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PubMed2006

The ATP-binding cassette transporter ABCA2 as a mediator of intracellular trafficking.

ATP-binding cassette (ABC) transporters are a family of proteins that translocate molecules across cellular membranes. Substrates can include lipids, cholesterol and drugs. Mutations in ABC transporter genes can cause human pathologies and drug resistance phenotypes in cancer cells. ABCA2, the second member the A sub-family to be identified, was found at high levels in ovarian carcinoma cells resistant to the anti-cancer agent, estramustine (EM). In vitro models with elevated levels of ABCA2 are resistant to a variety of compounds, including estradiol, mitoxantrone and a free radical initiator, 2,2'-azobis-(2-amidinopropane) (AAPH). ABCA2 is most abundant in the central nervous system (CNS), ovary and macrophages. Enhanced expression of ABCA2 and related proteins, including ABCA1, ABCA4 and ABCA7, is found in human macrophages upon bolus cholesterol treatment. ABCA2 also plays a role in the trafficking of low-density lipoprotein (LDL)-derived free cholesterol and is coordinately expressed with genes involved in cholesterol homeostasis. Additionally, ABCA2 expression has been linked with gene cluster patterns consistent with pathologies including Alzheimer's disease (AD). A single-nucleotide polymorphism (SNP) in exon 14 of the ABCA2 gene was shown to be linked to early onset AD in humans, supporting the observation that ABCA2 expression influences levels of beta-amyloid peptide (Abeta), the primary component of senile plaques. ABCA2 may play a role in cholesterol transport and affect a cellular phenotype conducive to the pathogenesis of a variety of human diseases including AD, atherosclerosis and cancer.

ATP-Binding Cassette Transporters↗
PubMed1978

Use of intraoperative esophageal manometrics in surgical treatment of gastroesophageal reflux in pediatric patients.

Intraoperative lower esophageal sphincter (LES) pressures and lenghts were measured in 10 pediatric patients requiring surgery for compications of gastroesophageal reflux. LES pressure changed significantly pre- and post-Nissen fundoplication (9.8 +/- 1.51 mm Hg vs. 32.8 +/- 2.68 mm Hg, p less than 0.001). LES length also showed a significant change (1.3 +/- 0.13 cm vs. 2.8 +/- 0.26 cm, p less than 0.001). One week postoperatively LES pressures were significantly greater than preoperative values (26.4 +/- 1.74 mm Hg vs. 15.6 +/- 2.64 mm Hg, p less than 0.01). Eight of 10 patients have been evaluated 6 mo post fundoplication. None has gastroesophageal reflux by acid reflux testing or water siphon barium esophagram. None of the 10 patients has had gas bloat syndrome during the follow-up period.

Adolescent↗
PubMed1978

Incompetent lower esophageal sphincter and gastroesophageal reflux in recurrent acute pulmonary disease of infancy and childhood.

Fifteen patients with recurrent acute respiratory symptoms were evaluated for gastroesophageal reflux. All 15 had barium esophagrams. Ten of 15 had acid reflux tests performed and lower esophageal sphincter pressures measured. The data were compared to those in 23 patients with no acid reflux and 23 patients with positive acid reflux but no respiratory symptoms. Ten of ten patients with respiratory symptoms who were evaluated by the acid reflux test had positive results. The remaining five demonstrated GER by barium esophagram. LES pressure measurements in the ten patients were 11.3 +/- 1.5 mm Hg, which was significantly lower than the pressures in the acid reflux-negative group (20.3 +/- 1.3 mm Hg, P less than 0.001) but not different than in the patients with GER but no respiratory symptoms (13.9 +/- 1.5 mm Hg, P greater than 0.05). GER secondary to an incompetent lower esophageal sphincter may be one cause of recurrent acute respiratory disease in infants and children.

Acute Disease↗
PubMed1996

Concurrent validity of Spanish-language versions of the Mini-Mental State Examination, Mental Status Questionnaire, Information-Memory-Concentration test, and Orientation-Memory-Concentration test: Alzheimer's disease patients and nondemented elderly comparison subjects.

