Abstract AP05: OVARIAN CANCER-ASSOCIATED RAD51D MUTATIONS WHICH IMPAIR ITS INTERACTION WITH XRCC2 RESULT IN DNA REPAIR DEFICIENCY

The proficiency of ovarian cancer cells to repair DNA double-strand breaks (DSBs) by homologous recombination (HR) is a key determinant in predicting response to targeted therapies such as PARP inhibitors (PARPi). The RAD51 paralogs act downstream of BRCA1/2 to facilitate HR. Numerous epidemiological studies have linked mutations in the RAD51 paralogs with hereditary ovarian cancer predisposition. Despite their substantial links to cancer predisposition and development, RAD51 paralog function during HR has remained elusive, in part due to limitations in studying recombination events downstream of RAD51 filament formation. Here we investigate the impact of cancer-associated mutations in the RAD51 paralog, RAD51D, using yeast 2/3-hybrid assays to screen for altered protein-protein interactions. Following the identification of mutations that disrupt the interaction between RAD51D and XRCC2 in yeast, we validated the interaction by co-immunoprecipitation in human cells. Importantly, we determined the impact of these mutations on HR-proficiency using a direct-repeat recombination assay. By characterizing the impact of cancer-associated mutations in the RAD51 paralogs on HR-proficiency, we aim to develop more effective predictive models for therapeutic sensitivity and resistance in patients who harbor similar mutations in these essential genes.

Citation Format: Robert A. Baldock, Catherine A. Pressimone, Jared M. Baird, Anton Y. Khodakov, Yoav Karpenshif, Edwige B. Garcin, Stéphanie Gon, Mauro Modesti, Kara A. Bernstein. OVARIAN CANCER-ASSOCIATED RAD51D MUTATIONS WHICH IMPAIR ITS INTERACTION WITH XRCC2 RESULT IN DNA REPAIR DEFICIENCY [abstract]. In: Proceedings of the 12th Biennial Ovarian Cancer Research Symposium; Sep 13-15, 2018; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2019;25(22 Suppl):Abstract nr AP05.

Fit αβ T-cell receptor suppresses leukemogenesis of Pten-deficient thymocytes

Signaling through the αβT cell receptor (TCR) is a crucial determinant of T-cell fate and can induce two opposite outcomes during thymocyte development: cell death or survival and differentiation. To date, the role played by T-cell receptor in the oncogenic transformation of developing T cells remains unclear. Here we show that human primary T-cell acute lymphoblastic leukemias expressing an αβT cell receptor are frequently deficient for phosphatase and tensin homolog protein (PTEN), and fail to respond strongly to T-cell receptor activation. Using Pten-deficient T-cell acute lymphoblastic leukemia mouse models, we confirm that T-cell receptor signaling is involved in leukemogenesis. We show that abrogation of T-cell receptor expression accelerated tumor onset, while enforced expression of a fit transgenic T-cell receptor led to the development of T-cell receptor-negative lymphoma and delayed tumorigenesis. We further demonstrate that pre-tumoral Pten-deficient thymocytes harboring fit T-cell receptors undergo early clonal deletion, thus preventing their malignant transformation, while cells with unfit T-cell receptors that should normally be deleted during positive selection, pass selection and develop T-cell acute lymphoblastic leukemias. Altogether, our data show that fit T-cell receptor signaling suppresses tumor development mediated by Pten loss-of-function and point towards a role of Pten in positive selection.

Localized Castleman’s Disease in Retroperitoneum Mimicking Broad Ligament Leiomyoma – a Diagnostic Challenge

Primary retroperitoneal tumours pose a diagnostic dilemma and therapeutic challenges because of their location and late detection. Localized Castleman Disease (CD) in retroperitoneal location is a rare occurrence, with incidence of only 4% cases occurring in diverse locations like retroperitoneum. A rare case of unicentric localized Castleman Disease localized in broad ligament is hereby reported which was clinically & radiologically suspected as broad ligament leiomyoma but finally diagnosed as Castleman’s Disease, hyaline vascular type in a young female posing a diagnostic challenge both for the pathologist and clinician. Definite diagnosis is essential as complete surgical excision in case of unicentric Castleman’s Disease has good prognosis after resection.   

