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Biomedical subjects

J Cai

Publications and source records attributed to J Cai.

At least 235 records · Page 13Linked to original sources
PubMed1996

Phylogenetic relationships among members of the ascomycetous yeast genera Brettanomyces, Debaryomyces, Dekkera, and Kluyveromyces deduced by small-subunit rRNA gene sequences.

A molecular systematic investigation of members of the ascomycetous yeast genera Brettanomyces, Debaryomyces, Dekkera, and Kluyveromyces was performed by using 18S rRNA gene sequence analysis. Our comparative sequence analysis revealed that Brettanomyces anomalus and Brettanomyces bruxellensis were closely related to one another and also to their teleomorphs, Dekkera anomala and Dekkera bruxellensis, respectively. Together with Dekkera custersiana and Dekkera naardenensis, these four species formed a stable and distinct phylogenetic group. The three representative species of the genus Debaryomyces examined (viz., Debaryomyces castellii, Debaryomyces hansenii, and Debaryomyces udenii) were found to be genealogically highly related to each other and exhibited a specific phylogenetic affinity (level of sequence similarity, approximately 99.2%) with Candida guilliermondii (teleomorph, Pichia guilliermondii). Debaryomyces species and C. guilliermondii formed a distinct phylogenetic group, which displayed a significant association with a phylogenetically coherent cluster encompassing Lodderomyces elongisporus, Candida albicans, and four other Candida species. In contrast to the situation with the genera Brettanomyces and Debaryomyces, the genus Kluyveromyces displayed very marked phylogenetic heterogeneity. Kluyveromyces polysporus, the type species of the genus Kluyveromyces, and six other Kluyveromyces species (viz., Kluyveromyces africanus, Kluyveromyces delphensis, Kluyveromyces lodderae, Kluyveromyces thermotolerans, Kluyveromyces waltii, and Kluyveromyces yarrowii) were phylogenetically intermixed with species of the genera Zygosaccharomyces, Saccharomyces, and Torulaspora. In contrast, Kluyveromyces aestuarii, Kluyveromyces dobzhanskii, Kluyveromyces lactis, Kluyveromyces wickerhamii, and three Kluyveromyces marxianus varieties, along with their anamorph, Candida kefyr, formed a highly stable monophyletic group worthy of separate generic status. Kluyveromyces blattae and Kluyveromyces phaffii formed two distinct phylogenetic lines that did not exhibit particularly close affinity with each other or other ascomycetous yeast genera. Our phylogenetic findings are discussed in the context of the results of other genotypic and phenotypic studies.

Ascomycota↗
PubMed1996

Alignment of multi-segmented anatomical features from radiation therapy images by using least square fitting.

A least square fitting algorithm for alignment of multi-open-curved segments and point pairs of anatomical features obtained from both portal images and simulation radiographs has been developed for patient position verification in radiation therapy. A coordinate system associated with each curved segment pair is constructed so that the discrepancies of each segment pair can be obtained easily. The algorithm allows users to select not only multiple curve pairs but also individual point pairs on the important anatomic landmarks. The misregistration is measured by the sum of the position deviation of individual point pairs and ordinate discrepancies of all segment pairs from their corresponding coordinate systems. A mathematical minimization method is applied to seek an optimal transformation for matching of all segment and/or point pairs involved. The reliability of the algorithm has been tested with both phantom and clinical images. The test results indicate that the typical errors are less than 1 mm and 1 degrees in translation and rotation, respectively.

Algorithms↗
PubMed1996

Transcriptional regulation in the obligate intracytoplasmic bacterium Rickettsia prowazekii.

Transcriptional regulation was demonstrated in Rickettsia prowazekii, an obligate intracytoplasmic bacterium. The level of citrate synthase (gltA) mRNA II, from promoter P2, was greater in the total RNA isolated from heavily infected L929 cells than in moderately infected L929 cells; conversely, the level of ATP/ADP translocase (tlc) mRNA was greater in moderately infected cells. The level of gltA mRNA I, from promoter P1, did not change under these conditions. The chemical half-lives of gltA mRNA II and tlc mRNA under these conditions were very similar.

Animals↗
PubMed1996

Expression of the Escherichia coli chromosomal ars operon.

