Randomized controlled trials of non-pharmacological interventions for healthy seniors: Effects on cognitive decline, brain plasticity and activities of daily living-A 23-year scoping review

Little is known about the simultaneous effects of non-pharmacological interventions (NPI) on healthy older adults' behavior and brain plasticity, as measured by psychometric instruments and magnetic resonance imaging (MRI). The purpose of this scoping review was to compile an extensive list of randomized controlled trials published from January 1, 2000, to August 31, 2023, of NPI for mitigating and countervailing age-related physical and cognitive decline and associated cerebral degeneration in healthy elderly populations with a mean age of 55 and over. After inventorying the NPI that met our criteria, we divided them into six classes: single-domain cognitive, multi-domain cognitive, physical aerobic, physical non-aerobic, combined cognitive and physical aerobic, and combined cognitive and physical non-aerobic. The ultimate purpose of these NPI was to enhance individual autonomy and well-being by bolstering functional capacity that might transfer to activities of daily living. The insights from this study can be a starting point for new research and inform social, public health, and economic policies. The PRISMA extension for scoping reviews (PRISMA-ScR) checklist served as the framework for this scoping review, which includes 70 studies. Results indicate that medium- and long-term interventions combining non-aerobic physical exercise and multi-domain cognitive interventions best stimulate neuroplasticity and protect against age-related decline and that outcomes may transfer to activities of daily living.

Cognitive enrichment through art: a randomized controlled trial on the effect of music or visual arts group practice on cognitive and brain development of young children

BACKGROUND

The optimal stimulation for brain development in the early academic years remains unclear. Current research suggests that musical training has a more profound impact on children's executive functions (EF) compared to other art forms. What is crucially lacking is a large-scale, long-term genuine randomized controlled trial (RCT) in cognitive neuroscience, comparing musical instrumental training (MIP) to another art form, and a control group (CG). This study aims to fill this gap by using machine learning to develop a multivariate model that tracks the interconnected brain and EF development during the academic years, with or without music or other art training.

METHODS

The study plans to enroll 150 children aged 6-8 years and randomly assign them to three groups: Orchestra in Class (OC), Visual Arts (VA), and a control group (CG). Anticipating a 30% attrition rate, each group aims to retain at least 35 participants. The research consists of three analytical stages: 1) baseline analysis correlating EF, brain data, age, gender, and socioeconomic status, 2) comparison between groups and over time of EF brain and behavioral development and their interactions, including hypothesis testing, and 3) exploratory analysis combining behavioral and brain data. The intervention includes intensive art classes once a week, and incremental home training over two years, with the CG receiving six annual cultural outings.

DISCUSSION

This study examines the potential benefits of intensive group arts education, especially contrasting music with visual arts, on EF development in children. It will investigate how artistic enrichment potentially influences the presumed typical transition from a more unified to a more multifaceted EF structure around age eight, comparing these findings against a minimally enriched active control group. This research could significantly influence the incorporation of intensive art interventions in standard curricula.

TRIAL REGISTRATION

The project was accepted after peer-review by the Swiss National Science Foundation (SNSF no. 100014_214977) on March 29, 2023. The study protocol received approval from the Cantonal Commission for Ethics in Human Research of Geneva (CCER, BASEC-ID 2023-01016), which is part of Swiss ethics, on October 25, 2023. The study is registered at clinicaltrials.gov (NCT05912270).

Increased functional connectivity in the right dorsal auditory stream after a full year of piano training in healthy older adults

Learning to play an instrument at an advanced age may help to counteract or slow down age-related cognitive decline. However, studies investigating the neural underpinnings of these effects are still scarce. One way to investigate the effects of brain plasticity is using resting-state functional connectivity (FC). The current study compared the effects of learning to play the piano (PP) against participating in music listening/musical culture (MC) lessons on FC in 109 healthy older adults. Participants underwent resting-state functional magnetic resonance imaging at three time points: at baseline, and after 6 and 12 months of interventions. Analyses revealed piano training-specific FC changes after 12 months of training. These include FC increase between right Heschl's gyrus (HG), and other right dorsal auditory stream regions. In addition, PP showed an increased anticorrelation between right HG and dorsal posterior cingulate cortex and FC increase between the right motor hand area and a bilateral network of predominantly motor-related brain regions, which positively correlated with fine motor dexterity improvements. We suggest to interpret those results as increased network efficiency for auditory-motor integration. The fact that functional neuroplasticity can be induced by piano training in healthy older adults opens new pathways to countervail age related decline.

Sleep Assessment in Critically Ill Patients With Acute Hypoxemic Respiratory Failure

BACKGROUND

Sleep deprivation alters respiratory muscle performance and may precipitate respiratory failure. This study aimed to assess sleep in subjects admitted to ICU for acute hypoxemic respiratory failure and its role in the risk of intubation.

METHODS

This was a prospective observational single-center cohort study including subjects admitted to ICU for de novo acute hypoxemic respiratory failure defined as breathing frequency ≥ 25 breaths/min or clinical signs of respiratory distress and PaO2 /FIO2 < 300 mm Hg while receiving high-flow nasal oxygen. Subjects with altered consciousness, central nervous or psychiatric disorders, continuous sedation or neuroleptic medication, or were uncooperative were excluded. Sleep was assessed by complete polysomnography (PSG) the night following ICU admission. The main outcome was to assess sleep among subjects with acute hypoxemic respiratory failure and to compare sleep between subjects who eventually required intubation to those who did not.

RESULTS

Over a 24-month inclusion period, 34 subjects had complete PSG, among whom 5 (15%) required intubation in the ICU. Total sleep time was 4.2 h in median (interquartile range 2.9-6.8); deep-sleep duration was 70 min (34-127), and rapid eye movement (REM) sleep duration was 9 min (0-28). Among them, 13 subjects (38%) had no REM sleep. Total sleep time and duration of deep and REM sleep stages did not differ between subjects who required intubation and those successfully treated with high-flow nasal oxygen.

CONCLUSIONS

Whereas total sleep time remained relatively preserved in critically ill subjects with acute hypoxemic respiratory failure, REM sleep time was uncommon or completely absent in a large number of subjects. Sleep did not differ between subjects who required intubation and those who did not. However, given a trend toward an increased risk of intubation in subjects with a complete absence of REM sleep, further studies are needed to better explore the impact of REM sleep on the risk of intubation.

