PubMed Health⌕ Search

Biomedical subjects

D C Russo

Publications and source records attributed to D C Russo.

At least 19 recordsLinked to original sources
PubMed2001

Molecular defects underlying the Kell null phenotype.

Expression of the Kell blood group system is dependent on two proteins, Kell and XK, that are linked by a single disulfide bond. Kell, a type II membrane glycoprotein, is a zinc endopeptidase, while XK, which has 10 transmembrane domains, is a putative membrane transporter. A rare phenotype termed Kell null (Ko) is characterized by the absence of Kell protein and Kell antigens from the red cell membrane and diminished amounts of XK protein. We determined the molecular basis of eight unrelated persons with Ko phenotypes by sequencing the coding and the intron-exon splice regions of KEL and, in some cases, analysis of mRNA transcripts and expression of mutants on the cell surface of transfected cells. Six subjects were homozygous: four with premature stop codons, one with a 5' splice site mutation, G to A, in intron 3, and one with an amino acid substitution (S676N) in exon 18. Two Ko persons with premature stop codons had identical mutations in exon 4 (R128Stop), another had a different mutation in exon 4 (C83Stop), and the fourth had a stop codon in exon 9 (Q348Stop). Two Ko persons were heterozygous for two mutations. One had a 5' splice site mutation (G to A) in intron 3 of one allele that caused aberrant splicing and exon skipping, and the other allele had an amino acid substitution in exon 10 (S363N). The other heterozygote had the same amino acid substitution in exon 10 (S363N) in one allele and a premature stop codon in exon 6 (R192Stop) in the other allele. The S363N and S676N mutants, expressed in 293T cells, were retained in a pre-Golgi compartment and were not transported to the cell surface, indicating that these mutations inhibit trafficking. We conclude that several different molecular defects cause the Kell null phenotype.

Adult↗
PubMed2000

The mouse Kell blood group gene (Kel): cDNA sequence, genomic organization, expression, and enzymatic function.

The human Kell blood group system is important in transfusion medicine, since Kell is a polymorphic protein and some of its antigens can cause severe reactions if mismatched blood is transfused, while maternal alloimmunization may lead to fetal and neonatal anemia. In humans, Kell is an Mr 93,000 type II membrane glycoprotein with endothelin-3-converting enzyme activity that is linked by a single disulfide bond to another protein, XK, that spans the membrane ten times. An absence of XK leads to clinical symptoms termed the McLeod syndrome. We determined the cDNA sequence of the mouse Kell homologue, the organization of the gene, expression of the protein and its enzymatic function on red cells. Comparison of human and mouse Kell cDNA showed 80% nucleotide and 74% amino acid sequence identity. Notable differences are that the mouse Kell protein has eight probable N-linked carbohydrate side chains, compared to five for human Kell, and that the mouse homologue has one more extracellular cysteine than human Kell protein. The mouse Kell gene (Kel), like its human counterpart, is similarly organized into 19 exons. Kel was located to proximal Chromosome 6. Northern blot analysis showed high expression in spleen and weaker levels in testis and heart. Western blot analysis of red cell membrane proteins demonstrated that mouse Kell glycoprotein has an apparent Mr of 110,000 and, on removal of N-linked sugars, 80,000. As in human red cells, Kell is disulfide-linked to XK and mouse red cells have endothelin-3-converting enzyme activity.

Amino Acid Sequence↗
PubMed2000

First example of anti-Kx in a person with the McLeod phenotype and without chronic granulomatous disease.

BACKGROUND: Kx is lacking in the RBCs of patients with the McLeod syndrome. This condition is sometimes associated with chronic granulomatous disease (CGD). If given allogeneic RBCs, CGD patients with the McLeod phenotype may produce anti-Kx and anti-Km, and only phenotypically matched McLeod blood would be compatible. McLeod phenotype persons without CGD have made anti-Km but not anti-Kx (2 examples), and thus both McLeod and K(O) blood would be compatible. CASE REPORT: RBCs from a transfused patient with the McLeod phenotype but not with CGD (non-CGD McLeod) were typed for the Kell blood group antigens, and the plasma was analyzed for the presence of antibody by agglutination. The molecular basis was determined by analyzing for XK protein on RBC membranes by Western immunoblotting, by sequencing the XK gene, and by RFLP. RESULTS: The RBCs did not react with anti-Kx + anti-Km and showed weakening of Kell system antigens. The patient's plasma reacted moderately (2+) with RBCs of common Kell type and strongly (4+) with K(O) RBCs and RBCs of common Kell type treated with dithiothreitol, and did not react with McLeod RBCs. XK protein was absent from the RBC membranes. The XK gene had a point mutation in the donor splice site of intron 1 (G>C). CONCLUSION: This is the first report describing the molecular alteration in a non-CGD McLeod patient who has made anti-Kx. The immune response of people with the McLeod phenotype can vary, and K(O) blood may not always be compatible.

