Biomedical subjects

D L Beck

Publications and source records attributed to D L Beck.

29 records · Page 2Linked to original sources

PubMed1991

Triple gene block proteins of white clover mosaic potexvirus are required for transport.

The functions of the protein products encoded by a block of three overlapping genes (the triple gene block) of white clover mosaic potexvirus (WCIMV) have been determined. Mutations were introduced into each of the triple gene block open reading frames and in vitro RNA transcripts assayed in plants and protoplasts. None of the mutants was able to induce symptoms or spread in four systemic hosts and one local lesion host, but all were able to produce progeny genomic RNA, subgenomic RNA, coat protein, and virions in inoculated protoplasts, indicating that all the triple gene block proteins are involved in cell-to-cell spread. Based on observed homologies between the triple gene block proteins of the potex-, carla-, furo-, and hordeivirus groups and Nicotiana velutina mosaic virus, and the demonstrated transport function of the WCIMV and barley stripe mosaic virus triple gene block proteins, these proteins are proposed to constitute a new class of transport proteins.

Amino Acid Sequence↗

PubMed1991

Intraoperative facial nerve monitoring: prognostic aspects during acoustic tumor removal.

Intraoperative facial nerve monitoring with electrical stimulation (IFNMES) has become an integral part of acoustic tumor surgery. We reviewed the records of fifty-six patients who underwent translabyrinthine acoustic tumor removal with IFNMES. There was excellent correlation between intraoperative facial nerve activity and immediate postoperative facial nerve function (24 hours after surgery and at hospital discharge). Our data would suggest that patients who exhibit less than 500 microvolts of ongoing EMG activity during surgery, and who yield at least a 500-microvolt contraction when stimulated with 0.05 milliamps at the brainstem after tumor removal, can expect an excellent immediate facial nerve result (grade I or II).

Ear Neoplasms↗

PubMed1991

Perceived level and sources of stress in baccalaureate nursing students.

The purpose of this study was to investigate the perception of level and sources of stress in nursing students in the various years of the baccalaureate nursing program by identifying the general level of physiological and psychological health, identifying the levels of stress experienced by students in second-, third-, and fourth-year nursing and by identifying the areas that are perceived as being particularly stressful. The method was a descriptive correlational design. The sample consisted of 94 baccalaureate nursing students. Data were collected using two questionnaires--the General Health Questionnaire (GHQ) and the Stress Inventory. Data were analyzed using frequency distributions, t-tests, content analysis, measures of correlation, and analysis of variance. Results showed that the students experienced high stress levels and that they are at risk of having a physical or psychiatric illness. Analysis was done splitting the groups by student status, i.e., RN or generic. Results showed that while both groups are stressed, the generic students report significantly higher levels of stress. Sources of stress also were identified and reported in this article.

Education, Nursing, Baccalaureate↗

PubMed1990

Infectious transcripts and nucleotide sequence of cloned cDNA of the potexvirus white clover mosaic virus.

The complete nucleotide sequence of white clover mosaic virus (WCIMV) strain O has been determined and compared to the WCIMV strain M sequence. The two virus strains show 12% divergence at the nucleotide level and 3% divergence at the amino acid level (open reading frames 1 to 5). Two open reading frames, 10 and 21 kDa, identified in the strain M sequence were not found in the strain O sequence. High levels of infectious RNA transcripts were produced from a full-length cDNA clone of strain O constructed downstream of the SP6 RNA polymerase promoter (greater than 2 micrograms RNA/micrograms template DNA). Symptoms characteristic of WCIMV developed when host plants were inoculated with SP6 RNA transcripts. The specific infectivity of transcript RNA produced in the presence of m7GpppG was similar to that of virion RNA. The SP6 transcripts lacked 5' nonviral nucleotides, but contained 6, 14, or 198 3' nonviral nucleotides (derived from the pUC19 vector). Transcripts were infectious without m7GpppG, or with long nonviral 3' nucleotide stretches. Progeny virus RNA from infections initiated with transcripts containing 198 nonviral 3' nucleotides did not maintain these sequences.

Base Sequence↗

PubMed1990

Deletion of repeated sequences from tobacco mosaic virus mutants with two coat protein genes.

Tobacco mosaic virus (TMV) hybrids were constructed in vitro with an extra coat protein gene (gene order 5'- 126K/183K gene-30K gene-first coat protein gene-subgenomic mRNA promoter:second coat protein gene-3'). One coat protein gene was wild type and the other was derived from one of three coat protein mutants that elicit distinctive phenotypic responses. The hybrids contained large sequence repeats (up to 747 nucleotides). RNA transcripts of each of seven hybrid constructs initiated infections in host plants, but the progeny virus contained only one coat protein gene with no additional or missing nucleotides. Progeny of mutants with the two functional coat protein genes in different order within the genome retained coat protein gene sequence predicted by the number of repeated nucleotides 3' and 5' of the differential nucleotides. In contrast, progeny that resulted from virus hybrids with a wild-type and a nonfunctional coat protein gene possessed only the wild-type coat protein gene, even when the predicted progeny was a free-RNA virus. This demonstrated that selection strongly affected which progeny became predominant in the resulting populations.

Base Sequence↗

PubMed1990

Facial nerve monitoring in otologic surgery: clinical indications and intraoperative technique.