Therapeutic targeting of c-Myc in T-cell acute lymphoblastic leukemia, T-ALL

T-ALL patients treated with intensive chemotherapy achieve high rates of remission. However, frequent long-term toxicities and relapses into chemotherapy-refractory tumors constitute major clinical challenges which could be met by targeted therapies. c-MYC is a central oncogene in T-ALL, prompting the exploration of the efficacy of MYC inhibitors such as JQ1 (BET-bromodomain inhibitor), and SAHA (HDAC inhibitor). Using a standardized ex vivo drug screening assay, we show here that JQ1 and SAHA show competitive efficiency compared to inhibitors of proteasome, PI3K/AKT/mTOR and NOTCH pathways, and synergize in combination with Vincristine. We also compared for the first time the in vivo relevance of such associations in mice xenografted with human primary T-ALLs. Our data indicate that although treatments combining JQ1 or SAHA with chemotherapeutic regimens might represent promising developments in T-ALL, combinations will need to be tailored to specific subgroups of responsive patients, the profiles of which still remain to be precisely defined.

RUNX1-dependent RAG1 deposition instigates human TCR-δ locus rearrangement

Within the human TCR-α/δ locus, ordered rearrangements requires RUNX1, which binds to the Dδ2-23RSS and interacts with RAG1 to enhance RAG1 deposition at this site. Absence of this RUNX1 binding site in the homologous murine Dδ1-23RSS offers an explanation for the lack of ordered TCR-δ gene assembly in mice.

V(D)J recombination of TCR loci is regulated by chromatin accessibility to RAG1/2 proteins, rendering RAG1/2 targeting a potentially important regulator of lymphoid differentiation. We show that within the human TCR-α/δ locus, Dδ2-Dδ3 rearrangements occur at a very immature thymic, CD34⁺/CD1a⁻/CD7^+dim stage, before Dδ2(Dδ3)-Jδ1 rearrangements. These strictly ordered rearrangements are regulated by mechanisms acting beyond chromatin accessibility. Importantly, direct Dδ2-Jδ1 rearrangements are prohibited by a B12/23 restriction and ordered human TCR-δ gene assembly requires RUNX1 protein, which binds to the Dδ2-23RSS, interacts with RAG1, and enhances RAG1 deposition at this site. This RUNX1-mediated V(D)J recombinase targeting imposes the use of two Dδ gene segments in human TCR-δ chains. Absence of this RUNX1 binding site in the homologous mouse Dδ1-23RSS provides a molecular explanation for the lack of ordered TCR-δ gene assembly in mice and may underlie differences in early lymphoid differentiation between these species.

Spectrum of histopathological lesions in the fallopian tubes

Background: Fallopian tubes are common surgical specimen in the pathology laboratory; still there is a lack of data to describe the frequency of various histological fi ndings. The aim and objectives of this study was to describe the various histopathological fi ndings of fallopian tubes. Materials and Methods: Two thousand fi ve hundred and seventy fi ve cases where fallopian tubes were removed either separately or along with other female genital tract organs were studied retrospectively and their histopathological fi ndings documented. Results: Ectopic pregnancy comprised maximum number of cases closely followed by salpingitis. Primary neoplastic lesions were rare as compared to secondary malignancies. Serial sections of fallopian tube and sections from representative areas are essential for a pathologist so that the diagnosis of these pathological entities is not missed. Conclusion: Though the fallopian tubes remain unremarkable in majority of the surgical pathological specimens, it must be subjected for histopathological examination to demonstrate the pathological lesions. Journal of Pathology of Nepal (2013) Vol. 3, No.1, Issue 5, 356-360 DOI: http://dx.doi.org/10.3126/jpn.v3i5.7858

How Bacteria Adhere to Brushy PEG Surfaces: Clinging to Flaws and Compressing the Brush

This study examined the compression of solvated polymer brushes on bioengineered surfaces during the initial stages of Staphylococcus Aureus (S. aureus) adhesion from gentle flow. A series of PEG [poly(ethylene glycol)] brushes, 7 to 17 nm in height and completely non-adhesive to proteins and bacteria, were modified by the incorporation of sparse isolated ~10 nm cationic polymer "patches" at their bases. These nanoscale regions, which lacked PEG tethers, were electrostatically attractive towards negative bacteria or proteins. S. aureus drawn to the interface by multiple adhesive patches compressed the PEG brush in the remaining contact region. The observed onset of bacterial or fibrinogen capture with increases in patch content was compared with calculations. Balancing the attraction energy (proportional to the number of patches engaging a bacterium during capture) against steric forces (calculated using the Alexander-DeGennes treatment) provided perspective on the brush compression. The results were consistent with a bacteria-surface gap on the order of the Debye length in these studies. In this limit of strong brush compression, structural features (height, persistence length) of the brush were unimportant so that osmotic pressure dominated the steric repulsion. Thus, the dominant factor for bacterial repulsion was the mass of PEG in the brush. This result explains empirical reports in the literature that identify the total PEG content of a brush as a criteria for prevention of bioadhesion, independent of tether length and spacing, within a reasonable range for those parameters. Bacterial capture was also compared to that of protein capture. It was found, surprisingly, that the patchy brushes were more protein-than bacteria-resistant. S. aureus adhesion driven by patches within otherwise protein-resistant PEG brushes was explained by the bacteria's greater tendency to compress large areas of brush to interact with many patches. By contrast, proteins are thought to penetrate the brush at a few sites of PEO-free patches. The finding provides a mechanism for the literature reports that in-vitro protein resistance is a poor predictor of in-vitro implant failure related to cell-surface adhesion.

