Polyvinylpyrolidone-functionalized silver nanoparticles do not affect aerobic performance or fractional rates of protein synthesis in rainbow trout (Oncorhynchus mykiss)

Aerobic performance in fish is linked to individual and population fitness and can be impacted by anthropogenic contaminants. Exposure to some engineered nanomaterials, including silver nanoparticles (nAg), reduces rates of oxygen consumption in some fish species, but the underlying mechanisms remain unclear. In addition, their effects on swim performance have not been studied. Our aim was to quantify the impact of exposure to functionalized nAg on aerobic scope and swim performance in rainbow trout (Oncorhychus mykiss) and to characterize the contribution of changing rates of protein synthesis to these physiological endpoints. Fish were exposed for 48 h to 5 nm polyvinylpyrolidone-functionalized nAg (nAgPVP; 100 μg L^-1) or 0.22 μg L^-1 Ag⁺ (as AgNO₃), which was the measured quantity of Ag released from the nAgPVP over that time period. Aerobic scope, critical swimming speed (U_crit), and fractional rates of protein synthesis (K_s), were then assessed, along with indicators of osmoregulation and cardiotoxicity. Neither nAgPVP, nor Ag⁺ exposure significantly altered aerobic scope, its component parts, or swim performance. K_s was similarly unaffected in 8 tissue types, though it tended to be lower in liver of nAgPVP treated fish. The treatments tended to decrease gill Na⁺/K⁺-ATPase activity, but effects were not significant. The latter results suggest that a longer or more concentrated nAgPVP exposure may induce significant effects. Although this same formulation of nAgPVP is bioactive in other fish, it had no effects on rainbow trout under the conditions tested. Such findings on common model animals like trout may thus misrepresent the safety of nAg to more sensitive species.

Functionalized silver nanoparticles depress aerobic metabolism in the absence of overt toxicity in brackish water killifish, Fundulus heteroclitus

Engineered nanomaterials (ENMs) tend to precipitate in saline waters so the majority of aquatic toxicity studies have focused on freshwaters, where bioavailability is presumed to be higher. Recent studies have illustrated that some ENM formulations are bioavailable and bioactive in salt water and that their effects are more pronounced at the physiological than biochemical level. These findings raise concerns regarding the effects of ENMs on marine organisms. Therefore, our goal was to characterize the effects of polyvinylpyrolidone-functionalized silver ENMs (nAg) on aerobic performance in the killifish (Fundulus heteroclitus), a common euryhaline teleost. Fish were exposed to 80 μg L^-1 of 5 nm nAg for 48 h in brackish water (12 ppt) and routine (ṀO_2min) and maximum (ṀO_2max) rates of oxygen consumption were quantified. Silver dissolution was minimal and nAg remained well dispersed in brackish water, with a hydrodynamic diameter of 21.0 nm, compared to 19.3 in freshwater. Both ṀO_2min and ṀO_2max were significantly lower (by 53 and 30%, respectively) in killifish exposed to nAg and a reduction in ṀO₂ variability suggested spontaneous activity was suppressed. Neither gill Na⁺/K⁺-ATPase activity, nor various other biochemical markers were affected by nAg exposure. The results illustrate that a common ENM formulation is bioactive in salt water and, as in previous studies on functionalized copper ENMs, that effects are more pronounced at the whole animal than the biochemical level.

Hydration study of homopolypeptides by (2)H NMR

Deuteron T(1) and T(2) was studied as a function of hydration in homopolyglycine (PG) and homopolyproline (PP). Water deuteron relaxation rates in PG conform to a hydration model involving two types of primary hydration sites where water is directly bonded to the polymer. Once these sites are filled, additional water only bonds to water molecules at the primary sites and in so doing affect their dynamics. PP exhibits an anomalous T(1) and T(2) hydration dependence which has been interpreted in terms of a cooperative water molecule-PP molecule helical conformational rearrangement which occurs once a certain hydration level is reached. The proposal of a water-PP structure is tested using molecular dynamics simulations.

