Biomedical subjects

C N Chang

Publications and source records attributed to C N Chang.

At least 73 records · Page 4Linked to original sources

PubMed1993

Epidural hematomas in the posterior cranial fossa.

A review of 89 cases of posterior fossa epidural hematoma (PFEDH) is presented. The mortality rate was 17.9%. In 44 cases (49.4%) there were associated intracranial hematomas. In 30 cases the hematoma was localized within the boundary of the foramen magnum and the transverse and sigmoid sinuses ("pure" PFEDH). In 59 cases the hematoma extended beyond the sinuses to the occipital area ("mixed" PFEDH). In the pure PFEDHs, the bleeder could be identified in only six cases and in five cases the source was a bleeding transverse sinus. The bleeders disclosed in the mixed PFEDHs were a torn transverse sinus in 28 cases, a meningeal artery in three cases, and a bony fracture in three cases. The possibility of a PFEDH should be kept in mind when evaluating patients who have suffered an occipital blow resulting in a frontal or temporal hematoma. In our series, patients with the pure PFEDHs with no associated intracranial hematomas had the best prognoses. Nine patients developed a PFEDH after surgery for a supratentorial hematoma. In 14 cases the PFEDH was treated at the subacute or chronic stage. All but one patient survived with a good recovery. Children generally had better prognoses.

Adolescent↗

PubMed1993

The expectant treatment of "asymptomatic" supratentorial epidural hematomas.

Seventy-four patients with a traumatic epidural hematoma (EDH) and a Glasgow Coma Scale score of more than 12 received expectant treatment; 14 subsequently underwent surgical evacuation of the EDH. A patient with initial brain computed tomograms (CT) showing an EDH volume of more than 30 ml, a thickness of more than 15 mm, and a midline shift beyond 5 mm tended to require surgery within 3 days of the injury when the brain had exhausted its compensatory mechanism and yielded to the expanding EDH. After the 3-day period, in the absence of neurological symptoms, the presence of the EDH may not be an indication for surgical evacuation or hospitalization beyond 7 days. In our patients, the presence of a skull fracture in the temporal bone, the heterogeneous density of the EDH in the CT scan, or the 6-hour period between the CT study and the injury did not significantly increase the failure rate of nonsurgical treatment. Although a zero mortality was achieved in this series, these guidelines may not be applicable to the management of an infratentorial EDH.

Adult↗

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↗

PubMed1993

Complete transection of common bile duct due to blunt abdominal trauma: a case report and literature review.

A case of complete transection of the common bile duct due to abdominal blunt injury in a 49-year-old man is presented. The rarity of this injury and its initial presentation as a pancreatic pseudocyst warrant its description. This patient was diagnosed as having bile duct injury following ascites aspiration. Common bile duct transection was documented and a choledochostomy was done. However, bile leaked into the peritoneal cavity one week after the operation. A Roux-en-Y choledochojejunostomy was done successfully in a second operation. Delayed diagnosis is common in these kinds of injuries, but it should be considered when a patient has bile ascites, abdominal distention and jaundice after a blunt abdominal injury. A review of the literature, methods of diagnosis and the technique of surgical repair are described.

Cholangiography↗

PubMed1993

Eosinophilic granuloma of the skull--report of four cases.

Eosinophilic granuloma is a benign form of the three clinical variants of histiocytosis-X. It is an uncommon, localized granulomatous process, forming solitary or multiple lytic skeletal lesions, and primarily involving male children and young adults. We studied 4 cases, three boys and one girl, aged 4, 8, 27 and 12 years, in Chang Gung Memorial Hospital from 1981 to 1990. Their common presentation was the rapidly growing, painful, and protruding scalp masses without neurological deficits. En bloc excisions of these lesions were performed. Then radiotherapy was given postoperatively in two cases, chemotherapy in one, and no adjuvant treatment in one. During their follow-up period of 2 to 10 years, all 4 patients were well, without evidence of recurrence.

Adult↗

PubMed1992

Biochemical pharmacology of (+)- and (-)-2',3'-dideoxy-3'-thiacytidine as anti-hepatitis B virus agents.

