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Biomedical subjects

J W Chang

Publications and source records attributed to J W Chang.

At least 73 records · Page 4Linked to original sources
PubMed1997

Volume changes following gamma knife radiosurgery of intracranial tumors.

BACKGROUND: The primary goal of radiosurgery for brain tumors is the prevention of further growth. The purpose of this article is to evaluate temporal changes of tumor volume after Gamma Knife radiosurgery on intracranial tumors. METHOD: Some 137 patients with 148 intracranial tumors who were treated with Gamma Knife radiosurgery and underwent radiological follow-up were reviewed. The tumors with high radiosensitivities to conventional external radiation were excluded. RESULT: The median radiological follow-up period was 12 months (range 1.5-38 months). Volume decreased after radiosurgery in 15 of 45 meningiomas; 10 of 37 schwannomas; 6 of 21 pituitary adenomas; 4 of 15 benign gliomas, including both of 2 subependymal giant cell astrocytomas; and 2 of 8 malignant gliomas. Some 87% of meningiomas and 60% of schwannomas whose volume had decreased began to shrink within 12 months and after 12 months, respectively. Transitory increase in volume preceded shrinkage in 16.2% of schwannomas, 13.3% of benign gliomas, 4.8% of pituitary adenomas, and 2.2% of meningiomas. Marked shrinkage occurred in 17 of 19 metastatic tumors and in all 3 neurocytomas shortly after radiosurgery. Of eight malignant gliomas, five began to grow 2-14 months (median = 5 months) after radiosurgery. CONCLUSION: Several points should be considered carefully while following up on patients after radiosurgery: the possibility of transient volume increase, tumor-specific volume change patterns, and the tumor-specific goals of radiosurgery.

Adolescent↗
PubMed1997

Dendritic translocation of RC3/neurogranin mRNA in normal aging, Alzheimer disease and fronto-temporal dementia.

RC3/neurogranin is a postsynaptic protein kinase C (PKC)-/calmodulin-binding substrate implicated in long-term potentiation (LTP) forms of synaptic plasticity. Our previous digoxigenin in situ hybridization (DIG-ISH) studies detected RC3 mRNA in apical dendrites and cell bodies of neurons in the rat cerebral cortex and hippocampus. This observation suggested that RC3 mRNA is selectively translocated to dendrites, where it may be translated locally in response to synaptic activity. To test this hypothesis further, we isolated a full-length cDNA clone of the homologous human RC3 mRNA from a human cortex lambda GT11 library, determined its nucleotide and predicted amino acid sequences, and performed mRNA expression studies in cerebral cortex from normal human patients and from patients with Alzheimer disease (AD) and fronto-temporal dementia (FTD). The human cDNA clone detects a single approximately 1.3 kb mRNA whose nucleotide sequence is 73% similar to the rat nucleotide sequence and 96% similar to its amino acid sequence. DIG-ISH studies detect robust staining of RC3 mRNA in cell bodies of numerous neurons throughout Layers II-VI and in both apical and basal dendrites of pyramidal neurons in human neocortex (temporal/frontal). We conclude that dendritic targeting of RC3 mRNA is conserved in human brain. In AD neocortex tissue, there is little or no evidence for RC3 mRNA translocation to dendrites, while in FTD neocortex, targeting of RC3 mRNA to apical dendrites is preserved. Comparative studies in AD and FTD point to the potential importance of synapse integrity and the dendritic cytoskeleton in RC3 mRNA targeting in the human neocortex.

Aged↗
PubMed1997

Microvascular decompression and percutaneous rhizotomy in trigeminal neuralgia.

We analyzed 417 patients with trigeminal neuralgia who underwent microvascular decompression (MVD; n = 146) or percutaneous procedures, i.e. radiofrequency rhizotomy (RFR; n = 235) and glycerol rhizotomy (GR; n = 36) between March 1973 and December 1996. MVD and RFR showed the highest rates of initial pain relief (MVD 96.5%; RFR 92.3%; GR 82.8%). RFR and GR had 5.1 and 3.3% rates of facial dysesthesia, respectively, and MVD had the lowest rate (0.3%). Among 9 cases (8.6%) with recurrences after MVD, 8 cases underwent RFR and all of them obtained good long-term results (7.2 years on average). We concluded that MVD is the treatment of choice for tolerant younger patients and should be recommended for patients who desire no sensory deficit. We also determined that radiofrequency rhizotomy is the procedure of choice for patients in whom MVD failed.

