Biomedical subjects

P Huang

Publications and source records attributed to P Huang.

At least 109 records · Page 6Linked to original sources

PubMed1999

Use of a mixed-mode packing and voltage tuning for peptide mixture separation in pressurized capillary electrochromatography with an ion trap storage/reflectron time-of-flight mass spectrometer detector.

A mixed-mode (reversed-phase/anion-exchange) stationary phase has been used as the capillary column packing for investigation of the separation of peptide mixtures in pressurized capillary electrochromatography (pCEC). This stationary phase contains both octadecylsilanes and dialkylamines. The amine groups of the stationary phase determine the charge density on the surface of the packing and can produce a strong and constant electroosmotic flow (EOF) at low pH. A comparison was made in terms of the capability of separating tryptic digests between the mixed-mode phase and C18 reversed phase. In addition, the constant EOF enabled the tuning of the retention and the selectivity of the separation by adjusting the mobile phase pH from 2 to 5. Furthermore, the magnitude and the polarity of the electric voltage were demonstrated to greatly influence the elution profiles of the peptides in pCEC. An ion trap storage/reflectron time-of-flight mass spectrometer was used as an on-line detector in these experiments due to its ability to provide rapid and accurate mass detection of the sample components eluting from the separation column.

Chromatography, Liquid↗

PubMed1999

Transforming growth factor alpha (TGF-alpha) expression in dysplastic oral leukoplakia: modulation by 13-cis retinoic acid.

BACKGROUND: Surrogate endpoint biomarkers (SEBs) are detectable molecular, cellular, and tissue changes that take place during tumorigenesis and can be modulated by a chemoprevention agent. METHOD: To identify candidate SEBs for invasive squamous cell carcinoma of the upper aerodigestive tract (SCC), we have studied the expression of transforming growth factor-alpha (TGF-alpha) and epidermal growth factor receptor (EGFr) in sequential biopsy specimens of dysplastic oral leukoplakia and adjacent normal-appearing mucosa. Biopsies were taken from patients before, during, and after treatment with 13-cis retinoic acid, a vitamin A derivative. Immunohistochemistry was performed using the Biogenex Super Sensitive Biotin-Streptavidin horseradish peroxidase detection system. RESULTS: The pretreatment expression of TGF-alpha and EGFr in dysplastic oral leukoplakia was increased when compared with their expression in adjacent normal-appearing mucosa (p = 0.001 and p = 0.01, respectively). Eleven of 14 patients enrolled in the study (78.6%) completed 3 months of treatment with 13-cis retinoic acid (1. 0 mg/kg/day). TGF-alpha expression in dysplastic oral leukoplakia, but not in adjacent normal-appearing mucosa, decreased during treatment (p < 0.05). CONCLUSIONS: TGF-alpha is a candidate SEB for future SCC chemoprevention trials.

Antineoplastic Agents↗

PubMed1999

Existence of multiple novel Gs alpha splice variants in acute leukemia patients.

The alpha subunit of the stimulatory G protein, Gs alpha, is involved in stimulation of the adenylate cyclase pathway of signal transduction. In this study, we investigated the status of the Gs alpha gene in 29 acute leukemia patients and identified three novel splice variants (designated Gs alpha L-1, Gs alpha L-2, and Gs alpha L-3), possibly derived from aberrant splicing. All of the splice variants have in-frame deletions, removing the functional domain responsible for GTPase activity of Gs alpha, and would encode truncated proteins of 160(Gs alpha L-1), 90(Gs alpha L-2) and 70(Gs alpha L-3) amino acids, respectively. The data suggest that these novel products may be implicated in an as-yet-unidentified signal transduction pathway in hematopoietic cells.

Acute Disease↗

PubMed1999

In situ identification of normal visceral tissues using contact telescopic microscopy.

