New frontiers in applied veterinary point‐of‐capture diagnostics: Toward early detection and control of zoonotic influenza

Among the chief limitations in achieving early detection and control of animal‐origin influenza of pandemic potential in high‐risk livestock populations is the existing lag time between sample collection and diagnostic result. Advances in molecular diagnostics are permitting deployment of affordable, rapid, highly sensitive, and specific point‐of‐capture assays, providing opportunities for targeted surveillance driving containment strategies with potentially compelling returns on investment. Interrupting disease transmission at source holds promise of disrupting cycles of animal‐origin influenza incursion to endemicity and limiting impact on animal production, food security, and public health. Adoption of new point‐of‐capture diagnostics should be undertaken in the context of promoting robust veterinary services systems and parallel support for operationalizing pre‐authorized plans and communication strategies that will ensure that the full potential of these new platforms is realized.     

Practices and ethical concerns regarding preimplantation diagnosis. Who regulates preimplantation genetic diagnosis in Brazil?

Preimplantation genetic diagnosis (PGD) was originally developed to diagnose embryo-related genetic abnormalities for couples who present a high risk of a specific inherited disorder. Because this technology involves embryo selection, the medical, bioethical, and legal implications of the technique have been debated, particularly when it is used to select features that are not related to serious diseases. Although several initiatives have attempted to achieve regulatory harmonization, the diversity of healthcare services available and the presence of cultural differences have hampered attempts to achieve this goal. Thus, in different countries, the provision of PGD and regulatory frameworks reflect the perceptions of scientific groups, legislators, and society regarding this technology. In Brazil, several texts have been analyzed by the National Congress to regulate the use of assisted reproduction technologies. Legislative debates, however, are not conclusive, and limited information has been published on how PGD is specifically regulated. The country requires the development of new regulatory standards to ensure adequate access to this technology and to guarantee its safe practice. This study examined official documents published on PGD regulation in Brazil and demonstrated how little direct oversight of PGD currently exists. It provides relevant information to encourage reflection on a particular regulation model in a Brazilian context, and should serve as part of the basis to enable further reform of the clinical practice of PGD in the country.     

Motion‐compensated b‐tensor encoding for in vivo cardiac diffusion‐weighted imaging

Motion is a major confound in diffusion‐weighted imaging (DWI) in the body, and it is a common cause of image artefacts. The effects are particularly severe in cardiac applications, due to the nonrigid cyclical deformation of the myocardium. Spin echo‐based DWI commonly employs gradient moment‐nulling techniques to desensitise the acquisition to velocity and acceleration, ie, nulling gradient moments up to the 2nd order (M2‐nulled). However, current M2‐nulled DWI scans are limited to encode diffusion along a single direction at a time. We propose a method for designing b‐tensors of arbitrary shapes, including planar, spherical, prolate and oblate tensors, while nulling gradient moments up to the 2nd order and beyond. The design strategy comprises initialising the diffusion encoding gradients in two encoding blocks about the refocusing pulse, followed by appropriate scaling and rotation, which further enables nulling undesired effects of concomitant gradients. Proof‐of‐concept assessment of in vivo mean diffusivity (MD) was performed using linear and spherical tensor encoding (LTE and STE, respectively) in the hearts of five healthy volunteers. The results of the M2‐nulled STE showed that (a) the sequence was robust to cardiac motion, and (b) MD was higher than that acquired using standard M2‐nulled LTE, where diffusion‐weighting was applied in three orthogonal directions, which may be attributed to the presence of restricted diffusion and microscopic diffusion anisotropy. Provided adequate signal‐to‐noise ratio, STE could significantly shorten estimation of MD compared with the conventional LTE approach. Importantly, our theoretical analysis and the proposed gradient waveform design may be useful in microstructure imaging beyond diffusion tensor imaging where the effects of motion must be suppressed.     

