Misconceptions and issues regarding allometric scaling during the drug development process

Introduction: Allometry is the study of size and its consequences. The simple hypothesis of allometric scaling is that all physiological parameters are proportional to body size or body mass. This review examines the development of theory-based allometry or fixed exponents (0.75 and 1.0 for basal metabolic rate and volume, respectively) and the evidence for or against the theory. The main focus of this report is to show the readers that there is enough evidence from experimental data that negate the concept of theory-based allometry in biology, physiology, and pharmacokinetics.

Areas covered: In this review, the history of the development of theoretical allometry and the strong evidence against theory-based allometry demonstrated by experimental data is provided. During drug development, allometry is applied to both inter-species (from animals to humans) and intra-species (adults to children) scaling. These two forms of allometric scaling in the context of theory-based allometry are discussed and provide insight on scientific progress that refute theory-based allometry.

Expert opinion: Theory-based allometry is a mere theory and experimental data and real-life observations strongly negate the existence of such a theory. Pharmacostatistical and physiological models based on theory-based allometry can be misleading and incorrect because the theory-based allometric exponent 0.75 is not universal. The exponents of allometry are data dependent and are not fixed in the universe.     

Anthropometric Determinations of Umbilical Position in Iraqi Adults

Introduction  Umbilicus is an important surface landmark on the anterior abdominal wall in addition to its aesthetic and psychological effect. Objectives  The objective of the study is to determine the position of umbilicus in Iraqi adults to provide a guide for the neoumbilicus in abdominoplasty. Subjects and Methods  This is an observational study performed on 100 volunteers with no abdominal wall abnormality. Measurements included weight, height, body mass index (BMI), distance from xiphoid to umbilicus, distance from xiphoid process to pubic symphysis, distance from xiphoid process to both anterior superior iliac spine (ASIS), distance from pubic symphysis to umbilicus and from pubic symphysis to xiphisternum, distance of umbilicus to both ASIS, and distance of umbilicus to interspinous line and to inter-anterior hypochondrium line. Results  The study included 100 volunteers, with 50% male and 50% female whose age ranges between 18 to 60 years. The results were a follows: distance from xiphoid process to umbilicus and distance from xiphoid process to pubic symphysis were 18.03 ± 3.25 cm and 32.21 ± 4.64 cm, respectively; distances from xiphoid process to right ASIS and left ASIS were 25.95 ± 5.72 cm and 25.84 ± 6.02 cm, respectively; distance from pubic symphysis to umbilicus was 17.66 ± 3.12 cm; distance of umbilicus to interspinous line was 9.25 ± 1.84 cm. The distance from umbilicus to inter anterior hypochondrium line was 9.905 ± 2.19 cm. Conclusion  These measurements can determine the neoumbilicus position, reduce practical mistakes, and improve postsurgical outcomes.     

Overview of non-invasive factors (low level laser and low intensity pulsed ultrasound) accelerating tooth movement during orthodontic treatment

The need for orthodontic treatment is increasing all the time. As the treatment is time consuming ranging from a year to several years, any method of reducing the period of treatment and increasing the quality of the tissue will be beneficial to patients. The use of non-invasive techniques such as low level laser therapy and low intensity pulsed ultasound in accelerating orthodontic tooth movement are promising. Thus, this overview study will help to generate more understanding about the background information and the possible applications of them in daily orthodontics, depending on previous literature searching for reviews and original research articles.     

Optimisation of Shrinkage and Strength on Thick Plate Part Using Recycled LDPE Materials

Achieving good quality of products from plastic injection moulding processes is very challenging, since the process comprises many affecting parameters. Common defects such as warpage are hard to avoid, and the defective parts will eventually go to waste, leading to unnecessary costs to the manufacturer. The use of recycled material from postindustrial waste has been studied by a few researchers. However, the application of an optimisation method by which to optimise processing parameters to mould parts using recycled materials remains lacking. In this study, Response Surface Methodology (RSM) and Particle Swarm Optimisation (PSO) methods were conducted on thick plate parts moulded using virgin and recycled low-density polyethylene (LDPE) materials (100:0, 70:30, 60:40 and 50:50; virgin to recycle material ratios) to find the optimal input parameters for each of the material ratios. Shrinkage in the x and y directions increased in correlation with the recycled ratio, compared to virgin material. Meanwhile, the tensile strength of the thick plate part continued to decrease when the recycled ratio increased. R30 (70:30) had the optimum shrinkage in the x direction with respect to R0 (100:0) material where the shrinkage increased by 24.49% (RSM) and 33.20% (PSO). On the other hand, the shrinkage in the y direction for R30 material increased by 4.48% (RSM) and decreased by 2.67% (PSO), while the tensile strength of R30 (70:30) material decreased by 0.51% (RSM) and 2.68% (PSO) as compared to R0 (100:0) material. Validation tests indicated that the optimal setting of processing parameter suggested by PSO and RSM for R0 (100:0), R30 (70:30), R40 (60:40) and R50 (50:50) was less than 10%.