2',3'-Dideoxy-3'-thiacytidine (cis-(+/-)-SddC) was found to have potent activity against hepatitis B virus and human immunodeficiency viruses in culture. Recent studies by us identified (-)-SddC as the stereoisomer responsible for the antiviral effect and showed that the cytotoxicity was mainly caused by (+)-SddC. Metabolism studies showed that these drugs were converted to their monophosphates, diphosphates, and triphosphates. The enzyme responsible for the formation of monophosphates was identified to be cytoplasmic deoxycytidine kinase in CEM cells. Uptake studies showed that the intracellular concentration of (-)-SddC and its metabolites was approximately 5-fold higher than that of (+)-SddC metabolites. (-)-SddCTP was more potent than (+)-SddCTP in inhibiting hepatitis B virus replication; (+)- and (-)-SddCTP exhibited minimal inhibition on polymerases alpha and delta, more inhibition on beta, and strong inhibition on gamma. In all cases, (+)-SddCTP was found to be more inhibitory than (-)-SddCTP to all four polymerases. (+)-SddCMP competed with dCTP for incorporation into DNA by DNA polymerase gamma and beta and served as a chain terminator; however, similar incorporation was not detected using other polymerases. The selective inhibition of DNA synthesis in isolated mitochondria by (+)- and (-)-SddCTP suggests a stereospecificity on the mitochondrial uptake of deoxynucleoside triphosphates.

Antiviral Agents↗

PubMed1992

Deoxycytidine deaminase-resistant stereoisomer is the active form of (+/-)-2',3'-dideoxy-3'-thiacytidine in the inhibition of hepatitis B virus replication.

2',3'-Dideoxy-3'-thiacytidine (+/-)-SddC) was found to have potent activity against human hepatitis B virus as well as human immunodeficiency viruses in culture. The (-)form ((-)-SddC) which is resistant to deoxycytidine deaminase was found to be the more active antiviral stereoisomer than the (+)-form ((+)-SddC). The (+)-SddC is susceptible to deamination by deoxycytidine deaminase and is 25- and 12-fold more toxic than (-)-SddC in CEM cells in terms of anti-cell growth and anti-mitochondrial DNA synthesis, respectively. Similar results were obtained using a mixture of their 5-fluoro analogs ((+/-)-FSddC). Unlike 2',3'-dideoxycytidine, which is a potent inhibitor of mitochondrial DNA synthesis and results in such delayed toxicity as peripheral neuropathy with long term usage, (-)-SddC does not affect mitochondrial DNA synthesis. The (-)form is phosphorylated to (-)-SddCMP and is subsequently converted to (-)-SddCDP and (-)-SddCTP. One additional major metabolite which has been tentatively assigned the name "(-)-SddCMP sialate" was also identified. No significant difference in terms of the profiles of the metabolites was found between 4 and 24 h. There is an appreciable amount of (-)-SddCTP detectable 24 h after removal of the drug. (-)-SddCTP was also found to be approximately 3-fold more potent than (+)-SddCTP in inhibiting human hepatitis B virus DNA polymerase. This is the first nucleoside analog with the unnatural sugar configuration demonstrated to have antiviral activity.

Antiviral Agents↗

PubMed1992

Conversion of 5-iodo-2-pyrimidinone-2'-deoxyribose to 5-iodo-deoxyuridine by aldehyde oxidase. Implication in hepatotropic drug design.

5-Iodo-2-pyrimidinone-2'-deoxyribose (IPdR) can be converted into 5-iodo-deoxyuridine (IUdR), a clinical radiosensitizer, by aldehyde oxidase in the liver. This conversion does not require exogenous cofactors and cannot be catalyzed by mixed-function oxidases, xanthine oxidase or many other oxido-reductases. This "IPdR oxidase" activity is enriched in the liver; thus, extensive conversion of IPdR to IUdR could be anticipated in the liver and the therapeutic index of IPdR could be better than that of IUdR as a radiosensitizer for primary liver cancers or tumors metastasized to the liver. Based on structure and activity relationship studies, nucleoside analogues which could be activated by this enzyme to compounds capable of inhibiting DNA synthesis could be designed and should be explored as agents against cancer, viruses or parasites in the liver.

Aldehyde Oxidase↗

PubMed1992

Intraventricular neurocytoma: four cases report.

Intraventricular neurocytoma, a newly identified disease entity with probably not so rare incidence, has several distinctive clinico-pathological characteristics. Four cases are presented. As in the other cases reported in the literature [1-7], the characteristic features are young age, location close to the junction of the septum pellucidum and foramen of Monro, and well-differentiated neuronal origin pathologically.

Adult↗

PubMed1992

Bilateral glossopharyngeal neuralgia after excision of a solitary cervico-medullary haemangioblastoma: case report.

A man presenting with sleep apnoea was found to have a haemangioblastoma at the cervico-medullary junction. The associated hydrocephalus and syringomyelia resolved after excision of the tumour. Postoperatively the patient developed transient bilateral glossopharyngeal neuralgia, presumably due to surgical damages to the tractus solitarius. To the best of our knowledge this is the first reported case with transient bilateral glossopharyngeal neuralgia following resection of a haemangioblastoma of the cervico-medullary junction.

