Potential of Chitosan for the Control of Powdery Mildew (Leveillula taurica (Lév.) Arnaud) in a Jalapeño Pepper (Capsicum annuum L.) Cultivar.

One of the phytopathogens that cause severe damage to jalapeño pepper is Leveillula taurica (Lév.) Arnaud, the causative agent of powdery mildew. Synthetic fungicides are currently employed for its control, contributing to adverse effects on human health and the environment. The main objective of this research was to identify the causal agent of powdery mildew and assess the efficacy of chitosan in powdery mildew control on jalapeño pepper. The following treatments were evaluated in laboratory and greenhouse conditions: T1 = 0.0125% chitosan, T2 = 0.0025% chitosan, T3 = 0.05% chitosan, T4 = 0.1% chitosan, T5 = 0.2% chitosan, T6 = tebuconazole 25% (1.8 mL/L water), and T7 = control (water). Symptomatology results indicated that L. taurica is indeed the causative agent of powdery mildew. Treatments T4 and T5 exhibited the lowest percentages of incidences and severity, hence achieving higher control efficacy in the laboratory (57.70 ± 3.85 and 65.39 ± 3.85) and greenhouse (56.67 ± 4.08 and 70 ± 8.16%) compared to T6 (control efficacy, 38.46 ± 0.00% in the laboratory and 50 ± 0.00% in the greenhouse). The chitosan derived from shrimp had a significant impact on the cell walls of L. taurica spores and mycelium. Consequently, chitosan emerges as a viable organic alternative to fungicides for controlling powdery mildew in jalapeño pepper.

Physalis virginiana as a Wild Field Host of Bactericera cockerelli (Hemiptera: Triozidae) and 'Candidatus Liberibacter solanacearum'.

The potato/tomato psyllid, Bactericera cockerelli (Sulc), is among the most important pests of solanaceous crops as a vector of the pathogen 'Candidatus Liberibacter solanacearum' (Lso). Lso-infected psyllids often arrive in crop fields from various wild species of Solanaceae and Convolvulaceae, especially those that provide early-season hosts for the vector. Physalis species are perennial plants within the family Solanaceae with often broad geographical distributions that overlap those of B. cockerelli, yet the status of many Physalis species as hosts for B. cockerelli or Lso remains unknown. Our objective was to determine whether wild Physalis species that occur in the potato-growing region of Galeana, Nuevo León, Mexico, host B. cockerelli populations and whether they also are susceptible to Lso. Sampling was carried out in the potato-growing zone of Galeana, Nuevo León, Mexico, where unidentified Physalis spp. are common. In March to October 2021, a wild plant identified as Physalis virginiana was observed; eggs, nymphs, and adults of B. cockerelli were observed on these plants throughout the growing season, and nymphs completed development on these plants under laboratory conditions. Lso also was detected in 22 of the 93 (23.7%) wild P. virginiana plants using conventional PCR, while 13.3% of B. cockerelli adults that emerged from P. virginiana cuttings harbored the pathogen. This is the first report that P. virginiana is a host for B. cockerelli and for Lso. These results suggest that P. virginiana is a likely source of Lso-infected psyllids colonizing solanaceous crops in northeastern Mexico. The importance of P. virginiana and other wild hosts on the population dynamics of the vector and pathogen should be investigated to assist in pest management decision-making.

Impact of Sustained Fructose Consumption on Gastrointestinal Function and Health in Wistar Rats: Glycoxidative Stress, Impaired Protein Digestion, and Shifted Fecal Microbiota.

The gastrointestinal tract (GIT) is the target of assorted pathological conditions, and dietary components are known to affect its functionality and health. In previous in vitro studies, we observed that reducing sugars induced protein glycoxidation and impaired protein digestibility. To gain further insights into the pathophysiological effects of dietary sugars, Wistar rats were provided with a 30% (w/v) fructose water solution for 10 weeks. Upon slaughter, in vivo protein digestibility was assessed, and the entire GIT (digests and tissues) was analyzed for markers of oxidative stress and untargeted metabolomics. Additionally, the impact of sustained fructose intake on colonic microbiota was also evaluated. High fructose intake for 10 weeks decreased protein digestibility and promoted changes in the physiological digestion of proteins, enhancing intestinal digestion rather than stomach digestion. Moreover, at colonic stages, the oxidative stress was harmfully increased, and both the microbiota and the intraluminal colonic metabolome were modified.

