Stem Profile Research Articles

A "Switch" in Time through Genes Aligned: Unraveling the Genomic Landscape of HSC Development.

Seeking to define the "switch" from fetal to adult hematopoiesis, Li etal. (2020) performed extensive genomic and epigenomic profiling of hematopoietic stem and progenitor cells across ontogeny (as explored in this issue of Cell Stem Cell). Gradual and stochastic changes in genomic and epigenomic regulation suggest the absence of any specific regulator.

Ahusamiento y volumen comercial de pinos tropicales en plantaciones forestales de Veracruz, México

En los últimos años, en el sureste de México se han establecido plantaciones forestales de Pinus caribaea, que tienen como propósito la extracción de resina y la producción de madera. Ambas variables se han correlacionado positivamente con características morfológicas como la forma del fuste. Generalmente, para la descripción del perfil fustal se utilizan dos expresiones: factor de forma y ahusamiento. En este sentido, el objetivo del presente estudio fue construir un sistema de cubicación para estimar el ahusamiento y el volumen comercial de tres progenies de pinos tropicales establecidos en una plantación forestal en las Choapas, Veracruz, México, así como evaluar sus diferencias en la geometría del fuste a través de enfoque de variables indicadoras. Por medio del modelo de la variable combinada lineal y la utilización de variables indicadoras, se analizó el efecto de la procedencia en el factor de forma, encontrándose que el híbrido entre Pinus caribaea y Pinus elliotti presenta una geometría cercana al paraboloide. Se probaron diferentes modelos de ahusamiento, de los cuales, el de Demaerschalk presentó el mejor ajuste y, a partir de su integración matemática, se derivó una ecuación de volumen comercial variable, que se ajustó de manera simultánea con la de ahusamiento para generar un sistema compatible de ahusamiento-volumen comercial. Los resultados indican que el híbrido es superior en la geometría del fuste y en el volumen comercial maderable frente a las otras dos procedencias de Pinus caribaea.

The Sda Synthase B4GALNT2 Reduces Malignancy and Stemness in Colon Cancer Cell Lines Independently of Sialyl Lewis X Inhibition.

Background: The Sda antigen and its biosynthetic enzyme B4GALNT2 are highly expressed in healthy colon but undergo a variable down-regulation in colon cancer. The biosynthesis of the malignancy-associated sialyl Lewis x (sLex) antigen in normal and cancerous colon is mediated by fucosyltransferase 6 (FUT6) and is mutually exclusive from that of Sda. It is thought that the reduced malignancy associated with high B4GALNT2 was due to sLex inhibition. Methods: We transfected the cell lines SW480 and SW620, derived respectively from a primary tumor and a metastasis of the same patient, with the cDNAs of FUT6 or B4GALNT2, generating cell variants expressing either the sLex or the Sda antigens. Transfectants were analyzed for growth in poor adherence, wound healing, stemness and gene expression profile. Results: B4GALNT2/Sda expression down-regulated all malignancy-associated phenotypes in SW620 but only those associated with stemness in SW480. FUT6/sLex enhanced some malignancy-associated phenotypes in SW620, but had little effect in SW480. The impact on the transcriptome was stronger for FUT6 than for B4GALNT2 and only partially overlapping between SW480 and SW620. Conclusions: B4GALNT2/Sda inhibits the stemness-associated malignant phenotype, independently of sLex inhibition. The impact of glycosyltransferases on the phenotype and the transcriptome is highly cell-line specific.

