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T S Ho

Publications and source records attributed to T S Ho.

5 recordsLinked to original sources
PubMed1999

Constructing multidimensional molecular potential energy surfaces from ab initio data.

This paper describes the reproducing kernel Hilbert space (RKHS) method for constructing accurate, smooth, and efficient global potential energy surface (PES) representations for polyatomic systems using high-level ab initio data. The RKHS method provides a rigorous and effective framework for smooth multivariate interpolation of arbitrarily scattered data points and also for incorporating various physical requirements onto the PESs. Smoothness, permutation symmetry, and the asymptotic properties of polyatomic systems can be incorporated into the construction of reproducing kernels to render globally accurate PESs. Tensor products of one-dimensional generalized-spline-reproducing kernels are amenable to a fast algorithm, which makes a single evaluation of RKHS PESs essentially independent of the number of interpolated ab initio data points. This efficient implementation enables the study of the detailed dynamics of polyatomic systems based on high-quality RKHS PESs.

Journal Article↗
PubMed1997

Intracerebral injection of myelin basic protein (MBP) induces inflammation in brain and causes paraplegia in MBP-sensitized B6 mice.

Brain inflammation and paraplegia can be induced by an additional intraperitoneal (i.p.) and intracerebral (i.c.) restimulation in B6 mice after standard immunization with MBP in Freund's complete adjuvant (FCA) and Bordetella pertussis coadjuvant. Only the combination of i.p. MBP/FCA and i.c. MBP injection could induce clinical paraplegia; either one alone was not effective. Clinical symptoms would develop 2 days after the i.c. injection. The induction of paraplegia was MBP-specific, as irrelevant bovine serum albumin with the same protocol could not induce it. The i.p. restimulation was requisite and needed the MBP in FCA, as MBP in PBS was ineffective. Histopathological observation manifested cellular infiltration by leucocytes in perivascular spaces and cerebral cortex. Neutrophils were prominent at 12 h after i.c. injection, then were replaced by mononuclear cells 24 h later. There were dynamic changes in cell number and immunophenotype of VLA-4+ expression in cervical lymph node cells after i.c. injection. The cells derived from cervical lymph nodes had higher MBP-stimulated proliferation than that of distal lymph nodes. This additional i.p. and i.c. stimulation provides a new manipulation to study brain inflammation.

Animals↗
PubMed1994

Protein quantification and electrophoresis in aqueous humor of pseudoexfoliation eyes.

PURPOSE: Pseudoexfoliation (PSX) eyes frequently show clinical signs of blood-aqueous barrier impairment. To analyze these alterations, the authors examined aqueous humor of human eyes with and without PSX. METHODS: After aqueous humor samples had been obtained during cataract or filtering glaucoma surgery, a modified Pierce-bicin choninic acid assay was used to quantify total aqueous protein concentration in 27 PSX eyes and 37 eyes without clinical signs of PSX (12 cataract eyes and 25 eyes with primary open-angle glaucoma). In addition, aqueous protein composition was analyzed by sodium dodecylsulfate polyacrylamide gel electrophoresis, silver staining, and laser densitometry in 27 PSX eyes and 59 eyes without PSX. RESULTS: Aqueous protein concentration was significantly higher in PSX (mean 0.42 +/- 0.16 mg/ml) than in normal cataract eyes (0.22 +/- 0.08 mg/ml, P < 0.0001) and in eyes with open-angle glaucoma (0.26 +/- 0.09 mg/ml, P < 0.0001, Wilcoxon-Mann-Whitney test). Electrophoresis revealed a characteristic increase of a 12.5-kDa band in 15 of 27 PSX eyes but in only 1 of 59 eyes without PSX (P < 0.00001, chi-square test). CONCLUSIONS: These results substantiate increased aqueous protein concentration and aqueous barrier impairment in PSX. The additional finding of an increased 12.5-kDa band in 56% of PSX eyes may be related to the pathogenesis of PSX in the anterior ocular segment.

Aged↗
PubMed1977

Serum-stimulated phosphate uptake and initiation of fibroblast proliferation.

Previous studies have shown that initiation of proliferation of density-inhibited fibroblasts by fresh serum is accompanied by a rapid increase in phosphate uptake. This increase might be a key event in the initiation of DNA synthesis. The present studies examined this possibility. Mouse 3T3, secondary chick embryo, or human diploid foreskin cultures were grown to quiescence in medium containing varying levels of serum. When proliferation of the cultures was initiated by addition of fresh serum, the changes in phosphate uptake were inversely related to the final increases in cell number. Additional experiments showed that the change in phosphate uptake following serum addition was determined by the level of phosphate uptake prior to serum addition. Addition of dexamethasone to quiescent 3T3 cultures caused them to proliferate but did not increase phosphate uptake. Similarly, trypsin or insulin stimulated proliferation of quiescent secondary chick embryo cultures, but caused little or no change in phosphate uptake. Quiescent 3T3 cultures switched to medium containing fresh serum and reduced levels of phosphate showed a decrease in both phosphate uptake and intracellular phosphate pool size. Cell proliferation in these cultures, however, was stimulated to the same degree as cultures switched to medium containing fresh serum and the normal amount of phosphate. In addition, quiescent secondary chick embryo cultures switched to medium containing fresh serum and no phosphate showed a decrease in the intracellular phosphate pool size. Thymidine incorporation and final cell number in these cultures, however, was stimulated to the same or higher degree than in cultures switched to medium containing fresh serum and the normal amount of phosphate. These results demonstrate that the rapid increase in phosphate uptake following addition of fresh serum to quiescent fibroblasts is not a necessary event for the initiation of proliferation.

Animals↗