Effects of semaglutide and empagliflozin on oxygenation, vascular autoregulation, and central thickness of the retina in people with type 2 diabetes: A prespecified secondary analysis of a randomised clinical trial

AIMS

Semaglutide and empagliflozin have shown cardiovascular protection. In SUSTAIN-6, semaglutide was associated with an increased risk of diabetic retinopathy. We investigated whether changes in retinal oxygenation, retinal vascular autoregulation, and central retinal thickness are altered by semaglutide, empagliflozin or the combination.

METHODS

This study was a prespecified, secondary outcome from a randomised, 32 weeks partly placebo-controlled, partly open-label, clinical trial on the effects of semaglutide and empagliflozin on arterial stiffness and kidney oxygenation. A total of 120 participants with type 2 diabetes, established or high risk of cardiovascular disease and age ≥50 years were randomised into four parallel groups (semaglutide, empagliflozin, the combination or tablet placebo, n = 30 for each group). We primarily hypothesized that semaglutide would increase venular oxygenation.

RESULTS

We found no changes in retinal arteriolar, venular or venular-arteriolar oxygenation nor in retinal vessel diameter regardless of treatment group. Semaglutide increased central retinal thickness compared to placebo with ~1 % (3.8 μm 95 % CI [0.9;6.7], p = 0.009) with no changes in the empagliflozin or combination group.

CONCLUSION

Neither semaglutide, empagliflozin nor the combination alters markers of retinal function. The effect of semaglutide on central retinal thickness was small, but the clinical significance is uncertain.

Low Levels of Vitamin C during Pregnancy; a Risk Marker of Progression of Diabetic Retinopathy in Type 1 Diabetic Women?

Pregnancy is a risk factor for the development or aggravation of diabetic retinopathy. Here, we suggest a relationship between plasma vitamin C (vitC) status during pregnancy and into postpartum in type 1 diabetes and the possible progression of diabetic retinopathy based on data of 29 women. VitC was measured in first, second, and third trimesters and three months postpartum. The women had visual acuity testing and fundus photography performed at least twice during pregnancy and onto four months after birth. An overall retinopathy grade was assigned on a scale from 0 (no retinopathy) to four according to the International Clinical Diabetic Retinopathy scale. At baseline in 1st trimester, 12 women had no retinopathy; seventeen women had retinopathy in grade 1–3. The retinopathy grade increased in nine women; remained unchanged in 17 women, and improved in three women. No women had or developed proliferative retinopathy (grade 4). The level of vitC in 1st trimester predicted the possible progression of retinopathy—the lower the vitC, the more probable the progression (p = 0.03; OR 1.6 (95% CI:1.06–3.2); n = 29 (multiple logistic regression))—while the combined levels of 1st and 2nd trimesters and the mean vitC level of the whole pregnancy did not. The diabetes duration, retinopathy grade per se in 1st trimester, 24-h blood pressure measurements, kidney function, urinary protein, HbA1c, or lipid profile were not independent predictors of progression of retinopathy during pregnancy. Retrospectively, the women who experienced progression of their retinopathy during and into postpartum had significantly lower vitC levels in 1st trimester (p = 0.02; n = 9/20), combined level of vitC in 1st and 2nd trimester (p = 0.032; n = 7/18), and mean vitC level of the whole pregnancy (p = 0.036; n = 7/9), respectively. In conclusion, our results suggest that low vitC status in pregnancy could be associated with progression of diabetic retinopathy.

Vasomotion in Retinal Arterioles Is Modified by Exercise and Flicker Stimulation

PURPOSE

Vasomotion is spontaneous oscillations in the diameter of resistance vessels with derived effects on blood flow, and it has been proposed that disturbances in vasomotion may be involved in retinal vascular disease. The purpose of this study was to investigate whether retinal vasomotion shows regional variation and is modified by activated autoregulation.