The acidic tumor microenvironment drives a stem-like phenotype in melanoma cells

Acidosis characterizes the microenvironment of most solid tumors and is considered a new hallmark of cancer. It is mainly caused by both “aerobic” and “anaerobic” glycolysis of differently adapted cancer cells, with the final product lactic acid being responsible of the extracellular acidification. Many evidences underline the role of extracellular acidosis in tumor progression. Among the different findings, we demonstrated that acidosis-exposed cancer cells are characterized by an epithelial-to-mesenchymal transition phenotype with high invasive ability, high resistance to apoptosis, anchorage-independent growth, and drug therapy. Acidic melanoma cells over-express SOX2, which is crucial for the maintenance of their oxidative metabolism, and carbonic anhydrase IX, that correlates with poor prognosis of cancer patients. Considering these evidences, we realized that the profile outlined for acid cancer cells inevitably remind us the stemness profile. Therefore, we wondered whether extracellular acidosis might induce in cancer cells the acquisition of stem-like properties and contribute to the expansion of the cancer stem cell sub-population. We found that a chronic adaptation to acidosis stimulates in cancer cells the expression of stem-related markers, also providing a high in vitro/in vivo clonogenic and trans-differentiating ability. Moreover, we observed that the acidosis-induced stem-like phenotype of melanoma cells was reversible and related to the EMT induction. These findings help to characterize a further aspect of stem cell niche, contributing to the sustainment and expansion of cancer stem cell subpopulation. Thus, the usage of agents controlling tumor extracellular acidosis might acquire great importance in the clinic for the treatment of aggressive solid tumor.Key messages• Extracellular acidosis up-regulates EMT and stem-related markers in melanoma cells• Acidic medium up-regulates in vitro self-renewal capacity of melanoma cells• Chronic acidosis adaptation induces trans-differentiation ability in melanoma cells• Melanoma cells adapted to acidosis show higher tumor-initiating potential than control cells• Extracellular acidosis promotes a stem-like phenotype in prostate and colorectal carcinoma cells

A Comparative Evaluation of Three Stem Profile Equations for Three Precious Tree Species in Southern China

Accurately describing the stem curve of precious tree species and estimating the quantity of various types of wood and their volume in the tropics can provide technical support for reasonable bucking. This study utilized Erythrophleum fordii, Castanopsis hystrix and Tectona grandis as study objects. Forty replicates of each species were used for a total of 120 individual trees. Their tape equations were constructed using simple tape equations, segmented taper equations and variable form taper equations. Statistical indicators were utilized to determine the best taper equation for the three types of precious tree species. A number of methods were compared and analyzed, including the index of correlation, the residual sum of squares, the mean prediction error, the variance of prediction errors and the root mean square error. Finally, a preliminary quantitative analysis was conducted to determine the trends of these three types of tree species. The result shows that the precision of the three predictions developed for each species is high, and, in particular, the segmented taper equations with optimized algorithms is the best. The tendency of the three species to vary was shown to be the highest for T. grandis in the range of 0.0 to 0.8 for its relative height, followed by E. fordii, while the variation of C. hystrix was the smallest. However, in the range of 0.8 to 1.0 relative height, the variation of Castanopsis hystrix was the largest, and the variation of both E. fordii and T. grandis were almost the same. Therefore, the segmented taper equations with optimization algorithms was recommended to fit the three types of tree species in the tropics. These types of equations can be used to estimate the stumpage and timber quantity and as a guide reasonable bucking for these three species.

Fatty acid profile analysis of grape by-products from Slovakia and Austria

Fatty acid profile analysis of grape by-products from Slovakia and Austria

CD10/Neprilysin Enrichment in Infrapatellar Fat Pad–Derived Mesenchymal Stem Cells Under Regulatory-Compliant Conditions: Implications for Efficient Synovitis and Fat Pad Fibrosis Reversal

Background: Synovitis and infrapatellar fat pad (IFP) fibrosis participate in various conditions of the knee. Substance P (SP), a neurotransmitter secreted within those structures and historically associated with nociception, also modulates local neurogenic inflammatory and fibrotic responses. Exposure of IFP mesenchymal stem cells (IFP-MSCs) to a proinflammatory/profibrotic environment (ex vivo priming with TNFα, IFNγ, and CTGF) induces their expression of CD10/neprilysin, effectively degrading SP in vitro and in vivo. Purpose/Hypothesis: The purpose was to test the therapeutic effects of IFP-MSCs processed under regulatory-compliant protocols, comparing them side-by-side with standard fetal bovine serum (FBS)–grown cells. The hypothesis was that when processed under such protocols, IFP-MSCs do not require ex vivo priming to acquire a CD10-rich phenotype efficiently degrading SP and reversing synovitis and IFP fibrosis. Study Design: Controlled laboratory study. Methods: Human IFP-MSCs were processed in FBS or either of 2 alternative conditions—regulatory-compliant pooled human platelet lysate (hPL) and chemically reinforced medium (Ch-R)—and then subjected to proinflammatory/profibrotic priming with TNFα, IFNγ, and CTGF. Cells were assessed for in vitro proliferation, stemness, immunophenotype, differentiation potential, transcriptional and secretory profiles, and SP degradation. Based on a rat model of acute synovitis and IFP fibrosis, the in vivo efficacy of cells degrading SP plus reversing structural signs of inflammation and fibrosis was assessed. Results: When compared with FBS, IFP-MSCs processed with either hPL or Ch-R exhibited a CD10High phenotype and showed enhanced proliferation, differentiation, and immunomodulatory transcriptional and secretory profiles (amplified by priming). Both methods recapitulated and augmented the secretion of growth factors seen with FBS plus priming, with some differences between them. Functionally, in vitro SP degradation was more efficient in hPL and Ch-R, confirmed upon intra-articular injection in vivo where CD10-rich IFP-MSCs also dramatically reversed signs of synovitis and IFP fibrosis even without priming or at significantly lower cell doses. Conclusion: hPL and Ch-R formulations can effectively replace FBS plus priming to induce specific therapeutic attributes in IFP-MSCs. The resulting fine-tuned, regulatory-compliant, cell-based product has potential future utilization as a novel minimally invasive cell therapy for the treatment of synovitis and IFP fibrosis. Clinical Relevance: The therapeutic enhancement of IFP-MSCs manufactured under regulatory-compliant conditions suggests that such a strategy could accelerate the time from preclinical to clinical phases. The therapeutic efficacy obtained at lower MSC numbers than currently needed and the avoidance of cell priming for efficient results could have a significant effect on the design of clinical protocols to potentially treat conditions involving synovitis and IFP fibrosis.

