Biomedical subjects

J Lin

Publications and source records attributed to J Lin.

At least 55 records · Page 3Linked to original sources

PubMed2001

BAG-1 is a novel cytoplasmic binding partner of the membrane form of heparin-binding EGF-like growth factor: a unique role for proHB-EGF in cell survival regulation.

Several cell functions related to growth and survival regulation have been attributed specifically to the membrane form of heparin-binding EGF-like growth factor (proHB-EGF), rather than to the diffusible, processed HB-EGF isoform. These findings suggest the existence of a functional binding partner specifically for the membrane form of the growth factor. In this study we have identified the prosurvival cochaperone, BAG-1, as a protein that interacts with the cytoplasmic tail domain of proHB-EGF. Interaction between BAG-1 and the 24-amino acid proHB-EGF cytoplasmic tail was initially identified in a yeast two-hybrid screen and was confirmed in mammalian cells. The proHB-EGF tail bound BAG-1 in an hsp70-independent manner and within a 97-amino acid segment that includes the ubiquitin homology domain in BAG-1 but does not include the hsp70 binding site. Effects of BAG-1 and proHB-EGF co-expression were demonstrated in cell adhesion and cell survival assays and in quantitative assays of regulated secretion of soluble HB-EGF. Because the BAG-1 binding site is not present on the mature, diffusible form of the growth factor, these findings suggest a new mechanism by which proHB-EGF, in isolation from the diffusible form, can mediate cell signaling events. In addition, because effects of BAG-1 on regulated secretion of soluble HB-EGF were also identified, this interaction has the potential to alter the signaling capabilities of both the membrane-anchored and the diffusible forms of the growth factor.

Animals↗

PubMed2001

Removal of styrene vapor from waste gases by a trickle-bed air biofilter.

The trickle-bed air biofilter (TBAB) performance for the removal of high-strength styrene was evaluated under different gas flow rates and influent concentrations. Under pseudo-steady-state conditions, the elimination capacity increased but the removal efficiency decreased with the increase of styrene loading. More than 90 and 80% removal efficiencies were achieved for influent styrene loadings below 32 and 55g/m(3)/h, respectively. The TBAB appears to be an effective treatment process for controlling high-strength styrene emission under low-to-medium loading conditions, and the effectiveness could be maintained over 140 days of laboratory operation.

Air Movements↗

PubMed2001

PartsList: a web-based system for dynamically ranking protein folds based on disparate attributes, including whole-genome expression and interaction information.

As the number of protein folds is quite limited, a mode of analysis that will be increasingly common in the future, especially with the advent of structural genomics, is to survey and re-survey the finite parts list of folds from an expanding number of perspectives. We have developed a new resource, called PartsList, that lets one dynamically perform these comparative fold surveys. It is available on the web at http://bioinfo.mbb.yale.edu/partslist and http://www.partslist.org. The system is based on the existing fold classifications and functions as a form of companion annotation for them, providing 'global views' of many already completed fold surveys. The central idea in the system is that of comparison through ranking; PartsList will rank the approximately 420 folds based on more than 180 attributes. These include: (i) occurrence in a number of completely sequenced genomes (e.g. it will show the most common folds in the worm versus yeast); (ii) occurrence in the structure databank (e.g. most common folds in the PDB); (iii) both absolute and relative gene expression information (e.g. most changing folds in expression over the cell cycle); (iv) protein-protein interactions, based on experimental data in yeast and comprehensive PDB surveys (e.g. most interacting fold); (v) sensitivity to inserted transposons; (vi) the number of functions associated with the fold (e.g. most multi-functional folds); (vii) amino acid composition (e.g. most Cys-rich folds); (viii) protein motions (e.g. most mobile folds); and (ix) the level of similarity based on a comprehensive set of structural alignments (e.g. most structurally variable folds). The integration of whole-genome expression and protein-protein interaction data with structural information is a particularly novel feature of our system. We provide three ways of visualizing the rankings: a profiler emphasizing the progression of high and low ranks across many pre-selected attributes, a dynamic comparer for custom comparisons and a numerical rankings correlator. These allow one to directly compare very different attributes of a fold (e.g. expression level, genome occurrence and maximum motion) in the uniform numerical format of ranks. This uniform framework, in turn, highlights the way that the frequency of many of the attributes falls off with approximate power-law behavior (i.e. according to V(-b), for attribute value V and constant exponent b), with a few folds having large values and most having small values.

Cysteine↗

PubMed2001

Cdk6-cyclin D3 complex evades inhibition by inhibitor proteins and uniquely controls cell's proliferation competence.