METHODS

Video recordings of the diameter of retinal arterioles previously obtained from 55 normal persons were subjected to Fourier analysis to characterize the frequencies and propagation of spontaneous diameter changes in retinal arterioles. The analyses were performed on peripapillary temporal retinal arterioles, on arteriolar branches toward the macular area and the retinal periphery, and were performed during rest, during an increase in the arterial blood pressure induced by isometric exercise, and during increased retinal metabolism induced by flickering light.

RESULTS

There was no propagation of diameter changes along the studied vascular segments. Isometric exercise constricted the arterioles significantly by (mean ± SD) 1.76% ± 3.56% (P = 0.02) and increased the power of diameter oscillations at very low frequencies (0.1-1.4 c/min). Flicker stimulation dilated the arterioles significantly by (mean ± SD) 5.10% ± 2.91% (P < 0.0001) and reduced the power of diameter oscillations at all but the very low frequencies (P < 0.006 for all comparisons). Flicker-induced dilation and changes in hydraulic conductance were lower in peripheral than in macular arterioles.

CONCLUSIONS

Retinal vasomotion in normal persons increases during increased arterial blood pressure and decreases during flicker stimulation. The findings may act as a basis for the study of vasomotion in retinal vascular disease.

Gender differences in first-episode psychosis at 5-year follow-up – two different courses of disease? Results from the OPUS study at 5-year follow-up

Objective

Gender differences in psychosis have been investigated, and the results have contributed to a better understanding of the disease, but many questions are unanswered. In clinical terms, women and men with psychosis differ in terms of access to social support, tendency of substance abuse, level of functioning and symptom patterns. We aimed to investigate how gender differences at onset of psychosis develop during the first 5 years of treatment.

Method

A total of 578 patients with a first-episode psychosis in the schizophrenia spectrum were included in the Danish OPUS trial – a randomized clinical trial comparing 2 years of intensive early-intervention programme with standard treatment. All patients were assessed with validated instruments at inclusion, and after 2 and 5 years. Data were analysed for significant gender differences.

Results

Males have significantly higher levels of negative symptoms at all times, and are more likely to live alone and suffer from substance abuse. Females reach higher levels of social functioning at follow-up, and show a greater tendency to be employed or in education than males. Markedly more women than men live with children. More women than men reach a state of recovery and are more compliant with medication.

Conclusion

There are significant gender differences at 2- and 5-year follow-up in this large cohort of first-episode psychotic patients. Males and females show different symptomatology and different levels of social functioning.

Retinal vasodilatation in the affected eye but reduced pressure autoregulation of both eyes in unilateral Coats' disease

BACKGROUND

Coats' disease is characterized by vascular hyperpermeability, oedema and accumulation of exudates related to impairment of retinal vascular function. The background for the development of the disease is unknown, but it is likely that the study of diameter changes of retinal vessels may contribute to understanding the pathophysiology of the disease.

METHODS

In seven patients with unilateral Coats' disease (mean age = 34.7 years, range: 11-69 years), the baseline diameter and reactivity of retinal vessels during an increase in the arterial blood pressure by isometric exercise and in the metabolism by flicker stimulation were measured on video recordings of the retina obtained with the Dynamic Vessel Analyzer.

RESULTS

The baseline diameter of retinal vessels was larger in the affected than in the unaffected eyes which was significant for the arterioles (p = 0.02), but not for the venules (p = 0.15). During an increase in the arterial blood pressure induced by isometric exercise, the normal contraction of arterioles was absent in both eyes (p > 0.7), whereas there was a significant dilatation of the venules in the unaffected eyes (p = 0.04). Stimulation with flickering light induced normal dilatation of retinal vessels in both affected and unaffected eyes.

CONCLUSION

Unilateral Coats' disease is accompanied by vasodilatation in the affected eye but impaired pressure autoregulation in both eyes. A further investigation of the disease should include an elucidation of the background for dilatation of retinal vessels in affected eyes and whether impaired pressure autoregulation can be found in vessels elsewhere in the body.

