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Biomedical subjects

A Li

Publications and source records attributed to A Li.

At least 109 records · Page 6Linked to original sources
PubMed2000

AtRAD1, a plant homologue of human and yeast nucleotide excision repair endonucleases, is involved in dark repair of UV damages and recombination.

Plants are unique in the obligatory nature of their exposure to sunlight and consequently to ultraviolet (UV) irradiation. However, our understanding of plant DNA repair processes lags far behind the current knowledge of repair mechanisms in microbes, yeast and mammals, especially concerning the universally conserved and versatile dark repair pathway called nucleotide excision repair (NER). Here we report the isolation and functional characterization of Arabidopsis thaliana AtRAD1, which encodes the plant homologue of Saccharomyces cerevisiae RAD1, Schizosaccharomyces pombe RAD16 and human XPF, endonucleolytic enzymes involved in DNA repair and recombination processes. Our results indicate that AtRAD1 is involved in the excision of UV-induced damages, and allow us to assign, for the first time in plants, the dark repair of such DNA lesions to NER. The low efficiency of this repair mechanism, coupled to the fact that AtRAD1 is ubiquitously expressed including tissues that are not accessible to UV light, suggests that plant NER has other roles. Possible 'UV-independent' functions of NER are discussed with respect to features that are particular to plants.

Amino Acid Sequence↗
PubMed2000

Corynebacterium pseudodiphtheriticum keratitis and conjunctivitis: a case report.

A case of keratitis and conjunctivitis in an 86-year-old man caused by Corynebacterium pseudodiphtheriticum is reported. Corynebacteria are uncommon causes of ocular surface infections. However, the presence of corneal and conjunctival epithelial defects in an immunocompromised patient can result in severe infection by a commensal organism such as C. pseudodiphtheriticum. The significance of a positive culture in these settings should not be overlooked.

Abscess↗
PubMed2000

Adhesive properties of human basal epidermal cells: an analysis of keratinocyte stem cells, transit amplifying cells, and postmitotic differentiating cells.

The basal layer of human epidermis is a heterogeneous population of proliferative and differentiating cells that can be divided into at least three functionally discrete compartments: keratinocyte stem cells, transit amplifying cells, and postmitotic differentiating cells. Basal cells adhere to the underlying basement membrane via integrins, and although decreased adhesion is a key event in epidermal differentiation, the specific role of particular integrins is poorly understood. We report here on the comparative expression and function of the beta1 versus alpha6beta4 integrins in keratinocyte stem cells, transit amplifying cells, and postmitotic differentiating cells of neonatal human foreskin epidermis. Adhesion assays demonstrate that both keratinocyte stem cells and transit amplifying cells comprise rapidly adhering cells that exhibit high levels of functional beta1 and alpha6beta4 integrins. Interestingly, a proportion of basal cells that have begun to differentiate in vivo within the basal layer as determined by their expression of the differentiation-specific markers K10 and involucrin also retain high levels of activated beta1 integrin, but downregulate alpha6beta4 expression selectively (termed alpha6dimbeta1bri). These cells also retain their adhesive capacity, indicating that induction of differentiation in vivo does not correlate with decreased beta1 integrin expression or function. We have previously reported on the use of alpha6 integrin in conjunction with a proliferation associated marker (10G7 ag) to separate keratinocyte stem cells (phenotype alpha6bri10G7dim) from other basal cells (Li et al. Proc Natl Acad Sci 95:3902-3907 1998). A comparison of the long-term proliferative potential of beta1bri10G7dim cells with alpha6bri10G7dim showed that selection of alpha6bri10G7dim allows the isolation of a purer fraction of keratinocyte stem cells.

Antigens, CD↗
PubMed2000

Control of photon beam dose profiles by localized transverse magnetic fields.

