Cytokines in Allergic Conjunctivitis: Unraveling Their Pathophysiological Roles.

Allergic conjunctivitis is one of the common immune hypersensitivity disorders that affect the ocular system. The clinical manifestations of this condition exhibit variability contingent upon environmental factors, seasonal dynamics, and genetic predisposition. While our comprehension of the pathophysiological engagement of immune and nonimmune cells in the conjunctiva has progressed, the same cannot be asserted for the cytokines mediating this inflammatory cascade. In this review, we proffer a comprehensive description of interleukins 4 (IL-4), IL-5, IL-6, IL-9, IL-13, IL-25, IL-31, and IL-33, as well as thymic stromal lymphopoietin (TSLP), elucidating their pathophysiological roles in mediating the allergic immune responses on the ocular surface. Delving into the nuanced functions of these cytokines holds promise for the exploration of innovative therapeutic modalities aimed at managing allergic conjunctivitis.

The Usefulness of Assessing Glaucoma Progression With Postprocessed Visual Field Data.

Purpose: Data postprocessing with statistical techniques that are less sensitive to noise can be used to reduce variability in visual field (VF) series. We evaluated the detection of glaucoma progression with postprocessed VF data generated with the dynamic structure-function (DSF) model and MM-estimation robust regression (MRR). Method: The study included 118 glaucoma eyes with at least 15 visits selected from the Rotterdam dataset. The DSF and MRR models were each applied to observed mean deviation (MD) values from the first three visits (V1-3) to predict the MD at V4. MD at V5 was predicted with data from V1-4 and so on until the MD at V9 was predicted, creating two additional datasets: DSF-predicted and MRR-predicted. Simple linear regression was performed to assess progression at the ninth visit. Sensitivity was evaluated by adjusting for false-positive rates estimated from patients with stable glaucoma and by using longer follow-up series (12th and 15th visits) as a surrogate for progression. Results: For specificities of 80% to 100%, the DSF-predicted dataset had greater sensitivity than the observed and MRR-predicted dataset when positive rates were normalized with corresponding false-positive estimates. The DSF-predicted and observed datasets had similar sensitivity when the surrogate reference standard was applied. Conclusions: Without compromising specificity, the use of DSF-predicted measurements to identify progression resulted in a better or similar sensitivity compared to using existing VF data. Translational Relevance: The DSF model could be applied to postprocess existing visual field data, which could then be evaluated to identify patients at risk of progression.

Detecting Progression in Patients With Different Clinical Presentations of Primary Open-angle Glaucoma.

PRCIS: Glaucoma progression was more frequently identified by assessing retinal fiber layer thickness than by monitoring visual field (VF) loss for different baseline classifications in primary open-angle glaucoma. PURPOSE: The aim was to compare the detection of glaucoma progression by retinal nerve fiber layer thickness (RNFLT) and VF assessments for different baseline classifications of primary open-angle glaucoma. METHODS: This study included 194 eyes from 194 patients with a minimum of 9 follow-up visits selected from the Diagnostic Innovation in Glaucoma Study (DIGS) and the African Descent and Glaucoma Evaluation Study (ADAGES). Each eye was classified according to baseline clinical signs: ocular hypertension (n=39), glaucomatous optic neuropathy only (n=60), glaucomatous visual field loss only (GVF, n=39) and definite glaucoma (concurrent optic disc and VF defect, n=56). We assessed progression by performing simple linear regression on global and sectorial mean deviations values generated for RNFLT (RNFLT-MD) and VF data (VF-MD). The proportion of eyes identified as progressing (positive rate) by RNFLT-MD and by VF-MD were compared within each classification. RESULTS: Whereas both parameters performed similarly among glaucomatous optic neuropathy only and definite glaucoma eyes, the positive rate obtained with global RNFLT-MD was significantly greater compared with global VF-MD by 33.3% and 30.8% among ocular hypertension eyes and GVF eyes, respectively. This finding was consistent in the inferotemporal sector; however, similar positive rates were obtained for both parameters in the superotemporal sector. CONCLUSIONS: While both RNFLT and VF parameters showed comparable abilities to identify progression across the different classifications, RNFLT assessment may be better suited to monitor progression, particularly among patients with elevated intraocular pressure and those who present with only GVF defect at baseline.

Nutrition knowledge and dietary patterns in ophthalmic patients.