P2568Larger vectorcardiographic QRS area is associated with increased risk of heart failure development among left bundle branch block patients: a register-based cohort study

Background

QRS morphology including left bundle branch block (LBBB) and duration remain the most widely used surrogate markers in the 12-lead electrocardiogram (ECG) for assessing ventricular dyssynchrony and predicting future burden of heart failure (HF) and cardiovascular mortality. However, the vectorcardiographic QRS area has recently been proposed and evidence suggest that this marker may more accurately predict HF development.

Purpose

The aim of this study was to investigate the association between vectorcardiographic QRS area and risk of HF development in LBBB patients.

Methods

From 2001–2015, the Copenhagen General Practitioners' Laboratory was used to identify patients with a first-time LBBB ECG (QRS>120 ms; LBBB morphology), from which QRS area was derived using the Kors transformation method and grouped into quartiles. Outcome was a composite of HF diagnosis, redeemed prescriptions of loop diuretics, or death from HF. Death from other causes was accounted for as a competing risk.

Results

We included a total of 2843 LBBB patients who were free of heart failure (median age, 70 years; female, 58%; ischemic heart disease, 9%). QRS area quartiles comprised Q1, 67–158 μVs; Q2, 159–189 μVs; Q3, 190–228 μVs; and Q4, 229–739 μVs. During 6-month, 1-year, and 5-year follow-up, 9%, 12%, and 28% of patients reached the combined HF endpoint, and 1%, 2%, and 8% of patients died from other causes, respectively (Figure 1). After multivariable adjustment, the highest QRS area quartile, Q4, was associated with increased HF risk (adjusted hazard ratio, 1.64; 95% confidence interval, 1.35–2.00) compared with the lowest quartile, Q1. We did not observe any significant increase in HF risk for remaining quartiles (Q2 or Q3 vs. Q1).

Figure 1

Conclusions

Among primary care patients with newly discovered LBBB, a large vectorcardiographic QRS area (229–739 μVs) is associated with increased risk of developing the incident, combined HF endpoint. This indicates that the QRS area derived using the Kors method may serve as a valuable prognostic marker when assessing risk of HF in patients with LBBB.

Retinal vessel reactivity is not attenuated in patients with type 2 diabetes compared with matched controls and is associated with peripheral endothelial function in controls

BACKGROUND AND AIMS

Attenuated retinal vasoreactivity in patients with type 2 diabetes preceding diabetic retinopathy development has been proposed to reflect local endothelial dysfunction. Whether retinal vessel reactivity is associated with peripheral endothelial dysfunction and large artery stiffness in patients with type 2 diabetes remains to be elucidated.

METHODS

Twenty patients with type 2 diabetes without retinopathy and 20 sex- and age matched controls (diabetes duration: 9.9 years (range 6.0;12.4), 40% male, age: 66.5 ± 7.3 (diabetes) and 65.2 ± 7.6 years (controls)) were included. Endothelial function was assessed using EndoPAT. Arterial stiffness was assessed by carotid-femoral pulse wave velocity using the SphygmoCor. Retinal blood supply regulation was examined by retinal arteriolar diameter change during 1) isometric exercise (hand-weight lifting), 2) exposure to flickering lights, and 3) a combined stimulus of 1) + 2) using the Dynamic Vessel Analyzer.

RESULTS

No significant differences were observed in retinal vessel reactivity in T2DM patients compared to controls. Endothelial function was associated with mean arteriolar diameter change during only the combination intervention, (Beta = 0.033 [0.0013;0.064], p = 0.042) in the overall population of patients and controls. When groups were analyzed separately, the associations was statistically significant only in controls. However, formal test for interaction was not statistically significant, p = 0.40. No association was observed between pulse wave velocity and retinal arteriolar %-diameter change in patients or controls.

CONCLUSION

Peripheral endothelial function was associated with retinal arteriolar diameter change in the combined sample. The association seemed to be driven primarily by the controls. Our findings indicate that peripheral endothelial function is reflective of endothelial function in the retina mainly in subjects without T2DM, whereas an association in T2DM without retinopathy was not observed. Further studies are needed in T2DM patients with more advanced retinopathy.

