Nicotine's role in smoking: An analysis of nicotine regulation.

Nicotine regulation refers to a smoker's maintenance of a characteristic level of nicotine in the body. It implies that changes in smoking behavior (i.e., compensation) will accompany either increases or decreases in nicotine availability. Research on regulation has been inconclusive because of (a) a failure to distinguish between regulation and compensation, (b) the use of indirect rather than direct measures of nicotine exposure, and (c) a number of methodological problems. The present review addresses these issues by (a) clarifying definitional ambiguities, (b) presenting a classification strategy that differentiates the indirect and direct evidence for regulation, (c) quantifying the direct evidence, and (d) discussing measurement and methodological problems. (76 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Inhibition of phospholipase D activity by fodrin. An active role for the cytoskeleton

Phospholipase D (PLD) is a major enzyme implicated in important cellular processes such as secretion and proliferation. The knowledge of its regulation is essential to understand the control of these phenomena. Several proteins activating PLD have been described in the last years. In this report, we chromatographed bovine brain cytosolic proteins to identify fodrin, the non-erythroid spectrin, as the first described inhibitor of PLD. A cytosolic fraction with an inhibitory effect on PLD activity loses its capacity after immunoprecipitation of fodrin. Moreover, at 1 nM, purified fodrin blocks fully and quickly PLD activity, whatever the stimuli used. In contrast, fodrin has no effect on adenylate cyclase activity. Fodrin-analogous proteins like dimeric or tetrameric erythroid spectrin have the same inhibitory effect on PLD, at higher concentrations. Other cytoskeletal proteins, actin and vimentin, are inefficient on PLD inhibition. The mechanisms implicated in PLD modulation such as post-translational modifications of fodrin and the role of small G-proteins on the cytoskeleton regulation are discussed. In conclusion, this study reveals that fodrin is involved in the control of PLD activity, suggesting that the cytoskeleton could have an active role in control of secretion and proliferation.     

An input-process-output analysis of influence and performance in problem-solving groups.

Member characteristics and social processes that determine influence in problem-solving groups were examined. University students completed a non-eureka intellective task—the Desert Survival Situation—both individually and in small groups. LEVEL-adjusted correlations and EQS structural modeling revealed that the extent of talking was predicted by dominance and confidence, but not actual expertise. Perceived expertise was most closely predicted by the extent of talking. Perceived expertise mediated the relation between talking and influence. Groups attempted to base decisions on expertise, but were not proficient at recognizing expertise. Additional analyses, which examined the impact of 8 influence tactics, indicated that the tactics of reason and autocracy predicted perceived expertise. Group performance was related to level of member expertise and recognition of expertise. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An experimental analysis of role behavior.

"Six Ss, equated for age, conformance of expectation of the role of daughter in contemporary American culture, and congruence of self with the daughter role, each engaged in brief enactment of the role of daughter. The Ss varied systematically in role-taking aptitude as assessed by a simple face-valid As-If procedure." The following hypotheses are tested and supported by the data: "role-taking aptitude and validity of role-enactment are positively correlated; role-taking aptitude and self-constancy following role-enactment are negatively correlated; the shift in self-conception following role-enactment is in part, a function of the specific role enacted; and, finally, role-taking aptitude and a social adjustment variable are positively correlated." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Social phobia: An analysis of possible developmental factors.

Sixty-eight individuals with specific or generalized social phobia and 25 normal controls were assessed for presence of a family history of anxiety, childhood shyness, traumatic conditioning experiences, neuroticism, and extraversion. Subtype differences emerged, including significantly greater neuroticism and a more frequent history of shyness in the generalized subtype. Those with the generalized subtype also had significantly lower extraversion scores, and those with the specific subtype had a significantly higher frequency of traumatic conditioning episodes. Together, traumatic conditioning and childhood shyness predicted the presence of social phobia, although other unidentified factors also appeared to be relevant. The results are discussed in terms of potentially different modes of onset for the subtypes of social phobia and the role of neuroticism and introversion in the development of the disorder. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The molecular structure of mitochondrial contact sites. Their role in regulation of energy metabolism and permeability transition

