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Biomedical subjects

K S Johnson

Publications and source records attributed to K S Johnson.

At least 37 records · Page 2Linked to original sources
PubMed1994

Temporal patterns of radiographic infiltration in severely traumatized patients with and without adult respiratory distress syndrome.

We prospectively evaluated the patterns of pulmonary structural and functional changes in 100 consecutive surgical intensive care unit trauma patients who had (1) emergent major surgery, (2) a pelvic fracture, or (3) two or more major long bone fractures. For each patient, arterial blood gas measurements (ABGs), central venous pressure (CVP), pulmonary capillary occlusion pressure (PAOP), thoracic compliance, arterial oxygen tension/fraction of inspired oxygen (PAO2/FIO2), pulmonary venous admixture (Qs/Qt), and portable chest roentgenograms were sequentially tracked. The senior staff radiologist interpreted all chest roentgenograms. Pulmonary infiltration was quantitated in each of six fields using a scale ranging from 0 to 4, with 0 being no infiltration and 4 being the maximum. Adult respiratory distress syndrome (ARDS) was defined as follows: Qs/Qt > or = 20%, PAO2/FIO2 < 250 or both; dependence on mechanical ventilation for life support for > or = 24 hours; PAOP or CVP or both < 20 mm Hg; and thoracic compliance < 50 mL/cm H2O. Time zero (T0) the time of onset of ARDS, was defined as the time these criteria were met. Eighty-three of 100 study group patients had penetrating injuries, and 17 were admitted with blunt trauma. Fifty-one of 100 patients developed ARDS: 36 of 51 died. Only 4 of 49 (8%) patients without ARDS died. The injured lungs of patients with and without ARDS had similar amounts of infiltration over most measured time intervals. The noninjured lungs of the ARDS patients, however, had significantly greater infiltration than those without ARDS at T0 and over subsequent time intervals.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Schedule-induced defecation: No-food and massed-food baselines.

Defecation rate was monitored during daily 30-min periods as 16 rats were exposed to different sequences of the following three experimental conditions: (a) a fixed-time 60-s food delivery schedule, (b) a massed-food presentation baseline, and/or (c) a no-food baseline. All food delivery was response independent. Rate of defecation increased during fixed-time 60-s food delivery when compared to baseline rates of defecation established during no-food and massed-food baselines. This effect was present for 12 of 16 rats during four alternative sequences of experimental conditions. Within-subject reversals established reliability of this effect. Schedule induction of defecation is clearly demonstrated under these conditions.

Journal Article↗
PubMed1991

Multi-subunit proteins on the surface of filamentous phage: methodologies for displaying antibody (Fab) heavy and light chains.

The display of proteins on the surface of phage offers a powerful means of selecting for rare genes encoding proteins with binding activities. Recently we found that antibody heavy and light chain variable (V) domains fused as a single polypeptide chain to a minor coat protein of filamentous phage fd, could be enriched by successive rounds of phage growth and panning with antigen. This allows the selection of antigen-binding domains directly from diverse libraries of V-genes. Now we show that heterodimeric Fab fragments can be assembled on the surface of the phage by linking one chain to the phage coat protein, and secreting the other into the bacterial periplasm. Furthermore by introducing an amber mutation between the antibody chain and the coat protein, we can either display the antibody on phage using supE strains of bacteria, or produce soluble Fab fragment using non-suppressor strains. The use of Fab fragments may offer advantages over single chain Fv fragments for construction of combinatorial libraries.

Amino Acid Sequence↗
PubMed1991

Molecular cloning of Taenia taeniaeformis oncosphere antigen genes.

