The InSight HP3 Penetrator (Mole) on Mars: Soil Properties Derived from the Penetration Attempts and Related Activities

The NASA InSight Lander on Mars includes the Heat Flow and Physical Properties Package HP³ to measure the surface heat flow of the planet. The package uses temperature sensors that would have been brought to the target depth of 3-5 m by a small penetrator, nicknamed the mole. The mole requiring friction on its hull to balance remaining recoil from its hammer mechanism did not penetrate to the targeted depth. Instead, by precessing about a point midway along its hull, it carved a 7 cm deep and 5-6 cm wide pit and reached a depth of initially 31 cm. The root cause of the failure - as was determined through an extensive, almost two years long campaign - was a lack of friction in an unexpectedly thick cohesive duricrust. During the campaign - described in detail in this paper - the mole penetrated further aided by friction applied using the scoop at the end of the robotic Instrument Deployment Arm and by direct support by the latter. The mole tip finally reached a depth of about 37 cm, bringing the mole back-end 1-2 cm below the surface. It reversed its downward motion twice during attempts to provide friction through pressure on the regolith instead of directly with the scoop to the mole hull. The penetration record of the mole was used to infer mechanical soil parameters such as the penetration resistance of the duricrust of 0.3-0.7 MPa and a penetration resistance of a deeper layer ( > 30 cm depth) of 4.9 ± 0.4 MPa . Using the mole's thermal sensors, thermal conductivity and diffusivity were measured. Applying cone penetration theory, the resistance of the duricrust was used to estimate a cohesion of the latter of 2-15 kPa depending on the internal friction angle of the duricrust. Pushing the scoop with its blade into the surface and chopping off a piece of duricrust provided another estimate of the cohesion of 5.8 kPa. The hammerings of the mole were recorded by the seismometer SEIS and the signals were used to derive P-wave and S-wave velocities representative of the topmost tens of cm of the regolith. Together with the density provided by a thermal conductivity and diffusivity measurement using the mole's thermal sensors, the elastic moduli were calculated from the seismic velocities. Using empirical correlations from terrestrial soil studies between the shear modulus and cohesion, the previous cohesion estimates were found to be consistent with the elastic moduli. The combined data were used to derive a model of the regolith that has an about 20 cm thick duricrust underneath a 1 cm thick unconsolidated layer of sand mixed with dust and above another 10 cm of unconsolidated sand. Underneath the latter, a layer more resistant to penetration and possibly containing debris from a small impact crater is inferred. The thermal conductivity increases from 14 mW/m K to 34 mW/m K through the 1 cm sand/dust layer, keeps the latter value in the duricrust and the sand layer underneath and then increases to 64 mW/m K in the sand/gravel layer below.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s11214-022-00941-z.

Pediatric considerations for pineal tumor management

Pineal tumors are relatively rare central nervous system lesions with a predilection for the pediatric population. For the vast majority of these lesions, surgical resection is a critical step in effective treatment. This article discusses current strategies for preoperative evaluation, operative management, and postoperative care of the pediatric patient with a newly diagnosed pineal region tumor.

Adverse Clinico-Pathological Features in Breast Cancer Patients under the Age of 35

