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R Moore

Publications and source records attributed to R Moore.

At least 289 records · Page 16Linked to original sources
PubMed1989

Movement of endogenous calcium in the elongating zone of graviresponding roots of Zea mays.

Endogenous calcium (Ca) accumulates along the lower side of the elongating zone of horizontally oriented roots of Zea mays cv. Yellow Dent. This accumulation of Ca correlates positively with the onset of gravicurvature, and occurs in the cytoplasm, cell walls and mucilage of epidermal cells. Corresponding changes in endogenous Ca do not occur in cortical cells of the elongating zone of intact roots. These results indicate that the calcium asymmetries associated with root gravicurvature occur in the outermost layers of the root.

Calcium↗
PubMed1989

Root graviresponsiveness and cellular differentiation in wild-type and a starchless mutant of Arabidopsis thaliana.

Primary roots of a starchless mutant of Arabidopsis thaliana L. are strongly graviresponsive despite lacking amyloplasts in their columella cells. The ultrastructures of calyptrogen and peripheral cells in wild-type as compared to mutant seedlings are not significantly different. The largest difference in cellular differentiation in caps of mutant and wild-type roots is the relative volume of plastids in columella cells. Plastids occupy 12.3% of the volume of columella cells in wild-type seedlings, but only 3.69% of columella cells in mutant seedlings. These results indicate that: (1) amyloplasts and starch are not necessary for root graviresponsiveness; (2) the increase in relative volume of plastids that usually accompanies differentiation of columella cells is not necessary for root graviresponsiveness; and (3) the absence of starch and amyloplasts does not affect the structure of calyptrogen (i.e. meristematic) and secretory (i.e. peripheral) cells in root caps. These results are discussed relative to proposed models for root gravitropism.

Arabidopsis↗
PubMed1989

Characterizing pathways by which gravitropic effectors could move from the root cap to the root of primary roots of Zea mays.

Plasmodesmata linking the root cap and root in primary roots Zea mays are restricted to approx. 400 protodermal cells bordering approx. 110000 microns2 of the calyptrogen of the root cap. This area is less than 10% of the cross-sectional area of the root-tip at the cap junction. Therefore, gravitropic effectors moving from the root cap to the root can move symplastically only through a relatively small area in the centre of the root. Decapped roots are non-responsive to gravity. However, decapped roots whose caps are replaced immediately after decapping are strongly graviresponsive. Thus, gravicurvature occurs only when the root cap contacts the root, and symplastic continuity between the cap and root is not required for gravicurvature. Completely removing mucilage from the root tip renders the root non-responsive to gravity. Taken together, these data suggest that gravitropic effectors move apoplastically through mucilage from the cap to the root.

Cell Communication↗
PubMed1989

Measured energy expenditure in severe head trauma.

Metabolic profiles of 20 patients admitted to the Conemaugh Valley Memorial Hospital Trauma Unit from July 1987 through June 1988 with Glasgow Coma Scale Scores of 7 or less were retrospectively reviewed. Analysis of Injury Severity Scale (ISS) determinations indicated that all patients had major closed head injury, and associated injuries were minor in nature. No significant co-morbid disease states were present in this patient population. All patients required mechanical ventilatory support, and within 48 hours of admission measurements of oxygen consumption (VO2), carbon dioxide production (VCO2) and respiratory quotient (VCO2/VO2) were made using a Beckman Metabolic Measurement Cart which employs indirect closed calorimetry to assess resting energy expenditure (REE). When predicted values of REE and VO2 (derived from the Harris-Benedict equation) were compared to actual measured data, the percentage increase over predicted was 160 +/- 37 (p less than 0.005) and 166 +/- 43 (p less than 0.005), respectively. Based on these observations it is evident that patients with severe head trauma are physiologically in an early hypermetabolic state, and that values of REE derived from standard formula are grossly inaccurate, leading to inadequate nutritional support.

Adolescent↗
PubMed1989

Detection and characterization of the fibroblast growth factor-related oncoprotein INT-2.

