Consumer behavior: a quadrennium

Consumer behavior continued to attract additional researchers and publication outlets from 1993 through 1996. Both general interest and domain-specific scholarly contributions are discussed, along with limitations and suggested areas for future research. A concluding section observes that the integrity of consumer research is unnecessarily compromised by the failure of the major scholarly association in the field to develop and adopt a code of researcher ethics.

The alpha-helix 4 residue, Asn135, is involved in the oligomerization of Cry1Ac1 and Cry1Ab5 Bacillus thuringiensis toxins

The insecticidal Cry toxins produced by the bacterium Bacillus thuringiensis are comprised of three structural domains. Domain I, a seven-helix bundle, is thought to penetrate the insect epithelial cell plasma membrane through a hairpin composed of alpha-helices 4 and 5, followed by the oligomerization of four hairpin monomers. The alpha-helix 4 has been proposed to line the lumen of the pore, whereas some residues in alpha-helix 5 have been shown to be responsible for oligomerization. Mutation of the Cry1Ac1 alpha-helix 4 amino acid Asn135 to Gln resulted in the loss of toxicity to Manduca sexta, yet binding was still observed. In this study, the equivalent mutation was made in the Cry1Ab5 toxin, and the properties of both wild-type and mutant toxin counterparts were analyzed. Both mutants appeared to bind to M. sexta membrane vesicles, but they were not able to form pores. The ability of both N135Q mutants to oligomerize was also disrupted, providing the first evidence that a residue in alpha-helix 4 can contribute to toxin oligomerization.

Metallization of hydrogen using heavy-ion-beam implosion of multilayered cylindrical targets

Employing a two-dimensional simulation model, this paper presents a suitable design for an experiment to study metallization of hydrogen in a heavy-ion beam imploded multilayered cylindrical target that contains a layer of frozen hydrogen. Such an experiment will be carried out at the upgraded heavy-ion synchrotron facility (SIS-18) at the Gesellschaft für Schwerionenforschung, Darmstadt by the end of the year 2001. In these calculations we consider a uranium beam that will be available at the upgraded SIS-18. Our calculations show that it may be possible to achieve theoretically predicted physical conditions necessary to create metallic hydrogen in such experiments. These include a density of about 1 g/cm(3), a pressure of 3-5 Mbar, and a temperature of a few 0.1 eV.

Shaping of intense ion beams into hollow cylindrical form

A specifically tailored plasma lens could shape a high-energy, heavy-ion beam into the form of a hollow cylinder without loss of beam intensity. It has been experimentally confirmed that both a positive as well as a negative radial gradient of the current density in the active plasma lens can be the underlying principle. Calculations were performed that yield the ideal current density distribution for both cases. A numerical simulation of an experiment with an intense ion beam highlights that the shaping of the beam increases the achievable compression in a lead sample.

Suck and spit, don't blow: orbital emphysema after decompression surgery

PURPOSE

To describe the occurrence of vision-threatening orbital emphysema in patients awakening from orbital decompression surgery and to assess risk factors and preventive measures.

DESIGN

Small noncomparative case series.

PARTICIPANTS

Three patients undergoing bilateral orbital two-wall decompression experienced significant orbital emphysema associated with persistent coughing and Valsalva at the time of extubation.

INTERVENTION

In two patients, symptoms resolved with simple observation, whereas one patient required sedation, topical anesthesia around the endotracheal tube, and needle decompression of trapped air.

MAIN OUTCOME MEASURES

Visual acuity, pupils, visual fields, and sensorimotor examination.

RESULTS

No patient experienced a permanent deficit of visual or sensorimotor function.

CONCLUSIONS

Acute orbital emphysema can occur after orbital decompression surgery despite the large bony opening created. Violent coughing spells at the time of extubation are more common in patients with a history of heavy tobacco use and may be causative. Opening the periorbita may be another specific predisposing risk factor. Knowledge of this dangerous phenomenon, along with appropriate perioperative management, may prevent this complication from occurring.

Adult rat olfactory nerve ensheathing cells are effective promoters of adult central nervous system neurite outgrowth in coculture

A coculture method is described for ensheathing glial cells from adult rat olfactory nerve, serving as a substrate for the regrowth of neurites from adult rat retinal ganglion cells. Immunocytochemically identified phenotypes present in primary cultures of olfactory nerve cells are described, and their ability to promote neurite outgrowth is compared with neonatal astrocytes and Schwann cells, with other nonglial cells, and with laminin. Ensheathing cell cultures were more effective than any other substrate tested and also directed the orientation of regrowing neurites. In comparison with cultured Schwann cells, which released neurotrophic factors into the culture medium, there was no evidence of a similar activity in ensheathing cell cultures. Combinations of ensheathing cell-conditioned medium and substrates of laminin, merosin, or 3T3 cells also failed to show the release of factors enhancing either survival or neurite outgrowth from retinal ganglion cells. Evidence is presented for a partial inhibition of neurite outgrowth in the presence of calcium channel antagonists or an intracellular calcium-chelating reagent. This provides evidence for a contribution from an intracellular calcium signaling mechanism, possibly implicating ensheathing cell adhesion molecules in promoting neurite outgrowth.

