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Biomedical subjects

T K Lee

Publications and source records attributed to T K Lee.

At least 19 recordsLinked to original sources
PubMed1992

Mucosal glutamine utilization after small-bowel transplantation: an electrophysiologic study.

A short course of FK 506 after small bowel transplantation averts rejection in the rat and achieves indefinite survival of the recipient whose nutritional status is dependent on the function of the intestinal graft. Ex vivo electrophysiologic studies using the Ussing Cell were conducted to delineate functional competence of the graft by evaluating mucosal ion transport and glutamine utilization. Orthotopic small-bowel transplantation was performed in Lewis (LEW) rats as recipients of either Brown-Norway (BN) allografts or LEW syngeneic grafts. Allograft recipients received FK 506 either as a short course (2 mg/kg on Day 0-4 after transplantation) or continuously (2 mg/kg Day 0-4, then 0.5 mg/kg weekly). Ileal mucosa was harvested from small bowel grafts 9 and 60 days after transplantation and mounted in the Ussing Cell containing Hanks' balanced salt solution with/without L-glutamine (20 mM). Transmembrane potential difference (PD), which represents mucosal active ion transport, and mucosal resistance, an index of membrane integrity, were recorded. Nine days after transplantation, mucosal PD was the same in the ileum from syngeneic grafts, allografts treated with FK 506 and normal LEW and BN rats, and the addition of glutamine increased PD equally in all groups. In comparison, PD was markedly decreased in allografts undergoing rejection, and the glutamine response was blunted. Sixty days after transplantation, mucosal PD was reduced in allografts treated with a short course of FK 506, but normal in allografts receiving continuous immunosuppression with FK 506 and in syngeneic grafts. A decrease of mucosal resistance was not a feature of rejection nor a sequel of limited FK 506 therapy. Our data indicate that allograft rejection results in a significant decrease in mucosal PD and a poor response to glutamine. Control of rejection by FK 506 preserves normal electrophysiologic responses of the allograft mucosa.

Animals↗
PubMed1992

Process development for the recovery and purification of recombinant protein G.

The domains of protein G from streptococcus which bind immunoglobulin G have been cloned and expressed in Escherichia coli (Fahnestock et al., 1986). Because protein G binds to several animal immunoglobulin G's, it has many immunochemical applications. This report describes process development for large-scale production of this recombinant protein G (also known as GammaBind G). In 200 l cultures of E. coli, this protein G variant was released from the cell into the culture medium by heating at 80 degrees C for 10 min. The concentration was monitored by either a competitive enzyme-linked immunoassay or a liquid chromatographic assay. Cross-flow microfiltration with 0.22 micron membrane was used to remove the cells. The protein G-rich permeate from the cross-flow microfilter was purified by affinity chromatography using a 5 l column of IgG-Sepharose 6 Fast Flow, which yielded 16-18 g of protein G per column cycle. The pools of purified protein G were concentrated and desalted using ultrafiltration. The salt-free protein G was then lyophilized as bulk product. The overall recovery through the entire process was 50-64%. The analysis of the final product included sodium dodecyl sulfate polyacrylamide gel electrophoresis, UV-visible spectrum, high performance gel filtration, endotoxin level and binding efficiency to human IgG Sepharose.

Bacterial Proteins↗
PubMed1992

Perinatal mortality and prevalence of major congenital malformations of twins in Taipei city.

In order to examine perinatal mortality and prevalence of major congenital malformations in twins, deliveries in four teaching hospitals in Taipei City were studied. Among a total of 73,264 deliveries from October 1985 to June 1989, there were 844 pairs of twins. The zygosity of the twin pairs was determined by sex, placentation and 12 red blood cell antigens. There were 482 MZ and 252 DZ twin pairs identified, but the zygosity of a further 110 twin pairs was indeterminable due to lack of information on plancentation and/or blood types. A total of 4,573 singletons delivered in one study hospital from July 1986 to June 1987 were also studied as controls. The perinatal mortality rate was 7.5% for MZ twins, 1.4% for DZ twins, and 0.7% for singletons. The concordance rate of perinatal death was significantly higher in MZ (60%) than in DZ (0%) twins. The prevalence of major congenital malformations was 2.7% for MZ twins, 1.0% for DZ twins, and 0.6% for singletons. The concordance rate of major congenital malformations was 18% for MZ twins, but no DZ pair was concordant in any major congenital malformation. The concordance rate of facial clefts was 29% for MZ twins. There were 2 sets of conjoined twins giving a prevalence rate of 2.7 per 100,000 deliveries. These findings showing the prevalence of perinatal mortality and major congenital malformation to be highest in MZ twins, intermediate in DZ twins and lowest in singletons, suggest the importance of intrauterine environments in the determination of perinatal mortality and congenital malformations.

