Cell wall polymers in the Phaeoceros placenta reflect developmental and functional differences across generations

The placenta of hornworts is unique among bryophytes in the restriction of transfer cells that are characterized by elaborate wall labyrinths to the gametophyte generation. During development, cells around the periphery of the sporophyte foot elongate, forming smooth-walled haustorial cells that interdigitate with gametophyte cells. Using immunogold labeling with 22 antibodies to diverse cell wall polymers, we examined compositional differences in the developmentally and morphologically distinct cell walls of gametophyte transfer cells and sporophyte haustorial cells in the placenta of Phaeoceros. As detected by Calcofluor White fluorescence, cellulose forms the cell wall scaffolding in cells on both sides of the placenta. Homogalacturonan (HG) and rhamnogalacturonan I (RG-I) pectins are abundant in both cell types, and haustrorial cells are further enriched in methyl-esterified HGs. The abundance of pectins in placental cell walls is consistent with the postulated roles of these polymers in cell wall porosity and in maintaining an acidic apoplastic pH favorable to solute transport. Xyloglucan hemicellulose, but not mannans or glucuronoxylans, are present in cell walls at the interface between the two generations with a lower density in gametophytic wall ingrowths. Arabinogalactan proteins (AGPs) are diverse along the plasmalemma of placental cells and are absent in surrounding cells in both generations. AGPs in placental cell walls may play a role in calcium binding and release associated with signal transduction as has been speculated for these glycoproteins in other plants. Callose is restricted to thin areas in cell walls of gametophyte transfer cells. In contrast to studies of transfer cells in other systems, no reaction to the JIM12 antibody against extensin was observed in Phaeoceros.

Differential localization of cell wall polymers across generations in the placenta of Marchantia polymorpha

To further knowledge on cell wall composition in early land plants, we localized cell wall constituents in placental cells of the liverwort Marchantia polymorpha L. using monoclonal antibodies (MAbs) in the transmission electron microscope and histochemical staining. The placenta of M. polymorpha is similar to the majority of bryophytes in that both generations contain transfer cells with extensive wall ingrowths. Although the four major cell wall polymers, i.e., cellulose, pectins, hemicelluloses, and arabinogalactan proteins, are present, there are variations in the richness and specificity across generations. An abundance of homogalacturonan pectins in all placental cell walls is consistent with maintaining cell wall permeability and an acidic apoplastic pH necessary for solute transport. Although similar in ultrastructure, transfer cell walls on the sporophyte side in M. polymorpha are enriched with xyloglucans and diverse AGPs not detected on the gametophyte side of the placenta. Gametophyte wall ingrowths are more uniform in polymer composition. Lastly, extensins and callose are not components of transfer cell walls of M. polymorpha, which deviates from studies on transfer cells in other plants. The difference in polymer localizations in transfer cell walls between generations is consistent with directional movement from gametophyte to sporophyte in this liverwort.

Immunogold Localization of Molecular Constituents Associated with Basal Bodies, Flagella, and Extracellular Matrices in Male Gametes of Land Plants

Male gametes (spermatozoids) are the only motile cells produced during the life cycle of land plants. While absent from flowering and most cone-bearing plants, motile cells are found in less derived taxa, including bryophytes (mosses, liverworts and hornworts), pteridophytes (lycophytes and ferns) and some seed plants (Ginkgo and cycads). During development, these cells undergo profound changes that involve the production of a locomotory apparatus, unique microtubule (MT) arrays, and a series of special cell walls that are produced in sequence and are synchronized with cellular differentiation. Immunogold labeling in the transmission electron microscope (TEM) provides information on the exact location and potential function of macromolecules involved with this developmental process. Specifically, it is possible to localize epitopes to proteins that are associated with the cellular inclusions involved in MT production and function. Spermatogenesis in these plants is also ideal for examining the differential expression of carbohydrates and glycoproteins that comprise the extracellular matrixes associated with the dramatic architectural changes in gamete shape and locomotory apparatus development. Here we provide methodologies using monoclonal antibodies (MAbs) and immunogold labeling in the TEM to localize macromolecules that are integral to spermatozoid development.

Transmission Electron Microscopy of Centrioles, Basal Bodies and Flagella in Motile Male Gametes of Land Plants

Motile male gametes (spermatozoids) of land plants are coiled and contain a modified and precisely organized complement of organelles that includes a locomotory apparatus with two to thousands of flagella. Each flagellum is generated from a basal body that originates de novo as a centriole in spermatogenous cell lineages. Much of what is known about the diversity of plant male gametes was derived from detailed transmission electron microscopic studies. Because the process of spermatogenesis results in complete transformation of the shape and organization of these cells, TEM studies have yielded a wealth of information on cellular differentiation. Because green algal progenitor groups contain centrioles and a variety of motile cells, land plant spermatozoids also provide a plethora of opportunities to examine the evolution and eventual loss of centrioles and locomotory apparatus during land colonization. Here we provide a brief overview of the studies and methodologies we have conducted over the past 20 years that have elucidated not only the structural diversity of these cells but also the development of microtubule organizing centers, the de novo origin of centrioles and the ontogeny of structurally complex motile cells.

Predictive factors for surgical site infection in head and neck cancer surgery: A case-control study

Surgical Site Infection (SSI) after head and neck cancer surgery may be life threatening and induces increasing in healthcare cost. The objective of this present study was to identify predictive factors associated to surgical site infection in head and neck cancer surgery. Numerous predictive factors were analyzed with univariate case-control method, then with multivariate method. This retrospective study included 71 patients who have been hospitalized in our department during 2010 for a head and neck cancer surgery. The incidence of surgical site infection was 15.5%. The T3-T4 stages were identified as an independent predictive factor (p = 0.04). Our study does not find other predictive factor for a SSI. The NNIS index (National Nosocomial Infections Surveillance), used by the Center for disease control and prevention as predictive factor, was not valid in our study. A specific predictive index should include the tumor stage for Head and Neck Cancer surgery and should be taken into account for the management of a preventive antibiotic treatment.