CLINICAL SIGNIFICANCE: Ophthalmic nutrition education programs and good dietary patterns are of considerable significance to ocular health outcomes. BACKGROUND: The study aimed at assessing the level of ophthalmic nutrition knowledge and to compare the dietary patterns between different ophthalmic patients. METHODS: Four hundred and ninety-two adults (mean age 54.7 ± 19.4-years) receiving care at three eye-care facilities in Ghana were surveyed: 171 had senile cataract, 162 had open-angle glaucoma, and 159 had healthy eyes. A modified food frequency questionnaire was administered to elicit ophthalmic nutrition knowledge and dietary intake information of participants over the last 30-days. The results were compared between the three groups. RESULTS: More than half of the participants (n = 267; 54.3 per cent) had received some form of education on food sources that are good for the eyes and vision, with healthy participants accounting for 50.6 per cent of this proportion. Television (55.1 per cent; 147/267), radio (49.1 per cent; 131/267) and the eye doctor (34.1 per cent; 91/267) were the most frequent sources of ophthalmic nutritional knowledge. Overall, less than one-quarter of the participants (n = 108; 22.2 per cent) were able to correctly identify one food source for at least four out of seven selected ophthalmic nutrients. Vitamin C was the most frequently consumed ophthalmic nutrient, whereas lycopene was the least taken across all groups. The average ophthalmic nutrients intake score for those with healthy eyes (59.16 [53.39-64.93]) was significantly greater than for both glaucoma patients (37.73 [32.01-43.44]) and cataract patients (34.81 [29.24-40.37]). CONCLUSION: In addition to poor ophthalmic nutrition awareness and knowledge, both cataract and glaucoma patients, compared to those with healthy eyes, consumed a lesser amount of nutrients considered vital for eye health and vision. Ophthalmic nutrition education is needed to improve eye-health outcomes.

Associations between neighborhood-level violence and individual mental disorders: Results from the World Mental Health surveys in five Latin American cities.

Rapidly urbanizing areas of Latin America experience elevated but unevenly distributed levels of violence. Extensive research suggests that individual exposure to violence is associated with higher odds of both internalizing (anxiety and mood) and externalizing (substance and intermittent explosive) mental disorders. Less research, however, has focused on how neighborhood-level violence, as an indicator of broader neighborhood contexts, might relate to the mental health of residents, independently of an individual's personal exposure. We used multilevel analyses to examine associations of neighborhood-level violence with individual-level past-year mental disorders, controlling for individual-level violence exposure. We used data from 7,251 adults nested in 83 neighborhoods within five large Latin American cities as part of the WHO World Mental Health Surveys. Accounting for individual-level violence exposure, living in neighborhoods with more violence was associated with significantly elevated odds of individual-level internalizing disorders, but not externalizing disorders. Caution should be exercised when making causal inferences regarding the effects of neighborhood-level violence in the absence of experimental interventions. Nevertheless, neighborhood context, including violence, should be considered in the study of mental disorders. These findings are particularly relevant for rapidly urbanizing areas with high levels of violence, such as Latin America.

Managing uncertain recovery for patients nearing the end of life in hospital: a mixed-methods feasibility cluster randomised controlled trial of the AMBER care bundle.