One-hundred fifty-eight elderly Spanish-speaking U.S. residents (81 patients diagnosed with Alzheimer's disease and 77 subjects without dementia) were tested with Spanish-language versions of four brief cognitive assessment instruments: the Mini-Mental State Examination (S-MMSE), the Mental Status Questionnaire (S-MSQ), the Information-Memory-Concentration test (S-IMC), and the Orientation-Memory-Concentration test (S-OMC). Within-group performances were highly correlated for all four instruments. All tests distinguished between the demented and nondemented groups, but best discrimination was achieved with the S-IMC, which correctly classified 98% of subjects. This version was also the best predictor of functional disability, as measured by impairments in instrumental activities of daily living. Within the normal comparison group, neither gender nor a subject's monolingual/bilingual status affected test performance. These four Spanish-language cognitive screening tasks may aid in the evaluation of dementia among Spanish-speaking patients.

Adult↗
PubMed2000

Age-specific effects of novel mutations in Drosophila melanogaster II. Fecundity and male mating ability.

Evolutionary theories of senescence assume that mutations with age-specific effects exist, yet until now, there has been little experimental evidence to support this assumption. In this study, we allowed mutations to accumulate in an outbred, wild population of Drosophila melanogaster to test for age-specific differences in both male mating ability and fecundity. We assayed for age-specific effects of mutations after 10, 20, and 30 generations of mutation accumulation. For mating ability, we found the strongest effects of mutations in the first half of the life span after 20 generations, and at nearly all ages by generation 30. These results are qualitatively consistent with results from a companion study in which age-specific mortality was assayed on the same lines of D. melanogaster. By contrast, effects of fecundity were confined to late ages after 20 generations of mutation accumulation, but by generation 30, as with male mating ability, effects of novel mutations were distributed across all age classes. We discuss several possible explanations for the differences that we observe between generations within traits, and among traits, and the relevance for these patterns to models of aging as well as models of mate choice and sexual selection.

Aging↗
PubMed2005

Restoration of spatial working memory by genetic rescue of GluR-A-deficient mice.

Gene-targeted mice lacking the AMPA receptor subunit GluR-A (also called GluR1 encoded by the gene Gria1,) have deficits in hippocampal CA3-CA1 long-term potentiation (LTP) and have profoundly impaired hippocampus-dependent spatial working memory (SWM) tasks, although their spatial reference memory remains normal. Here we show that forebrain-localized expression of GFP-tagged GluR-A subunits in GluR-A-deficient mice rescues SWM, paralleling its rescue of CA3-CA1 LTP. This provides powerful new evidence linking hippocampal GluR-A-dependent synaptic plasticity to rapid, flexible memory processing.

Analysis of Variance↗
PubMed2001

Dominance of the lurcher mutation in heteromeric kainate and AMPA receptor channels.

Homomeric glutamate receptor (GluR) channels become spontaneously active when the last alanine residue within the invariant SYTANLAAF-motif in the third membrane segment is substituted by threonine. The same mutation in the orphan GluRdelta2 channel is responsible for neurodegeneration in "Lurcher" (Lc) mice. Since most native GluRs are composed of different subunits, we investigated the effect of an Lc-mutated subunit in heteromeric kainate and AMPA receptors expressed in HEK293 cells. Kainate receptor KA2 subunits, either wild type or carrying the Lc mutation (KA2(Lc)), are retained inside the cell but are surface-expressed when assembled with GluR6 subunits. Importantly, KA2(Lc) dominates the gating of KA2(Lc)/GluR6(WT) channels, as revealed by spontaneous activation and by slowed desensitization and deactivation kinetics of ligand-activated whole-cell currents. Moreover, the AMPA receptor subunit GluR-B(Lc)(Q) which forms spontaneously active homomeric channels with rectifying current-voltage relationships, dominates the gating of heteromeric GluR-B(Lc)(Q)/GluR-A(R) channels. The spontaneous currents of these heteromeric AMPAR channels show linear current-voltage relationships, and the ligand-activated whole-cell currents display slower deactivation and desensitization kinetics than the respective wild-type channels. For heteromeric Lc-mutated kainate and AMPA receptors, the effects on kinetics were reduced relative to the homomeric Lc-mutated forms. Thus, an Lc-mutated subunit can potentially influence heteromeric channel function in vivo, and the severity of the phenotype will critically depend on the levels of homomeric GluR(Lc) and heteromeric GluR(Lc)/GluR(WT) channels.

Amino Acid Substitution↗
PubMed2003

[MR-guided biopsies of undetermined liver lesions: technique and results].

