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Biomedical subjects

A D Wang

Publications and source records attributed to A D Wang.

At least 19 recordsLinked to original sources
PubMed2001

Antitumor efficacy of SarCNU in a human glioma xenograft model expressing both MGMT and extraneuronal monoamine transporter.

Treatment of malignant brain tumors with chloroethylnitrosoureas (CENUs) in addition to surgical resection and radiotherapy remains the foundation of glioma therapy. However, the clinical response to CENUs is at best modest. A novel analogue of nitrosoureas, 2-chloroethyl-3-sarcosinamide-1-nitrosourea (SarCNU), as compared to the standard CENU, 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU), has been demonstrated to have increased anticancer effects both in vitro and in vivo. Unfortunately, many human tumors have been known to be resistant to CENUs since they express DNA repair protein O6-methylguanine-DNA methyltransferase (MGMT). In order to assess whether SarCNU has an effect on MGMT positive tumors, we evaluated its antitumor efficacy using an MGMT positive human glioma (SF-767) nude mouse xenograft model. Since SF-767 has high MGMT levels, BCNU treatment (20 mg/kg, Q4D x 3 i.p.) alone did not result in a satisfactory anticancer effect (p > 0.05). As expected, O6-benzylguanine (O6-BG) (100 mg/kg), which was given prior to BCNU treatment, by depleting MGMT activity, significantly enhanced BCNU antitumor efficacy (p < 0.001). Moreover, SarCNU treatment (167 mg/kg, Q4D x 3 i.p.) alone had a better antitumor effect than O6-BG plus BCNU treatment (F = 51.7, p = 0.0004). However, in this xenograft model, O6-BG did not significantly enhance the anticancer efficacy of SarCNU (F = 0.8, p = 0.411). The SF-767 human glioma xenograft is positive for extraneuronal monoamine transporter EMT (EMT) as determined by reverse-transcription polymerase chain reaction (RT-PCR). Our present results suggest that SarCNU is also effective for MGMT positive tumor if they exhibit EMT.

Animals↗
PubMed2001

[Analysis of genetic diversity of Bama miniature pigs and Guizhou miniature pigs by RAPD].

RAPD analysis was performed with 31 selected single primers to study genetic diversity of two strains of miniature pigs, The percentages of polymorphisic loic in or between two strains of miniature pigs were 30.9%, 29.2% and 25.7% respectively, and the average genetic distances in and between two strains of miniature pigs were 0.120, 0.072, and 0.067 respectively. These results suggested that genetic diversity and genetic variability were poorer in and between two strains of miniature pigs than ordinary breeds' pigs.

Animals↗
PubMed1999

Enhanced antitumor activity of sarCNU in comparison to BCNU in an extraneuronal monoamine transporter positive human glioma xenograft model.

A novel analogue of nitrosoureas, 2-chloroethyl-3-sarcosinamide-1-nitrosourea (SarCNU), has demonstrated increased anticancer effects in vitro and in vivo. Our previous work suggested that SarCNU enters cells via the extraneuronal monoamine transporter (EMT), that contributes to its enhanced cytotoxicity. In the present study, comparative activities of SarCNU and 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) were evaluated in an EMT positive human glioma xenograft model. Athymic nude mice implanted subcutaneously or intracranially with human glioma SHG-44, a cell line that has been confirmed EMT positive by using reverse-transcription polymerase chain reaction (RT-PCR) assay, were treated with SarCNU at an optimal dose of 167 mg/kg, or BCNU at 20 mg/kg or 30 mg/kg, q4d x 3 intraperitoneally (i.p.). In 17 animals with subcutaneous tumor grafts treated with SarCNU, 9 animals became tumor free and 8 demonstrated tumor regression. While in the BCNU treated group, there were only 2 out of 10 mice in the 20 mg/kg group and 2 out of 7 in the 30 mg/kg group, which demonstrated some tumor regression. There were 4 drug related deaths in the BCNU (30 mg/kg) group, while there were no drug related deaths in the SarCNU group. In the intracranially implanted mice, the median survival time in the SarCNU group was more than 130 days, while in the BCNU treated group it was only 22 days which was similar to the control group (18 days). This is the first demonstration that SarCNU, in comparison to BCNU, has enhanced anticancer activity in an EMT positive human glioma xenograft model.

Animals↗
PubMed1993

Cerebral sparganosis diagnosed and treated with stereotactic techniques. Report of two cases.

Infestation of the central nervous system with sparganum, the larva of Spirometra mansoni, is rare. Only 27 cases have been reported in the literature; however, the true incidence might be underestimated. Two cases are reported that were definitively diagnosed by stereotactic biopsy techniques. Without a positive histological diagnosis, the first case would have been diagnosed as having a metastatic brain tumor and a course of radiotherapy would probably have been initiated. Differentiation between granuloma of cerebral sparganosis and brain tumors such as meningiomas, gliomas, and metastatic tumors is often difficult before operation. Detailed magnetic resonance imaging might offer some help in such cases. Emphasis is placed on the increasing importance of stereotactic surgery in the diagnosis and treatment of an intracerebral mass lesion, including cerebral sparganosis.

