Marrow Blood Flow Research Articles

Effects of aging and exercise training on bone and marrow blood flow and vascular function

Effects of aging and exercise training on bone and marrow blood flow and vascular function

Cytogenetic, Clinical, Hematologic, Demographic, Immunohistochemical, and Flow Cytometry Characteristics of Patients with Plasma Cell Neoplasm in Five Years: A First Report from Iran.

The aggregation of clonal plasma cells causes plasma cell neoplasms, which vary in severity and clinical outcomes. The present research focused on the epidemiological, clinical, immunologic, and cytogenetic characteristics of plasma cell neoplasms. In this five-year retrospective cross-sectional study, demographic information such as age and sex, calcium elevation, renal insufficiency, anemia, and bone lesion (CRAB) characteristics, as well as laboratory data including bone marrow and peripheral blood film results, immunohistochemistry, flow cytometry, and cytogenetic study outcomes were collected at Shiraz University of Medical Sciences, Shiraz, Iran. The collected data were analyzed using SPSS Statistics software (version 20.0). Descriptive statistics were reported as numbers, percentages, and mean±SD. 417 newly diagnosed plasma cell neoplasm patients were confirmed by bone marrow or other tissue biopsy tests. 279 patients were men (66.9%). The most prevalent age group was 60-64 years old (18.46%). Plasma cell myeloma (PCM) affected 355 (85.13%) patients, while monoclonal gammopathy of undetermined significance (MGUS) affected 6 (1.43%) patients. Solitary plasmacytoma was seen in 56 (13.42%) patients. At the time of diagnosis, 119 (33.52%) of 355 PCM patients were asymptomatic, whereas 236 (66.47%) patients had at least one CRAB symptom, 55 (15.49%) had two or more, and 14 (3.94%) had three or more. There were 7 (1.97%) cases of amyloidosis. Cytogenetic abnormalities were found in 51.28% (40/78) of the patients. Twenty-one individuals (52.5%) were hyperdiploid with multiple trisomy, while 19 (47.50%) were not. When diagnosed, Iranian PCM patients might have more advanced disease. PCM was more prevalent in young adults, and hyperdiploid was the most common cytogenetic finding in this investigation.

Phase I First-in-Human Study on the Feasibility, Safety, and Antitumor Activity of CD4-Redirected Chimeric Antigen Receptor (CAR) T-Cell Therapy in Patients with CD4+ T-Cell Malignancies (TCM)

Background TCM are aggressive diseases with poor outcomes. Translating the CAR T-cell therapy success from B-cell diseases to TCM has proven challenging. CD4 is an attractive therapeutic target, owing to its restricted expression on normal tissues. In this first-in-human phase I study, we investigate the autologous third generation CD4-redirected CAR T-cell safety, tolerability, manufacturing feasibility, trafficking and preliminary efficacy in patients with R/R CD4+ TCM who failed standard therapies. Methods The investigational construct is engineered with a single-chain variable fragment (ScFV) and dual co-stimulators (CD28; 4-1BB), fused to CD3zeta and CD8 leader sequence, packaged in lentivirus and transducer into T-cells. Patients received conditioning therapy with fludarabine and cyclophosphamide. CD4CAR product is administered in a 3+3 dose-escalation scheme. Dose-limiting toxicities (DLT) were monitored during the initial 42-days post-treatment. Treatment-emergent adverse events (AE) were graded by CTCAE v5.0 Results Three patients with median age of 63 years (range, 18-68) were enrolled and treated at DL1 (2.0x10^5/kg), including 2 (66%) women and 2 (66%) African-American. Median number of prior therapies was 3 (range, 2-4) (Figure). AEs included grade 3-4 hematologic toxicity in 3 (100%) patients, all present before enrollment. There was no protocol defined DLTs. All grade ≥3 lymphopenia reverted to grade 2 by day 30 and no related infections occurred between CAR infusion and hematopoietic stem cell transplantation (HSCT). Since infusion, the CAR T-cells percentage in peripheral blood had continued to expand. CD4CAR T-cells were detectable in all patients for at least 28 days post-infusion, meeting the primary endpoint, and on D111 in one patient. CD4CAR expansion was reflected on by a decrease in CD4/CD8 ratio and flow cytometry using ScFV Fab2 specific antibodies (Figure). Cytokine response analysis CD4CAR was associated with variable but significant production that seems to correlate with clinical responses (Figure; More data at meeting). No cytokine-mediated organ toxicities were observed. Bone marrow and peripheral blood flow cytometry confirmed complete remission (CR) in 2 patients at day 30 (PTCL and T-ALL). Patient 3 (mycosis fungoides) achieved hematological CR with stable skin lesions. Post-treatment day 30 skin biopsy demonstrated persistent disease with marked loss of CD4. Conclusions CD4CAR T-cell therapy is feasible in patients with R/R CD4+ TCM. 2/3 patients achieved CR and the third achieved hematological CR with stable skin disease. Toxicities were manageable without DLT upon completion of cohort 1. The cytokine response suggests immune activation and tumor recognition by CD4CAR T-cells. Dose escalation will proceed. NCT03829540

Expression of Tie2 (angiopoietin receptor) on the monocyte subpopulations from ischemic stroke patients: Histological and flowcytometric studies.

