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Biomedical subjects

C Y Yu

Publications and source records attributed to C Y Yu.

51 records · Page 3Linked to original sources
PubMed1988

MR imaging of cavernous sinus involvement by pituitary adenomas.

The ability of high-resolution MR imaging (1.5 T) to detect invasion of the cavernous sinuses by pituitary adenoma was determined through a retrospective review of 74 patients. These patients were divided into three groups: 25 normal subjects, 24 subjects with invasive pituitary adenomas, and 25 subjects with noninvasive pituitary adenomas. A fourth group of 30 patients, who subsequently underwent surgery for pituitary adenoma, was evaluated prospectively by MR for the presence or absence of cavernous sinus invasion. Several features were analyzed: (1) the detectability of the medial and lateral dural margins of the cavernous sinus (2) the size and variation in intensity of compartments within the cavernous sinus (3) the relationship of endocrine function to the surgical and MR appearance of the cavernous sinus and (4) carotid artery displacement or encasement by tumor. The normal cavernous sinuses were usually symmetric, but their sizes varied. The lateral dural margin of the cavernous sinus was always recognized on MR as a linear, discrete, low-intensity area. The medial dural margin (pituitary capsule) was seen on MR in only two of the 25 normal patients. In all 24 patients with cavernous sinus invasion involvement was unilateral and was most common with laterally positioned prolactin or adrenocorticotropic hormone secretory adenomas. Invasion of the cavernous sinus was suspected by MR in only two of the 13 invasive microadenomas and was questionable in three. In 10 of the 11 macroadenomas with surgically proved dural invasion, MR demonstrated an asymmetric increase in size and intensity of the superior and inferior cavernous sinus compartments. Noninvasive macroadenomas compressed and displaced the cavernous sinus bilaterally. The prospective MR evaluation of 30 patients undergoing surgery for pituitary tumor revealed a sensitivity for predicting cavernous sinus invasion of 55%, a specificity of 85.7%, a positive predictive value of 62.5%, and a negative predictive value of 81.8%. No feature permitted certain distinction between invasive and noninvasive microadenomas, as the medial dural wall of the cavernous sinus could not be reliably identified. The most specific sign of cavernous sinus invasion was carotid artery encasement.

Adenoma↗
PubMed1987

Reduction of common carotid resistance upon stimulation of an area dorsal to the facial nucleus of cats.

In chloralose-urethane-anesthetized cats, electrical stimulation and glutamate injection on a small reticular area just dorsal to the facial nucleus (DFA) elicited an ipsilateral reduction in the common carotid resistance (CCR-reduction) with no or minimal change in other cardiovascular parameters. CCR-reduction was mediated via facial and glossopharyngeal nerves, involving partially muscarinic and partially non-muscarinic mechanisms.

Animals↗
PubMed1987

Molecular characterization of the HLA-linked steroid 21-hydroxylase B gene from an individual with congenital adrenal hyperplasia.

21-Hydroxylase deficiency which causes congenital adrenal hyperplasia is one of the most common defects of adrenal steroidogenesis. There are two 21-hydroxylase genes in man, A and B, and these have been mapped to the HLA class III region. Only the 21-hydroxylase B gene is thought to be active. To understand the molecular basis of congenital adrenal hyperplasia in a patient with the salt-wasting form of the disease, we cloned and characterized his single 21-hydroxylase B gene. The nucleotide sequence of this gene and a 21-hydroxylase B gene from a normal individual have been determined. Comparison of the two sequences has revealed 11 nucleotide alterations, of which two are in the 5' flanking region, four are in introns, one is in the 3' untranslated region and four are in exons. Two of the differences in exons cause codon changes, with Ser-269 and Asn-494 in the normal 21-hydroxylase B gene being converted to Thr and Ser, respectively. These amino acid substitutions may give an insight into those residues necessary for 21-hydroxylase enzymatic activity. We have also confirmed that the 21-hydroxylase A gene is a pseudogene due to three deleterious mutations in the exons. In addition, comparison of the 21-hydroxylase B gene sequence with other published sequences indicates that this microsomal cytochrome P-450 may be polymorphic.

