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Biomedical subjects

A Harris

Publications and source records attributed to A Harris.

At least 235 records · Page 13Linked to original sources
PubMed1997

Correlates of battering among 997 men: family history, adjustment, and attitudinal differences.

In order to identify the characteristics associated with physical abuse of female partners, a detailed questionnaire was administered to 997 men who were recruited from either a forensic out-patient clinic (780) or from a community based employment center (217). This questionnaire sampled family and personal history, criminal behavior, psychopathology, and attitudes towards violence. Based upon self-report, the sample was divided into 184 non-abusive men, 517 moderately abusive men, and 296 severely abusive men. The full sample (997) was randomly divided into two subsamples and then, using a cross-validation design, group differences were identified in both subsamples on 46 of the 93 variables examined in this study. All significant effects were linear, such that the average scores of the severely abusive men were worse than the scores of the abusive men who, in turn, scored worse than the non-abusive men. In general, both groups of abusive men reported high rates of violence during childhood (both as victims and perpetrators), antisocial personality disorder, subjective distress, marital maladjustment, attitudes tolerant of spouse assault, and a range of impulsive behaviors (impulsive violence, substance abuse, motor vehicle accidents). The factors that correlated with abuse in the total sample also correlated with abuse in the community sample.

Adult↗
PubMed1996

A 22 kDa protein associated with the Plasmodium falciparum merozoite surface protein-1 complex.

The Plasmodium falciparum merozoite surface protein-1 (MSP-1) is synthesized as a precursor of approximately 195 kDa and is processed to form a complex of polypeptides on the surface of free merozoites. As a result of a second processing event, the entire MSP-1 complex is shed from the surface, apart from a C-terminal fragment that remains anchored to the merozoite membrane. We have identified a 22 kDa protein (p22) on the surface of merozoites by cell surface radioiodination and indirect immunofluorescence assay on unfixed free merozoites. p22 is also a component of the shed MSP-1 complex where it is present in part as a 19 kDa form (p22(19)) as shown by immunochemical and peptide mapping analyses. The soluble complex contains MSP-1-derived polypeptides and p22 in approximately stoichiometrically equal amounts. N-terminal amino acid sequence analyses of p22/p22(19) showed that the protein is not derived from the MSP-1 precursor.

Amino Acid Sequence↗
PubMed1996

Hydrostatic pressure has different effects on the assembly of tubulin, actin, myosin II, vinculin, talin, vimentin, and cytokeratin in mammalian tissue cells.

Hydrostatic pressures in the range of hundreds of atmospheres are known to disrupt cytoskeletal organization in tissue culture cells, with profound changes in cell shape. The molecular mechanisms of these effects are poorly understood. To determine the effect of pressure on the cytoskeleton, and thus to provide better indicators of the molecular mechanisms, we used fluorescent antibody staining to compare the organizations of seven different cytoskeletal proteins in HeLa cells and rat osteosarcoma cells (ROS-17/2.8) subjected to different pressures up to 400 atm. Pressures of 300 atm or more caused cells of both lines to "round up" and to withdraw their lamellar extensions. However, this response varied within a population of cells, with some cells remaining spread at pressures that caused their neighbors to round up. The most resistant to rounding were those cells touching other cells, and the occasional giant cells. As expected, the rounded cells showed disruption of actin stress fibers and of vinculin and talin at focal contacts. The unrounded cells showed less disruption in the organization of these same proteins. Microtubules and myosin II filaments appeared resistant to 400 atm pressure in both cell types, whether rounded or unrounded. However, in HeLa cells, the intermediate filaments, vimentin and cytokeratin, depolymerized and formed small vesicles when pressures exceeded 200 atm, and this occurred in rounded as well as unrounded cells. In osteosarcoma cells, which do not have cytokeratin, vimentin did not depolymerize. We discuss different mechanisms that might explain these responses to pressure, including direct effects on the equilibria of protein polymerization and less direct effects on regulatory mechanisms, such as phosphorylation pathways, that control cytoskeletal organization. The later type of explanation seems more consistent with both the variability of response within cell populations and the difference in vimentin's response in one cell line compared with the other.

Actins↗
PubMed1996

COOH-terminal extended recombinant amphiregulin with bioactivity comparable with naturally derived growth factor.