While identification of the intratemporal portion of the facial nerve is mandatory in most otologic surgical procedures, inadvertent instrumentation, traction, or thermal injury may still result from inaccurate delineation, purposeful avoidance, or false protection of this critical structure. Improved functional preservation of the facial nerve has been achieved in acoustic neuroma surgery through the monitoring of evoked facial electromyographic activity. This technique may also be used during otologic procedures in which facial nerve manipulation is anticipated in the management of recurrent cholesteatoma, temporal bone trauma, congenital deformity, or purposeful access for cochlear implantation. Potential indications for using facial nerve monitoring in contemporary otologic surgery are detailed through illustrative case presentations, and necessary instrumentation and techniques are briefly reviewed. Intraoperative monitoring can assist the surgeon in isolating the facial nerve when chronic inflammation, traumatic injury, or anomalous development has resulted in distortion or absence of microanatomic landmarks.

Adult↗

PubMed1990

Intraoperative facial nerve monitoring. Technical aspects.

Intraoperative facial nerve monitoring (FNM) is widely used as a method of assessing the anatomic and physiologic integrity of the facial nerve during procedures in which the nerve may be in jeopardy. The doctors of the Otologic Medical Group use intraoperative FNM during all neurotologic procedures. This technique can also be used for congenital ear surgery and complicated revision chronic ear surgery. On the basis of experience gained from more than 200 cases in which FNM has been used, definitive conclusions can be made in regard to technical aspects. This article will discuss indications for intraoperative FNM, electrode design, visual and auditory feedback, and the particulars about stimulators.

Facial Nerve↗

PubMed1990

Audio-visual consonant recognition with the 3M/House cochlear implant.

Eight experienced 3M/House cochlear implant users' consonant recognition was evaluated with videotaped vowel-consonant vowel lists presented in auditory implant only (A), visual (V), and auditory-visual (AV) conditions. All subjects' scores were better than chance. Results revealed that the AV scores were significantly better than the V scores, which were better than the A scores. Sequential Information Analysis of the consonant errors revealed that different features were transmitted better in each condition. Sonorant and voicing features were transmitted well for the A condition, but features related to high-frequency and place cues were not. Place features were transmitted best in the V condition, but acoustic features were not. Both place and acoustic features were transmitted in the AV condition, but they were influenced most by visual cues.

Auditory Perception↗

PubMed1986

cDNA cloning of the complete genome of tobacco mosaic virus and production of infectious transcripts.

The entire genome of tobacco mosaic virus (TMV) was copied into a series of subgenomic cDNA clones. cDNA sequences of the 5' and 3' ends of TMV were cloned separately. A synthetic oligonucleotide primer was used to generate a Pst I site at the 5' terminus, whereas a different primer was used to generate an Nde I site at the 3' terminus. This strategy permitted removal of non-TMV sequences from cloned cDNA inserts by treatment with exonuclease VII following restriction endonuclease cleavage. Pst I linkers were added to TMV 3' terminal cDNAs. Subgenomic cDNA fragments were ligated together into several independent full-genomic constructions from which TMV cDNA sequences could be cleanly excised as a single fragment by Pst I digestion. Full-genomic TMV cDNA was ligated immediately downstream from the lambda phage promoter from pPM1 and transcribed in vitro with Escherichia coli RNA polymerase. RNA transcripts from three of four full-genomic cDNA constructions were infectious, even though they contained 6 non-TMV nucleotides at the 3' end. Transcripts from a construction with 6 extra nucleotides at the 5' end also were infectious. Progeny virus from plants infected with cDNA transcripts appeared identical to the parental virus. Restriction maps of independent cDNA clones of the same regions of the genome were identical to each other and as predicted from the reported nucleotide sequence of TMV. Also, sequences of the 200 nucleotides proximal to the 5' termini of four independent cDNA clones were identical to each other and to published sequences, suggesting that independent isolates of TMV may have remarkably similar sequences.

Journal Article↗

PubMed1983

Quantitation of apolipoprotein E in rabbit sera with a competitive enzyme-linked immunosorbent assay.

A competitive enzyme-linked immunosorbent assay was developed to quantitate apoE levels in normal and cholesterolemic rabbit serum. The assay can detect 1 ng of apoE and has an interassay coefficient of variation of 5.1%. The assay's antigen specificity was established by the generation of a competitive displacement curve with rabbit apoE, but not with rabbit albumin nor with rabbit apoC. Nonimmune serum was not able to produce a detectable response in the assay. Lipid-protein interactions did not interfere with the assay and color development was linear throughout the incubation time. Rabbits fed a normal diet had 5.3 +/- 0.4 mg of apoE/dl serum. Rabbits fed a diet containing 1% (w/w) cholesterol for 14 days had 86 +/- 11 mg of apoE/dl serum.

Animals↗

PubMedDate not supplied

Effect of dietary cholesterol on apolipoprotein E synthesis in the rabbit.

Female New Zealand White rabbits were fed either rabbit chow or rabbit chow plus 1% (w/w) cholesterol for 14 days. The chow-fed rabbits had normal plasma lipoprotein profiles on agarose gel electrophoresis, 59 +/- 5 mg of cholesterol and 5.5 +/- 0.4 mg of apolipoprotein E (apoE) per dl of serum. The cholesterol-fed rabbits had significant amounts of beta-VLDL in their serum, 1870 +/- 140 mg of cholesterol and 96 +/- 12 mg of apoE per dl of serum. Relative rates of apoE synthesis were determined by incubating hepatocytes in culture medium containing [3H]leucine for 15 min at 37 degrees C and expressing the radioactivity incorporated into immunoprecipitable apoE as a percentage of the radioactivity incorporated into total protein. Hepatocytes from cholesterol-fed rabbits had twice the relative rate of apoE synthesis (1.05 +/- 0.18%) of hepatocytes from chow-fed rabbits (0.55 +/- 0.07%). This increase in synthesis could be a major contributor to the 17-fold increase in serum apoE levels in the cholesterol-fed rabbit.

Animals↗