Large tandem duplications in cancer result from transcription and DNA replication collisions

Despite the abundance of somatic structural variations (SVs) in cancer, the underlying molecular mechanisms of their formation remain unclear. Here, we use 6,193 whole-genome sequenced tumors to study the contributions of transcription and DNA replication collisions to genome instability. After deconvoluting robust SV signatures in three independent pan-cancer cohorts, we detect transcription-dependent replicated-strand bias, the expected footprint of transcription-replication collision (TRC), in large tandem duplications (TDs). Large TDs are abundant in female-enriched, upper gastrointestinal tract and prostate cancers. They are associated with poor patient survival and mutations in TP53, CDK12, and SPOP. Upon inactivating CDK12, cells display significantly more TRCs, R-loops, and large TDs. Inhibition of G2/M checkpoint proteins, such as WEE1, CHK1, and ATR, selectively inhibits the growth of cells deficient in CDK12. Our data suggest that large TDs in cancer form due to TRCs, and their presence can be used as a biomarker for prognosis and treatment.

Single-cell genotypic and phenotypic analysis of measurable residual disease in acute myeloid leukemia

Measurable residual disease (MRD), defined as the population of cancer cells that persist following therapy, serves as the critical reservoir for disease relapse in acute myeloid leukemia and other malignancies. Understanding the biology enabling MRD clones to resist therapy is necessary to guide the development of more effective curative treatments. Discriminating between residual leukemic clones, preleukemic clones, and normal precursors remains a challenge with current MRD tools. Here, we developed a single-cell MRD (scMRD) assay by combining flow cytometric enrichment of the targeted precursor/blast population with integrated single-cell DNA sequencing and immunophenotyping. Our scMRD assay shows high sensitivity of approximately 0.01%, deconvolutes clonal architecture, and provides clone-specific immunophenotypic data. In summary, our scMRD assay enhances MRD detection and simultaneously illuminates the clonal architecture of clonal hematopoiesis/preleukemic and leukemic cells surviving acute myeloid leukemia therapy.

Oncogenic IDH1 Mutation Imparts Therapeutically Targetable Metabolic Dysfunction in Multiple Tumor Types

SUMMARY

In this issue of Cancer Discovery, Thomas and colleagues leverage mass spectrometry metabolomics, stable isotope labeling, and functional studies to explore metabolic vulnerabilities in cancers harboring mutations in isocitrate dehydrogenase (IDH). The authors present compelling data to support the claim that dysregulated lipid synthesis underpins a synthetic lethal target in cancers with IDH1, but not IDH2, mutations. See related article by Thomas et al., p. 496 (9).

Distinct and opposite effects of leukemogenic Idh and Tet2 mutations in hematopoietic stem and progenitor cells

Mutations in IDH1, IDH2, and TET2 are recurrently observed in myeloid neoplasms. IDH1 and IDH2 encode isocitrate dehydrogenase isoforms, which normally catalyze the conversion of isocitrate to α-ketoglutarate (α-KG). Oncogenic IDH1/2 mutations confer neomorphic activity, leading to the production of D-2-hydroxyglutarate (D-2-HG), a potent inhibitor of α-KG-dependent enzymes which include the TET methylcytosine dioxygenases. Given their mutual exclusivity in myeloid neoplasms, IDH1, IDH2, and TET2 mutations may converge on a common oncogenic mechanism. Contrary to this expectation, we observed that they have distinct, and even opposite, effects on hematopoietic stem and progenitor cells in genetically engineered mice. Epigenetic and single-cell transcriptomic analyses revealed that Idh2^R172K and Tet2 loss-of-function have divergent consequences on the expression and activity of key hematopoietic and leukemogenic regulators. Notably, chromatin accessibility and transcriptional deregulation in Idh2^R172K cells were partially disconnected from DNA methylation alterations. These results highlight unanticipated divergent effects of IDH1/2 and TET2 mutations, providing support for the optimization of genotype-specific therapies.