The determination of the size and shape of buried InAs/InP quantum dots by transmission electron microscopy

Bright-field, diffraction-contrast imaging in the transmission electron microscope has been applied to the determination of the diameter and height populations of a single layer of buried, pure, InAs/InP quantum dots (QDs). Plan-view diffraction contrast from the QDs was observed to increase significantly when the sample was tilted away from the [001] growth direction to near the [111] zone-axis orientation. This added contrast was a result of contributions to the displacement of atoms in a direction perpendicular to the electron beam arising from strain in the growth direction. Since the strain in the growth direction was about an order of magnitude larger than the strain perpendicular to the growth direction, as the sample is tilted away from the [001] zone-axis condition, the larger strain component increases the projected strain thereby increasing the QD contrast in the image. For the sample studied, both of the populations for the QD diameter and the image contrast were observed to be multimodal with the seven peaks in the contrast distribution correlating with seven distinct populations of QDs each differing in height by one monolayer (ML), from 3 to 9MLs. An analysis of the theoretically expected and experimentally observed standard deviations in the Gaussian fits to the QD diameter and height distributions provided an additional constraint in the selection of the optimal model for the multimodal distributions.

Intravenous and oral pharmacokinetic study of BCX-1777, a novel purine nucleoside phosphorylase transition-state inhibitor. In vivo effects on blood 2'-deoxyguanosine in primates

Administration of BCX-1777 to primates results in a rapid elevation of plasma 2'-deoxyguanosine (up to 0.4 microg/ml, 1.5 microM). Maximum 2'-deoxyguanosine C(max), 0.4 microg/ml, was achieved with the lowest IV dose of BCX-1777 and increasing the IV dose of BCX-1777 did not increase the 2'-deoxyguanosine C(max). However, plasma 2'-deoxyguanosine remained elevated longer as the dose of BCX-1777 increased. In contrast, increases in the oral dose of BCX-1777 did increase the plasma C(max) of 2'-deoxyguanosine. This was in spite of the observation that overall oral bioavailability of BCX-1777 was only 8.2%. This suggests that the BCX-1777 was absorbed slowly producing a sustained low concentration of BCX-1777, resulting in prolonged plasma concentrations of 2'-deoxyguanosine. After IV dosing, the BCX-1777 was cleared relatively quickly and the plasma 2'-deoxyguanosine tracked slightly behind the BCX-1777. IV administration of 5 mg/kg of BCX-1777 twice daily maintains the plasma 2'-deoxyguanosine concentrations at around 0.3 microg/ml (1.1 microM). These data indicate that oral and IV administration of BCX-1777 induce a rapid rise in 2'-deoxyguanosine and that oral dosing at 8.8 and 17.6 mg/kg are at least equivalent to 4.4 mg/kg IV in effecting the accumulation of 2'-deoxyguanosine. Finally, 2'-deoxyguanosine plasma concentration was maintained longer in the three highest oral doses in comparison to all IV doses.

Does a physically active lifestyle improve symptoms in women with irritable bowel syndrome?

It has been proposed that physical activity moderates physiological or psychological responses to chronic conditions. The purpose of this study was to determine if women with a chronic functional gastrointestinal (GI) disorder, irritable bowel syndrome, had less active lifestyles than healthy controls and to test whether active women with irritable bowel syndrome had less severe recalled or daily reports of GI, psychological, and somatic symptoms than inactive women with irritable bowel syndrome. Questionnaires were used to measure GI and psychological distress and somatic symptoms in 89 women who participated in this study. A daily symptom and activity diary was kept for one menstrual cycle. Women with irritable bowel syndrome were significantly less likely to be active (48%) than control women (71%) (X2 = 3.4, p = .05). Within the irritable bowel syndrome group, active women were less likely to report a feeling of incomplete evacuation following a bowel movement than inactive women (p < .04), yet active women did not have less severe recalled psychological or somatic symptoms than inactive women. Active women with irritable bowel syndrome reported less severe daily somatic symptoms, which were accounted for by a lower level of fatigue (p = .003), but not daily GI or psychological symptoms. These results suggest that physical activity may produce select symptom improvement in women with irritable bowel syndrome.

