Beyond power amplification: latch-mediated spring actuation is an emerging framework for the study of diverse elastic systems.

Rapid biological movements, such as the extraordinary strikes of mantis shrimp and accelerations of jumping insects, have captivated generations of scientists and engineers. These organisms store energy in elastic structures (e.g. springs) and then rapidly release it using latches, such that movement is driven by the rapid conversion of stored elastic to kinetic energy using springs, with the dynamics of this conversion mediated by latches. Initially drawn to these systems by an interest in the muscle power limits of small jumping insects, biologists established the idea of power amplification, which refers both to a measurement technique and to a conceptual framework defined by the mechanical power output of a system exceeding muscle limits. However, the field of fast elastically driven movements has expanded to encompass diverse biological and synthetic systems that do not have muscles - such as the surface tension catapults of fungal spores and launches of plant seeds. Furthermore, while latches have been recognized as an essential part of many elastic systems, their role in mediating the storage and release of elastic energy from the spring is only now being elucidated. Here, we critically examine the metrics and concepts of power amplification and encourage a framework centered on latch-mediated spring actuation (LaMSA). We emphasize approaches and metrics of LaMSA systems that will forge a pathway toward a principled, interdisciplinary field.

The effect of activation level on muscle function during locomotion: are optimal lengths and velocities always used?

Skeletal muscle exhibits broad functional diversity, despite its inherent length and velocity constraints. The observed variation in morphology and physiology is assumed to have evolved to allow muscle to operate at its optimal length and velocity during locomotion. Here, we used the variation in optimum lengths and velocities that occurs with muscle activation level to experimentally test this assumption. Muscle ergometry and sonomicrometry were used to characterize force-length and power-velocity relationships, and in vivo operating lengths and velocities, at a range of activation levels. Operating lengths and velocities were mapped onto activation level specific force-length and power-velocity relationships to determine whether they tracked changing optima. Operating velocities decreased in line with decreased optimal velocities, suggesting that optimal velocities are always used. However, operating lengths did not change with changing optima. At high activation levels, fibres used an optimal range of lengths. However, at lower activation levels, fibres appeared to operate on the ascending limb of sub-maximally activated force-length relationships. This suggests that optimal lengths are only used when demand is greatest. This study provides the first mapping of operating lengths to activation level-specific optima, and as such, provides insight into our assumptions about the factors that determine muscle performance during locomotion.

Locomotor function shapes the passive mechanical properties and operating lengths of muscle.

Locomotor muscles often perform diverse roles, functioning as motors that produce mechanical energy, struts that produce force and brakes that dissipate mechanical energy. In many vertebrate muscles, these functions are not mutually exclusive and a single muscle often performs a range of mechanically diverse tasks. This functional diversity has obscured the relationship between a muscle's locomotor function and its mechanical properties. I use hopping in toads as a model system for comparing muscles that primarily produce mechanical energy with muscles that primarily dissipate mechanical energy. During hopping, hindlimb muscles undergo active shortening to produce mechanical energy and propel the animal into the air, whereas the forelimb muscles undergo active lengthening to dissipate mechanical energy during landing. Muscles performing distinct mechanical functions operate on different regions of the force-length curve. These findings suggest that a muscle's operating length may be shaped by potential trade-offs between force production and sarcomere stability. In addition, the passive force-length properties of hindlimb and forelimb muscles vary, suggesting that passive stiffness functions to restrict the muscle's operating length in vivo. These results inform our understanding of vertebrate muscle variation by providing a clear link between a muscle's locomotor function and its mechanical properties.

What drives activation-dependent shifts in the force-length curve?

Skeletal muscles are rarely recruited maximally during movement. However, much of our understanding of muscle properties is based on studies using maximal activation. The effect of activation level on skeletal muscle properties remains poorly understood. Muscle optimum length increases with decreased activation; however, the mechanism responsible is unclear. Here, we attempted to determine whether length-dependent calcium effects, or the effect of absolute force underpin this shift. Fixed-end contractions were performed in frog plantaris muscles at a range of lengths using maximal tetanic (high force, high calcium), submaximal tetanic (low force, high calcium) and twitch (low force, low calcium) stimulation conditions. Peak force and optimum length were determined in each condition. Optimum length increased with decreasing peak force, irrespective of stimulation condition. Assuming calcium concentration varied as predicted, this suggests that absolute force, rather than calcium concentration, underpins the effect of activation level on optimum length. We suggest that the effect of absolute force is due to the varying effect of the internal mechanics of the muscle at different activation levels. These findings have implications for our understanding of in vivo muscle function and suggest that mechanical interactions within muscle may be important determinants of force at lower levels of activation.

