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Biomedical subjects

L Shi

Publications and source records attributed to L Shi.

At least 109 records · Page 6Linked to original sources

Vulnerable populations and health insurance.

This study provided a national profile of health insurance of certain vulnerable populations including children, racial/ethnic minorities, low-income families, non-metropolitan statistical area (MSA) residents, and those with poor health status. The study shows an increase in the proportion of uninsured nonelderly population. While public insurance helped reduce the employment- and health-related disparities in private coverage, it has not overcome other disparities related to vulnerable characteristics including race/ethnicity, wages, education, and area of residence. Comparison between health maintenance organization (HMO) and fee-for-service insurance indicates that younger although not much healthier people, racial/ethnic minorities, MSA residents, and those residing in the West and Northeast regions were more likely to have HMO coverage. To reduce significant disparities in health insurance coverage, policy makers will have to consider expanding public insurance coverage, targeting vulnerable groups, particularly those with multiple vulnerable characteristics rather than merely the economically distressed. Expecting managed care to achieve cost containment for services provided to vulnerable populations may be unrealistic.

Adolescent↗

Individual sociodemographic characteristics associated with hospitalization for pediatric ambulatory care sensitive conditions.

This study examined the association of individual sociodemographic characteristics with pediatric ambulatory care sensitive condition (ACSC) hospitalizations in American hospitals while controlling for selected hospital characteristics. Data came from the 1994 National Hospital Discharge Survey. Bivariate statistical comparisons were performed to test the differences between ACSC and non-ACSC hospitalization rates in patient demographic and hospital characteristics. Logistic regression was followed to examine the relative significance of patient and hospital characteristics associated with pediatric ACSC hospitalizations. Such individual sociodemographic characteristics as age, race, and insurance status were significant predictors of ACSC hospitalization. Younger children were more likely to have ACSC hospitalization than older ones. Black children were 1.653 times more likely than white children to be hospitalized for ACSC (confidence interval = 1.53-1.79). Those with Medicaid or no secondary insurance were more likely to be hospitalized for ACSC than those with private insurance or with secondary insurance.

Adolescent↗

Biological activity of CD-ring modified 1alpha,25-dihydroxyvitamin D analogues: C-ring and five-membered D-ring analogues.

Nonsteroidal analogues of 1alpha,25(OH)2D3, lacking either the full five-membered D ring (C-ring analogues) or the full six-membered C ring (D-ring analogues) are more potent inhibitors of cell proliferation or inducers of cell differentiation than is 1alpha,25(OH)2D3. Maximal superagonistic activity was seen for the C-ring analogue with a 24(R)-hydroxyl group in the side chain [30- to 60-fold the activity of 1alpha,25(OH)2D3]. The 19-nor-16-ene-26,27-bishomo C-ring analogue showed the best ratio of antiproliferative to calcemic effects (1275-fold better than 1alpha,25(OH)2D3 and severalfold better than all vitamin D analogues so far described). The analogues are able to stimulate specific vitamin D-dependent genes and are active in transfection assays using an osteocalcin promoter VDRE. Low binding affinity to the vitamin D binding protein, differences in metabolism, or affinity for the vitamin D receptor (VDR) are not the most important explanations for the enhanced intrinsic activity. However, the analogues are able to induce conformational changes in the VDR, which makes the VDR-ligand complex more resistant against protease digestion than is 1alpha,25(OH)2D3. In contrast to 20-epimer steroidal vitamin D analogues, 20-epimer C-ring analogues were less potent than analogues with a natural C-20 configuration. In conclusion, several nonsteroidal vitamin D analogues are superagonists of 1alpha,25(OH)2D3 despite lower receptor affinity and, for the C-ring analogues, higher flexibility of the side chain; moreover, they have a better selectivity profile than all analogues yet published.

Calcitriol↗

Type of health insurance and the quality of primary care experience.

