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S H Lin

Publications and source records attributed to S H Lin.

At least 55 records · Page 3Linked to original sources
PubMed2001

The applications of capture-recapture models to epidemiological data.

Capture-recapture methodology, originally developed for estimating demographic parameters of animal populations, has been applied to human populations. This tutorial reviews various closed capture-recapture models which are applicable to ascertainment data for estimating the size of a target population based on several incomplete lists of individuals. Most epidemiological approaches merging different lists and eliminating duplicate cases are likely to be biased downwards. That is, the final merged list misses those who are in the population but were not ascertained in any of the lists. If there are no matching errors, then the duplicate information collected from a capture-recapture experiment can be used to estimate the number of missed under proper assumptions. Three approaches and their associated estimation procedures are introduced: ecological models; log-linear models, and the sample coverage approach. Each approach has its unique way of incorporating two types of source dependencies: local (list) dependence and dependence due to heterogeneity. An interactive program, CARE (for capture-recapture) developed by the authors is demonstrated using four real data sets. One set of data deals with infection by the acute hepatitis A virus in an outbreak in Taiwan; the other three sets are ascertainment data on diabetes, spina bifida and infants' congenital anomaly discussed in the literature. These data sets provide examples to show the usefulness of the capture-recapture method in correcting for under-ascertainment. The limitations of the methodology and some cautionary remarks are also discussed.

Adult↗
PubMed2001

Cell cycle induction in post-mitotic neurons proceeds in concert with the initial phase of programmed cell death in rat.

Neuronal programmed cell death (PCD) is increasingly becoming recognized as a dynamic process that may be amenable to resolution. Critical to this resolution is the identification of the cellular pathways that modulate the initial stages of apoptotic death. In this regard, we examined whether the activation of a latent cell cycle was associated with the initial phase of PCD. We demonstrate that free radical nitric oxide induced PCD results in the rapid generation of membrane phosphatidylserine residue exposure. This early phase of PCD functions in parallel with an untoward attempt to enter the cell cycle in the same population of post-mitotic neurons. We therefore offer an attractive molecular target to prevent or reverse neuronal PCD by elucidating a novel mechanism through which the majority of neurons meet their demise by attempting to enter a latent cell cycle.

Animals↗
PubMed2001

Adsorption of hydrazoic acid from aqueous solution by macroreticular resin.

Sodium azide is a key component in the automobile air bag. When dissolved in aqueous solution, it reacts rapidly with water to form hydrazoic acid which is a highly toxic chemical and is strongly regulated by government. In the present study, adsorption of hydrazoic acid from aqueous solution by macroreticular resin is investigated. This method can provides a convenient means for dealing with the toxic hydrazoic acid. Experimental tests of batch equilibrium adsorption and continuous column adsorption of hydrazoic acid were conducted and the test results were employed to establish adsorption isotherm and to evaluate the column adsorption efficiency. The test results revealed that the multilayer adsorption isotherms, like the modified Langmuir or Jossens model, are needed to adequately describe the hydrazoic acid adsorption equilibrium between the liquid and solid (resin) phases. In the column adsorption process, a theoretical model was adopted for representing the hydrazoic acid change in the aqueous solution exiting the column and the verified theoretical model significantly facilitates prediction of adsorption breakthroughs and column design. Regeneration of exhausted resin was investigated. Solution of 10% (w/w) NaCl was found to be a very efficient regenerant.

Adsorption↗
PubMed2001

Differences in tissue-specific and embryonic expression of mouse Ceacam1 and Ceacam2 genes.

