Talking about sexuality with your own child. The perspective of the parents of children born with arm

PURPOSE

Evaluate whether parents have ever discussed sexuality with their children with anorectal malformations (ARM), which sexuality issues they think should be addressed and who, in their opinion, should address these issues.

METHODS

Parents from the Italian Parents' and Patients' Association for Anorectal Malformation participated in meetings organized by the Association together with local Pediatric Surgical Units and were asked to fill in a questionnaire.

RESULTS

103 parents participated. Overall, 66% of parents had never talked about sex with their children. Children's age was marginally correlated with occasions to talk about sexuality (r = .202, p = 0.53) indicating that the older were the children, the more the parents talked about sexuality. The majority of parents reported that their children should have the possibility to talk about sex with them (72%), psychologists (57%), gynecologists/andrologists (47%), pediatric surgeons (33.5%), surgeons specialized in ARM (39.8%), friends (28%), nurses (24.7%) and teachers (20.4%), respectively. The most important topic they thought their children should address was handling serene sexuality, although the most common topic effectively discussed with them was the conception.

CONCLUSION

Psychologists, gynecologists/andrologists, and pediatric surgeons are seen as key resources for talking about sexuality. A great number of parents express the wish that their children had more opportunities to discuss sexual topics with pediatric surgeons.

Non-financial conflicts of interest: contribution to a surgical dilemma by the European Reference Networks for Rare Diseases

PURPOSE

Conflicts of interest can impede both research and medical treatment. The European Reference Networks require their members to deal with financial and non-financial conflicts according to an explicit protocol. In a literature review, we identified relevant interests in paediatric surgery, and drafted such a policy.

METHODS

We conducted a Pubmed query and identified additional publications based on the content of the papers.

RESULTS

58 titles were identified. According to their abstracts, 10 publications were studied in full text. A scientific taxonomy does not yet exist, but a variety of factors are mentioned. Non-financial conflicts of interest are addressed less accurately and less frequently than financial ones, especially regarding surgical treatment. Since the clinical effect of surgical volume was identified as being relevant, additional 29 respective publications were analysed. This volume-quality relationship causes conflicts of interest for the many surgeons treating a broad spectrum of rare conditions. We present a recommendation that may guide referral of patients requiring complex surgery to centres with a higher volume.

CONCLUSIONS

Non-financial conflicts of interest need to be dealt with more accuracy, especially with regard to surgery in rare, complex congenital conditions. The European Reference Networks offer a framework to mitigate these conflicts.

Self-efficacy beliefs, faecal incontinence and health-related quality of life in patients born with anorectal malformations

AIM

Anorectal malformations (ARMs) are rare congenital colorectal anomalies with long lasting consequences, among which faecal incontinence is one of the most relevant since it may strongly affect patients' health-related quality of life (HRQoL). Although a growing body of literature supports the importance of self-efficacy in chronic disease health outcomes, only few studies have focused on self-efficacy in ARMs and in faecal incontinence. The purpose of the present study is to examine the mediational role of self-efficacy in the path between faecal incontinence and HRQoL in patients born with ARMs.

METHOD

Ninety-eight adult patients from the Italian Association for Anorectal Malformations (AIMAR) responded to measures of faecal incontinence, self-efficacy for managing ARM consequences, and physical and mental HRQoL (SF-36). Data were analysed by means of structural equation models.

RESULTS

The tested model provides support for the guiding hypothesis. Fit indices indicate that the model fits the data well (χ²  = 33.48, df = 23, P = 0.07; comparative fit index [CFI] = 0.97; root mean square error of approximation [RMSEA] = 0.07; standardized root mean square residual [SRMR] = 0.05). Faecal incontinence has negative effects on both physical and mental HRQoL, as well on self-efficacy. In turn, self-efficacy has a positive and direct effect on mental HRQoL.

CONCLUSION

Faecal incontinence is the most relevant and negative factor influencing HRQoL; in addition, self-efficacy contributes in reducing emotional distress and in improving mental health outcomes. Longitudinal and controlled studies may be helpful to evaluate the effectiveness of self-efficacy interventions in improving mental HRQoL in patients with faecal incontinence.

