[Bleeding origin, patient-related risk factors, and prognostic indicators in patients with acute gastrointestinal hemorrhages requiring intensive care treatment. A retrospective analysis from 1999 to 2010]. / Ursachen, patientenspezifische Risikofaktoren und prognostische Indikatoren bei akuter gastrointestinaler Blutung und intensivmedizinischer Therapieindikation. Eine retrospektive Untersuchung der Jahre 1999-2010.

BACKGROUND: Gastrointestinal bleeding (GIB) is a common problem in elderly patients involving severe comorbidities and concomitant antiplatelet or anticoagulatory therapy. The risk factors and prognostic indicators of patients with severe GIB requiring intensive care medical treatment have not been well evaluated. METHODS: A retrospective analysis of 7,376 patients from the medical intensive care unit (ICU) at the University Hospital Aachen was carried out between 1999 and 2010. RESULTS: Of 614 patients admitted to the ICU because of acute GIB, 463 (75%) presented with upper GIB (UGIB) and 151 (25%) with lower GIB (LGIB). Despite early endoscopic intervention and ICU treatment, UGIB had a mortality rate of 16%, whereas LGIB showed a significantly better prognosis (mortality <5%) in the ICU setting. Risk factors for OGIB-related mortality were hemodynamic instability, organ failure, comorbidities (especially liver cirrhosis), and rebleeding. In total, 218 patients (36%) were treated with antiplatelet or anticoagulatory drugs, which were associated with a favorable prognosis in the UGIB group. Elevated serum lactate levels upon admission were superior in predicting mortality than established indicators of prognosis such as the Rockall or the Glasgow-Blatchford score. CONCLUSIONS: Despite successful endoscopic intervention, severe acute UGIB is associated with a significant mortality rate of 16% in the ICU setting, determined by hemodynamic failure, organ dysfunction, and comorbidities. The serum lactate levels of patients with GIB on the day of admission to the ICU are prognostic.

[Gastrointestinal bleeding in liver cirrhosis at the ICU]. / Gastrointestinale Blutungen als Komplikation von Patienten mit Leberzirrhose auf der Intensivstation.

Due to portal hypertension and bleeding disorders, patients with liver cirrhosis are at increased risk for severe gastrointestinal bleedings (GIB), commonly requiring therapy at the intensive care unit (ICU). In order to identify epidemiological and prognostic factors for GIB in cirrhotic patients, we retrospectively analysed patients from our medical ICU from 1999 to 2010. Among 7376 critically ill patients, 650 (8.8 %) were diagnosed with liver cirrhosis. Hepatic cirrhosis was frequently found in ICU patients admitted due to severe GIB (23.2 % of 711 patients had cirrhosis). Moreover, patients with cirrhosis were at increased risk to develop severe GIB during intensive care treatment (40.9 % of 44 patients with GIB during ICU stay had cirrhosis). Besides the high rate of variceal bleedings (64.4 %) in cirrhotic patients, non-variceal haemorrhages were also common (28.5 %). We identified the MELD score and necessity of mechanical ventilation as independent risk factors for mortality in cirrhotic patients with severe GIB. Patients with liver cirrhosis and severe GIB had significantly impaired prognosis (case-related fatality rate of 26.1 % with cirrhosis vs. 6.8 % without cirrhosis), especially in cases of newly developed GIB during ICU therapy. Advanced therapeutic approaches and novel strategies are warranted to improve the critical prognosis of these high-risk patients.

[Validation of the new version of the minimal documentation system (MIDOS) for patients in palliative care : the German version of the edmonton symptom assessment scale (ESAS)]. / Validierung der neuen fassung des minimalen dokumentationssystems (MIDOS(2)) für patienten in der palliativmedizin : deutsche version der edmonton symptom assessment scale (ESAS).

