Biomedical subjects

Albert P Senft

Publications and source records attributed to Albert P Senft.

7 recordsLinked to original sources

PubMed2006

Altered postnatal lung development in C3H/HeJ mice.

C3H/HeJ mice develop an increase in terminal air space area detectable by postnatal d 14 that persists into adulthood compared with strain-matched controls (C3H/SnJ, C3H/OuJ). Morphometric quantification revealed a 50% increase in terminal air space area by postnatal d 14 and a 2.3-fold increase by 2 mo of age in C3H/HeJ mice. Bacteriologic cultures obtained from the left lung on postnatal d 7 revealed > 100 colony-forming units (CFU)/left lung of predominantly Gram-negative bacteria (GNB) (Escherichia coli and Proteus mirabilis) in 13 of the 14 C3H/HeJ mice compared with 0 of 12 controls demonstrating colonization of the developing lung in C3H/HeJ mice. An approximately threefold increase in macrophages from bronchoalveolar lavage, threefold increases in matrix metalloproteinase 12 (MMP-12) mRNA and protein levels and elevated levels of proinflammatory cytokines monocyte chemoattractant protein (MCP-1) and keratinocyte-derived cytokine (KC) were also found. P. mirabilis obtained from lung cultures in C3H/HeJ mice induced nuclear factor-kappaB (NF-kappaB) activation in human embryonic kidney 293 (HEK 293) cells transfected with TLR5. In C3H/HeJ mice lacking TLR4 signaling, bacterial colonization is associated with chronic inflammation and permanent changes in lung morphology.

Animals↗

PubMed2006

Surfactant protein D regulates the cell surface expression of alveolar macrophage beta(2)-integrins.

The beta(2)-integrin receptors (CD11a/CD18, CD11b/CD18, and CD11c/CD18) are expressed on the surface of alveolar macrophages and are important for the phagocytic clearance of pathogens. In the present study, we demonstrate that surfactant protein D (SP-D) modulates surface expression of CD11b and CD11c, but not CD11a or CD18, on alveolar macrophages. While cell surface receptors were reduced, CD11b and CD11c mRNAs were increased by SP-D deficiency. CCSP-rtTA(+)/(tetO)(7)-rSPD(+)/SP-D(-/-) mice, which conditionally express SP-D in the lung, were used to study the kinetics and reversibility of beta(2)-integrin receptors in response to changes in alveolar SP-D. Surface CD11b and CD11c were reduced on the alveolar macrophages within 3 days of SP-D deficiency and were restored with 3 days for CD11b and 7 days for CD11c of repletion of SP-D. SP-D deficiency caused a loss of cellular CD11b and CD11c content, indicating that the decrease in total cell content of the receptors was related to degradation rather than to redistribution of the receptor within the macrophage. CD11b and CD11c staining colocalized with Lamp-1 during SP-D deficiency, supporting the concept that reduced macrophage receptor levels resulted from increased lysosomal trafficking. Hydroxychloroquine, a lysomotropic agent, prevented the reduction of cellular and surface CD11b and CD11c. SP-D regulates surface CD11b and CD11c levels on the alveolar macrophage by modulating receptor trafficking, providing a mechanism by which SP-D mediates phagocytic activity in the alveolar macrophage.

Animals↗

PubMed2005

Surfactant protein-D regulates soluble CD14 through matrix metalloproteinase-12.

Surfactant protein D (SP-D) and CD14 are important innate immune defense molecules that mediate clearance of pathogens and apoptotic cells from the lung. To test whether CD14 expression and function were influenced by SP-D, the surface expression of CD14 was assessed on alveolar macrophages from SP-D-/- mice. CD14 was reduced on alveolar macrophages from SP-D-/- mice and was associated with reduced uptake of LPS and decreased production of TNF-alpha after LPS stimulation. CD14 is proteolytically cleaved from the cell surface to form a soluble peptide. Soluble CD14 (sCD14) was increased in the bronchoalveolar lavage fluid from SP-D-/- mice. Because matrix metalloproteinase (MMP)-9 and -12 activities were increased in the lungs of SP-D-/- mice, the role of these metalloproteases in the production of sCD14 was assessed. sCD14 was decreased in both MMP(9-/-)/SP-D-/- and MMP12(-/-)/SP-D-/- mice demonstrating MMP-9 and MMP-12 contribute to proteolytic shedding of CD14. The increased sCD14 seen in SP-D-/- mice was dependent upon the activation of MMP-12 via an MMP-9-dependent mechanism. Supporting this observation, MMP-12 caused the release of sCD14 from RAW 264.7 cells in vitro. In conclusion, SP-D influences innate host defense, in part, by regulating sCD14 in a process mediated by MMP-9 and MMP-12.

Animals↗

PubMed2005

Basic molecular biology.

Rapid advances in molecular biology over the past 20 years have and will continue to impact on the practice of medicine. Advances in molecular biology are having an immense impact in determining the underlying aetiology of lung disease and its treatment. In this review, basic molecular biology techniques will be discussed with examples of how these techniques are used in clinical practice.

Blotting, Northern↗

PubMed2003

Antioxidant perturbations in the olfactory mucosa of alachlor-treated rats.

