Update on programs for achieving Specialist in Blood Banking certification in the United States: 2023.

A person who has achieved the Specialist in Blood Banking (SBB) certification is a medical laboratory scientist who receives advanced training in blood banking and transfusion medicine and has passed an examination given by the American Society for Clinical Pathology. There are several pathways or "eligibility routes" to qualify for the examination to obtain SBB certification, with the most common route involving enrollment in a Commission on Accreditation of Allied Health Education Programs-accredited SBB program. The goal of this study was to compile information about the current accredited SBB programs in the United States and SBB exam statistics for purposes of assessing changes in the programs and detecting trends in SBB exam takers and pass rates. SBB program coordinators were surveyed about qualitative and quantitative aspects of their programs. Current data, changes over time, and nationally available data were tabulated for comparison. This information may be helpful for all medical laboratory scientists interested in considering further studies and certification in blood banking and transfusion medicine.

Novel KEL allele associated with loss of Kpb identified in a white blood donor.

The importance of identifying variant alleles among blood donors is significant to the safety of transfusion for recipients. Molecular methods have become more prominent in the routine process of antigen typing donor units. Some variant antigens cannot be detected using only serologic methods. Molecular testing allows the determination of nucleotide sequences that are used to predict a phenotype. Antigens of the Kell blood group system are known for being highly immunogenic and causing adverse reactions upon antibody formation. A female white blood donor who typed Kp(b-) using serologic methods on multiple donations since 2005 was the subject of a typing discrepancy investigation. Routine genotyping using a commercial genotyping kit (HemoID DQS Panel; Agena Bioscience, San Diego, CA) predicted the donor to type Kp(a+b+). Investigation of the discrepancy between these two results identified a rare single nucleotide variant in the KEL gene at nucleotide position c.948G>T that alters amino acid residue 316 from tryptophan (Trp) to cysteine (Cys). After discovery of the novel allele, adsorption and elution studies were performed to see if there was weakened Kpb expression. The elution studies yielded negative results, which indicated that Kpb is not expressed. The KEL transcripts expressed by the donor were determined using cDNA analysis, and the predicted amino acid sequence of the novel allele was modeled to investigate the impact of the amino acid sequence on the structure of the KEL polypeptide. Both SWISS-MODEL and Robetta software were used to evaluate the impact of the p.Trp316Cys on the three-dimensional protein structure. There was no conformational change noted with SWISS-MODEL, whereas the Robetta software showed a significant conformational change compared with the normal Kp(b+) reference sequence. Because the donor is homozygous for variants associated with k and Jsb expression, it was not possible to determine whether the novel allele is associated with loss of Kpb only or loss of all Kell antigens.

Development of anti-Jk3 associated with silenced Kidd antigen expression and a novel single nucleotide variant of the JK gene.