Fine motor control improves in older adults after one year of piano lessons: Analysis of individual development and its coupling with cognition and brain structure

Musical training can improve fine motor skills, cognitive abilities and induce macrostructural brain changes. However, it is not clear whether the changes in motor skills occur simultaneously with changes in cognitive and neurophysiological parameters. In this study, 156 healthy, musically naïve, and right-handed older adults were recruited and randomly assigned to a piano training or a music listening group. Before, after six and twelve months participants were scanned using MRI and assessed for fine motor skills, auditory working memory and processing speed. A Bayesian multilevel modeling approach was used to examine behavioral and neurophysiological group differences. The relationships between motor and cognitive and between motor and neurophysiological parameters were determined using latent change score models. Compared to music listening, practicing piano resulted in greater improvement in fine motor skills and probably working memory. Only in the piano group, unimanual fine motor skills and gray matter volume of the contralateral M1 changed together during the 6-12-month period. Additionally, M1 co-developed with ipsilateral putamen and thalamus. Playing piano induced more prevalent coupling between the motor and cognitive domain. However, there is little evidence that fine motor control develops concurrently with cognitive functions. Playing an instrument promotes motor, cognitive and neural development into older age. During the learning process, the consolidation of piano skills appears to take place in sensorimotor networks, enabling musicians to perform untrained motor tasks with higher acuity. Relationships between the development of motor acuity and cognition were bidirectional and can be explained by a common cause as well as by shared resources with compensatory mechanisms.

Early non-invasive ventilation and high-flow nasal oxygen therapy for preventing endotracheal intubation in hypoxemic blunt chest trauma patients: the OptiTHO randomized trial

BACKGROUND

The benefit-risk ratio of prophylactic non-invasive ventilation (NIV) and high-flow nasal oxygen therapy (HFNC-O₂) during the early stage of blunt chest trauma remains controversial because of limited data. The main objective of this study was to compare the rate of endotracheal intubation between two NIV strategies in high-risk blunt chest trauma patients.

METHODS

The OptiTHO trial was a randomized, open-label, multicenter trial over a two-year period. Every adult patients admitted in intensive care unit within 48 h after a high-risk blunt chest trauma (Thoracic Trauma Severity Score ≥ 8), an estimated PaO₂/FiO₂ ratio < 300 and no evidence of acute respiratory failure were eligible for study enrollment (Clinical Trial Registration: NCT03943914). The primary objective was to compare the rate of endotracheal intubation for delayed respiratory failure between two NIV strategies: i) a prompt association of HFNC-O₂ and "early" NIV in every patient for at least 48 h with vs. ii) the standard of care associating COT and "late" NIV, indicated in patients with respiratory deterioration and/or PaO₂/FiO₂ ratio ≤ 200 mmHg. Secondary outcomes were the occurrence of chest trauma-related complications (pulmonary infection, delayed hemothorax or moderate-to-severe ARDS).

RESULTS

Study enrollment was stopped for futility after a 2-year study period and randomization of 141 patients. Overall, 11 patients (7.8%) required endotracheal intubation for delayed respiratory failure. The rate of endotracheal intubation was not significantly lower in patients treated with the experimental strategy (7% [5/71]) when compared to the control group (8.6% [6/70]), with an adjusted OR = 0.72 (95%IC: 0.20-2.43), p = 0.60. The occurrence of pulmonary infection, delayed hemothorax or delayed ARDS was not significantly lower in patients treated by the experimental strategy (adjusted OR = 1.99 [95%IC: 0.73-5.89], p = 0.18, 0.85 [95%IC: 0.33-2.20], p = 0.74 and 2.14 [95%IC: 0.36-20.77], p = 0.41, respectively).

CONCLUSION

A prompt association of HFNC-O₂ with preventive NIV did not reduce the rate of endotracheal intubation or secondary respiratory complications when compared to COT and late NIV in high-risk blunt chest trauma patients with non-severe hypoxemia and no sign of acute respiratory failure.

CLINICAL TRIAL REGISTRATION

NCT03943914, Registered 7 May 2019.

Abstract 5152: Photodynamic therapy promotes immune infiltration and control of malignant pleural mesothelioma through NF-kB mediated upregulation of E-Selectin in the tumor vasculature

Introduction: Malignant pleural mesothelioma (MPM) is an aggressive cancer with limited treatment options. The application of photodynamic therapy (PDT) was shown to significantly improve patient survival. Previously, we found that low dose PDT (L-PDT) enhanced the immune infiltration of MPM and increased the impact of immune checkpoint inhibitors on tumor control. However, the mechanisms behind these observations are unknown. Here, in an orthotopic murine model of MPM, we show that L-PDT upregulates tumor vascular E-Selectin expression via NF-kB. This upregulation favors enhanced leukocyte trafficking and immune mediated MPM regression.

Methods: We analyzed adhesion molecules (E-Selectin, ICAM-1, VCAM-1) and canonical NF-kB activation (phosphorylated IκBα) protein levels in endothelial (ECRF-24) cells treated by L-PDT in the presence or absence of a NEMO/IKKγ siRNA in vitro. For in vivo validation, AB12-Luc MPM cells were grown in the pleural cavity of syngeneic BALB/c mice and treated with L-PDT (verteporfin 400 µg/kg, fluence 10 J/cm2, fluence rate 50 mW/cm2) alone or in presence of NF-kB or E-Selectin inhibitors (NEMO Binding Domain (NBD) peptide and E-Selectin blocking antibody respectively). For each treatment group, we determined the expression of endothelial adhesion molecules (E-Selectin, ICAM-1, VCAM-1) and the tumor immune infiltrate by immunohistochemistry and flow cytometry. In parallel, the impact of L-PDT on MPM growth and mouse survival were assessed in the presence of E-Selectin inhibition.

Results: L-PDT increased the levels of endothelial adhesion molecules E-Selectin, ICAM-1 and VCAM-1 9 to 24 hours after L-PDT treatment in vitro. This was preceded by an increase of IκBα phosphorylation. In the presence of NEMO siRNAs, the expression of NEMO/IKKγ was reduced and led to E-Selectin repression. In orthotopic MPM bearing mice, the treatment of MPM by L-PDT enhanced adhesion molecules expression in tumor vasculature at 24 hours. This correlated with increased infiltration of CD4+ and CD8+ granzyme B+ T-cells and improved tumor control and mouse survival. NF-kB inhibition impaired tumor vascular adhesion molecules upregulation and the recruitment of tumor infiltrating lymphocytes in MPM. The targeted inhibition of E-Selectin abrogated the immune infiltration and tumor regression of MPM following L-PDT, which ultimately decreased animal survival in our MPM model.

