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Biomedical subjects

C C Yang

Publications and source records attributed to C C Yang.

At least 253 records · Page 14Linked to original sources
PubMed1990

V-Y advancement flap for facial defects.

V-Y advancement flaps based on subcutaneous pedicles are an ideal option for closure of small to medium sized facial defects. This technique has been used to treat 69 patients with various lesions of the face, (30 basal cell carcinoma, 9 squamous cell carcinoma, 18 nevus, 4 traumatic defect, 3 old scar and 5 others) during the past seven years. There was no necrosis of any single flap. All the designs could be planned so that the long axes of the flaps were parallel to the wrinkle line, contour line or line of dependency. All wounds healed uneventfully with fine or undelineated scar. There were no secondary operation for these cases. Clinical results of this series have shown advantages of this flap in reconstruction of facial defects. It is reliable in circulation and is easy to design and execute. It causes no distortion of critical features and offers excellent cosmetic satisfaction in color and texture matching. Therefore, the V-Y advancement flap is recommended for closure of properly selected facial defects.

Adolescent↗
PubMed1990

An unusually-formed appearance epidermoid cyst of the plantar region--a case report.

A rare site for an epidermoid cyst is herein reported. A 40-year-old female was admitted for treatment of a right plantar tumor. The tumor was multiloculated, soft, nodular and in the range of about seven by seven centimeters. We initially diagnosed it as a saccular hemangioma, but it was finally diagnosed as an epidermoid cyst with foreign body reaction from the surgical specimen. Epidermoid cysts can occur in various parts of the body. Trauma is regarded to be the chief cause of them. Due to their various locations and appearance, they are sometimes difficult to diagnose. In such cases, however, it is generally agreed that pathological study is mandatory for a correct diagnosis.

Adult↗
PubMed1989

Studies on the status of lysine residues in phospholipase A2 from Naja naja atra (Taiwan cobra) snake venom.

Phospholipase A2 (PLA2) from Naja naja atra (Taiwan cobra) snake venom was subjected to lysine modification with trinitrobenzene sulphonic acid (TNBS), and two major trinitrophenylated (TNP) derivatives, TNP-1 and TNP-2, were separated by h.p.l.c. TNP-1 contained only one TNP group on Lys-6 and showed a marked decrease in enzymic activity, but still retained 45% of the lethal toxicity. Both Lys-6 and Lys-65 were modified in TNP-2, and modification of Lys-65 caused a further reduction of the lethal toxicity to 12.6%. However, the antigenicity of both TNP-1 and TNP-2 remained unchanged. The reactivity of Lys-6 and Lys-65 toward TNBS was greatly enhanced by Ca2+ and dihexanoyl-lecithin, suggesting that the two Lys residues are not directly involved in the binding of Ca2+ and substrate. The modified derivatives retained their affinity for Ca2+, indicating that Lys-6 and Lys-65 did not participate in the Ca2+ binding. The TNP derivatives could be regenerated with hydrazine hydrochloride. The biological activities of the regenerated PLA2 are almost the same as those of native PLA2. These results indicate that Lys-6 and Lys-65 are important for the biological activities of PLA2, and incorporation of a bulky TNP group on Lys-6 and Lys-65 might give rise to a distortion of the active conformation of PLA2.

Animals↗
PubMed1989

The interaction of E. coli IHF protein with its specific binding sites.

We have used two kinds of footprinting techniques, dimethylsulfate interference and hydroxyl radical protection, to explore the way that IHF recognizes its specific target sequences. Our results lead us to conclude that IHF recognizes DNA primarily through contacts with the minor groove, an unprecedented mode for a sequence-specific binding protein. We have also determined that, although IHF is a small protein that protects a large region of DNA, only a single IHF protomer is present at each binding site. IHF bends the DNA to which it binds. We have combined this fact plus our footprinting and stoichiometry data together with the crystal structure of a related protein, the nonspecific DNA binding protein HU, to propose a model for the way in which IHF binds to its DNA target.

Bacterial Proteins↗
PubMed1989

Oxygen transfer from the nitro group of a nitroaromatic radiosensitizer to a DNA sugar damage product.

