Photoacoustic analysis of proteins: volumetric signals and fluorescence quantum yields

A series of proteins has been examined using time-resolved, pulsed-laser volumetric photoacoustic spectroscopy. Photoacoustic waveforms were collected to measure heat release for calculation of fluorescence quantum yields, and to explore the possibility of photoinduced nonthermal volume changes occurring in these protein samples. The proteins studied were the green fluorescent protein (GFP); intestinal fatty acid binding protein (IFABP), and adipocyte lipid-binding protein (ALBP), each labeled noncovalently with 1-anilinonaphthalene-8-sulfonate (1,8-ANS) and covalently with 6-acryloyl-2-(dimethylamino)naphthalene (acrylodan); and acrylodan-labeled IFABP and ALBP with added oleic acid. Of this group of proteins, only the ALBP labeled with 1,8-ANS showed significant nonthermal volume changes at the beta = 0 temperature (approximately 3.8 degrees C) for the buffer used (10 mM Tris-HCI, pH 7.5) (beta is the thermal cubic volumetric expansion coefficient). For all of the proteins except for acrylodan-labeled IFABP, the fluorescence quantum yields calculated assuming simple energy conservation were anomalously high, i.e., the apparent heat signals were lower than those predicted from independent fluorescence measurements. The consistent anomalies suggest that the low photoacoustic signals may be characteristic of fluorophores buried in proteins, and that photoacoustic signals derive in part from the microenvironment of the absorbing chromophore.     

Analysis of response competition in discriminated and nondiscriminated escape training of neonatal rats.

Examined the escape behavior of male (n = 180) and female (n = 40) albino Wistar neonatal rats in 4 experiments to determine whether (a) failure to increase speed of escape as turning decreases results from an increase in other superfluous activity; (b) turning does, in fact, compete with the escape reaction; and (c) a decrease in turning is a valid indicator of escape learning. In general, superfluous activity decreased in frequency at all ages, whereas only 7-11 day olds increased speed. At these ages, turning was inversely correlated with speed and trial, suggesting that turning does compete with the escape response and that a decrease in turning is indicative of learning. Failure of the 5 day olds to increase speed resulted from an increased duration of turning and reflected an inability to learn the direction of escape. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Two models of epileptic spike-and-wave rhythm in rats are differently influenced by ethosuximide

One hundred and thirty-seven consecutive patients who received bone marrow or peripheral blood stem cell transplantation were studied retrospectively to identify the risk factors for hepatic veno-occlusive disease (VOD). Of the 137 recipients, twenty (14.6%) patients were diagnosed with VOD using the McDonald's criteria. In these 20 patients with VOD, we analyzed various clinical parameters, including age, sex, HLA status, conditioning regimen, irradiation, immunosuppressive agents, mode of transplantation, history of hepatic dysfunction, pre-transplant hepatic and renal function, infectious episodes, antibiotics use, and serum viral titers. A history of hepatic dysfunction and low levels of pseudocholinesterase before transplantation were found to be statistically significant (P = 0.04 and 0.04). Low levels of pseudocholinesterase were significant by multivariate analysis using the logistic regression model (P = 0.02). These results suggest that pseudocholinesterase levels before transplant are important markers of VOD in patients receiving BMT.     

Can social behavior be influenced by events that we are unaware of?

Responds to the comments of K. A. Markus (see record 199810886-007), T. D. Nelson (see record 199810886-008), and M. C. Green et al (see record 199810886-008) referring to D. Kipnis's (see record 199707781-001) article analyzing social psychology's assumption that psychological states can explain social behavior. In the present reply, Kipnis addresses the arguments contained in the 3 aforementioned comments, and concludes with the assumption that the content of consciousness is explained by people's interactions with events in their world, and, further, that the understanding of social behavior will progress when theory and empirical research are extended to include societal events. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pulmonary distribution and efficacy of exogenous surfactant in lung-lavaged rabbits are influenced by the instillation technique

Surfactant bolus instillation has been reported to cause changes in arterial blood pressure (BP) and cerebral blood flow velocities which may increase the risk of intraventricular haemorrhage. To avoid these effects, slow tracheal infusion was evaluated as a possible alternative method of surfactant administration. Saline lung lavages were performed in 13 anesthetized and artificially ventilated adult rabbits to produce respiratory distress syndrome. Curosurf (CS, 200 mg/kg) labeled with 14C-dipalmitoyl-phosphatidylcholine (-DPPC) and/or red microspheres (RMS) was instilled into the trachea either as a single bolus (n = 8) or by infusion during 45 min via a side-channel within the wall of the tracheal tube (n = 5). An arterial cannula was placed for monitoring of blood gases and BP. To determine surfactant distribution, the lungs were cut into 60-70 pieces and radioactivity and/or the number of RMS were measured in each piece. The distribution of RMS was closely related to the distribution of 14C-DPPC (r = 0.96). Bolus instillation of CS led to a prompt and sustained increase in PaO2 (from < 10.5 to > 40 kPa within 2 min), a transient decrease in BP, and a reasonably homogeneous pulmonary surfactant distribution. Tracheal infusion of CS changed neither BP nor PaO2 during the observation period of 60 min. The pulmonary distribution of CS was extremely uneven after infusion. The distribution of exogenous surfactant and its effects on gas exchange are influenced by the instillation method. An inadequate instillation technique may add to the causes of "poor response" after surfactant replacement.     