Alzheimer's disease cybrids replicate beta-amyloid abnormalities through cell death pathways

Alzheimer's disease (AD) is characterized by the deposition in brain of beta-amyloid (Abeta) peptides, elevated brain caspase-3, and systemic deficiency of cytochrome c oxidase. Although increased Abeta deposition can result from mutations in amyloid precursor protein or presenilin genes, the cause of increased Abeta deposition in sporadic AD is unknown. Cytoplasmic hybrid ("cybrid") cells made from mitochondrial DNA of nonfamilial AD subjects show antioxidant-reversible lowering of mitochondrial membrane potential (delta(gYm), secrete twice as much Abeta(1-40) and Abeta(1-42), have increased intracellular Abeta(1-40) (1.7-fold), and develop Congo red-positive Abeta deposits. Also elevated are cytoplasmic cytochrome c (threefold) and caspase-3 activity (twofold). Increased AD cybrid Abeta(1-40) secretion was normalized by inhibition of caspase-3 or secretase and reduced by treatment with the antioxidant S(-)pramipexole. Expression of AD mitochondrial genes in cybrid cells depresses cytochrome c oxidase activity and increases oxidative stress, which, in turn, lowers delta(psi)m. Under stress, cells with AD mitochondrial genes are more likely to activate cell death pathways, which drive caspase 3-mediated Abeta peptide secretion and may account for increased Abeta deposition in the AD brain. Therapeutic strategies for reducing neurodegeneration in sporadic AD can address restoration of delta(psi)m and reduction of elevated Abeta secretion.

Substrate-specific binding of hook-associated proteins by FlgN and FliT, putative chaperones for flagellum assembly

During flagellum assembly by motile enterobacteria, flagellar axial proteins destined for polymerization into the cell surface structure are thought to be exported through the 25-30 A flagellum central channel as partially unfolded monomers. How are premature folding and oligomerization in the cytosol prevented? We have shown previously using hyperflagellated Proteus mirabilis and a motile but non-swarming flgN transposon mutant that the apparently cytosolic 16. 5 kDa flagellar protein FlgN facilitates efficient flagellum filament assembly. Here, we investigate further whether FlgN, predicted to contain a C-terminal amphipathic helix typical of type III export chaperones, acts as a chaperone for axial proteins. Incubation of soluble radiolabelled FlgN from Salmonella typhimurium with nitrocellulose-immobilized cell lysates of wild-type S. typhimurium and a non-flagellate class 1 flhDC mutant indicated that FlgN binds to flagellar proteins. Identical affinity blot analysis of culture supernatants from the wild-type and flhDC, flgI, flgK, flgL, fliC or fliD flagellar mutants showed that FlgN binds to the flagellar hook-associated proteins (HAPs) FlgK and FlgL. This was confirmed by blotting artificially expressed individual HAPs in Escherichia coli. Analysis of axial proteins secreted into the culture medium by the original P. mirabilis flgN mutant demonstrated that export of FlgK and FlgL was specifically reduced, with concomitant increased release of unpolymerized flagellin (FliC), the immediately distal component of the flagellum. These data suggest that FlgN functions as an export chaperone for FlgK and FlgL. Parallel experiments showed that FliT, a similarly small (14 kDa), potentially helical flagellar protein, binds specifically to the flagellar filament cap protein, FliD (HAP2), indicating that it too might be an export chaperone. Flagellar axial proteins all contain amphipathic helices at their termini. Removal of the HAP C-terminal helical domains abolished binding by FlgN and FliT in each case, and polypeptides comprising each of the HAP C-termini were specifically bound by FlgN and FliT. We suggest that FlgN and FliT are substrate-specific flagellar chaperones that prevent oligomerization of the HAPs by binding to their helical domains before export.