BACKGROUND: repeated self-assessment of symptoms and problems of patients is required for quality assurance in palliative care. In Germany, the Minimal Documentation System (MIDOS) has been designed specifically for palliative care patients. To adapt MIDOS as a German version of the Edmonton Symptom Assessment Scale (ESAS) a revised version of MIDOS(2) has now been validated. Two original items on average and highest pain intensity (11-step NRS) were replaced by one item on pain intensity on a 4-step VRS and the assessment of vomitus, lack of appetite and depressive mood were added to the assessment of nausea, dyspnoea, constipation, weakness, tiredness, anxiety, others and well-being which were already part of the original version. METHOD: all patients admitted to the palliative care unit were asked to participate voluntarily in this study. MIDOS(2), the German versions of the ESAS and the quality of life questionnaire EORTC QLQ-C15-Pal were completed on the same day during their inpatient stay. MIDOS(2) was repeated on the next day. RESULTS: from August 2009 to March 2010, 60 patients (55% men, 45% women; mean age = 64.3, range = 23.6-92.4 years) treated in the palliative care unit completed the study. Self-assessment with MIDOS(2) was reported to burden the patients only slightly (mean burden = 1.1, range: 0 = no to 10 = maximum burden on a NRS), application of MIDOS(2) took between 1 and 7 min (mean duration = 2.4 min) and 61.7% of the patients preferred MIDOS(2) (with VRS) to ESAS (30%) (with NRS) for routine daily documentation. External criterion validity by inter-item correlations of MIDOS(2) with ESAS varied between r = .533 (anxiety) and .881 (nausea) and between r = .348 (depressive mood) and .717 (constipation) for the corresponding items of the EORTC QLQ-C15-Pal. Test-retest reliability between the sum scores of symptoms and problems reported in MIDOS(2) on the first day and on the second day was .688, and r = .573 for well-being. CONCLUSION: MIDOS(2) can be recommended for routine daily documentation in palliative care because of low burden, little expenditure of time and high participation of patients. Statistical evaluation indicated good external validity and reliability.

Expression of reverse cholesterol transport proteins ATP-binding cassette A1 (ABCA1) and scavenger receptor BI (SR-BI) in the retina and retinal pigment epithelium.

AIMS: Excessive lipid accumulation in Bruch's membrane (BrM) is a hallmark of ageing, the major risk factor for age-related macular degeneration (AMD). Retinal pigment epithelial (RPE) cells may utilise reverse cholesterol transport (RCT) activity to move lipid into BrM, mediated through ATP-binding cassette A1 (ABCA1) and scavenger receptor BI (SR-BI). METHODS: ABCA1 expression was assessed by reverse transcription polymerase chain reaction (RT-PCR) and western blotting of human RPE cell extracts. Lipid transport assays were performed using radiolabelled photoreceptor outer segments (POS). ABCA1 and SR-BI expression was examined in normal mouse eyes by immunofluorescence staining. BrMs of ABCA1 and SR-BI heterozygous mice were examined microscopically. RESULTS: Human RPE cells expressed ABCA1 mRNA and protein. The ABCA1 and SR-BI inhibitor glyburide (also known as glibenclamide) abolished basal transport of POS-derived lipids in RPE cells in the presence of high-density lipoprotein. Mouse retina and RPE expressed ABCA1 and SR-BI. SR-BI was highly expressed in RPE. BrMs were significantly thickened in SR-BI heterozygous mice, but not in ABCA1 heterozygous mice. CONCLUSION: RPE cells express ABCA1 and SR-BI. This implies a significant role for SR-BI and ABCA1 in lipid transport and RCT in the retina and RPE.

Quantitative genetics of age-related retinal degeneration: a second F1 intercross between the A/J and C57BL/6 strains.

