Chimeric molecules created by gene amplification interfere with the analysis of somatic hypermutation of murine immunoglobulin genes.

We used the polymerase chain reaction (PCR) to amplify genes encoding murine immunoglobulin (Ig) lambda light-chain variable (V) regions, using DNA isolated from populations of germinal center B-cells, to study somatic hypermutation at this locus. Sequence analysis revealed that 30% of the amplified products were chimeric molecules consisting of segments of the V lambda 1 and V lambda 2 genes. Furthermore, an amplification- and cloning-associated artifact exchanged sequences between mutational variants of V lambda 1 genes. These PCR artifacts interfere with the analysis of somatic hypermutation of Ig genes. An alternative method that avoids these artifacts is suggested which involves the amplification of individual V lambda genes from single cells.

Patient information leaflets for prostate cancer: which leaflets should healthcare professionals recommend?

This study evaluated 31 patient information leaflets (PILs) discussing treatment options for prostate cancer. In stage one, the authors evaluated the leaflets' quality, readability and suitability using objective measures: the DISCERN instrument; Flesch formula; and the Suitability Assessment of Materials (SAM) instrument, respectively. Although the leaflets varied in terms of their scores on each measure, it was possible to identify the best five leaflets across the three conditions. In stage two, eight men with prostate cancer took part in a focus group discussion or individual interview to outline their views regarding a number of leaflets, including the best five booklets or leaflets identified in stage one of the study. The interviews were audiotaped and analysed using a template analysis. Patients were able to discriminate between the best five leaflets or booklets and identify their preferred booklets. These were the booklets: "Understanding cancer of the prostate" by CancerBACUP, "Prostate cancer: everything you need to know" by the Prostate Cancer Charity and "The treatment of prostate cancer. Questions and answers" by the Covent Garden Cancer Research Trust. On the basis of their high ratings for the objective measures and patients' views, healthcare professionals are advised to recommend these three booklets to men with prostate cancer who want written information about the disease. However, randomised controlled trials are needed to examine the impact of these booklets on the psychosocial outcomes of men with prostate cancer.

Pasture levels of tryptophan in relation to outbreaks of fog fever.

Oral administration of tryptophan induces in cattle clinical signs and lung lesions similar to those of fog fever. Tryptophan assays were performed by a microbiological method on various herbage samples. There was no significant difference in tryptophan content between herbage from two normal pastures and from three pastures in which outbreaks of fog fever occurred.

Effects on sheep of transport by road for up to 24 hours.

Five groups of 20 slaughter sheep of approximately 37.9 kg liveweight were transported by road for either three, nine, 15, 18 or 24 hours and three groups were not transported, one of them being deprived of food and water for 24 hours. Before and after transport the liveweight and various blood variables were measured and heart rate and behavioural observations were recorded from subsets of the animals. With increased journey time there was a decrease in liveweight and an increase in the plasma levels of free fatty acids, beta-hydroxybutyrate and urea; however, the changes over 24 hours were similar to those in the group deprived of food and water. In the transported sheep, the heart rate and levels of plasma cortisol and glucose were increased by the stresses of loading and the initial stages of the journey, but after nine hours the sheep appeared, to some extent, to have adapted. They were able to lie down and did not appear to be physically stressed. Measurements of plasma osmolality, total plasma protein and albumin did not indicate that the sheep had become severely dehydrated after 24 hours of transport but upon their return, feeding and drinking activity was greater than that observed before the journey.

Protein quality in cereals and pulses. 1. Application of microbiological and other in vitro methods in the evaluation of rice (Oryza sativa L.), sorghum (Sorghum vulgare Pers.), barley and field beans (Vicia faba L.).

1. The Streptococcus zymogenes assay procedure was modified and used in the estimation of available methionine and relative nutritional value in rice (Oryza sativa L.), sorghum (Sorghum vulgare Pers.), barley and field beans (Vicia faba L.). The results were assessed in relation to the content of tannins and 'dye-binding lysine', and to published information on the nutritional quality of some of the test samples. 2. In grain of ten varieties of sorghum, for which other workers had reported a correlation (r -0.82; P less than 0.01) between tannin content and amino acid digestibility in chicks, the available methionine content ranged from 6.3 to 17.7 g/kg protein (nitrogen x 6.25) and was highly correlated with tannin content (r -0.97; P less than 0.001). The content of total methionine and dye-binding lysine varied little between varieties and was not related to tannin content. 3. In nine samples of rice the availability of methionine was uniformly high, in accordance with literature values for true digestibility of the N. 4. In field beans the presence of tammins in the seed coat was associated with a significant (P less than 0.001) reduction in the availability of methionine. In eleven tannin-free varieties the coefficient of availability averaged 0.791, compared with 0.685 in eleven tannin-containing varieties. The standard deviation associated with both values was 0.04. There was no such difference between the corresponding dye-binding lysine values. 5. Thirty-three samples of barley were examined, representing fourteen varieties, four of which had been grown at several widely different latitudes in England and Sweden. There was little difference in methionine content between samples. The average availability coefficient for eighteen samples grown in England was 0.995+/-0.044, and for fifteen varieties grown in Sweden it was 0.851+/-0.042. The difference was not associated with any difference in tannin content, which was uniformly low. The findings contradict published evidence for marked increase in tannin content with increase in geographical latitude of cultivation, associated with decrease in digestibility of N.

