A device for high-throughput monitoring of degradation in soft tissue samples

This work describes the design and validation of a novel device, the High-Throughput Degradation Monitoring Device (HDD), for monitoring the degradation of 24 soft tissue samples over incubation periods of several days inside a cell culture incubator. The device quantifies sample degradation by monitoring its deformation induced by a static gravity load. Initial instrument design and experimental protocol development focused on quantifying cartilage degeneration. Characterization of measurement errors, caused mainly by thermal transients and by translating the instrument sensor, demonstrated that HDD can quantify sample degradation with <6 μm precision and <10 μm temperature-induced errors. HDD capabilities were evaluated in a pilot study that monitored the degradation of fresh ex vivo human cartilage samples by collagenase solutions over three days. HDD could robustly resolve the effects of collagenase concentration as small as 0.5 mg/ml. Careful sample preparation resulted in measurements that did not suffer from donor-to-donor variation (coefficient of variance <70%). Due to its unique combination of sample throughput, measurement precision, temporal sampling and experimental versality, HDD provides a novel biomechanics-based experimental platform for quantifying the effects of proteins (cytokines, growth factors, enzymes, antibodies) or small molecules on the degradation of soft tissues or tissue engineering constructs. Thereby, HDD can complement established tools and in vitro models in important applications including drug screening and biomaterial development.     

A hydrostatic device for tissue dehydration.

A simple device for mixing water and organic solvents can be easily constructed to dehydrate tissue for electron microscopy. The device utilizes hydrostatic leveling between a reservoir and a mixing chamber to produce a continuously increasing concentration of dehydrating solvent. The rate of dehydration may be regulated by geometry and/or outflow rate. A prototype model is described which compactly incorporates the solvent reservoirs and a tissue tray that can accommodate ten tissue specimens in stainless steel mesh baskets. The device can be fabricated cheaply and replaces manual dehydration.     

A new device for dermabrasion: the centrifugal dermabrader

A new rotary device for dermabrasion is presented that allows a superficial dermabrasion to be performed quickly with low risk of contour defects.     

A new method for the concentration of micro protein samples

In many cases before a protein sample can be subjected to analysis by gel filtration, electrophoresis, or immunoelectrophoresis, concentration may be necessary. Some of the commonly used techniques for sample concentration are adsorption on columns, ultrafiltration through cellophane membranes, evaporation of water, absorption by hydrophilic gels, precipitation by salts or organic solvents, and rechromatography. Except for evaporation, all of the other procedures are practical only when the sample size exceeds a few milliliters. Although there is no lower limit on the sample size when evaporation is employed, the resulting increase in salt concentration of the final product is a problem.In this communication we describe a simple technique that is capable of concentrating, severalfold, samples of proteins 25–250 μl in volume. The technique is based on the same principle as ultrafiltration through cellophane membranes.     

A method for preparing freeze-clamped tissue samples for metabolite analyses

A rapid and simple method for preparing freeze-clamped tissue samples for metabolite determinations is described. Freeze-clamped rat heart tissue samples weighing from 0.8 to 1.0 g were homogenized directly in an Ultra-Turrax homogenizer for 60 s in 3.5 ml of ice-cold 0.6 M HClO4 without pulverizing them in liquid nitrogen. After centrifugation, the pellet was rehomogenized in the Ultra-Turrax homogenizer for 30 s in 1.5 ml of HClO4. Following a further centrifugation the extracts were combined and the pH was adjusted to 7.0 by adding 5 M K2CO3. The neutralized supernatant was used for the desired assays. The analyses of the tissue extracts obtained from isolated perfused rat hearts by the present method give similar results for different kinds of metabolites than those processed according to the previous classical method. Moreover, the values of the various parameters determined from the tissue extracts prepared according to the method described here are similar to the data reported in literature. The method can be readily applied to any other freeze-clamped tissue. The greatest improvement obtained is that the homogenization procedure can be accomplished easily and conveniently in about one-tenth of the time required for the earlier classical method without the time-consuming and unpleasant tissue grinding in liquid nitrogen.     

A hot wire device for cutting tissue culture flasks

Summary A small hot wire device for cutting plastic culture ware can be constructed of steel rod, brass screws, nichrome wire and acrylic plastic sheeting and tubing. The nichrome wire is heated using a variable power transformer. Four sequential cuts are made in the culture flask bottom and the bottom separated from the remainder of the flask. Cultures can be stained, air-dried and cover slips affixed with PVP or epoxy resin. This method of cutting culture ware avoids the formation of small bits of polystyrene generated by rotating discs or saws.     

A collection device for small electronically sorted samples from flow cytometers

A device (Hunziker chamber) has been fabricated which facilitates the collection and biochemical analysis of electrostatically sorted nuclei. The G₀ + G₁ and G₂ + M populations and the 2N and 4N populations of rat liver nuclei were sorted on the basis of light scatter or fluorescence by the fluorescent activated cell sorter (Becton-Dickinson). Sufficient amounts of nuclear samples were sorted and collected in the Hunziker chamber for the analysis of nuclear proteins by sodium dodecyl sulfate discontinuous polyacrylamide gel electrophoresis. An example of the electrophoretic banding patterns of nuclear proteins from these populations is given.     

A new device for the metric study of the hard palate

This new device which measures anatomic elevations makes it possible that the measurements on the palate model can be performed very rapidly. This permits outstanding exact classification of the palate relief to the respective category.