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R Boland

Publications and source records attributed to R Boland.

At least 19 recordsLinked to original sources
PubMed2001

Parathyroid hormone activation of map kinase in rat duodenal cells is mediated by 3',5'-cyclic AMP and Ca(2+).

In a previous study, we demonstrated that parathyroid hormone (PTH) stimulates in rat duodenal cells (enterocytes) the phosphorylation and activity of extracellular signal-regulated mitogen-activated protein kinase (MAPK) isoforms ERK1 and ERK2. As PTH activates adenylyl cyclase (AC) and phospholipase C and increases intracellular Ca(2+) in these cells, in the present study we evaluated the involvement of cAMP, Ca(2+) and protein kinase C (PKC) on PTH-induced MAPK activation. We found that MAPK phosphorylation by the hormone did not depend on PKC activation. PTH response could, however, be mimicked by addition of forskolin (5-15 microM), an AC activator, or Sp-cAMP (50-100 microM), a cAMP agonist, and suppressed to a great extent by the AC inhibitor, compound Sq-22536 (0.2-0.4 mM) and the cAMP antagonist Rp-cAMP (0.2 mM). Removal of external Ca(2+) (EGTA 0.5 mM), chelation of intracellular Ca(2+) with BAPTA (5 microM), or blockade of L-type Ca(2+)-channels with verapamil (10 microM) significantly decreased PTH-activation of MAPK. Furthermore, a similar degree of phosphorylation of MAPK was elicited by the Ca(2+) mobilizing agent thapsigargin, the Ca(2+) ionophore A23187, ionomycin and membrane depolarization with high K(+). Inclusion of the calmodulin inhibitor fluphenazine (50 microM) did not prevent hormone effects on MAPK. Taken together, these results indicate that cAMP and Ca(2+) play a role upstream in the signaling mechanism leading to MAPK activation by PTH in rat enterocytes. As Ca(2+) and cAMP antagonists did not block totally PTH-induced MAPK phosphorylation, it is possible that linking of the hormone signal to the MAPK pathway may additionally involve Src, which has been previously shown to be rapidly activated by PTH. Of physiological significance, in agreement with the mitogenic role of the MAPK cascade, PTH increased enterocyte DNA synthesis, and this effect was blocked by the specific inhibitor of MAPK kinase (MEK) PD098059, indicating that hormone modulation of MAPK through these messenger systems stimulates duodenal cell proliferation.

Animals↗
PubMed2001

Differential cellular localization of estrogen receptor alpha in uterine and mammary cells.

The classical alpha isoform of the estrogen receptor (ER) has been reported to localize almost exclusively in the nucleus. However, studies on non-genomic steroid effects have also suggested the existence of ERs residing at the cell surface. In this work, we present immunological data supporting extra-nuclear ERalpha localization in uterine (SHM) and mammary (MCF-7) cell lines. Immunocytological studies performed on SHM cells revealed that native ERs mainly localize as a perinuclear cytoplasmic ring. The receptors were rapidly translocated to the nucleus by 17beta-estradiol. In addition to nuclear ERs, a peripheral reservoir of ERalpha immunoreactivity, most probably associated with the plasma membrane, was detected in MCF-7 cells. These results were confirmed by the detection of membrane estrogen binding sites using fluorescent estrogen-BSA derivatives and ligand binding assays to intact cells, where [3H]-estradiol could be partly displaced by impeded estrogen conjugates. Partial inhibition of radioligand binding by an antibody against the steroid binding domain of the ERalpha suggests that the isoform faces the extracellular media in MCF-7 cells. Moreover, ERalpha-like proteins ( approximately 67 kDa) were found to be associated in isolated membrane subfractions from the cells. However, immunocytology of COS-1 (ER-negative) and SHM cells transfected with the complete cDNA coding for the cloned ERalpha and beta isoforms showed exclusive nuclear localization of the overexpressed ERs. The non-classical distribution of native ERalpha-like proteins in each cell line, suggests an alternative mode of ERalpha cellular localization/function. Cell type-dependent processing may account for the differential localization shown by native and expressed receptors in the systems considered.

Animals↗
PubMed2001

The stimulation of MAP kinase by 1,25(OH)(2)-vitamin D(3) in skeletal muscle cells is mediated by protein kinase C and calcium.

