*5.2.4 Modification of undergrowth*

Alteration and modification of undergrowth vegetation is one of the major conservation issues, a lot of the forestlands are facing in Bangladesh. Both the Bangladesh Forest Department (BFD) and local community contribute to this factor. Collection of dead leaves from the forest floor prevents natural seed germination, which eventually hinder undergrowth plant diversity. The forest department permits local people to clean up undergrowth and eventually plant canes (*Calamus rotang*) in the forestland. The rapid growth and aggressive nature of canes prevents growth of other plant species. The forest department also encourages bamboo plant during winter season, which results the monoculture of bamboo undergrowth and ultimately contributes to the topsoil erosion of the forests [5].

#### *5.2.5 Grazing by livestock*

Deforestation is closely associated with overgrazing in many parts of the world, and Bangladesh is no exception [4]. Overgrazing by domesticated animals and farming play a major role in natural forest regeneration. Free-range cattle in the forestland would eliminate seedlings, which would potentially regenerate the forest. Grazing also accelerates soil erosion [10].

**27**

*Forest Biodiversity and Deforestation in Bangladesh: The Latest Update*

travel allocations to make necessary field interventions [4].

*5.3.2 Lack of coordination among different agencies*

Huge landslide during rainy season in the hilly region (Chittagong and CHT) of Bangladesh is quite common and one of the major reasons for the lack of vegetation cover of the area. Landslides change the hydrological pattern of forest and could be

The Ministry of Environment and Forests (MoEF) is the sole authority from the government side to implement and enforce natural resource-related activities and laws. The Bangladesh Forest Department and Department of Environment operates under the MoEF and two major wings to manage natural resources in Bangladesh. However, limitations like poor institutional capacity, lack of logistical and operational support, and insufficient funding and manpower are holding the country behind. Most of the field offices in the peripheral forest range have no vehicles or

There is lack of coordination in the management of biodiversity and natural resources among different government agencies in Bangladesh. For example, there are overlaps between the jurisdictions of the Bangladesh Forest Department, Department of Environment (DoE), and Ministry of Land (MoL). Coordination gaps or overlaps are also found among different projects and among different donor agencies, especially in high-profile areas like the Sundarbans. Lack of coordination is also observed at the transboundary level, especially between water rights and usage between Bangladesh and neighboring countries that are the upstream sources of water [4].

Information is not widely available in Bangladesh, and with regard to field level baseline data on natural resources, there is no single place to get everything. Aside from some modest university efforts, there is a dire lack of scientific data on forest, wetland, and aquatic species. This information is crucial for effective management of natural resources and biodiversity of the country. There are no long-term monitoring efforts to evaluate any changes in species occurrence, abundance, and distribution in Bangladesh [4]. Bangladesh managed to have a number of sound environmental policies, but that is not enough, and there are many gaps. For example, donor-initiated conservation projects are not sustained after the funding tenure is over. The government either does not have their interest or no self-funding

Environmental crime is not treated as seriously as other types of crime either by the local communities or by the law enforcement agencies. Although there are laws related to natural resources in Bangladesh, enforcement of these laws is very poor. Poachers are often politically connected and often are protected by their leaders or contractors [4]. Even when a case makes it into the court, there are no incentives (monitory or logistic) for the forest officials who are willing to testify before court.

capability to continue the project initiated by a donor agency [32].

*DOI: http://dx.doi.org/10.5772/intechopen.86242*

an issue for animal movement [2].

*5.3.1 Poor institutional capacity*

*5.3.3 Policy and information gap*

*5.3.4 Lack of enforcement*

*5.2.6 Land erosion*

**5.3 Indirect threats**

*Forest Biodiversity and Deforestation in Bangladesh: The Latest Update DOI: http://dx.doi.org/10.5772/intechopen.86242*

### *5.2.6 Land erosion*

*Forest Degradation Around the World*

animals [4].

*5.2.2 Fuel wood extraction*

mangrove forest [5].

*5.2.4 Modification of undergrowth*

hinder regeneration of the forest [4].

*5.2.3 Expansion of agricultural activities*

gibbons, capped langurs, macaques, and squirrels for their movement and breeding activities. Fragmentation of forest also restricts the movement of mammals from one habitat to another, which poses more threats to their existence. Moreover, due to the softwood demand in plywood industry, illegal poaching of softwood trees is also happening in Bangladesh, which would otherwise provide food for the wild

Almost all households, in and around the forests, use fuel wood for daily livelihood. Majority of the fuelwoods are sourced from the nearby forests. The local people generally collect dead or fallen trees or branches, which do not contribute directly to the destruction of trees in the forest; but it has other ecological consequences. Some local community members live on selling the fuelwood extracted from the forest. Fallen leaves collection is a major problem in deciduous forests in the central as well as in the northern part of the country. Leaf and fuelwood collectors clean up the undergrowth of the forest and also cut down seedlings which

Several crops are extensively cultivated on the hill slopes and in the low-lying areas in and around the forestland in Bangladesh. Pineapple, banana (*Musa* spp.), citrus, bean (*Vigna* spp.), and papaya (*Carica papaya*) are mainly cultivated on the hilltop. Paddy (*Oryza* spp.) is cultivated in the low land between two hills [4]. For making the land cultivable, local people usually clean the forest floor, burn the unwanted vegetation, and cultivate the desired crops, resulting in destruction of natural vegetation. Local farmers slowly expand their cultivation land each year, which causes rapid fragmentation of the forestland. Expansion of agricultural land is one of the major problems of deforestation in Bangladesh except the Sundarbans

Alteration and modification of undergrowth vegetation is one of the major conservation issues, a lot of the forestlands are facing in Bangladesh. Both the Bangladesh Forest Department (BFD) and local community contribute to this factor. Collection of dead leaves from the forest floor prevents natural seed germination, which eventually hinder undergrowth plant diversity. The forest department permits local people to clean up undergrowth and eventually plant canes (*Calamus rotang*) in the forestland. The rapid growth and aggressive nature of canes prevents growth of other plant species. The forest department also encourages bamboo plant during winter season, which results the monoculture of bamboo undergrowth and ultimately contributes to the topsoil erosion of the

Deforestation is closely associated with overgrazing in many parts of the world,

and Bangladesh is no exception [4]. Overgrazing by domesticated animals and farming play a major role in natural forest regeneration. Free-range cattle in the forestland would eliminate seedlings, which would potentially regenerate the forest.

**26**

forests [5].

*5.2.5 Grazing by livestock*

Grazing also accelerates soil erosion [10].

Huge landslide during rainy season in the hilly region (Chittagong and CHT) of Bangladesh is quite common and one of the major reasons for the lack of vegetation cover of the area. Landslides change the hydrological pattern of forest and could be an issue for animal movement [2].

#### **5.3 Indirect threats**

#### *5.3.1 Poor institutional capacity*

The Ministry of Environment and Forests (MoEF) is the sole authority from the government side to implement and enforce natural resource-related activities and laws. The Bangladesh Forest Department and Department of Environment operates under the MoEF and two major wings to manage natural resources in Bangladesh. However, limitations like poor institutional capacity, lack of logistical and operational support, and insufficient funding and manpower are holding the country behind. Most of the field offices in the peripheral forest range have no vehicles or travel allocations to make necessary field interventions [4].

#### *5.3.2 Lack of coordination among different agencies*

There is lack of coordination in the management of biodiversity and natural resources among different government agencies in Bangladesh. For example, there are overlaps between the jurisdictions of the Bangladesh Forest Department, Department of Environment (DoE), and Ministry of Land (MoL). Coordination gaps or overlaps are also found among different projects and among different donor agencies, especially in high-profile areas like the Sundarbans. Lack of coordination is also observed at the transboundary level, especially between water rights and usage between Bangladesh and neighboring countries that are the upstream sources of water [4].

#### *5.3.3 Policy and information gap*

Information is not widely available in Bangladesh, and with regard to field level baseline data on natural resources, there is no single place to get everything. Aside from some modest university efforts, there is a dire lack of scientific data on forest, wetland, and aquatic species. This information is crucial for effective management of natural resources and biodiversity of the country. There are no long-term monitoring efforts to evaluate any changes in species occurrence, abundance, and distribution in Bangladesh [4]. Bangladesh managed to have a number of sound environmental policies, but that is not enough, and there are many gaps. For example, donor-initiated conservation projects are not sustained after the funding tenure is over. The government either does not have their interest or no self-funding capability to continue the project initiated by a donor agency [32].

#### *5.3.4 Lack of enforcement*

Environmental crime is not treated as seriously as other types of crime either by the local communities or by the law enforcement agencies. Although there are laws related to natural resources in Bangladesh, enforcement of these laws is very poor. Poachers are often politically connected and often are protected by their leaders or contractors [4]. Even when a case makes it into the court, there are no incentives (monitory or logistic) for the forest officials who are willing to testify before court.

#### *5.3.5 Inadequate and poorly managed protected areas*

Many of the forests in Bangladesh are recently declared as protected areas, but the actual implementation is still in very rudimentary stage (**Figure 2**). The idea of the PA is not very welcomed and well perceived by the local people, and also there is lack of coordination between the stakeholders and the government. Although there are dozens of PAs in the country, many are 500 hectares or less: too small to provide adequate habitat to preserve biodiversity. In addition, protected area system includes only forestland and does not include some of the most critically important wetland habitat of the country.