Reduced baseline diameter and contraction of peripheral retinal arterioles immediately after remote ischemia in diabetic patients

PURPOSE

Remote ischemic conditioning (RIC) implies that transient ischemia in one organ can affect blood flow and protect from ischemia in another remote organ such as the retina. The purpose of the present study was to investigate the effect of RIC on the diameter of retinal arterioles in patients with diabetic retinopathy and whether this effect differs among peripheral and macular vessels.

METHODS

In twenty type 1 diabetes patients aged 20-31 years, the Dynamic Vessel Analyzer (DVA) was used to measure diameters of peripheral and macular arterioles during rest, isometric exercise, and flicker stimulation. Measurements were obtained before, immediately after, and 1 h after RIC, and were compared to responses obtained from normal persons.

RESULTS

The reduced baseline diameter (p < 0.009) and contraction of peripheral retinal arterioles during isometric exercise (p = 0.025) observed immediately after RIC in normal persons were absent in the studied diabetic patients.

CONCLUSIONS

RIC affects the diameter of peripheral but not macular arterioles in normal persons, but the response is abolished in diabetic patients.

TRIAL REGISTRATION

NCT03906383.

The Diameter of Retinal Arterioles Is Unaffected by Intravascular Administration of the Adenosine A2A Receptor Agonist Regadenoson in Normal Persons

Background

The neurotransmitter adenosine has been proposed to be involved in the pathogenesis of diabetic retinopathy, which may be due to the vasoactive properties of the compound. Previous studies have shown that adenosine can affect the tone of retinal arterioles in vitro to induce dilatation mediated by A_2A and A_2Breceptors and constriction mediated by A₁ and A₃ receptors.

Purpose

To investigate effects of intravenous administration of the adenosine A_2A receptor agonist regadenoson on the diameter of retinal vessels in vivo.

Method

The diameter responses of larger retinal arterioles and venules were evaluated using the dynamic vessel analyser in 20 normal persons (age 22–31 years) after intravenous administration of the adenosine A_2A receptor agonist regadenoson during exposure to systemic normoxia and hypoxia.

Results

The diameter of retinal arterioles and venules increased significantly during stimulation with flickering light (p < 0.0001). Regadenoson reduced the flicker-induced dilatation of venules during normoxia (p = 0.0006), but otherwise had no effect on vessel diameters (p > 0.08 for all comparisons).

Conclusions

Intravenous administration of the adenosine A_2A receptor agonist regadenoson had no significant effect on the diameter of retinal arterioles. Future studies should investigate differential effects of intra- and extravascular administration of adenosine receptor agonists on retinal vessels.

A Danish register-based study on involuntary treatment in anorexia nervosa

OBJECTIVE

Involuntary treatment is controversial and widely debated, but remains a significant component of treatment for severe anorexia nervosa. Given how little is known about this topic, we describe the frequency of various involuntary measures in a national cohort of all patients diagnosed with anorexia nervosa. In a subsample of patients, we explored predictors of the first involuntary measure recorded.

METHOD

Descriptive statistics and Cox proportional hazard analyses were conducted using the national registers of Denmark covering the total population. Data from the National Patient Register and the Psychiatric Central Research Register including all psychiatric visits from 1969 onwards were merged with data from the National Register on Coercion covering 1999 onward. Involuntary measures registered between 2000 and 2013 were analyzed.

RESULTS

A total of 4,727 patients with a diagnosis of anorexia nervosa representing 16,592 admissions were included. Eighteen percent experienced at least one involuntary measure. A variety of measures were used with tube feeding being the most frequent followed by mechanical restraint, involuntary medication, physical restraint, constant observation, and sedative medication. A subsample of 2% of AN patients had more than 100 involuntary measures recorded. The first recorded involuntary measure was predicted by most but not all psychiatric comorbidities, especially schizophrenia, autism spectrum, and personality disorders, older age at first diagnosis, and previous admissions.

DISCUSSION

It is important to develop a more granular understanding of patients at risk of requiring involuntary treatment and to determine how best to treat them effectively with minimal use of involuntary measures.