Anti-Jk3 is a rare alloantibody to a high-prevalence antigen primarily seen in individuals of Polynesian descent and is associated with a handful of well-established variants of the SLC14A1 gene. We report a case of the Jknull phenotype, associated with formation of anti-Jk3, in a patient of non-Polynesian descent. This patient, a 51-year-old woman self-described as of Jamaican and Scottish ancestry, presented to our hospital for oncologic care. The patient's blood sample typed as blood group A, D+. All screening and panel reagent red blood cells showed reactivity, ranging from 2 to 4+; autocontrol and direct antiglobulin test were both negative. Antigen phenotyping revealed Jk(a-b-), leading to suspicion for anti-Jk3, which was subsequently confirmed by our immunohematology reference laboratory. Given her reported familial background, testing of the SLC14A1 gene was performed, revealing that the patient was heterozygous for the single nucleotide variant (SNV) at c.838G>A in exon 8 and therefore carries both JK*01 and JK*02 alleles that encode Jka and Jkb, respectively. However, the patient was found to be heterozygous for several additional SNVs: c.28G>A in exon 3; c.191G>A, c.226G>A, and c.303G>A in exon 4; and c.757T>C in exon 7. The patient's Jk(b-) phenotype can be explained by coinheritance of c.838A with c.191G>A, which defines null allele JK*02N.09. Coinheritance of SNVs c.28G>A and c.838G with rare SNV c.757C that is predicted to cause a non-conservative amino acid change (p.S253P) likely accounts for the complete serologic absence of Jka and the ability to form anti-Jk3 in this case. This finding would represent a new JK*01 null allele. This evaluation illustrates the importance of genetic analysis in identifying the factors preventing a high-prevalence antigen from being expressed, particularly when discovered outside of an expected racial or ethnic group.Anti-Jk3 is a rare alloantibody to a high-prevalence antigen primarily seen in individuals of Polynesian descent and is associated with a handful of well-established variants of the SLC14A1 gene. We report a case of the Jknull phenotype, associated with formation of anti-Jk3, in a patient of non-Polynesian descent. This patient, a 51-year-old woman self-described as of Jamaican and Scottish ancestry, presented to our hospital for oncologic care. The patient's blood sample typed as blood group A, D+. All screening and panel reagent red blood cells showed reactivity, ranging from 2 to 4+; autocontrol and direct antiglobulin test were both negative. Antigen phenotyping revealed Jk(a­b­), leading to suspicion for anti-Jk3, which was subsequently confirmed by our immunohematology reference laboratory. Given her reported familial background, testing of the SLC14A1 gene was performed, revealing that the patient was heterozygous for the single nucleotide variant (SNV) at c.838G>A in exon 8 and therefore carries both JK*01 and JK*02 alleles that encode Jka and Jkb, respectively. However, the patient was found to be heterozygous for several additional SNVs: c.28G>A in exon 3; c.191G>A, c.226G>A, and c.303G>A in exon 4; and c.757T>C in exon 7. The patient's Jk(b­) phenotype can be explained by coinheritance of c.838A with c.191G>A, which defines null allele JK*02N.09. Coinheritance of SNVs c.28G>A and c.838G with rare SNV c.757C that is predicted to cause a non-conservative amino acid change (p.S253P) likely accounts for the complete serologic absence of Jka and the ability to form anti-Jk3 in this case. This finding would represent a new JK*01 null allele. This evaluation illustrates the importance of genetic analysis in identifying the factors preventing a high-prevalence antigen from being expressed, particularly when discovered outside of an expected racial or ethnic group.

New ABO intron 1 variant alleles.

Unusual and discrepant ABO phenotypes are often due to genetic variants that lead to altered levels or activity of ABO transferases and consequently to altered expression of ABO antigens. This report describes eight genetic alterations found in 15 cases with reduced or undetectable expression of ABO antigens. Forward and reverse ABO grouping was performed by standard gel or tube methods. Adsorption-heat elution and saliva testing for H and A substances followed the AABB technical manual procedures. Genomic DNA extracted from whole blood was PCR-amplified to cover the entire ABO coding sequence, splice junctions, proximal promoter, and intron 1 enhancer. Amplification products were sequenced by next-generation or Sanger dideoxy methods, either directly or after cloning into a bacterial plasmid vector. Eight unreported alleles were found in the 15 cases analyzed. Alleles ABO*A(28+1C) and ABO*A(29-5G) harbor variants that alter the consensus sequence at the intron 1 donor and acceptor splice sites, respectively. The other alleles harbor variants that alter the consensus sequence at transcription factor-binding sites in the intron 1 enhancer: specifically, ABO*A(28+5792T), ABO*A(28+5859A), and ABO*A(28+5860G) at GATA-1 sites; ABO*B(28+5877T) and ABO*B(28+5878G) at a RUNX1 site; and ABO*A(28+5843A) at or near a C/EBP site. Molecular and serologic characterization of ABO alleles can help in their future identification and in the resolution of discrepancies.Unusual and discrepant ABO phenotypes are often due to genetic variants that lead to altered levels or activity of ABO transferases and consequently to altered expression of ABO antigens. This report describes eight genetic alterations found in 15 cases with reduced or undetectable expression of ABO antigens. Forward and reverse ABO grouping was performed by standard gel or tube methods. Adsorption-heat elution and saliva testing for H and A substances followed the AABB technical manual procedures. Genomic DNA extracted from whole blood was PCR-amplified to cover the entire ABO coding sequence, splice junctions, proximal promoter, and intron 1 enhancer. Amplification products were sequenced by next-generation or Sanger dideoxy methods, either directly or after cloning into a bacterial plasmid vector. Eight unreported alleles were found in the 15 cases analyzed. Alleles ABO*A(28+1C) and ABO*A(29­5G) harbor variants that alter the consensus sequence at the intron 1 donor and acceptor splice sites, respectively. The other alleles harbor variants that alter the consensus sequence at transcription factor­binding sites in the intron 1 enhancer: specifically, ABO*A(28+5792T), ABO*A(28+5859A), and ABO*A(28+5860G) at GATA-1 sites; ABO*B(28+5877T) and ABO*B(28+5878G) at a RUNX1 site; and ABO*A(28+5843A) at or near a C/EBP site. Molecular and serologic characterization of ABO alleles can help in their future identification and in the resolution of discrepancies.

