Locally Aggressive Rib Hemangioma With Glomeruloid and Papillary Features - Expanding the Clinicopathologic spectrum of Bone Hemangiomas

Intra-osseous hemangiomas are uncommon tumors that can present diagnostic and treatment dilemmas. Bone hemangiomas with papillary and glomeruloid growth patterns are exceptionally rare. We present an example of an intra-osseous hemangioma of the rib displaying aggressive features on both radiology and histology. Morphologically, prominent papillary and glomeruloid architectural patterns were observed, in addition to features of cavernous and capillary hemangiomas. Extensive extra-osseous soft tissue involvement was seen. Awareness of the diverse histological features and locally aggressive behavior of bone hemangiomas is important in avoiding over-interpretation as a malignant lesion.

Clinicopathologic and Molecular Characteristics of Epstein-Barr Virus-Associated Smooth Muscle Tumor Compared With Those of Leiomyoma and Leiomyosarcoma

Epstein-Barr virus (EBV)-associated smooth muscle tumors (EBV-SMTs) are rare smooth muscle neoplasms exclusively associated with immunosuppression, such as in patients with HIV/AIDS, posttransplant, and congenital immunodeficiency. However, the genomic landscape of EBV-SMTs is poorly understood. Leiomyosarcomas harbor genomic instability and multiple recurrent DNA copy number alterations, whereas leiomyomas lack such changes. Thus, this study aimed to fill this knowledge gap by characterizing copy number alterations in EBV-SMTs and correlating this information with clinicopathologic characteristics. Our study investigated and compared the pathologic characteristics and copy number profiles of 9 EBV-SMTs (from 7 post-transplant and AIDS patients), 6 leiomyomas, and 7 leiomyosarcomas, using chromosomal microarray platforms. Our results showed a lower copy number alteration burden in EBV-SMTs and leiomyoma than in leiomyosarcoma. This contrast in the molecular profile between EBV-SMTs and leiomyosarcoma is concordant with the different clinical behaviors and pathologic characteristics exhibited by these tumors. Despite having an overall copy number alteration profile closer to leiomyoma, recurrent copy number gain of oncogenes, such as RUNX1, CCND2, and ETS2, was found in EBV-SMTs. Epigenetic alterations may play an important role in tumorigenesis as recurrent copy number gains were found in histone deacetylases. A gene enrichment analysis also demonstrated enrichment of genes involved in the host response to viral infection, suggesting that the tumor immune microenvironment may play an important role in EBV-SMT tumorigenesis.

MHD simulation of supersonic FRC merging corrected by non-invasive magnetic measurements

In this study, a newly developed correction method with external magnetic measurements for the magnetohydrodynamics (MHD) simulation of the collisional merging formation of a field-reversed configuration (FRC) realized the estimation of the internal structure of the FRCs without invasive internal measurements. In the collisional merging formation of FRCs, an FRC is formed via merging of two initial FRC-like plasmoids at supersonic/Alfvénic velocity. An invasive diagnostic may also interfere with the collisional merging formation process. A two-dimensional resistive MHD simulation was conducted to evaluate the global behavior and internal structure of FRCs in the collisional merging formation process without invasive measurements. This code simulated the initial formation and collisional merging processes of FRCs including discharge circuits. However, the translation velocity and the pressure of initial FRCs did not simultaneously agree with the experimental values because the magnetic pressure gradient in each formation region could not be reproduced without the artificial adjustment of the initial condition. The experimentally measured current distribution was given as the initial condition of the circuit calculation in the developed correction method. The initial FRCs were successfully translated at the translation velocity and plasma pressure in the corrected simulation, both of which were equivalent to the experiments. The properties of the merged FRCs in the experiments such as volume, total temperature, and average electron density were reproduced in the corrected simulation. The detailed radial profile of the internal magnetic field of the FRC was also measured and found to agree very well with the simulation results.

0574 Prevalence and Characteristics of Rapid Eye Movement Obstructive Sleep Apnoea (REM OSA) in a Multi-Ethnic OSA Cohort

Introduction

Recent studies have shown that REM OSA is associated with increased incidence of hypertension and insulin resistance. However, there is a lack of Asian data on REM OSA. Our study aimed to examine the prevalence and characteristics of REM OSA in a multi-ethnic OSA cohort.

Methods

This was a retrospective observational study of all patients who underwent an overnight diagnostic polysomnography at a Singapore tertiary hospital from 1st August 2017 to 31st August 2018. All patients with a diagnosis of OSA (Apnoea Hypopnea Index (AHI) ≥5) were included in the study. REM OSA is defined as an overall AHI≥5, REM AHI/Non REM (NREM) AHI>2, NREM AHI<15 and at least 15 minutes of REM sleep.

