A solid state delayed auditory feedback system for speech therapy

A delayed auditory feedback system has been constructed using solid state integrated circuit components. The construction of the instrument is described and the advantages of such an electronic device over conventional electro-mechanical systems are discussed.

Responses of cancer patients in the MEM test: not just a function of charge on basic proteins

It has been reported that lymphocytes from cancer patients give positive responses to PPD, myelin basic protein, tumour basic protein, and certain histone fractions in the MEM test. The underlying mechanisms of the MEM test are poorly understood, but it is widely assumed that it detects immunological sensitization to specific antigenic determinants. The cross-reactivity experienced is interpreted as indicating shared antigenicity. Since all the stimulatory proteins are strongly basic we investigated an alternative explanation that responsiveness is a function of electrical charge by comparing the known stimulatory proteins in the MEM test with two others of similar basicity: lysozyme and cytochrome-C. We obtained highly significant stimulation with PPD, tryptophane peptide of myelin, and tumour basic protein using Mantoux + cancer patients, but found no response to other basic proteins. We failed to confirm the reported activity of histone F2a. Our results indicate that basicity alone is insufficient to elicit response, and strengthens the concept that the MEM test is measuring sensitization to the determinants shared by myelin and tumour basic protein.

A comprehensive treatment unit for the respiratory distress syndrome in the newborn

Various systems have been devised to improve the therapy of idiopathic respiratory distress syndrome in newborn infants. This article describes a new ventilator which provides alternating positive and negative pressure ventilation(APNPV) in addition to the more conventional techniques. Safety aspects, technical performance and cleaning procedures are described. A brief summary of the clinical performance of the machine is given.

Experience in the development of low haemolysis pumps

In an attempt to provide a pulsatile pump with a low rate of haemolysis, two pulsatile pumps have been developed. These were compared with commercially available pulsatile and roller pumps. The blood flow and the rate of haemolysis were studied under similar conditions. Our pumps were significantly better than the commercial pumps as far as mechanical damage to the red blood cells was concerned. However, we carried out certain modifications to one of our pumps which resulted in a significant reduction in the amount of haemolysis over its previous performance.

Experimental evaluation of mechanical haemolysis with Starr-Edwards, Kay-Shiley and Björk-Shiley valves

Mechanical cell damage was studied in vitro with three types of prostheses: Starr-Edwards, Kay-Shiley and Björk-Shiley valves. Mechanical cell damage was found to be closely related to the flow characteristics in the prosthesis. Considering valves of similar orifice diameter, Björk-Shiley valves produced the lowest rate of haemolysis. This is due to the improved haemodynamic characteristics of the valve which resulted from the laminar type of flow. With Starr-Edwards valves, smaller sizes produced unacceptably high rates of haemolysis. Increasing the mean forward flow across the valve resulted in a disproportionate rise in the energy loss and the rate of haemolysis when compared with Björk-Shiley valves of similar annulus diameters.

Requirement for accessory cells in the antibody response to T cell-independent antigens in vitro

The antibody responses of mouse spleen cells in vitro to three thymus-independent (TI) antigens namely, polymeric flagellin (POL) of Salmonella adelaide, DNP-Ficoll and "soluble" sheep erythrocyte (SRBC) antigen, were found to be dependent on adherent accessory cells (A cells) but to a lesser degree than the response to intact SRBC. Evidence for this comes from selective depletion of A cells from spleen cells and reconstitution with A cell-rich populations. Thus, depletion of A cells by adherence on glass resulted in abolition of the response to SRBC leaving the response to POL intact. More thorough removal of A cells by treatment with carbonyl iron powder was required for appreciable reduction of the responses to POL, DNP-Ficoll and "soluble" SRBC. This reduction in responsiveness was not due to poor cell survival after A cell depletion or to the loss of immunocompetent cells since 1) the recoveries of viable cells in all cultures were similar; 2) the contents of theta- and Ig-bearing cells and tritium-labeled POL-binding cells were unaltered after carbonyl iron treatment, and 3) responsiveness was fully restored by the addition of irradiated and anti-theta-treated A cells from the peritoneal cavity or the spleen. Hence, the hitherto A cell independence of TI antigens on which some theories of B cell activation are based is a result of inadequate depletion procedures, and the minimal model for B cell activation must take into account two cell types: B cells and A cells.

Electrical interference in hospitals--practical experience in a large region

A great deal has been written about electrical interference, yet there is a distinct lack of information for the hospital environment. There are many factors affecting this problem in the clinical context and we report on our own practical experiences based on routine investigation of electrical interference. We describe the special instrumentation developed, the method of investigation adopted and the most common interference problems encountered. We also review the manufacturer's contribution.

Pancreaticoduodenectomy in the treatment of congenital fibrosarcoma of the duodenum

A 2-mo-old female with congenital fibrosarcoma causing duodenal obstruction had a pancreaticoduodenectomy. She is doing well with the aid of oral pancreatic enzyme supplements 14 mo after her pancreaticoduodenectomy with no evidence of tumor recurrence or pancreatic endocrine dysfunction.

Care of medical instrumentation

Bio-engineering means much more than academic research—there is now a great deal of complex medical instrumentation in hospitals yet little consideration has been given to its care. This article discusses from practical experience the requirements of a good maintenance service

Medical equipment hazards--practical experience in a large region

An investigation has been carried out into the cause of accidents involving patient interfaced medical equipment, in a large region over a period of 3 years. In a high proportion of accidents the cause is faulty design, or poor construction of equipment. However, a considerable number can also be attributed to lack of user appreciation of the hazards involved. A few accidents have been caused by inexperienced personnel attempting to service equipment about which they have little knowledge.

Mechanical deficiencies in scintillation counters, scanners, and gamma cameras

After an accident involving a scintillation counter, the machanical integrity of scintillation counters and their stands, rectilinear scanners, and gamma cameras was examined. An alarming proportion of these divices were found to be poorly designed with consequent danger to patients and staff. This class of equipment should be covered by standards incorporated in a comprehensive hospital technical memorandum.