Conclusion: Low dose PDT relieves MPM tumor vascular anergy via NF-kB mediated adhesion molecules expression. Endothelial E-Selectin has been identified, in our MPM model, as a major determinant for L-PDT enhanced lymphocyte trafficking, tumor control and animal survival.

Citation Format: Louis-Emmanuel Chriqui, Yameng Hao, Damien Marie, Michel Gonzalez, Thorsten Krueger, Etienne Meylan, Johanna Joyce, Sabrina Cavin, Jean-Yannis Perentes. Photodynamic therapy promotes immune infiltration and control of malignant pleural mesothelioma through NF-kB mediated upregulation of E-Selectin in the tumor vasculature. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5152.

Abstract 6399: Hyperthermic intrathoracic chemotherapy (HITOC) improves malignant pleural mesothelioma control through a tumor specific cytotoxic immune response

Introduction: The management of malignant pleural mesothelioma (MPM) remains challenging with poor patient survival. Local therapies such as hyperthermic intrathoracic cisplatin (HITOC) have shown good tumor control in selected patients. HITOC was shown to increase MPM drug exposure while limiting systemic side effects but alternative mechanisms for HITOC are still lacking. Here, we hypothesized that HITOC induces an immune response directed against MPM which decreases cancer related mortality.

Methods: We implanted AB12-luc MPM cells in the pleural cavity of BALB/c mice. A chemotherapy perfusion circuit was downsized to administer cisplatin (80mg/m2 equivalent dose) in the thoracic cavity at normo (37°C, ITOC) or hyperthermic (39°C, HITOC) conditions for 30 minutes. Tumor growth (visualized by bioluminescence) and mouse survival were then assessed. We determined tumor platinum content and distribution by inductively coupled plasma mass spectrometry (ICP-MS) and by laser ablation ICP-MS (LA-ICP-MS) respectively. We also questioned the impact of (H)ITOC on the MPM immune microenvironment (innate and adaptive immune cells, activity and checkpoint expression) by 16-colour flow cytometry and immunohistochemistry. Finally, tumor response to (H)ITOC was assessed in BALB/c athymic mice implanted with AB12-luc cells.

Results: MPM tumor control and mouse survival were significantly improved by HITOC compared to controls (ITOC, saline 37 and 39°C). Tumor platinum content was significantly higher in HITOC compared to ITOC but was majorly located at the surface of tumors. HITOC enhanced MPM infiltration by CD8+Granzyme B+ T-cells and decreased the levels of MCHII−/CD80− (M2-like) macrophages compared to controls at day 7. Interestingly, immune checkpoint expression of PD1 and CTLA4 was significantly enhanced in CD8+ lymphocytes in HITOC treated MPM compared to controls at day 7. Finally, the lack of T lymphocytes (BALB/c athymic mice) abrogated the impact of HITOC on MPM control and mouse survival.

Conclusion: HITOC improves MPM control through a T lymphocyte immune mediated response. The enhanced immune checkpoint (PD1/CTLA4) expression in CD8+ lymphocytes opens perspectives for the combination of HITOC with immune checkpoint inhibitors.

Citation Format: Yameng Hao, Aspasia Gkasti, Louis-Emmanuel Chriqui, Damien Marie, Michel Gonzalez, Thorsten Krueger, Solange Peters, Paul J. Dyson, Etienne Meylan, Johanna Joyce, Sabrina Cavin, Jean Y. Perentes. Hyperthermic intrathoracic chemotherapy (HITOC) improves malignant pleural mesothelioma control through a tumor specific cytotoxic immune response. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6399.

Impact of Radial Arterial Location on Catheter Lifetime in ICU Surgical Intensive Care

The use of arterial catheters is frequent in intensive care for hemodynamic monitoring of patients and for blood sampling, but they are often removed because of dysfunction. The primary objective is to compare the prevalence of radial arterial catheter dysfunction according to location in relation to the radiocarpal joint in intensive care patients.

DESIGN

Prospective randomized, controlled, single-center study.

SETTING

The surgical ICU of the university hospital of Poitiers in France.

PATIENTS

From January 2016 to April 2017, all patients over 18 years old admitted to the surgical ICU and requiring an arterial catheter were included.

INTERVENTIONS

Randomization into two groups: catheter placed near the wrist (within 4 cm of the radiocarpal joint) and catheter placed away the wrist. The primary endpoint was the prevalence of dysfunction. We also compared the prevalence of infection and colonization.

MEASUREMENTS AND MAIN RESULTS

One hundred seven catheters were analyzed (14 failed placements with no difference between the two groups, and 16 catheters excluded for missing data), with 58 catheters in near the wrist group and 49 in away the wrist group. We did not find any significant difference in the number of catheter dysfunctions between the two groups (p = 0.56). The prevalence density of catheter dysfunction was 30.5 of 1,000 catheter days for near the wrist group versus 26.7 of 1,000 catheter days for away the wrist group. However, we observed a significant difference in terms of catheter-related infection in favor of away the wrist group (p = 0.04). In addition, distal positioning of the catheter was judged easier by the physicians.

CONCLUSIONS

The distal or proximal position of the arterial catheter in the radial position has no influence on the occurrence of dysfunction. However, there may be an association with the prevalence of infections.

Musical and psychomotor interventions for cognitive, sensorimotor, and cerebral decline in patients with Mild Cognitive Impairment (COPE): a study protocol for a multicentric randomized controlled study

BACKGROUND

Regular cognitive training can boost or maintain cognitive and brain functions known to decline with age. Most studies administered such cognitive training on a computer and in a lab setting. However, everyday life activities, like musical practice or physical exercise that are complex and variable, might be more successful at inducing transfer effects to different cognitive domains and maintaining motivation. "Body-mind exercises", like Tai Chi or psychomotor exercise, may also positively affect cognitive functioning in the elderly. We will compare the influence of active music practice and psychomotor training over 6 months in Mild Cognitive Impairment patients from university hospital memory clinics on cognitive and sensorimotor performance and brain plasticity. The acronym of the study is COPE (Countervail cOgnitive imPairmEnt), illustrating the aim of the study: learning to better "cope" with cognitive decline.