Results

457 OSA subjects were included in the analysis. 19% (87/457) had REM OSA. Univariate analysis showed that REM OSA was more prevalent among female OSA than male OSA [34/115 (29.6%) versus 53/342 (15.5%) respectively, p<0.001]. Compared to non REM OSA, REM OSA had milder OSA severity [mean AHI 12.74±4.71 versus 45.34±28.38, p<0.001] and lower prevalence of hypertension [21/87 (24.1%) versus 138/370(37.3%), p=0.02]. No differences were found between both groups for age (p=0.273), ethnicity (p=0.615), Body Mass Index (p=0.336), diabetes mellitus (p=0.245) and Epworth Sleepiness Scale (0.06). Gender and OSA severity differences between both groups remained statistically significant in multivariate analysis (higher prevalence of REM OSA in female, p=0.043 and milder disease severity in REM OSA, p=0.006).

Conclusion

REM OSA was common in our OSA cohort and had higher prevalence in female and milder disease severity compared to non REM OSA. However, we did not find an increased prevalence of hypertension or diabetes mellitus in REM OSA. Further population-based study on REM OSA is needed to understand this phenotype better.

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0627 Cognitive Perceptions Impact Short-Term CPAP Adherence in Asian Patients with Obstructive Sleep Apnea

Introduction

Adherence for the gold standard Continuous Positive Airway Pressure (CPAP) treatment for obstructive sleep apnea (OSA) is poor worldwide. Studies have explored factors impacting CPAP adherence but data is limited for Asian patients where cultural and social norms differ. This study aimed to examine the role of disease and treatment-related perceptions in short-term CPAP adherence among patients from a multi-ethnic Southeast Asian country.

Methods

34 patients with newly diagnosed OSA were recruited from Changi General Hospital, a 1000-bed tertiary hospital in Singapore between September 2018 and February 2019. Psychological factors of self-efficacy, risk-perception and outcome expectancies were assessed with the Self-Efficacy Measure for Sleep Apnea (SEMSA) questionnaire. The SEMSA questionnaire has been previously validated for the evaluation of adherence-related cognitions. Patients were administered the SEMSA questionnaire before commencement of CPAP treatment and 1 month after.

Results

73.5% (25/34) of the patients were male (82.4% Chinese, 11.8% Malays, 2.9% Indians, 2.9% others). Mean age was 43.3 ± 11.8 years, mean apnea hypopnea index (AHI) was 45.2 ± 29.6 events/hr and mean CPAP usage at one month was 3.6±2.0 hours. 47% were adherent to CPAP, defined as average device use > 4 hrs/day. Pre-treatment self-efficacy was significantly correlated with CPAP adherence (r = 0.498, P<0.01). Outcome expectancies and self-efficacy measured after one-month CPAP use were significantly correlated with CPAP adherence (r = 0.702, P<0.01; r = 0.467, P<0.01, respectively). However, no association between risk perception and CPAP adherence was noted at either time points.

Conclusion

Consistent with previous literature in Western population, our study demonstrated that patients’ cognitive perceptions of outcome expectancies and sense of self-efficacy have an impact on CPAP adherence in a Southeast Asian population. Strategies targeting these aspects would be important in designing patient education programs.

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Diabetes mellitus and tuberculosis in Korean adults: impact on tuberculosis incidence, recurrence and mortality

<sec id="st1"> <title>SETTING</title> The prevalence of diabetes mellitus (DM) worldwide is increasing markedly, and many countries with rising rates also have a high incidence rate of tuberculosis (TB). </sec> <sec id="st2"> <title>OBJECTIVE</title> To investigate the relationships of fasting serum glucose (FSG) and DM with TB incidence, recurrence and mortality risk in a prospective cohort study in South Korea. </sec> <sec id="st3"> <title>DESIGN</title> Our study comprised 1 267 564 Koreans who received health insurance from the National Health Insurance System, had an initial medical evaluation between 1997 and 2000 and were prospectively followed biennially. </sec> <sec id="st4"> <title>RESULTS</title> Participants with DM had a higher risk for incident TB (hazard ratio [HR] 1.81, 95%CI 1.71-1.91 in males, HR 1.33; 95%CI 1.20-1.47 in females) than those without DM. There was a strong positive trend for TB risk with rising FSG among males. The risk for recurrent TB among those with previous TB was significantly higher in males (HR 1.58, 95%CI 1.43-1.75) and in females with DM (HR 1.38, 95%CI 1.08-1.76). The increased risk of death from TB during follow-up was also significant in men (HR 1.91, 95%CI 1.87-1.95) and in women (HR 1.71, 95%CI 1.65-1.77). </sec> <sec id="st5"> <title>CONCLUSIONS</title> A diagnosis of DM is a risk factor for TB, TB recurrence and death from TB. Screening for TB should be considered among people living with DM in Korea, particularly those with severe DM. </sec>.