Captopril does not improve insulin action in essential hypertension: a double-blind placebo-controlled study

OBJECTIVE

To compare the effect of captopril with that of placebo on peripheral and hepatic insulin action in essential hypertension, in light of evidence that insulin resistance is associated with cardiovascular risk.

DESIGN

Randomized, double-blind, placebo-controlled, crossover trial, with 8 week treatment periods of captopril and placebo preceded and separated by 6 weeks of placebo.

SETTING

Belfast teaching hospital.

PATIENTS

Eighteen Caucasian nondiabetic patients (10 males), aged under 65 years, with essential hypertension, recruited from general practices in the greater Belfast area.

INTERVENTIONS

Captopril at 50 mg twice a day or placebo twice a day for two 8 week treatment periods.

MAIN OUTCOME MEASURES

Peripheral and hepatic insulin sensitivity assessed by glucose clamps.

RESULTS

Fourteen patients completed the study. Mean (+/- SEM) levels of fasting glucose, fasting insulin and postabsorptive hepatic glucose production were similar after captopril and placebo (5.4+/-0.1 versus 5.4+/-0.1 mmol/l, 10.6+/-2.2 versus 9.5+/-1.1 mU/l, 11.2+/-0.6 versus 11.0+/-0.5 mmol/kg per min, respectively). During hyperinsulinaemia, hepatic glucose production was suppressed to comparable levels after both treatments (4.8+/-0.6 versus 4.3+/-0.6 mmol/kg per min) and exogenous glucose infusion rates required to maintain euglycaemia were also similar (30.0+/-2.6 versus 30.3+/-2.6 mmol/kg per min).

CONCLUSION

Captopril therapy in uncomplicated essential hypertension has no effect on peripheral or hepatic insulin sensitivity.

Ethical considerations in drug administration for critically ill patients

The ethical dilemmas critical care nurses face in daily practice are increasing as treatments are weighed against the benefit in individual patients. Managing critically ill patients holistically creates ethical challenges on a daily basis. Determining how to assist patients and significant others in making sound ethical decisions is critical to optimal outcomes. Case studies are presented to illustrate further how cost effectiveness will continue to have a major role in determining patient care in the 21st century.

Purification and characterization of insulin and the C-peptide of proinsulin from Przewalski's horse, zebra, rhino, and tapir (Perissodactyla)

Within the order Perissodactyla, the primary structure of insulin has been strongly conserved. Insulin from Przewalski's horse and the mountain zebra (suborder Hippomorpha) is the same as that from the domestic horse and differs from insulin from the white rhinoceros and mountain tapir (suborder Ceratomorpha) by a single substitution (Gly-->Ser) at position 9 in the A-chain. A second molecular form of Przewalski's horse insulin isolated in this study was shown to represent the gamma-ethyl ester of the Glu17 residue of the A-chain. This component was probably formed during the extraction of the pancreas with acidified ethanol. The amino acid sequence of the C-peptide of proinsulin has been less well conserved. Zebra C-peptide comprises 31 amino acid residues and differs from Przewalski's horse and domestic horse C-peptide by one substitution (Gln30-->Pro). Rhino C-peptide was isolated only in a truncated form corresponding to residues (1-23) of intact C-peptide. Its amino acid sequence contains three substitutions compared with the corresponding region of horse C-peptide. It is postulated that the substitution (Pro23-->Thr) renders rhino C-peptide more liable to proteolytic cleavage by a chymotrypsin-like enzyme than horse C-peptide. C-peptide could not be identified in the extract of tapir pancreas, suggesting that proteolytic degradation may have been more extensive than in the rhino. In contrast to the ox and pig (order Artiodactyla), there was no evidence for the expression of more than one proinsulin gene in the species of Perissodactyla examined.

Primary structure of pancreatic polypeptide from four species of Perissodactyla (Przewalski's horse, zebra, rhino, tapir)

Pancreatic polypeptide (PP) has been purified from extracts of the pancreas of four species of odd-toed ungulates (Perissodactyla): Przewalski's horse, mountain zebra, white rhinoceros, and mountain tapir. The amino acid sequence of Przewalski's horse pancreatic polypeptide was established as Ala-Pro-Met-Glu-Pro-Val-Tyr-Pro-Gly-Asp10-Asn- Ala-Thr-Pro-Glu-Gln-Met-Ala-Gln-Tyr20-Ala-Ala-Glu-Leu-Arg-Arg-Tyr- Ile-Asn-Met30 - Leu-Thr-Arg-Pro-Arg-Tyr.NH2. Zebra PP was identical to Przewalski's horse PP, rhinoceros PP contained three substitutions relative to the horse (Ser for Ala1, Leu for Met3, and Glu for Gln16), and tapir PP contained one substitution relative to the horse (Leu for Met3). On the basis of morphological characteristics and the fossil record, the rhinocerotids are classified with the tapirids in the suborder Ceratomorpha, whereas the horse and zebra belong to a separate suborder, Hippomorpha. On the basis of structural similarity of the PP molecules, however, it would appear that the tapir is more closely related to the horse than to the rhinoceros. These observations provide a further example of the need for extreme caution when inferring taxonomic or phylogenetic relationships between species from the structures of homologous peptides.

Avoidance of Untoward Effects of OEstrogenic Therapy in the Menopause

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Some Aspects of Sterility

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An Unusual Uterine Polyp

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