Different subpopulations of monocytes play roles in phagocytosis, inflammation, and angiogenic processes e.g., Tie2-expressing monocytes (TEMs). The brain is flooded with macrophages that are derived from monocytes within 3-7 days after a stroke. This study aimed to determine the expression level of Tie2 (an angiopoietin receptor) on monocytes and their subpopulations in ischemic stroke patients using the histological and immunohistological study of bone marrow biopsies and blood flow cytometry examination. Ischemic stroke patients within two days were selected. Participants in the control group were healthy volunteers of matched age and gender. Sample collection was performed within 24 to 48 hours after medical consultants confirmed the stroke diagnosis. An iliac crest bone marrow biopsy was obtained and fixed for histological and immunohistological staining with antiCD14 and antiCD68. Flow cytometry was used to determine the total monocyte population, monocyte subpopulations, and TEMs after staining with monoclonal antibodies to CD45, CD14, CD16, and Tie2. Post-stroke patients' bone marrow cells were hypercellular. There was an apparent increase in CD68 and CD14-positive cells. Ischemic stroke patients exhibited low percentages of nonclassical monocytes CD14lowCD16++, with an increase in intermediate monocytes CD14highCD16+. Moreover, ischemic stroke patients had significantly higher levels of TEMs than control group. The results of this study demonstrate dysregulation of angiogenesis in monocyte subsets in ischemic stroke patients, which could be used as an early diagnostic marker of neurovascular damage and may need angiogenic therapy or improved medications to prevent further damage of blood vessels.

Can the Left Internal Mammary Artery Be Used During Coronary Artery Bypass Graft Surgery in Patients Undergoing Bone Marrow Transplant? A First Case Report

Introduction: With the improvements in neoplasm treatments and the increased survival of patients with neoplastic diseases, we have entered a new era of having to deal with the complications of senile patients. The issue of bone fusion or the side effects of its delay, such as malunion or infections, are among the concerns for any surgery in patients whose bone marrow is affected by treatment or whose bone marrow blood flow is impaired. The left internal mammary artery (LIMA) is used for coronary artery bypass graft (CABG) surgery with its 2 - 3 times longer lifespan compared to saphenous vein grafts, but its harvest from the sternum affects the sternum blood flow and the outcome of its use is still not identified in patients undergoing bone marrow transplant. This case report is the first report on this issue. Case Presentation: A 60-year-old man with diffuse large B cell lymphoma who had undergone bone marrow transplant a year before had then developed chest pain, which was diagnosed as vessel disease; he was selected for CABG surgery. The LIMA was harvested during the surgery and the left anterior descending artery (LAD) was anastomosed. The saphenous vein graft was also anastomosed to the diagonal artery, obtuse marginatus (OM), posterior descending artery (PDA), and posterior left ventricle (PLV). After the surgery, the patient was followed up for six months, during which time no specific incidents occurred and no sternum-related complications were observed either. Conclusions: In this case report, the use of LIMA in a patient who had undergone a bone marrow transplant and CABG surgery was not associated with any increase in sternum-related complications.

Clinical Outcome and Treatment-Related Mortality in Patients with Acute Myeloid Leukemia Treated at the Uganda Cancer Institute

