Association between physical activity and leisure-time sedentary behavior among 140,808 adolescents aged 12 to 15 from 47 low- and middle-income countries.

OBJECTIVES: Data from high-income countries (HICs) indicate that sedentary behavior is negatively associated with moderate-to-vigorous physical activity (MVPA) in young people. We examined associations between leisure-time sedentary behavior (LTSB) and MVPA in adolescents from 47 low- and middle-income countries (LMICs). STUDY DESIGN: Cross-sectional study. METHODS: Data from the Global school-based Student Health Survey were analyzed in 140,808 adolescents (13.8 ± 1.0 years; 49% girls). Time spent in LTSB was a composite variable assessing time spent sitting and playing computer games, watching TV, talking with friends during a typical day. The PACE + Adolescent Physical Activity Measure assessed MVPA levels. The association between ≥3 h/day of LTSB and adequate physical activity levels (every day last week 60 min MVPA) was explored with multivariable logistic regression analyses. RESULTS: The prevalence of ≥3 h/day of LTSB and 60 min of MVPA/day last week were 26.3% (girls 26.2%; boys 26.5%) and 15.3% (girls 12.1%; boys 18.4%), respectively. LTSB of ≥3 h/day versus <3 h/day was associated with a 35% increased odds for adequate levels of MVPA in boys [OR = 1.35 (95%CI = 1.23-1.48)] and 22% in girls [1.22 (95%CI = 1.10-1.36)]. CONCLUSIONS: Our data indicate that being physically active 60 min per day every day and at moderate-to-vigorous intensity and being sedentary ≥3 h/day during leisure-time might co-exist in adolescents in some LMICs.

Assessing physical activity in people with mental illness: 23-country reliability and validity of the simple physical activity questionnaire (SIMPAQ).

BACKGROUND: Physical inactivity is a key contributor to the global burden of disease and disproportionately impacts the wellbeing of people experiencing mental illness. Increases in physical activity are associated with improvements in symptoms of mental illness and reduction in cardiometabolic risk. Reliable and valid clinical tools that assess physical activity would improve evaluation of intervention studies that aim to increase physical activity and reduce sedentary behaviour in people living with mental illness. METHODS: The five-item Simple Physical Activity Questionnaire (SIMPAQ) was developed by a multidisciplinary, international working group as a clinical tool to assess physical activity and sedentary behaviour in people living with mental illness. Patients with a DSM or ICD mental illness diagnoses were recruited and completed the SIMPAQ on two occasions, one week apart. Participants wore an Actigraph accelerometer and completed brief cognitive and clinical assessments. RESULTS: Evidence of SIMPAQ validity was assessed against accelerometer-derived measures of physical activity. Data were obtained from 1010 participants. The SIMPAQ had good test-retest reliability. Correlations for moderate-vigorous physical activity was comparable to studies conducted in general population samples. Evidence of validity for the sedentary behaviour item was poor. An alternative method to calculate sedentary behaviour had stronger evidence of validity. This alternative method is recommended for use in future studies employing the SIMPAQ. CONCLUSIONS: The SIMPAQ is a brief measure of physical activity and sedentary behaviour that can be reliably and validly administered by health professionals.

Burnout and compassion fatigue among Exercise Physiologists in mental healthcare.

BACKGROUND: Burnout and compassion fatigue (CF) are common among mental health practitioners. Accredited Exercise Physiologists (AEPs) provide clinical services to individuals experiencing mental illness, increasing their likelihood of experiencing burnout and CF. AIMS: To examine the prevalence of burnout and CF among AEPs working with people experiencing mental illness. METHODS: An anonymous online cross-sectional survey of AEPs working with people experiencing mental illness was distributed via the Exercise and Sports Science Australia Mental Health Special Interest Group Facebook page between July and November 2019. In addition to demographics and caseload data, respondents completed the Professional Quality of Life scale and Oldenburg Burnout Inventory (OLBI). Results are reported using descriptive statistics. RESULTS: Sixty-two AEPs (68%, n = 42 female) completed the survey. Most (n = 53, 86%) reported delivering services to consumers with severe mental health conditions. Less than half (n = 27, 44%) reported working in a dedicated mental health facility. Moderate levels of burnout and CF were experienced by 60% and 30% of respondents, respectively. CONCLUSIONS: The prevalence of moderate burnout and CF symptoms in AEPs is comparable with other mental health professionals. Strategies to preserve psychological well-being such as enhancing mental health training for undergraduates and formalized supervision structures discussed.