IntroductionBreast cancer in younger patients is a unique disease entity, associated with aggressive biologic phenotype and poorer prognosis. The aim of this study was to analyse age as a prognostic factor in pre-menopausal breast cancer specifically in regards to pre-menopausal patients under the age of 35.MethodsA 7 year prospective audit of pre-menopausal patients presenting to the symptomatic breast clinic in St. James's Hospital between 2001 and 2008 was conducted. The Clinico-pathological features of pre-menopausal patients presenting under the age of 35 versus over 35 where compared. All cancer diagnoses were discussed at the breast multidisciplinary conference, and all clinico-pathological treatment details and follow-up information were entered by a full-time data manager.ResultsPre-menopausal patients under the age of 35 (n=55) were more likely to present with higher grade (p<0.05), oestrogen receptor negative (p<0.05), HER-2 receptor negative (p<0.05) and stage IV disease (p<0.05) relative to the older premenopausal group (n=250). This group also had a non-significant increased rate of lymphovascular invasion and negative progesterone receptor status compared to the older premenopausal group (p> 0.05). Pre-menopausal patients over the age of 35 were twice as likely to have lobular carcinoma as opposed to their younger counterparts. Tumour size, nodal status and axillary node burden was not significantly different between groups. Patients under-35 with breast cancer were more likely to be nulliparous.ConclusionThis data demonstrates that breast cancer in pre-menopausal patients under the age of 35 is associated with adverse clinicopathological features relative to the older pre-menopausal patients. Further studies should be aimed at assessing the prognosis, disease recurrence, disease free survival and distinct genetic profile in age related breast cancer.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 3043.

Experiment LEND of the NASA Lunar Reconnaissance Orbiter for high-resolution mapping of neutron emission of the Moon

The scientific objectives of neutron mapping of the Moon are presented as 3 investigation tasks of NASA's Lunar Reconnaissance Orbiter mission. Two tasks focus on mapping hydrogen content over the entire Moon and on testing the presence of water-ice deposits at the bottom of permanently shadowed craters at the lunar poles. The third task corresponds to the determination of neutron contribution to the total radiation dose at an altitude of 50 km above the Moon. We show that the Lunar Exploration Neutron Detector (LEND) will be capable of carrying out all 3 investigations. The design concept of LEND is presented together with results of numerical simulations of the instrument's sensitivity for hydrogen detection. The sensitivity of LEND is shown to be characterized by a hydrogen detection limit of about 100 ppm for a polar reference area with a radius of 5 km. If the presence of ice deposits in polar "cold traps" is confirmed, a unique record of many millions of years of lunar history would be obtained, by which the history of lunar impacts could be discerned from the layers of water ice and dust. Future applications of a LEND-type instrument for Mars orbital observations are also discussed.

Reduced intensity allogeneic umbilical cord blood transplantation in children and adolescent recipients with malignant and non-malignant diseases

There is a significant amount of morbidity and mortality following myeloablative umbilical cord blood transplantation (UCBT). Reduced intensity (RI) conditioning offers an alternative to myeloablative conditioning before UCBT. We investigated RI-UCBT in 21 children and adolescents with malignant (n=14), and non-malignant diseases (n=7). RI conditioning consisted of fludarabine (150-180 mg/m2) with either busulfan (< or = 8 mg/kg)+rabbit antithymocyte globulin (R-ATG; n=16) or cyclophosphamide+R-ATG+/-etoposide (n=5). Human leukocyte antigen match: 4/6 (n=13), 5/6 (n=5) and 6/6 (n=3). The median total nucleated cell and CD34+ cell dose per kilogram were 3.58 x 10(7) and 2.54 x 10(5), respectively. The median time for neutrophil and platelet engraftment was 17.5 and 52 days, respectively. There were six primary graft failures (chronic myelogenous leukemia (CML), beta-thalassemia, hemophagocytic lymphohistiocytosis (HLH) and myelodysplastic syndrome (MDS)). The probability of developing grade II to grade IV acute graft-versus-host disease (GVHD) and chronic GVHD was 28.6 and 16.7%, respectively. Incidence of transplant-related mortality (TRM) was 14%. The 5 years overall survival (OS) in all patients was 59.8%. The 5 years OS for patients with average versus poor-risk malignancy was 77.8 versus 22.2% (P=0.03). RI-UCBT may result in graft failure in specific high-risk chemo-naïve patients (CML, beta-thalassemia, HLH and MDS), but in more heavily pretreated pediatric and adolescent recipients results in rapid engraftment and may be associated with decreased severe GVHD and TRM.

