Biomedical subjects

Kewu Huang

Publications and source records attributed to Kewu Huang.

5 recordsLinked to original sources

PubMed2007

Variation in senescent-dependent lung changes in inbred mouse strains.

Previous studies from our laboratories showed lung development differences between inbred strains of mice. In the present study, the C57BL/6J (B6) and DBA/2J (D2) strains were examined for senescent-dependent differences with respect to the lung structure and function. Specifically, we hypothesize that senescent changes in lung vary between strains due to identifiable gene expression differences. Quasi-static pressure-volume curves and respiratory impedance measurements were performed on 2- and 20-mo-old B6 and D2 mice. Lung volume at 30 cm H(2)O (V(30)) pressure was significantly (P < 0.01) increased with age in both strains, but the increase was proportionally greater in D2 (68%) than in B6 (40%) mice. In addition, decreased elastic recoil pressure at 50% of V(30) and a reduction in airway resistance as a function of positive end-expiratory pressure were observed in 20-mo-old D2 mice but not in B6 mice. Morphometric analysis of lung parenchyma showed significant decreases in elastic fiber content with age in both strains, but the collagen content was significantly (P < 0.01) increased with age in D2 but not B6 mice at 20 mo. Furthermore, using quantitative RT-PCR methods, gene expression differences between strains suggested that D2 mice significantly (P < 0.05) downregulated the expressions of elastin (Eln) and procollagen I, III, and VI (Col1a1, Col3a1, and Col6a3) in lung tissue at 20 mo of age. These age-dependent changes were accompanied by an increased gene expression in matrix metalloproteinase 9 (Mmp9) in D2 and an increase in tissue inhibitor of matrix metalloproteinase (Timp1 and Timp4) in B6 mice. In conclusion, the results from the present study demonstrate that lung mechanics of both strains show significant age-dependent changes. However, changes in D2 mice are accelerated relative to B6 mice. Moreover, gene expression differences appear to be involved in the strain-specific changes of lung mechanic properties.

Aging↗

PubMed2006

Age-dependent changes of airway and lung parenchyma in C57BL/6J mice.

In the current study, we hypothesize that senescent-dependent changes between airway and lung parenchymal tissues of C57BL/6J (B6) mice are not synchronized with respect to altered lung mechanics. Furthermore, aging modifications in elastin fiber and collagen content of the airways and lung parenchyma are remodeling events that differ with time. To test these hypotheses, we performed quasi-static pressure-volume (PV) curves and impedance measurements of the respiratory system in 2-, 20-, and 26-mo-old B6 mice. From the PV curves, the lung volume at 30 cmH(2)O pressure (V(30)) and respiratory system compliance (Crs) were significantly (P < 0.01) increased between 2 and 20 mo of age, representing about 80-84% of the total increase that occurred between 2 and 26 mo of age. Senescent-dependent changes in tissue damping and tissue elastance were analogous to changes in V(30) and Crs; that is, a majority of the parenchymal alterations in the lung mechanics occurred between 2 and 20 mo of age. In contrast, significant decreases in airway resistance (R) occurred between 20 and 26 mo of age; that is, the decrease in R between 2 and 20 mo of age represented only 29% (P > 0.05) of total decrease occurring through 26 mo. Morphometric analysis of the elastic fiber content in lung parenchyma was significantly (P < 0.01) decreased between 2 and 20 mo of age. To the contrary, increased collagen content was significantly delayed until 26 mo of age (P < 0.01, 2 vs. 26 mo). In conclusion, our data demonstrate that senescent-dependent changes in airway and lung tissue mechanics are not synchronized in B6 mice. Moreover, the reduction in elastic fiber content with age is an early lung remodeling event, and the increased collagen content in the lung parenchyma occurs later in senescence.

Aging↗

PubMed2003

Sequential non-invasive mechanical ventilation following short-term invasive mechanical ventilation in COPD induced hypercapnic respiratory failure.