Adult↗

PubMed1992

Spontaneous intracerebral hematoma from occult carotid-cavernous fistula during pregnancy and puerperium. Case report.

In most cases, intracerebral hemorrhage during pregnancy or puerperium results from cerebral aneurysms or arteriovenous malformations. The authors present a case of a 30-year-old woman whose symptoms from a traumatic carotid-cavernous fistula had completely resolved 1 1/2 years after the event, but recurred 4 years later, causing two hemorrhages during pregnancy (33rd and 35th week of gestation) and one during the postpartum period (10 days after Caesarean section). Partial thrombosis of the cavernous sinus with obliteration of most of the drainage from the fistula accounted for the resolution of clinical symptoms, but also promoted back-flow to the preserved drainage of superficial cortical veins. The hemodynamic changes and the hormonal effects due to the patient's subsequent pregnancy further aggravated the venous engorgement and finally caused rupture. All three hematomas occurred in the vicinity of the extremely dilated veins, suggesting that back-flow with venous hypertension was the probable cause for the intracerebral hematomas. Spontaneous healing of the carotid-cavernous fistula should be confirmed with cerebral angiography.

Adult↗

PubMed1992

[Pituitary apoplexy: a study of eighteen cases].

Pituitary Apoplexy is a rare but sometimes life threatening condition which requires prompt recognition and timely medical intervention to avoid catastrophic consequences. From January 1979 to June 1989 and total of one hundred and ninety eight pituitary tumor patients were operated on our hospital. Eighteen cases (9.1%) were diagnosed "pituitary apoplexy" according to histopathological findings. The group consisted of twelve men and six women ranging in age from twenty two to sixty one years with a mean of forty. There were three cases of prolactin-secreting adenomas (16.7%), four growth-hormone secreting adenomas (22.2%), and eleven nonfunctional adenomas (61.1%) with an incidence of 6.1%, 8.3%, and 11.4% respectively (P > 0.05). Clinical manifestation occurred acutely in 66.7% and nonacutely in 33.3%. The patients presented with headaches (100%), visual impairment (83.3%), visual field defects (66%), disturbed consciousness (22%), fever and meningismus (11%). Radiological examinations able to demonstrate abnormalities included plain skull films (84%), computed tomography (84.6%), and angiography (93.8%). Various investigations of endocrine function pre and post operatively showed a deficient gonad axis (53%, 62.5%), adrenal axis (26.7%, 56.2%), and thyroid axis (20%, 43.8%). Sixteen cases received a transsphenoid operation and three cases underwent a transfrontal craniotomy. No case of mortality was reported. Postoperative radiotherapy was given to nine cases and nine cases were followed up on a regular basis. Therefore, our retrospective study suggests that pituitary apoplexy is not uncommon and has an acute clinical presentation. No particular tumor type was prone to occur. Various radiological examinations could define perisellar abnormalities. With a decreasing order of hormone deficiency, gonad, adrenal and thyroid axis were observed during the course of treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

The simultaneous use of electrocochleogram, brainstem auditory evoked potential and facial muscle EMG in cerebellopontine angle tumor removal.

In six cases of acoustic neurilemmoma, electrocochleogram (ECOchG), brainstem auditory evoked potentials (BAEP) and facial muscle electromyograms (EMG) were recorded to monitor facial nerve and brainstem function. Under isoflurane and nitrous oxide anesthesia, we recorded ECOchG from the tympanic membrane, BAEP from the scalp needle, and facial muscle EMG from the mentalis muscle. During surgery, the body temperature was kept above 36.5 degrees C, and PaCO2 above 30 mmHg. In all cases, the peak N1 of ECOchG and wave I of BAEP had identical latencies throughout the monitoring period. The response was faster and the amplitude was higher in the ECOchG recordings. For calculation of the I-III or I-V interpeak latency of BAEP, the wave I of BAEP could be confirmed more quickly and precisely by the peak N1 of ECOchG. During tumor removal, the embedded facial nerve pathway in the tumor was identified by electric stimulation of the intracranial facial nerve, followed by evoked facial muscle EMG. Facial nerve function was confirmed by nerve traction or direct electric stimulation after total removal of the tumor. No facial palsy or other neurologic sequelae was found after the operations.

Adult↗

PubMed1992

Hemiparkinsonism in a patient with frontal meningioma.

