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Biomedical subjects

S Ma

Publications and source records attributed to S Ma.

At least 73 records · Page 4Linked to original sources
PubMed2000

Reverse of regioselectivity in intramolecular nucleophilic substitution of pi-allyl palladium species. Highly selective formation of vinylic cyclopropanes via the Pd(0)-catalyzed coupling-cyclization reaction of organic iodides with 2-(2', 3'-Dienyl)malonates

Vinylic cyclopropanes were formed highly selectively via the Pd(PPh(3))(4)-catalyzed insertion-intramolecular nucleophilic substitution reaction of aryl or 1-alkenyl iodides with 2-(2', 3'-dienyl)malonates. The regioselectivity observed here is different from what was reported by Cazes et al.

Journal Article↗
PubMed2000

Glycosylation of the cationic peanut peroxidase gene expressed in transgenic tobacco.

The major cationic peanut (Arachis hypogaea) peroxidase, secreted into the extracellular space, is a glycoprotein with three N-linked glycans (polysaccharides) which are connected to the peptide backbone at Asn-60, Asn-144 and Asn-185. In this report, a C-terminal histidine-tagged cationic peanut peroxidase gene was expressed in transgenic tobacco (Nicotiana tabacum). Tissue of the transgenic tobacco was cultured in suspension culture and the his-tagged peroxidase was purified in large quantities from 14-day-old suspension culture. The number of glycans, glycosylation sites and the chemical nature of glycan moieties attached to cationic peanut peroxidase expressed in transgenic tobacco were examined. Cationic peanut peroxidase isolated from the above transgenic tobacco had the identical number of complex glycans, attached at the same glycosylation sites as on cationic peanut peroxidase isolated from peanut suspension culture. Monosaccharide components of these glycans are N-acetylglucosamine (GlcNAc), mannose (Man), fucose (Fuc), xylose (Xyl) and galactose (Gal), the same sugars as found in native cationic peanut peroxidase.

Journal Article↗
PubMed2000

Palladium(0)-catalyzed cyclization reaction of polymer-supported aryl iodides with 1,2-allenyl carboxylic acids. A facile solid-phase synthesis of butenolides.

[reaction--see text] Aryl iodides anchored to Merrifield resin via the linkages between a carboxyl, hydroxyl, or hydroxymethyl group and the benzylic chloride moiety in the resin reacted efficiently with 1,2-allenic carboxylic acids under the catalysis of Pd(0) to afford polymer-supported butenolides. Polysubstituted butenolides can be easily cleaved from the resins by Lewis acid-catalyzed processes in good yields and purities.

4-Butyrolactone↗
PubMed2000

Unusual regioselectivity of Pd(0)-catalyzed coupling reaction of electron-deficient alkenyl halides with allenic/propargylic zinc reagents. Highly selective synthesis of 6-phenylhex-5-yn-2(or 3)-enoates/enitrile and 4-phenyl-6-substituted-hexa-2,4,5-trienoates

The Pd(0)-catalyzed coupling reaction of electron-deficient alkenyl halides with the organozinc formed by the subsequent treatment of 1-phenylalk-1-yne with n-BuLi and ZnBr2 with or without a catalytic amount of HgCl2 was studied. Both the allene-formation- and the alkyne-formation-type coupling reactions were observed with high regio- and stereoselectivity: the reaction of 1-phenylprop-1-yne afforded 6-phenylhex-5-yn-2(or 3)-enoates and -enitriles, while the reaction of 1-phenylhex-1-yne formed 4-phenyl-6-substituted-hexa-2,4,5-trienoates. A plausible explanation for the regioselectivity was discussed. The double bonds in 6-phenylhex-5-yn- 2-enoates were prone to migrate to the position conjugated with the carbon-carbon triple bonds to form 6-phenylhex-5-yn-3-enoates at higher temperature. The migration did not occur in absence of an excess amount of allenic/propargylic zinc reagent or at low temperature.

Journal Article↗
PubMed2000

Responses of nitric oxide synthase expression in the gracile nucleus to sciatic nerve injury in young and aged rats.

