Association between Fiber Intake and Risk of Incident Chronic Kidney Disease: The UK Biobank Study

OBJECTIVES

Dietary fiber intake is associated with a lower risk of diabetes, cardiovascular disease, and cancer. However, it is unknown whether dietary fiber has a beneficial effect on preventing the development of chronic kidney disease (CKD).

DESIGN, SETTING, PARTICIPANTS AND MEASUREMENTS

Using the UK Biobank prospective cohort, 110,412 participants who completed at least one dietary questionnaire and had an estimated glomerular filtration rate ≥60 mL/min/1.73 m2, urinary albumin-to-creatinine ratio <30 mg/g, and no history of CKD were included. The primary exposure was total dietary fiber density, calculated by dividing the absolute amount of daily total fiber intake by total energy intake (g/1,000 kcal). We separately examined soluble and insoluble fiber densities as additional predictors. The primary outcome was incident CKD based on diagnosis codes.

RESULTS

A total of 3,507 (3.2%) participants developed incident CKD during a median follow-up of 9.9 years. In a multivariable cause-specific model, the adjusted hazard ratios (aHRs; 95% confidence intervals [CIs]) for incident CKD were 0.85 (0.77-0.94), 0.78 (0.70-0.86), and 0.76 (0.68-0.86), respectively, for the second, third, and highest quartiles of dietary fiber density (reference: lowest quartile). In a continuous model, the aHR for each +∆1.0g/1,000 kcal increase in dietary fiber density was 0.97 (95% CI, 0.95-0.99). This pattern of associations was similar for both soluble and insoluble fiber densities and did not differ across subgroups of sex, age, body mass index, hypertension, diabetes, smoking, and inflammation.

CONCLUSION

Increased fiber intake was associated with a lower risk of CKD in this large well-characterized cohort.

Topological magnon insulators in two-dimensional van der Waals ferromagnets CrSiTe3 and CrGeTe3: Toward intrinsic gap-tunability

The bosonic analogs of topological insulators have been proposed in numerous theoretical works, but their experimental realization is still very rare, especially for spin systems. Recently, two-dimensional (2D) honeycomb van der Waals ferromagnets have emerged as a new platform for topological spin excitations. Here, via a comprehensive inelastic neutron scattering study and theoretical analysis of the spin-wave excitations, we report the realization of topological magnon insulators in CrXTe₃ (X = Si, Ge) compounds. The nontrivial nature and intrinsic tunability of the gap opening at the magnon band-crossing Dirac points are confirmed, while the emergence of the corresponding in-gap topological edge states is demonstrated theoretically. The realization of topological magnon insulators with intrinsic gap-unability in this class of remarkable 2D materials will undoubtedly lead to new and fascinating technological applications in the domain of magnonics and topological spintronics.

Polarized neutron scattering studies of magnetic excitations in iron-selenide superconductor Li0.8Fe0.2ODFeSe (Tc41 K)

We report polarized neutron scattering measurements of the low energy spin fluctuations of the iron-selenide superconductor Li_0.8Fe_0.2ODFeSe below and above its superconducting transition temperatureT_c= 41 K. Our experiments confirmed that the resonance mode near 21 meV is magnetic. Moreover, the spin excitations are essentially isotropic in spin space at 5 ⩽E⩽ 29 meV in the superconducting and normal states. Our results suggest that the resonance mode in iron-based superconductors becomes isotropic when the influence of spin-orbit coupling and magnetic/nematic order is minimized, similar to those observed in cuprate superconductors.

Elucidation of Diffusivity of Hydrogen Isotopes in Flexible MOFs by Quasi-Elastic Neutron Scattering

Kinetic-quantum-sieving-assisted H₂ :D₂ separation in flexible porous materials is more effective than the currently used energy-intensive cryogenic distillation and girdle-sulfide processes for isotope separation. It is believed that material flexibility results in a pore-breathing phenomenon under the influence of external stimuli, which helps in adjusting the pore size and gives rise to the optimum quantum-sieving phenomenon at each stage of gas separation. However, only a few studies have investigated kinetic-quantum-sieving-assisted isotope separation using flexible porous materials. In addition, no reports are available on the microscopic observation of isotopic molecular transportation during the separation process under dynamic transition. Here, the experimental observation of a significantly faster diffusion of deuterium than hydrogen in a flexible pore structure, even at high temperatures, through quasi-elastic neutron scattering, is reported. Unlike rigid structures, the extracted diffusion dynamics of hydrogen isotopes within flexible frameworks show that the diffusion difference between the isotopes increases with an increase in temperature. Owing to this unique inverse trend, a new strategy is suggested for achieving higher operating temperatures for efficient isotope separation utilizing a flexible metal-organic framework system.

Erratum: Lattice Dynamics Coupled to Charge and Spin Degrees of Freedom in the Molecular Dimer-Mott Insulator κ-(BEDT-TTF)_{2}Cu[N(CN)_{2}]Cl [Phys. Rev. Lett. 123, 027601 (2019)]

This corrects the article DOI: 10.1103/PhysRevLett.123.027601.

In-plane uniaxial pressure-induced out-of-plane antiferromagnetic moment and critical fluctuations in BaFe2As2

A small in-plane external uniaxial pressure has been widely used as an effective method to acquire single domain iron pnictide BaFe2As2, which exhibits twin-domains without uniaxial strain below the tetragonal-to-orthorhombic structural (nematic) transition temperature Ts. Although it is generally assumed that such a pressure will not affect the intrinsic electronic/magnetic properties of the system, it is known to enhance the antiferromagnetic (AF) ordering temperature TN ( < Ts) and create in-plane resistivity anisotropy above Ts. Here we use neutron polarization analysis to show that such a strain on BaFe2As2 also induces a static or quasi-static out-of-plane (c-axis) AF order and its associated critical spin fluctuations near TN/Ts. Therefore, uniaxial pressure necessary to detwin single crystals of BaFe2As2 actually rotates the easy axis of the collinear AF order near TN/Ts, and such effects due to spin-orbit coupling must be taken into account to unveil the intrinsic electronic/magnetic properties of the system.

Specific Isotope-Responsive Breathing Transition in Flexible Metal-Organic Frameworks

An isotope-selective responsive system based on molecular recognition in porous materials has potential for the storage and purification of isotopic mixtures but is considered unachievable because of the almost identical physicochemical properties of the isotopes. Herein, a unique isotope-responsive breathing transition of the flexible metal-organic framework (MOF), MIL-53(Al), which can selectively recognize and respond to only D₂ molecules through a secondary breathing transition, is reported. This novel phenomenon is examined using in situ neutron diffraction experiments under the same conditions for H₂ and D₂ sorption experiments. This work can guide the development of a novel isotope-selective recognition system and provide opportunities to fabricate flexible MOF systems for energy-efficient purification of the isotopic mixture.