Mammalian cells require a cyclin D-dependent kinase for the cell cycle start, yet many mesenchymal cells express three seemingly redundant D cyclins and similarly, seemingly redundant Cdk4 and Cdk6 as their kinase partners. We have found that the Cdk6-cyclin D3 complex is unique among the D cyclin and kinase combinations in the ability to promote the cell cycle start. In an anchorage-minus G(1)-arrested rat fibroblast, only Cdk6-D3 retains kinase activity due mainly to its ability to evade inhibition by p27(KIP1) and p21(CIP1) with a resemblance to viral cyclin-bound Cdk6. Rodent fibroblasts engineered to overexpress both Cdk6 and cyclin D3 highly resist serum starvation- or cell-cell contact-imposed G(1)-arrest. In BALB/c 3T3 cells, D3 is constitutively expressed, but Cdk6 is markedly induced with concomitant activation upon stimulation with a growth-promoting factor. These results suggest a role for the Cdk6-D3 complex in regulating cell's proliferation ability in response to external stimuli.

3T3 Cells↗

PubMed2001

Novel 3',5'-cyclic nucleotide analogue: adenosine 3',5'-cyclic boranomonophosphate.

A general procedure for the first synthesis of a 3',5'-cyclic boranomonophosphate was established. Specifically, adenosine 3',5'-cyclic boranomonophosphosphate (cyclic AMPB, 4c), a P-borane (BH(3)) analogue of adenosine 3',5'-cyclic monophosphate (cAMP), was synthesized via a phosphite approach in good yield. The method is also applicable for syntheses of natural cAMP and its phosphorothioate analogue. The two diasteromers of cyclic AMPB 4c were separated, and their chemical structures were established via spectroscopic methods.

Boron Compounds↗

PubMed2001

Trimethylolpropane phosphate induces epileptiform discharges in the CA1 region of the rat hippocampus.

The actions of trimethylolpropane phosphate (TMPP), an ethyl bicyclophosphate convulsant produced during the partial pyrolysis of some phosphate ester-based lubricants, were tested on CA1 neurons of rat hippocampal slices using intracellular recording techniques. Bath application of TMPP (0.1-100 microM) induced spontaneous paroxysmal depolarizing shifts and the associated spontaneous epileptiform bursts followed by after-hyperpolarizations in 63% of neurons tested. The TMPP-induced epileptiform bursts were blocked by muscimol, a gamma-aminobutyric acid A (GABA(A)) receptor agonist, diazepam (DZP), a GABA(A)-benzodiazepine ionophore complex agonist, or baclofen, a GABA(B) receptor agonist. While bath application of muscimol, DZP, or baclofen suppressed spontaneous activity in CA1 neurons not previously exposed to TMPP, subsequent application of TMPP (10 microM) reversed the actions of muscimol and diazepam, but not baclofen. TMPP (0.1-100 microM) also induced membrane hyperpolarization associated with an increase in peak input resistance and inward rectification in 33% of neurons tested or membrane depolarization associated with an increase in input resistance in 17% of neurons tested. In summary, TMPP induced epileptiform activities in hippocampal CA1 neurons. The epileptogenic effects of TMPP are consistent with its interaction with GABA(A)-benzodiazepine receptors.

Action Potentials↗

PubMed2001

Correlation of low-barrier hydrogen bonding and oxyanion binding in transition state analogue complexes of chymotrypsin.