Background Acute myeloid leukaemia (AML) is the most common acute leukaemia in adults, accounting for about 80% of cases, and accounts for 20% of childhood leukemias. Treatment of AML is similar in both high-income and low- and middle-income countries (LMICs), and utilizes an anthracycline and cytarabine backbone. Treatment-related mortality (TRM) for AML in high-income countries is significantly lower than in LMICs. Understanding the factors associated with TRM in LMICs is critical to improving AML outcomes. Here we describe the response rate to induction therapy and TRM in patients with AML treated at a tertiary cancer facility in Uganda. Methods A retrospective study of all patients treated for AML at the Uganda Cancer Institute (UCI) in the years 2015-2020 was performed. The diagnosis of AML was based on bone marrow or peripheral blood morphology or flow cytometry. The regimen for remission induction of adult patients with AML at the UCI includes daunorubicin 60mg/m2 given intravenously on days 1-3 and cytarabine 200mg/m2 given intravenously on days 1-7 ("3+7"), while the paediatric regimen (termed "AD") consists of daunorubicin 50mg/m2 given intravenously on days 1, 3, and 5 and cytarabine 100mg/m2 given intravenously twice daily on days 1-10, followed by a second course. Consolidation therapy is given to all patients who achieve complete remission after up to 2 courses of induction. Complete remission was defined as <5% blasts in the marrow identified by morphology or flow cytometry. The study was approved by the UCI Research Ethics Committee (Ref. UCI-2020-9) and the Uganda National Council for Science and Technology (Ref. HS946ES). All patients’ information was anonymized. Results. Medical records were reviewed for 290 patients with a diagnosis of AML, of whom 186 were further analyzed after excluding patients diagnosed with acute promyelocytic leukemia (n=33), those who did not receive induction therapy (n=66), and those who received low dose chemotherapy (n=5). The median age was 20 (IQR, 10-35) years. Patient characteristics are reported in Table 1. One hundred fourteen (61.3%) adult and adolescent patients received a standard "3+7” induction regimen, 65 (34.9%) children were treated with "AD,” and 7 (3.8%) patients received other regimens. Seventy four (39.8%) patients received a second course of induction. Treatment response assessment showed that 86 (46.2%) patients achieved complete remission (CR). Of these, 62 (72%) achieved CR after the first induction, with the remaining 24 (28%) after the second induction. Forty five (24.2 %) patients with evaluable response data at the end of induction did not achieve remission. A total of 55 (29.6%) patients died, all in the first induction course. The overall 30-day induction TRM rate was 31.5% (95% CI, 25.2 - 38.8) with 3-month, 6-month and one-year survival of 52.9% (95% CI, 45.3 - 60), 43.3% (95% CI, 35.8 - 50.6) and 30.8% (95% CI, 23.6 - 30.4) respectively (Figure 1). A pre-treatment HCT - CI score of >2 HR 3.37 (1.084 - 10.461), p=0.04 was associated with increased 30-day TRM. Conclusion This study of 186 patients with AML treated at the UCI with standard induction regimens over a 5-year period demonstrates a CR rate of 46.2% and an overall 30-day induction TRM rate of 31.5%. A pre-treatment HCT-CI score of >2 was associated with increased TRM. Our study demonstrates the urgent need for interventions that can reduce TRM and improve the outcome for patients with AML in LMICs. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Focal Osteoporotic Marrow Defects – Variant of Chronic Ischemic Bone Disease? Clinicopathology Review of 596 Cases

<h3>Background</h3> Focal Osteoporotic Marrow Defects (FOMD) presents as a localized, asymptomatic, poorly-demarcated radiolucency, considered by some as a variant of normal marrow architecture. The cause of this lesion is unknown but recent examples of ischemiarelated regional osteoporosis in long bones suggest an anoxic or ischemic origin. <h3>Objective</h3> To determine the proportion of FOMD lesions showing histopathologic evidence of ischemic marrow disease. Methods: 596 intramedullary tissue samples of microscopically diagnosed FOMD were reviewed for fea- tures of regional ischemic osteoporosis. Microscopic criteria characteristic for early ischemic changes in long bones were used to compare with findings in jawbone biopsy samples of FOMD. Clinical features and patient demograph- ics were also analyzed. Results: 74% of 581 patients were female and the average age at diagnosis was 49 years. Lesions were evenly distributed between the jaws and 79% were in the retromolar/third molar area. 92% were in edentulous bone, and 77% were in old extraction sites; 3% of cases were bilateral and 30% were tender or painful. The average lesion size was 1.2 cm (range: 0.52.8 cm.) and none showed cortical expansion. 76% of FOMD lesions were comprised primarily of fatty marrow, and 88% of the total showed microscopic features of ischemic marrow damage consistent with those found in regional osteoporosis of the long bones; 9% demonstrated intravascular thrombi. Differences were found between hematopoietic and fatty FOMD lesions. <h3>Conclusions</h3> The FOMD lesion appears to be the jawbone variant of regional osteoporosis of long bones, i.e. is an ischemic phenomenon perpet- uated by compromised marrow blood flow. There are 2 subtypes of FOMD: the fatty marrow type and the less common hematopoietic marrow type; fatty lesions are much more likely to be in the maxilla, to be in males, and to be associated with pain.

RNA-based immunoglobulin repertoire sequencing is a new tool for the management of monoclonal gammopathy of renal (kidney) significance

The diagnostic approach of monoclonal gammopathy of renalsignificance is based on the detection of a monoclonal immunoglobulin in the blood and urine, and the identification of the underlying clone through bone marrow and/or peripheral blood cytologic and flow cytometry analysis. However, the monoclonal component and its corresponding clone may be undetectable using these routine techniques. Since clone identification is the cornerstone for guiding therapy and assessing disease response, more sensitive methods are required. We recently developed a high-throughput sequencing assay from bone marrow mRNA encoding immunoglobulins (RACE-RepSeq). This technique provides both full-length V(D)J region (variable, diversity andjoining genes that generate unique receptors as antigen receptors) of the monoclonal immunoglobulin and the dominant immunoglobulin repertoire. This allows analysis ofmutational patterns, immunoglobulin variable gene frequencies and diversity due to somatic hypermutation. Here, we evaluated the diagnostic performance of RACE-RepSeq in 16 patients with monoclonal-associated kidney lesions, and low serum monoclonal immunoglobulin and free light chain levels at diagnosis. Bone marrow immunohistochemical analysis was negative in all 11 patients so tested and 7 of 12 patients had no detectable clone matching the kidney deposits using flow cytometry analysis. By contrast, RACE-RepSeq detected a dominant clonal light chain sequence of matched isotype with respect to kidney deposits in all patients. Thus, high throughput mRNA sequencing appears highly sensitive to detect subtle clonal disorders in monoclonal gammopathy of renal significance and suggest this novel approach could help improve the management of this kidney disease.

