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Biomedical subjects

Y M Deng

Publications and source records attributed to Y M Deng.

18 recordsLinked to original sources
PubMed2001

Chemo- and radio-protective effects of polysaccharide of Spirulina platensis on hemopoietic system of mice and dogs.

AIM: To observe polysaccharide of Spirulina platensis (PSp) on the hematopoietic system of mouse and dogs which were damaged by injection of cyclophosphamide (CTX) and 60Co-gamma irradiation. METHODS: CTX and 60Co gamma ray were used to induce bone marrow damage, and the experimental animals were ig with different dose of PSp in vivo, after 12-d and 21-d administration, the whole blood cells and nucleated cells in bone marrow were measured, and the DNA in bone marrow were inspected by UV-spectrophotometer. RESULTS: CTX and 60Co-gamma irradiation induced hemopoietic system damage in mice and dogs, respectively. PSp 30, 60 mg/kg increased the level of the white cells in blood and nucleated cells and DNA in bone marrow in mice but had no effects on red cells and hemoglobins. PSp 12 mg/kg increased the level of red cells, white cells, and hemoglobins in blood and nucleated cells in bone marrow in dogs (P < 0.01), and the effects of PSp 60 mg/kg were better than that of berbamine hydrochloride 60 mg/kg. CONCLUSION: PSp has chemo-protective and radio-protective capability, and may be a potential adjunct to cancer therapy.

Animals↗
PubMed2000

Mapping dispersed repetitive loci using semi-specific PCR cloning and somatic cell hybrid mapping.

A simple and effective method based upon semi-specific PCR followed by cloning has been developed. Chromosomal mapping of the generated fragment on a somatic cell hybrid panel identifies the chromosomal position, and yields a unique sequence tag for the site. Using this method, the chromosomal location of one porcine endogenous retrovirus (PERV) was determined. The porcine genomic sequences were first amplified by PCR using a PERV-specific primer and a porcine short interspersed nuclear element (SINE)-specific primer. PCR products were cloned, and those sequences that contained PERV plus flanking regions were selected using a second round of PCR and cloning. Sequences flanking the PERV were determined and a PERV-B was physically mapped on porcine chromosome 17 using a somatic hybrid panel. The general utility of the method was subsequently demonstrated by locating PERVs in the genome of PERV infected human 293 cells. This method obviates the need for individual library construction or linker/adaptor ligation, and can be used to quickly locate individual sites of moderately repeated, dispersed DNA sequences in any genome.

Animals↗
PubMed2000

Transmission of porcine endogenous retroviruses in severe combined immunodeficient mice xenotransplanted with fetal porcine pancreatic cells.

BACKGROUND: Xenotransplantation using pig organs or tissues may alleviate the human donor organ shortage. However, one concern is the potential transmission of pig pathogens to humans, especially pig endogenous retroviruses (PERV), which infect human cell lines in vitro. In this report, the cross-species in vivo transmission of PERV by xenotransplantation was studied using a severe combined immunodeficient (SCID) mouse model. METHODS: Twenty-one SCID mice were transplanted with fetal pig pancreatic cells and left for periods from three to 41 weeks before being killed. DNA and RNA were extracted from liver, spleen, and brain of these mice, and examined for PERV using nested polymerase chain reaction (PCR) and reverse transcriptase-PCR. The pig mitochondrial cytochrome oxidase II subunit gene (COII) was also amplified to monitor the presence of pig cell microchimerism in xenotransplanted tissues, and a housekeeping gene was included to monitor the DNA quality and quantity. RESULTS: Examination of 39 DNA samples from tissues of the 21 xenografted mice identified two mouse tissues (M4-liver and M19-spleen) that were positive for PERV but negative for COII. A total of 23 (59%) of the mouse tissues were positive for both PERV and COII, 6 (16%) were negative for both, and 8 (20%) were positive for COII only. PCR and direct sequencing of the PCR products identified three PERV variants, which were different from the PERV sequence detected by PCR direct sequencing from the pig donor cells. CONCLUSIONS: The PERV+/COII- results from M4-liver and M19-spleen indicated the presence of PERV transmission from pig to mouse tissue. The PERV variants detected in the mouse tissues indicated that different PERVs were transmissible from the pig to mouse tissue during xenotransplantation. The negative reverse transcriptase-PCR results for PERV from three mouse samples including M4-liver and M19-spleen suggest there was no active PERV transcription in the mouse tissues, although this would need to be studied further.

Animals↗
PubMed2000

LldI, a plasmid-encoded type I restriction and modification system in Lactococcus lactis.