#### *5.3.6 Corruption*

Corruption is evident at all levels of the government system in Bangladesh where biodiversity and forest conservation are an integral part. It is expected that folks with strong political connections or wealth can circumvent existing laws to obtain individual favors, rights to use protected land, and immunity to environmental crimes [4].

#### *5.3.7 Lack of awareness*

Most country people are not properly aware of the importance of maintaining a healthy biodiversity and its conservation. Being a developing country, Bangladesh is fighting with poverty, high population density, and lack of education. Most local stakeholders have no idea about the existing laws of the land, especially with regard to environmental crimes [32].

#### *5.3.8 Climate and biophysical changes*

Climate change is being recognized as a global crisis threatening any forms of life on the face of earth. The biophysical changes in the environment have an underlying effect on the present and future biodiversity in Bangladesh [19]. Some of these biophysical factors are changes in temperature and precipitation pattern, sea level rise, frequent natural disasters, increase of salinity in the southern coast, drastic changes in upstream water flow, high sedimentation in inland water, etc. [38].

#### *5.3.9 Alternate income and recent human migration*

Most people living in and around the forests and protected areas support themselves using forest resources collected either legally or illegally. Bangladesh already has a very high population density, and this problem has been intensified by allowing thousands of outside people settled in by the government in the southeastern part of the country. The presence of large refugee camps of Rohingya people from Myanmar in Teknaf Wildlife Sanctuary has already been identified as a major threat for the biodiversity of the region. With no other income options, these Rohingya people are engaged in unsustainable practices in forest resources along the coast. This problem would even go out of control if it is not taken seriously and a solution is chalked out by the governments of the two neighboring countries [2, 13].

#### **6. Conclusion**

The high and rapidly growing population of Bangladesh places a great strain on the natural resources, and PAs are no exception [39]. The situation in Bangladesh

**29**

*Forest Biodiversity and Deforestation in Bangladesh: The Latest Update*

is not atypical; the majority of PAs around the world, not only those in developing countries or the tropics, face a variety of problems [40]. Among many others, shortage of skilled manpower, insufficient logistics, political influence, corruption, and lack of interagency coordination are some of the major reasons for the improper enforcement of law. Review and proper implementation of laws; institutional development; promotion of collaboration among different agencies; habitat protection and restoration; and human-wildlife conflict mitigation are some of the urgently needed factors for the conservation of wildlife and forest in

Although there are lots of limitations, Bangladesh has several laws and policies that still safeguard the existing forest and wildlife species, and we hope that proper implementation of these laws would help to thrive the unique biodiversity and diverse wildlife of the country. Some of the important laws and policies for the conservation of forest and wildlife of Bangladesh are Forest Act, 1927; Wildlife (Conservation and Security) Act, 2012; Environment Conservation Act, 1995; Environment Protection Act, 2000; Climate Change Trust Act, 2010; Biological Diversity Act, 2012; Forest Policy, 1994; Environment Policy, 1992; Wetland Policy, 1998; and Coastal Zone Policy, 2005. The country needs to work hard to implement these laws and eliminate corruption from the government

The Bangladesh Forest Department (BFD) is the primary government agency that deals with forests and forest management and monitoring of biodiversity. The BFD manages PAs, forests, and most biodiversity activities in the field and operates through three management plan divisions. BFD's Wildlife Crime Control Unit (WCCU) was established in 2013 to combat wildlife trafficking and coordinate efforts with other agencies both national and international. Bangladesh Forest Department's capability for preventing wildlife crimes is currently not sufficient, and the country should invest more resources and manpower to the

The BFD manages two large safari parks: Bangabandhu Safari Park, Gazipur, and Dulahazra Safari Park, Cox's Bazar. These facilities maintain animals in near natural conditions and also serve as a repository for animals that have been confiscated through the illegal wildlife trade. The BFD also manages a few botanical gardens around the country, and the National Botanical Garden in Dhaka displays many native and exotic species sells roses and fruit trees to the public, and engages in minor activities in the field; their space limitations prevent the addition of new

The content of this manuscript is the outcome of many field visits and research

activities made by the Wildlife Research Group of the Department of Zoology, Jahangirnagar University, Bangladesh, where the authors actively participated. The authors are thankful to the other group members and the university. The authors are also thankful to the Bangladesh Forest Department for their cooperation. Thanks go to the Arannayk Foundation, Bangladesh, and Wildlife Rescue Center of the Department of Zoology, Jahangirnagar University, for providing valuable references. The first author would like to thank Delta State University for its cooperation

*DOI: http://dx.doi.org/10.5772/intechopen.86242*

species that may need ex situ conservation.

and support to his research activities in Bangladesh.

**Acknowledgements**

Bangladesh.

system.

agency.

#### *Forest Biodiversity and Deforestation in Bangladesh: The Latest Update DOI: http://dx.doi.org/10.5772/intechopen.86242*

*Forest Degradation Around the World*

wetland habitat of the country.

*5.3.6 Corruption*

*5.3.7 Lack of awareness*

to environmental crimes [32].

*5.3.8 Climate and biophysical changes*

*5.3.9 Alternate income and recent human migration*

*5.3.5 Inadequate and poorly managed protected areas*

Many of the forests in Bangladesh are recently declared as protected areas, but the actual implementation is still in very rudimentary stage (**Figure 2**). The idea of the PA is not very welcomed and well perceived by the local people, and also there is lack of coordination between the stakeholders and the government. Although there are dozens of PAs in the country, many are 500 hectares or less: too small to provide adequate habitat to preserve biodiversity. In addition, protected area system includes only forestland and does not include some of the most critically important

Corruption is evident at all levels of the government system in Bangladesh where biodiversity and forest conservation are an integral part. It is expected that folks with strong political connections or wealth can circumvent existing laws to obtain individual favors, rights to use protected land, and immunity to environmental crimes [4].

Most country people are not properly aware of the importance of maintaining a healthy biodiversity and its conservation. Being a developing country, Bangladesh is fighting with poverty, high population density, and lack of education. Most local stakeholders have no idea about the existing laws of the land, especially with regard

Climate change is being recognized as a global crisis threatening any forms of life on the face of earth. The biophysical changes in the environment have an underlying effect on the present and future biodiversity in Bangladesh [19]. Some of these biophysical factors are changes in temperature and precipitation pattern, sea level rise, frequent natural disasters, increase of salinity in the southern coast, drastic changes in upstream water flow, high sedimentation in inland water, etc. [38].

Most people living in and around the forests and protected areas support themselves using forest resources collected either legally or illegally. Bangladesh already has a very high population density, and this problem has been intensified by allowing thousands of outside people settled in by the government in the southeastern part of the country. The presence of large refugee camps of Rohingya people from Myanmar in Teknaf Wildlife Sanctuary has already been identified as a major threat for the biodiversity of the region. With no other income options, these Rohingya people are engaged in unsustainable practices in forest resources along the coast. This problem would even go out of control if it is not taken seriously and a solution

The high and rapidly growing population of Bangladesh places a great strain on the natural resources, and PAs are no exception [39]. The situation in Bangladesh

is chalked out by the governments of the two neighboring countries [2, 13].

**28**

**6. Conclusion**

is not atypical; the majority of PAs around the world, not only those in developing countries or the tropics, face a variety of problems [40]. Among many others, shortage of skilled manpower, insufficient logistics, political influence, corruption, and lack of interagency coordination are some of the major reasons for the improper enforcement of law. Review and proper implementation of laws; institutional development; promotion of collaboration among different agencies; habitat protection and restoration; and human-wildlife conflict mitigation are some of the urgently needed factors for the conservation of wildlife and forest in Bangladesh.

Although there are lots of limitations, Bangladesh has several laws and policies that still safeguard the existing forest and wildlife species, and we hope that proper implementation of these laws would help to thrive the unique biodiversity and diverse wildlife of the country. Some of the important laws and policies for the conservation of forest and wildlife of Bangladesh are Forest Act, 1927; Wildlife (Conservation and Security) Act, 2012; Environment Conservation Act, 1995; Environment Protection Act, 2000; Climate Change Trust Act, 2010; Biological Diversity Act, 2012; Forest Policy, 1994; Environment Policy, 1992; Wetland Policy, 1998; and Coastal Zone Policy, 2005. The country needs to work hard to implement these laws and eliminate corruption from the government system.

The Bangladesh Forest Department (BFD) is the primary government agency that deals with forests and forest management and monitoring of biodiversity. The BFD manages PAs, forests, and most biodiversity activities in the field and operates through three management plan divisions. BFD's Wildlife Crime Control Unit (WCCU) was established in 2013 to combat wildlife trafficking and coordinate efforts with other agencies both national and international. Bangladesh Forest Department's capability for preventing wildlife crimes is currently not sufficient, and the country should invest more resources and manpower to the agency.

