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Biomedical subjects

A L Powell

Publications and source records attributed to A L Powell.

At least 19 recordsLinked to original sources
PubMed2000

Transgenic expression of pear PGIP in tomato limits fungal colonization.

Transgenic tomato plants expressing the pear fruit polygalacturonase inhibitor protein (pPGIP) were used to demonstrate that this inhibitor of fungal pathogen endopolygalacturonases (endo-PGs) influences disease development. Transgenic expression of pPGIP resulted in abundant accumulation of the heterologous protein in all tissues and did not alter the expression of an endogenous tomato fruit PGIP (tPGIP). The pPGIP protein was detected, as expected, in the cell wall protein fraction in all transgenic tissues. Despite differential glycosylation in vegetative and fruit tissues, the expressed pPGIP was active in both tissues as an inhibitor of endo-PGs from Botrytis cinerea. The growth of B. cinerea on ripe tomato fruit expressing pPGIP was reduced, and tissue breakdown was diminished by as much as 15%, compared with nontransgenic fruit In transgenic leaves, the expression of pPGIP reduced lesions of macerated tissue approximately 25%, a reduction of symptoms of fungal growth similar to that observed with a B. cinerea strain in which a single endo-PG gene, Bcpg1, had been deleted (A. ten Have, W. Mulder, J. Visser, and J. A. L. van Kan, Mol. Plant-Microbe Interact. 11:1009-1016, 1998). Heterologous expression of pPGIP has demonstrated that PGIP inhibition of fungal PGs slows the expansion of disease lesions and the associated tissue maceration.

Base Sequence↗
PubMed1999

An expansin gene expressed in ripening strawberry fruit.

Tissue softening accompanies the ripening of many fruit and initiates the processes of irreversible deterioration. Expansins are plant cell wall proteins proposed to disrupt hydrogen bonds within the cell wall polymer matrix. Expression of specific expansin genes has been observed in tomato (Lycopersicon esculentum) meristems, expanding tissues, and ripening fruit. It has been proposed that a tomato ripening-regulated expansin might contribute to cell wall polymer disassembly and fruit softening by increasing the accessibility of specific cell wall polymers to hydrolase action. To assess whether ripening-regulated expansins are present in all ripening fruit, we examined expansin gene expression in strawberry (Fragaria x ananassa Duch.). Strawberry differs significantly from tomato in that the fruit is derived from receptacle rather than ovary tissue and strawberry is non-climacteric. A full-length cDNA encoding a ripening-regulated expansin, FaExp2, was isolated from strawberry fruit. The deduced amino acid sequence of FaExp2 is most closely related to an expansin expressed in early tomato development and to expansins expressed in apricot fruit rather than the previously identified tomato ripening-regulated expansin, LeExp1. Nearly all previously identified ripening-regulated genes in strawberry are negatively regulated by auxin. Surprisingly, FaExp2 expression was largely unaffected by auxin. Overall, our results suggest that expansins are a common component of ripening and that non-climacteric signals other than auxin may coordinate the onset of ripening in strawberry.

Amino Acid Sequence↗
PubMed1997

Attention deficit hyperactivity disorder associated with orbitofrontal epilepsy in a father and a son.

The authors report on a father and son with frontal lobe epilepsy and symptoms of attention deficit hyperactivity disorder (ADHD). Attention deficit hyperactivity is a syndrome defined by criteria that include inattention, impulsive behavior, impaired concentration and motor restlessness. It does not require medical or neurobehavioral evaluation to determine an underlying etiology. The father is a 45-year-old man evaluated for possible ADHD. His referral came after the diagnosis of ADHD in his 6-year-old son who responded well to treatment with methylphenidate HCL. Neurobehavioral evaluation of the father suggested frontal lobe dysfunction. Magnetic resonance imaging and electroencephalography (EEG) were normal. Brain 99mTc HMPAO single-photon emission computed tomography (SPECT) revealed left orbitofrontal hypoperfusion. Additional history from his wife revealed episodic symptoms suggestive of nonconvulsive epilepsy that included nonresponsive staring, complex automatic behavior, and amnesic lacunas. Treatment of the father with carbmazepine produced dramatic improvement. Subsequent evaluation of his son, currently on maintenance treatment with methylphenidate HCL for ADHD, elicited a history consistent with atonic and simple motor partial epilepsy. The son's brain SPECT revealed bilateral orbitofrontal hypoperfusion defects. Attention deficit hyperactivity disorder is a syndrome that may be caused by frontal lobe lesions or epilepsy. In the setting of possible ADHD, neurological evaluation is warranted. Although overreliance on structural imaging or EEG in such an evaluation must be discouraged, brain SPECT may be useful to evaluate patients with symptoms of attention disorders for frontal epilepsy.