Treating depression with physical activity in adolescents and young adults: a systematic review and meta-analysis of randomised controlled trials.

We aimed to establish the treatment effect of physical activity for depression in young people through meta-analysis. Four databases were searched to September 2016 for randomised controlled trials of physical activity interventions for adolescents and young adults, 12-25 years, experiencing a diagnosis or threshold symptoms of depression. Random-effects meta-analysis was used to estimate the standardised mean difference (SMD) between physical activity and control conditions. Subgroup analysis and meta-regression investigated potential treatment effect modifiers. Acceptability was estimated using dropout. Trials were assessed against risk of bias domains and overall quality of evidence was assessed using GRADE criteria. Seventeen trials were eligible and 16 provided data from 771 participants showing a large effect of physical activity on depression symptoms compared to controls (SMD = -0.82, 95% CI = -1.02 to -0.61, p < 0.05, I2 = 38%). The effect remained robust in trials with clinical samples (k = 5, SMD = -0.72, 95% CI = -1.15 to -0.30), and in trials using attention/activity placebo controls (k = 7, SMD = -0.82, 95% CI = -1.05 to -0.59). Dropout was 11% across physical activity arms and equivalent in controls (k = 12, RD = -0.01, 95% CI = -0.04 to 0.03, p = 0.70). However, the quality of RCT-level evidence contributing to the primary analysis was downgraded two levels to LOW (trial-level risk of bias, suspected publication bias), suggesting uncertainty in the size of effect and caution in its interpretation. While physical activity appears to be a promising and acceptable intervention for adolescents and young adults experiencing depression, robust clinical effectiveness trials that minimise risk of bias are required to increase confidence in the current finding. The specific intervention characteristics required to improve depression remain unclear, however best candidates given current evidence may include, but are not limited to, supervised, aerobic-based activity of moderate-to-vigorous intensity, engaged in multiple times per week over eight or more weeks. Further research is needed. (Registration: PROSPERO-CRD 42015024388).

The effects of vitamin and mineral supplementation on symptoms of schizophrenia: a systematic review and meta-analysis.

BACKGROUND: When used as an adjunctive with antipsychotics, certain vitamins and minerals may be effective for improving symptomatic outcomes of schizophrenia, by restoring nutritional deficits, reducing oxidative stress, or modulating neurological pathways. METHOD: We conducted a systematic review of all randomized controlled trials (RCTs) reporting effects of vitamin and/or mineral supplements on psychiatric symptoms in people with schizophrenia. Random-effects meta-analyses were used to calculate the standardized mean difference between nutrient and placebo treatments. RESULTS: An electronic database search in July 2016 identified 18 eligible RCTs, with outcome data for 832 patients. Pooled effects showed that vitamin B supplementation (including B6, B8 and B12) reduced psychiatric symptoms significantly more than control conditions [g = 0.508, 95% confidence interval (CI) 0.01-1.01, p = 0.047, I 2 = 72.3%]. Similar effects were observed among vitamin B RCTs which used intention-to-treat analyses (g = 0.734, 95% CI 0.00-1.49, p = 0.051). However, no effects of B vitamins were observed in individual domains of positive and negative symptoms (both p > 0.1). Meta-regression analyses showed that shorter illness duration was associated with greater vitamin B effectiveness (p = 0.001). There were no overall effects from antioxidant vitamins, inositol or dietary minerals on psychiatric symptoms. CONCLUSIONS: There is preliminary evidence that certain vitamin and mineral supplements may reduce psychiatric symptoms in some people with schizophrenia. Further research is needed to examine how the benefits of supplementation relate to nutrient deficits and the impact upon underlying neurobiological pathways, in order to establish optimal nutrient formulations for improving clinical outcomes in this population. Future studies should also explore the effects of combining beneficial nutrients within multi-nutrient formulas.