The BFD manages two large safari parks: Bangabandhu Safari Park, Gazipur, and Dulahazra Safari Park, Cox's Bazar. These facilities maintain animals in near natural conditions and also serve as a repository for animals that have been confiscated through the illegal wildlife trade. The BFD also manages a few botanical gardens around the country, and the National Botanical Garden in Dhaka displays many native and exotic species sells roses and fruit trees to the public, and engages in minor activities in the field; their space limitations prevent the addition of new species that may need ex situ conservation.


*5.6. Identification of Prospective EFMs in the Chilled Water Air-Conditioning System*

The analysis of the different characteristics explains the existence of two operative clusters in the system as shown in Figure 9. Cluster I, the first operation profile, comprises working days and outdoor temperatures over 10 ◦C, where the cooling demand increases and no free-cooling option is available. Cluster II, the second operation profile covers working days below 10 ◦C, where the cooling demand is relatively reduced and a considerable part of the cooling demand is supplied by CHWFC-1. Additionally, Cluster II also covers non-working days, where there a base cooling demand, mainly for the data center. This was inferred from an analysis of the days in a calendar year on which each of the determined operative clusters will be active.

The analysis of the chilled water system using a cross-analysis matrix based on Tables 2 and 3 and evaluating each crucial characteristic as either positive or negative showed the availability of two different EFMs in the analyzed system:

The availability of both prospective EFM was validated with the energy managers in the facility. Due to expected high investment costs of the dedicated energy storage, this EFM was deemed unattractive.


Introductory Chapter: Biomechanics

*Hadi Mohammadi*

### **1. Introduction**

Biomechanics or biomechanical engineering is the application of mechanical engineering and its concepts and principles in biological systems, living tissues/ organs, and medical devices. Mechanical properties of tissues can be characterized as anisotropy, hyperelasticity, viscoelasticity, viscoplasticity, preconditioning performance, and the existence of residual stresses [1]. Most experiments on the mechanical characterization of tissues are based on the laboratory work. Often, samples are removed from cadavers or animals and are cut in order to be tested which are either fresh or after storage. Testing machines are often based on electromechanical or hydraulic systems which are often performed in living animals or patients. Mathematical interpretation of data is often considered an important part of tissue mechanics such as 3D modeling of stress-strain behavior. Modeling may be either phenomenological, which is to some extent seeking to define behavior using model systems that do not reference structure, or plainly based on information of tissue construction. Phenomenological models are often based on linear or quasilinear viscoelastic theory. Constitutive equations, mostly those based on improvement of strain energy density functions, are often as a means to explaining tissue behavior under random loading.

Tissue mechanics or tissue biomechanics is the field of endeavor that seeks to understand and describe the correlations between structure, composition, and mechanical functionality in a variety of tissues such as connective tissues, cardiovascular tissue, epithelial tissues, etc., in the human body [2]. Much of the research work has been done in the connective tissues of the body, such as the bone, tendons, cartilage, arteries, and skin, where mechanical demands are greatest; however, all tissues have mechanical features of interest. An interesting area of research could be made around the (1) use of structural anatomy as a means to understanding natural design, (2) mechanical engineering analysis of structures based on continuum mechanics, and (3) materials science study of detailed links between structure and function. As all natural tissues are composite materials, understanding their mechanical function requires study of the mechanical properties and architectural arrangement of the individual structural components, particularly strong, stiff collagen fibers; the physiological rubber elastin; hydroxyapatite mineral; and proteoglycan sol/gels. The mechanical features of tissues include marked anisotropy, nonlinear stress-strain relations, viscoelasticity, preconditioning behavior, and the presence of residual stresses. Most studies of the mechanical behavior of tissues have been carried out in the laboratory, with samples removed from cadavers or animals, cut or machined to shape, and tested either fresh or after storage. Commercial testing machines based on electromechanical or hydraulic systems are

widely used, as are custom-built apparatus. Testing is also carried out in living animals or patients. In either case, determination of sample geometry or deformations is difficult. Mathematical description of data is an important part of tissue mechanics, as is modeling of 3D stress-strain behavior. Soft tissues require the use of large deformation (finite) elasticity equations. Modeling may either be phenomenological (seeking to describe behavior using model systems that do not reference structure) or may be explicitly based on knowledge of tissue architecture. Phenomenological models have often been based on linear or quasi-linear viscoelastic theory derived from previous work on polymer materials. Constitutive equations, particularly those based on the development of strain energy density functions, have been widely used as a means to describing tissue behavior under arbitrary loading. In a complementary development, finite element analysis has found wide use for analysis of complex structures. I believe tissue mechanics is a tool both for (1) the study of natural structures in health and disease and (2) technological application, which, in recent years, has included the design of surgical replacements and surgical technique and evaluation and design of tissue engineered replacements and analysis/prevention of injuries. Native and functioning tissues display an exciting and dynamic response to mechanical loading. In fact, living tissues are capable of adapting to the micromechanical environment surrounding them which may be characterized by changes in their composition and structure due to their external conditions. Following this concept, tissue differentiation and profanation are good examples in which they are highly dependent and significantly affected by on their micromechanical environment. A quantifiable understanding of these concepts, by the means of experimentation and/or computational modeling, is of fundamental significance for many applications in the area of biomechanics or biomechanical engineering such as tissue and cell damage due to continued loading (e.g., decubitus), the usage of suitable biomaterials in the design of prostheses (e.g., intervertebral disc or in small size blood vessel, i.e., coronary arteries), and heart valve tissue engineering [1].

As of the future research directions, developing computational multiscale models to study the micromechanical loadings on discrete cells in an engineered tissue such as cartilage tissue or heart valve leaflet tissue is of particular importance. This is because these models will help understand the process by which normal living cells detect and realize mechanical loadings such as shear forces or tensile strains and convert them into a multiple of chemical events in tissues at multiscale levels that trigger and affect the cellular function in health and disease [3, 4]. Living cells vigorously detect, realize, and process micromechanical signals surrounding them, and all their motility, differentiation, and growth are significantly affected by them. It is of particular importance to understand the micromechanical language between the extracellular matrix (ECM) and cells embedded in it and the fundamental mechanisms of this mechanical communication simply because an abnormality in the mechanical properties of the ECM may lead to numerous diseases, such as fibrosis and cancer. Furthermore, ECM mechanics plays a major role when stem cell differentiation is programmed for organ-on-chip applications. Mechanotransduction is a developing multidisciplinary area that embraces cell and developmental biology, biomaterials, biochemistry, biomedical engineering, and medical biophysics [5, 6]. The following topics are a few applications of biomechanics in order to further understand the mechanobiology associated with tissues in health and disease.

### **2. Spine biomechanics**

To understand the motion of the spine and how it supports movement, we must first understand each component and the overall structure of the spine. The spine

**5**

*Introductory Chapter: Biomechanics*

*DOI: http://dx.doi.org/10.5772/intechopen.82130*

**3. Articular cartilage biomechanics**

serves as a structural column providing the human body physical durability and protection. There are 32–34 total bones in the spine, divided into 5 regions: 7 vertebrae in the cervical region, 12 in the thoracic region, 5 in the lumbar region, 5 in the sacral region, and 3–5 in the coccygeal region. In between these spinal bones, there are 23 discs. The bones and discs, in combination with muscles and ligaments, allow the lumbar, thoracic, and cervical spine, different degrees of mobility. This is measured through rotational, side to side, and front to back bending. As mobile humans, it is important to realize the impact of certain activities on the spine, in order to avoid injuries and spinal conditions. Looking at the spine as a purely mechanical system, solutions can be identified using engineering principles. By making use of medical professionals' expertise in surgical procedures and the human body and engineers expertise in mechanical systems and hardware, spinal disorders can be treated. The motion of the spine is very complex, and in order to fully understand the biomechanics of this system, the components, motion, force transmission, conditions, and treatment of the spine must be examined. Understanding the motion of the spine and how it supports movement eases the understanding of each component and the overall structure of the spine. The spine serves as a structural column providing the human body physical durability and protection. The bones and discs, in combination with muscles and ligaments, allow the lumbar, thoracic, and cervical spine to move with different degrees of mobility. This is measured through rotational and lateral bending and flexion/extension. As discussed the motion of the spine is complex. By fully understanding the biomechanics of the spine as a mechanical system, the components, motion, force transmission, and conditions of the spine can be harnessed to develop new technologies in vibration reduction,

sports performance, and new methods and practices for spinal surgery.