Effects of Aging and Exercise Training on Vasomotor Function of Bone Resistance Arteries and Bone Blood Flow

Adequate skeletal perfusion is necessary to maintain bone remodeling processes, and decrements in bone arterial function and regional blood flow may lead to conditions such as osteoporosis. Aging elicits progressive bone loss, associated with impaired bone vasomotor function and perfusion, that can lead to osteoporosis. Although these age‐related adaptations are ameliorated via exercise training, the specific mechanisms underlying exercise‐induced alterations of bone vasomotor function with aging remain largely unknown. The purpose of this study was to elucidate the age‐ and exercise‐induced vasomotor adaptations of the bone principal nutrient artery and subsequent alterations in bone blood flow.Young and old male Fischer‐344 rats underwent treadmill exercise training (15 m/min, 15° incline, 1hr/day, 5 days/wk for 10–12 wks) or remained sedentary in cages. At the end of the experimental period, the femoral principal nutrient artery (PNA) was isolated, cannulated, and pressurized for vascular response studies. Vasoconstrictor responses of the PNA were assessed in vitro using α‐adrenergic agonist phenylephrine (PE, 10−9–10−4 M), receptor‐independent potassium chloride (KCl, 10–100 mM) and myogenic responsiveness to increasing intraluminal pressure (0 to 140 cmH2O). Endothelium‐dependent (ACh, 10−9–10−4 M) and ‐independent (Dea‐NONOate, 10−9–10−4 M) vasodilator responses were also evaluated. Additionally, regional blood flow to the femur was measured at rest and during exercise using radiolabeled microspheres.Vasomotor responses to agonists for constriction (PE, KCl) and dilation (ACh, Dea‐NONOate) decreased with aging. In contrast, myogenic responsiveness in old rats was greater compared with young rats (p&lt;0.05). Vasoconstrictor response to KCl was greater after training in both young and old rats as compared to the sedentary rats. Exercise‐trained old rats also showed increased vasoconstrictor responses to PE and myogenic responsiveness; however, no significant difference was shown in young rats (p&lt;0.05). Exercise training enhanced endothelium‐dependent vasodilation in both young and old rats; however, no significant exercise effect was observed in endothelium‐independent vasodilation (p&lt;0.05). Regional femur blood flow to the proximal and distal metaphysis and epiphysis, as well as diaphyseal marrow, was lower in aged rats compared to young rats at rest. However, exercise‐trained old rats showed significantly increased regional blood flow during exercise compared with old SED rats (p&lt;0.05).These results demonstrate vasomotor responses are impaired in the femoral PNA from aged rats; however, endurance training intervention at advancing age can reverse vasomotor deficits including vasoconstrictor and vasodilator response in bone resistance arteries and enhance regional bone and marrow blood flow. Such changes in bone and marrow perfusion could play an important role in enhancing the quality and strength of bone in old age following exercise training.Support or Funding InformationNIH grant AG055029

Measuring Knee Bone Marrow Perfusion Using Arterial Spin Labeling at 3\u2009T

Bone perfusion is an essential physiological measure reflecting vasculature status and tissue viability of the skeletal system. Arterial spin labeling (ASL), as a non-invasive and non-contrast enhanced perfusion imaging method, is an attractive approach for human research studies. To evaluate the feasibility of ASL perfusion imaging of knee bone marrow in the distal femoral condyle at a 3 T MRI scanner, a study was performed with eight healthy volunteers (three males and five females, 26 ± 2 years old) and two patients (male, 15 and 11 years old) with diagnosed stage II juvenile osteochondritis dissecans (JOCD). ASL imaging utilized a flow-sensitive alternating inversion recovery method for labeling and a single-shot fast spin echo sequence for image readout. In addition to quantitative knee bone marrow ASL imaging, studies were also performed to evaluate the effects of prolonged post-bolus delay and varied labeling size. ASL imaging was successfully performed with all volunteers. Despite the benefits of hyper-intensive signal suppression within bone marrow, the use of a prolonged post-bolus delay caused excessive perfusion signal decay, resulting in low perfusion signal-to-noise ratio (SNR) and poor image quality. Bone marrow perfusion signal changed with the labeling size, suggesting that the measured bone marrow perfusion signal is flow-associated. The means and standard deviations of bone marrow blood flow, spatial SNR, and temporal SNR from the quantitative perfusion study were 38.3 ± 5.2 mL/100 g/min, 3.31 ± 0.48, and 1.33 ± 0.31, respectively. The imaging results from JOCD patients demonstrated the potential of ASL imaging to detect disease-associated bone marrow perfusion changes. This study demonstrates that it is feasible to perform ASL imaging of knee bone marrow in the distal femoral condyle at 3 T.