METHODS

We aim to conduct a randomized controlled multicenter intervention study on 32 Mild Cognitive Impairment (MCI) patients (60-80 years), divided over 2 experimental groups: 1) Music practice; 2) Psychomotor treatment. Controls will consist of a passive test-retest group of 16 age, gender and education level matched healthy volunteers. The training regimens take place twice a week for 45 min over 6 months in small groups, provided by professionals, and patients should exercise daily at home. Data collection takes place at baseline (before the interventions), 3, and 6 months after training onset, on cognitive and sensorimotor capacities, subjective well-being, daily living activities, and via functional and structural neuroimaging. Considering the current constraints of the COVID-19 pandemic, recruitment and data collection takes place in 3 waves.

DISCUSSION

We will investigate whether musical practice contrasted to psychomotor exercise in small groups can improve cognitive, sensorimotor and brain functioning in MCI patients, and therefore provoke specific benefits for their daily life functioning and well-being.

TRIAL REGISTRATION

The full protocol was approved by the Commission cantonale d'éthique de la recherche sur l'être humain de Genève (CCER, no. 2020-00510) on 04.05.2020, and an amendment by the CCER and the Commission cantonale d'éthique de la recherche sur l'être humain de Vaud (CER-VD) on 03.08.2021. The protocol was registered at clinicaltrials.gov (20.09.2020, no. NCT04546451).

Assessing the contribution of diazotrophs to microbial Fe uptake using a group specific approach in the Western Tropical South Pacific Ocean

Diazotrophs are often limited by iron (Fe) availability in the oligotrophic ocean. The Western Tropical South Pacific (WTSP) ocean has been suggested as an intense N2 fixation area due to Fe fertilizations through shallow hydrothermal activity. Yet, the Fe demand of diazotrophs in their natural habitat, where they cohabit with other microbial organisms also requiring Fe, remains unknown. Here we develop and apply a method consisting of coupling 55Fe uptake experiments with cell-sorting by flow cytometry, and provide group-specific rates of in situ Fe uptake by the microbial community in the WTSP, in addition to bulk and size fractionation rates. We reveal that the diazotrophs Crocosphaera watsonii and Trichodesmium contribute substantially to the bulk in situ Fe uptake (~33% on average over the studied area), despite being numerically less abundant compared to the rest of the planktonic community. Trichodesmium had the highest cell-specific Fe uptake rates, followed by C. watsonii, picoeukaryotes, Prochlorococcus, Synechococcus and finally heterotrophic bacteria. Calculated Fe:C quotas were higher (by 2 to 52-fold) for both studied diazotrophs compared to those of the non-diazotrophic plankton, reflecting their high intrinsic Fe demand. This translates into a diazotroph biogeographical distribution that appears to be influenced by ambient dissolved Fe concentrations in the WTSP. Despite having low cell-specific uptake rates, Prochlorococcus and heterotrophic bacteria were largely the main contributors to the bulk Fe uptake (~23% and ~12%, respectively). Overall, this group-specific approach increases our ability to examine the ecophysiological role of functional groups, including those of less abundant and/or less active microbes.

Evidence of cortical thickness increases in bilateral auditory brain structures following piano learning in older adults

Morphological differences in the auditory brain of musicians compared to nonmusicians are often associated with life-long musical activity. Cross-sectional studies, however, do not allow for any causal inferences, and most experimental studies testing music-driven adaptations investigated children. Although the importance of the age at which musical training begins is widely recognized to impact neuroplasticity, there have been few longitudinal studies examining music-related changes in the brains of older adults. Using magnetic resonance imaging, we measured cortical thickness (CT) of 12 auditory-related regions of interest before and after 6 months of musical instruction in 134 healthy, right-handed, normal-hearing, musically-naive older adults (64-76 years old). Prior to the study, all participants were randomly assigned to either piano training or to a musical culture/music listening group. In five regions-left Heschl's gyrus, left planum polare, bilateral superior temporal sulcus, and right Heschl's sulcus-we found an increase in CT in the piano training group compared with the musical culture group. Furthermore, CT of the right Heschl's gyrus could be identified as a morphological substrate supporting speech in noise perception. The results support the conclusion that playing an instrument is an effective stimulator for cortical plasticity, even in older adults.

Six Months of Piano Training in Healthy Elderly Stabilizes White Matter Microstructure in the Fornix, Compared to an Active Control Group

While aging is characterized by neurodegeneration, musical training is associated with experience-driven brain plasticity and protection against age-related cognitive decline. However, evidence for the positive effects of musical training mostly comes from cross-sectional studies while randomized controlled trials with larger sample sizes are rare. The current study compares the influence of six months of piano training with music listening/musical culture lessons in 121 musically naïve healthy elderly individuals with regard to white matter properties using fixel-based analysis. Analyses revealed a significant fiber density decline in the music listening/musical culture group (but not in the piano group), after six months, in the fornix, which is a white matter tract that naturally declines with age. In addition, these changes in fiber density positively correlated to episodic memory task performances and the amount of weekly piano training. These findings not only provide further evidence for the involvement of the fornix in episodic memory encoding but also more importantly show that learning to play the piano at an advanced age may stabilize white matter microstructure of the fornix.

Broca area homologue's asymmetry reflects gestural communication lateralisation in monkeys (Papio anubis)

Manual gestures and speech recruit a common neural network, involving Broca’s area in the left hemisphere. Such speech-gesture integration gave rise to theories on the critical role of manual gesturing in the origin of language. Within this evolutionary framework, research on gestural communication in our closer primate relatives has received renewed attention for investigating its potential language-like features. Here, using in vivo anatomical MRI in 50 baboons, we found that communicative gesturing is related to Broca homologue’s marker in monkeys, namely the ventral portion of the Inferior Arcuate sulcus (IA sulcus). In fact, both direction and degree of gestural communication’s handedness – but not handedness for object manipulation are associated and correlated with contralateral depth asymmetry at this exact IA sulcus portion. In other words, baboons that prefer to communicate with their right hand have a deeper left-than-right IA sulcus, than those preferring to communicate with their left hand and vice versa. Interestingly, in contrast to handedness for object manipulation, gestural communication’s lateralisation is not associated to the Central sulcus depth asymmetry, suggesting a double dissociation of handedness’ types between manipulative action and gestural communication. It is thus not excluded that this specific gestural lateralisation signature within the baboons’ frontal cortex might reflect a phylogenetical continuity with language-related Broca lateralisation in humans.