Modelling bark thickness variation in stems of cork oak in south-western Portugal

The thickness of bark (cork) is of utmost importance for its industrial processing and, therefore, for the sustainable management of cork oak (Quercus suber L.) woodlands. Cork thickness has been reported to decrease from the stem base upwards but, to our knowledge, prediction models have not yet been presented. This study intended to develop reliable models to predict stem profiles of cork thickness. We addressed the relationship between bark thickness and stem height by measuring stem diameters and cork thickness at various stem heights in 76 trees. Through a repeated measure ANOVA, we selected the bark thickness response variables, cork-ring width and cork thickness. A mixed-effect modelling approach was used to fit linear bark thickness curves with stem height. Our results showed that the equations that performed better for cork thickness were functions of the stem relative height and cross-sectional cork area increment. The decreasing trend upwards the stem might lead to underestimation of cork thickness at the base, more than overestimate it at upper stem parts, in relation to the values at breast height, which are generally used to estimate the thickness of the whole cork plank. Furthermore, cork thickness curves were tree size-related, with larger trees exhibiting a steeper reduction in cork thickness upwards the stem.

Pengembangan Perangkat Pembelajaran Berbasis STEM (Science, Technology, Engineering, And Mathematics) Untuk Mahasiswa Prodi PGSD

Abstract: The general objective of this study was to find a kind of Science, Technology, Engineering, and Mathematics (STEM) study instruments, and the specific purposes of this study were to investigate the validity, effectiveness, and practicality of it. This was a Research & Development study which was simplified into two stages; they are the preliminary stage and the development stage. This study resulted several kinds of instruments: lesson plan, worksheets, material lesson, teaching evaluation sheets, observation sheets, and questionares. The validity was very good with score 84,38 % for content aspect, 82,50 % for language aspect, and 82,14 % for display aspect. The instruments were very effective to be used by elementary teacher education students and lecturers in the simple machines material to describe the STEM profile’s teacher education students. The instruments could practically be used by the elementary teacher education students and lecturers for the simple machines material based on the positive elementary teacher education students and lecturers responses. Students' science ability increased 27.20%, technology ability increased 23.36%, engineering ability increased 55.20%, and mathematics ability increased 81.80%. The effectiveness of learned was shown by the success of the lecturer in designed learning. The learning design got score of 100 from both expert. The developed learning device is practically used by students and lecturers for simple machines material based on positive responses of students and lecturer. The practicality of learning tools based STEM is shown from the implementation of learning. The percentage of student activities during STEM learning was 75.79%, it showed that student activities during learning including the good category and the teaching ability of lecturers got average score 97,73.

Dynamic sampling method for ship resistance performance optimisation based on approximated model