Unlike electron beams, scant attention has been paid in the literature to possible magnetic field effects on therapeutic photon beams. Generally, dose profiles are considered to be fully determined by beam shape, photon spectrum and the substances in the beam path. Here we show that small superconducting magnets can exercise potentially useful control over photon dose profiles. The magnet produces a locally strong transverse field with large gradients and is applied to the tissue surface below which the photon beam is passing. For one practical magnet design, our simulations, which use the EGS-4 Monte Carlo code modified to include magnetic field effects, show significant intensification and shielding effects. In water phantoms, the effects extend to 3-4 cm or more beyond the warm face of the cryostat and greater distances are achieved in phantoms simulating lung (density approximately 0.3). Advances in applying the concept and in superconducting materials and magnet design hold promise for extending these ranges.

Humans↗
PubMed2000

Radial carpal bone fractures in 15 dogs.

Between 1977 and 1992, 15 adult dogs were presented to the Universities of Bristol, Glasgow, Liverpool and London with fractures of the radial carpal bone which had occurred without a known episode of violent trauma. Eleven of the dogs were boxers and the other breeds affected were a Pharaoh hound, rottweiler, springer spaniel and a greyhound. The condition was bilateral in three cases. Eleven dogs were treated surgically by cast immobilisation (four cases), fragment removal (one case), lag screw fixation (three cases), pan-carpal arthrodesis (one case) and lag screw reduction followed by pan-carpal arthrodesis (two cases). The remaining four dogs were treated conservatively with rest and tactical use of non-steroidal anti-inflammatory drugs. Follow-up periods ranged from two months to 11 years. Varying degrees of lameness, which tended to be exacerbated by exercise, persisted in all cases. The radial carpal bone appears to have at least three separate centres of ossification which eventually fuse; their planes of fusion correspond approximately to the two main fracture lines. These areas of fusion could be weak points within the radial carpal bone.

Animals↗
PubMed2000

Muscimol dialysis in the retrotrapezoid nucleus region inhibits breathing in the awake rat.

Under anesthesia, inactivation of the retrotrapezoid nucleus (RTN) region markedly inhibits breathing and chemoreception. In conscious rats, we dialyzed muscimol for 30 min to inhibit neurons of the RTN region reversibly. Dialysis of artificial cerebrospinal fluid had no effect. Muscimol (1 or 10 mM) significantly decreased tidal volume (VT) (by 16-17%) within 15 min. VT remained decreased for 50 min or more, with recovery by 90 min. Ventilation (VE) decreased significantly (by 15-20%) within 15 min and then returned to baseline within 40 min as a result of an increase in frequency. This, we suggest, is a compensatory physiological response to the reduced VT. Oxygen consumption was unchanged. In response to 7% CO(2) in the 1 mM group, absolute VE and change in VE were significantly reduced (by 19-22%). In the 10 mM group, the response to dialysis included a time-related increase in frequency and decrease in body temperature, which may reflect greater spread of muscimol. In the awake rat, the RTN region provides a portion of the tonic drive to breathe, as well as a portion of the response to hypercapnia.

Animals↗
PubMed2000

Polymerase chain reaction-based method for quantifying recruitment of monocytes to mouse atherosclerotic lesions in vivo: enhancement by tumor necrosis factor-alpha and interleukin-1 beta.

The critical role of monocyte recruitment in atherogenesis has been appreciated for some time. However, until recently, there have been no sufficiently sensitive methods for measuring rates of monocyte recruitment to the arterial wall in vivo. We have developed a novel highly sensitive method, based on the polymerase chain reaction, for quantitatively tracking DNA-marked monocytes and have adapted it for use in mice. We use the uniquely male gene, SRY:, on the Y chromosome as a gene marker. We transfuse monocytes from a male donor into a congenic female mouse, euthanize the mouse after 24 to 48 hours, and then quantify the arterial uptake of monocytes by quantitative polymerase chain reaction. This study describes the techniques used and their sensitivity and reproducibility and demonstrates the approach by assessing the effects of cytokines. In control low density lipoprotein receptor-negative mice, monocyte recruitment decreased slightly but significantly as lesions progressed. Intraperitoneal injection of a combination of tumor necrosis factor-alpha and interleukin-1 beta more than doubled the rate of monocyte recruitment into developing lesions. However, the response to the cytokines was much greater in younger mice with less advanced lesions than in older animals with more advanced lesions.