Tethered cord in patients affected by anorectal malformations: a survey from the ARM-Net Consortium

PURPOSE

The goal of this study was to determine the degree of consensus in the management of spinal cord tethering (TC) in patients with anorectal malformation (ARM) in a large cohort of European pediatric centers.

METHODS

A survey was sent to pediatric surgeons (one per center) members of the ARM-Net Consortium.

RESULTS

Twenty-four (86%) from ten different countries completed the survey. Overall prevalence of TC was: 21% unknown, 46% below 15, and 29% between 15 and 30%. Ninety-six agreed on screening all patients for TC regardless the type of ARM and 79% start screening at birth. Responses varied in TC definition and diagnostic tools. Fifty percent of respondents prefer ultrasound (US), 21% indicate either US or magnetic resonance (MRI) based on a pre-defined risk of presenting TC, and 21% perform both. Discrepancy exists in complementary test: 82% carry out urodynamic studies (UDS) and only 37% perform somatosensory-evoked potentials (SSEP). Prophylactic untethering is performed in only two centers (8%).

CONCLUSIONS

Survey results support TC screening in all patients with ARM and conservative management of TC. There is discrepancy in the definition of TC, screening tools, and complementary test. Protocols should be developed to avoid such variability in management.

Transition from childhood to adolescence: Quality of life changes 6 years later in patients born with anorectal malformations

BACKGROUND/PURPOSE

Disease-specific quality of life (QoL) may be more or less relevant when children enter preadolescence/adolescence. Few attentions have been given to development and transition periods. Aim of the present longitudinal study is to evaluate ARM specific changes in QoL and the stability of QoL over 6 years.

METHODS

Questionnaires were sent to families of the AIMAR Association (in 2007 and in 2013/2014). They included the Hirschsprung's Disease/ARM QoL Questionnaire (HAQL, [1]). Rank correlations and within group comparisons for the HAQL subscales were conducted analyzing the scores of time 1 vs time 2. Gender effects were tested.

RESULTS

134 parents answered the questionnaires at time 1 and 73 at time 2. Results of the repeated Analyses of Variance indicated improvements in the continence subscales ("Presence of Diarrhea," "Fecal Continence"). QoL significantly worsened in "Social and Emotional Functioning" and in "Body Image" areas. The analysis of stability of change indicates that QoL scores remain stable, with the exception of the Body Image area.

CONCLUSIONS

Despite improvements in the continence areas, parents reported worse levels of QoL in the psychosocial areas, as their child grow. As patients grow, they might have more difficulties in daily and social activities, and feel more frequently ashamed and more dissatisfied with their body.

Does mothers' perception of social support mediate the relationship between fecal incontinence and quality of life of the child?

PURPOSE

Fecal incontinence is a common problem in children and adolescents with anorectal malformation (ARM) and may negatively impact psycho-social well-being. Mothers' perception of social support has been proved to contribute to children's quality of life (QOL). Considering ARM studies, the role of family and social resources have received little attention. The aim of the present study was to analyze whether mothers' perception of social support mediates the impact of child fecal incontinence on his/her QOL.

METHODS

One hundred and nine mothers with a child born with ARM (aged 6-15 years old; mean age = 11 years) completed questionnaires including the fecal incontinence subscale of the Hirschsprung's Disease/Anorectal Malformation QOL Questionnaire, the Pediatric QOL Inventory, and a social relationship questionnaire. Structural equation models were used to explore the relations hypothesized.

RESULTS

No differences were found in the QOL scores across gender. The hypothesized model fits the data well; mothers' perception of social support partially mediated the relationship between fecal incontinence and QOL.

CONCLUSIONS

An important direction for pediatric surgeons and their interdisciplinary teams may be to develop strategies to strengthen mothers' social relationships.