Assessment of common red blood cell pretreatments to yield an accurate serologic antigen phenotype compared with genotype-predicted phenotype.

For patients requiring multiple transfusions and patients with positive direct antiglobulin tests (DATs), an extended red blood cell (RBC) phenotype can provide valuable information and help to determine the risk of forming alloantibodies. In some instances, the phenotype may be used for prophylactic matching. Phenotyping in this patient population is often hindered by the presence of circulating donor cells and/or by a positive DAT. Several methods, such as EDTA glycine acid (EGA) treatment to remove IgG, hypotonic saline wash to separate autologous RBCs, or reticulocyte separation, are often used in these situations to isolate patient RBCs for serologic phenotyping. This study aimed to determine the accuracy of each RBC pretreatment method by comparing serologically determined antigen types with those predicted by RBC genotyping. Forty-eight peripheral blood samples from recently transfused patients were phenotyped for selected antigens in the Rh, Kell, MNS, Duffy, and Kidd systems. Treatment methods for the sample sets were reticulocyte separation (N = 12), EGA (N = 16), and hypotonic saline wash (N = 20). DNA was extracted using standard methods, and genotyping was performed using the HEA BeadChip panel. In addition, 21 samples positive for RBC-bound IgG were EGA-treated up to two times. These samples were analyzed pre- and post-EGA treatment for RBC-bound IgG by tube DAT and by flow cytometry with fluorescein isothiocyanate-labeled anti-human IgG. After reticulocyte separation, 3 of the 12 samples had discordant types with one antigen each: Fyb, N, and K; serologic results were negative compared with genotype-predicted positive phenotype results. The EGA-treated sample set showed one discordant type: Fyb; serologic results were negative compared with genotype-predicted positive phenotype results. Four of the 20 samples had discordant types involving the following antigens: Fyb, N, e, and M; serologic results were negative compared with genotype-predicted positive phenotype results. After EGA treatment of 21 samples, 14 (67%) were negative for RBC-bound IgG by tube DAT, and 7 remained positive. Using flow cytometry, EGA treatment rendered only 4 samples negative, and 17 remained positive. In the antigen testing sample set of 48 samples, 10 of 511 total antigen types tested were discordant. Discordant types were most frequent in the hypotonic saline wash sample set (N = 6). In the flow cytometry sample set, 48 percent of the samples negative by tube DAT after EGA elution had detectable RBC-bound IgG by flow cytometry. These findings suggest that caution should be taken when using phenotype results from all pretreated RBCs and support the use of RBC genotyping to predict RBC antigen expression in samples from recently transfused patients.For patients requiring multiple transfusions and patients with positive direct antiglobulin tests (DATs), an extended red blood cell (RBC) phenotype can provide valuable information and help to determine the risk of forming alloantibodies. In some instances, the phenotype may be used for prophylactic matching. Phenotyping in this patient population is often hindered by the presence of circulating donor cells and/or by a positive DAT. Several methods, such as EDTA glycine acid (EGA) treatment to remove IgG, hypotonic saline wash to separate autologous RBCs, or reticulocyte separation, are often used in these situations to isolate patient RBCs for serologic phenotyping. This study aimed to determine the accuracy of each RBC pretreatment method by comparing serologically determined antigen types with those predicted by RBC genotyping. Forty-eight peripheral blood samples from recently transfused patients were phenotyped for selected antigens in the Rh, Kell, MNS, Duffy, and Kidd systems. Treatment methods for the sample sets were reticulocyte separation (N = 12), EGA (N = 16), and hypotonic saline wash (N = 20). DNA was extracted using standard methods, and genotyping was performed using the HEA BeadChip panel. In addition, 21 samples positive for RBC-bound IgG were EGA-treated up to two times. These samples were analyzed pre- and post-EGA treatment for RBC-bound IgG by tube DAT and by flow cytometry with fluorescein isothiocyanate­labeled anti-human IgG. After reticulocyte separation, 3 of the 12 samples had discordant types with one antigen each: Fyb, N, and K; serologic results were negative compared with genotype-predicted positive phenotype results. The EGA-treated sample set showed one discordant type: Fyb; serologic results were negative compared with genotype-predicted positive phenotype results. Four of the 20 samples had discordant types involving the following antigens: Fyb, N, e, and M; serologic results were negative compared with genotype-predicted positive phenotype results. After EGA treatment of 21 samples, 14 (67%) were negative for RBC-bound IgG by tube DAT, and 7 remained positive. Using flow cytometry, EGA treatment rendered only 4 samples negative, and 17 remained positive. In the antigen testing sample set of 48 samples, 10 of 511 total antigen types tested were discordant. Discordant types were most frequent in the hypotonic saline wash sample set (N = 6). In the flow cytometry sample set, 48 percent of the samples negative by tube DAT after EGA elution had detectable RBC-bound IgG by flow cytometry. These findings suggest that caution should be taken when using phenotype results from all pretreated RBCs and support the use of RBC genotyping to predict RBC antigen expression in samples from recently transfused patients.