Mechanisms based on one-electron oxidation appear incomplete in explaining cellular radiosensitization by nitroaromatic compounds such as misonidazole. Evidence is presented for a novel mechanism that may be involved in enhancing DNA strand breakage due to a variety of agents, including ionizing radiation, that generate carbon-centered radicals on DNA deoxyribose. Under anaerobic conditions the carbon-centered radical generated selectively at C-5' of deoxyribose of thymidylate residues in DNA by the antitumor antibiotic neocarzinostatin reacts with misonidazole to produce a DNA damage product in the form of 3'-(formyl phosphate)-ended DNA. In an 18O-transfer experiment we find that the carbonyl oxygen of the activated formyl moiety (trapped as formyl-Tris) is derived from the nitro group oxygen of misonidazole. This result strongly supports a mechanism in which a nitroxide radical adduct, formed by the addition of misonidazole to the radical at C-5' of deoxyribose, cleaves between the N and O so as to form an oxy radical precursor of the formyl moiety and a two-electron reduction species of misonidazole.

Antibiotics, Antineoplastic↗
PubMed1989

Do chemical modifications dissociate between the enzymatic and pharmacological activities of beta bungarotoxin and notexin?

We have measured enzymatic, hemolytic and anticoagulant activities, lethal potencies and effects on contractions of the phrenic nerve-diaphragm preparation, by chemically modified derivatives of beta bungarotoxin (beta BuTX) and notexin, two presynaptically acting toxins which have PLA2 activity. The following chemical modifications of beta BuTX were tested: alkylation and methylation of histidine 48, alkylation of tryptophan 19, sulfonylation of tyrosine 68, oxidation of methionines 6 and 8, semicarbazide addition under varied conditions to carboxyl groups, varied extents of carbamylation or trinitrophenylation of lysines and guanidination of all lysines with or without trinitrophenylation of the N-terminal asparagine. Only the histidine, tryptophan and tyrosine residues were modified in notexin. The results obtained were compared with those previously obtained using chemically modified derivatives of Naja nigricollis and Naja naja atra PLA2 enzymes which do not have a specific presynaptic site of action. The results with oxidized methionine and lysine-modified derivatives of beta BuTX are supportive of the suggestions of others that the N-terminal region and basic residues away from the enzymatic active region contribute towards the beta type presynaptic neurotoxicity of the PLA2 toxins. Using modified derivatives of beta BuTX and notexin, the dissociations between enzymatic activities and pharmacological properties were not as marked as previously observed with N. nigricollis and N. n. atra PLA2; nevertheless, several dissociations were noted. We conclude that, just as with non-presynaptically acting PLA2 enzymes, some pharmacological actions of presynaptically acting PLA2 toxins may occur independently of phospholipid hydrolysis.

Amino Acid Sequence↗
PubMed1989

Assessment of the role of tryptophan residues in phospholipase A2 by fluorescence quenching.

Tryptophan (Trp) fluorescence of two phospholipases A2 (PLA2) from Naja naja atra and Naja nigricollis snake venoms was quenched by acrylamide and iodide. Trp residues in N. naja atra PLA2 were equally accessible to acrylamide and iodide. Iodide quenching studies indicate that there are two classes of Trp fluorophores in N. nigricollis CMS-9. The accessible class consists of Trp-18 and Trp-19. Removal of the N-terminal octapeptide caused a perturbation of the micro-environment of the Trp residues in the PLA2 enzymes. The presence of a substrate lowers the susceptibility of the Trp residues to iodide quenching in N. naja atra PLA2, suggesting that all three Trp residues are at the substrate binding site, but in N. nigricollis CMS-9 Trp-18 and Trp-19 are related to substrate binding.

Acrylamide↗
PubMed1989

The reverse digital artery flap for fingertip reconstruction.

Reverse digital artery flaps were performed successfully to resurface the major fingertip defect in 10 patients and the volar defect of the middle phalanx in 1. This thin flap with its long vascular pedicle containing a digital artery and its perivascular cuff tissue has a wide arc of transposition. It can be used to reconstruct the defect located from the proximal phalanx to the fingertip of all fingers. No loss of the flap in this series was noted. The procedure is a time-saving, one-stage operation. Patients who received this procedure had no uncomfortable immobilization of the hand or long hospitalization. It also causes no disfigurement and no functional loss of the involved digit. Our clinical experience showed favorable results.

