Quantitative evaluation of cardiac parasympathetic activity in normal and diabetic man

Heart rate and RR variation (the standard deviation of the mean RR interval for a 5-min period) were evaluated as measurements of cardiac parasympathetic nervous system activity in fasting supine diabetic (N = 22) and comparable age normal (N = 22) subjects. The rate of breathing did not effect heart rate, but was inversely related to the RR variation (r = 0.89, P less than 0.01). Heart rate was increased (P less than 0.0001) and RR variation decreased (P less than 0.05) during beta-adrenergic stimulation with isoproterenol and during parasympathetic blockade with atropine (both P less than 0.0001). Hence, the cardiac effects of beta-adrenergic stimulation may mimic the effects of diminished parasympathetic function. To evaluate parasympathetic control of RR variation, independently of possible effects of increased sympathetic activities, studies were performed during beta-adrenergic blockade with propranolol. RR variation during propranolol was less both in 14 diabetic subjects without clinical symptoms of autonomic neuropathy (P less than 0.005) and in 8 diabetics with clinical symptoms of autonomic neuropathy (P less than 0.001) when compared with 22 age-comparable normal subjects. The measurement of RR variation was very reproducible with a day-to-day coefficient of variation of 9.7 +/- 2.8% (x +/- SEM) in diabetic subjects with stable hyperglycemia. It is concluded that supine RR variation during a deep respiratory rate and during beta-adrenergic blockade is a sensitive, quantitative, and reproducible method to evaluate parasympathetic nervous activity in normal and diabetic subjects. Furthermore, cardiac parasympathetic activity may be diminished in diabetic subjects before clinical symptoms of autonomic neuropathy are evident.

Racial differences in performance of invasive cardiac procedures in a Department of Veterans Affairs Medical Center

Racial differences have recently been described in hospital practice, most notably with regard to cardiac procedure utilization. To evaluate the possible reasons behind these differences, we analyzed statistics generated from a surgical referral conference at a large, tertiary care Veterans Affairs hospital between the years 1988 and 1996. In this setting, there is no financial incentive for physicians to recommend or perform invasive procedures, as all physicians are salaried employees of the Veterans Administration. Furthermore, all patients presented at conference have already had cardiac catheterization and are felt to be potential candidates for surgery or angioplasty. Cardiac therapeutic procedures (surgery or percutaneous transluminal coronary angioplasty) were recommended for 1075 of 1474 (72.9%) Caucasian patients and 207 of 322 (64.3%) African-American patients (odds ratio 1.497, 95% confidence interval 1.160 to 1.932, p = 0.0022). Of those patients presented with the option of an invasive procedure, 32 of 207 (15.4%) African-American patients and 89 of 1075 (8.3%) Caucasian patients refused any invasive procedure (odds ratio 2.026, 95% confidence interval 1.311 to 3.130, p = 0.0025). We conclude that reluctance by African-American patients to undergo invasive cardiac procedures may help explain observed disparities in race-related cardiac care.

Quantitative evaluation of sympathetic and parasympathetic control of iris function

The use of quantitative measurements of pupil size as an index of autonomic nervous system (ANS) activity in normal and diabetic subjects is described. The dual innervation of the iris by the parasympathetic (PNS) and sympathetic (SNS) nervous system was demonstrated by measurement of steady-state pupil size before and after changes in ANS activity by pharmacologic agents. In the presence of total PNS blockade, dark-adapted pupil size was a reliable index of SNS activity to the iris. Latency time (time from light stimulation to initial pupil response) appeared to be a good index of PNS activity. However, increased SNS activity may also prolong the latency time. Thus, consideration of SNS activity is necessary when evaluating the latency time. In 25 diabetic subjects, there was evidence of impaired SNS activity (smaller dark-adapted pupil size during total PNS blockade) and PNS activity (prolonged latency time). In a subgroup of diabetic subjects without clinical manifestations of autonomic neuropathy and normal subjects, both dark-adapted pupil size during PNS blockade (SNS index) and latency time (PNS index) were abnormal. The coefficient of variation for these two indices was less than 5% in glycemic stable diabetic subjects. Thus, these two indices are reliable and sensitive measures of the SNS and PNS activity to the iris in normal and diabetic subjects.