Targeted immunotherapy with gemtuzumab ozogamicin (GO) following reduced intensity allogeneic stem cell transplantation (RI AlloSCT) to reduce minimal residual disease (MRD) in children with acute myeloid leukemia (AML): MRD monitoring by Wilms tumor gene

9532

Background: RI vs myeloablative (MA) AlloSCT in adults with AML is associated with significantly less transplant related mortality but increased rate of relapse, presumably secondary to MRD (Alyea et al; Blood, 2005). Quantification of the WT1 has been used successfully to detect MRD in children with acute myeloid leukemia (AML) (Kletzel et al; Pediatr Dev Pathol, 2002). GO has induced ORR in >30% of patients with overt relapsed CD33+ AML and may have a better effect in the setting of MRD (Sievers et al; J Clin Oncol, 2001). We have shown that RI AlloSCT followed by 2 doses of GO in average risk AML has resulted in >94% donor chimerism (Roman/Cairo, Clin Can Res, 2005). We explored changes in MRD prior to and after consolidation with 2 doses of GO targeted immunotherapy in children with average risk AML post RI AlloSCT. Methods: 11 pts, 11 years (0.5–21) with CD33+ (8 CR1, 3 CR2) received fludarabine 30 mg/m2x6d and busulfan 3.2–4 mg/kgx2d. Donors: 7 6/6 HLA related peripheral blood stem cells (RPBSC), 1 5/6 RPBSC, 1 6/6 related cord blood (CB) and 2 4/6 unrelated CB. GOx2 was administered =60d post AlloSCTx2 (8wks apart), at 4.5–7.5 mg/m2 (dose escalation). Samples were collected for WT1 analysis prior to and after each dose of GO (n=5). WT1 levels were determined by quantitative RT-PCR and compared with WT1 expression in a K562 leukemia line. Positive MRD was a ratio of K562 WT/patient's WT1>0.5. Results: The MTD for GO post RI AlloSCT has not been reached. 8/11 are NED (3 deaths: 1 relapse, 1 graft failure, 1 cGVHD) Pre GO WT1–0.079±0.07 (n=5), pre GO-dose #2–0.012±0.016 (n=3). One of these patients had detectable MRD (WT1–1.56) prior to the GO-dose #2, no MRD at 1year and is alive and in remission at 2 years post GOx2. The fifth patient entered transplant with +MRD (WT-0.866), relapsed after the first dose of GO and died of relapse prior to receiving the second dose. Conclusions: Targeted therapy with GOx2 may be useful in eradicating MRD in patients post RI AlloSCT. A larger cohort is necessary to assess the impact of GO (at the MTD) on MRD post RI AlloSCT in children with AML.

No significant financial relationships to disclose.

A pilot study of myeloablative (MA) autologous stem Cell (Auto SCT) followed by reduced intensity (RI) allogeneic transplantation (AlloSCT) in children with relapsed/refractory(R/R) Hodgkin’s disease (HD)