Contact sites between the outer and peripheral inner membrane of mitochondria are involved in protein precursor uptake and energy transfer. Hexokinase and mitochondrial creatine kinase could be attributed by different techniques to the energy transfer contacts. Kinetic analyses suggested a functional interaction between the kinases, outer membrane pore protein, and inner membrane adenylate translocator (ANT). This suggestion was strongly supported by isolation of hexokinase and creatine kinase complexes that were constituted of kinase oligomers, porin and ANT. Phospholipid vesicles carrying reconstituted kinase-porin-ANT complexes enclosed internal ATP in contrast to vesicles containing free porin only. This indicated that unspecific transport through porin was regulated by its interaction with a specific antiporter, ANT. A direct interaction between porin and ANT in the hexokinase complex conferred the reconstituted system with permeability properties reminiscent of the mitochondrial permeability transition (PT) pore. In the creatine kinase complex this interaction between porin and ANT was replaced by contact of both with the kinase octamer. Thus PT-pore-like functions were not observed unless the creatine kinase octamer was dissociated, suggesting that the ANT was locked in the antiporter state by interaction with the octamer. Indeed, reconstituted pure ANT showed PT-pore-like properties concerning Ca2+ sensitivity. However, as cyclophilin was missing, sensitivity against cyclosporin was not observed.     

Control of respiration in newborn babies. IV. Rib cage stability and respiratory regulation

The recordings from an earlier study regarding the respiratory depth and rate changes induced by exposure to 4% CO2 in air in 13 babies with PM age varying between 32 and 43 weeks were reexamined with regard to the pattern of thoracic abdominal breathing excursion in breathing immediately prior to the CO2 exposure and the type of response induced. The pattern was called "stable" when the thoracic breathing excursions were in phase and congruent with the abdominal ones. When the thoracic excursions in comparison with the abdominal excursions were totally inverted, or incongruous but in phase, or rapidly varying between those two, the pattern was called "unstable". "Unstable" pattern of the breathing prior to the CO2 exposures was followed in an incidence of 60% by the type of response to CO2 which is characterized by a prompt rate increase (the "Type B" response) and only in 16% by the type characterized by an increased breathing amplitude (the "Type A" response). When the excursion pattern of the breathing prior to the CO2 exposures was "stable" "Type A" responses were induced in 59% and "Type B" responses in only 14%. The excursion pattern present when a baby is exposed to 4% CO2 thus seems to affect the type of respiratory depth and rate changes achieved. With increasing postmenstrual age the excursion pattern of the spontaneous breathing is more often "stable" and respiratory depth and rate changes of the "Type B" induced by CO2 less common. The variabilities of the breathing seen preferably in the preterm baby regarding regularity, rate and tidal volumes (as they could be approximated by the registration methods used) were noted most when the excursion pattern was "unstable". The results can be hypothetically interpreted to indicate a dynamic interaction between the thoracic wall and pulmonary mechanoreceptor systems of respiratory regulation. The decreasing variability of the breathing seen with increasing maturation in the baby could be explained by an increasing maturation of the neuromuscular ability to provide stability to the rib cage which would act stabilizing on the pulmonary vagal afferent input to the respiratory center.     

The development of hyperventilation in patients with chronic heart failure and Cheyne-Strokes respiration: a possible role of chronic hypoxia

