Influence of rise-fall time upon short-tone threshold.
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Adult↗
Biomedical subjects
K R Johnson
Publications and source records attributed to K R Johnson.
Fibrous myopathy. A rheumatic complication of drug abuse.
A progressive fibrous myopathy may result from chronic intramuscular drug abuse. This complication may mimic other rheumatic disorders and early recognition may prevent disability. The patient described here presented with fixed flexion and extension contracture of hips and knees, respectively, after abusing meperidine and other agents for 3 years. Soft tissues of thighs and buttocks were "wood hard," EMG showed absence of action potentials in affected muscles, and biopsy revealed extensive replacement of muscle with dense, acellular fibrous tissue. Possible mechanisms are discussed.
Biopsy↗
A new allelic series for the underwhite gene on mouse chromosome 15.
A new allelic series at the underwhite gene is described. Three of the alleles in the series--uw, uwd, and Uwdbr--arose as spontaneous mutations on different genetic backgrounds at The Jackson Laboratory. We report here the visible phenotypes and dominance hierarchy of these alleles, all of which are defined by a reduction of pigmentation in both eye and coat color. Electron microscopic analysis of retinal epithelium suggests that the primary defect is in the melanosome. The degree of severity of melanosome anomalies in the retina correlates with the degree of hypopigmentation in the coat. The perturbed gene and its gene product are unknown. We show that the uw locus is genetically distinct from Myo10, a suggested candidate gene for this mutation.
Alleles↗
Dense incisors (din): a new mouse mutation on chromosome 16 affecting tooth eruption and body size.
Dense incisors (din) is a new autosomal recessive mutation in the mouse that interferes with complete eruption of the incisors. The initial eruption of incisors through the gingiva does not differ in mutants and normal littermates, but subsequent further eruption of incisors is arrested in mutants. Radiographic examinations show that, because the incisors do not erupt, continued dentin formation gradually occludes the pulp chambers of these teeth creating as dense incisor. The arrested eruption of the incisor results in an anterior open bite. The pleiotropic phenotype of din/din mutant mice also includes small body size, reduced ear pinna size, and coat color dilution. The din mutation was mapped to Chr 16 near the pituitary transcription factor gene Pit1, but din is not a mutation in Pit1.
Animals↗
Linkage associations in hybridized Salvelinus genomes. The duplicate loci encoding pepidase-D and glucosephosphate isomerase and the unduplicated sorbitol dehydrogenase locus.
Electrophoresis was performed on parents and progeny of 21 families of tetraploid derivative Salvelinus species. Variable phenotypes were shown for the duplicate loci encoding the enzyme peptidase D in lake (S. namaycush) and brook trout (S. fontinalis) and in the fertile hybrid (splake) between them. Pairwise examinations of joint segregation between the duplicated PepD loci and 23 other biochemical loci were performed. Nonrandom assortment was found among progeny of parents doubly heterozygous for the PepD-1 and PepD-2 loci, the duplicate loci encoding glucosephosphate isomerase (Gpi-1 and Gpi-2) and the single locus encoding sorbitol dehydrogenase (Sdh). Two classical linkage groups were found among the uniquely marked loci; PepD-1 with Gpi-1 and PepD-2 with Gpi-2 with Sdh. Pseudolinkage among loci in the two different groups was found in males. The results are shown to fit a chromosomal model involving preferential tetravalent pairing of homoeologous chromosomes. The linkage of PepD and Gpi loci is consistent with that reported in a variety of vertebrate species and indicates the conservation of this linkage group over taxa separated by at least 300 million years of evolution.
Animals↗
Balding: a new mutation on mouse chromosome 18 causing hair loss and immunological defects.
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Alopecia↗
In vitro evaluation of combination chemotherapy against human tumor cells (Review).
Combination therapy with multiple drugs or with multiple modalities is common practice in the treatment of cancer. The purpose of using drugs in combinations is to increase the therapeutic efficacy, decrease toxicity toward the host and minimize or delay the development of drug resistance. Presently used clinical protocols for cancer combination therapy are mainly obtained empirically or from clinical trials. Accumulation of experience from clinical trials is invaluable but is a slow and expensive process. Also, due to heterogeneous patient populations exposed to different environments, human clinical data frequently cannot be used for quantitative synergy determinations. Therefore, in vitro quantitative drug combination studies with cultured tumor cells are becoming imperative either as prospective studies or as adjuvant assessment for combination therapy. In recent years, a variety of in vitro assays have been developed to examine cytotoxicity or biochemical effects of drugs on cultured tumor cells. These methods can, not only quickly predict the potential therapeutic effects of the combined agents, but also provide the information or clues to the possible mechanisms of drug interactions. In addition, with the better understanding of various antineoplastic drugs and the development of new technologies to characterize actions of the drugs, the in vitro study of combination therapy is no longer limited to the measurement of cytotoxic effects. Instead, many other studies, such as cell cycle analyses, detection of apoptosis and biochemical analyses of drug interactions have also become common methods for the in vitro evaluation of combination drug therapy.
Antineoplastic Combined Chemotherapy Protocols↗
Using patient acuity data to manage patient care outcomes and patient care costs.
This article describes actual reported uses for patient acuity data that go beyond historical uses in determining staffing allocations. These expanded uses include managing patient care outcomes and health care costs. The article offers the patient care executive examples of how objective, valid, and reliable data are used to drive approaches to effectively influence decision making in an increasingly competitive health care environment.
Cost Control↗
Management training effects on nurse manager leadership behavior.
Costly organization-based leadership/management development training gives little evidence that such training affects long-term changes in nurse manager leader style adaptability in meeting situations and staff needs.
Adaptation, Psychological↗