Immunotherapeutic Targeting and PET Imaging of DLL3 in Small-Cell Neuroendocrine Prostate Cancer

Effective treatments for de novo and treatment-emergent small-cell/neuroendocrine (t-SCNC) prostate cancer represent an unmet need for this disease. Using metastatic biopsies from patients with advanced cancer, we demonstrate that delta-like ligand 3 (DLL3) is expressed in de novo and t-SCNC and is associated with reduced survival. We develop a PET agent, [89Zr]-DFO-DLL3-scFv, that detects DLL3 levels in mouse SCNC models. In multiple patient-derived xenograft models, AMG 757 (tarlatamab), a half-life-extended bispecific T-cell engager (BiTE) immunotherapy that redirects CD3-positive T cells to kill DLL3-expressing cells, exhibited potent and durable antitumor activity. Late relapsing tumors after AMG 757 treatment exhibited lower DLL3 levels, suggesting antigen loss as a resistance mechanism, particularly in tumors with heterogeneous DLL3 expression. These findings have been translated into an ongoing clinical trial of AMG 757 in de novo and t-SCNC, with a confirmed objective partial response in a patient with histologically confirmed SCNC. Overall, these results identify DLL3 as a therapeutic target in SCNC and demonstrate that DLL3-targeted BiTE immunotherapy has significant antitumor activity in this aggressive prostate cancer subtype.

SIGNIFICANCE

The preclinical and clinical evaluation of DLL3-directed immunotherapy, AMG 757, and development of a PET radiotracer for noninvasive DLL3 detection demonstrate the potential of targeting DLL3 in SCNC prostate cancer.

Role of Tetra Amino Acid Motif Properties on the Function of Protease-Activatable Viral Vectors

Protease-activatable viruses (PAV) based on adeno-associated virus have previously been generated for gene delivery to pathological sites characterized by elevated extracellular proteases. "Peptide locks", composed of a tetra-aspartic acid motif flanked by protease cleavage sequences, were inserted into the virus capsid to inhibit virus-host cell receptor binding and transduction. In the presence of proteases, the peptide locks are cleaved off the capsid, restoring the virus' ability to bind cells and deliver cargo. Although promising, questions remained regarding how the peptide locks prevented cell binding. In particular, it was unclear if the tetra-amino acid (4AA) motif blocks receptor binding via electrostatic repulsion or steric obstruction. To explore this question, we generated a panel of PAVs with lock designs incorporating altered 4AA motifs, each wielding various chemical properties (negative, positive, uncharged polar, and hydrophobic) and characterized the resultant PAV candidates. Notably, all mutants display reduced receptor binding and decreased transduction effciency in the absence of proteases, suggesting simple electrostatics between heparin and the D4 motif do not play an exclusive role in obstructing virus-receptor binding. Even small hydrophobic (A4) and uncharged polar (SGGS) motifs confer a reduction in heparin binding compared to the wild type. Furthermore, both uncharged polar N4 and Q4 mutants (comparable in size to the D4 and E4 motifs respectively, but lacking the negative charge) demonstrate partial ablation of heparin binding. Collectively, these results support a possible dual mechanism of PAV lock operation, where steric hindrance and electrostatics make nonredundant contributions to the disruption of virus-receptor interactions. Finally, because of high virus titer production and superior capsid stability, only the negatively charged 4AA motifs remain viable design choices for PAV construction. Future studies probing the structure-function relationship of PAVs will further expand its promise as a gene delivery vector able to target diseased tissues exhibiting elevated extracellular proteases.