The mature secreted form of the epidermal growth factor (EGF) receptor ligand amphiregulin (AR) is reported to be an 84-amino acid residue polypeptide, which is generated by proteolytic processing of a 252-amino acid precursor. This form of recombinant AR (rAR84) and two forms with COOH-terminal extensions corresponding to sequences from the AR precursor (rAR87 and rAR92) were expressed at high levels in Escherichia coli, oxidized to the correct disulfide arrangement, and purified to homogeneity. rAR84 competed poorly for binding of radiolabeled EGF to the EGF receptor and had little ability to stimulate growth of Balb/c/3T3 cells. In striking contrast, rAR87 and rAR92 possessed 42- and 20-fold greater receptor binding activity and 55- and 14-fold greater bioactivity, respectively. Furthermore, addition of the COOH-terminal four amino acids from transforming growth factor alpha to the COOH terminus of rAR84 improved the activity of rAR84 by 100- and 1000-fold, respectively, in these assays. rAR87 was found to have approximately 32% of the specific activity of natural AR from MCF-7 cells when compared in two different bioassays. These findings strongly suggest that the 84-amino acid sequence is not the correct structure of the naturally occurring secreted form of AR and that natural AR contains additional amino acid residues at the COOH-terminal end.

3T3 Cells↗
PubMed1996

Zidovudine use to reduce perinatal HIV type 1 transmission in an urban medical center.

OBJECTIVE: To evaluate whether zidovudine treatment was accepted and used by pregnant women subsequent to the release of the results of a multicenter, randomized, placebo-controlled trial (AIDS Clinical Trial Group [ACTG] Protocol 076) that showed that zidovudine significantly reduced maternal-infant human immunodeficiency virus (HIV) type 1 transmission. DESIGN: Prospective study. SETTING: A community hospital with an integrated, multidisciplinary HIV-dedicated program located in an impoverished, HIV-endemic urban setting. PARTICIPANTS: All HIV-infected pregnant women identified after the release of the ACTG 076 results who were offered zidovudine therapy to reduce maternal-infant transmission. RESULTS: Only 49 of the 125 HIV-infected pregnant women delivering at our site during this study period were identified prenatally. Perinatal zidovudine therapy was chosen by 37 (75%) of 49 women. Women refusing zidovudine were more likely to report injection drug use as their HIV risk factor and to continue to use drugs during their pregnancy. Of women choosing zidovudine and delivering, 24 of 36 received all components of their elected therapy. The intrapartum dose was missed by 12 women, 4 of whom also missed their prescribed prenatal oral therapy. Lack of adherence to chosen therapy was associated with continued cocaine use during pregnancy. CONCLUSIONS: Zidovudine therapy to interrupt vertical transmission of HIV was not widely used by these HIV-infected pregnant women. Further studies evaluating factors affecting the acceptance and use of recently published public health recommendations are needed.

Adolescent↗
PubMed1996

A regulatory element in intron 1 of the cystic fibrosis transmembrane conductance regulator gene.

The cystic fibrosis transmembrane conductance regulator (CFTR) gene exhibits a tightly regulated pattern of expression in human epithelial cells. The mechanism of this regulation is complex and is likely to involve a number of genetic elements that effect temporal and spatial expression. To date none of the elements that have been identified in the CFTR promoter regulate tissue-specific expression. We have identified a putative regulatory element within the first intron of the CFTR gene at 181+10kb. The region containing this element was first identified as a DNase I hypersensitive site that was present in cells that express the CFTR gene but absent from cells not transcribing CFTR. In vitro analysis of binding of proteins to this region of DNA sequence by gel mobility shift assays and DNase I footprinting revealed that some proteins that are only present in CFTR-expressing cells bound to specific elements, and other proteins that bound to adjacent elements were present in all epithelial cells irrespective of their CFTR expression status. When assayed in transient expression systems in a cell line expressing CFTR endogenously, this DNA sequence augmented reporter gene expression through activation of the CFTR promoter but had no effect in nonexpressing cells.

Base Sequence↗
PubMed1996

Kinetic analysis of inositol trisphosphate binding to pure inositol trisphosphate receptors using scintillation proximity assay.