Antibody Formation↗
PubMed1994

Topology of Kell blood group protein and the expression of multiple antigens by transfected cells.

Kell is one of the major blood group systems in human red blood cells (RBCs). The Kell antigens are carried on a 731 amino acid glycoprotein that is thought to span the erythrocyte membrane once. Rabbit antibodies to three synthetic peptides, derived from different parts of the Kell protein, were used to determine the topology of Kell protein on the RBC. Antibodies to a C-terminal peptide and to a peptide derived from amino acid residues 410 to 439 reacted with RBCs treated with 0.2 mol/L dithiothreitol. An antibody to the N-terminal peptide reacted with inside-out RBC vesicles but not with right-side-out vesicles nor with intact RBCs, showing that Kell is a type II membrane protein and that the extracellular portion of the protein is folded by disulfide bonds. By transfection, Kell protein was expressed on the cell surface of surrogate cells, and the transfected cells expressed similar antigenic properties as native RBCs. Kell protein was expressed in COS-1 and K562 cells and in Sf9 cells infected by the Baculovirus system. Transfected K562 cells expressed several high-incidence antigens but not the low-incidence antigen K1.

Animals↗
PubMed1994

Mechanisms for the elimination of potentially lytic complement-fixing variable surface glycoprotein antibody-complexes in Trypanosoma brucei.

Live antibody-coated Trypanosoma brucei parasites remove variable surface glycoprotein (VSG)-antibody complexes from their surface upon warming to 37 degrees C and evade antibody-activated complement lysis by both protein synthesis-dependent and protein synthesis-independent mechanisms. The protein synthesis-dependent process follows antibody-mediated trypanosome agglutination, whereas the protein synthesis-independent mechanism can occur in the absence of trypanosome agglutination. The latter process leads to a more rapid elimination of complement-fixing VSG-antibody complexes.

Agglutination↗
PubMed1994

Transient loss of proteins carrying Kell and Lutheran red cell antigens during consecutive relapses of autoimmune thrombocytopenia.

A patient is described in whom two consecutive relapses of autoimmune thrombocytopenic purpura (AITP) were associated with loss of red cell antigens of the Kell and Lutheran blood group systems respectively. During the second relapse the glycoprotein CD44 and to a lesser extent the LW antigen were also depressed. Both relapses were associated with concomitant production of IgG antibody recognizing high-frequency determinants on the corresponding antigen-carrying protein. Blocking of antigen sites by these antibodies was not the cause of reduced antigen expression, because immunoblotting studies showed absence of Kell protein during the first relapse, and Lutheran protein during the second. On both occasions the red cell changes reverted to normal with disappearance of the antibody as the AITP entered remission. There was no evidence of clonal lymphocyte expansion as demonstrated using immunoglobulin JH and T cell receptor beta chain probes.

Adult↗
PubMed1993

Directional movement of variable surface glycoprotein-antibody complexes in Trypanosoma brucei.

Binding of antibody, antibody fragments (Fab and F(ab)2) and biotin molecules to variable surface glycoprotein (VSG) of Trypanosoma brucei was studied by both light microscopy and fluorescence activated cell sorter (FACS) analysis. Antibodies, antibody fragments and biotin molecules were distributed over the entire parasite surface after incubation at 0 degree C. Upon warming to 37 degrees C, surface bound Fab and F(ab)2 fragments showed different rates of clearance from the parasite surface. Clearance, which in both cases followed double exponential decay kinetics, resulted from a directional movement of VSG-bound antibody complexes from both the surface of the flagellum and the cell body towards the cellular site of active endocytosis, the flagellar pocket (FP), even in the absence of antibody-mediated crosslinking of VSG. Immunofluorescence on trypanosomes permeabilized after binding, clearance and internalization, indicated the location of small amounts of antibody intracellularly, between the nucleus and the flagellar pocket. However, if a cocktail of protease inhibitors was added to the medium, larger amounts of internalized antibody could be detected within vacuoles situated between the nucleus and the flagellar pocket. Movement of antibody-VSG complexes was reversibly inhibited at temperatures below 37 degrees C and by increasing the NaCl concentration in the medium to 200 mM.