Fibrous dysplasia: rapid malignant transformation into osteogenic sarcoma - A rare occurance

Malignant transformation of fibrous dysplasia is rare, occurring in less than 1% of cases with a mean lag period of 13.5 years. We report a case of Osteogenic Sarcoma with chondroid differentiation in a pre-existing Fibrous Dysplasia occurring within one year of surgical resection and without any history of exposure to radiation. To the best of our knowledge and extensive search of literature, malignant transformation of Fibrous Dysplasia in such a short period of time, and without history of radiation exposure has never been reported from India.Journal of Pathology of Nepal (2012) Vol. 2, 335-337DOI: http://dx.doi.org/10.3126/jpn.v2i4.6891

[Midterm survival of valve replacement with Carpentier-Edwards pericardial bioprosthesis in young adults]

Biologic prostheses are generally considered to have superior antithrombotic properties but lack durability. We recommend biologic prostheses to elderly patients aged over 65 years old. The purpose of this report is to evaluate the midterm outcomes of aortic or mitral valve replacement with Carpentier-Edwards Pericardial Bioprosthesis (CEP) in patients younger than 60 years old. We performed valve replacement with CEP in 17 patients, aged 60 years or youngers, in the past 10 years. The survival rate and freedom from cardiac death at 9 years was 73.2% and 87.8%, respectively. There was no valve-related thromboembolism, anticoagulant-related hemorrhage, prosthetic valve endocarditis, structual valve dysfunction or re-operation. The midterm durability of the CEP in young patients was excellent. In selection of valve prosthesis, it is important to consider factors such as risk of re-operation as well as taking warfarins, and the patient's life style and wishes.

[Surgical treatment of chronic constrictive pericarditis due to old tuberculosis; report of a case]

We experienced a case of pericardiectomy to treat constrictive pericarditis due to old tuberculosis. A 40-year-old woman was admitted to our hospital with dyspnea on exertion and edema of both legs. The chest computed tomography showed calcification of anterior ventricles. They were tightened up by calcified band. Subtotal pericardiectomy and removal of the calcification were performed without cardiopulmonary bypass. After the operation, symptoms were not disappeared in early phase. However, improvement for the patient was confirmed 3 months later.

In vivo requirement for glutaredoxins and thioredoxins in the reduction of the ribonucleotide reductases of Escherichia coli

Escherichia coli expresses three types of ribonucleotide reductases (RNRs) that utilize the redox chemistry of cysteine to catalyze the reduction of ribonucleotides. Upon reduction, the cysteines form a disulfide bond and must be reduced. The authors present in vivo studies that shed light on the mechanism by which these enzymes are regenerated. The class Ia enzyme, NrdAB, can be reduced by either the thioredoxins 1 and 2 or by glutaredoxin 1. The class Ib enzyme, NrdEF, is reduced in vivo by a dedicated glutaredoxin-like protein, NrdH. Despite its similarities to glutaredoxins, this protein is itself reduced by thioredoxin reductase in vivo. However, in the absence of thioredoxin reductase and NrdH, glutaredoxin 1 can partially replace NrdH. Despite their similar structures, the NrdEF and NrdAB RNRs differ in their abilities to function under low oxygen conditions. With only traces of oxygen present, NrdAB can allow some growth in the absence of the anaerobic enzyme NrdDG. NrdEF cannot. Furthermore, in anaerobiosis, E. coli is dependent for growth on class III RNR, NrdDG, and on having at least one of the two reductive systems, thioredoxin reductase or glutathione reductase. These findings indicate a role for these enzymes either for NrdDG reactivation or some other essential anaerobic process.

Ribonucleotide reductases: influence of environment on synthesis and activity

Ribonucleotide reductases (RNRs) are enzymes that provide deoxyribonucleotides (dNTPs), the building blocks required for de novo DNA synthesis and repair. They are found in all organisms from prokaryotes to eukaryotes. Interestingly, in the microbial world, several organisms possess the genes encoding two, or even three different RNRs that present different structures and allosteric regulation. The finding of an increasing number of bacterial species that possess more than one RNR might suggest particular functions for these enzymes in different growth conditions. Recent support for this proposal comes from studies indicating that expression and activity of the different RNRs depends on the environment. The oxygen content as well as the redox and oxidative stresses regulate RNR activity and synthesis in various organisms. This regulation has a direct consequence on dNTP pools. An excess of dNTP pools that leads to misincorporation of dNTPs results in genetic abnormalities in eukaryotes as in prokaryotes. In contrast, increased dNTP concentrations help cells to survive under conditions where DNA has been damaged. Hence the use of different RNRs in response to various environmental conditions allows the cell to regulate the amount precisely of dNTP in both a positive and negative manner so that enough, yet not excessive, dNTPs are synthesized.