Two small, cysteine-rich and cationic antifungal proteins from Penicillium chrysogenum: A comparative study of PAF and PAFB.

The filamentous fungus Penicillium chrysogenum Q176 secretes the antimicrobial proteins (AMPs) PAF and PAFB, which share a compact disulfide-bond mediated, ß-fold structure rendering them highly stable. These two AMPs effectively inhibit the growth of human pathogenic fungi in micromolar concentrations and exhibit antiviral potential without causing cytotoxic effects on mammalian cells in vitro and in vivo. The antifungal mechanism of action of both AMPs is closely linked to - but not solely dependent on - the lipid composition of the fungal cell membrane and requires a strictly regulated protein uptake into the cell, indicating that PAF and PAFB are not canonical membrane active proteins. Variations in their antifungal spectrum and their killing dynamics point towards a divergent mode of action related to their physicochemical properties and surface charge distribution. In this review, we relate characteristic features of PAF and PAFB to the current knowledge about other AMPs of different sources. In addition, we present original data that have never been published before to substantiate our assumptions and provide evidences that help to explain and understand better the mechanistic function of PAF and PAFB. Finally, we underline the promising potential of PAF and PAFB as future antifungal therapeutics.

Fecal shedding of infectious feline leukemia virus and its nucleic acids: a transmission potential.