In previous work we have demonstrated that the steroid hormone 1,25(OH)(2)-vitamin D(3) [1,25(OH)(2)D(3)] stimulates in skeletal muscle cells the phosphorylation and activity of the extracellular signal-regulated mitogen-activated protein (MAP) kinase isoforms ERK1 and ERK2. In the present study we evaluated the involvement of Ca(2+) and protein kinase C (PKC) on 1,25(OH)(2)D(3)-induced activation of MAP kinase. The hormone response was found to depend on PKC stimulation since it was attenuated by the PKC inhibitors calphostin C (100 nM) and bisindolylmaleimide I (30 nM) and PKC downregulation by prolonged treatment with the phorbol ester TPA (1 microM). Removal of external Ca(2+), chelation of intracellular Ca(2+) with BAPTA (5 microM), inhibition of phosphoinositide-phospholipase C (PLC) by neomycin, the calmodulin antagonist fluphenazine (50 microM) and the specific inhibitor of calmodulin kinase II, KN-62 (10 microM), significantly decreased 1,25(OH)(2)D(3)-activation of MAP kinase. In addition, the Ca(2+)-channel blocker verapamil (5 microM) suppressed hormone-induced MAP kinase activity in these cells. Furthermore, the Ca(2+)-mobilizing agent thapsigargin and the Ca(2+)-inophore A23187 paralleled the phosphorylation of MAP kinase observed with 1,25(OH)(2)D(3). Taken together, these results indicate that PKC and Ca(2+) are two upstream activators mediating the effects of 1,25(OH)(2)D(3) on MAP kinase in skeletal muscle cells.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed2001

Neurocognitive performance enhanced by highly active antiretroviral therapy in HIV-infected women.

OBJECTIVE: To determine whether highly active retroviral therapy (HAART) is associated with better neurocognitive outcome over time among HIV-infected women with severely impaired immune function. METHODS: A semiannual neurocognitive examination on four tasks was administered: Color Trail Making, Controlled Oral Word Association, Grooved Pegboard and Four-Word Learning. This protocol was initiated in the HIV Epidemiological Research study (HERS) study when a woman's CD4 cell count fell to < 100 x 10(6) cells/l. Immune function (CD4), viral load status and depression severity (CESD) were also assessed semi-annually, along with an interview to determine medication intake and illicit drug use. RESULTS: HAART was not available to any participant at the time of enrollment (baseline), while 44% reported taking HAART at their most recent visit (mean duration of HAART 36.3 +/- 12.6 months). HAART-treated women had improved neurocognitive performance compared with those not treated with HAART. Women taking HAART for 18 months or more showed the strongest neurocognitive performance with improved verbal fluency, psychomotor and executive functions. These functions worsened among women not taking HAART. Substance abuse status, severity of depressive symptoms, age and educational level did not influence the HAART treatment effects on neurocognitive performance. Neurocognitive improvements were strongly associated with the magnitude of CD4 cell count increases. CONCLUSIONS: HAART appeared to produce beneficial effect on neurocognitive functioning in HIV-infected women with severely impaired immune systems. Benefits were greatest for women who reported receiving HAART for more than 18 months.

Adolescent↗
PubMed2001

Subcellular distribution of native estrogen receptor alpha and beta isoforms in rabbit uterus and ovary.

The association of estrogen receptors with non-nuclear/cytoplasmic compartments in target tissues has been documented. However, limited information is available on the distribution of estrogen receptor isoforms, specially with regard to the newly described beta isotype. The subcellular localization of estrogen receptor alpha and beta isoforms was investigated in rabbit uterus and ovary. Native alpha and beta subtypes were immunodetected using specific antibodies after subjecting the tissue to fractionation by differential centrifugation. The ovary expressed alpha and beta estrogen receptors in predominant association to cytosolic components. However, in the uterus, a substantial proportion of the total estrogen binding capacity and coexpression of the two isoforms was detected in mitochondria and microsomes. The mitochondrial-enriched subfraction represented an important source of 17beta-estradiol binding, where the steroid was recognized in a stereospecific and high affinity manner. The existence of mitochondrial and membrane estrogen binding sites correlated with the presence of estrogen receptor alpha but mainly with estrogen receptor beta proteins. Using macromolecular 17beta-estradiol derivatives in Ligand Blot studies, we could confirm that both alpha and beta isoforms were expressed as the major estrogen binding proteins in the uterus, while estrogen receptor alpha was clearly the dominant isoform in the ovary. Other low molecular weight estrogen receptor alpha-like proteins were found to represent an independent subpopulation of uterine binding sites, expressed to a lesser extent. This differential cellular partitioning of estrogen receptor alpha and beta forms may contribute to the known diversity of 17beta-estradiol effects in target organs. Both estrogen receptor alpha and beta expression levels and cellular localization patterns among tissues, add complexity to the whole estrogen signaling system, in which membrane and mitochondrial events could also be implicated.