ABSTRACT Sampling method is an effective tool for building approximated models, which can improve the efficiency of hull form optimisation. A dynamic sampling method (DSM) is introduced herein to improve the accuracy and efficiency of the approximated model by considering the influences of sample quality measures in both input and output parameter spaces. The DSM uses leave-one-out to obtain an estimate of the cross-validation errors, which are maximised to determine the sample points in the design space. The variation is used for the calculation of continuous and multimodal regions. The proposed method is compared, using both numerical examples and hull form optimisation, with traditional sampling methods from the literature. The stem profile’s optimisation for KCS based on DSM and static sampling method is performed. And the optimised hull form with less ship resistance is obtained. The comparison results show that DSM performs better than the static sampling method. Abbreviations: AM: approximated models; ACE: accumulative error; AMDSM: approximated models based on dynamic sampling method; AMUD: approximated models based on uniform design; CAMM: continuous and multimodal; CF: covariance function; CFD: computational fluid dynamics; CV: cross validation; CVV: cross validation variance; DSM: dynamic sampling method; eLOO: leave-one-out error; LOO: leave-one-out; LHS: Latin Hypercube Sampling; MAPE: mean absolute predictive error; MCS: Monte Carlo Sampling; NN: neural network; RAAE: relative average absolute error; RMSE: root mean square error; SM: sampling methods; SP: sample points; SSM: static sampling method; TS: test samples; UDL: uniform design; VF: variation function.

Developing A Form Factor Function for Acacia Decurrensin Southwestern Amhara National Regional State, Ethiopia

Volumetric estimation is very important for a sustainable management of forest resources, yield prediction and also to know its growth rates. It is the product of DBH, tree height and form factor. Acacia decurrens Willd is extensively grown as a rotational crop for charcoal and productivity improvement in woodlot of Awi Zone. The objective of the study was to develop a form factor function that can estimate the stem profile of the tree species. Pollanschutz’s, F. Evert’s, Short Swedish’s, Mayer’s and Rosset’s form factor functions were tested to select the best one. The data were collected at 58 destructed trees from five years aged in two woodlots and one community-managed plantation of A. decurrens during farmers’ harvesting. To predict the volume of the species, all the functions were evaluated by Root mean square error (RMSE), mean absolute deviation (MAD), coefficient of variance (CV) and graph behavior of observed form factor. The performance of all functions was almost similar even though we chose Mayer’s and Pollanschutz’s functions due to their relatively lower values of RMSE, MAD and the nature of the graphs of predicted versus observed form factors are nearly stable. Based on this, 0.4875 was recommended to estimate the above ground stand volume of A. decurrens with a DBH range of 8-14cm for the five years old woodlot in the study site.

PLAG1 enhances the stemness profiles of acinar cells in normal human salivary glands in a cell type-specific manner

ObjectivesDetails of the histogenesis of salivary gland tumors are largely unknown. The oncogenic role of PLAG1 in the salivary gland has been demonstrated in vivo. Herein, we demonstrate PLAG1 roles in the acinar and ductal cells of normal human salivary glands to clarify the early events that occur during the histogenesis of salivary gland tumors. MethodsNormal salivary gland cells with acinar and ductal phenotypes were transfected with PLAG1 plasmid DNA. Subsequently, PLAG1 overexpressed and mock cells were examined by cell proliferation, transwell migration, and salisphere formation assays. Differentiation and salivary and pluripotent stem cell marker expression levels were evaluated by quantitative reverse transcription-polymerase chain reaction and immunofluorescence. Alterations in transcriptional expressions were investigated via cap analysis of gene expression with gene-enrichment and functional annotation analysis. ResultsPLAG1 promoted cell proliferation and transwell migration in the acinar and ductal cells, and markedly enhanced the stemness profiles and luminal cell-like profiles in acinar cells; the stemness profiles were partially increased in the ductal cells. ConclusionPLAG1 enhanced the stemness profiles in the acinar cells of normal human salivary glands in a cell type-specific manner. Thus, it may be involved in salivary gland tumorigenesis by increasing the stemness character of the normal salivary gland cells.

Natural Dyes Characterization of Local Plants as Acid-Base Indicator

Hanjuang, mangosteen, putat, and tabelian plants are used by people of Lanjak deras Village as natural dyes for woven cloth and food so that they can be used as an alternative substitute synthesis indicators that are limited in a remote area. The purpose of the study is to determine the best type of solvent in extracting the samples, pH range, UV spectrum profiles, precision, and accuracy of the plant's extract as indicator. The sample was the plants that are used by the people of West Borneo as natural dyes, namely putat flower, tebelian stem, mangosteen leave, and hanjuang leave. Each sample was macerated with four types of solvents, namely aquadest, ethanol, methanol, and (1:1) ethanol:methanol, then the extract was testing by pH range. The extracts providing color changes were determined for its UV-Vis spectrum profile, stability, accuracy, and precision. The results showed that ethanol and methanol were suitable for extracting mangosteen leaves, methanol for putat flowers, ethanol for hanjuang leaves, and (1: 1) ethanol:methanol for tebelian stems. Mangosteen leaf extract, putat flower, and tebelian stem gave a pH range of 12-14, while hanjuang leaf extract did not change color. The phytochemical test results and UV spectrum profile of mangosteen leaf extract, putat flower, and tebelian stem indicated the presence of phenolic compounds. The powder and extract solution had high stability. Mangosteen leaf extract, putat flower, and tebelian stem had precision and accuracy with the medium category. These data indicated that mangosteen leaf extract, putat flower, and tebelian stem have potential as indicators of acid-base.