Infection of mice with the cestode Taenia taeniaeformis exhibits several important features common to other cestode infections, including the ability to vaccinate with crude antigen mixtures. Partial purification of the protective oncosphere antigens has been reported with a cutout from deoxycholate (DOC) acrylamide gels; this cutout was called fraction II (FII), and comprises approximately 10% of total DOC-soluble oncosphere antigen. Western blots of DOC gels probed with anti-FII antisera revealed a series of 3-5 discrete bands within the FII region. Further fractionation of the FII antigens on DOC gels was impractical due to limitations in supply of oncospheres, so a cDNA library was constructed from 150 ng of oncosphere mRNA and screened with alpha-FII antisera. Two distinct clone families were identified, oncA and oncB. Antibodies affinity-purified on either of two representative members, oncA1 and oncB1, recognised all the FII bands. Individual FII bands excised from a DOC gel resolved into an overlapping series of molecules when re-run on SDS-PAGE, indicating that each FII band consisted of several polypeptides of differing molecular weight. Immunoprecipitates resolved on SDS-PAGE revealed that alpha-FII recognised 3 major oncosphere antigens, of 62, 34 and 25 kDa; antisera against oncB precipitated both the 34- and 25-kDa antigens, whereas alpha-oncA antisera precipitated the 62-kDa antigen. We conclude that oncA and oncB encode the major antigens in the FII complex. The 62-kDa antigen encoded by oncA1 was the only common antigen precipitated by anti-FII and two other antisera raised against different protective extracts, suggesting that it may be a protective component in all three. Southern blot results indicate that oncA and oncB are distinct genes present at low copy number in the genome. Evidence is also presented suggesting that some cestode mRNAs, including oncA, may use variant polyadenylation signals.

Amino Acid Sequence↗
PubMed1990

Normalization of blunted lymphocyte beta-adrenergic responsivity in melancholic inpatients by a course of electroconvulsive therapy.

Electroconvulsive therapy has been reported to desensitize brain beta-adrenergic receptors in rodents, but this effect has not been studied in man. We examined the effect of a course of electroconvulsive therapy on lymphocyte beta-adrenergic responsivity in 19 inpatients with melancholia. Before treatment, beta-adrenergic cyclic adenosine monophosphate response to isoproterenol was significantly blunted in the patients compared with controls. Following a course of electroconvulsive therapy, beta-adrenergic responsivity increased such that patients no longer differed from controls. Thus, blunted lymphocyte beta-adrenergic responsivity is a state-dependent effect of melancholia that can be corrected by a therapeutic course of electroconvulsive therapy. The effect of electroconvulsive therapy on this beta-adrenergic system is in the opposite direction to that reported for rodent forebrain, where electroconvulsive therapy causes desensitization, and may reflect differences between peripheral and central effects, species differences, or disease effects.

Cyclic AMP↗
PubMed1990

Acute effects of single and repeated electroconvulsive therapy on plasma catecholamines and blood pressure in major depressive disorder.

The role of activation of adrenergic neurons by electroconvulsive therapy (ECT) in its antidepressant action was studied by examining acute sympathetic nervous system (SNS) responses to ECT during a course of treatment in patients with melancholia. ECT had an acute dose-dependent effect on plasma norepinephrine (NE) level and blood pressure. The postictal increase in plasma NE and blood pressure was independent of electrical seizure duration. Acute levels of NE and epinephrine after ECT correlated positively with ECT dosage. No cumulative effect of repeated ECT was found on the SNS responses. ECT does activate the SNS in a dose-dependent fashion. However, alternative strategies seem necessary for studying the action of ECT on noradrenergic neurons to identify effects that are cumulative, correspond more closely to the time course of its antidepressant action, and correlate with clinical outcome.

Adult↗
PubMed1990

Immunomagnetic microsphere mediated purging of cALLa positive leukemic cells from bone marrow for autologous reinfusion.

Bone marrow from sixteen patients with cALLa positive ALL have been treated with a monoclonal antibody (MoAb) cocktail which includes DuALL-1 (CD9), WCMH15.14 (CD10) and HD-37 (CD19). Following antibody treatment, marrows were incubated (30 minutes) with anti-murine-IgG1 (Fc) coated magnetic microbeads and passed through a graded magnetic field chamber. Two problems have had to be addressed: (1) More marrow cells must be processed than in marrows from patients with neuroblastoma, for which the separation chamber was originally developed, requiring the use of more beads, causing occlusion of the chamber's collection surface. This has been corrected by using a large surface area pre-magnet for the elimination of excess microbeads prior to processing in the main chamber; (2) Up-modulation (up to 40% positive cells) of the CD9 associated antigen has been detected. To avoid difficulty, marrows are being routinely screened prior to harvest for purging, and purging is delayed for patients with elevated CD9 levels. Eight patients have been reinfused, with no morbidity or mortality associated with the purging or other ex vivo handling of the marrow.