Attention Deficit Disorder with Hyperactivity↗
PubMed1996

Emotions and cognitions associated with bingeing and weight control behavior in bulimia.

The examination of cognitions and emotions during the bulimic cycle is critical in understanding possible maintenance factors involved in bulimia. In this study, 22 bulimics and 22 nonbulimics recorded their thoughts and feelings every 2 waking hours over a 6-day period. Bulimics additionally recorded their moods and thoughts during their binges and compensatory behaviors (e.g., purging, exercise). Higher levels of negative affect were reported at all stages of the cycle compared to baseline, although negative affect decreased after the compensatory behavior stage. Subjects also reported stronger distorted cognitions before and after the binge compared to baseline. One of the distorted cognitions (feeling fat) decreased in strength after subjects engaged in compensatory behavior. Additional analyses revealed that most levels of negative affect and distorted cognitions were elevated prior to binges as compared to meals. Finally, negative affect and distorted cognitions were stronger after binges than after meals.

Adult↗
PubMed1995

The protective effects of education on simulated brain injury.

Disturbed intellectual function is an important determinant of long-term recovery after head injury. Residual behavioral disability depends largely upon which hemisphere is damaged and the site of injury within the hemisphere. Resulting neurobehavioral syndromes vary with the pattern of brain insult. While this correlation is important, it is still not well understood how damage to single neurons translates into abnormal behavior. In addition, no currently available technology permits in vivo evaluation of such cells in normal or injured states. While research into brain trauma traditionally emphasize single cell pathology, this level of study is insufficient to clarify how individual cell activity contributes to higher cognition. In contrast, neural network simulations may partially fill this void by predicting biological function. Here, we present data generated by a three-layer neural network that employs the ALOPEX algorithm, capable of learning 10 words. The addition of Gaussian distributed noise into connection weights strengths damaged the network's function; interestingly, the rate and extent of network impairment depended upon the level of learning that occurred during the training period, in agreement with human studies that demonstrate a protective effect of education on subsequent brain injury. Damage to input signals resulted in similar effects on network function. Accordingly, such simulations offer powerful evidence that human behavior may be considered in terms of neuronal cell populations and efforts to preserve brain function at the time of injury should emphasize maintaining neural connections.

Algorithms↗
PubMed1994

Structure and expression of an inhibitor of fungal polygalacturonases from tomato.

A polygalacturonase inhibitor protein (PGIP) was characterized from tomato fruit. Differential glycosylation of a single polypeptide accounted for heterogeneity in concanavalin A binding and in molecular mass. Tomato PGIP had a native molecular mass of 35 to 41 kDa, a native isoelectric point of 9.0, and a chemically deglycosylated molecular mass of 34 kDa, suggesting shared structural similarities with pear fruit PGIP. When purified PGIPs from pear and tomato were compared, tomato PGIP was approximately twenty-fold less effective an inhibitor of polygalacturonase activity isolated from cultures of Botrytis cinerea. Based on partial amino acid sequence, polymerase chain reaction products and genomic clones were isolated and used to demonstrate the presence of PGIP mRNA in both immature and ripening fruit as well as cell suspension cultures. Nucleotide sequence analysis indicates that the gene, uninterrupted by introns, encodes a predicted 36.5 kDa polypeptide containing amino acid sequences determined from the purified protein and sharing 68% and 50% amino acid sequence identity with pear and bean PGIPs, respectively. Analysis of the PGIP sequences also revealed that they belong to a class of proteins which contain leucine-rich tandem repeats. Because these sequence domains have been associated with protein-protein interactions, it is possible that they contribute to the interaction between PGIP and fungal polygalacturonases.

Amino Acid Sequence↗
PubMed1993

A retrospective study of syphilis seropositivity in a cohort of demented patients.

A retrospective study of 376 patients with dementia was performed to determine the rate of syphilis seropositivity. Subjects were seen over a 2.5-year period and received medical, social, psychiatric, neurological, and laboratory evaluations. Mean age was 74 years and 73% were women. Diagnoses included Alzheimer's disease (AD; 29.8%), vascular dementia (VascD; 24.7%), combined AD/VascD (14.3%), and other diagnoses (31.2%). Dementia was moderately advanced with a mean Folstein Mini-Mental State Score of 16. Fluorescent treponemal antibody absorption tests (FA) were performed on 338 of the patients with 10.9% being reactive. Two of nine subjects with reactive FA's had reactive rapid plasma reagin tests.

