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Biomedical subjects

S C Hu

Publications and source records attributed to S C Hu.

At least 73 records · Page 4Linked to original sources
PubMed1991

Neurotoxic effects of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine in the substantia nigra and the locus coeruleus in BALB/c mice.

The purpose of the present study was to determine whether 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), administered systemically or as a local infusion, has a direct neurotoxic action upon dopamine (DA) neurons in the substantia nigra (SN) and norepinephrine (NE) neurons in the locus coeruleus (LC) in BALB/c mice. Results indicated that both acute and repeated MPTP infusions (2 micrograms/0.3 microliter per side) significantly impaired locomotor activity, decreased stereotyped behavior and caused a disturbed pattern of locomotion in mice. The biochemical changes parallel the behavioral changes. Repeated MPTP infusions to the SN decreased DA levels markedly in the SN and the striatum; chronic MPTP infusions to the LC reduced NE levels markedly in the LC and the hippocampus. Furthermore, repeated MPTP injections for 7 days (30 mg/kg, one injection per day) have resulted in a long-lasting effect on both the nigral-striatal and the coeruleus-hippocampal systems. DA levels in the SN and the striatum were decreased at 1, 3, 7 and 28 days after the last MPTP injection. Similarly, NE levels in the LC and the hippocampus were also reduced markedly at the same time intervals examined. Behaviorally, repeated MPTP treatment also produced long-lasting motor deficits in mice at all time intervals studied. Moreover, the LC appeared to be more sensitive than the SN to the neurotoxic effects of MPTP. Immunohistochemical results have similarly revealed that repeated MPTP treatment markedly decreased tyrosine hydroxylase-positive cells and fibers in the SN and the LC. It also markedly decreased DA-beta-hydroxylase-positive cells and fibers in the LC.(ABSTRACT TRUNCATED AT 250 WORDS)

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1991

[Synthesis and antimicrobial activity of 7-acylamido-3-1, 2, 3-triazol-1-ylmethyl) cephalosporins].

In order to develop oral cephalosporin exhibiting broad-spectrum activity, a series of cephalosporin derivatives (VIII1-12) bearing 1, 2, 3-triazolymethyl substituents on the C3 position were synthesized. 7-Phenylacetamido-3-methyl-3-cephem-4-carboxylic acid (I) was employed as starting material and converted to VIII by procedures of esterification and oxidation, bromination, azido-substitution, dipolarcycloaddition, deprotection, cleavage, and condensation. Minimum inhibitory concentration (MIC) values in vitro showed that VIII2-4.9-11 had a wide antibacterial spectrum against Gram positive and Gram negative bacteria and possessed high activities. Further biological evaluation and the study of oral absorption for the six compounds will be performed.

Cephalosporins↗
PubMed1990

[Survey of Enterobius vermicularis infection among school children in Tainan City].

A survey was conducted for enterobiasis, in six primary schools at Tainan city. The survey was conducted in 1986, involving 8,120 school children. The manner of testing, was two consecutive day, adhesive cellophane paper perianal swabs. The test resulted in general infection rate of 30.4%. The positive rates among those primary school children were significantly different (chi 2-test, p less than 0.001). The highest rate (40.3%), was in Shih-Men primary school and the lowest rate (18.7%) in Pao-Jeng primary school. Gender occurrence of enterobiasis was determined by making a statistic analysis between sex. We found significantly higher occurrence in males (32.4%) as opposed to females (28.3%) (chi 2-test, p less than 0.001). The infection rates were also significantly different by grade (chi 2-test, p less than 0.001). The highest rate was found in the lower grades (35.3%), the next in the middle grades (32.4%), and the lowest in the higher grades (21.6%). A questionnaire demonstrated that the family status and personal hygiene are the most important factors in transmission of pinworm infection, among the group surveyed. Moreover, the educational levels, occupations of parents, and facilities of bathrooms, (between both primary schools) were also found significantly associated with the transmission of pinworm infection. Therefore, we believe that these factors play a role in transmission of pinworm infection among school children.

Age Factors↗
PubMed1989

Immunomodulatory activity of staphylococcal enterotoxin-B. The induction of an I-J-restricted suppressor factor.

Staphylococcal enterotoxin-B (SEB), a common cause of food-borne intoxication, is a potent polyclonal T cell activator. Previous studies from this laboratory and others have shown that SEB has the capacity to nonspecifically inhibit antibody responses both in vivo and in vitro. We have shown that the inhibitory activity of SEB is mediated, in part, by the activation of a CD8+, CD4-, and CD5- suppressor cell population. The present studies show that the activity of the SEB-induced suppressor cell population is mediated by a soluble factor. This factor nonspecifically inhibits both primary and secondary in vitro antibody responses. Delayed addition analysis demonstrates that the factor must be present early in the ongoing antibody response to exhibit suppressive activity. Monoclonal anti-I-J antisera block the activity of the factor, and eluates (but not filtrates) collected from monoclonal anti-I-J immunoaffinity columns possess suppressive activity. Furthermore, the activity is restricted at the "I-J" gene locus, but is not restricted at the Igh locus. Finally, size-exclusion chromatographic analysis shows that the factor possesses an apparent Mr of 26 kDa. These studies suggest that SEB induces the production of a suppressive factor with properties similar to those exhibited by Ag-induced, and typically Ag-specific, suppressor factors.

