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Biomedical subjects

A Tseng

Publications and source records attributed to A Tseng.

At least 37 records · Page 2Linked to original sources
PubMed1996

Centrifugal pump-assisted venous bypass between the superior mesenteric vein and the umbilical vein during portal vein resection.

We describe herein our method of performing centrifugal pump-assisted venous bypass between the superior mesenteric vein and the umbilical vein, developed with the aim of preventing congestion of the small intestine and promoting strong and constant hepatic blood flow during portal vein resection. By using this bypass method, portal vein resection and reconstruction was able to be carried out with ease and safety in six patients undergoing surgery for a pancreatic mass or cancer. No coagulation abnormalities, thrombocytopenia, leukocytopenia, severe liver dysfunction, or portal vein thrombosis developed in any of the patients postoperatively. Thus, we highly recommend this simple and reliable method of bypass when portal vein resection is being performed.

Carcinoma, Acinar Cell↗
PubMed1996

Acute cholecystitis. Does the clinical diagnosis correlate with the pathological diagnosis?

BACKGROUND: Most of the literature dealing with the surgical management of acute cholecystitis bases patient selection on pathological diagnosis, either exclusively or using it as a major selection criteria or as a confirmation of diagnosis. The purpose of this study was to examine the correlation between preoperative clinical findings, intraoperative gross findings, and postoperative pathological findings. METHODS: A retrospective review of 493 consecutive laparoscopic cholecystectomies performed by a single surgeon (RJF) in a single institution was done. Four different sets of criteria were used to define four groups of patients as having acute cholecystitis: (1) preoperative acute cholecystitis based on defined criteria (PA); (2) intraoperative gross findings of acute or subacute cholecystitis based on surgeon assessment of inflammation (IA); (3) initial pathological evaluation by a staff pathologist (IP); and (4) expert pathological (EP) review using strictly defined histological criteria. RESULTS: Of 41 patients, 40 (97.6%) were classified as having acute cholecystitis by IA, 21 (51.2%) by IP, and 17 (41.5%) by EP. Of the 75 patients classified as having acute cholecystitis by IA, 40 (53.0%) were classified acute by PA, 34 (45. 0%) by IP, and 17 (22.7%) by EP. Of the 72 IP patients, 34 (47.2%) were classified as acute by IA, 15 (20.8%) by EP, and 24 (33.3%) were PA. Of the 32 EP patients, 21 (65.6%) were classified as acute by IA, 14 (43.8%) by IP, and 18 (56.3%) were PA. CONCLUSION: The correlation between the pathological diagnosis and intraoperative findings is poor. Preoperative clinical findings of acute cholecystitis are highly reliable for predicting intraoperative gross findings. However, intraoperative findings of acute cholecystitis are commonly found in the absence of preoperative clinical signs. Recommendations for surgical therapy should be based on studies which use either operative findings or the preoperative clinical findings as the basis for patient selection.

Adolescent↗
PubMed1995

Evidence that portal vein decompression improves survival of canine quarter orthotopic liver transplantation.

The minimum graft volume still remains unclear in reduced-size liver transplantation (RLT). This study reports the improved survival of canine RLT using a quarter graft with the aid of a portahepatic vein shunt (PHVS). In beagles, the donor liver was reduced to the right lateral and caudate lobes (quarter graft) with or without provision of PHVS, and transplanted orthotopically in the recipient. The PHVS was established by an end-to-end anastomosis of the portal vein branch and the hepatic vein in the resected left lateral lobe. Liver chemistries including arterial blood ketone body ratio (AKBR) were serially measured during and after surgery. All seven animals with PHVS survived more than 3 days (mean +/- SD; 5.3 +/- 1.7 days), whereas all six without PHVS died within 3 days (1.8 +/- 0.8 days, P < 0.01). Portal vein pressures immediately after recirculation in animals with and without PHVS were 8.5 +/- 1.2 mmHg and 16.9 +/- 3.1 mmHg, respectively (P < 0.01). Regardless of the presence or absence of PHVS, AKBR dropped to a level lower than 0.7 during the anhepatic period and returned promptly to above 1.0 as early as 30 min after recirculation. Thereafter, the AKBR values in animals with PHVS remained higher than 1.0, whereas those in animals without PHVS showed a progressive decrease, showing a statistically significant difference between the two groups after 12 hr (P < 0.05). Graft function, as assessed by AKBR, was well correlated with survival and other liver chemistries. These results indicate that, in an extreme RLT, portal hypertension is a risk factor predisposing to graft failure, most likely by increasing microvascular injury after recirculation.