Adrenal Hyperplasia, Congenital↗
PubMed1987

Definitive RFLPs to distinguish between the human complement C4A/C4B isotypes and the major Rodgers/Chido determinants: application to the study of C4 null alleles.

Definitive restriction fragment length polymorphisms (RFLPs) representing the exact locations responsible for isotypicity between the human complement components C4A and C4B, and their generally associated major Rodgers (Rg1) and Chido (Ch1) antigenic determinants, have been designed. By means of C4d-specific genomic probe for Southern blot analysis, a C4A gene can be defined by the presence of the 276 bp and 191 bp N1a IV fragments, while a C4B gene can be defined by a single 467 bp N1aIV fragment. In addition, an Rg1-expressing C4 gene can be represented by a 565 bp EcoO 109 fragment, and a Ch1-expressing C4 gene by a 458 bp EcoO 109 fragment, under the same conditions. All these polymorphic restriction fragments can be unambiguously and conveniently detected. In combination with the Taq I polymorphic patterns specific for the C4 loci and for the neighboring 21-hydroxylase genes, the nature and structure of the tandem C4,21-hydroxylase gene complex can be elucidated. In this study, it is inferred that the null allele of the HLA haplotype B44 DR6 C4A3 C4BQO is not a C4B allele, but probably encodes another C4A 3 allotype at the second C4 locus.

Alleles↗
PubMed1986

Structural basis of the polymorphism of human complement components C4A and C4B: gene size, reactivity and antigenicity.

The human complement components C4A and C4B are highly homologous proteins, but they show markedly different, class-specific, chemical reactivities. They also differ serologically in that C4A generally expresses the Rodgers (Rg) blood group antigens while C4B generally expresses the Chido (Ch) blood group antigens. C4A 1 and C4B 5 are exceptional variants which possess their class-specific chemical reactivities, but express essentially the reversed antigenicities. The genes encoding the typical Rg-positive C4A 3a and Ch-positive C4B 3 allotypes and the interesting variants C4A 1 and C4B 5 have been cloned. Characterization of the cloned DNA has revealed that the genes encoding the A 3a, A 1 and B 3 allotypes are 22 kb long, but that encoding B 5 is only 16 kb long. Comparison of derived amino acid sequences of the polymorphic C4d fragment has shown that C4A and C4B can be defined by only four isotypic amino acid differences at position 1101-1106. Over this region C4A has the sequence PCPVLD while C4B has the sequence LSPVIH, and this presumably is the cause of their different chemical reactivities. Moreover, the probable locations of the two Rg and the six Ch antigenic determinants have been deduced. Our structural data on the C4A and C4B polymorphism pattern suggests a gene conversion-like mechanism is operating in mixing the generally discrete serological phenotypes between C4A and C4B.

Amino Acid Sequence↗
PubMed1986

Molecular genetics of the fourth component of human complement.

The fourth component of human complement is encoded by two separate, but closely linked, loci, C4A and C4B, that have been positioned within the class III region of the HLA complex. While the two isotypes vary by only six amino acid residues, they differ significantly in haemolytic activity. Both loci are considerably polymorphic and this may be biologically relevant to ensure interaction with a wide range of pathogens. The number of C4 genes expressed is polymorphic as null alleles, total deficiency and duplication has been shown based on protein studies. Southern analysis of 24 different haplotypes with either C4A or C4B null alleles using the C4 probes showed that three of the null alleles were due to deleted genes but the majority appeared normal. A cosmid library was prepared from DNA of one of the deleted haplotypes and the region of deletion analysed by restriction mapping.

Alleles↗
PubMed1986

Improved methods of direct and cultured chromosome preparations from chorionic villous samples.

A new method is described for preparing direct mitotic chromosome spreads from chorionic villous samples, which has resulted in sufficiently high yields of well-banded metaphases to permit a complete standard chromosomal diagnosis in 20 of 20 cases. A method of establishing monolayer cultures from this material that can be harvested from 3 to 7 days after initiation is also presented.

Cells, Cultured↗
PubMed1985

Polymorphism of human complement component C4.