Motivating factors and barriers towards exercise in severe mental illness: a systematic review and meta-analysis.

Exercise can improve clinical outcomes in people with severe mental illness (SMI). However, this population typically engages in low levels of physical activity with poor adherence to exercise interventions. Understanding the motivating factors and barriers towards exercise for people with SMI would help to maximize exercise participation. A search of major electronic databases was conducted from inception until May 2016. Quantitative studies providing proportional data on the motivating factors and/or barriers towards exercise among patients with SMI were eligible. Random-effects meta-analyses were undertaken to calculate proportional data and 95% confidence intervals (CI) for motivating factors and barriers toward exercise. From 1468 studies, 12 independent studies of 6431 psychiatric patients were eligible for inclusion. Meta-analyses showed that 91% of people with SMI endorsed 'improving health' as a reason for exercise (N = 6, n = 790, 95% CI 80-94). Among specific aspects of health and well-being, the most common motivations were 'losing weight' (83% of patients), 'improving mood' (81%) and 'reducing stress' (78%). However, low mood and stress were also identified as the most prevalent barriers towards exercise (61% of patients), followed by 'lack of support' (50%). Many of the desirable outcomes of exercise for people with SMI, such as mood improvement, stress reduction and increased energy, are inversely related to the barriers of depression, stress and fatigue which frequently restrict their participation in exercise. Providing patients with professional support to identify and achieve their exercise goals may enable them to overcome psychological barriers, and maintain motivation towards regular physical activity.

Physical activity and depression: a large cross-sectional, population-based study across 36 low- and middle-income countries.

OBJECTIVE: Physical activity (PA) is good for health, yet several small-scale studies have suggested that depression is associated with low PA. A paucity of nationally representative studies investigating this relationship exists, particularly in low- and middle-income countries (LMICs). This study explored the global association of PA with depression and its mediating factors. METHOD: Participants from 36 LMICs from the World Health Survey were included. Multivariable logistic regression analyses were undertaken exploring the relationship between PA and depression. RESULTS: Across 178 867 people (mean ± SD age = 36.2 ± 13.5 years; 49.9% male), the prevalence of depression and the prevalence of low PA were 6.6% and 16.8% respectively. The prevalence of low PA was significantly higher among those with depression vs. no depression (26.0% vs. 15.8%, P < 0.0001). In the adjusted model, depression was associated with higher odds for low PA (OR = 1.42; 95% CI = 1.24-1.63). Mediation analyses demonstrated that low PA among people with depression was explained by mobility limitations (40.3%), pain and discomfort (35.8%), disruptions in sleep and energy (25.2%), cognition (19.4%) and vision (10.9%). CONCLUSION: Individuals with depression engage in lower levels of PA in LMICs. Future longitudinal research is warranted to better understand the relationships observed.

Effect of dietary fish oil on the expression of genes involved in lipid metabolism in liver and skeletal muscle of lactating sows.