Animals↗
PubMed1994

Neuropeptide Y analog with selective antagonism of effects mediated by postjunctional Y1 receptors.

Neuropeptide, a 36 amino acid peptide, is one of the most ubiquitous neuropeptides in the nervous system. It is released during stimulation of sympathetic nerves and is implicated as an important neurotransmitter regulating cardiovascular activity. Administration of neuropeptide Y results in vasoconstriction and inhibition of neurotransmitter release. However, the absence of any effective inhibitors of neuropeptide Y action have precluded the examination of its possible role in hypertension. Here we describe a synthetic hexapeptide (BRC 672), corresponding to residues 22-27 of neuropeptide Y. Following the administration of BRC 672 (6.7 mumol/kg), neuropeptide Y-induced pressor responses were reduced by 32-48% in a dose-dependent fashion. The inhibition was specific for neuropeptide Y, as the pressor response to phenylephrine, an alpha-adrenoceptor agonist, was unchanged. It was selective for the postsynaptic (neuropeptide Y Y1 receptor-mediated) vasoconstrictor activity, because the presynaptic (neuropeptide Y Y2 receptor-mediated) cardiac vagal inhibition evoked by injection of neuropeptide Y to rats was not affected. The hexapeptide inhibited the neuropeptide Y-induced increase in cytosolic free Ca2+ in mammalian cells expressing the cloned human neuropeptide Y Y1 receptor. Injections of BRC 672 significantly reduced blood pressure in anaesthetised rats and in conscious spontaneously hypertensive rats. Resting arterial blood pressure decreased from 136 +/- 4 mm Hg to 122 +/- 3 mm Hg and remained depressed 2 h after the administration of the hexapeptide in anaesthetised rats. In spontaneously hypertensive rats blood pressure was decreased for up to 4 h.

Animals↗
PubMed1994

Stabilized structure of the presynaptic (Y2) receptor-specific neuropeptide Y analog N-acetyl[Leu-28,Leu-31]NPY(24-36).

Neuropeptide Y analog N-acetyl[Leu-28,Leu-31]NPY(24-36)-amide binds specifically to prejunctional or Y2 receptors acting to inhibit neurotransmitter release. The structure of this biologically active mutant was studied by two-dimensional proton nuclear magnetic resonance spectroscopy. Assignments of all backbone and side chain hydrogens were made by using totally correlated spectroscopy (TOCSY) experiments providing through-bond 1H-1H connectivities, and nuclear Overhauser effect spectroscopy (NOESY), which provided through-space and sequential backbone connectivities. Structure analysis of the peptide was performed using distance geometry and dynamic simulated annealing revealing the presence of a helical structure exhibiting an amphiphilic character and slight constriction in the segment 24-29.

Amino Acid Sequence↗
PubMed1994

A novel neuropeptide Y analog, N-acetyl [Leu28,Leu31]neuropeptide Y-(24-36), with functional specificity for the presynaptic (Y2) receptor.

