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PubMed2004

Analysis of solution nonideality of a pseudomorphic drug system through a comprehensive thermodynamic framework for the design of a crystallization process.

Solutions of a semipolar drug belonging to the alpha(V) beta(iii) integrin antagonist class of compounds were studied in a comprehensive thermodynamic framework. The solubility of two pseudomorphic forms (an anhydrate and a monohydrate) was measured at several temperatures and various solvent mixtures of acetonitrile and water. Both forms displayed a "bell"-shaped solubility behavior as a function of cosolvent composition. Thermodynamic framework used to analyze the data comprised van't Hoff and enthalpy-entropy compensation analyses. The two pseudomorphs exhibited linear temperature dependence from 25 to 65 degrees C at all solvent compositions (i.e., ideal behavior with temperature for fixed solvent composition). Plots of enthalpy of solublization and Gibbs free energy showed two distinct regions with contrasting thermodynamic, and consequently, underlying structural properties (indicating non-deal behavior with solvent composition for a fixed temperature). Solubility increased due to entropy effects in the acetonitrile rich region, whereas enthalpy effects dominated solublization in the water-rich region. Quantification of this phenomenon by plotting DeltaH versus DeltaG showed considerable nonlinearity, and that the two regions were separated by a significant discontinuity-a trend rarely seen before in the literature. The reason behind this behavior is believed to be due to the complex interactions in the solution of the drug in water acetonitrile solvent system. A very significant aspect of the comprehensive thermodynamic analysis is that it helped explain the puzzling feature of the data, which showed that the free energy of phase transformation between the two pseudomorphic forms for a given temperature was not independent of the solvent composition. The resulting explanation has major consequences for crystallization process development.

Algorithms↗

PubMed2004

A comprehensive picture of non-site specific oxidation of methionine residues by peroxides in protein pharmaceuticals.

In this article, a comprehensive picture of the oxidation of protein pharmaceuticals by peroxides is developed based on our earlier computational and experimental studies. We propose a new mechanism, the water-mediated mechanism, for the oxidation of methionine residues, and it has been shown to satisfy all available experimental data including new data reported here. Based on the water-mediated mechanism, we found a structural property, average 2-shell water coordination number, that correlates well to the relative rates of oxidation of methionine groups. We used this to study the oxidation of granulocyte colony-stimulating factor (G-CSF) and 1-34 human parathyroid hormone hPTH(1-34). We believe that this comprehensive picture should aid researchers in the pharmaceutical sciences to develop solvent formulations for therapeutic proteins in a more rational way.

Binding Sites↗

PubMed2004

Analysis of sulfur-containing compounds in crude oils by comprehensive two-dimensional gas chromatography with sulfur chemiluminescence detection.

This paper reports an analytical method for separating, identifying, and quantifying sulfur-containing compounds in crude oil fraction (IBP-360 degrees C) samples based on comprehensive two-dimensional gas chromatography coupled with a sulfur chemiluminescence detector. Various sulfur-containing compounds and their groups were analyzed with one direct injection. 3620 peaks were detected including 1722 thiols/thioethers/ disulfides/1-ring thiophenes, 953 benzothiophenes, 704 dibenzothiophenes, and 241 benzonaphthothiophenes. The target sulfur compounds and their groups were identified based on the group separation feature and structured retention of comprehensive two-dimensional gas chromatography as well as standard substances. The quantitative analysis of major sulfur-containing compounds and total sulfur was based on the linear response of the sulfur chemiluminescence detector using the internal standard method. The sulfur contents of target sulfur compounds and their groups in 4 crude oil fractions were also determined. The recoveries for standard sulfur-containing compounds were in the range of 90-102%. The quantitative result of total sulfur in the Oman crude oil fraction sample was compared with those from ASTM D 4294 standard method (total S by X-ray fluorescence spectrometry), the relative deviation (RD%) was 4.2% and the precision of the method satisfactory.

