Biomedical subjects
Publications and source records attributed to C Wei.
The energies of CrKbeta X-Rays in metel Cr, Cr2Os and K2CrO4, which are excited respectively by gamma-ray 59.6keV from radioactive source 241Am, have been measured by Si(Li) spectrometry. It is shown in the experiment that the peak of CrKbeta X-ray in K2CrO4 shifts 2.12 +/- 0.27eV compared to that in metel Cr.
BACKGROUND: Testicular volume is used to evaluate male growth and development. Since the volume of the testes varies in different races, data for Taiwanese boys are essential to assess normal testicular growth. METHODS: Testicular volume was measured using Prader's orchidometer in 430 boys aged 0-14 years. RESULTS: Testicular growth was minimal before nine to 10 years of age. The mean testicular volume (mean of left and right testes) was 1.3 +/- 0.3 ml in newborns, 1.8 +/- 0.5 ml at six years of age and 9.1 +/- 3.5 ml at 12 years of age. CONCLUSIONS: Data on the normal values of testicular volume in Taiwanese boys will be helpful in assessing the growth of normal individuals as well as in patients with testicular or hormonal disorders.
Human prostate-specific antigen (PSA) has been widely used as a serum marker for cancer of the prostate. The cell type-specific expression of PSA also makes it a potential tumor antigen for prostate cancer immunotherapy. Study of the immunological aspects of PSA within either normal or malignant prostate tissue has been hampered by the lack of a mouse model, because no PSA counterpart has been identified in mice. Using a 14-kb genomic DNA region that encompasses the entire human PSA gene and adjacent flanking sequences, we generated a series of human PSA transgenic mice. In the six independent lines of transgenic mice generated, the expression of the human PSA transgene, driven by its own cis-acting regulatory elements, is specifically targeted to the prostate. Tissue distribution analysis demonstrated that PSA transgene expression closely follows the human expression pattern. Immunohistochemical analysis of the prostate tissue also showed that the expression of the PSA transgene is confined to the ductal epithelial cells. Despite expressing PSA as a self-antigen in the prostate, these transgenic mice were able to mount a cytotoxic immune response against PSA expressed by tumor cells, indicating that expression of the transgene has not resulted in complete nonresponsiveness. This transgenic mouse model will provide a well defined system to gain an insight into the mechanisms of nonresponsiveness to PSA, ultimately leading to strategies for immunotherapy of human prostate cancer using PSA as the target antigen.
Prostaglandin H synthase (PGHS) is a heme protein that catalyzes both the cyclooxygenase and peroxidase reactions needed to produce prostaglandins G2 and H2 from arachidonic acid. Replacement of the heme group by mangano protoporphyrin IX largely preserves the cyclooxygenase activity, but lowers the steady-state peroxidase activity by 25-fold. Thus, mangano protoporphyrin IX serves as a useful tool to evaluate the function of the heme in PGHS. A detailed kinetic analysis of the peroxidase reaction using 15-hydroperoxyeicosatetraenoic acid (15-HPETE), EtOOH, and other peroxides as substrates has been carried out to compare the characteristics of PGHS reconstituted with mangano protoporphyrin IX (Mn-PGHS) to those of the native heme enzyme (Fe-PGHS). The rate constant describing the reaction of Mn-PGHS with 15-HPETE to form the oxidized, Mn(IV) intermediate with absorption at 420 nm, exhibits saturable behavior as the 15-HPETE concentration is raised from 10 to 400 microM. This is most likely due to the presence of a second, earlier intermediate between the resting enzyme and the Mn(IV) species. Measurements at high substrate concentrations permitted resolution of the absorbance spectra of the two oxidized Mn-PGHS intermediates. The spectrum of the initial intermediate, assigned to a Mn(V) species, had a line shape similar to that of the later intermediate, assigned to a Mn(IV) species, suggesting that a porphyrin pi-cation radical is not generated in the peroxidase reaction of Mn-PGHS. The rate constant estimated for the formation of the earlier intermediate with 15-HPETE is 1.0 x 10(6) M-1 s-1 (20 degrees C, pH 7.3). A rate constant of 400 +/- 100 s-1 was estimated for the second step in the reaction. Thus, Mn-PGHS reacts considerably more slowly than Fe-PGHS with 15-HPETE to form the first high-valent intermediate, but the two enzymes appear to follow a similar overall reaction mechanism for generation of oxidized intermediates. The difference in rate constants explains the observed lower steady-state peroxidase activity of Mn-PGHS compared with Fe-PGHS.