High-grade myoepithelial carcinoma can show histologically undifferentiated/anaplastic features

High grade malignant tumors with a poorly-/un-differentiated morphology pose significant diagnostic challenges. Increasingly, the use of adjunct immunohistochemical and molecular tests to characterize and delineate the histopathologic phenotype of these tumors has become necessary, particularly in head and neck tumors. Recently, several entities with a poorly-/un-differentiated light microscopic morphology have been defined based on specific immunohistochemical and genetic characteristics. We herein describe two cases of high-grade myoepithelial carcinoma, one occurring in the submandibular gland and the other occurring in the left nasal cavity, both showing undifferentiated histological and anaplastic cytomorphological features. This led to very broad differential diagnostic considerations and the diagnosis was only established after extensive immunohistochemical studies. Molecular testing for HPV was negative in both cases. Gene fusion analysis using a targeted sequencing assay (Archer® FusionPlex® system) did not identify fusions involving PLAG1, HMGA2, EWSR1 or ALK genes in either case. The submandibular tumor showed an aggressive clinical course, with diffuse pulmonary metastases at presentation, whilst the nasal cavity tumor showed only localized disease. Awareness of a subcategory of high-grade myoepithelial carcinomas with undifferentiated light microscopical features is of significant importance in antibody selection for immunohistochemical investigation of poorly-/undifferentiated malignant tumors in the head and neck region. This histological variant of myoepithelial carcinoma adds to the growing list of differential diagnoses in this diagnostically complex and multifaceted field.

Primary Renal Hybrid Low-grade Fibromyxoid Sarcoma-Sclerosing Epithelioid Fibrosarcoma: An Unusual Pediatric Case With EWSR1-CREB3L1 Fusion

Low-grade fibromyxoid sarcoma (LGFMS) and sclerosing epithelioid fibrosarcoma (SEF) are rare tumors with distinct sets of morphological features, both characterized by MUC4 immunoreactivity. Tumors exhibiting features of both entities are considered hybrid LGFMS-SEF lesions. While the majority of LGFMS cases are characterized by FUS-CREB3L2 gene fusions, most cases of pure SEF show EWSR1 gene rearrangements. In the largest study of hybrid LGFMS-SEF tumors to date, all cases exhibited FUS rearrangements, a similar genetic profile to LGFMS. We herein describe the clinicopathological features and genetic findings of a case of primary renal hybrid LGFMS-SEF occurring in a 10-year-old child, with disseminated metastases. Fusion gene detection using a next-generation sequencing-based anchored multiplex PCR technique (Archer FusionPlex Sarcoma Panel) was performed on both the primary renal tumor that showed the morphology of a LGFMS, and a cervical metastasis that showed the morphology of SEF. An EWSR1-CREB3L1 gene fusion occurring between exon 11 of EWSR1 and exon 6 of CREB3L1 was present in both the LGFMS and SEF components. This unusual case provides evidence that a subset of hybrid LGFMS-SEF harbor EWSR1-CREB3L1 gene fusions. In this case, these features were associated with an aggressive clinical course, with disease-associated mortality occurring within 12 months of diagnosis.

Internal magnetic field measurements of translated and merged field-reversed configuration plasmas in the FAT-CM device

Field-reversed configuration (FRC) Amplification via Translation-Collisional Merging (FAT-CM) experiments have recently commenced to study physics phenomena of colliding and merged FRC plasma states. Two independently formed FRCs are translated into the confinement region of the FAT-CM device, collided near the mid-plane of the device with a relative speed of up to ∼400 km/s, and a final merged FRC plasma state is achieved. To measure internal magnetic field profiles of the translated and merged FRC plasmas as well as to understand its collisional-merging process, an internal magnetic probe array, developed by TAE Technologies, has been installed in the mid-plane of the FAT-CM device. Initial magnetic field measurements indicate that both the translated and the merged FRC plasma states exhibit a clear field-reversed structure, which is qualitatively in good agreement with 2D MHD simulation. It is found and verified that a sufficient mirror field in the confinement region is required for colliding FRCs to be fully merged into a single FRC plasma state.

