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Biomedical subjects

C N Chang

Publications and source records attributed to C N Chang.

At least 91 records · Page 5Linked to original sources
PubMed1991

Clinical manifestations of acute rejection in renal allograft recipients receiving cyclosporin-A therapy.

Cyclosporin-A-treated renal allograft recipients have demonstrated an improved graft survival rate, when compared to that of patients treated with conventional azathioprine and steroid therapy. Cyclosporin-A has been used for immunosuppressive therapy after renal transplantation at the National Taiwan University Hospital since November 1985. Since then, the one-year graft survival rate has been 78%, and the patient survival rate is 91%. At our service, acute rejection is confirmed mainly by an increase in the serum creatinine level of 0.5 mg% per day and a subsequent return of kidney function to normal after pulse steroid therapy. Twenty patients receiving cyclosporin-A and suffering from acute rejection episodes were chosen for comparison with 18 patients receiving conventional azathioprine and steroid therapy. Compared to conventional therapy, the classical systemic manifestations of rejection, such as malaise, lethargy, apathy, general weakness, vague discomfort, increase in body weight, swelling of graft with tenderness, were all more mild and less frequent in the cyclosporin-A-treated group. Episodes of rejection appeared earlier and the duration of rejection was shorter than in those of the conventional group. The urinary sodium concentration and the ratio of urine urea nitrogen to blood urea nitrogen were reliable references during the acute rejection episode in the conventional group, but it cannot be used as indices in the cyclosporine group. These findings can help us understand the changes which occurred in acute rejection in patients who receive renal transplantation during the cyclosporine era.

Adult↗
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

The outcome of delayed graft function in cadaveric renal transplants treated with low dose cyclosporine.

Thirty-three consecutive cadaveric renal transplantations performed at the National Taiwan University Hospital from November 1985 to December 1989 were reviewed to determine the effect of early function on the 1-year patient and graft survival rates. Immediate function was present in 17 transplants; delayed graft function with acute tubular necrosis occurred in 16 cases. The 16 transplants with acute tubular necrosis (ATN) were treated with low dose cyclosporine. Among them, 13 patients had delayed function which resolved after 2 to 60 days of hemodialysis, but 3 grafts did not regain function. The allograft survival rate at 1-year was 68.7% for the delayed function group and 88.2% for the immediate function group. This difference was not statistically significant (p greater than 0.05). The 1-year patient survival rate was also not significantly different (87.5% vs 88.2%). There was no relationship between graft loss and duration of ATN. However, the graft survival rate in patients with a serum creatinine level below 2 mg/dL, after recovery either from ATN or non-ATN, was better than that for patients with a serum creatinine level of more than 2 mg/dL. The difference was statistically significant (95.8% vs 50.0%, p less than 0.02). It is concluded that delayed allograft function with acute tubular necrosis does not significantly alter the 1-year survival rates of patients and grafts in low-dose cyclosporine therapy. However, it is deleterious to the 1-year survival rate of an allograft when poor functional recovery occurs in an ATN or non-ATN condition.

Adult↗
PubMed1991

Aneurysmal subarachnoid hemorrhage. Report of 219 cases in Chang Gung Memorial Hospital.

Two hundred and nineteen cases with aneurysmal subarachnoid hemorrhage treated at Chang Gung Memorial Hospital from January 1986 to December 1989 were studied. Their ages ranged from 19 to 76, with a mean of 55 +/- 16 years. About one third of the cases occurred in the age group of 50 to 59 years. Females were predominant with a female to male ratio of 2:1, but there was a male predominance below age 40. The most common site of aneurysm was the anterior communicating artery. Rebleeding, delayed vasospasm with cerebral infarction, and hydrocephalus were the main causes of death or disability. The mean follow-up of 6 months for the whole group showed a 59% favorable outcome, 13% severe disability and a 28% mortality. For those 166 patients who underwent surgical treatment, there was 8% mortality.

Adult↗
PubMed1990

Facial bone fracture associated with carotid-cavernous sinus fistula.