Animals↗
PubMed1993

The transferrin receptor in African trypanosomes: identification, partial characterization and subcellular localization.

All eukaryotic cells, including African trypanosomes, require iron for growth and division, and this iron is acquired by the receptor-mediated endocytosis of iron-loaded transferrin (diFe(3+)-transferrin). In trypanosomes transferrin (Tf) has been shown to be delivered into lysosomes and may not recycle back to the cell surface as it does in mammalian cells (Grab, D. J., et al., Eur. J. Cell Biol. 59, 398-404 (1992)). Here, we describe for the first time, the characteristics of a Tf-binding protein with receptor-like properties in Trypanosoma brucei brucei. Bloodstream forms of rodent-adapted T. brucei were incubated with [35S]methionine and detergent lysates chromatographed on a Sephacryl S-300 column. Fractions were incubated with anti-Tf serum to immunoprecipitate Tf/Tf-binding protein complexes. On sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) the molecular mass of the major protein in the immunoprecipitate was 88 to 92 kDa. Tf-binding proteins could also be isolated using diferric Tf-Sepharose. The molecular mass of the major Tf-binding protein, as estimated from Sephacryl S-300 column chromatography, in the presence of detergent, was approximately 90 to 100 kDa and 90 kDa with SDS-PAGE. Each 90 kDa Tf-binding protein was able to bind one molecule of diferric Tf. Since monoclonal antibodies to human and bovine Tf receptors failed to react with any trypanosome proteins, antisera were raised against the T. brucei Tf-binding proteins eluted from Tf-Sepharose at low pH. These antibodies recognized a 90 kDa protein on Western blots of a T. brucei lysate and inhibited the growth of T. brucei in vitro. Immunolocalization studies, using this antiserum showed that the Tf-binding protein was localized in the flagellar pocket and within the early endosomal compartments. In the presence of protease inhibitors there was additional localization in lysosome-like organelles. The Tf-binding characteristics and localization of this 90 kDa protein suggest that this molecule is a strong candidate as a physiological receptor for Tf in these parasites.

Animals↗
PubMed1992

Endocytosed transferrin in African trypanosomes is delivered to lysosomes and may not be recycled.

It has been shown in mammalian systems that the passage of transferrin-colloidal gold (Tf-Au) through the endocytic system is influenced by the size of the gold colloid (Neutra, M. R. et al., J. Histochem. Cytochem. 33, 1134-1144 (1985); Woods, J. W. et al., Eur. J. Cell Biol. 50, 132-143 (1989)). However, in both Trypanosoma brucei brucei and Trypanosoma congolense, widely varying sizes of Tf-Au (Tf-Au5 and Tf-Au15) have been shown to proceed to lysosomes (Webster, P., Eur. J. Cell Biol. 49, 295-302 (1989); Webster, P., D. Grab, J. Cell Biol. 106, 279-288 (1988)). Using an affinity-purified anti-bovine transferrin IgG we have demonstrated that, in both T. brucei and T. congolense, native transferrin, like Tf-Au, is found in the flagellar pocket, coated vesicles, tubular structures, and lysosome-like organelles where it appears to be concentrated. The presence of Tf in the lysosomes was confirmed in colocalization experiments using T. congolense, where native bovine transferrin colocalized with a trypanosome lysosomal marker, a cysteine protease. The data suggest that, unlike the situation in mammalian cells where most transferrin is recycled to the cell surface, in African trypanosomes transferrin is routed into lysosomes and may not, therefore, be recycled.

Animals↗
PubMed1990

The interaction of Trypanosoma brucei with antibodies to variant surface glycoproteins.

Binding to Trypanosoma brucei of polyvalent IgMs and IgGs, monoclonal IgGs and Fab1 fragments of monoclonal IgGs specific for exposed epitopes of T. brucei variant surface glycoproteins (VSGs) was monitored by both immunofluorescence and immunocytochemistry. All antibodies and antibody fragments, were uniformly distributed over the parasite surface after incubation with the organism at 0 degrees C. Upon warming to 37 degrees C bound antibodies and fragments were detected in the flagellar pocket and intracellular organelles. Removal of single layers of bound antibody, or Fab1 fragments, from the cell surface at 37 degrees C, as determined by immunofluorescence, was complete within 20 min and occurred in the presence or absence of protein synthesis. Parasites that had shown an altered distribution of surface-bound antibody after warming remained fully covered with VSGs of the original antigen type as shown by immunocytochemistry.

