PubMed Health⌕ Search

Biomedical subjects

G C Lin

Publications and source records attributed to G C Lin.

46 records · Page 3Linked to original sources
PubMed1991

Effects of individual genetic substitutions of arginine residues on the deprotonation and reprotonation kinetics of the Schiff base during the bacteriorhodopsin photocycle.

The rates are determined for the deprotonation and reprotonation of the protonated Schiff base (PSB) as well as of formation and decay of the UV transient in the photocycle of seven bacteriorhodopsin (bR) mutants in which Arg-7, 82, 164, 175, 225, or 227 are replaced by glutamine and Arg-134 by cysteine. The results show that all these mutations increase the rate of deprotonation of the PSB compared to ebR, (wild-type bacteriorhodopsin expressed in Escherichia coli) greatly increase the rate of the reprotonation of the SB (Schiff base) in the case of the Arg-164 and Arg-175 mutations and dramatically decrease this rate in the case of the Arg-227 mutation. Temperature studies on the latter mutant suggest that the observed change in its rate of reprotonation is due to large decrease in the energy and entropy of activation, similar to those observed for Asp-96 mutations (Miller, A. and D. Orsterhelt. 1990. Biochim. Biophys. Acta. 1020:57-64). These results suggest that the reprotonation process is changed to a proton diffusion-controlled mechanism in the Arg-227 mutant due to a change in the structure of the proton channel. The absorption intensity ratio (AUV/AMslow) of each arginine mutant relative to that of ebR is found to be similar to that for native purple membrane (PM) except for the Arg-227 mutant where it is greatly reduced, and for the Arg-82 mutant where it is not observed, suggesting that both Arg-227 and Arg-82 residues somehow play roles in inducing the UV transient absorption. All the above results are discussed in terms of the model for the structure of bR proposed by Henderson, R., J.M. Baldwin, T.A. Ceska, F. Zemlin, E. Beckmann, and K.H. Downing. (1990. J. Mol. Biol. 213:899-929).

Amino Acid Sequence↗
PubMed1991

[The role of neck dissection in the eradication of salivary carcinomas].

From 1955 to 1984, radical neck dissection (RND) had been done in 300 salivary carcinoma patients, 114 of which had regional lymph node metastasis, with a 38% metastatic rate. Respective 3, 5, 10, 15, 20 year survival rates were 76, 64, 47, 35, 35% in a 3 to 20 years follow-up study in 283 patients (94.33%). The following four points are concluded: 1. The metastatic rate is determined not only on tumor staging, but more to its typing (pathologic behaviour). 2. Elective RND gave a better prognosis than therapeutic and negative metastasis has a better survival chance than positive where the low level metastasis is the worst. 3. According to pathologic typing, Elective RND is indicated for undifferentiated adenocarcinoma, high malignant mucoepidermoid carcinoma, squamous cell carcinoma, adenocarcinoma and papillary cystic adenocarcinoma, therapeutic RND for malignant pleomorphic adenoma, acinic cell carcinoma and mucoepidermoid carcinoma. 4. Unilateral RND is indicated for all but sublingual and buccal tumors.

Adenocarcinoma↗
PubMed1991

[Oral and maxillofacial multiple primary cancers].

Among 2989 patients with oral and maxillofacial cancers treated in our department from 1953 to 1985, 49 cases (1.63%) had the multiple primary lesions. The double primary cancers occurred in 44 cases (89.8%), three or more in 5 cases (10.2%). The multiple foci in an organ happened in 16 cases, different organ of systems in 23, and two systems in 10 cases. The followup in 49 cases (92.4%) for 3-27 years revealed the survival rates as follow: 76% (3 yrs), 69% (5 yrs), 42% (10 yrs), and 33% (15 yrs). The aggressive surgical intervention should be performed in oral and maxillofacial multiple primary cancers for a good therapeutic result.

Adult↗
PubMed1990

[Postradiation cancer of oral and maxillofacial regions].

Twenty-two patients with postradiation cancer of oral and maxillofacial regions treated in our hospital from 1969 to 1985 are reported. Of them, 3 patients had double postradiation cancers. The shortest interval between the two primary cancers was 3 years, the longest was 32 years with a median of 9 years. Of 15 patients treated with 60Co, 9 patients developed cancers and 6 sarcomas. In 4 patients treated with deep X-ray, cancers developed in 3 and sarcoma in one. Three patients were treated with 60Co, deep X-ray and radium implantation, all of them developed cancers. Radiation dose ranged from 3000 to 10,000 cGy but in most of the patients it was 7000-8000 cGy. In 19/22 patients the postradiation cancers were resected, giving 3 and 5 year survival rates of 50% and 23%. Only 1 patient survived for 14 years. Three patients treated by non-operative methods all died within 1-2 years. More aggressive treatments in patients with postradiation cancer are therefore indicated.

Adult↗
PubMed1984

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↗