Biomedical subjects

J Pan

Publications and source records attributed to J Pan.

At least 91 records · Page 5Linked to original sources

PubMed2000

Innate antiviral defenses in body fluids and tissues.

Innate, non-specific, resistance mechanisms are important barriers to pathogens, particularly delaying virus multiplication at the onset of infections. These innate defense mechanisms include a series of mechanical barriers, pre-existing inhibitory molecules, and cellular responses with antimicrobial activity. The antiviral activities of these innate inhibitors reside in a variety of partly characterized substances. This review presents the innate antiviral inhibitors in cell cultures, urine, serum, the gastrointestinal tract, the nervous system, tissues of crustaceans, and saliva. Medical adaptation of the innate antiviral defense mechanisms may be useful for prevention and treatment of viral infections.

Animals↗

PubMed2000

P300 habituation from auditory single-stimulus and oddball paradigms.

The habituation of auditory P300 event-related brain potential (ERP) from single-stimulus paradigm was evaluated and compared to that from oddball paradigm. Three task conditions were: oddball with a button press (oddball/press) response, single-stimulus with a button-press (single-stimulus/press) response and a silent count (single-stimulus/count) response. The oddball/press condition demonstrated larger P300 amplitude and longer latency overall than either single-stimulus condition, but P300 amplitude decreased and peak latency increased similarly over successive trial blocks for all three tasks. Thus, the oddball and single-stimulus ERP tasks produce analogous changes under repeated measurements and indicate that the single-stimulus task can serve as an alternative method for eliciting the P300 in applied and clinical settings.

Acoustic Stimulation↗

PubMed2000

Comparison of clinical and histologic diagnoses in periapical lesions.

OBJECTIVE: To determine the frequency with which histopathologic examination of periapical biopsy specimens contributed information not anticipated clinically. STUDY DESIGN: Clinical and histopathologic information from 805 sequentially submitted periapical biopsy specimens over a 2-year period was compared. Clinical data included endodontic status, age and sex of patient, location of lesion, and submitting clinician. Histopathologic diagnoses were categorized as 1) sequelae of pulpal necrosis (SPN), 2) complicated SPN (CSPN) with infection or antral involvement, or 3) periapical lesions unrelated to pulpal necrosis (PLUPN). RESULTS: Of the 805 cases, 788 (97.9%) were SPN, 9 (1.1%) were CSPN, and 8 (1%) were PLUPN, representing a range of locally aggressive but benign lesions and 1 malignancy. Comparison of clinical and histologic diagnoses indicated that the clinical interpretation was inaccurate in 4.1% of cases (suggesting SPN in PLUPN cases or PLUPN in SPN cases). In another 0.9% of cases, the histologic analysis (indicating CSPN) contributed additional information to the clinical diagnosis. CONCLUSIONS: A histopathologic examination contributed clinically relevant information in 5.0% of submitted cases. General extrapolation of this figure is not possible. Theoretical considerations, which could positively or negatively bias this figure, are discussed.

Adult↗

PubMed2000

Signal transduction during fertilization in the unicellular green alga, Chlamydomonas.

Sexual reproduction in the green alga, Chlamydomonas, is regulated by environmental conditions and by cell-cell interactions. After gametogenesis, flagellar adhesion between gametes triggers gamete activation, leading to cell fusion and zygote formation. Recent studies have identified new molecular events that underlie signal transduction during Chlamydomonas fertilization, including expression of a sex-determining protein, phosphorylation of a homeodomain protein, activity of a kinesin II and regulated translocation of an aurora/Ip11-like protein kinase from the cell body to the flagella.

Animals↗

PubMed2000

Effect of ovariectomy on bone remodeling adjacent to hydroxyapatite-coated implants in the tibia of mature rats.