Out of 989 cases of facial bone fracture, ten patients had carotid-cavernous sinus fistulas (1.01%). Their ages ranged from 25 to 48 years. Seven were male and three female. Two of the ten patients had lower third, three patients had middle third, three patients had upper third, and two patients had combined middle and lower third facial bone fractures. The signs and symptoms of a fistula appeared from the first postinjury day up to 50 days after the injury (mean, 21 days). Four patients had symptoms after operation for facial bone fracture. Most fistulae were identified by arteriography before treatment. Followup ranged from 1 year, 8 months, to 5 years, 9 months (mean, 2 years, 9 months). One patient had a malocclusion. Nine patients had complete resolution of their bruits. Complications included unilateral complete visual loss (two), CSF rhinorrhea (two), and stroke in one of the two CSF rhinorrhea patients. One patient expired due to a severe head injury, and there was one death from an unrelated cause.

Adult↗
PubMed1990

Early postoperative seizures after posterior fossa surgery.

A review is reported of the seizure incidence in 726 patients who underwent 740 posterior fossa operations via a suboccipital craniectomy without prophylactic anticonvulsant agents. Thirteen patients (1.8%) experienced seizures within 2 weeks postoperatively. Five of these patients (0.7% of the series) had seizures within 24 hours after operation. The incidence was highest for patients with medulloblastoma (7.2%) followed by those with astrocytoma (2.3%). Also, a higher percentage was found in patients with preoperative ventriculoperitoneal shunt or intraoperative ventriculostomy (2.7%) than in those without (1%), but the difference was not statistically significant. Metabolic acidosis (80%) and hyponatremia (20%) were the major causes of the seizures that developed within 24 hours after operation. Follow-up computerized tomography showed no definite lesion in these patients. Hydrocephalus (75%) and supratentorial hemorrhage remote from the operative site (25%) were detected in the patients who developed seizures between the 2nd and 14th postoperative day. Two of these patients also had postoperative bacterial meningitis. This review suggests that seizures are a possible complication in the early postoperative period after suboccipital craniectomy for posterior fossa lesions.

Adolescent↗
PubMed1990

Features of head injury in a developing country--Taiwan (1977-1987).

Certain features of head-injured patients admitted to the Chang Gung Memorial Hospital in Taiwan during the period 1977 to 1987 were reviewed. The most common causes of injury were motorcycle accidents (56.3%) and street accidents with pedestrian injury (29.47%). The age groups with the greatest incidence of injury were aged 16-20 years, 21-25 years, and 25-30 years. The pedestrian group involving the highest incidence of injury was less than 10 years of age. Overall mortality was 17.26%. The injured pedestrian group had the highest mortality (19.1%). Initial clinical assessment was recorded using the Glasgow Coma Scale. Head-injured patients with a GCS less than 8 had a mortality in the injured pedestrian group of 46%, whereas the mortality rate in the motorcycle accident group was 41%. Additional features studied were time of occurrence of injury and pattern of injury. Information gathered from this study would suggest the need to establish a Head Injury Prevention Program in Taiwan. This of course implies major cooperation among the providers of health care delivery, the medical profession, legislators, and the government at all levels.

Adolescent↗
PubMed1990

[Median nerve somatosensory evoked potential monitoring during carotid endarterectomy-report of one case].

Carotid endarterectomy was performed on a 64 y/o female patient who had been suffering from multiple transient ischemic attacks caused by the stenosis of right common carotid artery at its bifurcation. Median nerve somatosensory evoked potential (SSEP) was utilized for monitoring cerebral function during and after operation. Latency, amplitude and central conduction time (CCT) of bilateral N13 (CV2) and N20 (C3', C4') were measured as an aid for management of anesthesia, surgical procedure and postoperative care. The results showed SSEP which is sensitive for detection of cerebral ischemia and could help the surgeon and anesthesiologist maintaining optimal cerebral perfusion, but yields little information about postoperative hyperperfusion state. Besides evaluating the efficacy of SSEP, we discussed the problems encountered during the SSEP monitoring.

Carotid Arteries↗
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

Mechanism of DNA cleavage and substrate recognition by a bovine apurinic endonuclease.