The Genomics and Molecular Biology of Natural Killer/T-Cell Lymphoma: Opportunities for Translation

Extranodal NK/T-cell lymphoma, nasal type (ENKTL), is an aggressive malignancy with a poor prognosis. While the introduction of L-asparaginase in the treatment of this disease has significantly improved the prognosis, the outcome of patients relapsing after asparaginase-based chemotherapy, which occurs in up to 50% of patients with disseminated disease, remains dismal. There is hence an urgent need for effective targeted therapy especially in the relapsed/refractory setting. Gene expression profiling studies have provided new perspectives on the molecular biology, ontogeny and classification of ENKTL and further identified dysregulated signaling pathways such as Janus associated kinase (/Signal Transducer and activation of transcription (JAK/STAT), Platelet derived growth factor (PDGF), Aurora Kinase and NF-κB, which are under evaluation as therapeutic targets. Copy number analyses have highlighted potential tumor suppressor genes such as PR Domain Zinc Finger Protein 1 (PRDM1) and protein tyrosine phosphatase kappa (PTPRK) while next generation sequencing studies have identified recurrently mutated genes in pro-survival and anti-apoptotic pathways. The discovery of epigenetic dysregulation and aberrant microRNA activity has broadened our understanding of the biology of ENKTL. Importantly, immunotherapy via Programmed Cell Death -1 (PD-1) and Programmed Cell Death Ligand1 (PD-L1) checkpoint signaling inhibition is emerging as an attractive therapeutic strategy in ENKTL. Herein, we present an overview of the molecular biology and genomic landscape of ENKTL with a focus on the most promising translational opportunities.

Cytomorphological changes induced by intraperitoneal chemotherapy present important diagnostic pitfalls in peritoneal fluid cytology

OBJECTIVE

Intraperitoneal chemotherapy (IP ChT) is an emerging modality in the treatment of advanced gastric adenocarcinoma with peritoneal disease. Cytological evaluation of peritoneal fluid specimens from patients undergoing IP ChT is important in clinical management. However, direct intraperitoneal exposure to chemotherapeutic agents induces cytomorphological changes in benign constituents of peritoneal fluid, presenting particular challenges to accurate cytological interpretation. These morphological changes have not been well characterised in the literature. We systematically reviewed the cytomorphological features in immunocytochemically-confirmed positive and negative IP ChT peritoneal fluid samples to elucidate the degree of morphological overlap between malignant and reactive cells.

METHODS

We reviewed 39 peritoneal fluid samples of patients treated with IP ChT, and scored specific cytomorphological parameters of both benign and malignant cells with the aid of relevant immunocytochemical interrogation.

RESULTS

The present findings show a significant degree of morphological overlap between reactive and malignant cells. Abnormal, "exploding" mitotic figures, nuclear membrane irregularities, multi-nucleation and cytoplasmic vacuolation were commonly observed in negative fluid specimens. The most helpful feature that favoured malignant cells was the increased nuclear-to-cytoplasmic ratio. A background inflammatory milieu of eosinophils and/or neutrophils was seen in 45-58% of post IP ChT peritoneal fluid specimens. The presence of pseudoparakeratotic cells, a novel observation in post IP ChT fluid specimens is also described.

CONCLUSIONS

The extent of reactive cytomorphological anomalies arising from treatment with IP ChT poses unique diagnostic challenges and may prompt a malignant or 'atypical' diagnosis in benign reactive samples.

Do we need transbronchial lung biopsy if we have bronchoalveolar lavage Xpert® MTB/RIF?

BACKGROUND

Studies evaluating the role of transbronchial lung biopsy (TBLB) in diagnosing pulmonary tuberculosis (PTB) date back decades and have shaped current practice. However, with the recent advent of bronchoalveolar lavage (BAL) Xpert® MTB/RIF, it is time to re-evaluate the role of TBLB.

OBJECTIVE

To assess the impact of BAL and TBLB with the addition of BAL Xpert on diagnostic PTB yields and time to treatment initiation in sputum-scarce or acid-fast bacilli (AFB) smear-negative PTB patients.

METHODS

We retrospectively reviewed all sputum-scarce or AFB smear-negative patients who underwent both BAL and TBLB for suspected PTB between March 2011 and October 2013. Xpert was performed on all BAL specimens.

RESULTS

Of 158 patients included in our analysis, 44 were culture-proven PTB. Ninety-four per cent of the patients had AFB smear-negative BAL samples. The sensitivity and specificity of Xpert in AFB smear-negative BAL samples were respectively 60% and 98%. The addition of BAL Xpert expedited the institution of PTB treatment while having diagnostic yields comparable to those of conventional BAL with TBLB.

CONCLUSIONS

The use of BAL Xpert may obviate the need for TBLB in increasing the diagnostic yield of PTB in sputum-scarce or AFB smear-negative patients.

