Optoelectronic oscillator stabilized to an intra-loop Fabry-Perot cavity by a dual servo system

We report construction and characterization of an optoelectronic oscillator (OEO), which is stabilized to an intra-loop Fabry-Perot cavity by a dual servo system. In addition to providing strong mode selection and increasing the Q factor by adding significant loop length, the cavity serves as a stable frequency reference. In order to fully exploit the stability we employ a dual servo system. Carrier frequency is locked to the cavity mode by using Pound-Drever-Hall technique. The OEO loop length is adjusted by comparing the phase difference between the carrier-sideband beat signals at upstream and downstream sides of the cavity so that the OEO mode spacing is commensurate with the free spectral range of the cavity. This dual servo system and additional stabilizations of the seed laser frequency to a cesium transition and the laser power result in an order of magnitude improvement in OEO frequency stability over a previous work using a free-running Fabry-Perot cavity. Long term Allan deviation of the OEO is 6 x 10(-8). It represents 4 x 10(-4)of the cavity resonance linewidth. We also discuss possibility of relating the OEO frequency to an atomic transition as an absolute frequency reference.

Production of a coherent pair of light beams with a microwave frequency difference from a single extended-cavity diode laser

We produced a pair of coherent laser beams with a 3-GHz frequency difference by optically phase locking two modes from a single, multimode extended-cavity diode laser. This method is complementary to either a direct modulation or an optical phase locking of two independent lasers. A large differential frequency shift between the two modes of the laser allows efficient phase locking. We developed a simple theory to account for the large differential frequency shift. Allan deviation of the beat frequency when the two modes are phase-locked drops as an inverse of the measurement time and it reaches 10(-14) when the time is 1 h. Coherent population trapping spectroscopy of Rb atoms using the phase-locked beams resulted in a spectrum as narrow as that of the case using direct modulation by a stable frequency synthesizer.

Prognostic and predictive values of carbonic anhydrase IX (CAIX) and pathologic features in patients with metastatic clear cell renal cell carcinoma receiving targeted therapy

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Background: Tumor Carbonic Anhydrase IX (CAIX) expression and histologic features can predict outcome in patients with metastatic renal cell carcinoma (mRCC) treated with immunotherapy. We sought to investigate the prognostic and predictive utility of such features in patients receiving VEGF-targeted therapy. Methods: We identified 118 patients with mRCC initiating first- line VEGF-targeted therapy including 94 with clinical data, clear cell histology and available tissue. Tumors were evaluated for specific histologic features and for CAIX expression by immunohistochemistry using the MN75 antibody. The relationship between these pathology findings and tumor shrinkage and other treatment outcomes was assessed. Results: Higher tumor clear cell component was independently associated with greater tumor shrinkage (p=0.02), response (p=0.02) and treatment duration (p=0.02). Patients with high vs. low tumor CAIX expression had mean tumor shrinkages of -12% vs. -5%, respectively (p=.38). There was heterogeneity in tumor responsiveness to sunitinib or sorafenib according to CAIX status (p=0.055 for interaction): mean shrinkage was -17% vs. -25% (mean difference +8%, 95% CI -14% to +31%) for sunitinib-treated patients with high vs. low tumor CAIX expression compared to -13% vs. +9% (mean difference -22%, 95% CI -42% to -1%) for sorafenib-treated patients. Conclusions: Patients with higher clear cell component in their tumors are likely to experience superior clinical benefit from VEGF-targeted therapy. Although CAIX expression was not found to be of prognostic value in patients with clear cell mRCC treated with VEGF-targeted therapy, it may be a predictive biomarker for response to sorafenib treatment.

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Polarization orthogonalizer for a pair of laser beams with nearly equal frequencies

We have demonstrated a device to produce an overlapping pair of orthogonally polarized laser beams with a 3 GHz frequency offset out of a single laser beam containing the two frequency components with the same linear polarization. Our design is based on a Michelson interferometer formed by a polarizing beam splitter and two quarter-waveplates. Such a device can be used to make the polarization states of a carrier and a sideband produced through modulation mutually orthogonal. An orthogonally polarized pair of coherent laser beams can be used for an interferometric measurement of a small displacement in a heterodyne scheme or to produce a large-contrast coherent population trapping signal from alkali metal atoms. As a demonstration we used the device to achieve 40% contrast for a coherent population trapping signal from a rubidium vapor cell.