Catheter Ablation↗
PubMed1996

DSP-4 treatment influences olfactory preferences of developing rats.

Control cagemates of rats treated with the norepinephrine (NE) neurotoxin DSP-4, showed normal olfactory learning as infants, but abnormal aversion to home-cage odors as juveniles. Neither age nor social housing conditions influenced the odor preferences of DSP-4-treated rats: they showed tolerance or attraction to familiar odors at both developmental stages. Controls, but not DSP-4-treated juveniles, housed in mixed treatment groups, showed elevated concentrations of a serotonin metabolite and reduced NE concentrations in the hippocampus, suggesting that this social situation was particularly stressful for the controls. DSP-4-treated juveniles, but not infants, produced odors that were discriminable from controls'. Thus, conflicting olfactory signals in the home-cages of mixed juvenile groups may have led to the development of stress in controls. NE depletion appeared to lessen social stress effects in their DSP-4-treated cagemates. These findings support other data suggesting that NE modulates the biobehavioral effects of the social environment.

Adrenergic Agents↗
PubMed1996

Interleukin-1 beta induces prostaglandin G/H synthase-2 (cyclooxygenase-2) in primary murine astrocyte cultures.

Activation of glial cells and the consequent release of cytokines, proteins, and other intercellular signaling molecules is a well-recognized phenomenon in brain injury and neurodegenerative disease. We and others have previously described an inducible prostaglandin G/H synthase, known as PGHS-2 or cyclooxygenase-2, that is up-regulated in many cell systems by cytokines and growth factors and down-regulated by glucocorticoid hormones. In cultured mouse astrocytes we observed increased production of prostaglandin E2 (PGE2) after stimulation with either interleukin-1 beta (IL-1 beta) or the protein kinase C activator phorbol 12-myristate 13-acetate (TPA). This increase in PGE2 content was blocked by pretreatment with dexamethasone and correlated with increases in cyclooxygenase activity measured at 4 h. Northern blots revealed concomitant increases in PGHS-2 mRNA levels that peaked at 2 h and were dependent on the dosage of IL-1 beta. Dexamethasone inhibited this induction of PGHS-2 mRNA by IL-1 beta. TPA, basic fibroblast growth factor, and the proinflammatory factors tumor necrosis factor alpha and lipopolysaccharide, but not interleukin-6, also stimulated PGHS-2 mRNA expression. Relative to IL-1 beta, the greater increases in PGE2 production and cyclooxygenase activity caused by TPA correlated with a greater induction of PGHS-2 mRNA. Furthermore NS-398, a specific inhibitor of cyclooxygenase-2, blocked > 80% of the cyclooxygenase activity in TPA-treated astrocytes. These findings indicate that increased expression of PGHS-2 contributes to prostaglandin production in cultured astrocytes exposed to cytokines and other factors.

Animals↗
PubMed1996

Inhibition of renin secretion by Ca2+ through activation of myosin light chain kinase.

