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F Peng

Publications and source records attributed to F Peng.

31 records · Page 2Linked to original sources
PubMed1996

Bayesian inference for hierarchical mixtures-of-experts with applications to regression and classification.

This paper studies the problems of inference and prediction in a class of models known as hierarchical mixtures-of-experts (HME). The statistical model underlying an HME is a mixture model in which both the mixture coefficients and the mixture components are generalized linear models. Bayesian inference regarding an HME's parameters is presented in the contexts of regression and classification using Markov chain Monte Carlo methods. A benefit of this Bayesian approach is the ability to obtain a sample from the posterior distribution of any functional of the parameters of the given model. In this way, more information is obtained than provided by a point estimate. The methods are illustrated on a nonlinear regression problem and on a breast cancer classification problem. The results indicate that the HME showed good prediction performance, and also gave the additional benefit of providing for the opportunity to assess the degree of certainty of the model in its predictions.

Algorithms↗
PubMed1992

Isolation and characterization of cDNAs from BamHI-H gene family RNAs associated with the tumorigenicity of Marek's disease virus.

It has been reported that loss of the tumorigenic potential of attenuated Marek's disease virus (MDV) is strongly associated with amplification of the 132-bp repeat sequences found within the BamHI-D and BamHI-H fragments contained within the long terminal repeat and the long internal repeat, respectively. The expansion of this region results in loss of transcripts that are 3.8, 3.0, and 1.8 kbp long that are produced by tumorigenic strains of MDV. This evidence suggests that production of one or more of these three RNAs is strongly associated with the tumorigenic potential of the virus. In this study, we have cloned and sequenced 1.69-, 1.5-, 1.9-, and 2.2-kbp cDNAs from the BamHI-H gene family RNAs associated with tumorigenicity. The 1.69- and 2.2-kbp cDNAs are derived from nonspliced transcripts, whereas the 1.5- and 1.9-kbp cDNAs are from single spliced mRNAs spanning the BamHI-H and BamHI-I2 fragments of MDV DNA. Sequence analysis has shown two potential open reading frames in each of the cDNAs. The putative 63-amino-acid protein encoded by the first open reading frame in the 1.69-kbp cDNA and a putative 75-amino-acid protein encoded by the first open reading frame in the 1.5-kbp cDNA showed limited homology with the mouse T-cell lymphoma oncogene and the fes/fps family of kinase-related transforming proteins.

Amino Acid Sequence↗
PubMed1982

Cholinergic projections from the basal forebrain of rat to the amygdala.

Cholinergic afferents to the amygdala from the basal forebrain were studied using di-isopropyl fluorophosphate-AChE histochemistry in combination with retrograde tracing using various fluorescent dyes. Cells sending their axons to the amygdala and staining intensely for AChE were located mainly in the nucleus of the substantia innominata. They also were found in the ventral part of the globus pallidus, the horizontal limb of the nucleus tractus diagonalis Broca, and the nucleus interstitialis ansae lenticularis. A correspondence was established between these cells and cells staining for choline acetyltransferase by immunohistochemistry in both distribution and morphology. Non-cholinergic neurons which send their axons to the amygdala also were found in the substantia innominata complex.

Acetylcholinesterase↗
PubMed1980

Choline acetyltransferase-containing neurons in rodent brain demonstrated by immunohistochemistry.

Choline acetyltransferase was demonstrated in neuronal structures of the rodent central nervous system by immunohistochemistry through the application of Fab fragments obtained from monospecific antiserums to human choline acetyltransferase. The specificity of the antiserum for the enzyme was confirmed by the staining of both the ventral horn motor neurons in the rat spinal cord and the neuromuscular junction of the guinea pig diaphragm. Enzyme-containing cell bodies were observed in frontal sections of rat and guinea pig brain in the neostriatum, accumbens, nucleus of the diagonal band, medial septum, and olfactory tubercle. Positively staining fibers and probable nerve terminals were also found in the olfactory tubercle field and other areas of the basal forebrain. The results provide information on the distribution of the cholinergic systems in the rostral forebrain of the rodent.

