Biomedical subjects
Publications and source records attributed to S H Lin.
The time-dependent Schrödinger equation for two quite general types of perturbation has been solved by introducing the Laplace transforms to eliminate the time variable. The resulting time-independent differential equation can then be solved by the perturbation method, the variation method, the variation-perturbation method, and other methods.
The reaction cross section of a bimolecular reaction has been calculated from the corresponding rate constant by the inverse Laplace transform. In carrying out the inverse Laplace transform, the method of steepest-descent has been used. As applications, the reaction cross sections for the rate constant of k(T) = k' T(n)e(-E0/kT) and for the rate constant of the absolute reaction rate theory have been calculated. The computation of the energy density function associated with the definition of the weighted-average cross section has also been discussed.
A theoretical model for the accumulation of pesticides in soil has been proposed and discussed from the viewpoint of heterogeneous reaction kinetics with a basic aim to understand the complex nature of soil processes relating to the environmental pollution. In the bulk of soil, the pesticide disappears by diffusion and a chemical reaction; the rate processes considered on the surface of soil are diffusion, chemical reaction, vaporization, and regular pesticide application. The differential equations involved have been solved analytically by the Laplace-transform method.
The purpose of this paper is to investigate the nature of band shapes of emission spectra and their relation to the rate of nonradiative processes. Two cases are discussed, one in which the Franck-Condon principle applies and the other in which the electronic transition is symmetry-forbidden but vibronic-allowed. The moment relations of emission spectra have been derived and their applications demonstrated.The vibrational structuring in emission spectra is discussed and empirical equations for calculation of the shapes of vibrational bands are derived. It is found that from the shapes of vibrational bands one can obtain the information of intermolecular vibration and from the areas under vibrational bands one can determine the Franck-Condon factors of intramolecular vibration.
The first-order and zero-order kinetics of heterogeneous reactions coupled with the diffusion process are studied. The differential equations of these reaction systems are solved for the cases in which the fluid is not stirred and the fluid is well stirred. It is shown that both the rate constants and the diffusion coefficient can be determined in various ways depending on the experimental conditions.
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The interaction between alcohols (ethanol and n-butanol) and dipalmitoylphosphatidylcholine (DPPC) in carbon tetrachloride was studied by Fourier transform infrared spectroscopy (FTIR). Upon addition of the alcohols, the P = O stretching band of DPPC at 1260 cm-1 shifted to lower frequency (red-shift). The red-shift indicates that the P = O vibration became slower possibly because the heavier alcohol molecules replaced the water molecules hydrogen bonded to the PO2 moiety. The formation constants between the PO2 group and ethanol or n-butanol (n-butanol data in parenthesis) were 19.0 M-1 (7.1 M-1) when estimated from the spectral change. A new absorbance peak appeared at 3265 cm-1 (3275 cm-1) representing the DPPC-alcohol complex. The formation constant of this complex was also 19.0 M-1 (7.1 M-1). The identical formation constant suggests that the DPPC-alcohol complex was formed at the PO2 moiety of DPPC with hydrogen bonding to the alcohol OH. At higher alcohol concentrations, the absorbance peak of DPPC-alcohol complex shifted to 3225 cm-1 (3235 cm-1). Apparently, the lower frequency shift at higher alcohol concentration occurred by the formation of alcohol multimers (dimer, trimer, and tetramer) interacting with DPPC.
The geometries of the Fe-O2 and Fe-CO bonds in myoglobin and haemoglobin differ significantly from those in free porphyrin model compounds. It has been suggested that steric hindrance by Val-E11 and His-E7 and a hydrogen bond between His-E7 and oxygen affect the geometry and electronic state of the Fe-ligand bond, and that these interactions may be important in controlling oxygen affinity. We have produced mutant haemoglobins in E. coli having Val(67 beta)E11 replaced by Ala, Met, Leu or Ile and His(58 beta)E7 by Gln, Val or Gly. We have studied the effect of these mutations on the equilibrium and kinetics of ligand binding. The conformation of the new side chains and their effect on the protein structure have been examined by X-ray crystallography, and the vibrational properties of the Fe-CO bond observed by resonance Raman spectroscopy. We found that the steric hindrance of ligand binding by the E11 residue and the polarity of the E7 residue in the beta subunit are critical for fine-tuning ligand affinity.
