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D E Larson

Publications and source records attributed to D E Larson.

67 records · Page 4Linked to original sources
PubMed1982

Endoscopic variceal sclerosis: a one-year experience.

Our first year's experience with endoscopic variceal sclerosis (EVS) performed with a cuffed balloon fiberoptic endoscope is presented. Seventy-five patients have been treated with EVS without requiring the use of general anesthesia. All but one patient had endoscopically documented variceal hemorrhage and underwent EVS while bleeding or shortly thereafter. Ninety-two per cent of the patients were discharged from the hospital after initial treatment with the current overall survival rate being 89.3%. Complications resulting in a prolonged hospitalization were infrequent, but two deaths occurred in which EVS complications may have been a contributing factor. Based on these results, EVS is recommended for managing variceal hemorrhage and is a reasonable alternative for shunt surgery in the management of variceal bleeding.

Adolescent↗
PubMed1981

Structure and protein composition of the striated flagellar rootlets of some protists.

The striated rootlets of different protists are extremely diverse and, on the basis of structural organization, can be assigned to no fewer than four major types. In light of this extreme variation in fine-structure is it reasonable to expect that all striated rootlets may share common protein species? Using the flagellar rootlet of Naegleria gruberi strain NB-1 as reference, we compared rootlet size, structure, and protein composition to another Naegleria strain, another amoebo-flagellate, Tetramitus rostratus, and to the ciliate Tetrahymena pyriformis. Although differing in size and distribution in the cells, the rootlets of all three amoebo-flagellates appeared very similar in structure, periodicity, and in the presence of a common 170 000 Dalton subunit. Kinetodesmal fibres of Tetrahymena differed markedly in detailed fine-structure, in periodicity, and in the apparent absence of the 170 000 Dalton subunit as tested either by SDS gel electrophoresis or by indirect immunofluorescence staining using a specific antiserum directed against the NB-1 major rootlet protein. Consideration of literature describing striated rootlet structure in a wide variety of ciliated and flagellated cells led to the speculation that striated rootlets arose subsequent to primitive flagella and likely evolved along two major pathways: a narrow-period rootlet similar to those discussed above, which developed from the microtubule rootlets of algal flagellates, and a wide-band, contractile rootlet which originated from the primitive interbasal body connector prominent in both algal and protozoan species.

Animals↗
PubMed1981

Isolation, ultrastructure, and protein composition of the flagellar rootlet of Naegleria gruberi.

Attached to the basal bodies of Naegleria gruberi flagellates is a striated rootlet or rhizoplast. The rootlet-basal body complex has been isolated by Triton X-100 lysis of deflagellated cells and differential centrifugation through a 25% glycerol medium. Rootlets isolated from mature flagellates are approximately 13 micrometers long but vary from 8 to 15 micrometers in length: they taper at both ends from a maximum width of approximately 0.25 micrometers in the vicinity of the basal bodies. They are highly stable during isolation but can be solubilized by urea, high salt, low pH, or detergent (Sarkosyl). Partial dissociation of rootlets with 1 M urea reveals that they are composed of filaments, approximately 5 nm diameter, associated in a linear fashion to yield the characteristic 21-nm cross-banded appearance. Differential solubilization of rootlets and their associated contaminants allowed identification of a major rootlet protein, comprising at least 50% of any purified rootlet preparation, with an apparent subunit molecular weight of 170,000. The localization of rootlets in situ by indirect immunofluorescence using a specific antibody directed against the purified rootlet protein demonstrated unequivocally that this 170,000-dalton protein is an organelle component.

Animals↗
PubMed1980

Experimental determinations of tubulin in the in vivo mitotic apparatus of sea urchin zygotes.

Mitotic apparatus (MA) were isolated from zygotes of a sea urchin (Strongylocentrotus purpuratus), using hexylene glycol (pH 6.4) as lysing-stabilizing agent. Protein was measured in the MA pellet and in the remainder of the cell lysate (using the Lowry procedure). Tubulin was measured in the MA pellet and in the remainder of the cell lysate (using microdensitometry of stained gels after sodium dodecyl sulphate - polyacrylamide gel electrophoresis). From these data we calculated the maximum possible amounts of tubulin in the isolated MA and in the MA in vivo; in these calculations we assumed that all the tubulin in the cell is associated with the MA, and we assumed that, as reported in the literature, the MA lose 90% of their dry matter during the isolation. We conclude that tubulin probably comprises less than 7% of the protein in the in vivo MA, and, even if there are very large errors, tubulin is considerably less than half the protein in the MA.

Animals↗
PubMed1979

The limited utility of fibrinogen I 125 leg scanning.

Using venography as the reference procedure, this study examined the utility of fibrinogen I 125 scanning for the detection or demonstration of deep venous thrombosis. The results demonstrate the inability of leg scanning to detect accurately the presence or absence of thrombi in the deep venous system. Most striking was the lack of sensitivity of this procedure in areas where the propensity for embolization is greatest. Sensitivity is extremely low in the anatomic areas where leg scanning demonstrates reasonable specificity. The results are nearly identical in the extremity not operated upon. The validity of all prior studies relying heavily or exclusively on 125I leg scans to determine the presence or absence of thrombi must be critically reassessed.

Fibrinogen↗
PubMedDate not supplied

Regulation of ribosome biogenesis in differentiated rat myotubes.

The rate of ribosome biogenesis is closely coupled with cell proliferation, representing a unique model system for studying gene regulation. Terminal differentiation of rat L6 myoblasts, an example of a rapidly proliferating population of cells being converted into a non-dividing syncytial population, results in an 80% decline in the rate of ribosome accumulation. Ribosome production during myogenesis is regulated by a down-shift in the rate of rRNA accumulation, controlled at the level of transcription by specific trans-acting factors. The synthesis of both ribosomal proteins and 5S rRNA remains unchanged in myotubes, however, resulting in an over-production of these precursors. The excess molecules are rapidly degraded, preventing the accumulation of a static pool of ribosome components.

Animals↗
PubMedDate not supplied

Resuscitation discussion experiences of patients hospitalized in a coronary care unit.

OBJECTIVE: To learn about patients' feelings, beliefs, and values concerning resuscitation and to suggest the role for nurses in discussion of resuscitation options with patients. DESIGN: Prospective, qualitative, phenomenological. SETTING: Midwestern teaching hospital. PATIENTS: Ten patients hospitalized in a coronary care unit. Age range was 67 to 89 years. RESULTS: Participants described beliefs about life-sustaining interventions, decision making, and patient and family involvement, nurses' and physicians' roles in the decision-making process, and desire to know the truth about their health care options. Subjects also offered definitions of cardiopulmonary resuscitation, resuscitation, and code in their own words. CONCLUSIONS: This study suggests that decision-making opportunities are important to patients. Because patients frequently feel comfortable discussing their feelings with nurses, nurses have the opportunity to initiate discussion of sensitive issues with patients.

Aged↗