Improved Speech in Noise Perception in the Elderly After 6 Months of Musical Instruction

Understanding speech in background noise poses a challenge in daily communication, which is a particular problem among the elderly. Although musical expertise has often been suggested to be a contributor to speech intelligibility, the associations are mostly correlative. In the present multisite study conducted in Germany and Switzerland, 156 healthy, normal-hearing elderly were randomly assigned to either piano playing or music listening/musical culture groups. The speech reception threshold was assessed using the International Matrix Test before and after a 6 month intervention. Bayesian multilevel modeling revealed an improvement of both groups over time under binaural conditions. Additionally, the speech reception threshold of the piano group decreased during stimuli presentation to the left ear. A right ear improvement only occurred in the German piano group. Furthermore, improvements were predominantly found in women. These findings are discussed in the light of current neuroscientific theories on hemispheric lateralization and biological sex differences. The study indicates a positive transfer from musical training to speech processing, probably supported by the enhancement of auditory processing and improvement of general cognitive functions.

Train the brain with music (TBM): brain plasticity and cognitive benefits induced by musical training in elderly people in Germany and Switzerland, a study protocol for an RCT comparing musical instrumental practice to sensitization to music

BACKGROUND

Recent data suggest that musical practice prevents age-related cognitive decline. But experimental evidence remains sparse and no concise information on the neurophysiological bases exists, although cognitive decline represents a major impediment to healthy aging. A challenge in the field of aging is developing training regimens that stimulate neuroplasticity and delay or reverse symptoms of cognitive and cerebral decline. To be successful, these regimens should be easily integrated in daily life and intrinsically motivating. This study combines for the first-time protocolled music practice in elderly with cutting-edge neuroimaging and behavioral approaches, comparing two types of musical education.

METHODS

We conduct a two-site Hannover-Geneva randomized intervention study in altogether 155 retired healthy elderly (64-78) years, (63 in Geneva, 92 in Hannover), offering either piano instruction (experimental group) or musical listening awareness (control group). Over 12 months all participants receive weekly training for 1 hour, and exercise at home for ~ 30 min daily. Both groups study different music styles. Participants are tested at 4 time points (0, 6, and 12 months & post-training (18 months)) on cognitive and perceptual-motor aptitudes as well as via wide-ranging functional and structural neuroimaging and blood sampling.

DISCUSSION

We aim to demonstrate positive transfer effects for faculties traditionally described to decline with age, particularly in the piano group: executive functions, working memory, processing speed, abstract thinking and fine motor skills. Benefits in both groups may show for verbal memory, hearing in noise and subjective well-being. In association with these behavioral benefits we anticipate functional and structural brain plasticity in temporal (medial and lateral), prefrontal and parietal areas and the basal ganglia. We intend exhibiting for the first time that musical activities can provoke important societal impacts by diminishing cognitive and perceptual-motor decline supported by functional and structural brain plasticity.

TRIAL REGISTRATION

The Ethikkomission of the Leibniz Universität Hannover approved the protocol on 14.08.17 (no. 3604-2017), the neuroimaging part and blood sampling was approved by the Hannover Medical School on 07.03.18. The full protocol was approved by the Commission cantonale d'éthique de la recherche de Genève (no. 2016-02224) on 27.02.18 and registered at clinicaltrials.gov on 17.09.18 ( NCT03674931 , no. 81185).

Supports non invasifs d’oxygénation et de ventilation chez les patients de réanimation considérés comme « palliatifs »

L’admission en réanimation de patients en détresse respiratoire aiguë considérés comme « palliatifs » conduit à l’utilisation privilégiée de ventilation non invasive. Plus récemment l’oxygénothérapie nasale à haut débit humidifi é est venuecompléter les possibilités de prise en charge. Le pronostic de ces patients est à l’évidence réservé, notamment si lapathologie sous-jacente est un cancer ou une hémopathie évolutive. Cependant un certain nombre de ces patientspeut avoir une évolution favorable et retrouver une qualité de vie satisfaisante. Cet article passe en revue les pratiquesutilisées pour ces patients.

Impact of sleep alterations on weaning duration in mechanically ventilated patients: a prospective study

Sleep is markedly altered in intensive care unit (ICU) patients and may alter respiratory performance. Our objective was to assess the impact of sleep alterations on weaning duration.

We conducted a prospective physiological study at a French teaching hospital. ICU patients intubated for at least 24 h and difficult to wean were included. Complete polysomnography (PSG) was performed after the first spontaneous breathing trial failure. Presence of atypical sleep, duration of sleep stages, particularly rapid eye movement (REM) sleep, and electroencephalogram (EEG) reactivity at eyes opening were assessed by a neurologist.

20 out of 45 patients studied (44%) had atypical sleep that could not be classified according to the standard criteria. Duration of weaning between PSG and extubation was significantly longer in patients with atypical sleep (median (interquartile range) 5 (2–8) versus 2 (1–2) days; p=0.001) and in those with no REM sleep compared with the others. Using multivariate logistic regression analysis, atypical sleep remained independently associated with prolonged weaning (>48 h after PSG). Altered EEG reactivity at eyes opening was a good predictor of atypical sleep.

Our results suggest for the first time that brain dysfunction may have an influence on the ability to breathe spontaneously.

Surface-Based Morphometry of Cortical Thickness and Surface Area Associated with Heschl's Gyri Duplications in 430 Healthy Volunteers

We applied Surface-Based Morphometry to assess the variations in cortical thickness (CT) and cortical surface area (CSA) in relation to the occurrence of Heschl's gyrus (HG) duplications in each hemisphere. 430 healthy brains that had previously been classified as having a single HG, Common Stem Duplication (CSD) or Complete Posterior Duplication (CPD) in each hemisphere were analyzed. To optimally align the HG area across the different groups of gyrification, we computed a specific surface-based template composed of 40 individuals with a symmetrical HG gyrification pattern (20 single HG, 10 CPD, 10 CSD). After normalizing the 430 participants' T1 images to this specific template, we separately compared the groups constituted of participants with a single HG, CPD, and CSD in each hemisphere. The occurrence of a duplication in either hemisphere was associated with an increase in CT posterior to the primary auditory cortex. This may be the neural support of expertise or great abilities in either speech or music processing domains that were related with duplications by previous studies. A decrease in CSA in the planum temporale was detected in cases with duplication in the left hemisphere. In the right hemisphere, a medial decrease in CSA and a lateral increase in CSA were present in HG when a CPD occurred together with an increase in CSA in the depth of the superior temporal sulcus (STS) in CSD compared to a single HG. These variations associated with duplication might be related to the functions that they process jointly within each hemisphere: temporal and speech processing in the left and spectral and music processing in the right.

