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M Anderson

Publications and source records attributed to M Anderson.

At least 91 records · Page 5Linked to original sources
PubMed2001

Identification of G protein-coupled, inward rectifier potassium channel gene products from the rat anterior pituitary gland.

Dopamine (DA) is a physiological regulator of PRL secretion, exerting tonic inhibitory control. DA activates an inward rectifier K(+) (IRK) channel in rat lactotropes, causing membrane hyperpolarization and inhibition of Ca(2+)-dependent action potentials. Both the activation of this effector K(+) channel and the inhibition of PRL release are mediated by D(2)-type receptor activation and pertussis toxin- sensitive G proteins. To study the molecular basis of this physiologically relevant channel, a homology-based PCR approach was employed to identify members of the IRK channel family expressed in the anterior pituitary gland. Nondegenerate primers corresponding to regions specific for IRK channels known to be G protein activated (GIRKs; gene subfamily Kir 3.0) were synthesized and used in the PCR with reverse transcribed female rat anterior pituitary messenger RNA as the template. PCR products of predicted sizes for Kir 3.1, 3.2, and 3.4 were consistently observed by ethidium bromide staining after 16 amplification cycles. The identities of the products were confirmed by subcloning and sequencing. Expression of each of these gene products in anterior pituitary was confirmed by Northern blot analysis. Functional analysis of the GIRK proteins was performed in the heterologous expression system, Xenopus laevis oocytes. Macroscopic K(+) currents were examined in oocytes injected with different combinations of Kir 3.0 complementary RNA (cRNA) and G protein subunit (beta(1)gamma(2)) cRNA. The current-voltage relationships demonstrated strong inward rectification for each individual and pairwise combination of GIRK channel subunits. Oocytes coinjected with any pair of GIRK subunit cRNA exhibited significantly larger inward K(+) currents than oocytes injected with only one GIRK channel subtype. Ligand-dependent activation of only one of the GIRK combinations (GIRK1 and GIRK4) was observed when channel subunits were coexpressed with the D(2) receptor in Xenopus oocytes. Dose-response data fit to a Michaelis-Menten equation gave an apparent K(d) similar to that for DA binding in anterior pituitary tissue. GIRK1 and GIRK4 proteins were coimmunoprecipitated from anterior pituitary lysates, confirming the presence of native GIRK1/GIRK4 oligomers in this tissue. These data indicate that GIRK1 and GIRK4 are excellent candidate subunits for the D(2)-activated, G protein-gated channel in pituitary lactotropes, where they play a critical role in excitation-secretion coupling.

Animals↗
PubMed2001

Imidazolines inhibit secretory responses of rat colonic mucosa to calcium-dependent but not cyclic AMP-dependent secretagogues.

The purpose of this study was to investigate whether imidazolines have an anti-secretory action on intestinal epithelial cells. Muscle-stripped preparations of rat colon and monolayers of T84 human colonic epithelial cells were set up in Ussing chambers for measurement of short-circuit current. In rat colon acetylcholine, histamine, vasoactive intestinal polypeptide and forskolin elicited secretory responses which were recorded as increases in short-circuit current. Secretory responses to acetylcholine were inhibited in a concentration-dependent manner by the imidazolines phentolamine, idazoxan and clonidine. The effect of clonidine was not reversed by pre-incubation of mucosal preparations with yohimbine. Secretory responses to vasoactive intestinal polypeptide were unaffected by the three imidazolines. Phentolamine reduced responses of colonic mucosa to histamine but had no effect on responses to forskolin. Responses to vasoactive intestinal polypeptide and forskolin were significantly reduced in the presence of barium. In T84 cell monolayers phentolamine significantly reduced responses to acetylcholine. Three imidazolines, two with alpha-adrenoceptor-antagonist properties and one with alpha-agonist properties, have anti-secretory effects in rat colonic mucosal preparations. The anti-secretory action appears to discriminate between calcium-dependent and cyclic AMP-dependent secretagogues, inhibiting the former but not the latter.

Adrenergic alpha-Agonists↗
PubMed2001

Annotation: conceptions of intelligence.

This paper argues for the scientific utility of the concept "intelligence". In the first section three common arguments against the validity of general intelligence are discussed and dismissed. The second section presents the evidence in favour of the proposition that individual differences in IQ may be based on differences in speed of information processing. However, the third section shows that executive functions, particularly inhibitory processes, represent a more likely basis for the development of intelligence. The theory of the minimal cognitive architecture underlying intelligence and development (Anderson, 1992a) shows how speed and executive functioning might represent two dimensions to g--one an individual differences (within age) dimension based on speed and the other a developmental dimension based on changing executive functioning. In the fourth section this theory is used to generate new insights on the nature of intellectual disability and specific cognitive deficits and to make practical suggestions for educational intervention for low-IQ children.