CD66a (human homolog of rat cell-cell adhesion molecule, also known as biliary glycoprotein) is a cell surface protein of the immunoglobulin family. CD66a has been shown to mediate homotypic cell adhesion. Aside from this, no other functions of this molecule have been demonstrated. We have observed previously that CD66a protein expression is lost in most prostate tumors, suggesting that the down-regulation of CD66a is associated with the abnormal growth of prostate cells. CD66a is homologous (65% identity) to rat cell-cell adhesion molecule, which has been shown to have tumor-suppressive activity. This homology suggests the possibility that CD66a might also be a tumor suppressor. In this report, we show that restoring CD66a expression in DU145 human prostate cancer cells by adenovirus (Ad)-mediated gene transfer dramatically altered the malignant phenotype of these cells, as evidenced by their reduced ability to form tumors in a xenograft animal model. This result suggests that loss of CD66a protein plays an important role in the development of prostate cancer, and that restoring CD66a expression might provide an effective treatment for prostate cancer. We further explored the possibility of using Ad vectors to deliver CD66a as a potential therapeutic agent for prostate cancer. Direct injection of Ad-CD66a, an Ad vector carrying the CD66a gene, into DU145 tumors in mice significantly suppressed the growth of these tumors. This antitumor activity of CD66a was found to be dose-dependent. These results suggest that CD66a has tumor-suppressive activity and that Ad-CD66a is a potential therapeutic agent for prostate cancer treatment.
Metabolic acidosis induces a combination of inhibited osteoblastic and stimulated osteoclastic activity. To determine the role of alkali therapy in osteoblast function in chronic renal failure, serum bone isoenzyme of alkaline phosphatase (BAP) and osteocalcin were assessed before and after bicarbonate infusion. Eighteen patients with mild to moderate metabolic acidosis, none of whom had received dialysis therapy, were enrolled in this study. Metabolic acidosis was corrected by continuous bicarbonate infusion while plasma ionized calcium was monitored at 5 min intervals and held at the preinfusion level by calcium solution infusion during the entire procedure. The end-point of the study was reached when the plasma bicarbonate was approximately 24 mmol/l or pH was approximately 7.4 and plasma ionized calcium was clamped at the preinfusion level with only a 0.01 mmol/l fluctuation. The plasma pH (7.31 +/- 0.04 vs. 7.40 +/- 0.03, P < 0.001), bicarbonate (18.46 +/- 2.49 vs. 23.66 +/- 2.72 mmol/l, P < 0.001), serum total calcium, and osteocalcin (15.61 +/- 6.45 vs. 18.79 +/- 6.71 mg/l, P < 0.05) levels were significantly increased, whereas serum concentrations of alkaline phosphatase and albumin levels were significantly decreased after bicarbonate infusion. The serum BAP (1.85 +/- 1.29 vs. 1.79 +/- 1.18 mukat/l, P = 0.252), and inorganic phosphorus levels showed no significant differences before and after bicarbonate infusion. These results demonstrate that rapid correction of metabolic acidosis improves osteoblast function and may underline the importance of maintaining normal acid-base homeostasis in chronic renal failure.
A subset of patients on long-term hemodialysis have sustained hypotension, defined as a predialysis systolic pressure of < 100 mmHg. To determine the role of nitric oxide (NO), an important vasodilator, in this condition, the authors measured the plasma levels of nitrite (NO2-) and nitrate (NO3-), the known NO metabolites taken as an index of NO production, in 10 hypotensive patients on long-term hemodialysis. None of them had diabetes, cirrhosis of the liver, congestive heart failure, or infection. Fifteen age and gender-matched normotensive patients on hemodialysis were selected as control subjects. Measurements of plasma levels of nitrite and nitrate based on the Greiss reaction were made. There was no significant difference in hematocrit, serum intact parathyroid hormone, total calcium, inorganic phosphorus, albumin, heart rate, cardiac index, or interdialysis weight gain between these two groups. Plasma nitrite and nitrate levels did not correlate with either predialysis serum creatinine or blood urea nitrogen. The mean arterial pressure (MAP) was significantly lower and plasma nitrite and nitrate levels were significantly higher in chronic hypotensive patients than in normotensive patients (MAP: 68.30 +/- 3.24 mmHg vs 95.20 +/- 2.44 mmHg, p < 0.001; plasma nitrite and nitrate: 72.49 +/- 14.41 mumol/L vs 36.42 +/- 5.45 mumol/L, p < 0.05). In addition, MAP from hypotensive and normotensive patients on hemodialysis was inversely correlated with plasma levels of nitrite and nitrate (r = -0.54, p < 0.01). It was concluded that enhanced NO production in this subset of patients on hemodialysis may contribute to their chronic hypotension.