Lattice Dynamics Coupled to Charge and Spin Degrees of Freedom in the Molecular Dimer-Mott Insulator κ-(BEDT-TTF)_{2}Cu[N(CN)_{2}]Cl

Inelastic neutron scattering measurements on the molecular dimer-Mott insulator κ-(BEDT-TTF)_{2}Cu[N(CN)_{2}]Cl reveal a phonon anomaly in a wide temperature range. Starting from T_{ins}∼50-60  K where the charge gap opens, the low-lying optical phonon modes become overdamped upon cooling towards the antiferromagnetic ordering temperature T_{N}=27  K, where also a ferroelectric ordering at T_{FE}≈T_{N} occurs. Conversely, the phonon damping becomes small again when spins and charges are ordered below T_{N}, while no change of the lattice symmetry is observed across T_{N} in neutron diffraction measurements. We assign the phonon anomalies to structural fluctuations coupled to charge and spin degrees of freedom in the BEDT-TTF molecules.

Anisotropic spin fluctuations in detwinned FeSe

Superconductivity in FeSe emerges from a nematic phase that breaks four-fold rotational symmetry in the iron plane. This phase may arise from orbital ordering, spin fluctuations or hidden magnetic quadrupolar order. Here we use inelastic neutron scattering on a mosaic of single crystals of FeSe, detwinned by mounting on a BaFe2As2 substrate to demonstrate that spin excitations are most intense at the antiferromagnetic wave vectors QAF = (±1, 0) at low energies E = 6-11 meV in the normal state. This two-fold (C2) anisotropy is reduced at lower energies, 3-5 meV, indicating a gapped four-fold (C4) mode. In the superconducting state, however, the strong nematic anisotropy is again reflected in the spin resonance (E = 3.6 meV) at QAF with incommensurate scattering around 5-6 meV. Our results highlight the extreme electronic anisotropy of the nematic phase of FeSe and are consistent with a highly anisotropic superconducting gap driven by spin fluctuations.

Microscopic hematuria is a risk factor of incident chronic kidney disease in the Korean general population: a community-based prospective cohort study

BACKGROUND

Although asymptomatic microscopic hematuria (MH) is a common finding in clinical practice, its long-term outcome remains unknown.

AIM

This study evaluated the clinical implication of MH in the general population using a large-scale long-term longitudinal cohort database.

METHODS

This study included 8719 participants from the Korean Genome and Epidemiology Study between 2001 and 2014. MH was defined as ≥5 red blood cells per high-power field in random urinalysis without evidence of pyuria. The primary study outcome measure was incident chronic kidney disease (CKD), defined as estimated glomerular filtration rate <60 ml min-1⋅1.73⋅m-2.

RESULTS

During a median follow-up of 11.7 years, CKD occurred in 677 (7.8%) subjects. In Cox regression after adjustment for multiple confounders, subjects with MH had a significantly higher risk of incident CKD than those without [hazard ratio (HR) 1.45, 95% confidence interval (CI) 1.12-1.87; P = 0.005]. Isolated MH without proteinuria was also a risk factor of incident CKD (HR 1.37, 95% CI 1.04-1.79; P = 0.023) and the risk was further increased in MH with concomitant proteinuria (HR 5.41, 95% CI 2.54-11.49; P < 0.001). In propensity score matching analysis after excluding subjects with proteinuria, multi-variable stratified Cox regression analysis revealed that subjects with isolated MH had a significantly higher risk of incident CKD than those without (HR 1.83, 95% CI 1.14-2.94; P = 0.012).

CONCLUSION

The presence of MH is associated with an increased risk of incident CKD in the general population. Therefore, attentive follow-up is warranted in persons with MH for early detection of CKD.

Structure of spin excitations in heavily electron-doped Li0.8Fe0.2ODFeSe superconductors

Heavily electron-doped iron-selenide high-transition-temperature (high-T_c) superconductors, which have no hole Fermi pockets, but have a notably high T_c, have challenged the prevailing s_± pairing scenario originally proposed for iron pnictides containing both electron and hole pockets. The microscopic mechanism underlying the enhanced superconductivity in heavily electron-doped iron-selenide remains unclear. Here, we used neutron scattering to study the spin excitations of the heavily electron-doped iron-selenide material Li_0.8Fe_0.2ODFeSe (T_c = 41 K). Our data revealed nearly ring-shaped magnetic resonant excitations surrounding (π, π) at ∼21 meV. As the energy increased, the spin excitations assumed a diamond shape, and they dispersed outward until the energy reached ∼60 meV and then inward at higher energies. The observed energy-dependent momentum structure and twisted dispersion of spin excitations near (π, π) are analogous to those of hole-doped cuprates in several aspects, thus implying that such spin excitations are essential for the remarkably high T_c in these materials.

The microscopic mechanism underlying an enhanced superconductivity in electron-doped iron selenide superconductor remains unclear. Here, Pan et al. report the spin excitations of Li_0.8Fe_0.2ODFeSe, revealing analogous momentum structure and dispersion to hole-doped cuprates.

Spin-Wave Excitations Evidencing the Kitaev Interaction in Single Crystalline α-RuCl_{3}

Kitaev interactions underlying a quantum spin liquid have long been sought, but experimental data from which their strengths can be determined directly, are still lacking. Here, by carrying out inelastic neutron scattering measurements on high-quality single crystals of α-RuCl_{3}, we observe spin-wave spectra with a gap of ∼2  meV around the M point of the two-dimensional Brillouin zone. We derive an effective-spin model in the strong-coupling limit based on energy bands obtained from first-principles calculations, and find that the anisotropic Kitaev interaction K term and the isotropic antiferromagnetic off-diagonal exchange interaction Γ term are significantly larger than the Heisenberg exchange coupling J term. Our experimental data can be well fit using an effective-spin model with K=-6.8  meV and Γ=9.5  meV. These results demonstrate explicitly that Kitaev physics is realized in real materials.

Abstract P2-01-36: Ex vivo shear-wave elastography of axillary lymph nodes predicting nodal metastasis in patients with primary breast cancer: A pilot study

Objective: To evaluate the feasibility of shear-wave elastography using breast ultrasonography in identifying metastasis of removed sentinel lymph nodes during the operation for treatment of breast cancer.

Background: Conventional method for identification of sentinel nodal metastasis is time and cost consuming. The optimal method for identification of nodal status is important.

Methods: Excised sentinel lymph nodes during the operation were prospectively examined with the elastography. Metastatic status of lymph nodes was confirmed with permanent histology. Only macrometastasis was regarded as positive. Elastic values measured by the ex vivo elastography and nodal characteristics were analyzed to correlate with nodal metastasis.

Results: A total of 274 lymph nodes harvested from 68 breast cancer patients at Gangnam Severance Hospital from May 2014 to April 2015 were included this study. There was the difference of elastic values between nodes with and without metastasis (mean stiffness, 41.6 kPa and 17.4 kPa, P &lt; 0.001). Mean sizes of metastatic nodes (range 0.36-2.59 cm) were significantly larger than that of non-metastatic nodes (1.0 cm versus 0.75 cm, P &lt; 0.001). Moreover, there was a correlation between the size of metastatic nodes which ranged from 0.7 to 21.5 mm with a median of 7 mm and nodal stiffness (correlation coefficient of mean stiffness, r = 0.431). The area under the receiver operating characteristic curve (AUC) by the mean stiffness was 0.794. The combination of size of nodes, mean stiffness and ratio made AUC of 0.856.