A chromosomally located operon (ars) of Escherichia coli has been previously shown to be functional in arsenic detoxification. DNA sequencing revealed three open reading frames homologous to the arsR, arsB, and arsC open reading frames of plasmid-based arsenic resistance operons isolated from both E. coli and staphylococcal species. To examine the outline of transcriptional regulation of the chromosomal ars operon, several transcriptional fusions, using the luciferase-encoding luxAB genes of Vibrio harveyi, were constructed. Measurement of the expression of these gene fusions demonstrated that the operon was rapidly induced by sodium arsenite and negatively regulated by the trans-acting arsR gene product. Northern blotting and primer extension analyses revealed that the chromosomal ars operon is most likely transcribed as a single mRNA of approximately 2100 nucleotides in length and processed into two smaller mRNA products in a manner similar to that found in the E. coli R773 plasmid-borne ars operon. However, transcription was found to initiate at a position that is relatively further upstream of the initiation codon of the arsR coding sequence than that determined for the E. coli R773 plasmid's ars operon.

Adenosine Triphosphatases↗
PubMed1996

Presence and severity of cerebral white matter lesions and hypertension, its treatment, and its control. The ARIC Study. Atherosclerosis Risk in Communities Study.

BACKGROUND AND PURPOSE: White matter lesions (WML) may result from cerebral hypoperfusion or ischemia. We investigated the association of WML with blood pressure, hypertension, and its treatment and control. METHODS: A random sample of 1920 participants aged 55 to 72 years in the Atherosclerosis Risk in Communities Study (ARIC) was examined. Spin-density 1.5-T MRI scan images were coded from 0 for normal to 9 for most severe WML. Hypertension was defined as systolic or diastolic pressure > or = 140/90 mm Hg or use of antihypertensive medication. RESULTS: The percentages of persons with WML grades 0 through 2 and 3 through 9, respectively, were as follow: normotensive, 92.4% and 7.6%, versus all hypertensive subjects, 83% and 17% (P < .001); and treated controlled hypertensive, 86% and 14%, versus treated uncontrolled hypertensive subjects, 76% and 24% (P = .003). Multivariable adjusted odds ratios (95% confidence intervals) for WML grade > or = 3 relative to normotensive subjects was 2.34 (1.71 to 3.20) for all hypertensives, 1.99 (1.19 to 3.08) for untreated hypertensives, 1.94 (1.32 to 2.85) for treated controlled hypertensives, and 3.40 (2.30 to 5.03) for treated uncontrolled hypertensives. After additional adjustment for hypertension duration, treatment, and control status, the odds ratios (95% confidence intervals) for a 1 SD increase of systolic and diastolic blood pressure were 1.43 (1.11 to 1.85) and 1.16 (0.94 to 1.43), respectively. CONCLUSIONS: Hypertension is associated with increased odds of WML, and treated uncontrolled hypertensive subjects have greater odds of WML than those with treated controlled hypertension. The data suggest that the level of blood pressure, especially systolic blood pressure, is related to WML, additional to the effects of categorically defined hypertension and its treatment and control status.

Aged↗
PubMed1996

Redefining rate regulation in a competitive environment.

Neither rate regulation nor market competition alone is likely to contain health care spending in the long run. We need an approach to cost containment that can simultaneously address the major causes of rising health expenditures: higher prices, greater intensity, and new technologies. Whereas rate regulation and market competition have been viewed as alternative strategies, an innovative approach would include a rate-regulatory system that is compatible with an evolving competitive market. We discuss the Maryland hospital rate-setting system as an illustration of the compatibility of a regulatory approach within a competitive market. In addition, we consider the feasibility of expanding a hospital rate-setting system nationwide and to the nonhospital sectors.

Capitation Fee↗
PubMed1996

Can postmenopausal hormone replacement improve plasma lipids in women with diabetes? The Atherosclerosis Risk in Communities Study Investigators.

