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Biomedical subjects

W C Cheng

Publications and source records attributed to W C Cheng.

At least 55 records · Page 3Linked 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↗
PubMed1992

Outcome of cryopreservation and subsequent programmed replacement of frozen-thawed embryos in an in vitro fertilisation programme: preliminary report and proposals for improvement.

In order to prevent wastage of good quality embryos and limit the number transferred in fresh in vitro fertilisation (IVF) cycles, 577 supernumerary embryos were cryopreserved for a mean duration of 6.23 +/- 4.7 months (range 1-24). Four hundred and twenty-two have been thawed so far of which 81 (19.19%) were totally lysed, 317 (75.12%) survived with at least 50% of their blastomeres intact and 180 (42.65%) cleaved. Two hundred and sixteen frozen-thawed embryos have been transferred in 62 stimulated and 11 natural cycles involving 61 patients. The mean number of embryos transferred per cycle was 2.96 +/- 0.86. Twenty-one pregnancies resulted from the 62 stimulated cycles (33.87%). No pregnancy occurred in the 11 natural cycles. Overall pregnancy rate was therefore 28.77%. Eleven singletons (eight male; three female) and one set of twins (one male one female) have so far been delivered in good condition:- six (54.5%) by caesarean section, five (45.5%) vaginally, including one by Neville Barnes forceps, one ventouse and the rest were spontaneous. Presentation was cephalic in 10 (91%) and breech in one case (9%). All were delivered at term except one premature (9%). Mean birth weight was 3.23 +/- 0.32 kg for singletons and 2.7 kg for the twins. Despite the diversity of racial, cultural and religious differences in our multinational patient population, we found embryo cryopreservation following IVF generally acceptable and our preliminary results are quite encouraging. Strategies for improving the outcome of future cycles are proposed.

Cryopreservation↗
PubMed1992

Vertebrobasilar insufficiency related to cervical spondylosis. A case report and review of the literature.

A 64-year-old man suffered from symptoms of vertebrobasilar insufficiency (VBI) while turning his head to the left. Roentgenograms of the cervical spines showed severe spondylosis. Cerebral angiography demonstrated compression of the left vertebral artery by osteophytes of the cervical spine when the patient turned his head to the left. He was treated surgically by fixation of the vertebral bodies with good relief of symptoms during one year of follow-up. VBI induced by spondylotic compression of the vertebral artery is uncommon. We therefore reviewed the literature and suggested a more simple method of operation.

Cervical Vertebrae↗
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↗
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

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↗
PubMed1986

Bacterial agglutination and polyacrylamide gel electrophoresis for typing Clostridium difficile.

Bacterial agglutination and polyacrylamide gel electrophoresis (PAGE) were methods evaluated for typing strains of Clostridium difficile. A panel of four antisera, obtained by immunizing rabbits with washed whole cells of different strains of C. difficile, produced distinctive patterns of agglutination. Ethylenediaminetetraacetate (EDTA) extracts subjected to PAGE also produced distinctive protein profiles. Excellent correlation between the two methods was observed when geographically distant isolates were typed without knowledge of their clinical origin. Both typing methods should receive further evaluation for their value as tools for epidemiological studies.

Agglutination Tests↗
PubMed1985

Characterization of antigenic components of immune complexes isolated from a melanoma patient.

Immune complexes (IC) from the serum of a melanoma patient were partially purified with DEAE Affigel Blue. The IC were radioiodinated and then immobilized with activated Sepharose 4B. Immunologically bound components in the IC were dissociated with 3M MgCl2 followed by gel filtration chromatography. A distinct antigen component of about 700,000 daltons was obtained by refractionation of a region of the chromatogram containing antigenic activity by Sephacryl S-300 column chromatography. Though the antigenic component behaved as a single entity in the gel filtration, it consisted of at least five polypeptide chains that were revealed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing conditions. However, 92,000 and 41,000 dalton subunits were predominant. This procedure may be useful for isolating tumor antigens from circulating IC of cancer patients.

Antigen-Antibody Complex↗
PubMed1975

Fractionation and characterization of surface antigens from group A Neisseria meningitidis.

Group A meningococcal surface components were first subjected to fractionation with a mixture of chloroform-methanol. Sodium dodecyl sulfate-acrylamide gel electrophoresis of the aqueous phase containing 30 to 40% of the original material revealed only two polypeptide components and a slowly migrating carbohydrate component. The soluble fraction of the interphase was found to contain most of the bacterial surface proteins and the chloroform-methanol phase essentially all of the lipid components. The components of the aqueous phase were further fractionated by use of the hydrophobic affinity column, 4-phenylbutylamino-Sepharose and gradient elution with NaCl to yield fractions I and II. Fraction II was further separated into a minor and a major component (IIb) with Sepharose G-200. Fraction I contained the group A polysaccharide in ionic linkages with a minor polypeptide component (6%). It elicited bactericidal antibodies in rabbits and protected mice against homologous challenge, whereas the polysaccharide alone was non-immunogenic in these animals. Fraction IIb was a polysaccharide-polypeptide complex with unknown linkages; it induced a low concentration of rabbit antibodies that were bactericidal to group A and C meningococci. Mice vaccinated with fraction IIb were most resistant to homologous challenge and the resistance was also extended to challenges with group B and C cells. Fractions I and IIb appeared to be useful alternatives to the currently employed group-specific polysaccharide vaccines for the protection against drug-resistant meningococci. A simplified procedure for the preparation of group-specific polysaccharide was presented.

Amino Acids↗