How local antipredator response unbalances the rock-paper-scissors model

Antipredator behavior is a self-preservation strategy present in many biological systems, where individuals join the effort in a collective reaction to avoid being caught by an approaching predator. We study a nonhierarchical tritrophic system, whose predator-prey interactions are described by the rock-paper-scissors game rules. We perform a set of spatial stochastic simulations where organisms of one out of the species can resist predation in a collective strategy. The drop in predation capacity is local, which means that each predator faces a particular opposition depending on the prey group size surrounding it. Considering that the interference in a predator action depends on the prey's physical and cognitive ability, we explore the role of a conditioning factor that indicates the fraction of the species apt to perform the antipredator strategy. Because of the local unbalancing of the cyclic predator-prey interactions, departed spatial domains mainly occupied by a single species emerge. Unlike the rock-paper-scissors model with a weak species because of a nonlocal reason, our findings show that if the predation probability of one species is reduced because individuals face local antipredator response, the species does not predominate. Instead, the local unbalancing of the rock-paper-scissors model results in the prevalence of the weak species' prey. Finally, the outcomes show that local unevenness may jeopardize biodiversity, with the coexistence being more threatened for high mobility.

Mobility-limiting antipredator response in the rock-paper-scissors model

Antipredator behavior is present in many biological systems where individuals collectively react to an imminent attack. The antipredator response may influence spatial pattern formation and ecosystem stability but requires an organism's cost to contribute to the collective effort. We investigate a nonhierarchical tritrophic system, whose predator-prey interactions are described by the rock-paper-scissors game rules. In our spatial stochastic simulations, the radius of antipredator response defines the maximum prey group size that disturbs the predator's action, determining the individual cost to participate in antipredator strategies. We consider that each organism contributes equally to the collective effort, having its mobility limited by the proportion of energy devoted to the antipredator reaction. Our outcomes show that the antipredator response leads to spiral patterns, with the segregation of organisms of the same species occupying departed spatial domains. We found that a less localized antipredator response increases the average size of the single-species patches, improving the protection of individuals against predation. Finally, our findings show that although the increase of the predation risk for a more localized antipredator response, the high mobility constraining benefits species coexistence. Our results may help ecologists understand the mechanisms leading to the stability of biological systems where locality is crucial to behavioral interactions among species.

“This is not a doctors thing, it is witchcraft” - A case report of acute psychosis concomitant to primary hyperparathyroidism

Introduction

Primary hyperparathyroidism (PHPT), usually caused by a parathyroid adenoma, is characterized by a pathologically high secretion of parathyroid hormone and consequent hypercalcemia. PHPT has a high prevalence among elderly patients and might be responsible for neuropsychiatric symptoms.

Objectives

We aim to report the rare manifestation of acute psychosis accompanying a PHPT diagnosis, and to discuss the neurobiological relationship between hyperparathyroidism, hypercalcaemia and neuropsychiatric symptoms.

Methods

We present a clinical case based on patient’s history and clinical data, along with a literature review on PHPT neuropsychiatric symptons.

Results

We present the case of a 68-year-old man diagnosed with PHPT in November 2019. He was brought up to psychiatric evaluation for the first time in May 2020 upon behavioral changes (aggressiveness and bizarre rituals). The patient described the sensation of burns scattered throughout the body since January 2020, felling anxious and frightened, sleeping poorly and progressive social isolation. He presented delusional ideas of mystical and paranoid content. No significant cognitive impairments were found. The patient’s psychosis was partially responsive to atypical antipsychotics. He’s waiting for surgery. Hypercalcaemia might manifest as mood disorders, cognitive changes and rarely as acute psychosis. Although there is not yet a clear mechanism to explain it, high calcium levels seem to cause neurotoxicity and neurotransmission dysfunction. Restoration of normal calcium levels tend to resolve neuropsychiatric symptoms, but in PHPT parathyroidectomy is usually recommended.