Minimally invasive carcinosarcoma ex pleomorphic adenoma: A case report and literature review with cytohistological correlation

BACKGROUND

Carcinosarcoma of the salivary glands is a rare neoplasm, and the minimally invasive form constitutes a subgroup with a more favorable prognosis. The cytomorphologic features of this neoplasm can be appreciated on fine-needle aspiration biopsy.

METHODS AND RESULTS

We present a patient with a minimally invasive carcinosarcoma ex non-recurrent pleomorphic adenoma (Ca ex PA) who underwent initial fine-needle aspiration biopsy followed by surgical resection. The tumor was composed predominantly of a light microscopic pleomorphic high-grade sarcoma exhibiting partial myoepithelial immunohistochemical features, with a minor component of in situ and invasive salivary duct carcinoma (10%). A limited area with features of a hyalinized pleomorphic adenoma was identified.

CONCLUSION

This is the third case report of the cytological features of Ca ex PA of the salivary gland, with histologic correlation. It further illustrates the oncogenic relationship between epithelial and myoepithelial elements in the early stages of carcinosarcomatous transformation. © 2016 Wiley Periodicals, Inc. Head Neck 38: E2483-E2489, 2016.

From epistaxis to bone pain-report of two cases illustrating the clinicopathological spectrum of phosphaturic mesenchymal tumour with fibroblast growth factor receptor 1 immunohistochemical and cytogenetic analyses

AIMS

Phosphaturic mesenchymal tumour (PMT) is a rare, recently described neoplastic entity. It is characterized by distinct histological features, which often occur together with oncogenic osteomalacia. Recently, a novel FN1-FGFR1 gene fusion has been described in a subset of PMTs. The aim of this study is to characterise the clinicopathological features of two PMTs, with FGFR1 immunohistochemical and cytogenetic analyses.

METHODS AND RESULTS

We present two contrasting cases of PMT, one occurring in the sinonasal region, and the other occurring in bone (proximal femur). In the former, local effects, including epistaxis and anosmia, dominated the clinical presentation, whereas the latter case presented with refractory bone pain, muscle weakness, and occult osteomalacia, the cause of which was only identified after 2 years. Both tumours showed characteristic histological features of PMT, including a monomorphic proliferation of round to ovoid cells, osteoclast-like multinucleated giant cells, and areas of 'smudgy' basophilic calcifications. Chromogenic in-situ hybridization showed fibroblast growth factor FGF-23 expression by the sinonasal tumour. By using immunohistochemistry, we also demonstrated, for the first time, FGF receptor 1 (FGFR1) protein overexpression in this tumour, for which FN1-FGFR1 gene fusion was not detected by fluorescence in-situ hybridization.

CONCLUSIONS

Our findings indicate that up-regulation of FGFR1 in phosphaturic mesenchymal tumours can occur via mechanisms other than FN1-FGFR1 fusion, raising the possibility of FGFR1 overexpression being a potential common pathway with pathophysiological and therapeutic implications.

Drug sensitivity testing platforms for gastric cancer diagnostics

Gastric cancer diagnostics has traditionally been histomorphological and primarily the domain of surgical pathologists. Although there is an increasing usage of molecular and genomic techniques for clinical diagnostics, there is an emerging field of personalised drug sensitivity testing. In this review, we describe the various personalised drug sensitivity testing platforms and discuss the challenges facing clinical adoption of these assays for gastric cancer.

Hybrid Intercalated Duct Lesion of the Parotid: Diagnostic Challenges of a Recently Described Entity with Fine Needle Aspiration Findings

Intercalated duct lesions (IDL) of the salivary glands are recently described, and encompass both hyperplasia and benign neoplasms that remain incompletely understood. IDLs have been linked to various benign and low-grade malignant salivary gland neoplasms. We herein present a case of a 77 year old woman with an IDL of the parotid composed of both a hyperplastic and an adenomatous component and report, for the first time, the fine needle aspiration findings of such a lesion. This case illustrates the morphologic spectrum of an IDL, as well as challenges in rendering an accurate cytological and histologic diagnosis. The potential diagnostic pitfalls presented by the hybrid pattern of this lesion are also discussed.

