[Chronic-idiopathic enteropathy in cats--a case control study]. / Die chronisch-idiopathische Enteropathie bei der Katze--Eine Fall-Kontroll-Studie.

Aim of this study is to clinically, microbiologically and histopathologically characterize inflammatory bowel disease (IBD) in the cat. Nine cats with chronic persistent or intermitent vomitus and diarrhea were examined between 1998 and 2001. All cats had a thuorough diagnostic workup performed. Full thickness biopsies from stomach, duodenum, jejunum, ileum and colon were surgically obtained for histopathological examination. Duodenal juice was obtained by direct aspiration for microbiologic qualitative and semiquantitative examination. Seven cats euthanized for other medical reasons were used as controls. Six cats had a lymphoplasmacytic IBD and three an eosinophilic IBD. Four cats with IBD had additional diseases diagnosed. Three cats with IBD had elevated bacterial counts. Retrospectively no correlation could be found between clinical symptoms and histopathological results. Serum TLI was not able to differentiate chronic pancreatitis and IBD. Serum folic acid and cobalamin did not correlate with the distribution of lesions in the gastrointestinal tract. Finally, no correlation was found between bacterial counts in the proximal duodenum and IBD.

Influence of laser irradiation on endogenous hyaluronan in rabbit iris and aqueous humor.

PURPOSE: To monitor changes of endogenous hyaluronan in the iris tissue and aqueous humor after an isolated trauma to the iris by argon laser irradiation of the anterior surface of the iris. METHODS: Iris and aqueous hyaluronan concentrations in rabbit were measured with a radiometric assay at different time points after laser irradiation. RESULTS: Total hyaluronan content in iris tissue increased 3-fold to a peak concentration of 71-72 microg/g at 1 and 2 days after laser treatment. Aqueous hyaluronan increased to a maximum of about 1.6 microg/ml at 2 h and 12 h after laser irradiation of the iris. CONCLUSIONS: The iris tissue responds with increased hyluronan synthesis to an isolated iris argon laser irradiation and it seems to be the most important source of aqueous hyaluronan.

Data reliability and structure in the Swedish National Cataract Register.

PURPOSE: A Swedish National Cataract Register was instituted in 1992, monitoring nearly all cataract operations in Sweden, and since its inception comprising about 95% of all operations. Data from a total of approximately 290 000 operations have been collected during 1992-1998. Data quality is an important factor, and we have therefore assessed the various types and frequencies of data entry errors in the material. METHODS: The medical records for all operations in five selected participating clinics were retrieved for a set month. Each data transfer step from the record to the final data base was monitored for a total of 574 operations. A total of 10 variables were recorded for each operation. RESULTS: Significant sources of error were absent in most variables. However, possibly important errors appeared in three: "date entering waiting list", "preoperative best corrected visual acuity in the operated eye", or "visual acuity in the fellow eye". There were also noteworthy variations between the five clinics, different for different parameters. Errors were predominantly prone to appear at the very first step of registration. In most cases this was due to deviations from the data collection instructions. CONCLUSIONS: The reliability is good for most values entered into the register, but it is important to ensure that data definitions are exact and adhered to. Repeated information to the involved persons on how to fill in the forms appears to be a requisite for maintaining good input quality.

Developmental expression of DCC in the rat retina.

The protein product of the deleted in colorectal cancer (DCC) gene possesses netrin-binding activity and may be involved in axonal guidance during retinal development. The temporal and spatial expression of DCC was analyzed in developing rat retina by means of immunoblotting and immunohistochemistry as well as by reverse transcription-polymerase chain reaction. Transient DCC protein expression is evident on ganglion cell axons in embryonic and neonatal retina. Double labeling experiments demonstrate DCC immunolabeling on processes that stratify in the inner plexiform layer and are derived from cholinergic amacrine cells. This pattern is maintained during the early postnatal period. DCC immunolabeling in the inner plexiform layer declines with age and is not observed in adult retina. The down-regulation of the DCC protein is confirmed by Western blot analysis. mRNA for DCC is expressed in embryonic, postnatal and adult retina and shows no correlation with the protein down-regulation. We suggest that DCC expression may be correlated with the functional segregation of the inner plexiform layer.

Immunohistochemical studies of cone photoreceptors and cells of the inner retina in feline rod-cone degeneration.