Congenital Abnormalities↗
PubMed1992

Secular trend and associated factors of twinning in Taiwan.

Delivery records of public hospitals and local health centers were analyzed to investigate the secular trend of multiple births from 1955 to 1990 in Taiwan. Twinning rates decreased gradually from the late 1950s to 1973, slightly increased and remained stable from 1974 to 1980, and then increased strikingly from 1981 to 1990. During the study period, MZ rates were consistently higher than DZ rates except in 1986 when a higher DZ rate was observed. The highest MZ rate of 7.7 per 1,000 deliveries was observed in 1985, while the highest DZ rate of 4.6 per 1,000 deliveries was observed in 1986. The triplet incidence rate also declined from the early 1960s to 1973 and then increased markedly from 1974 to 1990. A case-control study including 482 MZ and 252 DZ twin pairs and 1,496 singletons was carried out in four teaching hospitals in Taipei City between October 1985 and June 1989 to examine factors related to twinning. The zygosity of twin pairs was determined by sex, placentation and red blood cell antigens. Multiple logistic regression analysis showed that the higher the maternal age, the lower the MZ and DZ rates, while the higher the parity, the higher the rates. There was no association of paternal age or of maternal educational level with twinning rates.

Adult↗
PubMed1992

Evaluation of finger blood flow with Tc-99m MDP (methylene diphosphonate).

BACKGROUND: A variety of methods were used to establish objective diagnostic criteria of Raynaud's phenomenon. We intended to introduce another method, using radionuclide (Tc-99m methylene diphosphonate) scintigraphy, which is more objective, simple and economical than the past methods. METHODS: The finger blood flow with radionuclide scintigraphy was evaluated in 10 patients of Raynaud's syndrome, 12 patients of connective disease without Raynaud's symptoms, and 20 normal persons. After immersing one hand in ice water (4 degrees C) for 30 seconds, the hand was exposed to 22 degrees C room air for 15 minutes, and then the patients received the intravenous (IV) bolus of 20 microCi of Tc-99m methylene diphosphonate (MDP). At the same time, scintigraphic image of both hands started with the region of interest, including the second, third, fourth and fifth fingers distal to the metacarpophalangeal (MCP) joints. Computer recording of the counts in the region of interest every 2 seconds for 310 seconds was started on IV bolus injection. RESULTS: The 310 seconds cumulative digital blood flow ratio of cold exposed hand to room air exposed hand was significantly lower in Raynaud's group (p < 0.001), and the ratio of initial slope of activity curve was also lower in the Raynaud's group (p < 0.001). Of the 8 patients showing Raynaud's syndrome, 4 patients of scleroderma and 1 patient of multiple myeloma showed no improvement of finger blood flow in the cold exposed hand after 2 weeks of pharmacological therapy, but 1 patient of mixed connective tissue disease, 1 patient of Behcet's syndrome and 1 patient of SLE showed much improved finger blood flow after combined administration of vasodilator, calcium channel blockers and antiplatelet drugs. CONCLUSIONS: The evaluation of finger blood flow with 99mTc-MDP could be considered to be one of the simple, economical and new methods that can be used in the follow-up, objective assessment of therapeutic effect, and giving an aid in the study of the pathophysiology of the Raynaud's phenomenon.

Adult↗
PubMed1992

The size of small cell lung carcinoma cells. Ratio to lymphocytes and correlation with specimen size and crush artifact.