Adverse life events increase risk for postpartum psychiatric episodes: A population-based epidemiologic study

BACKGROUND

Trauma histories may increase risk of perinatal psychiatric episodes. We designed an epidemiological population-based cohort study to explore if adverse childhood experiences (ACE) in girls increases risk of later postpartum psychiatric episodes.

METHODS

Using Danish registers, we identified women born in Denmark between January 1980 and December 1998 (129,439 childbirths). Exposure variables were ACE between ages 0 and 15 including: (1) family disruption, (2) parental somatic illness, (3) parental labor market exclusion, (4) parental criminality, (5) parental death, (6) placement in out-of-home care, (7) parental psychopathology excluding substance use, and (8) parental substance use disorder. Primary outcome was first occurrence of in- or outpatient contact 0-6 months postpartum at a psychiatric treatment facility with any psychiatric diagnoses, ICD-10, F00-F99 (N = 651). We conducted survival analyses using Cox proportional hazard regressions of postpartum psychiatric episodes.

RESULTS

Approximately 52% of the sample experienced ACE, significantly increasing risk of any postpartum psychiatric diagnosis. Highest risks were observed among women who experienced out-of-home placement, hazard ratio (HR) 2.57 (95% CI: 1.90-3.48). Women experiencing two adverse life events had higher risks of postpartum psychiatric diagnosis HR: 1.88 (95% CI: 1.51-2.36), compared to those with one ACE, HR: 1.24 (95% CI: 1.03-49) and no ACE, HR: 1.00 (reference group).

CONCLUSIONS

ACE primarily due to parental psychopathology and disability contributes to increased risk of postpartum psychiatric episodes; and greater numbers of ACE increases risk for postpartum psychiatric illness with an observed dose-response effect. Future work should explore genetic and environmental factors that increase risk and/or confer resilience.

OPUS study: Suicidal behaviour, suicidal ideation and hopelessness among patients with first-episode psychosis

Background

Patients with first-episode psychosis comprise a high-risk group in terms of suicide.

Aims

To identify predictive factors for suicidal behaviour and to examine the effect of integrated treatment on suicidal behaviour and hopelessness.

Method

A total of 341 patients with a first-episode schizophrenia-spectrum disorder were randomised to integrated treatment or treatment as usual.

Results

During the 1-year follow-up period, 11% attempted suicide. This was associated with female gender, hopelessness, hallucinations and suicide attempt reported at baseline, with the two latter variables being the only significant ones in the final multivariate model. The integrated treatment reduced hopelessness.

Conclusions

Hallucinations and suicide attempt before inclusion in the study were the most significant predictors of suicide attempt in the follow-up period.

The Diameter of Retinal Vessels Is Affected by Transient Ischemia of the Arm in Normal Persons

Purpose

Remote ischemic conditioning (RIC) implies that transient ischemia in a limb can affect perfusion in a target organ elsewhere in the body. The changes in perfusion can be assumed to be paralleled by changes in the vessel diameters in the target organ. It remains to be elucidated whether the diameter of normal retinal vessels can be used as a marker of RIC in vivo.

Methods

In 20 normal persons aged 20 to 31 years the Dynamic Vessel Analyzer (DVA) was used to measure the resting diameter and diameter changes during isometric exercise and flicker stimulation before, immediately after, and 1 hour after RIC induced by transient ischemia in the left arm.

Results

The baseline diameter of retinal venules was reduced nonsignificantly immediately after (P = 0.07) and significantly 1 hour after RIC (P = 0.009), whereas the baseline diameter of arterioles was unaffected by the intervention (P = 0.61). Arterial constriction induced by isometric exercise was significantly reduced immediately after RIC (P = 0.04), but not 1 hour after RIC (P = 0.99). None of the other diameter responses were affected by RIC (P = 0.22 for all comparisons).

Conclusions

The diameter of retinal vessels might potentially be a marker of ischemic conditioning in the body in general. The effect of RIC on retinal vascular diseases where ischemia is a part of the pathogenesis should be investigated.