This study investigated the hypothesis that dietary supplementation of fish oil as a source of n-3 polyunsaturated fatty acids (PUFA) influences the expression of target genes of sterol regulatory element-binding proteins (SREBP)-1 and (SREBP)-2 involved in triacylglycerol (TAG) synthesis and fatty acid and cholesterol metabolism in the liver, and moreover activates the expression of target genes of peroxisome proliferation-activated receptor (PPAR)-α involved in TAG and fatty acid catabolism in liver and skeletal muscle. Twenty lactating sows were fed a control diet or a fish oil diet with either 50 g of a mixture of palm oil and soya bean oil (4:1, w/w) or fish oil per kg. The diet of the fish oil group contained 19.1 g of n-3 PUFA (mainly 20:5 n-3 and 22:6 n-3) per 100 g of total fatty acids, while the diet of the control group contained 2.4 g of n-3 PUFA (mainly 18:3 n-3) per 100 g of total fatty acids. The fish oil group had reduced relative mRNA concentrations of various target genes of SREBP-1 involved in fatty acid and TAG synthesis in comparison with the control group (p < 0.05). Relative mRNA concentrations of target genes of PPARα involved in fatty acid catabolism in both liver and muscle, and mRNA concentrations of target genes of SREBP-2 involved in cholesterol synthesis and uptake were not influenced by fish oil supplementation. Concentrations of cholesterol and TAG in plasma, fat content of milk and weight gains of litters during the suckling period were not different between the two groups of sows. In conclusion, this study suggests that fish oil has only minor effects on hepatic lipid metabolism, which are non-critical with respect to milk production in sows.

Exercise augmentation compared with usual care for post-traumatic stress disorder: a randomized controlled trial.

OBJECTIVE: To investigate the impact of a 12-week exercise programme in addition to usual care for post-traumatic stress disorder (PTSD). METHOD: An assessor-blinded randomized controlled trial was conducted among 81 participants with a DSM-IV-TR diagnosis of primary PTSD. Participants were recruited after admission to an in-patient programme at a private hospital. Participants were randomized to receive either usual care (n=42), or exercise in addition to usual care (n=39). The exercise intervention involved three, 30-min resistance-training sessions/week and a pedometer-based walking programme. Usual care involved psychotherapy, pharmaceutical interventions, and group therapy. Primary outcome was PTSD symptoms assessed via the PTSD checklist-civilian version (PCL-C). Secondary outcomes included symptoms of depression, anthropometry, physical activity, mobility, strength, and sleep quality. RESULTS: Participants had a mean (SD) age of 47.8 years (12.1), 84% male. PTSD symptoms in the intervention group significantly reduced compared with the usual care group (mean difference=-5.4, 95% CI -10.5 to -0.3, P=0.04, n=58). There were significant between-group differences at follow-up for depressive symptoms, waist circumference, sleep quality, and sedentary time. CONCLUSION: This study provides the first evidence that an exercise intervention is associated with reduced PTSD and depressive symptoms, reduced waist circumference, and improved sleep quality.

Promotion of cardiorespiratory fitness in schizophrenia: a clinical overview and meta-analysis.

OBJECTIVE: Cardiorespiratory fitness (CRF) is a major modifiable risk factor for cardiovascular disease (CVD). We conducted a clinical overview to highlight the reduced CRF expressed as maximal oxygen uptake (VO2max) (or predicted) or peak oxygen uptake (VO2 peak) in people with schizophrenia compared to the general population. We also aimed to identify correlates of and clinical strategies to improve CRF. METHOD: We systematically searched major electronic databases from inception until November 2014. A meta-analysis calculating the standardised mean difference (SMD) was employed. RESULTS: CRF was significantly reduced in people with schizophrenia (n = 154) with a SMD of -0.96 (95% CI -1.29 to -0.64) (N = 5) compared to controls (n = 182). Negative symptoms, increased body mass index and female gender were negatively associated with CRF. Promoting physical activity may improve CRF in people with schizophrenia by up to 4-4.5 ml/kg/min following a 6-8 weeks programme (N = 4, n = 98). CONCLUSION: People with schizophrenia have a large and significantly reduced CRF. Given the overwhelming evidence for physical activity as the cornerstone of preventing and managing CVD in the general population, incorporating such interventions in the treatment of people with schizophrenia is justified and urgently required. We present clear practical strategies of how this can be achieved within clinical settings.

The prevalence of pain in bipolar disorder: a systematic review and large-scale meta-analysis.