A novel regulatory mechanism couples deoxyribonucleotide synthesis and DNA replication in Escherichia coli

We present evidence for a complex regulatory interplay between the initiation of DNA replication and deoxyribonucleotide synthesis. In Escherichia coli, the ATP-bound DnaA protein initiates chromosomal replication. Upon loading of the beta-clamp subunit (DnaN) of the replicase, DnaA is inactivated as its intrinsic ATPase activity is stimulated by the protein Hda. The beta-subunit acts as a matchmaker between Hda and DnaA. Chain elongation of DNA requires a sufficient supply of deoxyribonucleotides (dNTPs), which are produced by ribonucleotide reductase (RNR). We present evidence suggesting that the molecular switch from ATP-DnaA to ADP-DnaA is a critical step coordinating DNA replication with increased deoxyribonucleotide synthesis. Characterization of dnaA and dnaN mutations that result in a constitutively high expression of RNR reveal this mechanism. We propose that the nucleotide bound state of DnaA regulates the transcription of the genes encoding ribonucleotide reductase (nrdAB). Accordingly, the conversion of ATP-DnaA to ADP-DnaA after initiation and loading of the beta-subunit DnaN would allow increased nrdAB expression, and consequently, coordinated RNR synthesis and DNA replication during the cell cycle.

The bacterial ATPase SecA functions as a monomer in protein translocation

The ATPase SecA drives the post-translational translocation of proteins through the SecY channel in the bacterial inner membrane. SecA is a dimer that can dissociate into monomers under certain conditions. To address the functional importance of the monomeric state, we generated an Escherichia coli SecA mutant that is almost completely monomeric (>99%), consistent with predictions from the crystal structure of Bacillus subtilis SecA. In vitro, the monomeric derivative retained significant activity in various assays, and in vivo, it sustained 85% of the growth rate of wild type cells and reduced the accumulation of precursor proteins in the cytoplasm. Disulfide cross-linking in intact cells showed that mutant SecA is monomeric and that even its parental dimeric form is dissociated. Our results suggest that SecA functions as a monomer during protein translocation in vivo.

Genes regulated by TorR, the trimethylamine oxide response regulator of Shewanella oneidensis

The torECAD operon encoding the trimethylamine oxide (TMAO) respiratory system of Shewanella oneidensis is positively controlled by the TorS/TorR two-component system when TMAO is available. Activation of the tor operon occurs upon binding of the phosphorylated response regulator TorR to a single operator site containing the direct repeat nucleotide sequence TTCATAN4TTCATA. Here we show that the replacement of any nucleotide of one TTCATA hexamer prevented TorR binding in vitro, meaning that TorR specifically interacts with this DNA target. Identical direct repeat sequences were found in the promoter regions of torR and of the new gene torF (SO4694), and they allowed TorR binding to both promoters. Real-time PCR experiments revealed that torR is negatively autoregulated, whereas torF is strongly induced by TorR in response to TMAO. Transcription start site location and footprinting analysis indicate that the operator site at torR overlaps the promoter -10 box, whereas the operator site at torF is centered at -74 bp from the start site, in agreement with the opposite role of TorR in the regulation of the two genes. Since torF and torECAD are positively coregulated by TorR, we propose that the TorF protein plays a role related to TMAO respiration.

Interactions of glutaredoxins, ribonucleotide reductase, and components of the DNA replication system of Escherichia coli

A strain of Escherichia coli missing three members of the thioredoxin superfamily, thioredoxins 1 and 2 and glutaredoxin 1, is unable to grow, a phenotype presumed to be due to the inability of cells to reduce the essential enzyme ribonucleotide reductase. Two classes of mutations can restore growth to such a strain. First, we have isolated a collection of mutations in the gene for the protein glutaredoxin 3 that suppress the growth defect. Remarkably, all eight independent mutations alter the same amino acid, methionine-43, changing it to valine, isoleucine, or leucine. From the position of the amino acid changes and their effects, we propose that these alterations change the protein so that its properties are closer to those of glutaredoxin 1. The second means of suppressing the growth defects of the multiply mutant strain was by mutations in the DNA replication genes, dnaA and dnaN. These mutations substantially increase the expression of ribonucleotide reductase, most likely by altering the interaction of the regulatory protein DnaA with the ribonucleotide reductase promoter. Our results suggest that this increase in the concentration of ribonucleotide reductase in the cell allows more effective interaction with glutaredoxin 3, thus restoring an effective pool of deoxyribonucleotides. Our studies present direct evidence that ribonucleotide reductase is the only essential enzyme that requires the three reductive proteins missing in our strains. Our results also suggest an unexpected regulatory interaction between the DnaA and DnaN proteins.