Although it is assumed that fecal shedding of feline leukemia virus (FeLV) constitutes a transmission potential, no study has been performed showing that feces of infected cats can be a source of infection. In this study, we investigated fecal viral shedding of FeLV and its role in viral pathogenesis with the goal to improve infection control. FeLV RNA and DNA levels were determined in rectal swabs of experimentally infected cats by real-time PCR, and the results were correlated with proviral and viral loads in whole blood and plasma, respectively, and plasma p27 levels. All antigenemic cats shed FeLV RNA and DNA in feces. To determine whether the viral RNA detected was infectious, virus isolation from feces was also performed. Infectious virus was isolated from feces of antigenemic cats, and these results perfectly correlated with the isolation of virus from plasma. Naïve cats exposed to these feces seroconverted, showing that infection through feces took place, but remained negative for the presence of FeLV provirus and p27 in blood, an outcome so far not described. Some of the organs collected after euthanasia were provirus positive at low copy numbers. From these results it is concluded that fecal shedding of FeLV plays a role in transmission, but it is probably of secondary importance in viral pathogenesis. Nevertheless, sharing of litter pans by susceptible and viremic cats could increase the environmental infectious pressure and appropriate measures should be taken to avoid unnecessary viral exposure.

Global transcription and metabolic flux analysis of Escherichia coli in glucose-limited fed-batch cultivations.

A time series of whole-genome transcription profiling of Escherichia coli K-12 W3110 was performed during a carbon-limited fed-batch process. The application of a constant feed rate led to the identification of a dynamic sequence of diverse carbon limitation responses (e.g., the hunger response) and at the same time provided a global view of how cellular and extracellular resources are used: the synthesis of high-affinity transporters guarantees maximal glucose influx, thereby preserving the phosphoenolpyruvate pool, and energy-dependent chemotaxis is reduced in order to provide a more economic "work mode." sigma(S)-mediated stress and starvation responses were both found to be of only minor relevance. Thus, the experimental setup provided access to the hunger response and enabled the differentiation of the hunger response from the general starvation response. Our previous topological model of the global regulation of the E. coli central carbon metabolism through the crp, cra, and relA/spoT modulons is supported by correlating transcript levels and metabolic fluxes and can now be extended. The substrate is extensively oxidized in the tricarboxylic acid (TCA) cycle to enhance energy generation. However, the general rate of oxidative decarboxylation within the pentose phosphate pathway and the TCA cycle is restricted to a minimum. Fine regulation of the carbon flux through these pathways supplies sufficient precursors for biosyntheses. The pools of at least three precursors are probably regulated through activation of the (phosphoenolpyruvate-)glyoxylate shunt. The present work shows that detailed understanding of the genetic regulation of bacterial metabolism provides useful insights for manipulating the carbon flux in technical production processes.

Transcriptional regulatory network analysis of developing human erythroid progenitors reveals patterns of coregulation and potential transcriptional regulators.

Deciphering the molecular basis for human erythropoiesis should yield information benefiting studies of the hemoglobinopathies and other erythroid disorders. We used an in vitro erythroid differentiation system to study the developing red blood cell transcriptome derived from adult CD34+ hematopoietic progenitor cells. mRNA expression profiling was used to characterize developing erythroid cells at six time points during differentiation (days 1, 3, 5, 7, 9, and 11). Eleven thousand seven hundred sixty-three genes (20,963 Affymetrix probe sets) were expressed on day 1, and 1,504 genes, represented by 1,953 probe sets, were differentially expressed (DE) with 537 upregulated and 969 downregulated. A subset of the DE genes was validated using real-time RT-PCR. The DE probe sets were subjected to a cluster metric and could be divided into two, three, four, five, or six clusters of genes with different expression patterns in each cluster. Genes in these clusters were examined for shared transcription factor binding sites (TFBS) in their promoters by comparing enrichment of each TFBS relative to a reference set using transcriptional regulatory network analysis. The sets of TFBS enriched in genes up- and downregulated during erythropoiesis were distinct. This analysis identified transcriptional regulators critical to erythroid development, factors recently found to play a role, as well as a new list of potential candidates, including Evi-1, a potential silencer of genes upregulated during erythropoiesis. Thus this transcriptional regulatory network analysis has yielded a focused set of factors and their target genes whose role in differentiation of the hematopoietic stem cell into distinct blood cell lineages can be elucidated.

Shedding of feline leukemia virus RNA in saliva is a consistent feature in viremic cats.

