Therapeutic interventions for PTSD – current evidence on the the role of psychedelics

Introduction

Post-traumatic stress disorder (PTSD) is often a chronic condition, despite the existence of evidence-based treatment options. Psychotherapy is the designated first line treatment for PTSD, although high rates of psychiatric and medical comorbidity are observed among patients who have undergone treatment. The psychoactive properties of psychedelics may be of particular interest within a substance-assisted psychotherapy approach, offering new treatment opportunities for this debilitating disorder.

Objectives

Review current evidence, therapeutic context, and possible mechanisms of action of different types of psychedelics in the treatment of PTSD.

Methods

Literature review using Medline database.

Results

3,4-methylenedioxymethamphetamine (MDMA)-assisted psychotherapy appears to be a potentially safe, effective, and durable treatment for individuals with treatment-refractory PTSD. Based on a small number of studies, ketamine administration appears to result in temporary symptom relief and may, in combination with psychotherapy, lead to lasting reductions in PTSD symptoms. Although these have not yet been investigated in controlled studies, it is known that psilocybin and LSD induce psychoactive effects that could as well contribute to the psychotherapeutic treatment of PTSD.

Conclusions

The use of psychedelic compounds within a substance-assisted psychotherapy framework offers a novel method for pharmacotherapy-psychotherapy integration, although there is still much to learn from both a clinical and neurobiological perspective. It is necessary to generate more data regarding the safety and efficacy of psychedelics, in addition to research on cost-effectiveness, its use in mental health care infrastructure and also regarding the training of specialized therapists.

The use of soluble fibre for the management of chronic idiopathic large-bowel diarrhoea in police working dogs

Background

Chronic intermittent or persistent diarrhoea is a common condition in dogs and may be a reflex of gastrointestinal or non-gastrointestinal disorders. Besides diarrhoea, many athletes experience other gastrointestinal symptoms. Dietary fiber can help normalize colonic motility and transit time, support normal gastrointestinal microflora growth and provide fuel for colonocytes. This study aimed to evaluate dietary supplementation effectiveness with psyllium husk in police working dogs with chronic large-bowel diarrhoea. Twenty-two animals were selected. Concurrent conditions were ruled out through complete blood count and serum biochemistry. Fecal Clostridium and Salmonella were also screened. A soluble fiber, psyllium husk, was added to the diet at the dose of 4 tablespoons/day for 1 month. A daily log of fecal characteristics (type, frequency, and color) was maintained during the supplementation month and for an additional month, without supplementation.

Results

Response to treatment was classified as “very good” in 50% of animals, “good” in 40% of animals, and “poor” in 10% of cases. During the month of psyllium husk supplementation, defecation frequency decreased from 3.5 to 2.9 times a day, with 90% of animals showing consistent stools regularly and registering a mean increase of 2 kg in body weight. Beneficial effects were still observed during the second month, without psyllium husk supplementation.

Conclusion

Psyllium husk can be useful in the management of chronic large-bowel diarrhoea in working dogs, which exhibited lower defecation frequency, improved stool consistency, and gained weight. Effects were felt beyond the supplementation period. Alternative approaches for non-responsive cases need to be evaluated.

Intraarticular triamcinolone hexacetonide, stanozolol, Hylan G-F 20 and platelet concentrate in a naturally occurring canine osteoarthritis model