The Contribution of TRPA1 to Corneal Thermosensitivity and Blink Regulation in Young and Aged Mice.

The role of TRPA1 in the thermosensitivity of the corneal cold thermoreceptor nerve endings was studied in young and aged mice. The contribution of the TRPA1-dependent activity to basal tearing and thermally-evoked blink was also explored. The corneal cold thermoreceptors' activity was recorded extracellularly in young (5-month-old) and aged (18-month-old) C57BL/6WT (WT) and TRPA1-/- knockout (TRPA1-KO) mice at basal temperature (34 °C) and during cooling (15 °C) and heating (45 °C) ramps. The blink response to cold and heat stimulation of the ocular surface and the basal tearing rate were also measured in young animals using orbicularis oculi muscle electromyography (OOemg) and phenol red threads, respectively. The background activity at 34 °C and the cooling- and heating-evoked responses of the cold thermoreceptors were similar in WT and TRPA1-KO animals, no matter the age. Similar to the aged WT mice, in the young and aged TRPA1-KO mice, most of the cold thermoreceptors presented low frequency background activity, a low cooling threshold, and a sluggish response to heating. The amplitude and duration of the OOemg signals correlated with the magnitude of the induced thermal change in the WT but not in the TRPA1-KO mice. The basal tearing was similar in the TRPA1-KO and WT mice. The electrophysiological data suggest that the TRPA1-dependent nerve activity, which declines with age, contributes to detecting the warming of the ocular surface and also to integrating the thermally-evoked reflex blink.

Cyclosporine A Decreases Dryness-Induced Hyperexcitability of Corneal Cold-Sensitive Nerve Terminals.

Cyclosporine A (CsA) is used for the treatment of dry eye (DE) with good clinical results, improving tear secretion and decreasing subjective symptoms. These effects are attributed to the improved tear film dynamics, but there are no data on the effect of CsA on the abnormal sensory nerve activity characteristic in DE. Our purpose was to evaluate the CsA effect on the enhanced activity of corneal cold thermoreceptors in a tear-deficient DE animal model using in vitro extracellular recording of cold thermoreceptors nerve terminal impulses (NTIs) before and in the presence of CsA. NTI shape was also analyzed. Blinking frequency and tearing rate were also measured in awake animals before and after topical CsA. CsA increased the tearing and blinking of treated animals. CsA significantly decreased the peak response to cold of cold thermoreceptors. Neither their spontaneous NTIs discharge rate nor their cooling threshold were modified. CsA also seemed to reverse some of the changes in NTI shape induced by tear deficiency. These data suggest that, at least in part, the beneficial clinical effects of CsA in DE can be attributed to a direct effect on sensory nerve endings, although the precise mechanisms underlying this effect need further studies to be fully clarified.

Improved quality of life (EHP-30) in patients with endometriosis after surgical treatment.

OBJECTIVE: This study aimed to evaluate the quality of life of patients with endometriosis before and after surgical treatment. METHODS: An observational, longitudinal, and prospective study was conducted with 102 women with pelvic pain and endometriosis that was unimproved by clinical treatment and indicated for surgical treatment. The patients' quality of life was assessed using the 30-item Endometriosis Health Profile (EHP-30) questionnaire before and 3 and 6 months after surgery. The statistical tests were analyzed using the Statistical Package for Social Sciences version 17.0, and the Friedman test was used. RESULTS: There was a reduction in EHP-30 scores 3 and 6 months after surgery compared to before surgery, as well as 6 months after surgery compared to 3 months after surgery, in the central questionnaire (PART 1) and in Sections A, B, C, E, and F (p<0.0001). For Section D, there was a reduction in scores 6 months after surgery compared to before surgery (p<0.0001). CONCLUSION: Surgical treatment of endometriosis improves quality of life in several areas assessed by the EHP-30 questionnaire.

Biochemical and molecular confirmation of alkaptonuria in a Sumatran orangutan (Pongo abelii).