This study sought to identify specific enzyme(s) involved in the biochemical cascade of inhibition of renin secretion through Ca(2+)-calmodulin mediation with the use of inhibitors of protein kinase and phosphatases. Inhibition of renin secretion mediated by Ca(2+)-calmodulin was induced by incubating rat renal cortical slices in K(+)-rich depolarizing medium, producing > 50% inhibition. This inhibition was completely blocked by the calmodulin antagonist calmidazolium. The inhibitor of protein kinase with broad specificity, K-252a, blocked the inhibition of renin secretion. Neither KN-62, a specific inhibitor of Ca(2+)-calmodulin-dependent protein kinase II (CaMK II), nor specific inhibitors of protein phosphatase 2B (PP2B), cyclosporin A and FK-506, blocked the inhibition. On the other hand, all four known inhibitors specific for myosin light chain kinase (MLCK), with different chemical structures and mechanisms of inhibition (ML-9, ML-7, KT-5926 and wortmannin), almost completely protected renin secretion against the inhibition by Ca2+. In particular, ML-9 reversively protected > 77% secretion against the inhibition both in K(+)-rich medium alone and in combination with the calcium ionophore A-23187 in a concentration-dependent manner. Together, these findings from our present study provide the first evidence, albeit indirect in nature, for the possibility that activation of Ca(2+)-calmodulin-dependent MLCK at the downstream of Ca2+ influx into juxtaglomerular (JG) cells leads to phosphorylation of 20-kDa regulatory myosin light chain (MLC20). Through interaction with actin, the phosphorylated MLC20 may play an important role in the inhibitory stimulus-secretion coupling of renin.

Animals↗
PubMed1996

Gamma knife surgery in pituitary microadenomas.

The application of transsphenoidal microsurgery in the management of pituitary microadenoma, long regarded as effective surgical treatment, has had a relatively low mortality and morbidity rate. However early failure and late recurrence has been reported in no small numbers. It has been proposed that stereotactic radiosurgery is an alternative treatment modality. Recent advances in neuroimaging permits precise targeting in radiosurgery of microadenomas. Additionally, a prompt hormonal reduction after the treatment is important for the patients with hormonally active microadenomas. The authors performed Gamma Knife radiosurgery in 27 patients with pituitary adenomas and observed the hormonal changes after radiosurgery in 19 patients with functioning microadenomas (5 with Cushing's disease, 7 with acromegaly, and 7 with prolactinoma). The maximum dose administered ranged from 25 to 75 Gy. The margin of the tumor was encompassed within the 50 to 90% isodose volume. The endocrinological status was assessed pre- and post-operatively. We measured the serum growth hormone and prolactin level, as well as the 24-hour urinary free-cortisol level. Normalization of the hormonal level was achieved in 6 cases, the majority of them within 10 months. The other 6 cases showed marked reduction of hormonal levels (less than 50% of preoperative levels) with a strong possibility of hormonal remission at further follow-up. The remaining 6 were failures. The cure for one case is still pending. It took approximately 1 approximately 3 months after the radiosurgery before the reduction of hormonal secretion began to show up with some improvement of symptoms. When the GKS was successful, hormonal secretion seemed to return to normal within 10 months. Although further follow-up is necessary to evaluate the long-term tumor control rate and hormonal effect, these initial results indicate a potential therapeutic role of radiosurgery in controlling hormone hypersecretion in pituitary microadenomas. Gamma knife radiosurgery is very promising in managing pituitary microadenoma with complementary of the transsphenoidal surgery.

Adenoma↗
PubMed1995

Complications following Gamma Knife radiosurgery.

Between May 1992 and February 1994, 213 lesions in 183 consecutive patients were treated with Gamma Knife radiosurgery at Severance Hospital, Yonsei University, Seoul, Korea. During this period, we experienced 2 deaths, 1 directly and another indirectly related to irradiation. Nonfatal complications included 1 tumor bleeding, and 4 ventriculoperitoneal shunts had to be inserted due to aggravation of preexisting hydrocephalus. Radiation-induced imaging changes developed in 23.6% of the cases followed up for more than 6 months. Among 24 lesions of 8 cavernous hemangiomas, all 4 cases with lesions larger than 1.5 cm3 developed imaging changes.

Dose-Response Relationship, Radiation↗
PubMed1995

Indium-111-pentetreotide imaging in intra-axial brain tumors: comparison with thallium-201 SPECT and MRI.