Osteoarthritis (OA) is a disease transversal to all mammals, a source of chronic pain and disability, a huge burden to societies, with a significant toll in healthcare cost, while reducing productivity and quality of life. The dog is considered a useful model for the translational study of the disease, closely matching human OA, with the advantage of a faster disease progression while maintaining the same life stages. In a prospective, longitudinal, double-blinded, negative controlled study, one hundred (N = 100) hip joints were selected and randomly assigned to five groups: control group (CG, n = 20, receiving a saline injection), triamcinolone hexacetonide group (THG, n = 20), platelet concentrate group (PCG, n = 20), stanozolol group (SG, n = 20) and hylan G-F 20 group (HG). Evaluations were conducted on days 0 (T0, treatment day), 8, 15, 30, 60, 90, 120, 150 and 180 days post-treatment, consisting of weight distribution analysis and data from four Clinical Metrology Instruments (CMI). Kaplan-Meier estimators were generated and compared with the Breslow test. Cox proportional hazard regression analysis was used to investigate the influence of variables of interest on treatment survival. All results were analyzed with IBM SPSS Statistics version 20 and a significance level of p < 0.05 was set. Sample included joints of 100 pelvic limbs (of patients with a mean age of 6.5 ± 2.4 years and body weight of 26.7 ± 5.2 kg. Joints were graded as mild (n = 70), moderate (n = 20) and severe (n = 10) OA. No differences were found between groups at T0. Kaplan-Meier analysis showed that all treatments produced longer periods with better results in the various evaluations compared to CG. Patients in HG and PCG took longer to return to baseline values and scores. A higher impact on pain interference was observed in THG, with a 95% improvement over CG. PCG and HG experienced 57-81% improvements in functional evaluation and impairments due to OA, and may be a better options for these cases. This study documented the efficacy of several approaches to relieve OA clinical signs. These approaches varied in intensity and duration. HG and PCG where the groups were more significant improvements were observed throughout the follow-up periods, with lower variation in results.

Deep muscle-proteomic analysis of freeze-dried human muscle biopsies reveals fiber type-specific adaptations to exercise training

Skeletal muscle conveys several of the health-promoting effects of exercise; yet the underlying mechanisms are not fully elucidated. Studying skeletal muscle is challenging due to its different fiber types and the presence of non-muscle cells. This can be circumvented by isolation of single muscle fibers. Here, we develop a workflow enabling proteomics analysis of pools of isolated muscle fibers from freeze-dried human muscle biopsies. We identify more than 4000 proteins in slow- and fast-twitch muscle fibers. Exercise training alters expression of 237 and 172 proteins in slow- and fast-twitch muscle fibers, respectively. Interestingly, expression levels of secreted proteins and proteins involved in transcription, mitochondrial metabolism, Ca2+ signaling, and fat and glucose metabolism adapts to training in a fiber type-specific manner. Our data provide a resource to elucidate molecular mechanisms underlying muscle function and health, and our workflow allows fiber type-specific proteomic analyses of snap-frozen non-embedded human muscle biopsies.

Pilonidal Disease Treatment By Radial Laser Surgery (FilaC™): The First Finnish Experience

BACKGROUND AND AIMS

Pilonidal disease is common, and it afflicts especially young adults, causing disability. Several types of treatment methods are applicable, but no consensus exists regarding the best method. The aim of our study was to assess the novel radial laser probe treatment in pilonidal disease and report the success rate and recurrence rate.

METHODS

We studied retrospectively 86 patients who, according to our hospital patient records, underwent radial laser probe surgery between January 2017 and September 2019.

RESULTS

In a mean follow-up time of 14 months, the success rate at 2 months was 86%. Most operations were done under local anesthesia on a day-surgery basis. The recovery time was rapid, and median sick leave was 12 days. Of those initially successfully treated, 3% developed a recurrence. Altogether 17% of the patients underwent a re-operation. Spillage of pus during surgery, however, reduced the success rate to 53%.

CONCLUSION

Radial laser probe treatment is a quick, safe, and minimally invasive treatment choice for pilonidal disease, especially when no active infection is present.

Clinical and diagnostic imaging findings in police working dogs referred for hip osteoarthritis

Background

Osteoarthritis (OA) is the most commonly diagnosed joint disease in veterinary medicine, with at least 80% of the cases of lameness and joint diseases in companion animals being classified as OA. Sporting and working animals are more predisposed to develop OA since they are exposed to chronic fatigue injuries, leading to bone and muscular tissue damage and failure, resulting in clinical signs. To characterize the clinical signs and diagnostic findings of Police working dogs presenting with bilateral hip OA at the time of diagnosis. Fifty animals were evaluated with a bodyweight ≥ 15 kg, be older than two years, and without any medication or nutritional supplements for ≥ 6 weeks.

