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At least 1,531 records · Page 85Linked to original sources
PubMed1993

Ocular pathology in mice with a transgenic insertion at the microphthalmia locus.

A DNA insertional mutation at the microphthalmia locus (mi) in a transgenic mouse has been developed and given the allele symbol of mitg (Krakowsky et al., 1993). Mice homozygous for this transgene have eyes markedly reduced in size and relatively unpigmented. In this study, we examined the morphology of these eyes using light and electron microscopy. Transgenic homozygous (mitg/mitg) animals have a structurally normal choroid which lacks melanocytes but contains occasional leukocytes. The elastica of Bruch's membrane is absent except in an occasional site. The retinal pigmented epithelium (RPE) appears dramatically abnormal. It displays cellular heterogeneity, residual basal infoldings and apical microvilli, rare and immature melanosomes, and numerous cilia-like structures. Occasionally, cells of the RPE appear to have extruded into or from the choroid. The photoreceptor cells are devoid completely of outer segments and partially of inner segments. Numerous active macrophages are present between the amelanotic RPE and neuro-retina and also within the vitreous body. The anterior uveal tract is underdeveloped and hypomelanotic. This new microphthalmia model exhibits ocular pathology with similarities and differences to other mutations and the mi (microphthalmia) locus.

Alleles↗
PubMed1993

A helix-loop-helix transcription factor-like gene is located at the mi locus.

The mouse microphthalmia phenotype is complex and consists of one or more of the following phenotypic alterations: a lack of pigmentation, small eyes, a mast cell defect, and bone abnormalities. The locus for this allele has been assigned to chromosome 6. A single gene defect that produces such a pleiotropic effect has suggested some involvement at a control point in development. Recently a mutant line of mice carrying a transgene insertion, which represents a new allelic form of mi, was described. The integration site of the transgene from these mi(tg) mice was cloned and analyzed. An exon sequence was discovered adjacent to the insertion. Computer analysis of this nucleotide sequence revealed the presence of a motif indicative of the helix-loop-helix class of transcription factors. The gene was expressed in a number of tissues from wild type animals but was absent in the tissue RNA from mi(tg) mice. Southern blot analysis demonstrated a deletion of some of the genetic material for this gene in the mi(tg) mice. This is consistent with the lack of expression in the mi(tg) mice. Interestingly, when DNA from other mi allelic variants was subjected to a similar analysis, a deletion was also observed in this gene in two other mi lines. Taken together, these data suggest that the gene encoding this new helix-loop-helix DNA-binding protein, and residing in the mi locus, is a strong candidate for the mi gene.

Amino Acid Sequence↗
PubMed1996

[Histochemical studies on glycosaminoglycans in Bruch's membrane of experimental microphthalmic mice].

The Cts mouse is a mutant mouse of the Jcl:ICR strain which has congenital cataracts and small eyes in homozygotes. Therefore, this mouse could be a model for autosomal dominant cataract with microphthalmia in humans. In the present study, attempts were made to demonstrate light-microscopically the molecular species of glycosaminoglycans (GAG) in Bruch's membrane of Cts mice on day 14, 16, and 18 of gestation and at 0, 4, and 7 days after birth by means of combined sensitized high iron diamine staining and testicular hyarulonidase digestion procedures. In Bruch's membrane of the unaffected mice at all stages examined, no substantial amount of chondroitin sulfate A/C could be detected. In homozygous mice, however, a large amount of chondroitin sulfate A/C was contained in Bruch's membrane. These results indicate that the abnormal change in GAG molecular species induced the functional disorder of Bruch's membrane and could play a certain role in the etiology of microphthalmia in homozygotes.

Animals↗
PubMed1996

[A case of hemifacial oculo-oral anomalies].

In the present work is described a female with an incomplete oral duplication. The occurrence of a supernumerary mouth is rare. Moreover, these cases present other anomalies that make each one relatively unique. In this context, in fact, the patient presented an association of oral manifestation and ocular anomalies. From a pathogenetic point of view, maxillary duplication probably arises from a partial doubling of growth centers around the stomodeal plate.

Abnormalities, Multiple↗
PubMed1997

Nanophthalmic uveal effusion managed with scleral windows and topical mitomycin-C.

The authors treated a 38-year-old man with nanophthalmic uveal effusion with scleral windows and local application of mitomycin-C. The patient underwent two separate surgical procedures, involving placement of scleral windows in all four quadrants and topical application of mitomycin-C in one quadrant. Episcleral scarring led to closure of scleral windows in all quadrants except one quadrant where mitomycin-C was applied during the first surgery. The uveal effusion resolved following the second surgery. No complications related to mitomycin-C were observed. Topical mitomycin-C may be a useful adjunct in the surgical management of uveal effusion syndrome.

Administration, Topical↗
PubMed1997

Microphthalmia (mi) in murine mast cells: regulation of its stimuli-mediated expression on the translational level.