Adult↗
PubMed1989

Surgical treatment of the penoscrotal Paget's disease.

Data from six cases of penoscrotal Paget's disease were collected. Erythematous, indurated, and pruritic skin lesions that failed to respond to the topical therapy were the main complaints. Symptoms had been observed for three to seven years before correct diagnosis. Extensive diagnostic studies revealed negative findings of subjacent adenocarcinoma, but 1 patient had concurrent skin cancer of nasal ala. In treating penoscrotal Paget's disease, our policy is to (1) resect 3 cm or more skin beyond the margin of the cutaneous lesion, (2) resect deeply to the subcutaneous fat, (3) use intraoperative frozen sections to confirm the free margin and (4) reconstruct the wound with the local iliac flap. No local recurrence was noted during the follow-up period of two to seven years. The iliac flap is thin and pliable; it precluded scar contracture and painful penile erection, which are the common sequelae of free skin graft in the penoscrotal area. Patients enjoyed normal sexual activity after surgery.

Aged↗
PubMed1989

The pharmacological and pathological studies on several hepatic protective crude drugs from Taiwan (II).

Four crude drug extracts of Solanum incanum (entire plant), Ixeris chinensis (entire plant), Gardenia jasminoides (wild and cultivated, fructus) were administered to rats as dose of 1.0 g/kg, I.P. injection to screen the liver protective effect on CC14 induced hepatotoxicity. The acute increase of transaminase SGOT and SGPT levels that was caused by CC14 (1.0 ml/kg) S.C. injection can be significantly improved when treated with Solanum incanum (p less than 0.005), Ixeris chinensis (p less than 0.001), Gardenia jasminoides (cultivated) (p less than 0.005) but only a moderate change was shown by means of wild Gardenia jasminoides (p less than 0.05). As our results indicated, the extraction of these drugs has been found to possess a marked hepatic protective effect. The hepatic fatty metamorphosis and necrosis of central lobule were obviously improved by S. incanum and I. chinensis, administration, while the effect of treatment with G. jasminoides (cultivated) demonstrated a moderate protective action and little histopathological change by G. jasminoides (wild). In contrast to B. chinese, which has been reported previously as a treatment criteria, the S. incanum (p less than 0.01) and I. chinensis (p less than 0.01) in the present study have indicated that a significantly different hepatic protective effect on CC14 induced hepatic injury.

Animals↗
PubMed1989

Early smooth horizontal eye movement: a favorable prognostic sign in patients with locked-in syndrome.

Locked-in Syndrome (LIS) is a rare clinical entity consisting of quadriplegia, paralysis of lower cranial nerves, mutism, and bilateral paresis of horizontal gaze. The prognosis is usually poor. Most patients who do survive have severe residual impairment or develop chronic LIS. Review of the literature shows that recovery has been reported but not systematically studied, particularly with respect to early prognostic signs. We report a case of LIS with bilateral pontine infarctions shown by MRI. Severe neurological deficits included quadriplegia, paresis of horizontal gaze, facial paralysis, and bulbar palsy. Horizontal eye movements were present and smooth by the second week after onset. The patient had almost full functional motor recovery within four months, after a comprehensive rehabilitation program. Fourteen other reported cases of LIS with full recovery had documented recovery of lateral gaze in the early stage. In addition, smooth horizontal gaze is the most frequent activity in incomplete LIS. Early recovery of horizontal eye movement may indicate that the brain lesion is limited and may be a good prognostic sign in LIS.

Adult↗
PubMed1988

Role of the N-terminal region of the A chain in beta 1-bungarotoxin from the venom of Bungarus multicinctus (Taiwan-banded krait).