Descriptive anatomy of Heschl's gyri in 430 healthy volunteers, including 198 left-handers

This study describes the gyrification patterns and surface areas of Heschl's gyrus (HG) in 430 healthy volunteers mapped with magnetic resonance imaging. Among the 232 right-handers, we found a large occurrence of duplication (64 %), especially on the right (49 vs. 37 % on the left). Partial duplication was twice more frequent on the left than complete duplication. On the opposite, in the right hemisphere, complete duplication was 10 % more frequent than partial duplication. The most frequent inter-hemispheric gyrification patterns were bilateral single HG (36 %) and left single-right duplication (27 %). The least common patterns were left duplication-right single (22 %) and bilateral duplication (15 %). Duplication was associated with decreased anterior HG surface area on the corresponding side, independently of the type of duplication, and increased total HG surface area (including the second gyrus). Inter-hemispheric gyrification patterns strongly influenced both anterior and total HG surface area asymmetries, leftward asymmetry of the anterior HG surface was observed in all patterns except double left HG, and total HG surface asymmetry favored the side of duplication. Compared to right-handers, the 198 left-handers exhibited lower occurrence of duplication, and larger right anterior HG surface and total HG surface areas. Left-handers' HG surface asymmetries were thus significantly different from those of right-handers, with a loss of leftward asymmetry of their anterior HG surface, and with significant rightward asymmetry of their total HG surface. In summary, gyrification patterns have a strong impact on HG surface and asymmetry. The observed reduced lateralization of HG duplications and anterior HG asymmetry in left-handers highlights HG inter-hemispheric gyrification patterns as a potential candidate marker of speech lateralization.

Genome size and base composition in Medicago sativa and M. truncatula species

The genome size (1C value) and base composition of 14 ecotypes of two species of tetraploid and diploid Medicago have been assessed by flow cytometry. These parameters vary both between and within species. The diploid annual Medicago truncatula Gaertn. had the smallest genome of the group studied (which also covered M. sativa L. subsp. sativa, M. sativa L. subsp. caerulea (Less. ex Ledeb.) Schmalh., M. sativa L. subsp. quasifalcata Sinsk., M. sativa L. subsp. x varia (Martyn) Arcangeli; however, its ecotypes revealed substantial intraspecific variation. The smallest M. truncatula genome observed was ecotype 108-1 with 1C = 0.49 pg and 38.1% GC and the largest was Jemalong with 1C = 0.57 pg and 38.6% GC. The degree of polysomaty in these Medicago was low, although in some tissues the frequency of cells with 4C nuclei reached 50%.

Enumeration and Cell Cycle Analysis of Natural Populations of Marine Picoplankton by Flow Cytometry Using the Nucleic Acid Stain SYBR Green I

The novel dye SYBR Green I binds specifically to nucleic acids and can be excited by blue light (488-nm wavelength). Cell concentrations of prokaryotes measured in marine samples with this dye on a low-cost compact flow cytometer are comparable to those obtained with the UV-excited stain Hoechst 33342 (bis-benzimide) on an expensive flow cytometer with a water-cooled laser. In contrast to TOTO-1 and TO-PRO-1, SYBR Green I has the advantage of clearly discriminating both heterotrophic bacteria and autotrophic Prochlorococcus cells, even in oligotrophic waters. As with TOTO-1 and TO-PRO-1, two groups of heterotrophic bacteria (B-I and B-II-like types) can be distinguished. Moreover, the resolution of DNA distribution obtained with SYBR Green I is similar to that obtained with Hoechst 33342 and permits the analysis of the cell cycle of photosynthetic prokaryotes over the whole water column.

Effect of Phosphorus on the Synechococcus Cell Cycle in Surface Mediterranean Waters during Summer

The effect of phosphorus (P) and nitrogen (N) additions on the Synechococcus cell cycle was tested with natural populations from the Mediterranean Sea in summer. In the absence of stimulation, the Synechococcus cell cycle was synchronized to the light-dark cycle. DNA synthesis began around 1600, a maximum of S-phase cells was observed at around dusk (2100), and a maximum of G(inf2)-phase cells was observed at around 2400. Addition of P (as PO(inf4)(sup3-)) caused, in all cases, a decrease in the fraction of cells in G(inf2) at around 1800, no change at around 2400, and an increase at around 1200 the next day, while addition of N (as NO(inf3)(sup-)) had no effect. We hypothesize that P addition induced a shortening of the G(inf1) phase, resulting in cells entering and leaving the S and G(inf2) phases earlier. These data suggest very strongly that the Synechococcus cells were P limited rather than N limited during this period of the year. In most cases, additions as low as 20 nM P induced a cell cycle response. From dose-response curves, we established that the P concentration inducing a 50% change in the percentage of cells in G(inf2) was low, close to 10 nM, at the beginning of the sampling period (30 June) and increased to about 50 nM by the end (9 July), suggesting a decrease in the severity of P limitation. This study extends recent observations that oligotrophic systems may be P rather than N limited at certain times of the year.

Enumeration of phytoplankton, bacteria, and viruses in marine samples

For many years, a small but dedicated group of scientists have been using flow cytometry for the evaluation of marine microorganisms. One of these scientists now provides us with a detailed series of protocols in this area, spelling out the variations in method and instrument operation that are crucial to the successful extraction of quality flow data from marine organisms. In addition, the use of a number of less frequently employed fluorescent probes gives some insight into alternative staining procedures. As our collection of microbiologically oriented techniques increases, this knowledge database becomes invaluable.

DNA/RNA analysis of phytoplankton by flow cytometry

The past 10 years or so have seen the combination of molecular and biochemical techniques within the confines of cytometry. The use of flow cytometry in microbiology is finally coming of age. This unit carefully defines the criteria for evaluation of DNA and RNA in phytoplankton. Of course not everyone works with phytoplankton, but the methods outlined are very appropriately representative for other organisms. In addition, the unit discusses the methods for evaluating cell cycle and discriminating specific taxa using fluorescent oligonucleotide probes targeted to 18S rRNA.