PURPOSE: Previously, several quantitative trait loci (QTL) that influence age-related retinal degeneration (ageRD) were demonstrated in a cross between the C57BL/6J-c(2J) and BALB/cByJ strains (B x C). In this study, as a complementary approach to ongoing recombinant progeny testing for the purpose of identifying candidate quantitative trait genes (QTG), a second test cross using the A/J and the pigmented C57BL/6J strains (A x B) was carried out. The albino A/J strain was selected because it had the most amount of ageRD among several inbred strains tested, and the pigmented C57BL/6J strain was selected because along with its coisogenic counterpart C57BL/6J-c(2J) it had the least amount of ageRD. Thus, the effect of pigment on ageRD could be tested at the same time that the C57BL/6 genetic background was kept in common between the crosses from the two studies for the purpose of comparison. METHODS: A non-reciprocal F1 intercross between the A/J and C57BL/6J strains produced 170 F2 progeny. At 8 months of age after being maintained in relatively dim light, F2 mice, control mice and mice of other strains were evaluated for retinal degeneration by measurement of the thickness of the outer nuclear layer of the retina. The F2 mice were genotyped with dinucleotide repeat markers spanning the genome. Correlation of genotype with phenotype was made with Map Manager QTX software. RESULTS: Comparison of several strains of mice including the pigmented strains 129S1/SvImJ and C57BL/6J and the albino strains A/J, NZW/LacJ, BALB/cByJ and C57BL/6J-c(2J), showed significant differences in ageRD. The greatest difference was between the albino A/J strain and the pigmented C57BL/6J strain. However, there was no significant difference between the pigmented C57BL/6J and its albino coisogenic counterpart C57BL/6J-c(2J). Neither was there significant difference between the pigmented and albino F2 mice from the A x B cross. On the other hand, F2 males had a small but significantly lower amount of ageRD than females. Several QTL were identified in the A x B cross but surprisingly none of the 3 major QTL present in the original B x C cross (Chrs 6, 10, and 16) was present. There were minor QTL on proximal Chr 12 and proximal Chr 14 in common between the two crosses, and the proximal Chr 12 QTL was present in a previous light damage study involving the B and C strains. At least one sex-limited QTL was present on the X chromosome with a peak in a different location from that of a sex-limited QTL in the previous B x C study. In addition, the protective X allele was from the BALB/cByJ strain in the B x C cross and from C57BL/6J in the A x B cross. In both crosses, the C57BL/6J X-chromosome allele was recessive. CONCLUSIONS: Significant differences were observed in ageRD among several inbred strains of mice maintained in relatively dim light. AgeRD was not influenced by pigment but was influenced by gender, albeit to a small degree. The presence of the same QTL in one light-induced and two ageRD studies suggests at least partial commonality in retinal degeneration pathways of different primary cause. However, the three main QTL present in the B x C cross were absent from the A x B cross. This suggests that the genetic determinants responsible for the greater sensitivity to ageRD of BALB/cByJ and A/J relative to C57BL/6J are not the same. This is supported by the presence of sex-limited X-chromosome QTL in the two crosses in which the C57BL/6J allele is protective relative to the A allele and sensitive relative to the C allele. The findings in the two studies of differing allelic relationships of QTG, and differing QTL aid the identification of candidate genes mapping to critical QTL. Identifying natural modifying genes that influence retinal degeneration resulting from any causal pathway, especially those QTG that are protective, will open avenues of study that may lead to broad based therapies for people suffering retinal degenerative diseases.

Lack of p75 receptor does not protect photoreceptors from light-induced cell death.

Rod photoreceptors are susceptible to light-induced cell death. Previous results have suggested that the neurotrophin receptor p75 in Müller cells controls photoreceptor cell death during light-exposure by suppressing trophic factor release; and consequently, if p75 is blocked or eliminated during light-exposure, apoptosis is delayed. We explored this question by examining photoreceptor cell survival in albino p75(-/-) mice as well as their heterozygous and homozygous littermates. Photoreceptor cell death was examined in semi-thin sections by counting the remaining rows of photoreceptors. No difference in the amount of cell death was found between p75(+/+) and p75(-/-) animals, whereas the single copy of p75 in the heterozygous p75(+/-) mice provided significant neuroprotection. Cell death in the wild-type animals may indeed be mediated by p75, whereas other known apoptosis pathways may be activated in the p75(-/-) mice. The pro-apoptotic activity of the p75 receptor may have been partially suppressed in the heterozygous p75(+/-) mice by the silencing effect of the Trk receptor. Thus, our results suggest that p75 signaling does not mediate the main apoptosis pathway activated during light-damage.