OBJECTIVE: to evaluate the association of postmenopausal hormone replacement with plasma lipids in diabetic women. RESEARCH DESIGN AND METHODS: Cross-sectional data from a multiracial population study were used to evaluate the relationship of hormone replacement status with plasma lipids in diabetic (n = 694) versus nondiabetic (n = 5,321) postmenopausal women. RESULTS: Although diabetic women who currently used hormone replacement had higher adjusted mean HDL cholesterol levels than those who did not (56.9 vs. 53.6 mg/dl), they had proportionately lower hormone-related increases in HDL, HDL2, and HDL3 cholesterol than did nondiabetic women (HDL cholesterol 64.9 [current users] vs. 55.7 mg/dl [those who never used hormones]). There was a trend toward greater triglyceride values with hormone replacement in diabetic women (156.6 [current users] vs. 125.4 mg/dl [those who never used hormones]) than in nondiabetic women (143.3 [current users] vs. 123.7 mg/dl [those who never used hormones]). LDL cholesterol and apolipoprotein B levels were lower and apolipoprotein A-I levels were higher with hormone replacement, to a similar degree in diabetic and nondiabetic women. CONCLUSIONS: Diabetic women appear to have a blunted response to the HDL-raising effects of estrogen and an exaggerated hypertriglyceridemic response. This may result in attenuated cardioprotection from postmenopausal hormone replacement therapy and potentially an increased risk of acute pancreatitis from hypertriglyceridemia. The risks and benefits of postmenopausal hormone replacement need to be carefully weighed in diabetic women.

Alcohol Drinking↗
PubMed1996

[The radiobiologic characteristics of DNA polymerase beta in hepatomas].

DNA polymerase beta activity, its content and gene transcription levels in SMMC-LTNM hepatoma were investigated, using 3H-TTP incorporation, immunocytochemistry and cytoplasmic dot hybridization, respectively. The relations between the biological properties of the enzyme and DNA repair synthesis induced by gamma-ray irradiation were also studied. It was found that DNA polymerase beta activity, its content and the amount of its mRNA were much higher in hepatoma than those in normal hepatocytes (P < 0.01). Following whole-body irradiation of the nude mouse bearing SMMC-LTNM with 2 Gy of gamma ray, the polymerase beta activity in hepatoma increased temporarily and the gene transcription of the enzyme seemed to be more active. DNA polymerase beta participated in DNA repair synthesis and this effect was different between hepatoma and hepatocyte because of the biological differences of DNA polymerase beta. The results presented here indicated that DNA polymerase beta could affect radiation damage and radiotherapy of cancer.

Animals↗
PubMed1996

Quantification of bovine neutrophil migration across mammary epithelium in vitro.

A microassay system was developed to quantify bovine neutrophil transepithelial migration in vitro. The bovine mammary epithelial cell line (MAC-T) formed a confluent monolayer that served as a biologically meaningful barrier for neutrophil migration. Neutrophils added into the upper compartment of an inverted monolayer were driven to migrate across the epithelium from a basal-to-apical direction by the addition of zymosan activated serum (ZAS) into the lower compartment. The numbers of migrated neutrophils were determined by assaying the neutrophil azurophilic granule marker, myeloperoxidase. Results showed that ZAS stimulated neutrophil migration across the epithelium in a time-and dose-dependent manner. In the presence of 5% ZAS and 2 x 10(6) neutrophils, approximately 2.4 x 10(5) neutrophils migrated across the epithelium in 120 min. The procedures we have developed in this study provide a simple precisely controlled system to investigate the normal dynamics of bovine neutrophil transepithelial migration and a means to detect and study impaired neutrophil migration.

Animals↗
PubMed1996

[Inferior mesocaval shunt].

The results of inferior mesenteric vein-inferior vena cava shunt coupled with splenectomy and gastroesophageal devascularization in 16 patients with cirrhotic portal hypertention were reviewed. The mean diameter of the shunt stoma was 6.46 +/- 0.78 mm, and the portal pressure decreased from 4.25 +/- 0.54 kPa to 3.39 +/- 0.41 kPa. Variceal bleeding stopped in all 16 patients with no severe postoperative complications. This procedure should preserve satisfactory portal perfusion to the liver, and technically is easier than other shunt procedures.

Adult↗
PubMed1995

The citrate synthase-encoding gene of Rickettsia prowazekii is controlled by two promoters.

