Preconditioning of the ischaemic myocardium is reversed by methylene blue; further evidence for the role of cGMP?

A bolus injection of methylene blue (1 mg), a guanylate cyclase inhibitor, or aspirin (3 mg) in the isolated rat lung preparation had little or no effect on resting perfusion pressure under normoxic condition. In contrast, methylene blue markedly potentiated hypoxic vasopressor response (4-fold) when injected before or during the alveolar hypoxic stimulation. Hemoglobin also potentiated the hypoxic pressor response. Similarly, methylene blue or aspirin augmented the pressor responses to angiotensin II (0.1–1 microgram). The increased hypoxic response induced by methylene blue was immediate and sustained. Methylene blue, when added during hypoxia in the presence of aspirin, further augmented the response to hypoxia compared with the enhanced hypoxic response observed with aspirin alone. Our results suggest that, in addition to the role of cyclooxygenase products, the pulmonary vascular bed may be regulated by endothelium-dependent factors that can be antagonized directly or indirectly by methylene blue.

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Endometrial evaluation with methylene blue staining in patients with normal hysteroscopy

International Journal of Reproduction Contraception Obstetrics and Gynecology ◽

10.18203/2320-1770.ijrcog20193031 ◽

2019 ◽

Vol 8 (7) ◽

pp. 2715

Author(s):

Alka Goel ◽

Pooja Gupta ◽

Akansha Singh ◽

Khushboo Singh

Keyword(s):

Methylene Blue ◽

Pregnancy Loss ◽

Recurrent Pregnancy Loss ◽

Blue Staining ◽

False Negatives ◽

Normal Endometrium ◽

Significant Difference ◽

History Of ◽

Dark Blue

Background: Normally, endometrium comprises of non-absorptive epithelium and does not take up stain. Conventional staining with methylene blue is explained on the basis of existence of apoptotic cells in endometrium.Methods: Of 50 patients of unexplained infertility, AUB, recurrent pregnancy loss were randomly selected and included in the study. Those with abnormal ultrasound and history of tuberculosis were excluded. Conventional hysteroscopy was performed using normal saline as distending medium and in those with grossly normal endometrium were subjected to staining with 5% methylene blue instilled trans cervically. After 5 min, irrespective of the size and pattern, focal dark blue stained areas were considered abnormal and randomly biopsied. Incidence of endometritis in both groups was compared after histopathological examination.Results: Of total 50 patients, histopathological report of only one patient with dark blue staining had evidence of endometritis. Rest had no evidence, of which 73.5% had light blue or unstained areas and 26.5% showed dark blue staining. No statistically significant difference was found between histopathological reports and light or dark blue staining (p=0.28). When percentage stained area was considered more than 50% only to be positive, sensitivity was 100%, specificity 94%, PPV 25% and NPV 100%. False positives were 75% and no false negatives were observed. Although p values improved but still statistically insignificant.Conclusions: Present study failed to establish any significant correlation between staining pattern and detection rate of endometritis. With no Indian studies published on chromohysteroscopy so far, role of methylene blue in detection of subtle endometrial changes in modern gynaecology in Indian subpopulation is yet to be established.

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Uptake of Methylene Blue from Aqueous Solution by Pectin–Chitosan Binary Composites

Journal of Composites Science ◽

10.3390/jcs4030095 ◽

2020 ◽

Vol 4 (3) ◽

pp. 95

Author(s):

Dexu Kong ◽

Lee D. Wilson

Keyword(s):

Methylene Blue ◽

Aqueous Media ◽

Dye Adsorption ◽

Adsorption Properties ◽

Point Of Zero Charge ◽

Cross Linking ◽

Gravimetric Analysis ◽

Adsorption Sites ◽

Biopolymer Composites

To address the need to develop improved hybrid biopolymer composites, we report on the preparation of composites that contain chitosan and pectin biopolymers with tunable adsorption properties. Binary biopolymer composites were prepared at variable pectin–chitosan composition in a solvent directed synthesis, dimethyl sulfoxide (DMSO) versus water. The materials were characterized using complementary methods (infrared spectroscopy, thermal gravimetric analysis, pH at the point-of-zero charge, and dye-based adsorption isotherms). Pectin and chitosan composites prepared in DMSO yielded a covalent biopolymer framework (CBF), whereas a polyelectrolyte complex (PEC) was formed in water. The materials characterization provided support that cross-linking occurs between amine groups of chitosan and the –COOH groups of pectin. CBF-based composites had a greater uptake of methylene blue (MB) dye over the PEC-based composites. Composites prepared in DMSO were inferred to have secondary adsorption sites for enhanced MB uptake, as evidenced by a monolayer uptake capacity that exceeded the pectin–chitosan PECs by 1.5-fold. This work provides insight on the role of solvent-dependent cross-linking of pectin and chitosan biopolymers. Sonication-assisted reactions in DMSO favor CBFs, while cross-linking in water yields PECs. Herein, composites with tunable structures and variable physicochemical properties are demonstrated by their unique dye adsorption properties in aqueous media.

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A Study on the Potential Role of Occlusal Fissure Fractures in the Etiopathogenesis of Equine Cheek Teeth Apical Infections

Journal of Veterinary Dentistry ◽

10.1177/0898756419894653 ◽

2019 ◽

Vol 36 (3) ◽

pp. 171-178 ◽

Cited By ~ 2

Author(s):

Katherina Y. Wellman ◽

Padraic M. Dixon

Keyword(s):

Computed Tomography ◽

Methylene Blue ◽

Potential Role ◽

Histological Study ◽

Extraction Process ◽

Dental Tissue ◽

Rule Out

Thirty-nine equine cheek teeth diagnosed as having anachoretic apical infections and also having occlusal fissure fractures, but without occlusal pulpar exposure, that had been orally extracted without causing occlusal damage and 10 control teeth were used in this study. The teeth were individually imaged by computed tomography, occlusally stained with methylene blue and visually reexamined, then sectioned subocclusally at 5 mm intervals until the fissure fractures could no longer be detected. A limited histological study was then performed on 7 apically infected and 5 control teeth. Standard computed tomography only detected 1 of 39 fissure fractures. Thirteen of the 39 stained teeth had subocclusal fissure fractures visually identified at approximately 6 mm beneath the surface, and in 9 of these 13 teeth the fissure fractures had deeper staining to a level immediately above or into a pulp horn, indicating a potential route for bacterial pulpitis. However, the current study cannot rule out the possibility that the extraction process, long-term formalin storage, or the processing of teeth may have allowed for deeper staining. Additionally, methylene blue may penetrate dental tissue more readily than bacteria can invade. Further studies on the potential role of fissure fractures in the etiopathogenesis of cheek teeth apical infection are warranted.

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