Robust cross-links in molluscan adhesive gels: testing for contributions from hydrophobic and electrostatic interactions

The cross-linking interactions that provide cohesive strength to molluscan adhesive gels were investigated. Metal-based interactions have been shown to play an important role in the glue of the slug Arion subfuscus (Draparnaud), but other types of interactions may also contribute to the glue's strength and their role has not been investigated. This study shows that treatments that normally disrupt hydrophobic or electrostatic interactions have little to no effect on the slug glue. High salt concentrations and non-ionic detergent do not affect the solubility of the proteins in the glue or the ability of the glue proteins to stiffen gels. In contrast, metal chelation markedly disrupts the gel. Experiments with gel filtration chromatography identify a 40 kDa protein that is a central component of the cross-links in the glue. This 40 kDa protein forms robust macromolecular aggregations that are stable even in the presence of high concentrations of salt, non-ionic detergent, urea or metal chelators. Metal chelation during glue secretion, however, may block some of these cross-links. Such robust, non-specific interactions in an aqueous environment are highly unusual for hydrogels and reflect an intriguing cross-linking mechanism.

Macaques co-immunized with SIVgag/pol-HIVenv and IL-12 plasmid have increased cellular responses

BACKGROUND

The cell mediated immune profiles following immunization with a recombinant DNA vaccine was assessed in the simian-human immunodeficiency virus (SHIV) and Macaque model. Earlier work demonstrated increased numbers of antigen specific CD8 and CD4 effector cells able to secrete IFN-gamma.

METHOD

The vaccine strategy included co-immunization of a DNA based vaccine alone or in combination with a macaque IL-12 expressing plasmid (pmacIL12). Antigen activated lymphocytes were studied for activation of a set of immunological molecules.

RESULTS

The current study demonstrates lymphocytes isolated and activated from the group that was immunized with DNA and pmacIL12 had a higher level of IFN-gamma producing cells. We also observed a different immunological profile when comparing the cells isolated from macaques immunized with DNA as compared to those animals that also received pmacIL12.

CONCLUSION

The observed immune profiles are reflective of the co-delivery of pmacIL12 and demonstrates that IL-12 can increase the magnitude and polyfunctionality of the cellular immune response.

Spontaneous resolution of carotid stenosis--a case for routine preoperative duplex ultrasound

Spontaneous resolution of carotid stenosis has not been previously reported in the context of preoperative duplex ultrasound scanning, although it has been described as a recognizable phenomenon in the past. We report a case in whom significant carotid stenosis was noted at the time of listing for surgery on both duplex ultrasound and MRA. On preoperative imaging there was resolution of the lesion and surgery was avoided. This case emphasises that spontaneous resolution of carotid stenosis can occur and that preoperative duplex is useful as a prelude to surgery and can prevent unwarranted intervention.

Targeted antigen delivery to antigen-presenting cells including dendritic cells by engineered Fas-mediated apoptosis

Immunity to tumors as well as to viral and bacterial pathogens is often mediated by cytotoxic T lymphocytes (CTLs). Thus, the ability to induce a strong cell-mediated immune response is an important requirement of novel immunotherapies. Antigen-presenting cells (APCs), including dendritic cells (DCs), are specialized in initiating T-cell immunity. Harnessing this innate ability of these cells to acquire and present antigens, we sought to improve antigen presentation by targeting antigens directly to DCs in vivo through apoptosis. We engineered Fas-mediated apoptotic death of antigen-bearing cells in vivo by co-expressing the immunogen and Fas in the same cell. We then observed that the death of antigen-bearing cells results in increased antigen acquisition by APCs including DCs. This in vivo strategy led to enhanced antigen-specific CTLs, and the elaboration of T helper-1 (Th1) type cytokines and chemokines. This adjuvant approach has important implications for viral and nonviral delivery strategies for vaccines or gene therapies.

Dietary creatine supplementation does not affect some haematological indices, or indices of muscle damage and hepatic and renal function

BACKGROUND

The use of creatine (Cr) as a nutritional supplement to aid athletic performance has gained widespread popularity among athletes. However, concerns have recently been expressed over potentially harmful effects of short and long term Cr supplementation on health.

METHODS

Forty eight young healthy subjects were randomly allocated to three experimental protocols aimed at elucidating any potential health risks associated with five days (20 g/day) to nine weeks (3 g/day) of Cr supplementation. Venous blood samples were collected before and after periods of Cr supplementation and were analysed for some haematological indices, and for indices of hepatic, muscular, and renal dysfunction.