Prognosis is predicted by early hearing improvement in patients with idiopathic sudden sensorineural hearing loss

The time-course of the recovery of the hearing level after treatment in 90 patients with idiopathic sudden sensorineural hearing loss was examined. The improvement rate calculated relative to the hearing level of the opposite ear was investigated to estimate the hearing recovery. Follow-up audiograms were performed once per week for 1 month after treatment and once per month thereafter. There were two groups that differed with respect to the characteristics of hearing recovery. One group showed an improvement rate of over 50% at 1-2 weeks and a good improvement rate at 3 months after treatment. In the other group, the improvement rate did not reach 50% at 1-2 weeks, and the improvement rate was poor at 3 months after treatment. The patients with improvement rates of over 50% at 1-2 weeks had earlier initial visits and had mild hearing loss, whereas the patients with profound hearing loss had improvement rates under 50% and poor long-term prognosis. We conclude that the improvement rate at 1-2 weeks after treatment predicts the long-term prognosis for recovery of hearing level in patients with sudden sensorineural hearing loss.

Reconstitution of the trimethylamine oxide reductase regulatory elements of Shewanella oneidensis in Escherichia coli

Several bacteria can grow by using small organic compounds such as trimethylamine oxide (TMAO) as electron acceptors. In Shewanella species, the TMAO reductase respiratory system is encoded by the torECAD operon. We showed that production of the TMAO reductase of S. oneidensis was induced by TMAO and repressed by oxygen, and we noticed that a three-gene cluster (torSTR) encoding a complex two-component regulatory system was present downstream of the torECAD operon. We introduced the torSTR gene cluster into Escherichia coli and showed that this regulatory gene cluster is involved in TMAO induction of the torE promoter but plays no role in the oxygen control. The TorR response regulator was purified, and gel shift and footprinting experiments revealed that TorR binds to a single region located about 70 bases upstream of the transcription start site of the tor structural operon. By deletion analysis, we confirmed that the TorR operator site is required for induction of the tor structural promoter. As the TMAO regulatory system of S. oneidensis is homologous to that of E. coli, we investigated a possible complementation between the TMAO regulatory components of the two bacteria. Interestingly, TorS(ec), the TMAO sensor of E. coli, was able to transphosphorylate TorR(so), the TMAO response regulator of S. oneidensis.

An unsuspected autoregulatory pathway involving apocytochrome TorC and sensor TorS in Escherichia coli

Trimethylamine N-oxide (TMAO) respiration is carried out mainly by the Tor system in Escherichia coli. This system is encoded by the torCAD operon and comprises a periplasmic TMAO reductase (TorA) and a c-type cytochrome (TorC), which shuttles electrons to TorA. Expression of the tor operon is positively controlled by the TorS/TorR phosphorelay system in response to TMAO availability and negatively regulated by apocytochrome TorC. Interaction studies showed that, when immature, TorC can no longer bind TorA efficiently but can bind the periplasmic detector region of sensor TorS. ApoTorC negative autoregulation and TMAO induction are thus mediated by the same sensor protein. As apocytochromes related to TorC could not down-regulate the tor operon, we concluded that this negative control is highly specific. Moreover, the N-terminal half of apoTorC played no role in this control but the immature C-terminal domain of TorC strongly down-regulated the tor operon and interacted with the TorS detector region. This sophisticated autoregulatory pathway thus involves the C-terminal domain of apoTorC and allows optimal TorC biogenesis by preventing from saturation the c-type cytochrome maturation machinery.

Electron transfer and binding of the c-type cytochrome TorC to the trimethylamine N-oxide reductase in Escherichia coli

