Nitrogen metabolism of sheep and goats consuming Acacia brevispica and Sesbania sesban

We described the effects of two East African browses, Acacia brevispica and Sesbania sesban, on nitrogen metabolism of sheep and goats. The A. brevispica had a substantial amount of proanthocyanidins (condensed tannins); S. sesban did not. The browses were fed at three levels in combination with vetch (Vicia dasycarpa) and teff straw (Eragrostis abyssinica). Fecal N, N balance, and plasma urea N (PUN) were estimated with intact animals. Ruminal ammonia (RuA) and VFA concentrations were estimated with ruminally fistulated animals. Urinary N loss, PUN, RuA, and VFA concentrations were higher for S. sesban diets than for A. brevispica diets. Fecal N was highest with diets including A. brevispica due to high levels of fecal neutral-detergent insoluble N. Nitrogen retention was highest for diets including S. sesban. Nitrogen retention was adequate for A. brevispica diets because low urinary N compensated for high fecal N. Four hypotheses describe possible effects of tannins on N metabolism: 1) escape of protein from the rumen to the lower tract; 2) increased microbial yield; 3) increase in N-containing endogenous products; and 4) protein made indigestible in tannin-protein complexes. The effect of tannins in A. brevispica on N metabolism can best be described by the formation of indigestible tannin-protein complexes, although increased production of endogenous products is also possible.     

Biometrics: privacy's foe or privacy's friend?

From the INS to ATM's, both the public and private sectors are making extensive use of biometrics for human recognition. As this technology becomes more economically viable and technically perfected, and thus more commonplace, the field of biometrics will spark legal and policy concerns. Critics inevitably compare biometrics to Big Brother and the loss of individual privacy. The probiometric lobby generally stresses the greater security and improved service that the technology provides. Is biometrics privacy's friend or privacy's foe? This paper explores the various arguments for and against biometrics and contends that while biometrics may pose legitimate privacy concerns, these issues can be adequately addressed. In the final analysis, biometrics emerges as privacy's friend     

Analogs of 3-hydroxy-1H-1-benzazepine-2,5-dione: structure-activity relationship at N-methyl-D-aspartate receptor glycine sites

A series of aromatic and azepine ring-modified analogs of 3-hydroxy-1H-1-benzazepine-2,5-dione (HBAD) were synthesized and evaluated as antagonists at NMDA receptor glycine sites. Aromatic ring-modified HBADs were generally prepared via a Schmidt reaction with substituted 2-methoxynaphthalene-1,4-diones followed by demethylation. Electrophilic aromatic substitution of benzazepine 3-methyl ethers gave 7-substituted analogs. The preparation of multiply substituted 2-methoxynaphthalene-1,4-diones was effected via Diels-Alder methodology utilizing substituted butadienes with 2-methoxybenzoquinones followed by aromatization. Structural modifications, such as elimination of the aromatic ring, removal of the 3-hydroxyl group, and transfer of the hydroxyl group from C-3 to C-4, were also studied. An initial evaluation of NMDA antagonism was performed using a [3H]MK801 binding assay. HBADs demonstrating NMDA antagonist activity as indicated by inhibition of [3H]MK801 binding were further evaluated employing a [3H]-5,7-dichlorokynurenic acid (DCKA) glycine site binding assay. Selected HBADs were characterized for functional antagonism of NMDA and AMPA receptors using electrophysiological assays in Xenopus oocytes and cultured rat cortical neurons. Antagonist potency of HBADs showed good correlation between the different assay systems. HBADs substituted at the 8-position possessed the highest potency with the 8-methyl (5), 8-chloro (6), and 8-bromo (7) analogs being the most active. For HBAD 6, the IC50 in [3H]-DCKA binding assays was 0.013 microM and the Kb values for antagonism of NMDA receptors in oocytes (NR1a/2C) and cortical neurons were 0.026 and 0.048 microM, respectively. HBADs also antagonized AMPA-preferring non-NMDA receptors expressed in oocytes but at a lower potency than corresponding inhibition of NMDA receptors. HBADs demonstrating a high potency for NMDA glycine sites showed the highest steady-state selectivity index relative to AMPA receptors. Substitution at the 6-, 7-, and 9-positions generally reduced or eliminated glycine site affinity. Moving the hydroxyl group from C-3 to C-4 reduced receptor affinity, and potency was eliminated by the removal of the aromatic ring or the hydroxyl group. These data indicate that the HBAD series has specific structural requirements for high receptor affinity. With the exception of substitution at C-8, modified HBADs generally have a lower affinity at NMDA receptor glycine sites than the parent compound 3. Mouse maximum electroshock-induced seizure studies show that the three HBADs selected for testing have in vivo potency with the 6,8-dimethyl analog (52) being the most potent (ED50 = 3.9 mg/kg, iv).     