Animals↗
PubMed2001

Effect of culture conditions on the synthesis of vitamin D(3) metabolites in Solanum glaucophyllum grown in vitro.

In cultured Solanum glaucophyllum we have recently described the operation of a light-independent pathway of 1alpha,25-dihydroxy-vitamin D(3) (1alpha,25(OH)(2)D(3)) biosynthesis which involves similar intermediates as in vertebrates. In this work we investigated factors influencing the formation of 1alpha,25(OH)(2)D(3) and related sterols in S. glaucophyllum grown in vitro in darkness. Callus tissue and cells cultured in Murashige and Skoog medium in the absence of light were employed. Lipids were extracted with chloroform-methanol. The remaining water soluble fraction was incubated with beta-glucosidase to release vitamin D(3) compounds from their glycoconjugated derivatives followed by organic solvent extraction. Vitamin D(3) derivatives were isolated by Sephadex LH-20 and high-performance liquid chromatography (HPLC). HPLC or competitive protein binding assays with intestine 1alpha,25(OH)(2)D(3) receptor and serum vitamin D binding protein were used to quantify the metabolites. The levels of 1alpha,25(OH)(2)D(3) in calli varied according to the tissue explant origin, e.g. stem>leaf>fruit. For all organs, the metabolite was mainly present as free sterol (>80% of total). There were larger amounts of 25(OH)D(3) than 1alpha,25(OH)(2)D(3). It was found that Ca(2+), auxin and kinetin are important factors upregulating 1alpha,25(OH)(2)D(3) synthesis in S. glaucophyllum tissue and cells. Irradiation with UV light increased vitamin D(3) but not 1alpha,25(OH)(2)D(3) levels. In agreement with these results, incubation of cells with [3H]25(OH)D(3) revealed a low conversion rate to [3H]1alpha,25(OH)(2)D(3). The operation of a light-dependent pathway formation of vitamin D(3) coupled to higher expression of 25(OH)D(3)-1alpha-hydroxylase may account for the large concentrations of 1alpha,25(OH)(2)D(3) normally found in differentiated field-grown plants.

Calcifediol↗
PubMed2001

PTH stimulates PLCbeta and PLCgamma isoenzymes in rat enterocytes: influence of ageing.

We previously reported that in rat duodenal cells (enterocytes), parathyroid hormone (PTH [1-34]: PTH) stimulates the hydrolysis of polyphosphoinositides by phospholipase C (PLC), generating the second messengers inositol trisphosphate (IP(3)) and diacylglycerol (DAG) and that this mechanism is severely altered in old animals. In the present study, we show that PTH [1-34]-dependent IP(3) release in young rats was blocked to a great extent by an antibody against guanine nucleotide binding protein Galphaq/11, indicating that the hormone activates a beta isoform of PLC coupled to the alpha subunit of Gq/11. In addition, PTH rapidly (within 30 s, with maximal effects at 1 min) stimulated tyrosine phosphorylation of PLCgamma in a dose-dependent fashion (10(-10)-10(-7) M). The hormone response was specific as PTH [7-34] was without effects. The tyrosine kinase inhibitors, genistein (100 microM) and herbimycin (2 microM), suppressed PTH-dependent PLCgamma tyrosine phosphorylation. Stimulation of PLCgamma tyrosine phosphorylation by PTH [1-34] greatly decreased with ageing. PP1 (10 microM), a specific inhibitor of the Src family of tyrosine kinases, completely abolished PLCgamma phosphorylation. The hormone-induced Src tyrosine dephosphorylation, a major mechanism of Src activation, an effect that was blunted in old animals. These results indicate that in rat enterocytes PTH generates IP(3) mainly through G-protein-coupled PLCbeta and stimulates PLCgamma phosphorylation via the nonreceptor tyrosine kinase Src. Impairment of PTH activation of both PLC isoforms upon ageing may result in abnormal hormone regulation of cell Ca(2+) and proliferation in the duodenum.