Metabolism of heat-damaged proteins in the rat. Inhibition of amino acid uptake by "unavailable peptides" isolated from enzymic digests of heat-damaged cod fillet.

1. An extract containing "unavailable" small peptides was isolated from an enzymic digest of heat-damaged cod fillet and examined for its influence on uptake of leucine in the rat small intestine, using the everted-sac technique. 2. The extract strongly inhibited the uptake of leucine. It had no effect on uptake of glucose or its metabolism to lactate. 3. The findings are discussed in relation to the concept (Buraczewski, Buraczewska & Ford, 1967) that the accumulation of "unavailable peptide" material in the intestine, found in rats given heat-damaged protein, might hinder the absorption of amino acids by blocking a mechanism involved in their transport across the mucosal barrier.

Nutritional availability of methionine, lysine and tryptophan in fish meals, as assessed with biological, microbiological and dye-binding assay procedures.

In vitro assay procedures were applied in the measurement of available amino acids in a selection of fish meals representing good- and poor-quality product. Results were assessed by comparing them with results from chick-growth assays. Available methionine and tryptophan were assayed microbiologically with Streptococcus zymogenes, after predigestion of the test samples with papain or pronase. Results for methionine were correlated with chick-growth assays (r 0.86 for papain, 0.91 for pronase; P less than 0.01). Compared with the chick assays, papain tended to give lower, and pronase higher, results. Finer milling of the test samples did not influence the pronase values. Results for available tryptophan were also correlated with chick-growth assays (r 0.95 for papain, 0.96 for pronase; P less than 0.001). Compared with the chick values, papain gave markedly lower results and pronase marginally higher ones. Finer milling of the test samples increased the papain values by about 50% but had no effect with pronase. Available lysine was assayed microbiologically with Tetrahymena pyriformis and with a dye-binding procedure (DBL). The results correlated with the chick-growth assays (r 0.99 for DBL, P less than 0.001; 0.85 for Tetrahymena, P less than 0.01) but both methods overrated the poorer-quality samples. True nitrogen digestibilities and amino acid digestibilities were determined with chickens by the 'ileal analysis' procedure: the amino acid digestibilities were significantly higher and similar to the corresponding availabilities as measured in chick-growth assays. Ball milling a poor-quality fish meal caused a marked fall in its N digestibility, whereas similar treatment of a good-quality meal caused a slight increase. An explanation for this finding is proposed. Strep. zymogenes assays following pronase digestion of the test samples gave precise and acceptably accurate measures of the biologically available methionine and tryptophan in the test samples. For available lysine, Tetrahymena and DBL values for the poorer-quality samples were notably higher than the chick-growth assay; possible reasons for this are discussed. The ileal analysis procedure underestimated true N digestibility.

Protein quality in cereals and pulses. 3. Bioassays with rats and chickens on sorghum (Sorghum vulgare Pers.), barley and field beans (Vicia faba L.). Influence of polyethylene glycol on digestibility on the protein in high-tannin grain.

1. Two preceding papers in this series describe the application of microbiological and other in vitro tests in the evaluation of sorghum (Sorghum vulgare Pers.), field beans (Vicia faba L.) and barley, and in assessing the influence of polyethylene glycol (PEG 4000) on the nutritional availability of the methionine. The present paper gives for comparison the results of bioassays on some of the same test samples. Net protein utilization (NPU) in rats was measured by the nitrogen balance method, and N digestibility in chickens by the ileal analysis procedure. 2. In rat tests on sorghum, N in grain of high-tannin varieties was poorly digested. Supplementation of the test diets with 0.1 g PEG 4000/g protein gave a large improvemnet, which was partly offset by an apparent decrease in biological value (BV). With chickens N digestibility was even lower, and was similarly improved with PEG 4000. Treatment of high-tannin grain with ammonia solution was also effective in improving N digestibility. 3. With low-tannin sorghum the amino acid digestibilities were uniformly high and were not affected by addition of PEG to the test diet. With high-tannin sorghums they were low and less uniform, and were much improved by PEG 4000. 4. With field beans, the influence of the seed-coat tannin on protein utilization was much less pronounced than with sorghum. In chickens there was a significant effect (P less than 0.05) of PEG 4000 on N idgestibility in a high-tannin variety. With rats the effect was smaller and not significant. 5. In four samples of barley. N digestibility was high (0.87--0.96) and was not further improved by PEG 4000. The BV of a high-lysine cultivar proved marginally inferior to that of a normal variety. Possible reasons for this are discussed. 6. Over all, the results were closely consistent with those from microbiological tests with Streptococcus zymogenes.

