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Biomedical subjects

E Johnson

Publications and source records attributed to E Johnson.

At least 271 records · Page 15Linked to original sources
PubMed1989

Local bone transportation for treatment of intercalary defects by the Ilizarov technique. Biomechanical and clinical considerations.

Ilizarov applied revolutionary methods for salvaging limbs with severe congenital, posttraumatic, or other acquired deformities. His methods, which use a universal system of ring external fixators with tensioned transosseous wires, were developed over the past 35 years at his institute in Kurgan, USSR. These noninvasive techniques have proved successful in over 300,000 patients (adults and children) treated for bone shortening and intercalary deficiency, angulatory and rotational malalignment, active infection, ischemia, joint contractures, and nonunions. Bone transportation involves moving a free segment of living bone to fill intercalary bone defects with vital bone. The trailing end of the transport bone segment maintains continuity with the host bone surface by distraction osteogenesis. The leading end of the transport bone segment fuses to the target bone surface by transformational osteogenesis. The small diameter of the transosseous wires contributes to better patient tolerance over the prolonged treatment times required for gradual distraction at 1 mm per day.

Biomechanical Phenomena↗
PubMed1989

Brain lesions in patients with acquired immunodeficiency syndrome.

Infections involving the brain have become a major complication in patients with acquired immunodeficiency syndrome. We have reviewed 48 cases of central nervous system lesions in patients with acquired immunodeficiency syndrome. and its related complex. All patients had computed tomographic scans with contrast performed; 31 of 48 were intravenous drug abusers. Computed tomographic abnormalities found included 21 patients with multiple ring-enhancing lesions, 13 with single ring-enhancing lesions, 11 with single hypodense lesions, and three with multiple hypodense lesions. Twenty-five patients had a positive serologic reaction for Toxoplasma. Sixteen patients had brain tissues examined. Of the 16 patients, six had cerebral Toxoplasma (one with concomitant Mycobacterium tuberculosis), and ten had diagnoses other than toxoplasmosis (three of whom had a positive serologic reaction for Toxoplasma). Two patients had M tuberculosis; one patient had Nocardia asteroides with Salmonella enteritidis. Of the remaining seven patients, three had encephalitis of unknown cause, two had inconclusive tissue diagnoses, one had progressive multifocal leukoencephalopathy, and one had vasculitis. In the population of intravenous drug users, brain lesions from diseases other than toxoplasmosis may be just as prevalent. Attempts to obtain a diagnosis from brain tissue is highly recommended to permit the design of effective and specific therapy for those diseases amenable to therapy.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Value of screening umbilical cord blood for hemoglobinopathy.

Foremost among the beneficial effects of screening umbilical cord blood is the optimized quality of care that can follow the immediate involvement of an infant with sickle cell disease and his or her family in an appropriate health care system. This is exemplified by the reduction in the case fatality rate of pneumococcal septicemia that has been achieved. Appropriate follow-up of screening also includes transmission of information about the diagnosis of a hemoglobinopathy trait or alpha-thalassemia to affected families and their physicians, with ready availability of education and counseling.

Anemia, Sickle Cell↗
PubMed1989

Duration and patterns of transmission of Theiler's mouse encephalomyelitis virus infection.

The duration and patterns of Theiler's murine encephalomyelitis virus (TMEV) transmission were studied in eight index mice inoculated orally. Transmission was monitored by testing for seroconversion to TMEV in sentinel mice in direct contact with index mice and in other sentinel mice in contact with bedding soiled by index mice. For the first 14 weeks after inoculation, two contact sentinels were housed with each index mouse for 1 week, then replaced with two new sentinels. For the remaining 16 weeks, contact sentinels were changed monthly. All index mice transmitted TMEV continuously (weekly) for 4 to 9 weeks. Thereafter, six index mice transmitted virus intermittently. All index mice ceased transmitting TMEV 7 to 22 weeks post-inoculation. Results obtained from sentinel mice in contact with bedding soiled by index mice were 86% concordant with those using contact sentinel mice. Seven index mice were treated with cyclophosphamide or hydrocortisone 30 weeks post-inoculation. One cyclophosphamide treated mouse reinitiated virus shedding.

