Cyclic RGD Peptides Containing Azabicycloalkane Reverse‐Turn Mimics

The Fmoc‐protected lactams 3 and 4 were used to prepare cyclo(Arg‐Gly‐Asp‐lactam) 1 and cyclo(Arg‐Gly‐Asp‐Phe‐lactam) 2 , which contain the Arg‐Gly‐Asp (RGD) recognition motif. Their solid‐phase synthesis, conformational analysis, and binding to purified α_Vβ₃ and α_Vβ₅ integrins are reported. Compound 1 was found to act as an active and selective inhibitor of the α_Vβ₅ integrin.     

Histomorphometric analysis of glucocorticoid-induced osteoporosis

Bone histomorphometry or quantitative histology consists of counting or measuring tissue components: cells, extracellular constituents and microarchitecture. Bone histomorphometry is the only method that allows the measurement of mineralization rate and the study of bone formation at three levels: cell, remodeling unit and tissue levels. It is a useful tool to explain the pathogenesis and cellular mechanisms of different metabolic bone diseases such as glucocorticoid-induced osteoporosis (GIO).

Glucocorticoids (GC) affect calcium and bone metabolism at every level, but the main effect is the osteoblastic dysfunction.

Concerning the bone formation, some histomorphometric studies have shown a depressed osteoblastic activity at a cell, bone remodeling unit, and tissue levels. In addition, there is evidence of a shortening of the period in which the osteoblasts work actively forming the bone matrix. This latter effect seems to occur after high cumulative doses of GC. With regard to the resorption, the results are still debated, but histomorphometric parameters seem to be increased in the majority of studies, at least in the first period of the GC treatment. From a structural point of view, GC seem to induce a thinning of the trabeculae without their perforation, which occurs only after high cumulative doses. Antiresorptive treatments, such as bisphosphonates, are able to counteract the negative effects of GC on bone. In particular, along with their active working period, they prolong the lifespan of osteoblasts and osteocytes. In addition, the antiresorptive treatments seem to extend the time for secondary mineralization through a reduction of the Activation Frequency. The latter is an intriguing mechanism of bisphosphonates in GIO that needs further ad hoc investigations.     

Effects of parasitics in lowpass elliptic filters for mic

The possibility of realising 5th-or higher-order Cauer-Chebyshev lowpass filters by cascading rectangular microwave integrated structures is demonstrated. A new equivalent circuit of the rectangular element is introduced which accounts for the parasitic inductances due to higher-order modes. A simple adjusting procedure is developed which improves the passband behaviour of the filters, taking advantage of the presence of the parasitics.     

Evidence for a resonant structure of the hadron production from e+e− annihilations in the 1700–1950 cm energy region

We present experimental evidence for a resonant behaviour of the hadron production from e⁺e^? annihilations at the e⁺e^? storage ring ADONE. A Breit-Wigner fit to the enhancement present between 1800 and 1850 MeV gives the following parameters M = 1812_?13⁺⁷ MeV, Γ = 34_?15⁺²¹ MeV.     

Nanosize patterns as reference structures for macroscopic transport properties and vortex phases in YBCO films

This paper reports on the striking correlation between nanosize mosaic domain walls in YBCO films and 1D rows of parallel Josephson junctions, determining the J _c vs.B curves. From X-ray data analysis, it results that the average “hidden" domain wall, faceted at a nanometric scale, is almost mimicking the Josephson Junction (JJ) 1D array. The assumption that the JJs and the domain-wall arrays are coincident, enables to find out the particular scaling field, making the J _c vs.B curves independent of temperature. This scaling field can be interpreted in terms of the Josephson nature of the transport current across these particular patterns in the intermediate temperature range. By means of our model it is also possible to calculate two asymptotic behaviors of the pinning force as a function of field, for low and high fields, respectively. These behaviors are punctually repeated by the experimental results in the same asymptotic limit, so that two corresponding vortex regimes are clearly pointed out. All results can be interpreted by concluding that in the intermediate temperature range, the strong pinning observed in high quality YBCO films is due to the Josephson Junctions average patterns. These patterns are the counterpart related to the transport mechanisms of “hidden" structural nano-domains. Received 16 October 2000 and Received in final form 28 November 2000     

A Low-Power Reconfigurable Analog Filter for UMTS/WLAN Receivers

A low-power analog filter able to be reconfigured in order to be used in UMTS and WLAN applications is reported. The 4th order low-pass continuous-time filter is going to be included in the receiver path of a reconfigurable terminal. The filter is made up by the cascade of two Active-G$_m$-RC low-pass biquadratic cells. The unity-gain-bandwidth of the opamps embedded in the Active-G$_m$-RC cells is comparable to the filter cut-off frequency. Thus, the power consumption of the opamp can be strongly reduced. In addition, the filter can be programmed in order to process UMTS and WLAN signals, while a little area overhead is required since the filter can share capacitors as well as opamps in both operations modes. The cut-off frequency deviation due to the technological spread, aging and temperature variation is adjusted by using a tuning circuit.The full device in a 0.13 μ$m CMOS technology occupies a 2.8 mm²area.