Psychic determinism versus freedom of choice: Order versus chaos.

In response to L. E. Tyler's (see record 1974-25495-001) article on a hopeful psychology, S. Morganstein proposed that orderly thought or behavior, based on a sequence of choices, is either determined by the external environment or a combination of the latter plus internal causes or control. The author submits that a psychologist who recognizes his/her own motivations is freer than one who judges by what society deems profitable. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fluconazole versus Candida albicans: a complex relationship

A murine model of systemic candidiasis was used to assess the virulence of serial Candida albicans strains for which fluconazole MICs were increasing. Serial isolates from five patients with 17 episodes of oropharyngeal candidiasis were evaluated. The MICs for these isolates exhibited at least an eightfold progressive increase from susceptible (MIC < 8 microg/ml; range, 0.25 to 4 microg/ml) to resistant (MIC >/= 16 microg/ml; range, 16 to >/=128 microg/ml). Virulence of the serial isolates from three of five patients showed a more than fivefold progressive decrease in the dose accounting for 50% mortality and was associated with development of fluconazole resistance. Low doses of fluconazole prolonged survival of mice infected with susceptible yeasts but failed to prolong survival following challenge with a resistant strain. In addition, a decreased burden of renal infection was noted in mice challenged with two of the three resistant strains. This was consistent with reduced virulence. Fluconazole did not further decrease the level of infection. In the isolates with a decrease in virulence, two exhibited overexpression of CDR, which encodes an ABC drug efflux pump. In contrast, serial isolates from the remaining two patients with the development of resistance did not demonstrate a change in virulence and fluconazole remained effective in prolonging survival, although significantly higher doses of fluconazole were required for efficacy. Resistant isolates from both of these patients exhibited overexpression of MDR. This study demonstrates that decreased virulence of serial C. albicans isolates is associated with increasing fluconazole MICs in some cases but not in others and shows that these low-virulence strains may not consistently cause infection.     

Trigeminal nuclear complex of the ferret: anatomical and immunohistochemical studies

In order to establish the ferret as an animal model for studies of trigeminal pain, we describe the cytoarchitecture and neurochemistry of the trigeminal nuclear complex in the ferret and compare them to those of the cat and rat. The complex was divided as previously described, but the ferret differed in the extent of the nuclear boundaries. The neuroanatomical istribution of substance P-, calcitonin gene-related peptide-, galanin-, enkephalin-, serotonin-, somatostatin-, neuropeptide Y-, and neurotensin-immunoreactivity was determined throughout the rostrocaudal extent of the complex. In subnucleus caudalis, substance P-, calcitonin gene-related peptide-, enkephalin-, serotonin-, somatostatin-, neuropeptide Y-, and galanin-immunoreactivity was densest in laminae I and II. In subnucleus interpolaris, immunoreactivity for all the above neurochemicals was most dense along the lateral border and the ventral third of the caudal part of the subnucleus. Enkephalin-immunoreactive cell bodies were present in subnucleus caudalis and interpolaris. In subnucleus oralis, labelling for substance P, calcitonin gene-related peptide, galanin, enkephalin, and serotonin was most prominent in the dorsomedial part of the subnucleus. Somatostatin-immunoreactive cell bodies were distributed throughout the spinal nucleus. Labelling of serotonin, substance P, calcitonin gene-related peptide, galanin, enkephalin, and somatostatin was present in the main sensory nucleus. The motor nucleus contained fibers immunoreactive for substance P, enkephalin, serotonin and neuropeptide Y, and cell bodies immunoreactive for calcitonin gene-related peptide. The majority of neurotensin-immunoreactivity was found at the level of subnucleus caudalis, where it was densest in the trigeminal extension of the lateral cervical nucleus. The distribution of peptides in this species throughout the spinal nucleus is consistent with the notion that all the subnuclei may be involved in the processing of nociceptive inputs.     

Continuous versus discrete information processing: Modeling accumulation of partial information.

Comments on D. E. Meyer and colleagues' (see record 1988-28535-001) new technique for examining the time course of information processing, which is a variant of the response signal procedure: On some trials Ss are presented with a signal that requires them to respond, whereas on other trials they respond normally. The accuracy of guesses based on partial information can be determined by using the data from the regular trials and a simple race model to remove the contribution of fast-finishing regular trials from signal trial data. This analysis shows that the accuracy of guesses is relatively low and is either approximately constant or grows slowly over the time course of retrieval. Myers et al argue that this pattern of results rules out most continuous models of information processing. But the analyses presented in the present article show that this pattern is consistent with several stochastic RT models: the simple random walk, the runs, and the continuous diffusion models. The diffusion model is assessed with data from a new experiment using the study–test recognition memory procedure. Fitting the diffusion model to the data from regular trials fixes all parameters of the model except one (the signal encoding and decision parameter). With this one free parameter, the model predicts the observed guessing accuracy. It is concluded that the results obtained from Meyer and colleagues' new technique give qualitative support to some stochastic models and quantitative support to the continuous diffusion model. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Modeling the cell cycle of complex populations

A model of cell cycle kinetics of complex populations is developed, by using systems of difference equations, and simulated on the computer. This model provides theoretical curves of labeled mitoses (PLM) percentage, labeling index and grain count histograms for different time intervals after 3H-thymidine administration. The PLM curve corresponding to a mixed population is a weighed sum of PLMs for populations, comprising the mixture, the weights being determined by parameters of populations. The model appeared to give a good agreement with the PLM curves obtained elsewhere.     

Structure of a mycobacterial polysaccharide-fatty acyl-CoA complex: nuclear magnetic resonance studies

MMP, a linear alpha 1 leads to 4 linked polymer of 3-O-methylmannose, regulates the fatty acid synthetase from Mycobacterium smegmatis by forming stoichiometric complexes with the long-chain acyl-CoA synthetase products. In agreement with previous proposals [Bloch, K. (1977) in Advances in Enzymology and Related Areas of Molecular Biology, ed. Meister, A. (Wiley, New York), Vol. 45, pp. 1-84], nuclear magnetic resonance studies show that the polysaccharide, a random coil in its free form, undergoes a major conformational transition upon enclosing long-chain acyl-CoA. The polysaccharide, probably in helical conformation in the complexed form, interacts with both the paraffinic chain and the CoA moieties of the included fatty acyl thioester.