A plasmid-encoded type I restriction and modification (R-M) system, designated LldI, was identified in Lactococcus lactis biovar diacetylactis LD10-1. LldI consists of three genes encoding endonuclease, methylase and specificity subunits, respectively. RT-PCR analysis revealed that the three genes are co-transcribed as a polycistronic mRNA in L. lactis. The specificity subunit of LldI differs significantly in the target recognition domains from those of other type I R-M systems, suggesting that LldI confers a novel specificity in L. lactis.

Amino Acid Sequence↗
PubMed1999

Genetic organization and functional analysis of a novel phage abortive infection system, AbiL, from Lactococcus lactis.

A plasmid-encoded phage abortive infection mechanism (AbiL) was identified from Lactococcus lactis biovar. diacetylactis LD10-1. AbiL conferred complete resistance to the small isometric-headed phage phi 712 (936 species) and partial resistance to the prolate-headed phage phi c2 (c2 species) when introduced into L. lactis LM0230. However, AbiL was not effective against the small isometric-headed phage ul36 (P335 species). The AbiL determinant was sequenced and it consists of two open reading frames, abiLi and abiLii. Their encoded proteins did not share significant homology with any known proteins in the protein databases. Transcriptional analysis indicated that abiLi and abiLii are organized as a single operon. Deletion within abiLii abolished the phage resistance. The levels of four phi c2-specific transcripts, three within the early transcribed region and one within the late transcribed region, were examined by RT-PCR, no effect of AbiL on synthesis of these transcripts was detected, suggesting that AbiL may act at a point after the transcription of phi c2 in L. lactis.

Amino Acid Sequence↗
PubMed1998

Adjunctive orthodontic treatment of periodontally involved teeth: case reports.

Elongated and spaced incisors are common in patients suffering from severe periodontal disease. Intrusion and uprighting of incisors might be the logical solution for this problem. This article describes a team approach to treatment planning for adult patients with severe localized periodontitis accompanied by marginal bone loss and spacing and elongation of incisors. The treatment involves the combination of periodontal treatment, orthodontic intrusion, and prosthetic therapy. Controlled intrusion in two patients led to a decrease in the clinical crown length, better access for oral hygiene procedures, better gingival form, and a more suitable distribution of occlusal forces.

Adult↗
PubMed1997

A novel plasmid-encoded phage abortive infection system from Lactococcus lactis biovar. diacetylactis.

A 16-kb plasmid (pND859) was identified from Lactococcus lactis biovar. diacetylactis UK12922 which encodes phage resistance to the small isometric phage 712 when tested in L. lactis LM0230. The gene encoding phage abortive infection, designated abi-859, was localized on a 1.2-kb region which consists of an open reading frame (ORF) of 846 bp preceded by a potential ribosome-binding site and a putative promoter region. A helix-turn-helix region typical of DNA-binding motifs was identified near the N-terminal of the abi-859 product, suggesting a possible interaction with the phage DNA.

Amino Acid Sequence↗
PubMed1997

Genetic analysis of regions involved in replication and cadmium resistance of the plasmid pND302 from Lactococcus lactis.

The 8.8-kb Lactococcus lactis plasmid pND302 encodes resistance to cadmium (CdR). Regions of pND302 involved in replication and CdR were subcloned and sequenced. The replication region is localized on a 1.5-kb region and consists of an open reading frame (repB) preceded by a noncoding AT-rich sequence (ori) which is highly homologous to lactococcal theta-type replicons. The CdR determinant is localized on a 2.9-kb region and encodes putative proteins similar to the Cd(2+)-specific P-type efflux ATPase (CadA) and the transcriptional regulatory repressor (CadC) identified in Staphylococcus aureus, Bacillus firmus, and Listeria monocytogenes. Similar CdR determinants were also detected by PCR in other CdR plasmids isolated from different L. lactis strains.

Adenosine Triphosphatases↗
PubMed1996

The effect of demineralized bone matrix on the healing of intramembranous bone grafts in rabbit skull defects.

A clinical dilemma exists regarding the type of bone that should be used to replace diseased or traumatized osseous tissue. Oral, plastic, and orthopedic surgeons normally implant viable mineralized endochondral (EC) autografts or demineralized EC allografts. A few clinicians have recognized the disadvantages of using EC bone in craniofacial surgery and advocated the replacement of intramembranous (IM) bone with healthy IM bone. However, controversy and uncertainty surround our understanding of these matrices to induce bone formation. Recent studies have advocated the use of other materials with osteoinductive properties, such as demineralized bone matrix (DBM). The proposed delivery system used in this study included IM bone grafts, DBM, and fixation of the IM bone graft. The purpose of this work was to gain further insights into the mechanism of healing of IM bone, in both the presence and the absence of DBM, and to compare the healing of IM bone grafts with that of DBM alone. Critical-sized (10 x 5 mm), full-thickness bony defects in rabbit parietal bone, devoid of periosteum, were filled with IM bone graft (mandible) alone, demineralized cortical bone matrix (DBM) alone, or combined DBM-IM bone graft, or were left unfilled. Histologic changes were examined 14 days later. The IM bone graft healed through IM ossification with no intermediate cartilage stage. DBM and composite DBM-IM healed through an EC ossification with an intermediate cartilage stage. It is hypothesized that the role of the IM graft is to induce neovascularization into the defect site, and that the undifferentiated mesenchymal cells in the perivascular region of the new blood vessels are induced by the bone morphogenetic protein(s) in the DBM into bone-forming cells.

