Search for B^{+}→K^{+}νν[over ¯] Decays Using an Inclusive Tagging Method at Belle II

A search for the flavor-changing neutral-current decay B^{+}→K^{+}νν[over ¯] is performed at the Belle II experiment at the SuperKEKB asymmetric energy electron-positron collider. The data sample corresponds to an integrated luminosity of 63  fb^{-1} collected at the ϒ(4S) resonance and a sample of 9  fb^{-1} collected at an energy 60 MeV below the resonance. Because the measurable decay signature involves only a single charged kaon, a novel measurement approach is used that exploits not only the properties of the B^{+}→K^{+}νν[over ¯] decay, but also the inclusive properties of the other B meson in the ϒ(4S)→BB[over ¯] event, to suppress the background from other B meson decays and light-quark pair production. This inclusive tagging approach offers a higher signal efficiency compared to previous searches. No significant signal is observed. An upper limit on the branching fraction of B^{+}→K^{+}νν[over ¯] of 4.1×10^{-5} is set at the 90% confidence level.

Search for Axionlike Particles Produced in e^{+}e^{-} Collisions at Belle II

We present a search for the direct production of a light pseudoscalar a decaying into two photons with the Belle II detector at the SuperKEKB collider. We search for the process e^{+}e^{-}→γa, a→γγ in the mass range 0.2<m_{a}<9.7  GeV/c^{2} using data corresponding to an integrated luminosity of (445±3)  pb^{-1}. Light pseudoscalars interacting predominantly with standard model gauge bosons (so-called axionlike particles or ALPs) are frequently postulated in extensions of the standard model. We find no evidence for ALPs and set 95% confidence level upper limits on the coupling strength g_{aγγ} of ALPs to photons at the level of 10^{-3}  GeV^{-1}. The limits are the most restrictive to date for 0.2<m_{a}<1  GeV/c^{2}.

Search for an Invisibly Decaying Z^{'} Boson at Belle II in e^{+}e^{-}→μ^{+}μ^{-}(e^{±}μ^{∓}) Plus Missing Energy Final States

Theories beyond the standard model often predict the existence of an additional neutral boson, the Z^{'}. Using data collected by the Belle II experiment during 2018 at the SuperKEKB collider, we perform the first searches for the invisible decay of a Z^{'} in the process e^{+}e^{-}→μ^{+}μ^{-}Z^{'} and of a lepton-flavor-violating Z^{'} in e^{+}e^{-}→e^{±}μ^{∓}Z^{'}. We do not find any excess of events and set 90% credibility level upper limits on the cross sections of these processes. We translate the former, in the framework of an L_{μ}-L_{τ} theory, into upper limits on the Z^{'} coupling constant at the level of 5×10^{-2}-1 for M_{Z^{'}}≤6  GeV/c^{2}.

Induced pluripotent stem cells from hair follicles as a cellular model for neurodevelopmental disorders

Disease-specific induced pluripotent stem cells (iPSC) allow unprecedented experimental platforms for basic research as well as high-throughput screening. This may be particularly relevant for neuropsychiatric disorders, in which the affected neuronal cells are not accessible. Keratinocytes isolated from hair follicles are an ideal source of patients' cells for reprogramming, due to their non-invasive accessibility and their common neuroectodermal origin with neurons, which can be important for potential epigenetic memory. From a small number of plucked human hair follicles obtained from two healthy donors we reprogrammed keratinocytes to pluripotent iPSC. We further differentiated these hair follicle-derived iPSC to neural progenitors, forebrain neurons and functional dopaminergic neurons. This study shows that human hair follicle-derived iPSC can be differentiated into various neural lineages, suggesting this experimental system as a promising in vitro model to study normal and pathological neural developments, avoiding the invasiveness of commonly used skin biopsies.

Tibial pilon fractures

Tibial pilon fractures are severe injuries to the distal articular surface of the tibia. Such injuries frequently result from high-energy axial impact and are often associated with extended soft tissue injury. Various treatment methods are available, depending not only on the fracture type but mostly on the extent of the soft tissue injury; one of the most frequent procedures is a two-stage surgery: the initial closed reduction of the fracture via primary placement of an ankle joint-spanning external fixator, if possible in conjunction with open reduction and internal fixation of the fractured fibula followed by a secondary procedure after soft tissue recovery by open reduction and internal fixation of the tibial plafond. By now, new types of low-profile and locking plates are available for internal fixation allowing the anatomical reconstruction of the fractured articular surface while sparing the soft tissue. Nonetheless, the treatment of tibial pilon fractures is technically demanding because of their potential for severe complications.