Cartilage is an essential component of the human body. It plays multiple roles throughout the body, and without it our bodies would not have the ability to respond to the demanding nature of our everyday lives. Cartilage is the basis of skeletal growth; it transmits and cushions demanding loads throughout brittle bone structures. Also, it gives elasticity and shape to surrounding tissues, all this while being an avascular tissue. The complexity of cartilage's biomechanical behavior makes cartilage a demanding field of research within the biomedical engineering industry. There is ample information in the literature on the three different types of cartilage: hyaline, fibro, and elastic cartilage. Studies of the composition of articular cartilage concluded that the ECM is made up of collagen, proteoglycans, chondrocytes, and water. Collagen is the main structure in the extracellular space, while proteoglycans are heavily glycosylated proteins with a core protein with one or more covalently attached sugar chains. Chondrocytes are the single existing cell within the articular cartilage and are highly specialized and metabolically active while water is the most abundant component contributing to approximately 80% of the wet weight. Further research into the structure of articular cartilage (AC) found four distinct zones, including superficial, middle, deep, and calcified; all of which have distinct differences in composition. Within these four zones, three regions are present referenced as the territorial, pericellular, and interterritorial region. Initiating signal transduction throughout the loaded cartilage between chondrocytes and the ECM is controlled by the territorial region, which also surrounds the pericellular region. Bundles of large collagen fibers that are randomly oriented and have varying proteoglycans define the interterritorial region. Articular cartilage was found to be biphasic and anisotropic giving it distinctly different tensile and compressive

### *Introductory Chapter: Biomechanics DOI: http://dx.doi.org/10.5772/intechopen.82130*

*Biomechanics*

widely used, as are custom-built apparatus. Testing is also carried out in living animals or patients. In either case, determination of sample geometry or deformations is difficult. Mathematical description of data is an important part of tissue mechanics, as is modeling of 3D stress-strain behavior. Soft tissues require the use of large deformation (finite) elasticity equations. Modeling may either be phenomenological (seeking to describe behavior using model systems that do not reference structure) or may be explicitly based on knowledge of tissue architecture. Phenomenological models have often been based on linear or quasi-linear viscoelastic theory derived from previous work on polymer materials. Constitutive equations, particularly those based on the development of strain energy density functions, have been widely used as a means to describing tissue behavior under arbitrary loading. In a complementary development, finite element analysis has found wide use for analysis of complex structures. I believe tissue mechanics is a tool both for (1) the study of natural structures in health and disease and (2) technological application, which, in recent years, has included the design of surgical replacements and surgical technique and evaluation and design of tissue engineered replacements and analysis/prevention of injuries. Native and functioning tissues display an exciting and dynamic response to mechanical loading. In fact, living tissues are capable of adapting to the micromechanical environment surrounding them which may be characterized by changes in their composition and structure due to their external conditions. Following this concept, tissue differentiation and profanation are good examples in which they are highly dependent and significantly affected by on their micromechanical environment. A quantifiable understanding of these concepts, by the means of experimentation and/or computational modeling, is of fundamental significance for many applications in the area of biomechanics or biomechanical engineering such as tissue and cell damage due to continued loading (e.g., decubitus), the usage of suitable biomaterials in the design of prostheses (e.g., intervertebral disc or in small size blood vessel, i.e., coronary arteries), and heart valve tissue engineering [1].

As of the future research directions, developing computational multiscale models to study the micromechanical loadings on discrete cells in an engineered tissue such as cartilage tissue or heart valve leaflet tissue is of particular importance. This is because these models will help understand the process by which normal living cells detect and realize mechanical loadings such as shear forces or tensile strains and convert them into a multiple of chemical events in tissues at multiscale levels that trigger and affect the cellular function in health and disease [3, 4]. Living cells vigorously detect, realize, and process micromechanical signals surrounding them, and all their motility, differentiation, and growth are significantly affected by them. It is of particular importance to understand the micromechanical language between the extracellular matrix (ECM) and cells embedded in it and the fundamental mechanisms of this mechanical communication simply because an abnormality in the mechanical properties of the ECM may lead to numerous diseases, such as fibrosis and cancer. Furthermore, ECM mechanics plays a major role when stem cell differentiation is programmed for organ-on-chip applications. Mechanotransduction is a developing multidisciplinary area that embraces cell and developmental biology, biomaterials,

biochemistry, biomedical engineering, and medical biophysics [5, 6].

stand the mechanobiology associated with tissues in health and disease.

The following topics are a few applications of biomechanics in order to further under-

To understand the motion of the spine and how it supports movement, we must first understand each component and the overall structure of the spine. The spine

**4**

**2. Spine biomechanics**

serves as a structural column providing the human body physical durability and protection. There are 32–34 total bones in the spine, divided into 5 regions: 7 vertebrae in the cervical region, 12 in the thoracic region, 5 in the lumbar region, 5 in the sacral region, and 3–5 in the coccygeal region. In between these spinal bones, there are 23 discs. The bones and discs, in combination with muscles and ligaments, allow the lumbar, thoracic, and cervical spine, different degrees of mobility. This is measured through rotational, side to side, and front to back bending. As mobile humans, it is important to realize the impact of certain activities on the spine, in order to avoid injuries and spinal conditions. Looking at the spine as a purely mechanical system, solutions can be identified using engineering principles. By making use of medical professionals' expertise in surgical procedures and the human body and engineers expertise in mechanical systems and hardware, spinal disorders can be treated. The motion of the spine is very complex, and in order to fully understand the biomechanics of this system, the components, motion, force transmission, conditions, and treatment of the spine must be examined. Understanding the motion of the spine and how it supports movement eases the understanding of each component and the overall structure of the spine. The spine serves as a structural column providing the human body physical durability and protection. The bones and discs, in combination with muscles and ligaments, allow the lumbar, thoracic, and cervical spine to move with different degrees of mobility. This is measured through rotational and lateral bending and flexion/extension. As discussed the motion of the spine is complex. By fully understanding the biomechanics of the spine as a mechanical system, the components, motion, force transmission, and conditions of the spine can be harnessed to develop new technologies in vibration reduction, sports performance, and new methods and practices for spinal surgery.

### **3. Articular cartilage biomechanics**

Cartilage is an essential component of the human body. It plays multiple roles throughout the body, and without it our bodies would not have the ability to respond to the demanding nature of our everyday lives. Cartilage is the basis of skeletal growth; it transmits and cushions demanding loads throughout brittle bone structures. Also, it gives elasticity and shape to surrounding tissues, all this while being an avascular tissue. The complexity of cartilage's biomechanical behavior makes cartilage a demanding field of research within the biomedical engineering industry. There is ample information in the literature on the three different types of cartilage: hyaline, fibro, and elastic cartilage. Studies of the composition of articular cartilage concluded that the ECM is made up of collagen, proteoglycans, chondrocytes, and water. Collagen is the main structure in the extracellular space, while proteoglycans are heavily glycosylated proteins with a core protein with one or more covalently attached sugar chains. Chondrocytes are the single existing cell within the articular cartilage and are highly specialized and metabolically active while water is the most abundant component contributing to approximately 80% of the wet weight. Further research into the structure of articular cartilage (AC) found four distinct zones, including superficial, middle, deep, and calcified; all of which have distinct differences in composition. Within these four zones, three regions are present referenced as the territorial, pericellular, and interterritorial region. Initiating signal transduction throughout the loaded cartilage between chondrocytes and the ECM is controlled by the territorial region, which also surrounds the pericellular region. Bundles of large collagen fibers that are randomly oriented and have varying proteoglycans define the interterritorial region. Articular cartilage was found to be biphasic and anisotropic giving it distinctly different tensile and compressive

properties. The viscoelastic nature of AC is also governed by its liquid and solid ECM phases leading to creep and stress relaxation behavior. Boundary layer lubrication transitioning to fluid film lubrication yields the very low coefficient of friction required to prevent cartilage deterioration between joints. Mechanical materials available today do not present the combination of elasticity and strength articular cartilage possesses making medical replacements less than ideal.

Finally, medical conditions and treatments were covered including osteoarthritis, microfracture, osteotomy, arthroplasty, stem cell therapy, and hydrogels. Current treatments do provide some alleviation of pain and discomfort; however, high costs and unwanted growth of fibro instead of hyaline cartilage leave room for further improvement in this area of the biomedical industry.

### **4. Biomechanics of atherosclerosis**

Currently, atherosclerosis is the leading cause of deaths in the developed world. Due to the nature of this disease and how prevalent it is in our modern society, it is important for all to understand how this disease manifests and is detected, as well as how it can be prevented. Atherosclerosis is a silent killer and contributes to many deaths throughout the world every year. It develops over a long period of time due to a buildup of LDL on the arterial wall before the body contains it with a mesh of collagen and elastin fibers called a fibrous cap. Based on the volume that the soft plaque occupies and the thickness of the fibrous cap itself, a person can live for years without that plaque being a danger to their health. The issue arises when the necrotic core takes up 40% or more of the volume of the plaque or if the fibrous cap is less than 65 μm thick. If either of these criteria are met, the plaque is at risk of rupturing and creating a thrombus that will kill the victim. Even without rupturing, the stiffening of the arterial wall leads to physical changes in the body's function. These changes include increased shear stress in the blood vessels, changes in systolic and diastolic blood pressures, and increased pressure fluctuations in the arteries. Thankfully in our modern age, atherosclerotic plaques can be detected and treated through a variety of methods. Each method has its advantages and disadvantages. Certain procedures excel at identifying atherosclerosis in certain arteries but struggle in other arteries. For these reasons, multiple procedures can be used together to allow a better picture of the health of a patient's arteries. It is becoming more common to use noninvasive procedures as they become more advanced. In many cases, they are just as effective as invasive procedures at detecting atherosclerosis. As atherosclerosis becomes more common, research on the disease is expanding. Every year, doctors are becoming more equipped to handle atherosclerosis.