Animals↗
PubMed1996

Treatment of a palatally impacted canine accompanied by root resorption of incisors: a case report.

This case report describes a simplified orthodontic system for the management of a palatally impacted canine accompanied by root resorption of incisors. The anchorage for this system is the transpalatal arch and a heavy buccal segment arch wire with two loops soldered to stainless steel bands. This type of stationary anchorage provides stability by uniting both molars across the palatal vault and thus avoids the need for bonding of adjacent mobile teeth. With this system an impacted canine can be extruded, moved distally, jumped over the occlusion, and derotated. The efficiency of this appliance makes it a safe method for moving teeth through simple manipulation and with minimal esthetic inconvenience.

Adolescent↗
PubMed1995

Prevalence of temporomandibular joint dysfunction (TMJD) in Chinese children and adolescents. A cross-sectional epidemiological study.

The aim of this study was to investigate the prevalence of temporomandibular joint dysfunction (TMJD) in Chinese children and adolescents, and the relationship between TMJD and type of occlusion. The sample consisted of 3105 Chinese children, 3-19 years of age, divided into four groups by the stage of dental maturation. The prevalence of TMJD for the entir group was 17.9 per cent and there was no significant sex difference. TMJD increased in the mixed and early permanent dentitions, but decreased in the permanent and deciduous dentitions. In the subjects with TMJD, the most common sign was sound (87.7 per cent), followed by abnormal jaw movement (23.6 per cent), but pain was registered in 0.6 per cent only. A single sign was registered in 88.5 per cent, a combination of sound and abnormal jaw movement in 11.0 per cent, and combinations of other signs in less than 1.0 per cent. Sound as a single sign increased with the specific stages of dental development (P < 0.001).

Adolescent↗
PubMed1994

[Occlusal contact changes before and after orthodontic treatment of TMJD patients in children and adolescents].

Occlusal contacts were examined in a sample of 32.8-17 Years old TMJD patients before and after orthodontic treatment. Computer-aided video system was applied to the silicone occlusal record obtained in the intercuspid position to assess the quantitative and qualitative changes of occlusal contacts. The results showed that after orthodontic treatment, the mean number of contacts on anterior teeth decreased, the mean area per contact decreased, the location of contacts on centric stops increased and the contacts on inclined plane were decreased. All of these indicated that the occlusal stability increased after orthodontic treatment.

Adolescent↗
PubMed1988

Laser-induced multiphoton fluorescence of hemoglobin.

Hemoglobin (Hb) and other samples were irradiated by the 1064 nm nanosecond pulses of an Nd:YAG laser. At room temperature, we observed two red fluorescence bands, which resulted from the absorption of two 1064 nm photons in Hb, and measured the fluorescence emission spectra in the red spectral region for Hb and hematoporphyrin derivative. A red shift of the wavelength and a mirror image in the intensity of fluorescence emissions by two-photon excitation were observed. It is shown that the fluorescence of Hb originates from the heme group. In addition, we also observed fluorescence emission at 392 nm for Hb, which may be from its tryptophan groups.

Fluorescence↗
PubMed1987

Sister chromatid exchanges in lymphocytes of early cases of nasopharyngeal carcinoma and in 100 healthy subjects.

Sister chromatid exchange rate was studied in 12 early diagnosed cases of nasopharyngeal carcinoma and in their paired controls. Exchange frequencies were also analyzed in 100 healthy subjects distributed in four regions of Hunan Province and correlated to nationality, age and sex. The incidence of sister chromatid exchange was significantly higher in the cancer patients than in the normal controls. No correlation was found between the frequency of sister chromatid exchange and region, nationality, age or sex.

Adult↗
PubMed1987

Fluorescence of proteins induced by two-photon absorption.

At room temperature, the UV fluorescence of trypsin, thyroglobulin, hemoglobin and albumin are observed; these molecules undergo two-photon absorption when they are excited with the radiation of a frequency-duplicated Q-switched Nd:YAG laser. It is shown that the fluorescence of these proteins comes from the tryptophan residues and that it has a red shift of about 20 nm relative to the one-photon fluorescence. We suggest that the weak emission from tyrosine arises from the forbidden two-photon transition. The influence of concentration on the fluorescence of hemoglobin and tryptophan is discussed. The two-photon absorption cross-sections are estimated.

Hemoglobins↗