The histological interpretation of high frequency cutaneous ultrasound imaging

BACKGROUND

High frequency, high resolution B-scan ultrasound imaging (US) has been used to assess skin. The use of US is limited because of difficulty interpreting the various echoes.

OBJECTIVES

To correlate the appearance of constant US echoes with histology in normal human skin.

METHODS

Normal skin from eight volunteers was scanned with US at a frequency of 20-25 MHz, prior to excision for clinical reasons. The echogenic bands of the skin and histological measurements of various layers were related statistically.

RESULTS

Three constant echogenic bands were identified, which correlated with skin surface, dermis, and subcutaneous fascia.

CONCLUSION

The correct interpretation of echogenic bands in normal skin allows for the US to be more reliably used for assessment of skin disorders.

The extraction-nonextraction dilemma as it relates to TMD

Extraction has been a controversial subject for as long as the specialty of orthodontics has existed. Some authors believe that the extraction of premolars leads to temporomandibular disorders. This occurs, they say, because the vertical dimension collapses. Concomitantly, over-retraction and retroclination of the incisors cause the facial profile to flatten, bring about premature anterior contacts, and distally displace the mandible and mandibular condyle. Numerous correlation studies in the dental literature do not support this contention. There appears to be no higher incidence of temporomandibular disorders in patients treated with the extraction of premolars than in nontreated patients or those treated without extractions. Analysis of premolar extraction cases reveals that there is no collapse of the vertical dimension; on the contrary, the vertical dimension is either maintained or slightly opened. Similarly, there is no evidence that premolar extraction causes undesirable flattening of the facial profile. The facial profile established during treatment is primarily the result of diagnosis and treatment mechanics. Excessive anterior interferences resulting in possible posterior condyle displacement are the result of treatment mechanics. When arches are leveled properly and space closure and overjet reduction are adequately controlled, there is no reason that such interferences should occur.

Expression of mRNA for the GATA-binding proteins in human eosinophils and basophils: potential role in gene transcription

The expression of the hematopoietic transcription factors GATA-1, GATA-2, and GATA-3 was studied in eosinophils and basophils. Eosinophils express mRNA for GATA-1, GATA-2, and GATA-3. Basophils express GATA-2 and GATA-3. Treatment of HL-60 eosinophilic sublines with either interleukin-5 or butyric acid increased the expression of GATA-1 mRNA concomitant with the expression of eosinophil-specific genes, whereas levels of GATA-2 mRNA remained relatively constant. The presence of mRNA for these proteins in eosinophils and basophils suggests that gene transcription in these lineages may be regulated by GATA-binding proteins.