A 6-yr-old female orangutan presented with a history of dark urine that turned brown upon standing since birth. Repeated routine urinalysis and urine culture were unremarkable. Urine organic acid analysis showed elevation in homogentisic acid consistent with alkaptonuria. Sequence analysis identified a homozygous missense variant, c.1081G>A (p.Gly361Arg), of the homogentisate 1,2-dioxygenase (HGD) gene. Familial studies, molecular modeling, and comparison to human variant databases support this variant as the underlying cause of alkaptonuria in this orangutan. This is the first report of molecular confirmation of alkaptonuria in a nonhuman primate.

Improved quality of life (EHP-30) in patients with endometriosis after surgical treatment

SUMMARY OBJECTIVE: This study aimed to evaluate the quality of life of patients with endometriosis before and after surgical treatment. METHODS: An observational, longitudinal, and prospective study was conducted with 102 women with pelvic pain and endometriosis that was unimproved by clinical treatment and indicated for surgical treatment. The patients' quality of life was assessed using the 30-item Endometriosis Health Profile (EHP-30) questionnaire before and 3 and 6 months after surgery. The statistical tests were analyzed using the Statistical Package for Social Sciences version 17.0, and the Friedman test was used. RESULTS: There was a reduction in EHP-30 scores 3 and 6 months after surgery compared to before surgery, as well as 6 months after surgery compared to 3 months after surgery, in the central questionnaire (PART 1) and in Sections A, B, C, E, and F (p<0.0001). For Section D, there was a reduction in scores 6 months after surgery compared to before surgery (p<0.0001). CONCLUSION: Surgical treatment of endometriosis improves quality of life in several areas assessed by the EHP-30 questionnaire.

A clinically validated method to separate and quantify underivatized acylcarnitines and carnitine metabolic intermediates using mixed-mode chromatography with tandem mass spectrometry.

Acylcarnitines are intermediate metabolites of the mitochondria that serve as biomarkers for inherited disorders of fatty acid oxidation and amino acid metabolism. The prevailing clinical method used to quantify acylcarnitines involves flow-injection tandem mass spectrometry, an approach with a number of limitations; foremost the inability to separate and therefore distinguish key isobaric acylcarnitine species. To address these issues, we report a clinically validated liquid chromatography tandem mass spectrometry method to quantify acylcarnitines, free carnitine, and carnitine metabolic intermediates in human plasma. Importantly, this method resolves clinically relevant isobaric and isomeric acylcarnitine species in a single 22 min analysis without the use of ion pairing or derivatization reagents. This unique combination of features is not achievable by existing acylcarnitine methods and is made possible by the use of a novel mixed-mode chromatographic separation. Further clinical validation studies demonstrate excellent limits of quantification, linearity, accuracy, and inter-assay precision for analyses of 38 different calibrated analytes. An additional 28 analytes are semi-quantitatively analyzed using surrogate calibrators. The study of residual patient specimens confirms the clinical utility of this method and suggests expanded applicability to the diagnosis of peroxisomal disorders. In summary, we report a clinically validated acylcarnitine method that utilizes a novel mixed-mode chromatographic separation to provide a number of advantages in terms of specificity, accuracy, sample preparation time, and clinical utility.

Unilateral Corneal Insult Also Alters Sensory Nerve Activity in the Contralateral Eye.