AIM: To analyze the relationship between daytime respiratory and cardiac function in patients with compensated chronic heart failure (CHF) with and without periodic breathing (PB) or Cheyne-Stokes respiration (CSR). PATIENTS: We studied 132 patients (female, 13%; mean age, 53+/-8 years; body mass index, 25.9+/-3.5 kg/m2; left ventricular ejection fraction <40%; 23% in New York Heart Association class I, 43% in class II, and 34% in class III-IV). METHODS: Measurement of pulmonary function and blood gases, hemodynamic evaluation, analysis of breathing profile, echocardiography, recording of ECG, beat-to-beat arterial oxygen saturation, and respiration during spontaneous breathing. RESULTS: Fifty-eight percent of patients showed PB or CSR. Patients with PB or CSR have greater cardiac function impairment. Mean values of lung volumes and PaO2 were similar in the three groups of patients considered. In contrast, patients with PB or CSR had an increased minute ventilation and reduced PaCO2 values. Interestingly, patients with PB or CSR had lower values of arterial content of O2 and systemic oxygen transport (SOT) than patients with a normal breathing pattern (SOT, 394+/-9.8, 347+/-9.6, 438+/-11 mL of O2/min/m2, respectively; analysis of variance p<0.001). Weak correlations were found among lung volumes, blood gases, and cardiac function parameters: ie, vital capacity was correlated inversely with pulmonary capillary wedge pressure (PCWP) (-0.25; p<0.05); PaCO2 with PCWP (r=0.26; p<0.05), lung-to-ear circulation time (LECT) (r=-0.4; p<0.05), SOT (r=-0.33; p<0.0001), and cardiac index (CI) (r=0.27; p=0.003). Multiple regression analyses showed that arterial PCO2 was significantly correlated with SOT, LECT, and CI (r=0.51; r2=0.26; p<0.000001); the correlation became stronger considering only CSR patients (r=0.64; r2=0.4; p<0.001). CONCLUSIONS: Our study shows that patients with daytime breathing disorders have chronic hypocapnia. A reduced SOT may be one of the stimuli determining increased minute ventilation in these patients.     

An analysis of concentration profiles for fluxes,diffusion depths,and zero-flux planes in multicomponent diffusion

Concentration profiles developed during isothermal, multicomponent diffusion for a single-phase, solid-solid diffusion couple are expressed on the basis of a relative concentration variable for each component and analyzed for the determination of interdiffusion fluxes. The individual concentration profiles intersect at a common cross-over composition where the relative concentrations of all components are identical. New relations are developed for describing internal consistency among the concentration profiles of the various components. A link is made between the cross-over composition and the depths of the diffusion zone on either side of the Matano plane for a diffusion couple. The cross-over composition is interpreted as the average relative concentration of each component over the diffusion zone. The identification of a zero-flux plane from concentration profiles is also described. The analysis offers several advantages in presenting as well as checking the self-consistency of results as illustrated with a single phase Cu-Ni-Zn diffusion couple annealed at 775 °C.     

Removals of hydrogen peroxide and hydroxyl radical by thiol-specific antioxidant protein as a possible role in vivo

Thiol-specific antioxidant protein (Protector Protein; PRP) from Saccharomyces cerevisiae was found to remove hydrogen peroxide and hydroxyl radical in the presence of dithiothreitol (DTT). Without DTT as a reducing equivalent, the antioxidant protein did not show the activities for destroying hydrogen peroxide and hydroxyl radical. N-ethylmaleimide (NEM) was observed to prevent the PRP from both removing hydrogen peroxide and protecting the cleavage of DNA. These observations suggest that the sulfhydryl of cysteine in PRP could function as a strong nucleophile to attack and destroy H2O2 and .OH.     

The possible involvement of LH/hCG induced mitochondrial proteins in the regulation of steroidogenesis in bovine luteal cells

Beta-2-microglobulin (B2M) forms the small invariable light chain subunit of class I HLA antigens on the cell membrane of all nucleated cells. During the continuous turnover of the HLA molecules, B2M is shed from the cell membrane into blood. Lymphocytes are the main source of serum free B2M. Serum B2M concentration is increased in renal diseases, various malignant diseases and some inflammatory and autoimmune disorders. In lymphatic malignancies serum B2M has significant prognostic value. Interferons (IFNs) have the ability to enhance the expression of class I and II histocompatibility antigens. Accordingly, IFNs cause a rise in formation and release of B2M. Currently, treatment with IFN alpha is used in diseases, like multiple myeloma, where serum B2M measurements are used to assess tumor burden. We have measured serum B2M levels during IFN alpha treatment in patients with both multiple myeloma and chronic myeloproliferative diseases, and IFN alpha caused a significant increase in serum B2M. It can be concluded that use of IFN alpha abolishes the value of serum B2M as an indicator of disease activity.     