We report on a 44-year-old woman with a right frontal meningioma, who presented with resting tremor, rigidity and bradykinesia in the left limbs. There were no other neurologic manifestations. A computed tomography scan demonstrated a huge high-density mass in the right frontal lobe and marked surrounding edema causing compression of the basal ganglia. Cerebral angiography showed a typical sunburst tumor stain and three feeding vessels from the bilateral middle meningeal arteries and the right callosomarginal artery. The pathologic diagnosis was transitional type meningioma. Before surgery, treatment with levodopa and bromocriptine was significantly effective in controlling hemiparkinsonism, which completely disappeared after surgical removal of the tumor. This outcome supports the notion that local compression due to edema may cause a functional disorder in the basal ganglia producing reversible contralateral parkinsonism.

Adult↗

PubMed1991

Expression of antibody Fab domains on bacteriophage surfaces. Potential use for antibody selection.

We describe a method for expressing an antibody Fab fragment on the surface of M13 filamentous bacteriophage. The L chain gene, preceded by an Escherichia coli signal sequence, is linked to the 5' end of the gene for the M13 major coat protein. A partial H chain gene, preceded by an E. coli signal sequence and truncated at the end of the CH1 region, is inserted on a plasmid adjacent to the fused L chain gene, so both genes are under the transcriptional control of an inducible promoter. The plasmid also contains the M13 origin of replication. When the promoter is induced, functional antibody Fab fragment appears on the surface of the E. coli inner membrane, as shown by specific binding to an Ag-affinity matrix. When the E. coli are further infected with a helper phage, allowing replication and packaging of the plasmid into phage particles, the resulting phage specifically bind to an Ag-coated plate, indicating they have antibody Fab fragment on their surface. The antibody-expressing phage can also be specifically bound to and eluted from an Ag-affinity column. These observations support the possibility of a new way of generating antibodies, in which amplified Ig cDNA from an appropriate B cell population is cloned into a suitable M13 vector, and phage containing the genes for desired antibodies are selected directly by binding to an Ag-affinity matrix.

Chromatography, Affinity↗

PubMed1991

A recombinant, membrane-acting immunotoxin.

The anti-Tac antibody is known to bind to the p55 chain of the human interleukin 2 receptor. An immunotoxin was produced by genetically linking Clostridium perfringens phospholipase C (PLC) to the Fab domain of anti-Tac. For this purpose, the PLC gene, with its own promoter and signal sequence, was fused to the 5' end of the VHCH1 segment of the anti-Tac heavy chain gene. The anti-Tac light chain gene, with an attached bacterial signal sequence, was made part of the same transcriptional unit. Escherichia coli transformed with the construct secreted a recombinant immunotoxin, anti-Tac(Fab)-PLC, in an active form. Anti-Tac(Fab)-PLC bound to cells expressing the interleukin 2 receptor and inhibited protein synthesis, with a 50% inhibitory concentration of 0.02 nM (1.8 ng/ml).

Amino Acid Sequence↗

PubMed1991

Acute post-traumatic intraventricular hemorrhage analysis of 25 patients with emphasis on final outcome.

A series of 25 patients suffering acute post-traumatic intraventricular hemorrhage (IVH) after closed head injury is reviewed. Post-traumatic IVH was associated with other brain lesion in most cases; intracerebral lesions with contusion, subdural hematoma, and epidural hematoma coexisted with post-traumatic IVH in ten, three, and one instance, respectively. In six cases, no CT abnormality other than IVH was noted. The final outcome in this series is poor, only 10 (40%) patients made a functional survival. Four different groups of IVH were proposed according to the CT scan findings: deep nuclei hemorrhage, brain stem injury, white matter hemorrhage and isolated IVH. The group of isolated IVH usually got a good outcome. The abnormal motor response, abnormal pupil reaction and impaired oculocephalic response were reliable parameters for poor prognosis.

Adolescent↗

PubMed1991

Abnormal muscle response in microvascular decompression of hemifacial spasm.

In 1976, Jannetta et al, suggested that microvascular compression caused by arteries and veins crossing the root entry zone of the facial nerve, was the major etiology of hemifacial spasm (HFS). Surgical treatment has become a major trend. Microvascular decompression (MVD) with teflon patches has a high cure rate. However, the possible occurrence of multiple vessel compression makes it difficult to decide which of these vessels are responsible for the symptom during operation. Recently, a method of abnormal EMG was elaborated upon by Møller and Jannetta in 1987, to ensure the quality of MVD intraoperatively. In this study, we report 6 cases who underwent the procedure successfully. After general anesthesia and muscle relaxation, the abnormal EMG was not suppressed. When the offending vessel was lifted up from the facial nerve, the abnormal EMG disappeared immediately. In each case, postoperative improvement of facial spasm correlated with intraoperative abnormal EMG changes. This method is not only able to guide the surgeon to the vessel that induces HFS but also guarantees the quality of MVD.

Adult↗