Aging↗
PubMed2001

Impairments of attention and effort among patients with major affective disorders.

Impairments of attention are common among people with major affective disorders, yet the influence of effortful task demands on attentional performance in unipolar and bipolar illness has been little studied. The authors compared psychiatric inpatients with primary diagnoses of unipolar or bipolar affective disorder (n=27) and age-matched normal control subjects (n=20) on a battery of eight neuropsychological tasks designed to measure different attentional functions. There were low-effort and high-effort versions of each task. Significant group differences were consistently observed on tasks demanding sustained and focused attention, but not on tasks requiring visual selective attention. Although affective disorder patients showed impairments on most tasks regardless of level of task effort, group differences were greatest on high-effort conditions. Results indicate that patients with major affective disorders show significant attentional impairments on most measures of effortful attention, and the magnitude of these impairments increases as the effortful demands of the task increase.

Adult↗
PubMed2001

Perceived need for and use of mental health services by women living with or at risk of human immunodeficiency virus infection.

OBJECTIVES: To determine prevalence of and factors associated with perceived need for and use of mental health services and use of psychotherapeutic medications among women in the Human Immunodeficiency Virus Epidemiology Research Study (HERS). METHODS: We interviewed 871 HIV-seropositive and 439 demographically and behaviorally similar seronegative women at baseline regarding demographics, psychosocial measures, substance use, medical history, and use of health care services and medications. RESULTS: Thirty-eight percent of HIV-seropositive women and 35% of seronegative women (p = 0.33) reported needing mental health services in the prior six months. Women who were older, were white or Latina (compared with African American), had some college education, had less social support, and reported recent negative life events or had CES-D scores higher than 15 (suggesting depression) were more likely to report needing mental health services. Sixty-seven percent of seropositive and 65% of seronegative women who reported needing services (p = 0.69) reported obtaining services. Women who were white (compared with Latina or African American) and had more education, more social support, and health insurance were more likely to obtain services. Eighteen percent of seropositive and 13% of seronegative women (p = 0.006) reported current use of psychotherapeutic medications, especially antidepressants and antianxiety medications. Women who reported use of medications were more likely to report recent negative life events; were older, white, or Latina; had more education, less social support, CES-D scores higher than 15, and health insurance. CONCLUSION: Women both living with or at risk of HIV perceived a need for and used mental health services in association with negative life events, social isolation, and depressive symptoms. Need for and use of services differed by race/ethnicity, education, and availability of social support.

Adolescent↗
PubMed2000

Involvement of tyrosine kinase activity in 1alpha,25(OH)2-vitamin D3 signal transduction in skeletal muscle cells.

In cultured chick skeletal muscle cells loaded with Fura-2, the tyrosine kinase inhibitors herbimycin A and genistein abolished both the fast inositol 1,4,5-trisphosphatedependent Ca(2+) release from internal stores and extracellular Ca(2+) influx induced by 1alpha, 25(OH)(2)-vitamin D(3) (1alpha,25(OH)(2)D(3)). Daidzein, an inactive analog of genistein, was without effects. Tyrosine phosphatase inhibition by orthovanadate increased cytosolic Ca(2+). Anti-phosphotyrosine immunoblot analysis revealed that 1alpha, 25(OH)(2)D(3) rapidly (0.5-10 min) stimulates in a concentrationdependent fashion (0.1-10 nm) tyrosine phosphorylation of several myoblast proteins, among which the major targets of the hormone could be immunochemically identified as phospholipase Cgamma (127 kDa), which mediates intracellular store Ca(2+) mobilization and external Ca(2+) influx, and the growth-related proteins mitogen-activated protein (MAP) kinase (42/44 kDa) and c-myc (65 kDa). Genistein suppressed the increase in phosphorylation and concomitant elevation of MAPK activity elicited by the sterol. Both genistein and the MAPK kinase (MEK) inhibitor PD98059 abolished stimulation of DNA synthesis by 1alpha,25(OH)(2)D(3). The sterol-induced increase in tyrosine phosphorylation of c-myc, a finding not reported before for cell growth regulators, was totally suppressed by the specific Src inhibitor PP1. These results demonstrate that tyrosine phosphorylation is a previously unrecognized mechanism involved in 1alpha,25(OH)(2)D(3) regulation of Ca(2+) homeostasis in hormone target cells. In addition, the data involve tyrosine kinase cascades in the mitogenic effects of 1alpha, 25(OH)(2)D(3) on skeletal muscle cells.