After the unilateral inflammation or nerve lesion of the ocular surface, the ipsilateral corneal sensory nerve activity is activated and sensitized, evoking ocular discomfort, irritation, and pain referred to the affected eye. Nonetheless, some patients with unilateral ocular inflammation, infection, or surgery also reported discomfort and pain in the contralateral eye. We explored the possibility that such altered sensations in the non-affected eye are due to the changes in their corneal sensory nerve activity in the contralateral, not directly affected eye. To test that hypothesis, we recorded the impulse activity of the corneal mechano- and polymodal nociceptor and cold thermoreceptor nerve terminals in both eyes of guinea pigs, subjected unilaterally to three different experimental conditions (UV-induced photokeratitis, microkeratome corneal surgery, and chronic tear deficiency caused by removal of the main lacrimal gland), and in eyes of naïve animals ex vivo. Overall, after unilateral eye damage, the corneal sensory nerve activity appeared to be also altered in the contralateral eye. Compared with the naïve guinea pigs, animals with unilateral UV-induced mild corneal inflammation, showed on both eyes an inhibition of the spontaneous and stimulus-evoked activity of cold thermoreceptors, and increased activity in nociceptors affecting both the ipsilateral and the contralateral eye. Unilateral microkeratome surgery affected the activity of nociceptors mostly, inducing sensitization in both eyes. The removal of the main lacrimal gland reduced tear volume and increased the cold thermoreceptor activity in both eyes. This is the first direct demonstration that unilateral corneal nerve lesion, especially ocular surface inflammation, functionally affects the activity of the different types of corneal sensory nerves in both the ipsilateral and contralateral eyes. The mechanisms underlying the contralateral affectation of sensory nerves remain to be determined, although available data support the involvement of neuroimmune interactions. The parallel alteration of nerve activity in contralateral eyes has two main implications: a) in the experimental design of both preclinical and clinical studies, where the contralateral eyes cannot be considered as a control; and, b) in the clinical practice, where clinicians must consider the convenience of treating both eyes of patients with unilateral ocular conditions to avoid pain and secondary undesirable effects in the fellow eye.

Allysine and α-Aminoadipic Acid as Markers of the Glyco-Oxidative Damage to Human Serum Albumin under Pathological Glucose Concentrations.

Understanding the molecular basis of the disease is of the utmost scientific interest as it contributes to the development of targeted strategies of prevention, diagnosis, and therapy. Protein carbonylation is a typical feature of glyco-oxidative stress and takes place in health disorders such as diabetes. Allysine as well as its oxidation product, the α-amino adipic acid (α-AA) have been found to be markers of diabetes risk whereas little is known about the chemistry involved in its formation under hyperglycemic conditions. To provide insight into this issue, human serum albumin was incubated in the presence of FeCl3 (25 µM) and increasing glucose concentrations for 32 h at 37 °C. These concentrations were selected to simulate (i) physiological fasting plasma concentration (4 mM), (ii) pathological pre-diabetes fasting plasma concentration (8 mM), and pathological diabetes fasting plasma concentration (12 mM) of glucose. While both allysine and α-AA were found to increase with increasing glucose concentrations, the carboxylic acid was only detected at pathological glucose concentrations and appeared to be a more reliable indicator of glyco-oxidative stress. The underlying chemical mechanisms of lysine glycation as well as of the depletion of tryptophan and formation of fluorescent and colored advanced glycation products are discussed.

'Candidatus Liberibacter solanacearum' Infection of Physalis ixocarpa Brot. (Solanales: Solanaceae) in Saltillo, Mexico.

The potato psyllid Bactericera cockerelli (Sulc) (Hemiptera: Triozidae) is a pest of solanaceous crops (order Solanales), including potato (Solanum tuberosum L.) and tomato (S. lycopersicum L.). Feeding by high populations of nymphs causes psyllid yellows while adults and nymphs are vectors of the plant pathogen 'Candidatus Liberibacter solanacearum'. Foliar symptoms that were consistent with either 'Ca. L. solanacearum' infection or psyllid yellows were observed in 2019 on tomatillo (Physalis ixocarpa Brot.; family Solanaceae) grown within an experimental plot located near Saltillo, Mexico. This study had three primary objectives: 9i) determine whether the foliar symptoms observed on tomatillo were associated with 'Ca. L. solanacearum' infection, (ii) identify the haplotypes of 'Ca. L. solanacearum' and potato psyllids present in the symptomatic plot, and (iii) use gut content analysis to infer the plant sources of 'Ca. L. solanacearum'-infected psyllids. Results confirmed that 71% of symptomatic plants and 71% of psyllids collected from the plants were infected with 'Ca. L. solanacearum'. The detection of 'Ca. L. solanacearum' in plants and psyllids and the lack of nymphal populations associated with psyllid yellows strongly suggests that the observed foliar symptoms were caused by 'Ca. L. solanacearum' infection. All infected plants and insects harbored the more virulent 'Ca. L. solanacearum' haplotype B but one psyllid was also coinfected with haplotype A. The potato psyllids were predominantly of the central haplotype but one psyllid was identified as the western haplotype. Molecular gut content analysis of psyllids confirmed the movement of psyllids between noncrop habitats and tomatillo and indicated that 'Ca. L. solanacearum' infection of psyllids was associated with increased plant diversity in their diet.

