metastasis to the brain is rare. A case of prostatic carcinoma with brain metastasis presenting as a tumor hemorrhage is reported. The pertinent literature is also reviewed.

Glycine increases arterial pressure and augments NMDA-induced pressor responses in the dorsomedial and ventrolateral medulla of cats

The present study is designed to determine and characterize two neurobiological events. Firstly, we investigated whether increases of systemic arterial pressure (SAP) and sympathetic vertebral nerve activity (VNA) produced by microinjection of glycine (Gly) in the dorsomedial (DM) or rostral ventrolateral medulla (RVLM) are mediated by pressor neurons in DM or RVLM. Secondly, we assessed whether simultaneous microinjections of Gly and N-methyl-D-aspartate (NMDA) in DM or RVLM potentiate the NMDA-pressor effects. Changes in SAP and VNA were recorded in 33 cats under alpha-chloralose and urethane anesthesia. Microinjection of sodium glutamate (Glu, 0.25 M, 30 nl) or Gly (1.0 M, 30 nl) into the DM or RVLM increased SAP and VNA in similar magnitude. Latencies of changes in SAP and VNA induced by Gly, however, were longer (3 s) than those induced by Glu. Prior microinjection of the following antagonists blocked the Gly-induced pressor responses: 2-amino-5-phosphonopentanoate (AP-5, 25 mM, 30 nl), a specific NMDA receptor antagonist; or glutamate diethyl ester (GDEE, 0.5 M, 30 nl), a quisqualate receptor antagonist; or kynurenic acid (KYN, 10 mM, 30 nl), a broad spectrum competitive Glu antagonist. Prior treatment with strychnine (3 mM, 30 nl), a specific Gly antagonist, also blocked the Gly-induced pressor responses. Since Gly is believed to be an inhibitory neurotransmitter, these data suggest that Gly may produce pressor actions via an inhibition on specific inhibitory neurons synapsing with the pressor neurons. NMDA (0.1 M, 30 nl) and Gly (1.0 M, 30 nl) microinjected simultaneously in DM or RVLM produced a greater pressor action than NMDA alone. This potentiation was blocked by KYN, another known antagonist for such potentiation, but was only partially blocked by strychnine.

The role of mucopolysaccharide induction in treatment of experimental osteoarthritis in rats by ultrasound

Therapeutic ultrasound has been used in the treatment of osteoarthritis for the relief of symptom and improvement of functional status. In recent study, we found that ultrasound enhances cartilage repair in experimental early stage osteoarthritis, and prevents deteriorative changes in later stages. In the present study, we further investigate the bioeffects of ultrasound on cartilage matrix of experimental arthritis. Fifty-four rats with three different degrees of papain induced osteoarthritis classified by 99m-Tc pertechnetate bone scan were collected for ultrasound treatment. The changes in their arthritic severity after sonication treatment and two months after treatment were measured using 99m-Tc bone scan. The histopathological changes were evaluated through light microscope after disarticulation sections (H.E. stain), and the changes in mucopolysaccharide density in cartilage matrix were measured using a Optimas scanner analyzer after Alcian blue staining. The results showed that the density of mucopolysaccharide rose in the initial stage of induced arthritis, and decreased progressively in the later stage. The density of mucopolysaccharide increased upon complete sonication more for the treated rats than for the controls, and this was closely related with the improvement in histopathological findings, but inversely with the changes in arthritic severity. In conclusion, therapeutic ultrasound enhances mucopolysaccharide synthesis of arthritic cartilage, and results in the repair of arthritic cartilage in the early stage of induced arthritis and the prevention of deteriorative changes in later stages.

Effects of sonication on articular cartilage in experimental osteoarthritis

OBJECTIVE

To investigate the histological effect of therapeutic ultrasound on arthritic cartilage of rats with various severities of induced osteoarthritis.