The structures of the hemiketal adducts of Ser 195 in chymotrypsin with N-acetyl-L-leucyl-L-phenylalanyl trifluoromethyl ketone (AcLF-CF3) and N-acetyl-L-phenylalanyl trifluoromethyl ketone (AcF-CF3) were determined to 1.4-1.5 A by X-ray crystallography. The structures confirm those previously reported at 1.8-2.1 A [Brady, K., Wei, A., Ringe, D., and Abeles, R. H. (1990) Biochemistry 29, 7600-7607]. The 2.6 A spacings between Ndelta1 of His 57 and Odelta1 of Asp 102 are confirmed at 1.3 A resolution, consistent with the low-barrier hydrogen bonds (LBHBs) between His 57 and Asp 102 postulated on the basis of spectroscopy and deuterium isotope effects. The X-ray crystal structure of the hemiacetal adduct between Ser 195 of chymotrypsin and N-acetyl-L-leucyl-L-phenylalanal (AcLF-CHO) has also been determined at pH 7.0. The structure is similar to the AcLF-CF3 adduct, except for the presence of two epimeric adducts in the R- and S-configurations at the hemiacetal carbons. In the (R)-hemiacetal, oxygen is hydrogen bonded to His 57, not the oxyanion site. On the basis of the downfield 1H NMR spectrum in solution, His 57 is not protonated at Nepsilon2, and there is no LBHB at pH >7.0. Because addition of AcLF-CHO to chymotrypsin neither releases nor takes up a proton from solution, it is concluded that the hemiacetal oxygen of the chymotrypsin-AcLF-CHO complex is a hydroxyl group and not attracted to the oxyanion site. The protonation states of the hemiacetal and His 57 are explained by the high basicity of the hemiacetal oxygen (pK(a) > 13.5) relative to that of His 57. The 13C NMR signal for the adduct of AcLF-13CHO with chymotrypsin is consistent with a neutral hemiacetal between pH 7 and 13. At pH <7.0, His 57 in the AcLF-CHO-hemiacetal complex of chymotrypsin undergoes protonation at Nepsilon2 of His 57, leading to a transition of the 15.1 ppm downfield signal to 17.8 ppm. The pK(a)s in the active sites of the AcLF-CF3 and AcLF-CHO adducts suggest an energy barrier of 6-7 kcal x mol(-1) against ionizations that change the electrostatic charge at the active site. However, ionizations of neutral His 57 in the AcLF-CHO-chymotrypsin adduct, or in free chymotrypsin, proceed with no apparent barrier. Protonation of His 57 is accompanied by LBHB formation, suggesting that stabilization by the LBHB overcomes the barrier to ionization. On the basis of the hydration constant for AcLF-13CHO and its inhibition constant, its K(d) is 16 microM, 8000-fold larger than the comparable value for AcLF-CF3.

Acetals↗

PubMed2001

Genome sequence of enterohaemorrhagic Escherichia coli O157:H7.

The bacterium Escherichia coli O157:H7 is a worldwide threat to public health and has been implicated in many outbreaks of haemorrhagic colitis, some of which included fatalities caused by haemolytic uraemic syndrome. Close to 75,000 cases of O157:H7 infection are now estimated to occur annually in the United States. The severity of disease, the lack of effective treatment and the potential for large-scale outbreaks from contaminated food supplies have propelled intensive research on the pathogenesis and detection of E. coli O157:H7 (ref. 4). Here we have sequenced the genome of E. coli O157:H7 to identify candidate genes responsible for pathogenesis, to develop better methods of strain detection and to advance our understanding of the evolution of E. coli, through comparison with the genome of the non-pathogenic laboratory strain E. coli K-12 (ref. 5). We find that lateral gene transfer is far more extensive than previously anticipated. In fact, 1,387 new genes encoded in strain-specific clusters of diverse sizes were found in O157:H7. These include candidate virulence factors, alternative metabolic capacities, several prophages and other new functions--all of which could be targets for surveillance.

Base Sequence↗

PubMed2001

Secular trend in tooth size in urban Chinese assessed from two-generation family data.

Environmental improvements can lead to greater size of skeletodental structures as the population comes closer to expressing its genetic growth potential. Such secular trends have been documented in many human settings, especially for increased stature and faster tempos of growth. The present study is based on 185 same-sex parent-offspring pairs of data for maximum buccolingual crown diameters of the permanent teeth from a cohort in Beijing, China, where parents experienced much of their development during and after World War II with the deprivations of the changing regime. Their offspring enjoyed the relative stability of the established Communist system, where nutrition and stability were much improved. There were significant increases in buccolingual diameters of the premolars and molars in the offspring. Increase for premolars and molars was about 1%, but larger in females than males (1.6% vs. 0.5%). Opposite changes occurred in the incisors and canines (i.e., larger parental dimensions), but we contend that these are an age-related artifact brought on by greater passive eruption of older individuals' teeth that exposes a broader portion of the crown at the gingival margin. The secular trend in crown size coincides with other research in contemporary China, disclosing increases in body size and faster tempos of growth as health and nutrition continue to improve.

Adolescent↗

PubMed2001

A kinship analysis of asthma among the Hutterites.

A formal kinship analysis of asthma in a large Hutterite kindred indicates that cases are significantly more related to one another than are age matched controls. The higher kinship coefficient is shown to be due to an increased probability of the condensed identity state delta 8 which, in turn, is shown to be due to an increased probability of detailed identity state delta 10.

Adult↗

PubMed2001

Exploiting linkage disequilibrium in population isolates.

