Biomedical subjects
Publications and source records attributed to C D Ferris.
This paper describes several retrofit designs to correct operational problems associated with small bench-type blood cell counters. Replacement electronic circuits as well as modifications to the vacuum systems are discussed.
The two inositol phosphate-binding proteins, the Ins(1,4,5)P3 (InsP3) and Ins(1,3,4,5)P4 (InsP4) receptors, and the two particulate InsP3-metabolizing enzymes, InsP3 5-phosphatase and InsP3 3-kinase, were solubilized with detergent from rat cerebellar membranes. These four activities are shown to be distinct molecular species by separation using a variety of protein chromatographic steps. The pharmacology of the partially purified InsP4-binding site indicates that the binding has a high affinity and selectivity for InsP4 over InsP3. These results suggest the existence of a distinct specific InsP4-binding protein which may represent the receptor for this putative second messenger.
When incorporated into lipid vesicles, the purified inositol 1,4,5-trisphosphate (IP3) receptor protein mediates 45Ca2+ flux. We observe a potent, selective allosteric regulation by ATP of IP3 actions on Ca2+ flux. The action of ATP is selective for adenine nucleotides with ADP and AMP less potent and GTP inactive. At 1-10 microM, ATP increases maximal IP3-induced flux by 50% with no change in IP3 potency. The enhancing effect of ATP diminishes between 0.1 and 1 mM. Concentration-response curves are steep for both the increasing and the decreasing effects of ATP on IP3 actions, suggesting a physiological regulatory role of ATP in IP3-induced Ca2+ release. Diminishing local ATP concentrations coincident with filling of Ca2+ stores by the Ca2(+)-ATPase may enhance IP3 release of Ca2+, an effect that would decline as ATP returns to physiological levels. ATP regulation of Ca2+ release may also play a role in oscillations of intracellular Ca2+ concentration.
An instrumentation system is described for obtaining qualitative and quantitative measurements of breast engorgement in postpartum nursing mothers. The system uses an LVDT and associated electronics.
Inositol 1,4,5-trisphosphate (Ins(1,4,5)P3), a second messenger molecule involved in actions of neurotransmitters, hormones and growth factors, releases calcium from vesicular non-mitochondrial intracellular stores. An Ins(1,4,5)P3 binding protein, purified from brain membranes, has been shown to be phosphorylated by cyclic-AMP-dependent protein kinase and localized by immunohistochemical techniques to intracellular particles associated with the endoplasmic reticulum. Although the specificity of the Ins(1,4,5)P3 binding protein for inositol phosphates and the high affinity of the protein for Ins(1,4,5)P3 indicate that it is a physiological Ins(1,4,5)P3 receptor mediating calcium release, direct evidence for this has been difficult to obtain. Also, it is unclear whether a single protein mediates both the recognition of Ins(1,4,5)P3 and calcium transport or whether these two functions involve two or more distinct proteins. In the present study we report reconstitution of the purified Ins(1,4,5)P3 binding protein into lipid vesicles. We show that Ins(1,4,5)P3 and other inositol phosphates stimulate calcium flux in the reconstituted vesicles with potencies and specificities that match the calcium releasing actions of Ins(1,4,5)P3. These results indicate that the purified Ins(1,4,5)P3 binding protein is a physiological receptor responsible for calcium release.
Several designs for true constant-current stimulators are described in this paper. These designs, which include both analog signal and pulse operation, center about the LM334 integrated circuit adjustable current source. Depending upon configuration, these circuits will drive resistive-component loads varying from 500 omega to 10 k omega at current levels up to 10 mA.
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Blood cell counters that operate on the Coulter principle of an electrical resistance change when a cell passes through a small sampling orifice are especially sensitive to electrical noise. The sampling probe is immersed in an electrolyte (isotonic diluent for blood cells), which in itself presents an electrochemically noisy environment. The probe, owing to its large size, acts as an antenna for environmental electrical noise up to 60 Hz. Additionally, the basic Coulter method for cell counting requires a dc potential across the sampling orifice electrodes contained within the probe. This potential produces electrolysis of the diluent and generation of gas bubbles at the electrode surfaces. Sampling (counting) time must be short (less than 30 seconds) to avoid sample heating and an intolerably high noise level as a consequence of ionic motion and gas bubble generation. The resistance change that takes place when a cell passes through the sampling orifice is only a small fraction of a percent, thus noise is a serious problem. Electric noise produces false counts and general degradation of counting function. This paper presents a discussion of a currently used method for signal acquisition and some of the problems encountered in the clinical laboratory. A novel alternative design has been implemented using integrated circuit components, which eliminates many of the problems associated with the use of small bench-type counters. Design philosophy is discussed in detail including presentation of the final circuitry developed. Performance characteristics of the signal acquisition circuitry are presented.(ABSTRACT TRUNCATED AT 250 WORDS)
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A code-generating and display system is described which permits an individual who has lost vocal voluntary motor ability to communicate. The subject sustained severe brain damage in an automobile accident which left him without the power of speech or any significant motor ability, although he is not by definition quadriplegic. He lacks reliable control of eye blink, and the oral movements associated with sucking and blowing are severely impaired; thus, the usual foundations upon which prosthetic devices for quadriplegic patients are designed were not applicable in this case. The subject is confined to a bed, wheelchair, or an exercise table. The system described here has provided the subject with a simple and reliable means of communicating with his family and it permits him to communicate with persons who do not know the Morse code.
This paper briefly examines the experimentally observed effects in, and symmetry arguments for, the constituents of bone which lead to a transversely isotropic configuration for the elastic behavior of bone. Based on this, a regime for computing the anisotropic elastic constants is considered in terms of ultrasonic transit time measurements. To extend the usefulness of ultrasonic techniques to an in vivo situation, a mathematical model for bone is developed in outline form and numerical results for the characteristic frequency equation discussed.