Investigation of two yeast genes encoding putative isoenzymes of phosphoglycerate mutase

Our previous data indicated that GPM1 encodes the only functional phosphoglycerate mutase in yeast. However, in the course of the yeast genome sequencing project, two homologous sequences, designated GPM2 and GPM3, were detected. They have been further investigated in this work. Key residues in the deduced amino acid sequence, shown to be involved in catalysis for Gpm1 (i.e. His8, Arg59, His181) are conserved in both enzymes. Overexpression of the genes under control of their own promoters in a gpm1 deletion mutant did not complement for any of the phenotypes. This could in part be attributed to a lack of expression due to their weak promoters. Higher level expression under the control of the yeast PFK2 promoter partially complemented the gpm1 defects, without restoring detectable enzymatic activity. Nevertheless, deletion of either GPM2 or GPM3, or the two deletions in concert, did not produce any obvious lesions for growth on a variety of different carbon sources, nor did they change the levels of key intermediary metabolites. We conclude that both genes evolved from duplication events and that they probably constitute non-functional homologues in yeast.

Glucose modification of human serum albumin: a structural study

Structural changes associated with the exposure of human serum albumin (HSA) to glucose with or without the presence of Cu (II) have been characterized using a bank of methods for structural analysis including circular dichroism (CD), amino acid analysis (AAA), fluorescence measurements, SDS-PAGE, and boronate binding (which is a measure of Amadori product formation). We show that in the short-term (10 d) incubation mixtures, HSA is resistant to Cu (II)-mediated oxidative damage and that the early products of glycation of HSA had minimal effects on the folded structure. Amino acid analysis showed that there was no formation of advanced glycation endproducts (AGE), which can be measured by loss of lysine. This remained the case in longer term incubation of HSA (56 d) in the hyperglycemic concentration range (5-25 mM glucose) despite increased levels of Amadori product (60% boronate binding) and the formation of glycophore (Excitation 350, Emission 425). At high, nonphysiological concentrations (100 mM and 500 mM) of glucose, glycophore formation increased and 3 and 11 mol Lysine-glucose adduct/mol HSA were converted to AGE, respectively. This was accompanied by increased damage to tryptophan and protein-protein crosslinking but only minor tertiary structural change. In the presence of Cu (II), however, AGE formation was accompanied by extensive damage to histidine and tryptophan side chains, main chain fragmentation, and loss of both secondary and tertiary structure. Thus, changes in structure appear to be the result of oxidation as opposed to glycation, per se.

Myofibril size variation along the length of extraocular muscle in rabbit and rat. I: orbital layer

It is generally assumed that a muscle fiber is structurally uniform along its length. That assumption is not consistent with the observed variation of myofibrillar profile size along the length of both singly innervated fibers (SIFs) and multiply innervated fibers (MIFs) in the orbital (outer) layer of extraocular muscle (EOM). Muscle fibers were reconstructed in serial sections along the orbital layer of rabbit and rat EOM. For both the SIFs and MIFs, myofibril profile size was smallest (narrowest) near the endplate. In the SIFs of rat, for example, the myofibril profiles were 28% wider at a distance of 1.5 mm from the endplate than at the endplate itself. Measures of profile size included the mean intercept length and the mean shortest path from test points within the profile to the profile boundary. The possible effect of sarcomere length variation was controlled by normalizing the myofibrillar profile size data to a constant spacing of the myosin filament lattice. This morphometric approach was also used to quantify the further increase of profile size that occurs in the end portions of the orbital MIFs where the myobrillar organization is typically ill-defined.

Myofibril size variation along the length of extraocular muscle in rabbit and rat. II: global layer

Systematic variation of myofibril profile size was observed along the length of both singly innervated fibers (SIFs) and multiply innervated fibers (MIFs) of the global (inner) layer of extraocular muscle (EOM). These findings contrast with the assumption that global layer fibers of EOM are structurally uniform along their length. Muscle fibers were reconstructed in serial sections along the global layer of rabbit and rat EOM. Long fibers of the 'Pale' SIF (fast twitch glycolytic) and the MIF (tonic) populations were sampled by EM in both proximal and distal portions of the muscle. In rabbit, myofibril size of the Pale SIFs showed a proximal-to-distal increase of 28% whereas the MIFs showed a proximal-to-distal decrease of 10%. In rat, these two fiber populations showed analogous smaller changes. Measures of profile size included the mean intercept length and the mean shortest path from test points within the profile to the profile boundary. The possible effect of sarcomere length variation was controlled by normalizing the measures to a constant spacing of the myosin filament lattice.