Adjuvants, Immunologic↗
PubMed1989

A one-compartment single-pore model for extracorporeal hemoperfusion.

A one-compartment single-pore model is proposed for the dynamic analysis and performance evaluation of a hemoperfusion column under operation. Experimental data obtained from binary systems containing creatinine and uric acid may be well predicted by the theoretically computed curves. This theory offers a means for the preclinical evaluation of any prototype hemoperfusion column.

Adsorption↗
PubMed1989

Dynamics of intercellular communication and differentiation in a rapidly developing mammalian airway epithelium.

A considerable body of data suggests that gap junctions represent channels that facilitate intercellular communication, thereby modulating growth and development. However, direct quantitative evidence supporting such a structure/function relationship is limited. This study has identified a new model in the rapidly developing tracheal epithelium of infant ferrets wherein gap junction prevalence and intercellular transfer of a fluorescent, low molecular weight dye, epithelial cell incorporation of tritiated thymidine, and progressive ciliation of the epithelium have been characterized. This developmental pattern provides favorable conditions for the study of relationships between gap junctions, intercellular translocation of chemical signals, and cell growth and differentiation in a mammalian airway epithelium with a minimum of experimental intervention.

Animals↗
PubMed1989

A clinical evaluation of ultrasonography in the diagnosis of acute appendicitis.

Recently ultrasonography (US) has proven effective in the diagnosis of acute appendicitis. However, the impact of US on surgical decision-making in clinical practice remains unclear. From August 1986 to July 1987, 62 patients with clinical signs of acute appendicitis received US examinations after initial clinical evaluations. According to clinical pictures, they were classified into two groups: group I, clinically typical (Alvarado's score greater than or equal to 7) and group II, clinically dubious (Alvarado's score less than or equal to 6) cases. All group I patients (n = 34) had surgery. Group II patients (n = 28) received close in-hospital observation on an every 4-hour basis for less than 24 hours. However, surgery was performed if Alvarado's score increased up to or above 7 or surgical indications became evident during observation. The pathologic reports and operative findings were retrospectively correlated with the US diagnosis. For group I patients, clinical examination without knowledge of US findings was correct in 30 (88.9%) cases, 26 (86.7%) of which were detected by US. Four (50%) of eight patients with negative US findings had acute appendicitis. In group II, 12 of 15 patients who had surgery had acute appendicitis, and 10 (83.3%) were detected by US. Two (11%) of 18 patients with negative US findings were finally proved to have acute appendicitis. The average duration from initial clinical examination to surgical decision fpr patients with acute appendicitis was 6.8 hours. There were no false-positives in either group. For patients with typical clinical presentation, US is not superior to clinical examination, and surgery is recommended even if US findings are negative.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1988

Functional organization of the murine leukemia virus reverse transcriptase: characterization of a bacterially expressed AKR DNA polymerase deficient in RNase H activity.

The functional organization of the murine leukemia virus reverse transcriptase was investigated by expressing a molecular clone containing AKR MuLV reverse transcriptase-coding sequences in Escherichia coli. A purified preparation of the expressed enzyme (pRT250 reverse transcriptase) consisted primarily of a 69-kilodalton protein that has normal levels of murine leukemia virus polymerase activity but 10-fold-reduced levels of RNase H compared with the viral enzyme. The deficit in RNase H activity was correlated with the absence of 60 to 65 amino acids normally present at the carboxyl end of murine leukemia virus reverse transcriptase. The results provide additional experimental evidence for the localization of polymerase and RNase H domains to the N- and C-terminal regions of reverse transcriptase, respectively.

AKR murine leukemia virus↗
PubMed1988

Development, organization, and function of tight junctional complexes in the tracheal epithelium of infant ferrets.

The surface epithelium of newborn ferret airways matures rapidly in the first month of life. Prominent developmental features include a transition from predominantly non-ciliated to ciliated cells, quantitative and qualitative changes in secretion of macromolecules, and a transition from secretory to absorptive patterns of ion transport. Freeze-fracture replicas of ferret tracheal epithelium from 0 to 28 days of age exhibited progressive developmental patterns in tight junctional structure from beaded, unclosed patterns in newborns to more closed patterns at 28 days. Strand number increased while the depth of tight junctional structures and the proportion of strands exhibiting discontinuity decreased postnatally. Total transepithelial conductance, paracellular conductance, and cell size decreased over the first month. Our data suggest that changes in physiological parameters that reflect epithelial tight junction permeability can be attributed, at least in part, to maturation of this intercellular junction during the postnatal period.

Animals↗
PubMed1987

[Biological effect of HPD photosensitivity on human stomach cancer cells (MGC-803) in mitotic phase and interphase].