Conclusions

Neuropsychiatric symptoms are responsible for great disability, and demand an organic in-depth investigation. A multidisciplinary team approach must always be considered in the management of such conditions.

Behavioural movement strategies in cyclic models

The spatial segregation of species is fundamental to ecosystem formation and stability. Behavioural strategies may determine where species are located and how their interactions change the local environment arrangement. In response to stimuli in the environment, individuals may move in a specific direction instead of walking randomly. This behaviour can be innate or learned from experience, and allow the individuals to conquer or the maintain territory, foraging or taking refuge. We study a generalisation of the spatial rock-paper-scissors model where individuals of one out of the species may perform directional movement tactics. Running a series of stochastic simulations, we investigate the effects of the behavioural tactics on the spatial pattern formation and the maintenance of the species diversity. We also explore a more realistic scenario, where not all individuals are conditioned to perform the behavioural strategy or have different levels of neighbourhood perception. Our outcomes show that self-preservation behaviour is more profitable in terms of territorial dominance, with the best result being achieved when all individuals are conditioned and have a long-range vicinity perception. On the other hand, invading is more advantageous if part of individuals is conditioned and if they have short-range neighbourhood perception. Finally, our findings reveal that the self-defence strategy is the least jeopardising to biodiversity which can help biologists to understand population dynamics in a setting where individuals may move strategically.

On Becoming Ill: An Exploration of the Concept of “Transition” to a Mental Disorder

Introduction

As a general problem in nosology, the moment when one becomes ill may be hard to define. In Psychiatry, the boundaries of disease may be more difficult to establish. In the last decade, we’ve been observing a growing interest in early diagnosis in this field, and the concept of “transition” to a mental illness became an important topic of discussion with implications in clinical practice.

Objective

To review different author's models of evolution of symptoms and transition to mental illness and discuss their advantages and limitations in the actual context of Psychiatry research and clinical practice.

Aim

To increase understanding on the different paradigms of becoming ill and their relevance to present and future psychiatric practice.

Methods

Non-systematic review of literature devoted to the creation of models that describe the establishment of a mental disorder.

Results

One of the first accounts of becoming mentally ill was developed by K. Jaspers within a phenomenological life-history analysis. Nonetheless, a cross-sectional approach to diagnosis has dominated Psychiatry for most of the time. With the advent of early intervention studies, longitudinal models of disease have been emphasized. The concept of a transition to disease was then operationalized but also highly criticized. Recently, McGorry proposed a staging model for psychiatric disorders in continuum with the non-clinical population. Finally, a dynamic systems approach to diagnosis in Psychiatry will be discussed.

Conclusion

Driven by research in early phases of mental illnesses, current models of disease propose a longitudinal approach that emphasizes the complex and non-linear course of symptom clusters.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Evaluation of collected outcome measures in axial spondyloarthritis in daily-care rheumatology settings: the experience of the RHEVER network

OBJECTIVES

Nowadays, the recommended measures for optimal monitoring of axial Spondyloarthritis (ax-SpA) disease activity are either BASDAI and CRP, or ASDAS-CRP. However, there could be a gap between recommendations and daily practice. We aimed to determine the measures collected by rheumatologists in an ax-SpA follow-up visit, and to determine the impact of a meeting (where rheumatologists reached a consensus on the measures to be collected) on the collection of such measures.

METHODS

A consensual meeting of a local network of 32 rheumatologists proposed, four months later, to report at least the BASDAI score in the medical file of every ax-SpA patient at every follow-up visit. An independent investigator reviewed the medical files of 10 consecutive patients per rheumatologist, seen twice during the year (e.g. before and after the meeting). The most frequently collected measures were assessed, and then, the frequency of collection before and after the meeting was compared.