Journal Article↗

PubMed2004

Assessment by monte carlo simulation of thermodynamic correlation of retention times in dual-column temperature programmed comprehensive two-dimensional gas chromatography.

The correlation of retention times in comprehensive two-dimensional gas chromatography caused by correlation of enthalpy and entropy changes between two stationary phases, methylsilicone and poly(ethylene glycol), was examined using commercial GC software and in-house Monte Carlo simulation. The enthalpy change, deltaH0, and entropy change, deltaS0, of 93 compounds were predicted from isothermal one-dimensional gas chromatograms predicted by the software. These values then were mimicked by Monte Carlo simulation, which removed the strong correlation of deltaH0 and modest correlation of deltaS0 between the two phases. Retention times in a comprehensive two-dimensional gas chromatogram (GC x GC) and in simulations of it were predicted for typical dual-capillary temperature-programmed conditions using the actual, correlated values of deltaH0 and deltaS0 and their uncorrelated Monte Carlo counterparts, respectively. The uncorrelated deltaH0 and deltaS0 values caused the retention-time range of the simulations' second dimension to expand substantially beyond that in the GC x GC. Other simulations were developed using a restricted range of uncorrelated deltaH0 and deltaS0 values to mimic more closely the retention-time range of the GC x GC's second dimension. The intervals between nearest neighbor retention-time coordinates were calculated in both the latter simulations and the GC x GC. The intervals were larger in the simulations than in the GC x GC because the former contained uncorrelated coordinates and the latter contained correlated ones, which clustered along or near the diagonal. The retention times in the first dimension of the GC x GC were Poisson distributed, as assessed by statistical-overlap theory. In contrast, the two-dimensional reduced retention-time coordinates in the GC x GC were not Poisson distributed, because retention times were correlated. However, the reduced retention-time coordinates in the simulations were Poisson distributed.

Journal Article↗

PubMed2006

Separation of triacylglycerols in a complex lipidic matrix by using comprehensive two-dimensional liquid chromatography coupled with atmospheric pressure chemical ionization mass spectrometric detection.

The present investigation describes the employment of a comprehensive 2-D HPLC system, based on the combination of a silver ion and an RP column, for the characterization of the triacylglycerol (TAG) fraction of a very complex lipidic sample: donkey milk fat. The TAGs were grouped on the resulting bidimensional contour plot according to their double bond numbers (aligned along vertical bands) and according to their partition numbers (aligned along horizontal bands). Peak assignment was supported by using atmospheric pressure chemical ionization mass spectrometric (APCI-MS) detection. The combination of the enhanced resolving power of comprehensive multidimensional LC, the formation of ordered 2-D patterns, and APCI-MS detection proved to be an effective tool for the characterization of the complex matrix, enabling the separation and identification of nearly 60 TAGs.

Animals↗

PubMed2006

Development of different comprehensive two dimensional systems for the separation of phenolic antioxidants.

Three different comprehensive 2-D HPLC systems for the separation of phenolic antioxidants have been developed on the basis of different selectivities of a PEG-silica column in the first dimension and a packed or monolithic C18 or a ZR-CARBON column, respectively, in the second dimension. Two-dimensional comprehensive liquid chromatography using a serially connected short PEG-silica column and a conventional C18-silica or a ZR-CARBON column in the second dimension was tested to improve the resolution of the earlier eluting compounds in the first dimension. Various types of interface were used to connect the columns in the first and in the second dimension: i) two injection sampling loops of 100 microL in conventional arrangement; ii) a 10-port 2-position valve equipped with two trapping X-Terra columns instead of loops; and iii) two analytical D2 columns in parallel. The mobile phase in the first dimension has a lower elution strength than in the second dimension, allowing band compression of the solutes transferred from the first to the second dimension. This effect was enhanced using trapping columns instead of sampling loops as the interface between the two dimensions, thus allowing a decrease in the time of analysis. These systems were used for the analysis of beer samples. The relative location of the components in the 2-D retention plane varied in relation to their chemical structure in each instrumental set-up and allowed positive peak identification.