Agricultural Workers' Diseases↗
PubMed1991

Intramedullary spinal cord metastasis: report of a case and review of the literature.

Intramedullary spinal cord metastasis (ISM) is an unusual cause of myelopathy, in comparison to the common problem of extramedullary metastasis. Most patients with ISM are found at autopsy. When patients with ISM are diagnosed premorbidly, they usually have a previously known or concurrently diagnosable primary neoplasm. Radiation therapy is the definitive therapy. We recently encountered a patient who was seen initially because of progressive myelopathy, without evidence of underlying malignancy, in whom a papillary carcinoma was found at myelotomy. The condition improved after surgery and the patient returned to his previous work for five months. Subsequently, a lesion histologically identical with that obtained from the previous myelotomy was found in the lung. This case illustrates the value of surgical intervention in selected situation. When there is no identifiable organ metastasis or multiple intramedullary lesions, radical microsurgical resection of a focal intramedullary lesion should be considered.

Carcinoma, Papillary↗
PubMed1991

Post-traumatic basal ganglia hemorrhage: analysis of 52 patients with emphasis on the final outcome.

A series of 52 patients suffering post-traumatic basal ganglia hemorrhage (BGH) after closed head injury is reviewed. Post-traumatic BGH was associated with other intracranial lesions in most cases. The outcome in this series is rather good, with 53.8% of patients having a functional survival. Radiologically, the post-traumatic intraventricular hemorrhage (IVH) and brainstem hemorrhage usually coexisted with a poor outcome. Old age (greater than 60), abnormal pupil reaction, impaired oculocephalic response, and abnormal motor response to pain stimuli are reliable clinical hallmarks for poor prognosis.

Adolescent↗
PubMed1990

The association of arteriovenous malformation and aneurysm within the posterior cranial fossa--report of a case.

A relatively rare case of cerebellar arteriovenous malformation (AVM) associated with a saccular aneurysm fed by the left posterior inferior cerebellar artery (PICA) is described. The interpretation of angiograms and the appropriate surgical treatment for the coexistence of the intracranial AVM and aneurysm are discussed. It is a fact that the steal phenomenon existed in the flow of contrast medium during the angiography. The appropriate surgical treatment may be clipping of the aneurysmal neck first and then radical excision of the AVM.

Adult↗
PubMed1990

Spinal extradural cavernous hemangioma.

Three cases of isolated spinal extradural cavernous hemangiomas are reported, two in the thoracic and one in the lumbar region. One of them manifested as acute cord compression, the other two as chronic progressive myelopathy or radiculopathy. A total excision or subtotal excision with irradiation was performed. All of them had good functional recovery. The clinical picture, radiological diagnosis, and optimal method of treatment are discussed. The relevant literature is reviewed.

Adult↗
PubMed1990

Epistaxis due to traumatic intracavernous aneurysm: case report.

A patient who noted the onset of repetitive arterial epistaxis and progressive unilateral visual impairment 2 months after a blunt head injury was found to have a traumatic aneurysm of the cavernous portion of internal carotid artery (ICA). The epistaxis resolved and his vision recovered following a trapping procedure. This case and a review of previously reported cases emphasize the importance of early cerebral angiography in patients with post-traumatic epistaxis and visual failure.

Adult↗
PubMed1989

Upper lumbar disc herniation.

Herniations of the upper lumbar disc have often been overlooked due to a relatively low incidence we had 457 lumbar disc surgeries from January 1978 to June 1987. Twenty-two of them were of the upper three lumbar discs. We analyzed these patients according to their clinical syndromes, radiological findings and surgical results. The characteristic features of anterior thigh pain from upper lumbar disc herniation were different from the more commonly seen fourth and fifth lumbar disc herniation which resulted in sciatica. The incidence of cauda equina syndrome was relatively high in our series (36%). All the 22 cases had correlated X-ray findings. Satisfactory operative results for upper lumbar disc herniation were achieved in 20 of 22 (90%).

Cauda Equina↗
PubMed1989

Cystic meningioma--a case report.

A case of cystic meningioma is presented. The cyst in this particular case is within the tumor. Preoperatively, the diagnosis has been confused with astrocytoma, hemangioblastoma and neuroblastoma. Retrospectively, we conclude that careful evaluation of CT scan and angiogram will lead to accurate diagnosis.

Cysts↗
PubMed1989

Acoustic neurinoma presenting as intratumoral bleeding.