Animals↗
PubMed2000

Oxidized LDL reduces monocyte CCR2 expression through pathways involving peroxisome proliferator-activated receptor gamma.

The CCR2-mediated recruitment of monocytes into the vessel wall plays an important role in all stages of atherosclerosis. In recent studies, we have shown that lipoproteins can modulate CCR2 expression and have identified native LDL as a positive regulator. In contrast, oxidized LDL (OxLDL), which is mainly formed in the aortic intima, reduces CCR2 expression, promotes monocyte retention, and may cause pathological accumulation of monocytes in the vessel wall. We now provide evidence that OxLDL reduces monocyte CCR2 expression by activating intracellular signaling pathways that may involve peroxisome proliferator-activated receptor gamma (PPARgamma). Receptor-mediated uptake of the lipoprotein particle was required and allows for delivery of the exogenous ligand to the nuclear receptor. The suppression of CCR2 expression by OxLDL was mediated by lipid components of OxLDL, such as the oxidized linoleic acid metabolites 9-HODE and 13-HODE, known activators of PPARgamma. Modified apoB had no such effect. Consistent with a participation of the PPARgamma signaling pathway, BRL49653 reduced CCR2 expression in freshly isolated human monocytes ex vivo and in circulating mouse monocytes in vivo. These results implicate PPARgamma in the inhibition of CCR2 gene expression by oxidized lipids, which may help retain monocytes at sites of inflammation, such as the atherosclerotic lesion.

Animals↗
PubMed2000

Immunohistochemical estimation of in-situ cell cycle time in neoplastic epithelial cells in human large intestine: a new cell proliferation index.

In-situ cell cycle time (in-situ Tc) of epithelial cells could be estimated by using a formula; in-situ Tc = cell proliferation rate divided by mitosis rate, on a scale of Tm (cell cycle time in M phase) arbitrary unit (AU), In order to see the nature of in-situ Tc in the adenoma-carcinoma sequence in the human large intestine, the in-situ Tc in 27 cases of adenoma and 71 cases of adenocarcinoma with adenoma components in the human large intestine was estimated by using this formula, counting proliferating cells and mitotic cells in the immunohistochemistry of Ki-67 antigen. C12 antigen was examined as an oncogenic progression indicator in the adenoma-carcinoma sequence. The in-situ Tc tended to shorten in adenoma in accordance with the histological grading of atypia but not in adenoma component. No significant differences in the in-situ Tc was recognized as a whole among adenomas, adenoma components and adenocarcinomas in the mucosa, whereas the in-situ Tc of adenoma components with moderate to severe atypia was significantly longer than that of adenocarcinomas in the mucosa (p = 0.05). The in-situ Tc lengthened in adenocarcinomas invading the submucosa and shortened in adenocarcinomas invading the proper muscular layer. The cases expressing the C12 antigen increased in order of adenoma, adenoma component and adenocarcinoma. The cases expressing the C12 antigen indicated short in situ Tc in the adenomas and adenocarcinomas but not in the adenoma components. Thus, the estimated in-situ Tc is a useful index of the oncogenetic progression, which is different from that detected by the C12 antigen.

Adenocarcinoma↗
PubMed2000

[Clinical significance of ProGRP31-98 in patients with small-cell lung cancer].