Animals↗
PubMed1988

Some novel aspects of the relationship between the amino acid gradient and the sodium electrochemical gradient in mouse ascites tumour cells.

Accumulation of 2-aminoisobutyrate by mouse ascites tumour cells was studied in circumstances where nigericin reversed the normal direction of the Na+ concentration gradient. The membrane potential (delta psi) was assayed using oxonol V as a voltage-sensitive probe. The amino acid gradient (delta mu A) that formed did not significantly exceed the likely magnitude of the Na+ electrochemical gradient when this was in the range 2-6 kJ mol-1. When delta-Na mu increased up to 11 kJ mol-1, delta mu A was almost constant at 7-8 kJ mol-1. The observations indicate that when delta psi is large changes in cellular [Na+] in the range 16-80 mM scarcely affect delta mu A.

Algorithms↗
PubMed1988

Ultrastructural changes in dermal pig skin after exposure to heat and electric energy and acid and basic solutions.

In order to describe the ultrastructure of the histopathological changes in dermis after exposure to electrical energy, heat energy and acid and basic solutions the skin of fully anaesthetized Danish Landrace pigs were exposed to direct current, heat (80 degrees C and 450 degrees C) and acid and basic solutions. Biopsies were obtained immediately after the exposure from all types of injury. Biopsies from the cathode areas biopsies were also taken on day 1 and day 2.5 in order to describe the initial calcium deposits. Homogeneous collagen fibres without any birefringence from heat exposed areas were ultrastructurally composed of filamentous materials. Collagen fibres with fine densely spaced cross-striation from cathode areas and areas exposed to basic solutions were shown ultrastructurally to consist of parallelly arranged collagen fibrils with regular waves. It is concluded that the cross-striation of the collagen fibres observed in polarized light are due to a periodic change in the orientation of the fibres seen as waves of the fibres. The ultrastructure of dermal cells were similar to that of epidermal cells following the different types of influence. Characteristically the nuclei were condensed following heat and more electron-lucent following direct current (d.c.) and acid and basic solutions. In cathode areas and areas influenced by basic solutions the electron-lucent nuclei contained fine fibrils. The ultrastructural study supports the suggestion from light microscopic studies that the morphology of anode and cathode lesions shows resemblance to acid induced and basic induced lesions, respectively. Apatite crystals were observed on day 2.5 at the periphery of the collagen fibrils and in the matrix of elastic fibres.

Animals↗
PubMed1988

Synthesis of soluble C3 and C9 neoepitopes by human alveolar macrophages in vitro.

The aim of this study was to examine whether soluble neoepitopes of activated C3 (C3b, iC3b, C3c) and C9 are produced by human alveolar macrophages cultured in serum-free medium. There was a significant and inhibitable production of C3 and C9 neoepitopes and C9 by the macrophages from all donors, as detected by enzyme-linked immunosorbent assays based on monoclonal (bH6, aE11) and polyclonal (anti-C9) antibodies. A strong donor-dependent variation in the levels of the C3 neoepitope and C9 (five- to sevenfold) and the C9 neoepitope (twofold) was found. After 1 day (24 h) of incubation, the complement levels were largely unaltered. The presence of an exogenous alternative pathway activator (agarose beads) reduced the amount of soluble complement because of binding to the agarose. However, the relative fraction of C9 neoepitope versus C9 increased (two- to threefold), due to agarose-mediated activation of C9. The results demonstrate activation of the complement system in serum-free alveolar macrophage cultures, irrespective of the presence of a known complement activator.

Antibodies, Monoclonal↗
PubMed1988

IgM anti-D as auto-antibody in a case of 'cold' auto-immune haemolytic anaemia.