OBJECTIVES: To improve the intraoperative anatomic identification of normal tissues during surgery using histologic-like criteria STUDY DESIGN: A contact telescope was used to identify normal visceral tissues in an animal model using pigs and dogs during routine human surgical procedures. METHODS: Tissues that could be identified grossly were stained topically with methylene blue and then examined with the contact telescope. The histologic appearance of these tissues with the contact telescope was correlated with routine histologic hematoxylin and eosin stains obtained after such tissues were excised. RESULTS: Normal tissues, such as fat, blood vessels, muscle, and parathyroid tissue, can be identified reliably in animals and humans. The contact telescope appears to be able to differentiate between a variety of visceral tissues in the neck and may become useful for practical differentiation between tissues during surgery.

Animals↗

PubMed1999

Polypyrimidine tract-binding protein binds to the leader RNA of mouse hepatitis virus and serves as a regulator of viral transcription.

A cellular protein, previously described as p55, binds specifically to the plus strand of the mouse hepatitis virus (MHV) leader RNA. We have purified this protein and determined by partial peptide sequencing that it is polypyrimidine tract-binding protein (PTB) (also known as heterogeneous nuclear ribonucleoprotein [hnRNP] I), a nuclear protein which shuttles between the nucleus and cytoplasm. PTB plays a role in the regulation of alternative splicing of pre-mRNAs in normal cells and translation of several viruses. By UV cross-linking and immunoprecipitation studies using cellular extracts and a recombinant PTB, we have established that PTB binds to the MHV plus-strand leader RNA specifically. Deletion analyses of the leader RNA mapped the PTB-binding site to the UCUAA pentanucleotide repeats. Using a defective-interfering RNA reporter system, we have further shown that the PTB-binding site in the leader RNA is critical for MHV RNA synthesis. This and our previous study (H.-P. Li, X. Zhang, R. Duncan, L. Comai, and M. M. C. Lai, Proc. Natl. Acad. Sci. USA 94:9544-9549, 1997) combined thus show that two cellular hnRNPs, PTB and hnRNP A1, bind to the transcription-regulatory sequences of MHV RNA and may participate in its transcription.

5' Untranslated Regions↗

PubMed1999

Polypyrimidine tract-binding protein binds to the complementary strand of the mouse hepatitis virus 3' untranslated region, thereby altering RNA conformation.

Mouse hepatitis virus (MHV) RNA transcription is regulated mainly by the leader and intergenic (IG) sequences. However, a previous study has shown that the 3' untranslated region (3'-UTR) of the viral genome is also required for subgenomic mRNA transcription; deletion of nucleotides (nt) 270 to 305 from the 3'-UTR completely abolished subgenomic mRNA transcription without affecting minus-strand RNA synthesis (Y.-J. Lin, X. Zhang, R.-C. Wu, and M. M. C. Lai, J. Virol. 70:7236-7240, 1996), suggesting that the 3'-UTR affects positive-strand RNA synthesis. In this study, by UV-cross-linking experiments, we found that several cellular proteins bind specifically to the minus-strand 350 nucleotides complementary to the 3'-UTR of the viral genome. The major protein species, p55, was identified as the polypyrimidine tract-binding protein (PTB, also known as heterogeneous nuclear RNP I) by immunoprecipitation of the UV-cross-linked protein and binding of the recombinant PTB. A strong PTB-binding site was mapped to nt 53 to 149, and another weak binding site was mapped to nt 270 to 307 on the complementary strand of the 3'-UTR (c3'-UTR). Partial substitutions of the PTB-binding nucleotides reduced PTB binding in vitro. Furthermore, defective interfering (DI) RNAs harboring these mutations showed a substantially reduced ability to synthesize subgenomic mRNA. By enzymatic and chemical probing, we found that PTB binding to nt 53 to 149 caused a conformational change in the neighboring RNA region. Partial deletions within the PTB-binding sequence completely abolished the PTB-induced conformational change in the mutant RNA even when the RNA retained partial PTB-binding activity. Correspondingly, the MHV DI RNAs containing these deletions completely lost their ability to transcribe mRNAs. Thus, the conformational change in the c3'-UTR caused by PTB binding may play a role in mRNA transcription.