ARTIFICIAL NEURAL NETWORKS AND MIXED-EFFECTS MODELING TO DESCRIBE THE STEM PROFILE OF Pinus taeda L.

The aim of this study was to compare the effectiveness of artificial neural networks (ANNs) and mixed-effects models (MEMs) in describing the stem profile of Pinus taeda L., using sample data from 246 trees. First, three taper functions of different classes were adjusted: non-segmented, segmented, and variable-form. To adjust the models, the nonlinear regression technique (nls) was used. In the best performance equation for nls-adjusted diameter estimates, the nonlinear MEM (nlme) was applied at two levels, using the age class (ci) and DBH class (cd). For this, three different study scenarios were considered, with the number of coefficients with random effects ranging from one to three in each scenario. The adjustments were made using the nls and nlme functions in R software. The selected mixed-effect equations were compared with ANNs generated in Neuro 4.0 software. The taper function models and ANNs were classified according to statistical criteria and graphical analysis of residues. The tapering equation of Bi (2000) presented better performance for diameter estimates than the non-segmented and segmented equations. Application of the nlme technique in the Bi (2000) equation increased the accuracy of the diameter estimates for Pinus taeda, in relation to the adjustment using the nls technique. In the comparison of ANNs with the variations of the Bi equation of mixed-effects, the networks performed better, indicated in the description of the P. taeda profile.

A new model for predicting the total tree height for stems cut-to-length by harvesters in Pinus radiata plantations

A new model for predicting the total tree height for harvested stems from cut-to-length (CTL) harvester data was constructed for Pinus radiata (D.Don) following a conceptual analysis of relative stem profiles, comparisons of candidate models forms and extensive selections of predictor variables. Stem profiles of more than 3000 trees in a taper data set were each processed 6 times through simulated log cutting to generate the data required for this purpose. The CTL simulations not only mimicked but also covered the full range of cutting patterns of nearly 0.45 × 106 stems harvested during both thinning and harvesting operations. The single-equation model was estimated through the multiple-equation generalized method of moments estimator to obtain efficient and consistent parameter estimates in the presence of error correlation and heteroscedasticity that were inherent to the systematic structure of the data. The predictive performances of our new model in its linear and nonlinear form were evaluated through a leave-one-tree-out cross validation process and compared against that of the only such existing model. The evaluations and comparisons were made through benchmarking statistics both globally over the entire data space and locally within specific subdivisions of the data space. These statistics indicated that the nonlinear form of our model was the best and its linear form ranked second. The prediction accuracy of our nonlinear model improved when the total log length represented more than 20% of the total tree height. The poorer performance of the existing model was partly attributed to the high degree of multicollinearity among its predictor variables, which led to highly variable and unstable parameter estimates. Our new model will facilitate and widen the utilization of harvester data far beyond the current limited use for monitoring and reporting log productions in P. radiata plantations. It will also facilitate the estimation of bark thickness and help make harvester data a potential source of taper data to reduce the intensity and cost of the conventional destructive taper sampling in the field. Although developed for P. radiata, the mathematical form of our new model will be applicable to other tree species for which CTL harvester data are routinely captured during thinning and harvesting operations.

BRAIN-DERIVED NEUROTORPHIC FACTOR EXPRESSION AS A PROGNOSIS MARKER IN SQUAMOUS CELL CARCINOMA

Objectives To evaluate the association between the brain-derived neurotrophic factor (BDNF) and tyrosine kinase receptor B (TrkB) pathway with disease-specific survival, cell senescence, and profile in oral squamous cell carcinoma (OSCC). Study Design Specimens from 87 primary OSCC were arranged into tissue microarray (TMA) blocks. Immunohistochemical analysis for BDNF, TrkB, P-AKT, P-S6, BM1, and p16 were performed. The slides were scanned into high-resolution images using the Aperio Scanscope CS Slide Scanner and evaluated using software for digital analysis. Statistical analysis was performed using the SPSS software. Receiver operating curves were constructed to establish the cut-off values. Results All OSCC cases analyzed were positive for BDNF, TrkB, P-AKT, and pS6. Patients with high BDNF and high P-Akt expression presented, respectively, a 2.83-fold and 2.19-fold significantly higher chance of dying during the follow-up period. An increase in TrkB expression was directly correlated with increased cell senescence measured through p16. The stemness profile, accessed by BM1 expression, was inversely correlated with P-Akt and directly correlated with pS6. Conclusions The increased availability of BDNF influences OSCC prognosis presumably by activating downstream targets such as Akt. Moreover, this pathway seems to have an influence in cell senescence and profile. FIPE/HCPA:160437.