Sodium Channel Blockers Modulate Abnormal Activity of Regenerating Nociceptive Corneal Nerves After Surgical Lesion.

Purpose: To test the effect of different sodium channel blockers on the electrical activity of corneal nociceptors in intact and surgically injured corneas. Methods: In anesthetized guinea pigs, a 4-mm diameter corneal flap was performed in one eye at a midstromal depth using a custom-made microkeratome. At different times after surgery (3 hours to 15 days), the electrical activity of corneal nociceptor fibers was recorded from ciliary nerve filaments in the superfused eye in vitro. Mechanical threshold was measured using calibrated von Frey hairs; chemical stimulation was performed applying 30-second CO2 gas pulses. The characteristics of the spontaneous and stimulus-evoked activity of corneal nociceptors recorded from intact and lesioned corneas, before and after treatment with the sodium channel blockers lidocaine, carbamazepine, and amitriptyline, were compared. Results: No spontaneous or stimulus-evoked impulse activity was detected inside the flap at any of the studied time points. However, both were recorded from mechanonociceptor and polymodal nociceptors fibers in the surrounding corneal tissue, being significantly higher (sensitization) 24 to 48 hours after surgery. In these fibers, none of the tested drugs affected mechanical threshold, but they significantly reduced the CO2 response of polymodal nociceptors of intact and injured corneas. Likewise, they diminished significantly the transient increase in spontaneous and stimulus-evoked activity of sensitized polymodal nociceptors. Conclusions: Na+ channel blockers decrease the excitability of intact and sensitized corneal nociceptor fibers, thus acting as potential tools to attenuate their abnormal activity, which underlies the spontaneous pain, hyperalgesia, and allodynia often accompanying surgical corneal lesions, as occurs after photorefractive surgery.

Formation of allysine in ß-lactoglobulin and myofibrillar proteins by glyoxal and methylglyoxal: Impact on water-holding capacity and in vitro digestibility.

The ability of α-dicarbonyls, glyoxal (GO) and methyl-glyoxal (MGO) (2 M), to induce the formation of allysine in ß-lactoglubulin (LAC), and myofibrillar proteins (MP) (2 mg/mL) during incubation at 80 °C for 48 h, was studied. Both GO and MGO induced the formation of allysine in all tested proteins with GO being more reactive (23.8 and 8.6 nmoles/mg protein in LAC and MP respectively after 6 h) than MGO (2.6 and 3.1 nmoles/mg protein at the same sampling point). LAC seemed to be more susceptible to the glycation reactions than MP. The concentration of allysine decreased at 24 h along with a concomitant increase of advanced-glycation end-products suggesting that allysine may be involved in the formation of fluorescent adducts. The water-holding capacity and trypsin-chymotrypsin digestibility of the proteins decreased during the incubation assay. The mechanisms by which α-dicarbonyls-mediated carbonylation likely influenced the impairment of such protein properties are thoroughly discussed.

Oxidative damage to food and human serum proteins: Radical-mediated oxidation vs. glyco-oxidation.

This study compared a hydroxyl radical-generating system (HRGS) (0.05-0.2mM Fe3++0.6mM H2O2) and a glycation system (GLY) (0.05-0.2mM Fe3++0.05M glucose) for their ability to promote protein carbonylation and tryptophan depletion in myofibrillar proteins, ovalbumin, ß-lactoglobulin, soy protein and human serum albumin. Animal-source were more susceptible to protein carbonylation than soy proteins and globular were more susceptible than fibrillar proteins. Both systems promoted tryptophan loss and the formation of protein carbonyls and iron had a clear dose-effect in most systems and proteins. In the tested conditions, the GLY environment was more effective than the HRGS system in promoting the oxidative damage to food proteins. According to the results, glucose and H2O2 may compete for iron for the production of glycosylative and oxidative species, respectively. This study provides original insight into the chemical mechanisms implicated in the oxidative and glycosylative damage to food proteins.

c-Jun N-terminal kinase and p38 mitogen-activated protein kinase pathways link capacitation with apoptosis and seminal plasma proteins protect sperm by interfering with both routes†.