The purpose of this investigation was to characterize the shedding pattern of feline leukemia virus (FeLV) RNA in saliva, and to correlate it with the proviral load in whole blood, viral load in plasma, levels of p27 in saliva and plasma, the isolation of infectious FeLV from saliva, and the titers of FeLV-specific antibodies of the IgG and IgA isotypes. We evaluated 24 experimentally FeLV-infected cats for these parameters using real-time RT-PCR and PCR, cell culture assay and sandwich ELISA. We observed that shedding of viral RNA in saliva was a consistent feature in viremic cats. Latently FeLV-infected cats, displaying a very low proviral load, did not shed infectious virus in saliva, but occasionally shed viral RNA. Consequently, salivary shedding of FeLV RNA may not necessarily indicate a transmission potential for susceptible cats. This study also confirmed previous results from our laboratory, showing that a negative result for p27 in plasma, or for viral RNA in plasma or saliva does not exclude FeLV infection, considering that blood cells from those cats contained provirus. We also showed that FeLV RNA and DNA were stable for more than 64 days in saliva samples stored at room temperature. We conclude that the detection of FeLV RNA in saliva may be a useful indicator of viremia, and that the detection of salivary viral RNA by RT-PCR could become a reliable tool for the diagnosis of FeLV infection, which is facilitated by the low invasive method of collection of the samples.

Differential expression of Fc gamma RIIA, Fc gamma RIIB and Fc gamma RIIC in hematopoietic cells: analysis of transcripts.

Fc gamma receptors (Fc gamma R) are glycoproteins that function in the immune response through their ability to bind the Fc portion of immunoglobulin G. Of the three human Fc gamma R classes, Fc gamma RII is most widely distributed among hematopoietic cells and is the only Fc gamma R class present on platelets and megakaryocytes. There are three different genes coding for Fc gamma RII: Fc gamma RIIA, Fc gamma RIIB and Fc gamma RIIC. Alternative splicing of at least two of these genes results in the production of multiple transcripts. Combining Northern blot analysis with reverse transcription-PCR, we analyzed steady state levels of Fc gamma RII mRNA in the megakaryocytic, myeloid and lymphoid lineages. We determined that megakaryocytic cells predominantly contain Fc gamma RIIA mRNA; Fc gamma RIIA transcripts with and without the transmembrane exon (Fc gamma RIIa1 and Fc gamma RIIa2, respectively) are present in comparable amounts. In contrast, B lymphocytes do not express Fc gamma RIIA mRNAs, but do contain both Fc gamma RIIB transcripts, Fc gamma RIIb1 and Fc gamma RIIb2, as well as the Fc gamma RIIC transcript, Fc gamma RIIc. Myelomonocytic cells contain mRNAs from all three Fc gamma RII genes, predominantly the Fc gamma RIIa1 transcript, both Fc gamma RIIb1 and Fc gamma RIIb2 transcripts and Fc gamma RIIc. Lineage-specific expression of the Fc gamma RII genes implies both differential regulation of expression and differential function in diverse cells.

Characterization of the 5'-flanking transcriptional regulatory region of the human Fc gamma receptor gene, Fc gamma RIIA.

The human Fc gamma receptor gene Fc gamma RIIA is expressed in platelets, neutrophils, monocytes and macrophages. Understanding the regulation of expression of Fc gamma RIIA will enhance our knowledge of regulated gene expression and immune function in these cells. We cloned a 3.65 kb region of the 5' end of the Fc gamma RIIA gene and characterized 3.4 kb of previously unreported sequence of the 5'-flanking region. Primer extension studies and RNase protection analyses of mRNA from HEL, K562 and U937 cells revealed multiple transcription start sites. One transcription start site mapped to a 5'-untranslated (5'UT) exon approximately 1 kb 5' to the ATG translation initiation codon, while a second start site mapped near the ATG codon. Reverse transcription combined with PCR (RT-PCR) employing an oligonucleotide in the putative 5'UT exon and an antisense oligonucleotide in the translated region yielded products which confirm that transcription starts in this 5'UT exon 881 bp upstream of the ATG codon. Sequence analysis of the RT-PCR products showed two related RNA splice products which use alternative 3'-consensus AG splice acceptor sites. Fc gamma RIIA mRNA thus has three distinct potential 5'UT regions, two alternatively spliced forms from the start site in the 5'UT exon and the third from the start site near the ATG codon. Comparisons of the human Fc gamma RIIA 5'-flanking region with human Fc gamma RI and mouse Fc gamma RII beta genes as well as with other genes expressed in megakaryocytes, neutrophils and monocytes reveal structural similarities and shared promoter elements.