Results

Weight distribution, joint range of motion at flexion and extension, thigh girth, digital thermography, and radiographic signs were collected. Data from different Clinical Metrology Instruments (CMI) were collected: Canine Brief Pain Inventory, Liverpool Osteoarthritis in Dogs, Canine Orthopedic Index, and the Hudson Visual Analogue Scale. Results were compared by breed, age, sex, and Orthopaedic Foundation for Animals hip grades with the Independent Samples T-Test, ANOVA followed by a Bonferroni post hoc test, and Pearson correlation coefficient, with p < 0.05. The sample included 30 males and 20 females, with a mean age of 6.5 ± 2.4 years and a bodyweight of 26.7 ± 5.2 kg. Animals with weight distribution below normal levels had significant variations of joint extension and function scores. This evaluation was the only not correlated with at least one breed. Animals with caudolateral curvilinear osteophyte showed a poorer clinical presentation and worse scores in all considered CMIs. Radiographic changes correlated with age and corresponded to worse CMIs scores and weight distribution. Dutch Shepherd Dogs showed better CMI scores than the other considered breeds.

Conclusions

Police working dogs presented with complaints related to hip OA at an early stage of the disease. Hip scores influenced clinical presentation, with moderate cases showing lower thigh girth and worse pain interference and severity, and function scores than mild cases. Patients with severe OA had lower thermographic evaluations than patients with moderate OA. Age was the primary variable influencing considered CMI scores.

Pre-test probability of obstructive coronary artery disease in the new guidelines: too much, too little or just enough?

Background

Previous 2013 ESC guidelines recommended the use of the Modified Diamond-Forrester method to assess the pre-test probability (PTP) of obstructive coronary artery disease (CAD). The 2019 ESC Chronic Coronary Syndrome guidelines updated this recommendation with a major downgrade in PTP. The aim of this study was to compare the performance of these two methods in patients with stable chest pain undergoing coronary computed tomography angiography (CCTA) for suspected CAD.

Methods

We performed a retrospective analysis on prospectively collected data from a cohort of consecutive patients undergoing CCTA for suspected CAD from October 2016 to 2019. Key exclusion criteria were age &lt;30 years-old, known CAD, suspected acute coronary syndrome or symptoms other than chest pain. Obstructive CAD was defined as any luminal stenosis ≥50% on CCTA. Whenever invasive coronary angiography (ICA) was subsequently performed, patients were reclassified if luminal stenosis was &lt;50%. The two PTP prediction models were assessed for calibration and discrimination.

Results

A total of 320 patients (median age 63 years [IQR 53–70], 59% women) were included. Chest pain characteristics were: 48% atypical angina, 38% non-anginal chest pain, 14% typical angina. The observed prevalence of obstructive CAD was 16.3% (n=52). Patients with obstructive CAD were more often male, were significantly older and had a higher prevalence of typical angina and cardiovascular risk factors (except for family history of CAD). On average, individual PTP was 22.1% lower in the new guidelines. The 2013 prediction model significantly overestimated the likelihood of obstructive CAD (mean PTP 37.3% vs 16.3%; relative overestimation of 130%, p-value for miscalibration 0.005). The updated 2019 method showed good calibration for predicting the likelihood of obstructive CAD (mean PTP 15.2% vs 16.3%; relative underestimation of 6.5%, p-value for miscalibration 0.712). The two approaches showed similar discriminative power, with a C-statistics of 0.730 and 0.735 for the 2013 and 2019 methods, respectively (p-value for comparison 0.933). Stratification by gender produced similar results.

Conclusions

In patients with stable chest pain undergoing CCTA, the updated 2019 prediction model allows for a more precise estimation of pre-test probabilities of obstructive CAD than the previous model. Adoption of this new score may improve disease prediction and change the downstream diagnostic pathway in a significant proportion of cases.

Graph 1

Funding Acknowledgement

Type of funding source: None

Health-related quality of life in patients with untreated cavernous malformations of the central nervous system

BACKGROUND AND PURPOSE

To estimate health-related quality of life (HRQOL) in patients with untreated cavernous malformation of the CNS [cavernous cerebral malformations (CCMs)].