Focal lesions of human hippocampal CA1 neurons in transient global amnesia impair place memory

A critical role in place learning has been attributed to place cells within the cornu ammonis 1 (CA1) sector of the hippocampus in rodents. The role of CA1 cells in the human hippocampus with regard to place learning remains elusive. Using a virtual Morris water maze, we investigated patients with acute transient global amnesia (TGA), a rare self-limiting dysfunction of the hippocampal system. Fourteen individuals with selective and focal lesions in the CA1 sector of the hippocampus showed a profound impairment in place learning. The size of the lesions and the duration of the TGA correlated with the deficit in the performance.

Surgical management of symptomatic spinal metastases. Postoperative outcome and quality of life

STUDY DESIGN

Eighty-six surgical interventions in 76 consecutive patients with symptomatic spinal metastases were reviewed retrospectively.

OBJECTIVES

To evaluate the postoperative outcome and quality of life of patients surgically treated for symptomatic spinal metastases.

SUMMARY OF BACKGROUND DATA

The standard surgical treatment for patients with symptomatic spinal metastases is anterior spinal cord decompression with stabilization. However, because therapy is only palliative, satisfactory quality of life and high patient acceptance are essential.

METHODS

The medical records of all patients were reviewed retrospectively. Furthermore, all surviving patients or the next of kin of deceased patients were interviewed by telephone, and the family doctors or the care-providing physicians of external institutions were contacted.

RESULTS

First-choice surgical treatment was anterior spinal cord decompression with stabilization. Postoperative mean survival was 13.1 months, and mean time at home after spinal surgery was 11.1 months. Neurologic improvement with regard to Frankel classification was observed in 58% of the patients, and 93% were able to walk postoperatively. Pain relief was noted in 89%. Overall, 67% of the patients achieved moderate or good general health as shown by the Karnofsky Index, and 80% were satisfied or very satisfied with the surgical intervention. Moreover, 19% of the surgical interventions were associated with complications, local tumor recurrence developed in 22% of the patients, and paraplegia ultimately developed in 18% of patients.

CONCLUSIONS

Surgical management of symptomatic spinal metastases, in particular anterior decompression, is of benefit in most metastatic lesions in terms of satisfactory postoperative outcome and quality of life. However, in patients with melanoma or lung carcinoma, the authors advocate spinal surgery only in very exceptional cases.

Mechanical behavior and biochemical composition of canine knee cartilage following periods of joint disuse and disuse with remobilization

The mechanical behavior and biochemical composition of articular cartilage were studied in an experimental model of joint disuse, in which the canine knee was immobilized in a sling at 90 degrees of flexion. Articular cartilage from the surface zone of the femur was tested in an isometric tensile test and full-thickness cartilage on the tibial plateau was tested in a compressive indentation test. Water, proteoglycan and collagen contents were measured in site-matched samples. Site-specific increases in the tensile moduli (approximately 88% above control values in distal femoral groove) were observed in cartilage after 8 weeks of joint disuse, and after 3 weeks of remobilization following either 4 (approximately 140%, distal and proximal femoral groove) or 8 weeks (approximately 140%, distal femoral groove) of joint disuse. In contrast, the compressive properties of cartilage determined in the indentation test exhibited no change from control values with joint disuse or disuse followed by remobilization. Water contents increased at some sites on the tibia after 8 weeks of joint disuse (approximately 6% of tissue wet weight, posterior site), but not in the surface zone tissue of the femur. Proteoglycan/collagen and cartilage thickness were not found to change with disuse or disuse followed by remobilization. Reduced values for the ratio of proteoglycan:water were observed in the surface zone tissue of the femur (approximately 23%, distal femoral groove) and in the full-thickness tissue of the tibia (approximately 21%, anterior and posterior sites) after periods of joint disuse. In this study, the measured material properties suggest that the articular surface remains intact following periods of disuse or disuse with remobilization. This finding suggests one important difference between this model of joint disuse and other experimental models in which cartilage changes are both progressive and degenerative, such as surgically-induced joint instability.