20007

Background: Allo SCT may benefit patients with R/R HD by providing a graft vs lymphoma effect. Peggs et al (Lancet 2005) demonstrated durable engraftment and reduced non relapse mortality (NRM) in HD pts post RI Allo SCT. Carella et al (JCO2000) and Gutman et al (BMT2005) demonstrated the success of MA Auto SCT followed by RI AlloSCT in adults with refractory lymphoma. We investigated the feasibility of MA Auto SCT followed by RI Allo SCT in children with R/R HD. Methods: MA conditioning prior to AutoSCT was CTX 1,500 mg/m2 x 4 d, BCNU 100 mg/m2 x 3d, VP-16 800 mg/m2 x 3d. AlloSCT conditioning was fludarabine 30 mg/m2 x 5d, busulfan 3.2 mg/kg x 2d, and R ATG 2 mg/kg x 4d (unrel. donor). CD20+ patients received rituximab (375 mg/m2/wk x4) and all pts received involved field radiotherapy (IFRT). Results: Ten pts have enrolled, 2 pts did not proceed (parental withdrawal) to RI AlloSCT (Donors: 1 MRD, 2 MUD, 5 UCB). Median time to RI AlloSCT after MA Auto SCT was 142 d (97–219). The median cell dose was 3.43 x 107 TNC/kg for UCB grafts (n=5). Engraftment was achieved at a median of 20.5 d for PMN and 46.5 d for PLT. Donor chimerism reached ≥ 95% in all pts by day 100 with a median follow up of 703d (128–2025). Toxicities were grade (3) hematuria (n=1), (3–4) infection (n=7), (4) pulmonary fibrosis (n=1), (4) hearing loss (n=1), (4) neurotoxicity (n=1). GVHD: grade II-III aGVHD (3/8), cGVHD (3/8). Six patients are alive and NED post allo SCT. There has been one NRM (cGVHD) and one relapse mortality. The OS at one year is 66.7%. Conclusions: MA AutoSCT followed by RI AlloSCT is feasible and well tolerated in pediatric pts with R/R HD. A larger study with longer follow up is required to determine if this approach will reduce relapse, long term toxicity and/or improve survival.

No significant financial relationships to disclose.

Pilot study of tandem high-dose chemotherapy and autologous stem cell transplantation with a novel combination of regimens in patients with poor risk lymphoma

In an effort to improve the outcome of poor-risk lymphoma patients, we evaluated a novel regimen of tandem high-dose chemotherapy (THDC) with autologous stem cell transplantation. A total of 41 patients (median age 40 years, range 15-68 years) with poor-risk non-Hodgkin's lymphoma and Hodgkin's disease were enrolled. THDC consisted of melphalan (180 mg/m2) and escalating dose mitoxantrone (30-50 mg/m2) (MMt) for the first conditioning regimen, and thiotepa (500 mg/m2), carboplatin (800 mg/m2), and escalating dose etoposide phosphate (400-850 mg/m2), (ETCb) as the second regimen. In all, 31 patients (76%) completed both transplants, with a median time between transplants of 55 days (range 26-120). The maximum tolerated dose was determined as 40 mg/m2 for mitoxantrone and 550 mg/m2 for etoposide phosphate. The overall toxic death rate was 12%. Following high-dose chemotherapy, 10 of 24 evaluable patients (42%) were in CR. The two-year overall survival and event-free survival is 67% (95% CI, 52-81%) and 45%, (95% CI, 29-61%) for the 41 patients enrolled; and 69% (95% CI, 525-586%) and 48% (95% CI, 30-67%) for the 31 patients completing both transplants. This THDC regimen is feasible but with notable toxicity in heavily pretreated patients; its role in the current treatment of high-risk lymphoma remains to be determined.

Outcomes of unrelated cord blood transplantation in pediatric recipients

We report results of unrelated cord blood transplants (UCBT) in 29 pediatric recipients in one center and the risk factors associated with survival. Median age: 9 years (0.5-20); diagnosis: ALL (9), AML (4), CML (1), HD (3), HLH (1), NHL (3), NBL (2); B-thal (1), FA (1), FEL (1), Krabbe (1), WAS (1), SAA (1); median follow-up: 11 months; conditioning: total body irradiation (TBI)-ablative (14), chemotherapy-ablative (6) and reduced intensity chemotherapy (9); GVHD prophylaxis: MMF/FK506 (18), cyclosporin A (CsA)+steroids+/-MMF (7) or CsA+methotrexate (MTX) (4); median total nucleated cells (TNC): 3.8 x 10(7)/kg (1.1-11); median CD34+: 2.3 x 10(5)/kg (0.2-9.9); and HLA match: 2 (6/6), 5 (5/6), 22 (4/6). Neutrophil engraftment by cumulative incidence curves 63% (median 28 (95% confidence interval (CI) 18-32)). Probability of >/=grade II acute graft-versus-host disease (aGVHD) by day +60 27%, >/=grade III aGVHD 20% and chronic graft-versus-host disease 3%. Estimated 1-year overall survival (OS) 46% (95% CI 30-71) and standard risk 60% (95% CI 29-100%). Variables associated with improved survival by multivariate analysis include non-TBI-ablative conditioning (P=0.024), CD34+/kg (P=0.038) and gender (P=0.048). These results suggest that CD34/kg cell dose and non-TBI-ablative conditioning may be important variables influencing OS following UCBT in pediatric recipients. Given the small number of patients, these results should be viewed cautiously.