Association of Vascular Endothelial Growth Factor Levels with Risk of Alzheimer's Disease: A Systematic Review and Meta-Analysis.

BACKGROUND: Alzheimer's disease (AD) is a progressive neurodegenerative illness that leads to impairment of cognitive functions and memory loss. Even though there is a plethora of research reporting the abnormal regulation of VEGF expression in AD pathogenesis, whether the CSF and serum VEGF are increased in AD is an open question yet. In this study, the association of CSF and serum VEGF concentrations with the risk of Alzheimer's disease was investigated using systematic review and meta-analysis. METHODS: A systematic literature search was carried out using online specialized biomedical databases of Web of Science, Pubmed, Scopus, Embase, and Google Scholar until Feb 2023 without restriction to the beginning time. The meta-analysis was performed using the random-effects model and only case-control publications describing VEGF concentrations in Alzheimer's patients were considered for calculating the pooled effect size. RESULTS: In the systematic literature search, 6 and 13 studies met the inclusion criteria to evaluate CSF and serum VEGF concentrations of Alzheimer's patients, respectively. This meta-analysis retrieved a total number of 2380 Alzheimer's patients and 5368 healthy controls. Under the random-effects model in the meta-analysis, the pooled SMD for CSF and serum VEGF concentrations of Alzheimer's patients were -0.13 (95%CI,-0.42-0.16) and 0.23 (95%CI,-0.27-0.73), respectively. Results of meta-regression analysis showed that the quality scores of papers and female sex ratios of participants did not affect the associations of VEGF concentrations with the risk of Alzheimer's disease. However, the age average of patients significantly affects the associations of CSF VEGF concentrations with the risk of Alzheimer's disease (P=0.051). There was a statistically significant subgroup effect for the disease severity of Alzheimer's patients which modifies the associations of serum VEGF concentrations with the risk of Alzheimer's disease (P<0.01) and subgroup analysis shows that study location modifies the associations of CSF and serum VEGF concentrations with the risk of Alzheimer's disease (P<0.01). CONCLUSION: The results show that the serum VEGF concentrations increased for Alzheimer's patients in accordance with the increased expression of VEGF and the VEGF levels of Alzheimer's patients decreased by increasing their disease severities. Therefore, in addition to detecting AD in the earliest stages of the disease, serum VEGF could be a promising biomarker to follow up on the disease and evaluate the clinical course of the disease.

Chasing maximal performance: a cautionary tale from the celebrated jumping frogs of Calaveras County.

Maximal performance is an essential metric for understanding many aspects of an organism's biology, but it can be difficult to determine because a measured maximum may reflect only a peak level of effort, not a physiological limit. We used a unique opportunity provided by a frog jumping contest to evaluate the validity of existing laboratory estimates of maximum jumping performance in bullfrogs (Rana catesbeiana). We recorded video of 3124 bullfrog jumps over the course of the 4-day contest at the Calaveras County Jumping Frog Jubilee, and determined jump distance from these images and a calibration of the jump arena. Frogs were divided into two groups: 'rental' frogs collected by fair organizers and jumped by the general public, and frogs collected and jumped by experienced, 'professional' teams. A total of 58% of recorded jumps surpassed the maximum jump distance in the literature (1.295 m), and the longest jump was 2.2 m. Compared with rental frogs, professionally jumped frogs jumped farther, and the distribution of jump distances for this group was skewed towards long jumps. Calculated muscular work, historical records and the skewed distribution of jump distances all suggest that the longest jumps represent the true performance limit for this species. Using resampling, we estimated the probability of observing a given jump distance for various sample sizes, showing that large sample sizes are required to detect rare maximal jumps. These results show the importance of sample size, animal motivation and physiological conditions for accurate maximal performance estimates.

In vitro study on the effect of doxorubicin on the proliferation markers MCM3 and Ki-67.