METHODS

Twenty-seven rats with 3 different stages (Grade I, II, III) of papain induced knee arthritis received 7 min pulse sonication treatment, 3 times/week for 4 weeks. Another 27 rats with the same severity of induced arthritis were studied as controls. The severity of arthritis and related histopathological changes of articular cartilage were evaluated by bone scan and histological findings with hematoxylin and eosin stain.

RESULTS

"Severity indexes" based on bone scan decreased after sonication treatment in each study group. Histopathological findings indicated marked cartilage repair in the early stage of induced arthritis (Grade I). However, progressive cartilage damage present in untreated Grade II, III induced arthritis was significantly reduced after sonication.

CONCLUSION

Therapeutic ultrasound enhances cartilage repair in the early stage, and has the effect of arresting further deteriorative damage in the later stage of induced arthritis.

Expression of epidermal growth factor receptors and c-erbB-2 proteins in human astrocytic tumors

Tumorigenesis is the result of sequential or multiple genetic alterations. The overexpression or amplification of various oncogenes in diverse human brain tumors have been observed. While numerous studies on the immunohistochemical demonstration of EGFR-overexpression have been reported, little has been found in the literature about the c-erbB-2 protein in human astrocytic tumors. In the present study, we evaluated the expression of EGFR and c-erbB-2 protein in 33 astrocytic tumors with immunohistochemistry. According to the World Health Organization brain tumor classification, the study included 9 low-grade astrocytomas (grade 2), 15 anaplastic astrocytomas (grade 3), and 9 glioblastomas multiforme (grade 4). The positive EGFR immunoreactivity was detected in 28 (85%) of 33 tumors. The expression of EGFR increased with the grade of malignancy in low-grade astrocytomas (67%), anaplastic astrocytomas (87%), and glioblastomas (100%). For the expression of c-erbB-2 protein, 17 (51.5%) of 33 tumors were positive immunostain, including 3 low-grade astrocytomas (37.5%), 9 anaplastic astrocytomas (81.8%), and 5 glioblastomas (62.5%). Different degrees of immunoreactivity for c-erbB-2 protein were found in variant grades of astrocytomas. However, the positive immunostain of EGFR displayed moderate or strong reactivity. The coexpression of EGFR and c-erbB-2 protein was found in 17 (15.5%) of 33 tumors. The results emphasize that the overexpression of EGFR parallels astrocytoma progession and higher frequency of c-erbB-2 immunoreactivity was seen in snaplastic astrocytomas and glioblastomas than in low-grade astrocytomas.

Propofol inhibits medullary pressor mechanisms in cats

PURPOSE

Propofol may cause hypotension and the mechanism is complex. The present study was designed to determine the direct actions of propofol in medulla of cats.

METHODS

Mean systematic arterial pressure (MSAP), heart rate (HR) and cardiac contractility (dp/dt) were compared before and after administration of propofol the femoral vein (2, 3, or 4 mg.kg-1), vertebral artery (1 mg.kg-1) or the lateral cerebral ventricle (0.5 mg.kg-1) in eight anaesthetized cats. To study the direct effect of propofol in medulla, pressor areas of the dorsomedial medulla (DM) and rostral ventrolateral medulla (RVLM), or the depressor area of the caudal ventrolateral medulla (CVLM) were first identified with electrical stimuli and then confirmed by pressure microinjection of glutamate (Glu, 0.25M, 30 nl) via a multibarrel-micropipette in 28 cats. One hour later, propofol (0.001%, 50 nl) was microinjected at the same site. Electrical stimulation and Glu were applied again to compare changes of SAP, HR and dp/dt with that of the control.

RESULTS

Propofol dose-dependently decreased SAP, HR and cardiac contractility. The percent increase of MSAP induced by Glu were reduced by propofol in DM (59 +/- 3% vs 13 +/- 2%, n = 11, P < 0.01) or in RVLM (56 +/- 4% vs 18 +/- 2%, n = 9, P < 0.01). In CVLM, propofol slightly but not significantly increased depressor responses elicited by Glu (-27 +/- 2% vs -33 +/- 3%, n = 5, P > 0.05).