We have carried out functional and in vitro studies on a novel analog of neuropeptide Y which shows selectivity for the prejunctional or neuropeptide Y Y2 receptor. In anaesthetised rats N-acetyl [Leu28,Leu31]neuropeptide Y-(24-36) attenuates cardiac vagal action (a prejunctional or neuropeptide Y Y2 action) and has no significant pressor effects (postjunctional or neuropeptide Y Y1 action). In the human neuroblastoma cell line (SMS-KAN) which expresses and endogenous Y2-like neuropeptide Y receptor, N-acetyl [Leu28,Leu31]neuropeptide Y-(24-36) competes with peptide YY for binding sites with an IC50 of 0.5 +/- 0.1 nM. In contrast in a fibroblast Chinese hamster ovary cell line which expresses the cloned human neuropeptide Y Y1 receptor and is used to study changes in cytosolic calcium evoked by (a neuropeptide Y Y1 effect), N-acetyl [Leu28,Leu31]neuropeptide Y-(24-36) showed no activity even at high concentrations. The steric structure for this novel compound has been determined using proton nuclear magnetic resonance (NMR) spectroscopy and it is consistent with the C-terminal end of published structures of neuropeptide Y. We suggest acetylation and amino acid substitutions stabilise the molecule and allow it to bind only to the neuropeptide Y Y2 receptor.

Acetylation↗
PubMed1994

Coumarin modulates the cell-cycle progression of an MTV-EJras cell line.

The effects of coumarin (1,2-benzopyrone) on ras oncogene expression during the cell cycle of an MTV-EJras cell line was determined by flow cytometry. ras oncogene expression in cells was induced by dexamethasone and increased fivefold during G1/G0 phase and threefold in S phase. Dexamethasone also increased the percentage of cells in S phase from 21% to 31%, compared to phosphate-buffered-saline-treated control cells (P < 0.01). Coumarin decreased the percentage of dexamethasone-treated cells in S phase from 31% to 19%, with a concomitant increase in the percentage of cells in G1/G0 compared to control levels. Coumarin also reduced ras expression (mean fluorescence) by 40% in G1/G0 phase and 30% in S phase. We conclude that coumarin significantly reduces the cell-cycle progression of MTV-EJras cells and decreases ras expression in both G1 and S phases. These findings suggest a novel approach to the selective control of proliferation of malignant cells.

Animals↗
PubMed1993

Research cost analyses to aid in decision making in the conduct of a large prevention trial, CARET. Carotene and Retinol Efficacy Trial.

Because of their larger study populations and longer durations, prevention trials typically are more costly than treatment trials. Thus it is important to analyze costs systematically to aid in making cost-effective decisions during the conduct of prevention trials as well as in the original design. Cost analysis must be tied to sample size estimation because costs depend on such factors as the total number of person-years of follow-up and the number of trial outcomes, which are not basic design parameters but are derived quantities resulting from sample size estimation. We illustrate the use of cost analysis to decide among options for future conduct of an ongoing prevention trial with three issues that have arisen during the Carotene and Retinol Efficacy Trial (CARET): the trade-off between extending the duration of the trial or increasing the number of participants, the effect on costs of delay in accrual, and the cost effectiveness of particular retention activities.

Anticarcinogenic Agents↗
PubMed1993

Effects on response rates and costs of stamps vs business reply in a mail survey of physicians.

In the general population, the use of stamps rather than business reply postage significantly improves response rates in mail surveys. Among physicians, however, a smaller effect might be anticipated due to their greater sophistication. An experiment was conducted to test the hypothesis that stamps would improve response rates and lower costs in a physician survey that included intensive follow up. In 1989, 380 physicians who reported providing primary care were surveyed. The protocol included two mailings, a postcard reminder, and two telephone reminders. Physicians were randomly assigned to receive a return envelope with a first-class stamp or an envelope that had been preprinted "business reply mail" in the first and second mailings. Response rates, calculated as completed surveys divided by eligible physicians, were 83.8 and 72.1% for stamps and business reply respectively, a difference of 11.7 percentage points (p < 0.01). Moreover, the total cost per completed survey was $11.18 for the physicians receiving stamps and $14.25 for the physicians receiving business reply. As in mail surveys of the general public, the use of first-class stamps on return envelopes both improves response rates and reduces cost in surveys of physicians.

Data Collection↗
PubMed1992

A truncated form of fibroblast growth factor receptor 1 inhibits signal transduction by multiple types of fibroblast growth factor receptor.