A pilot study of reduced intensity conditioning and allogeneic stem cell transplantation from unrelated cord blood and matched family donors in children and adolescent recipients

Reduced intensity (RI) allogeneic stem cell transplantation (AlloSCT) was initially demonstrated in adults following HLA-matched family and unrelated adult donor AlloSCT. There is little information about RI AlloSCT in children. We report results of a pilot study of RI AlloSCT in 21 recipients (< or =21 years). Age: median 13 (0.5-21) years, 8F:13M, 14 unrelated cord blood units (UCB) (10 4/6, 4 5/6), two related BM (6/6, 5/6), four related PBSC (2 6/6, 2 5/6), and one related BM+PBSC (6/6). RI: fludarabine, busulfan (n=14); fludarabine, cyclophosphamide (n=4); fludarabine, melphalan (n=1); total body irradiation, fludarabine, cyclophosphamide (n=1); or fludarabine, cyclophosphamide, and etoposide (n=1). Graft-versus-host disease prophylaxis: FK506 0.03 mg/kg/day and mycophenolate mofetil 15 mg/kg/q 12 h. UCB median nuc/kg and CD34/kg was 4.3 x 10(7)/kg (0.9-10.8) and 1.9 x 10(5)/kg (0.3-6.9), and related BM/PBSC median nuc/kg and CD34/kg was 8.3 x 10(8) (4.7-18.9) and 5.0 x 10(6)/kg (4.6-6.4). Maximal chimerism following unrelated cord blood transplantation, 100% x 7, 98% x 1, 95% x 2, 55% x 1, and 0% x 3; related PBSC/BM, 100% x 5, 65% x 1, and 55% x 1. Graft failure occurred in 5/21 (24%). In summary, RI AlloSCT in children is feasible and tolerable (< or =25% GF) and results in > or =85% of recipients initially achieving > or =50% donor chimerism.

Mars exploration

An international flotilla of spacecraft are to be sent to Mars over the next decade in an effort to understand the planet's geology and climate history, and to determine whether some form of life ever started there. At least two spacecraft will be sent at each launch opportunity, and at times up to four spacecraft may be operating simultaneously at the planet.

High-dose carmustine, thiotepa and etoposide followed by autologous bone marrow rescue for the treatment of high risk central nervous system tumors

Forty-two patients (29 newly diagnosed) with high grade gliomas (n = 37), medulloblastoma (n = 2) or non-biopsied tumors (n = 3) with supratentorial (n = 24), brain stem (n = 11), posterior fossa (n = 5) or spinal (n = 2) location were eligible for this study with adequate organ function and no bone marrow tumor infiltration. Median patient age was 12.2 years (range, 0.7-46.8). A total of 600 mg/m2 BCNU, 900 mg/m2 thiotepa and 1500 or 750 mg/m2 etoposide (VP-16) was administered followed by autologous bone marrow reinfusion (ABMR). Twenty-one newly diagnosed patients received local irradiation (RT) post ABMR. Nine early deaths were observed (21%), as well as one secondary graft failure. Half of the patients aged 18 years or older experienced toxic deaths, whereas only 15% of patients younger than 18 years experienced toxic death (P = 0.05). Of 25 evaluable newly diagnosed patients, 20% achieved complete remission (CR) and 4% partial remission (PR), while 28% remained in continuing complete remission (CCR) and 44% remained with stable disease prior to RT. Of eight evaluable patients with recurrent disease, one achieved CR and two PR, while one remained in CCR and four with stable disease for 1 to 110.2 months. Overall survival was 36%, 24% and 17% at 1, 2 and 3 years following ABMR, with three newly diagnosed patients and one patient treated for recurrent disease being alive, without disease progression 64.4, 67.0, 86.3 and 110.2 months after ABMR, respectively. The combination of high-dose BCNU/ thiotepa/VP-16 has substantial toxicity but definite activity for high risk CNS tumors. Similar protocols with lower toxicity merit further evaluation in both newly diagnosed and recurrent CNS tumors.