Products of the fibroblast growth factor-related proto-oncogene int-2 have been detected by using a monoclonal antibody and polyclonal antisera raised against synthetic peptides predicted from the DNA sequence. COS-1 monkey cells transfected with int-2 DNA linked to the simian virus 40 early promoter contained at least four int-2-specific proteins, presumably representing modified forms of the expected 27-kilodalton primary translation product. The level of expression was increased approximately six- to eightfold by mutation of sequences around the presumed initiation codon, negating their capacity to encode a short oligopeptide in the +1 reading frame. Both tunicamycin inhibition and in vitro translation experiments indicated that some of the modifications correspond to asparagine-linked glycosylation, for which the sequence predicts a single site. In line with the similarities between INT-2 and other fibroblast growth factors, the in vitro translation products functioned as weak mitogens for mammary epithelial cells.

Amino Acid Sequence↗
PubMed1989

Villus contraction aids repair of intestinal epithelium after injury.

A highly reproducible in vitro model of intestinal epithelial injury in guinea pig ileum was used to study the structural and functional events that accompany rapid epithelial repair. This model is characterized by denudation of the villus tip followed by rapid restitution of the epithelial barrier. Using standard electrophysiological and quantitative morphometric techniques, we found that immediately after injury the number of cells lost exceeded the number of empty cell positions on the denuded basement membrane by 100%. Concurrently, cytoplasmic processes of subepithelial myofibroblasts contained condensations of microfilaments that were not apparent in controls. Additionally, villus height was diminished immediately after injury, and progressively decreased during the restitution period. In tissues that were depleted of ATP using the uncoupler dinitrophenol and in tissues functionally denervated by tetrodotoxin, villus shortening after injury was significantly reduced. Denervation also retarded functionally and structurally defined reestablishment of epithelial barrier function. These data suggest that intestinal epithelial repair is aided by energy-dependent, neurally mediated villus contraction. We speculate that the subepithelial network of myofibroblasts is responsible for this process, which effectively minimizes the denuded surface area to be reepithelialized.

2,4-Dinitrophenol↗
PubMed1989

Pitfalls in testing drug uptake by leukocytes using radiolabeled drugs and an explanation of conflicting results with clindamycin.

Although studies of drug uptake by leukocytes use similar methods, the results reported are sometimes vastly different. To determine the possible reasons for this, we studied neutrophil uptake of [3H]-clindamycin using the most frequently used density gradient centrifugation method and the volume probes 3H2O and [3H]-polyethylene glycol. We found that the [3H]-clindamycin available to investigators had undergone radiolytic decomposition; thus, its microbiologic activity was only 20% of its original potency. By thin-layer chromatography and autoradiography, four extra label-bearing regions were observed with [3H]-clindamycin. Results of neutrophil uptake studies have shown a drop of cellular:extracellular concentration ratios from 40:1 in 1981 to 10:1 in 1982 and 1987.

Chromatography, Thin Layer↗
PubMed1989

Prophylactic treatment of postperfusion bleeding using EACA.

To determine the effects of prophylactic treatment with EACA for blood loss after cardipulmonary bypass surgery, 350 consecutive patients undergoing open-heart surgery were studied. One hundred seventy patients received an initial dose of 5 g of EACA prior to skin incision, followed by intravenous administration of 1 g/h for the next 6 to 8 h. The control group received saline solution in the same fashion. The EACA-treated group had decreased chest tube blood loss 24 h postoperatively. In addition, EACA-treated patients had fewer myocardial infarctions, cerebrovascular accidents or reoperations for bleeding. Treated patients needed fewer units of blood transfusions than the nontreated group. There was no incidence of hyperthrombotic state or other side effects in the EACA-treated group. We concluded that prophylactic treatment with EACA for open-heart surgery requiring extracorporeal circulation may reduce the total blood loss and the number of blood transfusions in a safe and tolerable manner.

Aminocaproates↗
PubMed1989

A step in the right direction. Florida Hospital shows how to achieve ambulatory care success.

In the early 1980s St. Vincent's Medical Center, Jacksonville, FL, needed a way to correct its shrinking patient census. Its solution: Set up a network of community ambulatory care centers. The centers would give St. Vincent's, an established and well-respected institution, a presence in neighborhoods that did not normally identify with the medical center. In fall 1982 St. Vincent's opened its first Family Medical Care Center in Ponte Vedra Beach. Today, St. Vincent's manages a network of 15 ambulatory care centers located in every quadrant of the city and covering an area of more than 2,000 square miles. Four of the centers have become financially self-sufficient, three are well on their way to self-sufficiency, and all justify their cost through their referrals to the medical center. Ambulatory care centers can become the cornerstone for any hospital's growth plan. First, the environment is ripe for their development; second, they can function as a feeder mechanism for the hospital to ensure future inpatients; third, they provide diversification of risk; and fourth, they increase a hospital's purchasing power through economies of scale. Any hospital interested in ambulatory care must consider several factors: the right model, the advantages, the potential pitfalls, developmental and capital costs, and the development of a solid marketing strategy.