FINDINGS

All measured indices were well within their respective normal range at all times. Serum creatinine concentration tended to be increased the day after Cr supplementation. However, values had returned to baseline six weeks after the cessation of supplementation. These increases were probably attributable to increased creatinine production rather than renal dysfunction. No indication of impairment to the haematological indices measured, hepatic function, or muscle damage was apparent after Cr supplementation.

INTERPRETATION

These data provide evidence that there are no obvious adverse effects of acute or more chronic Cr supplementation on the haematological indices measured, nor on hepatic, muscle, and renal function. Therefore there is no apparent health risk associated with Cr supplementation to healthy people when it is ingested in quantities that have been scientifically proven to increase muscle Cr stores.

Cultural diversity and transcultural nursing as they impact health care

This article examines and critiques what can be broadly defined as "culturally sensitive nursing practice." The authors argue that both past and present research on culturally sensitive nursing practice, regardless of which branch of such practice it subscribes to (transcultural, cross-cultural, multicultural, intercultural, international, and so forth), is not sufficiently based in a sociopolitical context. As a result, there is not significant positive improvement in health care outcomes for patients from traditionally under-represented social membership groups (i.e., groups based on race, gender, socioeconomic class, etc.). Realizing sincere and affective culturally sensitive nursing practice is contingent upon the development and implementation of a comprehensive, sociopolitically conceptualized multicultural nursing education curriculum and pedagogy.

Cytokine and Eicosanoid Production by Cultured Human Monocytes Exposed to Titanium Particulate Debris

: Phagocytosis of particulate wear debris from arthroplasties by macrophages induces an inflammatory response that has been linked to implant loosening and premature failure of artificial joints. Inflammatory mediators released by phagocytic macrophages such as tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), interleukin-6 (IL-6), and prostaglandin E(2) (PGE(2)) are believed to play a central role in the pathogenesis of aseptic loosening. The objective of this study was to characterize titanium alloy particulates that closely match wear debris found around joint arthroplasties and to study their effects on the biosynthesis of inflammatory mediators by cultured monocytes. Peripheral blood monocytes were isolated from healthy human volunteers. Monocytes were cultured in 96-well plates for 24 h, washed, and exposed to three concentrations of titanium particulates and controls from 18-24 h. Supernatants were assayed for TNF-alpha, IL-1beta, IL-6, and PGE(2) activity. Energy dispersive X-ray spectroscopy (EDX) verified the titanium alloy to be Ti6A14V. Scanning electron microscopy (SEM) analysis showed significant titanium particulate heterogeneity with approximately 95% of the particles <1 µm in diameter. SEM and EDX technology was useful in the characterization of the titanium particulates utilized for in vitro models of titanium-induced cytokine release by monocytes. Incubation of titanium particulates (in concentrations similar to those found around loosened prosthetic joints) with cultured monocytes significantly increased their production of TNF-alpha, IL-1beta, and PGE(2).

Role of submaximal exercise in promoting creatine and glycogen accumulation in human skeletal muscle

We examined the effect of glycogen-depleting exercise on subsequent muscle total creatine (TCr) accumulation and glycogen resynthesis during postexercise periods when the diet was supplemented with carbohydrate (CHO) or creatine (Cr) + CHO. Fourteen subjects performed one-legged cycling exercise to exhaustion. Muscle biopsies were taken from the exhausted (Ex) and nonexhausted (Nex) limbs after exercise and after 6 h and 5 days of recovery, during which CHO (CHO group, n = 7) or Cr + CHO (Cr+CHO group, n = 7) supplements were ingested. Muscle TCr concentration ([TCr]) was unchanged in both groups 6 h after supplementation commenced but had increased in the Ex (P < 0.001) and Nex limbs (P < 0.05) of the Cr+CHO group after 5 days. Greater TCr accumulation was achieved in the Ex limbs (P < 0.01) of this group. Glycogen was increased above nonexercised concentrations in the Ex limbs of both groups after 5 days, with the concentration being greater in the Cr+CHO group (P = 0.06). Thus a single bout of exercise enhanced muscle Cr accumulation, and this effect was restricted to the exercised muscle. However, exercise also diminished CHO-mediated insulin release, which may have attenuated insulin-mediated muscle Cr accumulation. Ingesting Cr with CHO also augmented glycogen supercompensation in the exercised muscle.