PURPOSE: Aberrant proliferation is an essential feature of cancer cells, which can be caused by alterations in components of the cell cycle, such as minichromosome maintenance protein-3 (MCM3) and Ki-67. Doxorubicin is a cytotoxic/cytostatic anticancer agent commonly used in chemotherapy. We investigated the effect of this drug on MCM3 and Ki-67 in the KB cell line, which is considered a subline of HeLa cell line. METHODS: KB cells were treated with doxorubicin and its effect on apoptosis, mRNA levels and protein expression of MCM3 and Ki-67 was determined by flow cytometry (annexin V-FITC/PI assay), quantitative real-time RT-PCR (qRT-PCR) and immunocytochemistry, respectively. Cytotoxicity was assessed using the MTT assay. One-way analysis of variance (ANOVA) was used for comparing groups and differences were assessed by a Tukey's post hoc test. RESULTS: Protein expression of both biomarkers and MCM3 mRNA were not affected by doxorubicin, but Ki-67 mRNA significantly increased after treatment (p=0.049). CONCLUSIONS: Considering that doxorubicin can influence certain biochemical events that lead to modifications in Ki- 67, this factor might be useful in evaluating the impact of anthracycline-based chemotherapeutic agents. Changes in MCM3 following doxorubicin treatment require further investigation.

Linking in vivo muscle dynamics to in situ force-length and force-velocity reveals that guinea fowl lateral gastrocnemius operates at shorter than optimal lengths.

Force-length (F-L) and force-velocity (F-V) properties characterize skeletal muscle's intrinsic properties under controlled conditions, and it is thought that these properties can inform and predict in vivo muscle function. Here, we map dynamic in vivo operating range and mechanical function during walking and running, to the measured in situ F-L and F-V characteristics of guinea fowl (Numida meleagris) lateral gastrocnemius (LG), a primary ankle extensor. We use in vivo patterns of muscle tendon force, fascicle length, and activation to test the hypothesis that muscle fascicles operate at optimal lengths and velocities to maximize force or power production during walking and running. Our findings only partly support our hypothesis: in vivo LG velocities are consistent with optimizing power during work production, and economy of force at higher loads. However, LG does not operate at lengths on the force plateau (±5% Fmax) during force production. LG length was near L0 at the time of EMG onset but shortened rapidly such that force development during stance occurred almost entirely on the ascending limb of the F-L curve, at shorter than optimal lengths. These data suggest that muscle fascicles shorten across optimal lengths in late swing, to optimize the potential for rapid force development near the swing-stance transition. This may provide resistance against unexpected perturbations that require rapid force development at foot contact. We also found evidence of passive force rise (in absence of EMG activity) in late swing, at lengths where passive force is zero in situ, suggesting that dynamic history dependent and viscoelastic effects may contribute to in vivo force development. Direct comparison of in vivo work loops and physiological operating ranges to traditional measures of F-L and F-V properties suggests the need for new approaches to characterize dynamic muscle properties in controlled conditions that more closely resemble in vivo dynamics.

Spring and latch dynamics can act as control pathways in ultrafast systems.

Ultrafast movements propelled by springs and released by latches are thought limited to energetic adjustments prior to movement, and seemingly cannot adjust once movement begins. Even so, across the tree of life, ultrafast organisms navigate dynamic environments and generate a range of movements, suggesting unrecognized capabilities for control. We develop a framework of control pathways leveraging the non-linear dynamics of spring-propelled, latch-released systems. We analytically model spring dynamics and develop reduced-parameter models of latch dynamics to quantify how they can be tuned internally or through changing external environments. Using Lagrangian mechanics, we test feedforward and feedback control implementation via spring and latch dynamics. We establish through empirically-informed modeling that ultrafast movement can be controllably varied during latch release and spring propulsion. A deeper understanding of the interconnection between multiple control pathways, and the tunability of each control pathway, in ultrafast biomechanical systems presented here has the potential to expand the capabilities of synthetic ultra-fast systems and provides a new framework to understand the behaviors of fast organisms subject to perturbations and environmental non-idealities.

Molecular analysis of MEN1 expression in MCF7, T47D and MDA-MB 468 breast cancer cell lines treated with adriamycin using RT-PCR and immunocytochemistry.