3' Untranslated Regions↗

PubMed1999

Cytokine analysis in multiple sclerosis by competitive RT - PCR: A decreased expression of IL-10 and an increased expression of TNF-alpha in chronic progression.

Multiple sclerosis (MS) is an inflammatory, demyelinating disease that is specific to the central nervous system. Cytokines are thought to be key mediators of the autoimmune attack against central nervous system myelin in MS. To investigate the involvement of cytokines in MS, the mRNA levels of interferon gamma (IFN-gamma), tumor necrosis factor alpha (TNF-alpha), interleukin-4 (IL-4) and interleukin-10 (IL-10) in peripheral blood mononuclear cells without stimulation in vitro were quantified by a competitive reverse transcription polymerase chain reaction technique. The level of IL-10 specific mRNA was significantly decreased in 47 MS patients compared with 42 healthy controls (P<0.0001). TNF-alpha was significantly increased in MS patients compared with healthy controls (P=0.014), especially in the patients with chronic progressive MS (P=0.0003). Thus we conclude that there are significant in vivo alterations in cytokine gene expression in the periphery in MS.

Adult↗

PubMed1999

Prevalence and treatment of Pediculus capitis infestation among aboriginal school children in northern Taiwan.

In the present study, pediculosis was investigated among a total of 2,725 children from 35 primary schools in Hsiulin District of Hualien County, Jenai District of Nantou County, Wulai District of Taipei County, Chienshih District of Hsinchu County, Fushing District of Taoyuan County, and Nanao District of Ilan County. The overall infestation rate was 12.8%. The rates by districts were 19.7%, 17.3%, 16.7%, 15.1%, 7.9%, and 3.0%, respectively. The pediculicides including Nix (permethrin 1%) 56 gm/tube, Para aerosol (bioallethrin 0.66%) 90 gm/tube, and Perioderm (malathion 1%) cream shampoo 40 gm/tube were used to treat the head louse infestation in 83, 91, and 103 children; the cure rates were 97.3%, 94.1%, and 93.4%, respectively. No significant differences were found in these rates. The reactions were slight and transitory. A total of 636 lice was collected from the hair using fine-toothed combs before treatment and from the used towels after treatment of children in Wulai, Chienshih, Hsiulin, and Jenai Districts. Each child was found infested with a mean of 7.7 lice. The mean intensity of infestation was highest in Jenai (9.3) and Chienshih (8.7) came next. Wulai (3.7) and Hsiulin (3.6) had lower intensities.

Animals↗

PubMed1999

Chart documentation of clinical preventive services at 9 Texas clinics.

Documentation of clinical preventive services at 9 Texas family practice residency programs, community health centers, and public health regional clinics was examined. Assessment of 11 risks, counseling on those risks, and timeliness of 8 screening tests and immunizations were abstracted. Documentation of clinicians' risk assessment focused on tobacco use (56.4%), alcohol/drug abuse (45.8%), and excess weight (21.6%). Counseling was documented most often for nutrition (20.5%), family planning (11.6%), and physical activity (10.3%). Of the sites studied, public health regional clinics had the highest documentation of assessment and counseling. Community health centers were most up-to-date for diabetes and cholesterol screening. Family practice residencies documented the highest rate of counseling for obesity risk. Clinicians do not document risk assessment, counseling, or up-to-date screening tests and immunizations for most of their adult patients. Texas practitioners may need support or assistance to provide universal access to clinical preventive services.

Adult↗

PubMed1999

Construction of La-tPA vector and expression in the mammary gland of transgenic mice.