DC Vaccination Induces Antigen Specific Immune Responses in AML Patients: A 1-Year Interim Assessment

Acute myeloid leukemia (AML) is a lethal hematological malignancy characterized by high rates of relapse (50%). Studies of immune responses in AML patients led to identification of two leukemia-associated antigens (Wilms' tumor protein 1 (WT1) and preferentially expressed antigen of melanoma (PRAME) for which cellular and humoral immune responses were detected. Based on expression profiles in AML and normal tissues, WT1 and PRAME were selected as target antigens for a DC vaccine, aiming to elicit adaptive and innate immune responses in AML patients. The primary objective of the trial (EudraCT No.: 2014-003520-44) is to evaluate safety and feasibility of active immunotherapy with antigen-loaded autologous DCs. The secondary objectives are to assess DC vaccination-induced T cell responses against WT1 and PRAME and to evaluate the clinical outcome over a period of 2 years or until disease progression/relapse. WT1-positive AML patients, with or without PRAME positivity were included, if they had a morphological remission with or without hematological recovery (CRi) after induction chemotherapy and were not eligible for allogeneic hematopoietic stem cell transplantation. DCs were administered intradermally (2.5x106 WT1 plus 2.5x106 PRAME DCs) on a weekly basis for 4 consecutive weeks, followed by administration on week 6 and then every 4 weeks until 2 years, tumor progression or patient withdrawal. This report focusses on the immune-monitoring data collected during the first year of treatment. Multiple parameters were evaluated, including WT1- and PRAME specific T cell responses in peripheral blood (IFN-g ELISPOT), the recurrence of WT1- and/or PRAME-positive AML blasts in bone marrow (qRT-PCR) and peripheral blood (flow cytometry), and occurrence of AML-specific mutations in bone marrow (NGS). DCs were assessed for expression of WT1 and PRAME and costimulatory molecules by flow cytometry, while secretion of IL10 and IL12 was evaluated by double-color ELISPOT. Twenty CR/CRi AML patients were vaccinated, and vaccination was well tolerated, and no signs of autoimmunity were observed. 12/20 patients remained stable throughout the first year of treatment, while 8/20 relapsed. 2/8 relapsed patients died due to progression of disease during the first year. In patients in stable remission, 7/12 patients had no detectable IFN-γ ELISPOT response in peripheral blood, 3/12 mounted a response and 2/12 were not evaluable due to high background production of IFN-γ. Positive IFN-γ ELISPOT responses were observed within 1-30 weeks of treatment and associated with a decrease over time in levels of WT1 (3/3) and/or PRAME mRNA (1/3) expression. Except for 2 patients who remained MRD-negative throughout the first year of treatment, ELISPOT-negative patients in remission (5/7) exhibited low, relatively stable levels of target antigens. Stable remissions were associated with one (3/12) or no (8/12) AML-related mutations while one patient was not evaluable. AML relapses were observed within 50 days in 4 patients, within 51-100 days in 1 patient, and after more than 150 days in 3 patients. Overall, 6/8 relapsing patients exhibited positive IFN-γ ELISPOT responses, while 2 patients relapsing in &lt;50 days failed to respond and one patient relapsing on day 77 exhibited an IFN-γ response at baseline. In all other relapsing patients, IFN-γ ELISPOT responses were detected within 6-30 weeks after vaccination, in association with rapid and progressive increases in levels of WT1 and/or PRAME. AML-related gene mutations were detected in 6/8 relapses, while one patient was not evaluable, and one had no mutation; In 4 of the relapsing patients, 3 to 6 mutations were detected, while in 2/8 a single mutation was observed. In conclusion, IFN-γ responses to WT1 and/or PRAME were detected in peripheral blood of 75% (6/8) of relapsing patients, but only 25% (3/12) of the patients in remission. It is tempting to speculate that detection of IFN-γ response in peripheral blood is linked to the concomitant presence of AML blasts in the periphery of relapsing patients. Stable or decreasing levels of WT1 and/or PRAME mRNA in bone marrow of most patients in remission is compatible with the hypothesis that a local response against AML antigens may be ongoing, despite a negative IFN-γ response in peripheral blood. Monitoring of the patients currently in remission may shed some light on the role of DC vaccination on the prevention of AML recurrence. Disclosures Eckl: Medigene Immunotherapies GmbH: Employment. Raffegerst:Medigene Immunotherapies GmbH: Employment. Schnorfeil:Medigene Immunotherapies GmbH: Employment. Prinz-Schulz:Medigene Immunotherapies GmbH: Employment. Fingerhut:Medigene Immunotherapies GmbH: Employment. Bigalke:BioNTech Innovative Manufacturing Services GmbH: Employment. Pinkernell:Medigene AG: Employment. Schendel:Medigene AG: Employment, Equity Ownership, Honoraria, Membership on an entity's Board of Directors or advisory committees, Patents &amp; Royalties. Tafuri:Medigene Immunotherapies GmbH: Employment.