UNLABELLED: Highly undifferentiated glial tumors do not express somatostatin receptors (SSR) in contrast to low-grade astrocytomas which contain SSR. To differentiate a malignant glioma from a low-grade astrocytoma and to distinguish an SSR-positive intra-axial brain tumor from an SSR negative one, 111In-pentetreotide brain SPECT was prospectively undertaken. METHODS: Eight patients with intra-axial brain tumors (three glioblastoma multiforme, one low-grade astrocytoma, one lymphoma, one medulloblastoma, one neurocytoma and one metastatic tumor) were studied. Thallium-201 and 111In-pentetreotide brain SPECT were performed with a 3- to 4-day interval before surgery. The SPECT findings were compared with those of Gd-enhanced MRI. RESULTS: Increased uptake of 111In-pentetreotide was observed in all of the patients with glioblastoma multiforme (Grade in two and Grade + in one) despite lack of SSR. Low-grade astrocytoma exhibited minimal uptake of 111In-pentetreotide (Grade +). Remaining tumors had intense uptake of 111In-pentetreotide. Thallium-201 SPECT showed similar findings to those of 111In-pentetreotide scintigraphy except in two patients with glioblastoma multiforme: One with 201TL negative scan showed increased uptake of 111In-pentetreotide and the other showed increased thallium uptake but minimal uptake of 111In-pentetreotide. The uptake pattern of both 201Tl and 111In-pentetreotide appeared to correlate with Gd-enhanced MRI. CONCLUSION: Indium-111-pentetreotide scintigraphy is sensitive in the detection of intra-axial brain tumors; however, it has no role in assessing the tumor grading and in the definition of the receptor profile.

Adult↗
PubMed1994

Long-term follow-up results of stereotactic adrenal medullary transplantation in Parkinson's disease.

Stereotactic adrenal medullary transplantation into the striatum was performed in 5 patients with severe Parkinson's disease. Four patients had previously been treated with thalamotomies and all were on L-dopa therapy with significant side effects. All 5 patients had shown marked disability before the procedure. Autologous adrenal medullary tissue was sliced into 20-30 fragments and transplanted into two sites of the caudate nucleus, one at the ventricular surface and the other in the head of the nucleus. The cases were followed for 4-5 years (mean 4.5 years), except for 1 patient who died of unrelated causes 22 months after the procedure. Initial bilateral symptom improvement was observed in all cases for 9-21 months (mean 15.2 months) after transplantation without L-dopa therapy. Later, these improvements progressively deteriorated. L-dopa therapy had to be resumed for all. MRI on the long-term follow-up showed the transplanted tissue as a low signal intensity area surrounded by high intensity spots in T1- and T2-weighted images. Compared to previous MR studies, the transplanted tissue was shrunken and presumed nonviable.

Adrenal Medulla↗
PubMed1994

An unusual intracranial metastasis of osteosarcoma.

Intracranial metastasis is unusual in osteosarcoma. A case of osteosarcoma was presented with a large intracranial "stone" which was a subdural convexity metastasis. Smaller epidural metastases over other areas were noted also in brain CT scan. Using the radiographs and bone scans, many other lesions at bones, the mediastinum, pleura, perirenal space, and adrenal gland were detected simultaneously. This condition might result from either early metastases or multifocal osteosarcomas. Because many of the above lesion sites were not frequent locations of primary osteosarcoma and had been reported as metastatic targets of osteosarcoma. So the explanation of a very malignant osteosarcoma with early metastases may be more appropriate for this case. The baseball-like tumor in the subdural space with marked compression of the brain surface was grossly totally excised. Histopathologic examination confirmed the diagnosis of osteosarcoma. Postoperatively, the man's condition improved dramatically, though only for two months. He died 5 months later. Reports of such metastatic osteosarcomas are reviewed.

Adult↗
PubMed1991

Skull metastasis of primary hepatoma--case report.

Skull metastasis of hepatoma is rare. A case of a 56-year-old man with painless masses over the skull is presented in this paper. The largest mass in the occipital area measured 10 x 15 cm2; skull radiographs and computed tomography (CT) of the brain revealed several skull tumors with epidural extensions. The largest mass was almost totally excised, and metastatic hepatoma was diagnosed by a histological examination and supported by abdominal ultrasound findings. Literature in regard to hepatoma with skull metastasis is also reviewed.