Plant stress signalling: understanding and exploiting plant-plant interactions.

When plants are attacked by insects, volatile chemical signals can be released, not only from the damaged parts, but also systemically from other parts of the plant and this continues after cessation of feeding by the insect. These signals are perceived by olfactory sensory mechanisms in both the herbivorous insects and their parasites. Molecular structures involved can be characterized by means of electrophysiological assays, using the insect sensory system linked to chemical analysis. Evidence is mounting that such signals can also affect neighbouring intact plants, which initiate defence by the induction of further signalling systems, such as those that increase parasitoid foraging. Furthermore, insect electrophysiology can be used in the identification of plant compounds having effects on the plants themselves. It has been found recently that certain plants can release stress signals even when undamaged, and that these can cause defence responses in intact plants. These discoveries provide the basis for new crop protection strategies, that are either delivered by genetic modification of plants or by conventionally produced plants to which the signal is externally applied. Delivery can also be made by means of mixed seed strategies in which the provoking and recipient plants are grown together. Related signalling discoveries within the rhizosphere seem set to extend these approaches into new ways of controlling weeds, by exploiting the elusive potential of allelopathy, but through signalling rather than by direct physiological effects.

Insertional tagging of regulatory sequences in tritordeum; a hexaploid cereal species.

As an approach to isolate novel cereal promoters, promoterless uidA constructs and particle bombardment were used to transform tritordeum. Five of eight transgenic lines containing uidA sequences showed evidence of promoter tagging. Expression of uidA was detected in four lines as: constitutive expression, expression in short cells of the epidermis of the spikelets, expression in pollen grains and in cells of the epidermis of the spikelet, and expression in anther primordia and pollen grains. In the fifth line, the uidA was shown by RT-PCR to be transcribed, but no GUS activity was detected. The different patterns of uidA expression indicate that different regulatory sequences were tagged in each of these lines. Analysis of the progeny resulting from self-fertilisation of the primary tagged plants, indicate that the transgenes integrated at one or two loci and the patterns of expression were stably inherited. To our knowledge, this is the first report of promoter tagging in cereals by direct gene transfer.

Correction of the retinal dystrophy phenotype of the RCS rat by viral gene transfer of Mertk.

The Royal College of Surgeons (RCS) rat is a widely studied animal model of retinal degeneration in which the inability of the retinal pigment epithelium (RPE) to phagocytize shed photoreceptor outer segments leads to a progressive loss of rod and cone photoreceptors. We recently used positional cloning to demonstrate that the gene Mertk likely corresponds to the retinal dystrophy (rdy) locus of the RCS rat. In the present study, we sought to determine whether gene transfer of Mertk to a RCS rat retina would result in correction of the RPE phagocytosis defect and preservation of photoreceptors. We used subretinal injection of a recombinant replication-deficient adenovirus encoding rat Mertk to deliver the gene to the eyes of young RCS rats. Electrophysiological assessment of animals 30 days after injection revealed an increased sensitivity of treated eyes to low-intensity light. Histologic and ultrastructural assessment demonstrated substantial sparing of photoreceptors, preservation of outer segment structure, and correction of the RPE phagocytosis defect in areas surrounding the injection site. Our results provide definitive evidence that mutation of Mertk underlies the RCS retinal dystrophy phenotype, and that the phenotype can be corrected by treatment of juvenile animals. To our knowledge, this is the first demonstration of complementation of both a functional cellular defect (phagocytosis) and a photoreceptor degeneration by gene transfer to the RPE. These results, together with the recent discovery of MERTK mutations in individuals with retinitis pigmentosa, emphasize the importance of the RCS rat as a model for gene therapy of diseases that arise from RPE dysfunction.

Retinal degeneration in the nervous mutant mouse. IV. Inner retinal changes.