Identification of alpha-cardiac myosin heavy chain mRNA and protein in extraocular muscle of the adult rabbit

Extraocular muscles contain both fast-twitch and multiply-innervated, tonic-contracting fibres. In rat, these fibres collectively express numerous myosin heavy chain isoforms including fast-type embryonic and neonatal, adult slow twitch type I and fast twitch type II, and a fast isoform unique to extraocular muscle. Immunocytochemical and Western blotting results are presented which suggest that, in rabbit, an additional species, the alpha-cardiac myosin heavy chain, is present. The immunoreactive species is found in all rabbit extraocular muscles and in the extraocular muscles is expressed in almost all fibres which do not contain a fast myosin heavy chain. Positive identification of this isoform as the alpha-cardiac myosin heavy chain was obtained by sequencing a cloned PCR product derived from extraocular muscle mRNA unique to the 3'-end of rabbit alpha-cardiac myosin heavy chain mRNA. This is the first unequivocal demonstration of alpha-cardiac myosin heavy chain expression in extraocular muscle.

Psychologic testing as an aid to selection of residents in anesthesiology

There are no precise psychologic criteria for the selection of residents in anesthesiology. We attempted to provide an objective guide by comparing clinical performance with psychologic tests which we administered to 95 beginning residents in six training programs. The performance of the residents was evaluated by faculty members at the end of the first and second years. We found that high-performance residents scored better than low-performance residents in the categories of Dominance, Independence, Empathy, Responsibility, Socialization, Achievement Motivation, and Well-Being. Prediction of high performance can also be based on Alpha personalities, who typically are independent, reliable, and self-disciplined. The California Psychological Inventory (CPI) is valuable in selecting people with these characteristics.

Transaldolase mutants in the yeast Kluyveromyces lactis provide evidence that glucose can be metabolized through the pentose phosphate pathway

We have isolated the gene encoding transaldolase from Kluyveromyces lactis (KITAL1) by screening a genomic library of this yeast using the TAL1 gene of Saccharomyces cerevisiae as a radioactive probe. The clone isolated contained an open reading frame of 1002 bp, encoding a protein with 76% identical residues in the deduced amino acid sequences as compared to Tal from S. cerevisiae. KITAL1 can complement a tal1 deletion of S. cerevisiae for enzymatic activity. The transcription start of KITAL1 was located at -69 bp relative to the ATG translation start codon. Deleting a large part of the open reading frame from the genome did not lead to any obvious phenotype. Transaldolase was not produced in such mutants as shown by immunological detection. In combination with a double null-mutant in the genes encoding the phosphofructokinase subunits in K. lactis (Klpfk1 Klpfk2 Kltal1), the cells lost their ability to grow on glucose. We take this as strong evidence that glucose is metabolized via the pentose phosphate pathway in this yeast when glycolysis is blocked. In addition, by tetrad analysis we detected a close linkage to KIPFK1 and inferred that KITAL1 is localized on chromosome I.

Sarcoplasmic reticulum fast CA(2+)-pump and myosin heavy chain expression in extraocular muscles

PURPOSE

To investigate the distribution of the sarcoplasmic reticulum fast-twitch Ca(2+)-pump (Ca(2+)-adenosine triphosphatase [Ca(2+)-ATPase]) in extraocular muscle fiber populations of the rat and rabbit, using fast Ca(2+)-adenosine triphosphatase-specific monoclonal antibodies.

METHODS

Adult female rats and rabbits were killed with overdose of sodium pentobarbital, and the extraocular muscles were rapidly frozen in isopentane cooled with liquid nitrogen. Serial transverse frozen sections were cut and labeled respectively with monoclonal antibodies specific for various isoforms of myosin heavy chain, and monoclonal antibodies specific for the fast isoform of the sarcoplasmic reticulum Ca(2+)-ATPase.

RESULTS AND CONCLUSIONS

In rat extraocular muscle, fast type 2 myosin heavy chain and fast Ca(2+)-ATPase are coexpressed in both singly- and multiply-innervated fibers of the orbital layer near the endplate band, but distally both proteins drop out entirely, indicating that the contraction and relaxation properties of orbital fibers vary along their length. Also, fast Ca(2+)-ATPase persists more distally in orbital fibers than does type 2 myosin heavy chain, suggesting that their joint expression is not directly coregulated. This conclusion is reinforced in rabbit, whose orbital multiply-innervated fibers express fast Ca(2+)-ATPase but do not express type 2 myosin heavy chain at all. Fast Ca(2+)-ATPase is expressed in all global layer fast-twitch singly-innervated fibers, but not in global multiply-innervated fibers. In light of known differences in myosin heavy chain expression, the two populations of multiply-innervated fibers must differ with respect to both contractility and relaxation.

The nurse advocate and care for the caregivers

Dramatic improvement in morale, increased retention and an enhanced atmosphere of optimism resulted from introduction of a Nurse Advocate role in an acute care hospital. Within the context of a collaborative governance model, the Nurse Advocate was able to empower individuals and groups to immediate successes. Use of registry nurses was reduced by 99 percent!