Gas-CT cisternography for the diagnosis of small acoustic neuroma.
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Adult↗
Biomedical subjects
Y S Tang
Publications and source records attributed to Y S Tang.
Evaluation of free flaps transferred by microvascular anastomosis in oral and maxillofacial surgery.
The authors discuss indications for the use of microvascular free flaps transferred to the oral and maxillofacial region. A series of 139 cases, involving 145 free flaps, is reported over a three year period. The overall success rate for all types of flaps was 89.3%. Advantages and disadvantages of the use of various flaps are presented and suggestions are offered to avoid complications.
Adolescent↗
Immunological and immunochemical studies of ascitic fluid antibodies in mice immunized with spring-summer encephalitis virus.
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Animals↗
Biological and chemical monitoring of occupational exposure to ethylene oxide.
Studies were carried out on two populations occupationally exposed to ethylene oxide (EtO) using different physical and biological parameters. Blood samples were collected from 9 hospital workers (EI) and 15 factory workers (EII) engaged in sterilization of medical equipment with EtO and from matched controls (CI and CII). Average exposure levels during 4 months (the lifespan of erythrocytes) prior to blood sampling were estimated from levels of N-(2-hydroxyethyl)valine adducts in hemoglobin. They were significantly enhanced in EI and EII and corresponded to a 40-h time-weighted average of 0.025 ppm in EI and 5 ppm in EII. Exposures were usually received in bursts with EtO concentrations in air ranging from 22 to 72 ppm in EI and 14 to 400 ppm in EII. All samples were analyzed for HPRT mutants (MFs), chromosomal aberrations (CAs), micronuclei (MN) and SCEs. MFs were significantly enhanced by 60% in EII but not in EI. These results are the first demonstration of mutation induction in man by ethylene oxide. CAs were significantly enhanced in EI and EII by 130% and 260% respectively. MN were not enhanced in EI but significantly in EII(217%). The mean frequency of SCEs was significantly elevated by 20% in EI and by almost 100% in EII. SCE was the only parameter that allowed distinction between daily and occasionally exposed workers in EII. An interesting finding in exposed workers was the large increase of the percentage of cells with high frequencies of SCE (3-4 times in EI and 17-fold in EII). The relative sensitivity of endpoints for detection of EtO exposure in the present investigation was in the following order: HOEtVal adducts greater than SCEs greater than chromosomal aberrations greater than micronuclei greater than HPRT mutants.
Adult↗
Hydroxyethylation of hemoglobin by 1-(2-chloroethyl)-1-nitrosoureas.
Following treatment of cancer patients with three 1-(2-chloroethyl)-1-nitrosoureas, hemoglobin was isolated and analyzed by GC-MS for N-(2-hydroxyethyl)-N-terminal valine. This alkylated amino acid was liberated as a (pentafluorophenyl)thiohydantoin from the hemoglobin by a modified Edman degradation procedure. Following intravenous infusion of fotemustine [diethyl[1-[3-(2-chloroethyl)-3-nitrosoureido]ethylphosphonate] (ca. 90 mg/m2) the levels of (hydroxyethyl)valine in two patients increased steadily, reaching a peak of ca. 300 pmol/g after 6 h. In a further five patients receiving fotemustine (100 mg/m2) alkylation levels 24 h after treatment ranged from 132 to 1524 pmol/g of globin. Treatment with TCNU [1-(2-chloroethyl)-3-[2-[(dimethylamino)sulfonyl]ethyl]-1- nitrosourea] or ACNU [1-[(4-amino-2-methylpyrimidin-5-yl)methyl]-3-(2-chloroethyl)-3- nitrosourea] resulted in similar increases in (hydroxyethyl)valine in hemoglobin, although the amounts (as with fotemustine) showed considerable interindividual variation. It appears that the measurement of (hydroxyethyl)valine in hemoglobin may be a suitable monitor of exposure to hydroxyethylating agents during (chloroethyl)nitrosourea chemotherapy.
Alkylation↗
Dynamic CT of the laterosellar extradural venous spaces.
We evaluated the ability of dynamic CT scanning to accurately demonstrate the laterosellar extradural venous spaces. Careful examination of 680 consecutive patients with this technique has permitted us to describe four main venous groups: the veins of the lateral wall (present in 98% of cases), the vein of the inferolateral group located beneath cranial nerve VI (present in 92% of cases), the medial vein located between the internal carotid artery and the pituitary gland (present in 20-30% of cases), and the vein of the carotid sulcus located between the intracavernous internal carotid artery and the lateral wall of the sphenoid bone (present in 65% of cases). The vein of the carotid sulcus is absent only when the internal carotid artery lies close to the sphenoid bone. In 12 patients with suspected cavernous sinus invasion, dynamic CT scanning demonstrated obliteration of the vein of the carotid sulcus. In five patients with huge tumors of the temporal region, dynamic CT scanning of the cavernous sinus permitted demonstration of normal laterosellar extradural venous spaces, thus permitting exclusion of intracavernous sinus invasion. We believe dynamic CT is the imaging technique best suited for studying the laterosellar extradural venous spaces. Its spatial resolution and dynamic capacity make it superior to MR, and it should be the first procedure when invasion of the cavernous sinus by a pituitary tumor is suspected.
Adenoma↗
CT in diagnosis of acoustic neuromas.
A detailed analysis of the CT findings in 75 cases of acoustic neuroma is presented. The method of examination included plain and enhanced CT, metrizamide CT cisternography (M-CTC), and gas CT cisternography (gas-CTC). The common CT appearances of acoustic neuromas were as follows: 93.6% appeared as isodense or hypodense on precontrast scan; homogeneous enhancement was observed in 53.8% on postcontrast scan; the tumor center, mostly located at the level of the internal acoustic canal, was spherical in shape with an acute angle between the lateral tumor border and petrous bone; and there was widening of the internal acoustic canal or destruction of petrous bone. However, the presence of an acoustic neuroma could not be excluded if widening of the internal acoustic canal was absent. It was not certain whether contrast filling of the internal acoustic canal occurred at M-CTC in the four cases so examined. One case of intracanalicular neuroma was diagnosed by gas-CTC, which is the most sensitive and reliable technique for detecting and excluding small tumors. The significance of various CT appearances, early diagnosis, and differential diagnosis of acoustic neuroma from other cerebellopontine-angle tumors, particularly meningioma, are discussed.
Adolescent↗