BACKGROUND AND THE PURPOSE OF THE STUDY: MEN1 is an important tumor suppressor gene that encodes a nuclear protein called menin. Recent data suggest that interactions between menin and other proteins have important roles in control of the cell cycle and apoptosis. In addition, estrogen receptor (ER), an important prognostic factor is differentially expressed in breast cancer cells. In this study the MEN1 gene and protein expression in MCF7, T47D and MDA-MB-468 breast cancer cell lines with different ER status following exposure to adriamycin (ADR) was investigated. MATERIALS AND METHODS: Cytotoxicity of ADR on these cell lines was determined using MTT assay. The mRNA and protein levels were analyzed in tested cell lines using RT-PCR and immunocytochemistry (ICC) assays, respectively. RESULTS: ADR cytotoxicity was highest on MDA-MB-468 and lowest on MCF7 cells. MEN1 mRNA showed significant decrease after ADR exposure only in the MDA-MB-468 cell line. Menin protein expression was higher in MDA-MB-468 and lower in MCF7 cells. CONCLUSION: Differential molecular responses to adriamycin were observed in cancer cell lines. Molecular data also suggest that MEN1 as a new biomarker can be used in combination with current biomarkers for prediction of response to chemotherapy.

Resistance to radial expansion limits muscle strain and work.

The collagenous extracellular matrix (ECM) of skeletal muscle functions to transmit force, protect sensitive structures, and generate passive tension to resist stretch. The mechanical properties of the ECM change with age, atrophy, and neuromuscular pathologies, resulting in an increase in the relative amount of collagen and an increase in stiffness. Although numerous studies have focused on the effect of muscle fibrosis on passive muscle stiffness, few have examined how these structural changes may compromise contractile performance. Here we combine a mathematical model and experimental manipulations to examine how changes in the mechanical properties of the ECM constrain the ability of muscle fibers and fascicles to radially expand and how such a constraint may limit active muscle shortening. We model the mechanical interaction between a contracting muscle and the ECM using a constant volume, pressurized, fiber-wound cylinder. Our model shows that as the proportion of a muscle cross section made up of ECM increases, the muscle's ability to expand radially is compromised, which in turn restricts muscle shortening. In our experiments, we use a physical constraint placed around the muscle to restrict radial expansion during a contraction. Our experimental results are consistent with model predictions and show that muscles restricted from radial expansion undergo less shortening and generate less mechanical work under identical loads and stimulation conditions. This work highlights the intimate mechanical interaction between contractile and connective tissue structures within skeletal muscle and shows how a deviation from a healthy, well-tuned relationship can compromise performance.

Optimized Seizure Detection Algorithm: A Fast Approach for Onset of Epileptic in EEG Signals Using GT Discriminant Analysis and K-NN Classifier.

BACKGROUND: Epilepsy is a severe disorder of the central nervous system that predisposes the person to recurrent seizures. Fifty million people worldwide suffer from epilepsy; after Alzheimer's and stroke, it is the third widespread nervous disorder. OBJECTIVE: In this paper, an algorithm to detect the onset of epileptic seizures based on the analysis of brain electrical signals (EEG) has been proposed. 844 hours of EEG were recorded form 23 pediatric patients consecutively with 163 occurrences of seizures. Signals had been collected from Children's Hospital Boston with a sampling frequency of 256 Hz through 18 channels in order to assess epilepsy surgery. By selecting effective features from seizure and non-seizure signals of each individual and putting them into two categories, the proposed algorithm detects the onset of seizures quickly and with high sensitivity. METHOD: In this algorithm, L-sec epochs of signals are displayed in form of a third-order tensor in spatial, spectral and temporal spaces by applying wavelet transform. Then, after applying general tensor discriminant analysis (GTDA) on tensors and calculating mapping matrix, feature vectors are extracted. GTDA increases the sensitivity of the algorithm by storing data without deleting them. Finally, K-Nearest neighbors (KNN) is used to classify the selected features. RESULTS: The results of simulating algorithm on algorithm standard dataset shows that the algorithm is capable of detecting 98 percent of seizures with an average delay of 4.7 seconds and the average error rate detection of three errors in 24 hours. CONCLUSION: Today, the lack of an automated system to detect or predict the seizure onset is strongly felt.