MiR-210 is induced by Oct-2, regulates B cells, and inhibits autoantibody production

MicroRNAs (MiRs) are small, noncoding RNAs that regulate gene expression posttranscriptionally. In this study, we show that MiR-210 is induced by Oct-2, a key transcriptional mediator of B cell activation. Germline deletion of MiR-210 results in the development of autoantibodies from 5 mo of age. Overexpression of MiR-210 in vivo resulted in cell autonomous expansion of the B1 lineage and impaired fitness of B2 cells. Mice overexpressing MiR-210 exhibited impaired class-switched Ab responses, a finding confirmed in wild-type B cells transfected with a MiR-210 mimic. In vitro studies demonstrated defects in cellular proliferation and cell cycle entry, which were consistent with the transcriptomic analysis demonstrating downregulation of genes involved in cellular proliferation and B cell activation. These findings indicate that Oct-2 induction of MiR-210 provides a novel inhibitory mechanism for the control of B cells and autoantibody production.

Field reversed configuration confinement enhancement through edge biasing and neutral beam injection

Field reversed configurations (FRCs) with high confinement are obtained in the C-2 device by combining plasma gun edge biasing and neutral beam injection. The plasma gun creates an inward radial electric field that counters the usual FRC spin-up. The n = 2 rotational instability is stabilized without applying quadrupole magnetic fields. The FRCs are nearly axisymmetric, which enables fast ion confinement. The plasma gun also produces E × B shear in the FRC edge layer, which may explain the observed improved particle transport. The FRC confinement times are improved by factors 2 to 4, and the plasma lifetimes are extended from 1 to up to 4 ms.

Dynamic formation of a hot field reversed configuration with improved confinement by supersonic merging of two colliding high-β compact toroids

A hot stable field-reversed configuration (FRC) has been produced in the C-2 experiment by colliding and merging two high-β plasmoids preformed by the dynamic version of field-reversed θ-pinch technology. The merging process exhibits the highest poloidal flux amplification obtained in a magnetic confinement system (over tenfold increase). Most of the kinetic energy is converted into thermal energy with total temperature (T{i}+T{e}) exceeding 0.5 keV. The final FRC state exhibits a record FRC lifetime with flux confinement approaching classical values. These findings should have significant implications for fusion research and the physics of magnetic reconnection.

Neuraminidase-induced thrombocytopenia in mice: effects on thrombopoiesis

Previous studies to examine the effects of thrombocytopenia on thrombopoiesis have generally utilized immune-mediated platelet depletion. We have developed a nonimmune model to exclude the possibility that adverse immune-mediated effects have been misinterpreted as the physiological response to stimulation of thrombopoiesis. Thrombopoiesis was examined in mice after induction of thrombocytopenia with a single injection of the nonimmunologic agent neuraminidase (Ndase). Utilizing electron microscopy, we examined platelets and megakaryocytes (MK) obtained 8, 12, 24, 48, 72, 96, and 120 hr after administration of Ndase. Eight to 48 hr after induction of acute, severe thrombocytopenia (mean platelet count less than 50,000/microliters), the medians of the platelet sectional area distributions, as measured morphometrically, were significantly greater than the median platelet sectional area of pooled controls. The maximum median value for platelet sectional area was observed at 24 hr. The largest platelets in these samples contained more profiles of endoplasmic reticulum and Golgi cisternae, and a lower concentration of surface-connected canalicular system, as compared with normal platelets. By 72 hr post-injection of Ndase, virtually all platelets exhibited normal size and organelle complement. Mean platelet volumes, determined by electrical impedance analysis, paralleled the serial changes in platelet sectional areas. MK frequency and ploidy, measured by two-color fluorescence activated flow cytometry, were unchanged 12 and 24 hr following Ndase. At 48 hr, total MK frequency increased significantly (P less than 0.01) from 0.11% to 0.17%, and MK ploidy distribution shifted with a reduction in 16N MK (P less than 0.005) and an increase in 32N MK (P less than 0.01). MK ploidy was maximally altered from normal at 72 hr with increased 32N MK frequency (32.0%, P less than 0.001) and increased 64N MK frequency (2.4%, P less than 0.005). Morphologic and morphometric examination of MK at all time points did not reveal detectable changes from normal in cytoplasmic appearance or size, respectively. Therefore, we have demonstrated marked alterations of morphology and size of platelets, and of MK ploidy, using this nonimmunologic model. These studies further support our previous observations that megakaryocyte ploidy and platelet volume are independently regulated in response to depletion of the circulating platelet mass, and they show that these changes are not dependent upon the mechanism of thrombocytopenia.