METHODS

We performed a cross-sectional observational study on patients with CCMs admitted to our department from 1 November 2017 to 10 January 2020 using standardized interviews [short-form-36 questionnaire, hospital anxiety and depression score (HADS-A/D), CCM perception questionnaire]. Included criteria were diagnosis of an untreated CCM and information about the diagnosis in a specialized CCM consultation. Health-related quality of life (HRQOL) data were analyzed and compared to the German normal population. Uni- and multivariate analyses were carried out to identify variables with impact on outcome.

RESULTS

Two hundred nineteen (93%) of 229 eligible patients were included. Mean age was 46.3 ± 14.7 (18-86) years; 136 (62%) were female. Ninety-eight (45%) patients presented with symptomatic hemorrhage (SH), and 17 (8%) with repetitive SH. Ninety-two (42%) patients were asymptomatic. Thirty-seven patients (17%) suffered from cavernoma-related epilepsy. Twenty-eight patients (13%) suffered from familial CCMs. Patients showed significantly decreased component scores and subdomain scores compared to the normal population, with effects ranging from small to large. This accounted largely also for asymptomatic patients (except for physical component score and main physical subdomains). Multivariate regression analysis confirmed impact of functional impairment on physical component score. HADS-A was significantly increased. HADS-A/D strongly correlated with mental component score and individual perception of the CCM.

CONCLUSIONS

Patients with the diagnosis of a CCM showed decreased HRQOL compared to the normal population even when not suffering functional impairment or neurological symptoms. Our data may function as benchmarks in evaluation of different (future) management strategies.

Changes in physiological, haematological and biochemical parameters in police working dogs during a treadmill incremental exercise test

This study aimed to evaluate the physiological, haematological and biochemical changes during a treadmill incremental exercise test (IET). Animals were submitted to five stages of 6 min each, at 6, 7, 8, 9 and 10 mph, at an inclination of 5%. Blood samples were collected at rest (T0), immediately after exercise (T5) and after a 20 min rest period (T6), to determine complete blood count, urea, creatinine, creatine kinase, aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, total plasma protein, albumin, alkaline phosphatase (AP), cholesterol, triglycerides (Trig), Ca2+, Na+, K+ and Cl-. Blood lactate (BL), heart rate (HR), rectal temperature (RT) and glycaemia were measured at rest (T0), after each stage (T1-T5) and after the rest period (T6). Variations were recorded between T0 and T5 in red blood cells, haemoglobin, AP, Na+, K+ (P<0.01), Trig (P<0.05), Ca2+ and Cl- (P<0.02). Differences were observed in BL at T5 (P<0.02) and T6 (P<0.02), RT at T2-T6 (P<0.01), HR at T3-T5 (P<0.01) and glycaemia at T2-T4 (P<0.01) and T5 (P<0.05). This study is a novel description of the shifts of physical fit police working dogs during this IET protocol.

Psychiatric and neurocognitive consequences of endogenous hypercortisolism

Psychiatric and neurocognitive symptoms due to hypercortisolism were already described by Harvey Cushing in his original paper on patients with Cushing's syndrome (CS). Nowadays, it is well known that psychiatric and cognitive complaints are two of the most common, and most distressing, symptoms in patients with CS. Psychiatric symptoms are indeed a major clinical manifestation of CS. The most commonly observed psychiatric conditions are depression and anxiety, whilst mania and psychosis are less common. Several domains of cognitive function are impaired at diagnosis, including episodic and working memory, executive function and attention. Following treatment, one-fourth of the patients still experience depressed mood, and the cognitive impairments are only partially restored. Consequently, quality of life in patients with CS is severely and persistently affected. Neuroimaging studies have also illustrated the deleterious effects of hypercortisolism on the brain by demonstrating reduced grey matter volumes and cortical thickness, altered resting-state functional responses and during cognitive tasks, as well as widespread reduced white matter integrity, especially in structures important for cognitive function and emotional processing, both before and after successful abrogation of hypercortisolism. In this paper, we summarize the current knowledge on the psychiatric and neurocognitive consequences of hypercortisolism in patients with CS, both before, and after successful treatment. In addition, we review the structural and functional brain abnormalities associated with hypercortisolism and discuss the influence of these factors on quality of life.