BACKGROUND: The AMBER (Assessment, Management, Best Practice, Engagement, Recovery Uncertain) care bundle is a complex intervention used in UK hospitals to support patients with uncertain recovery. However, it has yet to be evaluated in a randomised controlled trial (RCT) to identify potential benefits or harms. The aim of this trial was to investigate the feasibility of a cluster RCT of the AMBER care bundle. METHODS: This is a prospective mixed-methods feasibility cluster RCT. Quantitative data collected from patients (or proxies if patients lack capacity) were used (i) to examine recruitment, retention and follow-up rates; (ii) to test data collection tools for the trial and determine their optimum timing; (iii) to test methods to identify the use of financial resources; and (iv) to explore the acceptability of study procedures for health professionals and patients. Descriptive statistical analyses and thematic analysis used the framework approach. RESULTS: In total, 894 patients were screened, of whom 220 were eligible and 19 of those eligible (8.6%) declined to participate. Recruitment to the control arm was challenging. Of the 728 patients screened for that arm, 647 (88.9%) were excluded. Overall, 65 patients were recruited (81.3% of the recruitment target of 80). Overall, many were elderly (≥80 years, 46.2%, n = 30, mean = 77.8 years, standard deviation [SD] = 12.3 years). Over half (53.8%) had a non-cancer diagnosis, with a mean of 2.3 co-morbidities; 24.6% patients (n = 16) died during their hospital stay and 35.4% (n = 23) within 100 days of discharge. In both trial arms, baseline IPOS subscale scores identified moderate patient anxiety (control: mean 13.3, SD 4.8; intervention: mean 13.3, SD 5.1), and howRwe identified a good care experience (control: mean 13.1, SD 2.5; intervention: mean 11.5, SD 2.1). Collecting quantitative service use and quality of life data was feasible. No patient participants regarded study involvement negatively. Focus groups with health professionals identified concerns regarding (i) the subjectivity of the intervention's eligibility criteria, (ii) the need to prognosticate to identify potential patients and (iii) consent procedures and the length of the questionnaire. CONCLUSIONS: A full trial of the AMBER care bundle is technically feasible but impractical due to fundamental issues in operationalising the intervention's eligibility criteria, which prevents optimal recruitment. Since this complex intervention continues to be used in clinical care and advocated in policy, alternative research approaches must be considered and tested. TRIAL REGISTRATION: International Standard Randomised Controlled Trial Number (ISRCTN) Register, ISRCTN36040085 .

Implementation of the North Carolina HIV Bridge Counseling Program to Facilitate Linkage and Reengagement in Care for Individuals Infected with HIV/AIDS.

BACKGROUND Statewide interventions are critical to meeting the goals of the National HIV/AIDS Strategy in this country. In 2012, the North Carolina Division of Public Health developed the North Carolina State Bridge Counselor program to improve linkage to and reengagement in care for newly diagnosed persons and persons living with HIV who were out-of-care.METHODS We reviewed the planning process for the North Carolina State Bridge Counselor program, which involved a review of existing strengths-based counseling models for persons living with HIV, implementation of these models, and communication strategies with other providers. State bridge counselor responsibilities were delineated from the role of disease intervention specialists while retaining the fieldwork capability of disease intervention specialists to conduct outreach and provide services for persons living with HIV throughout the state.RESULTS Program implementation required extensive planning with stakeholders, incorporation of strengths-based counseling models, development of performance standards, and utilization of CAREWare, an HIV care software program to document referrals and data-sharing between state bridge counselors and clinics. By the end of 2014, state bridge counselor services were provided to approximately 60 of the 400 persons living with HIV (15%) who are diagnosed each quarter in North Carolina, with increasing utilization of the program.LIMITATIONS We assessed the development of this intervention specific to the North Carolina Division of Public Health, which may limit its generalizability. However, the State Bridge Counselor program was implemented in both urban and rural areas throughout the state, which increases its applicability to different public health programs throughout the country.CONCLUSION We demonstrated that a statewide State Bridge Counselor program for linkage and reengagement activities can be implemented by leveraging existing infrastructures, electronic medical records, HIV care networks, and fieldwork activities.

Near vision spectacle coverage and barriers to near vision correction among adults in the Cape Coast Metropolis of Ghana.

PURPOSE: To determine the near vision spectacle coverage and barriers to obtaining near vision correction among adults aged 35 years and older in the Cape Coast Metropolis of Ghana. METHODS: A population-based cross-sectional study design was adopted and 500 out of 576 participants aged 35 years and older were examined from 12 randomly selected clusters in Cape Coast, Ghana. All participants underwent a comprehensive eye examination which included: distance and near visual acuities measurements and external and internal ocular health assessments. Distance and near refractions were performed using subjective refraction technique. Information on participants' demographics, near vision correction status, near visual needs and barriers to acquiring near vision correction were obtained through a questionnaire administered as part of the study. RESULTS: The mean age of participants was 52.3±10.3 years of whom 280 (56%) were females and 220 (44%) were males. The near vision spectacle coverage was 25%, 33% "met need" for near vision correction in the presbyopic population, and 64% unmet need in the entire study population. After controlling for other variables, age (5th and 6th decades) and educational level were associated with "met need" for near vision correction (OR=2.7 (1.55-4.68), p =0.00, and OR=2.36 (1.18-4.72), p=0.02 respectively). Among those who needed but did not have near vision correction, 64 (26%) did not feel the need for correction, 55 (22%) stated that they were unaware of available interventions, and 53 (21%) found the cost of near vision correction prohibitive. CONCLUSION: There was a low near vision spectacle coverage in this population which suggests the need for strategies on health education and promotion to address the lack of awareness of spectacle need and cost of services.