The transcripts of the citrate synthase-encoding gene (gltA) in Rickettsia prowazekii (Rp), an obligate intracellular parasitic bacterium, were analyzed by RNase protection (RP), primer extension (PE) and in vitro transcription assays. Analysis of the 5' end of the gltA mRNA by RP and PE assays revealed that there were two gltA mRNAs with the 5' ends located at 16 bp and 307 bp upstream from the gltA coding region. Since these two mRNAs might represent two species of mRNA transcribed from two different promoters or a single transcript that was processed to give two mRNAs, an in vitro transcription analysis with purified Rp RNA polymerase (RNAP) was performed to distinguish these two possibilities. Purified Rp RNAP catalyzed the formation of two transcripts initiated from the same nucleotides indicated by RP and PE. Sequence analysis identified Escherichia coli (Ec) promoter-like sequences immediately upstream from both transcription start points (tsp). The first promoter (promoter P1) had the core sequence TTCTAA-N17-TATACT, was 6 bp upstream from the tsp (base A) and was centered at 37 bp upstream from the coding region. The second promoter (promoter P2) had the core sequence ATGAAA-N17-TAAAGT, was 7 bp upstream from the tsp (base T) and was centered at 329 bp upstream from the coding region. This is the first demonstration of multiple promoters in this obligate intracellular parasite which has implications concerning transcriptional regulation.

Amino Acid Sequence↗
PubMed1995

Chiral separation and detection of terbutaline and ephedrine by capillary electrophoresis coupled with ion spray mass spectrometry.

The enantiomers of both terbutaline and ephedrine were separated by capillary electrophoresis using electrolyte solutions of heptakis(2,6-di-O-methyl)-beta-cyclodextrin in low pH buffers. The analytes were detected by ion spray mass spectrometry using selected ion monitoring or by selected reaction monitoring in the positive ion mode. Both the free drug enantiomers and the noncovalent enantiomer-cyclodextrin inclusion complexes for terbutaline can be detected simultaneously using this method. The feasibility of using CE/MS for chiral purity determination is demonstrated. In addition, a comparison of UV detection versus mass spectrometry detection for a spiked urine sample is included to demonstrate the selectivity and sensitivity advantages of the mass spectrometer as a CE detector.

Adrenergic beta-Agonists↗
PubMed1995

Synthesis and biological properties of water-soluble p-boronophenylalanine derivatives. Relationship between water solubility, cytotoxicity, and cellular uptake.

Water-soluble p-boronophenylalanine (BPA) derivatives having cascade polyols, the monohydroxy derivative BPA(OH) (4), the dihydroxy analogue BPA(OH)2 (5), and the tetrahydroxy analogue BPA(OH)4 (6), were synthesized in order to elucidate a relationship between the molecular structures and the cellular uptake. Biological properties of these compounds in addition to BPA (1) itself were investigated. Water solubility increased in the order of BPA < BPA(OH) < or = BPA(OH)2 > BPA(OH)4. Cytotoxicity to B-16 melanoma and TIG hybrobrast cells decreased in the order of BPA >> BPA(OH) > or = BPA(OH)2 > BPA(OH)4. The cellular uptake by both B-16 and TIG cells decreased in the order of BPA > BPA(OH) > or = BPA(OH)2 > BPA(OH)4, whereas the uptake ratio of B-16/TIG increased in the order of BPA < BPA(OH) < or = BPA(OH)2 < BPA(OH)4. The latter ratio indicates the selectivity on the uptake by a cancer to normal cell.

Antineoplastic Agents↗
PubMed1995

Effects of interleukin-1 and interleukin-1 receptor antagonist in AIDS-Kaposi's sarcoma.

Kaposi's sarcoma (KS) is the most common tumor seen in patients with HIV-1 infection. HIV-1 may induce KS directly through viral protein(s) or indirectly through regulation of cytokines such as IL-1 and IL-6. We have shown that AIDS-KS spindle cells express IL-1 beta and that IL-1ra inhibits KS-spindle cell growth. IL-1ra had little effect on human umbilical vein endothelial cells (HUVEC), human aortic smooth muscle cells (HASM), and human foreskin fibroblast (NN41). These findings support an autocrine activity for IL-1. Furthermore, exogenous IL-1 can enhance AIDS-KS cell growth, and this effect is completely blocked by IL-1ra. As expected, IL-1ra also blocks IL-1 mediated upregulation of IL-6 and bFGF, both of which are autocrine growth factors for KS. IL-1ra is thus a potential candidate for the treatment of AIDS-associated KS.

Acquired Immunodeficiency Syndrome↗