Dry weight evaluation is generally made from clinical observation of body weight (BW) changes, edema, blood pressure, and chest radiograph. In fact, 25-50% of patients on chronic hemodialysis had an incorrectly determined dry weight. To predict dry weight, twenty stable patients on regular hemodialysis were enrolled to investigate the correlation among dry weight, hematocrit, blood volume (BV), and vasoactive hormones including plasma renin activity (PRA), aldosterone (PA), and cyclic 3',5'-guanosine monophosphate (cGMP) values. BV was estimated by an infrared light reflection method. PRA, PA, and plasma cGMP were determined by commercial radioimmunoassay kits. The results showed significantly decreasing plasma cGMP values toward the end of hemodialysis compared with before hemodialysis (15.76 +/- 3.56 pmol/ml vs 33.57 +/- 3.98 pmol/ml; p < 0.05). A significant correlation exists between changes in plasma cGMP values and BV (p < 0.05). In addition, no significant correlation exists between changes in plasma cGMP and BW. A good correlation was found between changes in BV and hematocrit throughout dialysis (r = -0.774; p < 0.001). PRA and PA values predict neither BV nor BW changes. All patients were treated to attain a further ultrafiltration of 0.5 to 1.0 L after reaching dry weight, and we found that the critical point in blood pressure drop occurred when BV decreased by 8% or when plasma cGMP values decreased by 50% from their initial values. Continuous BV monitoring with infrared light reflection and detecting of cGMP throughout hemodialysis could help predict dry weight and avoid dialysis hypotension.
OBJECTIVE: The objectives of this study were to evaluate the psychological consequences of combination antiretroviral treatment in terms of mood, hope, and life satisfaction in men with symptomatic human immunodeficiency virus (HIV) infection or acquired immune deficiency syndrome and to compare those whose health improved with those whose health did not improve. METHODS: One hundred seventy-three HIV+ gay or bisexual men with symptomatic HIV illness (40% nonwhite) were evaluated semiannually in a university-affiliated research program between July 1995 and December 1997. The primary outcome measures were the Structured Clinical Interview for DSM-IV, Beck Depression Inventory, Endicott Quality of Life Enjoyment and Satisfaction Questionnaire, and Beck Hopelessness Scale. RESULTS: Psychological distress in this sample was mild to moderate at baseline. During the first 2 years that highly active antiretroviral therapy became widely available, we observed a statistically significant but clinically modest reduction in distress in the sample as a whole, with significant covariates of CD4 cell count, HIV symptoms, and social support in a mixed-effects model. Rates of clinical depression declined. However, this generalized mental health improvement was not related to individual medical improvement of markers of HIV illness progression; those classified as improved were no more likely than those who remained unimproved to report greater declines in measures of distress and hopelessness. Number of self-reported physical symptoms were directly related to distress levels. CONCLUSIONS: A cohort effect was observed, with overall psychological improvement. Physical symptoms were more strongly related to psychological distress than were laboratory markers. Consequently, those whose CD4 cell count and HIV RNA viral load reflected successful treatment were no more likely than others to be relieved of the psychological burdens of illness.