Splenic thrombopoiesis after bone marrow ablation with radiostrontium: a murine model

Murine platelet production is normally supported by high-ploidy bone marrow megakaryocytes without significant contribution from splenic megakaryocytes with predominantly low-ploidy levels. We produced sustained bone marrow ablation using radiostrontium, and examined the processes by which splenic platelet production is initiated and maintained in the absence of bone marrow function. Bone marrow hematopoiesis, measured by total nucleated cell number and viability, megakaryocyte colony-forming cells, and granulocyte-macrophage colony-forming cells, was rapidly ablated in mice by using yttrium 90-free strontium 90. Platelet count declined from normal (1224 x 10(3)/microliters) to a nadir (98 x 10(3)/microliters) 11 days after 90Sr, and then rose to a stable level (705 x 10(3)/microliters) on days 20 through 115. Peripheral leukocyte concentration decreased rapidly and remained below 25% of normal in contrast to hemoglobin levels, which were minimally lowered. Mean spleen weight rose rapidly after 90Sr to 66% above normal. Splenic megakaryocyte frequency, measured by two-color fluorescence-activated flow cytometry, rose from basal levels (0.09% +/- 0.06%) to 0.15% +/- 0.07% (p less than 0.001), total spleen nucleated cells fell to 71% of normal, and the absolute number of spleen megakaryocytes was unchanged. Total spleen megakaryocyte colony-forming cells were not significantly increased above normal whereas total spleen granulocyte-macrophage colony-forming cells increased abruptly after day 13 to 10 times normal levels. Splenectomy after hematopoietic recovery from 90Sr bone marrow ablation resulted in a rapid decline of platelet levels, followed by death. Although the spleen became the sole site of platelet production, the splenic megakaryocyte ploidy distribution was only minimally changed from normal, and the modal ploidy class remained 2N. In contrast to experimental thrombocytopenia in mice with intact bone marrow, in which megakaryocyte ploidy is increased, thrombocytopenia associated with sustained bone marrow ablation does not result in upward regulation of splenic megakaryocyte ploidy as a compensatory mechanism.

Regulation of platelet heterogeneity: effects of thrombocytopenia on platelet volume and density

We have examined the effects of variable degrees of acute thrombocytopenia on platelet levels, mean platelet volume (MPV), and buoyant density after induction of thrombocytopenia by platelet antiserum (PAS) in mice with or without spleens. Mice were studied serially 10-16, 36, 48, 60-64, 84, 108, 144, 180, 228, 276, 348-360, 372, and 516 h after PAS treatment. MPV and platelet count (PC) x 10(6)/microliters for normal intact mice (n = 136) were 4.7 +/- 0.3 fl (SD) and 1.69 +/- 0.52 (SD), respectively. Twelve hours after PAS-induced severe thrombocytopenia (PC less than 0.05 x 10(6)/microliters), MPV increased significantly (p less than 0.01) to 6.4 fl, was maximal at 36 h (8.2 fl), remained elevated until 144 h following PAS treatment, and then returned to normal. Platelet density decreased significantly (p less than 0.05) 64 h after PAS treatment and returned to normal at 144 h. Hematocrits of repeatedly bled intact control mice decreased from 45% to 30%, accompanied by thrombocytosis (maximal PC 2.24 x 10(6)/microliters) without significant changes in either MPV or platelet density. Moderate thrombocytopenia (PC 0.1-0.2 x 10(6)/microliters) in intact mice produced significantly (p less than 0.05) increased MPV, at 5.7 fl 12 h after PAS treatment, with a peak MPV of 7.6 fl (p less than 0.001) at 36 h; MPV returned to normal at 84 h. Platelet density decreased (p less than 0.001) 12 h after PAS treatment and returned to baseline at 228 h. Control splenectomized mice (n = 185) had an MPV of 5.0 fl +/- 0.7 fl and a PC of 2.14 +/- 0.6 x 10(6)/microliters. Comparably severe and moderate thrombocytopenia in splenectomized mice produced alterations in platelet count, MPV, and density similar to those in intact mice, although maximal MPV and the degree of rebound thrombocytosis after severe thrombocytopenia were more marked in splenectomized mice. In response to reduction of the platelet mass in both intact and splenectomized mice, MPV increased in proportion to the severity of thrombocytopenia, occurred as early as 4 h after induction, and persisted during early rebound thrombocytosis. Previous observations that megakaryocyte ploidy did not shift until 48 h after onset of thrombocytopenia confirm that both initial and maximal changes in MPV in response to this stimulus are regulated by processes other than alterations of megakaryocyte DNA levels.(ABSTRACT TRUNCATED AT 400 WORDS)

Enamel fluoride uptake affected by site of application: comparing sodium and amine fluorides