The effect of hemorrhagic shock and intraosseous adrenaline injection on the delivery of a subsequently administered drug - an experimental study

BackgroundIntraosseous (IO) access is a recommended method when venous access cannot be rapidly established in an emergency. Experimental data suggest that major hemorrhage and catecholamine administration both reduce bone marrow blood flow. We studied the uptake of gentamicin as a tracer substance administered IO following adrenaline administration in hemorrhagic shock and in cardiac arrest.MethodsTwenty anesthetized pigs underwent hemorrhage corresponding to 50% of the blood volume. They then received injections of either; adrenaline IO (n = 5), saline IO n = 5), adrenaline IO during cardiac arrest and cardiopulmonary resuscitation (CPR, n = 5), or intravenous adrenaline. The injections were followed by an injection of gentamicin by the same route. Doses and volumes were equivalent among the groups. In all animals, mixed venous antibiotic concentrations were analyzed at 5, 15 and 30 min after administration.ResultsMean (SD) plasma gentamicin concentrations (mg x L− 1) at 5 min were 26.4 (2.3) in the group with previous IO adrenaline administration, 26.6 (4.5) in the IO saline group, 31. 2 (12) in the IO adrenaline + CPR group and 23 (4.5) in the IV group. Concentrations in the CPR group were significantly higher than the others.ConclusionsNo impairment of drug uptake with IO administration after recent IO adrenaline exposure was demonstrable in this shock model.

Regulation of bone blood flow in humans: The role of nitric oxide, prostaglandins, and adenosine.

The mechanisms that regulate bone blood flow (BBF) in humans are largely unknown. Animal studies suggest that nitric oxide (NO) could be involved, and in this study, we investigated the effects of inhibition of nitric oxide synthase (NOS) alone and in combination with inhibition of cyclooxygenase (COX) enzyme, thus prostaglandin (PG) synthesis on femoral bone marrow blood flow by positron emission tomography in healthy young men at rest and during one-leg dynamic exercise. In an additional group of healthy men, the role of adenosine (ADO) in the regulation of BBF during exercise was investigated by use of an adenosine receptor blocker (aminophylline). Inhibitors were directly infused into the femoral artery. Resting BBF was 1.1±0.4mL100g-1 min-1 and increased to almost sixfold in response to exercise (6.3±1.5mL100g-1 min-1 ). Inhibition of NOS reduced BBF at rest to 0.7±0.3mL100g-1 min-1 (P=.036), but did not affect BBF significantly during exercise (5.5±1.4mL100g-1 min-1 , P=.25). On the other hand, while combined NOS and COX inhibition did not cause any further reduction of blood flow at rest (0.6±0.2mL100g-1 min-1 ), the combined blockade reduced BBF during exercise by ~21%, to 5.0±1.8mL100g-1 min-1 (P=.014). Finally, the ADO inhibition during exercise reduced BBF from 5.5±1.9mL100g-1 min-1 to 4.6±1.2mL100g-1 min-1 (P=.045). In conclusion, our results support the view that NO is involved in controlling bone marrow blood flow at rest, and NO, PG, and ADO play important roles in controlling human BBF during exercise.

Effects of Volatile Anesthetics on Oral Tissue Blood Flow in Rabbits: A Comparison Among Isoflurane, Sevoflurane, and Desflurane

The aim of this study was to compare the concentration-dependent effects of isoflurane, sevoflurane, and desflurane on oral tissue blood flow. Thirty male Japan White rabbits were randomized to receive 1 of 3 volatile anesthetics: isoflurane (group Iso), sevoflurane (group Sevo), or desflurane (group Des). The end-tidal concentration of each volatile anesthetic was regulated to 0.5, 1, and 1.5 minimum alveolar concentrations (MACs). The observed variables were heart rate, systolic blood pressure, diastolic blood pressure, mean arterial pressure, common carotid arterial blood flow, tongue mucosal blood flow, mandibular bone marrow blood flow (BBF), masseter muscle blood flow (MBF), upper alveolar tissue blood flow, and lower alveolar tissue blood flow (LBF). The blood pressure in each group tended to decrease depending on the concentration of each volatile anesthetic, with the smallest effect in group Des. BBF and MBF in group Iso were higher than those in group Des at 1 MAC, and MBF and LBF in group Iso were highest at 1.5 MAC. The results of this study suggest that each volatile anesthetic produced unique effects on blood flow in oral tissues and circulatory parameters. Among the 3 volatile anesthetics, desflurane produced the smallest effects on oral tissue blood flow.

Type 2 diabetes alters bone and marrow blood flow and vascular control mechanisms in the ZDF rat.