Unexpected power-law stress relaxation of entangled ring polymers

After many years of intense research, most aspects of the motion of entangled polymers have been understood. Long linear and branched polymers have a characteristic entanglement plateau and their stress relaxes by chain reptation or branch retraction, respectively. In both mechanisms, the presence of chain ends is essential. But how do entangled polymers without ends relax their stress? Using properly purified high-molar-mass ring polymers, we demonstrate that these materials exhibit self-similar dynamics, yielding a power-law stress relaxation. However, trace amounts of linear chains at a concentration almost two decades below their overlap cause an enhanced mechanical response. An entanglement plateau is recovered at higher concentrations of linear chains. These results constitute an important step towards solving an outstanding problem of polymer science and are useful for manipulating properties of materials ranging from DNA to polycarbonate. They also provide possible directions for tuning the rheology of entangled polymers.

Doxycycline clearance of experimentally induced chronic Ehrlichia canis infection in dogs

BACKGROUND

Ineffective clearance of Ehrlichia canis after doxycycline administration has been reported despite the fact that the recommended treatment for canine ehrlichiosis is doxycycline. The effectiveness of doxycycline in clearing E canis infection from the blood and tissues of dogs requires additional evaluation.

HYPOTHESIS

Doxycycline (5 mg/kg PO q12h), administered for 4 weeks, will eliminate E canis infection from the blood and tissues of experimentally infected dogs.

ANIMALS

Fifteen Walker hound-mixed breed dogs were inoculated subcutaneously with E canis-infected canine histiocytic cells 4 months before doxycycline treatment.

METHODS

Four dogs were treated with doxycycline (5 mg/kg PO q12h for 3 weeks), 5 dogs were treated with doxycycline at the same dosage for 4 weeks, and 5 control dogs were not treated. Dexamethasone (0.4 mg/kg i.v.) was given after treatment to precipitate recrudescence of any remaining E canis organisms. Platelet counts, anti-E canis immunofluorescent antibodies, and polymerase chain reaction (PCR) detection of E canis deoxyribonucleic acid (DNA) in blood and tissues were evaluated.

RESULTS

E canis DNA was not detected in the blood and tissues of doxycycline-treated dogs after treatment. Platelet counts were within reference intervals, and E canis antibodies decreased. Spontaneous clearance of E canis infection occurred in 2 of 5 control dogs. Three control dogs had E canis DNA detected in blood and tissues, platelet counts remained low or within the reference interval, and E canis antibodies remained high.

CONCLUSIONS AND CLINICAL IMPORTANCE

As administered in this study, doxycycline cleared E canis from the blood and tissues of experimentally infected dogs.

Investigation of the corticotropin-releasing hormone-proopiomelanocortin axis in various skin tumours

BACKGROUND

Various types of external stress cause the skin and central neuroendocrine system to express corticotropin-releasing hormone (CRH)-proopiomelanocortin (POMC) axis-related hormones. However, the precise role of the CRH-POMC axis-related hormones in various skin tumours is unclear.

OBJECTIVES

This study examined expression patterns of the CRH-POMC axis-related hormones in skin tumours.

METHODS

The production of CRH, adrenocorticotropic hormone (ACTH) and alpha-melanocyte-stimulating hormone (alpha-MSH) in various tumour cell lines including HaCaT and primary keratinocytes was examined using an enzyme-linked immunosorbent assay. Immunohistochemical analysis of the skin tumours was also performed.

RESULTS

CRH, ACTH and alpha-MSH were strongly expressed in malignant skin tumour cell lines such as G-361 and DX-3 (both malignant melanoma, MM). However, normal and haematological malignancy cell lines did not express the CRH-POMC axis-related hormones. Immunohistochemical analysis of the skin tumours showed that MM (80%), squamous cell carcinoma (SCC, 70%) and basal cell carcinoma (BCC, 10%) had strong immunoreactivity (++/+++) for CRH. Strong ACTH and alpha-MSH expression was observed in MM (70% and 50%, respectively), SCC (80% and 60%, respectively) and BCC (70% and 50%, respectively).

CONCLUSIONS

We report that an increase in the level of the CRH-POMC axis-related hormones is associated with malignant skin tumours such as MM. These results highlight the importance of the CRH-POMC axis-related hormones in the malignant tendency of skin tumours.

Induction of leukemic-cell-specific cytotoxic T lymphocytes by autologous monocyte-derived dendritic cells presenting leukemic cell antigens