The intercellular adhesion molecule CEACAM1, also known as C-CAM1 (where CAM is cell-adhesion molecule), can function as a tumour suppressor in several carcinomas, including those of the prostate, breast, bladder and colon. This suggests that CEACAM1 may play an important role in the regulation of normal cell growth and differentiation. However, there is no direct evidence to support this putative function of CEACAM1. To elucidate its physiological function by targeted gene deletion, we isolated the Ceacam genes from a mouse 129 Sv/Ev library. Although there is only one Ceacam1 gene in humans and one in rats, two homologous genes (Ceacam1 and Ceacam2) have been identified in the mouse. Our sequence analysis revealed that the genes encoded nine exons and spanned approx. 16-17 kb (Ceacam1) and 25 kb (Ceacam2). The genes were highly similar (79.6%). The major differences in the protein-coding regions were located in exons 2, 5 and 6 (76.9%, 87.0% and 78.5% similarity respectively). In addition, introns 2, 5 and 7 were also significantly different, being 29.7%, 59.8% and 64.5% similar respectively. While most of these differences were due to nucleotide substitutions, two insertions of 418 and 5849 bp occurred in intron 2 of Ceacam2, and another two insertions of 1384 and 197 bp occurred in introns 5 and 7 respectively. To determine whether functional redundancy exists between Ceacam1 and Ceacam2, we examined their expression in 16 mouse tissues by using semi-quantitative reverse transcription-PCR. As in human and rat, in the mouse Ceacam1 mRNA was highly abundant in the liver, small intestine, prostate and spleen. In contrast, Ceacam2 mRNA was only detected in kidney, testis and, to a lesser extent, spleen. Reverse transcription-PCR using testis RNA indicated that Ceacam2 in the testis is an alternatively spliced form containing only exons 1, 2, 5, 6, 8 and 9. In the mouse embryo, Ceacam1 mRNA was detected at day 8.5, disappeared between days 9.5 and 12.5, and re-appeared at day 19. On the other hand, no Ceacam2 mRNA was detected throughout embryonic development. The different tissue expression patterns and regulation during embryonic development suggest that the CEACAM1 and CEACAM2 proteins, although highly similar, may have different functions both during mouse development and in adulthood.

Adenosine Triphosphatases↗
PubMed2001

Group I metabotropic glutamate receptors prevent endothelial programmed cell death independent from MAP kinase p38 activation in rat.

Activation of Group I metabotropic glutamate receptors (mGluRs) prevents neuronal programmed cell death (PCD), but the role of these receptors in the vascular endothelial cell (EC) system has not been defined. Since ECs are principal targets for ischemic free radical injury, we examined whether the mGluR system could modulate vascular PCD. Activation of the Group I mGluR system, but not antagonism, addressed two distinct pathways of PCD by preventing the destruction of genomic DNA and maintaining EC membrane asymmetry. The induction of nitric oxide (NO)-induced PCD in ECs paralleled the specific activation of the MAP kinase p38 pathway, but the vascular protection conferred by the Group I mGluR system appears to rely on more downstream cellular pathways. We provide initial evidence for Group I mGluRs to prevent NO-induced vascular injury and offer new directions for vascular disease treatment.

Animals↗
PubMed2001

Signal transduction by the CEACAM1 tumor suppressor. Phosphorylation of serine 503 is required for growth-inhibitory activity.

CEACAM1 is a cell-cell adhesion molecule that mediates homophilic cell adhesion. In addition, CEACAM1 was also shown to suppress the growth of prostate, breast, and colon tumors. Structural and functional analyses showed that the adhesion activity of CEACAM1 is mediated by its extracellular domain while its cytoplasmic domain is necessary and sufficient for growth-inhibitory activity. The signal pathways leading to CEACAM1-mediated growth suppression are not known. We studied the importance of phosphorylation of serine 503 in this growth-inhibitory signaling pathway. Full-length CEACAM1 was found to be phosphorylated in vivo in both tyrosine and serine residues. Mutation of tyrosine 488 to phenylalanine did not abolish the tumor-suppressive activity of CEACAM1, suggesting that phosphorylation at tyrosine 488 is not critical for CEACAM1's tumor-suppressive activity. Although expression of CEACAM1's cytoplasmic domain inhibited the growth of DU145 prostate cancer cells in vivo, mutation of serine 503 to alanine abolished the growth-inhibitory activity. In addition, the change of serine 503 to aspartic acid produced tumor-suppressive activity similar to that of the wild-type CEACAM1. These results suggested that phosphorylation at serine 503 is essential for CEACAM1's growth-inhibitory function in vivo.

Alanine↗
PubMed2001

Expression of a truncated first exon BCR sequence in chronic myelogenous leukemia cells blocks cell growth and induces cell death.