Expression vectors of long acting human tissue plasminogen activator (La-tPa) in the mammary gland was constructed using the promoters of sheep beta-lactoglobulin gene (BLG, 5 kb) containing the first and the second introns obtained by PCR. Transgenic mice were established by microinjection. 540 fertilized eggs were injected and 6 transgenic mice were screened out from the offspring by PCR and Southern Blot analysis. The foreign gene integrating rate was 32%. The expression of La-tPA in mammary glands of transgenic mice was confirmed by milk assay and Northern blot analysis. Expression level of La-tPA reached 6 ug/ml in milk of transgenic mice.

Animals↗

PubMed1999

[Analysis on the treatment of 1,020 patients with immunologic infertility].

OBJECTIVE: To investigate the treatment for immunologic infertility. METHODS: Serum antisperm antibody, anti-ovarian antibody, anti-endometrial antibody and anti-hCG antibody in 1,020 female patients with primary or secondary infertility were tested. Patients were treated with dexamethasone, vitamin E and vitamin C for 3 cycles consecutively as one course. RESULTS: The detective rates of the above antibodies were 25.88%, 22.86%, 32.81% and 23.61% respectively. After one course of treatment, the disappearance rates of the antibodies mentioned were over 90%, and the average pregnancy rate was up to 30%. CONCLUSION: Corticosterocls may reduce or even eliminate the effects of the immune factors on infertility.

Adult↗

PubMed1999

[Histology and physiological function of dogs after extirpation of bronchi].

OBJECTIVE: To investigate the effect of extirpation of bronchi on histology and physiological function. METHODS: 21 dogs were divided in to two groups: control (3) and experimental (18). After bronchi extirpation one week, two weeks, one month, three months, six months, and twelve months, we used specimens to test the pulmonary surfactant (PS) and to observe the morphological changes. RESULTS: After the operation, the residual lung nearby the operative area had traumatic changes. Around the aforementioned area, the structure of lung was normal. Specially after six months, the lung returned to good status. We found that two weeks after operation, the contents of PS increased remarkably (P < 0.05). After one month the parameter returned to normal (P > 0.05). CONCLUSIONS: The residual lung after bronchi extirpation had ventilation and air-exchange functions. The lung function was preserved directly.

Animals↗

PubMed1999

[Retreatment after excimer laser photorefractive keratectomy].

OBJECTIVE: To evaluate the efficacy and safety of reoperation of residual myopia because of regression, undercorrection with or without coexisting severe corneal haze after excimer laser photorefractive keratectomy (PRK). METHODS: A VISK 20/20 excimer laser was used to treat myopia of -1.00 to -16.50 diopters (spherical equivalent) at corneal plane. 35 patients (51 eyes) who had residual myopia because of regression, undercorrection with or without coexisting severe corneal haze after initial PRK were retreated by using PRK and phototherapeutic keratectomy. RESULTS: At 12 months after retreatment, the rates of uncorrected visual acuity more than or equal to 10/20 or 20/20 were 82.6% and 39.1% respectively, 100.0% and 50.0% in myopia up to -6.00 D, 73.3% and 33.3% in myopia of -6.25 to -16.50 D respectively. 86.3% of eyes were within +/- 1.00 diopters of desired emmetropia. Corneal haze after retreatment was not greater than that observed after initial procedures. CONCLUSIONS: The residual myopia because of regression, undercorrection with or without severe corneal haze after initial PRK can be successfully retreated. Although the therapeutic result of retreatment of PRK is less successful than that of the initial procedure, retreatment appears to enhance it.

Adult↗

PubMed1999

[Expression of transforming growth factor alpha and its relationship with HBV infection in hepatocellular carcinomas].

