Search PubMed⌕ Search

Biomedical subjects

T Y Shih

Publications and source records attributed to T Y Shih.

79 records · Page 5Linked to original sources

The ras oncogene product p21 is not a regulatory component of adenylate cyclase.

Harvey (Ha-MSV) and Kirsten (Ki-MSV) murine sarcoma viruses induce tumours in animals and transform various cells in culture because of the expression of the ras oncogene product, p21 (ref. 1). Proto-oncogenes homologous with these genes are highly conserved evolutionarily and activated ras oncogenes have been detected in many human cancers. Whether c-ras oncogenes are directly responsible for human carcinogenesis is uncertain; however, it is clear that p21 mediates virus-induced transformation, although by an unknown mechanism. Epithelial and fibroblast cell lines transformed with Ha-MSV and Ki-MSV express p21 (ref. 8) and exhibit reduced adenylate cyclase activity. Like the guanine nucleotide regulatory proteins, Ns and Ni, which mediate stimulation and inhibition, respectively, of adenylate cyclase, p21 is a membrane-associated GTP binding protein, which exhibits GTPase activity. These similarities suggest that p21 and the adenylate cyclase regulatory proteins are related in cellular function, and that p21 depresses adenylate cyclase by inhibiting the activity of Ns or acting as Ni. We have therefore now examined the structural and functional similarities between p21 and Ns and Ni and find no evidence that p21 regulates adenylate cyclase activity by acting as one of these regulatory proteins.

Adenylyl Cyclases↗

[Amniotic band disruption complex: report of one case in twins].

Amniotic band disruption complex is a congenital disorder with the principal features vary from simple digital band constrictions to major craniofacial and visceral defects. Early amniotic rupture results in multiply affected infants who are frequently aborted or stillborn, whereas later rupture results primarily in limb involvement. Here we report a case of amniotic band disruption complex, a male infant (twin A) weighing 2350 gm with Apgar scores of 9 and 10 at one and five minutes. The second, third and fourth fingers on the left hand appeared to have ring constrictions, the distal part of the fourth finger had been amputated distally. There were amputations and ring constrictions of the distal parts of the second, third and fifth digits on the right hand, the fourth finger had only proximal third. All of the toes on the left foot had been amputated distally. The fifth toe on the right foot were absent, and the others had been partly amputated. Left cleft lip and palate were present with sunken left nasal flare. This baby underwent the cranial ultrasound examination, which demonstrated on structural anomalies, and both of the twins had the karyotype of 46XY. No other abnormalities was noted in the infant. The 890 gm placenta was delivered spontaneously. Two umbilical cords were present, each with normal vessels. The examination of the placenta revealed it to be dichorionic and diamniotic, and numerous fibrous strings extending form the fetal surface.

Amniotic Band Syndrome↗

Role of the Ha-ras (RasH) oncogene in mediating progression of the tumor cell phenotype (review).

Recent experimental evidence indicates that the c-Ha-ras (rasH) oncogene may be causally involved in the etiology and evolution of specific human neoplasms. In addition, cultured cells transformed by the rasH oncogene can induce both a tumorigenic and a metastatic phenotype when expressed in appropriate cultured cells. To begin to define the molecular and biochemical mechanism(s) by which the rasH oncogene induce their effects on expression of the transformed state we have employed a cloned rat embryo fibroblast (CREF) cell line. Transformation of CREF cells with wild-type 5 adenovirus (Wt) results in transformed cells which display anchorage-independence and an increased saturation density in monolayer culture, but are non-tumorigenic in both athymic nude mice and syngeneic Fischer rats. In contrast, when CREF cells are transformed with mutant type 5 adenoviruses, such as H5hrl, or the ElA transforming gene from hrl (0-4.5), tumors are induced in both nude mice and syngeneic rats. However, hrl (0-4.5)-transformed CREF cells are not metastatic following intravenous injection into the tail vein of syngeneic rats. Insertion of an activated T24 rasH oncogene or a wild-type v-rasH oncogene into CREF, wt-transformed CREF or hrl (0-4.5)-transformed CREF cells results in acquisition of a metastatic phenotype by these cells. A mutant v-rasH oncogene (mutant 116K), which is defective in GTP binding and the induction of transformation of NIH 3T3 cells, does not induce transformation in CREF cells, but it can progress wt-transformed CREF cells to a tumorigenic-non-metastatic state. Employing this model system which displays well-defined and stable stages in the tumor cell progression lineage, we have analyzed the potential role of changes in the phosphatidylinositol (PI) cycle and phospholipase A2 (PLA2) enzyme activity during progression to a tumorigenic and metastatic phenotype. An increase in PI cycle intermediates (primarily inositol triphosphate; IP3) were observed only in the wt-transformed and hrl (0-4.5)-transformed CREF cell lines transfected with the rasH oncogene. In the case of PLA2, all rasH-transformed CREF cell lines displayed increased activity. In contrast, CREF cells transformed only by Ad5 (Wt or hrl (0-4.5)) or the 116K v-rasH oncogene did not display increased PLA2 activity similar to that observed in rasH transfected cells. Since one important metabolite generated by PLA2 is arachidonic acid, which is converted into prostaglandins and leukotrienes by cyclooxygenase or lipooxygenase, respectively, the levels of prostaglandin E2 (PGE2) in the various cell lines were monitored.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