The location of the phosphodiester bond cleaved by homogeneous Mg2+-dependent apurinic endodeoxyribonuclease (EC 3.1.25.2; APE) of bovine calf thymus has been determined by using a 21-mer oligonucleotide containing a single central apurinic site as a substrate. A single product of cleavage consistent with cleavage of the oligonucleotide 5' to the apurinic site, and leaving a 3' hydroxyl group, was identified. This enzyme is, therefore, a class II apurinic endonuclease. The substrate specificities of this enzyme have been determined by using a variety of natural and synthetic DNAs or oligonucleotides containing base-free sites. Calf thymus APE has an absolute requirement for a double-stranded DNA and requires an abasic site as a substrate. The presence of a base fragment such as a urea residue, an alkoxyamine group attached to the C'-1 position of the abasic site, or reduction of the C'-1 aldehyde abolishes the APE activity of this enzyme. Synthetic abasic sites containing either ethylene glycol, propanediol, or tetrahydrofuran interphosphate linkages are excellent substrates for bovine APE. These results indicate that APE has no absolute requirement for either ring-opened or ring-closed deoxyribose moieties in its recognition of DNA-cleavage substrates. The enzyme may interact with the pocket in duplex DNA that results from the base loss or with the altered conformations of the phosphodiester backbone that result from the abasic site.

Amines↗
PubMed1989

NMR studies of abasic sites in DNA duplexes: deoxyadenosine stacks into the helix opposite acyclic lesions.

Proton and phosphorus NMR studies are reported for two complementary nonanucleotide duplexes containing acyclic abasic sites. The first duplex, d(C-A-T-G-A-G-T-A-C).d(G-T-A-C-P-C-A-T-G), contains an acyclic propanyl moiety, P, located opposite a deoxyadenosine at the center of the helix (designated APP 9-mer duplex). The second duplex, d(C-A-T-G-A-G-T-A-C).d(G-T-A-C-E-C-A-T-G), contains a similarly located acyclic ethanyl moiety, E (designated APE 9-mer duplex). The ethanyl moiety is one carbon shorter than the natural carbon-phosphodiester backbone of a single nucleotide unit of DNA. The majority of the exchangeable and nonexchangeable base and sugar protons in both the APP 9-mer and APE 9-mer duplexes, including those at the abasic site, have been assigned by recording and analyzing two-dimensional phase-sensitive NOESY data sets in H2O and D2O solution between -5 and 5 degrees C. These spectroscopic observations establish that A5 inserts into the helix opposite the abasic site (P14 and E14) and stacks between the flanking G4.C15 and G6.C13 Watson-Crick base pairs in both the APP 9-mer and APE 9-mer duplexes. The helix is right-handed at and adjacent to the abasic site, and all glycosidic torsion angles are anti in both 9-mer duplexes. Proton NMR parameters for the APP 9-mer and APE 9-mer duplexes are similar to those reported previously for the APF 9-mer duplex (F = furan) in which a cyclic analogue of deoxyribose was embedded in an otherwise identical DNA sequence [Kalnik, M. W., Chang, C. N., Grollman, A. P., & Patel, D. J. (1988) Biochemistry 27, 924-931]. These proton NMR experiments demonstrate that the structures at abasic sites are very similar whether the five-membered ring is open or closed or whether the phosphodiester backbone is shortened by one carbon atom. Phosphorus spectra of the APP 9-mer and APE 9-mer duplexes (5 degrees C) indicate that the backbone conformation is similarly perturbed at three phosphodiester backbone torsion angles. These same torsion angles are also distorted in the APF 9-mer but assume a different conformation than those in the APP 9-mer and APE 9-mer duplexes.

Base Composition↗
PubMed1989

Prophylactic anticonvulsants for prevention of immediate and early postcraniotomy seizures.

Phenytoin (15 mg/kg) was administered intravenously to 189 patients shortly before their intracranial, supratentorial surgery was completed. Intravenous phenytoin of 5-6 mg/kg/day in three divided doses was administered daily for the first 3 postoperative days. Therapeutic serum levels (10-20 micrograms/mL) were achieved in 113 (59.8%) patients. An equally constituted, randomized control group of 185 patients received a placebo under identical conditions. The group receiving phenytoin had only one immediate and two early postoperative seizures. The 185 controls had four immediate and nine early postoperative seizures. None of the follow-up computed tomography scans of the patients with seizures showed postoperative hematoma. One patient had a significant tension pneumocranium, a possible cause of postoperative seizures. To avoid a decrease in the serum anticonvulsant level due to intraoperative blood loss, it is suggested that for patients who need an urgent or emergent craniotomy, prophylatic anticonvulsant medication should be given at least 20 minutes before completion of wound closure.