Interactions of cell-surface galactosyltransferase with immunoglobulins

Detection of the activity of beta-1,4-galactosyltransferase (beta-1,4-GT) in suspensions of viable mouse hepatocytes, the human hepatoma cell line Hep G2, the human colonic adenocarcinoma cell line HT-29, the monocyte-like cell line U937, and human splenic B and T lymphocytes suggested the presence of beta-1,4-GT, in an enzymatically active form, on plasma membranes. The presence of beta-1,4-GT on cell surfaces was also indicated from the effect of trypsinization of live cells, which significantly reduced cell surface beta-1,4-GT activity, but did not affect the activity associated with cytoplasmic membranes. Furthermore, the presence of beta-1,4-GT on the cell surface was demonstrated by indirect immunofluorescence staining of cells with anti-beta-1,4-GT antibody. The detection of radioactivity in immunoglobulins (Ig) and their component chains after incubation with suspensions of intact cells in the presence of Mn2+ and UDP-[3H]-galactose, indicated that Ig molecules were galactosylated. In the absence of UDP-[3H]-galactose, beta-1,4-GT on cell surfaces, or immobilized on Sepharose-4B, formed stable complexes with galactose acceptors, including Ig. The efficiency of binding decreased in the order: J chain > alpha chain > mu chain > polymeric IgA2 > monomeric/polymeric IgA1 > IgM > IgG. Thus, beta-1,4-GT could act as a cell-surface receptor for Ig through a cation-dependent, lectin-like association of the beta-1,4-GT with the carbohydrate moieties of the Ig. This was confirmed by indirect surface immunofluorescence and radiolabeled ligand binding assays. The binding was inhibitable by EDTA, alpha-lactalbumin (in the presence of glucose), GlcNAc, or uridine 3',5'dialdehyde. At 37 degrees C, the apparent affinity constants and association rate constants of interaction between cell surface beta-1,4-GT on glutaraldehyde-fixed HT-29 and U937 cells and alpha 2 chain or monomeric IgA1 were in the range from 7.1 x 10(7) to 4.6 x 10(8) M-1 and from 1 x 10(5) to 3 x 10(6) M-1 s-1, respectively. The dissociation rate constants and half time of dissociation calculated from these data were in the range from 2.1 x 10(-2) to 5.0 x 10(-4) s-1 and from 33 to 1380 s, respectively. The number of alpha 2 or IgA1 molecules bound per HT-29 and U937 cell were in the range from 1.9 x 10(5) to 1.3 x 10(6). The binding of IgA by the cell surface beta-1,4-GT was not associated with internalization or the catabolic degradation of the ligand.

Interactions of galactosyltransferase with serum and secretory immunoglobulins and their component chains

Assay of the activity of beta-1,4-galactosyltransferase (beta-1,4-GT) revealed that in addition to serum, milk, colostrum, amniotic and cerebrospinal fluids and malignant effusions, this enzyme is present also in tears and saliva. Molecular-sieve chromatography of human colostral whey and serum and subsequent assay of beta-1,4-GT activity have shown that beta-1,4-GT was present as a free enzyme (55 kDa) and associated with components of larger molar mass. The elution pattern did not change when the chromatography was carried out in a buffer devoid of, or enriched with, Mn2+, a cofactor of beta-1,4-GT activity. However, the activity associated with the large molar mass components was absent when the chromatography was carried out in the presence of a chelating agent (EDTA). Analyses of the eluted material by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate (SDS-PAGE), and by immunodiffusion indicated that the major colostral component in beta-1,4-GT activity-containing fractions was secretory IgA (S-IgA); in addition, the beta-1,4-GT activity was detected in fractions that contained lactoferrin and alpha-lactalbumin. Interactions of beta-1,4-GT with S-IgA and lactoferrin in colostrum were also demonstrated by the detection of radioactivity in precipitin lines obtained by immunoelectrophoresis and autoradiography of the colostral whey after it had been incubated with UDP-[3H]-galactose. Furthermore, radioactively labeled S-IgA and alpha-chain were detected when colostral whey incubated with UDP-[3H]-galactose was analyzed by SDS-PAGE under non-reducing and reducing conditions, respectively. In serum, the beta-1,4-GT-binding components identified in fractions after molecular-sieve chromatography were IgG, IgA, IgM and transferrin. The binding of beta-1,4-GT to immunoglobulins (Ig) was also demonstrated by assaying the beta-1,4-GT activity associated with Sepharose-4B-immobilized Ig of various isotypes and molecular forms, which were incubated with colostral beta-1,4-GT in the presence of Mn2+. Beta-1,4-GT measured by enzyme activity was bound to these Ig in order: polymeric IgA2 > monomeric IgA1 = polymeric IgA1 = secretory IgA = pentameric IgM > IgG. Immobilized component chains, namely alpha, mu and J chains, bound beta-1,4-GT more effectively than native Ig. Incubation of the IgA1 myeloma protein with crude human colostral galactosyltransferase in the presence of UDP[3H]-galactose and Mn2+ resulted in galactosylation of both N- and O-linked carbohydrate side chains.(ABSTRACT TRUNCATED AT 400 WORDS)

