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Biomedical subjects

C S Shin

Publications and source records attributed to C S Shin.

At least 55 records · Page 3Linked to original sources
PubMed1980

Three hundred and fifty-three consecutive patients with permanent transvenous pacemakers.

The safety and convenience of the transvenous approach to long-term endocardial pacing are well established, but its principal drawback is electrode displacement. The reported incidence of this complication varies between 3.0% to 36.7%, and is highest in the early post-implantation period before endocardial fixation of the electrode tip. Recently Brewster and Evans determined that the electrode displacement rate in 21 published series averaged 14.3%. However, the Inter Society Committee on Heart Diseases (ICHD) report on pacemakers states that a rate of early displacement greater than 5% calls for a critical review of results. The training and expertise of the persons inserting the pacemaker electrodes undoubtedly are major factors which determine the proper transvenous placement of permanent cardiac electrodes. This paper deals with our clinical experience of 353 patients who received permanent transvenous pacemakers during the period September 1, 1974 through March 1, 1979, with emphasis on problems and complications encountered and overall results.

Adolescent↗
PubMed1980

Early morphologic changes in the intestine following massive resection of the small intestine and parenteral nutrition therapy.

Following massive resection of the small intestine, including the ileocecal valve in seven adult mongrel dogs, the remaining 20 centimeters of the proximal part of the jejunum was anastomised to the midtransverse portion of the colon. All dogs were given parenteral nutrition for four weeks. Six weeks after resection, the dogs underwent reexploration, and gross and microscopic examinations of the remaining part of the jejunum were carried out. Grossly, there was a 29.5 per cent increase in the length and a 31 per cent increase in the circumference of the intestine. Microscopically, there was a 23 per cent increase in the depth of the crypts, a 21 per cent increase in the number of villi and a 22 per cent increase in the width of the villi. No change was observed in the height of the villi.

Animals↗
PubMed1979

The hemodynamics of extra-anatomic bypass grafts.

The hemodynamics of extra-anatomic bypass were studied with the use of right to left iliac artery bypass grafts. An arteriovenous fistula on the recipient side was used to increase the flow through the graft. Flow measurements in this model under normotensive conditions showed proportionate increases in the suprarenal aortic blood flow and in the blood flow through the segment of donor artery proximal to the bypass graft anastomosis. Stealing of blood was not observed even when the graft flow was increased to approximately 11 times the normal flow in the donor artery. Arfonad was used for producing hypotension through vasodilatation. In the presence of peripheral vasodilatation, adequate blood flow can be expected after such bypass grafts at blood pressures as low as 80 millimeters of mercury and hypotension per se does not produce vascular steal.

Animals↗
PubMed1979

Regional versus systemic heparinization.

In 12 mongrel dogs, the comparative effectiveness of systemic versus regional heparinization was studied after injecting 100 units per kilogram of heparin into a systemic vein or regionally into an artery. Activated plasma thromboplastin time was used to monitor the heparin activity, and the coagulability of blood in the general circulation was compared with the coagulability of blood in the excluded circulation distal to the vascular clamps. Both methods of heparinization were found to be equally effective. Heparin injected regionally rapidly achieves a uniform distribution in the excluded, as well as the general, circulation and, as such, cannot be called regional. There was no difference in coagulability of blood in the general circulation compared with the blood in the excluded circulation. Results of this study suggest that regional heparinization is, in fact, systemic heparinization.

Animals↗
PubMed1978

Effect of diminished distal blood flow on the morphologic changes in autogenous vein grafts.

Histologic changes in canine autogenous femoral veins were studied after interposition into the femoral artery. After a 50 per cent reduction of distal blood flow, marked fibrosis of the intima, causing narrowing of the intima and focal destruction of the internal elastic membrane and media, were found in the vein graft and the adjacent arterial segment. These changes are probably due to abnormal intraluminal pressure of femoral artery and interposed vein graft following constriction.

Animals↗
PubMed1977

His bundle electrograms in 51 patients requiring permanent transvenous pacemakers.