Adult↗
PubMed1989

Influence of abasic and anucleosidic sites on the stability, conformation, and melting behavior of a DNA duplex: correlations of thermodynamic and structural data.

We report a complete thermodynamic characterization of the impact of abasic and anucleosidic lesions on the stability, conformation, and melting behavior of a DNA duplex. The requisite thermodynamic data were obtained by using a combination of spectroscopic and calorimetric techniques to investigate helix-to-coil transitions in a family of DNA duplexes of the form d(CGCATGAGTACGC).d(GCGTACXCATGCG), where X corresponds to a thymidine residue in the parent Watson-Crick duplex and to an abasic or anucleosidic site in the modified duplexes. The data derived from these studies reveal that incorporation of an abasic site into a DNA duplex dramatically reduces the duplex stability, transition enthalpy, and transition entropy. The magnitudes of these lesion-induced effects are greater than one would expect based on simple nearest-neighbor considerations. Nearly identical thermodynamic data are obtained when the modified duplex contains an anucleosidic site rather than an abasic site. This observation suggests that the thermodynamic impact of these lesions primarily results from removal of the base rather than the sugar ring. Significantly, the melting cooperativities of the abasic and anucleosidic derivatives are identical with each other and with the corresponding unmodified Watson-Crick parent duplex. This result suggests that the phosphodiester backbone, rather than the base-sugar network, serves as the primary propagation path for the communication of cooperative melting effects. We propose molecular interpretations for the thermodynamic data based on the structural picture that has emerged from the NMR studies of Patel and coworkers on the same family of modified and unmodified DNA duplexes [Kalnik, M.W., Chang, C.-N., Grollman, A.P. & Patel, D.J. (1988) Biochemistry 27, 924-931].

Apurinic Acid↗
PubMed1988

NMR studies of abasic sites in DNA duplexes: deoxyadenosine stacks into the helix opposite the cyclic analogue of 2-deoxyribose.

Proton and phosphorus NMR studies are reported for the complementary d(C-A-T-G-A-G-T-A-C).d(G-T-A-C-F-C-A-T-G) nonanucleotide duplex (designated APF 9-mer duplex) which contains a stable abasic site analogue, F, in the center of the helix. This oligodeoxynucleotide contains a modified tetrahydrofuran moiety, isosteric with 2-deoxyribofuranose, which serves as a structural analogue of a natural apurinic/apyrimidinic site [Takeshita, M., Chang, C.N., Johnson, F., Will, S., & Grollman, A.P. (1987) J. Biol. Chem. 262, 10171-10179]. Exchangeable and nonexchangeable base and sugar protons, including those located at the abasic site, have been assigned in the complementary APF 9-mer duplex by recording and analyzing two-dimensional phase-sensitive NOESY data sets in H2O and D2O solution at low temperature (0 degrees C). These studies indicate that A5 inserts into the helix opposite the abasic site F14 and stacks with flanking G4.C15 and G6.C13 Watson-Crick base pairs. Base-sugar proton NOE connectivities were measured through G4-A5-G6 on the unmodified strand and between the base protons of C15 and the sugar protons of the 5'-flanking residue F14 on the modified strand. These studies establish that all glycosidic torsion angles are anti and that the helix is right-handed at and adjacent to the abasic site in the APF 9-mer duplex. Two of the 16 phosphodiester groups exhibit phosphorus resonances outside the normal spectral dispersion indicative of altered torsion angles at two of the phosphate groups in the backbone of the APF 9-mer duplex.

Base Sequence↗
PubMed1988

Brain abscess after dilatation of esophageal stricture.

Two children, below 15 years of age, developed brain abscesses after esophageal dilation. They were among 40 children treated for supratentorial brain abscesses during the past 10 years. Pus culture of one of the abscesses was peptostreptococcus, which is a common oropharyngeal flora. Clinicians should be aware of this complication since the prognosis is usually satisfactory after prompt treatment.

Brain Abscess↗