The authors report a case of acoustic neurinoma presenting as intratumoral bleeding. This is the tenth reported occurrence. The literature is reviewed. All cases that have been reported have appeared with sudden onset of headache, vomiting, and decreased levels of consciousness. Aneurysm rupture, an arteriovenous malformation, or other vascular anomalies are suspected first. Preexisting unilateral hearing impairment is a valuable clue to differential diagnosis. Contrast-enhanced computed tomographic scans and cerebral angiograms are important tools for correct diagnosis. The tumor size (greater than 2 cm) and the thin, dilated vessels within the tumor are considered as pathogenetic factors for bleeding. When neurological status is not stable, placement of a ventriculoperitoneal shunt followed by urgent extirpation of the tumor is indicated.

Aged↗
PubMed1987

Effects of temporary arterial occlusion on somatosensory evoked responses in aneurysm surgery.

Changes in the central conduction time (CCT) during the application of temporary clips were studied in 40 patients who had undergone operations for intracranial aneurysms in relation to postoperative neurological outcome. Ten of these 40 patients (25%) showed postoperative morbidity, although promptly recoverable in 5. None of the patients whose CCTs did not change following temporary occlusion of major vessels showed any postoperative morbidity, except in one case of anterior cerebral artery aneurysm. In 6 patients, temporary vascular occlusion caused a considerable transient prolongation in CCT of up to 10 msec. Two of these 6 patients were associated with postoperative neurological deficit (which was recoverable in 1). The cortical response became flat in 15 patients. Seven of these 15 patients showed hemispheric deficits postoperatively, although recoverable in 4. There was a correlation between the change in the somatosensory evoked response and postoperative outcome. Disappearance of the N20 potential following occlusion is regarded as a danger signal, but postoperative, irrecoverable neurological deficit seems to be unlikely if its disappearance takes more than 3-4 minutes. Even if the cortical response disappears, the clinical outcome is expected to be good if the N20 potential recovers within 20 minutes after recirculation.

Adult↗
PubMed1985

The application of flash visual evoked potentials during operations on the anterior visual pathways.

Flash visual evoked potentials (F-VEP's) have been recorded in fifteen patients (thirty eyes) with anterior visual pathway compression lesions before, during and after the operation in relation to clinical visual testing. A grading system for the wide variety of abnormal F-VEP's has been established, based on changes in forty patients (eighty eyes). No significant correlation between change in F-VEP and visual acuity or visual field has been demonstrated. Intraoperative F-VEP's have been found to be sensitive to halothane and to surgical manipulation of the optic nerve and/or chiasm during dissection of the tumour. The technique is considered a useful means of identifying the optic pathway during operation and may assist in prevention of optic damage if the transphenoidal approach is used.

Adult↗
PubMed1985

The effects of halothane on somatosensory and flash visual evoked potentials during operations.

Intraoperative use of somatosensory evoked potentials (SEP's) to monitor intracranial aneurysm surgery and flash visual evoked potentials (F-VEP's) for parasellar surgery have been routinely employed in our clinic. We found that both EP modalities are sensitive to the changing concentration of our standard hypotensive agent, halothane. The prolongation of the N14-N20 interpeak latency to median nerve stimulation at the wrist, and prolongation of P100 latency with altered configuration of early VEP components to flash light stimulation, appear to be the results of direct pharmacological effects of the agent and not an effect of secondary hypotension. VEP is found easily abolished by halothane at a concentration of 2.0%, while the SEP is more resistant. Halothane is not ideal however when monitoring intraoperative VEP.

Adolescent↗
PubMed1985

Relationship between hemispheric cerebral blood flow, central conduction time, and clinical grade in aneurysmal subarachnoid hemorrhage.

The relationship between central conduction time (CCT) and hemispheric cerebral blood flow (CBF) has been examined in 20 patients presenting with subarachnoid hemorrhage. A total of 63 combined CCT/CBF recordings were performed at various times throughout the hospital course of these patients, and the findings were correlated to clinical status. The initial-slope index of the CBF (CBF isi) was found to correlate well with clinical grade, and a gradation in flow was noted between the different neurological grades. Patients in Grades I and II (Hunt and Hess classification) had the highest flows (mean CBF isi = 47.2 +/- 8.1); Grade III patients had intermediate flows (mean CBF isi = 39.6 +/- 7.8); and Grade IV patients had the lowest flows (mean CBF isi = 32.0 +/- 6.4). While CCT tended to become increasingly prolonged with worsening grade, a significant difference could not be demonstrated between Grade I, II, and III patients. Only when Grade IV status was reached was the CCT significantly prolonged. When CBF isi and CCT were examined, a threshold relationship was noted between CBF isi and CCT prolongation. At flow values above 30, little change was noted in CCT, and CCT remained in the normal range. However, at flow values below 30, CCT became increasingly prolonged as blood flow diminished. The degree of CCT prolongation appeared to be directly proportional to the degree of blood flow diminution at flows below threshold.

Adult↗