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Biomedical subjects

J Cai

Publications and source records attributed to J Cai.

At least 271 records · Page 15Linked to original sources
PubMed1994

Phylogenetic analysis of species of the meso-diaminopimelic acid-containing genera Brevibacterium and Dermabacter.

16S rRNA gene sequencing studies were performed on Dermabacter hominis and four meso-diaminopimelic acid-containing species of the genus Brevibacterium. Phylogenetic analysis revealed a close association between Dermabacter hominis and representatives of the lysine-containing genera Arthrobacter, Micrococcus, and Renibacterium. By contrast, the genus Brevibacterium formed a distinct line of descent within the high-guanine-plus-cytosine-containing actinomycetes, displaying no specific affinity with any other organism examined.

Actinomycetales↗
PubMed1994

The phylogeny of the genus Clostridium: proposal of five new genera and eleven new species combinations.

The 16S rRNA gene sequences of 34 named and unnamed clostridial strains were determined by PCR direct sequencing and were compared with more than 80 previously determined clostridial sequences and the previously published sequences of representative species of other low- G + C-content gram-positive genera, thereby providing an almost complete picture of the genealogical interrelationships of the clostridia. The results of our phylogenetic analysis corroborate and extend previous findings in showing that the genus Clostridium is extremely heterogeneous, with many species phylogenetically intermixed with other spore-forming and non-spore-forming genera. The genus Clostridium is clearly in need of major revision, and the rRNA structures defined in this and previous studies may provide a sound basis for future taxonomic restructuring. The problems and different possibilities for restructuring are discussed in light of the phenotypic and phylogenetic data, and a possible hierarchical structure for the clostridia and their close relatives is presented. On the basis of phenotypic criteria and the results of phylogenetic analyses the following five new genera and 11 new combinations are proposed: Caloramator gen. nov., with Caloramator fervidus comb. nov.; Filifactor gen. nov., with Filifactor villosus comb. nov.; Moorella gen. nov., with Moorella thermoacetica comb. nov. and Moorella thermoautotrophica comb. nov.; Oxobacter gen. nov., with Oxobacter pfennigii comb. nov.; Oxalophagus gen. nov., with Oxalophagus oxalicus comb. nov.; Eubacterium barkeri comb. nov.; Paenibacillus durum comb. nov.; Thermoanaerobacter kivui comb. nov.; Thermoanaerobacter thermocopriae comb. nov.; and Thermoanerobacterium thermosaccharolyticum comb. nov.

Base Sequence↗
PubMed1994

[Heel reconstruction by the composite island flap of the lower leg].

From 1987, 6 to 1992, 6 cases of heel defect were repaired successfully by reverse transfer of the composite island flap from the lateral lower leg. The flap, pedicled with peroneal vessels, consisted of skin, subcutaneous tissue, fibula and adjacent muscles. The contour and function were satisfactory.

Adolescent↗
PubMed1994

Oncostatin-M is an autocrine growth factor in Kaposi's sarcoma.

Oncostatin-M is a cytokine produced by macrophages and activated T lymphocytes that has recently been shown to be a mitogen for AIDS-related Kaposi's sarcoma (KS)-derived spindle cells. The significance of oncostatin-M production in AIDS-related KS in vivo, however, remains unknown. In this study we wanted to determine whether oncostatin-M is expressed in vivo in patients with HIV-I-related KS, define the cell types that express this cytokine, and compared with the control tissues from HIV-I-negative individuals. A second objective of our study was to define the expression of oncostatin-M in AIDS-KS-derived spindle cell isolates cultured in vitro and to determine whether oncostatin-M is an autocrine growth factor for these KS cells. We have determined that oncostatin-M is not expressed in any of the several organs examined in control cases, whereas the tumor tissue obtained from the skin biopsies of HIV-I-infected cases with KS displayed oncostatin-M expression in the spindle cell components of the tumor, as well as the cells lining the vascular structures, smooth muscle cells lining the eccrine sweat glands, and the epidermal layers of the skin. Furthermore, uninvolved skin of patients with HIV-related KS express oncostatin-M in the cells lining normal vessels. The mRNA polymerase chain reaction analysis confirmed findings in the primary tissues and showed expression in all of the AIDS-KS-derived spindle cell isolates examined. We have also shown with the use of oncostatin-M-specific antisense oligodeoxynucleotides that KS cell proliferation is inhibited, which correlated with a more precipitous decline in the production of interleukin-6 by these cells. We conclude that oncostatin-M is only expressed in the skin and KS tumor of HIV-I-infected individuals. Furthermore, we provide evidence that oncostatin-M is an autocrine growth factor for KS.