We have recently noted that the inner nuclear layer (INL) and the inner plexiform layer (IPL) were significantly thinner in mice homozygous for the nervous defect (nr / nr) than in control (nr /+ or +/+) littermates. Here, we have carried out a series of anatomical studies to further understand these inner retinal changes. At postnatal day (P) 13, there was no difference in the inner retina between nervous and control mice, while a significant difference was observed at P30. Similar changes were not seen in other mouse models of photoreceptor degeneration. There was a significant reduction in the density of cells in the INL that were stained by antibodies against the inhibitory neurotransmitters GABA and glycine. These results indicate that the nervous defect causes a degeneration of one or more sub-types of amacrine cells, in addition to the loss of cerebellar Purkinje cells and retinal photoreceptors that is known to occur in these mutant animals. Finally, evidence is provided that photoreceptors die by an apoptotic pathway in nervous mice.

Liver transplantation after organ preservation with normothermic extracorporeal perfusion.

OBJECTIVE: To study normothermic extracorporeal liver perfusion (NELP) as a means to preserve livers for transplantation and to reverse warm ischemic injury. SUMMARY BACKGROUND DATA: The authors provide experimental evidence that successful transplantation after 4 hours of normothermic extracorporeal liver perfusion is possible and as reliable as 4 hours of cold preservation in University of Wisconsin solution. NELP preserves liver function completely and can reverse 60 minutes of warm ischemic injury in non-heart-beating donors. METHODS: Thirty-six German Landrace pigs received transplants in six groups. Group 1 animals received direct transplantation. Group 2 received transplants after 4 hours of cold preservation with University of Wisconsin solution and Group 3 animals after 4 hours of NELP. Group 4 animals sustained 1 hour of warm ischemia before transplantation. Group 5 animals received transplants after 1 hour of warm ischemia and 4 hours of cold preservation and Group 6 animals after 1 hour of warm ischemia and 4 hours of NELP. RESULTS: All animals receiving livers treated by NELP survived more than 7 days after the transplant (Groups 3 and 6). In contrast, all animals in Group 5 developed primary graft nonfunction within 24 hours after transplantation. CONCLUSION: The technique of NELP holds the potential to keep a mammalian liver outside the body completely functional, possibly for more than 4 hours. NELP can be used for liver preservation before transplantation or for the use of organs from non-heart-beating donors.

Ribozyme rescue of photoreceptor cells in P23H transgenic rats: long-term survival and late-stage therapy.

Ribozyme-directed cleavage of mutant mRNAs appears to be a potentially effective therapeutic measure for dominantly inherited diseases. We previously demonstrated that two ribozymes targeted to the P23H mutation in rhodopsin slow photoreceptor degeneration in transgenic rats for up to 3 months of age when injected before significant degeneration at postnatal day (P) 15. We now have explored whether ribozyme rescue persists at older ages, and whether ribozymes are effective when injected later in the degeneration after significant photoreceptor cell loss. Recombinant adeno-associated virus (rAAV) vectors incorporating a proximal bovine rod opsin promoter were used to transfer either hairpin or hammerhead ribozyme genes to photoreceptors. For the study of long-term survival, rAAV was administered by subretinal injection at P15, and the rats were allowed to live up to 8 months of age. For the study of late-stage gene transfer, rAAV was administered at P30 or P45, when 40-45% of the photoreceptors already had degenerated. Eyes were examined functionally by the electroretinogram and structurally by morphometric analysis. When injected at P15, expression of either ribozyme markedly slowed the rate of photoreceptor degeneration for at least 8 months and resulted in significantly greater electroretinogram amplitudes at least up to P180. When injected at P30 or P45, virtually the same number of photoreceptors survived at P130 as when injected at P15. Ribozyme rescue appears to be a potentially effective, long-term therapy for autosomal dominant retinal degeneration and is highly effective even when the gene transfer is done after significant photoreceptor cell loss.