COMT Val158Met and MTHFR C677T moderate risk of schizophrenia in response to childhood adversity

OBJECTIVE

Mesolimbic dopamine sensitization has been hypothesized to be a mediating factor of childhood adversity (CA) on schizophrenia risk. Activity of catechol-O-methyltransferase (COMT) Val158Met increases mesolimbic dopamine signaling and may be further regulated by methylenetetrahydrofolate reductase (MTHFR) C677T. This study investigates the three-way interaction between CA, COMT, and MTHFR.

METHODS

We conducted a nested case-control study on individuals born after 1981, linking population-based registers to study the three-way interaction. We included 1699 schizophrenia cases and 1681 controls, and used conditional logistic regression to report incidence rate ratios (IRRs).

RESULTS

Childhood adversity was robustly associated with schizophrenia. No main genetic effects were observed. MTHFR C677T increased schizophrenia risk in a dose-dependent manner per MTHFR T allele (P = 0.005) consequent upon CA exposure. After inclusion of the significant (P = 0.03) COMT × MTHFR × CA interaction, the risk was further increased per high-activity COMT Val allele. Hence, exposed COMT Val/Val and MTHFR T/T carriers had an IRR of 2.76 (95% CI, 1.66-4.61). Additional adjustments for ancestry and parental history of mental illness attenuated the results with the interaction being only marginally significant.

CONCLUSION

MTHFR C677T and COMT Val158Met interact with CA to increase risk of schizophrenia.

The Association Between School Achievement and Subsequent Development of Bipolar Disorder

Introduction

Prior studies have indicated that both high and low school achievement are associated with development of bipolar disorder (BD). We believe that the latter association may be due to the confounding effect of family history of mental disorder.

Objective

To further investigate the association between school achievement and subsequent development of BD by adding adjustment for family history of mental disorder.

Methods

We are conducting a historical prospective cohort study based on data from nationwide Danish registers. The cohort consists of all individuals born in Denmark 1986–97 of Danish-born parents, who were alive and living in Denmark at age 16 years, and who have completed final examinations in 9th grade between 2002 and 2014 (n = 578,247). The cohort members will be followed until death, emigration, development of bipolar disorder, or end of study, whichever comes first. Hazard rate ratios for bipolar disorder will be calculated in a Cox model using the z-score for examination grades as unit of exposure. The regression analyses will be adjusted for a series of potential confounders including family history of mental disorder.

Results

We expect to find a positive association between high school achievement and development of BD. In contrast, we expect to demonstrate that the association between low school achievement and BD detected in prior studies is due to confounding by family history of mental disorder. The results will be shown at the conference.

Conclusions

By further testing the potential link between eminence and BD, we hope to contribute to a more balanced perception of BD.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Infections and exposure to anti-infective agents and the risk of severe mental disorders: a nationwide study

OBJECTIVE

Severe infections are associated with increased risks of mental disorders; however, this is the first large-scale study investigating whether infections treated with anti-infective agents in the primary care setting increase the risks of schizophrenia and affective disorders.

METHOD

We identified all individuals born in Denmark 1985-2002 (N = 1 015 447) and studied the association between infections treated with anti-infective agents and the subsequent risk of schizophrenia and affective disorders during 1995-2013. Cox regression analyses were adjusted for important confounders.

RESULTS

Infections treated with anti-infective agents were associated with increased risks of schizophrenia by a hazard rate ratio (HRR) of 1.37 (95%-CI = 1.20-1.57) and affective disorders by a HRR of 1.64 (95%-CI = 1.48-1.82), fitting a dose-response and temporal relationship (P < 0.001). The excess risk was primarily driven by infections treated with antibiotics, whereas infections treated with antivirals, antimycotics, and antiparasitic agents were not significant after mutual adjustment. Individuals with infections requiring hospitalization had the highest risks for schizophrenia (HRR = 2.05; 95%-CI = 1.77-2.38) and affective disorders (HRR = 2.59; 95%-CI = 2.31-2.89).