Anti-mitotic properties of indirubin-3'-monoxime, a CDK/GSK-3 inhibitor: induction of endoreplication following prophase arrest

The bis-indole indirubin is the active ingredient of the Traditional Chinese Medicine recipe Danggui Longhui Wan used against chronic myelocytic leukemia. We have previously shown that indirubins are potent inhibitors of cyclin-dependent kinases and glycogen synthase kinase-3. We here investigated the anti-mitotic properties of this class of compounds using the cell permeable indirubin-3'-monoxime and the HBL-100 cell line. Indirubin-3'-monoxime reversibly arrests asynchronous HBL-100 cells in G2. This arrest is not accompanied by any significant change in expression of the major cell cycle regulators. However indirubin-3'-monoxime inhibits the phosphorylation of consensus CDK phosphorylation sites as well as of nucleolin at a specific CDK1/cyclin B phosphorylation site, suggesting a direct action on the mitotic CDK1/cyclin B. When indirubin-3'-monoxime is added to HBL-100 cells synchronized in M phase by nocodazole, cells undergo an endoreplication leading to an 8n DNA content. As soon as indirubin-3'-monoxime is washed away, these polyploid cells become aneuploid and later die from necrosis. This mechanism of endoreplication followed by cell death may contribute to the anti-tumour properties of indirubins.

Cell cycle regulation by light in Prochlorococcus strains

The effect of light on the synchronization of cell cycling was investigated in several strains of the oceanic photosynthetic prokaryote Prochlorococcus using flow cytometry. When exposed to a light-dark (L-D) cycle with an irradiance of 25 micromol of quanta x m(-2) x s(-1), the low-light-adapted strain SS 120 appeared to be better synchronized than the high-light-adapted strain PCC 9511. Submitting L-D-entrained populations to shifts (advances or delays) in the timing of the "light on" signal translated to corresponding shifts in the initiation of the S phase, suggesting that this signal is a key parameter for the synchronization of population cell cycles. Cultures that were shifted from an L-D cycle to continuous irradiance showed persistent diel oscillations of flow-cytometric signals (light scatter and chlorophyll fluorescence) but with significantly reduced amplitudes and a phase shift. Complete darkness arrested most of the cells in the G1 phase of the cell cycle, indicating that light is required to trigger the initiation of DNA replication and cell division. However, some cells also arrested in the S phase, suggesting that cell cycle controls in Prochlorococcus spp. are not as strict as in marine Synechococcus spp. Shifting Prochlorococcus cells from low to high irradiance translated quasi-instantaneously into an increase of cells in both the S and G2 phases of the cell cycle and then into faster growth, whereas the inverse shift induced rapid slowing of the population growth rate. These data suggest a close coupling between irradiance levels and cell cycling in Prochlorococcus spp.

Diel expression of cell cycle-related genes in synchronized cultures of Prochlorococcus sp. strain PCC 9511

The cell cycle of the chlorophyll b-possessing marine cyanobacterium Prochlorococcus is highly synchronized under natural conditions. To understand the underlying molecular mechanisms we cloned and sequenced dnaA and ftsZ, two key cell cycle-associated genes, and studied their expression. An axenic culture of Prochlorococcus sp. strain PCC 9511 was grown in a turbidostat with a 12 h-12 h light-dark cycle for 2 weeks. During the light periods, a dynamic light regimen was used in order to simulate the natural conditions found in the upper layers of the world's oceans. This treatment resulted in strong cell cycle synchronization that was monitored by flow cytometry. The steady-state mRNA levels of dnaA and ftsZ were monitored at 4-h intervals during four consecutive division cycles. Both genes exhibited clear diel expression patterns with mRNA maxima during the replication (S) phase. Western blot experiments indicated that the peak of FtsZ concentration occurred at night, i.e., at the time of cell division. Thus, the transcript accumulation of genes involved in replication and division is coordinated in Prochlorococcus sp. strain PCC 9511 and might be crucial for determining the timing of DNA replication and cell division.

Flow cytometric detection of viruses

Representatives from several different virus families (Baculoviridae, Herpesviridae, Myoviridae, Phycodnaviridae, Picornaviridae, Podoviridae, Retroviridae, and Siphoviridae) were stained using a variety of highly fluorescent nucleic acid specific dyes (SYBR Green I, SYBR Green II, OliGreen, PicoGreen) and examined using a standard flow cytometer equipped with a standard 15 mW argon-ion laser. The highest green fluorescence intensities were obtained using SYBR Green I. DNA viruses with genome sizes between 48.5 and 300 kb could easily be detected. The fluorescence signals of the small genome-sized RNA viruses (7.4-14.5 kb) were found at the limit of detection. No significant linear relationship could be found between genome size and the green fluorescence intensity of the SYBR Green I stained virus preparations. To our knowledge, this is the first report of detecting and discriminating between a wide range of different viruses directly using flow cytometry. This rapid and precise assay represents a new and promising tool in the field of virology.

Indirubin, the active constituent of a Chinese antileukaemia medicine, inhibits cyclin-dependent kinases

Indirubin is the active ingredient of Danggui Longhui Wan, a mixture of plants that is used in traditional Chinese medicine to treat chronic diseases. Here we identify indirubin and its analogues as potent inhibitors of cyclin-dependent kinases (CDKs). The crystal structure of CDK2 in complex with indirubin derivatives shows that indirubin interacts with the kinase's ATP-binding site through van der Waals interactions and three hydrogen bonds. Indirubin-3'-monoxime inhibits the proliferation of a large range of cells, mainly through arresting the cells in the G2/M phase of the cell cycle. These results have implications for therapeutic optimization of indigoids.

Thermococcus barophilus sp. nov., a new barophilic and hyperthermophilic archaeon isolated under high hydrostatic pressure from a deep-sea hydrothermal vent

A novel barophilic, hyperthermophilic, anaerobic sulfur-metabolizing archaeon, strain MPT (T = type strain), was isolated from a hydrothermal vent site (Snakepit) on the Mid-Atlantic Ridge (depth, 3550 m). Enrichments and isolation were done under 40 MPa hydrostatic pressure at 95 degrees C. Strain MPT was barophilic at 75, 80, 85, 90, 95 and 98 degrees C, and was an obligate barophile between 95 and 100 degrees C (Tmax). For growth above 95 degrees C, a pressure of 15.0-17.5 MPa was required. The strain grew at 48-95 degrees C under atmospheric pressure. The optimal temperature for growth was 85 degrees C at both high (40 MPa) and low (0.3 MPa) pressures. The growth rate was twofold higher at 85 degrees C under in situ hydrostatic pressure compared to at low pressure. Strain MPT cells were motile, coccoid, 0.8-2.0 microns in diameter and covered by a hexagonal S-layer lattice. The optimum pH and NaCl concentration for growth at low pressure were 7.0 and 20-30 g l-1, respectively. The new isolate was an obligate heterotroph and utilized yeast extract, beef extract and peptone for growth. Growth was optimal in the presence of elemental sulfur. Rifampicin and chloramphenicol inhibited growth. The core lipids consisted of a major archaeol and a complex lipid pattern consisting of a major phospholipid. The DNA G + C content was 37.1 mol%. Sequencing of the 16S rRNA gene revealed that strain MPT belonged to the genus Thermococcus and it is proposed that this isolate should be designated as a new species, Thermococcus barophilus.