PURPOSE: To evaluate safety and precision of liver tumor biopsies performed in an open low field system using different sequence techniques. MATERIALS AND METHODS: In 47 patients with liver tumors, MR-guided biopsies were performed in a low field system (0.2 Tesla, Magnetom Open, Siemens) using two different sequences. The procedure was monitored with T1-weighted FLASH sequences (TR/TE = 100/9; 70(3)) in all patients and with FISP-Rotated-Keyhole-sequence (TR/TE = 18/8; 90(3)) in additional 20 patients. After positioning of the needle tip in the tumors, 166 biopsy specimens were acquired with 16 G cutting needles (Somatex*). The diameter of the biopsied lesions ranged from 1 to 10 cm (mean diameter 3.2 cm). Visibility of the needles and precision of the biopsies were evaluated. RESULTS: All interventional biopsies were performed without vascular or organ injuries. Adequate specimens for histologic interpretation were obtained in 42 cases (89.3%). The biopsy results were non-specific in 2 patients (4.2%) and the lesions missed in 3 patients (6.3%). Mean in-room time was 35 minutes and the intervention time was 8.3 minutes. T1-weighted FLASH images proved optimal for confirming needle-tip placement during the biopsies or punctures. Organs, tumors and vessels were easily identified. The FISP sequence proved to be inferior in visualizing vessels and tumors. CONCLUSION: MR-guided liver biopsies are safely and precisely performed using T1-weighted FLASH-sequences with sufficient visualization of the lesions and might be complementary to US- or CT-guided biopsies.

Adult↗
PubMed1997

Comparison of remifentanil and fentanyl in patients undergoing craniotomy for supratentorial space-occupying lesions.

BACKGROUND: Remifentanil hydrochloride is an ultra-short-acting, esterase-metabolized mu-opioid receptor agonist. This study compared the use of remifentanil or fentanyl during elective supratentorial craniotomy for space-occupying lesions. METHODS: Sixty-three adults gave written informed consent for this prospective, randomized, double-blind, multiple-center trial. Anesthesia was induced with thiopental, pancuronium, nitrous oxide/oxygen, and fentanyl (n = 32; 2 micrograms.kg.-1. min-1) or remifentanil (n = 31; 1 mu.kg-1.min-1). After tracheal intubation, infusion rates were reduced to 0.03 microgram.kg-1.min-1 (fentanyl) or 0.2 microgram.kg-1.min-1 (remifentanil) and then adjusted to maintain anesthesia and stable hemodynamics. Isoflurane was given only after specified infusion rate increases had occurred. At the time of the first burr hole, intracranial pressure was measured in a subset of patients. At bone flap replacement either saline (fentanyl group) or remifentanil (approximately 0.2 microgram.kg-1.min-1) were infused until dressing completion. Hemodynamics and time to recovery were monitored for 60 min. Analgesic requirements and nausea and vomiting were observed for 24 h. Neurological examinations were performed before operation and on postoperative days 1 and 7. RESULTS: Induction hemodynamics were similar. Systolic blood pressure was greater in the patients receiving fentanyl after tracheal intubation (fentanyl = 127 +/- 18 mmHg; remifentanil = 113 +/- 18 mmHg; P = 0.004). Intracranial pressure (fentanyl = 14 +/- 13 mmHg; remifentanil = 13 +/- 10 mmHg) and cerebral perfusion pressure (fentanyl = 76 +/- 19 mmHg; remifentanil = 78 +/- 14 mmHg) were similar. Isoflurane use was greater in the patients who received fentanyl. Median time to tracheal extubation was similar (fentanyl = 4 min: range = -1 to 40 min; remifentanil = 5 min: range = 1 to 15 min). Seven patients receiving fentanyl and none receiving remifentanil required naloxone. Postoperative systolic blood pressure was greater (fentanyl = 134 +/- 16 mmHg; remifentanil = 147 +/- 15 mmHg; P = 0.001) and analgesics were required earlier in patients receiving remifentanil. Incidences of nausea and vomiting were similar. CONCLUSIONS: Remifentanil appears to be a reasonable alternative to fentanyl during elective supratentorial craniotomy.

Adult↗
PubMed1997

Modification of glutamine synthetase expression by mammalian Müller (glial) cells in retinal organ cultures.