In enamel fluoride uptake studies, the most frequently sampled site is the middle third of the buccal surface. Because different parts of the enamel surface vary in fluoride concentration, the present study investigated fluoride uptake at contrasting sites using two different topical agents. One was a neutral aqueous solution of sodium fluoride containing 2% w/w of fluoride, and the second was an aqueous solution of two amine fluorides containing 1% w/w of fluoride. The enamel of 10 pairs of clinically sound extracted human premolars was etched initially and after treatment with one of these agents on the cervical and middle thirds of the buccal surface and on the proximal surface, yielding the pre- and post-treatment fluoride concentrations of these sites at depths of 5 and 10 microns from the surface. Enamel treated with the amine F solution had significantly higher fluoride uptakes at all sites compared to the NaF-treated specimens. The differences in uptake from the two agents varied with site, being smallest for the buccal middle third enamel and greatest for the proximal enamel. It is suggested that these results relate to possible differences in enamel maturation or to the presence of initial proximal caries, and the greater affinity of amine fluoride for porous enamel. The findings emphasise the importance of obtaining site-specific data in the study of fluoride in enamel.

Measurement of megakaryocyte frequency and ploidy distribution in unfractionated murine bone marrow

Measurement of megakaryocyte frequency, ploidy distribution, and maturation stage have been complicated by the low frequency of megakaryocytes in either bone marrow or spleen. Due to harsh labeling conditions, previous studies utilizing flow cytometry have not quantified cell recovery or megakaryocyte frequency. We have modified our two-color fluorescence-activated cytometric technique in order to identify megakaryocytes in unfractionated murine bone marrow with a fluoresceinated cell surface immunologic probe (heterologous polyclonal platelet antiserum) and to selectively measure megakaryocyte DNA content with propidium iodide using isosmolar conditions. Under these conditions, total nucleated cell recovery from unfractionated normal murine bone marrow, after all preparative procedures, averaged 68.0% +/- 5.0% (SD) with 93.5% +/- 2.0% DNA staining efficiency. Mean megakaryocyte frequency (n = 30) was 0.14% +/- 0.04%. Using both our previously described gating technique with single parameter analysis and our modified dual parameter technique, the modal megakaryocyte ploidy class was 16N. Low ploidy megakaryocytes, 2N and 4N, constituted 9.8% and 10.8%, respectively, of the total megakaryocyte population. Analysis of the megakaryocyte population with respect to cell surface fluorescence intensity demonstrated that the dimly fluorescent population contained an increased proportion of lower ploidy class cells (2N + 4N + 8N) compared with brightly fluorescent cells, which contained an increased proportion of higher ploidy cells (16N + 32N). Our modifications of the two-color technique yielded improved recovery of total nucleated bone marrow cells from unfractionated bone marrow and provided more precise measurements of megakaryocyte frequency and ploidy than previously available.

Regulation of thrombopoiesis: effects of the degree of thrombocytopenia on megakaryocyte ploidy and platelet volume

We have established a murine model and techniques with which to serially study thrombocytopoiesis after induction of experimental immune thrombocytopenia of variable severity and duration. Bone marrow megakaryocyte ploidy distribution was determined by using unfractionated bone marrow, a polyclonal megakaryocyte-specific probe, and two-color, fluorescence-activated flow cytometry. With these techniques, the modal megakaryocyte ploidy class in normal murine bone marrow was 16N. Serial studies of bone marrow megakaryocyte ploidy after the induction of acute, severe thrombocytopenia (platelet count, less than 0.05 X 10(6) microL) demonstrated no detectable change in the ploidy distribution at 12, 24, and 36 hours after the onset of thrombocytopenia. At 48 hours, the modal ploidy class shifted from 16N to 32N, and the 64N class increased significantly (P less than .001). The ploidy distribution returned to normal 120 hours after the onset of thrombocytopenia. A lesser degree of thrombocytopenia (platelet count reduction to 0.100 to 0.200 X 10(6)/microL) delayed the modal ploidy class shift from 16N to 32N until 72 hours after the onset of thrombocytopenia. Chronic, severe thrombocytopenia (platelet count, less than 0.05 X 10(6)/microL for seven days) resulted in a modal ploidy class shift from 16N to 32N during the thrombocytopenic phase and an enhanced increase in the 64N megakaryocyte class during the recovery phase. Mean platelet volume (MPV) was simultaneously measured on isolated total platelet populations after induction of thrombocytopenia. MPV was significantly increased (P less than .001) as early as eight hours after the onset of acute, severe thrombocytopenia, 40 hours before a shift in the ploidy distribution. Mild thrombocytopenia (platelet count reduction to 0.400 X 10(6)/microL) was not associated with a ploidy shift but did result in a significantly increased MPV (P less than .001). These studies demonstrate that the temporal relationship and magnitude of the effects of thrombocytopenia upon megakaryocyte ploidy distribution are dependent upon the degree and the duration of the thrombocytopenic stimulus and that the effects of experimental thrombocytopenia on platelet volume and megakaryocyte ploidy are dissociated.