Acquired Immunodeficiency Syndrome↗
PubMed1993

A study on the effect of lesions of area 7 of the parietal cortex on the short-term visual spatial memory of rhesus monkeys (Macaca mulatta).

This research is focused on the contribution of area 7 to the short-term visual spatial memory. Three rhesus monkeys (Macaca mulatta) were trained in the direct delayed response task in which 5 delay intervals were used in each session. When each monkey reached the criterion of 90% correct responses in 5 successive sessions, two monkeys underwent a surgery while the other one received a sham operation as a control. In the first stage of the surgery, bilateral areas 7a, 7b and 7ip of the parietal cortex of two monkeys were precisely lesioned. After 7 days of recuperation, the monkeys were required to do the same task. The average percentage of correct responses in the lesioned animals decreased from 94.7% to 89.3% and 93.3% to 82.0% respectively (no significance, P > 0.05, n = 2). In addition, the monkeys' complex movements were mildly impaired. The lesioned monkeys were found to have difficulty picking up food from the wells. In the second stage, bilateral area 7m was lesioned. In the 5 postoperative sessions, the average percentage of correct responses in one monkey, with a relatively precise 7m lesion, decreased from 94.7% to 92.2% (no significance, P > 0.05), while the other monkey, with widely spread necrosis of lateral parietal cortex, showed an obvious decline in performance, but still over the chance level. After 240 trials this monkey reattained the normal criterion.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Replantation of a multiple digit and circular palm amputation: a case report.

A case of successful replantation of multiple digits and circular palm amputation caused by an industrial punch force is reported. The two-level amputation was reconstructed by first replanting the severed fingers to the palmar segment and then connecting the palm segment to the hand stump. An arterial crisis was treated with urokinase, and postoperative functional recovery is described.

Adult↗
PubMed1993

AIDS-associated Kaposi's sarcoma pathogenesis, clinical features, and treatment.

Kaposi's sarcoma is the most common tumor associated with HIV-1 infection. Kaposi's sarcoma is seen most frequently among homosexual or bisexual men, the reasons for which are unknown. Culture of Kaposi's sarcoma spindle cells has been very useful to study various biologic features of the tumor and to develop novel drug therapy. Treatment of AIDS-associated Kaposi's sarcoma is planned based on tumor burden, immunologic status of the patient, and bone marrow rescue. All treatment types at present only provide palliation, whereas efforts to find more effective therapy and possibly preventive therapy are in progress.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Aeromonas enteropelogenes and Aeromonas ichthiosmia are identical to Aeromonas trota and Aeromonas veronii, respectively, as revealed by small-subunit rRNA sequence analysis.

The 16S rRNA gene sequences of the type strains of Aeromonas enteropelogenes and Aeromonas ichthiosmia were determined by polymerase chain reaction direct sequencing in order to clarify their interrelationships with other aeromonad species. On the basis of 16S rRNA gene sequence analysis, A. enteropelogenes and A. ichthiosmia were found to be identical to Aeromonas trota and Aeromonas veronii, respectively.

Aeromonas↗
PubMed1993

Identification of tlc and gltA mRNAs and determination of in situ RNA half-life in Rickettsia prowazekii.