The size of small cell lung carcinoma (SCLC) cells has often been ambiguously defined as one and a half to four times that of a lymphocyte. The purpose of this study was to determine the ratio of nuclear diameter (ND) of SCLC cells to that of lymphocytes in the same tissue sections and to assess whether the size of SCLC cells correlates with the size of tumor specimens and crush artifact. The overall mean ND (microns +/- SD) of SCLC cells was 9.2 +/- 2.1, found in 36 oat cell carcinomas (OAT, 1,800 nuclei) and 16 intermediate cell carcinomas (INT, 800 nuclei). The mean ND of OAT and INT cells was 8.1 +/- 1.3 and 11.6 +/- 1.5, respectively. The mean ND of lymphocytes (2,600 nuclei) was 5.2 +/- 0.3. The overall mean of ND ratios (+/- SD) between SCLC cells and lymphocytes was 1.8 +/- 0.4 (median, 1.7), 1.6 +/- 0.2 for OAT and 2.2 +/- 0.3 for INT. The mean size of the 52 SCLC biopsy specimens was 0.6 +/- 0.9 cm. Of all the biopsies, 84.6% (n = 44) showed various degrees of tissue crushing. The ND of SCLC cells was associated with specimen size (P = .004) and the degree of tissue crushing (P = .001). Therefore, our findings further support the hypothesis that OAT should be considered the effect of artifact rather than a true variant of SCLC and that the ND of SCLC cells is approximately two times that of lymphocytes.

Analysis of Variance↗
PubMed1992

Detection of nitric oxide by electron paramagnetic resonance spectroscopy during rejection and graft-versus-host disease after small-bowel transplantation in the rat.

BACKGROUND: Our previous observation that nitric oxide (NO) is synthesized during antigen-specific immune reactions in vitro led us to investigate whether NO is produced during the in vivo immune response to a vascularized organ allograft. METHODS: Orthotopic small-bowel transplantation in the rat was performed by standard microsurgical techniques in the LBNF1 to Lewis (rejection alone), Lewis to LBNF1 (graft-versus-host disease [GVHD] alone), and a syngeneic strain combination with and without immunosuppressive therapy with FK 506. The recipient serum NO2-/NO3- levels (stable end products of NO metabolism) were measured and erythrocytes were evaluated for the presence of nitrosylferrohemoglobin (specific for NO bound to hemoglobin). RESULTS: Animals that acutely rejected small-bowel allografts or suffered from acute GVHD showed significantly elevated serum NO2-/NO3- levels on days 6 and 9, and nitrosylferrohemoglobin electron paramagnetic resonance signals of different intensity were detected on days 3, 6, and 9. FK 506-treated allograft recipients and recipients of syngeneic grafts showed normal serum NO2-/NO3- levels and lacked nitrosylferrohemoglobin signals at all time points. CONCLUSIONS: This study indicates that NO is produced early during the course of small-bowel allograft rejection and GVHD and might therefore serve as a simple marker to detect such immune reactions.

Animals↗
PubMed1992

Predictive value of total body bone mineral density for vertebral fractures in elderly women. Geriatric Study Group.

In a general population-based geriatric disease survey in Taipei City, the bone mineral density (BMD) of 58 women over 65 years of age was measured for the whole body, lumbar spine (L2-L4), and proximal femurs using a 153Gd based dual photon absorptiometer. These women were found to have at least one vertebral fracture. The results showed that the BMD readings of both the lumbar spine (L2-L4) (mean Z score +/- SEM = 0.05 +/- 0.12) and the femoral neck (mean Z score +/- SEM = -0.20 +/- 0.10) were not statistically different from those of age-matched controls. However, the total body BMD in these 58 patients was significantly lower than in the normal controls (mean Z score +/- SEM = -1.07 +/- 0.10, p < 0.0001). In the normal control group (N = 69, age 50-85), there was a significant linear correlation between the total body and lumbar BMD (r = 0.81, p < 0.0001). This correlation was not found in the 58 women with vertebral fractures (r = 0.14, NS). Our results suggest that geriatric women with vertebral fractures are more osteoporotic than normal aged women, even though they have a relatively mild degree of spinal osteoporosis. But, because of age-associated degenerative changes or other factors, conventional anteroposterior lumbar BMD measurements cannot detect the difference. The total body BMD readings, but not the lumbar or femoral neck BMD readings, seem to be less affected by these local changes and may provide a better discriminative or predictive value for vertebral fracture in this particular age group.