Improved storage of erythrocytes by prior leukodepletion: flow cytometric evaluation of stored erythrocytes

In vivo phagocytosis of senescent red blood cells (RBCs) by macrophages occurs 120 days after their release into the circulation. It depends on two sequential signals that trigger phagocytosis: (1) desialylation of membrane glycoconjugates with the exposure of the penultimate beta-galactosyl residues and (2) exposure of phosphatidylserine in the membrane outer leaflet. Leukodepleted and nonleukodepleted RBCs were compared using flow cytometric procedures to determine whether the in vitro deterioration of RBCs during storage might be attributable to an identical mechanism of desialylation induced by leukocyte neuraminidases, resulting in exposure of beta-galactosyl and subsequently phosphatidylserine residues - signals of senescent RBCs. Without prior leukodepletion, stored RBCs showed an increased population of senescent RBCs (using light scatter measurements), extensive desialylation with the exposure of beta-galactosyl residues (using specific fluorescein isothiocyanate [FITC]-lectins), significant exposure of phosphatidylserine in the outer leaflet of the RBC membrane (using FITC-annexin V), and extensive in vitro phagocytosis (using PKH-26-labeled RBCs). There were minimal changes observed with the leukodepleted RBCs. These results lead to the conclusion that leukocyte enzymes, including neuraminidases, are definitive contributers to the desialylation of RBCs during storage and to the exposure of phosphatidylserine residues. These deleterious effects resulting from highly active leukocyte enzymes are preventable by prior leukodepletion of the stored RBCs. Previously developed flow cytometric procedures to detect in vivo "RBC senescence" have been applied and proved to be reliable criteria to monitor the viability of stored RBCs.

Cellular and molecular mechanisms of senescent erythrocyte phagocytosis by macrophages. A review

Human red blood cells (RBCs) have a life-span of 120 days in circulation, after which they are phagocytized by resident macrophages. Extensive studies have been undertaken by many investigators in order to elucidate the cellular and molecular mechanisms of the erythrophagocytosis. The critical questions addressed by physiologists, clinicians and biochemists are: 'which of the many traumatic blemishes that appear on the erythrocyte surface as it winds its way through the circulation is the primary signal for clearance of the effete RBC from the circulation?', or 'What is the critical signal that it, and it alone, will activate the resident macrophage to adhere to and engulf it?'. Numerous, and often conflicting, hypotheses have been proposed. Each investigator focusing on but one of the many modifications that afflict the cell surface of the ageing erythrocyte, viz changes in either or both the carbohydrate or peptidic moieties of glycoproteins; abolishment of the pre-existing asymmetry in the lipid bilayer with the exposure of phosphatidylserine residues; or alterations in spectrin, to mention but a few. Many of these investigators also have invoked an intermediary role for auto-immune antibodies that recognise the change(s) on the erythrocyte surface and thereby serve as opsonins as a prelude to the erythrophagocytosis. The objective of the present review is to evaluate the data in support of the various hypotheses, and to submit some of our own recent observations involving the use of flow cytometric procedures that: i) provide evidence that the cell surface sialic acid serves as a determinant of the life-span; ii) characterise the senescent erythrocyte population that is specifically captured and phagocytized by macrophages (utilising the rapid and sensitive procedure we developed for quantification of in vitro erythrophagocytosis); and finally iii) provide evidence for the existence of an alternative pathway that is independent of immunoglobulins.

Molecular mechanisms of erythrophagocytosis: flow cytometric quantitation of in vitro erythrocyte phagocytosis by macrophages

A rapid, sensitive, and reproducible flow cytofluorimetric procedure is described for quantitation of erythrophagocytosis based on the use of red blood cells (RBCs) labeled with the fluorescent probe PKH-26. The procedure involves the following steps: i) incubation of PKH-26-labeled erythrocytes with macrophages, ii) removal of un-bound red blood cells, iii) lysis of membrane-bound RBCs, and iv) measurement of extent of phagocytosis by direct flow-cytometric analysis of intact macrophages. Each step was controlled by fluorescence microscopy. Use of fluorescent, instead of radio-labeled RBCs, makes the method more sensitive, rapid, and avoids radioactive hazards. Furthermore, this approach is multi-parametric and can distinguish different populations of macrophages with reference to their erythrophagocytic potential. This technology moreover, has broad applications from the initial step of contact (between effector and target cells to study the specific receptor mediated attachment) to the subsequent cascade of time-dependent changes resulting from that signal transduction.