CONCLUSION

Our results show that propofol principally inhibits the vasomotor mechanism in the dorsomedial and ventrolateral medulla to effect its hypotensive actions.

Paramedian reticular nucleus may be unrelated to the development of hypertension in spontaneously hypertensive rats

The role of paramedian reticular nucleus (PRN), a structure effecting sympathetic inhibition, in the development of hypertension was investigated in young spontaneously hypertensive rats (SHR) and two age-matched normotensive rats, Wistar-Kyoto (WKY) and Sprague-Dawley rats (SD). Three different experimental manipulations, including electrical-lesioning, sham-operated and intact control, were performed in SHR, WKY and SD rats 7 weeks after birth. In the control groups, the systolic arterial blood pressure (SABP) of SHR increased abruptly from 160 mmHg to 230 mmHg from the 6th to 13th week after birth, whereas those of WKY and SD maintained a normal range of SABP. In the lesioned groups, a hypotension and/or bradycardia was evoked by electrical stimulation to verify the location of PRN. Following the verification, a direct current was delivered to lesion the PRN in situ. The effect of PRN lesioning on the subsequent development of hypertension was illustrated by comparing SABP in three experimental groups of age-matched conscious SHR, WKY and SD during 8-13 weeks after birth. We found that the average SABP in the lesioned SHR was consistently elevated and was not significantly different from those of the sham-operated and the control. In contrast, in the normotensive rats, there was no significant increase in SABP within the three experimental groups, i.e., the average SABP of the lesioned, the shamed-operated and the control group maintained a normal range. Our results support the contention that the hypertension of SHR developed within 6-13 weeks after birth. In addition, the sympatho-inhibitory mechanism of PRN was not directly related to the development of hypertension.

Attenuation of cardiovascular reactions of vocalized and non-vocalized defence areas of periaqueductal grey following lesions in dorsomedial or ventrolateral medulla of cats

In the pretentorial periaqueductal grey (PAG), the region producing pressor responses, vocalization and other somatic and visceral signs (VPR) of the defence reaction and another region producing pressor responses (PR) were localized by electrical stimulation in adult cats, anesthetized with intraperitoneal chloralose (40 mg/kg) and urethane (400 mg/kg). The pressor responses included increases of systemic arterial pressure (SAP) and heart rate, increases of blood flow in the common carotid and femoral arteries and a decrease of blood flow in the superior mesenteric artery. The VPR was found in a relatively restricted region of the dorsolateral PAG, while PR was found scattered within the dorsal and ventral portions of the lateral PAG. The increase of SAP and the changes of blood flow in the sampled arteries were slightly greater during VPR than PR stimulation. Mild vocalization with a slight increase of SAP but marked increases of carotid and femoral blood flow (vasodilation) could be induced by microinjection of N-methyl D-aspartate (0.2 M, 200 nl) into the VPR and the blood flow increase, particularly that of the femoral artery, was greatly attenuated by atropine (1 mg/kg, i.v.). In order to ascertain the contribution of the medullary pressor areas to the VPR- and PR-induced responses, extensive lesions were made in the dorsomedial (DM) or vetrolateral medulla (VLM) by microinjections of kainic acid (KA, 0.024 M) in 27 of the 42 cats. The resting SAP and blood flow of the three arteries were reduced by lesioning of the VLM more than that of the DM. Responses of SAP and blood flow from activation of the PR and VPR, particularly the latter, were affected more after DM compared to VLM lesioning. These data suggest that, while the pretentorial PAG constitutes the 'defence area,' vocalization is confined exclusively to its dorsolateral region and that both the VLM and DM contribute to the cardiovascular components of defence reactions. The DM appears to have a greater contribution compared to the VLM.