We have shown that a deletion mutant form of Bcr [Bcr(64-413)] is a strong inhibitor of the tyrosine kinase of Bcr-Abl in vitro and also inhibits its oncogenic growth effects (Liu et al., Cancer Res., 56: 5120-5124, 1996). To determine the effects of this Bcr-Abl kinase inhibitor on chronic myelogenous leukemia (CML) cells, we cloned BCR(64-413) into a recombinant, replication-defective adenovirus to express useful quantities of Bcr(64-413) in a wide variety of cells in culture. Infection of Cos1 cells with plaque-purified virus at a multiplicity of infection of 20-40 induced high expression of Bcr(64-413) as detected by Western blotting. Infection of hematopoietic cells at modest multiplicities of infection (20-40) required special conditions involving shifting cycling cells to a nongrowing condition involving serum starvation and cell crowding. Under these conditions, both Bcr-Abl-positive and -negative hematopoietic cells can be efficiently infected by adenovirus, as demonstrated by 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside staining of cells infected by beta-galactosidase (beta-GAL) adenovirus. We found that expression of Bcr(64-413) in Bcr-Abl-positive K562 and BV-173 cells, but not Bcr-Abl-negative SMS-SB cells, increased cell-cell clumping and inhibited cell growth. In contrast to the effects of the Bcr(64-413) adenovirus, the beta-GAL adenovirus, despite infecting both types of cells, did not block growth or increase cell-cell clumping of Bcr-Abl-positive and -negative hematopoietic cells. Expression of Bcr(64-413) protein in primary cultures of cells from CML patients with active disease interfered with cell growth, induced apoptosis (as measured by annexin staining), and increased cell-cell clumping, whereas the beta-GAL adenovirus and mock-infected cells lacked these effects. In contrast, normal marrow cells did not exhibit these effects on infection with Bcr(64-413) adenovirus. We conclude from these findings that Bcr(64-413) interferes with the oncogenic effects of Bcr-Abl and therefore has the potential for use in therapy of CML.

Adenoviridae↗
PubMed2001

Purification and characterization of human cell--cell adhesion molecule 1 (C-CAM1) expressed in insect cells.

The cell--cell adhesion molecule 1 (C-CAM1) plays an important role as a tumor suppressor for prostate cancer. Decreased expression of C-CAM1 was detected in prostate, breast, and colon carcinoma. Reexpression of C-CAM1 in prostate and breast cancer cell lines was able to suppress tumorigenicity in vivo. These observations suggest that C-CAM1 may be used as a marker for cancer detection or diagnosis. To generate monoclonal antibodies specific to C-CAM1, we have overexpressed full-length human C-CAM1 in Sf9 cells using a baculovirus expression system. The protein was purified 104-fold using nickel affinity chromatography. About 0.4 mg purified C-CAM1 was obtained from 200 mg of infected cells. When the purified protein was digested with peptidyl-N-glycosidase, the apparent mobility of the protein on SDS--PAGE changed from 90 to 58 kDa, which is close to the molecular weight predicted from the cloned cDNA sequence. This observation suggests that C-CAM1 was glycosylated on asparagine residues when expressed in Sf9 cells. Western blotting and internal protein sequencing analysis confirmed that the purified protein is human C-CAM1. Biochemical and functional assays indicate that this protein expressed in Sf9 cells displays characteristics similar to those of native protein, including adhesion function and glycosylation modification. Using this protocol, sufficient quantity of this protein can be produced with purity suitable for monoclonal antibody generation and biochemical study.

Adenosine Triphosphatases↗
PubMed2001

UV-induced increase in RNA polymerase activity in Xanthomonas oryzae pathovar oryzae.

UV radiation is thought to inhibit transcriptional elongation, as a result of the formation of pyrimidine dimers in the DNA template, as well as to activate specific transcription factors. However, the effect of UV radiation on the enzymatic activity of RNA polymerase has remained unknown. With the use of an in vitro assay, UV irradiation of Xanthomonas oryzae pathovar oryzae has now been shown to increase RNA polymerase activity. This effect was maximal at a UV dose of approximately 12 J m(-2) and at approximately 60 min after irradiation. It was also not inhibited by pretreatment of cells with chloramphenicol, an inhibitor of protein synthesis. Immunoprecipitation with antibodies to the RNA polymerase core enzyme revealed that exposure of the bacterial cells to UV radiation induced the association of the core enzyme with a protein of approximately 29 kDa. These results demonstrate that UV radiation increases the activity of RNA polymerase, and they suggest that this effect may be related to the repair of DNA damage.

Bacterial Proteins↗
PubMed2001

Novel neurotransmitters as natural ligands of orphan G-protein-coupled receptors.

The "orphan" G-protein-coupled receptors (GPCRs) are cloned GPCRs that bind unknown ligands. Since 1995, nineteen orphan GPCRs have been used as targets to identify and isolate their natural ligands via the application of the "orphan receptor strategy". These ligands are peptides, lipids or biogenic amines, and act as transmitter molecules. One nucleotide-sugar derivative and six peptides or peptide families identified through this strategy are novel and have already enriched our understanding of various brain functions.