Aged↗
PubMed1992

Dissociation of inhibitory effects of low-dose ASA on thromboxane production and platelet aggregation in ischemic stroke patients.

Acetylsalicylic acid (ASA) inhibits thromboxane production and hence platelet aggregation. However, individual variations in platelet aggregability and serum thromboxane B2 (TxB2) concentration after a low dose of ASA (40 mg/day) have been reported. To clarify this issue, we studied plasma thromboxane levels and platelet aggregation in 43 ischemic stroke patients. Of the 22 patients who received 100 mg of ASA daily, dissociation between inhibitory effects of ASA on the plasma TxB2 level and threshold concentrations of adenosine diphosphate was found in three cases after one month of drug administration, and in three cases after six, 12 and 18 months of ASA therapy. This dissociation also developed in two patients after one month and six months, respectively, of treatment in the 21 patients who received 300 mg of ASA daily. The dissociation between the inhibitory effects on plasma TxB2 and the circulating platelet aggregate ratio was found in two cases after taking medication for one month, and in four cases after six, 12, 18 and 24 months of therapy in the 100 mg ASA group. In the 300 mg ASA group, dissociation was noted in two cases after one month of medication, and in two cases after six and 12 months of medication. In these patients, although their TxB2 levels were inhibited to almost unmeasurable levels, platelet aggregation was still not inhibited. This ASA inhibitory dissociation phenomenon on platelet function may be due to the low dose of ASA, individual differences in platelet function in response to ASA therapy, or factors other than those involved in the cyclooxygenase system.

Aged↗
PubMed1992

The effect of tissue disaggregation methods on the clonogenicity of solid human tumor cells.

The effect of mechanical, enzymatic and combined disaggregations on the same tumor tissue (n = 154) to define variables related to clonogenic efficiency (CE) of human tumor clonogenic assay (HTCA) was examined. Overall, CE was highly associated with the percentage of malignant cells in the inoculative suspensions (P less than 0.001) and the total cell concentration plated (P = 0.03). However, there was no significant correlation between CE and the disaggregation method, type of tumor, cell viability, proportion of macrophages in the inoculum, or length of incubation (10 or 20 days). In addition, a higher CE was found in some nonadherent fractions when comparing the CE of the original plating suspensions to that of their nonadherent fractions. It is concluded that mechanical disaggregation is the simplest technique for obtaining the highest yield of malignant cells, which is a decisive factor for colony growth, and that an incubation time of 10 days and 1 x 10(6) cells per plate is the best condition for the human tumor clonogenic assay.

Gastrointestinal Neoplasms↗
PubMed1991

Construction and characterization of a single-chain catalytic antibody.

The antigen-binding (Fab) fragment of the catalytic monoclonal antibody NPN43C9 has recently been cloned by using bacteriophage lambda. By inserting the variable regions of this Fab coding sequence into a (NH2)-VL-linker-VH-(COOH) construct (where VL and VH represent the heavy and light chain variable regions), we have assembled a recombinant gene encoding a catalytic single-chain antigen-binding protein. This protein has been expressed in Escherichia coli and exhibits the same catalytic parameters as the parent monoclonal antibody NPN43C9. Single-chain forms of catalytic antibodies may prove valuable for structural and site-directed mutagenesis studies as well as for large-scale applications of catalytic antibodies.

Amino Acid Sequence↗
PubMed1991

Epidural tramadol for postoperative pain relief.