Intensive chemotherapy and bone marrow rescue for young children with newly diagnosed malignant brain tumors

PURPOSE

To evaluate a strategy that avoids radiotherapy in children less than 6 years of age with newly diagnosed malignant brain tumors, by administering myeloablative consolidation chemotherapy with autologous bone marrow reconstitution (ABMR) after maximal surgical resection and conventional induction chemotherapy.

PATIENTS AND METHODS

Between March 1991 and April 1995, 62 children (median age, 30 months) with newly diagnosed malignant brain tumors were enrolled onto this trial. Children received conventional induction chemotherapy with vincristine, cisplatin, cyclophosphamide, and etoposide, repeated every 3 weeks for five cycles. Children without disease progression on induction chemotherapy were offered consolidation with myeloablative chemotherapy that incorporated carboplatin, thiotepa, and etoposide followed by ABMR. Irradiation was used only for residual tumor at consolidation or for progressive/recurrent disease.

RESULTS

Induction chemotherapy was well tolerated by most patients; however, progression was noted in 17 children (27%) and four (6%) died of treatment complications. Of 37 children who received consolidation chemotherapy with ABMR, 15 are free of disease progression (median post-ABMR without further treatment, >44 months). The remaining 22 all progressed within 15 months of ABMR; three of 37 (8%) died of treatment-related complications. The 3-year overall survival (OS) and event-free survival (EFS) rates from diagnosis for all children are 40% (95% confidence interval [CI], 28% to 52%) and 25% (95% CI, 13% to 37%), respectively. Radiotherapy was administered to 19 of 62 children: 17 for progressive disease (PD) and two for residual disease at the time of ABMR.

CONCLUSION

A significant proportion of children with malignant brain tumors can avoid radiotherapy and prolonged maintenance chemotherapy yet still achieve durable remission with this brief intensive chemotherapy regimen.

Iron overload in reticuloendothelial systems of pediatric oncology patients who have undergone transfusions: MR observations

OBJECTIVE

Pediatric oncology patients who undergo intensive chemotherapy develop anemia caused by myeloid suppression that necessitates transfusions that, in turn, cause iron deposition in the reticuloendothelial system. We describe MR imaging of iron overload in pediatric patients who underwent such chemotherapy and who have solid and hematologic tumors.

MATERIALS AND METHODS

The MR appearance of the liver, spleen, and bone marrow was evaluated in 13 children with both solid (n = 10) and hematologic (n = 3) malignant lesions using known criteria for the presence of iron deposition. Findings were correlated with transfusional history, chemotherapeutic regimens, and ferritin levels.

RESULTS

MR imaging obtained after chemotherapy and transfusional therapy revealed signs of iron deposition in the liver and spleen, particularly on T2-weighted images. Bone marrow signal intensity varied among patients. Pancreatic signal intensity was normal. Ferritin levels were elevated in all patients.

CONCLUSION

Reticuloendothelial system iron deposition present in follow-up MR imaging of pediatric solid and hematologic malignant lesions reflected the intensity of the chemotherapeutic regimen, the degree of myeloid suppression, and the resultant transfusional requirements. Such iron deposition appeared to have no effect on cardiac, liver, or pancreatic function.

