Ashok Nambiar

Role of single-stranded DNA regions and Y-box proteins in transcriptional regulation of viral and cellular genes

Single‐stranded regions, known to be important for optimal rates of transcription, have been observed in the promoters of several cellular genes as well as in the promoters of many pathogenic viruses. Several host‐encoded, single‐stranded DNA binding proteins capable of binding these regions have been purified and their genes isolated. In this review, information available about single‐stranded regions present within various promoters and the interaction of a novel class of single‐stranded DNA binding transcription factors belonging to the Y‐box family of proteins is reviewed. Mechanisms by which these proteins influence transcription of both cellular and viral genes are proposed.

Chicken Y-box proteins chk-YB-1b and chk-YB-2 repress translation by sequence-specific interaction with single-stranded RNA

Y-Box proteins comprise a large family of multifunctional proteins with a wide spectrum of activities in both transcription and translational regulation of gene expression. Earlier, we have reported on the involvement of chk-YB-2 in transcriptional regulation of Rous sarcoma virus long terminal repeats and the involvement of chk-YB-1b in transcriptional regulation of alpha1(I) collagen genes. Here, we have investigated the potential role of chk-YB-2 and chk-YB-1b in RNA metabolism. We report that chk-YB-2 and chk-YB-1b are localized predominantly in the cytoplasm and that they both can bind single-stranded RNA in a sequence-specific and reversible manner. Well-conserved cold-shock domain, N-terminal proline-rich domain and the alternating clusters of acidic and basic amino acids located in the C-terminal ends of these two proteins were all found to be necessary for their RNA-binding ability. Further, we demonstrate that these two proteins inhibit translation in vitro and that binding to RNA is required for this inhibition. The significance of these results is discussed.

Longitudinal management with crossmatch‐compatible platelets for refractory patients: alloimmunization, response to transfusion, and clinical outcomes (CME)

BACKGROUND: The use of crossmatch‐compatible platelets (PLTs) improves posttransfusion corrected count increments (CCIs) in patients with alloimmune PLT refractoriness. However, few reports address the efficacy of utilizing this strategy for patients requiring intensive PLT transfusion therapy lasting several weeks to months.

Cloning of a novel Y-box homology protein (chkYB-1HP) cDNA lacking the cold-shock domain

We have isolated the complete cDNA clone of a novel 262 amino acid Chicken YB-1 Homology Protein (chkYB-1HP) by screening a chicken embryo cDNA expression library. While the chkYB-1HP is identical over its carboxyl-terminal 78 amino acids with the Y-box protein YB-1, it differs strikingly from all other Y-box transcription factors by lacking the cold-shock domain (CSD). We propose that proteins like chkYB-1HP that lack the CSD, but retain the hydrophilic carboxyl domain could regulate Y-box proteins through the formation of heterodimeric complexes.

Two septic transfusion reactions presenting as transfusion-related acute lung injury from a split plateletpheresis unit

Objectives: We report two simultaneous cases of Staphylococcus aureus sepsis initially consistent with and diagnosed as transfusion-related acute lung injury. The sepsis in both cases resulted from transfusion of two split products from a single contaminated plateletpheresis unit. In each case, the platelets were given along with numerous other blood products during posterior spine surgery. The discussion includes presentation, clinical course, diagnosis, and similarities between sepsis and transfusion-related acute lung injury. The cases and discussion highlight the importance of considering sepsis as part of the differential for any patient believed to have transfusion-related acute lung injury with clinical features of sepsis. Data Sources: Data were collected from the patients’ electronic medical records and the hospital laboratory medicine database. Conclusions: Our cases highlight the importance of vigilant investigation in patients suspected of transfusion-related acute lung injury, as septic transfusions are easily missed and may mimic or coexist with transfusion-related acute lung injury. Sepsis should be strongly considered whenever clinical features such as hypotension, leucopenia, and fever are noted in patients with suspected transfusion-related acute lung injury. In comparison to patients receiving red blood cells or plasma, platelet transfusion recipients are at a greater risk for sepsis from a contaminated unit. Patients developing sepsis from a contaminated blood product may meet the clinical definition of transfusion-related acute lung injury. In such cases, if the clinical syndrome is attributed solely to transfusion-related acute lung injury and bacterial sepsis is not suspected, the correct diagnosis may be missed or delayed. Consequently, appropriate treatment for sepsis would also be delayed or not provided and likely result in increased morbidity and mortality.