Overview no. 84: An analysis of diffusion and diffusional creep in stoichiometric and hyperstoichiometric uranium dioxide

Diffusion and diffusional creep mechanisms are analyzed for stoichiometric and hyperstoichiometric UO_2+x. A variety of criteria are used in the evaluation based on a critical review of literature data:

• 1.(1) agreement between measured tracer diffusivities and those calculated from creep rates or reported for sintering;
• 2.(2) self-consistent values of the activation energies for various diffusion controlled processes;
• 3.(3) self-consistent and theoretically reasonable stoichiometry dependencies for self-diffusion, creep, and sintering;
• 4.(4) a satisfactory grain size correlation in the diffusional creep regime.

It is conclusively shown that Coble creep is the dominant mechanism for any practical grain size where viscous creep processes are diffusion limited. This conclusion applies at stoichiometric and all oxygen-rich compositions. At low stress interface controlled diffusional creep is an important mechanism. A compilation of the “best” set of uranium grain boundary and lattice diffusivities is presented for the entire range of UO_2+x stoichiometries.     

The functional role of CrkII in actin cytoskeleton organization and mitogenesis

Crk is a member of a family of adapter proteins predominantly composed of Src homology 2 and 3 domains, whose role in signaling pathways is presently unclear. Using an in situ electroporation system which permits the introduction of glutathione S-transferase (GST) fusion proteins into cells, we found that c-CrkII bound to p130(cas), but not to paxillin in serum-starved rat-1 fibroblasts overexpressing the human insulin receptor (HIRc cells) in vivo. 17 nM insulin stimulation dissociated the binding of c-CrkII to p130(cas), whereas 13 nM insulin-like growth factor-I, 16 nM epidermal growth factor (EGF), and 10% serum each showed little or no effect. We found that stress fiber formation is consistent with a change in the p130(cas).c-CrkII interactions before and after growth factor stimulation. Microinjection of either GST-Crk-SH2 or -Crk-(N)SH3 domains, or anti-Crk antibody each inhibited stress fiber formation before and after insulin-like growth factor-I, EGF, and serum stimulation. Insulin stimulation by itself caused stress fiber breakdown and there was no additive effect of microinjection. Microinjection of anti-p130(cas) antibody also blocked stress fiber formation in quiescent cells. Microinjection of the Crk-inhibitory reagents also inhibited DNA synthesis after insulin-like growth factor-I, EGF, and serum stimulation, but not after insulin. These data suggest that the complex containing p130(cas).c-CrkII may play a crucial role in actin cytoskeleton organization and in anchorage-dependent DNA synthesis.     

Cesium ions influence cultured cell behavior by modifying specific subcellular components: the role of membranes and of the cytoskeleton

The exposure of the epidermoid cell line A431 to different concentrations of CsCl was assessed using different methodological approaches. Two different effects were detected depending upon the concentration of the agent: at low concentrations, cell modification was represented mainly by a very pronounced cell flattening and an alteration of the cell-to-cell contacts, interpreted as an increase in cell adhesion. At higher concentrations, a clear pathogenic effect was observed that allowed the formulation of the hypothesis that specific mechanisms of toxicity at the subcellular level involving mitochondrial and cytoskeletal function can exist. In addition, membrane order parameters, as detected by electron paramagnetic resonance (EPR) spectroscopy, displayed a dose-dependent increase in membrane rigidity. Results reported here seem to suggest that cesium ions can enter the cell, modify plasma membrane integrity and alter some specific cytoplasmic components, e.g. the cytoskeleton. Considering that environmental contamination by cesium as a result of radioactive fallout is of major importance and that few data are available thus far on this matter, this study provides evidence for the possible mechanisms of action of the non-radioactive form of this ion in cells.     

Psychological adjustment and the worker role: An analysis of occupational differences.