A comparison of haplotype frequencies between unrelated cases and controls from population isolates identifies a strong signal for the presence/absence of the discrete phenotype in an interval on chromosome 6 bounded by markers 34 and 35. We define a dissimilarity index, D, which is sensitive to differences in allele distributions and differences in the patterns of linkage disequilibrium between cases and controls. We describe two statistical methods to utilize D: a method appropriate for a single moderately sized sample and a sequential approach appropriate for multiple small independent samples.

Alleles↗

PubMed2001

GM3 as a novel growth regulator for human gliomas.

The simple ganglioside GM3 inhibits proliferation and induces apoptosis in proliferating immature rodent CNS cells. To determine whether GM3 influenced the expansion of human neural tumors the effects of GM3 treatment on primary human brain tumors were assayed. Here we demonstrate that GM3 treatment dramatically reduces cell numbers in primary cultures of high-grade human glioblastoma multiforme (GBM) tumors and the rat 9L cell gliosarcoma cell line. By contrast, GM3 treatment had little effect on cell number in cultures of normal human brain. A single injection of GM3 3 days after intracranial implantation of 9L tumor cells in a murine xenograft model system resulted in a significant increase in the symptom-free survival period of host animals. The effects of GM3 were not restricted to GBMs and 9L cells. Cultures of high-grade ependymomas, mixed gliomas, astrocytomas, oligodendrogliomas, and gangliogliomas were all susceptible to GM3 treatment. These results suggest that GM3 may have considerable value as a selectively toxic chemotherapeutic agent for human high-grade gliomas.

Animals↗

PubMed2001

Near-Infrared Spectrum of the A(2)Pi(i)-X(2)Sigma(+) (2,0) Band of CN Studied by Concentration Modulation Laser Spectroscopy.

The rotational structure of (2,0) vibrational band of A(2)Pi(i)-X(2)Sigma(+) transition of CN has been studied by concentration-modulation laser spectroscopy using a Ti:sapphire laser. The CN radical was produced in the ac glow discharge of acetonitrile with helium as the carrier gas. All 12 branches including four new branches have been observed and measured with an absolute accuracy of 0.007 cm(-1) in the region 12 450-12 750 cm(-1). Analysis of the spectra has led to improved molecular parameters of the A(2)Pi(i) (v' = 2) state. Copyright 2001 Academic Press.

Journal Article↗

PubMed2001

The clinical relevance of molecular staging for melanoma.

The presence of metastatic disease in the regional nodal basin is the most important prognostic indicator for patients with malignant melanoma. The metastatic status of the sentinel lymph node (SLN), defined as the first node in the basin to drain a primary tumor, has been shown to represent that of the entire basin. Since routine histologic examination of lymph nodes often underestimates the presence of micrometastatic disease, a more sensitive assay for detecting tumor cells is needed. We have previously shown that a molecular assay based on the reverse transcriptase polymerase chain reaction (RT-PCR) was able to define a population of patients at higher risk for both recurrence and death, compared with routine H&E histology. Recently, we have compared "molecular staging" of patients by RT-PCR with conventional S-100 immunohistochemistry (IHC) staining of the SLNs. In these studies, SLN specimens were bivaled, and half of each specimen was examined by routine histology, including both H&E and S-100 IHC. The other half of each specimen was analyzed by a nested RT-PCR assay. H&E histology alone detected metastatic disease in 36 of 233 (16%) patients tested. Serial sectioning and IHC detected micrometastatic disease in another 16 patients, thus increasing the proportion of patients with nodal disease to 22%. RT-PCR detected micrometastatic disease in 114 of 181 patients who were negative by conventional methods, further increasing the proportion of patients with evidence of nodal disease to 70% overall. The clinical significance of these findings is still uncertain. The value of additional therapy (including elective lymph node dissection and interferon therapy) for patients who are positive only by the molecular method is currently being investigated by the national multi-center Sunbelt Melanoma Trial.

Biomarkers, Tumor↗

PubMed2001

Anti-viral activity of hairpin ribozyme directed against HBV core region in vitro.

To study the preparation and cleavage of hairpin ribozyme (HpRz) directed against the transcript of HBV core region in vitro, HRz gene designed by computer targeting the transcript of HBV core gene was cloned into the vector p1.5 between 5'-cis-Rz and 3'-cis-Rz. 32P-labeled HpRz transcript proved whether the vector fit for the preparation of hairpin ribozyme. 32P-labeled pKC transcript containing HBV core region as targets-RNA was transcribed by using T7 RNA polymerase and purified by PAGE. Cold HpRz transcript was incubated with 32P-labeled target-RNAs under different conditions and radioautographed after denaturing polyacrylamide gel electrophoresis. The results showed that HpRz had the ability of cleavage at 37 degrees C and 12 mmol/L MgCl2 and the design of ribozyme was correct. It is concluded that HpRz prepared in vitro possesses specific catalytic activity, indicating that it is possible for HpRz to intracellularly inhibit the replication of HBV. It may be developed into a nucleic acid drug in the treatment of hepatitis B in the future.