Animals↗
PubMed2000

1,25(OH)(2)-vitamin D(3) affects the subcellular distribution of protein kinase C isoenzymes in rat duodenum: influence of aging.

We have previously shown that the steroid hormone 1, 25-dihydroxy-vitamin D(3) [1,25(OH)(2)D(3)] stimulates total cell protein kinase C (PKC) activity in rat duodenum, an effect that is severely impaired in old animals. We further examined the role of 1, 25(OH)(2)D(3) on PKC as it relates to aging by measuring hormone-induced changes in subcellular localization of PKC activity and isoenzymes in duodenal mucosae from young (three-month-old) and aged (24-month-old) rats. Short treatment of duodenum with 1, 25(OH)(2)D(3) (0.1 nM, 1 min) increased membrane-associated PKC activity, whereas it decreased the activity in the cytosol of young rats but was without significant effect in aged animals. Furthermore, the ability to translocate was present in young animals after a short treatment with the phorbol ester 12-O-tetradecanoyl phorbol 13-acetate (TPA; 100 nM) or dioctanoyl-glycerol (50 microM), whereas the ability was absent in aged rats, suggesting that PKC function was impaired with aging independent of agonist stimulation. The expression of specific PKC isoenzymes and changes in their subcellular distribution after short exposure of the duodenum to the hormone were determined. Western blot analysis of total homogenates using antibodies to various PKC isoforms allowed detection of PKC alpha, beta, and delta. The expression of the straight theta and the zeta isoforms was in addition demonstrated by reverse transcription-polymerase chain reaction. The pattern of isoenzymes present in the duodenum was unaffected by aging. In young rats, 1, 25(OH)(2)D(3) translocates PKC alpha, beta, and delta to the membrane and nucleus; however, no translocation of PKC isoforms was observed in 24-month-old animals in response to the hormone. In summary, in rat duodenum, 1,25(OH)(2)D(3) modulation of PKC activity and isoenzyme subcellular distribution are impaired with aging and may explain age-induced alterations in the intestinal processes under the control of the hormone.

Aging↗
PubMed2000

Nicotiana glauca: another plant species containing vitamin D(3) metabolites.

Vitamin D(3)-related compounds have been detected in various plant species, mostly belonging to the Solanaceae. In this work we show that Nicotiana glauca, a widespread member of this taxonomic family, contains 7-dehydrocholesterol, vitamin D(3) and hydroxylated derivatives bearing precursor-product metabolic relationships in vertebrates. Leaves collected in the field and callus cultures were used. By means of specific radioreceptor binding assays and mass spectrometry of purified fractions obtained from plant tissue lipid extracts by Sephadex LH-20 and Sep-Pak C18 chromatography followed by HPLC, we established the presence of 7-dehydrocholesterol, vitamin D(3), 25(OH)-vitamin D(3) and 1alpha,25(OH)(2)-vitamin D(3) (1alpha,25(OH)(2)D(3)), the latter being a hormonally relevant metabolite in animals. These results indicate that N. glauca may represent a useful species in which to characterize the biosynthetic pathway and physiological functions of vitamin D(3) compounds in plants. In addition, tissue culture of N. glauca could become a significant tool for biotechnological production of 1alpha,25(OH)(2)D(3).

Journal Article↗
PubMed2000

Effect of aging on the mechanisms of PTH-induced calcium influx in rat intestinal cells.