Animals↗
PubMedDate not supplied

Molecular cloning and sequence analysis of cDNAs encoding a beta-toxin-like peptide and two MkTx I homologues from scorpion Buthus martensii Karsch.

Three full-length cDNAs, one encoding the precursor of a beta-toxin-like peptide (named BmKBT) and the other two encoding those of (MkTx I) homologues (named MkTx II and MkTx III, respectively), were isolated from a venom gland cDNA library of the Chinese scorpion Buthus martensii Karsch, by screening with a cDNA fragment generated by PCR. The encoded precursor of BmKBT contained 83 amino acid residues including a signal peptide of 19 residues, a mature peptide of 63 residues and an extra basic residue (Lys) which have to be removed in the processing step. The deduced amino acid sequence of BmKBT showed 52% homology to that of beta-neurotoxin TsVII isolated from scorpion Tityus serrulatus. However, the positions of disulfide bridges have a little variation between the two peptides. The precursors of MkTx II and MkTx III both contained 85 amino acid residues including a signal peptide of 19 residues, a mature peptide of 64 residues and two extra residues (Gly-Arg) which have to be removed in the processing step, too. There was high sequence similarity (90%) between the two peptides. The sequences of mature MkTx II and MkTx III were highly homologous with MkTx I isolated from scorpion Buthus martensii Karsch, both showing 90% identities.

Amino Acid Sequence↗
PubMedDate not supplied

Molecular cloning and genomic organization of a K(+) channel toxin from the Chinese scorpion Buthus martensii Karsch.

A full-length cDNA encoding the precursor of a K(+) channel toxin (BmTX2) was first isolated from a venom-gland cDNA library of the Chinese scorpion Buthus martensii Karsch. The precursor is composed of a signal peptide of 21 residues and a mature toxin of 37 residues with three disulfide bridges. The genomic gene of BmTX2 was also cloned and sequenced. It consisted of two exons, disrupted by an intron of 81 bp inserted in the region encoding signal peptide.

Amino Acid Sequence↗
PubMedDate not supplied

Antagonism of NPY-induced feeding by pretreatment with cyclic AMP response element binding protein antisense oligonucleotide.

Although second messenger systems subserving neuropeptide Y (NPY)-mediated behaviors have been identified for a variety of receptors in several tissues, downstream signaling events are not well known. The nuclear binding protein, cyclic AMP response element binding protein (CREB) appears to be a transcription factor that is activated following injection of NPY into rat hypothalamus. To allow determination of the functional nature of CREB mediation of NPY-induced feeding, injection cannulae were implanted into the perifornical hypothalamus of 18 rats. Treatment of seven rats with CREB antisense oligonucleotide (15 ug) significantly antagonized NPY feeding for up to one week after treatment, while similar injections of CREB sense oligonucleotide (15 ug) had no significant effect on NPY-induced feeding. Two weeks after the antisense oligonucleotide treatment, feeding was once again elicited by the injection of NPY. Hypothalamic CREB protein was also reduced significantly two days after the CREB antisense oligonucleotide treatment. These results suggest that activation of CREB, probably through phosphorylation, may be a necessary event for the signal transduction of NPY stimulation into feeding behavior.

Animals↗
PubMedDate not supplied

Bayesian analysis of ROC curves using Markov-chain Monte Carlo methods.

The authors introduce a Bayesian approach to generalized linear regression models for rating data observed in the evaluation of a diagnostic technology. Such models were previously studied using a non-Bayesian approach. In a Bayesian analysis, the difficulties inherent in an ordinal rating scale are circumvented by using data-augmentation techniques. Posterior distributions for the regression parameters- and thereby for receiver operating characteristic (ROC) curve parameters and values, for the area under a ROC curve, differences between areas, etc.-may then be computed by Markov-chain Monte Carlo methods. Inferences are made in standard Bayesian ways. The methods are exemplified by a study of ultrasonography rating data for the detection of hepatic metastases in patients with colon or breast cancer (previously analyzed) and the results compared.

Bayes Theorem↗