Classic Kaposi's sarcoma in Jews living in Israel, 1961-1989: a population-based incidence study.

BACKGROUND: The incidence of classic Kaposi's sarcoma (CKS) has been reported to be high in Jewish populations, mostly born in Eastern Europe. OBJECTIVE: To describe the incidence on CKS in Israeli Jews and to determine differences in incidence according to their geography origin. DESIGN: We analysed data on 1098 incident CKS cases with known country of origin occurring between 1961 and 1989 in the Jewish Israeli population. Reporting systems were the Israel Cancer Registry, the medical documentation of all-Kaposi's sarcoma cases and the registry of HIV-seropositive patients. Patients who were seropositive for HIV were excluded from the study population. Population figures for groups of migrants and natives were derived from census surveys (1961, 1972, 1983) and inter-census estimates based on the population registry. RESULTS: The overall age-standardized rate of CKS was 16.9 per million in men and 6.3 per million in women. The ratio between genders remained stable during the study period. In both genders, there was a steep increase in CKS incidence between the late 1960s (age-standardized rates per million: 8.0 in men and 2.2 in women) and the early 1970s (17.9 in men and 6.7 in women). No further increase was present after 1971. Overall, immigrants experienced a relative risk (RR) of 1.17 [95% confidence interval (CI) 0.90-1.521 compared with Jews born in Israel. Immigrants from Morocco, Algeria and Tunisia had the highest incidence (RR 2.01; 95% CI 1.52-2.65) compared with Jews born in Israel, followed by those born in Iraq (RR 1.74; CI 95% 1.27-2.37). The lowest incidence was experienced by immigrants from Iran (RR 0.37; CI 95% 0.18-0.77) and from Central European countries (RR 0.45; CI 95% 0.30-0.66). Immigrants from other countries in Asia, Africa, the Americas and Europe had similar rates as Jews born in Israel. CONCLUSIONS: Israeli Jews present one of the highest incidences of CKS reported from developed countries. The incidence varies according to geographical origin. Countries surrounding the Mediterranean sea represent the area of highest CKS incidence.

Two p16 (CDKN2A) germline mutations in 30 Israeli melanoma families.

Germline mutations in the p16 (CDKN2A) tumour suppressor gene have been linked to inherited predisposition to malignant melanoma (MM). Variable frequencies of p16 germline mutations were reported in different collections of melanoma families but it can be as high as 50%. Here we describe the results of p16 mutation screening in 30 melanoma kindreds in Israel. The entire coding region of the p16 gene, including exons 1, 2 and 3, flanking exon/intron junctions, and a portion of the 3' untranslated (UTR) region of the gene were examined by single-stranded conformation polymorphism (SSCP) analysis and direct sequencing. Two p16 germline mutations were identified: G101W, which has been previously observed in a number of melanoma kindreds, and G122V, a novel missense mutation. Thus, the frequency of mutations identified in this collection of Israeli families was 7%. Functional analysis indicated that the novel G122V variant retained some capacity to interact with cyclin dependent kinases (CDKs) in vitro, yet it was significantly impaired in its ability to cause a G1 cell cycle arrest in human diploid fibroblasts. This partial loss of function is consistent with the predicted impact of G122V substitution on the 3-dimensional structure of the p16 protein.

A 15-year study of the role of Aeromonas spp. in gastroenteritis in hospitalised children.

During a 15-year period, 146 strains of Aeromonas spp. were isolated from 32810 faecal specimens from 13,820 hospitalised patients up to 13 years of age. These isolates constituted 4% of all the pathogenic bacterial strains cultured. For the years 1978-1988, the files of children with gastro-enteritis revealed 81 whose faeces yielded Aeromonas spp. Most of them (94%) were < 3 years of age, 78% < 1 year old. The peak incidence was at 2-6 months, involving severe morbidity including dehydration and vomiting with acidaemia and azotaemia; the mean duration of illness and length of hospitalisation at this age were longer than at other ages. Bloody diarrhoea was found in 7% of the children. Almost all the strains of Aeromonas were resistant to ampicillin. We conclude that Aeromonas spp. are of aetiological significance in gastro-enteritis in small children; culture for this pathogen should be routine in the bacteriological examination of faeces.

Cutaneous manifestations of familial Mediterranean fever.