The N-terminal alpha-amino groups of beta 1-bungarotoxin (beta 1-Bgt) from Bungarus multicinctus venom were modified with trinitrobenzene sulfonic acid and the modified derivative was separated by high performance liquid chromatography. The trinitrophenylated (TNP) derivative contained two TNP groups at the alpha-amino groups of A chain and B chain and showed a marked decrease in enzymatic activity. Methionine residues at positions 6 and 8 of the A chain were oxidized with chloramine T or cleaved with cyanogen bromide to remove the N-terminal octapeptide. Oxidation of methionine residues and removal of the N-terminal octapeptide caused a precipitous decrease in enzymatic activity, whereas antigenicity remained unchanged. The presence of dihexanoyllecithin influenced the interaction between beta 1-Bgt and 8-anilinonaphthalene sulfonate (ANS) and revealed that beta 1-Bgt consists of two types of ANS-binding sites, one at the substrate binding site of the A chain and the other might be at the B chain. The modified derivatives still retained their affinity for Ca2+ and ANS, indicating that the N-terminal region is not involved in Ca2+ and substrate binding. A fluorescence study revealed that the alpha-amino group of the A chain was in the vicinity of substrate binding site and that the TNP alpha-amino groups were in proximity to Trp-19 of the A chain. In addition, the study showed that the N-terminal region is important for stabilizing the architectural environment of Trp-19. The results, together with the proposal that Trp-19 of the A chain is involved in substrate binding, suggest that the N-terminal region of the A chain plays a crucial role in maintaining a functional active site for beta 1-Bgt.

Amino Acids↗
PubMed1988

Role of the N-terminal region in phospholipases A2 from Naja naja atra (Taiwan cobra) and Naja nigricollis (spitting cobra) venoms.

The N-terminal alpha-amino groups of two phospholipases A2 (PLA2) from Naja naja atra and Naja nigricollis venoms were selectively modified with trinitrobenzene sulfonic acid, and the modified derivatives were separated by high performance liquid chromatography (HPLC). Trinitrophenylated (TNP) derivatives contained only one TNP group in the alpha-amino group of Asn-1 and showed a marked decrease in enzymatic activity. PLA2 enzymes were cleaved with CNBr, and the N-terminal octapeptide was separated from the large C-terminal fragment by HPLC. Removal of the N-terminal octapeptide from PLA2 enzymes caused a precipitous decrease in enzymatic activity. Enzyme immunoassay and double immunodiffusion revealed that the N-terminal octapeptide is one of the antigenic determinants of PLA2 enzymes. The presence of dihexanoyllecithin influenced the interaction between PLA2 enzymes and 8-anilinonaphthalene sulfonate (ANS), indicating that ANS-binding site of PLA2 enzymes is at or near the substrate binding site. Modification of the N-terminal region perturbed the substrate binding and the binding ability for ANS. The modified derivatives retained their affinity for Ca2+, indicating that the N-terminal region is not involved in Ca2+-binding. A fluorescence study revealed that the alpha-amino group is near Trp residue(s) and that the N-terminal region is important for stabilizing the architectural environment of the Trp residue(s). The results, together with the proposal that Trp residues in PLA2 enzymes are involved in substrate binding, suggest that the N-terminal region of PLA2 enzymes is involved in substrate binding and in maintaining a functional active site.

Amino Acids↗
PubMed1988

The pharmacological and pathological studies on several hepatic protective crude drugs from Taiwan (I).

This study is to investigate the hepatic protective effect of several Taiwan crude drug extractions on the carbon tetrachloride (CCl4)-induced hepatotoxicity in rats. The pharmacological and pathological effects of Bupleurum chinense, Phellodendron wilsonii, Clematis chinensis and Hedyotis corymbosa were analyzed by liver enzyme function test and pathological studies. However, the results of amine transferase SGOT and SGPT have shown a significant hepatic protective effect after treatment with Bupleurum chinense (P less than 0.005), Phellodendron wilsonii (P less than 0.001), Clematis chinensis (P less than 0.005) and Hedyotis corymbosa (P less than 0.005, SGPT only). The fatty degeneration around the central vein area and necrosis of the central lobule can be significantly improved by P. wilsonii and moderately changed by B. chinense or C. chinensis. Although fatty metamorphosis has been affected by H. corymbosa, various inflammatory cell infiltrations in the cytoplasm were noted.

Animals↗