OBJECTIVE: To conduct a meta-analysis investigating the prevalence of pain in people with bipolar disorder (BD). METHOD: A systematic review and random effects meta-analysis searching major electronic databases from inception till 01/2014 in accordance with the PRISMA statement. We included articles reporting quantitative data on the prevalence of pain in people with BD with or without a healthy control group. Two independent authors conducted searches, extracted data, and completed methodological quality assessment. RESULTS: Twenty two cross-sectional studies were included, representing 12,375,644 individuals (BD n=171,352, n controls=12,204,292). The prevalence of pain in people with BD was 28.9% (95% CI=16.4-43.4%, BD n=171,352). The relative risk (RR) of pain in BD compared to controls was 2.14 (95% CI=1.67-2.75%, n=12,342,577). The prevalence of migraine was 14.2% (95% CI=10.6-18.3%, BD n=127,905), and the RR was 3.30 (95% CI=2.27-4.80%, n=6,732,220).About 23.7% (95% CI=13.1-36.3%, n=106,214) of people with BD experienced chronic pain. Age, percentage of males, methodological quality, and method of BD classification did not explain the observed heterogeneity. CONCLUSION: People with BD experience significantly increased levels of pain (particularly chronic pain and migraine). The assessment and treatment of pain should form an integral part of the management of BD.

Paroxysmal atrial fibrillation occurs often in cryptogenic ischaemic stroke. Final results from the SURPRISE study.

BACKGROUND AND PURPOSE: Atrial fibrillation (AF) increases the risk of stroke fourfold and is associated with a poor clinical outcome. Despite work-up in compliance with guidelines, up to one-third of patients have cryptogenic stroke (CS). The prevalence of asymptomatic paroxysmal atrial fibrillation (PAF) in CS remains unknown. The SURPRISE project aimed at determining this rate using long-term cardiac monitoring. METHODS: Patients with CS after protocolled work-up including electrocardiography (ECG) and telemetry were included after informed consent. An implantable loop recorder (ILR) was implanted subcutaneously. PAF was defined by events of atrial arrhythmia >2 min with a correlating one-lead ECG confirming the diagnosis. RESULTS: Eighty-five patients were monitored for a mean of 569 days (SD ±310). PAF was documented in 18 patients (20.7%) during the study period and detected by ILR in 14 patients (16.1%). In three patients PAF was detected by other methods before or after monitoring and was undiscovered due to device sensitivity in one case. The first event of PAF was documented at a mean of 109 days (SD ±48) after stroke onset. PAF was asymptomatic in all cases and occurred in episodes lasting predominantly between 1 and 4 h. Four recurrent strokes were observed, three in patients with PAF; all three patients were on oral anticoagulation (OAC). CONCLUSIONS: One in five patients with CS had PAF, which occurred at low burden and long after stroke. Future studies should determine the role of implantable cardiac monitors after stroke and determine the potential therapeutic benefit of OAC treatment of patients with PAF.

The UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase gene is mutated in recessive hereditary inclusion body myopathy.

Hereditary inclusion body myopathy (HIBM; OMIM 600737) is a unique group of neuromuscular disorders characterized by adult onset, slowly progressive distal and proximal weakness and a typical muscle pathology including rimmed vacuoles and filamentous inclusions. The autosomal recessive form described in Jews of Persian descent is the HIBM prototype. This myopathy affects mainly leg muscles, but with an unusual distribution that spares the quadriceps. This particular pattern of weakness distribution, termed quadriceps-sparing myopathy (QSM), was later found in Jews originating from other Middle Eastern countries as well as in non-Jews. We previously localized the gene causing HIBM in Middle Eastern Jews on chromosome 9p12-13 (ref. 5) within a genomic interval of about 700 kb (ref. 6). Haplotype analysis around the HIBM gene region of 104 affected people from 47 Middle Eastern families indicates one unique ancestral founder chromosome in this community. By contrast, single non-Jewish families from India, Georgia (USA) and the Bahamas, with QSM and linkage to the same 9p12-13 region, show three distinct haplotypes. After excluding other potential candidate genes, we eventually identified mutations in the UDP-N-acetylglucosamine-2-epimerase/N-acetylmannosamine kinase (GNE) gene in the HIBM families: all patients from Middle Eastern descent shared a single homozygous missense mutation, whereas distinct compound heterozygotes were identified in affected individuals of families of other ethnic origins. Our findings indicate that GNE is the gene responsible for recessive HIBM.