The chloracetanilide herbicide alachlor (2-chloro-2',6'-diethyl-N-(methoxymethyl)acetanilide) induces olfactory mucosal tumors in rats following chronic dietary exposure. Previous reports demonstrated that alachlor exposure was associated with depletion of glutathione (GSH) in liver in vivo and in vitro, but did not address this issue in the target tissue for the carcinogenic response. In this study we investigated a potential oxidative stress pathway in olfactory tissue by examining perturbations in olfactory mucosal antioxidants. Male Long-Evans rats were fed alachlor for up to 10 days (10-126 mg/kg per day), and intracellular reduced GSH and ascorbate levels were measured in olfactory mucosa. Both GSH and ascorbate rapidly decreased in olfactory mucosa following alachlor exposure, with a subsequent increase in both antioxidants to approximately 160% of control levels in the high dose group, and recovery of GSH to control levels in all groups by 10 days. Using Western blot analysis, we found that the modifier subunit of the rate-limiting enzyme in GSH synthesis, glutamate-cysteine ligase, increased in olfactory mucosa and remained elevated (126 mg/kg per day group). Two ascorbate transporters were detected by RT-PCR in olfactory mucosa, but neither appeared to be upregulated by alachlor exposure, and ascorbate synthesis was not stimulated in olfactory mucosa by alachlor treatment. Dietary exposure to alachlor depletes olfactory mucosa antioxidants, which may contribute to DNA damage and tissue-specific tumor formation.

Acetamides↗

PubMed2002

Mitochondrial reactive oxygen production is dependent on the aromatic hydrocarbon receptor.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (dioxin; TCDD) is a pervasive environmental contaminant that induces hepatic and extrahepatic oxidative stress. We have previously shown that dioxin increases mitochondrial respiration-dependent reactive oxygen production. In the present study we examined the dependence of mitochondrial reactive oxygen production on the aromatic hydrocarbon receptor (AHR), cytochrome P450 1A1 (CYP1A1), and cytochrome P450 1A2 (CYP1A2), proteins believed to be important in dioxin-induced liver toxicity. Congenic Ahr(-/-), Cyp1a1(-/-) and Cyp1a2(-/-) knockout mice, and C57BL/6J inbred mice as their Ahr/Cyp1a1/Cyp1a2(+/+) wild-type (wt) counterparts, were injected intraperitoneally with dioxin (15 microg/kg body weight) or corn-oil vehicle on 3 consecutive days. Liver mitochondria were examined 1 week following the first treatment. The level of mitochondrial H(2)O(2) production in vehicle-treated Ahr(-/-) mice was one fifth that found in vehicle-treated wt mice. Whereas dioxin caused a rise in succinate-stimulated mitochondrial H(2)O(2) production in the wt, Cyp1a1(-/-), and Cyp1a2(-/-) mice, this increase did not occur with the Ahr(-/-) knockout. The lack of H(2)O(2) production in Ahr(-/-) mice was not due to low levels of Mn(2+)-superoxide dismutase (SOD2) as shown by Western immunoblot analysis, nor was it due to high levels of mitochondrial glutathione peroxidase (GPX1) activity. Dioxin decreased mitochondrial aconitase (an enzyme inactivated by superoxide) by 44% in wt mice, by 26% in Cyp1a2(-/-) mice, and by 24% in Cyp1a1(-/-) mice; no change was observed in Ahr(-/-) mice. Dioxin treatment increased mitochondrial glutathione levels in the wt, Cyp1a1(-/-), and Cyp1a2(-/-) mice, but not in Ahr(-/-) mice. These results suggest that both constitutive and dioxin-induced mitochondrial reactive oxygen production is associated with a function of the AHR, and these effects are independent of either CYP1A1 or CYP1A2.

Aconitate Hydratase↗

PubMed2002

Dioxin increases reactive oxygen production in mouse liver mitochondria.

Dioxin (2,3,7,8-tetrachlorodibenzo-p-dioxin; TCDD) causes an oxidative stress response in liver and several extrahepatic tissues. The subcellular sources and underlying mechanisms of dioxin-induced reactive oxygen, however, are not well understood. In this study, we examined whether mitochondria, organelles that consume the majority of cellular oxygen, might be a source of dioxin-induced reactive oxygen. Female C57BL/6 mice were treated with dioxin (15 microg/kg body wt ip) on 3 consecutive days, and liver mitochondria were examined at 1, 4, and 8 weeks after the first treatment. Mitochondrial aconitase activity, an enzyme inactivated by superoxide, was decreased by 44% at 1 week, 22% at 4 weeks, and returned to control levels at 8 weeks. Dioxin elevated succinate-stimulated mitochondrial H2O2 production twofold at 1 and 4 weeks; H2O2 production remained significantly elevated at 8 weeks. The enhanced H2O2 production was due to neither increased Mn-superoxide dismutase activity nor decreased mitochondrial glutathione peroxidase activity. Dioxin treatment augmented mitochondrial glutathione, but not glutathione disulfide levels, a result that might be explained by increased mitochondrial glutathione reductase activity. Liver ATP levels were significantly lowered at 1 and 4 weeks, the peak times of mitochondrial reactive oxygen production. Increased dioxin-stimulated reactive oxygen at 1 and 4 weeks did not appear to be related to the observed decrease in cytochrome oxidase activity, since State 3 and State 4 respiration were not diminished. To our knowledge, this is the first report to show that dioxin increases mitochondrial respiration-dependent reactive oxygen production, which may play an important role in dioxin-induced toxicity and disease.

Aconitate Hydratase↗