Molecular cloning and characterization of human eosinophil Charcot-Leyden crystal protein (lysophospholipase). Similarities to IgE binding proteins and the S-type animal lectin superfamily

We have isolated and sequenced a 598-bp full length cDNA clone for the human Charcot-Leyden crystal (CLC) protein (eosinophil lysophospholipase), the unique and prominent constituent of human eosinophils and basophils that forms the hexagonal bipyramidal crystals classically observed in tissues and secretions from sites of eosinophil-associated inflammation. A 426-bp open reading frame encoded a 142-amino acid polypeptide with a predicted molecular mass of 16.5 kDa and isoelectric point of 7.28. The deduced amino acid sequence of CLC protein showed 20 to 30% similarity over regions of approximately 100 amino acids with the carboxyl-terminal domains of four IgE-binding proteins, including the 31-kDa human and rat IgE-binding proteins, the 35-kDa mouse carbohydrate binding protein (CBP35), Mac-2, the murine macrophage cell surface protein that is identical to CBP35, and the human homologue of Mac-2. These proteins are members of a superfamily of beta-galactoside binding S-type animal lectins, which includes a group of highly conserved 14-kDa lectins isolated from human lung, heart, placenta, bovine heart, chicken skin, mouse fibroblasts, and the electric organ of the electric eel; CLC protein also showed sequence similarities to these 14-kDa animal lectins, including conservation of 7 of 16 invariant amino acid residues thought to comprise the carbohydrate-binding domain of these proteins, with conservative amino acid changes at others; thus, CLC protein could potentially possess carbohydrate or IgE-binding activities. Northern analyses revealed an approximately 900-bp mRNA species that was present in peripheral blood eosinophils from patients with eosinophilia, basophils from patients with chronic myelogenous leukemia, and in HL-60 cells induced towards eosinophilic differentiation with B cell growth factor-II (IL-5) or granulocytic differentiation with DMSO, but was absent in neutrophils, monocytes, T cells, B cells, or HL-60 cells induced towards monocytic differentiation with vitamin D3. Southern analyses revealed a gene of approximately 5 to 6 kb in length. The cDNA clone and complete amino acid sequence data for CLC protein will facilitate structure-function analyses of its unusual hydrophobic properties, unique propensity for crystallization, lysophospholipase, and potential lectin-like activities.

Molecular cloning and characterization of human eosinophil Charcot-Leyden crystal protein (lysophospholipase). Similarities to IgE binding proteins and the S-type animal lectin superfamily

We have isolated and sequenced a 598-bp full length cDNA clone for the human Charcot-Leyden crystal (CLC) protein (eosinophil lysophospholipase), the unique and prominent constituent of human eosinophils and basophils that forms the hexagonal bipyramidal crystals classically observed in tissues and secretions from sites of eosinophil-associated inflammation. A 426-bp open reading frame encoded a 142-amino acid polypeptide with a predicted molecular mass of 16.5 kDa and isoelectric point of 7.28. The deduced amino acid sequence of CLC protein showed 20 to 30% similarity over regions of approximately 100 amino acids with the carboxyl-terminal domains of four IgE-binding proteins, including the 31-kDa human and rat IgE-binding proteins, the 35-kDa mouse carbohydrate binding protein (CBP35), Mac-2, the murine macrophage cell surface protein that is identical to CBP35, and the human homologue of Mac-2. These proteins are members of a superfamily of beta-galactoside binding S-type animal lectins, which includes a group of highly conserved 14-kDa lectins isolated from human lung, heart, placenta, bovine heart, chicken skin, mouse fibroblasts, and the electric organ of the electric eel; CLC protein also showed sequence similarities to these 14-kDa animal lectins, including conservation of 7 of 16 invariant amino acid residues thought to comprise the carbohydrate-binding domain of these proteins, with conservative amino acid changes at others; thus, CLC protein could potentially possess carbohydrate or IgE-binding activities. Northern analyses revealed an approximately 900-bp mRNA species that was present in peripheral blood eosinophils from patients with eosinophilia, basophils from patients with chronic myelogenous leukemia, and in HL-60 cells induced towards eosinophilic differentiation with B cell growth factor-II (IL-5) or granulocytic differentiation with DMSO, but was absent in neutrophils, monocytes, T cells, B cells, or HL-60 cells induced towards monocytic differentiation with vitamin D3. Southern analyses revealed a gene of approximately 5 to 6 kb in length. The cDNA clone and complete amino acid sequence data for CLC protein will facilitate structure-function analyses of its unusual hydrophobic properties, unique propensity for crystallization, lysophospholipase, and potential lectin-like activities.

