Bone homeostasis is securely controlled by the dynamic well‐balanced actions among osteoclasts, osteoblasts and osteocytes. Osteoclasts are large multinucleated cells that degrade bone matrix and involve in the bone remodelling in conjunction with other bone cells, osteoblasts and osteocytes, the completely matured form of osteoblasts. Disruption of this controlling balance among these cells or any disparity in bone remodelling caused by a higher rate of resorption by osteoclasts over construction of bone by osteoblasts results in a reduction of bone matrix including bone mineral density (BMD) and bone marrow cells (BMCs). The dominating effect of osteoclasts results in advanced risk of bone crack and joint destruction in several diseases including osteoporosis and rheumatoid arthritis (RA). However, the boosted osteoblastic activity produces osteosclerotic phenotype and weakened its action primes to osteomalacia or rickets. On the other hand, senescent osteocytes predominately progress the senescence associated secretory phenotype (SASP) and may contribute to age related bone loss. Here, we discuss an advanced level work on newly identified cellular mechanisms controlling the remodelling of bone and crosstalk among bone cells as these relate to the therapeutic targeting of the skeleton.

Mofizul IK Forhad (5) , Mariam Akhter (4-6) , Zaheer Iqbal (4) , Falgoonee Kumar Mondol (6) Allometric models are commonly used to estimate biomass, nutrients and carbon stocks in trees, and contribute to an understanding of forest status and resource dynamics. The selection of appropriate and robust models, therefore, have considerable influence on the accuracy of estimates obtained. Allometric models can be developed for individual species or to represent a community or bioregion. In Bangladesh, the nation forest inventory classifies tree and forest resources into five zones (Sal, Hill, Coastal, Sundarbans and Village), based on their floristic composition and soil type. This study has developed allometric biomass models for multi-species of the Sal zone. The forest of Sal zone is dominated by Shorea robusta Roth. The study also investigates the concentrations of Nitrogen, Phosphorus, Potassium and Carbon in different tree components. A total of 161 individual trees from 20 different species were harvested across a range of tree size classes. Diameter at breast height (DBH), total height (H) and wood density (WD) were considered as predictor variables, while total above-ground biomass (TAGB), stem, bark, branch and leaf biomass were the output variables of the allometric models. The best fit allometric biomass model for TAGB, stem, bark, branch and leaf were: ln (TAGB) =-2.460 + 2.171 ln (DBH) + 0.367 ln (H) + 0.161 ln (WD); ln (Stem) =-3.373 + 1.934 ln (DBH) + 0.833 ln (H) + 0.452 ln (WD); ln (Bark) =-5.87 + 2.103 ln (DBH) + 0.926 ln (H) + 0.587 ln (WD); ln (Branch) =-3.154 + 2.798 ln (DBH)-0.729 ln (H)-0.355 ln (WD); and ln (Leaf) =-4.713 + 2.066 ln (DBH), respectively. Nutrients and carbon concentration in tree components varied according to tree species and component. A comparison to frequently used regional and pantropical biomass models showed a wide range of model prediction error (35.48 to 85.51%) when the observed TAGB of sampled trees were compared with the estimated TAGB of the models developed in this study. The improved accuracy of the best fit model obtained in this study can therefore be used for more accurate estimation of TAGB and carbon and nutrients in TAGB for the Sal zone of Bangladesh.

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The study was undertaken to assess the tourist's carrying capacity and to explore ecotourism potential of Bangabandhu Sheikh Mujib Safari Park, the only safari park of Bangladesh. Carrying capacity was assessed both from physical and social aspect. On the other hand, 250 visitors were interviewed with semi structured questionnaire for ecotourism prospect evaluation along with some secondary data. The total daily-allowed visit was 17,300 with rotation coefficient of 3.46. Maximum daily average numbers of tourists were relatively below the physical carrying capacity of the Park (5,000). The social carrying capacity was 4.38 persons per day. As there are different categories of visitors, their choice of encounters and number of expected encounters also varied. Each year, the total tourist's number varied significantly (p≤0.05). That proved the safari park had immense tourist prospect. 85 percent visitors were from lower and middle class family as entrance fees and other fees inside were very cheap in relation to other private amusement place. The ecological perspective of the park will remain unaltered if the carrying capacities of the area are followed with sustainability. Therefore, it is the proper time for taking appropriate decision.

The current study investigated the immunomodulating and osteoblast differentiation potential of the natural compounds from Leea macrophylla (LMN). Immunomodulatory effects have been investigated by the phagocytosis of Candida albicans using polymorphonuclear neutrophil cells in the in vitro slide method. A bioactivity‐guided fractionation technique was used to evaluate the stimulating effect of L. macrophylla methanol extract on osteoblast differentiation using mouse osteoblastic cells. A low dose of LMN was found to stimulate the phagocytic effect better than a higher dose. The natural compounds from L. macrophylla have significantly increased alkaline phosphatase (ALP) and osteocalcin activities. The LMN promoted the osteoblast differentiation through upregulation of ALP, osteocalcin, and type 1 collagen in a dose‐dependent manner. These natural compounds also upregulated ALP, osteocalcin, and type 1 collagen gene expressions. The data suggest that LMN has potential anabolic sequel on bone formation and osteoblast differentiation.