Antibodies, Monoclonal↗
PubMed1990

Relative efficiency of leukemic cell depletion using anti-murine-IgG1(Fc) or anti-murine-IgG coated immunomagnetic microbeads.

Microbeads for immunomagnetic bone marrow purging, to which sheep anti-mouse-IgG1(Fc) antibodies have been linked, and beads linked with antibodies against whole murine immunoglobulin were compared. Competitive binding studies, in which Fc fragments and Fab fragments were titrated onto the microbeads, followed by incubation with 125I-labeled whole mouse Ig, revealed that the beads linked with anti-mouse-IgG1(Fc) specifically bound the Fc region of the murine immunoglobulin molecules. The total amount of antibody of either IgG1 or IgG2 isotype that would adhere to microbeads linked with either type of antibody, as revealed by secondary binding with 125I rabbit antimouse Ig, was identical, suggesting that similar numbers of antibody binding sites were available. In cell depletion studies, it was found that if IgG1 isotype monoclonal antibodies were employed as binding intermediaries between the target cells and the microbeads, the efficiency of target cell depletion was superior with the anti-mouse-IgG1(Fc)-coated beads, even if the amount of MoAb coating the target cells was suboptimal. However, if the intermediary antibodies were of the IgG2 isotype, the efficiency of target cell depletion with these beads was inferior. These findings indicate that the efficiency of immunomagnetic bone marrow purging is dependent upon matching of the targeting MoAb and the secondary antibodies that link to the surface to the microbeads.

Bone Marrow Transplantation↗
PubMed1989

Vaccination against ovine cysticercosis using a defined recombinant antigen.

Cysticercosis caused by larval tapeworms is a major public health problem and a cause of substantial economic losses in the farm-animal industries. Taenia ovis in sheep is a particularly important example. Immunity to reinfection with the larvae has a central role in regulating natural transmission of the parasites, and vaccination with antigens from the early larval oncosphere stage can induce complete protection against infection. As it is impractical to obtain enough oncospheres for a commercial vaccine against these tapeworms, an alternative approach is to use recombinant DNA methods to generate a cheap and plentiful supply of antigens. We report here the expression in Escherichia coli of complementary DNA encoding T. ovis antigens as fusion proteins with the Schistosoma japonicum glutathione S-transferase. Vaccination of sheep with these fusion proteins gave significant, although not complete, immunity against challenge infection with T. ovis eggs. Commercial development of a vaccine is being pursued.

Amino Acid Sequence↗
PubMed1989

The 86-kilodalton antigen from Schistosoma mansoni is a heat-shock protein homologous to yeast HSP-90.

We report the sequence of a cDNA clone encoding an 86-kDa polypeptide antigen (p86) from Schistosoma mansoni. Fusion proteins made in Escherichia coli are recognized by human infection sera. The reading frame of this antigen is highly homologous to those of the large heat-shock proteins of Saccharomyces cerevisiae (HSP90) and Drosophila melanogaster (HSP83). mRNA encoding p86 increases in response to heat shock of adult worms, as does HSP70. Comparisons of the sequences of HSP70 and HSP83 homologues show that these two families of heat-shock proteins are not significantly related except for the last four amino acid residues, which are Glu-Glu-Val-Asp in every case. This sequence is not found at the carboxy terminus of any other protein in the current databases.

Amino Acid Sequence↗
PubMed1988

Single-step purification of polypeptides expressed in Escherichia coli as fusions with glutathione S-transferase.