OBJECTIVE: To estimate the feasibility and the efficacy of early extubation and sequential non-invasive mechanical ventilation (MV) in chronic obstructive pulmonary disease (COPD) with exacerbated hypercapnic respiratory failure. METHODS: Twenty-two intubated COPD patients with severe hypercapnic respiratory failure due to pulmonary infection (pneumonia or purulent bronchitis) were involved in the study. At the time of pulmonary infection control window (PIC window) appeared, when pulmonary infection had been significantly controlled (resolution of fever and decrease in purulent sputum, radiographic infiltrations, and leukocytosis) after the antibiotic and the comprehensive therapy, the early extubation was conducted and followed by non-invasive MV via facial mask immediately in 11 cases (study group). Other 11 COPD cases with similar clinical characteristics who continuously received invasive MV after PIC window were recruited as control group. RESULTS: All patients had similar clinical characteristics and gas exchange before treatment, as well as the initiating time and all indices at the time of the PIC window. For study group and control group, the duration of invasive MV was (7.1 +/- 2.9) vs (23.0 +/- 14.0) days, respectively, P < 0.01. The total duration of ventilatory support was (13 +/- 7) vs (23 +/- 14) days, respectively, P < 0.05. The incidence of ventilator associated pneumonia (VAP) were 0/11 vs 6/11, respectively, P < 0.01. The duration of intensive care unit (ICU) stay was (13 +/- 7) vs (26 +/- 14) days, respectively, P < 0.05. CONCLUSIONS: In COPD patients requiring intubation and MV for pulmonary infection and hypercapnic respiratory failure, early extubation followed by non-invasive MV initiated at the point of PIC window significantly decreases the invasive and total durations of ventilatory support, the risk of VAP, and the duration of ICU stay.

Adult↗

PubMed2002

Proportional assist ventilation: methodology and therapeutics on COPD patients compared with pressure support ventilation.

OBJECTIVE: To investigate the impact of proportional assist ventilation (PAV) on tolerance and breathlessness in ventilated chronic obstructive pulmonary disease (COPD), and to describe the patient-ventilator interaction, hemodynamic state, breathing pattern and work of breath during PAV and pressure support ventilation (PSV). METHODS: Ten intubated COPD patients on weaning from mechanical ventilation were studied. Elastance and resistance were measured by both the inspiratory-hold technique during a brief period of volume control ventilation and runaway technique during PAV. Each assistance level of PAV (80%, 60% and 40%) and PSV was selected randomly. Patients' response, hemodynamics, blood gas and lung mechanics were monitored. RESULTS: Tidal volume and respiratory rate didn't change in a consistent manner as the level of assist was decreased (P > 0.05). With the level of assist increasing, peak inspiratory pressure was increasing significantly (P < 0.05), while patients' work of breath had the tendency to decrease (P < 0.05). A significant difference in the Borg Category Scale was observed between PAV and PSV (0.50 [1.50] vs. 0.75 [2.00], P < 0.05) at the same degree of respiratory muscle unloading. PaCO(2) was significantly higher on PAV (54 [23] mm Hg) than on PSV (48 [23] mm Hg) (P < 0.05). Peak inspiratory pressure on PAV was significantly lower than on PSV (16 +/- 4 cm H(2)O vs. 21 +/- 3 cm H(2)O, respectively, P < 0.05). Hemodynamics and oxygenation remained unchanged. CONCLUSIONS: PAV is a feasible method for supporting ventilator-dependent patients and was well tolerated. It can improve the breathing pattern and reduce inspiratory effort. At the same degree of respiratory muscle unloading, PAV can be implemented at much lower peak inspiratory pressure than PSV. It can also apply proportional pressure support according to the patients' ventilatory demand.

Aged↗

PubMed2002

[Epidemiological survey of the incidence of bronchial asthma in occupational populations in Beijing area].

OBJECTIVE: To investigate the correlation of asthma incidence with environmental pollution. METHODS: We performed stratified-cluster-disproportional-random-sampling survey in the occupational populations from 10 professional systems by using an uniform protocol, questionnaire and procedure in this multicenter study. Original data were processed and statistically analyzed with SPSS 8.0 for windows. Prevalence rates were compared by chi(2) test. RESULTS: A total of 50,558 people supposed to cover more than 200,000 staff and workers were sampled. Six hundred and thirty asthmatics were identified and the overall prevalence rate in Beijing area was 1.25%. The incidence of asthma in occupational populations from urban commercial and trade circles, common chemical plants, and a certain petrochemical works was 0.51%, 1.06% and 2.81% respectively. The morbidity of asthma in the latter two populations was significantly higher than that in peasants (0.43%) in the remote outskirts of Beijing city (P < 0.01). The relative risk (RR) of asthma incidence in occupational populations from the commercial and trade circles, common chemical plants, the petrochemical works and the students in elementary and middle schools was 1.88, 2.79, 5.19 and 3.05 respectively as compared to peasants, the differences being statistically significant. CONCLUSION: The results suggest that the difference in asthma incidence in occupational populations may be attributable to environmental pollution.

Adolescent↗