Bone health and cardiovascular function are compromised in individuals with type 2 diabetes mellitus (T2DM). The purpose of this study was to determine whether skeletal vascular control mechanisms are altered during the progression of T2DM in Zucker diabetic fatty (ZDF) rats. Responses of the principal nutrient artery (PNA) of the femur from obese ZDF rats with prediabetes, short-term diabetes, and long-term diabetes to endothelium-dependent (acetylcholine) and -independent (sodium nitroprusside) vasodilation and potassium chloride, norepinephrine (NE), and a myogenic vasoconstrictor were determined in vitro. Few changes in the PNA vasomotor responses occurred for the prediabetic and short-term diabetic conditions. Endothelium-dependent and -independent vasodilation were reduced, and NE and myogenic vasoconstriction were increased in obese ZDF rats with long-term diabetes relative to lean age-matched controls. Differences in endothelium-dependent vasodilation of the femoral PNA between ZDF rats and controls were abolished by the nitric oxide synthase inhibitor N(G)-nitro-l-arginine methyl ester. The passive pressure-diameter response of the femoral PNA was also lower across a range of intraluminal pressures with long-term T2DM. Regional bone and marrow perfusion and vascular conductance, measured in vivo using radiolabeled microspheres, were lower in obese ZDF rats with long-term diabetes. These findings indicate that the profound impairment of the bone circulation may contribute to the osteopenia found to occur in long bones during chronic T2DM.

Concomitant administration of nitrous oxide and remifentanil reduces oral tissue blood flow without decreasing blood pressure during sevoflurane anesthesia in rabbits.

To determine whether continuous administration of nitrous oxide and remifentanil—either alone or together—alters blood flow in oral tissues during sevoflurane anesthesia. Eight male tracheotomized Japanese white rabbits were anesthetized with sevoflurane under mechanical ventilation. Heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), common carotid arterial blood flow (CCBF), tongue mucosal blood flow (TMBF), mandibular bone marrow blood flow (BBF), masseter muscle blood flow (MBF), upper alveolar tissue blood flow (UBF), and lower alveolar tissue blood flow (LBF) were recorded in the absence of all test agents and after administration of the test agents (50 % nitrous oxide, 0.4 μg/kg/min remifentanil, and their combination) for 20 min. Nitrous oxide increased SBP, DBP, MAP, CCBF, BBF, MBF, UBF, and LBF relative to baseline values but did not affect HR or TMBF. Remifentanil decreased all hemodynamic variables except DBP. Combined administration of nitrous oxide and remifentanil recovered SBP, DBP, MAP, and CCBF to baseline levels, but HR and oral tissue blood flow remained lower than control values. Our findings suggest that concomitant administration of nitrous oxide and remifentanil reduces blood flow in oral tissues without decreasing blood pressure during sevoflurane anesthesia in rabbits.

Exercise Training Augments Regional Bone and Marrow Blood Flow during Exercise

The principal nutrient artery to the femur demonstrates an increase in nitric oxide-mediated vasodilation in rats after treadmill exercise training. The present study sought to determine whether exercise training improves hindlimb bone and marrow blood flow distribution at rest and during exercise. Six 8-month old male Sprague-Dawley rats were exercise trained (ET) with treadmill walking at 15 m · min(-1) up a 15° incline for 60 min · d(-1) over a 10- to 12-wk period. Sedentary (SED) control animals were acclimated to treadmill exercise for 5 min · d(-1) during the week preceding the blood flow measurements. Blood flow to nine distinct regions of the femur, tibia, and fibula was determined at rest and during low-intensity exercise (15 m · min(-1) walking, 0° incline) using the reference sample microsphere method. The results demonstrate an augmentation of exercise hyperemia above that observed in SED rats during exercise in only one region of the bone, the femoral diaphysis, of ET rats. However, whereas exercise hyperemia occurred in three of the nine hindlimb bone regions measured in SED rats, exercise hyperemia occurred in seven of nine regions in ET rats. These data indicate an increase in generalized hindlimb bone and marrow blood flow during physical activity after a period of exercise training. Elevations in regional bone and marrow blood flow after training may augment medullary pressure and bone interstitial fluid flow, thus benefiting bone integrity.