Predictive value of in vitro colony and cluster formation in acute nonlymphocytic leukemia

Granulocytic-monocytic colony-forming activity of marrow cells was evaluated at presentation in 20 patients with acute nonlymphocytic leukemia (ANLL). A double-layer agar culture was employed to determine colony- and cluster-forming activity. All patients underwent induction chemotherapy with cytosine arabinoside and daunorubicin. Five patients died during induction. Eight of the 11 patients entering complete remission had absent or decreased colony and cluster growth of marrow cells. Four patients who failed to obtain a complete remission produced increased or only cluster growth in culture. Our data support the conclusions of others that decreased colony and cluster formation in vitro is associated with a more favorable response to induction chemotherapy for ANLL.

Unique subset of thymic epithelial cells defined by the expression of a novel neuroendocrine antigen

Murine monoclonal antibodies (MoAbs) were produced against a rat medullary thyroid carcinoma to identify neuroendocrine differentiation antigens. One of these antibodies (1D4) identified a novel 62- to 69-kDa antigen expressed by subsets of immune system epithelial and neuroendocrine cells. This antigen is expressed by distinct subsets of thymic epithelial and splenic reticular cells and is shared by discrete subsets of anterior pituitary and thyroid neuroendocrine cells. In the thymus, 1D4 expression identified a unique subset of stellate-shaped Ia+ medullary epithelial cells which did not react with thymosin alpha-1 antisera nor with the MoAb A2B5 specific for a GQ ganglioside expressed by thymic hormone-producing cells. The availability of the 1D4 MoAb should facilitate further characterization of 1D4+ immune system epithelial cells and may advance our understanding of neuroendocrine-immune system interactions.

Prolongation of porcine islet xenograft survival in mice after therapy with immunosuppressive peptides

BACKGROUND

Recently, peptides derived from the heavy chain of HLA-B2702 have been shown to modulate immune responses. In this study, we examined the use of these peptides for immunosuppression in a pig to mouse islet xenograft model.

METHODS

Purified porcine islets were transplanted in autoimmune (non-obese diabetic) and non-autoimmune (streptozotocin-injected CBA or C57/Bl6) diabetic mice. Various dosing regimens of HLA-derived peptides with and without antilymphocyte therapy were administered to recipient mice. Graft rejection was determined by daily serum glucose determinations, and, at selected time points, grafts were removed to demonstrate function and provide immunohistochemical examination.

RESULTS

HLA-derived peptides were demonstrated to prolong graft survival in both pretransplant and posttransplant treatment regimens. This effect was increased with concomitant antilymphocyte therapy.

CONCLUSIONS

Further elucidation of the mechanism of action of these immunomodulatory peptides may help in the development of novel immunosuppressive protocols.

Abstract P5-03-06: MEDI3039, a novel highly potent tumor necrosis factor (TNF)-related apoptosis inducing ligand (TRAIL) receptor agonist, induces apoptotic cell death in breast cancer cells

TRAIL receptor agonists are attractive anti-tumor agents because of their capability to induce apoptosis in cancer cells by activating death receptors 4 and 5 (DR4 and DR5) with little toxicity against normal cells. We previously reported that GST-TRAIL efficiently induced cell death in breast cancer cells, particularly mesenchymal triple negative breast cancer (TNBC) – so called basal B breast cancer cells (Rahman et al., Adv. Cancer Res. 2009). Recently, a newly developed multivalent TRAIL receptor agonist designed to activate DR5, has been shown to be a TRAIL super-agonist with significantly enhanced potency in multiple cancer cell lines (Swers et al., Mol Cancer Ther. 2013). We hypothesized that MEDI3039, developed from this TRAIL super-agonist, is a potential new therapeutic agent to be used in human breast cancer treatment.