Neuronal nitric oxide synthase (nNOS) is induced in dorsal root ganglion neurons following axotomy in young rats, and is also increased in the gracile nucleus neurons of intact aged rats. The present study examined the influence of sciatic nerve axotomy on nNOS expression in the gracile nucleus in young compared to aged rats. The unilateral transection of the sciatic nerve was performed in young (4 months) and old (24 months) Fischer rats. Sections of rat medulla obtained 14 days after axotomy were immunolabelled using a polyclonal antibody directed against nNOS and stained by nicotinamide adenine dinucleotide phosphate diaphorase (NADPHd) histochemistry, a marker of nNOS activity. In young rats, unilateral axotomy produced increased NADPHd containing neurons in the rostral region and the caudal region of the ipsilateral gracile nucleus compared to the side with intact sciatic nerve. In old rats, the NADPHd containing neurons in the ipsilateral gracile nucleus were moderately increased by axotomy over the age changes seen in the contralateral side. Similar results were obtained with nNOS immunoreactivity in young rats, but more cells were seen with NADPHd staining compared to nNOS immunostaining in old rats. The results suggest that unilateral sciatic axotomy causes an increase in nNOS expression in the ipsilateral gracile nucleus of young rats, which is still seen in old rats as an increase over normal aging changes.

Aging↗
PubMed2000

High-Resolution Infrared Spectrum of BrCN in the nu(2) and nu(1)/2nu(2) Regions.

FT infrared spectra of BrCN have been recorded in the region of the nu(2) band near 340 cm(-1), the nu(1) band near 580 cm(-1), and the 2nu(2) band near 690 cm(-1) with a resolution between 2.9 and 4.7 x 10(-3) cm(-1). The vibrational levels (01(1)0), (10(0)0), (02(0)0), (02(2)0), (11(1)0), and (20(0)0) have been analyzed employing cold bands, hot bands, and new millimeter-wave transitions. Band-by-band polynomial analyses and a combined fit of all data relevant to the 2v(1) + v(2) = 2 polyad levels have been performed. The latter fit considered l-resonance interactions between the (02(0)0), e and (02(2)0), e levels and Fermi resonance between the two Sigma states (10(0)0) and (02(0)0). Altogether about 1000 pieces of data up to J = 100 were fitted for each of the two isotopic species with rms of the residuals of 2-8 x 10(-4) cm(-1) for the infrared and 10-120 kHz for the pure rotational data. Copyright 2000 Academic Press.

Journal Article↗
PubMed2000

Expression of an anti-CD3 single-chain immunotoxin with a truncated diphtheria toxin in a mutant CHO cell line.

ADP-ribosylating immunotoxins are generally expressed in Escherichia coli and then refolded in vitro. Because the efficiency of the in vitro refolding process decreases with the number of protein domains and internal disulfide bonds, these immunotoxins have been generally limited to single-chain monovalent structures. We now show that using the hamster cell line CHO K1 RE1.22c (J. M. Moehring and T. J. Moehring, 1979, Somat. Cell Genet. 5, 453-468) that has been mutated to ADP-ribosylation insensitivity, a level of 4 microg/ml of a truncated anti-T cell immunotoxin, DT390-scFvUCHT1, can be secreted into the medium. This immunotoxin is glycosylated at the two potential N-linked glycosylation sites in the toxin moiety: positions 16-18 in the A chain and residues 235-237 in the B chain. The glycosylated immunotoxin is relatively nontoxic (IC(50) 4.8 x 10(-10) M). Removal of the N-linked oligosaccharides by N-glycosidase F treatment or mutations at the two N-linked glycosylation sites results in a highly active immunotoxin with an IC(50) of 4 x 10(-12) M toward CD3(+) Jurkat cells. This is a 12-fold increase in toxicity over the same immunotoxin harvested from E. coli periplasm without refolding. A single Asn(235) Ala mutation that removed the B chain glycosylation was nearly as toxic as the double mutant. This suggests that B chain glycosylation is the major cause for the loss of toxicity.

Animals↗
PubMed2000

Surgical outcomes of photorefractive keratectomy and laser in situ keratomileusis by inexperienced surgeons.