Male-immature relationships in multi-male groups of mountain gorillas (Gorilla beringei beringei).

We examined the pattern and possible functions of social interactions between adult males and immatures in three free-ranging, multi-male groups of mountain gorillas (Gorilla beringei beringei). Previous studies conducted during the 1970s when groups contained one to three adult males concluded that male-immature relationships were likely to be a form of low-cost paternal investment [Stewart, Mountain gorillas: three decades of research at Karisoke. Cambridge, UK: Cambridge University Press, 2001]. We evaluated whether this hypothesis still held in groups containing six to nine adult males, or if male-immature relationships might serve other functions (e.g. mating effort, kin selection, or alliance building). Overall, we found that immatures spent the most time near, and interacted most with, the alpha silverback. These behaviors peaked during the period when infants were still quite vulnerable but increasing their independence from their mothers. Such findings suggest that parenting effort remains the primary function of male-immature relationships; however, there is some evidence for the mating effort hypothesis as well.

Characterization of hereditary inclusion body myopathy myoblasts: possible primary impairment of apoptotic events.

Hereditary inclusion body myopathy (HIBM) is a unique muscular disorder caused by mutations in the UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase (GNE) gene. GNE encodes a bi-functional enzyme acting in the biosynthetic pathway of sialic acid. Since the underlying myopathological mechanism leading to the disease phenotype is poorly understood, we have established human myoblasts cultures, derived from HIBM satellite cells carrying the homozygous M712T mutation, and identified cellular and molecular characteristics of these cells. HIBM and control myoblasts showed similar heterogeneous patterns of proliferation and differentiation. Upon apoptosis induction, phosphatidylserine externalization was similar in HIBM and controls. In contrast, the active forms of caspase-3 and -9 were strongly enhanced in most HIBM cultures compared to controls, while pAkt, downregulated in controls, remained high in HIBM cells. These results could indicate impaired apoptotic signaling in HIBM cells. Since satellite cells enable partial regeneration of the post-mitotic muscle tissue, these altered processes could contribute to the muscle mass loss seen in patients. The identification of survival defects in HIBM affected muscle cells could disclose new functions for GNE in muscle cells.

Acute MRI changes in progressive ischemic stroke.

BACKGROUND AND PURPOSE: Neurological deterioration following acute stroke is common and associated with increased morbidity and mortality. The underlying pathophysiological mechanisms are not fully understood, and it is difficult to predict which patients are at risk of deterioration. Our study aimed to assess if acute MRI findings could be used for the prediction of stroke in progression (SIP). METHODS: Prospectively 41 patients, 13 with lacunar infarcts and 28 with territorial infarcts, were admitted to an acute stroke unit within 24 h of stroke onset (median 11 h, range 3- 22). Diffusion-weighted imaging (DWI), perfusion-weighted imaging and magnetic resonance angiography were performed 3 times, immediately after clinical evaluation, on day 7 and after 3 months. Clinical neurological assessments were performed every 2 h during the first 24 h and once daily from day 2 to 7. SIP was defined as a permanent decrease of >or=3 Scandinavian Stroke Scale (SSS) points for speech or >or=2 SSS points for consciousness or >or=2 SSS points for limb strength, when assessed at baseline compared to the day after admission and daily during the following week. Patients were followed up on day 90 and assessed using the modified Rankin Scale, Barthel Index and SSS score. Patients with and without SIP were compared using both clinical and MRI data obtained on admission, on day 7 and after 3 months. RESULTS: Fifteen patients (37%) developed SIP. Increased DWI lesion volume on day 7 in all strokes was associated with SIP (chi(2), p = 0.005). All lacunar infarcts with a DWI volume >1.5 cm(3) at baseline (4 patients) developed SIP (p < 0.005). Patients with territorial infarcts and SIP had lower baseline SSS scores with severer symptoms than non-SIP patients (p

Inducible expression of the human interferon beta 1 gene linked to a bovine papilloma virus DNA vector and maintained extrachromosomally in mouse cells.