Development of a didactic curriculum in science related to internal medicine

To best prepare physicians for productive careers in medicine and to instill in them a lifelong commitment to learning, a didactic curriculum for the sciences should be incorporated in training programs. Such a curriculum can be effective only if it can be woven into the fabric of clinical experiences and it is seen by the housestaff as relevant to their needs. A new level of commitment by our clinical teachers and a reassessment of the allocation of time for learning will be required.

Autoimmune disease and the major histocompatibility complex: therapeutic implications

A hereditary basis for the predisposition to several autoimmune diseases has long been suspected. A relationship between diseases and genes that encode various immune effector proteins is now recognized. Many of these genes are components of the major histocompatibility complex (MHC). Recent studies have provided insights into the mechanism by which MHC antigens can influence the tendency to the expression of autoimmune disease. These findings have also provided the rationale for designing specific immunotherapeutic interventions.

The Effects of Transition Metal Substitutions in the NbTe4-TaTe4 Charge-Density Wave System

At room temperature, the structures of TaTe4 and NbTe4 are modulated by the presence of a charge-density wave which in the former compound is commensurate with the parent lattice and in the latter incommensurate. In addition, a series of incommensurate mixed crystals ( Tal-xNbx )Te4 (0 ≤ x ≤) exist in which the modulation wavevector increases as a function of x. In this paper, we report the occurrence of a systematic variation in the period of the charge-density wave upon substitution of the transition metal elements Ti, Zr or V for either Nb or Ta. Electron diffraction experiments reveal that, in TaTe4, substitutions of Group 4 elements Ti and Zr result in an incommensurate modulation with a decrease in the modulation wavevector q. In NbTe4, substitutions of Ti or Zr also reduce q, in this case towards the commensurate value, and, at sufficiently high concentrations, a commensurate phase is stabilized at room temperature. Vanadium substitutions in NbTe4 result in a slight increase in q. Satellite dark-field images reveal the presence of defects in the modulation structures of the doped crystals. The above results are discussed in terms of the factors which determine the charge-density wave periodicity in the NbTe4-TaTe4 system.

The injustice of nonjudicial remedies to address childhood violence

The hypothesis that nonjudicial remedies such as mediation, negotiation, and "fair fighting" are effective tools for use in dealing with childhood violence has enjoyed some speculation in recent years. This work evaluates the hypothesis that such methods are unjust to the victims of such violence and that these methods must be abandoned in favor of appropriate punishment for aggressors.

The irrationality of the catharsis theory of aggression as justification for educators' support of interscholastic football

The notion that hostile feelings can be catharted from the psyche by playing football or other aggressive sports was virtually destroyed by behavioral scientists several decades ago. Nonetheless educators continue to support interscholastic football as a means of venting the aggressive emotions that supposedly characterize adolescence. This work examines this phenomenon, concluding that educators realize the sport actually increases aggression but hide behind the outdated hypothesis about catharsis to perpetuate the sport--an activity which gives them much pleasure.

The irrationality of interscholastic football as a means of preparing adolescents for adulthood

Logical analysis of meaning and data on football players, coaches, and support groups indicate interscholastic football is not preparation for adulthood.