Previous studies using electroretinography and immunohistochemistry have shown normal cone function and structure in early stages of hereditary rod-cone degeneration of Abyssinian cats. To further investigate the cone photoreceptors and the inner retina of dystrophic cats, antibodies against green- and blue-sensitive cones and specific cell types of inner retina were used in seven cats with the recessively inherited rod-cone degeneration, and three normal European short-haired cats. There was a reduction in number of both types of cones early in the disease. Changes at early stages of disease also occurred among horizontal cells in which there was an extension and a thickening of their lateral processes. The regular configuration of bipolar cells was changed in the more advanced stages of disease and their apical dendrites were lost. Abnormalities were not observed in the amacrine cells and in the ganglion cell layer in any of the present cases. This study shows that the cone system is morphologically abnormal in young cats at an earlier stage of disease than previously shown. The present findings also support the assumption that the inner retina is largely preserved throughout the disease process.

Identification and localization of retinal cystatin C.

PURPOSE: Cystatin C is a mammalian cysteine protease inhibitor, synthesized in various amounts by many kinds of cells and appearing in most body fluids. There are reports that it may be synthesized in the mammalian retina and that a cysteine protease inhibitor may influence the degradation of photoreceptor outer segment proteins. In the current study cystatin C was identified, quantitated, and localized in mouse, rat, and human retinas. METHODS: Enzyme-linked immunosorbent assay (ELISA), reverse transcription-polymerase chain reaction (RT-PCR), DNA sequencing, Western blot analysis, and immunohistochemistry have been used on mouse, rat, and human retinas (pigment epithelium included). RESULTS: Cystatin C is present in high concentrations in the normal adult rat retina, as it is throughout its postnatal development. Its concentration increases to a peak at the time when rat pups open their eyes and then remains at a high level. It is mainly localized to the pigment epithelium, but also to some few neurons of varying types in the inner retina. Cystatin C is similarly expressed in normal mouse and human retinas. CONCLUSIONS: Cystatin C was identified and the localization described in the retinas of rat, mouse, and human using several techniques. Cystatin C is known to efficiently inactivate certain cysteine proteases. One of them, cathepsin S, is present in the retinal pigment epithelium and affects the proteolytic processing by cathepsin D of diurnally shed photoreceptor outer segments. Hypothetically, it appears possible that retinal cystatin C, given its localization to the pigment epithelium and its ability to inhibit cathepsin S, could be involved in the regulation of photoreceptor degradation.

Expression of nitric oxide synthase during the development of RCS rat retinas.

Nitric oxide (NO) has been reported to be both neurodestructive and neuroprotective in the central nervous system and could possibly play an important role in neurodegenerative disorders. On the assumption that NO synthesis may influence degenerative processes in the retina, we have examined the development and distribution of nitric-oxide-synthase(NOS)-immunoreactive cells in developing Royal College of Surgeons (RCS) rat retinas, which is an animal model for retinal degeneration. An antibody against constitutive neuronal NOS was used for immunocytochemistry on RCS rat retinas from postnatal (PN) days 3, 7, 10, 14, 35, 70 and 281 and compared with that in the normal rats of PN days 3, 7, 10, 14, 54 and adults. Immunoreactive cells were not seen in PN 3 retinas but were distinctly seen in the PN 7 retina along with a plexus in the inner plexiform layer. In both groups (normal and RCS rats) a distinct sublayering of the plexus in the inner plexiform layer could be seen at PN 10, which became more distinct at PN 14. The immunoreactive cells were detected also in the oldest retina examined, which was PN 281 in the case of RCS rats. In both groups, certain amacrine cells, certain bipolar cells and certain horizontal cells were found to be immunoreactive. In conclusion, the developmental timetable of the NOS immunoreactivity was identical in the normal and the RCS rat retinas. The NOS-immunoreactive cells persisted in the RCS retinas even when the retina had degenerated extensively. Abnormalities with the inducible isoforms of NOS cannot be ruled out from this study. We conclude that the chronological and qualitative development of the constitutive neuronal NOS immunoreactivity is normal in RCS rat retinas.

Survival of long-term retinal cell transplants.

PURPOSE: If retinal cell transplants are to be used in the management of retinal degeneration, they will need to survive in the eye for long time. This study assesses the fate of neural retinal transplants in the eye after long survival times. METHODS: Fragmented pieces of neural retinas from embryonic day 15 rabbits were transplanted to the subretinal space of adult animals of the same strain. The transplants were allowed to survive for up to 583 days prior to sacrifice and light microscopic examination. RESULTS: In most grafts, both neural and glial cells survived, however, some of the grafts seemed to contain predominantly glial cells. Only when the photoreceptors in the graft were apposed to the host pigmented epithelium did they survive. Otherwise, the neuronal components of the grafts were largely cells typically found in the inner retina. The long-term transplants were much thinner than short-term ones. Even after long survival times, the transplants lacked vascularization. No inflammatory cells were seen in or around the grafts. CONCLUSION: The results suggest that the cells of the inner retina survive for long periods after transplantation, but the photoreceptor cells seem to need the support of the host pigmented epithelium for long-term survival. It may therefore be important to have a transplantation technique where the graft photoreceptors can be placed in apposition with the host pigment epithelium.