One of the key enzymes in glial-neuronal transmitter recycling is glutamine synthetase (GS). In the retina, GS is exclusively expressed by glial (Müller) cells where it serves to convert neuron-released active transmitter substances (glutamate and GABA) into glutamine. Experiments on avian retinae have shown that GS expression is developmentally regulated by glucocorticoid hormones and, to a lesser extent, by a non-hormonal control mechanism(s). Much less is known about GS regulation in mammalian retinae, although either increases or decreases of GS immunoreactivity have been observed in Müller cells in different forms of retinal pathologies. We studied GS expression in postnatal rabbit retinae both in vivo and explanted as wholemounts in vitro, using immunocytochemistry and Western immunoblotting. GS expression was detectable in vivo from the fourth postnatal day, and increased rapidly within the first weeks of life. Levels were lower in vitro than in vivo by an order of magnitude, and could be significantly stimulated (> 60-110%) in vitro by application of hydrocortisone, conditioned medium from cultured retinal pigment epithelium and glutamate or ammonia, but not GABA. It is concluded that GS expression in mammalian Müller cells is dependent on systemic control by glucocorticoid hormones, as observed in birds, but environmental (activity-dependent) factors may play a more important role in mammals.

Animals↗
PubMed2006

Bone graft substitutes in periodontal and peri-implant bone regeneration.

Regenerative medicine provides different therapy alternatives alongside gold standard autogenous grafts for the treatment of periodontal or peri-implant osseous defects. Continuing progress in the field of alloplastic bone substitutes has yielded promising solutions to the appropriate indications with the membrane technique either alone or in combination with enamel matrix derivatives. Their clinical outcomes, however, still require critical discussion.

Alveolar Bone Loss↗
PubMedDate not supplied

Glutaraldehyde-fixed bovine pericardium for right ventricular outflow enlargement.

Right ventricular outflow tract enlargement using glutaraldehyde-fixed bovine pericardium was evaluated experimentally using the pig model. Twelve piglets (8-16 kg) underwent closure of surgically created, longitudinal right ventriculotomies using premeasured, round, bovine pericardial patches. Half of the animals had pulmonary artery banding to increase right sided pressures. The animals were studied an average of 5.1 months following surgery. Cardiac catheterization was performed on eight animals. Pressure measurements revealed no gradient across any outflow patch, and angiography showed no stenosis or dilatation. There was marked right ventricular hypertension in the banded animals. The hearts from all twelve animals were examined grossly and microscopically. There was endothelialization of all patches with no aneurysm formation. Measurements revealed that most patches had become oval shaped. There was no difference in patch size changes between banded and non-banded animals. The patches showed no significant size change in the longitudinal plane (average from 20.8 mm to 20.3 mm, 6.3% change); however, there was a significant decrease in the transverse size (20.8 mm to 17.3 mm, 16.0%) (p less than 0.001). The change in patch size was probably due to reshaping to conform to the longitudinal ventriculotomy and caused no narrowing. In this study, glutaraldehyde-fixed bovine pericardium appeared to be satisfactory for right ventricular outflow enlargement. Favorable qualities include ease of handling, hemostasis, and no aneurysm formation.

Animals↗
PubMed1979

Computer-assisted liver-mass estimation from gamma-camera images.

We have devised a computer-assisted method for objective estimation of liver mass from the right lateral projection of radiocolloid images of the liver. Gamma-camera images were digitized, preprocessed, and stored in computer memory. The definition of liver for area measurement was adaptively determined by means of a Laplacian operator that measures change in radioactivity slope associated with the liver margin. Individual thresholds were calculated for each of 16 subregions. A liver-mass index was derived from a linear regression model correlating the area of the right lateral projection with liver weight at autopsy in 50 patients whose livers weighed between 0.8 to 3.0 Kg. The correlation coefficient found for this method was 0.83 using the equation: Liver Mass [kg] = Area [cm2]/275 [kg/cm2]--0.215 [kg]. Liver-mass estimates using an alternative computer-assisted method or representative manual methods adapted for gamma-camera images showed lower correlation with liver weight at autopsy.

Adult↗
PubMed1993

Effect of exercise training on cardiopulmonary baroreflex control of forearm vascular resistance in humans.