We have investigated the effects of aging on parathyroid hormone (PTH) modulation of intracellular calcium homeostasis and their relationship to signal transduction pathways in isolated rat duodenal cells (enterocytes). PTH (10(-8)-10(-9) M) increased enterocyte (45)Ca(2+) influx and intracellular Ca(2+) concentration ([Ca(2+)](i)) to a greater extent (twofold and 50%, respectively) in aged (24 months) than in young (3 months) animals. The [Ca(2+)](i) response of old cells to the hormone was slower, lacking the early phase of changes in cytosolic Ca(2+). Ca(2+) influx induced by PTH was prevented by the protein kinase A antagonist Rp-cAMPS in both young and aged enterocytes, whereas neomycin and compound U73122, inhibitors of PLC-catalyzed phosphoinositide hydrolysis, abolished hormone-dependent Ca(2+) influx in young but had no effect on aged cells. Higher basal adenylyl cyclase (AC) activity and cAMP content were detected in old enterocytes. PTH increased the absolute levels of cAMP in aged cells and AC activity of microsomes isolated therefrom to a greater extent (>/= twofold) than in young enterocytes/membranes. In young cells, the hormone also induced a rapid and transient release of inositoltrisphosphate (IP(3)) and diacylglycerol (neomycin-sensitive) at 45 sec, and a delayed phase of DAG at 5 min (neomycin-insensitive). The early formation of IP(3) and DAG was blunted in aged animals. These results suggest that both the PLC and adenylyl cyclase cascades are involved in PTH stimulation of Ca(2+) influx in duodenal cells. During aging, however, only the cAMP pathway is operative, mediating a potentiation of the effects of the hormone. Additional studies are required to establish the relative role of PTH-dependent messenger systems in the regulation of intestinal calcium absorption and age-related abnormalities.

Adenylyl Cyclases↗
PubMed2000

Lumbar spine traction: evaluation of effects and recommended application for treatment.

Despite the widespread use of traction, little is known of the mode of effect, and application remains largely anecdotal. The efficacy of traction is also unclear because of generally poor design of the clinical trials to date, and because subgroups of patients most likely to benefit have not been specifically studied. These observations prompted this review, the purposes of which are to evaluate the mechanisms by which traction may provide benefit and to provide rational guidelines for the clinical application of traction. Traction has been shown to separate the vertebrae and it appears that large forces are not required. Vertebral separation could provide relief from radicular symptoms by removing direct pressure or contact forces from sensitised neural tissue. Other mechanisms proposed to explain the effects of traction (e.g. reduction of disc protrusion or altered intradiscal pressure) have been shown not to occur. We conclude that traction is most likely to benefit patients with acute (less than 6 weeks' duration) radicular pain with concomitant neurological deficit. The apparent lack of a dose-response relationship suggests that low doses are probably sufficient to achieve benefit.

Animals↗
PubMed2000

Hospitalization in the Program of All-Inclusive Care for the Elderly (PACE): rates, concomitants, and predictors.

BACKGROUND: The Program of All-Inclusive Care for the Elderly (PACE) replicates the model of comprehensive, community-based geriatric care pioneered by On Lok, that enrolls frail older adults who meet states' criteria for nursing home care, and that uses interdisciplinary teams to assess the participants and to deliver care in appropriate settings. As managed care, PACE receives capitated payment from Medicare and Medicaid. Thus, PACE's fiscal incentives are thought to be aligned with the goals of optimizing health, function, and quality of life through the delivery of effective primary, preventive, restorative, supportive, and palliative care and through the avoidance of inappropriate and expensive hospital and nursing home utilization. OBJECTIVES: To describe short-term hospital utilization, hospital discharge diagnoses, time from enrollment to first hospitalization and its clinical predictors, and hospitalization in relation to mortality among PACE participants. METHODS: Data on short-term hospitalization and participants were recovered from PACE's minimum data set. Bed use was evaluated in annual cross-sections of current participants. Primary hospital discharge diagnoses were available for discharges from September 1, 1993 through March 31, 1997. The time from enrollment to hospitalization was calculated for the participants (n = 5478) who were admitted between January 1, 1990 and March 31, 1997. The characteristics of this inception cohort were used to develop a Cox regression model of hospitalization. All PACE deaths were identified and the place of death was recovered, together with the medical records used in the hospital during PACE enrollment or 6 months before death. RESULTS: Bed-days per 1,000 PACE participants per year were comparable with the general Medicare (fee-for-service) population, at 2,046 (in 1998) versus 2014 (in 1997) despite the greater morbidity and disability for PACE participants, as reflected in their enrollment characteristics and primary hospital discharge diagnoses. The time to hospitalization was 773 days (median); 95% confidence interval, 725, 814, and was predicted by disease, treatment, social and demographic factors. Whereas 8% of PACE deaths occurred in acute hospitals, less than one-third of the decedents spent any time in the hospital in the 6-month interval before death. CONCLUSIONS: Overall, short-term hospital utilization among PACE participants is low in contrast with that for other older and disabled populations. Participant predictors of hospitalization in PACE are generally consistent with other studies in older clinical and community populations. Both utilization and risk vary considerably across PACE sites, independent of participant-level risk factors, hence suggesting that further investigation is required to study PACE's management of acute illness and hospitalization decisions. Critical to maintaining PACE's success is an understanding of the independent impact of the organization and the environment of health care on this management.