Chronic skeletal unloading of the rat femur: Mechanisms and functional consequences of vascular remodeling

Chronic skeletal unloading diminishes hindlimb bone blood flow. The purpose of the present investigation was to determine 1) whether 7 and 14days of skeletal unloading alter femoral bone and marrow blood flow and vascular resistance during reloading, and 2) whether putative changes in bone perfusion are associated with a gross structural remodeling of the principal nutrient artery (PNA) of the femur. Six-month old male Sprague–Dawley rats were assigned to 7-d or 14-d hindlimb unloading (HU) or weight-bearing control groups. Bone perfusion was measured following 10min of standing (reloading) following the unloading treatment. Histomorphometry was used to determine PNA media wall thickness and maximal diameter. Bone blood flow, arterial pressure and PNA structural characteristics were used to calculate arterial shear stress and circumferential wall stress. During reloading, femoral perfusion was lower in the distal metaphyseal region of 7-d HU rats, and in the proximal and distal metaphyses, diaphysis and diaphyseal marrow of 14-d HU animals relative to that in control rats. Vascular resistance was also higher in all regions of the femur in 14-d HU rats during reloading relative to control animals. Intraluminal diameter of PNAs from 14-d HU rats (138±5μm) was smaller than that of control PNAs (162±6μm), and medial wall thickness was thinner in PNAs from 14-d HU (14.3±0.6μm) versus that of control (18.0±0.8μm) rats. Decreases in both shear stress and circumferential stress occurred in the PNA with HU that later returned to control levels with the reductions in PNA maximal diameter and wall thickness, respectively. The results demonstrate that chronic skeletal unloading attenuates the ability to increase blood flow and nutrient delivery to bone and marrow with immediate acute reloading due, in part, to a remodeling of the bone resistance vasculature.

Dexmedetomidine Dose Dependently Decreases Oral Tissue Blood Flow During Sevoflurane and Propofol Anesthesia in Rabbits

The aim of the present study was to investigate the effect of dexmedetomidine (DEX) continuous infusion on blood flow in rabbit oral tissues during sevoflurane or propofol anesthesia. A total of 24 male tracheotomized Japanese white rabbits were anesthetized with sevoflurane or propofol under mechanical ventilation. An initial loading dose of 6.0 μg/kg/hr DEX was administered for 10 minutes. DEX was then maintained at 0.2, 0.4, and 0.6 μg/kg/hr for 1 hour, respectively. The observed variables were systolic blood pressure, diastolic blood pressure, mean arterial pressure, heart rate, common carotid artery blood flow, tongue mucosal blood flow (TBF), mandibular bone marrow blood flow (BBF), masseter muscle blood flow (MBF), upper alveolar tissue blood flow (UBF), lower alveolar tissue blood flow (LBF), and vascular resistance for each tissue (tongue mucosal vascular resistance, mandibular bone marrow vascular resistance, masseter muscle vascular resistance, upper alveolar tissue vascular resistance, and lower alveolar tissue vascular resistance). The heart rate, systolic blood pressure, mean arterial pressure, common carotid artery blood flow, TBF, BBF, MBF, UBF, and LBF showed dose-dependent decreases during DEX infusion during both sevoflurane and propofol anesthesia. The decreasing ratios in TBF, BBF, MBF, UBF, and LBF were greater than those in heart rate, systolic blood pressure, mean arterial pressure, and common carotid artery blood flow. The vascular resistance of the oral tissues was increased in a dose-dependent manner during DEX infusion in both sevoflurane and propofol anesthesia. Our findings suggest that infusion of DEX decreases TBF, BBF, MBF, UBF, and LBF in a dose-dependent manner without significant changes in systemic hemodynamic variables during sevoflurane or propofol anesthesia.

Tissue Blood Flow Reductions Induced by Remifentanil in Rabbits and the Effect of Naloxone and Phentolamine on These Changes

The purpose of this study was to investigate the effects of naloxone and phentolamine on the blood flow changes in rabbit oral tissue induced by remifentanil during sevoflurane anesthesia. Male Japan White rabbits were anesthetized with sevoflurane under mechanical ventilation. Remifentanil was continuously infused at a rate of 0.4 μg/kg/min. Naloxone 0.01 mg/kg or phentolamine 0.01 mg/kg was administered during remifentanil infusion. Observed variables were systolic and diastolic blood pressures, mean arterial pressure, heart rate, common carotid artery blood flow, tongue mucosal blood flow, mandibular bone marrow blood flow, masseter muscle blood flow, and upper and lower alveolar tissue blood flows. The common carotid artery blood flow was monitored continuously using an ultrasonic blood flowmeter. Tongue mucosal blood flow was monitored continuously using a laser Doppler blood flowmeter. Mandibular bone marrow blood flow, masseter muscle blood flow, and upper and lower alveolar tissue blood flows were measured using a hydrogen clearance tissue blood flowmeter. One-way analysis of variance for repeated measurements followed by the Student-Newman-Keuls test was used. Remifentanil produced decreases in the heart rate, systolic blood pressure, and common carotid artery blood flow by about 15% and mandibular bone marrow blood flow, masseter muscle blood flow, and upper and lower alveolar tissue blood flows by about 30%. In the naloxone group, all variables recovered after naloxone administration. In contrast, in the phentolamine group, tissue blood flow recovered, whereas heart rate, systolic blood pressure, and common carotid artery blood flow did not recover after phentolamine administration. Remifentanil deceased oral tissue blood flow and systemic hemodynamic variables. Naloxone and phentolamine produced a recovery of oral tissue blood flow with and without systemic hemodynamic recovery, respectively.