A model form for stem taper and volume estimates of Asian white birch (Betula platyphylla): a major commercial tree species of Northeast China

Stem taper functions are valuable tools for the study of stem profile and predict volume estimates. Such functions have long been analyzed for different birch species in the world. However, Asian white birch (Betula platyphylla Suk.) has not yet been investigated as an individual species in China or abroad. This study presents stem taper and volume equations for B. platyphylla in Northeast China. Eight commonly used taper functions were fit to the data of 615 destructively sampled trees from two regions of Northeast China. A second-order continuous autoregressive error structure was incorporated to address the autocorrelation in the data and to achieve the valid parameter estimation. The condition number was used to detect the multicollinearity in the models. The taper functions were compared in terms of overall evaluation statistics and by examining the box plots of diameter and volume residuals against relative heights and diameter classes. The equations of A. Kozak (2004, For. Chron. 80(4): 507–515; model 2), Z. Fang et al. (2000, For. Sci. 46(1): 1–12), and H. Bi (2000, For. Sci. 46(3): 397–409) were the leading models for diameter and volume estimates. Overall, the equation of Z. Fang et al. (2000, For. Sci. 46(1): 1–12) exhibited the best results for estimating diameter and total and merchantable volumes in terms of statistical performance and lower multicollinearity.

Pharmacognostic Profile of Root and Stem of Indigofera Tirunelvelica Sanjappa

Pharmacognostic Profile of Root and Stem of Indigofera Tirunelvelica Sanjappa

CALIBRATING A TAPER MODEL FOR ORIENTAL SPRUCE IN TURKEY

ABSTRACT In this study, Max and Burkhart (1976)’s segmented taper model was used to describe stem profile and predict stem volume of oriental spruce in Turkey. Thirty procedures were evaluated, which include five fitting methods and six adjustment strategies. The fitting methods resulted in parameters that were optimized for (1) taper, (2) cumulative volume, (3) taper and cumulative volume, (4) taper and total volume, and (5) taper, cumulative volume, and total volume. The adjustment strategies are (1) unadjusted, and adjusted to match (2) DBH, (3) predicted total volume, (4) DBH and predicted total volume, (5) a combined estimator, and (6) DBH and a combined estimator. Results showed that, without adjustment, the model with parameters optimized for taper gave good prediction for both taper and cumulative volume. Mixed results were obtained when various adjustment strategies were used on different fitting techniques. The overall best-ranked procedure for predicting both taper and volume was the model optimized for taper and cumulative volume and then adjusted to fit the combined estimator.

Mobile Laser Scanning for Estimating Tree Stem Diameter Using Segmentation and Tree Spine Calibration

Mobile laser scanning (MLS) could make forest inventories more efficient, by using algorithms that automatically derive tree stem center positions and stem diameters. In this work we present a novel method for calibration of the position for laser returns based on tree spines derived from laser data. A first calibration of positions was made for sequential laser scans and further calibrations of laser returns were possible after segmentation, in which laser returns were associated to individual tree stems. The segmentation made it possible to model tree stem spines (i.e., center line of tree stems). Assumptions of coherent tree spine positions were used for correcting laser return positions on the tree stems, thereby improving estimation of stem profiles (i.e., stem diameters at different heights from the ground level). The method was validated on six 20-m radius field plots. Stem diameters were estimated with a Root-Mean-Square-Error (RMSE) of 1 cm for safely linked trees (maximum link distance of 0.5 m) and with a restriction of a minimum amount of data from height intervals for supporting circle estimates. The accuracy was high for plot level estimates of basal area-weighted mean stem diameter (relative RMSE 3.4%) and basal area (relative RMSE 8.5%) because of little influence of small trees (i.e., aggregation of individual trees). The spine calibration made it possible to derive 3D stem profiles also from 3D laser data calculated from sensor positions with large errors because of disturbed below canopy signals from global navigation satellite systems.