Conclusions: In our study, ex vivo shear-wave elastography of sentinel lymph nodes was a feasible method to predict metastasis. Through the validation study, ex vivo elastography could be helpful to determine metastasis of sentinel lymph nodes during the operation.

Keywords Breast cancer; Elastography; Lymph node metastasis.

Citation Format: Lim JW, Lee HW, Park JT, Ahn SG, Jung J. Ex vivo shear-wave elastography of axillary lymph nodes predicting nodal metastasis in patients with primary breast cancer: A pilot study [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P2-01-36.

Effect of Nematic Order on the Low-Energy Spin Fluctuations in Detwinned BaFe_{1.935}Ni_{0.065}As_{2}

The origin of nematic order remains one of the major debates in iron-based superconductors. In theories based on spin nematicity, one major prediction is that the spin-spin correlation length at (0,π) should decrease with decreasing temperature below the structural transition temperature T_{s}. Here, we report inelastic neutron scattering studies on the low-energy spin fluctuations in BaFe_{1.935}Ni_{0.065}As_{2} under uniaxial pressure. Both intensity and spin-spin correlation start to show anisotropic behavior at high temperature, while the reduction of the spin-spin correlation length at (0,π) happens just below T_{s}, suggesting the strong effect of nematic order on low-energy spin fluctuations. Our results favor the idea that treats the spin degree of freedom as the driving force of the electronic nematic order.

Transition from Sign-Reversed to Sign-Preserved Cooper-Pairing Symmetry in Sulfur-Doped Iron Selenide Superconductors

An essential step toward elucidating the mechanism of superconductivity is to determine the sign or phase of the superconducting order parameter, as it is closely related to the pairing interaction. In conventional superconductors, the electron-phonon interaction induces attraction between electrons near the Fermi energy and results in a sign-preserved s-wave pairing. For high-temperature superconductors, including cuprates and iron-based superconductors, prevalent weak coupling theories suggest that the electron pairing is mediated by spin fluctuations which lead to repulsive interactions, and therefore that a sign-reversed pairing with an s_{±} or d-wave symmetry is favored. Here, by using magnetic neutron scattering, a phase sensitive probe of the superconducting gap, we report the observation of a transition from the sign-reversed to sign-preserved Cooper-pairing symmetry with insignificant changes in T_{c} in the S-doped iron selenide superconductors K_{x}Fe_{2-y}(Se_{1-z}S_{z})_{2}. We show that a rather sharp magnetic resonant mode well below the superconducting gap (2Δ) in the undoped sample (z=0) is replaced by a broad hump structure above 2Δ under 50% S doping. These results cannot be readily explained by simple spin fluctuation-exchange pairing theories and, therefore, multiple pairing channels are required to describe superconductivity in this system. Our findings may also yield a simple explanation for the sometimes contradictory data on the sign of the superconducting order parameter in iron-based materials.

Abstract P3-07-10: The association between the expression of progesterone receptor and clinical benefit of adjuvant trastuzumab in estrogen receptor-positive and HER2-positive breast cancer patients

Background: Previous studies have shown that progesterone receptor (PR) status has a prognostic value in hormone receptor-positive breast cancer. In this study, we evaluated the clinical significance of PR status in estrogen receptor (ER)-positive and HER2-positive breast cancer.

Methods: We retrospectively analyzed the data of ER+ and HER2+ breast cancer patients who underwent surgery at Gangnam Severance hospital and Severance hospital from 2002 to 2012. We excluded patients who had a history of previous cancer, received neoadjuvant chemotherapy, did not received adjuvant chemotherapy, and had contralateral breast cancer or metastasis at diagnosis. A total of 346 patients were identified. Among them, 155 patients (44.8%) received adjuvant trastuzumab.

Results: At a median follow-up of 59 months, median disease-free survival (DFS) and overall survival (OS) were 56 and 59 months, respectively. The DFS and OS showed no difference according to PR status in overall patients. Then, these patients were categorized into two groups: ER+/HER2+/PR+ and ER+/HER2+/PR-. In ER+/HER2+PR+ patient, there was no difference of DFS or OS according to trastuzumab use. In ER+/HER2+/PR- patients, DFS was significantly better in patients who received adjuvant trastuzumab treatment compared to those who did not (p=0.009). We also analyzed influence of PR status on treatment outcome between patients who received adjuvant trastuzumab and those who did not. In patients who received adjuvant trastuzumab, there was no difference of DFS or OS according to PR status. However, in patients who did not receive adjuvant trastuzumab, ER+/HER2+/PR- patients showed worse DFS than ER+/HER2+/PR+ patients (p=0.006).

Conclusions: In patients with ER+/HER2+ breast cancer, we found that a prognostic value of PR only retained in those who did not receive adjuvant trastuzumab. Our findings suggest that the use of adjuvant trastuzumab may offer less clinical benefit for the patients with ER+/HER2+/PR+ breast cancer.

Citation Format: Lee HW, Ahn SG, Park JT, Yang BS, Park S, Jeong J, Kim SI. The association between the expression of progesterone receptor and clinical benefit of adjuvant trastuzumab in estrogen receptor-positive and HER2-positive breast cancer patients. [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 P3-07-10.

Competing exchange interactions on the verge of a metal-insulator transition in the two-dimensional spiral magnet Sr3Fe2O7

We report a neutron scattering study of the magnetic order and dynamics of the bilayer perovskite Sr(3)Fe(2)O(7), which exhibits a temperature-driven metal-insulator transition at 340 K. We show that the Fe(4+) moments adopt incommensurate spiral order below T(N) = 115 K and provide a comprehensive description of the corresponding spin-wave excitations. The observed magnetic order and excitation spectra can be well understood in terms of an effective spin Hamiltonian with interactions ranging up to third-nearest-neighbor pairs. The results indicate that the helical magnetism in Sr(3)Fe(2)O(7) results from competition between ferromagnetic double-exchange and antiferromagnetic superexchange interactions whose strengths become comparable near the metal-insulator transition. They thus confirm a decades-old theoretical prediction and provide a firm experimental basis for models of magnetic correlations in strongly correlated metals.