New roles for cis-jasmone as an insect semiochemical and in plant defense.

cis-jasmone, or (Z)-jasmone, is well known as a component of plant volatiles, and its release can be induced by damage, for example during insect herbivory. Using the olfactory system of the lettuce aphid to investigate volatiles from plants avoided by this insect, (Z)-jasmone was found to be electrophysiologically active and also to be repellent in laboratory choice tests. In field studies, repellency from traps was demonstrated for the damson-hop aphid, and with cereal aphids numbers were reduced in plots of winter wheat treated with (Z)-jasmone. In contrast, attractant activity was found in laboratory and wind tunnel tests for insects acting antagonistically to aphids, namely the seven-spot ladybird and an aphid parasitoid. When applied in the vapor phase to intact bean plants, (Z)-jasmone induced the production of volatile compounds, including the monoterpene (E)-beta-ocimene, which affect plant defense, for example by stimulating the activity of parasitic insects. These plants were more attractive to the aphid parasitoid in the wind tunnel when tested 48 h after exposure to (Z)-jasmone had ceased. This possible signaling role of (Z)-jasmone is qualitatively different from that of the biosynthetically related methyl jasmonate and gives a long-lasting effect after removal of the stimulus. Differential display was used to compare mRNA populations in bean leaves exposed to the vapor of (Z)-jasmone and methyl jasmonate. One differentially displayed fragment was cloned and shown by Northern blotting to be up-regulated in leaf tissue by (Z)-jasmone. This sequence was identified by homology as being derived from a gene encoding an alpha-tubulin isoform.

A QTL on distal chromosome 3 that influences the severity of light-induced damage to mouse photoreceptors.

C57BL/6J-c(2J) (c2J) albino mice showed much less damage to their photoreceptors after exposure to prolonged light than BALB/c mice and seven other albino strains tested. There were no gender differences, and preliminary studies suggested that the c2J relative protective effect was a complex trait. A genome-wide scan using dinucleotide repeat markers was carried out for the analysis of 194 progeny of the backcross (c2J x BALB/c)F(1) x c2J and the thickness of the outer nuclear layer (ONL) of the retina was the quantitative trait reflecting retinal damage. Our results revealed a strong and highly significant quantitative trait locus (QTL) on mouse Chromosome (Chr) 3 that contributes almost 50% of the c2J protective effect, and three other very weak but significant QTLs on Chrs 9, 12, and 14. Interestingly, the Chrs 9 and 12 QTLs corresponded to relative susceptibility alleles in c2J (or relative protection alleles in BALB/c), the opposite of the relative protective effect of the QTLs on Chrs 3 and 14. We mapped the Rpe65 gene to the apex of the Chr 3 QTL (LOD score = 19.3). Northern analysis showed no difference in retinal expression of Rpe65 message between c2J and BALB/c mice. However, sequencing of the Rpe65 message revealed a single base change in codon 450, predicting a methionine in c2J and a leucine in BALB/c. When the retinas of aging BALB/c and c2J mice reared in normal cyclic light were compared, the BALB/c retinas showed a small but significant loss of photoreceptor cells, while the c2J retinas did not. Finding light damage-modifying genes in the mouse may open avenues of study for understanding age-related macular degeneration and other retinal degenerations, since light exposures may contribute to the course of these diseases.

Local activation of nonspecific defense against a respiratory model infection by application of interferon-gamma: comparison between rat alveolar and interstitial lung macrophages.

Pulmonary macrophages play a crucial role in the defense of inhaled pathogens. We characterized functional properties of alveolar (AM) and interstitial (IM) macrophages from rats. AM exhibited a pronounced microbicidal capacity as shown by an elevated production of reactive oxygen intermediates (ROI), nitric oxide (NO), tumor necrosis factor (TNF)-alpha, and tumor cytotoxicity when compared with IM. In contrast, IM were superior to AM regarding mechanisms mainly involved in the induction and maintenance of specific immune reactions (major histocompatibility complex [MHC] class II expression, interleukin [IL]-1 and IL-6). In this line, we were interested in whether the microbicidal potential of AM could be augmented by treating Lewis rats with rat recombinant interferon (IFN)-gamma (5 x 10(2) to 1 x 10(5) U/animal) intratracheally, avoiding infection of interstitial lung macrophages or other organ-associated macrophages. The pulmonary cytokine application resulted in an activation of AM when macrophages from IFN-treated animals were compared with control macrophages from saline-treated rats 18 h after the treatment: (1) mediator release (ROI, NO, TNF-alpha, IL-6), (2) tumoricidal activity; (3) dose-dependent increase of MHC class II expression. The local immunomodulation enhanced the resistance of normal and immunosuppressed rats against respiratory infections with Listeria monocytogenes. Taken together, local activation of lung macrophages is a feasible therapeutic strategy against pulmonary infections.