RNAs of Rickettsia prowazekii, an obligate intracytoplasmic bacterium, have been identified and analyzed by an RNase protection assay. Total RNA, a mixture of host cell RNA and rickettsial RNA, was isolated from rickettsia-infected mouse L929 cells by the hot-phenol method. After hybridization with specific antisense RNA probes and digestion with RNase, the protected products were analyzed by electrophoresis and autoradiography. The results show that there is only one mRNA species for the ATP/ADP translocase gene (tlc) but two mRNA species for the citrate synthase gene (gltA). RNA half-lives were determined by measuring the RNA remaining after addition of rifampin. The half-lives of tlc mRNA, gltA mRNA I, and gltA mRNA II in R. prowazekii are 8.4 +/- 0.6, 12.3 +/- 1.3, and 20.5 +/- 1.8 min, respectively. However, the half-lives of tlc mRNA and gltA mRNA I in recombinant Escherichia coli strains are 2.9 +/- 0.1 and 1.4 +/- 0.1 min, respectively. The 16S rRNA in R. prowazekii was also examined and shown to be stable.

Animals↗
PubMed1993

Possibility of signal transduction through microfilaments below the membrane following ligand-receptor interaction.

In this paper, we describe the changes of microfilament assembly and 3H-TdR incorporation in mouse ascites liver cancer cells under the action of concanavalin A (ConA) and laminin (LN). We have also studied the variation of 3H-TdR incorporation induced by destroying microfilaments with cytochalasin B (CB) following ConA and LN binding with their membrane receptors. It was found that ConA and LN interactions with their membrane receptors could induce the assembly of microfilaments below the membrane and promote DNA synthesis in these cells, but this effect was inhibited when microfilaments were destroyed by CB treatment. These results suggest that microfilaments might play a role in transferring signals from the membrane to the nucleus.

Actin Cytoskeleton↗
PubMed1993

[Molecular study of the mechanism of chromosomal translocation (15;17) in acute promyelocytic leukemia (APL)].

Molecular studies of chromosomal translocation (15;17) in acute promyelocytic leukemia (APL) have shown that retinoic acid receptor A (RARA) gene on chromosome 17 is juxtaposed to the PML gene on chromosome 15. This results in a PML-RARA chimeric gene. Our work has demonstrated that the PML breakpoints in APL patients are clustered in two limited regions, PML-bcr1 and PML-bcr2, separated from each other by about 10 kb. DNA sequence of PML-bcr1 and primary structure of the junctional region of reciprocal chromosomal translocation in a patient have been determined in this paper. Compared to those of two previously reported cases abroad, we found that the breakpoint may be situated in the topoisomerase II cleavage site. A working model has been proposed for the mechanism of DNA illegitimate recombination in t (15;17).

Base Sequence↗
PubMed1992

Extensive and selective mutation of a rearranged VH5 gene in human B cell chronic lymphocytic leukemia.

B cell chronic lymphocytic leukemia (CLL) is the malignant, monoclonal equivalent of a human CD5+ B cell. Previous studies have shown that the VH and VL genes rearranged and/or expressed in CLL have few and apparently random mutations. However, in this study, we have found that the rearranged VH251 gene, one of the three-membered VH5 family, has extensive and selective mutations in B-CLL cells. Somatic mutation at the nucleotide level is 6.03% in B-CLLs whereas the somatic mutation levels are much lower in CD5+ and CD5- cord B cells, adult peripheral blood B cells, and Epstein-Barr virus-transformed CD5+ B cell lines (0.45, 0.93, and 1.92%, respectively). Complementary determining region 1 (CDR1) mutation in CLLs is particularly prevalent, and interchanges in CDRs often lead to acquisition of charge. Analysis of somatic mutations and mutations to charged residues demonstrated that the mutations in CLLs are highly selected.

Adult↗
PubMed1992

Studies on the ribosomal RNA operons of Listeria monocytogenes.