Biphasic effects of alcohol on heart rate are influenced by alcoholic family history and rate of alcohol ingestion

The present study investigated cardiac response to acute alcohol challenge along the blood alcohol concentration (BAC) curve in two groups of young adult nonalcoholic men with (MFH) and without (FH-) multigenerational family histories of alcoholism, matched for drinking history. BACs and resting heart rate measurements were recorded every 10 min for 3 hr after ingestion of a 1.0 ml/kg dose of 95% USP alcohol at two different rates: one of 20 min (slow drinking) and the other of 5 min (fast drinking). Several analyses of variance were performed for each of the dependent measures [BAC and heart rate change from baseline (HRCH)]. A significant risk x BAC phase interaction emerged from the HRCH analysis, indicating that the MFH group was characterized by a significantly greater increase in resting heart rate along the ascending limb of the BAC curve. A significant risk x BAC phase x rate interaction indicated that, when alcohol was consumed at a faster rate, men with multigenerational family histories of alcoholism demonstrated a greater HRCH, which persisted throughout the BAC curve.     

Function and conformation of wild-type p53 protein are influenced by mutations in bovine leukemia virus-induced B-cell lymphosarcoma

The mutations of the p53 gene previously represented one of several genetic changes involved in the development of bovine leukemia virus (BLV)-induced lymphosarcoma, while the effects of these mutations on the function of p53 are unknown. We identified four mutations of p53 gene in BLV-infected cattle with lymphosarcoma and demonstrated clearly the existence of two functionally distinct groups of mutants: (i) the mutant forms with substitutions at codons 241 and 242, which were mapped within an evolutionally conserved region and corresponded to the human "hot-spot" mutations, had completely lost the capacities for transactivation and growth suppression and gained transdominant repression activity in p53-null SAOS-2 cells; and (ii) the mutations at codons 206 and 207 were located outside the evolutionally conserved regions. These mutants partially retained the capacity for transactivation and growth suppression and failed to inhibit the transactivation activity of coexpressed wild-type p53, instead showing an enhancement of this activity. In addition, protein analysis using an antibody specific for the mutant form revealed that the mutations at codons 206 and 242 induced a "mutant" conformation of the bovine p53 proteins. Collectively, these results show that mutations of p53 gene in BLV-infected cattle with lymphosarcoma can potentially alter its physiological function and may play an important role in BLV-induced leukemogenesis.     

Ultrasonic vocalizations are elicited from rat pups in the home cage by pentylenetetrazol and U50,488, but not naltrexone.

Although isolated rat pups emit ultrasonic vocalizations (USVs), those kept warm and undisturbed in the home cage with their littermates seldom do. Drugs were administered to 10-day-old Wistar rat pups in the home cage to determine whether pharmacological agents can elicit USVs in this familiar environment. Ss were injected with U50,488, a highly selective kappa opioid agonist; pentylenetetrazol (PTZ), an anxiogenic drug that binds at the GABA-benzodiazepine receptor complex; or naltrexone (NLX), an opiate receptor blocker, and then were returned to their littermates in the home cage. U50,488 increased USV and activity levels, lowered body temperature, and disrupted contact with littermates. PTZ raised activity levels but had a smaller effect on vocalization rates and did not alter temperature or contact with littermates. Behavioral measures and body temperature were unchanged by NLX. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Repeated tests of intermale aggression in mice (Mus musculus) are influenced by housing and test conditions.

Young adult male Binghamton Heterogenous (HET) mice were housed either individually or in groups of four, in two-tiered cages for 11 days before their agonistic behavior was observed. Pairs of male mice were tested 3 min each day for 9 consecutive days. Agonistic behavior was observed in two-tiered cages in which there were either clean pine shavings or shavings soiled by young adult female HET mice. Housing and shaving conditions interactively influenced aggression observed over the course of testing. That is, when individually housed mice were tested with clean shavings and when group-housed mice were tested with female-soiled shavings, agonistic behavior decreased over days, but when isolated mice were tested in soiled shavings and when group-housed mice were tested in clean shavings, aggression increased over the course of the 9-day test period. (PsycINFO Database Record (c) 2010 APA, all rights reserved)