OBJECTIVES: This study examined the association between type of health insurance coverage and quality of primary care as measured by its distinguishing attributes--first contact, longitudinality, comprehensiveness, and coordination. METHODS: The household component of the 1996 Medical Expenditure Panel Survey was used for this study. The analysis primarily focused on subjects aged younger than 65 years who identified a usual source of care. Logistic regressions were used to examine the independent effects of insurance status on primary care attributes while individual sociodemographic characteristics were controlled for. RESULTS: The experience of primary care varies according to insurance status. The insured are able to obtain better primary care than the uninsured, and the privately insured are able to obtain better primary care than the publicly insured. Those insured through fee-for-service coverage experience better longitudinal care and less of a barrier to access than those insured through health maintenance organizations (HMOs). CONCLUSIONS: While expanding insurance coverage is important for establishing access to care, efforts are needed to enhance the quality of primary health care, particularly for the publicly insured. Policymakers should closely monitor the quality of primary care provided by HMOs.

Adolescent↗

Primary care, income inequality, and self-rated health in the United States: a mixed-level analysis.

Using the 1996 Community Tracking Study household survey, the authors examined whether income inequality and primary care, measured at the state level, predict individual morbidity as measured by self-rated health status, while adjusting for potentially confounding individual variables. Their results indicate that distributions of income and primary care within states are significantly associated with individuals' self-rated health; that there is a gradient effect of income inequality on self-rated health; and that individuals living in states with a higher ratio of primary care physician to population are more likely to report good health than those living in states with a lower such ratio. From a policy perspective, improvement in individuals' health is likely to require a multi-pronged approach that addresses individual socioeconomic determinants of health, social and economic policies that affect income distribution, and a strengthening of the primary care aspects of health services.

Adolescent↗

Comparison of polymerase chain reaction, immunohistochemistry and conventional histopathology in the diagnosis of early leprosy in Sichuan Province of China.

46 formalin-fixed, paraffin-embedded skin biopsy specimens, which were clinically suspected or diagnosed as early leprosy, were retrieved from the files of Sichuan, China from 1997 to 1999. All of them were examined by polymerase chain reaction (PCR) using the primers amplifying the 130 base-pair fragment of the gene from the 16S ribosomal RNA of Mycobacterium leprae, hematoxylin and eosin (H&E) staining, modified Fite-Faraco technique for M. leprae and immunostaining with the antiserum against the PGL-1, LAM-B, S-100 protein using ABC method. PCR was positive for 27 (58.7%) of 46 specimens. In 13 (28.3%) among them, only PCR signals were positive for M. leprae and all other test were negative. AFB was positive for 7 (15.2%) of 46, PGL-1 was positive for 17 (36.9%) of 46, LAM-B was positive for 10 (21.7%) of 46. Early epithelioid cells granuloma was detected in 4 (8.7%) patients (TT 3, BT 1), macrophage granuloma was detected in 1 (2.2%) patient (BL), S-100 protein staining showed early nerve granuloma for 4 (8.7%) of 46, peripheral nerve inflammatory infiltration for 11 (23.9%) of 46. Comparison PCR with other method showed statistically significant difference. PCR have an advantage over microscopic examination in detecting M. leprae in biopsy specimens negative for acid-fast bacilli.

China↗

Respiratory symptoms and use of medical care associated with child day care and health care plan among preschool children.

This study compared the risk of respiratory infections in pre-school children (under 6-year-old) attending day care center and those taken care of at home by controlling for the type of health plan and sociodemographic characteristics. The study population consists of members of two health plans residing in two South Carolina counties. Results show that the risks of respiratory symptoms were higher among children attending day care settings than those taken care of at homes although this relationship is more apparent among Medicaid children than among HMO children. While the type of child care has weak influence on medical care utilization, the type of health plan exerts strong influence on utilization for both day care and home care groups.

Chi-Square Distribution↗

[Evaluation of immune prophylaxis of recombinant urease subunit of Helicobacter pylori].