Fifty-one patients required the implantation of a Cordis Omnis-Stanicor permanent pacemaker. His bundle electrograms studies, which included right atrial pacing and sinoatrial (SA) node postsuppression recovery times, were performed prior to the implantations. Pacing and sensing thresholds were obtained in all patients. Syncope or episodes of dizziness were the presenting symptoms in virtually every patient. Twenty-eight of the 51 patients had the sick sinus syndrome. Only nine patients were in complete heart block, and an additional nine were in second-degree heart block. The His bundle electrogram technique was not particularly helpful in selecting the potential pacemaker candidate. The symptomatic patient with second- or third-degree heart block requires a pacemaker. In the sick sinus syndrome, the His bundle electrogram was a disappointing tool in detecting abnormalities. In chronic bundle branch block, the His bundle electrogram appears to play a major role. A prolonged H-V interval in a symptomatic patient, in whom a specific noncardiac cause cannot be identified, signifies that a pacemaker is required.

Adult↗
PubMed1975

Effect of partial constriction of the superior mesenteric artery upon absorption of d-xylose, labeled triolein and labeled albumin.

Intestinal adsorption of triolein, Risa and d-xylose was determined before and after reduction of blood flow in the superior mesenteric artery. Absorption of d-xylose did not change, but absorption of triolein and Risa appeared to be slightly improved after arterial constriction, even if the artery was completely thrombosed. Enhancement in absorption of Risa and triolein was probably the result of extensive collateral formation around the constricted superior mesenteric artery.

Animals↗
PubMed1975

Aneurysm of a polar renal artery.

A patient with a saccular aneurysm arising from the left superior polar renal artery is presented together with a review of two further reports from the literature. The importance of selective arteriography and the interpretation of the "naked calyx" sign in the diagnosis of supernumerary renal arteries has been emphasized. We feel that this is the only report of an aneurysm of a polar artery successfully treated by excision and end-to-end arterial anastomosis.

Adult↗
PubMedDate not supplied

Enhanced production of human mini-proinsulin in fed-batch cultures at high cell density of Escherichia coli BL21(DE3)[pET-3aT2M2].

Synthesis of recombinant protein (human mini-proinsulin) is investigated in fed-batch cultures at high cell concentration of recombinant Escherichia coli BL21(DE3)[pET-3aT2M2]. Transcription of the recombinant gene is controlled by a T7 promoter system. The human mini-proinsulin is characterized by a C-chain peptide consisting of only nine amino acids, whereas the C-chain peptide of natural human proinsulin is made up of 35 amino acids. It is expressed in a fusion protein with a small fusion partner (a peptide with 18 amino acids) and finally aggregated into insoluble inclusion bodies in cytoplasm of recombinant E. coli. The fermentative production of this small fusion mini-proinsulin may be of great advantage in enhancing the yield of human insulin. To find an optimum induction strategy, effects of various key cultivation variables on the mini-proinsulin production are examined in high cell density fed-batch cultures. No general correlation is found between preinduction specific growth rate and recombinant protein synthesis, which confers a flexibility in choosing the feeding strategy of preinduction media for achieving the high cell density cultures. A culture temperature below 37 degrees C is unfavorable for recombinant gene expression, and the T7-based expression system is almost completely repressed at 30 degrees C. The nutrient glucose and yeast extract concentration in postinduction feed media is optimized by applying a statistical method for medium optimization, i.e. response surface methodology, and an effective amount of inducer molecule (IPTG) is determined to maximize the specific recombinant protein formation. The mini-proinsulin production in E. coli culture is significantly influenced by the volumetric feed rate of postinduction media, which is shown to be closely related to the plasmid copy number in the recombinant cell. Consequently, in a single-stage fed-batch process, the mini-proinsulin concentration is increased up to 7 g/L, approximately 62 wt % of which corresponds to mature human insulin. A two-stage fed-batch fermentation process, with recombinant cell growth occurring at a constant growth rate and constant cell concentration in a growth fermenter and mini-proinsulin production in an induction fermenter, is designed, and its efficacy in increasing volumetric productivity of mini-proinsulin is demonstrated.

Colony Count, Microbial↗