PURPOSE: The purpose of this study was to examine the effects of estrogen deficiency on bone remodeling adjacent to implants in the tibia of mature rats. MATERIALS AND METHODS: Hydroxyapatite-coated implants were placed bilaterally in the proximal metaphysis of the tibia of 18 female Wistar rats (48 weeks old), and ovariectomy was performed 168 days later. As a control, sham ovariectomy was performed in a similar group of 18 rats. Six animals from each group were killed at 28, 84, and 168 days after ovariectomy. Undecalcified sections were prepared, and changes in the bone tissue around the implants were evaluated histologically. Histomorphometric measurements were made with a computer-based image analyzer to quantify the unit bone mass around each implant and the amount of implant-bone contact. RESULTS: In the cortical bone area, ovariectomy induced only a slight decrease in bone contact with the implant, compared with that in the sham-operated rats. However, both the bone volume around the implant and implant-bone contact were significantly decreased in the cancellous bone area in ovariectomized rats compared with the sham-operated rats. CONCLUSION: Thinning of the bone trabeculae holding dental implants may occur with estrogen deficiency.

Animals↗

PubMed2000

The measurement of structural mobilities of a circular cylindrical shell

Structural mobility is useful for the estimation of structural power flows in coupled systems. Although the methods of measuring structural mobilities are easily found for one-dimensional beam structures, few are available for cylindrical shells. In this paper, a new method is proposed for the measurement of the structural mobilities of a circular cylindrical shell. A point force excitation is used instead of circumferential modal forces which are difficult to implement in practice. This method utilizes the least squares technique to obtain the transfer function components of different circumferential modes from the measured data. Experiments were carried out on a circular cylindrical shell with different end conditions excited by a point force to verify the feasibility of this proposed method.

Journal Article↗

PubMed2000

On acoustic and structural modal cross-couplings in plate-cavity systems

Modal cross-couplings are sometimes neglected in the prediction of sound field and structural responses of vibroacoustic systems where an enclosed sound field is coupled to a vibrating boundary structure. In such systems, there are two types of modal cross-couplings and they are commonly referred to as acoustic modal cross-coupling (ACC) and structural modal cross-coupling (SCC). The prediction errors generated from neglecting either of these cross-couplings are dependent not only on the modal properties of the vibroacoustic system (e.g., modal densities, dampings, etc.), but also on whether the sound field or the structure is directly driven. However, the physical mechanisms and characteristics of both cross-couplings are not well understood and, consequently, the conditions when ACC or SCC has a significant contribution to the system responses become unknown. This paper presents a mathematical description which allows the two types of modal cross-couplings to be studied independently. This description is then used to obtain the physical mechanisms and features of both cross-couplings. The effects of each type of cross-couplings on the system responses are then investigated and the general conditions under which these modal cross-couplings may be ignored are underlined.

Journal Article↗

PubMed2000

Acoustical wave propagator

In this paper, an explicit acoustical wave propagator (AWP) is introduced to describe the time-domain evolution of acoustical waves. To implement its operation on an initial state of wave motion, the acoustical wave propagator is approximated as a Chebyshev polynomial expansion, which converges to machine accuracy. The spatial gradient in each polynomial term is evaluated by a Fourier transformation scheme. Analysis and numerical examples demonstrated that this Chebyshev-Fourier scheme is highly accurate and computational effective in predicting time-domain acoustical wave propagation and scattering.

Journal Article↗

PubMed2000

Virus clearance through apoptosis-dependent phagocytosis of influenza A virus-infected cells by macrophages.

Some cultured cell lines undergo typical apoptosis upon infection with influenza virus. However, the release of replicated virus into the culture medium does not change when apoptosis is inhibited. Since apoptotic cells are heterophagically eliminated at early stages of the apoptosis pathway, we anticipated that the coexistence of phagocytic cells with virus-infected cells affects the extent of virus growth. When influenza A virus-infected HeLa cells were mixed with activated mouse peritoneal macrophages, efficient phagocytosis, which was abrogated in the presence of a caspase inhibitor, occurred. At the same time, the release of virus into the culture medium was completely inhibited, and this required direct contact between virus-infected cells and macrophages. Furthermore, an immunoelectron microscopic analysis detected influenza virus particles associated with phagosome-like structures within macrophages. These results indicate that apoptosis-dependent phagocytosis of virus-infected cells may lead to direct elimination of the pathogen.