Prospects for silicon monolithic opto-electronics with polymerlight emitting diodes

We have fabricated a monolithically integrated photodetector and amplifier in silicon bipolar technology and organic polymer light emitting diodes (LED's) using both poly (p-phenylene vinylene) (PPV) and its soluble derivative poly (2-methoxy, 5-(2'-ethyl-hexoxy)-1,4-phenylene vinylene) (MEH-PPV). Based on the individual capabilities of the photo-receiver and LED, we have begun to evaluate the feasibility of monolithic integration of opto-electronics for silicon chip-to-chip communication using both PPV-LED's and Si photoreceivers on Si chips. LED's made from PPV and its soluble derivative such as MEH-PPV are thought to be process-compatible with Si IC technology. However, as an additional requirement, the polymer LED's must emit large enough power to be detected by the receiver with an acceptable bit-error-rate (BER)     

Concentrations of metals associated with mining waste in sediments, biofilm, benthic macroinvertebrates, and fish from the Coeur d''Alene River basin, Idaho

p64 is a protein identified as a chloride channel by biochemical purification from kidney microsomes. We expressed p64 in HeLa cells using a recombinant vaccinia virus/T7 RNA polymerase driven system. Total cell membranes were prepared from infected/transfected cells and fused to a planar lipid bilayer. A novel chloride channel activity was found in cells expressing p64 and not in control cells. The p64-associated activity shows strong anion over cation selectivity. Single channels show prominent outward rectification with single channel conductance at positive potentials of 42 pS. The chloride channel activity is activated by treatment of the membranes with alkaline phosphatase and inhibited by DNDS and by TS-TM calix(4)arene. Whole membrane anion permeability was determined by a chloride efflux assay, revealing that membranes from cells expressing p64 showed a small but highly significant increase in chloride permeability, consistent with expression of a novel chloride channel activity.     

Sleep-disordered breathing and neuropsychological deficits. A population-based study

The relationship of sleep-disordered breathing (SOB) to neuropsychological deficits was investigated with cross-sectional data from the Wisconsin Sleep Cohort Study, a population-based study of the natural history of SDB. A sample of 841 employed men and women ages 30 to 60 yr was studied by overnight polysomnography to assess the frequency of apneas and hypopneas per hour of sleep (apnea-hypopnea index, AHI). Prior to overnight polysomnography, the participants were given a battery of neuropsychological tests for functionally important capacities including motor skills, attention, concentration, information processing, and memory. Principal factor analysis of all the neuro-psychological test data revealed a psychomotor efficiency and a memory factor. Multiple regression analysis showed a significant negative association between logarithmically transformed AHI (LogAHI) and psychomotor efficiency score independent of age, gender, and educational status (p = 0.017). The relationship was not explained by self-reported sleepiness. No significant relationship was seen between LogAHI and memory score. In assessing the clinical significance of mild SDB, we estimate that an AHI of 15 is equivalent to the decrement in psychomotor efficiency associated with 5 additional yr of age, or to 50% of the decrement associated with hypnosedative use.     

Mobilising opposition: The campaign against housing action trusts in Tower Hamlets

This paper examines tenant opposition to the British government's plans for Housing Action Trusts (HATs), using material drawn from a case study of the tenants' anti‐HAT campaign in the London Borough of Tower Hamlets. After examining the HAT plans, the reasons for tenant objections to the privatisation of their council estates are explained. The political discourse of the anti‐HAT campaign is examined in order to assess the strategies by which support amongst tenants on both the affected estates, and in the borough as a whole, was mobilised. Strategies of resistance to the HATs were negotiated within the campaign through a constant process of discussion and debate about the purposes of the campaign and the construction of arguments against the policy. Central themes to emerge included a justification of the principles behind the provision of council housing; parallels that could be drawn between the HATs and the London Docklands Development Corporation; the notion that only tenant power could defeat the HATS; and arguments linking local experiences of the ‘housing crisis’ to the HATs and the government's housing policies more generally. The experience of this campaign underlines the necessity for potential divisions in such campaigns to be minimised in order to mobilise support and achieve their objectives.