Application of the novel nucleic acid dyes YOYO-1, YO-PRO-1, and PicoGreen for flow cytometric analysis of marine prokaryotes

Novel blue light-excited fluorescent dyes for nucleic acids (YOYO-1, YO-PRO-1, and PicoGreen) were tested on cultures of Escherichia coli and of a variety of marine prokaryotes. Results of flow cytometric DNA analyses were compared with those obtained with the UV-excited dyes bis-benzimide Hoechst 33342 or 4', 6-diamidino-2-phenylindole (DAPI). YOYO-1, YO-PRO-1, and PicoGreen can be used only on aldehyde-fixed cells and need to be supplemented with cofactors such as potassium, citrate, or EDTA. They are highly sensitive to ionic strength. Consequently, seawater culture samples cannot be stained directly with these dyes and require at least a 10-fold dilution with distilled water to obtain reliable fluorescence signals. After treatment with RNase, coefficients of variation for the G1 peak of the DNA distributions of the different strains tested with YOYO-1 or PicoGreen indicated in general an improvement over Hoechst 33342 staining. These novel dyes can be used to enumerate prokaryotic cells by flow cytometry, as demonstrated with E. coli. However, their sensitivity to ionic strength makes them unsuitable for cell cycle analysis in natural samples.

Discrimination of respiratory dysfunction in yeast mutants by confocal microscopy, image, and flow cytometry

Living yeast cells can be selectively stained with the lipophilic cationic cyanine dye DiOC6(3) in a mitochondrial membrane potential-dependent manner. Our study extends the use of flow cytometric analysis and sorting to DiOC6(3)-stained yeast cells. Experimental conditions were developed that prevented the toxic side effect of the probe and gave a quantitative correlation between fluorescence and mitochondrial membrane potential, without any staining of other membranes. The localization of the fluorochrome was checked by confocal microscopy and image cytometry. The mitochondrial membrane alterations were also tested through cardiolipin staining with nonyl acridine orange. Differences in light scattering and in fluorescence were detected in mutants (rho-, rho degrees, mit-, or pet-) and wild-type (rho+mit+) populations of yeast. The dye uptake of respiratory-deficient yeast strains was significantly reduced as compared to that of the wild-type. Application of an uncoupler (mCICCP), which collapsed the mitochondrial membrane potential (alphapsi(m)), led to a drastic reduction of the dye uptake. It was observed that a decrease in deltapsi(m), was usually correlated with a decrease in cardiolipin stainability by nonyl acridine orange (NAO). Quantitative flow cytometry is a fast and reproducible technique for rapid screening of yeast strains that might be suspected of respiratory dysfunction and/or mitochondrial structural changes. We give evidence that it is an adequate method to characterize and isolate respiratory mutants through sorting procedure, with selective enrichment of the population studied in respiring or non-respiring yeast cells. Confocal microscopy and image cytometry corroborate the flow cytometry results.

Flow sorting of the Y sex chromosome in the dioecious plant Melandrium album

The preparation of stable chromosome suspensions and flow cytometric sorting of both the Y sex chromosome of the white campion, Melandrium album, and the deleted Y chromosome of an asexual mutant, 5K63, is described. The principle has been to maintain transformed roots in vitro, synchronise and block mitosis, reduce cells to protoplasts, and lyse these to release chromosomes. Such in vitro material, unlike many cell suspensions, showed a stable karyotype. Factors critical to producing high-quality chromosome suspensions from protoplasts include osmolality of isolation solutions and choice of spindle toxin and of lysis buffer. Agrobacterium rhizogenes transformed young growing root cultures were synchronised at G1/S with 50 microM aphidicolin for 24 h and released to a mitotic block with 30 microM oryzalin for 11 h. Protoplast preparations from such tissue routinely had metaphase indices reaching 15%. Suspensions of intact metaphase chromosomes, with few chromatids, were obtained by lysing swollen mitotic protoplasts in a citric acid/disodium phosphate buffer. Except for the presence of clumps of autosomal chromosomes near the X and Y chromosome zones, monoparametric histograms of fluorescence intensities of suspensions stained with 4',6-diamino-2-phenylindole showed profiles similar to theoretical flow karyotypes. Two types of Y chromosomes, one full-length and one partially deleted (from the asexual mutant), could be sorted at 90% purity (21-fold enrichment of Y). These results are discussed in the context of sex determination and differentiation in higher plants.

Fluorescent in situ hybridization with rRNA-targeted oligonucleotide probes to identify small phytoplankton by flow cytometry

Because of their tiny size (0.2 to 2 microns), oceanic picophytoplanktonic cells (either cultured strains or natural communities) are difficult to identify, and some basic questions concerning their taxonomy, physiology, and ecology are still largely unanswered. The present study was designed to test the suitability of in situ hybridization with rRNA fluorescent probes detected by flow cytometry for the identification of small photosynthetic eukaryotes. Oligonucleotide probes targeted against regions of the 18S rRNAs of Chlorophyta lineage (CHLO probe) and of non-Chlorophyta (NCHLO probe) algal species were designed. The CHLO and NCHLO probes, which differed by a single nucleotide, allowed discrimination of chlorophyte from nonchlorophyte cultured strains. The sensitivity of each probe was dependent upon the size of the cells and upon their growth stage. The mean fluorescence was 8 to 80 times higher for specifically labeled than for nonspecifically labeled cells in exponential growth phase, but it decreased sharply in stationary phase. Such taxon-specific probes should increase the applicability of flow cytometry for the rapid identification of cultured pico- and nanoplanktonic strains, especially those that lack taxonomically useful morphological features.