Centrifugal and biochemical comparison of proteoglycan aggregates from articular cartilage in experimental joint disuse and joint instability

Two models involving altered joint loading were compared with regard to their effects on the biochemical composition and proteoglycan aggregate structure of articular cartilage. Disuse atrophy was created in greyhound dogs by nonrigid immobilization of the right knee in 90 degrees of flexion, and joint instability was created by transection of the anterior cruciate ligament. Similarities and differences between the two experimental groups at two different time periods were examined to investigate why joint instability induces progressive and irreversible changes to the articular cartilage, whereas joint disuse induces changes that may be reversible when the joint is remobilized. The following studies were performed on the cartilage from all experimental and control groups: (a) compositional analyses to determine water, uronate, and hydroxyproline contents; (b) high performance liquid chromatography for detection of hyaluronan and chondroitin sulfates; and (c) centrifugation analyses of nondissociatively extracted and purified proteoglycans to isolate and quantify the populations of monomers and slow and fast-sedimenting families of aggregates. In general, all cartilage was found to have a decreased ratio of proteoglycan to collagen after 4 weeks of disuse, and this ratio returned to control values at 8 weeks. In contrast, cartilage had an elevated ratio of proteoglycan to collagen as well as increased hydration at 12 weeks after transection of the anterior cruciate ligament. The most striking contrast between the two models was the finding of an approximately 80% decrease in the content of hyaluronan at both time periods after transection of the anterior cruciate ligament, with no evidence of a change after disuse. The results of centrifugation analyses indicated a significant decrease in the quantity of proteoglycan aggregates in both models. However, this decrease was associated primarily with a loss of slow-sedimenting aggregates after disuse and a loss of both slow and fast-sedimenting aggregates after transection of the anterior cruciate ligament. Furthermore, the population of fast-sedimenting aggregates was depleted to a greater extent than that of the slow-sedimenting aggregates. The preservation of fast-sedimenting aggregates as well as hyaluronan after periods of joint disuse but not joint instability suggests a possible mechanism for the reversibility of cartilage changes. Although the proteoglycan aggregates were depleted after disuse atrophy, it is possible that an aggregate-depleted matrix could recover when normal proteoglycan synthesis is resumed. In contrast, although synthesis may be maintained or elevated after transection of the anterior cruciate ligament, the matrix may not be repopulated with aggregates because there is an insufficient amount of hyaluronan.

Mechanical properties of canine articular cartilage are significantly altered following transection of the anterior cruciate ligament

The compressive, tensile, and swelling properties of articular cartilage were studied at two time periods following transection of the anterior cruciate ligament in the knee of greyhound dogs. An experimental protocol was designed to quantify the essential equilibrium and biphasic material properties of cartilage in tension, compression, and shear, as well as the parameters of isometric swelling behavior. All properties were measured at several sites to elicit differences between sites of frequent and less frequent contact. Hydration was determined at each site and was compared with the material properties of cartilage from corresponding sites. There were extensive changes in all compressive, tensile, and swelling properties of cartilage after transection of the anterior cruciate ligament. Twelve weeks after surgery, the intrinsic moduli were reduced significantly in compression (approximately 24% of control values), tension (approximately 64%), and shear (approximately 24%), and the hydraulic permeability was elevated significantly (approximately 48%). Significant increases in hydration (approximately 9%) also were observed, as well as a strong correlation of hydration with hydraulic permeability. The pattern of these changes was not found to differ with site in the joint, but significant differences were observed in the magnitude of change for cartilage from the femoral groove and the femoral condyle. The pattern and extent of changes in the material properties following transection of the anterior cruciate ligament indicate that altered loading of the joint severely compromises the overall mechanical behavior of articular cartilage. The observed loss of matrix stiffness in compression, tension, and shear is associated with increases in the deformation of the solid matrix, a diminished ability to resist swelling, and the increase in hydration observed in this study. The increased swelling and elevated water content were related directly to the increase in hydraulic permeability; this suggests an associated loss of fluid pressurization as the load support mechanism in the degenerated cartilage. Without a successful mechanism for repair, damage to the solid matrix may progress and lead to further degenerative changes in the biochemistry, morphology, and mechanical behavior of articular cartilage.

Macro and micro rate zonal analytical centrifugation of polydisperse and slowly diffusing sedimenting systems in isovolumetric density gradients. Application to cartilage proteoglycans

A method to study the polydispersity of zonally sedimenting and slowly diffusing macromolecules or particles in isokinetic or isovolumetric density gradients is presented. First, a brief theory is given for predicting the zonal profile after a "triangular" (or "inverse") zone is centrifuged. This type of zone is essential to preserve hydrodynamic stability of the very slowly diffusing polydisperse solutes. It is proven, both by semitheoretical considerations and by computer calculations, that the resulting concentration profile of macrosolute is almost identical with that obtainable with a rectangular zone coextensive with the triangular one and carrying the same total mass. Next, practical procedures are described for the convectionless layering of very small triangular zones (50 microL or less). The linearity and stability of the zones are experimentally tested and verified. Finally, the method is applied to cartilage proteoglycan preparations that included either the monomeric molecules only or both the monomeric and the aggregated ones. The zonal results are compared with those obtained by using conventional boundary sedimentation. The two sets of results are seen to coincide fairly well, thus proving that the present technique can add to preparative zonal centrifugation the analytical precision of boundary sedimentation. A multimodal polydisperse system is suggested to describe the aggregated proteoglycan macromolecules.