OBJECTIVE: To assess the expression of TGF alpha in hepatocellular carcinoma and its relationship with HBV infection. METHODS: Using in situ hybridization and streptavidin-peroxidase immunohistochemistry to detect TGF alpha mRNA, TGF alpha protein and HBV DNA in 53 cases of HCC and 14 cases of controls. RESULTS: Positive rates of TGF alpha mRNA and TGF alpha protein in carcinoma tissue were 30.2% and 73.6% respectively, which were higher than in normal controls (P < 0.05). The expression of TGF alpha mRNA and TGF alpha protein was increased significantly in dysplastic liver cells (DLC) locating aside from the tumor tissue in comparing with those of non-dysplastic liver cells (NDLC) (P < 0.05). Positive rates of HBV DNA in carcinoma tissue and paratumorous liver tissue were 56.6% and 60.4% respectively, which were higher than in the normal controls (P < 0.001). Positive rate of HBV DNA in the nuclei of tumor tissues, tissue of the dysplastic areas and non-dysplastic areas was lowering down successively (P < 0.05). There was a significant relationship between expression of TGF alpha mRNA and TGF alpha protein in the carcinoma tissues and HBV DNA in the tumorous and its surrounding tissues respectively. CONCLUSIONS: Expression of TGF alpha in carcinoma tissues was closely associated with the existence of HBV DNA and TGF alpha may participate in the early stage of liver carcinogenesis. The increased expression of HBV DNA in nuclei may serve as an important morphology marker in distinguishing carcinoma from DLC and NDLC.

Carcinoma, Hepatocellular↗

PubMed1999

[Effects on the amount of total hemolytic complement levels(CH50) and immunoglobulin in serum induced by the implantation of biomaterials into rats].

Three kinds of biomaterials, PES, YP and SR, were implanted into the subcutaneous tissue of rats and stayed there for 7, 14, 30, 60 and 90 days. Then using the immunity assaying system (Beckman, ICS) and the standard method of measuring the value of total hemolytic complement levels (CH50), we determined the values of immunoglobulin and CH50 in serum of rats. The results showed the amounts of IgG and IgA of rats with the implanted YP and SR materials were significantly higher than those of the control groups, and their value of CH50 was significantly lower than that of the control group. There was no significant difference between the PES group and the control group.

Animals↗

PubMed1999

[The effects of fertilization on yield and root diameter of Codonopsis pilosula var. modesla].

Field trials were conducted using three factors regression design of quadratic orthogonal rotation. The result indicated that under the condition of cultivation, yield and average root diameter of Codonopsis Pilosula var. modesla (Nannf) L.T. Shen showed a positive correlation with N fertilizer application on high fertilization level; The effect of major three fertilizer on yield and average diameter of root was K > P > N. In the course of selective optimization yield which is higher than 3750 kg/hm2 (fresh weight) and average diameter of root which is more than 1.5 cm, the index of fertilizer application for N, P and K pure nutrient is 155 kg/hm2, 250 kg/hm2 (P2O5) and 60 kg/hm2 (K2O) respectively. The ration of N:P:K is 1:1.6:0.4.

Codonopsis↗

PubMed1999

[Study on cultivation of Dendrobium flexicaule by habitat imitation].

Dendrobium drug, a rare medicinal herb, reproduces differcut for growth environment to lead rare resources. By studying of cultivation for many many years in Fuliu mountain area, authors had found out the cultivated method simulating the habitat of wild Dendrobium flexicaule. The results could supply a basis for its development and utilization.

Conservation of Natural Resources↗

PubMed1998

Structure-activity studies related to ABT-594, a potent nonopioid analgesic agent: effect of pyridine and azetidine ring substitutions on nicotinic acetylcholine receptor binding affinity and analgesic activity in mice.

Analogs of A-98593 (1) and its enantiomer ABT-594 (2) with diverse substituents on the pyridine ring were prepared and tested for affinity to nicotinic acetylcholine receptor binding sites in rat brain and for analgesic activity in the mouse hot plate assay. Numerous types of modifications were consistent with high affinity for [3H]cytisine binding sites. By contrast, only selected modifications resulted in retention of analgesic potency in the same range as 1 and 2. Analogs of 2 with one or two methyl substituents at the 3-position of the azetidine ring also were prepared and found to be substantially less active in both assays.

Alkaloids↗