The prevalence and nature of supportive care needs in lung cancer patients.

PURPOSE: In the present work, we set out to comprehensively describe the unmet supportive care and information needs of lung cancer patients. METHODS: This cross-sectional study used the Supportive Care Needs Survey Short Form 34 (34 items) and an informational needs survey (8 items). Patients with primary lung cancer in any phase of survivorship were included. Demographic data and treatment details were collected from the medical charts of participants. The unmet needs were determined overall and by domain. Univariable and multivariable regression analyses were performed to determine factors associated with greater unmet needs. RESULTS: From August 2013 to February 2014, 89 patients [44 (49%) men; median age: 71 years (range: 44-89 years)] were recruited. The mean number of unmet needs was 8 (range: 0-34), and 69 patients (78%) reported at least 1 unmet need. The need proportions by domain were 52% health system and information, 66% psychological, 58% physical, 24% patient care, and 20% sexuality. The top 2 unmet needs were "fears of the cancer spreading" [n = 44 of 84 (52%)] and "lack of energy/tiredness" [n = 42 of 88 (48%)]. On multivariable analysis, more advanced disease and higher MD Anderson Symptom Inventory scores were associated with increased unmet needs. Patients reported that the most desired information needs were those for information on managing symptoms such as fatigue (78%), shortness of breath (77%), and cough (63%). CONCLUSIONS: Unmet supportive care needs are common in lung cancer patients, with some patients experiencing a very high number of unmet needs. Further work is needed to develop resources to address those needs.

Prognostic value of pretreatment circulating neutrophils, monocytes, and lymphocytes on outcomes in lung stereotactic body radiotherapy.

PURPOSE: In the present study, we determined the association of pretreatment circulating neutrophils, monocytes, and lymphocytes with clinical outcomes after lung stereotactic body radiotherapy (sbrt). METHODS: All patients with primary lung cancer and with a complete blood count within 3 months of lung sbrt from 2005 to 2012 were included. Overall survival (os) was calculated using the Kaplan-Meier method. Factors associated with os were investigated using univariable and multivariable Cox proportional hazards regression. Fine-Gray competing risk regression was performed to test the association of the neutrophil:lymphocyte (nlr) and monocyte:lymphocyte (mlr) ratios with two types of failure: disease-related failure and death, and death unrelated to disease. RESULTS: Of the 299 sbrt patients identified, 122 were eligible for analysis. The median and range of the nlr and mlr were 3.0 (0.3-22.0) and 0.4 (0.1-1.9) respectively. On multivariable analysis, sex (p = 0.02), T stage (p = 0.04), and nlr (p < 0.01) were associated with os. On multivariable analysis, T stage (p < 0.01) and mlr (p < 0.01) were associated with disease-related failure; mlr (p = 0.03), nlr (p < 0.01), and sbrt dose of 48 Gy in 4 fractions (p = 0.03) and 54 Gy or 60 Gy in 3 fractions (p = 0.02) were associated with disease-unrelated death. Median survival was 4.3 years in the nlr≤3 group (95% confidence interval: 3.5 to not reached) and 2.5 years in the nlr>3 group (95% confidence interval: 1.7 to 4.8; p < 0.01). CONCLUSIONS: In lung sbrt patients, nlr and mlr are independently associated with os and disease-unrelated death. If validated, nlr and mlr could help to identify patients who would benefit most from sbrt.

The association between socio-demographic marginalization and plasma glucose levels at diagnosis of gestational diabetes.