Plasmid expression vectors have been constructed that direct the synthesis of foreign polypeptides in Escherichia coli as fusions with the C terminus of Sj26, a 26-kDa glutathione S-transferase (GST; EC 2.5.1.18) encoded by the parasitic helminth Schistosoma japonicum. In the majority of cases, fusion proteins are soluble in aqueous solutions and can be purified from crude bacterial lysates under non-denaturing conditions by affinity chromatography on immobilised glutathione. Using batch wash procedures several fusion proteins can be purified in parallel in under 2 h with yields of up to 15 micrograms protein/ml of culture. The vectors have been engineered so that the GST carrier can be cleaved from fusion proteins by digestion with site-specific proteases such as thrombin or blood coagulation factor Xa, following which, the carrier and any uncleaved fusion protein can be removed by absorption on glutathione-agarose. This system has been used successfully for the expression and purification of more than 30 different eukaryotic polypeptides.

Amino Acid Sequence↗
PubMed1987

Possible eggshell protein gene from Schistosoma mansoni.

We have identified and sequenced a cDNA clone of a mRNA found only in mature female schistosomes. This mRNA is not detectably synthesized by female worms from single sex infections (unisexual females), by males or by the developing miracidia in the eggs. The clone hybridises to a highly abundant polyadenylated mRNA of approximately 1500 nucleotides. The nucleotide sequence of the clone predicts a polypeptide comprising two repetitive regions. A pentapeptide repeat with the consensus sequence Gly-Tyr-Asp-Lys-Tyr, and a region rich in histidine residues. Hybrid selected mRNA translated in vitro with [3H]tyrosine as labelled amino acid yields a polypeptide of 48 kDa (p48) that corresponds to the major [3H]tyrosine labelled translation product of female worm total mRNA. p48 does not label with [35S]methionine and is absent from the translation products of male and unisexual female mRNAs. The amino acid sequence of p48 has significant homologies to silk moth chorion proteins and we suggest that it is one of the major components of the schistosome eggshell probably accounting for the high level of [3H]tyrosine incorporation into the vitellaria of Schistosoma mansoni. The tyrosine content of the polypeptide suggests that it may play a role in phenol oxidase mediated cross-linking of the schistosome eggshell and in support of this we find that mushroom phenol oxidase will cause the specific cross-linking of p48 in in vitro translation products.

Animals↗
PubMed1986

Sequence and expression of a major egg antigen from Schistosoma mansoni. Homologies to heat shock proteins and alpha-crystallins.

One of the major proteins of eggs and miracidia (p40) of Schistosoma mansoni has an apparent molecular weight of 40,000 and elicits a strong immune response in over 90% of patients. The antigen consists of a family of at least four near identical proteins, probably encoded by a multi-gene family, and expression of the p40 polypeptides is differentially regulated around the parasite's life cycle. We have isolated and sequenced cDNA clones encoding two variants of the antigen and expressed one p40 clone in Escherichia coli. The fusion protein elicits antibodies which immunoprecipitate p40 and recognise antigens of identical sizes in S. haematobium and S. bovis. The open reading frame encoding this antigen specifies a protein which shares a block of sequence homology with alpha-crystallins and Drosophila small heat shock proteins.

Amino Acid Sequence↗
PubMed1986

The literature of occupational therapy: a citation analysis study.

A citation analysis was done on literature cited in 1978, 1980, and 1982 issues of the American Journal of Occupational Therapy. The results confirmed two impressions. The body of literature specific to occupational therapy is very small. But the body of literature potentially relevant to the work of the occupational therapist is very large, covering many disciplines. An unexpected finding was the reliance on older literature. Implications of these three findings are discussed.

Bibliographies as Topic↗
PubMed1982

Veterinary medical school libraries in the United States and Canada 1977/78.

Data on seven aspects of veterinary medical school libraries are presented and discussed: demographic data on the schools of veterinary medicine the libraries support, number of bound volumes held and number of serial titles received, audiovisual materials, staffing levels and salaries, materials budgets, physical size, and access to computerized bibliographic data bases. The great variability, especially in collection size, is stressed and attributed to such factors as size and programs of the veterinary school, age of the school and library, geographic location, accessibility of other libraries, administrative structure, and exchange programs.

Canada↗