OBJECTIVE: To evaluate the immune prophylaxis of recombinant urease subunit A or B (rUreA or rUreB). METHODS: The BALB/C mice were divided into seven groups: negative control group, control group with CTB, control group with rUreA, control group with rUreB, experimental group with rUreA + CTB and experimental group with rUreB + CTB, experimental group with sonicate + CTB, which were gastrically inoculated with 150 ml PBS, 5 micrograms CTB, 50 micrograms rUreA, 50 micrograms rUreB, 50 micrograms rUreA + CTB, 5 micrograms rUreB + CTB and 400 micrograms sonicate + 5 micrograms CTB, respectively. Two weeks later, the mice were gastrically infected with H. pylori (10(7)-10(8) CPU per time). 4, 8 and 12 weeks later, the mice were killed and the immune protection of PBS, CTB, rUreA, rUreB, rUreA + CTB, rUreB + CTB and sonicate + CTB were evaluated by the presence of H. pylori in gastric tissue stained with Giemsa by microscopy. The mice in the side-effecting groups of rUreA + CTB and rUreB + CTB were not infected with H. pylori. 12 weeks later, the mice in the two groups were killed, and the side effects of rUreA + CTB and rUreB + CTB were evaluated by the infiltration of inflammation cells in gastric tissue stained with HE by microscopy. RESULTS: The mice gastrically inoculated with CTB, rUreA or rUreB had significantly less H. pylori. The immune protective effect of rUreA, rUreB or sonicate of H. pylori combined with CTB was stronger than that of rUreA, rUreB or sonicate of H. pylori alone. The immune protective effect of rUreA + CTB occurred later than that of rUreB + CTB or sonicate of H. pylori + CTB. The mice immunized with rUreA + CTB, rUreB + CTB or sonicate of H. pylori + CTB were not completely protected against H. pylori infection. The mice immunized with rUreA + CTB, rUreB + CTB or sonicate of H. pylori + CTB were less infected with H. pylori, and had mild inflammation of gastric tissue. CONCLUSION: Mice immunized with rUreA + CTB, rUreB + CTB or sonicate of H. pylori + CTB could not be completely protected against H. pylori infection and have alleviated inflammation of gastric tissue.

Animals↗

[Effects of chronic exposure to lead on long-term potentiation in hippocampal CA1 area of young rats in vivo].

OBJECTIVE: To study the effects of chronic exposure to lead on learning and memory function in young rats, based on the plasticity of their synapse function. METHODS: With method of extracellular glass microelectrode recording, effects of exposure to lead at different concentrations on long term potentiation (LTP) induction in hippocampal CA(1) area of young rats in vivo were observed. RESULTS: Incidence of LTP and mean amplitude increase after application of high frequency stimulus decreased, as blood lead in rats reached (3.28 +/- 0.88) micromol/L, even causing long term depression. To the exposed rats, their mean increase ratio in their population spike amplitudes after high-frequency stimulation correlated inversely with their brain lead load. CONCLUSION: Chronic lead exposure could damage in vivo LTP induction and maintenance in the CA(1) area in hippocampus of rats, and the severity of damage increased with the extent of exposure to lead.

Animals↗

[The preliminary study on the gene mutations of sixty patients with G6PD deficiency in Yunnan province].

OBJECTIVE: To analyze the types and distribution of glucose-6-phosphate dehydrogenase (G6PD) gene mutations in Yunnan province. METHODS: By using the natural primers or mis-matched primers mediated polymerase chain reaction (PCR) followed by endonuclease digestion methods, six types of G6PD gene mutations, G1388A, G1376T, C1024T, G392T, C592T and A95G were in sixty patients with G6PD deficiency. RESULT: Six types of mutation were revealed: 28.3% (17 of 60) were G1388A, 11.7% (7 of 60) G1376T, 6.7% (4 of 60) C1024T, 1.7% (1 of 60) G392T, 1.7% (1 of 60) C592T, 1.7% (1 of 60) A95G and 48.3% (29 of 60) unidentified. C592T mutation is the first report in Yunnan people. CONCLUSIONS: The G6PD gene in Yunnan people is heterogeneous. Research of G6PD gene mutation types may provide some useful data for clinical diagnosis and prevention of G6PD deficiency, and for human genetic study.

Amino Acid Substitution↗

[Indicators for the assessment of iodine nutritional status].