AIMS: We examined the association between socio-demographic marginalization and plasma glucose levels at diagnosis of gestational diabetes in a multi-ethnic and socio-economically diverse patient group. METHODS: Medical charts at a Toronto gestational diabetes clinic were reviewed for women with a recorded pregnancy between 1 March 2006 and 26 April 2011. One-hour 50-g glucose challenge test values and postal code data were abstracted. Postal codes were merged with 2006 Canadian census data to compute neighbourhood-level ethnic concentration (% recent immigrants, % visible minorities) and material deprivation (% low education, % low income, single-parent households). We compared women in the highest neighbourhood quintiles for both ethnic concentration and material deprivation with all other women to explore an association between marginalization and diagnostic glucose levels. Multivariate regression models of glucose challenge test values and insulin prescription were adjusted for age, prior gestational diabetes, parity and diabetes family history. RESULTS: Among 531 patients with complete glucose challenge test data (mean 11.94 mmol/l, sd 1.83), those in the most marginalized neighbourhoods had 0.43 mmol/l higher glucose challenge test values (95% CI 0.08-0.78) compared with the rest of the study population. Other factors associated with higher glucose challenge test values were prior gestational diabetes (0.59 mmol/l increment, 95% CI 0.19-0.99) and diabetes family history (0.32 mmol/l increment, 95% CI -0.01 to 0.66). Each additional 1 mmol/l glucose challenge test result was associated with an increased likelihood of being prescribed insulin (odds ratio 1.33, 95% CI 1.17-1.51). CONCLUSIONS: Women living in the most materially deprived and ethnically concentrated neighbourhoods have higher glucose levels at diagnosis of gestational diabetes. They may need close monitoring for timely initiation of insulin.

The unsuspected killer: Liquefied petroleum gas overexposure in South Africa.

A 21-year-old woman with no past medical history of note was found unconscious together with five of her family members after prolonged exposure to liquefied petroleum gas. She was admitted to the intensive care unit at Victoria Hospital, Wynberg, Cape Town, South Africa, following resuscitation for pulseless electrical activity. On examination the following was found: coma without focal neurology; shock requiring fluid resuscitation and adrenaline; probable pneumonitis or aspiration pneumonia; acute rhabdomyolysis with severe metabolic acidosis; and raised serum K+. A carboxyhaemoglobin test was unable to confirm or exclude carbon monoxide poisoning.

Dietary glycemic index, glycemic load, insulin index, fiber and whole-grain intake in relation to risk of prostate cancer.

OBJECTIVE: Insulin may play a role in prostate cancer tumorigenesis. Postprandial blood glucose and insulin responses of foods depend importantly on the carbohydrate quality and quantity, represented by glycemic index (GI), glycemic load (GL), fiber and whole-grain content, but are also influenced by intake of protein and other characteristics. The recently developed insulin index (II) quantifies the postprandial insulin secretion, also taking into account these additional characteristics. METHODS: We investigated the association between dietary GI, GL, II, fiber, and whole grains and risk of total prostate cancer (n = 5,112) and subgroups of prostate cancer as defined by stage or grade in 49,934 male participants of the Health Professionals Follow-up Study. Multivariate adjusted hazard ratios (HR) and 95% confidence intervals (95% CI) were estimated using Cox proportional hazards regression. RESULTS: Dietary GI, GL, II, or fiber was not associated with risk of total or subgroups of prostate cancer. We observed a positive association between dietary intake of whole grains and total prostate cancer (HR highest versus lowest quintile 1.13, 95% CI 1.03-1.24), which was attenuated after restriction to PSA-screened participants (HR 1.03, 95% CI 0.91-1.17). CONCLUSIONS: These results suggest that long-term exposure to a diet with a high insulin response does not affect prostate cancer incidence.

Electrode displacement strain imaging of thermally-ablated liver tissue in an in vivo animal model.

PURPOSE: Percutaneous thermal ablation is increasingly being used to destroy hepatic tumors in situ. The success of ablative techniques is highly dependent on adequate ablation zone monitoring, and ultrasound-based strain imaging could become a convenient and cost-effective means to delineate ablation zone boundaries. This study investigates in vivo electrode displacement-based strain imaging for monitoring hepatic ablation procedures that are difficult to perform with conventional elastography. METHODS: a In our method, minute displacements (less than a millimeter) are applied to the unconstrained end of the ablation electrode, resulting in localized tissue deformation within the ablation zone that provides the mechanical stimuli required for strain imaging. This article presents electrode displacement strain images of radiofrequency ablation zones created in porcine liver in vivo (n = 13). RESULTS: Cross-sectional area measurements from strain images of these ablation zones were obtained using manual and automated segmentation. Area measurements from strain images were highly correlated with areas measured on histopathology images, quantitated using linear regression (R = 0.894, P < 0.001 and R = 0.828, P < 0.001, respectively). CONCLUSIONS: This study further demonstrates that electrode displacement elastography is capable of providing high-contrast images using widely available commercial ultrasound systems which may potentially be used to assess the extent of thermal ablation zones.

Evaluation of a novel food composition database that includes glutamine and other amino acids derived from gene sequencing data.