Synthesis of hyaluronan by normal and wounded rabbit iris.

BACKGROUND: Endogenous hyaluronan has been found in different tissues in the normal and traumatized eye. However, the main source, the biological aspects and the full potential role of hyloronan are still unclear. METHODS: Hyaluronan production was studied both in organ culture and in vivo, using a double-label protocol with [35S]sulfate and [3H]glucosamine. RESULTS: [3H]glucosamine and [35S]sulfate were incorporated into hyaluronan and sulfated glycosaminoglycans in normal and in traumatized iris tissue in organ culture and in vivo. There was low relative hyaluronan synthesis in vivo, only 2% of total incorporated [3H]glucosamine in normal irides. Increased relative incorporation of [3H]glucosamine into hyaluronan was seen after operative trauma to iris tissue both in vivo and in vitro. CONCLUSION: Our findings demonstrate synthesis of hyaluronan by normal and traumatized iris. The iris seems to be the most important source of aqueous hyaluronan.

Phenotypic expression of juvenile X-linked retinoschisis in Swedish families with different mutations in the XLRS1 gene.

OBJECTIVE: To describe the clinical phenotype of juvenile X-linked retinoschisis in patients with different mutations in the XLRS1 gene. METHODS: Thirty patients with 7 different XLRS1 mutations were examined. The genotype was determined by molecular genetics, which identified 6 known and 1 novel mutation (exon 5, 489 G-->T). Ophthalmologic examination included full-field electroretinogram (ERG) recordings. RESULTS: The fundus appearance showed marked variations between, as well as within, families with different XLRS1 mutations. The ERG demonstrated typical reduction of B-wave amplitude, with relative A-wave preservation, causing a reduced B-A ratio in all affected males. The implicit time of the 30-Hz flicker ERG was prolonged in all patients examined. In a large family with a deletion of exon 1 and the promoter region, 12 affected males showed a phenotype ranging from moderate to severe vision impairment and a broad range of ERG abnormality, suggesting that additional factors may contribute to the disease severity. CONCLUSIONS: Juvenile retinoschisis shows a wide variability in the phenotype between, as well as within, families with different genotypes. The ERG findings show reduced B-A ratios of dark-adapted recordings and prolonged implicit times of 30-Hz flicker response, which provide a useful clinical marker to confirm the clinical diagnosis. CLINICAL RELEVANCE: This study describes the wide variability in the phenotype in patients with juvenile retinoschisis and different mutations in the XLRS1 gene. The study emphasizes the importance of complementing the ophthalmologic examination with full-field ERG and molecular genetics in boys with visual failure of unknown etiology to determine the diagnosis early in the course of the disease. Arch Ophthalmol. 2000;118:1098-1104

Growth of postnatal rat retina in vitro. Development of neurotransmitter systems.

In this study, we demonstrate that explanted neonatal rat retina can be maintained in culture for periods up to 3 weeks. The cultured retinas displayed a distinct layering that was almost identical to litter-matched retinas of the same age, but the majority of the ganglion cells did not survive and photoreceptor outer segments did not develop properly. Distinct synaptophysin immunoreactivity was expressed in both the inner and outer plexiform layers of cultured retina and the pattern mimicked that one observed in vivo. After 2-3 weeks in vitro, the inner retina expressed immunoreactivities to various components of the cholinergic and nitrergic transmitter systems, including nitric oxide activated cyclic GMP immunoreactivity. The investigated cell populations displayed similar distribution patterns as in situ, but morphological differences appeared in vitro. Such differences were mainly observed as irregularities in the arborization patterns in the inner part of the inner plexiform layer. We suggest that these discrepancies may arise as a result of reduced ganglion cell survival. Our observations demonstrate that some neurotransmitter systems develop in vitro and their neural circuitry appears similar to the in vivo situation. The presence of synapses, receptor proteins and transmitter substances implies that neural communication can occur in cultured retinas.

Full-field ERG in patients with Batten/Spielmeyer-Vogt disease caused by mutations in the CLN3 gene.