Animals↗
PubMed2001

A comparison of insulin suppression tests performed with somatostatin and octreotide with particular reference to tolerability.

To evaluate the tolerability of insulin suppression test (IST) using octreotide instead of somatostatin, we compared the steady-state plasma glucose (SSPG) values and the safety during and after the test in 17 normal volunteers. The subject received IST twice (with somatostatin or with octreotide) in random order. During the test, all subjects were infused with regular insulin and glucose simultaneously for 180 min. In addition, either somatostatin or octreotide was infused intravenously over the same period of time. Plasma glucose, insulin and C-peptide were measured. The subject response to the test was recorded during and one day after the test by a structured questionnaire. The SSPG and the steady-state plasma insulin (SSPI) values reached during IST were similar, irrespective of the use of somatostatin or octreotide. There was a positive correlation between the SSPG values obtained from both methods (r = 0.67, P = 0.003). However, the mean intra-individual coefficient of variation is 17.9% for SSPG. The SSPG levels, no matter from which method, correlated positively with the 2-h insulin after oral glucose challenge. Most adverse events (especially gastrointestinal discomfort) occurred after the test, and increased much more after using octreotide than somatostatin (P = 0.002 by chi 2 test). In conclusion, the SSPG values measured by IST using octreotide or somatostatin are similar in normal healthy subjects. Yet, the octreotide method has more adverse events after the test.

Adult↗
PubMed2001

Abnormal cardiovascular reflex tests are predictors of mortality in Type 2 diabetes mellitus.

AIMS: To determine whether diabetic autonomic neuropathy is an important factor contributing to mortality in Type 2 diabetes mellitus. METHODS: Between 1989 and 1993, 431 men and 181 women with Type 2 diabetes were given diabetic autonomic neuropathy cardiovascular reflex (CVR) tests. These subjects were followed for the subsequent 5--9 years to assess mortality rates. RESULTS: The prevalence rate of abnormal CVR tests was 46.1% in patients with the history of diabetes less than 5 years and up to 69.4% when the history of diabetes exceeded 20 years. During the follow-up period from 1 January 1989 to 31 December 1997 (mean 7.7 years), a total of 135 participants died. The 8-year survival rate for patients with abnormal CVR tests was 63.6% in males and 76.4% in females, compared with 80.9 and 93.3% for patients with normal CVR tests. The results were grouped as: group 1, normal CVR tests without postural hypotension (PHT); group 2, normal CVR tests with PHT; group 3, abnormal CVR tests without PHT; and group 4, abnormal CVR tests with PHT. The 8-year survival rate was 85.4% in group 1, 80.9% in group 2, 74.5% in group 3 and 61.1% in group 4. CONCLUSION: Type 2 diabetic patients with abnormal CVR tests may have increased mortality, and those combined with postural hypotension have higher mortality than those without. Abnormal CVR tests may be important predictors of mortality in Type 2 diabetes mellitus.

Blood Pressure↗
PubMed2001

An improved method for determination of heavy metal bioavailability in contaminated soil.

Bioavailability of heavy metal in contaminated soil is investigated. A general diffusion model for determining the heavy metal bioavailability in soil has been developed The bioavailability predictions based on the present model were more accurate than those based on a previous model. Experimental results obtained using cadmium-, copper-, zinc- and lead-contaminated soils were employed for model verification. The effects of soil pH, initial heavy metal concentration, temperature and soil type on the effective diffusion coefficient or bioavailability index were also examined experimentally. The theoretical model and experimental procedure proposed in the present study provide a convenient means for the determination of heavy metal or inorganic ion bioavailability in contaminated soil.

Biological Availability↗
PubMed2001

Hypokalaemia and paralysis.