Cognition↗
PubMed2001

Attitudinal acceptance of intimate partner violence among U.S. adults.

Attitudinal acceptance of intimate partner violence (IPV) is an important correlate of violent behavior. This study examined acceptance of IPV using data collected from a nationally representative telephone survey of 5,238 adults. Multivariable logistic regression analyses were used to test for associations between sociodemographic characteristics, exposure to violence, question order, and acceptance of hitting a spouse or boyfriend/girlfriend under specific circumstances. Depending on the circumstance examined, acceptance of IPV was significantly higher among participants who were male and younger than 35; were non-White; were divorced, separated, or had never married; had not completed high school; had a low household income; or were victims of violence within the past 12 months. Participants were more accepting of women hitting men; they also were consistently more likely to report tolerance of IPV if they were asked first about women hitting men rather than men hitting women. Reports of IPV tolerance need to be interpreted within the context of the survey. Efforts to change IPV attitudes can be tailored to specific IPV circumstances and subgroups, and these efforts should emphasize that the use of physical violence is unacceptable to both genders.

Adolescent↗
PubMed2001

Sexual selection and the comparative anatomy of reproduction in monkeys, apes, and human beings.

Sexual selection has had profound effects at the copulatory and postcopulatory levels, upon the evolution of reproductive anatomy, physiology, and patterns of mating behavior. This review deals with the effects of sexual selection upon the evolution of relative testes sizes, sperm morphology, seminal vesicular function, penile morphology, and copulatory behavior in the Order Primates. The concept of cryptic female choice is also discussed, and its potential value in understanding how co-evolution of genital morphologies may have occurred in primates and inother animals.

Animals↗
PubMed2000

Association between dinucleotide repeat in non-coding region of interferon-gamma gene and susceptibility to, and severity of, rheumatoid arthritis.

BACKGROUND: Rheumatoid arthritis ranges from a mild, non-deforming arthropathy with little long-term disability to severe, incapacitating, deforming arthritis which may be refractory to conventional disease-modifying agents. Epidemiological studies show an important genetic influence in rheumatoid arthritis, and MHC region genes and cytokine genes within and outside this region have been considered as candidates. We did a case-control study to test whether polymorphisms in the interferon-gamma gene are associated with severity of rheumatoid arthritis. METHODS: Interferon gamma dinucleotide repeat polymorphisms were examined with quantitative genescan technology, and HLA-DR alleles were identified by PCR and restriction-fragment-length polymorphism analysis. We studied 60 patients with severe rheumatoid arthritis, 39 with mild disease, and 65 normal controls. FINDINGS: Susceptibility to, and severity of, rheumatoid arthritis were related to a microsatellite polymorphism within the first intron of the interferon-gamma gene. A 126 bp allele was seen in 44 (73%) of 60 patients with severe rheumatoid arthritis, compared with eight (21%) of 39 with mild disease (odds ratio 10.66 [95% CI 4.1-24.9]), and with eight (12%) of 65 normal controls (19.59 [7.7-49.9]). Conversely, a 122 bp allele at the same locus was found in four (7%) patients with severe disease compared with 25 (64%) of those with mild disease (0.04 [0.01-0.1]) and with 52 (80%) of controls (0.018 [0.005-0.06]). INTERPRETATION: This association may be valuable for understanding the mechanism of disease progression, for predicting the course of the disease, and for guiding therapy.

Adult↗
PubMed2000

Antiflow of K(0)(s) mesons in 6A GeV Au + Au collisions

We have measured the sideward flow of neutral strange ( K(0)(s)) mesons in 6A GeV Au+Au collisions. A prominent antiflow signal is observed for an impact parameter range ( b less, similar7 fm) which spans central and midcentral events. Since the K(0)(s) scattering cross section is relatively small in nuclear matter, this observation suggests that the in-medium kaon vector potential plays an important role in high density nuclear matter.

Journal Article↗
PubMed2000

Sideward flow in Au+Au collisions between 2A and 8A GeV

Using the large acceptance Time Projection Chamber of experiment E895 at Brookhaven, measurements of collective sideward flow in Au+Au collisions at beam energies of 2A, 4A, 6A, and 8A GeV are presented in the form of in-plane transverse momentum and the first Fourier coefficient of azimuthal anisotropy v(1). These measurements indicate a smooth variation of sideward flow as a function of beam energy. The data are compared with four nuclear transport models which have an orientation towards this energy range. All four exhibit some qualitative trends similar to those found in the data, although none show a consistent pattern of agreement within experimental uncertainties.