Reduction of trimethylamine N-oxide (E'(0(TMAO/TMA)) = +130 mV) in Escherichia coli is carried out by the Tor system, an electron transfer chain encoded by the torCAD operon and made up of the periplasmic terminal reductase TorA and the membrane-anchored pentahemic c-type cytochrome TorC. Although the role of TorA in the reduction of trimethylamine N-oxide (TMAO) has been clearly established, no direct evidence for TorC involvement has been presented. TorC belongs to the NirT/NapC c-type cytochrome family based on homologies of its N-terminal tetrahemic domain (TorC(N)) to the cytochromes of this family, but TorC contains a C-terminal extension (TorC(C)) with an additional heme-binding site. In this study, we show that both domains are required for the anaerobic bacterial growth with TMAO. The intact TorC protein and its two domains, TorC(N) and TorC(C), were produced independently and purified for a biochemical characterization. The reduced form of TorC exhibited visible absorption maxima at 552, 523, and 417 nm. Mediated redox potentiometry of the heme centers of the purified components identified two negative midpoint potentials (-177 and -98 mV) localized in the tetrahemic TorC(N) and one positive midpoint potential (+120 mV) in the monohemic TorC(C). In agreement with these values, the in vitro reconstitution of electron transfer between TorC, TorC(N), or TorC(C) and TorA showed that only TorC and TorC(C) were capable of electron transfer to TorA. Surprisingly, interaction studies revealed that only TorC and TorC(N) strongly bind TorA. Therefore, TorC(C) directly transfers electrons to TorA, whereas TorC(N), which probably receives electrons from the menaquinone pool, is involved in both the electron transfer to TorC(C) and the binding to TorA.

The torYZ (yecK bisZ) operon encodes a third respiratory trimethylamine N-oxide reductase in Escherichia coli

The bisZ gene of Escherichia coli was previously described as encoding a minor biotin sulfoxide (BSO) reductase in addition to the main cytoplasmic BSO reductase, BisC. In this study, bisZ has been renamed torZ based on the findings that (i) the torZ gene product, TorZ, is able to reduce trimethylamine N-oxide (TMAO) more efficiently than BSO; (ii) although TorZ is more homologous to BisC than to the TMAO reductase TorA (63 and 42% identity, respectively), it is located mainly in the periplasm as is TorA; (iii) torZ belongs to the torYZ operon, and the first gene, torY (formerly yecK), encodes a pentahemic c-type cytochrome homologous to the TorC cytochrome of the TorCAD respiratory system. Furthermore, the torYZ operon encodes a third TMAO respiratory system, with catalytic properties that are clearly different from those of the TorCAD and the DmsABC systems. The torYZ and the torCAD operons may have diverged from a common ancestor, but, surprisingly, no torD homologue is found in the sequences around torYZ. Moreover, the torYZ operon is expressed at very low levels under the conditions tested, and, in contrast to torCAD, it is not induced by TMAO or dimethyl sulfoxide.

Leukocyte-depleted continuous blood cardioplegia for coronary artery bypass grafting

Many cardiac surgeries are performed with blood cardioplegia. However, some studies suggest that activated neutrophils form blood cardioplegia can cause reperfusion injury. In this study we assessed myocardial protection using a leukocyte-depleted cardioplegic solution. Patients undergoing elective coronary artery bypass grafting (CABG) with continuous blood cardioplegia were divided into two groups: the LD group, which received leukocyte-depleted blood cardioplegia (n = 11); and the control group, which received nonfiltered blood cardioplegia (n = 11). IL-6, IL-8, CK-MB, and troponin T were measured in the coronary sinus blood immediately after the release of the aortic cross-clamp. Cytokine concentrations were also measured upon the patient's return to the ICU. The total dopamine and dobutamine doses, hemodynamic measurements after surgery, and the leukocyte filtration rate were also measured. During antegrade cardioplegia infusion, leukocytes were almost completely removed (filtration rate: 85.8+/-4.0%). However, during terminal warm cardioplegia, leukocyte removal decreased (filtration rate: 39.9+/-7.8%). Immediately after the release of the aortic cross-clamp, plasma CK-MB and troponin T concentrations were significantly lower in the LD group (17.7+/-1.9 U/l and 0.017+/-0.002 ng/ml, respectively) than in the control group (30.3+/-3.6 U/l and 0.072+/-0.029 ng/ml, respectively). The IL-6 and IL-8 concentrations were similar in the LD group and the control group. After the return to the ICU, the CK-MB and troponin T concentrations were similar in the two groups. No significant differences were found in the total doses of dopamine or dobutamine after surgery in the two groups (99+/-77 vs 101+/-128 microg/kg/min). No significant differences were found in the hemodynamic parameters after surgery in the two groups. In patients undergoing CABG with continuous blood cardioplegia, leukocyte-depleted blood cardioplegic solution may attenuate reperfusion injury.

[Double chambered right ventricle in a 62-year-old female: a surgical case report]

A 62-year-old female was admitted with a chief complaint of transient syncope on exertion. Angiography in right ventricle revealed a defect caused by an anomalous muscle bundle and a pressure gradient of 151 mmHg was observed between the two chambers by cardiac catheterization. Resection of the anomalouse muscle bundle was undertaken using a lower median sternotomy starting at the 2nd intercostal space level and through the outflow tract right ventriculotomy. Patch plasty was also undertaken in the outflow tract. Post-operative course was uneventful and pressure gradient had disappeared at the post-operative catheterization. A rare case of DCRV in a 62-year-old patient with a pressure gradient of 151 mmHg in the right ventricle was reported.