A 23S rRNA gene of Listeria monocytogenes was cloned into pUC19 on a 6.2-kb Pst I fragment. Hybridisation studies demonstrated the presence of the 5S and partial 16S rRNA genes within the clone. The nucleotide sequence of the region encoding the 23S rRNA was found to be highly homologous with those of other low G + C Gram-positive bacteria. The 16S-23S intergenic spacer region was amplified using PCR technology and revealed two product sizes, the larger of which contained tRNA(Ala) and tRNA(Ileu) genes. Further tRNA genes were found downstream of the 5S rRNA gene.

Base Sequence↗
PubMed1992

PCR cloning and nucleotide sequence determination of the 18S rRNA genes and internal transcribed spacer 1 of the protozoan parasites Cryptosporidium parvum and Cryptosporidium muris.

The genes encoding 18S rRNA and internal transcribed spacer 1 (1TS1) of Cryptosporidium parvum and Cryptosporidium muris were amplified from oocysts by PCR utilizing primers complementary to conserved regions of the 5' end of 18S and 5.8S rRNA. PCR products were cloned and the complete nucleotide sequences of two clones of each Cryptosporidium species were determined. The 18S rRNA genes of C. parvum and C. muris showed more than 99% sequence identity.

Animals↗
PubMed1992

Analysis of VH251 gene mutation in chronic lymphocytic leukemia (CLL) and normal B-cell subsets.

B-cell chronic lymphocytic leukemia (CLL) is the malignant, monoclonal equivalent of a human CD5+ B cell. Previous studies have shown that the VH and VL genes rearranged and/or expressed in CLL have low and random mutations. In this study, however, we have found that the rearranged VH251 gene, one of the three-membered VH5 family, has extensive and selective mutations in B-CLL cells. Somatic mutation at the nucleotide level is 6.03%, and there is a high ratio of replacement to silent mutation in CDRs relative to FWRs. CDR1 mutation is particularly prevalent, and interchanges often lead to acquisition of charge. In VH251 rearranged in CD5+ and CD5- cord-blood B cells, adult peripheral-blood B cells and EBV-transformed CD5+ B-cell lines, the somatic mutation levels are much lower (0.45%, 0.93%, and 1.92%, respectively) with concomitantly lower replacement to silent ratios in CDRs relative to FWRs. The extensive and highly selective somatic mutation of VH251 used in CD5+ CLL cells strongly suggests that part of CLL is generated under the influence of antigen selection and stimulation.

B-Lymphocyte Subsets↗
PubMed1991

Plasma membrane appearance of phosphatidylethanolamine in stimulated macrophages.

Mouse peritoneal macrophages were labeled with [1-3H]ethanolamine, and the presence of radioactive [3H]phosphatidylethanolamine (PE) at the plasma membrane was monitored by reacting the cells with trinitrobenzene sulfonic acid (TNBS) under nonpenetrating conditions. Macrophages stimulated with either the calcium ionophore A23187 or zymosan demonstrated a larger proportion of radiolabeled PE in the plasma membrane than control, nonstimulated cells. In experiments in which macrophages were labeled with ethanolamine for increasing times, appearance of membrane 3[H]PE was stimulated as early as after 2 hr of labeling. Macrophages labeled for 24 hr, then stimulated and returned to fresh medium still reflected a higher amount of membrane 3[H]PE at 2 hr after the stimulation, suggesting stimulation results in long-term alterations in plasma membrane lipids. Protease-peptone-elicited macrophages, which are not stimulated by zymosan or ionophore, did not exhibit an increase in membrane 3[H]PE upon stimulation. The size of the TNBS-accessible radiolabeled PE pool increased proportionately with a second stimulation; however, a subsequent labeling of the cells with TNBS after brief warming increased the TNBS-accessible pool in control cells only. As shown in previous studies, macrophage stimulation resulted in an increased incorporation of lipid precursors into phospholipid. The mass of plasma membrane Tnp-PE relative to mass of PE was not increased in ionophore-treated macrophages in contrast to a small (approximately 22%) increase in zymosan-treated cells. These results are suggestive of alterations in lipid synthesis in stimulated macrophages and possible long-term changes in the structure and function of the plasma membrane of macrophages following stimulation.

Animals↗