A 1.6-kilobase DNA segment of the genomic human interferon beta 1 (IF-beta 1) gene was inserted into each of two possible orientations at the single HindIII site of a recombinant plasmid pBPV69T, consisting of the 69% transforming region of the bovine papilloma virus type 1 (BPV-1) and a modified SalI-SalI fragment of plasmid pBR322. After cleavage of the pBR322 sequences from this recombinant, BPV69T-IF-beta 1 hybrid DNAs were transfected onto C127 mouse cells by the standard calcium precipitation technique. Mouse cells transformed by this hybrid DNA produced low levels of human IF-beta 1 constitutively and responded to induction with either inactivated Newcastle disease virus or polyriboinosinic acid-polyribocytidylic acid. The BPV69T-IF-beta 1 hybrid DNA was nonintegrated in the transformed mouse cells but had acquired DNA sequences as a result of the transfection. Accurate transcripts of the IF-beta 1 mRNA were detected in cells only after induction. When the IF-beta 1 gene was oriented in the plasmid in the same direction of transcription as the BPV-1 genome, transcription was promoted from within the BPV-1 sequences. These results indicate that the regulatory sequences responsible for the inducible expression of the human IF-beta 1 gene are present in the 1.6-kilobase genomic segment and that these sequences can function in a free extrachromosomal state linked to BPV-1 sequences.

Fluidity of membrane lipids and lateral mobility of concanavalin A receptors in the cell surface of normal lymphocytes and lymphocytes from patients with malignant lymphomas and leukemias.

Lymphocytes isolated from the peripheral blood of patients with nonmalignant and malignant disorders were studied for fluidity of membrane lipids and lateral mobility of concanavalin A (Con A) receptors. The degree of fluidity of the surface membrane lipid core was monitored quantitatively by fluorescence polarization analysis using the probe 1,6-diphenyl-1,3,5-hexatriene embedded in lipid regions of the surface membrane of intact cells. Mobility of Con A surface receptors was determined by the cap-forming ability after binding of fluorescent Con A. The present studies were performed on lymphocytes from 28 patients with malignant lymphomas, 22 patients with leukemia, 28 individuals who either were healthy or had nonmalignant disorders, and 5 patients with carcinoma. The results showed that lymphocytes and mononuclear cells from patients with malignant lymphomas and leukemias have a more fluid lipid layer in their surface membrane than do lymphocytes obtained from healthy individuals or from patients with other malignant and nonmalignant disorders. This increase in membrane fluidity was less pronounced in lymphocytes isolated from leukemic patients in clinical remission and from leukemic patients receiving treatment with steroids. The results also show a marked difference in the cap-forming ability of lymphocytes from patients with malignant lymphomas or leukemia as compared with lymphocytes from patients with non-malignant disorders or carcinoma. Lymphocytes isolated from lymphoma and chronic lymphatic leukemia patients during remission stages of the disease exhibited a higher cap-forming ability. The cap-forming ability of cells from patients with chronic lymphocytic leukemia was unaffected by treatment with steroids. The present results, which are in line with previous observations, have shown that normal lymphocytes can be characterized by a low degree of lipid fluidity but a high degree of mobility of Con A receptors, whereas leukemic lymphocytes are characterized by a high degree of lipid fluidity but a low degree of mobility of Con A receptors. These results confirmed our general hypothesis on the dynamic interrelation between membrane lipids and membrane protein receptors, and they indicate that the widely accepted term "membrane fluidity" requires better consideration for different membrane components.