Molecular mechanisms of erythrophagocytosis. Characterization of the senescent erythrocytes that are phagocytized by macrophages

We have recently developed a flow cytometric assay for the quantitation of erythrophagocytosis, using PKH 26-labeled erythrocytes as the target cells. Using this assay we have shown that there is extensive phagocytosis of desialylated erythrocytes. Furthermore, we have demonstrated that it is the densest population of erythrocytes obtained on a self-forming gradient of Percoll that shows the greatest susceptibility to phagocytosis. We designate this population of erythrocytes as fraction X; it is even denser than the fraction 5 found previously. This population of erythrocytes corresponds to zone X previously seen in the dot-plot of the flow cytometric analyses of human erythrocytes. Further scrutiny of this fraction indicates that a) it shows the greatest reactivity with annexin V, which is specific for the detection of phosphatidylserine (PS) exposed on the outer leaflet of the erythrocyte membrane, b) it is the most susceptible to erythrophagocytosis by resident murine peritoneal macrophages, and c) this erythrophagocytosis of PKH 26-labeled erythrocytes can be inhibited by annexin V and by liposomes containing PS. Scanning electron microscopy of fraction X shows two populations of erythrocytes: (A) spheroechinocytes with filipodes and (B) echinocytes without filipods. After a 2-h period of phagocytosis, the cells remaining in fraction X show a decrease in population A, commensurate with a decrease in reactivity with FITC-labeled annexin V from 65.5 to 24%.

Flow cytometric analysis of human erythrocytes: II. Possible identification of senescent RBC with fluorescently labelled wheat germ agglutinin

In the first paper of a series (Gutowski, et al., 1991) we discussed the use of flow cytometry to follow at the cellular level the aging of red blood cells (RBC) in circulation, using fluorescently labelled lectins and goat anti-human-IgG and -IgM. The Coulter Epics 541 was used for those studies. In this report we describe more extensive experiments using the Becton-Dickinson FACScan flow cytometer, and compare the results with those obtained with the Coulter Epics 541. By changing sample conditions from isotonic to hypotonic, compensation for differences of the two instruments was accomplished. We confirmed our previous observations that RBC react very strongly with fluorescein isothiocyanate labelled wheat germ agglutinin (FITC-WGA) and that there is little change in the intensity of fluorescence given by RBC of all sizes with the exception of the smallest. Reactivity with FITC-WGA is markedly decreased in the presence of competitive inhibitors of sialic acid or upon enzymatic removal of sialic acid from RBC. Removal of sialic acid is accompanied by increased reaction with peanut agglutinin (FITC-PNA). Flow cytometry was also used to monitor the enrichment of a population of smallest RBC (less than 0.05%), isolated from both counterflow centrifugation and the interface obtained from Histopaque separation. These smallest RBC showed low reactivity with FITC-WGA and higher binding of FITC-goat-anti-human-IgG, and -IgM, and therefore represent the most senescent RBC, just prior to their clearance from circulation by the reticuloendothelial system. These observations are in compliance with the hypothesis that physiological desialylation of glycophorin is responsible for clearance of senescent RBC from circulation (Aminoff, 1988).

Flow cytometric analysis of human erythrocytes: I. Probed with lectins and immunoglobulins

A recent review (Aminoff, 1988) summarized the evidence for and against our hypothesis for the role of glycophorin in the senescence and clearance of mammalian red blood cells (RBC) from circulation. This hypothesis postulates the loss of sialic acid from RBC surface in two forms: (a) as vesicles containing the sialoglycoprotein glycophorin, and (b) as free sialic acid residues from glycophorin molecules remaining on cell surface. In this report we demonstrate the applicability of flow cytometric procedures to explore, at the cellular level, time-dependent changes on RBC surface with change in cell size, and with in vivo age. The RBC are probed with fluorescein isothiocyanate (FITC) labelled lectins and goat anti-human-IgG and -IgM. The relative intensity of fluorescence is correlated to the change in RBC size as measured by forward lightscatter. Reactivity of RBC with FITC-labelled wheat germ agglutinin can be inhibited with either 0.2M N-acetylglucosamine or by removal of sialic acid residues with neuraminidase. The properties of the smallest RBC correspond to those of the oldest RBC in their: (a) decreased reactivity with FITC-labelled lectins that recognize sialic acid residues, wheat germ and Limax flavus agglutinins, and (b) increased reactivity with FITC-labelled goat anti-human-IgG and -IgM. These results are compatible with our glycophorin hypothesis. Moreover, they suggest that the initial loss of sialic acid as glycophorin containing vesicles is gradual, while the subsequent step involving the loss of sialic acid residues is rapid and exposes multiple disaccharide galactose beta(1-3)N-acetylgalacosaminyl residues. These unmasked disaccharide sites are recognized by autoimmune IgG, IgM, and lectin-like receptors on macrophages resulting in the clearance of senescent RBC from circulation.