Antioxidants↗

PubMed2001

A comprehensive analysis of loss of heterozygosity caused by hemizygous deletions in renal cell carcinoma using a subtraction library.

Several new loci were identified by a comprehensive analysis of loss of heterozygosity (LOH) using a subtraction library between matched normal and renal cell carcinoma (RCC) tissues. A total of 187 clones from the library, with a complexity of 1x10(4), were mapped, and 44 clusters of the mapped loci were subjected to LOH analysis using microsatellite markers. A total of 27 loci, which exhibited frequencies of LOH of at least 10% among 44 tumors, mostly clear-cell RCC, included several loci that were reported previously, such as, the von Hippel-Lindau gene, adenomatous polyposis coli, and interferon regulatory factor-1, as well as new loci, at 5q32-q34, 6q21-q22, 8p12, and others. These loci exhibited LOH among 11.8-93.8% of tumors, and most, if not all, were derived from the sites of hemizygous deletions. The minimum regions of LOH of chromosomes 5, 6, and 8 were 9.0, 10.3, and 0.775 Mb, respectively. The average distance between the cloned fragments on the chromosomes was 2.2 Mb in 187 clones, indicating that the minimum LOH size expected from this subtraction analysis was roughly 50 kb. Therefore, the strategy described here provides comprehensive analysis of LOH sites, which were mostly caused by hemizygous deletions.

Carcinoma, Renal Cell↗

PubMed1990

Comprehensive discharge planning for the elderly.

Discharge planning for the elderly can potentially reduce patient length of hospital stay, prevent rehospitalization, enhance patient outcomes and lessen the burden of care on the families. While increased numbers of elderly are being discharged earlier, there are few data on the process and effects of discharge planning protocols developed specifically for this population. The proposed study will attempt to answer the following questions regarding hospitalized elderly with selected DRG classifications: Are there significant differences between elderly patients who receive the hospital's general discharge planning procedure used for all categories of patients and elderly who receive the hospital's general discharge planning procedure plus a comprehensive discharge planning protocol specific to the elderly and implemented by a gerontological nurse specialist in: (1) Patient Outcomes (length of initial hospitalization; post-discharge morbidity; post-discharge health services; functional status; mental status; satisfaction with care; self-esteem; patient's perception of health status; and stress level); (2) Family Related Outcomes (primary care giver's functional status; mental status; care giving demands; stress level and family functioning); (3) Cost of Care Outcomes (charges for initial hospitalization, rehospitalizations, post-discharge health services; family related costs; and gerontological nurse specialist costs). The study design is a randomized clinical trial with a total of 280 elderly (2 groups of 140). The control group will receive routine discharge planning; the treatment group will receive routine discharge planning plus an elder-specific comprehensive discharge planning protocol. Data analysis will include frequency distributions and summary statistics. For each of the research questions, multivariate analysis of variance or chi-square statistics will be used.

Aged↗

PubMed2008

Impact of proximity to comprehensive sickle cell center on utilization of healthcare services among children with sickle cell disease.

BACKGROUND: The impact of comprehensive care on utilization of healthcare services by children with sickle cell disease (SCD) has not been fully evaluated. We compared the medical care utilization and mortality in children less than 20 years of age with SCD in four regions in the state of Tennessee with and without a comprehensive sickle cell center (CSCC). METHODS: Rates of hospitalizations, outpatient and emergency department (ED) visits, and deaths were measured in a cohort of children aged <20 years with SCD, enrolled in TennCare, from January 1995 to December 2002. TennCare data linked to Tennessee vital records were used to define the population and identify the outcomes. The patients were classified into one of four regions based on their residential address on the day of their hospitalization or outpatient visit. RESULTS: The cohort consisted of 1,214 children with 6,393 person-years of follow-up. Fifty-six percent of patients resided in the region with the CSCC. This region had the highest overall rates of hospitalization for all children (P < 0.001), while ED and outpatient visits were higher in other areas. The death rates ranged from 1.8 to 4.3 per 1,000 person-years in the four regions and did not represent statistically significant differences. CONCLUSION: No clear pattern of improved utilization of medical care services were identified in relation to proximity of residence to a CSCC. This cohort was not large enough to detect small differences in death rates. In addition, other outcomes that incorporate quality of life measures may be more sensitive to differences in medical care.