Animals↗
PubMed1986

Feeding induction in children who refuse to eat.

Seven chronically ill patients who refused to eat after prolonged hospitalizations were started on a feeding induction program that was based on behavior modification. Each of the children exhibited food aversions and was either dependent on central intravenous nutrition or received enteral feedings as the primary source of calories. An intervention program was initiated for six of the patients while they were hospitalized; the program was continued at home by the parents. All seven patients established consistent oral intake, and five were removed from supplemental feeding sources after implementation of the feeding induction programs.

Abnormalities, Multiple↗
PubMed1984

Behavioral interventions and stress management training for hospitalized adolescents and young adults with cystic fibrosis.

Recent studies have demonstrated that the majority of cystic fibrosis (CF) patients are not at high risk for developing psychological problems. Clinical studies emphasizing the development of adaptive coping mechanisms in these patients have been suggested as a more appropriate line of research. The purpose of the present paper is to describe our experience in teaching various behavioral and stress management strategies to help CF patients. Behavioral counseling, relaxation training, and biofeedback have all been used with these patients to help them manage a number of problems more effectively. The predominant presenting problems have included elevated anxiety levels, sleeping difficulties, pain, and hyperventilation episodes. The typical treatment course with these patients is described and a case example is given to help elucidate the nature of behavioral interventions. Patient satisfaction ratings indicate that most patients view these techniques positively. Clinical observations suggest that the acquisition of behavioral coping skills may enhance the CF patient's perceived control of his/her situation, reduce the level of pain and anxiety, and enhance the quality of life.

Adolescent↗
PubMed1984

Behavioral approaches to the management of chronic pain in children.

This article focuses on the basic premises underlying the behavioral assessment and treatment of chronic pain, particularly as they apply to the less distinct pain disorders of childhood, such as obscure headache and abdominal pain. Pain behavior management procedures, relaxation techniques, and biofeedback training are discussed in detail in reviewing recent research developments in this area.

Abdomen↗
PubMed1983

Behavioral variability as a function of noncontingent adult attention, peer availability, and situational demands in three hyperactive boys.

Recommendations about placements for children in need of special education are routinely made and carried out without empirical validation for the efficacy of particular approaches nor the appropriateness of an approach for a particular child. A study was designed to examine a methodological model which focuses on empirically deriving recommendations for the most appropriate teaching situation for any given child requiring special education. Prosocial, problem, and task-related behaviors in three hyperactive boys were assessed in eight prearranged situations: (1) group play with one adult supervising; (2) group play with three adults; (3) group teaching with one adult; (4) group teaching with three adults; (5) individual play with low density noncontingent adult attention; (6) individual play with high density noncontingent adult attention; (7) individual teaching with low density noncontingent adult attention; and (8) individual teaching with high density noncontingent adult attention. Behaviors assessed included adult, peer, and target child attention given and received; compliance; aggression; disruption; task involvement; and percent tasks correctly completed of tasks attempted. Data revealed that the most disruptions and least efficient task performance occurred in the group teaching situation with one adult. The most efficient task performance and fewest disruptions in a teaching situation occurred in the individual teaching setting with high density noncontingent adult attention. In addition, overall mean rates of disruptive behavior were higher in group situations than in individual situations. The data strongly validate the need for carefully selecting educational environments for problem children, and that the behavior of such children is, at least, partially influenced by environmental factors.

Aggression↗
PubMed1981

Compliance training and behavioral covariation in the treatment of multiple behavior problems.

The present study investigated the use of a compliance-training procedure and its effect on untreated deviant child behaviors. Three children, each generally noncompliant to adult requests and with several additional problems, such as crying, aggression, and self-injurious behavior, were trained in the compliance procedure under a multiple-baseline design across therapists. Compliance was defined as the correct response to prespecified requests. Other classes of deviant child behavior were measured continuously throughout the study but not directly reinforced. The results of the study showed that (a) increases in compliance to requests were directly related to the contingencies employed; (b) decreases in untreated deviant behaviors occurred when compliance increased, even though no direct contingencies had been placed on these behaviors; and (c) the relationship between untreated deviant behaviors and compliance appeared to be maintained by a different set of events in each of the three children. The results are discussed in terms of behavioral covariation and generalization.

Aggression↗