OBJECTIVES: To determine the content of glutamine in major food proteins. SUBJECTS/METHODS: We used a validated 131-food item food frequency questionnaire (FFQ) to identify the foods that contributed the most to protein intake among 70,356 women in the Nurses' Health Study (NHS, 1984). The content of glutamine and other amino acids in foods was calculated based on protein fractions generated from gene sequencing methods (Swiss Institute of Bioinformatics) and compared with data from conventional (USDA) and modified biochemical (Khun) methods. Pearson correlation coefficients were used to compare the participants' dietary intakes of amino acids by sequencing and USDA methods. RESULTS: The glutamine content varied from 0.01 to to 9.49 g/100 g of food and contributed from 1 to to 33% of total protein for all FFQ foods with protein. When comparing the sequencing and Kuhn's methods, the proportion of glutamine in meat was 4.8 vs 4.4%. Among NHS participants, mean glutamine intake was 6.84 (s.d.=2.19) g/day and correlation coefficients for amino acid between intakes assessed by sequencing and USDA methods ranged from 0.94 to 0.99 for absolute intake, -0.08 to 0.90 after adjusting for 100 g of protein, and 0.88 to 0.99 after adjusting for 1000 kcal. The between-person coefficient of variation of energy-adjusted intake of glutamine was 16%. CONCLUSIONS: These data suggest that (1) glutamine content can be estimated from gene sequencing methods and (2) there is a reasonably wide variation in energy-adjusted glutamine intake, allowing for exploration of glutamine consumption and disease.

Radiofrequency ablation with a high-power generator: device efficacy in an in vivo porcine liver model.

PURPOSE: The purpose of this study was to test the feasibility and efficacy of using a high-power generator with nondeployable electrodes to create large zones of coagulation in an in vivo porcine liver model. METHODS: With approval from our institution's research animal care and use committee, 12 female swine (mean weight = 55 kg) were anesthetized and received RF ablation at laparotomy. Twenty-nine ablations were performed in four groups using: (i) a conventional 200-W generator and cluster electrode (n = 4), or an experimental prototype 250-W generator and (ii) a single, 17-gauge electrode (n = 9), (iii) a cluster electrode (n = 8) or (iv) three electrodes spaced 2.0 cm apart in a triangular configuration (n = 8). In the three-electrode group, power was applied by switching between electrodes using a prototype switching device. All electrodes were internally cooled. Ablation zone size, shape and generator data from each group were compared using a mixed-linear model with animals modeled as random effects. RESULTS: The high-power generator was able to increase significantly the zone of coagulation. Mean (+/-SD) ablation diameter was largest in the switched group (4.31 +/- 0.7 cm) followed by the cluster (3.98 +/- 0.5 cm) and single-electrode (3.26 +/- 0.5 cm) groups. Mean diameter in the high-power single-electrode group was no different than the low-power cluster group (3.25 +/- 0.4 cm, p = 0.98). Circularity measures were high (>0.75) in all groups. CONCLUSIONS: Coupling a high-power generator and switching device is feasible. At higher powers, the switching device creates larger zones of ablation than cluster or single electrodes. Single-electrode ablations created with the prototype high-power generator were equivalent to those produced with the cluster electrode at conventional lower powers.

Involvement of cyclic GMP and potassium channels in relaxation evoked by the nitric oxide donor, diethylamine NONOate, in the rat small isolated mesenteric artery.