Animals↗

PubMed2000

Significance of ERK cascade compared with JAK/STAT and PI3-K pathway in gp130-mediated cardiac hypertrophy.

We compared the role of the Raf-1/mitogen-activated protein kinase/extracellular signal-regulated protein kinase (MEK)/extracellular signal-regulated protein kinase (ERK)/p90(RSK) cascade in gp130-mediated cardiac hypertrophy with the contribution of the Janus kinase (JAK)/signal transduction and activation of transcription (STAT) and phosphatidylinositide 3-kinase (PI3-K) pathways. Primary cultured neonatal rat cardiomyocytes were stimulated with leukemia inhibitory factor (LIF). LIF sequentially activated Raf-1, MEK1/2, ERK1/2, and p90(RSK). We used PD-98059 (a specific MEK inhibitor), AG-490 (a JAK2 inhibitor), and wortmannin (a PI3-K inhibitor) to confirm that this cascade was independent of the JAK/STAT and PI3-K/p70 S6 kinase (S6K) pathways. PD-98059, AG-490, and wortmannin suppressed the LIF-induced increase in [(3)H]phenylalanine uptake by 54.7, 21.5, and 25.6%, respectively, and inhibited the increase in cell area by 61.2, 42.8, and 39.2%, respectively. Reorganization of myofilaments was predominantly suppressed by AG-490. LIF-induced expression of c-fos, brain natriuretic peptide, and skeletal alpha-actin mRNA was markedly suppressed by PD-98059 and moderately suppressed by wortmannin and AG-490. Atrial natriuretic peptide was significantly suppressed by AG-490. These findings indicate that this pathway is critically involved in protein synthesis, induction of c-fos, brain natriuretic peptide, and skeletal alpha-actin expression and is partially involved in myofilament reorganization and atrial natriuretic peptide induction in gp130-mediated cardiac hypertrophy.

Androstadienes↗

PubMed2000

Plasma carbon monoxide levels in term newborn infants with sepsis.

Carbon monoxide (CO) has been implicated as a new endogenously produced mediator similar to nitric oxide (NO). CO was measured in plasma samples from 7 term newborn infants with sepsis and from 30 healthy neonates. Plasma CO levels were significantly higher in the group with sepsis at the time of admission to the neonatal intensive care unit than in the healthy controls (p < 0.05). Moreover, the elevated plasma CO levels were significantly related to increased NO production, as indicated by plasma nitrite/nitrate levels (p < 0.05). The present study suggests that, in addition to NO, CO might be another important mediator taking part in the pathogenesis of neonatal sepsis.

Bacterial Infections↗

PubMed2000

Role of carbon monoxide and nitric oxide in newborn infants with postasphyxial hypoxic-ischemic encephalopathy.

OBJECTIVE: To investigate the role of carbon monoxide (CO) and nitric oxide (NO) in the pathogenesis of neonatal hypoxic-ischemic encephalopathy (HIE). METHODS: Plasma CO and NO levels were studied in 33 asphyxiated term neonates, and 30 healthy neonates served as controls. RESULTS: Among the 33 asphyxiated term neonates, plasma CO and NO levels in 28 neonates with HIE were significantly higher than those in the 5 infants without HIE and in the normal controls. The plasma CO and NO levels in the newborn infants with HIE stage 3 were found to be significantly higher than those in the neonates with HIE stage 1 and 2. Moreover, plasma CO and NO levels were significantly increased in neonates with brain damage and adverse outcome as compared with those in patients with normal neuroimaging and normal outcome. CONCLUSION: Plasma CO and NO levels after perinatal asphyxia are related to the severity of neonatal HIE, brain damage, and neurologic outcome. The present study suggests that CO and NO might play important roles in the pathogenesis of neonatal HIE.