RESULTS

A total of 456 medical files from 228 patients were reviewed. Treatment (>60%), CRP (51.3%) and total BASDAI (28.5%) were the most reported measures in medical files. Before/After the meeting, the frequencies of collected measures in medical files were 28.5%/51.7%, 51.3%/52.2%, 16.7%/31.6% and 0.9%/6.1% for BASDAI, CRP, BASDAI + CRP and ASDAS, respectively reaching a statistically significance for BASDAI, ASDAS and BASDAI+CRP (p<0.05).

CONCLUSIONS

This study revealed a low rate of systematic report of the recommended outcome measures in ax-SpA. However, it suggests that a consensual meeting involving practicing rheumatologists might be relevant to improve the implementation of such recommendations.

[New melanoma immunotherapies: mechanisms of action, efficiency and management of toxicities]

In recent years the therapy of metastatic melanoma has been revolutionized from a disease with very few efficient treatment options to one with access to multiple therapies which can impact on patient survival. Two main classes of therapies have been developed: 1. Immunotherapy by immune checkpoint inhibitors and 2. Small molecule inhibitors of the MAPK pathway. Immunotherapies achieved by either inhibition of CTLA-4 or the PD1/PD-Ll axes are impacting the overall survival in an important fraction of patients. In addition, the side effects of these immune therapy approaches require early detection by all the specialists involved as well as early management according to precise guidelines for optimal outcome.

Spinal and pelvic parameters in Marfan’s syndrome and their relevance to surgical planning

Spinal deformities are a common feature of Marfan’s syndrome and can be a significant cause of morbidity. The morphology of the scoliosis associated with this condition was previously described by Sponseller, but no correlation with the pelvic parameters has been seen. We performed a retrospective radiological study of 58 patients with scoliosis, secondary to Marfan’s syndrome and related the findings in the thoracolumbar spine to the pelvic parameters, including pelvic version (tilt), pelvic incidence and sacral slope. Our results showed marked abnormalities in the pelvic values compared with those found in the unaffected population, with increased retroversion of the pelvis in particular. In addition we found a close correlation between the different patterns of pelvic parameters and scoliosis morphology. We found that pelvic abnormalities may partially dictate the spinal disorders seen in Marfan’s syndrome. Our results supplement the well-established Sponseller classification, as well as stressing the importance of considering the orientation of the pelvis when planning surgery.

Tolerance and short term efficacy of rituximab in 43 patients with systemic autoimmune diseases

OBJECTIVE

To assess the tolerance and efficacy of rituximab in patients with various autoimmune diseases seen in daily rheumatological practice.

METHODS

866 rheumatology and internal medicine practitioners were contacted by e-mail to obtain the files of patients treated with rituximab for systemic autoimmune diseases. Patients with lymphoma were analysed if the evolution of the autoimmune disease could be evaluated.

RESULTS

In all, 43 of 49 cases could be analysed, including 14 with rheumatoid arthritis (RA), 13 with systemic lupus erythematosus (SLE), six with primary Sjogren's syndrome (pSS), five with systemic vasculitis, and five with other autoimmune diseases. Rituximab was prescribed for lymphoma in two patients with RA and two with pSS. In the 39 other cases, rituximab was given because of the refractory character of the autoimmune disease. The mean follow up period was 8.3 months (range 2 to 26). There were 11 adverse events in 10 patients and treatment had to be discontinued in six. Efficacy was observed in 30 patients (70%): RA 11, SLE 9, pSS 5, vasculitis 2, antisynthetase syndromes 2, sarcoidosis 1. The mean decrease in corticosteroid intake was 9.5 mg/d (range 0 to 50) in responders. Seven patients experienced relapse after mean 8.1 months (5 to 15). Three patients died because of refractory autoimmune disease.

CONCLUSIONS

Despite absence of marketing authorisation, rituximab is used to treat various refractory autoimmune diseases in daily rheumatological practice. This study showed good tolerance and short term clinical efficacy, with marked corticosteroid reduction in patients with SLE, pSS, vasculitis, and polymyositis.