CONCLUSION

Infections treated with anti-infective agents and particularly infections requiring hospitalizations were associated with increased risks of schizophrenia and affective disorders, which may be mediated by effects of infections/inflammation on the brain, alterations of the microbiome, genetics, or other environmental factors.

The diameter response of retinal arterioles in diabetic maculopathy is reduced during hypoxia and is unaffected by the inhibition of cyclo-oxygenase and nitric oxide synthesis

PURPOSE

Diabetic retinopathy is accompanied with changes in the diameter regulation and oxygenation of retinal vessels. Previous studies have shown that in normal persons and in diabetic patients without retinopathy hypoxia-induced vasodilatation is mediated by cyclo-oxygenase (COX) products and nitric oxide (NO). The purpose of the present study was to study whether these effects can be reproduced in patients with diabetic maculopathy.

METHODS

Eighteen patients with diabetic maculopathy aged 29-57 years were examined using the Dynamic Vessel Analyzer. The resting diameter and the diameter changes of retinal arterioles during isometric exercise and flicker stimulation were studied before and during breathing a hypoxic gas mixture. The examinations were also performed before and during intravenous infusion of the NOS inhibitor L-NMMA, and were repeated on a second day after topical administration of the COX-inhibitor diclofenac.

RESULTS

The diameter of retinal arterioles showed no significant change during hypoxia or L-NMMA infusion, or after topical application of diclofenac (p > 0.25 for all comparisons). The resting diameter of the venules was significantly increased during hypoxia (p = 0.003) and decreased during L-NMMA infusion (p < 0.0001). The diameter of retinal venules during isometric exercise increased significantly during hypoxia (p = 0.01). Flicker stimulation induced significant dilatation of the venules, which was significantly reduced during hypoxia and increased during L-NMMA infusion (p < 0.0001 for all comparisons).

CONCLUSION

Hypoxia-induced dilatation of retinal arterioles is severely reduced in patients with diabetic maculopathy. Future intervention studies aimed at normalizing the diameter regulation of retinal arterioles in diabetic patients should preferentially be conducted in the early stages of the disease where the potential for changing the vessel diameter is preserved. ClinicalTrials.gov identifier: NCT01689090.

Functional characterization of the ectopically expressed olfactory receptor 2AT4 in human myelogenous leukemia

The olfactory receptor (OR) family was found to be expressed mainly in the nasal epithelium. In the last two decades members of the OR family were detected to be functional expressed in different parts of the human body such as in liver, prostate or intestine cancer cells. Here, we detected the expression of several ORs in the human chronic myelogenous leukemia (CML) cell line K562 and in white blood cells of clinically diagnosed acute myeloid leukemia (AML) patients by RT-PCR and next-generation sequencing. With calcium-imaging, we characterized in greater detail the cell biological role of one OR (OR2AT4) in leukemia. In both cell systems, the OR2AT4 agonist Sandalore-evoked strong Ca²⁺ influx via the adenylate cyclase-cAMP-mediated pathway. The OR2AT4 antagonist Phenirat prevented the Sandalore-induced intracellular Ca²⁺ increase. Western blot and flow cytometric experiments revealed that stimulation of OR2AT4 reduced the proliferation by decreasing p38-MAPK phosphorylation and induced apoptosis via phosphorylation of p44/42-MAPK. Furthermore, Sandalore increased the number of hemoglobin-containing cells in culture. We described for the first time an OR-mediated pathway in CML and AML that can regulate proliferation, apoptosis and differentiation after activation. This mechanism offers novel therapeutic options for the treatment of AML.

Preserved Pressure Autoregulation but Disturbed Cyclo-Oxygenase and Nitric Oxide Effects on Retinal Arterioles during Acute Hypoxia in Diabetic Patients without Retinopathy

BACKGROUND

Acute hypoxia induces retinal vasodilatation, which depends on cyclooxygenase (COX) products and nitric oxide (NO) in vitro. However, it is unknown whether these mechanisms are active in diabetic patients and may contribute to the development of diabetic retinopathy.