[Aortic valve operations through an upper partial sternotomy]

The median sternotomy has been accepted as the most common approach to the heart, because this approach is easily opened and closed, and easy access to the entire heart is possible. Following the pioneering work by Cosgrove and colleagues of using a parasternal incision for aortic and mitral valve operations, several reports suggested that modified minimal access procedures are likely to be associated with reduced postoperative discomfort and faster recovery. Since July 1997, we have used an upper partial sternotomy and a limited skin incision for isolated aortic valve replacement (AVR) at our hospital. To demonstrate the benefits of this approach, we compared 14 AVR operations using our minimal access incision (group M) with 19 patients undergoing isolated AVR using a conventional sternotomy (group F). In the minimal access group of patients, a small skin incision was made from the second intercostal space to the fourth rib. The pectralis major and intercostal muscle was freed from the sternum, and then a transverse half sternotomy was made in the fourth intercostal space using a striker without injury to the right internal mammary artery. A median partial sternotomy from the supersternal notch to the level of the fourth intercostal space. Cardiopulmonary bypass was connected through the same access site to avoid cannulation of both groins. Conversion to median sternotomy was not necessary in any patient including reexploration for postoperative bleeding. There was no operative mortality, stroke, aortic dissection and perivalvular leaks due to technical factors. In group F, wound infection occurred in 1 patient. One patient in group M required reoperation to control postoperative bleeding. Although mean duration of operation, cardiopulmonary bypass, and cross clamp time in group M was not prolonged, the initiation of cardiopulmonary bypass and aortic crossclamp was delayed by difficulties of cannulations. The distance between the transverse sternotomy (lower edge of divided sternum) and the midpoint of aortic valve annulus was correlated with mean duration of cardiopulmonary bypass and cross clamp time. Our experience demonstrates that isolated AVR through an upper partial sternotomy allows the same quality operations as the full sternotomy, although more clinical experience is required to clarify the benefits of this approach. Excellent exposure of the aortic valve through a partial sternotomy may be attained, if an adequate approach can be selected by the position of aortic valve.

Post-parturition infectious endocarditis in a patient with a normal mitral valve

A 29-year-old woman with no history of heart disease was admitted for the treatment of congestive heart failure. Six months earlier, she had given birth, then 20 days later developed a fever and cardiac failure ensued. An echocardiogram demonstrated severe mitral valve regurgitation. Her blood cultures were positive, and we made a diagnosis of mitral valve regurgitation due to infectious endocarditis. Despite treatment for congestive heart failure and antibiotic therapy, resulting in negative blood cultures, her congestive heart failure did not improve, and vegetation on the mitral valve was observed by echocardiography. We successfully removed the infected tissue with mitral valve plasty.

Surfing the wave of clinical laboratory science evolution in Hawai'i

OBJECTIVE

To describe the steps taken by the Hawaii Society for Clinical Laboratory Science, an affiliate of the American Society for Clinical Laboratory Science, to inform local laboratory professionals of current trends and to prepare for the future.

RESULTS

A Strategic Planning workshop was conducted at the 1997 Hawaii Society for Clinical Laboratory Science Annual Meeting where participants reviewed the essential (but non-traditional) functions of clinical laboratory scientists, and described current realities, identified forces and players affecting the changes, and envisioned the future of our profession.

CONCLUSION

As the way health care is provided changes in response to economics and advances in technology, the role of clinical laboratory scientists needs to be redefined. The Hawaii Society for Clinical Laboratory Science continues to provide timely support for members, and plans to work collaboratively with the local chapter of the Clinical Laboratory Managers' Association to advance clinical laboratory science to an appropriate place in the health care community.

Apoptosis and in vivo distribution and clearance of eosinophils in normal and Trichinella spiralis-infected rats

We examined apoptosis of eosinophils obtained from normal rats and rats infected with Trichinella spiralis (T. spiralis). A considerable percentage of normal rats underwent apoptosis within a few hours, however, the apoptosis rate of infected rats was significantly lower. This rate began decreasing only 12 h after infection, reached its lowest level on day 3, and was restored to normal by day 40. We also studied the effects on eosinophil apoptosis of culture supernatants from concanavalin A-stimulated spleen cells from infected rats and found that supernatants from days 3, 7, and 18 of infection inhibited apoptosis eosinophils from normal rats. We then examined the distribution and clearance of eosinophils in vivo. In normal rats, the largest numbers of eosinophils were found in the spleen, liver, and bone marrow. In the infected rats, however, by day 3, by which time the worms had begun to migrate, there was a striking increase in these cells in the intestines. In summary, normal eosinophils are unexpectedly sensitive to apoptosis, whereas infected eosinophils become resistant to this form of cell death.