[Marfan syndrome]

Marfan's syndrome is a monogenetic disease with an autosomal dominant transmission generally accompanied by type I fibrillin abnormality. This widely-distributed molecule participates in the structure of connective tissues so that any aberration may result in disease of many systems: skeletal morphology, dislocation of the lens, neurological or cutaneous signs and dilatation of the aorta predisposing to dissection, mitral valve prolapse being a common association. The diagnosis, clinical because of the size of the culprit gene and the multiplicity of the possible mutations, is sometimes difficult, and diagnostic criteria have been proposed. It is important to make the diagnosis because treatment is based on the restriction of violent exercise, betablocker therapy and regular echocardiographic monitoring of the ascending aorta, the region at highest risk of dilatation and dissection. A family enquiry is essential to make the diagnosis before the onset of complications in pauci-symptomatic patients (great intra-familial variability). Pregnancy poses special problems in these patients.

Pericardial involvement in human immunodeficiency virus infection

STUDY OBJECTIVES

Previous studies have showed that the pericardium is frequently involved in HIV infection. However, the characteristics and etiology of the pericardial abnormalities that have been found remained poorly defined. We analyzed the features of pericardial involvement in these patients and investigated the clinical variables associated with moderate and severe effusions.

DESIGN

Prospective, clinical, and echocardiographic study.

SETTING

The service of infectious diseases of a university hospital.

PATIENTS

181 consecutive patients at all stages of HIV infection.

RESULTS

Only one patient (0.55%) had acute pericarditis. Seventy-five patients (41%) had an asymptomatic pericardial effusion; in 23 patients (13% of all patients), the effusion was either moderate or severe. Ten cases (5.5% of all patients) of moderate or severe effusions resulted in right atrium diastolic compression, and three of these cases (1.6% of all patients) required pericardiocentesis for the management of tamponade. Six patients (3%) presented with echogenic pericardial masses of undetermined etiology. A moderate or severe effusion was present in a greater number of patients with symptomatic HIV infection than was present in asymptomatic HIV-infected patients, respectively: 17 vs 2% (p = 0.015). The following are variables independently associated with moderate or severe pericardial effusions: heart failure (odds ratio, 20.3; p = 0.0001); Kaposi's sarcoma (odds ratio, 8.6; p = 0.01), tuberculosis (TB; odds ratio, 47.2; p = 0.0006); and other pulmonary infections (odds ratio,15.0; p = 0.02).

CONCLUSIONS

Most of these moderate or severe effusions are clinically unsuspected, but they can lead to life-threatening tamponade. This fact seems to justify echocardiographic surveillance in HIV-infected patients, especially in those with heart failure, Kaposi's sarcoma, TB, or other pulmonary infections.

Predictors of myocardial dysfunction in human immunodeficiency virus-infected patients

BACKGROUND

Some of the most frequent manifestations of heart involvement in human immunodeficiency virus (HIV) infection include right and left ventricular dysfunction. The pathogenesis remains obscure.

METHODS AND RESULTS

This prospective clinical and echocardiographic study involved 181 patients at all stages of HIV infection. We tested a set of clinical variables using a backward logistic regression model to assess their ability to independently predict the presence of ventricular dysfunction. The presence of pulmonary infections (all etiologies mixed) was the only variable independently associated with isolated right ventricular dysfunction (odds ratio = 4.08; P = .02). Signs suggestive of pulmonary arterial hypertension were present in 71% of the patients with right ventricular dilation. History of previous opportunistic infections (all etiologies mixed) (odds ratio = 10.9; P = .0026) and time since the diagnosis of acquired immunodeficiency syndrome more than 12 months (odds ratio = 6.6; P = .03) were the only two independent predictors of left ventricular dysfunction.

CONCLUSIONS

Isolated right ventricular dysfunction may be secondary to pulmonary hypertension caused by repetitive pulmonary infections and not to primary myocardial disease. The aggressive treatment of opportunistic infections may become an important element of heart failure prophylaxis in HIV infection because they may be associated with left ventricular dysfunction.

