High bandwidth atomic magnetometery with continuous quantum nondemolition measurements

We describe an experimental study of spin-projection noise in a high sensitivity alkali-metal magnetometer. We demonstrate a fourfold improvement in the measurement bandwidth of the magnetometer using continuous quantum nondemolition measurements. Operating in the scalar mode with a measurement volume of 2 cm3 we achieve magnetic field sensitivity of 22 fT/Hz(1/2) and a bandwidth of 1.9 kHz with a spin polarization of only 1%. Our experimental arrangement is naturally backaction evading and can be used to realize sub-fT sensitivity with a highly polarized spin-squeezed atomic vapor.

Radiation dose-benefit analysis of hematopoietic stem cell grafting for tolerence induction across MHC barriers in living related donor renal allograft recipients

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Background: Donor specific immunologic tolerance protects an allograft from chronic rejection and allows discontinuation of chronic immunosuppressive therapy. Ahmedabad-tolerance induction protocol (A-TIP) allows grafting in living related donor (LRD) renal allograft recipients with persistent low-level MLHC. Present study aims to define of the ideal radiation dose needed for tolerance induction in patients undergoing A-TIP. Methods: 210 consecutive end stage renal disease patients recruited between May '05 through Mar '07 underwent renal transplantation (RTx) following A-TIP and negative Lymphocytotoxicity cross match (LCM). A-TIP includes (a) 2 DLI's (b) low intensity conditioning, and (c) HSC grafting.The conditioning regimen included fractionated low dose target specific radiation, cyclosporine, cyclophosphamide, anti T-cell a.b and treosulfan. All patients underwent subtotal lymphoid irradiation (STLI) targeting spleen, abdominal, iliac and inguinal lymph nodes, thoraco-lumbar vertebra and 75% of pelvis. Patients were randomized into 3 groups of 70 each: STLI 600, STLI 800, STLI 1000, corresponding to doses of 600cgy, 800cgy and 1000cgy delivered conventionally using 6MV/15MV photons. Unfractionated HSC procured from donor BM was administered into portal circulation, within 24 hours of achieving CD4+/CD8+ T cell count ≤ 10% of baseline. Donor specific cytotoxic antibodies were eliminated before RTx. Immunosuppression (ISp) was withdrawn 3–6 mo after RTx for patients with consistently positive chimerism. Tolerance - Robust (R), Prope (P) and Metastable (M) is defined as RT: Stable allograft function (fn.) for >100 days without ISp; PT: Early adequate, stable grafts fn. with no rejection episodes on minimum ISp; MT: Adequate graft fn. on ISp with single episode of steroid responsive ac. rejection. Results: See Table. Conclusions: The safe and effective dose for tolerance induction in LRD renal transplantation is 1000 cGy.

[Table: see text]

No significant financial relationships to disclose.

Combined spinal-epidural anesthesia for renal transplantation

INTRODUCTION

A patient undergoing renal transplantation presents unique problems to the anesthetist, as almost every body system is affected. The combined spinal-epidural technique has become popular in lower abdominal surgeries because it offers the advantages of both spinal and epidural techniques. We review our experience of combined spinal-epidural technique in patients undergoing renal transplantation with respect to demographics, intraoperative anesthesia, hemodynamics, postoperative analgesia, and untoward adverse events.

MATERIALS AND METHOD

Fifty consecutive patients scheduled for elective renal transplantation over a period of 4 months who consented for combined spinal-epidural anesthesia were enrolled in the study. Combined spinal-epidural anaesthesia was performed using a double-space technique in the right lateral position. Intraoperative monitoring included electrocardiography, pulse oximetry, noninvasive blood pressure, central venous pressure, and urinary output after clamp release. Intravenous fluids, colloids, and blood products were infused so as to keep the central venous pressure between 12 and 15 mm Hg. Postoperative analgesia was provided with buprenorphine via an epidural catheter. We noted intraoperative and postoperative complications.

RESULTS

Neuraxial blockade was satisfactory in all but four patients who required supplementation with general anesthesia for unduly prolonged surgery. There were no significant intraoperative hemodynamic changes. The total intravenous fluid used during surgery was 64.24 +/- 12.3 mL/kg. During the postoperative period, all patients had good postoperative pain relief with no incidence of epidural hematoma.

CONCLUSION

Combined spinal-epidural anesthesia proved to be a useful regional anesthetic technique, combining the reliability of spinal block and versatility of epidural block for renal transplantation.

Quantitative detection of circulating endothelial cells in vasculitis: comparison of flow cytometry and immunomagnetic bead extraction

BACKGROUND

Circulating endothelial cells (CECs) are biomarkers for endothelial cell (EC) injury and are quantified using immunomagnetic bead extraction (IBE), or flow cytometry (FC). Reports suggest that there is good agreement between these methods for CEC quantification.

OBJECTIVES

We examined levels of agreement between these techniques in children with systemic vasculitis.