### **5. Knee joint biomechanics**

During everyday activities like walking and climbing up stairs, the knee experiences 2.7–4.9 times the body weight. It is a wonder how the knee can withstand so much weight over such a long period of time. Millions of years of evolution and adaptation can be found in the knee as it seems to be built for exactly what humans need it to do. The knee is meant to bear load and help the body move at the same time, and it does just that. The meniscus not only reduces the friction between our femur and tibia but also reduces the stress felt on the tibia. Humans often stand for longer periods of time, and the knee has a mechanism to reduce the amount of force needed to stay standing upright. More recently in the field of biomedical engineering, procedures are being developed to fix the issues caused by trauma or simply by degradation.

**7**

*Introductory Chapter: Biomechanics*

**6. Muscle biomechanics**

**7. Vascular grafts**

*DOI: http://dx.doi.org/10.5772/intechopen.82130*

Muscle is a complex tissue that is involved in many processes and systems essential to human life. They are used for balance, stability, movement, organ function, lifting objects, and many other things. This tissue needs to be analyzed from the smallest unit all the way up to the macroscale of its involvement in complex functions. Furthermore, certain engineering applications and considerations needs to be covered. Through analysis of fundamental structures and functions, the role of the muscle in the body needs to be explored, and its relevance to human life needs to be discussed. Muscle is a contractile tissue within the body responsible for internal and external locomotion and posture. There are different types of muscle tissue, composed of different types of fibers. Contractions are stimulated by the nervous system and have a specific need for energy depending on their environment. In addition, adaptations to the structure and function will arise when exposed to stimuli such as exercise. Muscle is a complex, versatile tissue which provides humans with the ability to execute a variety of tasks. Both muscles as a complex functional group and single muscle fibers as an individual functional unit have been discussed. The interactions of muscle tissue with the rest of the body perform many different functions that need to be carried out simply and effectively. From the contraction of single muscle fibers all the way to the entire muscle groups working together to complete a movement, the structure and fundamental properties of muscles work

cooperatively to fulfill different functions and needs of the body.

Proper circulation of blood throughout the body is extremely crucial to a long and healthy life. Any infliction that inhibits the normal flow of blood through the vast network of blood vessels poses an extreme risk to patients and can cause numerous potentially fatal conditions depending on their location. Vascular grafts are a surgical method utilized to redirect blood flow from one area to another whether to bypass a clogged or narrowed blood vessel or provide an easy access point for other procedures such as blood dialysis. It is an unfortunate truth that, in their current state, synthetic grafts are not a long-term solution to vascular stenosis and provide only small extensions on expected life spans. With the current state of undesirable compliance mismatch that exists between them and the vessels that they are grafted too, it is clear that there is a lot of room for improvement. Future research on the use of multicomponent synthetic grafts in which multiple materials are used together to better mimic the elastin and collagen mechanical properties of natural arteries and veins has a potential for improving the compliance of synthetic grafts, which ultimately leads to improved patency over time.  The future of biomedical engineering lays in the replication of human tissues through tissue engineering. The only way to correctly mimic the compliance of a human blood vessel is to use a form of tissue engineering. Many improvements have been made already, with some very promising results as seen in the hybrid scaffold methods as well as the decellularized matrices. It is important to note that the highest potential lies in the assembly processes. These are the processes that will allow for any mechanical property and shape to be designed exactly. The only limiting factor being the excessive amount of time required in order to manufacture these grafts. Finally the research toward sutures and the anastomotic site is also a very key area. With the hypercompliant zone being so detrimental, it is very important to consider alternate forms of sutures to combat the high compliance mismatch of those areas.

### **6. Muscle biomechanics**

*Biomechanics*

properties. The viscoelastic nature of AC is also governed by its liquid and solid ECM phases leading to creep and stress relaxation behavior. Boundary layer lubrication transitioning to fluid film lubrication yields the very low coefficient of friction required to prevent cartilage deterioration between joints. Mechanical materials available today do not present the combination of elasticity and strength articular

Finally, medical conditions and treatments were covered including osteoarthritis, microfracture, osteotomy, arthroplasty, stem cell therapy, and hydrogels. Current treatments do provide some alleviation of pain and discomfort; however, high costs and unwanted growth of fibro instead of hyaline cartilage leave room for

Currently, atherosclerosis is the leading cause of deaths in the developed world. Due to the nature of this disease and how prevalent it is in our modern society, it is important for all to understand how this disease manifests and is detected, as well as how it can be prevented. Atherosclerosis is a silent killer and contributes to many deaths throughout the world every year. It develops over a long period of time due to a buildup of LDL on the arterial wall before the body contains it with a mesh of collagen and elastin fibers called a fibrous cap. Based on the volume that the soft plaque occupies and the thickness of the fibrous cap itself, a person can live for years without that plaque being a danger to their health. The issue arises when the necrotic core takes up 40% or more of the volume of the plaque or if the fibrous cap is less than 65 μm thick. If either of these criteria are met, the plaque is at risk of rupturing and creating a thrombus that will kill the victim. Even without rupturing, the stiffening of the arterial wall leads to physical changes in the body's function. These changes include increased shear stress in the blood vessels, changes in systolic and diastolic blood pressures, and increased pressure fluctuations in the arteries. Thankfully in our modern age, atherosclerotic plaques can be detected and treated through a variety of methods. Each method has its advantages and disadvantages. Certain procedures excel at identifying atherosclerosis in certain arteries but struggle in other arteries. For these reasons, multiple procedures can be used together to allow a better picture of the health of a patient's arteries. It is becoming more common to use noninvasive procedures as they become more advanced. In many cases, they are just as effective as invasive procedures at detecting atherosclerosis. As atherosclerosis becomes more common, research on the disease is expanding. Every year, doctors are becoming more equipped to handle atherosclerosis.

During everyday activities like walking and climbing up stairs, the knee experiences 2.7–4.9 times the body weight. It is a wonder how the knee can withstand so much weight over such a long period of time. Millions of years of evolution and adaptation can be found in the knee as it seems to be built for exactly what humans need it to do. The knee is meant to bear load and help the body move at the same time, and it does just that. The meniscus not only reduces the friction between our femur and tibia but also reduces the stress felt on the tibia. Humans often stand for longer periods of time, and the knee has a mechanism to reduce the amount of force needed to stay standing upright. More recently in the field of biomedical engineering, procedures are

being developed to fix the issues caused by trauma or simply by degradation.

cartilage possesses making medical replacements less than ideal.

further improvement in this area of the biomedical industry.

**4. Biomechanics of atherosclerosis**

**5. Knee joint biomechanics**

**6**

Muscle is a complex tissue that is involved in many processes and systems essential to human life. They are used for balance, stability, movement, organ function, lifting objects, and many other things. This tissue needs to be analyzed from the smallest unit all the way up to the macroscale of its involvement in complex functions. Furthermore, certain engineering applications and considerations needs to be covered. Through analysis of fundamental structures and functions, the role of the muscle in the body needs to be explored, and its relevance to human life needs to be discussed. Muscle is a contractile tissue within the body responsible for internal and external locomotion and posture. There are different types of muscle tissue, composed of different types of fibers. Contractions are stimulated by the nervous system and have a specific need for energy depending on their environment. In addition, adaptations to the structure and function will arise when exposed to stimuli such as exercise. Muscle is a complex, versatile tissue which provides humans with the ability to execute a variety of tasks. Both muscles as a complex functional group and single muscle fibers as an individual functional unit have been discussed. The interactions of muscle tissue with the rest of the body perform many different functions that need to be carried out simply and effectively. From the contraction of single muscle fibers all the way to the entire muscle groups working together to complete a movement, the structure and fundamental properties of muscles work cooperatively to fulfill different functions and needs of the body.

### **7. Vascular grafts**

Proper circulation of blood throughout the body is extremely crucial to a long and healthy life. Any infliction that inhibits the normal flow of blood through the vast network of blood vessels poses an extreme risk to patients and can cause numerous potentially fatal conditions depending on their location. Vascular grafts are a surgical method utilized to redirect blood flow from one area to another whether to bypass a clogged or narrowed blood vessel or provide an easy access point for other procedures such as blood dialysis. It is an unfortunate truth that, in their current state, synthetic grafts are not a long-term solution to vascular stenosis and provide only small extensions on expected life spans. With the current state of undesirable compliance mismatch that exists between them and the vessels that they are grafted too, it is clear that there is a lot of room for improvement. Future research on the use of multicomponent synthetic grafts in which multiple materials are used together to better mimic the elastin and collagen mechanical properties of natural arteries and veins has a potential for improving the compliance of synthetic grafts, which ultimately leads to improved patency over time.  The future of biomedical engineering lays in the replication of human tissues through tissue engineering. The only way to correctly mimic the compliance of a human blood vessel is to use a form of tissue engineering. Many improvements have been made already, with some very promising results as seen in the hybrid scaffold methods as well as the decellularized matrices. It is important to note that the highest potential lies in the assembly processes. These are the processes that will allow for any mechanical property and shape to be designed exactly. The only limiting factor being the excessive amount of time required in order to manufacture these grafts. Finally the research toward sutures and the anastomotic site is also a very key area. With the hypercompliant zone being so detrimental, it is very important to consider alternate forms of sutures to combat the high compliance mismatch of those areas.

