A correlation between muscular strength and hydroxyproline concentration in human patellar tendon

The connective tissue of the knee is frequently injured by athletes, especially those involved in contact sports. It would be important in the prevention of injury as well as the strategy of physical fitness training to know whether the connective tissue is modified in response to athletic stress or training. The potential modification investigated was variability in the concentration of hydroxyproline, a post-translationally modified imino acid found principally in collagen protein. A correlation was sought between this variability and the leg strength parameters torque (expressed as ft-lbs), torque/body weight and work (expressed as ft-lbs). In a preliminary study of five subjects, no correlation was found between hydroxyproline concentration of the patellar tendon and any of the leg strength parameters. These results suggest that this modification of the collagen in connective tissue does not occur in response to athletic stress or training, but rather, for the small number of subjects investigated, appeared to be relatively constant across a range of leg strengths.     

Optimization of selective hyperthermia

Selective hyperthermia can be a feasible treatment modality for deep tissue abnormalities. It is accomplished by using a laser or ultrasound noninvasively to transfer energy to a desired target causing tissue damage. This process has two potential benefits to medical professionals: simplicity of procedure and safety to patient. However, optimizing these selective interactions is difficult due to the number of variables. We propose an optimization coefficient relating the dynamic and geometric parameters of selective hyperthermia, and proceed to measure it in an experimental setup consisting of a near-infrared laser and laser-absorbing dye. To simulate tissue, gelatin phantoms are created using a combination of water, intralipid, and gelatin. Our experiments use a 1.00-cm-diam spherical phantom that is homogeneously enhanced with an indocyanine green (ICG) solution and placed inside a nontarget phantom and irradiated by an 805-nm diode laser. Temperature measurements taken at different locations are analyzed so optimization coefficients can be calculated for different parameters. This optimization coefficient compares the difference in temperatures from inside and outside the target. Analysis of the values after thermal equilibrium provides information about the best parameter selection. Our findings indicate that the optimal ICG concentration and power combination for our tested parameters are 0.083% and 0.97 W, respectively. Based on our analysis, optimization can be obtained by using this coefficient to compare the selectivity of several parameter combinations.     

Application of Stable Isotopic Ratio Analysis to Identify the Cause of Acute Versus Chronic Lead Poisoning of a Tundra Swan (Cygnus columbianus): A Case Study

We utilized lead (Pb) stable isotopes to identify the source of acute Pb poisoning in a Tundra Swan (Cygnus columbianus) and evaluated overall Pb exposure. Upon necropsy, we obtained samples of blood, liver, kidney, heart, thigh, breast, femur, and metallic objects (i.e., fishing sinker, spring and swivels) from the gizzard for Pb isotopic analysis. Pb isotope ratios of blood and soft tissues were essentially identical to the Pb ratios of the sinker, the likely source of acute poisoning. The spring and swivels had lower Pb content and ratios distinct from tissue, suggesting no significant contribution to poisoning. Femur Pb isotopic composition was the most distinct biological sample and indicative of a combination of sources. These results demonstrate isotopic analysis as a viable method for determining the source of acute Pb poisoning, and that Pb isotope ratios in bone most likely record a lifetime-averaged metric of Pb exposure.

     

Impacts of Maternal Nutrition on Vascularity of Nutrient Transferring Tissues during Gestation and Lactation

As the demand for food increases with exponential growth in the world population, it is imperative that we understand how to make livestock production as efficient as possible in the face of decreasing available natural resources. Moreover, it is important that livestock are able to meet their metabolic demands and supply adequate nutrition to developing offspring both during pregnancy and lactation. Specific nutrient supplementation programs that are designed to offset deficiencies, enhance efficiency, and improve nutrient supply during pregnancy can alter tissue vascular responses, fetal growth, and postnatal offspring outcomes. This review outlines how vascularity in nutrient transferring tissues, namely the maternal gastrointestinal tract, the utero-placental tissue, and the mammary gland, respond to differing nutritional planes and other specific nutrient supplementation regimes.     