Carcinoma, Hepatocellular↗
PubMed1991

Cerebellar lipoma: report of a case.

A patient with normal motor and intellectual development suffered headache; especially over the occipital area; and, blurring of vision for five months. Computerized tomography and magnetic resonance imaging of the brain showed a lipoma in the quadrigeminal/superior cerebellar cistern compressing of the aqueduct, inferior colliculus, and vermis. Using the modified sitting position, the tumor was almost totally removed via the infratentorial supracerebellar approach. Postoperative headache and blurring of vision had been improved, but ataxic gait and mild diplopia due to right superior oblique palsy was noted. Ataxic gait was disappeared in half a month and diplopia in two months respectively.

Adolescent↗
PubMed1989

Neonatal 6-hydroxydopa, but not DSP-4, elevates brainstem monoamines and impairs inhibitory avoidance learning in developing rats.

The involvement of brain monoamines in learning and memory in developing rats was studied by comparing the effects of 3 different noradrenergic neurotoxin treatments. Two experimental groups of male Sprague-Dawley rat pups were injected systemically with 50 micrograms/g of N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4) either on the day of birth or on postnatal days 17-18. Rats in the third experimental group were injected systemically with 60 micrograms/g of 6-hydroxydopa (6-OHDOPA) on postnatal days 0 and 2. Control littermates received vehicle. The animals were trained on an inhibitory avoidance task on postnatal days 27-29 and tested for retention 24 h later. The drug treatments produced comparable depletion of norepinephrine in the hippocampus and frontal cortex. 6-OHDOPA, but neither DSP-4 treatment, significantly elevated brainstem concentrations of norepinephrine and serotonin. In addition, 6-OHDOPA, but not DSP-4, significantly impaired retention of the inhibitory avoidance task. The impairment did not reflect insensitivity to the footshock used in training: both neonatal drug treatments tended to lower, not raise, footshock thresholds, as measured by a flinch test. High affinity choline uptake was not affected by either neonatal drug treatment in any of the brain areas examined. Thus, the 6-OHDOPA-induced behavioral deficit did not involve altered acetylcholine function. The results implicate brainstem monoamines in the modulation of learning and memory during development.

Animals↗
PubMed1989

Distribution of juxtaglomerular cells and synthesis and release of renin granules in patients with renal artery stenosis.

100 pieces of renal tissue from 4 patients with renal artery stenosis were studied histologically. Juxtaglomerular cells were found not only in the region close to the glomerulus but also in the proximal 2/3 of the afferent arteriole of the glomerulus, but not in the interlobular arterioles. In the cytoplasm of juxtaglomerular cells, three kinds of granules were found: crystalline granules (immature), the round or ovoid granules (mature), and the lobulated granules (fusion). Renin was synthesized in the rough endoplasmic reticulum and packaged in the Golgi complex. Electron microscopic findings suggested that the secretory microvesicles were produced on the surface of Golgi complex. They fused to form primary crystalline granules, which were enlarged by renin supplied by transportation vesicles and finally formed typical crystalline granules. The mature renin granules (round or ovoid) moved toward the periphery of the cytoplasma. Their limiting membranes on the side toward the basement membrane disintegrated and formed microvesicular bodies passing through the periplasm, and the basement membrane and were discharged into the interstitial matrix.

Humans↗
PubMed1987

[Establishment of epithelial cell line TBC-27 from a human bladder transitional cell carcinoma and its biological characteristics].

The cell line TBC-27, from a human bladder transitional cell carcinoma Grade II, was established and maintained for 8 months through 27 passages. TBC-27 cells have the epithelioid cell morphology during culture. The population doubling time of the 14th generation cells was 27 hours by growth curve. The chromosome karyotype of the 12th generation cells consisted mainly of hypodiploid (mode 40-45). Ultrastructurally, there was a great deal of freeribosome and vesicle in the cytoplasm and a great number of atypical microvilli on the surface of the 21st generation cells. The heterotransplantation test revealed that the xenografted tumor in the immunosuppressed suckling rats was similar to the initial bladder carcinoma in histology.

Animals↗