Clostridium difficile toxins or infection induce upregulation of adenosine receptors and IL-6 with early pro-inflammatory and late anti-inflammatory pattern

Clostridium difficile causes intestinal inflammation, which increases adenosine. We compared the expression of adenosine receptors (AR) subtypes A1, A2A, A2B, and A3 in HCT-8, IEC-6 cells, and isolated intestinal epithelial cells, challenged or not with Clostridium difficile toxin A and B (TcdA and TcdB) or infection (CDI). In HCT-8, TcdB induced an early A2BR expression at 6 h and a late A2AR expression at 6 and 24 h. In addition, both TcdA and TcdB increased IL-6 expression at all time-points (peak at 6 h) and PSB603, an A2BR antagonist, decreased IL-6 expression and production. In isolated cecum epithelial cells, TcdA induced an early expression of A2BR at 2s and 6 h, followed by a late expression of A2AR at 6 and 24 h and of A1R at 24 h. In CDI, A2AR and A2BR expressions were increased at day 3, but not at day 7. ARs play a role in regulating inflammation during CDI by inducing an early pro-inflammatory and a late anti-inflammatory response. The timing of interventions with AR antagonist or agonists may be of relevance in treatment of CDI.

Células-tronco mesenquimais de origem adiposa na fase de proliferação do processo de cicatrização de queimaduras frias

RESUMO A criocirurgia tem sido utilizada no tratamento de diferentes enfermidades de sistemas e órgãos. Contudo, são relatados efeitos adversos, como cicatrização lenta, cicatrizes extensas, disfunção estética e funcional. As lesões que ocorrem naturalmente pela exposição ao frio extremo, comumente, resultam em gangrena. O presente trabalho teve como objetivo avaliar a influência das células-tronco mesenquimais de origem adiposa (ADSCs) na fase de proliferação da cicatrização de feridas cutâneas. Por meio da aplicação do nitrogênio líquido pela técnica do spray aberto, realizou-se a indução de uma ferida, de aproximadamente 15mm de diâmetro, na região dorsal de cada rato. A ferida recebeu o tratamento de acordo com o grupo ao qual pertencia: 1) aplicação das ADSCs no 15º dia (grupo tratado); 2) aplicação da solução cloreto de sódio 0,9% no 15º dia (grupo sham); 3) nenhuma intervenção até o momento da eutanásia (grupo controle). O grupo tratado com as ADSCs apresentou as maiores taxas de contração média das feridas e obteve diferença estatisticamente significativa em relação ao grupo sham quanto à neovascularização. A terapia com as ADSCs proporcionou uma relevante evolução clínica das feridas, podendo ser constatada ao final do período de avaliação por cicatrizes mais estreitas e compridas.

A report on the use of a single intra-articular administration of autologous platelet therapy in a naturally occurring canine osteoarthritis model - a preliminary study

Background

Osteoarthritis (OA) represents a significant burden to societies, as it affects quality of life, performance and poses a large healthcare cost. We aimed to describe the use of a single intra-articular (IA) injection of an autologous platelet therapy in the management of osteoarthritis (OA) in a naturally occurring canine model.

Methods

Fifteen police working dogs with bilateral hip OA were treated with 3 ml of platelet concentrate per hip joint, produced with the V-PET kit. Response to treatment was measured by the Canine Brief Pain Inventory (CBPI, divided in pain interference score – PIS, and Pain Severity Score - PSS), Liverpool Osteoarthritis in Dogs (LOAD), Canine Orthopedic Index (COI, divided in four dimensions: function, gait, stiffness and quality of life - QOL) and the Hudson Visual Analogue Scale (HVAS). Seven different time points were considered: T0 (before treatment), T1 (after 15 days), T2, T3, T4, T5 and T6 (after 1, 2, 3, 4 and 5 months respectively). Results from each evaluation moment were compared with T0 with a Paired Samples T-Test, and a p < 0.05 was set.