The mitogen-activated protein kinase (MAPK), c-Jun N-terminal kinase (JNK), and p38 MAP kinase (p38) signaling cascades are involved in triggering apoptosis in somatic cells. Given that spermatozoa are able to undergo apoptosis, we tested the hypothesis that these pathways might be functional in ram spermatozoa as two signal transduction mechanisms that contribute to the modulation of capacitation and apoptosis. Indirect immunofluorescence and western blot analysis evidenced the presence of JNK and p38 in ram spermatozoa. To verify the involvement of these enzymes in sperm physiology, we determined the effect of specific inhibitors of JNK or p38 on in vitro capacitation induced with either cAMP-elevating agents or epidermal growth factor (EGF). Both inhibitions reduced the EGF-induced capacitation with a decrease in the chlortetracycline capacitated-sperm pattern, protein tyrosine phosphorylation, phosphatidylserine externalization, caspase-3 and -7 activation, and the proportion of DNA-damaged spermatozoa. No significant changes were found in the high-cAMP capacitated samples. The addition of 3.4 mg/ml seminal plasma proteins (SPPs) to the EGF-containing samples, either alone or together with each inhibitor, resulted in a decreased proportion of capacitated sperm pattern, protein tyrosine phosphorylation, loss of plasma membrane integrity, and apoptotic alterations. Furthermore, SPPs significantly reduced the phosphorylation level of JNK and p38 MAPK (active forms). These findings show a relationship between capacitation and apoptosis, and represent a step forward in the knowledge of the SPP protective mechanism in spermatozoa.

Effect of seminal plasma proteins on the motile sperm subpopulations in ram ejaculates.

It has been proposed that seminal plasma proteins (SPP) support survival of ram spermatozoa, exerting a dual effect, both capacitating and decapacitating. In this study, changes in motility patterns of ram spermatozoa capacitated in the presence of epidermal growth factor (EGF) were evaluated. Clustering procedures were used to determine the presence of sperm subpopulations with specific motion characteristics. Four sperm subpopulations (SP) were defined after the application of a principal component analysis procedure. Progressive spermatozoa with high straightness (STR) were found in SP1, reflected in the high linearity (LIN) and STR values and low amplitude of lateral head movement (ALH; rapid, non-hyperactivated spermatozoa). SP2 spermatozoa seemed to be starting to acquire hyperactivated motility, while the SP3 group consisted of rapid, hyperactivated spermatozoa. SP4 showed less-vigorous spermatozoa, with non-linear motility. The addition of SPP before in vitro capacitation with EGF induced a decrease in SP1 and an increase in SP3. However, a reduction in the chlortetracycline-capacitated sperm rate and protein tyrosine phosphorylation was found, which corroborates with the hypothesis that the SPP protective effect on spermatozoa is related to their decapacitating role. These findings allow us to deduce that ram spermatozoa are able to undergo capacitation with no hyperactivation and that SPP are able to induce hyperactivation in spermatozoa but maintain them in a decapacitated state.

Lacosamide diminishes dryness-induced hyperexcitability of corneal cold sensitive nerve terminals.