BACKGROUND: C-CAM1 functions as a tumor suppressor in prostate cancer. Thus C-CAM1 recombinant adenovirus therapy may be a promising treatment for prostate cancer. Understanding the time course of C-CAM1's antitumor activity is essential for designing an optimal schedule for C-CAM1 gene therapy. MATERIALS AND METHODS: PC3 cells were exposed to Ad-C-CAM1 and the time course of C-CAM1 expression was monitored by flow cytometry. Tumors generated in nude mice by subcutaneous injection of PC-3 cells were used for in vivo testing of C-CAM1's antitumor activity. Intratumoral injections of viruses (either Ad-C-CAM1 or Ad-beta-gal) or buffer only (control) were performed according to two different schedules. Mice in Schedule A received a single injection, while mice in Schedule B received the same total amount of viruses in 3 equal doses at 2-week intervals. RESULTS: After single exposure to Ad-C-CAM1, PC-3 cells expressed abundant C-CAM1 protein which reached the highest level on day 3 and persisted for up to 5 days. PC-3 tumors in nude mice exhibited 2 to 3-week lag in tumor growth curves after a single Ad-C-CAM1 injection. In contrast, 14 of the 18 tumors receiving 3 fractionated Ad-C-CAM1 injections regressed completely, while the other 4 tumors shrank to significantly smaller sizes. CONCLUSIONS: Sustained expression of C-CAM1 is required for optimal tumor suppression. The schedule-dependence of C-CAM1's antitumor activity should be taken into account in optimizing gene therapy in clinical settings.
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In order to estimate the seroprevalence and explore multiple risk factors associated with Helicobacter pylori infection among residents in Taiwan, a total of 823 subjects randomly selected from one metropolitan precinct and three townships were studied. Serum samples were tested for IgG antibodies against H. pylori by enzyme-linked immunosorbent assay using commercial kits. The overall seropositive rate was 54.4% with no gender difference (53.7% for males and 55.2% for females). There was a significant geographical variation with the highest seropositive rate (63.4%) in rural area where aborigines live, and where the age-adjusted stomach cancer mortality is highest and the lowest (40.5%) in urban area where Hakkas live, and where the stomach cancer mortality is lowest. There was also an increasing seropositive rate with age from 27.1% for children younger than 10 years old to 72.3% for adults aged more than 40 years old. Age-specific seroprevalence in Taiwan is higher than that in United States, France, Finland and Australia, and lower than that in Algeria, Ivory Coast and India. No association with H. pylori seropositivity was observed for drinking water source, toilet type, family income and educational level after adjusting for age and area. A dose-response relation between H. pylori seropositivity and sibship size was found. Upon further analysis of seroprevalence for children aged 16 or younger, a positive association was observed for birth order and current number of children in family; there was also an inverse association for current number of adults in family. The early childhood transmission among siblings seems an important determinant of H. pylori seropositivity in Taiwan.
BACKGROUND/AIMS: This study investigates the clinical features of chronic calcifying pancreatitis (CCP) in Taiwan and also the comparative differences in the disorder as it affects orientals and occidentals. MATERIALS AND METHODS: Medical records at seven tertiary hospitals relating to patients diagnosed with CCP between 1976 and 1996 are reviewed and analyzed. Ninety patients were enrolled. Defining the calcification of the pancreas is achieved by plain film, ultrasonography, computed tomography, or histology. RESULTS: CCP afflicts men more frequently than it does women, by a ratio of 3.5:1 (70 men and 20 women). The mean age is 45 years (male: 46 female: 41.4). For fifty-two patients (57.8%), alcohol is the major cause of the condition, while in others, the causes are non-alcoholic (idiopathic: 31; biliary: 4; hereditary: 3). Alcoholism is mainly associated with males and younger sufferers. The major complications are diabetes mellitus (53.3%), cysts or pseudocysts (21.1%), and biliary stricture or stones (20%). Pancreatic adenocarcinoma and splenic vein thrombosis were found in six and five patients, respectively. Three patients died from cancers of other than pancreatic origin (lung: 1;liver: 1;bile duct: 1). Thirty-three patients were treated surgically of which thirteen (39.4%), including one with pancreatic auto transplantation, improved. Fifty-seven patients received medical treatment but only eleven (19.3%) improved. CONCLUSIONS: The clinical features of CCP in Taiwan are notably similar to those manifesting in western countries and in Japan. With the changes in life style and increased alcoholic consumption in Taiwan, the prevalence of CCP may increase and its demographic features may alter in the future.