Adolescent↗

PubMed1994

Picture comprehension in probable Alzheimer's disease.

Patients with probable Alzheimer's disease (pAD) are frequently said to be compromised at a semantic level of picture comprehension. In order to test this hypothesis, pAD patients were asked to judge whether pictures are instances of a familiar superordinate category ("vegetable"). The targets (e.g., corn) varied in their representativeness, and the foils were either "coherent" items that were not target exemplars (e.g., apple, chair) or "anomalous" items displaying specific features that disqualified the stimuli as target exemplars (e.g., striped carrot). We also asked patients to judge a comparable set of words to determine whether difficulty appreciating pictures is material-specific. pAD patients were impaired at judging target pictures and a subset of picture foils, according to group-wide analyses, although they also encountered some difficulty judging the category membership of words. Individual patient analyses revealed that some patients were equally impaired at judging pictures and words. In particular, one subgroup experienced significant difficulty distinguishing coherent foils related to the target from true exemplars, and this occurred when the foils were presented as either pictures or words. An item-by-item analysis revealed highly concordant difficulty judging the same concepts expressed as either pictures or words in these patients. A material-specific deficit was evident in other pAD patients that resulted in selectively compromised picture judgments, including essentially all types of picture foils. We discuss these profiles of picture comprehension difficulty and conclude that deficits in understanding pictures in pAD may be due to semantic or perceptual types of impairment.

Aged↗

PubMed1994

Lack of error awareness in an aphasic patient with relatively preserved auditory comprehension.

The neuropsychological mechanisms underlying unawareness of speech/language deficits are unknown, but four possibilities have been suggested: impaired lexical-semantic representations associated with impaired speech comprehension, a failure of feedback, reduced attentional capacity, and psychological denial. We studied a patient who was unaware of his jargon aphasia despite only a mild auditory comprehension disturbance. Delaying auditory feedback altered his speech patterns. He recognized more of his errors in a recording of his voice than he did while speaking. He also recognized more errors in a recording of the examiner making errors than he did when listening to the recordings of his own speech. Based on these results, we suggest that none of the proposed mechanisms can exclusively account for this man's performance and that each may contribute to his failure to detect and correct errors in speech production.

Aged↗

PubMed1994

Semantic vs. syntactic subject: a comprehension test based on control constructions.

The test presented here is made of 32 + 32 complex sentences that are submitted with two different tasks: one to prove comprehension of the event denoted by their embedded clause and the other to prove the corret interpretation of this clause, whose null subject is syntactically controlled. The tasks have been administered to four stabilized aphasic patients of medium severity to see whether their comprehension could be considered asyntactic with respect to the specific Control module of Universal Grammar (Chomsky, 1981).

Adult↗

PubMed1995

Issues arising in contemporary studies of disorders of syntactic processing in sentence comprehension in agrammatic patients.

This paper reviews recent studies of sentence comprehension in agrammatic patients. The conclusion is reached that more detailed study of individual patients is necessary to support hypotheses that have been presented concerning the deficit in these patients and that the rationale for studying comprehension in this group of patients is not well developed. A set of suggested criteria is presented for patient analysis in this field.

Aphasia↗

PubMed1996

Verb comprehension deficits in probable Alzheimer's disease.

