Diagnosis of natural killer cell lymphoma by cytology and flow cytometric immunophenotyping. A case report

BACKGROUND: Natural killer (NK) cell lymphoma is a rare type of non-Hodgkin's lymphoma. It classically presents in the nasal region in Asian patients. There are few reports of its cytologic features. We describe a case that we diagnosed by fine needle aspiration (FNA) biopsy using flow cytometry immunophenotyping and cytomorphology. CASE: A 55-year-old, Chinese man presented with symptoms consistent with nasal obstruction. At examination, a polypoid lesion extending from the nose to the back of the throat was found. An intraoral FNA biopsy was performed. Representative smears were obtained and the remainder of the material sent for flow cytometry. A diagnosis of NK cell lymphoma was made. The patient was given chemotherapy and radiotherapy, with complete resolution of the lesion. Recurrence was noted on follow up seven months later. Pieces of tissue were taken for histology and flow cytometry and showed recurrent NK cell lymphoma. The lesion was again successfully treated by chemotherapy followed by radiotherapy. CONCLUSION: In the correct setting, a definitive diagnosis of non-Hodgkin's lymphoma can be made by FNA biopsy. This case of NK cell lymphoma was diagnosed by FNA biopsy using cytomorphology, flow cytometry immunophenotyping and clinical correlation.     

The Hexapeptide inhibitor of Galbeta 1,3GalNAc-specific alpha 2,3-sialyltransferase as a generic inhibitor of sialyltransferases

The mammalian Galbeta1,3GalNAc-specific alpha2,3-sialyltransferase (ST3Gal I) was expressed as a secreted glycoprotein in High Five (Trichoplusia ni) cells. Using this recombinant ST3Gal I, we screened the synthetic hexapeptide combinatorial library to explore a sialyltransferase inhibitor. We found that the hexapeptide, NH(2)-GNWWWW, exhibited the most strong inhibition of ST3Gal I among five different hexapeptides that were finally selected. The kinetic analysis of ST3Gal I inhibition demonstrated that this hexapeptide could act as a competitive inhibitor (K(i) = 1.1 microm) on CMP-NeuAc binding to the enzyme. Moreover, the hexapeptide was shown to strongly inhibit both N-glycan-specific alpha2,3- and alpha2,6-sialyltranferase in vitro, suggesting that this peptide may inhibit the broad range of sialyltransferases regardless of their linkage specificity. The inhibitory activity in vivo was investigated by RCA-I lectin blot analyses and by metabolic d-[6-(3)H]GlcNH(2) radiolabeling analyses of N- and O-linked oligosaccharides in Chines hamster ovary cells. Our results demonstrate that the hexapeptide can act as a generic inhibitor of the N- and O-glycan-specific sialyltransferases in mammalian cells, which results in the significantly reduced NeuAc expression on cellular glycoproteins in vivo.     

A ubiquitous and conserved signal for RNA localization in chordates

During oogenesis in Xenopus laevis, several RNAs that localize to the vegetal cortex via one of three temporally defined pathways have been identified. Although individual mRNAs utilize only one pathway, there is functional overlap and apparent continuity between them, suggesting that common cis-acting sequences may exist. Because previous work with the Vg1 mRNA revealed that short nontandem repeats are important for localization, we developed a new computer program, called REPFIND, to expedite the identification of repeated motifs in other localized RNAs. Here we show that clusters of short CAC-containing motifs characterize the localization elements (LEs) of virtually all mRNAs localized to the vegetal cortex of Xenopus oocytes. A search for this signal in GenBank [9] resulted in the identification of new localized mRNAs, demonstrating the applicability of REPFIND to predict localized RNAs. CAC-rich LEs are also found in ascidians and other vertebrates, indicating that these cis regulatory elements are conserved in chordates. Interestingly, biochemical evidence shows that distinct CAC-containing motifs have different functions in the localization process. Thus, clusters of CAC-containing motifs are a ubiquitous signal for RNA localization and can signal localization in a variety of pathways through slight variations in sequence composition.     

Molecular diagnosis of Duchenne/Becker muscular dystrophy by polymerase chain reaction and microsatellite analysis

Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) are X-linked recessive genetic disorders resulting from mutations in the dystrophin gene. About two-thirds of the affected patients have large deletions or duplications, which occur in the 5' and central region of the gene. The remaining DMD/BMD cases show no deletions, so they cannot be easily identified by current strategies. In these DMD/BMD families, a linkage analysis that involves DNA markers of the flanking and intragenic dystrophin gene are necessary for carrier and prenatal diagnosis. We analyzed eighteen deletion-prone exons of the gene by a polymerase chain reaction (PCR) in order to characterize the molecular defects of the dystrophin gene in Korean DMD/BMD families. We also performed a linkage analysis to assess the usefulness and application of six short tandem repeat markers for molecular diagnosis in the families. We observed a deletion that eliminated the exon 50. Also, a linkage analysis in the families with six short tandem repeat (STR) markers showed heterozygosity at most of the STR markers. The haplotype analysis was useful for detecting the carrier status. This study will be helpful for a molecular diagnosis of DMD/BMD families in the Korean population.     

Hox genes from the earthworm Perionyx excavatus

The Hox genes of the oligochaete, Perionyx excavatus, were surveyed using PCR and phylogenetic analysis. We were able to identify 11 different Hox gene fragments. Comparative and phylogenetic analyses revealed that this oligochaete would have at least five Hox genes of the anterior group, including three copies of labial-type, five of the central group and one of the posterior group. This is the first report regarding sequence information and phylogenetic analysis of Hox genes in the earthworm.     

Components of the human spindle checkpoint control mechanism localize specifically to the active centromere on dicentric chromosomes

The spindle checkpoint control mechanism functions to ensure faithful chromosome segregation by delaying cell division until all chromosomes are correctly oriented on the mitotic spindle. Initially identified in budding yeast, several mammalian spindle checkpoint-associated proteins have recently been identified and partially characterized. These proteins associate with all active human centromeres, including neocentromeres, in the early stages of mitosis prior to the commencement of anaphase. We have examined the status of proteins associated with the checkpoint protein complex (BUB1, BUBR1, BUB3, MAD2), the anaphase-promoting complex (Tsg24, p55CDC), and other proteins associated with mitotic checkpoint control (ERK1, 3F3/2 epitope, hZW10), on a human dicentric chromosome. Each of these proteins was found to specifically associate with only the active centromere, suggesting that only active centromeres participate in the spindle checkpoint. This finding complements previous studies on multicentric chromosomes demonstrating specific association of structural and motor-related centromere proteins with active centromeres, and suggests that centromere inactivation is accompanied by loss of all functionally important centromere proteins.