As model systems, we used 19 breast cancer cell lines that can be categorized into 4 different groups: ER+, HER2 amplified, TNBC basal A and TNBC basal B. MEDI3039- or GST-TRAIL-induced cell death was analyzed by an MTS assay in 96 well format after 72h of treatment. MEDI3039- or GST-TRAIL-induced caspase activation was measured by Caspase-glo 3/7 assay. Z-VAD-FMK was used as a pan-caspase inhibitor. To verify the receptor for MEDI3039, siRNA against DR4 and DR5 were transfected to cells and tested in MTS assay and Western blotting.

MEDI3039 induced cell death in MDA-MB231 (TNBC basal B), and the IC50 was 4.71pM. By contrast, GST-TRAIL induced cell death in this cell line with an IC50 of 624 pM (a 132 fold difference). MEDI3039 and GST-TRAIL induced cell death was completely inhibited by Z-VAD-FMK, indicating that cell death was the result of caspase-mediated apoptotic pathway. Knockdown of DR5, but not DR4, inhibited MEDI3039-induced cell death, demonstrating that MEDI3039-mediated apoptosis requires DR5. MEDI3039 induced cell death in multiple breast cancer cell lines, but the sensitivity varied between cell lines from the four different subtypes. TNBC basal B group was the most sensitive (avg IC50= 1.4 pM), TNBC basal A group was next most sensitive (avg IC50 = 203 pM, HER2 amplified group was less sensitive (avg IC50 = 314 pM), and ER+ group was the least sensitive to MEDI3039 (avg IC50= 403 pM). This was similar to what was observed with GST-TRAIL. Importantly, MEDI3039 was at least 2 orders of magnitude more potent compared with GST-TRAIL in most cell lines tested. Drug combination experiments indicated that MEDI3039 has synergistic effect with multiple drugs, including cisplatin, MK1775. Animal breast cancer xenograft experiments are planned to test the efficacy of MEDI3039 in vivo. Further work to identify biomarker(s) that correlate with MEDI3039 sensitivity, and effective combinations that enhance the toxicity of MEDI3039 especially in the resistant breast cancer subtypes are ongoing. In conclusion, MEDI3039 is a potent TRAIL receptor agonist in breast cancer cells and has potential as a cancer drug in breast cancer patients, especially those with TNBC basal B.

Citation Format: Greer YE, Tice D, Lipkowitz S. MEDI3039, a novel highly potent tumor necrosis factor (TNF)-related apoptosis inducing ligand (TRAIL) receptor agonist, induces apoptotic cell death in breast cancer cells. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P5-03-06.

Immune rosettes of T and B lymphocytes in infertile women with endometriosis

We examined the cell-mediated immune response in women with pelvic endometriosis by quantitating their T and B lymphocytes. The study was conducted on heparinized peripheral blood and peritoneal fluid. The results were compared with those in a control group of women without evidence of endometriosis. Each patient underwent laparoscopy as part of her infertility evaluation. The ability of T cells to form rosettes with sheep erythrocytes was used to estimate the percentage of total and active T cells. B lymphocytes were quantitated by erythrocyte antibody complement binding capacity. In addition, T and B lymphocytes were assayed with the Immunobead technique using specific monoclonal antibodies. The helper T cell (T4) and suppressor T cell (T8) subsets of lymphocytes were evaluated with specific monoclonal antibodies coupled to microbeads. The results demonstrated an increased number of T and B cells in peritoneal fluid and peripheral blood from patients with endometriosis as compared with controls. Furthermore, the ratio T4:T8 was significantly increased in patients with endometriosis. These results suggest a cell-mediated immune response in the presence of endometriosis.