Selecting appropriate evaluation indicators for surveying and monitoring iodine nutritional status is needed. The indicators, which are used commonly in recent literature, are urinary iodine, thyroid volume, dietary iodine intake, thyroid function parameters and intelligence quotient. These indicators are summarized on their clinical significance, application range, expression method and so on. The purpose of this review is to provide some scientific references for people who are working on prevention and treatment of iodine deficiency disorders.

Anthropometry↗

[Sampling survey for iodine content of iodized salt in household of CFNSS in 1998].

The sampling survey for iodine content of iodized salt was conducted in 36 food and nutrition surveillance sites of CFNSS in 1998 in China, which covered 26 provinces, 362 portions of salt samples. The average compliance rate was 76.0%, 83.2% in Urban area and 71.9% in Rural. Iodine content of salt less then 20 mg/kg at the rural households was 20.4%, and 9.9% in urban.

Female↗

[Hygienic status of deep fried oils in 1998 and the contrast with 10 years ago].

The hygienic status and influence factors of deep fried oil were studied. The samples from 29 individual producers, 38 state-operated or cooperated restaurants and 30 joint-invested enterprises were collected to investigate the hygienic condition on the spot, and to analyze the acid value(AV), carbonyl value (COV) and polar compound(PC) with national standard methods(GB). The data showed that the degree of rancidity of the deep fried oils varied with different types of oil, refinement of oil and the kind of fried food. Comparing with the results obtained a decade ago, COV was decreased while PC was increased. It was suggested: (1) to specify some types of oil for flying foods; (2) to develop some quick methods for checking fried oil; (3) to improve the method for detecting PC for solid oil at ordinary (indoor) temperature; (4) to study the quality and safety of fried foods prepared by solid oils.

Acids↗

[A study on the chemical components of essential oil of oak moss concrete by gas chromatography/mass spectrometry].

The essential oil of oak moss concrete was extracted by volatile oil content equipment. The chemical compositions and their relative contents were analyzed by GC and GC/MS. A Supelco-5 fused silica capillary column (30 m x 0.32 mm i.d.; 0.25 micron thickness) and a flame ionization detector (FID) were employed in GC analysis. The temperature program included temperature increase of 4 degrees C/min from 50 degrees C to 250 degrees C, and a 10 min isothermal period at 250 degrees C. Mass spectra were obtained by electron impact at 70 eV and a source temperature of 170 degrees C. Twenty-four volatile compounds of oak mass concrete were identified, which comprised more than 83% of volatile fraction. The major components were diethyl phthalate, alpha-terpineol, cedrane and linalool.

Acyclic Monoterpenes↗

Decay of activated Bacillus subtilis pho response regulator, PhoP approximately P, involves the PhoR approximately P intermediate.

PhoR of Bacillus subtilis is a histidine sensor-kinase belonging to the family of two-component signal transduction systems. PhoR is responsible for processing the phosphate-starvation signal and providing phosphate input to regulate the level of phosphorylated response regulator, PhoP, which activates/represses Pho regulon gene transcription. The catalytic domain of PhoR is sufficient for the low-phosphate inducible expression of Pho regulon genes since removing the N-terminal membrane-associated domain did not alter the kinetics of Pho induction, albeit the total level of induction was decreased (1). In this study we showed that the complete B. subtilis PhoR protein produced in Escherichia coli can be reverse phosphorylated by PhoP-phosphate. We also used a C-terminal fragment of the PhoR protein, PhoR, to demonstrate that the phosphoryl group on phospho-PhoP was transferred back to PhoR in the reverse phosphorylation reaction or released as inorganic phosphate to the reaction mixture. The reverse phosphorylation of the PhoR protein likely occurs at the same histidine residue (His360) that is utilized for the autokinase reaction by the same protein. In the presence of ADP, the phosphoryl group is further transferred to ADP to form ATP. While the autokinase reaction, the forward phosphotransfer reaction from PhoR approximately P to PhoP, and the release of inorganic phosphate from PhoP approximately P in the presence of PhoR require Mg(2+), the reverse phosphotransfer from PhoP approximately P to PhoR does not. These results indicate that the energy levels of the phosphoryl groups on PhoP and PhoR are very similar. The reversible autokinase reaction and/or the reversible phosphotransfer reaction between PhoR approximately P and PhoP may have a role in PhoP approximately P decay thus influencing the PhoP approximately P concentration in the cell.