Adult↗
PubMed1993

Molecular characterization of a polygalacturonase inhibitor from Pyrus communis L. cv Bartlett.

A polygalacturonase inhibitor glycoprotein with an apparent molecular mass of 43 kD was purified from pear (Pyrus communis L. cv Bartlett) fruit. Chemical deglycosylation of this protein decreased the molecular mass to 34 kD. Gas chromatographic analysis suggests that N-linked glycosylation accounts for the majority of sugar moieties. Partial amino acid sequence analysis of the purified polygalacturonase inhibitor protein provided information used to amplify a corresponding cDNA by polymerase chain reactions. Multiple cloned products of these reactions were sequenced and the same open reading frame was identified in all of the products. It encodes a 36.5-kD polypeptide containing the amino acid sequences determined by protein sequencing and predicts a putative signal sequence of 24 amino acids and seven potential N-glycosylation sites. The expression of polygalacturonase inhibitor is regulated in a tissue-specific manner. Activity and mRNA level were much higher in fruit than in flowers or leaves.

Amino Acid Sequence↗
PubMed1990

Brain imaging techniques in the diagnosis of dementia.

Various recently developed brain imaging techniques used to assist in the diagnosis of dementia are reviewed. The methods reviewed are x-ray computed tomography scan imaging, magnetic resonance imaging, positron emission tomography, and the older techniques of pneumoencephalography and radioisotope cisternography. It was concluded that while these techniques often offer excellent diagnostic information, none of them provides a definitive characteristic image for Alzheimer's disease.

Aged↗
PubMed1988

Five studies testing two new egoistic alternatives to the empathy-altruism hypothesis.

The empathy-altruism hypothesis claims that prosocial motivation associated with feeling empathy for a person in need is directed toward the ultimate goal of benefiting that person, not toward some subtle form of self-benefit. We explored two new egoistic alternatives to this hypothesis. The empathy-specific reward hypothesis proposes that the prosocial motivation associated with empathy is directed toward the goal of obtaining social or self-rewards (i.e., praise, honor, and pride). The empathy-specific punishment hypothesis proposes that this motivation is directed toward the goal of avoiding social or self-punishments (i.e., censure, guilt, and shame). Study 1 provided an initial test of the empathy-specific reward hypothesis. Studies 2 through 4 used three procedures to test the empathy-specific punishment hypothesis. In Study 5, a Stroop procedure was used to assess the role of reward-relevant, punishment-relevant, and victim-relevant cognitions in mediating the empathy-helping relationship. Results of these five studies did not support either the empathy-specific reward or the empathy-specific punishment hypothesis. Instead, results of each supported the empathy-altruism hypothesis. Evidence that empathic emotion evokes altruistic motivation continues to mount.

Adult↗
PubMed1988

Speech and language alterations in multi-infarct dementia.

Speech and language functions were assessed in 18 patients with multi-infarct dementia (MID) and 14 with dementia of the Alzheimer type (DAT). The age range and dementia severity of the two groups were comparable. We used a speech and language battery assessing 37 elements of verbal output to characterize alterations in the patients. MID patients had more abnormalities of motor aspects of speech, whereas DAT patients had empty speech, more marked anomia, and relative sparing of motor speech functions. The results demonstrate that speech and language differ in MID and DAT. In addition, MID patients exhibited common clinical features despite the heterogeneity of the syndrome.

Aged↗
PubMed1986

Lithium interaction with sulindac and naproxen.

The interaction of lithium with sulindac and naproxen was studied in six sulindac-treated and seven naproxen-treated patients admitted to a geropsychiatry ward. Patients under a steady state lithium level received lithium for 3 days, then lithium + sulindac (300 mg/day) or naproxen (750 mg/day) for 6 days, and then lithium alone for 5 days. Sulindac failed to affect serum lithium levels and lithium clearance. The results with naproxen showed marked interindividual variations ranging from no increase to a 41.9% increase in serum lithium levels within 5 days. There was a corresponding decrease in lithium clearance in naproxen-treated patients. Patients undergoing lithium therapy might need a reduction of their lithium dosage following naproxen administration. More frequent serum lithium level determinations are required following initiation of naproxen therapy until the magnitude of the lithium-naproxen drug interaction can be adequately assessed in a given individual.

Aged↗
PubMed1986

Failure of sulindac to increase serum lithium levels.

The interaction of sulindac with lithium was investigated in four patients who were admitted to a geropsychiatry ward and required lithium therapy. Sulindac 300 mg/day failed to affect lithium serum level and renal lithium clearance in these patients. Sulindac seems safer in patients receiving lithium than drugs like indomethacin, which can substantially increase serum lithium levels.