Forty-two surgical patients were given epidural tramadol for control of postoperative pain. They were randomly assigned to three groups: group 1 (n = 15), in which 25 mg of tramadol were given; group 2 (n = 13), in which 50 mg of tramadol were given; and group 3 (n = 14), in which 75 mg of tramadol were given. When the patients complained of wound pain, epidural tramadol was given. Heart rate, blood pressure, respiratory rate, oxygen saturation (SpO2), sedation scale, motor blockade, verbal rating scale, subjective grading, and visual analogue pain scale (VAPS) were measured and recorded before the tramadol administration, at 5 and 15 min, and at 1, 2, 4, and 8 h after the tramadol administration. Only 26.6% of the patients in group 1 had significant relief of pain. The rest of them needed at least one incremental dose of 25 mg of tramadol. The baseline VAPS of the patients in group 2 was 8.9 +/- 2.0. It became 5.46 +/- 3.0 (p greater than 0.05) 15 min after tramadol was given, and dropped further to 1.9 +/- 1.8 (p greater than 0.05) 2 h later. The average duration of pain relief was 12.0 +/- 5.9 h. In group 3, the initial VAPS was 8.14 +/- 1.9. It decreased to 4.28 +/- 1.8 (p greater than 0.05) 15 min, and further dropped to 1.7 +/- 0.9 (p greater than 0.05) 2 h following tramadol administration. The average duration of pain relief was 11.3 +/- 4.8 h. The common side effects of tramadol such as dizziness, nausea, and dry mouth, were most frequently found in group 3.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Comparison of in vitro platelet aggregation and its inhibition by three antithrombotic drugs between human and guinea pig.

Platelets of guinea pigs are frequently used to evaluate the effect of new antiplatelet agents. Although several studies have compared the platelet aggregation between humans and guinea pigs, but so far the information is still limited. In this study, we compare the inhibitory effect of aspirin, dipyridamole and pentoxifylline on the platelet aggregation induced by adenosine diphosphate (ADP), collagen, arachidonic acid and thrombin between humans and guinea pigs. The results for humans and guinea pigs were compared and analysed by two-way analysis of variance (ANOVA). Our results showed: 1. The trends wherein these three drugs suppressed collagen-induced platelet aggregation was very similar in humans and guinea pigs. 2. In ADP-induced aggregation, the trend of inhibition caused by the three drugs was also similar in humans and guinea pigs except that a difference in platelet disaggregation at a late phase of platelet aggregation was noted. 3. In arachidonic acid- and thrombin-induced aggregations, the trend of inhibition caused by the three drugs was somewhat different in humans and guinea pigs. 4. Considering all activators as a whole, it was found that the status of platelet disaggregation at the late phase of platelet aggregation was different in humans and guinea pigs. Therefore, we concluded that: 1. Collagen was the most appropriate platelet activator when we used platelets of guinea pigs to study the effect of new antiplatelet agents. 2. When platelets of guinea pigs were used to study platelet aggregation, no matter which activator was used, we should avoid using the late phase of aggregation as the control index for comparison, because the results thus obtained might not be applicable to human platelets.

Adenosine Diphosphate↗
PubMed1990

A simple method to create carotid endothelial laceration and acute platelet thrombus in vivo in guinea-pig.

A simple method, named 'clamp method', was developed to create carotid endothelial laceration and produce acute platelet thrombus in vivo in guinea-pig. This method used a hemostatic forceps to clamp common carotid artery of anesthetized guinea-pig at a tangent angle. Our study included two parts. The Part one demonstrated the procedures and effects of the 'clamp method': sixteen guinea-pigs were divided equally into control and heparin-treated groups. These two groups received the same clamping procedures except that the heparin-treated group was administrated with heparin (5,000U/kg) intravenously before clamping. One hour after the clamping, carotid arteries were resected and observed under scanning electron microscopy. The results showed that large carotid mural thrombi were formed in the control group with a mean surface area of 1.75 +/- 0.63 mm2 (M +/- SD, n = 8). In the heparin-treated group, the thrombus formation was prevented and linear endothelial lacerations were seen clearly. The Part two of our study identified the histologic nature of the thrombus produced by the 'clamp method': eight guinea-pigs received same procedures as that of control group in the Part one except that the carotid arteries were resected 5 min after performing the clamping. Four of the eight specimens were prepared for observation under transmission electron microscopy. The results showed that platelets adhered onto the subendothelial substances and formed platelet thrombi in the endothelial lacerations within 5 min after the carotid clamping.

Animals↗