Perinatal substance abuse: working with neonates and families

ACCORDING TO A NATIONAL survey on drug use during pregnancy, more than 5 percent of all neonates are exposed to illicit substancesin utero.1Five percent of births may not seem significant, but it represents 221,000 affected neonates each year. Cocaine and marijuana are the most frequently used illicit substances. In addition to illegal substances, we must also be concerned about the use of legal substances that can adversely affect the fetus—specifically, alcohol and tobacco. Annually, about 20 percent of fetuses are exposed to tobacco, which can adversely affect growth and result in an increased risk for low birth weight.1,2Additionally, approximately 20 percent of neonates are exposed to alcohol, a known teratogen.1,3

A comparison of transdermal fentanyl versus epidural morphine for analgesia in dogs undergoing major orthopedic surgery

Postoperative analgesia provided by transdermal fentanyl was compared with that provided by epidural morphine in dogs undergoing major orthopedic surgery. Dogs randomly were assigned to receive either a 100 microg per hour transdermal fentanyl patch 24 hours prior to surgery (n=8) or epidural morphine (0.1 mg/kg body weight) administered following induction of anesthesia (n=10). Temperature, heart rate, respiratory rate, and pain score were recorded prior to surgery and zero, six, 18, 30, and 42 hours after surgery. Blood samples were collected from the dogs in the transdermal fentanyl group beginning 24 hours preoperatively to 42 hours postoperatively. Fentanyl concentrations were determined by radioimmunoassay. When all time periods after surgery were combined, dogs in the transdermal fentanyl group were experiencing significantly less pain after surgery than dogs given epidural morphine. The transdermal fentanyl provided analgesia after major orthopedic surgery greater than or equivalent to that of epidural morphine.

MRI appearance of clear cell hidradenoma

We present the first reported MR imaging findings of a histologically proven clear cell hidradenoma. A fluid level was noted on all pulse sequences in this lesion, which demonstrated a prominent hemorrhagic component on sectioning. The presence of an enhancing nodule was also noted, differentiating this lesion from a post-traumatic hematoma. Fluid levels in a well-defined subcutaneous soft tissue mass should suggest the possibility of a hidradenoma.

Clinically inapparent tuboovarian actinomycosis in a woman with an IUD. A case report

BACKGROUND

The consequences and management of asymptomatic Actinomyces-like organisms detected on cervical cytologic smears continue to be controversial.

CASE

A unilateral tuboovarian actinomycotic abscess was discovered in a woman who had undergone a hysterectomy for uterine leiomyomas. She had had an intrauterine device in place for many years without any symptoms of pelvic inflammatory disease.

CONCLUSION

Ascending infection of the upper genital tract by Actinomyces may be clinically inapparent. When Actinomyces-like organisms aer detected on cervical cytologic smears, removal of an intrauterine device should be considered.

Malignant mesenchymoma associated with an unusual vasoinvasive metastasis in a dog

A case of a malignant mesenchymoma with an unusual, vasoinvasive, metastatic behavior in a three-year-old, intact female basset hound is presented. Malignant mesenchymomas are rare neoplasms in humans and in dogs. No previous reports of a malignant mesenchymoma with vasoinvasive metastasis in the dog were found in the literature. The constituent neoplasms are discussed in relation to reports in the human and veterinary literature, and a potential etiology for this unique presentation is hypothesized.