Mice harboring a mutation in the microphthalmia (mi) gene display a variety of abnormalities, including microphthalmia, depletion of skin melanocytes, deafness, a defect in osteoclasts, and a major decrease in mast cell number and function. However, despite the possible critical role played by this protein in mast cell development and function, characterization of its mRNA and protein synthesis in these cells has not yet been performed. In this study, we investigated the regulation of the synthesis of mi in murine mast cells activated by various physiologic stimuli. Using a specific rabbit polyclonal anti-mi antibody, we found that interleukin-3, interleukin-4, or aggregation of the mast cell high-affinity receptor for IgE (Fc epsilonRI) induced the synthesis of mi protein in these cells. None of these stimuli significantly affected the level of mi mRNA in the mast cells at any of the time points tested. Also, using this specific anti-mi antibody, an increase in mi protein synthesis was shown during differentiation of mast cells from their bone marrow cell precursors. Moreover, a complex containing mi bound to upstream stimulating factor 2 was detected only in activated mast cells. We conclude that the regulation of mi expression is on the translational level. Thus, stimulation of mast cells by a variety of stimuli elicits a signaling pathway that regulates mi expression.

Amino Acid Sequence↗
PubMed1996

[Expression of the mutant gene mi in mice: white spotting pattern].

Mice of mi/+ and +/+ genotypes of the mutant stock microphthalmia (mi) were mated inter se and with those of CC57BR/Mv and CBA/J inbred lines. In all types of crosses, the offsprings of mi/+ genotype had unpigmented fingers and distal tail parts (penetrance 100%). This trait is determined mostly by the mutant mi gene, the expression of which is not affected by modifier genes. However, the degree of mi gene expression, white spotting, on other body parts (wrist, foot, ventral body side, and parietal head part) varied widely in mice obtained from different crosses; penetrance ranged from 0 to 100%. The results obtained indicate that in these cases, the expression of mi gene was strongly affected by modifier genes. The different frequency of the mi gene effects, in heterozygote offspring obtained from reciprocal crosses, can result from the imprinting of the modifier genes in maternal and paternal gametes.

Animals↗
PubMedDate not supplied

[Clinical, diagnostic and therapeutic aspects of congenital anophthalmos].

This study was aimed at elucidating the diagnostic potentialities of computer-aided tomography (CAT) in congenital micro- and anophthalmia. Twenty-five young patients with various clinical manifestation of this abnormality were examined. Used in complex with the traditional diagnostic methods, CAT played the key role. It permitted imaging the entire complex of changes in the orbit and its contents, which helped choose adequate therapeutic measures. Surgical treatment was proven to be little effective or useless at all in cases with a more than 4 cm3 deficit of the orbital volume on the involved side; contrary to this, early staged fitting with prostheses is effective and creates favorable conditions for subsequent surgical correction in a less than 4 cm3 deficit of the volume.

Adolescent↗
PubMed1977

The mutual relations of structures in the growing bill of chick (Gallus domesticus L.) and duck (Anas platyrhynchos L.) Embryos. IV. The size, shape, and position of the upper and lower bills in unilaterally microphthalmic duck embryos.

Unilaterally microphthalmic duck (DUM) embryos studied in stage 39 were obtained by damaging the right eye in stage 17. The development between stages 19 and 39 was observed in samples. After prolonged incubation, one duck hatched and reached adulthood. In DUM embryos partial crossbeak develops. Both the upper and lower bills deviate lateralwards, the upper bill more than the lower. In stage 39 a small orbit is present on the treated side. In stained and cleared heads most of the elements of the skull (the bones surrounding the orbit, the brain-case, and the upper and lower bill elements) are translated in the direction of the rudimentary orbit on the treated side. The bills are twisted around each other at the tip. Measurements of external dimensions as well as those made in stained and cleared stage-39 DUM heads show elongation of the left part of the lower bill. Except for the crossed bills, the changes found in the embryos persisted in the adult. The findings support a hypothesis concerning the mutual influence of bills during morphogenesis. The coherence of the functional cranial components in the embryo is discussed.

Animals↗
PubMed1997

The oculo-dento-digital syndrome: male-to-male transmission and variable expression in a family.

We report two siblings--a 5 1/2 year old female and her 4 1/2 year old brother, both presenting the classical clinical findings of oculo-dento-digital dysplasia (ODD). 1. Digital anomalies: bilateral complete cutaneous syndactyly of fingers IV-V (III-IV-V at the left hand of the boy) and camptodactyly IV. 2. Facial and ocular anomalies: microphtalamos-epicanthal folds, small midfacies, thin nose with hypoplastic alae nasi and small nares. 3. Dental anomalies with partial dental agenesis and enamel hypoplasia. Examination of the parents showed a bilateral cutaneous syndactyly IV-V in the father as the sole partial manifestation of ODD. The findings in the present family confirm the autosomal dominant inheritance of ODD with great variability in clinical expression. Moreover, the facial morphology (thin, hypoplastic nose) observed in several ODD patients suggests nosological overlap with the Hallerman-Streiff syndrome and could indicate that both syndromes are variable expressions of a contiguous gene deletion syndrome.

Abnormalities, Multiple↗