Importance of topical hypothermia to ensure uniform myocardial cooling during coronary artery bypass

Recent reports have suggested that the delivery of cardioplegia to regional myocardium is impaired in patients with severe coronary artery disease. This study was designed to determine whether or not topical hypothermia is a necessary adjunct to systemic hypothermia and potassium cardioplegia to provide adequate cooling in regional myocardium supplied by stenotic or occluded coronary arteries. Twenty-two patients ranging in age from 47 to 68 years were included in the study. Patients were placed on bypass and cooled to 28 degrees C. Temperature was measured over the right and left coronary artery distributions. The aorta was then cross-clamped and 1,000 cc of potassium blood cardioplegia, 5.7 degrees to 11 degrees C (mean 8.7 degrees), was infused into the aortic root at a mean pressure of 99 mmHg. Temperature was measured and 6 L of cold electrolyte (Plasma-lyte) solution, 2.3 degrees to 5.1 degrees C (mean 3.5) was poured over the heart into the pericardial well. The temperature measurements were then repeated. Myocardial temperature in regional myocardium supplied by normal coronary arteries after the injection of cardioplegia was less than 15 degrees C. However myocardium distal to a severe stenosis or complete occlusion was significantly warmer (p less than 0.001). Topical hypothermia reduced myocardial temperature to less than 15 degrees C in regional myocardium supplied by severely diseased vessels (p less than 0.001). These data demonstrate that the combination of systemic hypothermia and potassium cardioplegia alone does not provide adequate myocardial cooling in patients with severe coronary artery disease and emphasize the need for intraoperative myocardial temperature monitoring to ensure optimal protection during the ischemic period.

Natural killer cell activity in rats infused with Intralipid

The effect of Intralipid on the natural killer (NK) cell activity of healthy male Fisher 344 adult rats was investigated. They were cannulated via the right jugular vein and continuously infused for five days with: normal saline plus heparin, 5% Intralipid plus heparin, or 10% Intralipid plus heparin. Control groups comprised of cannulated rats receiving no infusion and rats undergoing no operative procedures. Following the five-day infusion, rats were exsanguinated under ether anesthesia and mononuclear cells (MNC) harvested from the peripheral blood. NK activity was measured in a standard four hour 51Cr release assay against YAC-1 target cells. NK cell activity in rats infused with 5% Intralipid did not differ significantly from rats in both control groups or rats infused with saline. Infusion of rats with 10% Intralipid resulted in a significant increase in NK activity compared with all other groups.

Abstract P4-07-05: MEDI3379, an antibody against HER3, is active in HER2-driven human breast tumor models

HER3 (ERBB3) is a member of the EGFR/HER family of receptor tyrosine kinases (RTK), consisting of EGFR, HER2, HER3 and HER4. Unlike the other HER family members, HER3 lacks intrinsic tyrosine kinase activity and therefore needs to form heterodimers with EGFR, HER2 or other kinase-proficient RTKs to be functionally active. Dimerization is induced by overexpression of EGFR or HER2 in a ligand-independent (LI) manner. In this process HER3 acts as a driver in divergent cancer types including HER2-positive breast cancer (BC) via induction of the PI3K-AKT pathway. Alternatively, heregulin (NRG1/HRG), the major HER3 ligand, induces a conformational shift in HER3 which leads to dimer formation with a partner RTK in a ligand-dependent (LD) manner.

We have developed an antagonistic human monoclonal antibody against HER3, termed MEDI3379, and tested it in multiple breast cancer cell lines. We observed effective suppression of constitutive pHER3 and pAKT with MEDI3379, leading to anti-proliferation effects in cell culture models. Preclinical evaluation of MEDI3379 demonstrated antitumor activity in several orthotopic BC xenografts in nude mice which did not express HRG. For example, the BC xenograft model BT474 with amplified HER2 responded to MEDI3379 (65% dTGI). In conclusion, our findings with targeting of HER3 in mouse models support continued development of MEDI3379 for cancer.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P4-07-05.