The relative functional importance of potassium channels and cGMP-dependent pathways in the relaxation of vascular smooth muscle to the novel nitric oxide donor, diethylamine NONOate (DEA NONOate), was investigated in a resistance artery. The contribution from cGMP-dependent signalling pathways was examined by exposing arteries to 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), a selective inhibitor of soluble guanylyl cyclase, while the contribution through potassium channels was assessed with different sub-type-selective potassium channel blockers. DEA NONOate (3 nM-10 microM) evoked sustained relaxation in isolated segments of the rat small mesenteric artery contracted with phenylephrine (pEC50=6.7+/-0.2; n=11). The relaxation was attenuated significantly by either ODQ (10 microM; pEC50=5.8+/-0.4; n=7) or charybdotoxin (ChTX; 50 nM; pEC50=6.3+/-0.2; n=4), a peptide blocker of large conductance, calcium-activated potassium channels (BK(Ca)). The inhibitory effects of ODQ and ChTX were additive (pEC50=5.1+/-0.4; n=9). The selective inhibitor of BK(Ca) channels, iberiotoxin (IbTX; 30 nM), and 4-aminopyridine (4-AP; 1 mM), an inhibitor of voltage-gated potassium channels (Kv), failed to modify DEA NONOate-evoked relaxation. However, in the combined presence of both ODQ and either IbTX or 4-AP the relaxation was attenuated significantly (n=3). The blocker of ATP-modulated potassium channels (K(ATP)), glibenclamide (10 microM), and of small conductance calcium-activated potassium channels (SK(Ca)), apamin (30 nM), each failed to affect ODQ-sensitive or -resistant relaxations to DEA NONOate (n=3). In conclusion, relaxation to DEA NONOate in the rat isolated, small mesenteric artery can occur via both cGMP-dependent (ODQ-sensitive) and -independent (ODQ-resistant) mechanisms. However, the contribution made to relaxation by potassium channels appears to be unmasked following pharmacological attenuation of cGMP-dependent signalling pathways. The inhibitory action of ChTX suggests part of the cGMP-insensitive component involves the activation of potassium channels, a suggestion supported by the inhibitory actions of 4-AP and IbTX in the absence of cGMP.

Relaxation to authentic nitric oxide and SIN-1 in rat isolated mesenteric arteries: variable role for smooth muscle hyperpolarization.

Authentic nitric oxide (NO; 0.1 - 10 micromoles) caused transient, dose-dependent relaxation of phenylephrine-induced tone without changing membrane potential in mesenteric arteries. Larger doses, above 10 micromoles, did not evoke more relaxation (maximal relaxation to 150 micromoles NO in denuded arteries, 69+/-7%, n=8) but stimulated muscle hyperpolarization (maximum 19+/-3 mV, n=5). The soluble guanylyl cyclase inhibitor, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ; 10 microM), abolished relaxation to low doses of NO (n=4), but did not modify hyperpolarization with higher doses of NO (n=4). The potassium channel blocker charybdotoxin (ChTX; 50 nM) abolished hyperpolarization to high doses of NO and significantly reduced the maximal relaxation (to 43+/-6%, n=4; P<0.01). ODQ and ChTX together abolished tension and membrane potential change to all doses of NO (n=4). All relaxations to 3-morpholino-sydnonimine (SIN-1; 0.01 - 10 microM) were associated with hyperpolarization. When the endothelium was intact, ChTX inhibited hyperpolarization and relaxation to SIN-1 (n=5), while iberiotoxin (IbTX; 50 nM) or 4-aminopyridine (4-AP; 500 microM) reduced relaxation by 40% and 20%, respectively and by 80% in combination (n=6 in each case). In denuded arteries, relaxation to SIN-1 was unaffected by either ChTX or ODQ alone, but abolished by the inhibitors together (n=6). Alone, 4-AP did not alter relaxation, but in the presence of ODQ it reduced the maximal response by around 45% (n=6; P<0.01). 4-AP, ODQ and IbTX together inhibited relaxation to SIN-1 by 75% (n=6; P<0.01). Therefore, cyclic guanosine 3',5'-monophosphate (cyclic GMP)-independent smooth muscle hyperpolarization, possibly involving direct activation of calcium-activated and voltage-sensitive potassium channels, contributes to relaxation evoked by authentic NO and SIN-1. However, the importance of each pathway depends on the source of NO and with SIN-1 the relative contribution from each pathway is modified by the endothelium.

Evidence for expression and function of phosphodiesterase type 5 (PDE-V) in rat resistance arteries.

Evidence is provided for expression and a functional role for phosphodiesterase type V (PDE-V) in the rat isolated small mesenteric artery. The reverse transcription polymerase chain reaction (RT--PCR) demonstrated mRNA for PDE-V, while Western blotting and immunocytochemical studies showed corresponding protein expression. Smooth muscle relaxation to the nitric oxide donor, diethylamine NONOate (DEA NONOate; 1 nM - 10 microM; pEC(50)=6.7+/-0.3) was potentiated significantly by the specific inhibitor of PDE-V, 4-[[3,4-(methylenedioxy)benzyl]amino]-6-chloroquinazoline (MBCQ; 1 microM; pEC(50)=10.5+/-0.04). These data show that PDE-V is expressed in both the smooth muscle and endothelial cells of a resistance artery, and the enzyme can significantly influence nitric oxide-evoked vasorelaxation.