It is not uncommon for patients to present to the emergency room with severe weakness and a markedly low plasma potassium concentration. We attempted to identify useful clues to the diagnosis of hypokalaemic periodic paralysis (HPP), because its acute treatment aims are unique. We retrospectively reviewed charts over a 10-year period: HPP was the initial diagnosis in 97 patients. Mean patient age was 29+/-1.1 and the male:female ratio was 77:20. When the final diagnosis was HPP (n=73), the acid-base state was normal, the urine K(+) concentration was low, and the transtubular K(+) concentration gradient (TTKG) was <3. In patients with thyrotoxic periodic paralysis (TPP) (n=39), hypokalaemia was very commonly accompanied by hypophosphataemia (1.9+/-0.1 mg/dl). A clinical diagnosis of sporadic periodic paralysis (SPP) was made if hyperthyroidism and a family history of HPP were both absent (n=29). One subgroup of patients with HPP had a severe degree of hypernatraemia (167+/-5.0 mmol/l, n=3). There were only two patients with familial periodic paralysis (FPP). In 24 patients, the initial diagnosis was HPP, but subsequent studies failed to confirm this diagnosis. Each of these patients had an acid-base disorder, a high rate of renal K(+) excretion in the presence of hypokalaemia, and a TTKG of close to 7. With respect to therapy, much less K(+) was given to patients with HPP, yet 1:3 subsequently had a plasma K(+) concentration that eventually exceeded 5.0 mmol/l. Using plasma acid-base status, phosphate and K(+) excretion parameters allows a presumptive diagnosis of HPP with more confidence in the emergency room.

Acid-Base Equilibrium↗
PubMed2001

The metabotropic glutamate receptor system protects against ischemic free radical programmed cell death in rat brain endothelial cells.

As one of the key determinants of ischemic injury, cerebrovascular endothelial cell (EC) degeneration may be dependent upon the generation of the free radical nitric oxide (NO) and the subsequent induction of programmed cell death (PCD). Although the mechanisms that can prevent EC injury are most likely multifactorial in origin, the metabotropic glutamate receptor (mGluR) system may represent a novel therapeutic approach for ECs given the ability of the mGluR system to reverse neuronal cell injury. This study examined the modulation of individual subtypes of mGluRs during anoxia and NO toxicity in primary rat cerebrovascular ECs. Cell injury was determined through trypan blue dye exclusion, intracellular lactate dehydrogenase release, DNA fragmentation, membrane phosphatidylserine (PS) exposure, and cysteine protease activity. Anoxia, through the generation of NO, and exposure to exogenous NO were directly toxic to ECs. Exposure to NO rapidly decreased EC viability from 98% +/- 2% to 40% +/- 9%, increased DNA fragmentation from 2% +/- 2% to 61% +/- 9%, and increased membrane PS exposure from 3% +/- 3% to 66% +/- 6% over a 24-hour period. Activation of the mGluR system significantly increased EC survival through the prevention of NO-induced DNA fragmentation and cellular membrane PS residue exposure. In contrast, antagonism of the mGluR system failed to prevent PCD. Cytoprotection by the mGluR system was dependent, at least in part, upon the direct inhibition of NO-generated caspase 1- and caspase 3-like activities. Further investigation into the ability of the mGluR system to prevent PCD in ECs may open new therapeutic avenues for the treatment of cerebrovascular injury.

Animals↗
PubMed2001

The carboxyl terminus of the prolactin-releasing peptide receptor interacts with PDZ domain proteins involved in alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor clustering.

PDZ domain proteins use the PDZ domain binding motif to bind to the C-terminal sequence of membrane proteins to help scaffold them and spatially organize the components of the intracellular signaling machinery. We have identified a sequence at the C terminus of a G protein-coupled receptor, the PrRP receptor, that shares similarities with the C-terminal sequence of alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor (AMPA-R) subunits that interact with PDZ domain proteins. When coexpressed in human embryonic kidney 293 cells, PrRP receptor was able to coimmunoprecipitate the three PDZ domain proteins known to interact with AMPA receptors: glutamate receptor interacting protein (GRIP), AMPA binding protein (ABP), and protein that interacts with C-kinase (PICK1), but not the PDZ domain protein PSD-95, which does not interact with AMPA receptors. These interactions are sequence-selective as determined by mutagenesis. Furthermore, we show that PrRP receptor forms intracellular clusters when coexpressed with PICK1, and that this clustering effect is dependent on the interaction between the PICK1 PDZ domain and the last four amino acids of PrRP receptor. We found that PrRP receptor interaction with GRIP is not protein kinase C-regulated but may be regulated by other unidentified kinase because okadaic acid dramatically reduced GRIP interaction. By in situ hybridization, we show that the PrRP receptor is expressed in neurons that also express these PDZ domain proteins. We thus demonstrate that PrRP receptor interacts with the same PDZ domain proteins as the AMPA-Rs, raising the possibility that these two proteins could be scaffolded together at the synapse. These results may help to gain important insights into PrRP functions within the central nervous system.

Adaptor Proteins, Signal Transducing↗