Asphyxia Neonatorum↗

PubMed2000

Use of a novel real-time quantitative reverse transcription-polymerase chain reaction method to study the effects of cytokines on cytochrome P450 mRNA expression in mouse liver.

In this study, we developed a real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR) method to study cytochrome P450 (CYP) mRNA regulation by cytokines in mouse liver. The method combines standard RT-PCR with a fluorogenic probe in which the intensity of fluorescence is proportional to the amount of target template present. We show that this method provides very rapid, sensitive, and reproducible quantification of mouse Cyp mRNA with a wide dynamic range of starting target molecule. We validated the method by using several prototypic CYP inducers. As expected, the mRNA levels of Cyp3a11, Cyp2b10, and Cyp1a2 were induced by a single dose of dexamethasone (100 mg/kg), phenobarbital (80 mg/kg), and 3-methylcholanthrene (80 mg/kg), respectively. The method of real-time RT-PCR was then used to evaluate the effects of interleukin (IL)-6 (100 ng/mouse), IL-1beta (500 ng/mouse), and tumor necrosis factor (TNF)-alpha (2 microgram/mouse) on Cyp mRNA expression in the mouse. Constitutive Cyp2b10 mRNA was reduced to 40% by IL-6 and 15% by IL-1beta, whereas Cyp2d9 mRNA was reduced to 70% by TNF-alpha administration. The level of Cyp1a2 mRNA was suppressed to 67% by IL-6 and 59% by TNF-alpha. Cyp3a11 and Cyp2e1 mRNAs were not affected by any of the cytokines that were studied. We conclude that the real-time RT-PCR method is a powerful new tool to study CYP mRNA expression and regulation. Using this method, we are the first to report that the expression of constitutive Cyp2b10, 1a2, and 2d9 mRNAs was suppressed by proinflammatory cytokines.

Animals↗

PubMed2000

[A study of ventricular repolarization duration variability and dependence of RTm/RR].

As an important electrophysiological parameter that reflects cardiac depolarization and repolarization process, ventricular repolarization duration has been drawing growing attention. It is influenced by several physiological and pathological factors and associated with several cardiac diseases. We studied repolarization duration variability (RDV) and dependence of RTm/RR among normal subjects of different age-groups, as well as between normal subjects and subjects with cardiac diseases. It was found that RDV and dependence of RTm/RR are related to age. There are significant differences in the slope of RTm/RR, coherence, CV ratio and RDV between normal subjects and subjects with cardiac diseases. The RDV and dependence of RTm/RR can be employed in providing a more useful evaluation of cardiac disease and function in clinical care.

Adult↗

PubMed2000

Induced apoptosis and necrosis by 2-methylfuranonaphthoquinone in human cervical cancer HeLa cells.

2-Methylnaphtho[2,3-b]furan-4,9-dione (FNQ3) has been reported to be more cytotoxic to human malignant tumor cell lines than are the corresponding normal epithelial cells. Therefore, we examined the dose response of FNQ3 against human cervical cancer HeLa cells in culture. When 1.25 mg/ml FNQ3 was applied, apoptosis was induced, as determined by an immunohistochemical staining of fragmented genome DNA and cell profiles. Significant inhibition of Bcl-2 oncogene protein expression by the same concentration of FNQ3 also was demonstrated by an immunohistochemical staining method to visualize the expressed cells and Western blot in polyacrylamide gel electrophoresis. Flow-cytometric spectra showed S-phase arrest in cell cycles and the appearance of sub-G1 phase consistent with apoptosis. On the other hand, concentrations of 5 microg/ml or more of FNQ3 induced necrosis. These results show that FNQ3 may act as an antitumor agent to induce apoptosis by affecting Bcl-2 expression and cell cycles, or necrosis as the result of primary mitochondrial injuries.

Antineoplastic Agents, Phytogenic↗

PubMed2000

[Optimizing design in tissue engineering].

Tissue engineering may provide an alternative to organ transplantation and tissue transplantation which are both suffering from the limited condition of supply, so it is one of the research high-lights. This article puts forward the viewpoint of optimizing design according to its components and makes relevant suggestion; the aim is to lay a foundation for tissue engineering.

