Ultraviolet-A absorbance analysis in thin porcine corneas pre-and post-crosslinking.

Purpose: To determine the absorbance coefficient of the thin porcine cornea to ultraviolet-A radiation (365 nm) submitted for crosslinking.

Methods: This in vitro, benchtop experiment using cadaver tissue study analyzed 12 porcine corneal lamellas, which were obtained using a microkeratome after mechanical de-epithelization and separated into three thickness groups: 180, 300, and 360 μm. The corneal thickness values were measured by anterior-segment optical coherence tomography.

A novel metalloproteinase-derived cryptide from Bothrops cotiara venom inhibits angiotensin-converting enzyme activity.

Snake venoms are primarily composed of proteins and peptides, which selectively interact with specific molecular targets, disrupting prey homeostasis. Identifying toxins and the mechanisms involved in envenoming can lead to the discovery of new drugs based on natural peptide scaffolds. In this study, we used mass spectrometry-based peptidomics to sequence 197 peptides in the venom of Bothrops cotiara, including a novel 7-residue peptide derived from a snake venom metalloproteinase.

Spectrophotometric Analysis of Different Polymethyl Methacrylate Filters and their Importance in the Implantation of Corneal Rings.

Purpose: This study evaluated the luminous behavior applied to materials used in intraocular surgeries.

Methods: Discs of the different products were delivered in 19.00 mm × 3.

Biocompatibility of polyvinyl alcohol/trisodium trimetaphosphate as vitreous substitute in experimental vitrectomy model in rabbits.

Synthetic hydrogels have been proposed as vitreous substitutes recently. This study aims to evaluate the biocompatibility of polyvinyl alcohol (PVA) crosslinked with trisodium trimetaphosphate (SMTP) hydrogel in rabbit vitrectomized eyes. Seven animals were submitted to pars plana vitrectomy and the vitreous was replaced by PVA/SMTP hydrogel.

Characterization of PVA/glutaraldehyde hydrogels obtained using Central Composite Rotatable Design (CCRD).

Hydrogels are made from natural or synthetic polymers and, currently, they have many biomedical applications. In this work, the conditions for obtaining a hydrogel with similar physicochemical characteristics to the vitreous humor were defined using polyvinyl alcohol (PVA) and glutaraldehyde (GLUT) as cross-linker. The concentration of PVA and GLUT were modified, and their effect was analyzed in terms of the refractive index, density, and dynamic viscosity.

Paramagnetic bradykinin analogues as substrates for angiotensin I-converting enzyme: Pharmacological and conformation studies.

This study uses EPR, CD, and fluorescence spectroscopy to examine the structure of bradykinin (BK) analogues attaching the paramagnetic amino acid-type Toac (2,2,6,6-tetramethylpiperidine-1-oxyl-4-amino-4-carboxylic acid) at positions 0, 3, 7, and 9. The data were correlated with the potencies in muscle contractile experiments and the substrate properties towards the angiotensin I-converting enzyme (ACE). A study of the biological activities in guinea pig ileum and rat uterus indicated that only Toac-BK partially maintained its native biological potency among the tested peptides.

Conditions for obtaining polyvinyl alcohol/trisodium trimetaphosphate hydrogels as vitreous humor substitute.

Hydrogels are polymeric materials with numerous medical and biological applications because of their physicochemical properties. In this context, the conditions were defined for obtaining a hydrogel with characteristics similar to the vitreous humor using polyvinyl alcohol (PVA) and trisodium trimetaphosphate (STMP). The concentration of PVA (X1 ), PVA/STMP ratio (X2 ), and initial pH (X3 ) were modified, and their effect was analyzed in terms of the refractive index (Y1 ), density (Y2 ), dynamic viscosity (Y3 ), and final pH (Y4 ).

Angiotensin-converting enzyme in pericardial fluid: comparative study with serum activity.

Background: The characterization of an angiotensin-converting enzyme (ACE) in human pericardial fluid is relevant, considering its role in the angiotensin II release and thus, the role of the pericardium in cardiovascular homeostasis.

Objective: To isolate and characterize an ACE from human pericardial fluid and to compare the angiotensin I converting activities of the pericardial fluid with that of the serum in patients submitted to cardiovascular surgery.

Methods: The enzyme from human pericardial fluid was purified through chromatographic steps and characterized by polyacrylamide gel electrophoresis (SDS-PAGE), hydrolysis of angiotensin I, bradykinin, Hip-His-Leu and synthetic substrates with internal fluorescence suppression.

Analogues containing the paramagnetic amino acid TOAC as substrates for angiotensin I-converting enzyme.

The angiotensin I-converting enzyme (ACE) converts the decapeptide angiotensin I (Ang I) into angiotensin II by releasing the C-terminal dipeptide. A novel approach combining enzymatic and electron paramagnetic resonance (EPR) studies was developed to determine the enzyme effect on Ang I containing the paramagnetic 2,2,6,6-tetramethylpiperidine-1-oxyl-4-amino-4-carboxylic acid (TOAC) at positions 1, 3, 8, and 9. Biological assays indicated that TOAC(1)-Ang I maintained partly the Ang I activity, and that only this derivative and the TOAC(3)-Ang I were cleaved by ACE.