Specific immune induction following DNA-based immunization through in vivo transfection and activation of macrophages/antigen-presenting cells

The initiation of an adaptive immune response requires Ag presentation in combination with the appropriate activation signals. Classically, Ag presentation and immune activation occur in the lymph node and spleen, where a favorable organ architecture and rich cellular help can enhance the process. Recently, several investigators have reported the use of DNA expression cassettes to elicit cellular and humoral immunity against diverse pathogens. Although the immune mechanisms involved are still poorly understood, plasmid inoculation represents a model system for studying immune function in response to invading pathogens. In this report, we demonstrate the presence of activated macrophages or dendritic cells in the blood lymphocyte pool and peripheral tissues of animals inoculated with DNA expression cassettes. These cells are directly transfected in vivo, present Ag, and display the surface proteins CD80 and CD86. Our studies indicate that these cells function as APC and can activate naive T lymphocytes. They may represent an important first step APC in genetic immunization and natural infection.

Applying research in the NICU

It is important for all nurses to apply research findings to their practice. Research is a powerful tool, and it is essential that NICU nurses use it to substantiate our actions. When we do, we empower ourselves to advocate for better care for our special patients and their families.

Educational consortiums for NICU staff

Remember that forced change can provide opportunities for creative endeavors. Take the initiative to contact your colleagues and identify potential collaborative projects. The temporary alliances formed for an educational consortium may develop into other exciting joint ventures.

A transputer-based physiological signal processing system. Part 2--System testing and investigation of flow through models of very small arterial stenoses

This paper describes the performance testing of a novel transputer-based physiological digital signal processing (DSP) unit and its application in the interpretation of pulsed Doppler ultrasound signals, obtained from models of arterial stenoses. The first test used the DSP unit as a stand-alone spectrum analyser using (1) sinusoidal frequencies (50 Hz to 10 kHz) and (2) filtered white noise (centre frequency 3 kHz, bandwidth 2.5 kHz). For the second test, the DSP unit was attached to a 30-channel multi-gate Doppler ultrasound scanner (transmitting a 4.8 MHz pulse with a repetition frequency of 4.8 kHz) and a vessel tracking unit. The Doppler ultrasound signals obtained from steady flow (100-600 ml/min) in a rigid acrylic tube (internal diameter 6 mm) were then analyzed by the DSP unit and a commercially available system. Lastly, an in vitro investigation into the flow disturbances around very small stenoses (2-25% cross-sectional area reduction), using steady flow (100-600 ml/min), was undertaken. The results indicated that the system was capable of detecting stenoses as small as 5% cross-sectional area reduction.

Automated large-core needle biopsy of surgically removed breast lesions: comparison of samples obtained with 14-, 16-, and 18-gauge needles

PURPOSE

To determine the needle size that would consistently enable the pathologist to correctly diagnose tissue core biopsy specimens.

MATERIALS AND METHODS

Fifty-seven surgically removed mass lesions of the breast were sampled with a short-throw automated biopsy gun and an 18-gauge needle first, followed by a 16- and a 14-gauge needle. Samples were evaluated independently by three pathologists, and findings were compared with the final diagnosis made at surgical excision biopsy.

RESULTS

The sensitivity for the diagnosis of all 26 malignant lesions was 100%, 92%, and 65% for biopsy samples obtained with 14-, 16-, and 18-gauge needles, respectively. Specificity for malignancy was 100% for all three needle sizes. All of the benign diseases were correctly diagnosed in samples obtained with all three size needles except for two samples that did not survive processing.

CONCLUSION

Biopsy samples obtained with a 14-gauge needle provide the most accurate diagnosis, which correlates with the diagnosis made with the surgical excision biopsy technique.

A transputer-based physiological signal processing system. Part 1--System design

This paper, the first of two, details the design and in-vitro testing of a transputer-based physiological signal processing system. The heart of the system is a transputer-based digital signal processing (DSP) board which can act as a stand-alone spectrum analyser, designed to operate in the audio-frequency band up to 25 kHz. The board comprises a T800 processor, two A100 transversal filters, 12 bit A-D circuitry capable of sampling up to 48 kHz, memory and address mapper. The initial application of the system is for the detection of early arterial disease. For this the DSP board is harnessed to the front end of a multigate pulsed Doppler ultrasound scanner operating at 4.8 MHz insonation frequency and incorporating a vessel wall tracking unit. The complete system performs a Fourier transform on the backscattered signals, providing spectral information on discrete areas of flow (0.6 mm3) across the vessel lumen in real time. This first paper describes the hardware, and the second describes the performance testing of the system on the bench and an assessment of its ability to detect low grade stenoses during steady flow.