In the future it can be said that a form of biocompatible glue or laser or even a combination of both may be the best choice of suture. In order for this to happen a lot of work needs to be done in those areas in order to formulate techniques in which the negatives previously mentioned are mitigated.

### **8. Transcatheter heart valves**

Severe aortic stenosis is the calcification of the aortic heart valve that affects 3% of the world's population over the age of 75. This disease may have a variety of causes, such as age, gender, hyperlipidemia, rheumatic fever, hypertension, heart infection, abnormal stresses, and congenital abnormalities. Due to the extremely invasive nature of open-heart surgery, the mortality rate for older patients is very high, and until 1992 these patients would have had to take the risk of open-heart surgery or have no treatment and left to endure cardiac failure. Henning Rud Andersen invented an alternative surgery to replace the native aortic valve, known as a transcatheter aortic valve replacement (TAVR), also known as a percutaneous aortic valve replacement (PAVR). This surgery is done by using various catheters and medical imaging machines to allow for a replacement valve to be directed up an artery to the diseased native aortic valve. The catheter is most commonly inserted into the iliac artery or femoral artery, but there are other methods surgeons use based on their patient. A sheath is placed in an incision located near the groin to aid in inserting various surgical tools and the replacement valve into the artery. A flexible guide wire is transported to the valve to guide the surgical tools and new valve to the native valve. The native valve is then crushed using a procedure called aortic balloon valvuloplasty. Doctors will often use a method called fast pacing during an aortic balloon valvuloplasty to reduce the pulsatile aortic flow by increasing the heart rate to approximately 200 beats/min or greater. After crushing the native valve, a new bioprosthetic aortic valve is set in place using either a balloon expandable PAV or a self-expanding PAV. Doctors use various medical imaging techniques such as fluoroscopy, aortography, and echocardiography in the procedure to monitor flow characteristics and valve deployment location. This procedure is far less invasive than open-heart surgery and gives a safe alternative for older patients or patients characterized with a high mortality rate to receive a new aortic valve. The percutaneous valve is still a growing technology and is still in its optimizing stage. Issues with the valve include thrombosis (blood clotting), valve migration (due to the valve not being sutured in), stent malposition (due to physician error or valve migration), coronary obstruction, and issues with the catheter-based delivery and valve durability. Research into correcting these issues is essential for further optimizing the current models of the percutaneous heart valve and for minimizing negative inoperative and postoperative implications.

**9**

**Author details**

Hadi Mohammadi

Columbia, Kelowna, BC, Canada

provided the original work is properly cited.

\*Address all correspondence to<EMAIL_ADDRESS>
*Introductory Chapter: Biomechanics*

*DOI: http://dx.doi.org/10.5772/intechopen.82130*

© 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

Heart Valve Performance Laboratory, School of Engineering, University of British

*Introductory Chapter: Biomechanics DOI: http://dx.doi.org/10.5772/intechopen.82130*

*Biomechanics*

In the future it can be said that a form of biocompatible glue or laser or even a combination of both may be the best choice of suture. In order for this to happen a lot of work needs to be done in those areas in order to formulate techniques in which

Severe aortic stenosis is the calcification of the aortic heart valve that affects 3% of the world's population over the age of 75. This disease may have a variety of causes, such as age, gender, hyperlipidemia, rheumatic fever, hypertension, heart infection, abnormal stresses, and congenital abnormalities. Due to the extremely invasive nature of open-heart surgery, the mortality rate for older patients is very high, and until 1992 these patients would have had to take the risk of open-heart surgery or have no treatment and left to endure cardiac failure. Henning Rud Andersen invented an alternative surgery to replace the native aortic valve, known as a transcatheter aortic valve replacement (TAVR), also known as a percutaneous aortic valve replacement (PAVR). This surgery is done by using various catheters and medical imaging machines to allow for a replacement valve to be directed up an artery to the diseased native aortic valve. The catheter is most commonly inserted into the iliac artery or femoral artery, but there are other methods surgeons use based on their patient. A sheath is placed in an incision located near the groin to aid in inserting various surgical tools and the replacement valve into the artery. A flexible guide wire is transported to the valve to guide the surgical tools and new valve to the native valve. The native valve is then crushed using a procedure called aortic balloon valvuloplasty. Doctors will often use a method called fast pacing during an aortic balloon valvuloplasty to reduce the pulsatile aortic flow by increasing the heart rate to approximately 200 beats/min or greater. After crushing the native valve, a new bioprosthetic aortic valve is set in place using either a balloon expandable PAV or a self-expanding PAV. Doctors use various medical imaging techniques such as fluoroscopy, aortography, and echocardiography in the procedure to monitor flow characteristics and valve deployment location. This procedure is far less invasive than open-heart surgery and gives a safe alternative for older patients or patients characterized with a high mortality rate to receive a new aortic valve. The percutaneous valve is still a growing technology and is still in its optimizing stage. Issues with the valve include thrombosis (blood clotting), valve migration (due to the valve not being sutured in), stent malposition (due to physician error or valve migration), coronary obstruction, and issues with the catheter-based delivery and valve durability. Research into correcting these issues is essential for further optimizing the current models of the percutaneous heart valve and for minimizing

the negatives previously mentioned are mitigated.

negative inoperative and postoperative implications.

**8. Transcatheter heart valves**

**8**

### **Author details**

Hadi Mohammadi Heart Valve Performance Laboratory, School of Engineering, University of British Columbia, Kelowna, BC, Canada

\*Address all correspondence to<EMAIL_ADDRESS>
© 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

### **References**

[1] Mohammadi H, Mequanint K, Herzog W. Computational aspects of mechanical modeling of articular cartilage. IMechE, Part H: Journal of Engineering in Medicine. 2013;**227**(4):402-420

[2] Mohammadi H, Mequanint K, Herzog W. Multiscale modeling of O2 transport in articular cartilage. Biophysical Journal. 2012;**102**(3):592a

[3] Raustin R, Mohammadi H. Towards multiscale modeling of wave propagation in arteries. Journal of Mechanics in Medicine and Biology. 2015;**16**(2):1650027 (1-10)

[4] Mohammadi H, Mequanint K. Prosthetic aortic heart valves: Modeling and design. Medical Engineering & Physics. 2011;**33**(2):131-147

[5] Mohammadi H, Fradet G. Prosthetic aortic heart valves: Review article. Cardiovascular System. 2017;**2**(1). 55p

[6] Haley JP, Mohammadi H, Boughner DR. The effects of hammer pressure on cellular response in a porcine heart valve tissue. Cardiovascular Engineering. 2010;**10**(3):157-162

**11**

Section 2

Hemodynamics and Blood

Section 2


3.4.1. Knee Approach

For suitably training the classifier, each knee-angle signal was split into 20-sample windows (corresponding to 10 ms). A chronological sequence of 40-sample vectors was created, where each vector included the two synchronized 20-sample windows from two knee-angle signals (right and left leg). In details, the first sample of the first 40-sample vector of the sequence was the first sample of the knee angle measured in the right leg; the second sample of the first 40-sample vector was the first sample of the knee angle measured in the left leg.

Then, a specific label was assigned to each 40-sample window as follows: if the value of all the samples of the basographic signal corresponding to the 40-sample vector was 0 (or 1), a global label 0 (or 1) was assigned to the 40-sample vector. 40-sample vectors, including swing-to-stance or stance-to-swing transitions, were discarded. This approach including only knee-angle data to feed the neural network is referred to as 'Knee approach'.


**2. Biofilm formation**

Biofilms are formed on all types of surfaces existing in food plants ranging from plastic, glass, metal, cement, to wood and food products [4]. Usually, biofilms form a monolayer or more often multilayers, in which bacteria may undergo a significant change in physiology with an increased tolerance to environmental stresses [5].

*L. monocytogenes*, the pathogen that proliferates at low temperatures, is able either to form pure culture biofilms or to grow in multispecies biofilms [6]. Prevalent strains in food processing environments have good adhesion ability due to the presence of flagella, pili, and membrane proteins [7]. Composition of biofilms produced by *L. monocytogenes* is different in comparison with that produced by other bacteria. For example, exopolysaccharides like alginate in Pseudomonas or poly-N-acetylglucosamine in *Staphylo-coccus* have not been put into evidence [8].

*Salmonella* spp. express proteinaceous extracellular fibers called curli that are involved in surface and cell-cell contacts and promotion of community behavior and host colonization [9]. Besides curli, different fimbrial adhesins have been identified to have implications in biofilm formation, dependent of serotype. The presence of cellulose in the biofilm matrix contributes to cells' resistance to mechanical forces and improved adhesion to abiotic surfaces [10]. Significant differences between serovars were put into evidence regarding biofilm formation the most persistent in food processing environments being the ones that are capable to form biofilms [11].