Effects of nebulized terbutaline on oxygen saturation in acute asthmatic children.

To evaluate the paradoxical effect of oxygen desaturation following beta-2 bronchodilator nebulization treatment in acute asthmatic children, a total of 47 patients, aged between 1.8 and 14 years, 27 males and 20 females, were studied. Twenty ml of nebulized normal saline (NS), followed by 10 mg (4 ml) of terbutaline sulphate solution (TSS) in 20 ml NS, were delivered by an ultrasonic nebulizer in 10 min to each patient through a connecting air tube placed in front of the nose and mouth. Oxygen saturation (SaO2) and pulse rate were monitored, using a pulse oximeter, before study and every two minutes until the end of the study. The clinical severity score and peak expiratory flow rate (PEFR) were checked before the study, at the end of inhalation of NS, and at the end of inhalation of TSS. SaO2 was increased both after nebulized NS and TSS when compared with the pre-study data (p < 0.05 and p < 0.0001, respectively). Twenty two cases (47%) during NS and 12 cases (25%) during TSS nebulization had SaO2 below the pre-study level. The mean decrease of SaO2 for the former was 1.62 +/- 0.95% (range: 1.00% to 4.26%), and 1.64 +/- 0.83% (range: 1.02% to 3.13%) for the latter (p > 0.9). No SaO2 decrease after nebulized TSS was observed in any of the seven severe asthmatic children with a prestudy SaO2 < or = 90%. The clinical severity score and PEFR were also significantly improved both after nebulized NS and TSS (p < 0.0001 and p < 0.001, respectively for NS, and both p < 0.0001 for TSS).(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Inhalation↗

[Fetus in fetu: report of a single case].

A five-year-old girl had been noted, since birth to have abdominal distension. There was no history of twinning or teratoma in the family. Physical examination discovered a 15 x 10 cm mass in the abdomen. Roentgenologic examination demonstrated the presence of an axial skeleton and long bones within the mass. MRI showed a retroperitoneal mass with components of cystic, bony and fatty tissues. When the mass was surgically removed from the retroperitoneal cavity, pathologic examination disclosed a parasitic fetus measuring 15.3 x 6.3 x 6.0 cm in size and suspended by a peduncle within a capsule. The fetus was covered with skin, sebaceous materials and black hair. There were bilateral and symmetric upper extremities with a flapper-like, deformed hand. No obvious genital organ was noted. Dissection of the midline, revealed a vertebral column with spinal cord. An atrophic skull bone containing cephalized glial tissue was noted. A thoracic cavity and scapular bone were found in the thoracic cage; however, no heart was noted. Gastrointestinal tract and kidney-like organs were seen within the abdominal cavity. Microscopically, there were glial tissues within the skull bone, spinal cord and vertebra. The upper extremities revealed two long bones surrounded by myxomatous and fibrous tissue. A well developed intestine and an ovary containing follicles with nearby lympy nodes were seen. The capsule showed fibrous tissue with calcification and hairs. It was distinguished from the teratoma by the presence of a vertebral axis and by an appropriate arrangement of other organs or limbs with respect to the axis, and corresponding to the generally recognized diagnostic criteria of fetus in fetu.

Abdominal Neoplasms↗