Differential in vivo tumorigenicity of diverse KRAS mutations in vertebrate pancreas: A comprehensive survey

Somatic activation of the KRAS proto-oncogene is evident in almost all pancreatic cancers, and appears to represent an initiating event. These mutations occur primarily at codon 12 and less frequently at codons 13 and 61. While some studies have suggested that different KRAS mutations may have variable oncogenic properties, to date there has been no comprehensive functional comparison of multiple KRAS mutations in an in vivo vertebrate tumorigenesis system. We generated a Gal4/UAS-based zebrafish model of pancreatic tumorigenesis in which the pancreatic expression of UAS-regulated oncogenes is driven by a ptf1a:Gal4-VP16 driver line. This system allowed us to rapidly compare the ability of 12 different KRAS mutations (G12A, G12C, G12D, G12F, G12R, G12S, G12V, G13C, G13D, Q61L, Q61R, and A146T) to drive pancreatic tumorigenesis in vivo. Among fish injected with one of five KRAS mutations reported in other tumor types but not in human pancreatic cancer, 2/79 (0.25%) developed pancreatic tumors, with both tumors arising in fish injected with A146T. In contrast, among fish injected with one of seven KRAS mutations known to occur in human pancreatic cancer, 22/106 (20.8%) developed pancreatic cancer. All eight tumorigenic KRAS mutations were associated with downstream MAPK/ERK pathway activation in preneoplastic pancreatic epithelium, while non-tumorigenic mutations were not. These results suggest that the spectrum of KRAS mutations observed in human pancreatic cancer reflects selection based upon variable tumorigenic capacities, including the ability to activate MAPK/ERK signaling.

Translationally controlled tumour protein is associated with podocyte hypertrophy in a mouse model of type 1 diabetes

AIMS/HYPOTHESIS

Translationally controlled tumour protein (TCTP) is thought to be involved in cell growth by regulating mTOR complex 1 (mTORC1) signalling. As diabetes characteristically induces podocyte hypertrophy and mTORC1 has been implicated in this process, TCTP may have a role in the pathogenesis of diabetes-induced podocyte hypertrophy.

METHODS

We investigated the effects and molecular mechanisms of TCTP in diabetic mice and in high glucose-stimulated cultured podocytes. To characterise the role of TCTP, we conducted lentivirus-mediated gene silencing of TCTP both in vivo and in vitro.

RESULTS

Glomerular production of TCTP was significantly higher in streptozotocin induced-diabetic DBA/2J mice than in control animals. Double-immunofluorescence staining for TCTP and synaptopodin revealed that podocyte was the principal cell responsible for this increase. TCTP knockdown attenuated the activation of mTORC1 downstream effectors and the overproduction of cyclin-dependent kinase inhibitors (CKIs) in diabetic glomeruli, along with a reduction in proteinuria and a decrease in the sizes of podocytes as well as glomeruli. In addition, knockdown of TCTP in db/db mice prevented the development of diabetic nephropathy, as indicated by the amelioration of proteinuria, mesangial expansion, podocytopenia and glomerulosclerosis. In accordance with the in vivo data, TCTP inhibition abrogated high glucose-induced hypertrophy in cultured podocytes, which was accompanied by the downregulation of mTORC1 effectors and CKIs.

CONCLUSIONS/INTERPRETATION

These findings suggest that TCTP might play an important role in the process of podocyte hypertrophy under diabetic conditions via the regulation of mTORC1 activity and the induction of cell-cycle arrest.

Magnetic resonant mode in the low-energy spin-excitation spectrum of superconducting Rb2Fe4Se5 single crystals

We have studied the low-energy spin-excitation spectrum of the single-crystalline Rb(2)Fe(4)Se(5) superconductor (T(c)=32 K) by means of inelastic neutron scattering. In the superconducting state, we observe a magnetic resonant mode centered at an energy of ℏω(res)=14 meV and at the (0.5 0.25 0.5) wave vector (unfolded Fe-sublattice notation), which differs from the ones characterizing magnetic resonant modes in other iron-based superconductors. Our finding suggests that the 245-iron selenides are unconventional superconductors with a sign-changing order parameter, in which bulk superconductivity coexists with the √5×√5 magnetic superstructure. The estimated ratios of ℏω(res)/k(B)T(c)≈5.1±0.4 and ℏω(res)/2Δ≈0.7±0.1, where Δ is the superconducting gap, indicate moderate pairing strength in this compound, similar to that in optimally doped 1111 and 122 pnictides.

New anatomical insight of the levator labii superioris alaeque nasi and the transverse part of the nasalis

PURPOSE

The aim of this study was to clarify the morphology and topography of the deep layer of levator labii superioris alaeque nasi muscle (LLSAN) and the transverse part of the nasalis. Anatomical variations in the topographic relationships were also described to understand the function of the LLSAN and the transverse part of the nasalis.

METHODS

Anatomical dissections were performed on 40 specimens of embalmed Korean adult cadavers.

RESULTS

The LLSAN was divided into two layers, which were superficial and deep in the levator labii superioris muscle (LLS), respectively. The superficial layer of LLSAN descended on the LLS, and the deep layer was located deep in the LLS. The deep layer of LLSAN originated from the superficial layer of LLSAN and the frontal process of the maxilla. It inserted between the levator anguli oris and the orbicularis oris muscles. This transverse part of the nasalis received some muscle fibers from the superficial layer of LLSAN in 90% (36/40) of specimens. The transverse part of the nasalis originated from the maxilla and ascended, passing posterior to the superficial layer of LLSAN in 65% (26/40) of specimens. However, it originated as two muscle bellies from the maxilla and the upper half of the alar facial crease, respectively, in 35% (14/40) of specimens.

CONCLUSIONS

These findings will be crucial data to understand the structure and function of the LLSAN and the transverse part of the nasalis.

Weak superconducting pairing and a single isotropic energy gap in stoichiometric LiFeAs

We report superconducting (SC) properties of stoichiometric LiFeAs (T(c)=17 K) studied by small-angle neutron scattering (SANS) and angle-resolved photoemission (ARPES). Although the vortex lattice exhibits no long-range order, well-defined SANS rocking curves indicate better ordering than in chemically doped 122 compounds. The London penetration depth lambda(ab)(0)=210+/-20 nm, determined from the magnetic field dependence of the form factor, is compared to that calculated from the ARPES band structure with no adjustable parameters. The temperature dependence of lambda(ab) is best described by a single isotropic SC gap Delta(0)=3.0+/-0.2 meV, which agrees with the ARPES value of Delta(0)(ARPES)=3.1+/-0.3 meV and corresponds to the ratio 2Delta/k(B)T(c)=4.1+/-0.3, approaching the weak-coupling limit predicted by the BCS theory. This classifies LiFeAs as a weakly coupled single-gap superconductor.