Community Health Centers↗
PubMed1989

Seizures in haemodialysis patients treated with recombinant human erythropoietin.

Administration of recombinant erythropoietin (r-HuEPO) is an effective treatment for the anaemia of chronic renal failure, but in some patients it has been accompanied by elevated blood pressure. This study focuses on seven patients with end-stage renal failure, managed on haemodialysis, who developed probable hypertensive encephalopathy with seizures during treatment with r-HuEPO. All made a full recovery. The events were not clearly related to the haemoglobin concentrations achieved, and four patients have subsequently been restarted on r-HuEPO therapy at a reduced dose, resulting in a slower increase in haemoglobin with no recurrence of episodes of severe hypertension. Close attention needs to be paid to blood pressure in patients commencing erythropoietin therapy, and it seems prudent to aim for a gradual increase in haemoglobin concentration to allow the circulation to adapt to changes in oxygen delivery and haematocrit.

Adult↗
PubMed1989

Recent insights into the calcium channels.

Calcium channels play a central role in the regulation of intracellular calcium (Ca2+) concentration, and their function is subject to control by voltage-regulated, receptor-regulated, or voltage- and receptor-regulated mechanisms. Three types of calcium channels have been described. These are the T (transient or "fast"), the N (neuronal), and the L (long lasting or "slow") channels. The L channels appear to be heterogeneous and have different properties in different tissues. Intracellular calcium-ion concentration can be increased by three types of receptor mechanisms. In the heart, L channels can be phosphorylated by a cyclic AMP-dependent protein kinase after beta 1-adrenergic receptor stimulation. In vascular smooth muscle, the postjunctional alpha 2-adrenergic receptor is coupled to a Ca2+ channel by a G protein; receptor stimulation facilitates calcium influx. This channel might be a form of L channel. A third receptor mechanism, especially active in vascular smooth muscle, is typified by the alpha 1-adrenergic receptor that, when stimulated, will activate phospholipase C. This leads to an increase in intracellular inositol trisphosphate (IP3), which is an intracellular messenger that can induce calcium release from the sarcoplasmic reticulum. Thus, release of norepinephrine from sympathetic nerves in the cardiovascular system stimulates the heart and vessels to contract by increasing Ca2+; however, the mechanism by which this occurs is different, depending on whether the noradrenergic agonist interacts with beta 1-, alpha 2-, or alpha 1-adrenergic receptors.

Calcium↗
PubMed1989

Rapid barrier restitution in an in vitro model of intestinal epithelial injury.

Mild forms of intestinal epithelial injury commonly occur in many disease states. In order to study how such epithelial "wounds" heal, we have developed a highly reproducible in vitro model of intestinal epithelial injury. Guinea pig ileal mucosal sheets were mounted in Ussing chambers and the mucosal surfaces were exposed to 0.06% Triton-X 100 for 5 minutes. This resulted in denudation of the epithelium at the tips of 86% of villi. As a result of this injury, resistance to passive ion flow decreased significantly (56.5 +/- 1.3 versus 38.4 +/- 2.3 ohm.cm2 for control and injury, respectively, p less than 0.01), as did transepithelial potential difference (-11.9 +/- 0.7 versus -4.3 +/- 0.4 mV for control versus injury respectively, p less than 0.01). In parallel, transepithelial fluxes of the extracellular space markers mannitol and inulin increased 3- to 5-fold immediately after injury. Two hours after injury, villus tips were again confluently covered by columnar absorptive cells, a time course of healing too fast to be accounted for by enhanced cell proliferation. Analysis of the structural events occurring during recovery showed that absorptive cells shouldering the foci of denudation rapidly changed shape after injury: they became flattened and sent cell projections over the denuded basement membrane. By 60 minutes after injury, cells from opposite shoulders of the denudation abutted, thus resealing the defect. Paralleling these structural changes, transepithelial resistance, potential difference, and mannitol and inulin fluxes returned toward control values. These data show that focal epithelial discontinuities in the small intestine may be rapidly resealed. Such reparative processes may substantially limit the deleterious physiologic impact of superficial forms of intestinal injury.

Animals↗