Journal Article↗
PubMed2000

Bombarding energy dependence of pi(-) interferometry at the brookhaven AGS

We present the first excitation function of pi(-) intensity interferometry at Alternating Gradient Synchrotron (AGS) energies (2-8 A GeV). The sensitivity of the multidimensional correlation functions to the geometry and dynamics of the pion-emitting system provides a stringent test of transport models of heavy ion collisions. Detailed comparisons with a realistic transport model, both with and without an explicit nuclear mean field, suggest that the beam energy evolution in the reaction dynamics is different in the model than in the data. A significantly increased pi(-) emission time scale, which has been suggested as a signal of the onset of the transition to quark-gluon plasma, is not observed.

Journal Article↗
PubMed2000

Biomarkers of immunotoxicity in fish: from the lab to the ocean.

Historically, host immunocompetence has been monitored using a battery of immune parameters. Recently, many of these same assays have been employed as biomarkers for predicting chemical-induced immunotoxicity in wildlife species. In this laboratory, assays measuring immunopathology, immune cell function, and host resistance against bacteria have been used successfully to assess immunotoxicity in laboratory-reared Japanese medaka (Oryzias latipes) and in feral fish populations. As an example of the latter, smallmouth bass collected from a PCB-contaminated site demonstrated significantly reduced phagocyte function and antioxidant activity compared to reference site fish. Taken together, these studies along with those from other investigators demonstrate the usefulness of immune assays as indicators to predict the toxicological risk associated with 'real-world' polluted aquatic environments.

Animals↗
PubMed2000

The effects of low frequency and two-pulse stimulation protocols on synaptic transmission in the CA1-subiculum pathway in the anaesthetized rat.

The downregulation of synaptic efficacy is referred to as long-term depression (LTD). Recent work has shown that a two-pulse stimulation (TPS) protocol is successful at inducing LTD in vivo in area CA1 of the hippocampus. Here, we examine the ability of two TPS protocols and two low-frequency stimulation (LFS) protocols to induce LTD in the projection from hippocampal area CA1 to the subiculum in the anaesthetized rat. We find no evidence of LTD induction with TPS or LFS protocols. Instead, with three of the protocols (both TPS protocols and 1 Hz LFS), a late-developing potentiation is observed.

Animals↗
PubMed2000

Cell-specific, activation-dependent regulation of neutrophil CD32A ligand-binding function.

Neutrophils express 2 low-affinity FcgammaR, FcgammaRIIIB (CD16B), and FcgammaRIIA (CD32A). CD16B is a glycosyl-phosphatidyl inositol-anchored molecule, whereas CD32A is a polypeptide-anchored molecule. These 2 receptors also differ in their signaling. The biological significance of coexpression of 2 FcgammaRs with distinct membrane anchors and signaling capacities is not clearly understood. Using neutrophils from a CD16B-deficient donor and normal neutrophils treated with anti-CD16 monoclonal antibodies, the authors demonstrated that affinity modulation of CD32A is one of the mechanisms by which neutrophils regulate their FcgammaR-dependent functions. Neutrophils isolated from a CD16B(- )donor rosetted poorly with sheep erythrocytes opsonized with rabbit IgG (EA) (12% +/- 2% versus 80% +/- 6% for control) and were unable to mediate immunophagocytosis. However, activation of CD16B(-) neutrophils with fMLP, a bacterial chemotactic peptide, increased the CD32A-dependent EA rosetting to 58%. The CD32A-dependent rosetting of fMLP-activated normal neutrophils also increased nearly 5-fold, but there was no increase in CD32A expression. The CD32A-dependent immune complex (IC) binding was also increased in activated neutrophils. This affinity regulation was not observed with CD32A expressed on Chinese hamster ovary cells. These results suggest that in resting neutrophils CD32A is in a low-affinity state and that these cells primarily engage CD16B for IC binding. However, once the neutrophils are activated, the CD32A is converted to a high-affinity state that leads to CD32A-dependent ligand binding and signaling. These results suggest that neutrophils adopt a novel strategy to engage the 2 different FcgammaR selectively during physiologic and pathologic conditions to carry out their functions efficiently.

Animals↗
PubMed2000

UK CropNet: a collection of databases and bioinformatics resources for crop plant genomics.