A case is reported of an auto-immune haemolytic anaemia caused by IgM anti-D. This antibody, although active at 37 degrees C, gave stronger reactions at lower temperatures and appeared to activate complement. The auto-immune haemolytic anaemia was probably secondary to a non-Hodgkins lymphoma.

Anemia, Hemolytic, Autoimmune↗
PubMed1988

A sensitive method to detect synthesis of the functional classical, alternative and terminal pathway of complement by cells cultured in vitro.

A new method used to study in vitro synthesis by human monocytes and alveolar macrophages of the essential complement components for the functional classical, alternative and terminal pathway is presented. The method is based on accumulation of major complements components on activators of the alternative (agarose beads) and classical (lgM-sensitized sheep erythrocytes; ElgM) pathway during co-culture with the phagocytes. There was a time-dependent increase in binding of labelled protein to the co-cultured activators, demonstrating de novo protein synthesis by the phagocytes. Moreover, there was a significant binding to the co-cultured agarose beads and ElgM of monoclonal anti-C3c, anti-C3g, polyclonal anti-C5-C9 and of two monoclonal antibodies (poly C9-MA and MCaEll) to a neoantigen of polymerized C9 present in the terminal complement complex (TCC). In addition, we found a significant binding of polyclonal anti-C4 antibodies to co-cultured ElgM. Incubation of the activators in human serum, subsequently revealed the same pattern of antibody binding. There was no binding of anti-S protein antibodies to the activators after incubation with serum or with the phagocytes. We thus conclude that mononuclear phagocyte-produced complement in the form of C3b, iC3b, and the TCC (C5b-9) was deposited on both activators, whereas C4b was detected on the ElgM. It is our hope that this method can be applied when studying complement biosynthesis by cells other than mononuclear phagocytes.

Animals↗
PubMed1988

Disposable-column radioimmunoassay for serum digoxin with less interference from metabolites and endogenous digitalis-like factors.

A preparative extraction step using disposable C18 low-pressure chromatography columns greatly improved the specificity of a commercially prepared digoxin radioimmunoassay (RIA). Elution solvents were isopropanol/water (15/85 by vol), which extracted most immunoreactive digitalis-like factors and metabolites, and methanol, which extracted digoxin for RIA. Many different digoxin RIA kits could be used. The coefficients of variation for replicates and duplicates were 4.6% and 5.2%. Analytical recoveries of digoxin standards in serum of 1.0, 0.5, and 0.1 microgram/L were 96%, 95%, and 88%, respectively. Serum digoxin was assayed by this method in 200 patients, 47 of whom were studied by HPLC-RIA. Values correlated better with "true digoxin" by HPLC-RIA (r = 0.93) than did values found by direct assay (r = 0.63). The mean for the isopropanol fraction as a percentage of the mean direct RIA value was higher for the 21 dialysis-dependent patients than was that found for the 179 nondialysis patients (P less than 0.004). The method is suggested as being most useful when metabolites or digitalis-like factors are known to be often high and values for digoxin are disproportionate to the dose.

1-Propanol↗
PubMed1988

Evidence for an adrenal contribution to plasma digitalis-like factors.

Digitalis-like factors (DLF) were assayed on plasma collected serially using antibody to digoxin: (1) after intravenous ACTH (n = 3 patients) and (2) after 0.15 U/kg crystalline insulin, 50 micrograms gonadotropin-releasing hormone and 0.2 mg thyrotropin-releasing hormone (n = 7) as a combined pituitary function test. Patients had either hypothalamic-pituitary or ovarian problems. Mean values for DLF rose fourfold after ACTH, and by a factor of 2.3 with the combined pituitary function test. DLF rose at least 50% in all 10 subjects. In 3 dogs, adrenal vein values for DLF were on average more than double values in either adrenal artery or lower vena cava. These results suggest that certain DLFs have an adrenal origin.

Adrenal Glands↗