The effect of glycosidases on the survival of rat erythrocytes in circulation

Enzymatic removal of sialyl groups from mammalian erythrocytes resulted in their rapid sequestration from circulation subsequent to autologous transfusion. It has been demonstrated by many investigators that the terminal beta-D-galactosyl group, exposed on red blood cell by in vitro desialosylation, is recognized by an autoimmune anti-galactosyl IgG and/or by a lectin-like receptor on monocytes and macrophages. It is demonstrated herein that the disaccharide structure beta-D-Galp-(1----3)-D-GalpNAc (a) is masked in normal rat RBC, but exposed in asialo-RBC; (b) could be detected with fluorescently-labeled peanut agglutinin; (c) could be released from the asialo-RBC with an endo-N-acetyl-alpha-D-galactosaminidase; and (d) upon its removal by treatment with the endo-N-acetyl-alpha-D-galactosaminidase, enhances the survival of the asialo-RBC in circulation.

Adhesion and erythrophagocytosis of human senescent erythrocytes by autologous monocytes and their inhibition by beta-galactosyl derivatives

Senescent human erythrocytes (RBC) are able to adhere to and be phagocytized by autologous monocytes in vitro to a greater extent than are young RBC. This adhesion and erythrophagocytosis of senescent RBC is inhibited by D-galactose, N-acetyl-D-galactosamine, their corresponding derivatives of bovine serum albumin, and lactose. On the other hand, D-glucose, D-mannose, L-fucose, N-acetyl-D-glucosamine, and their corresponding derivatives of bovine serum albumin are noninhibiting. The glycopeptides released by tryptic digestion of senescent RBC and purified on immobilized peanut agglutinin are the most effective inhibitors of both RBC adhesion and phagocytosis by autologous monocytes obtained from peripheral blood.

Use of 75Se-labeled methionine to study the sequestration of senescent red blood cells

Labeling red blood cells with Na251CrO4 enabled us to study certain aspects of red cell survival and sequestration from the circulation. As a random labeling procedure, however, the 51Cr method has certain limitations. Therefore, we developed a cohort labeling method using 75Se-methionine as a two-rat procedure. This gives us a clear pulse-labeled population of rat red cells to study the dynamics of sequestration. With this labeling procedure, it was possible to demonstrate that 1) there is an increase in the density of red cells with age, 2) a significant sequestration of red cells from the circulation is apparent at the end of 48 days and essentially is complete at the end of 60 days, 3) there is a corresponding uptake of senescent red cells in the spleen, which peaks at 55 days, and 4) the 60-day end point is sharper and is more definitive when the "specific activity" (cpm per red blood cell) of the labeled red cells in the spleen is compared to that of the red cells still in the circulation. Asialo red cells, obtained by removal of sialic acid with sialidase, frequently have been used as a model for the study of sequestration of senescent red cells. With the technique herein described, it was possible to show that while asialo red cells will inhibit the uptake of labeled asialo red cells, they have no effect on the sequestration of senescent red cells. Presumably, different sites and mechanisms of sequestration are involved.

Studies on the sequestration of chemically and enzymatically modified erythrocytes

We have developed an experimental animal model to establish the patterns of sequestration of untreated, as well as chemically and enzymatically modified red blood cells (RBC). The intraperitoneal route of transfusion provides a useful way of transferring large numbers of untreated RBC into small animals and assuring their introduction into the circulation within 24 hr. Moreover, this route "filters" some types of modified erythrocytes, eg, glutaraldehyde treated RBC. From the pattern of sequestration, the RBC in the peritoneal cavity then pass through the liver where other types of modified RBC are sequestered, eg, after trypsin, pronase, protease, or sialidase treatment. Some modified RBC show a preference for the spleen as the site of sequestration, eg, galactose oxidase or N-ethylmaleimide treated RBC. These appear in the spleen despite intraperitoneal transfusion. Relevant to this study is the observation that in the rat old RBC are sequestered both by liver and spleen, while asialoerythrocytes are sequestered by liver only. A possible reason for this difference is discussed in the text.