Photodynamic effect of HPD plus light on human stomach cancer cells (MGC-803) in the mitotic phase and interphase was studied. The synchronized mitotic cells were selected from the monolayer of asynchronous growing cells by shaking the culture flask. It was found that the killing frequency of HPD photosensitization was markedly different in the mitotic phase and interphase of synchronous growing MGC-803 cells, but a very small difference was found in HPD alone or light alone groups. The results show that, for adhesive cells in the two phases, there was a marked difference in damage pattern and recovery rate of mitosis 36 hr, 60 hr and 108 hr after photoradiation. The tolerance of mitotic cells to HPD plus light was much greater than that of the interphase cells. In the interphase, a great many of nude nuclei were seen and in the mitotic phase, cytokinesis was arrested resulting in many binucleated or multinucleated cells.

Cell Cycle↗
PubMed1986

Murine leukemia virus pol gene products: analysis with antisera generated against reverse transcriptase and endonuclease fusion proteins expressed in Escherichia coli.

The organization of the murine leukemia virus (MuLV) pol gene was investigated by expressing molecular clones containing AKR MuLV reverse transcriptase or endonuclease or both gene segments in Escherichia coli and generating specific antisera against the expressed bacterial proteins. Reaction of these antisera with detergent-disrupted virus precipitated an 80-kilodalton (kDa) protein, the MuLV reverse transcriptase, and a 46-kDa protein which we believe is the viral endonuclease. A third (50-kDa) protein, related to reverse transcriptase, was also precipitated. Bacterial extracts of clones expressing reverse transcriptase and endonuclease sequences competed with the viral 80- and 46-kDa proteins, respectively. These results demonstrate that the antisera are specific for viral reverse transcriptase and endonuclease. Immunoprecipitation of AKR MuLV with antisera prepared against a bacterial protein containing only endonuclease sequences led to the observation that reverse transcriptase and endonuclease can be associated as a complex involving a disulfide bond(s).

AKR murine leukemia virus↗
PubMed1985

Response of human ciliated respiratory epithelium to brief in vivo ozone exposure: an ultrastructural study.

Ciliated nasal epithelium obtained from human volunteers exposed under controlled conditions to 0.4 ppm of ozone for 4 hr was examined by transmission electron microscopy. These investigations were initiated to evaluate the utility of human ciliated nasal epithelium as a model for the characterization of possible ultrastructural level cytopathic effects induced by short-term, low-level in vivo exposure to ozone. Particular attention was given to both the qualitative and quantitative evaluation of ciliated cells in the nasal respiratory epithelium in response to ozone exposure. The results of these investigations indicated that cell structure is generally retained and no appreciable manifestation of injury is evident in human nasal mucosa in response to the regimen of ozone exposure employed during these studies. Although these investigations were completed under highly controlled circumstances and with the constraints attendant to research on humans subjects, they may provide a fundamental base for future examinations of the potential injurious effects of ozone on human respiratory epithelium under conditions more relevant to habitual environmental exposure.

Cilia↗
PubMed1985

Lack of influence of aluminum hydroxide on the bioavailability and beta-adrenoceptor blocking activity of propranolol.

Plasma concentrations of propranolol and the changes of exercise induced heart rate were determined in 6 healthy subjects. An amount of 40 mg of propranolol was given alone or in combination with 30 ml of aluminum hydroxide gel. Neither the bioavailability nor the beta-adrenoceptor blocking activity of propranolol was significantly changed by concurrent administration of aluminum hydroxide gel. There is no need to increase the propranolol dose when aluminum hydroxide gel is administered concurrently.

Adult↗
PubMed1984

Murine leukemia virus mutant with a frameshift in the reverse transcriptase coding region: implications for pol gene structure.

The molecular defect in the nonconditional B-tropic MuLV pol mutant, clone 23 (Gerwin et al., J. Virol. 31:741-751, 1979), has been characterized by recombinant DNA technology. The entire mutant genome was cloned from an EcoRI digest of integrated cellular DNA into bacteriophage lambda Charon 4A and then subcloned at the EcoRI site of pBR322. NIH-3T3 cells transfected with the plasmid clone, termed pRTM (RTM, reverse transcriptase mutant), reproduced the properties of clone 23 virus-infected cells. In vivo ligation experiments involving cotransfection of subclones of pRTM and wild-type murine leukemia virus localized the defect in the clone 23 genome to an approximately 400-base-pair region in the pol gene between the SalI and XhoI sites. Sequence analysis of this region in the wild-type and mutant genomes revealed that the mutant has one additional C residue located 231 bases downstream of the last base of the SalI recognition site. This 1-base insertion brings three TGA termination codons into phase. Thus, the mutation in clone 23 leads to premature termination of translation, explaining the presence in clone 23 virions of a truncated polymerase with low levels of enzymatic activity. It was previously shown that the gag precursor is cleaved normally in clone 23-infected cells; therefore, if a virus-coded protease is involved in this cleavage, it must be encoded by sequences upstream of the reverse transcriptase region of the pol gene. This consideration, coupled with the observed molecular weight of the mutant polymerase and our precise determination of its C terminus, have led to a proposal for the genetic organization of the murine leukemia virus pol gene.

Animals↗