OBJECTIVE: To determine the clinical significance of serum level of pro-gastrin-releasing peptide 31-98 (ProGRP31-98) for small-cell lung cancer (SCLC) in comparison with neuron-specific enolase (NSE). METHODS: Serum level of ProGRP31-98 was measured by ELISa in 30 patients with SCLC, 30 patients with non-small-cell lung cancer (NSCLC), 10 patients with SCLC who had received treatment, 15 patients with benign lung diseases and 15 normal subjects. The receiver operating characteristic (ROC) curve was used to set the cut-off value and evaluate the diagnostic accuracy. RESULTS: The serum level of ProGRP31-98 was significantly increased in patients with SCLC as compared to that of the normal controls as well as that in any other groups of patients. It was higher in SCLC patients with extensive disease than in patients with limited disease. In patients with distant metastases, it was also higher than in those without. Increase in serum ProGRP31-98 and NSE was both seen in SCLC patients, but the former was of much greater magnitude when compared to the normal controls. Given the cut-off levels of 40 pg/ml for ProGRP31-98 and 8 micrograms/L for NSE, their sensitivity of diagnosis in SCLC was 73% and 60%, respectively. The area under ROC curve of ProGRP31-98 was significantly larger than that of NSE. Similar results of diagnostic sensitivity and area under ROC curve were observed in SCLC patients with limited disease. All patients responded to chemotherapy showed marked decrease in ProGRP31-98. CONCLUSION: ProGRP31-98 is a more specific and sensitive marker than NSE for the diagnosis of SCLC.

Adult↗
PubMed2000

[Classification of secondary nasal deformities associated with unilateral cleft lip].

OBJECTIVE: To classify secondary deformities of cleft lip noses. METHODS: 56 patients with secondary nasal deformities of cleft lip were chosen at random. Cartilages of those noses were dissected and measured when correcting nasal deformity in order to find the relationship between anatomical anomaly of nasal cartilages and nasal deformity. RESULTS: Three grades of anatomical anomalies of the nasal framework were found. Grade I, the morphological anomaly occurs at lower third of the diseased side only. Grade II, the lower third of the another side is involved in addition. Grade III, the dorsum nasi is also deviated. CONCLUSIONS: This classification may be employed as a practical guide for surgical planning.

Adolescent↗
PubMed2000

[The modulating effect of panax pseudoginseng wall saponins on the DAG-PKC signal pathway and TNF secretion of macrophages].

OBJECTIVE: To explore the roles of panax pseudoginseng wall saponins on the DAG-PKC signal pathway and TNF secretion of macrophages. METHODS: The changes of the activities of postburn inositol lipid signal system factors such as PLC, DAG, cytomembrane PKC, cytoplasma PKC, and intracellular calcium concentration and the secretory amount of macrophage TNF were observed. RESULTS: Panax pseudoginseng wall saponins could reduce the increased PLC activity from 57.58 +/- 8.19 to 27.00 +/- 2.31 and the intracellular calcium concentration from 393.18 +/- 392.62 to 90.56 +/- 7.21. With the role of panax pseudoginseng wall saponins, DAG activity reduced from 488.10 +/- 40.20 to 288.30 +/- 30.00, cytomembrane PKC activity decreased from 3081.50 +/- 698.50 to 1699.50 +/- 218.50, and cytoplasmic PKC activity from 2 188.60 +/- 258.30 to 848.40 +/- 138.30. The secretory TNF amount of macrophage decreased by 55%. CONCLUSION: Panax pseudoginseng wall saponins might play an very important role in the modulating of the DAG-PKC signal pathway and decreased TNF secretion of macrophage.

Animals↗
PubMed2000

[The effects of NAC on the expression and activity of SPA in rats inflicted by smoke inhalation injury].

OBJECTIVE: To investigate the effects of NAC (N-acetyl-L-cysteine) on the expression and activity of SPA (surfactant-associated protein A) in rats inflicted by smoke inhalation injury. METHODS: Wistar rats inflicted with smoke inhalation injury were employed as the model. The expression of SPA mRNA, the static pulmonary compliance, the surface tension of the alveolar lavage and the morphology of lamellae bodies (LB) of type II alveolar cells were examined. RESULTS: After the application of NAC, there exhibited an increase in SPA mRNA expression and static pulmonary compliance, and the restoration of the BAL surface tension to normal. CONCLUSION: The application of NAC could promote the expression of SPA mRNA after smoke inhalation injury and improve the SPA-related function.