Blockade of digestion by famotidine pretreatment does not interfere with the opioid-enhancing effect of ingested amniotic fluid

Ingestion of placenta or amniotic fluid by rats has been shown to enhance ongoing opioid-mediated antinociception, but does not, by itself, produce antinociception. This enhancement is produced by an active substance(s) in placenta and amniotic fluid that we have termed POEF for placental opioid-enhancing factor. Previous research has shown that enhancement requires mediation by the gastrointestinal system: gastric vagotomy blocks enhancement produced by ingested placenta; amniotic fluid injected SC or IP does not produce enhancement. The present study was designed to distinguish between two possible explanations for the blockade of the POEF effect produced by gastric vagotomy: that afferent information arising in vagal gastric receptors conveys the critical information to the CNS, or that disruption of vagal efferent action on digestion blocks the manufacture or activation of the POEF molecule in the gut. Famotidine is an H2-histamine receptor antagonist that reduces gastric acid and pepsin secretion to an extent at least as great as gastric vagotomy. Rats treated with either famotidine or a vehicle were fed placenta or a control substance, then stimulated with vaginal/cervical probing to produce antinociception that is partly opioid mediated. Famotidine did not block POEF enhancement of vaginal/cervical stimulation-induced analgesia in a tail flick latency test. These results suggest that enhancement by POEF does not require normal digestive processes or other processes inhibited by famotidine.

Detection of early atherosclerosis by analysis of ultrasonic Doppler signals produced by mural flow disturbances

The paper describes an in vitro study using a multi-gate Doppler ultrasound system to investigate flow disturbances in a blood analogue caused by small stenoses (2-25% cross-sectional area reduction), using steady flow (100-600 ml min-1) in a 6 mm diameter rigid artery model. The results indicate that stenoses greater than 5% were detectable.

Effect of extracorporeal membrane oxygenation on platelets in newborns

OBJECTIVES

To examine the effect of extracorporeal membrane oxygenation (ECMO) therapy on platelet function and number and to determine the in vivo survival of transfused platelets during ECMO.

DESIGN

Prospective study of all neonates treated with ECMO during a 6-month period.

SETTING

Neonatal intensive care unit in a tertiary referral center.

PATIENTS

Ten infants, < 1 wk of age, with respiratory failure requiring ECMO.

INTERVENTIONS

None.

MEASUREMENTS

Platelet counts were measured at timed intervals to determine the effect of ECMO on platelet counts. The change in platelet counts after transfusion was also measured. Whole blood platelet aggregation studies were performed to determine the effect of ECMO on platelet function.

MAIN RESULTS

A mean decrease of 26% from the baseline platelet count was found 15 mins after the initiation of ECMO, with an additional mean decrease of 16% by the end of 1 hr (p < .05). Fifteen minutes after platelet transfusions, a 17% mean increase in platelet counts was measured (p < .05). One hour after platelet transfusion, the platelet count had decreased to pretransfusion values. Platelet aggregation studies 15 mins after starting ECMO showed a 46% mean decrease in the response to collagen from baseline (p > .05), and a significantly (p < .05) reduced response to ristocetin and to adenosine 5'-diphosphate. Platelet adenosine triphosphate release was also significantly reduced. Single-unit platelet transfusions failed to correct platelet aggregation abnormalities. Resolution of platelet aggregation abnormalities and normalization of platelet counts occurred 8 hrs off ECMO.

CONCLUSIONS

The results of these studies show that qualitative and quantitative platelet changes occur while a neonate is receiving ECMO. The survival rate of transfused platelets is reduced, and the acquired platelet dysfunction is not reversed by the transfusion of platelets with normal function while the patient is receiving ECMO.