A truncated form of the type 1 fibroblast growth factor receptor (FGFR1) lacking most of its cytoplasmic domain was tested for its ability to inhibit signal transduction by each of three different wild-type FGFRs (FGFR1, 2, and 3). When the truncated FGFR1 was expressed in Xenopus oocytes in excess of each wild-type FGFR, mobilization of intracellular calcium mediated by the wild-type FGFRs was completely blocked. The truncated FGFR did not inhibit signal transduction by the co-expressed platelet-derived growth factor beta-receptor. A form of truncated FGFR1 which lacked the first immunoglobulin-like domain also inhibited signal transduction by wild-type FGFRs. Truncated FGFR formed complexes with wild-type FGFR in the presence of basic FGF in intact cells. These observations were consistent with the hypothesis that the truncated FGFR interacted with wild-type FGFRs to form nonfunctional heterodimers, thus eliminating the signaling by the wild-type FGFRs. The observation that signaling by multiple types of FGFR can be blocked by a single type of truncated FGFR suggests that the different types of FGFR can interact with each other in ligand-mediated complexes. These findings provide a molecular basis for inhibiting the actions of FGFs in vivo.

Animals↗
PubMed1992

Formation of proline thiohydantoin with ammonium thiocyanate: progress towards a viable C-terminal amino-acid-sequencing procedure.

Pure amino acid thiohydantoins are required as reference standards for development of C-terminal-sequencing procedures based on thiohydantoin formation of the C-terminal amino acids of peptides and proteins. Proline thiohydantoin was prepared using a straightforward method involving reaction of acetylproline with ammonium thiocyanate. It was characterized by UV spectrophotometry, mass spectrometry and back-hydrolysis to the free amino acid. These data establish unequivocally that the thiocyanate procedure is applicable to proline as well as to the other common amino acids. This work also validates earlier claims that proline thiohydantoin can be prepared by reaction with thiocyanic acid.

Amino Acid Sequence↗
PubMed1991

The prevention of cholelithiasis with infused sodium chenodeoxycholate in the prairie dog (Cynomys ludovicianus).

1. This study examines the efficacy of infused sodium chenodeoxycholate to prevent cholesterol gallstone formation in the prairie dog when fed a high cholesterol diet. 2. Three experimental groups were designed to examine this. The first group (N = 5) was fed a normal rat chow diet, the second group (N = 5) was fed a high cholesterol diet (0.4% cholesterol by weight), and the third group (N = 5) was fed a high cholesterol diet plus given a daily injection of intravenous sodium chenodeoxycholate (15 mg/kg). 3. All of the animals in the second group had cholesterol crystals and cholesterol gallstones. In the third group, none of the animals had gallstones, and all but one lacked cholesterol crystals. 4. Statistical analysis showed that the first and third groups were statistically identical in their lithogenic indices and biliary lipid composition. 5. We concluded that infused sodium chenodeoxycholate is effective in preventing cholesterol gallstone formation in the prairie dog when fed a high cholesterol diet.

Analysis of Variance↗
PubMed1990

The quantitative and qualitative analysis for biliary lipids in the prairie dog Cynomys ludovicianus.

1. The quantitative analysis of biliary lipids has been well characterized, however, there is little data related to the qualitative and quantitative analysis of phospholipids and conjugated bile salts for the prairie dog. 2. Gallbladder and hepatic bile were collected and the bile salts in each sample were analyzed by first fractionating them into unconjugated, glycoconjugated, and tauroconjugated bile salts. These fractions were further resolved by using HPLC techniques. 3. The data has shown that cholate exists predominately as the tauroconjugate and is the major bile salt, whereas chenodeoxycholate is rarely conjugated. 4. The qualitative analysis of biliary phospholipids by thin layer chromatography has shown a remarkable similarity to that of humans. Phosphatidylcholine was found to be the major phospholipid followed by phosphatidylethanolamine with trace amounts of lysophosphatidylcholine and phosphatidylserine.

Animals↗
PubMed1990

Proteins of the rat prostate. III. Effect of testosterone on protein synthesis by the ventral prostate of castrated rats.