Flagella, pili, and membrane proteins are also used by *E. coli* to initiate attachment on inanimate surfaces. Flagella are lost after attachment and bacteria start producing an extracellular polymeric substance (EPS) that provides a better resistance of bacteria to disinfectants as hypochlorite [12]. Similarities in biofilm structure and composition as well as regulatory mechanisms with *Salmonella* spp. have been demonstrated for *E. coli*, mostly in terms of expression of small RNAs leading to a change in bacterial physiology regarding the cell motility and production of curli or EPS [13].

In general terms, different *E. coli* serotypes have been reported to enhance flexibility and adaptability in forming biofilms when exposed to different stresses. For example, *E. coli* seropathotype A isolates associated with human infection, O157:H7 and O157:NM, showed greater ability to form biofilms than those belonging to seropathotype B or C associated with outbreaks and hemolytic-uremic syndrome (HUS) or sporadic HUS cases but no epidemics, respectively [14]. In addition, synergistic interactions are taking place in a fresh-cut produce processing plant in which *E. coli* is interacting with *Burkholderia caryophylli* and *Ralstonia insidiosa* with the formation of mixed biofilms [15].

*C. jejuni*, which is known as an anaerobic bacterium, is able to develop biofilms both in microaerophilic conditions (5% O2 and 10% CO2) and in aerobic conditions (20% O2) [1]. The cells embedded in the biofilm matrix are better protected from oxygen and survive for days in food processing environments [1].

*Pseudomonas* spp. produce high amounts of EPS and have been shown to attach and form biofilms on stainless steel surfaces. They coexist within biofilms with *Listeria, Salmonella*, and other pathogens forming multispecies biofilms, more stable and resistant [6].

*B. cereus* is a cause of biofilm formation on many food contact surfaces such as conveyor belts, stainless steel pipes, and storage tanks [16], but it is also able to

**215**

*Biofilms Formed by Pathogens in Food and Food Processing Environments*

the bacterium to antimicrobials and cleaning procedures.

**3. Genes involved in the biofilm formation**

a specific genetic signal control.

just the bioinformatics analysis.

cells and surface.

form immersed or floating biofilms, and to secrete within the biofilm a vast array of metabolites, surfactants, bacteriocins, enzymes as lipases and proteases affecting the sensorial qualities of foods, and toxins. For floating biofilms, the production of kurstakin, a lipopeptide biosurfactant, that is regulated via quorum sensing (QS)

Within the biofilm, *B. cereus* exists either in vegetative or in sporal form, the spores being highly resistant and adhesive, properties that increase the resistance of

Four mechanisms based on the flagellar motility of *B. cereus* are described as being involved in biofilm formation. The first mechanism is used in static conditions when the bacterium must reach on its own suitable places for biofilm formation [18], at the air-liquid interface. The second one is represented by the creation of channels in the biofilm matrix to facilitate nutrients' access on one hand and penetration of toxic substances on the other hand [19]. The third mechanism refers to motile planktonic bacteria that penetrate the biofilm and increase its biomass [18, 19], while the fourth represents the extension of the biofilm based on the ability of motile bacteria located at the edge of the biofilm to colonize the surroundings [18]. It has been showed that, in its planktonic form, *S. aureus* does not appear resistant to disinfectants, compared to other bacteria, but it may be among the most resistant ones when attached to a surface [20]. It seems that different stress-adaptive responses may enhance biofilm formation, with certain differences in terms of their composition and architecture, especially for the wild-type biofilms colonizing the food and related processing environments. Examples include protein-based sources responsible for the structure of biofilms formed by *S. aureus* of food origin [21] similar to those put into evidence for the coagulase-negative ones. However, other studies demonstrated that simple carbohydrates, such as milk lactose, can modulate the biofilm formation especially by inducing the production of polysaccharide intercellular adhesins [22].

Over time, beside the conditions that favor the biofilm formation in food processing plants**,** the genetic background of biofilm forming microorganisms was also intensively studied. At each step of biofilm development and dispersal, there is

The *L. monocytogenes* pattern of the microarray gene expression was analyzed at different time intervals (4, 12, and 24 h) in order to depict genes' expression at different stages of biofilm formation. The results showed that more than 150 genes were upregulated after 4 h of biofilm formation and a total of 836 genes highlighted a slow increase in expression with time [23]. Although for many bacterial species the genome sequencing allowed the identification of genes that were involved in biofilm synthesis, for *L. monocytogenes*, these genes could not be identified using

In the biofilm formation, the attachment step is a prerequisite in which flagella and type I pili-mediated motilities are critical for the initial interaction between the

In order to find out the roles of the genes and regulatory pathway controlling the biofilm formation, researchers applied one or two genome-wide approaches, like transposon insertion mutagenesis or/and transcriptome analyses. With a transposon mutagenesis library, it was possible to identify 70 *L. monocytogenes* mutants, with Himar1 mariner transposon insertion, which produced less biofilms [24]. From a total of 38 genetic loci identified, 4 of them (**Table 1**) were found to be involved in bacterial motility (*fli*D, *fli*Q, *fla*A, and *mot*A), a required property for initial surface

*DOI: http://dx.doi.org/10.5772/intechopen.90176*

signaling is important [17].

### *Biofilms Formed by Pathogens in Food and Food Processing Environments DOI: http://dx.doi.org/10.5772/intechopen.90176*

*Bacterial Biofilms*

associated with brand damage.

**2. Biofilm formation**

tion of curli or EPS [13].

stable and resistant [6].

the formation of mixed biofilms [15].

of processed foods [3]. When contamination of food products happens, recalls are necessary. These actions present large economic burden to industry and are also

Biofilms are formed on all types of surfaces existing in food plants ranging from plastic, glass, metal, cement, to wood and food products [4]. Usually, biofilms form a monolayer or more often multilayers, in which bacteria may undergo a significant change in physiology with an increased tolerance to environmental stresses [5]. *L. monocytogenes*, the pathogen that proliferates at low temperatures, is able either to form pure culture biofilms or to grow in multispecies biofilms [6].

Prevalent strains in food processing environments have good adhesion ability due to the presence of flagella, pili, and membrane proteins [7]. Composition of biofilms produced by *L. monocytogenes* is different in comparison with that produced by other bacteria. For example, exopolysaccharides like alginate in Pseudomonas or poly-N-acetylglucosamine in *Staphylo-coccus* have not been put into evidence [8]. *Salmonella* spp. express proteinaceous extracellular fibers called curli that are involved in surface and cell-cell contacts and promotion of community behavior and host colonization [9]. Besides curli, different fimbrial adhesins have been identified to have implications in biofilm formation, dependent of serotype. The presence of cellulose in the biofilm matrix contributes to cells' resistance to mechanical forces and improved adhesion to abiotic surfaces [10]. Significant differences between serovars were put into evidence regarding biofilm formation the most persistent in food processing environments being the ones that are capable to form biofilms [11]. Flagella, pili, and membrane proteins are also used by *E. coli* to initiate attachment on inanimate surfaces. Flagella are lost after attachment and bacteria start producing an extracellular polymeric substance (EPS) that provides a better resistance of bacteria to disinfectants as hypochlorite [12]. Similarities in biofilm structure and composition as well as regulatory mechanisms with *Salmonella* spp. have been demonstrated for *E. coli*, mostly in terms of expression of small RNAs leading to a change in bacterial physiology regarding the cell motility and produc-

In general terms, different *E. coli* serotypes have been reported to enhance flexibility and adaptability in forming biofilms when exposed to different stresses. For example, *E. coli* seropathotype A isolates associated with human infection, O157:H7 and O157:NM, showed greater ability to form biofilms than those belonging to seropathotype B or C associated with outbreaks and hemolytic-uremic syndrome (HUS) or sporadic HUS cases but no epidemics, respectively [14]. In addition, synergistic interactions are taking place in a fresh-cut produce processing plant in which *E. coli* is interacting with *Burkholderia caryophylli* and *Ralstonia insidiosa* with

*C. jejuni*, which is known as an anaerobic bacterium, is able to develop biofilms both in microaerophilic conditions (5% O2 and 10% CO2) and in aerobic conditions (20% O2) [1]. The cells embedded in the biofilm matrix are better protected from

*Pseudomonas* spp. produce high amounts of EPS and have been shown to attach and form biofilms on stainless steel surfaces. They coexist within biofilms with *Listeria, Salmonella*, and other pathogens forming multispecies biofilms, more

*B. cereus* is a cause of biofilm formation on many food contact surfaces such as conveyor belts, stainless steel pipes, and storage tanks [16], but it is also able to

oxygen and survive for days in food processing environments [1].

**214**

form immersed or floating biofilms, and to secrete within the biofilm a vast array of metabolites, surfactants, bacteriocins, enzymes as lipases and proteases affecting the sensorial qualities of foods, and toxins. For floating biofilms, the production of kurstakin, a lipopeptide biosurfactant, that is regulated via quorum sensing (QS) signaling is important [17].

Within the biofilm, *B. cereus* exists either in vegetative or in sporal form, the spores being highly resistant and adhesive, properties that increase the resistance of the bacterium to antimicrobials and cleaning procedures.