Protein quality in cereals and pulses. 2. Influence of polyethyleneglycol on the nutritional availability of methionine in sorghum (Sorghum vulgar Pers.), field beans (Vicia faba L.) and barley.

1. Polyethyleneglycol (PEG 4000) was examined for its influence on relative nutritional value (RNV) and available methionine in sorghum (Sorghum vulgare Pers.), field beans (Vicia faba L.) and barley, as measured microbiologically with Streptococcus zymogenes. The results were assessed in relation to the content of tannins in the test samples. 2. In grain of hybrid sorghum the RNV averaged 87 (range 79--92) for six low-tannin varieties and 41 (30--53) for eleven high-tannin varieties. The corresponding available methionine values averaged 17.0 (15.7--18.9) and 8.9 (6.7--11.0) g/kg protein. Addition of PEG 4000 to the test samples increased the average RNV of the high-tannin varieties from 41 to 78, and the average available methionine content from 8.9 to 16.2 g/kg protein. 3. With seed of ten coloured flowered varieties of field beans, treatment with PEG gave a small but consistent increase in the available methionine content, which resulted from the inactivation of tannins in the testa. 4. In twenty-three samples of barley grain, treatment with PEG had no effect on the values obtained for available methionine. 5. Treatment of high-tannin sorghum grain with ammonia has been reported to inactivate the tannins and increase the nutritional value for rats and chicks. This finding was confirmed. The present study showed that ammonia and PEG 4000 were equally effective in enhancing the nutritional quality as measured in the microbiological tests.

Organization of the human interleukin-1 receptor antagonist gene IL1HY1.

The interleukin (IL)-1 family of proteins plays an important role in inflammatory and defense mechanisms. The recently characterized IL1HY1 cDNA encodes a new member of the IL-1 receptor antagonist family (IL-1ra). In this report, we describe the complete nucleotide sequence of the human IL1HY1 gene. We sequenced approximately 7,600 nucleotides and found four coding exons ranging in size from 55 to 2,288 nucleotides. The 5' untranslated region is formed by one of two alternatively used exons and one invariably present exon which also contains the region encoding the first nine amino acids of the protein. IL1HY1 and IL-1ra intron positions are well conserved within the protein-coding region, providing evidence that these genes arose from a duplication of a primordial IL-1 receptor antagonist gene.

L chain isotype regulation in horse. I. Characterization of Ig lambda genes.

Analysis of 10 cDNA encoding lambda L chains of horse Ig indicated that this species may employ a relatively small number of variable region (V lambda) genes in the splenic B cell population. The V lambda sequences of all of the cDNA analyzed were closely related (> 88% identity at the nucleotide level) and were characterized by a deletion of the amino acid residue at position 3 compared with V lambda sequences so far described in other species. The 10 V lambda sequences could be grouped into three groups, V lambda 1 to V lambda 3, on the basis of a number of linked substitutions. Sequences within the groups showed the greatest divergence in the third cdr regions and at the V-J junctions. The junctional variation included amino acid substitutions on both sides of the V-J junction as well as the insertion or deletion of two to four amino acid residues. Four C lambda genes were identified in genomic blots of horse DNA, and three of these were found expressed in splenic cDNA. The fourth C lambda gene may represent a pseudogene, inasmuch as the associated J region possessed a defective heptamer joining sequence. Six of the nine possible V lambda-C lambda combinations were found in the cDNA analyzed, suggesting that genes belonging to groups V lambda 1 through V lambda 3 may rearrange to any one of three J lambda-C lambda genes. One V lambda germline gene was characterized and found to represent a distinct V lambda group (V lambda 4), not represented in the cDNA sequences analyzed. The number of germline V lambda genes was estimated to be 20 to 30, based on analysis of restriction fragments hybridizing with V lambda probes. On the basis of these data, we propose that the V lambda repertoire in horse may consist of relatively limited number of genes, of which only a few may be used at high frequency in the splenic B cell population. The results indicate that predominance of lambda-chains in horse Ig may not simply be due to the presence of a large germline V lambda gene repertoire.