Studies of lexical comprehension in probable Alzheimer's disease (pAD) have focused almost exclusively on nouns. In the following preliminary study, we examined whether lexical comprehension for verbs is also impaired in 25 pAD patients. The semantic meaning of motion verbs, cognition verbs, and perception verbs was assessed with a triadic comparison task. Structural meaning associated with these verbs was evaluated by asking the patients to judge the coherence of sentence frames that accept these verbs naturally or awkwardly. We found that pAD patients are significantly impaired at identifying semantic relations among verbs. pAD patients also encountered significantly more difficulty judging the coherence of sentences than control subjects. Correlation and regression analyses demonstrated that semantic characteristics of verbs are projected from the verb's sentence frames in control subjects, but there was minimal evidence for such a structural-semantic relationship in pAD. We consider several possible explanations for our preliminary observations of an impairment that has consequences for processing both semantic and structural aspects of verb meaning.

Aged↗

PubMed1996

The time-course of metaphor comprehension: an event-related potential study.

ERPs were recorded while subjects were reading short familiar metaphors (e.g., Those fighters are lions), unfamiliar metaphors (Those apprentices are lions), or literal control sentences (Those animals are lions) presented in isolation or preceded by either an irrelevant or relevant context (e.g., They are not idiotic: ...." vs. "They are not cowardly: Those fighters are lions"). The terminal word of metaphors elicited larger N400 components than did the terminal word of literal sentences (Experiment 1) suggesting that the (incongruous) literal meaning of metaphors was indeed accessed at some point during comprehension. The analysis of the 600-1000 and 1000-1400 latency bands (Late Positive Components) revealed no significant difference between metaphors and literal sentences. The manipulation of metaphor difficulty (Experiments 2 and 3) also failed to reveal any late effect specifically linked to metaphorical processing. Finally, an effect of the preceding sentence context was found in Experiments 3 and 4, as early as 300 ms following the terminal word onset. Overall, these results support a context-dependent account of metaphor comprehension stating that when contextually relevant, the metaphorical meaning is the only one accessed.

Adolescent↗

PubMed1997

Patterns of sentence comprehension in aphasia: a consideration of three hypotheses.

Three hypotheses concerning the functional source of aphasic patients' difficulty comprehending semantically reversible sentences were tested using declarative sentences in active and passive voice and sentences with center-embedded relative clauses. Each of the three hypotheses is predicated on relative patterns of impairment and sparing of patient performance on these (and other) sentence types, yet the three hypotheses make somewhat different predictions about performance patterns across these types. Results from 5 Broca's aphasic patients were not consistent with the predictions of the linguistically motivated Trace Deletion Hypothesis or of a hypothesis based on an impairment involving grammatical morphemes. The hypothesis that aphasic comprehension impairments reflect a general limitation of working memory capacity was given partial support by the ordinal pattern of difficulty for a mixed group of 10 patients, but failed to account for patterns obtained from individual patients. Results are interpreted as having relevance for methodological as well as theoretical aspects of research on aphasic sentence comprehension.

Adult↗

PubMed1998

Sentence comprehension in Alzheimer's disease.

We asked 22 patients with Alzheimer's disease (AD) to respond to simple probes of sentences where we manipulated grammatical factors, semantic factors, and cognitive resource demands associated with a sentence. The results demonstrated limitations in the cognitive resources needed to appreciate atypical syntactic-thematic mapping relations and difficulty processing selection restrictions associated with a verb. By comparison, comprehension in AD was not influenced by the active or passive voice of a sentence. These findings are consistent with the hypothesis that impaired sentence comprehension in AD is multifactorial in nature, including difficulty processing cognitive resource and semantic aspects of sentences.

Aged↗

PubMed1998

Gap-filling and end-of-sentence effects in real-time language processing: implications for modeling sentence comprehension in aphasia.

We present an on-line study showing different sources of lexical activation during sentence comprehension, distinguishing in this respect between reflexive syntactic and less temporarily constrained nonsyntactic sources. Specifically, we show that both the syntactic process of gap filling and a nonsyntactic end-of-sentence effect can be measurable in real time and can be temporally separated. The distinction between activation sources provides a new perspective on real-time sentence comprehension in aphasia and accounts for the disparate results reported in the literature.

Aged↗