The ComPact UniLock 2.0/2.4 system and its clinical application in small animal orthopedics.

This study describes the titanium ComPact UniLock 2.0/2.4 locking plate system (Stratec Medical, Oberdorf, Switzerland) and reports its application in nine selected clinical cases. The system was found useful for a variety of indications. Three categories of clinical applications are illustrated. They include (a) long bone fractures, (b) cervical spinal fractures and instabilities and (c) joint instabilities and luxations. A brief introduction to the system has already been published

A soluble form of the human Fc receptor Fc gamma RIIA: cloning, transcript analysis and detection.

The Fc gamma receptors (Fc gamma R) are glycoproteins that bind the Fc region of immunoglobulin G. Human hematopoietic cells express three biochemically distinct classes of Fc gamma receptors: Fc gamma RI (CD64), Fc gamma RII (CD32) and Fc gamma RIII (CD16). Complementary DNA (cDNA) clones for each of the human Fc gamma receptors have been isolated from myeloid and lymphoid cells. We describe the isolation and characterization of four Fc gamma RII clones from a cDNA library obtained from a megakaryocyte-like cell line, human erythroleukemia (HEL). Three clones encode the Fc gamma RIIA transmembrane (TM) form, while one novel clone lacks the TM region but retains the cytoplasmic domain. By conducting reverse transcription coupled to polymerase chain reaction (PCR), we found transcripts coding for this unique form of receptor in RNA from platelets, HEL cells and a second megakaryocyte-like cell line, CHRF-288-11. These results were confirmed by RNase protection analysis of RNA from HEL cells. The structure of the novel cDNA suggested that it codes for a soluble form of Fc gamma RIIA. A soluble Fc gamma RII protein was detected in the conditioned medium from HEL cells but not from the Fc gamma RII-negative T cell line, Jurkat, by immunoprecipitation with the anti-Fc gamma RII monoclonal antibody (mAb), IV.3. The immunoprecipitated protein was of the expected size for a soluble Fc gamma RII lacking the TM region but retaining the cytoplasmic domain. Soluble Fc gamma RIIA may be important in modulating the interaction between immune complexes and membrane-associated Fc gamma RII.

The effect of resource aggregation at different scales: optimal foraging behavior of Cotesia rubecula.

Resources can be aggregated both within and between patches. In this article, we examine how aggregation at these different scales influences the behavior and performance of foragers. We developed an optimal foraging model of the foraging behavior of the parasitoid wasp Cotesia rubecula parasitizing the larvae of the cabbage butterfly Pieris rapae. The optimal behavior was found using stochastic dynamic programming. The most interesting and novel result is that the effect of resource aggregation within and between patches depends on the degree of aggregation both within and between patches as well as on the local host density in the occupied patch, but lifetime reproductive success depends only on aggregation within patches. Our findings have profound implications for the way in which we measure heterogeneity at different scales and model the response of organisms to spatial heterogeneity.

Etiology of pertussis syndrome.