Stage IVN neuroblastoma: MRI diagnosis of left supraclavicular "Virchow's" nodal spread

Stage IV neuroblastoma is associated with high mortality; an exception are patients whose stage IV status includes distant positive nodes, but no skeletal metastases-stage IVN neuroblastoma. We describe our experience with preoperative MRI in three patients with extensive abdominal neuroblastoma without cortical bony involvement but with unsuspected metastatic involvement to the left supraclavicular (Virchow's) node. We review findings of left supraclavicular nodal spread in five earlier cases of IVN neuroblastoma.

Pilot study of high-dose thiotepa and etoposide with autologous bone marrow rescue in children and young adults with recurrent CNS tumors. The Children's Cancer Group

PURPOSE

This study was designed to determine the toxicity, radiographic response rate, and outcome following high-dose thiotepa, etoposide, and autologous bone marrow rescue (ABMR) for young patients with recurrent malignant brain tumors.

METHODS

Eligibility criteria required adequate renal, hepatic, and pulmonary function, and no bone marrow infiltration. Thiotepa 300 mg/m2 and etoposide 500 mg/ m2 were infused on 3 consecutive days, and autologous bone marrow was infused 72 hours following chemotherapy.

RESULTS

Forty-five patients with recurrent high-grade brain tumors, aged 8 months to 36 years (median, 8 years), were treated. Seven patients (16%) died of treatment-related toxicities within 56 days of marrow reinfusion. Delayed platelet engraftment occurred in 44% of patients who survived beyond day 56. Of 35 patients with radiographically measurable disease who survived at least 28 days following ABMR, there were two complete responses (CRs) and six partial responses (PRs), for an overall response (CRs plus PRs) rate of 23% (SE = 7%). Objective responses were observed in four of 14 assessable patients with high-grade glioma and in two of six with primitive neuroectodermal tumors (PNETs)/ medulloblastoma. Survival was significantly improved in patients treated with minimal residual disease (P < .0005). Five of 18 patients (28%) with high-grade gliomas remain free of disease at 39+, 44+, 49+, 52+, and 59+ months post-ABMR.

CONCLUSION

The combination of high-dose thiotepa and etoposide has activity against a variety of recurrent childhood brain tumors. These results merit further evaluation in children and young adults with both recurrent and newly diagnosed high-grade brain tumors.

Angiotensin II action in isolated microperfused rabbit afferent arterioles is modulated by flow

We have recently presented evidence that endogenous nitric oxide (NO) and prostaglandins (PGs) modulate angiotensin II (Ang II) action in microperfused afferent arterioles (Af-Arts). Because flow may be a physiological stimulus of endothelial release of NO and PGs, we tested the hypothesis that flow through the lumen of the Af-Art stimulates the endothelium to produce NO and PGs, which in turn modulate the action of Ang II. We microdissected the terminal segment of an interlobular artery together with two Af-Arts, their glomeruli and efferent arterioles (Ef-Art). The two Af-Arts were perfused simultaneously from the interlobular artery, while one Ef-Art was occluded. Since the arteriolar perfusate contained 5% albumin, oncotic pressure built up in the glomerulus with the occluded Ef-Art and opposed the force of filtration, resulting in little or no flow through the corresponding Af-Art. Thus this preparation allowed us to observe Ang II action in free-flow and non-flow Af-Arts simultaneously. Ang II-induced constriction was weaker in free-flow than non-flow Af-Arts, with the luminal diameter decreasing by 8 +/- 2% and 23 +/- 3% at 10(-9) M, respectively (P < 0.013 free-flow vs. non-flow; N = 9). Disrupting the endothelium augmented Ang II action in free-flow (33 +/- 5.1%; P < 0.01 vs. intact endothelium) but not non-flow Af-Arts (31 +/- 5.3%), thus abolishing the differences between them (N = 8). Pretreatment with an inhibitor of either NO synthase (N-nitro-L-arginine methyl ester) or cyclooxygenase (indomethacin) augmented Ang II action more in free-flow than non-flow Af-Arts, likewise abolishing the differences between them. These results suggest that intraluminal flow modulates the vasoconstrictor action of Ang II in Af-Arts via endothelium-derived NO and PGs. Thus flow may be important in the fine control of glomerular hemodynamics.