CTLA4 antagonists in phase I and phase II clinical trials,current status and future perspectives for cancer therapy

Introduction: In cancer, the immune response to tumor antigens is often suppressed by inhibitors and ligands. Checkpoint blockade, considered one of the most promising frontiers for anti-cancer therapy, aims to stimulate the immune anti-cancer response. Agents such as cytotoxic T lymphocyte–associated antigen 4 (CTLA-4) inhibitors offer prolonged survival with manageable side effects.

Areas covered: We summarize the recent clinical successes of CTLA-4 inhibitors and place a strong emphasis on those in early phase clinical trials, often in combination with other immune check-point inhibitors, i.e., programmed cell death protein 1 (PD-1) and BRAF/mitogen-activated protein kinase inhibitors.

Expert opinion: Recent phase I and phase II clinical trials confirm the efficacy of anti-CTLA-4 therapy for treatment of cancers such as renal cell carcinoma. These studies also indicated increased efficacy with combined immune checkpoint blockade with PD-1 or Ras/Raf/mitogen-activated protein kinase/ERK kinase (MEK)/extracellular-signal-regulated kinase (ERK) inhibitors. Researchers must search for new immune targets that may enable more effective and safe immune checkpoint blockade and cancer therapy. This goal may be achieved by next-generation combination therapies to overcome immune checkpoint therapy resistance.     

Contribution of Calcium Channel Subtypes to the Intracellular Calcium Signal in Sensory Neurons: The Effect of Injury

Background: Although the activation-induced intracellular Ca2+ signal is disrupted by sensory neuron injury, the contribution of specific Ca2+ channel subtypes is unknown.

Methods: Transients in dissociated rat dorsal root ganglion neurons were recorded using fura-2 microfluorometry. Neurons from control rats and from neuropathic animals after spinal nerve ligation were activated either by elevated bath K+ or by field stimulation. Transients were compared before and after application of selective blockers of voltage-activated Ca2+ channel subtypes.

Results: Transient amplitude and area were decreased by blockade of the L-type channel, particularly during sustained K+ stimulation. Significant contributions to the Ca2+ transient are attributable to the N-, P/Q-, and R-type channels, especially in small neurons. Results for T-type blockade varied widely between cells. After injury, transients lost sensitivity to N-type and R-type blockers in axotomized small neurons, whereas adjacent small neurons showed decreased responses to blockers of R-type channels. Axotomized large neurons were less sensitive to blockade of N- and P/Q-type channels. After injury, neurons adjacent to axotomy show decreased sensitivity of K+-induced transients to L-type blockade but increased sensitivity during field stimulation.     

Intracardiac transplantation of a mixed population of bone marrow cells improves both regional systolic contractility and diastolic relaxation.

BACKGROUND: Pre-clinical and clinical studies suggest that transplantation of bone marrow-derived stem cells can improve global cardiac function. However, no quantitative assessment of regional systolic contraction and correlation with phenotype has been made. Therefore, we used our model of cryoinfarcted rabbit myocardium for intracardiac transplantation of a mixed population of bone marrow-derived cells and assessed both regional function and myogenic conversion of the cells. METHODS: Nineteen New Zealand white rabbits underwent cryoinjury of the left ventricle. Autologous bone marrow (BM) cells were expanded in vitro. After 2 weeks, either 1 x 10(8) mixed BM-derived progenitor cells (BM group, n = 11) or vehicle (control group, n = 8) were injected into the cryoinjured region. Regional systolic function was measured using micromanometry and sonomicrometry before and 4 weeks after cell injection; cell phenotype was evaluated histologically. RESULTS: All animals in the BM group significantly improved both systolic shortening (0.11 +/- 0.7 vs -0.05 +/- 0.05 mm in the control group, p < 0.05) and regional stroke work when compared with control (9.6 +/- 2.4 vs -1.2 +/- 1.2 mm . mm Hg, p < 0.003). In addition, the BM group had improved global diastolic function, as measured by minimum dP/dt and end-diastolic pressure. On histologic assessment, BM cells differentiated toward a myogenic phenotype. CONCLUSIONS: Transplanting a mixed population of marrow-derived cells that can adopt a myogenic phenotype improves regional contractility and diastolic relaxation after myocardial infarction.     