Adenosine Triphosphate↗

Inhibitory effect of the kinase inhibitor chelerythrine on acetylcholine-induced current in PC12 cells.

In order to analyze the effect of protein kinase C(PKC) on nicotinic acetylcholine receptor in pheochromocytoma (PC12) cells by the whole-cell clamp technique, chelerythrine, a well-known inhibitor of PKC, was used to investigate the influence of PKC on acetylcholine (ACh)-induced current. When cells were preincubated with chelerythrine (0.1-10 microM) for 5 min, an inhibitory effect of chelerythrine on the peak of ACh-induced current was found. This effect was concentration-dependent, voltage-independent, and time-dependent within 1-6 min and reversible. However, intracellular dialysis with 0.1-5 microM PKCI 19-31, a specific pseudosubstrate PKC inhibitor, did not affect the inhibitory effect of chelerythrine. These results suggest that chelerythrine has an inhibitory effect on ACh-induced current in PC12 cells and that this effect is independent of its inhibition on PKC, may represent a new pharmacological effect of chelerythrine, and is mediated by an alternative mechanism.

Acetylcholine↗

Immunosuppressant PG490 (triptolide) inhibits T-cell interleukin-2 expression at the level of purine-box/nuclear factor of activated T-cells and NF-kappaB transcriptional activation.

PG490 (triptolide) is a diterpene triepoxide with potent immunosuppressive and antiinflammatory properties. PG490 inhibits interleukin(IL)-2 expression by normal human peripheral blood lymphocytes stimulated with phorbol 12-myristate 13-acetate (PMA) and antibody to CD3 (IC50 of 10 ng/ml), and with PMA and ionomycin (Iono, IC50 of 40 ng/ml). In Jurkat T-cells, PG490 inhibits PMA/Iono-stimulated IL-2 transcription. PG490 inhibits the induction of DNA binding activity at the purine-box/antigen receptor response element (ARRE)/nuclear factor of activated T-cells (NF-AT) target sequence but not at the NF-kappaB site. PG490 can completely inhibit transcriptional activation at the purine-box/ARRE/NF-AT and NF-kappaB target DNA sequences triggered by all stimuli examined (PMA, PMA/Iono, tumor necrosis factor-alpha). PG490 also inhibits PMA-stimulated activation of a chimeric transcription factor in which the C-terminal TA1 transactivation domain of NF-kappaB p65 is fused to the DNA binding domain of GAL4. In 16HBE human bronchial epithelial cells, IL-8 expression is regulated predominantly by NF-kappaB, and PG490 but not cyclosporin A can completely inhibit expression of IL-8. The mechanism of PG490 inhibition of cytokine gene expression differs from cyclosporin A and involves nuclear inhibition of transcriptional activation of NF-kappaB and the purine-box regulator operating at the ARRE/NF-AT site at a step after specific DNA binding.

Binding Sites↗

Identification of highly selective inhibitors of collagenase-1 from combinatorial libraries of diketopiperazines.

Thiol-containing diketopiperazines have been recently identified as novel heterocyclic inhibitors of matrix metalloproteinase (MMPs). The compounds described had similar activities against the MMPs collagenase-1 and gelatinase-B. An inhibitor that showed greater than 10-fold selectivity for collagenase-1 over gelatinase-B was desired. Previously published work with peptidyl hydroxamates and thiols indicated that while preparing gelatinase selective inhibitors was straightforward, there was not an obvious route to selective inhibitors of collagenase-1. Combinatorial libraries were prepared and evaluated for their ability to inhibit collagenase-1 and gelatinase-B substrate hydrolysis. A method for estimating the IC50 values of compounds generated by high-throughput parallel synthesis aided in the identification of compounds with the desired properties. We have found that thiol diketopiperazines derived from nitrophenylalanine are both potent and selective inhibitors of collagenase-1. In addition, we have demonstrated that combinatorial chemistry can be utilized to identify molecules with a desired selectivity profile without access to the traditional tools of rational drug design.

Drug Design↗