Centrifugal characterization of proteoglycans from various depth layers and weight-bearing areas of normal and abnormal human articular cartilage

Ultracentrifugal polydispersity differential [g(S)] distributions were determined for the proteoglycans of various postmortem human articular cartilage samples extracted from six lateral patellar grooves in nondissociative conditions after mild collagenase digestion of the tissue. The samples consisted of 53 slices (250 microns thick), from normal, mildly fibrillated, and extensively ulcerated knee joints. When statistically analyzed in various subgroupings, the obtained average sedimentation coefficients and polydispersity profiles supported the following conclusions: (a) loss of proteoglycan aggregation and sedimentability is confirmed to be a primary sign of cartilage matrix degradation; (b) higher S values for proteoglycans of the high weight (HW)-bearing areas and lower values for those of the low weight (LW)-bearing areas were a typical finding in normal cartilage samples; (c) inversion of this pattern was indicative of matrix degradation, suggesting that the HW regions are more affected than the LW-bearing areas; (d) the average S value distribution across cartilage thickness tended to resemble the corresponding proteoglycan content versus distance from articular surface; and (e) the deepest cartilage layer had, in most cases, the smallest amount of aggregates while the highest average sedimentability was observed at the middle zone of the normal samples. In the discussion, a role of proteoglycan aggregation for providing a means to "pack" more proteoglycans within the collagen meshwork and to control the generation of osmotic pressure gradients is suggested.

Augmented glucose-6-phosphate dehydrogenase activity and normal penetration and metabolism of dehydroepiandrosterone in mononuclear leukocytes in psoriasis

The aim of the study was to determine a biochemical basis for the augmented oxidative metabolism found in mononuclear leukocytes (MNL) of patients with active psoriasis. Dehydroepiandrosterone (DHEA) is known to inhibit glucose-6-phosphate dehydrogenase (G-6-PDH). We determined the activity of G-6-PDH as well as the penetration and metabolism of DHEA - diminished plasma concentrations of which have been found in psoriatics previously - in 16 patients with active psoriasis and 16 controls. MNL in patients with psoriasis possessed 52% more (p less than 0.05) G-6-PDH activity, based on cell number, and 34% more (p less than 0.05) activity, based on soluble protein. No difference in DHEA penetration and metabolism in MNL was found between psoriatics and controls, in contrast with previous findings of reduced penetration and increased reduction in erythrocytes of psoriatics. We conclude that the enhanced G-6-PDH activity in MNL of patients with active psoriasis is not due to altered DHEA penetration or metabolism.

Boundary centrifugation in isovolumetric and isokinetic cesium sulfate density gradients: application to cartilage proteoglycans and other macromolecules

A boundary sedimentation methodology is described that avoids plateau dilution and simplifies the calculation of centrifugal parameters. The technique is designed for the preparative ultracentrifuge and uses a newly developed sectorial cell. It is based on previous developments of the transport method and depends on isokinetic or isovolumetric Cs2SO4 density and viscosity gradients. These gradients are prepared with a single-chamber mixing device, and the only two parameters required for their calculations are presented in a tabulated form for general use with most available rotors and cell sizes. Conditions are specified (1) to assure that the density and shape of the sedimenting molecules remain invariant through the selected electrolytic gradient, (2) to monitor the gradient profiles, and (3) to verify attainment of isokinetic or isovolumetric sedimentations. A set of equations is presented to calculate the average and transport sedimentation coefficients and the differential sedimentation coefficient distribution for both the isokinetic and isovolumetric centrifugal regimes. The method was applied to slowly diffusing polydisperse proteoglycan monomers, to a paucidisperse DNA from bacteriophage PM2, and to a diffusible monodisperse system (purified bovine serum albumin). In all cases, the expected results were obtained.

A simple electronic capillary microviscometer

Inexpensive electronic components were adapted to a miniaturized version of a falling-ball viscometer. This allowed automatic determination of relative viscosities of Newtonian fluids with 1% accuracy and employing only 10 to 30 microliters of sample or about 1 microgram of some biological materials. The electronic microviscometer was tested with bidistilled water at several temperatures, with CS2SO4 and glycerol solutions, several organic liquids, and some preparations of high-molecular-weight hyaluronic acid. Details of construction, circuitry, temperature control, operating procedure, and calculations are given as well as an evaluation of the instrument's performance in terms of previously established criteria.