Isolation and characterization of a glycopeptide from human senescent erythrocytes

A glycopeptide (called "senescence-factor glycopeptide", SF-G) has been isolated from a tryptic digest of human erythrocytes by specific adsorption and elution from immobilized peanut lectin. SF-G was detectable in old but not in young erythrocytes isolated from the same unit of blood. It is present in small quantities, less than 1% of the D-galactose oxidase-borotritide-labeled D-galactosyl residues of erythrocytes. SF-G is free of sialic acid but is quite distinct from a similar glycopeptide isolated from completely desialylated erythrocytes. SF-G binds to spleen monocytes, and this property is abolished upon treatment of SF-G with beta-galactosidase. Some, but not all, of the oligosaccharide chains of the SF-G are of the O-glycosyl type, being released by an endo-N-acetyl-alpha-D-galactosaminidase.

Action of alpha-galactosidase from Clostridium sporogenes and coffee beans on blood group B antigen of erythrocytes. The effect on the viability of erythrocytes in circulation

The effect of alpha-galactosidase, purified from Clostridium sporogenes (Maebashi), was examined on erythrocytes from rats, rabbits and gibbons. The amount of galactose released by alpha-galactosidase from Cl. sporogenes and from coffee beans was compared. The amount of sialic acid released by Vibrio cholera sialidase was also determined. Loss of blood group B specificity following treatment with alpha-galactosidase was demonstrated with anti-B lectin. In animal models, removal of all the alpha-galactosyl residues with the coffee bean or clostridial alpha-galactosidase resulted in no change in the sequestration pattern of the treated erythrocytes over a period of several days. In contrast, erythrocytes treated with sialidase were rapidly sequestered from the circulation.

Structure determination of oligosaccharides isolated from A+, H+ and A-H- hog-submaxillary-gland mucin glycoproteins, by 360-MHz 1H-NMR spectroscopy, permethylation analysis and mass spectrometry

Alkaline borohydride reductive cleavage (beta-elimination) of hog submaxillary glycoproteins from three immunologically determined phenotypes, viz. A+, H+ and A-H-, resulted in the release of a series of neutral and acidic oligosaccharide-alditols. 360-MHz 1H-NMR spectroscopy in combination with methylation analysis and mass spectrometry were used for reinvestigation of the structures of these oligosaccharide-alditols. All are partial structures representing the possible complete and biosynthetically incomplete stages of the chain of a pentasaccharide-N-acetylgalactosaminitol, present in the glycoprotein with blood-group-A activity: (formula: see text) In this way, a prolonged argument about the occurrence of a NeuGc(alpha 2 leads to 6) Gal moiety in these carbohydrate chains, suggested by Aminoff et al. [Aminoff, D., Baig, M. M. and Gathmann, W. D. (1979) J. Biol. Chem. 254, 1788-1793 and 8909-8913] has been brought to a definite end. In the investigated oligosaccharide-alditols N-glycoloylneuraminic acid (NeuGc) is in no case attached to galactose (Gal), but, if present, it is (alpha 2 leads to 6)-linked to N-acetylgalactosaminitol (GalNAc-ol).

Purification and properties of alpha-N-acetylgalactosaminidase from Clostridium perfringens

Exo-alpha-N-acetylgalactosaminidase has been purified 8000-fold from Clostridium perfringens by gel filtration, ion exchange chromatography, isoelectric precipitation, and negative adsorption on human O type erythrocytes. The resulting enzyme is active at physiological pH and temperature. Phenyl glycosides, oligosaccharides, mucins, glycolipids, and cell membranes are substrates for this enzyme. The result of enzyme action on blood type A erythrocytes is the loss of A activity and the simultaneous appearance of H activity, characteristic of the O blood group type. Polyacrylamide gel electrophoresis in sodium dodecyl sulfate demonstrates electrophoresis in sodium dodecyl sulfate demonstrates that the blood group A-destroying activity is distinct from the other glycosidase activities found in C. perfringens.