Left ventricular dysfunction in human immunodeficiency virus (HIV)-infected patients

We evaluated left ventricular function by echocardiography in a prospective study that included 98 consecutive human immunodeficiency virus (HIV)-infected patients and 40 HIV-seronegative normal controls. When compared with controls, HIV patients showed increased isovolumic relaxation time (101+/-18 ms versus 71+/-10 ms; p<0.0001) and left ventricular diastolic diameters (51+/-6 mm versus 47+/-3 mm; p<0.0005), and decreased fractional shortening (31+/-6% versus 37+/-2%; p<0.0001). Diastolic dysfunction was the most frequent finding (63% of the patients). We found depressed ejection fraction in 31 (32%) patients. Only 8 (8%) patients had symptomatic congestive heart failure. Left ventricular dysfunction was not attributable to intravenous drug abuse or to therapy. It was less severe in earlier stages of the infection (fractional shortening: acquired immunodeficiency syndrome=30%+/-6%, asymptomatic HIV-seropositives 34%+/-5%; p<0.005) and in HIV-2-infected patients. Patients with opportunistic infections (all aetiologies mixed) had more frequent congestive heart failure than those without infections (16% of the patients with versus 4% of the patients without infections; p<0.05). The fact that even asymptomatic HIV-seropositives had signs of left ventricular dysfunction (fractional shortening: asymptomatic HIV-seropositives=34%+/-5%; controls=37%+/-2%; p<0.05) favours the hypothesis of the HIV being one of the causes of these abnormalities.

Inhalatory pentamidine therapy and the duration of the QT interval in HIV-infected patients

We evaluated the effect of chronic Pneumocystis carinii pneumonia (PCP) prophylaxis, with a once a month dose of 300 mg of inhalatory pentamidine isethionate, on QT interval duration. We included 22 human immunodeficiency virus (HIV)-infected patients: 11 were on this medication and 11 were not. The two groups were matched for age, sex and HIV infection stage. No patient had any clinical condition or was under any medication known to affect the duration of the QT interval. The heart rate-corrected QT (QTc) was obtained by averaging the observations of three independent observers. QTc duration was similar in both groups. The time separating pentamidine administration and the performance of the ECG did not influence the results, neither did the duration of inhalatory pentamidine therapy. Our results suggest that inhalatory pentamidine does not prolong the QT interval duration and so, as opposed to what has been reported concerning intravenous pentamidine therapy, does not seem to induce an increased risk of torsades de pointes.

Zidovudine therapy and left ventricular function and mass in human immunodeficiency virus-infected patients

Human immunodeficiency virus-infected (HIV) patients frequently present left ventricular dysfunction. Its etiology is not elucidated but zidovudine has been postulated as a possible cause factor. This study is an attempt to clarify this issue by evaluating the effect of zidovudine therapy on left ventricular function in these patients. We prospectively studied by echocardiographic examination 11 consecutive HIV-infected patients who were assigned for zidovudine therapy. We excluded patients that had a history or a physical examination suggestive of ischemic, rheumatic, congenital, or hypertensive heart disease. Patients with diabetes mellitus, excessive ethanol intake and patients on potentially cardiodepressant drugs were also excluded. Echocardiographic examination was performed immediately before the initiation of zidovudine therapy and 1 and 3 months later. Left ventricular diameters, mass and fractional shortening showed no significant difference from baseline, at 1 or 3 months after the initiation of zidovudine therapy. Our results suggest that zidovudine therapy has no effect on left ventricular diameters, mass or fractional shortening during a short term.

Cardiac morbidity in the human immunodeficiency virus infection

PURPOSE

To evaluate the cardiac involvement in Human Immunodeficiency Virus (HIV) infection.

DESIGN

Prospective and normal individuals group controlled study.