PURPOSE: To investigate the results of photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) procedures performed by novice ophthalmologists and compare the results with those of experienced refractive surgeons. SETTING: Doheny Eye Institute, University of Southern California, Los Angeles, and Department of Ophthalmology, University of California, Irvine, California, USA. METHODS: In this retrospective case series, data were examined from the first PRK procedures by 33 consecutive ophthalmologists and the first LASIK procedures by 19 consecutive ophthalmologists. Preoperative and postoperative uncorrected visual acuity (UCVA) and best spectacle-corrected visual acuity (BSCVA), as well as intraoperative and early postoperative complications, were recorded. RESULTS: In the PRK group, 33.3% of eyes achieved a UCVA of 20/20 and 87.8%, 20/40 or better; 54.5% were within +/-0.5 diopter (D) of emmetropia and 87.8%, within +/-1.0 D. Two eyes with a preoperative spherical equivalent of greater than -11.0 D lost 2 lines of BSCVA. If eyes with low myopia (</= -6.5 D) only were included, 40.7% achieved a UCVA of 20/20 and 96.3%, 20/40 or better. In the LASIK group, 52.6% achieved a UCVA of 20/20 and 84. 2%, 20/40 or better; 78.9% were within +/-0.5 D of emmetropia and 89. 5%, +/-1.0 D. No eye in the LASIK group lost 2 or more lines of BSCVA. CONCLUSIONS: Photorefractive keratectomy and LASIK are reasonably safe procedures that can be learned quickly by ophthalmic surgeons. Our data suggest that results achieved by beginning surgeons are comparable to those reported by experienced surgeons.

Adolescent↗
PubMed2000

Induction of Ro/SSA antigen expression on keratinocyte cell membrane by heat shock and phorbol 12-myristate 13-acetate as well as estradiol and ultraviolet B.

Skin is one of the main target organs in lupus erythematosus and in some circumstances, skin lesions precede systemic manifestations. Previous studies have demonstrated that Ro/SSA antigen antibody might be involved in the pathogenesis of lupus erythematosus. The present study was performed to investigate the factors regulating expression of Ro/SSA antigens on the cell surface of keratinocytes. Cultured normal human keratinocytes were treated with 50-200 mJ/cm(2) of ultraviolet B (UVB) irradiation, 10(-9) to 10(-5) mol/l of 17beta-estradiol, 5-10 microg/l of phorbol 12-myristate 13-acetate (PMA), and 42 and 45 degrees C heat shock, respectively. The Ro/SSA antigen expressions were determined by indirect immunofluorescence. The results showed that keratinocytes receiving UVB irradiation expressed Ro/SSA antigen on cell membranes in a dose-dependent fashion. 17beta-estradiol treatment also induced Ro/SSA antigen expression dose-dependently. Keratinocyte expression of Ro/SSA antigens was also induced by heat shock stimulation. The 45 degrees C heat shock showed a stronger effect than 42 degrees C heat shock. Keratinocytes incubated for 24 h after heat shock had more antigen-expressing cells than those incubated for 6 h after heat shock. PMA at 5 and 10 microg/l also strongly induced Ro/SSA antigen expression. These results suggest that Ro/SSA antigen expression can be regulated by many factors and that protein kinase C signal transduction pathway might be involved in this process.

Autoantigens↗
PubMed2000

Assessment of maximal fertilization rates with intracytoplasmic sperm injection.

PURPOSE: Maximal fertilization rates following ICSI were assessed using two essential steps: immobilization of sperm and aspiration of oocyte cytoplasm. METHODS: ICSI procedure was performed for couples (N = 42) in whom the male suffered severe infertility or failure of fertilization in previous IVF cycle using different oocyte cytoplasmic aspiration and sperm immobilization methods. Outcome in four patient groups was measured by oocyte damage, fertilization rate, and pregnancy rate. RESULTS: Maximal fertilization (90%) were achieved from the group which used immobilization of sperm by hard-touching the tail with a pipette and optimal aspiration of oocyte cytoplasm. CONCLUSIONS: The results suggest that if the immobilization of sperm and aspiration of oocyte cytoplasm are handled right during ICSI, this procedure can be expected to yield a 90% fertilization rate.