Clinical outcomes of multicenter domino kidney paired donation

Domino kidney paired donation (KPD) is a method by which an altruistic living nondirected donor (LND) is allocated to a pool of incompatible donor-recipient pairs (DRP) and a series of KPDs is initiated. To evaluate the feasibility and clinical outcomes of multicenter domino KPD, we retrospectively analyzed a cohort of DRPs who underwent domino KPD between February 2001 and July 2007 at one of 16 transplant centers. One hundred seventy-nine kidney transplants were performed, with 70 domino chains initiated by altruistic LND. There were 45 two-pair chains, 15 three-pair chains, 7 four-pair chains, 2 five-pair chains and 1 six-pair chain. A majority of donors were spouses (47.5%) or altruistic LNDs (39.1%). DRPs with a blood type O recipient or an AB donor comprised 45.9% of transplanted DRPs. HLA mismatch improved in transplanted donors compared to intended donors in pairs enrolled to improve HLA mismatch (3.4 +/- 0.7 vs. 4.8 +/- 1.0, p < 0.001). One-year and 5-year graft survival rates were 98.3% and 87.7%, respectively, with a median follow-up of 46 months. One-year and 5-year patient survival rates were 97.2% and 90.8%, respectively. In conclusion, multicenter domino KPD could multiply the benefits of donation from LNDs, with patients and graft survival rates comparable to those seen with conventional KPD.

Magnetic-field-enhanced incommensurate magnetic order in the underdoped high-temperature superconductor YBa2Cu3O6.45

We present a neutron-scattering study of the static and dynamic spin correlations in the underdoped high-temperature superconductor YBa2Cu3O6.45 in magnetic fields up to 15 T. The field strongly enhances static incommensurate magnetic order at low temperatures and induces a spectral-weight shift in the magnetic-excitation spectrum. A reconstruction of the Fermi surface driven by the field-enhanced magnetic superstructure may thus be responsible for the unusual Fermi surface topology revealed by recent quantum-oscillation experiments.

Two-gap superconductivity in Ba1-xKxFe2As2: a complementary study of the magnetic penetration depth by muon-spin rotation and angle-resolved photoemission

We investigate the magnetic penetration depth lambda in superconducting Ba1-xKxFe2As2 (Tc approximately 32 K) with muon-spin rotation (microSR) and angle-resolved photoemission (ARPES). Using microSR, we find the penetration-depth anisotropy gamma lambda=lambda c/lambda ab and the second-critical-field anisotropy gammaHc2 to show an opposite T evolution below Tc. This dichotomy resembles the situation in the two-gap superconductor MgB2. A two-gap scenario is also suggested by an inflection point in the in-plane penetration depth lambda ab around 7 K. The complementarity of microSR and ARPES allows us to pinpoint the values of the two gaps and to arrive to a remarkable agreement between the two techniques concerning the full T evolution of lambdaab. This provides further support for the described scenario and establishes ARPES as a tool to assess macroscopic properties of the superconducting condensate.

Electronic phase separation in the slightly underdoped iron pnictide superconductor Ba1-xKxFe2As2

Here we present a combined study of the slightly underdoped novel pnictide superconductor Ba1-xKxFe2As2 by means of x-ray powder diffraction, neutron scattering, muon-spin rotation (microSR), and magnetic force microscopy (MFM). Static antiferromagnetic order sets in below T{m} approximately 70 K as inferred from the neutron scattering and zero-field-microSR data. Transverse-field microSR below Tc shows a coexistence of magnetically ordered and nonmagnetic states, which is also confirmed by MFM imaging. We explain such coexistence by electronic phase separation into antiferromagnetic and superconducting- or normal-state regions on a lateral scale of several tens of nanometers. Our findings indicate that such mesoscopic phase separation can be considered an intrinsic property of some iron pnictide superconductors.

(pi, pi) electronic order in iron arsenide superconductors

The distribution of valence electrons in metals usually follows the symmetry of the underlying ionic lattice. Modulations of this distribution often occur when those electrons are not stable with respect to a new electronic order, such as spin or charge density waves. Electron density waves have been observed in many families of superconductors, and are often considered to be essential for superconductivity to exist. Recent measurements seem to show that the properties of the iron pnictides are in good agreement with band structure calculations that do not include additional ordering, implying no relation between density waves and superconductivity in these materials. Here we report that the electronic structure of Ba(1-x)K(x)Fe(2)As(2) is in sharp disagreement with those band structure calculations, and instead reveals a reconstruction characterized by a (pi, pi) wavevector. This electronic order coexists with superconductivity and persists up to room temperature (300 K).

The association between CD99 and LMP-1 expression in nasopharyngeal carcinoma

AIM

To characterize the roles of LMP-1 and CD99 in nasopharyngeal carcinogenesis, we undertook this pilot study of LMP-1 and CD99 expressions in nasopharyngeal cancer (NPC).

MATERIALS AND METHOD

40 NPC tissue samples were grouped according to the WHO classification. Immunohistochemical studies were performed using monoclonal antibodies against EBV latent membrane protein 1 (LMP-1) and CD99 protein. In addition, CD99 expression was evaluated in 10 samples of non-neoplastic nasopharyngeal epithelium.

RESULTS

LMP-1 was detected in 12 of the 40 (30.0%) cases and its expression was found to be confined to epithelial tumor cells. WHO type I NPC samples were completely negative for LMP-1, whereas WHO type III NPC samples showed highest expression. Interestingly, CD99 was expressed in all of the non-neoplastic nasopharyngeal epithelium samples along the cytoplasmic border. CD99 expression was noted in NPC tumor cells (5 of the 40 cases, 12.5%) and in surrounding lymphoid stroma (23 of the 40 cases, 57.5%), but was not expressed in WHO type I NPC. In the 12 LMP-1 positive cases, 9 cases (75.0%) were CD99 negative, and 3 cases (25.5%) were CD99 positive. There was a statistical significance between LMP-1 and CD99 expression in lymphoid stroma.

CONCLUSION

Our results suggest that the LMP-1 induced down-regulation of the CD99 pathway is important in nasopharyngeal carcinogenesis, and that the expression of CD99 in lymphoid stroma may regulate immune response to NPC.

Geographical difference in the prevalence of isolated systolic hypertension in middle-aged men and women in Korea: the Korean Health and Genome Study

To compare geographical difference in the prevalence of isolated systolic hypertension (ISH) in between urban (Ansan) and rural (Ansung) Korean adults aged 40-69 years, 4351 men and 4604 women enrolled in the Korean Health and Genome Study were analysed. Information was collected regarding gender, alcohol intake, smoking status, household income, occupation, and years of education by trained interviewers. Eligible subjects included untreated hypertensive and normotensive subjects. ISH was defined as a systolic blood pressure (SBP) > or = 140 mmHg and diastolic BP <90 mmHg. The overall age-adjusted prevalence of ISH was 4.1%. The prevalence of ISH in Ansung (5.7%) was higher than in Ansan (2.5%, P < 0.05). Also it increased with increments of age, from 1.0 to 12.8% in Ansung (P < 0.05) and from 0.3 to 13.0% in Ansan (P < 0.05). In those with body mass index (BMI) > or = 30.0 kg/m2 in Ansung, the prevalence of ISH in women was twice as much as in men. The prevalence of ISH in obese men and women with a waist-hip ratio > or =1.0 and > or = 0.85, respectively, was more than that of nonobese men and women in both areas. In Korea, because of industrialization, the age distribution was skewed and the Korean population in rural areas is more aged. ISH will become a truly major health problem in rural area, because ISH is related to age, BMI and waist-hip ratio. Therefore, the Korean government will be required to institute different policies in the hypertension management to target populations in rural and urban areas.