Results

Significant differences were observed at T1 (p < 0.01 for HVAS, PSS, COI, Gait and QOL; p = 0.01 for PIS; p = 0.02 for Function; and p < 0.05 for Stiffness), T2 (p < 0.01 for PSS, PIS and Gait; p = 0.01 for COI; p = 0.02 for HVAS, Function and QOL; and p = 0.04 for Stiffness), T3 (p < 0.01 for HVAS, PSS, PIS, Function and Gait; p = 0.01 for COI; and p = 0.02 for QOL), T4 (p < 0.01 for PSS; p = 0.03 for PIS and Gait), T5 (p < 0.01 for COI, Function and Gait; p = 0.03 for PSS, PIS and Stiffness), T6 (p < 0.01 for PSS, Function and Gait; p = 0.04 for PIS; p < 0.05 for COI) and T7 (p < 0.01 for PSS, Function and Gait; p = 0.01 for COI; and p < 0.05 for PIS).

Conclusions

Autologous platelet therapy was used without apparent harm in the subjects. A single administration produced significant improvements, which lasted several months, and therefore warrants further study.

Structural properties of additive binary hard-sphere mixtures

An approach to obtain the structural properties of additive binary hard-sphere mixtures is presented. Such an approach, which is a nontrivial generalization of the one recently used for monocomponent hard-sphere fluids [S. Pieprzyk, A. C. Brańka, and D. M. Heyes, Phys. Rev. E 95, 062104 (2017)2470-004510.1103/PhysRevE.95.062104], combines accurate molecular-dynamics simulation data, the pole structure representation of the total correlation functions, and the Ornstein-Zernike equation. A comparison of the direct correlation functions obtained with the present scheme with those derived from theoretical results stemming from the Percus-Yevick (PY) closure and the so-called rational-function approximation (RFA) is performed. The density dependence of the leading poles of the Fourier transforms of the total correlation functions and the decay of the pair correlation functions of the mixtures are also addressed and compared to the predictions of the two theoretical approximations. A very good overall agreement between the results of the present scheme and those of the RFA is found, thus suggesting that the latter (which is an improvement over the PY approximation) can safely be used to predict reasonably well the long-range behavior, including the structural crossover, of the correlation functions of additive binary hard-sphere mixtures.

Vitamin D in Infant Formula and Enteral Products by Liquid Chromatography: Collaborative Study

Results from a collaborative study of a new liquid chromatographic (LC) method for determination ofvitamin D in infant formulas and enteral products are presented. Each of 15 laboratories was provided with 11 blind duplicate samples covering a range ofapproximately 200-500 International Units/quart (normal dilution), a system suitability sample, and the U.S. Pharmacopeia ergo- and cholecalciferol standards. Product types included liquid and powder forms of milk (whey and casein), soy, and hydrolyzed protein-based infant formulas and enteral products. The method includes a single liquid-liquid extraction following saponification, solid-phase extraction,and then concentration by evaporation. An isocratic, nonaqueous, chromatographic system with reversed-phase, zero end- capped C18 column, and UV detector set at 265 nm are used. Statistical evaluation ofdata from participating laboratories showthe average reproducibility and repeatability of the method across all samples to be excellent, with RSDR and RSDr values of 13.48 and 9.44, respectively, after elimination of out liers. The LC method for determination of vitamin D in infant formulas and enteral products has been adopted by AOAC INTERNATIONAL.

Adherence to a Mediterranean Dietary Pattern and Functional Parameters: A Cross-Sectional Study in an Older Population

OBJECTIVES

In older adults, diet and physical activity are among the most important behaviours that influence health. The Mediterranean Dietary Pattern has been related to longevity and can benefit physical function in older adults. The present study aims to quantify the association of adherence to a Mediterranean Dietary Pattern with physical functioning through by handgrip strength, as well as, with sedentary behaviour based on sitting time, in a sample of older adults.

METHODS

A cross-sectional study was conducted in 1,491 older adults ≥ 65 years old. The adherence or non-adherence to a Mediterranean Dietary Pattern was assessed using the previously validated and translated 14 item questionnaire, the PREDIMED (Prevención com Dieta Mediterránea). Handgrip strength was measured with a Jamar Dynamometer. Sitting time per day was used as an indicator of sedentary behaviour. Multinomial logistic regressions were performed to quantify the association of adherence to a Mediterranean Dietary Pattern with handgrip strength and sitting time.

