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Biomedical subjects

A Mathews

Publications and source records attributed to A Mathews.

At least 37 records · Page 2Linked to original sources
PubMed1998

Identification of a nickel(II) binding site on hemoglobin which confers susceptibility to oxidative deamination and intramolecular cross-linking.

Complexation of Ni(II) with native state recombinant hemoglobin is shown to produce NH2-terminal deamination and globin cross-linking in the presence of the oxidant potassium peroxymonosulfate (OxoneTM). Both the oxidative deamination and cross-linking are exclusive to the beta chains. Recombinant hemoglobin mutants have been created to identify protein sequence requirements for these reactions. It was found that His-2 of the beta globin is required for redox active Ni(II) complexation, oxidative deamination, and cross-linking. The oxidative deamination results in the formation of a free carbonyl in place of the NH2-terminal amine of the beta chain. Most cross-linking of the beta globin occurs intramolecularly, forming beta globin dimers. Structural characterization of the beta globin dimers indicates the presence of heterogeneous cross-links within the central hemoglobin cavity between the NH2 terminus of one beta chain and the COOH-terminal region of the other.

Amino Acid Sequence↗
PubMed1997

Utilization and cost of serologic tests for Lyme disease in Maryland.

To ascertain use of serologic tests for Lyme disease (LD) in Maryland, all laboratories registered with the State Health Department were surveyed. Results show that from 1992 to 1995, 17 laboratories performed 100,000 serologic tests costing $7.1 million on Maryland residents; 90% of these tests were EIAs. The proportion of positive EIAs increased from 3.4% in 1992 to approximately 7.0% in 1994 and 1995, and the percentage of positive second tests (Western blot, WB) fell from 7.9% to 5.0%-5.5%. The large number of EIAs performed in comparison with the low incidence of LD in the state results in a low predictive value of a positive EIA test. Therefore, the WB is indicated to confirm equivocal and positive EIA tests when characteristic clinical findings of LD are not present. The 30,000 tests for LD performed annually on Maryland residents at a cost of over $2 million in direct medical costs must be added to the public health burden of LD in this state.

Blotting, Western↗
PubMed1997

Selective processing of concern-related information in depression.

OBJECTIVES: The major question examined in this paper is whether selective attentional and interpretative processing of emotional information occurs in depression, and if so, whether it depends on a close match between the material used and current concerns. DESIGN: Twenty-four depressed patients and the same number of matched controls were tested using two selective processing tasks (described below), and their performance related to self-reported sociotropic and autonomy-related concerns. METHODS: Colour-naming interference and interpretation of ambiguous situations were assessed using material judged relevant to each of the Sociotropy-autonomy Scales. RESULTS: Depression was associated with a general interference effect for all negative concern words, and more negative interpretations of ambiguous situations, while controls showed a converse bias in favour of all positive interpretations. There was no convincing evidence that this negative processing bias was proportional to the match between material and self-reported sociotropic or autonomous concerns. CONCLUSIONS: Depressed patients showed evidence of cognitive biases favouring all negative self-related information, on both attentional and interpretative tasks. We suggest that such effects in depression may occur only under conditions allowing the elaborative processing of negative material related to oneself.

Adjustment Disorders↗
PubMed1997

Interpretative inferences when reading about emotional events.

In three experiments we investigated the extent to which individuals with high or low levels of anxiety about interviews made emotionally-congruent interpretative inferences while reading descriptions of a relevant ambiguously-threatening event (being interviewed for a job). Evidence was found to support the hypothesis that groups varying in self-reported concern about the described event differed in the interpretations that they made while reading. Taken together, the results of the three experiments are consistent with the conclusion that non-anxious individuals infer positive outcomes to an ambiguous event, while highly anxious individuals do not. We suggest that these results have implications for cognitive processes that could maintain anxiety in real life.

Affect↗
PubMed1996

Isolation and characterization of full-length cDNA clones of the giant taro (Alocasia macrorrhiza) trypsin/chymotrypsin inhibitor.

A full-length cDNA encoding the 206 amino acid open reading frame of a trypsin/chymotrypsin inhibitor abundant in the corms of giant taro (Alocasia macrorrhiza) was isolated. An internal fragment was cloned using degenerate primers corresponding to a region of the mature protein sequence and the 'rapid amplification of cDNA ends' (RACE) method used to generate a composite cDNA sequence. The length of the cDNA was close to the predicted size of the corresponding transcript deduced from northern blot analysis of corm mRNA. The inhibitor was expressed strongly in the mature corm, at low levels in leaf blades and petioles but not in roots. Southern blot analysis of the giant taro DNA indicated that this inhibitor is encoded by a small multigene family and this was further supported by the isolation of two different sequence classes from corm cDNA using primers to the ends of the composite sequence.