Sialic acid content of erythrocytes in normal individuals and patients with certain hematologic disorders

The sialic acid content of erythrocytes from healthy individuals of different blood types and of patients with known hematological disorders has been determined. The sialic acid was completely released enzymatically with sialidase and quantitated by the thiobarbituric acid method. The sialic acid content of erythrocytes was constant irrespective of ABO blood type, or anticoagulant used; viz, 0.85-0.92 mumoles/ml of packed erythrocytes or 46-53 X 10(6) sialyl residues per cell. Deviations from these normal values were obtained with erythrocytes from patients with a variety of hematological disorders. Patients with the following disorders have significantly (P less than 0.01) lower sialic acid values compared to erythrocytes from healthy individuals (given in the order of decreasing sialic acid content): sickle cell anemia, acute lymphocytic leukemia, chronic lymphocytic leukemia, acute myelomonocytic leukemia, non-Hodgkin lymphocytic lymphoma, chronic granulocytic leukemia, acute myelocytic leukemia, leukemia, and Hodgkin disease.

Resistance of red blood cell membrane to oxygen uptake

The apparent association velocity constant (k'c) was determined before and after disruption of the red blood cell membrane in one of several ways: 1) radiation of the cells using a 137Cs source did not significantly alter k'c (95 +/- 39.3 and 118 +/- 35.5 mM-1.s-1), 2) incubation of the cells with sialidase produced no change in k'c (112 +/- 42.6 and 123 +/- 46.8 mM-1.s-1), 3) using papain for the incubation similarly produced no significant alteration in k'c (94 +/- 21.2 and 113 +/- 51.8 mM-1.s-1), 4) a radiomimetic agent p-chloromercuribenzene sulfonate likewise produced no significant alteration in k'c (128 +/- 16.3 and 122 +/- 3.5 mM-1.s-1), and 5) employing phospholipase C to disrupt the membrane k'c did not significantly change (115 +/- 15.3 and 112 +/- 8.7 mM-1.s-1). We conclude that either O2 traverses the membrane in a manner uninfluenced by the manipulations here employed, or that the membrane offers no significant resistance to the speed of O2 uptake.

Antibodies that define NANA-independent MN-system antigens

The hemagglutinating properties of a large proportion of anti-M and anti-N reagents, and sera containing antibodies to MN-related antigens, have been shown to be unaffected by treatment of red blood cells with neuraminidase. These antibodies, which define NANA-independent MN-system structures, provide further evidence that MN blood group specificity may also be determined by moieties other than N-acetylneuraminic acid.

2-acetamido-2-deoxy-alpha-D-galactosidases of Clostridium perfringens. Separation and characterization of an exoglycosidase and an oligosaccharidase

Two distinct 2-acetamido-2-deoxy-alpha-D-galactosidases have been separated from filtrates of cultured Clostridium perfringens by electrophoresis in 6.5% poly(acrylamide) gels. One of the enzymes had a mobility of 0.32--0.36 (relative to Bromophenol Blue) and was identified as the exoglycosidase, 2-acetamido-2-deoxy-alpha-D-galactosidase. It appears to be the same enzyme as that reported in 1972 by McGuire et al. The second of the two enzymes, having a relative mobility of 0.42--0.46, corresponds to the oligosaccharidase reported in 1972 by Huang and Aminoff. The A-specificities of human type-A erythrocytes and of water-soluble glycoproteins having A-activity are both destroyed by incubation with the 2-acetamido-2-deoxy-alpha-D-galactosidase, but not on incubation with the oligosaccharidase. A concomitant rise in blood-group O(H) activity, as indicated by the use of a lectin from Ulex europeus, occurred in the A-erythrocytes treated with the exoglycosidase 2-acetamido-2-deoxy-alpha-D-galactosidase.

