Determining skin thickness with pulsed ultra sound

A high frequency, high resolution ultrasonic echo technique is presented for determining the thickness of human skin. An experimental series is described in which the accuracy of this new technique is demonstrated by comparison with a radiological method of proven accuracy. The "ultrasonic biometric ruler" is shown to provide an accurate, simple, noninvasive method for measuring full-thickness human skin. In addition to the determination of skin thickness, it is demonstrated that the underlying subcutaneous fat and muscle can also be noninvasively "explored" with the possibility of identifying a variety of skin and underlying tissue lesions.

Sphygmomanometry in the pediatric patient

The indirect measurement of blood pressure in the pediatric population is often difficult or impossible to perform and when values are obtained, they are often unreliable or inaccurate. An accurate measurement of arterial systolic pressure in the upper extremity is obtainable with a properly designed and sized occluding cuff and an ultrasonic device to detect the first Korotoff sound. For the detection of the first Korotkoff sound ultrasonic Doppler devices are superior to the stethoscope. When wider occluding cuffs than usual are applied to the upper extremity, the error of measurement is minimized. A method for accurately measuring end diastolic pressure has yet to be described despite assertions to the contrary.

Accounting for natural tension in the mechanical testing of human skin

A low-pressure suction device has previously been used to obtain quantitative information on the mechanical properties of human skin. Reducing the raw data from this technique was complicated by the fact that the skin is already biaxially loaded in the natural state and a rational basis on which to compare results obtained from different subjects was not available. Using a strain gauged pretension device, a procedure for determining the natural state tension and extension fields in the skin has been developed. The natural tension was then relaxed in the direction of testing and the suction device used to determine the two-dimensional skin tension-extension ratio response of the skin at a constant testing rate. The data from a number of subjects have been used to develop a new multidimensional stress-strain theory in terms of two material constants that are related to basic material characteristics of the dermis and are uniquely determinable regardless of the natural state stress field. Tests performed on the upper backs of 23 healthy adult males were used to investigate the variations in the material constants with age and sun-exposure habits. Age variations were found to corroborate earlier studies, and variations with sun exposure habits were related to known dermal collagen and elastin changes due to ultraviolet radiation. The apparent sensitivity of the testing procedure to physiologic state variables holds out the hope that mechanical properties characterization will be a useful tool in the evaluation of the severity of certain pathologic states and the effect of therapy.

[Advances in sphygmomanometry (author's transl)]

Problems of the accuracy and reliability of Riva-Rocci's non-invasive method of measuring blood pressure always arise when the cuff does not fit well, i.e. with a very conical upper limb, adiposity or in neonates or patients in shock. From thorough clinical investigations it appeared that the cuff used for blood pressure measurements in adults and the few models for neonates and children are too inaccurate. The cuff must enclose the limb completely and have a minimum ratio of breadth to length of 1 : 3. An integral inflatable cuff unit has been developed and clinically tested in our laboratory during the last two years. It consists of a heat-sealed polyolefine film.

[Genetic activity of mouse oocytes during in vitro "spontaneous" maturation]

Mouse oocytes, liberated from ovarian follicles, resume meiosis in the obligatory presence of Ca++. PHMPS exerts a toxic effect on this mechanism. m-RNA synthesis, in contrast to that of r-RNA. seems to be required during the first hours of maturation in order to ensure realization of the following steps: in addition the 2nd maturation period, corresponding to the first polar body extrusion, depends on the presence of proteins synthesized during the chromatin condensation process and germinal vesicle breakdown. We suggest that it might be a factor responsible for microtubule formation in metaphase I.