One hundred patients with clinical pertussis were studied to determine the etiology of pertussis syndrome. Forty-two (42%) of the patients had either Bordetella pertussis of Bordetella parapertussis isolated from the nasopharynx. In additional 36 (36%) patients, B pertussis was isolated from the nasopharynx of the associated index case or family contact case. Thus, Bordetella was isolated from 78 (78%) of the patients or from their immediate family group. Of the 22 culture-negative patients residing in culture-negative families, 12 had serologic evidence of Bordetella infection and another was from a family group in which two members were seropositive. Therefore, 91 patients (91%) had bacteriologic or serologic evidence of Bordetella infection themselves or within their families. Viral cultures were obtained on 75 of the patients. Adenoviruses were isolated from 33% of those with positive cultures for B pertussis and from 14% of those with negative cultures. In the group without direct or indirect, bacteriologic or serologic evidence of Bordetella infection, the adenoviral isolation rate (13%) was not significantly different from the adenoviral isolation rate (33%) in patients with a positive bacterial culture. These data do not support a role of adenovirus alone in causing pertussis syndrome.

Inhibition of the anti-V3 loop response to a recombinant gp120SF2 vaccine by preexisting monoclonal antibody.

Our previous studies have shown that maternally transferred MAb 83.1 (Repligen), which recognizes the V3 loop of HIV-1SF2, inhibited the anti-V3 IgG response of offspring BALB/c mice immunized with rgp120SF2 (Chiron). To determine the mechanism of this epitope-specific inhibition, MAb 83.1 was directly administered intraperitoneally to 19-day-old BALB/c mice, followed by immunization with rgp120SF2 in Freund's complete adjuvant at 21 days of age. The total serum anti-rgp120SF2 IgG response was not inhibited by preexisting MAb 83.1, but the anti-V3 IgG response was significantly inhibited (p < 0.03) 12 weeks after immunization. These results confirm epitope-specific inhibition of the immunodominant V3 loop and are consistent with epitope masking by preexisting antibody. Idiotypic dysregulation is unlikely since MAb 83.1 exposure was not required during the period of repertoire development in neonatal mice. Treatment with MAb prior to immunization may redirect the epitope specificity of an HIV vaccine response.

Subacute necrotizing myelopathy: MR imaging in four pathologically proved cases.

This report describes the MR and correlative imaging findings of four histologically proved cases of subacute necrotizing myelopathy in which there was no evidence of a spinal dural arteriovenous fistula. Subacute necrotizing myelopathy is characterized clinically by progressive motor and sensory deterioration, and pathologically by necrosis in the spinal cord. Initial MR imaging showed focal enlargement of the spinal cord and nonspecific T1 and T2 lengthening. Rimlike enhancement was demonstrated in one case. Clinically, steroid therapy failed in all four patients. Follow-up MR scans showed two slightly enlarged lesions, one stable thoracolumbar lesion, and atrophy of a cervical lesion. Open spinal cord biopsies revealed foci of necrosis and abnormal parenchymal vessels with thickened hyalinized walls. A prolonged course distinguishes subacute necrotizing myelopathy from acute transverse myelitis, but the clinical course and imaging appearance are similar to those of intramedullary tumor. Rimlike rather than solid contrast enhancement may be a distinguishing feature. In the absence of a demonstrable spinal dural arteriovenous fistula, the radiologic differentiation of subacute necrotizing myelopathy from tumor is probably impossible, and biopsy establishes the correct diagnosis.

MRI of the floor of the mouth, tongue and orohypopharynx.

Magnetic resonance is the imaging modality of choice for studies of the orohypopharynx, floor of the mouth, or tongue base. The superiority of MRI soft tissue contrast can demonstrate intra- and extraorgan spread of tumor beyond that of CT. Use of T1- and T2-weighted pulse sequences allows better discrimination of pathologic masses from fat or muscle than does CT. Multiplanar capabilities allow ease of examination in the preferred planes. Various sequences or planes of imaging may be chosen to tailor the examination to the anatomic region of interest. The use of Gd-DTPA with T1-weighted images should further improve diagnostic precision of tumor location and extension and may replace the need for the longer T2-weighted sequences. Gadolinium may help differentiate tumor recurrence from fibrosis in the post-radiation patient. New improvements in surface coil technology, motion and flow compensation imaging strategies, faster scan times, and spatial resolution will further advance MRI as the modality of choice for assessment of oropharyngeal, mouth, and tongue soft tissue masses.