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.

Effects of intracoronary calcium chloride on regional oxygen balance and mechanical function in normal and stunned myocardium in dogs

BACKGROUND

Brief myocardial ischaemia has been demonstrated to result in mechanical and coronary endothelial dysfunction, in which calcium may play a role. We examined whether the mechanical and vascular responses to calcium are altered in postischaemic, reperfused myocardium.

METHODS

Regional myocardial oxygen consumption (MVO2), mechanical function and coronary blood flow (CBF) in response to calcium chloride (0.10, 0.25, 0.50 and 0.75 mg ml(-1) of CBF) directly infused into the left anterior descending (LAD) artery were determined before (normal) and 30 min after a 15-min-period of LAD occlusion (stunned) in an open-chest canine model. Percentage segment shortening (%SS) and percentage postsystolic shortening (%PSS) in the LAD territory were determined using ultrasonic crystals and CBF using a Doppler transducer. Myocardial extraction of oxygen (EO2) and lactate (Elac) was calculated.

RESULTS

The infusion of calcium chloride resulted in dose-dependent increases in %SS and MVO2 but did not affect %PSS in normal myocardium. These changes were accompanied by parallel increases in CBF, resulting in no change in EO2. In stunned myocardium, the responses to calcium chloride were not significantly altered, with the exception of a reduction in %PSS. However, ischaemia and reperfusion itself significantly reduced %SS and Elac and increased %PSS.

CONCLUSIONS

These data suggest that calcium chloride improves regional systolic and diastolic function both in normal and stunned myocardium. Calcium chloride is unlikely to cause direct coronary vasoconstriction or to deteriorate regional mechanical function in postischaemic myocardium.

Is the human papillomavirus test in combination with the Papanicolaou test useful for management of patients with diagnoses of atypical squamous cells of undetermined significance/low-grade squamous intraepithelial lesions?

OBJECTIVE

To determine whether human papillomavirus (HPV) testing is useful in the evaluation of patients diagnosed with atypical squamous cells of undetermined significance (ASCUS)/low-grade squamous intraepithelial lesion (LSIL) and whether the HPV test is appropriate as an alternative screening method.

DESIGN

The results of Papanicolaou (Pap) tests and subsequent hybrid capture tube (HCT) II tests for high-risk-type HPV were analyzed for 457 patients. Among these tests, 208 histologic diagnoses were made and correlated with the results of Pap and HPV tests. The sensitivity and specificity of the Pap test, HPV test, and the combined method of Pap and HPV tests to detect cervical intraepithelial neoplasia (CIN) 2/3 and all CIN were also measured.

RESULTS

Sixty (63.8%) of 94 women with LSIL and 31 (26.3%) of 118 women with ASCUS tested positive for high-risk HPV. The sensitivity values for Pap tests in detecting all cases of CIN and CIN 2/3 were 91.4% and 92.9%, respectively. The sensitivity values of HCT II tests using the high-risk probe for detecting all cases of CIN and CIN 2/3 were 62.6% and 88.1%, respectively. Biopsies confirmed that 10 (22.7%) of 44 LSIL patients with high-risk HPV had CIN 2/3, but only 1 (4.5%) of 22 LSIL patients without high-risk HPV had CIN 2/3.

CONCLUSION

Testing for high-risk HPV with the HCT II test is useful in the detection of CIN 2/3 in LSIL groups and in the selection of patients for colposcopy in ASCUS groups, but it is not suitable for cervical cancer screening tests.

Identification of a dedicated recycling pathway for anhydro-N-acetylmuramic acid and N-acetylglucosamine derived from Escherichia coli cell wall murein

Turnover and recycling of the cell wall murein represent a major metabolic pathway of Escherichia coli. It is known that E. coli efficiently reuses, i.e., recycles, its murein tripeptide, L-alanyl-gamma-D-glutamyl-meso-diaminopimelate, to form new murein. However, the question of whether the cells also recycle the amino sugar moieties of cell wall murein has remained unanswered. It is demonstrated here that E. coli recycles the N-acetylglucosamine present in cell wall murein degradation products for de novo murein and lipopolysaccharide synthesis. Furthermore, E. coli also recycles the anhydro-N-acetylmuramic acid moiety by first converting it into N-acetylglucosamine. Based on the results obtained by studying mutants unable to recycle amino sugars, the pathway for recycling is revealed.

Evaluation on the adsorption capabilities of new chemically modified polymeric adsorbents with protoporphyrin IX

A chemically modified polymeric adsorbent was synthesized to evaluate the availability as an adsorbent for solid-phase extraction (SPE) of phenol and chlorophenols. Commercially available Amberlite XAD-2 and XAD-4 resins were modified with macrocyclic protoporphyrin IX (PPIX) through the ketone linkage. Adsorption isotherms were obtained by batch experiments and the data were fitted to the Freundlich equation to calculate the adsorption parameters. Breakthrough volumes were measured by column experiments. Physical properties such as surface area, average pore diameter and micropore volume of resins were measured to correlate with the adsorption characteristics. As a result, adsorption capacity was increased for the chemically modified resins and it can be concluded that the increase of pi-pi interaction due to the introduction of the porphyrin molecule is the major factor for the increase of the adsorption capacity.

Molecular characterization of the beta-N-acetylglucosaminidase of Escherichia coli and its role in cell wall recycling

The beta-N-acetylglucosaminidase of Escherichia coli was found to have a novel specificity and to be encoded by a gene (nagZ) that maps at 25.1 min. It corresponds to an open reading frame, ycfO, whose predicted amino acid sequence is 57% identical to that of Vibrio furnissii ExoII. NagZ hydrolyzes the beta-1,4 glycosidic bond between N-acetylglucosamine and anhydro-N-acetylmuramic acid in cell wall degradation products following their importation into the cell during the process for recycling cell wall muropeptides. From amino acid sequence comparisons, the novel beta-N-acetylglucosaminidase appears to be conserved in all 12 gram-negative bacteria whose complete or partial genome sequence data are available.

Cerebral infarction with ICA occlusion after Gamma Knife radiosurgery for pituitary adenoma: A case report

Cranial irradiation may lead to accelerated atherosclerotic changes to small or medium sized arteries, but stroke associated with pituitary irradiation is not frequent. A patient treated with Gamma Knife radio-surgery (GKRS) for a pituitary adenoma suffered a cerebral infarction with internal carotid artery occlusion 4 years after radiosurgery. The patient was a 35-year-old male presenting with a visual disturbance. Endocrinological tests were normal. MRI revealed a 4.3 by 4.3 cm diameter invasive macroadenoma of the pituitary, projecting toward the suprasellar region and with cavernous sinus involvement with encasement of both internal carotid arteries (ICAs). GKRS was performed for residual tumor after a transcranial resection. The maximum dose was 40 Gy and the dose to the right carotid artery was below 20 Gy. The delayed hemiparesis was accompanied by a right capsular lacunar infarct shown on MRI. The images also showed a marked reduction in tumor size. Total, right ICA occlusion was confirmed by Doppler ultrasound. The patient had no history or signs of heart disease or metabolic disorder which could predispose to cerebrovascular

The convergence of murein recycling research with beta-lactamase research

The story of how investigation of Escherichia coli cell wall elongation evolved into a study of murein recycling and how this led to the discovery that ampG and ampD were required for both murein recycling and beta-lactamase regulation is chronicled. Preliminary information on two other genes believed to be involved in recycling, nagZ, the structural gene for beta-N-acetylglucosaminidase, and tpl, the presumed structural gene for the hypothetical tripeptide-adding enzyme, is presented. The possibility that recycling of murein fragments serves a signaling function is discussed.