Female↗
PubMed2000

The Australian National Sub-acute and Non-acute Patient Casemix Classification (AN-SNAP): its application and value in a stroke rehabilitation programme.

OBJECTIVE: To investigate whether the Australian National Sub-acute and Non-acute Patient Casemix Classification (SNAP) and Functional Independence Measure and Functional Related Group (Version 2) (FIM-FRG2) casemix systems can be used to predict functional outcome, and reduce the variance of length of stay (LOS) of patients undergoing rehabilitation after strokes. DESIGN AND SETTING: The study comprised a retrospective analysis of the records of patients admitted to the Cedar Court Healthsouth Rehabilitation Hospital for rehabilitation after stroke. SUBJECTS: The sample included 547 patients (83.3% of those admitted with stroke during this period). Patient data were stratified for analysis into the five SNAP or nine FIM-FRG2 groups, on the basis of the admission FIM scores and age. MAIN OUTCOMES: The AN-SNAP classification accounted for a 30.7% reduction of the variance of LOS, and 44.2% of motor FIM, and the FIM-FRG2 accounts for 33.5% and 56.4% reduction respectively. Comparison of the Cedar Court with the national AN-SNAP data showed differences in the LOS and functional outcomes of older, severely disabled patients. Intensive rehabilitation in selected patients of this type appears to have positive effects, albeit with a slightly longer period of inpatient rehabilitation. CONCLUSIONS: Casemix classifications can be powerful management tools. Although FIM-FRG2 accounts for more reduction in variance than SNAP, division into nine groups meant that some contained few subjects. This paper supports the introduction of AN-SNAP as the standard casemix tool for rehabilitation in Australia, which will hopefully lead to rational, adequate funding of the rehabilitation phase of care.

Activities of Daily Living↗
PubMed2000

[Correlation of photoplankton and its environmental factors in Rushan Bay].

The relationship between photoplankton and its environmental factors in Rushan Bay was studied from June to September, 1995. The result shows that there existed a negative correlation between the number of photoplankton and the content of inorganic nutrients. The correlation coefficients for inorganic nitrogen and phosphorus were -0.67 and -0.80, respectively. The dissolved oxygen and chlorophyll-a were positively correlated to photoplankton, and their correlation coefficients were 0.92 and 0.85 respectively. Based on N/P analysis, the content of inorganic nitrogen was relatively short to the reproductive growth of photoplankton during experimental months, except for the last ten days of August.

China↗
PubMed2000

Clinical significance of changes in beta-adrenoreceptors in peripheral lymphocytes in patients with essential hypertension.

OBJECTIVE: To explore the relationship of beta-adrenoreceptor density and function with the condition of patients with essential hypertension. METHODS: In the present study, 69 male patients with essential hypertension at different stages were compared with a group of age-matched normotensive controls. beta-adrenoreceptor maximum bound volume (Bmax) in peripheral lymphocytes was measured by 3H-dihydroalprenolol (3 H-DHA) radio ligand binding. beta-adrenoreceptor responsiveness was determined by Salbutamol (injection). RESULTS: In patients with essential hypertension at stages I and II, Bmax was significantly higher (P < 0.01 and P < 0.001, respectively) and the chronotropic doses of Salbutamol required to increase the heart rate by 30 beats/min (CD30) were significantly lower (P < 0.01 and P < 0.001, respectively) than in age-matched normotensive control subjects. In patients with essential hypertension at stage III, Bmax was significantly lower and CD30 was significantly higher (both P < 0.01) than those in the age-matched normotensive control subjects. Bmax was significantly higher and CD30 was significantly lower (both P < 0.001) in patients with essential hypertension and with left ventricular hypertrophy (LVH) than that in patients with essential hypertension but without LVH. In patients with essential hypertension and heart failure, Bmax was significantly lower and CD30 was significantly higher (both P < 0.001) than those in patients with essential hypertension without heart failure. CONCLUSIONS: The changes of beta-adrenoreceptor density and function were related to hypertension, hypertension complicated with ventricular hypertrophy, and heart failure. They may be viewed as indexes of the condition in the patients with essential hypertension.