Inositol 1,4,5-triphosphate (InsP3) receptors are regulated by many intracellular signals including proteins and small messengers. By linking purified cerebellar InsP3 receptors to scintillation proximity assay beads, binding of radioligands can be measured without separation of bound from free ligand. InsP3 receptors assayed by scintillation proximity assay bound heparin with high affinity and stereoselectively bound InsP3 with similar affinity to cerebellar membranes. By rapidly freezing scintillation proximity assay reactions and then counting the frozen samples, both fast and slow components of [3H] InsP3 association and dissociation were identified. Our novel freeze-quench method in combination with conventional stopped-quench equipment and scintillation proximity assay allows the rapid kinetics of the interactions of pure receptors with their ligands to be resolved.

Calcium Channels↗
PubMed1996

Protein synthesis-dependent formation of protein kinase Mzeta in long-term potentiation.

The maintenance of long-term potentiation (LTP) in the CA1 region of the hippocampus has been reported to require both a persistent increase in phosphorylation and the synthesis of new proteins. The increased activity of protein kinase C (PKC) during the maintenance phase of LTP may result from the formation of PKMzeta, the constitutively active fragment of a specific PKC isozyme. To define the relationship among PKMzeta, long-term EPSP responses, and the requirement for new protein synthesis, we examined the regulation of PKMzeta after sub-threshold stimulation that produced short-term potentiation (STP) and after suprathreshold stimulation by single and multiple tetanic trains that produced LTP. We found that, although no persistent increase in PKMzeta followed STP, the degree of long-term EPSP potentiation was linearly correlated with the increase of PKMzeta. The increase was first observed 10 min after a tetanus that induced LTP and lasted for at least 2 hr, in parallel with the persistence of EPSP enhancement. Both the maintenance of LTP and the long-term increase in PKMzeta++ were blocked by the protein synthesis inhibitors anisomycin and cycloheximide. These results suggest that PKMzeta is a component of a protein synthesis-dependent mechanism for persistent phosphorylation in LTP.

Animals↗
PubMed1996

Human enteric defensins. Gene structure and developmental expression.

Paneth cells, secretory epithelial cells of the small intestinal crypts, are proposed to contribute to local host defense. Both mouse and human Paneth cells express a collection of antimicrobial proteins, including members of a family of antimicrobial peptides named defensins. In this study, data from an anchored polymerase chain reaction (PCR) strategy suggest that only two defensin mRNA isoforms are expressed in the human small intestine, far fewer than the number expressed in the mouse. The two isoforms detected by this PCR approach were human defensin family members, HD-5 and HD-6. The gene encoding HD-6 was cloned and characterized. HD-6 has a genomic organization similar to HD-5, and the two genes have a striking pattern of sequence similarity localized chiefly in their proximal 5'-flanking regions. Analysis of human fetal RNA by reverse transcriptase-PCR detected enteric defensin HD-5 mRNA at 13.5 weeks of gestation in the small intestine and the colon, but by 17 weeks HD-5 was restricted to the small intestine. HD-6 mRNA was detectable at 13.5-17 weeks of gestation in the small intestine but not in the colon. This pattern of expression coincides with the previously described appearance of Paneth cells as determined by ultrastructural approaches. Northern analysis of total RNA from small intestine revealed quantifiable enteric defensin mRNA in five samples from 19 24 weeks of gestation at levels approximately 40-250-fold less than those observed in the adult, with HD-5 mRNA levels greater than those of HD-6 in all samples. In situ hybridization analysis localized expression of enteric defensin mRNA to Paneth cells at 24 weeks of gestation, as is seen in the newborn term infant and the adult. Consistent with earlier morphological studies, the ratio of Paneth cell number per crypt was reduced in samples at 24 weeks of gestation compared with the adult, and this lower cell number partially accounts for the lower defensin mRNA levels as determined by Northern analysis. Low levels of enteric defensin expression in the fetus may be characteristic of an immaturity of local defense, which is thought to predispose infants born prematurely to infection from intestinal microorganisms.

Amino Acid Sequence↗
PubMed1996

Interaction of ethanol with inducers of glucose-regulated stress proteins. Ethanol potentiates inducers of grp78 transcription.