Amino Acid Sequence↗
PubMed1996

Evidence for attention to threatening stimuli in depression.

A modified version of the attentional deployment task developed by MacLeod, Mathews and Tata (1986) [Journal of Abnormal Psychology, 95, 15-20] was used to examine two issues: first, whether there was any evidence of attentional bias in depressed subjects, rather than in anxious subjects alone; and second, whether attentional effects would occur in the location of stimuli that could not be identified. Subjects were presented with pairs of words, one above the other, and the extent to which attention favored threatening rather than neutral words was assessed from the latency to detect a dot in the same location of one them. These detection latencies showed that depressed, but not anxious subjects, were selectively attentive to socially threatening words. There was also evidence for attentional effects in the anxious subjects favoring physically threatening words. Furthermore, panic disorder patients were preferentially attentive to the location of physically-threatening stimuli that could not be accurately identified. Overall, the results provide further evidence that emotionally disturbed subjects tend to orient attention towards personally-relevant emotional stimuli. However, the previous hypothesis that this attentional bias occurs only in anxiety, and not in depression, was not supported.

Adult↗
PubMed1996

Unconscious mood-congruent memory bias in depression.

The purpose of this study was to investigate an unconscious or implicit mood-congruent memory (MCM) bias in clinical depression. Many studies have shown an explicit memory bias, but no study has yet found an implicit MCM bias in clinical depression. The authors compared depressed and control group participants on a conceptually driven implicit memory test. After studying words of positive, neutral, and negative affective valences, participants produced free associations to various cues. Implicit memory or priming was demonstrated by the production of more studied than unstudied words to the association cues. Depressed participants showed more priming of negative words, whereas controls showed more priming of positive words, thus supporting the MCM pattern. Also, no implicit memory deficit was found in depressed participants. These findings are discussed in the context of several prominent theories of cognition and depression.

Adolescent↗
PubMed1996

The emotional Stroop task and psychopathology.

Attentional bias is a central feature of many cognitive theories of psychopathology. One of the most frequent methods of investigating such bias has been an emotional analog of the Stroop task. In this task, participants name the colors in which words are printed, and the words vary in their relevance to each theme of psychopathology. The authors review research showing that patients are often slower to name the color of a word associated with concerns relevant to their clinical condition. They address the causes and mechanisms underlying the phenomenon, focusing on J.D. Cohen, K. Dunbar, and J.L. McClelland's (1990) parallel distributed processing model.

Anxiety Disorders↗
PubMed1996

Maternal mortality in Malaysia 1991-1992: the paradox of increased rates.

"This paper aims to show that the establishment of a better data collection and reporting system in Malaysia since 1991 has led to an apparent increase in the maternal mortality ratio.... Because of improved surveillance, the maternal mortality ratio may continue to appear to rise for a few years but should decline after that reflecting the improvement in the health status and service delivery in Malaysia."

Asia↗
PubMed1995

Nucleotide and deduced amino acid sequence of the 3' end of the BYMV-MI genome.

We have cloned and sequenced cDNA transcribed from the 3' 1,239 nucleotides of the genomic RNA of a Western Australian isolate (MI) of bean yellow mosaic potyvirus (BYMV). This sequence contains 246 nucleotides of the NIb (replicase) gene and 819 nucleotides representing the entire coding region of the viral coat protein gene, followed by a 3' non-coding region of 174 nucleotides. The coding region of the coat protein gene is identical in length (273 amino acids) to that already reported for other isolates of this virus. The sequence identities obtained for BYMV-MI and published sequences of BYMV isolates range between 85% and 92% for the coding region of the coat protein and 90% to 98% for the 3' non-coding region. Likewise, the region of the NIb gene sequenced shows 99% and 97% sequence identity in the deduced amino acid and the nucleotide sequences, respectively.

Amino Acid Sequence↗
PubMed1995

Memory for actual and imagined events in OC checkers.

Information-processing theorists have suggested that obsessive-compulsive (OC) checking may be a function of either (1) an impaired memory of emotional events, (2) an attenuated ability to distinguish between real and imagined events or (3) a dissatisfaction with one's recall without actual memory impairment. These hypotheses were tested by having OC and control Ss engage in real and imagined actions. Some of the actions were designed to produce anxiety in the OC Ss while other events were designed to be emotionally neutral. No differences in reality-monitoring ability were found between OC and control Ss. Contrary to our prediction, OC Ss recall of their last actual behavior was superior to controls, but only for those actions that elicited anxiety. OC Ss, but not controls, reported that they desired higher levels of memory vividness than they were able to produce. The potential mechanism whereby dissatisfaction with memory vividness could contribute to repetitive checking is discussed.