Biocompatible Materials↗

PubMed2000

Relationship between the burden of Pneumocystis carinii, the inflammatory reaction and lung injury in Pneumocystis carinii pneumonia.

OBJECTIVE: To study the relationship between the burden of Pneumocystis carinii (P. carinii) and the inflammatory reaction and biochemical markers in bronchoalveolar lavage fluids (BALF) in a rat model of P. carinii pneumonia (PCP). METHODS: Clean grade 50 male Sprague-Dawley rats were immunosuppressed by a subcutaneous injection of 25 mg cortisone acetate twice a week for 8-12 weeks; the PCP model was successfully induced in 14 rats. The inflammatory reaction and biochemical markers of the activity of lactate dehydrogenase (LDH), alkaline phosphatase (ALP) and type IV collagenase (matrix metalloproteinases, MMP-2, MMP-9) as well as the values of total protein (TP) and albumin (ALB) in BALF between the mild burden group of P. carinii (involved alveoli < 25% per 100 alveoli, Group A) and the moderate to severe burden group (involved alveoli > or = 25% per 100 alveoli, Group B) were measured. The other six clean grade SD rats served as normal control group (Group C). RESULTS: The total white cell count in BALF was higher in Group B [(6.8 +/- 1.7) x 10(6)/L] than in Group A [(3.8 +/- 1.2) x 10(6)/L] (P < 0.01); however, there were no differences in white cell differentiation. Assays of biochemical markers showed that ALB in BALF in Group B (0.893 +/- 0.469 g/L) was increased in comparison with Group A (0.262 +/- 0.169 g/L); it was only 0.026 +/- 0.021 g/L in Group C. The contents of TP and activities of LDH were higher in Group B (TP 1.756 +/- 0.706 g/L, LDH 2580 +/- 550 U/L) than in Group A (TP 0.784 +/- 0.553 g/L, LDH 1410 +/- 620 U/L); the values of TP and LDH were 0.063 +/- 0.020 g/L and 370 +/- 250 U/L respectively in Group C. The activity of Type IV collagenase, including MMP-2 and MMP-9, was higher in Group B than in Group A (P < 0.01) (MMP-2: 1102 +/- 169 grey value vs 459 +/- 274 grey value; MMP-9: 1218 +/- 257 grey value vs 449 +/- 225 grey value). There was no activity of Type IV collagenase in BALF of Group C. No statistically significant difference was observed in ALP between the groups B and A. CONCLUSIONS: These results indicate that there is a significant correlation between the burden of P. carinii in lung tissues and the inflammatory reaction as well as biochemical markers of the resultant activity of lung injury.

Albumins↗

PubMed2000

[The effects of experimental osteoporosis on bone tissues around hydroxyapatite implants].

OBJECTIVE: To investigate the effects of estrogen decreasing on bone tissues around implants in ovariectomized rats. METHOD: Forty-two female Wistar rats, aged 32 weeks, were used in this study. First, cylindrical hydroxyapatite-coated implants were planted in the proximal part of tibiae of the rats. Then, the rats in experimental group and control group were respectively performed ovariectomy and false surgery after 56 days, the rates were killed in 28, 84 and 168 days after operation, and tibiae were taken out to prepare undecalcified sections. The section were examined by routine histomorphometric measurement and the dynamic changes of trabecular bone and extent of contact between the implants and bone tissue around them. RESULTS: Twenty-eight days after operation, the density of trabecular bone around the implant in experiment group was found significantly reduced compared with the control group. In the area of cortical bone, no difference was found in the extent of implant-bone contact between two groups, while in the area of spongy bone the extent of contact was different obviously. CONCLUSION: Ovariectomy in Wistar rats can induce significant osteoporosis around implant, these finding suggest that menopause in women patients may also induce osteoporosis around implanted artificial teeth and affect the prognosis. Therefore, the patients should be carefully observed during the implant treatment course.

Animals↗