Lacosamide is an anti-epileptic drug that is also used for the treatment of painful diabetic neuropathy acting through voltage-gated sodium channels. The aim of this work was to evaluate the effects of acute application of lacosamide on the electrical activity of corneal cold nerve terminals in lacrimo-deficient guinea pigs. Four weeks after unilateral surgical removal of the main lachrimal gland in guinea pigs, corneas were excised and superfused in vitro at 34°C for extracellular electrophysiological recording of nerve terminal impulse activity of cold thermosensitive nerve terminals. The characteristics of the spontaneous and the stimulus-evoked (cooling ramps from 34°C to 15°C) activity before and in presence of lacosamide 100µM and lidocaine 100µM were compared. Cold nerve terminals (n=34) recorded from dry eye corneas showed significantly enhanced spontaneous activity (8.0±1.1 vs. 5.2±0.7imp/s; P<0.05) and cold response (21.2±1.7 vs. 16.8±1.3imp/s; P<0.05) as well as reduced cold threshold (1.5±0.1 vs. 2.8±0.2 Δ°C; P<0.05) to cooling ramps compared to terminals (n=58) from control animals. Both lacosamide and lidocaine decreased spontaneous activity and peak response to cooling ramps significantly (P<0.05). Temperature threshold was increased by the addition of lidocaine (P<0.05) but not lacosamide (P>0.05) to the irrigation fluid. In summary, the application of lacosamide results in a significant decrease of the augmented spontaneous activity and responsiveness to cold of corneal sensory nerves from tear-deficient animals. Based on these promising results we speculate that lacosamide might be used to reduce the hyperexcitability of corneal cold receptors caused by prolonged ocular surface dryness due to hyposecretory or evaporative dry eye disease.

Redox chemistry of the molecular interactions between tea catechins and human serum proteins under simulated hyperglycemic conditions.

Carbonylation is an irreversible modification in oxidized proteins that has been directly related to a number of health disorders including Type 2 diabetes. Dietary antioxidants have been proposed to counteract the oxidative stress occurring under hyperglycemic conditions. An understanding of the nature and consequences of the molecular interactions between phytochemicals and human plasma proteins is of utmost scientific interest. Three tea catechins namely epicatechin (EC), epigallocatechin (EGC) and epigallocatechin-3-gallate (EGCG) were tested for (i) their affinity to bind to human serum albumin (HSA) and human hemoglobin (HH) and (ii) their ability to inhibit tryptophan (Trp) depletion and for the formation of specific protein carbonyls and pentosidine in the aforementioned proteins. Both proteins (20 mg mL(-1)) were allowed to react with postprandial plasmatic concentrations of the catechins (EC: 0.7 µM, EGC: 1.8 µM, and EGCG: 0.7 µM) under simulated hyperglycemic conditions (12 mM glucose/0.2 mM Fe(3+)/37 °C/10 days). The three catechins were able to inhibit Trp oxidation and protein carbonylation in both plasma proteins. Some anti-glycation properties were linked to their binding affinities. The molecular interactions reported in the present study may explain the alleged beneficial effects of tea catechins against the redox impairment linked to hyperglycemic conditions.

Abnormal activity of corneal cold thermoreceptors underlies the unpleasant sensations in dry eye disease.

Dry eye disease (DED) affects >10% of the population worldwide, and it provokes an unpleasant sensation of ocular dryness, whose underlying neural mechanisms remain unknown. Removal of the main lachrymal gland in guinea pigs caused long-term reduction of basal tearing accompanied by changes in the architecture and density of subbasal corneal nerves and epithelial terminals. After 4 weeks, ongoing impulse activity and responses to cooling of corneal cold thermoreceptor endings were enhanced. Menthol (200 µM) first excited and then inactivated this augmented spontaneous and cold-evoked activity. Comparatively, corneal polymodal nociceptors of tear-deficient eyes remained silent and exhibited only a mild sensitization to acidic stimulation, whereas mechanonociceptors were not affected. Dryness-induced changes in peripheral cold thermoreceptor responsiveness developed in parallel with a progressive excitability enhancement of corneal cold trigeminal ganglion neurons, primarily due to an increase of sodium currents and a decrease of potassium currents. In corneal polymodal nociceptor neurons, sodium currents were enhanced whereas potassium currents remain unaltered. In healthy humans, exposure of the eye surface to menthol vapors or to cold air currents evoked unpleasant sensations accompanied by increased blinking frequency that we attributed to cold thermoreceptor stimulation. Notably, stimulation with menthol reduced the ongoing background discomfort of patients with DED, conceivably due to use-dependent inactivation of cold thermoreceptors. Together, these data indicate that cold thermoreceptors contribute importantly to the detection and signaling of ocular surface wetness, and develop under chronic eye dryness conditions an injury-evoked neuropathic firing that seems to underlie the unpleasant sensations experienced by patients with DED.