Activities of Daily Living↗
PubMed1999

17beta-oestradiol increases intracellular Ca2+ concentration in rat enterocytes. Potential role of phospholipase C-dependent store-operated Ca2+ influx.

The involvement of the phospholipase C (PLC) pathway in the non-genomic regulation of duodenal cell Ca2+ concentration by 17beta-oestradiol was investigated. The PLC inhibitors neomycin (0.5 mM) and U-73122 (2 microM) suppressed the stimulatory effect of 0.1 nM 17beta-oestradiol on the 45Ca2+ influx into enterocytes isolated from rat duodenum. The hormone (1 pM to 10 nM) increased the formation of 1,2-diacylglycerol in a biphasic pattern, characterized by an early peak at 45 s (+82%) and a later peak at 5 min (+46%). Both PLC inhibitors suppressed the first peak but were unable to block the 17beta-oestradiol effect at 5 min. 17beta-Oestradiol also increased the generation of inositol 1,4,5-trisphosphate within 15 s, with maximal stimulation at 30 s. 17beta-Oestradiol induced a rapid (30 s) and sustained (up to 5 min) increase in the intracellular Ca2+ concentration ([Ca2+]i) of fura 2-loaded enterocytes. The fast rise in [Ca2+]i was specific because other sex steroid hormones were without effect and could be blocked to a great extent by U-73122 (by 86% at 1 min). The effects of 17beta-oestradiol on enterocyte [Ca2+]i were decreased significantly (by 75%) in a Ca2+-free extracellular medium but a pronounced increase in [Ca2+]i was obtained after readmission of Ca2+ to the medium. The latter change was suppressed by 10 microM La3+, whereas nitrendipine (1 microM) and verapamil (10 microM) separately were without effect. The permeability of the 17beta-oestradiol-induced Ca2+ influx pathway to Mn2+ was increased 2.8-fold by treatment with oestrogen. These results suggest the operation of a PLC-dependent store-operated Ca2+ channel mechanism in 17beta-oestradiol regulation of enterocyte extracellular Ca2+ influx.

Animals↗
PubMed1999

Characterization of membrane estrogen binding proteins from rabbit uterus.

Estrogens exert fast non-genomic actions in their target tissues which may involve the participation of receptors located at the cell membrane. Studies were performed to identify and characterize membrane-associated 17beta-estradiol binding proteins in rabbit uterus. Specific and saturable [3H]17beta-estradiol binding sites of high affinity (Kd = 0.36 nM) were detected in uterine microsomes at higher concentration than in cytosol (370 +/- 98 vs. 270 +/- 87 fmol/mg protein, respectively). Various other steroid hormones, the stereoisomer 17alpha-estradiol and the antiestrogen tamoxifen were significantly less effective than 17beta-estradiol to compete with the radioactive ligand for binding to the membranes. The microsome binding sites were trypsin-sensitive and could be extracted to a great extent (80-90%) with 0.4/0.6 M KCl. Assays of the marker enzyme glucose-6-P dehydrogenase excluded membrane contamination with cytosolic soluble components. Immunoblot analysis of particulate and soluble fractions using monoclonal antibodies against the transactivation, heat shock protein recognition, and steroid binding domains of the nuclear estrogen receptor (ER; 67 kDa), revealed lower concentrations of the ER in membranes and the presence of five additional immunoreactive proteins of 57, 50, 32, 28, and 11 kDa which were absent in cytosol. Moreover, the antibody against the steroid binding domain was as effective as an inhibitor for cytosolic and membrane specific radioligand binding. Extraction of microsomes with the nondenaturing detergent CHAPS allowed a 2-fold enrichment of ER-like binding proteins as shown by antibody labeling and [3H]17beta-estradiol binding analysis. The results of this work are consistent with the existence of novel 17beta-estradiol membrane binding proteins structurally related to the intracellular ER. Future studies should investigate whether any of these proteins are involved in the primary events (e.g. receptor function) mediating nongenomic estrogen effects.

Animals↗