Cytotoxicity study of tacrine, structurally and pharmacologically related compounds using rat hepatocytes

Tacrine is the first drug approved for the treatment of Alzheimer's disease. Approximately 50% of patients treated with tacrine develop elevated serum aminotransferase levels, as an indication of potential hepatotoxicity. However, acute and chronic studies with a limited number of animal models have not demonstrated hepatotoxicity. The present study compared the cytotoxicity in hepatocyte cultures of tacrine with structurally (proflavine and 9-aminoacridine) or pharmacologically similar compounds (physostigmine), as well as structurally modified tacrine to determine if there was a structure activity relationship with regards to toxicity. Cytotoxicity was assessed by determination of extra- and intracellular amounts of lactate dehydrogenase. Cytotoxicity was assessed after a four-hour exposure over a test compound concentration range of 0 to 3 mM. Concentration-dependent cytotoxicity occurred with tacrine and all structurally related compounds. Physostigmine which is pharmacologically similar, but structurally different, did not induce cytotoxicity. Cytotoxic potency did not appear to be related to acetylcholinesterase inhibitory activity, while compounds with acridine structures induced cytotoxicity. Thus, in this in vitro model, cytotoxicity appears to be related to structure and not pharmacological action. Results of this study indicate that compounds structurally related to tacrine are cytotoxic because of the heterocyclic ring structure. Neither unsaturation of an aromatic ring of the heterocyclic compound, amino substitution of the heterocyclic rings, N-hydroxylation of the amino group, nor ring hydroxylation dramatically alter cytotoxicity.

Flow modulates myogenic responses in isolated microperfused rabbit afferent arterioles via endothelium-derived nitric oxide

Flow may be a physiological stimulus of the endothelial release of nitric oxide (NO) and prostaglandins (PGs). We tested the hypothesis that pressure-induced constriction of the glomerular afferent arteriole (Af-Art) is modulated by luminal flow via endothelial production of NO. We microdissected the terminal segment of an interlobular artery together with two Af-Arts, their glomeruli (GL) and efferent arterioles (Ef-Art). The two Af-Arts were perfused simultaneously from the interlobular artery, while one Ef-Art was occluded. Since the arteriolar perfusate contained 5% albumin, oncotic pressure built up in the glomerulus with the occluded Ef-Art and opposed the force of filtration, resulting in little or no flow through the corresponding Af-Art. Thus this preparation allowed us to observe free-flow and no-flow Af-Arts simultaneously during stepwise 30-mmHg increases in intraluminal pressure (from 30 to 120 mmHg). Pressure-induced constriction was weaker in free-flow than no-flow Af-Arts, with the luminal diameter decreasing by 11.1 +/- 1.7 and 25.6 +/- 2.3% (n = 30), respectively, at 120 mmHg. To examine whether flow modulates myogenic constriction through endothelium-derived NO and/or PGs, we examined pressure-induced constriction before and after (a) disruption of the endothelium, (b) inhibition of NO synthesis with NW-nitro-L-arginine methyl ester (L-NAME), or (c) inhibition of cyclooxygenase with indomethacin. Both endothelial disruption and L-NAME augmented pressure-induced constriction in free-flow but not no-flow Af-Arts, abolishing the differences between the two. However, indomethacin had no effect in either free-flow or no-flow Af-Arts. These results suggest that intraluminal flow attenuates pressure-induced constriction in Af-Arts via endothelium-derived NO. Thus flow-stimulated NO release may be important in the fine control of glomerular hemodynamics.