Cleavage of single strand RNA adjacent to RNA-DNA duplex regions by Escherichia coli RNase H1

RNase H1 from Escherichia coli cleaves single strand RNA extending 3' from an RNA-DNA duplex. Substrates consisting of a 25-mer RNA annealed to complementary DNA ranging in length from 9-17 nucleotides were designed to create overhanging single strand RNA regions extending 5' and 3' from the RNA-DNA duplex. Digestion of single strand RNA was observed exclusively within the 3' overhang region and not the 5' overhang region. RNase H digestion of the 3' overhang region resulted in digestion products with 5'-phosphate and 3'-hydroxyl termini. The number of single strand RNA residues cleaved by RNase H is influenced by the sequence of the single strand RNA immediately adjacent to the RNA-DNA duplex and appears to be a function of the stacking properties of the RNA residues adjacent to the RNA-DNA duplex. RNase H digestion of the 3' overhang region was not observed for a substrate that contained a 2'-methoxy antisense strand. The introduction of 3 deoxynucleotides at the 5' terminus of the 2'-methoxy antisense oligonucleotide resulted in cleavage. These results offer additional insights into the binding directionality of RNase H with respect to the heteroduplex substrate.     

A scaled 0.25-μm bipolar technology using full e-beamlithography

The full leverage offered by electron-beam lithography has been exploited in a scaled 0.25-μm double polysilicon bipolar technology. Devices and circuits were fabricated using e-beam lithography for all mask levels with level-to-level overlays tighter than 0.06 μm. Ion implantation was used to form a sub-100-nm intrinsic base profile, and a novel in-situ doped polysilicon emitter process was used to minimize narrow emitter effects. Transistors with 0.25-μm emitter width have current gains above 80 and cutoff frequencies as high as 40 GHz. A record ECL gate delay of 20.8 ps at 4.82 mW has been measured together with a minimum power-delay product of 47 fJ (42.1 ps at 1.12 mW). These results demonstrate the feasibility and resultant performance leverage of aggressive scaling of conventional bipolar technologies     

Is it possible to predict limb viability in complex Gustilo IIIB and IIIC tibial fractures? A comparison of two predictive indices

The patient with severe lower limb trauma presents a management dilemma; whether to amputate primarily or to attempt limb salvage. In recent years, many predictive indices have been published which purport to identify limbs which are non-viable. We retrospectively applied two recently described indices, the Mangled Extremity Severity Score (MESS) and the Limb Salvage Index (LSI), to 54 limbs in 50 patients with either Gustilo IIIB or IIIC complex tibial fractures. There were 22 amputations (40.7 per cent) in the series. The mean MESS score in the limb salvage group was 3.8 (range 2-10), and the mean MESS score in the amputation group was 7.7 (range 4-13) (P < 0.0001). The mean LSI score in the limb salvage group was 3.6 (range 3-8), and the mean LSI score in the amputation group was 6.9 (P < 0.01). However, in the group with MESS scores > 7 (which recommends amputation), there were three limbs which were salvaged with acceptable functional outcome. Similarly, in those with LSI scores > 6 (which recommends amputation), there were seven limbs successfully salvaged. A MESS > 7 offered a greater relative risk of amputation (9.2) than a LSI score > 6 (5.3). We found both indices of use in predicting limb salvage and functional outcome. However, neither is sufficiently accurate to be considered absolutely reliable in clinical practice.     

A strategy for sampling on a sphere applied to 3D selective RF pulse design

Conventional constant angular velocity sampling of the surface of a sphere results in a higher sampling density near the two poles relative to the equatorial region. More samples, and hence longer sampling time, are required to achieve a given sampling density in the equatorial region when compared with uniform sampling. This paper presents a simple expression for a continuous sample path through a nearly uniform distribution of points on the surface of a sphere. Sampling of concentric spherical shells in k-space with the new strategy is used to design 3D selective inversion and spin-echo pulses. These new 3D selective pulses have been implemented and verified experimentally.     

Fusarium fungaemia in severely neutropenic patients

We report two cases of Fusarium infection with evidence of fungaemia in severely neutropenic patients with leukaemia. One patient was a 65-year-old woman with chronic lymphocytic leukaemia infected by Fusarium verticillioides. The other patient was a 45-year-old woman with acute myeloblastic leukaemia infected by Fusarium spp. Fungaemia was the only evident manifestation of these fungal infections.     

Morphological organization of the globus pallidus-subthalamic nucleus system studied in organotypic cultures

The morphological organization of the globus pallidus (GP), the subthalamic nucleus (STN), and the pallidosubthalamic projection was studied in organotypic cultures. Coronal slices from the GP, the STN, the striatum (CPu), and the cortex (Cx) were taken from the rat after postnatal days 0-2 and grown for 2 or 5-6 weeks. For analysis, immunocytochemistry against glutamate (GLU), parvalbumin (PV), and calretinin (CR) was combined with confocal microscopy. After 2 weeks in vitro, the STN showed a densely packed, homogeneous GLU-immunoreactive (ir) cell population. Pallidal GLU-ir neurons were heterogeneous, consisting of large-sized weakly GLU-ir neurons and small-sized intensively GLU-ir neurons. After 5-6 weeks in vitro, pallidal axons had radiated from numerous large-sized PV-ir cells and selectively innervated the STN, where they heavily ramified. Cultured STN neurons were not stained for PV; however, multipolar intensely PV-ir neurons were located at the border of the STN with their dendrites oriented towards the STN. Double labeling for PV and CR in both mature cultures and in the adult rat revealed that the culture CR-ir neurons from the GP, the Cpu, and from areas adjacent to the STN were different from cultured PV-ir neurons and their morphologies and distribution corresponded to that in vivo. These results demonstrate that 1) cultured CP and STN neurons display similar morphologies found in in vivo, 2) PV-ir pallidal neurons heavily and selectively innervate the STN; 3) there is a specific class of STN border neurons; and 4) in contrast to the in vivo situation, most cultured STN neurons are PV-negative.     

Abdominal compartment syndrome

PURPOSE: Two cases of abdominal compartment syndrome are described and the pathophysiology associated with it is reviewed. CLINICAL FEATURES: The first patient was a 46-yr-old man who sustained extensive blunt abdominal injuries following a fall. The second was a 54-yr-old man involved in a motor vehicle accident with blunt abdominal trauma. In both cases, the patients developed an extremely tense abdomen, increasing peak inspiratory pressures, hypercarbia and oliguria. Both demonstrated improvement in cardiac performance and ventilatory variables following an emergency decompressive celiotomy. CONCLUSION: Abdominal compartment syndrome results in impairment of organ function secondary to increased intraabdominal pressure. These patients require emergency decompressive celiotomy to relieve the symptoms. However, the incidence of intractable asystole and hypotension during this procedure is high and vigilance must be maintained during the release of the increased intraabdominal pressure.