SETTING

The departments of cardiology and infectious diseases of an university hospital.

PATIENTS

137 consecutive HIV infected patients at all stages of the infection and 40 normal noninfected controls.

MEASUREMENTS AND MAIN RESULTS

Clinical and echocardiographic evaluation was performed. Cardiac symptoms were observed in 10 (7.3%) patients, manifested as congestive heart failure. The global HIV infected population had increased left ventricular (LV) dimensions and wall thickness and decreased LV fractional shortening and ejection fraction when compared with the control population. Seven (5.1%) patients had dilated cardiomyopathy, 9 (6.5%) had global LV hypokinesis with or without LV dilatation and 17 (12.4%) had segmental LV wall motion abnormalities. Right ventricular dilatation was present in 23 (16.8%). Mitral or tricuspid regurgitation of a moderate or severe degree was found in 3 (2.2%) patients. No valvular vegetations were found. Fifty nine (43.1%) patients presented a pericardial effusion. An echocardiogram with at least one abnormality was observed in 104 (75.9%) and a severely abnormal echocardiogram in 34 (24.8%). The presence of cardiac symptoms and of abnormal and severely abnormal echocardiograms was more frequent in patients with the acquired immunodeficiency syndrome than in asymptomatic HIV infected patients. When comparing HIV-1 with HIV-2 populations the first showed increased LV systolic and diastolic diameters and LV mass index. There was no statistically significant difference between all risk behavior groups regarding the frequency of cardiac symptoms or the echocardiographic abnormalities found. HIV infected patients with CD4+ lymphocytes counts < or = 100/mm3 had more frequent abnormal and severely abnormal echocardiograms than those with CD4+ lymphocytes counts > 100/mm3.

CONCLUSIONS

Although cardiac symptoms were rare in our population, subclinical cardiac involvement detected by echocardiography was frequent and could involve any cardiac layer. It was not influenced by the patients' risk behavior. The left ventricular trophic response observed in HIV-2 infection seemed less intense than that in HIV-1 infection. Cardiac involvement was more frequent in the more advanced stages of the infection and in patients with lower CD4+ lymphocyte counts.

Isradipine in the treatment of mild-to-moderate hypertension in geriatric patients

A number of studies have shown the benefit of hypertensive treatment even though the most common forms of the disease are mild-to-moderate in severity. Considering the overall aging of the world's population, it is of particular interest to study hypertension and its treatment in geriatric patients. A short-term study of isradipine was conducted to assess its effectiveness and tolerability in patients with mild-to-moderate hypertension. The study was carried out by general practitioners and involved 3343 patients, aged > or = 18 years, with diastolic blood pressures (DBPs) ranging from 95 to 114 mm Hg. A 4-week wash-out and placebo run-in phase was followed by a 12-week active treatment period with isradipine at 1.25 or 2.5 mg/day, depending on the blood pressure response. Posttreatment results in a subgroup of 1092 patients (444 men and 648 women), aged > or = 60 years, showed decreases in systolic blood pressure (SBP) from 173.1 to 149.2 mm Hg (mean decrease, 20.9 mm Hg) and, in DBP, from 102.0 to 85.0 mm Hg (mean decrease, 16.9 mm Hg). The majority (84.6%) of these patients showed DBP reductions of > 10 mm Hg, and 82.3% achieved normalization (DBP < 90 mm Hg) at the end of treatment. The mean dosage was 1.74 +/- 0.69 mg twice daily, and 37% of patients doubled their initial 1.25 mg twice daily dosages. There were no significant changes in either heart rate or major metabolic parameters. Adverse events were reported by 3.1% of the patients, and 90% of both patients and physicians expressed satisfaction with the therapy. There were no differences between men and women with regard to adverse events or efficacy, nor were the results in patients > or = 60 years different from those in younger patients. Thus, isradipine was effective and well tolerated in these geriatric patients.