Adult↗
PubMed1995

Effect of psychological treatment on cognitive bias in generalized anxiety disorder.

Measures of attention and implicit memory for threatening words were obtained from anxious patients before and after psychological treatment, and compared with data from non-anxious control Ss collected over the same period. Findings confirmed the expectation that the presence of threatening distractors would be associated with greater interference with the performance of anxious patients than with that of controls, in both color-naming and attentional search tasks, but failed to confirm the previous finding of related differences in priming on a word completion task. Treatment significantly reduced selective interference effects in anxious patients, and abolished evidence of differences between the treated patients and controls. It is suggested that cognitive bias effects in anxiety may either depend on state factors alone, or may represent a more enduring individual difference that becomes apparent only when vulnerable individuals are primed by mood state or stressful events.

Adult↗
PubMed1995

Effect of extracellular calcium on survival of human proximal tubular cells exposed to hypoxia.

Removal of extracellular calcium has been demonstrated to improve membrane integrity of rodent myocytes, astrocytes, and renal tubular cells injured by hypoxia. In this study, the effect of extracellular calcium on long-term survival of cultured human proximal tubular epithelial cells (PTEC) subjected to hypoxia was evaluated. In addition, the effect of extracellular calcium on release of arachidonic acid metabolites (AAM) was assessed during and after hypoxia. To induce hypoxic injury, PTEC were incubated in an anaerobic chamber in glucose-free buffer (combined oxygen/glucose deprivation, COGD). Long-term survival was assessed by measuring lactate dehydrogenase (LDH) efflux during COGD and after an additional 24-h "recovery" period (in routine culture medium in 95% air/5% CO2). To determine if extracellular calcium influenced AAM release from membrane phospholipids, cells were preincubated with [3H]arachidonic acid and the release of AAM was measured during COGD and recovery. With this model system, PTEC exhibited minimal LDH efflux during < or = 12 h COGD, but LDH efflux increased to 73.9 +/- 4.7% by 24 h COGD. With 12-18 h of COGD, the extent of LDH efflux was greater during recovery than during COGD, indicating that, for human PTEC, the extent of membrane damage does not become fully evident by LDH efflux for hours after hypoxia. PTEC exposed to 24 h of COGD in the absence of extracellular calcium exhibited strikingly less LDH efflux during COGD than cells incubated in the presence of extracellular calcium, suggesting that extracellular calcium contributes to membrane damage during COGD. However, upon reexposure of PTEC to extracellular calcium, LDH efflux rapidly increased to control levels. Furthermore, despite allowing cells to recover in oxygen or oxygen and glucose before exposure to calcium-containing medium, a rapid increase in LDH efflux could not be avoided. These results suggest that COGD induces an irreversible injury that ultimately leads to loss of membrane integrity whether or not extracellular calcium is present; however, extracellular calcium accelerates the loss of membrane integrity caused by hypoxia. Extracellular calcium did not alter AAM release, indicating that the effect of extracellular calcium on membrane damage (as indicated by LDH efflux) was not mediated by an increased activity of phospholipases (such as phospholipase A2) that are involved in the release of AAM.

Arachidonic Acid↗
PubMed1994

The differential pattern of memory deficit in normal aging and dementias of different etiology.

The study explored encoding, storage, and retrieval components of memory functioning in four groups of subjects: (1) normal elderly; (2) elderly subjects in the early prestages of DAT; (3) elderly subjects with a more advanced DAT; (4) younger subjects in the early prestages of AIDS dementia. Each group consisted of 26 subjects, who were administered the Rey Auditory-Verbal Learning Test. The results suggest impaired encoding and retrieval in the DAT groups. The AIDS group demonstrated deficient storage and retrieval. Their pattern of memory deficits was similar to that seen in normal aging. The results speak in favor of the hypothesis of subcortical nature of neurological changes in normal aging.

AIDS Dementia Complex↗
PubMed1994

Effects of priming and suppression of worry.

High and low worriers were primed by a short period of worry, suppression of worry, or the same period of non-worrying thought. Analysis of thoughts during the period following showed that worriers had more than twice as many unpleasant thoughts as did controls, across all prior conditions. Priming condition had little effect on this difference, although worry suppression was associated with a slight increase in the frequency of neutral or pleasant thoughts in high worriers, and a slight decrease in controls. These results are taken as evidence against the hypothesis that suppression of upsetting thoughts increases their intrusive quality, and thereby contributes to anxiety disorders.

Adult↗