Successful regrafting of a transplanted liver

We report on the successful regrafting of a transplanted liver. The donor liver was first grafted into a patient suffering from cryptogenic cirrhosis; the patient died 1 day after the elective transplantation of cerebral bleeding. The well-functioning graft was harvested again and transferred to our institution. After another 12 h of cold ischemia, the liver was reperfused in an urgently registered patient with recurrence of hepatitis B in his first graft. The transplantation was successfully performed and the patient is now doing well, more than 5 months after regrafting with the reused liver. Received: 21 October 1996 Received after revision: 9 January 1997 Accepted: 27 January 1997     

Pituitary responsiveness to GH-releasing hormone, GH-releasing peptide-2 and thyrotrophin-releasing hormone in critical illness

OBJECTIVE Protein hypercatabolism and preservation of fat depots are hallmarks of critical illness, which is associated with blunted pulsatile GH secretion and low circulating IGF-I, TSH, T4 and T3. Repetitive TRH administration is known to reactivate the pituitary-thyroid axis and to evoke paradoxical GH release in critical illness. We further explored the hypothalamic-pituitary function in critical illness by examining the effects of GH-releasing hormone (GHRH) and/or GH-releasing peptide-2 (GHRP-2) and TRH administration. PATIENTS AND DESIGN Critically ill adults (n=40; mean age 55 years) received two i.v. boluses with a 6-hour interval (0900 and 1500 h) within a cross-over design. Patients were randomized to receive consecutively placebo and GHRP-2 (n=10), GHRH and GHRP-2 (n=10), GHRP-2 and GHRH+GHRP-2 (n=10), GHRH+GHRP-2 and GHRH+GHRP-2+TRH (n=10). The GHRH and GHRP-2 doses were 1μg/kg and the TRH dose was 200μg. Blood samples were obtained before and 20, 40, 60 and 120 minutes after each injection. MEASUREMENTS Serum concentrations of GH, T4, T3, rT3, thyroid hormone binding globulin (TBG), IGF-I, insulin and cortisol were measured by RIA; PRL and TSH concentrations were determined by IRMA. RESULTS Critically ill patients presented a striking GH response to GHRP-2 (mean±SEM peak GH 51±9 μg/l in older patients and 102±2μg/l in younger patients; P=0.005 vs placebo). The mean GH response to GHRP-2 was more than fourfold higher than to GHRH (P=0.007). In turn, the mean GH response to GHRH+GHRP-2 was 2.5-fold higher than to GHRP-2 alone (P=0.01), indicating synergism. Adding TRH to the GHRH+GHRP-2 combination slightly blunted this mean response by 18% (P=0.01). GHRP-2 had no effect on serum TSH concentrations whereas both GHRH and GHRH+GHRP-2 evoked an increase in peak TSH levels of 53 and 32% respectively. The addition of TRH further increased this TSH response < ninefold (P=0.005), elicited a 60% rise in serum T3 (P=0.01) and an 18% increase in T4 (P=0.005) levels, without altering rT3 or TBG levels. GHRH and/or GHRP-2 induced a small increase in serum PRL levels. The addition of TRH magnified the PRL response 2.4-fold (P=0.007). GHRP-2 increased basal serum cortisol levels (531±29nmol/l) by 35% (P=0.02); GHRH provoked no additional response, but adding TRH further increased the cortisol response by 20% (P=0.05). CONCLUSIONS The specific character of hypothalamic-pituitary function in critical illness is herewith extended to the responsiveness to GHRH and/or GHRP-2 and TRH. The observation of striking bursts of GH secretion elicited by GHRP-2 and particularly by GHRH+GHRP-2 in patients with low spontaneous GH peaks opens the possibility of therapeutic perspectives for GH secretagogues in critical care medicine.