Familial Mediterranean fever (FMF) is frequently accompanied by erysipelas-like attacks. These should alert the physician to the correct diagnosis of this systemic disease. Several other nonspecific skin lesions may be seen in FMF. To our knowledge, histologic findings in erysipelas-like skin rashes seen in FMF are not reported elsewhere in the literature.

Combined vitamin A and E therapy prevents retinal electrophysiological deterioration in abetalipoproteinaemia.

Eight patients with abetalipoproteinaemia had the typical ocular, systemic, and laboratory findings of this disease. Combined therapy with vitamins A and E was administered, starting as early as the first day of life and as late as 26 years of age. The patients were followed up for 2-6 years. Electroretinography was undertaken in all cases and electrooculography in some. After initiation of vitamin A and E therapy no progression of disturbed visual function could be detected in any patient. These objective tests of retinal function demonstrated that the combined vitamin A and E therapy may be useful in arresting retinal deterioration in abetalipoproteinaemia.

Evaluation of immunotoxicity induced by diazinon in C57bl/6 mice.

Diazinon (DZN), an organophosphate insecticide, has been used in agriculture for several years. It is possible the residue of this compound to be recycled in the biological system. There is no report on DZN immunotoxicity potential. In the present study, we examined the immunotoxic effects of intraperitoneally administered DZN in the C57bl/6 female mice. Diazinon was administered at doses of 25, 2, and 0.2 mg/kg for 28 days (five injections per week). Animals were then sacrificed to observe the cellularity or histopathological changes in thymus, spleen, bone marrow, and peripheral blood. Furthermore, humoral and cellular functional responses such as Hemagglutination titration (HA), IgM-Plaque Forming Colony Assay (PFC), Delayed-Type-Hypersensitivity (DTH) to SRBC, and T cell subtyping (CD4/CD8) were determined. The results showed that DZN at 25 mg/kg not only could produce gross histopathological changes in thymus and spleen but also could suppress both humoral and cellular activity of the immune system. At lower doses (0.2 and 2 mg/kg) there were no observable alteration in cellularity or histology of immune tissues. However, DZN at medium dose (2 mg/kg per day) could inhibit RBC-cholinesterase and showed a mild decrease (P < 0.1) in thymus/body-weight ratio and DTH response. At dose of 0.2 mg/kg no histopathological or functional disturbances were detectable. These results indicate that DZN has immunosuppressive effects in the C57bl/6 mice at doses more than 2 mg/kg. The present results however indicate that under recommended Allowed Daily Intake (ADI) limit (<0.02 mg/kg), no observable immunotoxicity effect is expected.

Favourable melanoma prognosis associated with the expression of the tumour necrosis factor receptor and the alpha1beta1 integrin: a preliminary report.

Recently we encountered a patient (p1) with a Clark's level IV melanoma associated with recurrent cutaneous metastasis who subsequently experienced a complete remission after a period of therapy with dichloronitrobenzene (DCNB) and interferon-alpha (IFNalpha). Another patient (p2) with a similar Clark's level of disease but with a fatal prognosis and melanoma cells from the Sk-Mel 28 and MeWo cell lines served as control groups. Since cytokines and members of the alpha1 integrin family have been implicated in the growth and metastatic behaviour of melanomas, we evaluated the cytokine effects and integrins expressed by melanoma cells in the patients' tumours. P1, but not p2 nor MeWo melanoma cells, expressed HLA-DR, alpha1beta1 and the tumour necrosis factor receptor (TNF-R). Culturing p1 melanoma cells with TNFalpha, but not MeWo or p2 melanoma cells, increased their expression of alpha1beta1 integrin and was cytotoxic for the cells. Significant in vivo growth of metastatic p1 and p2 melanoma explants as well as MeWo cells grafted subcutaneously onto nude mice was noted over 36 days. Intralesional injection of TNFalpha induced complete regression of p1 explants, but not of p2 or MeWo explants. Intralesional injection of IFNalpha or anti-alpha1beta1 integrin arrested p1 graft growth. These results suggest that the slow growth of the melanoma cells in nude mice, as well as the susceptibility to tumour killing by TNFalpha and the dependence of the tumour on signals mediated by the alpha1beta1 integrin are features that may have contributed to the beneficial therapeutic response in patient 1.