Antiviral Agents↗

PubMed2001

The cell specific temporal expression of nitric oxide synthase isoforms during achilles tendon healing.

OBJECTIVE AND DESIGN: We have previously shown that nitric oxide synthase (NOS) activity is upregulated following tendon injury, and that this activity is important to Achilles tendon healing. The aim of this study was to identify the cellular distribution of nitric oxide synthase isoforms during tendon healing. MATERIAL OR SUBJECTS: Surgical division of the right Achilles tendon was performed in eighty-five male Sprague-Dawley rats. Healing Achilles tendons were harvested at 4, 7, 14 and 21 days following the surgery. The un-injured left Achilles tendons were used as controls. Using RNase protection assays, in situ hybridization and immunohistochemistry, mRNA and protein of NOS isoforms were evaluated. RESULTS: Minimal NOS expression was found in un-injured tendon. A cell specific temporal pattern for the mRNA and protein for all three NOS isoforms was found following injury to the Achilles tendon. iNOS was maximal on day 4 in macrophages and fibroblasts. eNOS was maximal on day 4 in endothelial cells and fibroblasts. bNOS expression gradually increased up to day 21 and was found only in fibroblasts. CONCLUSIONS: These results suggest that all three nitric oxide synthase isoforms are expressed by fibroblasts in a coordinated temporal sequence during tendon healing. The sequential pattern of NOS expression in healing fibroblasts suggests that each NOS isoform may play a different role in the healing process and provides opportunities to modify tendon healing in the clinical setting.

Achilles Tendon↗

PubMed2001

Growth suppression of hamster flank organs by topical application of catechins, alizarin, curcumin, and myristoleic acid.

Hamster flank organ growth, as measured by an increase in the area of the pigmented macule, is androgen-dependent. When flank organs of a castrated hamster are treated topically with testosterone, the flank organ becomes larger and darker. Since this growth is known to be dependent on the intracellular active androgen, 5alpha-dihydrotestosterone (DHT), inhibitors of 5alpha-reductase which converts testosterone to DHT can inhibit the growth of the flank organ. Certain unsaturated aliphatic fatty acids, such as gamma-linolenic acid and myristoleic acid, as well as other natural compounds, including alizarin and curcumin, are 5alpha-reductase inhibitors and inhibited flank organ growth. Green tea catechins, including (-)-epicatechin-3-gallate, and (-)-epigallo-catechin-3-gallate (EGCG) are also 5alpha-reductase inhibitors and inhibited flank organ growth. However, (-)-epicatechin and (-)-epigallocatechin, which are not 5alpha-reductase inhibitors, also inhibited flank organ growth. EGCG also inhibited DHT-dependent growth of flank organs. These catechins, therefore, may act by a mechanism other than inhibition of 5alpha-reductase. The effect of EGCG and other compounds was localized at the site of application; they did not affect the growth of the contralateral flank organ in the same animal. Since these compounds do not appear to exhibit systemic effects, they may be potentially useful for treatment of androgen-dependent skin disorders.

Administration, Topical↗

PubMed2001

Quantification of key odorants formed by autoxidation of arachidonic acid using isotope dilution assay.

Six odor-active compounds generated by autoxidation of arachidonic acid (AA) were quantified by isotope dilution assay (IDA), i.e., hexanal (1), 1-octen-3-one (2), (E,Z)-2,4-decadienal (3), (E,E)-2,4-decadienal (4), trans-4,5-epoxy-(E)-2-decenal (5), and (E,Z,Z)-2,4,7-tridecatrienal (6). Compound 1 was the most abundant odorant with about 700 mg/100 g autoxidized AA, which corresponds to 2.2 mol% yield. Based on the odor activity values (ratio of concentration to odor threshold), odorants 3 (fatty) and 5 (metallic) showed the highest sensory contribution followed by 1 (green), 2 (mushroom-like), 6 (egg white-like), and 4 (fatty). For the first time, reliable quantitative results are reported for odorants 1-6 in autoxidized AA, in particular odorant 6, which is a characteristic compound found in autoxidized AA. Synthesis of deuterated 6, required for IDA, is described in detail. The formation of odorants 1-6 by autoxidation of AA is discussed with respect to the quantitative data.

Aldehydes↗