Single stranded DNA-fragments containing short runs of isoguanine such as d(T4iG4T4) (5) or d(iG4T4) (6) form quartet structures by self-assembly of the isoguanine residues. The stoichiometry of the complexes is deduced from mixed aggregates formed between d(T4iG4T4) and d(iG4T4). The iGd-tetrads are more stable with regard to their thermal denaturation and to their resistance against enzymatic phosphodiester hydrolysis than those formed by dG.
To investigate bone mineral distribution in humans, the authors conducted a cross-sectional survey of, and performed bone-density measurements on, 1,310 healthy Japanese ranging in age 5 to 85 years. Eight hundred fifty-eight of the subjects were female, and 452 were male. Arm, leg, and spine bone mineral content (BMC) and bone mineral density (BMD) were assessed by dual-energy X-ray absorptiometry (DXA), and the subjects were divided into 5-year age groups. BMD showed increases with skeletal growth until reaching a peak at 15 to 19 years in females, and 25 to 29 for males. For both sexes the fastest growth to maturity in terms of bone mass values was in the late 20s. Females, though, had higher arm, leg, and spine remodeling rates than males. In premenopausal women no changes in arm, leg or spine BMC and BMD were observed. Postmenopausal women showed an overall reduction in bone mass, most noticeably in the spine. After menopause, women had about 10 years of accelerated loss (1.46%/year). Vertebral BMD values were similar for men and women (1.10 +/- 0.20g/cm2 for males vs. 1.09 +/- 0.14g/cm2 for females, p > 0.05). BMC values were significantly higher in males, and males at all times had a higher arm and leg BMD. There were no significant value differences in either sex for left and right leg BMC and BMD; however, from the age of 15, right arm values were significantly higher likely due to right handedness. For both sexes the order of BMC and BMD was leg, spine, and arm.
The contents of NO, TNF-alpha and IL-8 in the cerebrospinal fluids (CSF) of patients with tuberculous and cryptococcic meningitis were detected. The results showed that the concentration of NO2-/NO3- and the levels of TNF-alpha and IL-8 in CSF of the two kinds of meningitis were higher than those of normal CSF, and the concentration of NO2-/NO3- correlated positively to the content of TNF-alpha. The results indicate that the over production of NO, TNF-alpha and IL-8 in CSF may involve in the tissue inflammation and damage of central nerve system infection.
To study the effect of vocal polyps on vocal vibration, the authors analysed the EGG waveform of 201 cases of vocal polyps of various location and shape. The results showed that the EGG waveform in opening phase appeared a notch for vocal polyps with pedicle, and appeared steep for vocal polyps with a wide base. Among the polyps whose waveform appearing a notch in closing phase, most of their base located below vocal cord. Whether the polyps were located in the anterior, middle or posterior of the vocal cord and whether the polyps were unilateral or bilateral there are no effect on the EGG waveform. EGG was the potential technique for studying vocal function.
The three-dimensional distribution of arsenic impurity concentration on the silicon wafer surface is determinaed by means of synchrotron radiation X-ray microfluorescence (SRXRF) and total reflection X-ray fluorescence (TXRF) anslysis. The result of depth profile of As is checked with secondary ion mass spectrometry (SIMS) and the agreement is reasonably good.
Oligonucleotides with isoguanine-cytosine base pairs form duplexes with parallel chain orientation. This strong base pair dictates the strand polarity when additional dA-dT or N7Ad-dT pairs are present. The same is observed for the isocytosine-guanine pair. Quartet structures are built by the self-assembly of oligonucleotides containing short runs of isoguanine or 7-deazaisoguanine. New base pairs between isoguanine or guanine and 5-aza-7-deazaguanine are presented.
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The self-aggregation of the oligonucleotide d(T4isoG4T4) (1) is investigated. Based on ion exchange HPLC experiments and CD spectroscopy, a tetrameric structure is identified. This structure was formed in the presence of sodium ions and shows almost the same chromatographic mobility on ion exchange HPLC as d(T4G4T4) (2). The ratio of aggregate versus monomer is temperature dependent and the tetraplex of [d(T4isoG4T4)]4 is more stable than that of [d(T4G4T4)]4. A mixture of d(T4isoG4T4) and d(T4G4T4) forms mixed tetraplexes containing strands of d(T4isoG4T4) and d(T4G4T4).