We studied the stimulus-response characteristics of cardiopulmonary baroreflex control of forearm vascular resistance (FVR) in four groups of male volunteer subjects: i) unfit, ii) physically fit, iii) before and after 10 wk of endurance training (chronic blood volume expansion), and iv) before and after acute blood volume expansion. We assessed the relationship between reflex stimulus, i.e., changes in central venous pressure and response, i.e., FVR, during unloading of cardiopulmonary mechanoreceptors with lower body negative pressure (LBNP, 0 to -20 mm Hg). The slope of the linear relationship between FVR and CVP, the index of the responsiveness of this baroreflex, was significantly diminished (> 50%) in the fit subjects compared with the unfit. The slope of the FVR-CVP relationship was inversely correlated with the subject's total blood volume, suggesting that blood volume expansion was related to the attenuated CP baroreflex. In the exercise training study, maximal oxygen consumption and blood volume increased following 10 wk of endurance training (N = 14) but were unchanged in the time control group (N = 7). The slope of the FVR-CVP relationship was significantly reduced (32%) following 10 wk of training but was unchanged in the time control group. The reduction in slope of the FVR-CVP relationship was inversely related to the increase in blood volume associated with exercise training. Acute blood volume expansion 8 ml.kg-1 body weight with 5% human serum albumin solution) significantly reduced the slope of the FVR-CVP relationship. These data support the hypothesis that the attenuated forearm vascular reflex in physically fit individuals is related to a training-induced hypervolemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Physiological↗
PubMed2001

Macrophage effector mechanisms in melanoma in an experimental study.

BACKGROUND: The tumor-bearing state is known to induce immune dysfunction that contributes to increased infectious complications and tumor progression. However, the mechanisms underlying this immunosuppression remain unclear. HYPOTHESIS: Macrophage (MO) dysfunction may play a role in tumor-induced immunosuppression. DESIGN AND MAIN OUTCOME MEASURES: Using a murine model, this study investigated the effects of melanoma growth on peritoneal macrophage effector molecule and prostaglandin production, MO-mediated cytotoxicity, and candidacidal mechanisms. Female C57BL/6 mice were inoculated with 106 B16 melanoma cells or a salt solution subcutaneously. Mice were euthanized 3 weeks later and peritoneal MOs were harvested and assayed for nitric oxide, superoxide anion, tumor necrosis factor alpha, and prostaglandin E(2)production. Macrophage-mediated cytotoxicity against B16 melanoma targets and MO candidacidal mechanisms were also measured. RESULTS: Macrophage production of nitric oxide, superoxide anion, and tumor necrosis factor alpha were significantly decreased, while prostaglandin E(2)production was increased in MOs from melanoma-bearing mice. Concomitantly, MO-mediated cytotoxicity and candidacidal mechanisms were significantly impaired. CONCLUSIONS: Melanoma growth leads to decreased MO effector molecule production, increased prostaglandin E(2)production, and impaired MO cytotoxic and candidacidal mechanisms. These results may help explain the observed increased infectious complications in the tumor-bearing host. Strategies aimed at restoring MO function may have therapeutic potential.

Animals↗
PubMed1996

Dominance of T-helper 2-type cytokines after severe injury.

OBJECTIVE: To determine whether severe injury leads to a dominance of splenocyte-produced T-helper (Th) 2-type cytokines, partly explaining the observed defects in cellular immune responses in the posttraumatic state. DESIGN: Female BALB/c mice (n = 6 per group) were randomized to receive anesthesia alone (control) or a combined femur fracture and a hemorrhage of 40% of total blood volume (trauma). On days 1 and 7 after injury, mice were killed and spleens were harvested. Splenocytes were stimulated in vitro with 2.5 micrograms of concanavalin A per milliliter. After 72 hours of incubation, splenocyte proliferation was determined by means of tritiated thymidine uptake. Production of interferon-gamma and interleukins (IL) -2, -4, -5, -6, and -10 from supernatants harvested after 24 or 72 hours of incubation was quantified by enzyme-linked immunosorbent assay. SETTING: Surgical immunology research laboratory of a medical college. MAIN OUTCOME MEASURES: Mouse spleen weight, splenocyte number, and proliferation in addition to cytokine production (interferon-gamma, IL-2, IL-4, IL-5, IL-6, and IL-10). RESULTS: Splenocyte proliferative capacity was unaffected at day 1 after injury but was significantly suppressed (P < .05) by day 7 after injury. Similarly, there were no changes in splenocyte cytokine production in a comparison of control and injured mice at day 1. At day 7, however, there was nearly a 90% decrease in the Th1-type cytokines (interferon-gamma and IL-2; P < or = .002) and at least a 30% increase in the Th2-type cytokines IL-4, IL-5, IL-6, and IL-10 (P = .06 for IL-6 and P < or = .03 for IL-4, IL-5, and IL-10). CONCLUSIONS: These data indicate that a shift to a Th2-type splenocyte cytokine response occurs late, at 7 days after injury. Modulation of Th cell cytokine responses may partially explain defects observed in cellular immune responses in postinjury states. Therapies that augment Th1-type cytokine production and/or neutralize Th2-type cytokines may prove beneficial.

Animals↗