GRP78, a molecular chaperone expressed in the endoplasmic reticulum, is a "glucose-regulated protein" induced by stress responses that deplete glucose or intracisternal calcium or otherwise disrupt glycoprotein trafficking. Previously we showed that chronic ethanol exposure increases the expression of GRP78. To further understand the mechanism underlying ethanol regulation of GRP78 expression, we studied the interaction between ethanol and classical modulators of GRP78 expression in NG108-15 neuroblastoma x glioma cells. We found that, in addition to increasing basal levels of GRP78 mRNA ("induction"), ethanol produced greater than additive increases in the induction of GRP78 mRNA by the "classical" GRP inducers A23187, brefeldin A, and thapsigargin ("potentiation"). Both the ethanol induction and potentiation responses modulated grp78 gene transcription as determined by stable transfection analyses with the rat grp78 promoter. Ethanol potentiated the action of all classical inducers of grp78 transcription that were studied. In contrast, co-treatment with the classical GRP inducers thapsigargin and tunicamycin produced only simple additive increases in grp78 promoter activity. Transient transfection studies with deletion mutants of the rat grp78 promoter showed that cis-acting promoter sequences required for ethanol induction differ from those mediating responses to classical GRP inducers. Furthermore, linker-scanning mutations of the grp78 promoter suggested that the ethanol potentiation response required a cis-acting promoter element different from those involved in induction by ethanol or classical inducing agents. While the ethanol induction response required 16-24 h to be detectable, ethanol potentiation of thapsigargin occurred within 6 h. The potentiation response also decayed rapidly after ethanol removal. In addition, the protein kinase A inhibitor Rp-cAMPS and protein phosphatase inhibitor okadaic acid both increased ethanol potentiation of thapsigargin while Sp-cAMPS, an activator of protein kinase A, decreased ethanol potentiation. Taken together, our findings suggest two mechanisms by which ethanol regulates grp78 transcription, both differing from the action of classical GRP inducers such as thapsigargin. One mechanism (potentiation) involves a protein phosphorylation cascade and potentiates the action of classical GRP inducers. In contrast, GRP78 induction by ethanol involves promoter sequences and a mechanistic pathway separate from that of the ethanol potentiation response or classical GRP78 inducers. These studies show that ethanol produces a novel and complex regulation of grp78 transcription which could be of particular importance during neuronal exposure to GRP-inducing stressors as might occur with central nervous system injury.

Animals↗
PubMed1996

Retinal blood flow during dynamic exercise.

BACKGROUND: Exercise acutely lowers intraocular pressure (IOP) and raises arterial pressure. We wondered whether the resultant increase in ocular perfusion pressure would alter retinal blood flow. METHODS: To investigate this question, 11 healthy volunteers each performed progressive cycle ergometer exercise until exhaustion was reached in 5-10 min. Immediately after exercise, retinal blood flow and arteriovenous passage time were determined by video fluorescein angiography. Ten other volunteers performed repeated episodes of cycle ergometer exercise at approximately 60% of the maximal aerobic capacity, immediately prior to estimates of macular leukocyte velocity and density via blue-field stimulation. RESULTS: Progressive exercise lowered IOP and elevated calculated ocular perfusion pressure. Within the retinal circulation, this exercise tended to raise mean dye velocity, as it significantly narrowed the superior temporal artery and vein; as a result, calculated retinal blood flow was unchanged. Simultaneously, retinal arteriovenous passage time was substantially shortened. Blue-field simulation showed that exercise increased macular leukocyte velocity while leaving leukocyte density unchanged. CONCLUSIONS: These results show that the normal retinal hemodynamic response to increases in perfusion pressure on dynamic exercise includes vasoconstriction that normalizes flow and faster capillary and overall retinal blood transit.

Adult↗
PubMed1996

Volume-sensitive chloride currents in primary cultures of human fetal vas deferens epithelial cells.