Protein synthetic activities in the ventral prostate were assessed by two-dimensional electrophoresis in either four-day or seven-day castrated rats at different intervals following subcutaneous implantation of testosterone-filled silastic tubings for a period of up to four days. Prostatic tissues were cut into one to two mm. pieces and incubated in tissue culture medium containing S35-methionine (100 microCi/ml.) at 37C under 95% oxygen and 5% carbon dioxide for four hours. The incubated tissues were subjected to two-dimensional electrophoresis and radiofluorography. Analysis of protein spots detected in the fluorograms by computer-assisted densitometry revealed temporal changes in the synthesis of individual proteins by the ventral prostate of castrated rats following androgen treatment. Changes in two groups of proteins were evaluated: castration-induced proteins and androgen-dependent proteins. The level of synthesis of three castration-induced proteins (spots G, H, and I) declined rapidly upon testosterone treatment and reached a non-detectable level for spots G and H and a low level of synthesis for spot I by three days following androgen treatment. Synthesis of androgen-dependent proteins (spots D, E, and F) was activated by testosterone treatment. However, the time interval required to activate the synthesis of these proteins is different. Synthesis of protein spot D (prostatic binding protein) was detected as soon as half hour after the treatment. Synthesis of spots E and F, on the other hand, was not activated until 24 and 48 hours after the treatment, respectively. These changes in patterns of protein synthesis represent the characteristics of cellular responses to testosterone stimulation by the regressed prostate.

Animals↗
PubMed1990

Prevention of adult respiratory distress syndrome with plasminogen activator in pigs.

Death from traumatic shock has been associated with loss of blood externally or internally. However, many patients die after trauma, even though blood volume restoration is adequate. Death is often due to pulmonary failure (adult respiratory distress syndrome [ARDS]). Death and ARDS have been associated with disseminated intravascular coagulation (DIC) and microclots in the lungs. Dissolution of the microclots after trauma can be achieved by activation of endogenous plasmin. Nine pigs were anesthetized for 48 h. Trauma was administered by 60 standard blows to each thigh resulting in a bruise of muscle but no skin, bone, or major vessel injury. Nutrition and respiration were maintained at normal levels. All nine pigs died with severe lung pathology and low PaO2. Ten other traumatized pigs were treated with a plasminogen activator iv 4 h after trauma. Five of these were treated with tissue plasminogen activator (tPA) and five with urokinase. All treated pigs survived 48 h and maintained a normal PaO2. Autopsy showed minimal lung pathology.

Animals↗
PubMed1990

Spontaneously metastasizing variants of a human lung carcinoma cell line: monoclonal antibody characterization.

Spontaneously occurring microscopic lung and lymph node metastases (in athymic mice) of a low metastatic human lung carcinoma cell line, UCP3, and its high metastatic variant, MV522, were isolated. Characterization of the variants included karyotypic and isoenzyme analyses; assessment of spontaneous metastatic capabilities in athymic mice, and monoclonal antibody analyses. The high metastatic variant LNT had barely detectable amounts of a glycoprotein molecule with apparent Mr 73 kd and 90 kd, which was present in the other cell lines. This molecule was detected in 20/24 primary human neoplasms but only in 3/18 metastatic neoplasms, suggesting a loss during the metastatic disease process.

Animals↗
PubMed1990

Partial amino acid sequence of osteocalcin from an extinct species of ratite bird.

Osteocalcin the major gamma carboxyglutamic acid containing protein of vertebrate bone has been purified from the bones of a specimen of Pachyornis elephantopus, a species of the extinct class of New Zealand ratite birds, the moas. The sequence of the N-terminal region of moa osteocalcin was determined using gas phase N-terminal sequencing. The N-terminal sequences of the ostrich and rhea osteocalcins were also determined. Alignment of the N-terminal sequence of osteocalcin from the extinct moa against the osteocalcins of the extant ostrich, rhea and emu reveals the homology amongst the ratite species is greater than the homology with the chicken osteocalcin.

Amino Acid Sequence↗