Mutation of the receptor tyrosine kinase gene Mertk in the retinal dystrophic RCS rat.

Vertebrate photoreceptor cells are the basic sensory apparatus of the retina, capable of converting the energy of absorbed photons into neuronal signals. The proximal portions of mammalian photoreceptor outer segments are synthesized daily by cell bodies, and outer segment tips are shed with a circadian rhythm, resulting in a complete turnover of outer segments about every 9 days. The shed outer segments are phagocytosed by adjacent retinal pigment epithelial (RPE) cells, and metabolites are recycled to photoreceptors. The Royal College of Surgeons (RCS) rat is a widely studied, classic model of recessively inherited retinal degeneration in which the RPE fails to phagocytose shed outer segments, and photoreceptor cells subsequently die. We have used a positional cloning approach to study the rdy (retinal dystrophy) locus of the RCS rat. Within a 0.3 cM genetic inclusion interval, we have discovered a small deletion of RCS DNA that disrupts the gene encoding the receptor tyrosine kinase Mertk. The deletion includes the splice acceptor site upstream of the second coding exon of Mertk and results in a shortened transcript that lacks this exon. The aberrant transcript joins the first and third coding exons, leading to a frameshift and a translation termination signal 20 codons after the AUG. The concordance of these and other data indicate that Mertk is probably the gene for rdy. Our results provide genetic evidence for an essential role of a receptor tyrosine kinase in a specialized form of phagocytosis and suggest a molecular model for ingestion of outer segments by RPE cells.

The capacity to produce IFN-gamma rather than the presence of interleukin-4 determines the resistance and the degree of susceptibility to Leishmania donovani infection in mice.

The immune response against Leishmania donovani infection has been investigated in one resistant mouse strain (C3H/HeJ) and three susceptible mouse strains (C57BL/6, BALB/c, and B10D2/n). In order to correlate the strain-specific course of infection with the individual T cell response phenotype, the ex vivo cytokine secretion patterns of splenic lymphocytes were assessed by ELISA (interferon-y [IFN-gamma], interleukin-4 [IL-4], IL-10) or by bioassay (IL-2). The strain-dependent differences in the course of infection correlated closely with the potency of T cells to produce IFN-gamma. C3H/HeJ mice produced high amounts of IFN-gamma before and during infection, whereas susceptible mice produced low amounts of IFN-gamma early during L. donovani infection. However, C57BL/6 mice, which recovered from the infection rapidly after the acute stage, developed marked IFN-gamma response within the first 30 days of infection. In contrast, in BALB/c and B10D2/n mice, the IFN-gamma production diminished during the acute stage, and this was associated with a delay in recovery and with subsequent switching into the chronic stage. Interestingly, CD8+ T cells contributed significantly to IFN-gamma production during this phase. In contrast to IFN-y, the levels of IL-4 in response to antigen or mitogen ex vivo were always very low. Moreover, neutralization of endogenous IL-4 in vivo by treatment with soluble murine IL-4 receptor did not result in significant decreases in the parasite burdens in spleen and liver but did cause a decrease in the serum IgE level of L. donovani-infected BALB/c mice. These results confirm that in visceral leishmaniasis a Thl-dominated immune response is protective against the L. donovani parasites and, furthermore, that the capacity to produce IFN-gamma rather than the presence of IL-4 determines the efficacy of the immune response in susceptible mice. The data show that CD8+ T cells represent an important source of IFN-gamma during L. donovani infection in susceptible mice, implying a role for this cell type in healing and development of protective immunity.