Effect of galactose oxidase, with and without prior sialidase treatment, on the viability of erythrocytes in circulation

Previous studies have shown that sialidase-treated mammalian erythrocytes were rapidly eliminated from circulation. In contrast, chicken asialoerythrocytes remained fully viable. This investigation was undertaken to ascertain the reason for this difference in behavior as well as to determine the extent of the similarity of the physiological mechanism for the elimination from circulation of asialoglycoproteins and mammalian asialoerythrocytes. To that end, erythrocytes from dogs, rabbits, and chickens were each subjected to the action of galactose oxidase (D-galactose:oxygen 6-oxidoreductase; EC 1.1.3.9) both before and after sialidase (acylneuraminyl hydrolase; EC 3.2.1.18) treatment. The viability of the autologously transfused erythrocytes in circulation was monitored by Na2-51CrO4 labeling. Galactose oxidase had no deleterious effect on the viability of dog or chicken erythrocytes, nor did it restore the viability of dog or rabbit asialoerythrocytes. On the other hand, desialated chicken erythrocytes, which were fully viable, were rendered nonviable upon treatment with galactose oxidase. It may be concluded therefore that (a) the physiological mechanism of elimination of mammalian asialoerythrocytes from circulation is not the same as that for plasma asialoglycoproteins and (b) the treatment of chicken asialoerythrocytes with galactose oxidase results in the oxidation at carbons 6 of the galactosyl- or N-acetylgalactosaminyl residues, thereby rendering the erythrocytes nonviable.

Role of sialic acid in survival of erythrocytes in the circulation: interaction of neuraminidase-treated and untreated erythrocytes with spleen and liver at the cellular level

Sialidase (neuraminidase; acylneuraminyl hydrolase; EC 3.2.1.18)-treated erythrocytes obtained from different species are susceptible to rapid elimination from the circulation and are sequestered in the liver and spleen. The present studies were concerned with the mechanism of this clearance and how it may relate to the normal physiological process of removing senescent erythrocytes from the circulation. The results obtained indicate a preferential recognition of sialidase-treated as compared to normal erythrocytes by mono-nuclear spleen cells and Kupffer cells of the liver. This recognition manifests itself in both autologous and homologous systems by adhesion of the complementary cells in the form of rosettes, and as such could explain the removal of enzyme-treated erythrocytes from the circulation with their accumulation in liver and spleen. This phenomenon may represent a normal physiological mechanism for removal of senescent erythrocytes containing decreased sialic acid.

Effect of sialidase on the viability of erythrocytes in circulation

Sialic acid has been detected on the erythrocyte surface of a number of different species of animals. The objective of this investigation was to determine the physiological significance of these sialyl residues to the viability of erythrocytes in circulation. Methods have been described for the determination of total sialic acid on red blood cells and the conditions under which it may be released with sialidase. Chicken, dog, goat, and rabbit were chosen for these studies because of the differences in the amount (3 X 10(6) - 72 X 10(6) resides per erythrocyte), and type (N-acetyl-or N-glycolyl-neuraminic acids) of sialic acid found on the surface of their erythrocytes. Radioactive tagging with Na251CrO4 was used to monitor the effect of sialidase on the viability of erythrocytes upon autologous transfusion. By the two criteria used to assess the viability of erythrocytes-the percentage of erythrocytes surviving 24 hr after the autologous transfusion, and the half-life of those red blood cells in circulation that survive the first 24 h after the autologous transfusion, and the half-life of those red blood cells in circulation that survive the first 24 hr-it is apparent that the presence of sialic acid on the cell surface is crucial for the survival of nonnucleated mammalian erythrocytes. The loss of viability of dog erythrocytes can be elicited by the removal of approximately 10% of the total sialic acid. In marked contrast to the behavior of mammalian erythrocytes, sialidase-treated chicken erythrocytes appear to retain their viability in circulation.

Effect of sialidase on blood group specificity of hog submaxillary glycoproteins

Hogs can be divided into three phenotypes A, H and In, depending on the ability of extracts of their submaxillary glands to inhibit the agglutination of human A cells with human anti-A, and human O cells with eel-anti-H serum. Evidence is here provided that the inactive glycoprotein, In, represents H active glycoprotein containing additional N-glycolyl neuraminic acid, which stereospecifically masks the H determinant, alpha (1 --> 2)-L-fucosyl residue.