PURPOSE: To investigate, using full-field ERG, the retinal function in patients with Batten/Spielmeyer-Vogt disease caused by mutations in the CLN(3) gene. METHODS: Batten disease status of five patients was confirmed by the presence of vacuolated lymphocytes in peripheral blood and the identification of mutations in the Batten disease gene (CLN(3)). Visual acuity, fundus appearance, and full-field ERG were examined in all patients (age 4-19 years). The examination was repeated in one patient after 16 months. RESULTS: Three unrelated patients were homozygous for the most common mutation in CLN(3), the 1.02 kb deletion; two patients (sisters) were heterozygous for the 1.02 kb deletion and an as yet unidentified mutation in the CLN(3) gene. Full-field ERG recordings in all five patients demonstrated no rod responses and only small remaining cone responses, which could be detected with 30 Hz-flicker stimulation. Re-examination of a six-year-old girl after 16 months revealed a fast progression of the retinal degeneration. CONCLUSION: Full-field ERG recordings in Batten disease patients, both homozygous and heterozygous for the 1.02 kb deletion in the CLN( 3) gene, confirm retinal degeneration to be severe, widespread, and with a rapid progression early in the disease course. The onset of visual failure may be delayed when compared to the classic disease course, particularly in patients who are not homozygous for the most common CLN(3) mutation, a 1.02 kb deletion. In that case, the disease progression in terms of other symptoms may also be further delayed.

Tapetoretinal degenerations: experiences, experiments and expectations.

Tapetoretinal degenerations are a common cause for vision problems, but have until recently not been amenable to rational treatment. With rapidly increasing insights into basic neurobiology and pathobiology this has now begun to change. From having been a relatively small group of largely unknown yet fairly prevalent disorders, they are rapidly forming a large set of well defined diseases, and it is easy to predict that our knowledge about them will continue to increase for many years to come. Vitamin A (15,000 IU daily) is currently the only rational treatment available. However, in experimental animals, therapy strategies are now actively being developed along several different lines. Apoptotic photoreceptor cell death can be delayed with different drugs, and at least one of them, diltiazem, is approved for human use in cardiovascular diseases. It remains to be seen if it has any clinically significant effect in human tapetoretinal degenerations. Other strategies aim at counteracting the production of harmful protein variants, acting either on DNA or mRNA levels. Transgenes can also be used to induce the production of important but missing metabolic components. Finally, cells or retina sheets can be transplanted, either to replace failing cells or as a source for missing trophic factors. Neither of these strategies has yet been transferred to humans, but trials are under way. With the high increase in the flow of new information on tapetoretinal disorders, much more precise diagnoses and much improved treatments are soon to be expected, augmenting considerably the possibilities for ophthalmologists to help patients with such diseases. It is not likely that there will be a single treatment for all the many varieties. Instead, we are most likely going to see pharmacological treatments for some of them, DNA transfers for some, and transplantations for others.

NGF administered by microdialysis into rabbit vitreous.

PURPOSE: Microdialysis has been used in eye research for almost a decade. We have previously developed and used it mainly for chronic experiments and here it is used in acute experiments. It is highly suitable for both administration and withdrawal of substances from the eye, as it only permits molecules to cross the intraocular membrane without any net fluid movement in or out of the eye. METHODS: We have here investigated the ability of 125I labeled NGF (nerve growth factor) to cross a previously implanted high permeability membrane of a new type (polyether sulphone, PES, cutoff at 100000 daltons) in the rabbit vitreous. It was perfused for different time periods with a solution containing NGF The radioactivity of the entire vitreous was then counted. RESULTS: The results show detectable levels (up to 10(-11)M) of the substance after the perfusions. CONCLUSION: We conclude that microdialysis with PES membranes is a possible method for the intraocular administration of NGF.

Effects of the phosphodiesterase 4 inhibitor RPR 73401 in a model of immunological inflammation.

The study was performed to investigate effects of the phosphodiesterase 4 inhibitor RPR 73401 [N-(3, 5-dichloropyrid-4-yl)-3-cyclopentyl-oxy-4-methoxybenzamid] on an allergic skin reaction. To simulate an immunological inflammation, BALB/c mice were sensitized to dinitrochlorobenzene or toluenediisocyanate. At first, the abdominal skin was shaved and 50 microliter Freund's adjuvant were injected intracutaneously once. Then, the horny layer was removed by adhesive tape stripping and 100 microliter 0.5% dinitrochlorobenzene or 5% toluenediisocyanate were administered on the epidermis for 4 days. After repeated local treatment of the ear skin with 20 microliter 3% RPR 73401 or intraperitoneal administration of 1 and 5 mg/kg RPR 73401, 20 microliter 1% dinitrochlorobenzene or 0.5% toluenediisocyanate were given topically as a challenge. The vehicle controls showed a high increase in ear thickness over 48 h after challenge, whereas RPR 73401 administered on either route reduced this increase significantly. Nevertheless after topical administration, RPR 73401 had a longer lasting effect. These and other results may point to an indication for RPR 73401 in immunological dermatitis.