Regulation of neutrophil apoptosis--its biological significance in inflammation and the immune response

Neutrophils play a pivotal role in host defence against bacterial infection. Their life span is short compared with that of leukocytes of other lineages. Neutrophils are programmed to die by apoptosis at the time of differentiation. However, recent studies have demonstrated that environment also has a great influence on apoptosis of these cells. Based on our recent experimental results, we present here a review of studies on the regulation of neutrophil apoptosis and discuss its biological significance in inflammation and the immune response.

[TNF/TNFR gene and apoptosis]

Intracellular signal transduction pathways induced by in the reaction of TNF and TNF receptors has been clarified through finding of various TNF receptor associated intracytoplasmic molecules. The possible role of these signal transduction pathways for apoptosis induced by TNF is discussed.

Involvement of two types of TNF receptor in TNF-alpha induced neutrophil apoptosis

We previously demonstrated that tumor necrosis factor-alpha (TNF-alpha) induces rapid human neutrophil apoptosis. In this paper, we examined which of the TNF receptors, p55 kDa TNF receptor (55-R) or p75 kDa TNF receptor (75-R), or both are involved in this process using specific rabbit antisera. Antibodies to 55-R (anti55-R) or 75-R (anti75-R) alone did not induce neutrophil apoptosis. Further addition of cycloheximide and anti-rabbit immunoglobulin to anti55-R but not to anti75-R accelerated apoptosis, although anti75-R augmented the capacity of anti55-R to do so. These results suggest that 55-R is a prerequisite for TNF-alpha induced neutrophil apoptosis.

Modulation of rat neutrophil functions by administration of granulocyte colony-stimulating factor

Neutrophil function was examined in rats treated with recombinant human granulocyte colony-stimulating factor (G-CSF) using peripheral blood neutrophils (PBNs) and peritoneal exudate neutrophils (PENs) as sources of cells examined in vitro. Adherence to plastic plates containing fetal calf serum of nonstimulated or N-formylmethionyl-leucyl-phenylalanine (fMLP)- or tumor necrosis factor-alpha-stimulated PBNs obtained from G-CSF-injected rats was lower than that of control rats. In contrast, this adherence was higher in G-CSF-treated rats than in the control group when PENs were used. Neutrophil adherence of G-CSF-injected and noninjected groups was identical when phorbol myristate acetate was used to stimulate neutrophils. Superoxide production of PBNs stimulated with fMLP in vitro was lower in G-CSF-treated rats than in control rats but higher than in the controls when PENs were used. Furthermore, in vitro tumor cell growth inhibition by PBNs was lower in G-CSF-treated rats than in control rats, but when PENs were used inhibition was higher than in the controls.

Eosinophil and eosinophil cationic protein in allergic rhinitis

To evaluate the roles of eosinophils in allergic rhinitis, eosinophil cationic protein (ECP) levels in sera and nasal secretions were measured in 28 patients with allergic rhinitis. In patients, blood eosinophil counts and serum ECP levels were significantly higher than in controls (p < 0.05). However, there was no statistically significant correlation between blood eosinophil count and serum ECP level (r = 0.025). The number of eosinophils and the ECP level in nasal secretion were also measured. In patients, the ECP level increased with the number of eosinophils, and the ECP level in nasal secretion was significantly higher than in controls (p < 0.05). These results suggest that eosinophils and ECP play important roles in allergic rhinitis.

Effects of cimetidine on quinidine distribution in rats

The effects of cimetidine on the time course of plasma concentration, plasma protein binding and tissue distribution of quinidine were studied in rats. The plasma disappearance of quinidine after a 25 mg/kg intravenous injection was fitted to a two compartment open model. In the cimetidine-treated rats (50 mg/kg), the pharmacokinetic parameters of quinidine, such as the plasma total body clearance (Cltot), the volume of distribution at steady state (Vdss) and the elimination rate constant of the central compartment (kel) decreased to 62, 60 and 73%, respectively of those of the non-treated rats. The plasma concentration of quinidine at steady state, after an intravenous injection (20 mg/kg body weight) followed by a constant rate infusion (0.2 mg/min/kg), increased from 3.02 to 5.11 micrograms/ml after cimetidine treatment. The tissue-to-plasma concentration ratio (Kp) of heart, brain and muscle, determined in homogenates at steady state, decreased after cimetidine treatment. The effect of cimetidine lasted several hours after a cimetidine bolus intravenous injection. These decreases of Kp could satisfy quantitatively the decrease of Vdss. It may be concluded that the decrease of Vdss was due to the inhibition of tissue distribution (binding and/or partition to tissue components) of quinidine by cimetidine treatment.