Increased susceptibility to light damage in an arrestin knockout mouse model of Oguchi disease (stationary night blindness)

PURPOSE: To determine whether constitutive signal flow arising from defective rhodopsin shut-off causes photoreceptor cell death in arrestin knockout mice. METHODS: The retinas of cyclic-light-reared, pigmented arrestin knockout mice and wild-type littermate control mice were examined histologically for photoreceptor cell loss from 100 days to 1 year of age. In separate experiments, to determine whether constant light would accelerate the degeneration in arrestin knockout mice, these animals and wild-type control mice were exposed for 1, 2, or 3 weeks to fluorescent light at an intensity of 115 to 150 fc. The degree of photoreceptor cell loss was quantified histologically by obtaining a mean outer nuclear layer thickness for each animal. RESULTS: In arrestin knockout mice maintained in cyclic light, photoreceptor loss was evident at 100 days of age, and it became progressively more severe, with less than 50% of photoreceptors surviving at 1 year of age. The photoreceptor degeneration appeared to be caused by light, because when these mice were reared in the dark, the retinal structure was indistinguishable from normal. When exposed to constant light, the retinas of wild-type pigmented mice showed no light-induced damage, regardless of exposure duration. By contrast, the retinas of arrestin knockout mice showed rapid degeneration in constant light, with a loss of 30% of photoreceptors after 1 week of exposure and greater than 60% after 3 weeks of exposure. CONCLUSIONS: The results indicate that constitutive signal flow due to arrestin knockout leads to photoreceptor degeneration. Excessive light accelerates the cell death process in pigmented arrestin knockout mice. Human patients with naturally occurring mutations that lead to nonfunctional arrestin and rhodopsin kinase have Oguchi disease, a form of stationary night blindness. The present findings suggest that such patients may be at greater risk of the damaging effects of light than those with other forms of retinal degeneration, and they provide an impetus to restrict excessive light exposure as a protective measure in patients with constitutive signal flow in phototransduction.

Xenogeneic, extracorporeal liver perfusion in primates improves the ratio of branched-chain amino acids to aromatic amino acids (Fischer's ratio).

In fulminant hepatic failure (FHF), the development of hepatic encephalopathy is associated with grossly abnormal concentrations of plasma amino acids (PAA). Normalization of the ratio of branched-chain amino acids to aromatic amino acids (Fischer's ratio) correlates with clinical improvement. This study evaluated changes in PAA metabolism during 4 h of isolated, normothermic extracorporeal liver perfusion using a newly designed system containing human blood and a rhesus monkey liver. Bile and urea production were within the physiological range. Release of the transaminases AST, ALT and LDH were minimal. The ratio of branched (valine, leucine, isoleucine) to aromatic (tyrosine, phenylalanine) amino acids increased significantly. These results indicate that a xenogeneic extracorporeal liver perfusion system is capable of significantly increasing Fischer's ratio and may play a role in treating and bridging patients in FHF in the future.

Characterisation of genetic diversity in potential biomass willows (Salix spp.) by RAPD and AFLP analyses.

The genus Salix (willow) contains a number of species which have great potential value as biomass crops in short rotation coppice (SRC). Efforts to improve biomass willows by breeding are currently hampered by the limited information available on genetic diversity and on genetic relationships within and among species, clones, and hybrids in the gene pool. Hybridisation occurs commonly in nature and the relatedness of many clones is unclear. Molecular markers were used to assess genetic diversity in a reference set of willows maintained within the U.K. National Collection and 16 elite clones currently being evaluated in field trials at several European sites. The two marker systems tested, RAPDs and AFLPs, were equally informative for revealing relationships within the reference set of clones. No differences were observed when alternative similarity coefficients were compared or when analysis was restricted to the use of polymorphic bands only. Good agreement with available knowledge of the clonal origins was obtained and one instance of duplicate clones was identified. AFLPs revealed more genetic diversity and discriminated between closely related clones. A difference in the relationships revealed was observed with one AFLP primer combination. RAPDs were more problematic, both in terms of reproducibility and scorability.