Using the patch-clamp technique, we have identified a large, outwardly rectifying, Cl--selective whole-cell current in primary cultures of human vas deferens epithelial cells. Whole-cell currents were time- and voltage-dependent and displayed inactivation following depolarising pulses >/= 60 mV. Currents were equally permeable to bromide (PBr/PCl = 1.05 +/- 0.04), iodide (PI/PCl = 1. 06 +/- 0.07) and Cl-, but significantly less permeable to gluconate (PGluc /PCl = 0.23 +/- 0.03). Currents spontaneously increased with time after establishing a whole-cell recording, but could be inhibited by exposure to a hypertonic bath solution which reduced inward currents by 68 +/- 4%. Subsequent exposure of the cells to a hypotonic bath solution led to a 418 +/- 110% increase in inward current, indicating that these currents are regulated by osmolarity. 4,4'-Diisothiocyanatostilbene-2,2'-disulphonic acid (100 microM) produced a rapid and reversible voltage-dependent block (60 +/- 5% and 10 +/- 7% inhibition of current, measured at +/- 60 mV, respectively). Dideoxyforskolin (50 microM) also reduced the volume-sensitive Cl- current, but with a much slower time course, by 41 +/- 13% and 32 +/- 16% (measured at +/- 60 mV, respectively). Tamoxifen (10 microM) had no effect on the whole-cell Cl- current. These results suggest that vas deferens epithelial cells possess a volume-sensitive Cl- conductance which has biophysical and pharmacological properties broadly similar to volume-sensitive Cl- currents previously described in a variety of cell types.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1996

Two barium binding sites on a maxi K+ channel from human vas deferens epithelial cells.

Using the patch clamp technique, we have investigated the blockade of maxi-K+ channels present on vas deferens epithelial cells by extracellular Ba2+. With symmetrical 140 mM K+ solutions, Ba2+ produced discrete blocking events consisting of both long closings of seconds duration (slow block) and fast closings of milliseconds duration (flickering block). Kinetic analysis showed that flickering block occurred according to an "open channel blocking" scheme and was eliminated by reducing external K+ to 4.5 mM. Slow block showed a complex voltage-dependence. At potentials between -20 mV and 20 mV, blockade was voltage-dependent; at potentials greater than 20 mV, blockade was voltage-independent, but markedly sensitive to the extracellular K+ concentration. These data reveal that the vas deferens maxi-K+ channel has two Ba2+ binding sites accessible from the extracellular side. Site one is located at the cytoplasmic side of the gating region and binding to this site causes flickering block. Site two is located close to the extracellular mouth of the channel and binding to this site causes slow block.

Barium↗
PubMed1996

Bcl-2 and p53 expression in node-negative breast carcinoma: a study with long-term follow-up.

Bcl-2 and p53 gene products (Bcl-2, p53) are important regulators of apoptosis and cell proliferation, and their immunohistochemical expression may help to identify high-risk breast cancer patients. The authors evaluated p53 and Bcl-2 immunoreactivity in 178 node-negative breast cancers (NNBC) with long-term follow-up (median, 60 months). Bcl-2 was seen in 111 (62%) cases, and was significantly associated with small tumor size, nonductal morphology, low tumor grade, estrogen-receptor (ER) positivity, and p53 negativity. p53 overexpression (ie, > 15% reactive nuclei) was observed in 31 (17%) cases, and was associated with lower age, large tumor size, ductal morphology, high tumor grade, negative ER status, and lack of Bcl-2 immunoreactivity. In univariate analysis, the variables associated with short relapse-free survival (RFS) were large tumor size (P = .002), high histological grade (P = .01), high mitotic count (P = .03), and high Nottingham prognostic index (NPI) (P = .0002). In multivariate analysis (final model), only the NPI was of independent prognostic value concerning RFS.

Analysis of Variance↗
PubMed1996

Handicap in Darier's disease and Hailey-Hailey disease.

One hundred and thirty-seven patients with Darier's disease and 66 patients with Hailey-Hailey disease completed the Dermatology Life Quality Index (DLQI). The average DLQI score for Darier's disease was 5.89 (19.6% of the maximum score), median = 4, quartiles: 1.9. The average DLQI score for Hailey-Hailey disease was 6.06 (20.2% of the maximum score), median = 5, quartiles: 2.9. The DLQI score did not correlate with the physician's assessment of clinical severity in both diseases, thus emphasizing the importance of remembering the potential for handicap even in patients with disease that seems to be mild. The domains of the questionnaire with the highest mean scores in both diseases were for questions relating to symptoms and feelings. Domains relating to personal relationships and work obtained low mean scores even in severe disease. It is encouraging that most patients with Darier's disease and Hailey-Hailey disease maintain good relationships at work and home and seem to be able to adapt to their skin disease.

Adolescent↗