METHODS

The Dynamic Vessel Analyzer was used to study the diameter regulation in retinal vessels during hypoxia in type 1 diabetic patients without retinopathy. The influence of NO and COX synthesis inhibition on the diameter of larger retinal vessels was studied during hypoxia, during isometric exercise and during flicker stimulation.

RESULTS

Increased arterial blood pressure during L-NMMA infusion and isometric exercise were paralleled by constriction of the retinal arterioles suggesting normal pressure autoregulation. Hypoxia significantly reduced the diameter responses during isometric exercise and during flicker stimulation as compared to normal persons.

CONCLUSION

The findings support that changes in metabolic autoregulation develop before changes in pressure autoregulation in diabetic patients.

Lack of effect of nitroglycerin on the diameter response of larger retinal arterioles in normal persons during hypoxia

PURPOSE

Retinal hypoxia with consequent changes in blood flow play a role in a number of vision-threatening diseases, such as diabetic retinopathy. Previous studies have shown that the inhibition of nitric oxide synthase (NOS) and cyclooxygenase (COX) products are involved in the diameter regulation of the retinal vessels during hypoxia. Therefore, the aim of the present study was to examine the effects of an NO donor combined with COX inhibition on the diameter regulation of retinal vessels during hypoxia in normal persons.

METHODS

Twenty normal persons aged 21-47 years were examined. The Dynamic Vessel Analyzer (DVA) was used to measure retinal vessel diameters at rest, during isometric exercise, and during flicker stimulation. The measurements were performed during normoxia and hypoxia before and after sublingual administration of the NO donor nitroglycerin, and were repeated on a second study day after topical administration of the COX-inhibitor diclofenac.

RESULTS

The resting diameter of arterioles and venules increased significantly during hypoxia (p < 0.0001). Hypoxia also significantly reduced the arteriolar constriction during isometric exercise, and the dilatation of the arterioles and venules during flicker stimulation (p < 0.0001). Diclofenac further reduced the arteriolar constriction induced by isometric exercise during hypoxia (p = 0.005). However, the NO-donor nitroglycerin had no effect on vascular diameters.

CONCLUSION

Diameter regulation of retinal vessels during hypoxia in normal persons can be influenced by the inhibition of COX products, but not by increasing the NO concentration. The findings suggest that the vasoactive effects of NO on retinal arterioles during hypoxia are saturated in normal persons.

Diameter changes of retinal arterioles during acute hypoxia in vivo are modified by the inhibition of nitric oxide and prostaglandin synthesis

PURPOSE

Inhibition of cyclooxygenase (COX) and nitric oxide synthesis (NOS) has previously been shown to modify hypoxia-induced relaxation of retinal arterioles in vitro. The purpose of the present study was to investigate whether these findings can be reproduced in vivo.

METHODS

Twenty healthy persons aged 20-55 years were examined. Using the dynamic vessels analyzer (DVA), the resting diameter and diameter changes during isometric exercise and flicker stimulation were studied before and during breathing of a hypoxic gas mixture. The examinations were carried out before and during intravenous infusion of the NOS-inhibitor l-NMMA, and were repeated on a second study day after topical administration of the COX-inhibitor diclofenac.

RESULTS

The resting diameter of retinal arterioles increased significantly during hypoxia and decreased significantly during l-NMMA infusion (p < 0.0001) which compensated for changes in the blood pressure. During hypoxia and l-NMMA infusion together contraction of retinal arterioles could not compensate for the increased blood pressure as assessed by a gain factor significantly lower than one (p = 0.002). The arteriolar contraction induced by isometric exercise was significantly reduced by diclofenac and flicker-induced dilatation of retinal arterioles was increased during l-NMMA infusion (p < 0.0001).

CONCLUSION

Diameter changes of retinal vessels during acute hypoxia in vivo are modified by inhibiting NO and prostaglandin synthesis. The evidence points to possible new targets of intervention on the diameter regulation of retinal arterioles in diseases where retinal hypoxia is part of the disease pathogenesis.