RESULTS

Compared to participants who adhered to a Mediterranean Dietary Pattern, those who did not adhere to this diet have a significantly higher adjusted odds ratio for low handgrip strength [adjusted odds ratio: 1.50; 95% confidence interval: 1.09-2.05], as well as for longer sitting time [adjusted odds ratio: 1.43; 95% confidence interval: 1.04-1.96].

CONCLUSION

In older adults, the non-adherence to a Mediterranean Dietary Pattern was associated with both lower values of handgrip strength and longer sitting time.

161 Increasing the dose of cloprostenol sodium reduced pregnancy losses but did not increase pregnancies per AI in lactating dairy cows

Incomplete luteolysis after last prostaglandin F2α (PGF2α) of Ovsynch in fertility programmes decreases the likelihood of pregnancy per AI (P/AI) in lactating dairy cows (Martins et al. 2011 J. Dairy Sci. 94, 2815-2824; https://doi.org/10.3168/jds.2010-3652). Two doses of PGF2α 24h apart increased the percentage of cows with complete luteolysis (Brusveen et al. 2009 J. Dairy Sci. 92, 1412-1422; https://doi.org/10.3168/jds.2008-1289). Increasing the dose of cloprostenol sodium (CLO) from 0.5 to 0.75mg enhanced luteolytic properties and increased P/AI (Giordano et al. 2013 Theriogenology 80, 773-783; https://doi.org/10.1016/j.theriogenology.2013.07.003). We hypothesised that a 1.0-mg dose of CLO would not have different P/AI compared with two 0.5-mg doses 24h apart but would have greater P/AI than a single dose (0.5mg) in a timed AI programme. We also hypothesised that dose of CLO would not affect pregnancy losses. The objective was to determine the effect of cloprostenol dose on P/AI and pregnancy losses in lactating dairy cows. Lactating dairy cows (n=944) were randomly assigned to three treatments of various CLO doses at final PGF2α of Ovsynch: single dose (0.5 mg; n=338), two doses 24h apart (0.5mg each; n=311), or double dose (1.0 mg; n=295). Cows were randomly assigned to treatments by parity, synchronisation status, and type of AI (Double-Ovsynch (n=546) for first AI or GGPG (GnRH-GnRH-PGF2α-GnRH; n=398) for second and third AI). Cows were classified as either synchronised or non-synchronised based on evaluation of follicle and corpora lutea (CL) development during synchronisation protocols using ultrasound. Synchronised cows were defined as having at least one Day 7 and Day 14 CL at time of treatment. About 72% of all cows were classified as synchronised. Synchrony was not different between treatments. Within-cow pregnancy-specific protein B levels on Days 17 and 24 post-AI were used to determine pregnancy at 24 days. Pregnancy was confirmed via ultrasonography 34 days post-AI. All binomial variables were analysed using chi-square with PROC FREQ in SAS (SAS Institute Inc.). There were no differences between treatments on P/AI on d 24 post-AI (55, 50, and 53% for 0.5mg, two doses of 0.5mg 24h apart, and 1.0mg, respectively; P=0.35). At 24 days post-AI, P/AI were greater in synchronised versus non-synchronised cows (57 vs. 42%; P&lt;0.0001). Older cows (third parity or greater) had reduced P/AI (44%) compared with first-parity (60%) and second-parity (54%) cows at 24 days post-AI (P=0.0001). At 24 days post-AI, P/AI in cows inseminated following Double-Ovsynch were greater than those in cows that were resynchronised using GGPG (58 vs. 46%; P=0.0001). Pregnancy loss between 24 and 34 days post-AI was greater for cows receiving 0.5mg (single dose) versus two 0.5-mg doses 24h apart or 1.0mg (12, 6, and 5%, respectively; P=0.02). In summary, cows receiving a double dose (1.0mg) of CLO had similar P/AI to cows receiving two doses of 0.5mg 24h apart. Unexpectedly, P/AI at 24 days post-AI in cows from the single-dose group were not different from those of cows treated with a double dose and two doses 24h apart. Despite numerically higher P/AI, cows that received a single dose had greater pregnancy loss between 24 and 34 days post-AI. Further analyses of effects of treatment on luteal function assessed with colour Doppler may provide information about fertility outcomes.