The UK Crop Plant Bioinformatics Network (UK CropNet) was established in 1996 in order to harness the extensive work in genome mapping in crop plants in the UK. Since this date we have published five databases from our central UK CropNet WWW site (http://synteny.nott.ac.uk/) with a further three to follow shortly. Our resource facilitates the identification and manipulation of agronomically important genes by laying a foundation for comparative analysis among crop plants and model species. In addition, we have developed a number of software tools that facilitate the visualisation and analysis of our data. Many of our tools are made freely available for use with both crop plant data and with data from other species.

Crops, Agricultural↗
PubMed2000

Synaptic plasticity in the hippocampal area CA1-subiculum projection: implications for theories of memory.

This paper reviews investigations of synaptic plasticity in the major, and underexplored, pathway from hippocampal area CA1 to the subiculum. This brain area is the major synaptic relay for the majority of hippocampal area CA1 neurons, making the subiculum the last relay of the hippocampal formation prior to the cortex. The subiculum thus has a very major role in mediating hippocampal-cortical interactions. We demonstrate that the projection from hippocampal area CA1 to the subiculum sustains plasticity on a number of levels. We show that this pathway is capable of undergoing both long-term potentiation (LTP) and paired-pulse facilitation (PPF, a short-term plastic effect). Although we failed to induce long-term depression (LTD) of this pathway with low-frequency stimulation (LFS) and two-pulse stimulation (TPS), both protocols can induce a "late-developing" potentiation of synaptic transmission. We further demonstrate that baseline synaptic transmission can be dissociated from paired-pulse stimulation of the same pathway; we also show that it is possible, using appropriate protocols, to change PPF to paired-pulse depression, thus revealing subtle and previously undescribed mechanisms which regulate short-term synaptic plasticity. Finally, we successfully recorded from individual subicular units in the freely-moving animal, and provide a description of the characteristics of such neurons in a pellet-chasing task. We discuss the implications of these findings in relation to theories of the biological consolidation of memory.

Animals↗
PubMed2000

Soft tissue injuries to USA paralympians at the 1996 summer games.

OBJECTIVE: To report the soft tissue injuries sustained by the members of four disabled sports organizations (DSOs) who competed as the USA Team at the 1996 Paralympic Games. SETTING: 1996 Paralympic Games, Atlanta, Georgia. METHODS: Soft tissue (strain, sprain, tendonitis, bursitis, or contusion) injury frequencies sustained by Disabled Sports USA (DSUSA, n = 66), the United States Association for Blind Athletes (USABA, n = 53), the United States Cerebral Palsy Athletic Association (USCPAA, n = 56), and Wheelchair Sports USA (WSUSA, n = 129) athletes were compared by body region with chi-square tests (p<.05) and standardized residual assessment. RESULTS: A total of 254 soft tissue injuries (67% acute onset, 170/254) were sustained by the participant DSO members. Statistical design limitations and poor USCPAA athlete homogeneity prompted their exclusion from group comparisons (descriptive results are reported). The most common injury regions for specific DSOs were shoulder (26%), hip-thigh (14%), and ankle (12%) for DSUSA; hip-thigh (21%), cervicothoracic region (19%), and shoulder (17%) for USABA; lumbar region (14%), foot-toe (13%), and ankle (9%) for USCPAA; and shoulder (18%), arm-elbow (12%), forearm-wrist (12%), and lumbar region (9%) for USUSA. Chi-square residual analysis showed that the USABA athletes contributed more to cervicothoracic and lower leg region injury frequencies than DSUSA or WSUSA athletes. The WSUSA athletes contributed more to elbow-arm and forearm-wrist region injury frequencies than DSUSA or USABA athletes. The DSUSA athletes contributed more to ankle region injury frequencies than USABA or WSUSA athletes. CONCLUSIONS: Differences in soft tissue injury frequency among athletes of differing DSOs suggest that the competitive use of adaptive or assistive devices, in combination with sport-specific stressors and the athletes' disabilities, is related to the development of predictable soft tissue injury patterns. The decreased incidence of shoulder injury among WSUSA athletes suggests that the injury prevention advice provided by previous studies is being implemented among athletes at this competitive level. The increased incidence of ankle injuries among DSUSA athletes suggests lower extremity load imbalances (prosthetic vs. uninvolved) during running. The increased incidence of lower leg injuries among USABA athletes suggests "overuse" injury patterns typical of nondisabled runners, or inadvertent contacts (contused shins), whereas the increased incidence of cervicothoracic injuries suggests injuries related to falls, "near falls," or sudden directional changes prompted by guidance aids.

Athletic Injuries↗