Acetylcysteine↗
PubMed2000

[Effects of early enteral feeding and L-arginine supplementation on liver albumin synthesis in burned rats].

OBJECTIVE: To evaluate the effect of early enteral feeding and L-arginine supplementation on mRNA expression of albumin, and some cytokines. METHODS: Twenty Wistar rats prepared with gastrostomy 7 days before the experiment were inflicted with 30% TBSA flame and were divided into early enteral feeding group (EF) and L-arginine enriched early enteral feeding group (AEF). All rats in two group starts enteral feeding two hours after burn. Capillary electrophoresis and reverse transcription-polymerase chain reaction (RT-PCR) were used to measure the mRNA of albumin, TNFa, IL-1a, IL-6R and iNOS respectively on 1st, 3rd, 6th and 9th day post burn (PBD). Serum albumin was observed at the same time. RESULTS: The mRNA expression of albumin on PBD1 was reduced in both group and improved on PBD3, 6, 9. The gene expression of albumin was significantly higher in AEF group than in EF group onPBD3, 9 [(1812 +/- 41) vs (1417 plus minus 43), P < 0.01]. Similarly, serum albumin were very low in two groups on PBD1 and improved on PBD3, 6, 9. Serum albumin in AEF group was significantly higher than in EF group on PBD9 [(31.9 plus minus 2.1) g/L vs (28.1 plus minus 1.3) g/L, P < 0.01]. The mRNA of TNFalpha, IL-1alpha, IL-6R and iNOS were increased on PBD1 and reduced on PBD3, 6, 9. The gene expression of TNFalpha, IL-1alpha in AEF group were significantly lower than EF group on PBD6, while IL-6R differed significantly between AEF group and EF group [(972 +/- 87) vs (2570 +/- 90), P < 0.01] on PBD9. There were no significant difference in iNOS mRNA production after burn in two group. CONCLUSION: Early enteral feeding could improve albumin biosynthesis and reduce the gene expression of TNFalpha, IL-1alpha, IL-6R and iNOS. L-arginine-supplemented early enteral feeding could further increase the gene expression of albumin possibly by reducing the expression of TNFalpha, IL-1alpha and IL-6R and did not increase the expression of iNOS.

Albumins↗
PubMed2000

[The protective effects on postburn renal function by early enteral feeding in burned rats].

OBJECTIVE: To study the effects of enteral feeding on postburn renal function in rats and its possible mechanism. METHODS: Wistar rats inflicted with 30% TBSA skin burn were adopted as the model. The effects of early enteral feeding (EEF) were dynamically observed on the changes of intra-gastric mucosal pH (pHi), portal endotoxin level, renal water content, plasma level of tumor necrosis factoralpha (TNFalpha), serum BUN and Cr contents and endogenous creatinine clearance rate. RESULTS: Compared with that in simple burn group, the pHi decrease could be inhibited by EEF, the portal endotoxin level, plasma TNFalpha level and renal water content were decreased by the action of EEF. Serum BUN, Cr contents were not affected by EEF. But the CCr increased by 4.67 times [from (16.43 +/- 2.9) to (3.52 +/- 0.79), P < 0.01] with EEF. CONCLUSION: EEF could obviously improve postburn renal function in severely burned rats, which might be related to the decrease of enteral endotoxin translocation and the postburn release of inflammatory mediators.

Animals↗
PubMed2000

[Preliminary report on introducing exogenous DNA into Panax quinquefolium].

Worked aimed at introduction of Panax ginseng's exogenous DNA into Panax quinquefolium has been done continuously the past three years in our institute. The results showed that the best way of exogenous DNA introduction is via the pollen tube similarly lesser flowery organ. The suitable introducing time is at 10:00-11:00 am, and the seeds ratio is 13.21% at the experiment limits.

DNA, Plant↗