Estimation of Glomerular Podocyte Number: A Selection of Valid Methods

The podocyte depletion hypothesis has emerged as an important unifying concept in glomerular pathology. The estimation of podocyte number is therefore often a critical component of studies of progressive renal diseases. Despite this, there is little uniformity in the biomedical literature with regard to the methods used to estimate this important parameter. Here we review a selection of valid methods for estimating podocyte number: exhaustive enumeration method, Weibel and Gomez method, disector/Cavalieri combination, disector/fractionator combination, and thick-and-thin section method. We propose the use of the disector/fractionator method for studies in which controlled sectioning of tissue is feasible, reserving the Weibel and Gomez method for studies based on archival or routine pathology material.Podocytes play a key role in the preservation of normal glomerular structure and function.¹ Podocyte loss has been associated with progression of glomerular diseases both in humans^2,3 and in experimental models of glomerular injury.^4–6 The assessment of podocyte number in human renal biopsy samples and in kidney specimens from animal models may therefore be a pivotal component of studies of the pathogenesis and treatment of glomerular disease. Despite this, there is little uniformity in the biomedical literature with regard to the methods used for estimating podocyte number either in experimental models or clinical biopsy specimens. As a result, estimates of podocyte number can vary widely between studies, making meaningful comparisons difficult.The glomerulus and the cells within it are three-dimensional objects. Quantitative assessment of these structures, on the other hand, has traditionally involved measurements on two-dimensional images from histologic sections. Stereology is a body of mathematical/statistical theory and methods wherein three-dimensional characteristics of objects are estimated from lower-dimensional images of those objects. Although stereology is a well developed field, as with other forms of statistically based reasoning, its results can sometimes seem counterintuitive. At the same time, apparently common-sense approaches to the estimation of quantitative structural variables, such as podocyte number, often lack stereologic validity and, as a result, introduce biologic uncertainty.In this review we describe five methods for estimating podocyte number, examine their assumptions and limitations, and indicate some of the circumstances under which they may represent appropriate approaches. These methods occupy a range of increasingly general assumptions and corresponding changes in methodologic design. The main body of this paper provides an overview and motivation for these five methods (the Supplemental Material describes the methods with worked examples in more detail). We also present one example of a commonly used but invalid method and illustrate its shortcomings.     

Selective photothermal interaction using an 805-nm diode laser and indocyanine green in gel phantom and chicken breast tissue

. Laser immunotherapy, a novel therapy for breast cancer, utilises selective photothermal interaction to raise the temperature of tumour tissue above the cell damage threshold. Photothermal interaction is achieved with intratumoral injection of a laser-absorbing dye followed by non-invasive laser irradiation. When tumour heating is used in combination with immunoadjuvant to stimulate an immune response, antitumour immunity can be achieved. In this study, the selective photothermal effect was investigated using gel phantom and chicken breast tissue. An 805-nm diode laser and indocyanine green (ICG) were used. An ICG-containing gelatin phantom was constructed to simulate targeted tumour tissue. The target gel was buried inside chicken breast tissue and the tissue–gel construct was irradiated by the laser. Temperatures at different locations in the construct were measured during the laser irradiation. For comparison, the thermal effect of an Nd:YAG laser on the tissue–gel construct was also investigated. Selective heating of target gel containing 0.27% ICG and buried 1 cm below the chicken tissue surface was achieved with the 805-nm diode laser using a power of 0.85 W and beam radius of 1 cm. The target gel experienced a temperature increase of more then 6°C whereas the surrounding chicken breast tissue experienced only a minor temperature increase. The feasibility of this experimental set-up has been shown. It will be used in the future to optimise treatment parameters such as laser power, laser beam radius, and dye concentration. Paper received 17 April 2002; accepted 3 May 2002. Correspondence to: W.R. Chen, Biomedical Engineering Program, Department of Physics and Engineering, University of Central Oklahoma, Edmond, OK 73034, USA. Tel.: (405) 974-5198; Fax: (405) 974-3812; e-mail: wchen@ucok.edu