How does the place of worker role on his personal adjustment vary from nonmanual to manual type of employment? "301 Ss, all between the ages of 55 and 65, were divided into two occupational statuses, nonmanual and manual workers. The former status included 116 of the managerial, supervisory, professional-technical, and clerical-sales personnel of a Midwestern oil refinery, while the latter status contained 185 of that company's skilled, semiskilled, and unskilled laborers. Both groups were then treated as separate populations in an analysis of the worker role as it related to personal adjustment, social adjustment, and job satisfaction… . the personal adjustment of nonmanual employees was not significantly related with their work-role competency, while the personal adjustment of manual employees showed a significant correlation with the worker role variable… . It was therefore concluded that the degree to which personal adjustment is related with the worker role depends to some extent upon an employee's occupational status." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of the cytoskeleton in polarity and morphogenesis of algal cells

The significance of the anterior capsulolabral complex in anterior shoulder instability is well established. In cases of detachment of the ventrocaudal capsulolabral complex, definitive stability can be achieved only by operative refixation. These structures can only be imaged by invasive and cost-intensive methods such as MR arthrography and CT arthrography. We introduce an examination by ultrasonography: a 7.5 MHz linear transducer is used. The patient is in the supine position and both arms are abducted and externally rotated. The transducer is placed in the longitudinal direction, parallel to the border of the pectoral muscle with a ventrocaudal tilt. From March 1992 to October 1994 a number of 88 patients were preoperatively subjected to ultrasound examination before operative stabilization or arthroscopy. Eighty-three of the results were evaluable. Sixty-nine of the examinations showed evidence of detachment of the ligaments; 68 of them were confirmed operatively; 14 of the examinations showed no evidence of detachment; 12 of these results proved true operatively (sensitivity: 97.7%, specificity 92.3%). The sonographic procedure introduced seems to be valuable in detecting the Bankart lesion in anterior instability of the shoulder.     

Inability to detect Chlamyodomonas microtubule assembly in vitro: possible implications to the in vivo regulation of microtubule assembly

It has been demonstrated that the in vitro assembly of microtubules from Chlamydomonas preparations does not occur under a wide range of conditions, including those efficacious for mammalian brain tubulin. This incompetence of Chlamydomonas extracts to form microtubules is independent of the tubulin concentration, the presence of added nucleotides or an added seed, temperature, or the concentration of divalent cation. However, an amorphous aggregate was observed under certain conditions, who composition was mainly tubulin. The in vitro reassembly of microtubules in gerbil brain extracts is inhibited by Chlamydomonas preparations. Fractionation of the Chlamydomonas extracts by column chromatography suggests that the inhibitory component is Chlamydomonas tubulin itself. The mechanism of this inhibition is unknown, but reassembly experiments indicate that the 2 types of tubulins cannot copolymerize. We suggest that the Chlamydomonas tubulin, derived from a cytoplasmic pool, requires to be activated prior to its in vivo polymerization into microtubules.     

Analysis of the pesticin receptor from Yersinia pestis: role in iron-deficient growth and possible regulation by its siderophore

We have sequenced a region from the pgm locus of Yersinia pestis KIM6+ that confers sensitivity to the bacteriocin pesticin to certain strains of Escherichia coli and Y. pestis. The Y. pestis sequence is 98% identical to the pesticin receptor from Yersinia enterocolitica and is homologous to other TonB-dependent outer membrane proteins. Y. pestis strains with an in-frame deletion in the pesticin receptor gene (psn) were pesticin resistant and no longer expressed a group of iron-regulated outer membrane proteins, IrpB to IrpD. In addition, this strain as well as a Y. pestis strain with a mutation constructed in the gene (irp2) encoding the 190-kDa iron-regulated protein HMWP2 could not grow at 37 degrees C in a defined, iron-deficient medium. However, the irp2 mutant but not the psn mutant could be cross-fed by supernatants from various Yersinia cultures grown under iron-deficient conditions. An analysis of the proteins synthesized by the irp2 mutant suggests that HMWP2 may be indirectly required for maximal expression of the pesticin receptor. HMWP2 likely participates in synthesis of a siderophore which may induce expression of the receptor for pesticin and the siderophore.