Microfibrillar structure of PGG-glucan in aqueous solution as triple-helix aggregates by small angle x-ray scattering

The conformation of polysaccharide PGG-Glucan, isolated from yeast cell walls, in aqueous solution was investigated by small angle x-ray scattering (SAXS) and multidetector gel permeation chromatography coupled with postcolumn delivery (GPC/PCD) techniques in comparison with scleroglucan. It was shown that both polysaccharides exhibit a rigid rod-like conformation in aqueous solution by SAXS experiments. The mass per unit length (M/L) and radius (R) of rod cross section of PGG-Glucan were measured to be 6300 daltons/nm and 1.89 nm, while those of scleroglucan are 2300 and 0.83, respectively. Utilizing a GPC/light scattering technique, the average aggregation number of PGG-Glucan is 9, while that of scleroglucan is around 3. From the comparison of the M/L and R of the respective rod cross sections as well as their aggregation number data, it is concluded that PGG-Glucan is composed of triple helices, which tend to aggregate as triplets in solution, whereas scleroglucan is composed of a single triple helix. The aggregation number distribution of PGG-Glucan was found to range from 1 to about 25 determined by GPC/PCD. From the observation of a Debye-Scherrer ring type of peak in the macroscopic scattering cross section of PGG-Glucan by SAXS, the existence of a small amount of ordered clusters of PGG-Glucan can be deduced. The "lattice parameter" of these ordered fasces-like clusters is consistent with the radius of the individual triple-helical rods forming a microfibrillar superstructure. These results indicate that higher aggregated forms of PGG-Glucan containing up to 8 triple helices behave as ordered fasces-like clusters. We conclude that PGG-Glucan is triple-helix aggregates formed by rigid rods stacking together side by side. We propose a molecular structural model for PGG-Glucan conformations.

The periplasmic murein peptide-binding protein MppA is a negative regulator of multiple antibiotic resistance in Escherichia coli

MppA is a periplasmic binding protein in Escherichia coli essential for uptake of the cell wall murein tripeptide L-alanyl-gamma-D-glutamyl-meso-diaminopimelate. We have found serendipitously that E. coli K-12 strains carrying a null mutation in mppA exhibit increased resistance to a wide spectrum of antibiotics and to cyclohexane. Normal sensitivity of the mppA mutant to these agents is restored by mppA expressed from a plasmid. As is observed in the multiple antibiotic resistance phenotype in E. coli cells, the mppA null mutant overproduces the transcriptional activator, MarA, resulting in expression of the membrane-bound AcrAB proteins that function as a drug efflux pump. Reduced production of OmpF similar to that observed in the multiple antibiotic resistance phenotype is also seen in the mppA mutant. These and other data reported herein indicate that MppA functions upstream of MarA in a signal transduction pathway to negatively regulate the expression of marA and hence of the MarA-driven multiple antibiotic resistance. Overproduction of cytoplasmic GadA and GadB and of several unidentified cytoplasmic membrane proteins as well as reduction in the amount of the outer membrane protein, OmpP, in the mppA null mutant indicate that MppA regulates a number of genes in addition to those already known to be controlled by MarA.

Dominant-negative effect of a mutant cardiac troponin T on cardiac structure and function in transgenic mice

Hypertrophic cardiomyopathy (HCM) is a disease of sarcomeric proteins. The mechanism by which mutant sarcomeric proteins cause HCM is unknown. The leading hypothesis proposes that mutant sarcomeric proteins exert a dominant-negative effect on myocyte structure and function. To test this, we produced transgenic mice expressing low levels of normal or mutant human cardiac troponin T (cTnT). We constructed normal (cTnT-Arg92) and mutant (cTnT-Gln92) transgenes, driven by a murine cTnT promoter, and produced three normal and five mutant transgenic lines, which were identified by PCR and Southern blotting. Expression levels of the transgene proteins, detected using a specific antibody, ranged from 1 to 10% of the total cTnT pool. M-mode and Doppler echocardiography showed normal left ventricular dimensions and systolic function, but diastolic dysfunction in the mutant mice evidenced by a 50% reduction in the E/A ratio of mitral inflow velocities. Histological examination showed cardiac myocyte disarray in the mutant mice, which amounted to 1-15% of the total myocardium, and a twofold increase in the myocardial interstitial collagen content. Thus, the mutant cTnT-Gln92, responsible for human HCM, exerted a dominant-negative effect on cardiac structure and function leading to disarray, increased collagen synthesis, and diastolic dysfunction in transgenic mice.

Antigen-dependent intrathecal antibody synthesis in the normal rat brain: tissue entry and local retention of antigen-specific B cells

The intrathecal Ab response to Ag introduced into the normal brain has not been fully explored. Involvement of Ag-specific, peripheral B cells in an intrathecal response was studied using a normal rat model of Ag infusion through an indwelling cannula into defined brain sites, while maintaining a functionally intact blood-brain barrier. Specific Ab was detected in serum and cerebrospinal fluid. The intrathecal response is first detectable at day 14. Isoelectric focusing of cerebrospinal fluid reveals banding patterns consistent with local Ab production. To increase Ag-specific, circulating peripheral lymphocytes available for trafficking to Ag-stimulated brain and for enhancing intrathecal Ab synthesis, rats were preimmunized peripherally. Subsequently, Ag or saline (control) was infused through the cannula. Under this protocol, intrathecal synthesis is detectable earlier (day 5 postinfusion). Immunohistochemical studies at the infusion site assessed Ag-specific B cells, T cells, and activated APCs. Rats receiving peripheral preimmunization followed by Ag into caudate nucleus have far greater numbers of these cells, including plasma cells, within the infusion site compared with saline controls. Results confirm previous indirect evidence of intrathecal Ab synthesis in normal rat brain and provide the first direct evidence for B cell trafficking across normal brain barriers plus retention at the Ag deposition site. Our studies indicate that the normal brain microenvironment supports development of Ag-directed humoral immunity. We propose that immune privilege in normal brain is characterized by down-regulation of cell-mediated but not Ab immune responses within the central nervous system.

Hepatic metastases from carcinoma of the uterine cervix

OBJECTIVE

To investigate the patterns of hepatic involvement and the outcome of patients with hepatic metastases from carcinoma of the uterine cervix.