An assessment has been made of the polymorphism of human complement component C4 by comparing derived amino acid sequences of cDNA and genomic DNA with limited amino acid sequences. In all, one complete and six partial sequences have been obtained from material from three individuals and include two C4A and two C4B alleles. Differences were found between the 4 alleles from 2 loci in only 15 of the 1722 amino acid residues, and 12 lie within one section of 230 residues, which in 1 allele also contains a 3-residue deletion. In three variable positions, an allelic difference in one C4 type was common to the other types. Three nucleotide differences were found in four introns. In spite of marked differences in their chemical reactivity, the many allelic forms appear to differ in less than 1% of their amino acid residue positions. This unusual pattern of polymorphism may be due to recent duplication of the C4 gene, or may have arisen by selection as a result of the biological role of C4, which interacts in the complement sequence with nine other proteins necessitating conservation of much of the surface structure.

Amino Acid Sequence↗
PubMed1985

Expression of T4 early genes 62, 44, 45 and 46 in the lambda-T4 recombinant phage lambda 806-17.

A lambda-T4 recombinant phage, lambda 806-17, which carries the T4 early genes 62, 44, 45 and 46, was studied inside a homoimmune lysogen. Under such conditions, gene expression from the lambda promoters is represented. Results showed extensive expression of gene 46, and significant expression of genes 62 and 45. The expression of these early T4 genes is presumed to depend on T4 promoters included in the cloned fragment. A new promoter proximal to gene 46 is implicated. The results also indicate that the extent of gene expression, in terms of complementation, increases with the time allowed for expression.

Escherichia coli↗
PubMed1978

Mosaic autosomal trisomy in cultures from spontaneous abortions.

In a consecutive series of 592 karyotyped spontaneous abortions, ten of 103 autosomal trisomies were mosaic, with a normal cell line also present. The frequency of mosaicism (10%) is much higher than that reported in Down syndrome, but similar to that reported in amniotic fluid cultures and in induced abortions. The most likely explanations for this discrepancy are (1) previous underestimation of mosaicism in live births or (2) mosaicism which is often restricted to extraembryonic fetal tissue.

Abortion, Spontaneous↗
PubMedDate not supplied

MR appearance of umbilical endometriosis.

OBJECTIVE: We describe the MR appearance of endometriosis involving the umbilicus in two patients. One patient had a history of laparoscopy performed through the umbilicus; the other had an umbilical hernia. MATERIALS AND METHODS: MR imaging was performed using both a body coil and a spine coil (with the patient lying prone on the spine coil). The lesions were surgically removed and their MR appearance was correlated with the results of histologic analysis. RESULTS: The lesions were well delineated on MRI and showed evidence of prior hemorrhage consistent with endometriosis. Both lesions were shown to be endometriosis at surgical pathology. CONCLUSION: MR imaging was useful for delineating the size and location of the lesions and excluding intraabdominal extension.

Adult↗
PubMedDate not supplied

Emergency endoscopic nasobiliary drainage for acute calculous suppurative cholangitis and its potential use in chemical dissolution.

Acute suppurative cholangitis is one of the common causes of acute abdomen in Taiwan. Emergency decompression is a life-saving procedure if patients fail to respond to antibiotic treatment. From July 1988 to June 1991, 224 patients were encountered with concomitant bile duct stones and cholangitis; 40 were brought to the emergency service with shock or mental confusion or responded poorly to antibiotic treatment. The patients consisted of 20 males and 20 females aged 21-81 years (mean age 64 years); 55% had intrahepatic duct stones, 50% had positive blood culture, 38% had undergone previous biliary surgery, 25% had concomitant medical illnesses and 20% presented with mental confusion. Emergent endoscopic nasobiliary drainage (ENBD) was performed within 48 h of each patient's arrival in the emergency room. In 3 days all the patients exhibited significant improvement as defined by body temperature, vital signs, white blood cell count, serum bilirubin and alkaline phosphates levels. When their condition had stabilized, 21 patients underwent elective surgery. Six patients received ethylenediaminetetraacetic acid infusion through an ENBD tube. Two of the patients' stones dissolved completely. Six patients received papillotomy with stone removal. The remaining patients refused further treatment. There was no hospital mortality. It is therefore concluded that ENBD offers an effective treatment for acute calculus suppurative cholangitis and it is a potential route of administration for the chemical dissolution of bile duct stones.

Abdomen, Acute↗