Ulnar nerve inoculation of poliovirus in bonnet monkey: a new primate model to investigate neurovirulence

A new monkey model of poliovirus neurovirulence has been developed avoiding the currently used intraspinal injection route which traumatizes the spinal cord. Poliovirus type 1 (0.1 ml) was inoculated into the ulnar nerve of bonnet monkeys (Macaca radiata) at the right elbow. Five monkeys were inoculated with 10(7) TCID of LSc/2ab (Sabin vaccine strain); none developed any illness. Limb paralysis, clinically resembling spinal poliomyelitis in children, developed in all four monkeys given greater than or equal to 10(5) TCID50 of Mahoney strain, and in three of four monkeys given 10(4) or 10(3) TCID50. Higher functions and cranial nerves were not affected. Paralysis occurred more frequently in the lower limbs (11 limbs in seven monkeys) than in upper limbs (six limbs in seven monkeys). The incubation period, from inoculation to onset of paralysis, ranged from 5 to 12 days. Further progression of paralysis to other limbs occurred within 2 to 6 days. No illness developed in two monkeys given 10(2) TCID50 of Mahoney virus. All monkeys given LSc/2ab and those given greater than 10(2) TCID50 Mahoney virus developed humoral antibody response; however, infection of the gastrointestinal tract was detected by virus isolation from throat swabs and stools only in monkeys given Mahoney virus, but not in those given LSc/2ab. Thus, intraneural spread of Mahoney virus to the spinal cord, neurovirulence of Mahoney but not of LSc/2ab and retrograde gastrointestinal infection with Mahoney but not with LSc/2ab are the features of this experimental model.

The potential impact of new donor height and weight criteria on young donor eligibility and faint or prefaint reaction rates.

BACKGROUND: New criteria for young blood donors were recently developed to minimize faint reactions in this high‐risk group. The aim of this study was to determine the impact implementation of these criteria would have on collections and donor faint or prefaint reaction rates at our university blood center.

Importance of Getting a Sample for ABO Type Early in a Resuscitation

Testing for patient ABO type is important for two reasons. First, it allows the transfusion service to know which blood products are compatible with the circulating ABO isoagglutinins in the patient’s plasma. Second, it allows a switch in product support from “universal donor” products to ABO type-specific products. This is the most effective way to protect the community blood supply, particularly because more than 50% of patients will have a blood type other than O, and most patients are RhD positive. If a massive transfusion occurs before a sample is obtained for ABO type, it may be impossible to discern the patient’s native type. Further product support will entail risking the community supply of universal components in the effort to save the patient.

Risks of Giving Uncrossmatched Red Cells

Safe transfusion practice dictates that crossmatched red cells should be transfused if the patient is stable enough to wait for the crossmatch testing to be completed. In patients who lack red cell alloantibodies (outside of the ABO blood group system), a fast crossmatch can be performed once the antibody identification is known. Patients with red cell alloantibodies will require a slower, full serologic crossmatch. For those situations where the patient cannot wait for crossmatched blood, ABO compatible but uncrossmatched blood can be transfused. The risk of hemolysis in a patient without red cell alloantibodies is very small; the risk in a patient with red cell alloantibodies is higher, yet transfusion should be undertaken in an actively bleeding patient. Uncrossmatched red cells pose no higher risk of sensitization to “minor” blood group antigens compared with crossmatched red cells.