Leukemic-dendritic cells (leukemic-DCs) have certain limitations, which include difficult generation in 30-40% of patients, and low levels of expression of several key molecules. Therefore, an alternative approach using monocyte-derived DCs pulsed with tumor antigens is required. We investigated the possibility of immunotherapy for AML using leukemic-cell-specific cytotoxic T lymphocytes that were stimulated in vitro by autologous DCs pulsed with tumor antigens. To generate DCs, CD14(+) cells were isolated from peripheral blood mononuclear cells using magnetic-activated cell sorting, and cultured in the presence of GM-CSF and IL-4. On day 6, maturation of DCs was induced by addition of cytokine cocktail (TNF-alpha, IL-1beta, IL-6, and prostaglandin E(2)) for 2 days, and then the mature DCs were pulsed with whole leukemic cell lysates or apoptotic leukemic cells. There were no differences in the phenotypic expressions of mature DCs generated by pulsing with or without leukemic antigens. The mature DCs pulsed with tumor cell lysates or apoptotic leukemic cells showed a higher allostimulatory capacity for allogeneic CD3(+) T cells as compared with mature non-pulsed DCs. Autologous CD3(+) T cells stimulated by the mature pulsed DCs showed more potent cytotoxic activities against autologous leukemic cells than those stimulated by mature non-pulsed DCs. These results suggest that use of DCs pulsed with leukemic cell lysates or apoptotic leukemic cells is a feasible alternative immunotherapeutic approach to overcome the limitations of leukemic-DCs for the treatment of AML patients.

Kinetic studies on Korean serum cis-AB enzymes reveal diminished A and B transferase activities

BACKGROUND

cis-AB enzymes are rare glycosyltransferases that synthesize both blood group A and B antigens. We have identified a large cohort of Korean cis-AB blood donors and studied the N-acetylgalactosaminyltransferase (glycosyltransferase A, GTA) and galactosyltransferase (glycosyltransferase B, GTB) activity of their cis-AB serum enzymes.

MATERIALS AND METHODS

The cis-AB01 allele was identified by PCR-RFLP (polymerase chain reaction-restriction fragment length polymorphism) in 60 donors collected at the Gwangju-Chonnam Red Cross Blood Center. Enzyme assays of this cis-AB enzyme were performed on available serum samples from 16 donors with the cis-AB01/O genotype and three with the cis-AB01/A genotype.

RESULTS

In cis-AB donors with an O allele, both the GTA and GTB activity of the cis-AB enzyme were markedly reduced compared to normal A and B controls (29% and 27%, respectively). This is consistent with the behaviour predicted from kinetic studies of a recombinant model of the corresponding AAAB enzyme.

CONCLUSION

Although variable, cis-AB enzymes feature reduced GTA and GTB activities.

SUMMARY

Cis-AB enzymes feature variable but reduced GTA and GTB activities with relatively weaker GTB activity, consistent with the weak agglutination present on forward typing with anti-B.

Chimerism and mosaicism are important causes of ABO phenotype and genotype discrepancies

Discrepancies between blood group genotype and RBC phenotype are important to recognize when implementing DNA-based blood grouping techniques. This report describes two such cases involving the ABO blood group in the Korean population. Propositus #1 was a 22-year-old healthy man undergoing pretransfusion testing for minor surgery. Propositus #2 was a 23- year-old male blood donor. RBCs from both propositi were determined to be group AB and demonstrated unusual agglutination patterns on forward typing, which were inconsistent with their ABO genotype determined by allele-specific (AS) PCR. RBCs from propositus #1 demonstrated mixed field agglutination with both anti-A and -B, while RBCs from propositus #2 demonstrated mixed field only with anti-A reagents. Both had B/O genotypes by AS-PCR. Cloning and sequencing of ABO exons 6 and 7 revealed three alleles in both propositi: propositus #1: A102/B101/O04; propositus #2: A102/B101/O01. A panel of nine short-tandem repeat (STR) loci was tested on DNA extracted from blood, buccal mucosal cells, and hair from the propositi and on DNA isolated from their parents' blood. In all tissues tested from propositus #1, three loci demonstrated a double paternal and a single maternal DNA contribution, indicating that he was a chimera or a mosaic; in those from propositus # 2, one STR locus demonstrated a double paternal DNA contribution, indicating that he was a tetragametic chimera. Chimerism and mosaicism are uncommon but important causes of ABO genotype and phenotype discrepancies. The evaluation of patients and donors with unusual or unexpected serology in pretransfusion testing and consensus ABO alleles may include the evaluation of STR loci to detect these phenomena.

The genetic and phenotypic basis of blood group A subtypes in Koreans

A serological and genetic study of Korean blood donors with phenotypic group A subtypes was performed. There were 176 donors with phenotypic A subtypes identified. Exons 6 and 7 from 57 representative donors were sequenced. The A(var) allele (784 G > A) was cloned and sequenced, and a family study demonstrating its inheritance and unusual serological characteristics was performed. The A102 allele was the most frequently identified allele in phenotypically A2 (58%, 11/19) and A2B (68%, 17/25) donors. Anti-A1 was rarely present amongst A2 and A2B donors. The family study revealed that the A(var) allele was expressed as phenotype A(weak)B in A(var)/B heterozygote members, but as phenotype O in A(var)/O heterozygotes. The most frequent allele in Korean donors with the A2 phenotype differs from its Caucasian counterpart, as does the frequency of anti-A1. The A(var) allele demonstrates allelic enhancement in A(var)/B heterozygotes.