Gaucher disease is an inherited sphingolipidosis resulting from deficient glucocerebrosidase activity. Three clinical forms of Gaucher disease have been described: type 1 as non-neuronopathic, type 2 as acute neuronopathic, and type 3 as subacute neuronopathic. We recently identified a rare mutation (G-->A at glucocerebrosidase cDNA nucleotide position 1604) [Choy et al., 1994a, Am J Med Genet 51:156-160] and a novel mutation (T-->G at glucocerebrosidase cDNA nucleotide position 1366) in two type 1 Gaucher patients by sequence analysis of the entire glucocerebrosidase coding region [Choy et al., 1994a, 1994b, Hum Mol Genet 3:821-823]. To demonstrate that these are deleterious and not neutral mutations, we cloned the full-length glucocerebrosidase cDNA of patients and of a normal control in the plasmid vector pAcUW1, recombined the human gene into the Baculovirus genome downstream of its polyhedron p10 promoter, and expressed the inserted gene in cultured cells of Spodoptera frugiperda transfected by recombinant Baculovirus. The levels of residual glucocerebrosidase activity determined in transfected cells with the Gaucher G1604A and T1366G alleles are 6.9% and 2.9% of that expressed by the normal allele (normal = 352.0 nmol/hr/mg protein or 100%). By comparison, the enzyme-specific activity expressed in transfected cells by 2 known Gaucher alleles, A1226G and T1448C, that are prevalent in type 1 and type 2 Gaucher disease are 23.4% and 3.3% of normal. No endogeneous glucocerebrosidase activity was detected in cultured cells transfected by either the wild-type Baculovirus or Baculovirus with the pAcUW1 plasmid vector without the glucocerebrosidase cDNA insert. These findings show that the Baculovirus expression system in cultured Spodoptera frugiperda cells is a suitable system for the functional expression and characterization of the normal and mutant glucocerebrosidase alleles. Moreover, the use of this expression system demonstrates that the G1604A and T1366G mutations are both deleterious mutations resulting in profoundly deficient glucocerebrosidase activity and subsequent Gaucher disease.
The relationship between immunotoxicity of ammonium metavanadate (NH4VO3) and levels of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 (IL-1) was studied with a NH4VO3-treated murine macrophage-like cell line, 1774 and resident peritoneal macrophages (PEM) obtained from treated mice. Lipopolysaccharide (LPS)-induced elevation of extracellular TNF-alpha in PEM and 1774 cells was not markedly affected by prior treatment with vanadate. However, PEM from treated mice at 10 mg V/kg (10V) had a significantly lower level of LPS-induced intracellular TNF-alpha. NH4VO3-treated 1774 cells at 3.6 (V1) and 7.2 micrograms V/10(7) cells (V2) had significantly higher levels of intracellular TNF-alpha than the PO4 and V3 (10.8 micrograms V/10(7) cells) groups. Although the four PEM groups showed no marked difference in extracellular IL-1 alpha levels, PEM from treated mice at 2.5V and 10V had significantly lower levels of intracellular IL-1 alpha than those from control groups. 1774 cells from PO4 and NH4Cl groups showed significant increases in intracellular IL-1 alpha following treatment with LPS. However, 1774 cells with prior treatment with vanadate revealed significant reduction in levels of LPS-induced intracellular IL-1 alpha when compared to control groups. Therefore, the previously reported reduced resistance of vanadate-treated mice to Listeria monocytogenes could be attributed to an inhibitory effect on the production of IL-1 alpha in macrophages.
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Human prostate-specific antigen (PSA) has a highly restricted tissue distribution. Its expression is essentially limited to the epithelial cells of the prostate gland. Moreover, it continues to be synthesized by prostate carcinoma cells. This makes PSA an attractive candidate for use as a target antigen in the immunotherapy of prostate cancer. As a first step in characterizing the specific immune response to PSA and its potential use as a tumor-rejection antigen, we have incorporated PSA into a well-established mouse tumor model. Line 1, a mouse lung carcinoma, and P815, a mouse mastocytoma, have been transfected with the cDNA for human PSA. Immunization with a PSA-expressing tumor cell line demonstrated a memory response to PSA which protected against subsequent challenge with PSA-expressing, but not wild-type, tumors. Tumor-infiltrating lymphocytes could be isolated from PSA-expressing tumors grown in naive hosts and were specifically cytotoxic against a syngeneic cell line that expressed PSA. Immunization with tumor cells resulted in the generation of primary and memory cytotoxic T lymphocytes (CTL) specific for PSA. The isolation of PSA-specific CTL clones from immunized animals further demonstrated that PSA can serve as a target antigen for antitumor CTL. The immunogenicity studies carried out in this mouse tumor model provide a rationale for the design of methods to elicit PSA-specific cell-mediated immunity in humans.
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