Polarization-selective computer-generated holograms: design, fabrication, and applications.

We constructed polarization-selective computer-generated holograms that apply an independent phase profile during readout by horizontal and vertical light polarizations. These elements are composed of two surface-relief-etched birefringent substrates joined face to face. We describe the design methodology for arbitrary birefringent substrate and gap materials. We show how these holograms are fabricated with standard microelectronics technology and discuss the effects of etching and alignment errors on performance. We demonstrated a diffraction efficiency of 60% with a polarization contrast ratio of >100:1 using a multilevel phase hologram made from two birefringent lithium niobate substrates. We also showed that a single-layer SiO(2) thin-film antireflection coating on all surfaces can reduce reflections from the high-index substrates without significant effect on hologram performance. We also consider some possible applications of this technology and demonstrate experimentally a dual focal-length lens and a self-interconnecting binary 2 × 2 polarization switch.

Programmable ultrashort optical pulse delay using an acousto-optic deflector.

We present an optical pulse delay (OPD) for delaying ultrashort optical pulses that uses an acousto-optic deflector as an active component. The OPD is designed to correct for chromatic dispersion caused by the significant color spectrum of ultrashort pulses. It is intended to be used as one of the components in a three-dimensional memory system based on pulse-collision addressing in two-photon materials. Calculations show that the OPD should be able to provide 65 arbitrary delays with a random access time of ˜ 1 µs for 100-fs pulses. The power efficiency of the OPD can be as high as 85% and hence permits two units to be cascaded to provide more than 4000 distinct delays. The number of delays and the access time can be optimized such that a fewer number of delays are obtained with a shorter access time, which favors high-speed operations. We provide experimental results that use a Michelson interferometer to measure three different delays, approximately 1 mm apart (equivalent to ˜3-ps time delay), obtained with 130-fs pulses. In addition we include an analysis of the performance of acousto-optic devices for both monochromatic light and ultrashort pulsed lasers. Finally, we provide the design of the optical pulse-delay system for a three-dimensional memory application.

Enhanced photorefractive performance from 45 degrees -cut BaTiO(3).

We have characterized the photorefractive performance of a special 45 degrees -cut crystal of BaTiO(3) and compared it with the conventional 0 degrees -cut material. An increased peak gain coefficient of 26 cm(-1) was measured using near normal beam incidence. Response times measured were ~1 order of magnitude faster than similar 0 degrees -cut crystals. The effects of an externally applied electric field parallel to the grating wave vector on the gain and response time were investigated. As an application example, the crystal was used to produce efficient and stable self-pumped image phase conjugation.

Time-integrating interferometry using photorefractive fanout.

We have experimentally demonstrated a single-beam interferometer that effectively subtracts an exponentially weighted history of the input from the current value, thus functioning as a novelty filter. The single-beam interferometer uses signal depletion due to noise amplification (fanout) in a specially cut crystal of photorefractive BaTiO(3). To demonstrate its real-time operation we used a Hughes liquid-crystal light valve to convert a video image into a phase- and/or amplitude-modulated input signal. Potential applications of this interferometer include image-clutter removal, motion detection and tracking, edge enhancement, and image time differentiation.

Reconfigurable array interconnection by photorefractive correlation.

Electronic parallel processors might communicate more effectively by photons sent through glass or air than by electrons sent through wires, but quickly routing thousands of optical signals remains a problem. Previous photorefractive interconnection networks have dedicated one hologram to each input channel. Instead, we compute a control image from the entire network configuration and store it as a single color-keyedvolume hologram. This lets us use hologram superposition for fast switchingbetween multiple prestored patterns. During operation, data signals from the input modulator array, powered by a shared wavelength-tunable laser, are correlated optically with one color-matched connection hologram to produce the output array. This decouples both data rate and interconnect switching speeds from the slow photorefractive response. We can display arbitrary connection weights using simple binary-phase spatial light modulators and gracefully accommodate modulator limitations by trading off control-image bandwidth for output signal-to-noise ratio. Experimental results with color-multiplexed reflection holograms in z-cut LiNbO(3) confirmed our theoretical predictions that this approach works best for densely connected networks with high fan-in to each output. We obtained an average aggregate signal-to-noise ratio of more than 200:1 for 1024 inputs and outputs.

Array interconnection by phase-coded optical correlation.

We present an algorithm for optical interconnection of two-dimensional arrays by transmitting the input through a phase-code mask then correlating it with a control image constructed from the interconnection weights. An arbitrary complex-weighted interconnection pattern can be encoded. We show how the output signal-to-noise ratio can be traded for control image size and complexity by adjusting the phase-code feature size. Theoretical calculations of the average output signal-to-noise ratio are compared with computer simulations of the algorithm.