METHODS

Of 1665 patients with carcinoma of the uterine cervix, 20 patients with hepatic metastases were detected clinically during the course of the disease. Clinical presentation and detailed patterns of hepatic involvement were retrospectively reviewed for these patients. Comparative analysis between patterns of heaptic metastases and survival data was also undertaken.

RESULTS

Hepatic metastasis from carcinoma of the uterine cervix were nearly always accompanied by uncontrolled locoregional diseases and/or extrahepatic metastases, whereas only 1 patient developed an isolated hepatic metastasis. Ninety percent of the hepatic metastases were metachronously detected. The median time from the appearance of primary carcinoma to detection of hepatic metastases was 39 months, but late metastases after 5 years were not uncommon. Metastatic lesion in 16 patients consisted of multiple tumors distributed in either one or both anatomical lobes, whereas only 4 patients had a solitary lesion confined to a single lobe. Patients with hepatic metastases were unlikely to survive 2 years with a median survival of 10 months.

CONCLUSION

Favorable patterns of hepatic metastases in patient with carcinoma of the uterine cervix were not major determinants of favorable survival if components of extrahepatic disease were concomitantly present.

MppA, a periplasmic binding protein essential for import of the bacterial cell wall peptide L-alanyl-gamma-D-glutamyl-meso-diaminopimelate

Mutants of a diaminopimelic acid (Dap)-requiring strain of Escherichia coli were isolated which failed to grow on media in which Dap was replaced by the cell wall murein tripeptide, L-alanyl-gamma-D-glutamyl-mesodiaminopimelate. In one such mutant, which is oligopeptide permease (Opp) positive, we have identified a new gene product, designated MppA (murein peptide permease A), that is about 46% identical to OppA, the periplasmic binding protein for Opp. A plasmid carrying the wild-type mppA gene allows the mutant to grow on tripeptide. Two other mutants that failed to grow on tripeptide were resistant to triornithine toxicity, indicating a defect in the opp operon. An E. coli strain whose entire opp operon was deleted but which carried the mppA locus was unable to grow on murein tripeptide unless it was provided with oppBCDF genes in trans. Our data suggest a model whereby the periplasmic MppA binds the murein tripeptide, which is then transported into the cytoplasm via membrane-bound and cytoplasmic OppBCDF. In assessing the affinity of MppA for non-cell wall peptides, we have found that proline auxotrophy can be satisfied with the peptide Pro-Phe-Lys, which utilizes either MppA or OppA in conjunction with OppBCDF for its uptake. Thus, MppA, OppA, and perhaps the third OppA paralog revealed by the E. coli genome sequence may each bind a particular family of peptides but interact with common membrane-associated components for transport of their bound ligands into the cell. As to the physiological function of MppA, the possibility that it may be involved in signal transduction pathway(s) is discussed.

A promoter for the first nine genes of the Escherichia coli mra cluster of cell division and cell envelope biosynthesis genes, including ftsI and ftsW

We constructed a null allele of the ftsI gene encoding penicillin-binding protein 3 of Escherichia coli. It caused blockage of septation and loss of viability when expression of an extrachromosomal copy of ftsI was repressed, providing a final proof that ftsI is an essential cell division gene. In order to complement this null allele, the ftsI gene cloned on a single-copy mini-F plasmid required a region 1.9 kb upstream, which was found to contain a promoter sequence that could direct expression of a promoterless lacZ gene on a mini-F plasmid. This promoter sequence lies at the beginning of the mra cluster in the 2 min region of the E. coli chromosome, a cluster of 16 genes which, except for the first 2, are known to be involved in cell division and cell envelope biosynthesis. Disruption of this promoter, named the mra promoter, on the chromosome by inserting the lac promoter led to cell lysis in the absence of a lac inducer. The defect was complemented by a plasmid carrying a chromosomal fragment ranging from the mra promoter to ftsW, the fifth gene downstream of ftsI, but not by a plasmid lacking ftsW. Although several potential promoter sequences in this region of the mra cluster have been reported, we conclude that the promoter identified in this study is required for the first nine genes of the cluster to be fully expressed.

Identification of the mpl gene encoding UDP-N-acetylmuramate: L-alanyl-gamma-D-glutamyl-meso-diaminopimelate ligase in Escherichia coli and its role in recycling of cell wall peptidoglycan

A gene, mpl, encoding UDP-N-acetylmuramate:L-alanyl-gamma-D-glutamyl-meso-diaminopimelat e ligase was recognized by its amino acid sequence homology with murC as the open reading frame yjfG present at 96 min on the Escherichia coli map. The existence of such an enzymatic activity was predicted from studies indicating that reutilization of the intact tripeptide L-alanyl-gamma-D-glutamyl-meso-diaminopimelate occurred and accounted for well over 30% of new cell wall synthesis. Murein tripeptide ligase activity could be demonstrated in crude extracts, and greatly increased activity was produced when the gene was cloned and expressed under control of the trc promoter. A null mutant totally lacked activity but was viable, showing that the enzyme is not essential for growth.

Why does Escherichia coli recycle its cell wall peptides?

This review discusses the phenomenon of recycling of cell wall peptides. It is a major, though non-essential, pathway of the cell and is required for induction of beta-lactamase. Consequently, the recycling pathway is viewed as a possible signalling vehicle, informing the cell of the condition of the murein sacculus, an essential structure existing outside the cell itself. As the study of this phenomenon is in its infancy, several speculations are offered for a possible regulatory function.

Interactions of Yersinia pestis penicillin-binding proteins with beta-lactam antibiotics

The affinities of six major penicillin-binding proteins (PBPs) of Yersinia pestis EV76 to different beta-lactam antibiotics were determined. The results indicate that, similar to their counterparts in Escherichia coli, PBP2 and PBP3 are the lethal targets of amdinocillin and furazlocillin, respectively. The PBP contents of four additional Y. pestis strains and the morphological effects produced by some beta-lactam antibiotics are also reported.

AmpD, essential for both beta-lactamase regulation and cell wall recycling, is a novel cytosolic N-acetylmuramyl-L-alanine amidase

In enterobacteria, the ampD gene encodes a cytosolic protein which acts as a negative regulator of beta-lactamase expression. It is shown here that the AmpD protein is a novel N-acetylmuramyl-L-alanine amidase (E.C.3.5.1.28) participating in the intracellular recycling of peptidoglycan fragments. Surprisingly, AmpD exhibits an exclusive specificity for substrates containing anhydro muramic acid. This anhydro bond is mainly found in the peptidoglycan degradation products formed by the periplasmic lytic transglycosylases and thus might behave as a 'recycling tag' allowing the enzyme to distinguish these fragments from the newly synthesized peptidoglycan precursors. The AmpD substrate (or substrates) which accumulates in the absence of the corresponding enzymatic activity acts as an intracellular positive effector for beta-lactamase expression and might represent an element of a communication network between the chromosome and the cell wall peptidoglycan.