Full-thickness retinal transplants: a review.

Embryonic full-thickness rabbit neuroretinal sheets were transplanted to the subretinal space of adult hosts. This was accomplished by using a new transplantation technique involving vitrectomy and retinotomy. The grafts were followed from 10 to 306 days after surgery and were then examined by different histological techniques. In the light microscope, the transplants were seen to develop the normal retinal lamination and fusion with the host retina, especially after long survival times. Ultrastructurally, normal photoreceptor outer segments, well integrated with the host retinal pigment epithelium, were found. Growth cones were present in the zone of fusion between graft and host retina. Immunohistochemical labeling revealed many of the normal retinal components not previously found in retinal transplants, and graft-host connections between neurons in the rod pathway were seen. The morphology of vibratome-sectioned neuroretinal sheets as well as adult full-thickness grafts was also examined. These transplantation types showed less of the normal morphology compared with embryonic full-thickness grafts. The immunogenicity of embryonic full-thickness and fragmented grafts was compared using major histocompatibility complex immunolabeling. Fragmented grafts elicited a response from the host immune system similar to a chronic transplant rejection. This reaction was absent in the full-thickness grafts which is in accordance with their good long-term survival.

Ultrastructure of retinal cells transplanted to the rabbit choroid.

PURPOSE: Allogenic rabbit-to-rabbit retinal cell transplants survive in the choroid, which is not as expected because it has not been shown that this is an immune-privileged site. We have therefore examined the ultrastructure of such transplants, looking for features that might explain the phenomenon. METHODS: Rabbit retinal tissue fragment transplants were produced with previously described methods. The donor age was 15 days and the transplants were examined by standard electron microscopy when the transplants were 1-2 months (3 transplants) or 3-4 months old, of postconception age (3 transplants). RESULTS: The transplants survived and developed as expected from previous observations. Rosettes were seen, but they were not as common as in transplants produced with the same technique in the subretinal space of rabbits. Photoreceptor outer segments were not seen in the transplants. At 1 month, there was an incomplete sheath of Müller cells around the transplants, and a complete one at 3-4 months. There was also a well-developed basement membrane around the transplant at 3-4 months, but less so at 1 month. Blood vessels did not enter the transplant. The fenestrations in the choriocapillaris were not affected as long as the pigment epithelium was normal. CONCLUSIONS: The enclosure of the transplants by Müller cells might help to insulate them from the immune system of the host, but it is a late phenomenon and it is not likely to have much effect for the first few weeks after the transplantation. We suspect that either the rabbit choroid is an immune-privileged site, even though there is no previous direct evidence for this, or that the retinal tissue itself is responsible for the prolonged survival at this site.

Immunohistochemical analysis of the developing inner plexiform layer in postnatal rat retina.

PURPOSE: To investigate the development from early postnatal life to adulthood of neural cell processes that establish the circuitry of the inner plexiform layer (IPL). Emphasis was focused on the ontogeny of subsets of cGMP- and protein kinase C (PKC)immunoreactive amacrine and bipolar cells. METHODS: Paraformaldehyde-fixed postnatal and adult retinas were used for light microscopic analysis of immunohistochemical labeling of cryo-sections. Synthesis of cGMP in neural structures was achieved by means of an in vitro stimulation with a well-established nitric oxide donor. RESULTS: In vitro stimulation of postnatal and mature retina with the nitric oxide donor results in NO-activated cGMP synthesis in subsets of bipolar and amacrine cells. NO-activated cGMP immunoreactivity is expressed in specific cell populations during the first postnatal week. Other cell subsets, consisting of amacrine cells and rod bipolar cells, express PKC immunoreactivity during postnatal development. An increasing number of rod bipolar cells start to exhibit cGMP labeling after eye opening, and a colocalization with PKC is established in adult retinas. Processes from these cell populations terminate in several sublaminas in the developing IPL, but cGMP- and PKC-labeled terminals appear to be confined to ON-lamina as the retina matures. CONCLUSIONS: The development of cGMP- and PKC-labeled fibers within the IPL appears to be in concert with events of neural differentiation and synaptogenesis. These results suggest that the nitric oxide/cGMP signaling pathway and PKC may participate in activity-dependent processes during development that establish the mature circuitry of synaptic contacts within the IPL. The presence of cGMP in mature rod bipolar cells suggests a role in the signal transduction of rod bipolar cell-AII amacrine cell pathway.