11 research outputs found
Quantification of Antibiotic in Biofilm-Inhibiting Multilayers by 7.87 eV Laser Desorption Postionization MS Imaging
The potential of laser desorption postionization mass spectrometry (LDPI-MS) imaging for small molecule quantification is demonstrated here. The N-methylpiperazine acetamide (MPA) of ampicillin was adsorbed into polyelectrolyte multilayer surface coatings composed of chitosan and alginate, both high molecular weight biopolymers. These MPA-ampicillin spiked multilayers were then shown to inhibit the growth of Enterococcus faecalis biofilms that play a role in early stage infection of implanted medical devices. Finally, LDPI-MS imaging using 7.87 eV single photon ionization was found to detect MPA-ampicillin within the multilayers before and after biofilm growth with limits of quantification and detection of 0.6 and 0.3 nmol, respectively. The capabilities of LDPI-MS imaging for small molecule quantification are compared to those of MALDI-MS. Furthermore, these results indicate that 7.87 eV LDPI-MS imaging should be applicable to quantification of a range of small molecular species on a variety of complex organic and biological surfaces. Finally, while MS imaging for quantification was demonstrated here using LDPI, it is a generally useful strategy that can be applied to other methods
Estrogen-Induced Apoptosis of Breast Epithelial Cells Is Blocked by NO/cGMP and Mediated by Extranuclear Estrogen Receptors
Estrogen action, via both nuclear and extranuclear estrogen receptors (ERs), induces a variety of cellular signals that are prosurvival or proliferative, whereas nitric oxide (NO) can inhibit apoptosis
via caspase S-nitrosylation and via activation of soluble guanylyl cyclase to produce cGMP. The action of 17β-estradiol (E2) at ER is known to elicit NO signaling via activation of NO synthase (NOS) in many tissues. The MCF-10A nontumorigenic, mammary epithelial cell line is genetically stable
and insensitive to estrogenic proliferation. In this cell line, estrogens or NOS inhibitors alone had no significant effect, whereas in combination, apoptosis was induced rapidly in the absence of serum; the presence of inducible NOS was confirmed by proteomic analysis. The application of pharmacological agents determined that apoptosis was dependent upon NO/cGMP signaling via
cyclic GMP (cGMP)-dependent protein kinase and could be replicated by inhibition of the phosphatidylinositol 3 kinase/serine-threonine kinase pathway prior to addition of E2. Apoptosis was confirmed by nuclear staining and increased caspase-3 activity in E2 NOS inhibitor-treated cells.
Apoptosis was partially inhibited by a pure ER antagonist and replicated by agonists selective for extranuclear ER. Cells were rescued from E2-induced apoptosis after NOS blockade, by NO-donors and cGMP pathway agonists; preincubation with NO donors was required. The NOS and ER status of breast cancer tissues is significant in etiology, prognosis, and therapy. In this study, apoptosis of preneoplastic mammary epithelial cells was triggered by estrogens via a rapid, extranuclear ER-mediated response, after removal of an antiapoptotic NO/cGMP/cGMP-dependent protein kinase signal. (Endocrinology 151: 5602–5616, 2010
Derivatization of Surface-Bound Peptides for Mass Spectrometric Detection via Threshold Single Photon Ionization
Quantification of Antibiotic in Biofilm-Inhibiting Multilayers by 7.87 eV Laser Desorption Postionization MS Imaging
The potential of laser desorption postionization mass
spectrometry
(LDPI-MS) imaging for small molecule quantification is demonstrated
here. The <i>N</i>-methylpiperazine acetamide (MPA) of ampicillin
was adsorbed into polyelectrolyte multilayer surface coatings composed
of chitosan and alginate, both high molecular weight biopolymers.
These MPA-ampicillin spiked multilayers were then shown to inhibit
the growth of Enterococcus faecalis biofilms that play a role in early stage infection of implanted
medical devices. Finally, LDPI-MS imaging using 7.87 eV single-photon
ionization was found to detect MPA-ampicillin within the multilayers
before and after biofilm growth with limits of quantification and
detection of 0.6 and 0.3 nmol, respectively. The capabilities of LDPI-MS
imaging for small molecule quantification are compared to those of
MALDI-MS. Furthermore, these results indicate that 7.87 eV LDPI-MS
imaging should be applicable to quantification of a range of small
molecular species on a variety of complex organic and biological surfaces.
Finally, while MS imaging for quantification was demonstrated here
using LDPI, it is a generally useful strategy that can be applied
to other methods
Raloxifene and Desmethylarzoxifene Block Estrogen- Induced Malignant Transformation of Human Breast Epithelial Cells
There is association between exposure to estrogens and the development and progression of hormone-dependent gynecological cancers. Chemical carcinogenesis by catechol estrogens derived from oxidative metabolism is thought to
contribute to breast cancer, yet exact mechanisms remain elusive. Malignant transformation was studied in MCF-10A
human mammary epithelial cells, since estrogens are not proliferative in this cell line. The human and equine estrogen
components of estrogen replacement therapy (ERT) and their catechol metabolites were studied, along with the influence of co-administration of selective estrogen receptor modulators (SERMs), raloxifene and desmethyl-arzoxifene (DMA), and
histone deacetylase inhibitors. Transformation was induced by human estrogens, and selectively by the 4-OH catechol metabolite, and to a lesser extent by an equine estrogen metabolite. The observed estrogen-induced upregulation of
CYP450 1B1 in estrogen receptor negative MCF-10A cells, was compatible with a causal role for 4-OH catechol estrogens, as was attenuated transformation by CYP450 inhibitors. Estrogen-induced malignant transformation was blocked by SERMs
correlating with a reduction in formation of nucleobase catechol estrogen (NCE) adducts and formation of 8-oxo-dG. NCE
adducts can be formed consequent to DNA abasic site formation, but NCE adducts were also observed on incubation of
estrogen quinones with free nucleotides. These results suggest that NCE adducts may be a biomarker for cellular electrophilic stress, which together with 8-oxo-dG as a biomarker of oxidative stress correlate with malignant transformation
induced by estrogen oxidative metabolites. The observed attenuation of transformation by SERMs correlated with these biomarkers and may also be of clinical significance in breast cancer chemoprevention
Quantification of Antibiotic in Biofilm-Inhibiting Multilayers by 7.87 eV Laser Desorption Postionization MS Imaging
The potential of laser desorption postionization mass spectrometry (LDPI-MS) imaging for small molecule quantification is demonstrated here. The N-methylpiperazine acetamide of (MPA) ampicillin was adsorbed into polyelectrolyte multilayer surface coatings composed of chitosan and alginate, both high molecular weight biopolymers. These MPA-ampicillin spiked multilayers were then shown to inhibit the growth of E. faecalis biofilms that play a role in early stage infection of implanted medical devices. Finally, LDPI-MS imaging using 7.87 eV single photon ionization was found to detect MPA-ampicillin with the multilayers before and after biofilm growth with limits of quantification and detection of 0.6 and 0.3 nmoles, respectively. The capabilities of LDPI-MS imaging for small molecule quantification are compared to those of MALDI-MS. Furthermore, these results indicate that 7.87 eV LDPI-MS imaging should be applicable to quantification of a range of small molecular species on a variety of complex organic and biological surfaces. Finally, while MS imaging for quantification was demonstrated here using LDPI, it is a generally useful strategy that can be applied to other methods