Four mechanisms based on the flagellar motility of *B. cereus* are described as being involved in biofilm formation. The first mechanism is used in static conditions when the bacterium must reach on its own suitable places for biofilm formation [18], at the air-liquid interface. The second one is represented by the creation of channels in the biofilm matrix to facilitate nutrients' access on one hand and penetration of toxic substances on the other hand [19]. The third mechanism refers to motile planktonic bacteria that penetrate the biofilm and increase its biomass [18, 19], while the fourth represents the extension of the biofilm based on the ability of motile bacteria located at the edge of the biofilm to colonize the surroundings [18].

It has been showed that, in its planktonic form, *S. aureus* does not appear resistant to disinfectants, compared to other bacteria, but it may be among the most resistant ones when attached to a surface [20]. It seems that different stress-adaptive responses may enhance biofilm formation, with certain differences in terms of their composition and architecture, especially for the wild-type biofilms colonizing the food and related processing environments. Examples include protein-based sources responsible for the structure of biofilms formed by *S. aureus* of food origin [21] similar to those put into evidence for the coagulase-negative ones. However, other studies demonstrated that simple carbohydrates, such as milk lactose, can modulate the biofilm formation especially by inducing the production of polysaccharide intercellular adhesins [22].


We are IntechOpen, the world's leading publisher of Open Access books Built by scientists, for scientists

4,400+

Open access books available

117,000+

International authors and editors

130M+

Downloads

Our authors are among the

Top 1%

most cited scientists

12.2%

Contributors from top 500 universities

Selection of our books indexed in the Book Citation Index in Web of Science™ Core Collection (BKCI)


**MYELODYSPLASTIC SYNDROMES**

Edited by **Ota Fuchs**

#### **Myelodysplastic Syndromes**

http://dx.doi.org/10.5772/61879 Edited by Ota Fuchs

#### **Contributors**

Albert Breier, Khalid Ahmed Al-Anazi, Andreas Himmelmann, Argiris S Symeonidis, Alexandra Kouraklis-Symeonidis, Lale Olcay, Ota Fuchs

#### **© The Editor(s) and the Author(s) 2016**

The moral rights of the and the author(s) have been asserted.

All rights to the book as a whole are reserved by INTECH. The book as a whole (compilation) cannot be reproduced, distributed or used for commercial or non-commercial purposes without INTECH's written permission. Enquiries concerning the use of the book should be directed to INTECH rights and permissions department (permissions@intechopen.com).

Violations are liable to prosecution under the governing Copyright Law.

Individual chapters of this publication are distributed under the terms of the Creative Commons Attribution 3.0 Unported License which permits commercial use, distribution and reproduction of the individual chapters, provided the original author(s) and source publication are appropriately acknowledged. If so indicated, certain images may not be included under the Creative Commons license. In such cases users will need to obtain permission from the license holder to reproduce the material. More details and guidelines concerning content reuse and adaptation can be foundat http://www.intechopen.com/copyright-policy.html.

#### **Notice**

Statements and opinions expressed in the chapters are these of the individual contributors and not necessarily those of the editors or publisher. No responsibility is accepted for the accuracy of information contained in the published chapters. The publisher assumes no responsibility for any damage or injury to persons or property arising out of the use of any materials, instructions, methods or ideas contained in the book.

First published in Croatia, 2016 by INTECH d.o.o. eBook (PDF) Published by IN TECH d.o.o. Place and year of publication of eBook (PDF): Rijeka, 2019. IntechOpen is the global imprint of IN TECH d.o.o. Printed in Croatia

Legal deposit, Croatia: National and University Library in Zagreb

Additional hard and PDF copies can be obtained from<EMAIL_ADDRESS>
Myelodysplastic Syndromes Edited by Ota Fuchs p. cm. Print ISBN 978-953-51-2586-0 Online ISBN 978-953-51-2587-7 eBook (PDF) ISBN 978-953-51-7296-3


**9.4 Process**

The process involved the installation of the machine learning languages into the systems at Harris Methodist Hospital, coding and testing of programs using sample patient values, training the employees to use the program, and its commission for use in identifying patients at risk of heart failure.


**5. TB Vaccine Candidates in Clinical Trials**

As we previously mentioned, the lack of immune marker(s) for prediction of vaccine-elicited protection makes finding effective vaccines against TB extremely challenging, as it requires long and expensive efficacy trials with thousands of volunteers (Phase IIb proof-of-concept trials and Phase III efficacy trials) in endemic countries with a high incidence of TB after obtaining robust safety and immunogenicity data in previous trials with tens (Phase I) and then with hundreds (Phase II) of volunteers [32] (Figure 2).

**Figure 2.** Tuberculosis (TB) vaccine candidates in the pipeline of clinical trials. The diagram shows the advance in clinical trials of the 14 vaccine candidates coloured according to each vaccine strategy.

Unlike HIV and malaria, twenty years ago there was no new candidate for a vaccine against TB in clinical trials. After more than 10 years of previous clinical trials, in 2012 MVA85A was the first candidate since BCG in 1921 to enter efficacy evaluation as preventive TB vaccine in infants [43,44]. MVA85A vaccine was tested in a double-blind, placebo-control Phase IIb efficacy study for its ability to increase (or boost) the immunity in healthy infants HIV-uninfected (aged four to six months) recently vaccinated with BCG at birth, living in a highly endemic region for TB (Worcester, South Africa). A total of 2797 children were vaccinated (1399 with MVA85A and 1398 with a placebo) and followed up every three months for more than three years. Results showed that 32 children (2%) of the 1399 in the MVA85A arm, were diagnosed with TB and 39 children (3%) of the 1398 vaccinated with BCG + placebo. The difference between the two groups was not significant and the interpretation was absence of efficacy of MVA85A. For the TB vaccine scientific community, this study resulted highly informative, and it was a great step forward in the research of new vaccines paving the way for new TB vaccine efficacy studies. The Worcester study was coordinated by the South African TB Vaccine Initiative (SATVI) and the site is highly prepared for testing new promising TB vaccines. Years after this study, the scientific community continues learning and drawing conclusions about the immunology of the disease. After three years of follow-up of the children in the study, the QuantiFERON (QFT) and the risk of disease were studied by SATVI and Oxford University teams [45]. The extended immunogenicity analysis of the trial data showed that both children that remained QFT- (less than 0.35 IU/mL) or those who became QFT + (with less than 4 UI/mL) had a lower risk of developing TB as

compared to QFT + children with more than 4 IU/mL, whose risk of TB disease is high. This result may accelerate studies with other vaccines [45].

Current efficacy trials of new prophylactic TB vaccines attempt to measure either the prevention of infection against *Mtb* (POI), or the prevention of acquiring TB disease (POD) and the prevention of recurrent TB disease (POR) [46]. POR trials evaluate therapeutic vaccines administered as an adjunct to drug treatment to increase the effectiveness and shorten the duration of TB treatment in patients undergoing or completing TB treatment for active disease. The efficacy endpoints of POR trials are prevention of reactivation of existing infections and/or prevention of disease due to new infections. Considering lack of correlates of protection, POD trials provide the most reliable endpoint of vaccine efficacy and acceptance for Regulatory authorities.

In newborns, new TB vaccines should provide evidence of significant superiority over BCG. Global vaccination strategies targeting adolescents and adults would preferably include individuals with and without pre-existing *Mtb* infection, thus avoiding use of IGRAs which are expensive and can interfere with vaccine-induced immune results. In addition, testing candidates in both uninfected and infected individuals in future trials could avoid risks of excluding potentially efficacious candidates in the pipeline against infection but which lack efficacy in IGRA-positive individuals [47].

New TB vaccine candidates today in clinical trials could be divided into whole cell vaccines and subunit vaccines. Whole cell vaccines include live mycobacterial vaccines derived from live attenuated *Mtb* strains, *M. bovis* BCG or recombinant BCG and killed mycobacterial vaccines that could be formulated from other saprophytic mycobacterial species or *Mtb* [48] (Figure 3). Subunit vaccines contain *Mtb* antigens expressed as recombinant proteins that are formulated with different adjuvants or expressed by recombinant viral vectors that are used as vehicles for the administration of antigens [47]. Most of the current subunit vaccine candidates are vaccines with limited antigen diversity which are designed to enhance prior immunity mediated by T cells [49] (Figure 3).

There is a total of 14 TB vaccine candidates in clinical trials today, seven are based on subunits and seven consist on whole-cell mycobacteria [47,50] (Figure 3). Of the subunit candidates, four are mycobacterial fusion protein(s) in new adjuvant formulations (ID93: GLA-SE, H56.IC31, M72:ASO1E, GamTBVac) and three are based on recombinant live-attenuated or replication-deficient virus-vectored expressing one or more *Mtb* proteins (Ad5Ag85, ChadOx1.85/MVA85A, TB/FLU-04L). Of the whole-cell mycobacterial candidates, there are four candidates based on inactivated/extracts of mycobacteria (*M. vaccae*, MIP, DAR-901, RUTI) and three vaccine candidates are based on live attenuated mycobacteria, one is BCG revaccination, since a positive signal has been seen in prevention studies of *Mtb* infection [51], other is based on the use of recombinant BCG (VPM1002) and the third is derived from rationally attenuated *Mtb* (MTBVAC).