Bipolar Disorder↗
PubMed1984

Changes in T-DNA methylation and expression are associated with phenotypic variation and plant regeneration in a crown gall tumor line.

Phenotypic variation of an octopine-type crown gall tumor line resulting from changes in the pattern of T-DNA methylation and expression is described. Variants that grow as unorganized callus always express T-DNA transcripts 1 and 2. In shoot-forming variants (teratomas) only T-DNA transcript 4 is expressed. This line also regenerates normal-appearing, rooted plants in which all T-DNA expression is suppressed. Tissues from these plants require phytohormones for growth in vitro. These plants are self-fertile and transmit T-DNA through meiosis, and T-DNA suppression is maintained in the next generation. After treatment of regenerated plant tissue with 5-azacytidine, an inhibitor of DNA methylation, T-DNA transcription and phytohormone-independent tumorous growth resume. The T-DNA of cell lines in which T-DNA is not expressed is highly methylated, whereas the level of T-DNA methylation is reduced in 5-azacytidine treated cells that resume T-DNA expression and phytohormone-independent growth. The correlation between the degree of T-DNA methylation and the level of T-DNA expression indicates that hypermethylation is responsible for the suppression of T-DNA transcription.

Azacitidine↗
PubMed1979

Epstein-Barr virus-specific RNA. III. Mapping of DNA encoding viral RNA in restringent infection.

Namalwa and Raji cells, originally obtained from a Burkitt tumor biopsy, grow as continuous cell lines in vitro and contain the Epstein-Barr virus (EBV)-related nuclear antigen EBNA (B. M. Reedman and G. Klein, Int. J. Cancer 11:499-520, 1973) and RNA homologous to at least 17 and 30% of the EBV genome, respectively (S. D. Hayward and E. Kieff, J. Virol. 18:518-525, 1976; T. Orellana and E. Kieff, J. Virol. 22:321-330, 1977). The polyribosomal and polyadenylated [poly(A)+] RNA fractions of Namalwa and Raji cells are enriched for a class of viral RNA homologous to 5 to 7% of EBV DNA (Hayward and Kieff, J. Virol. 18:518-525, 1976; Orellana and Kieff, J. Virol. 22:321-330, 1977). The objective of the experiments described in this communication was to determine the location within the map of the EBV genome (D. Given and E. Kieff, J. Virol. 28:524-542, 1978) of the DNA which encodes the viral RNA in the poly(A)+ and non-polyadenylated [poly(A)-] RNA fractions of Namalwa cells. Hybridization of labeled DNA homologous to Namalwa poly(A)+ or poly(A)- RNA to blots containing EcoRI, Hsu I, or Hsu I/EcoRI double-cut fragments of EBV (B95-8) or (W91) DNA indicated that these RNAs are encoded by DNA contained primarily in the Hsu I A/EcoRI A and Hsu I B/EcoRI A fragments and, to a lesser extent, in other fragments of the EBV genome. Hybridizations of Namalwa poly(A)+ and poly(A)- RNA in solution to denatured labeled EcoRI A or B fragments, Hsu I A, B, or D fragments, and Hsu I A/EcoRI A or Bam I S fragments and of Raji polyribosomal poly(A)+ RNA to the EcoRI A fragment indicated that (i) Namalwa poly(A)+ RNA is encoded primarily by 6 x 10(5) daltons of a 2 x 10(6)-dalton segment of DNA, Bam I S, which is tandemly reiterated, approximately 10 times, in the Hsu I A/EcoRI A fragment and is encoded to a lesser extent by DNA in the Hsu I B, EcoRI B, and Hsu I D fragments. Raji polyribosomal poly(A)+ RNA is encoded by a similar fraction of the EcoRI A fragment as that which encodes Namalwa poly(A)+ RNA. (ii) The fraction of the Bam I S fragment homologous to Namalwa poly(A)- RNA is similar to the fraction homologous to Namalwa poly(A)+ RNA. However, Namalwa poly(A)- RNA is homologous to a larger fraction of the DNA in the Hsu I B, Hsu I D, and EcoRI B fragments.

Cell Line↗
PubMed1979

Immunopathological changes in cadmium-treated rats.

Rats treated with cadmium developed an interstitial pneumonitis with intraalveolar hemorrhage. In the spleen there was marked germinal center formation containing reactive B-cells. Lesions of the kidneys resembled those found in cadmium poisoning in man, primarily a proliferative glomerulonephritis.

Animals↗