METHODS

We added HUVEC or human pulmonary artery EC to whole blood to optimize FC gating strategies for EC. EC-optimized FC was then compared with IBE for CEC enumeration in 25 children with vasculitis and 20 healthy controls.

RESULTS

Using Bland-Altman analysis, agreement between IBE and EC-optimized FC was poor in children with vasculitis (n = 25) and healthy controls (n = 20): IBE consistently detected higher values than the EC-optimized FC method: the mean difference between the two techniques was 60 CECs mL(-1), 95% CI +/-374 CECs mL(-1) (paired analyses of 45 individuals). Agreement was poorest for vasculitis patients: mean difference (IBE - EC-optimized FC) 120 CECs mL(-1), 95% CI +/-460 CECs mL(-1) (P = 0.018). We identified three reasons for this discrepancy: (i) sub-optimal FC gating parameters previously used for detecting CECs; (ii) inherent lack of sensitivity of FC compared with IBE for CEC rare event detection; and (iii) use of lysis buffers required for FC causing CEC lysis.

CONCLUSIONS

There was poor agreement between EC-optimized FC and IBE for the quantification of CECs from children with active vasculitis and controls. We emphasize that in this clinical setting the two techniques are not directly comparable when comparing results obtained using these different methodologies.

Rhombencephalosynapsis: prenatal imaging and autopsy findings

OBJECTIVES

Rhombencephalosynapsis is a rare, but increasingly recognized, brain malformation characterized by congenital fusion of the cerebellar hemispheres and absence of the vermis. Rhombencephalosynapsis is associated with significant developmental delay, seizures and involuntary head movements. We report four cases, with correlation of prenatal and postnatal imaging and autopsy findings.

METHODS

Over a 2-year period, four cases of rhombencephalosynapsis were diagnosed in the perinatal period, three in one center and one in another center. The clinical cases were reviewed, and correlation was made between the prenatal and postnatal imaging and autopsy findings where available.

RESULTS

All cases presented initially with ventriculomegaly on prenatal ultrasound examination. Subsequent magnetic resonance imaging (MRI) established the diagnosis in two cases and postnatal MRI established the diagnosis in a further two cases. Autopsy was available and confirmed the diagnosis in two cases. In one case the pregnancy was terminated, two infants died in the neonatal period and one died in infancy.

CONCLUSIONS

The cases in this perinatal series of rhombencephalosynapsis showed a very poor prognosis. The presence of ventriculomegaly on prenatal ultrasound imaging should alert the physician to consider rhombencephalosynapsis in the differential diagnosis. MRI appears to be the imaging modality of choice in establishing the diagnosis.

Zero-field remote detection of NMR with a microfabricated atomic magnetometer

We demonstrate remote detection of nuclear magnetic resonance (NMR) with a microchip sensor consisting of a microfluidic channel and a microfabricated vapor cell (the heart of an atomic magnetometer). Detection occurs at zero magnetic field, which allows operation of the magnetometer in the spin-exchange relaxation-free (SERF) regime and increases the proximity of sensor and sample by eliminating the need for a solenoid to create a leading field. We achieve pulsed NMR linewidths of 26 Hz, limited, we believe, by the residence time and flow dispersion in the encoding region. In a fully optimized system, we estimate that for 1 s of integration, 7 x 10(13) protons in a volume of 1 mm(3), prepolarized in a 10-kG field, can be detected with a signal-to-noise ratio of approximately 3. This level of sensitivity is competitive with that demonstrated by microcoils in 100-kG magnetic fields, without requiring superconducting magnets.

T cell activation profiles in Kawasaki syndrome

Superantigens (SAgs) are potent stimulators of T cells bearing specific Vbeta T cell receptors (TCR) and may play a role in the pathogenesis of Kawasaki syndrome (KS), although despite 15 years of intense study this area remains controversial. Because SAgs can cause Vbeta restricted T cell activation in the absence of Vbeta skewing the aims of this study were to describe a flow cytometric protocol to study both CD4 and CD8 Vbeta repertoires, and CD69 expression across the CD4 and CD8 Vbeta repertoire in children with KS. Sixteen children with KS were studied. There was no significant increase in overall peripheral blood CD4 or CD8 T cell activation as determined by CD69 expression. However, Vbeta restricted CD4 and/or CD8 activation was observed in eight of 11 (72%) of the KS patients, a finding not observed in healthy controls. Thirteen of 16 (81%) of the KS patients had evidence of either Vbeta skewing (particularly CD4 Vbeta2 and Vbeta5.1) and/or Vbeta restricted activation. Three patients had Vbeta restricted activation in the absence of skewing. We suggest that these preliminary observations highlight the many layers of complexity when considering T cell activation in KS, which could explain some of the conflicting studies regarding peripheral blood T cell activation and Vbeta skewing. It is likely that in order to move forward with this debate a combination of detailed microbiological, immunological and molecular techniques applied to individual patients will be required ultimately to prove or refute the SAg hypothesis of KS.