Adrenergic beta-Agonists↗
PubMed2000

[Radiographic studies of cervical spine motion range in normal Chinese subjects with computer-assisted image analysis: full flexion and extension].

OBJECTIVES: To study the degenerative regularity of normal Chinese cervical spine by observing the motion range of full cervical flexion and extension, and to provide evidences for further investigation of cervical segmental instability. METHODS: 764 X-ray plain films of full cervical flexion and extension in 382 normal Chinese subjects (214 were male and 168 female) were investigated using self-designed cervical X-ray image analysis system. The subjects within the same sex group were divided into three groups according to the age: group A (20 years to 39 years), group B (40 years to 59 years) and group C (60 years to 76 years). During the full cervical flexion and extension motion, total intervertebral motion range (from C(2) - C(3) to C(6) - C(7)) and intervertebral motion range at each level were major parameters. RESULTS: The range of total intervertebral motion showed much greater mobility in group A than in group B and group C (P < 0.01) but no statistically significant difference between group B and group C (P > 0.05). The range of intervertebral motion was maximal at C(5) - C(6) in group A. The place of maximal motion shifted to the C(4) - C(5) in both group B and group C. C(2) - C(3) showed minimal mobility in all three groups. There was no statistically significant difference (P > 0.05) between male and female. CONCLUSIONS: The motion range and degenerative regularity of normal Chinese cervical spine were similar in either sex. The range of total intervertebral motion (from C(2) - C(3) to C(6) - C(7)) had a tendency to decrease rapidly and then became steady with age. For the range of intervertebral motion, the place of maximal motion shifted to the higher level with age from C(5) - C(6) in group A to C(4) - C(5) in group B and group C.

Adult↗
PubMed2000

[Effect of sodium fluoride on bone turnover and bone loss of vertebrae and tibia in ovariectomized rats].

OBJECTIVE: To investigate the effect of sodium fluoride on bone turnover and bone loss of vertebra and tibia of ovariectomized rats. METHODS: 34 female Wistar rats, 16 weeks old, were divided into 3 groups: sham-ovariectomy (CON), bilateral ovariectomy (OVX) and both OVX and NaF-treatment groups (OVX + NaF, 1.0 mg/kg BW). All of the rats were sacrificed 12 weeks after the treatment. Serum was collected for the analysis of estradiol, calcium, phosphorum and alkaline phosphotase. Temur was used for the analysis of calcium content. Tibiae and the first lumbar vertebral bodies were decalcified for histomorphometry. RESULTS: After treatment with NaF, bone resorption was not inhibited, but bone formation was significantly increased. The trabecular bone volume of vertebrae (18.73% +/- 3.04%) and tibiae (14.30% +/- 5.87%) was significantly increased in comparing with of OVX rats (15.07% +/- 2.45% and 8.81% +/- 2.60%, P < 0.05), but it was markedly lower than that of CON rats (22.44% +/- 1.82% and 24.87% +/- 4.02%, P < 0.05 and P < 0.01). CONCLUSIONS: NaF could not decrease bone turnover and it, has only a partial protective effect against bone loss of either vertebra or tibia.

Animals↗
PubMed2000

[B7 and DC vaccines induced anti-tumor immunity against murine T-lymphocyte leukemia L615].

OBJECTIVE: To study the effect of B7 and DC vaccines in inducing anti-tumor immunity in murine T-lymphocyte leukemia L615. METHODS: In vivo, murine mortality and survival were observed to compare the difference between B7 and DC vaccine in inducing immunoprotection against the subsequent challenge of live L615 cells;in vitro, specific cytotoxic assay and MLR were performed to test the specific cytotoxicity and proliferative activity of effective T cells. RESULTS: Both vaccines could efficiently improve T cell mediated anti-leukemic immunity in syngenic hosts, and DC vaccine was revealed to be more efficient. In vitro observations showed that both vaccines could induce tumor specific cytotoxicity and proliferative activity of effective T cells. CONCLUSION: DC vaccine is promising in tumor immunotherapy owing to its safety, efficiency and convenience.

Animals↗