Lacrimal canalicular obstructions: safety and effectiveness of balloon dilation

PURPOSE

Balloon dilation of the lacrimal canaliculi has been considered contraindicated because of possible damage to the canaliculi. The purpose of this study was to assess the safety and effectiveness of balloon dilation in treatment of obstruction of the lacrimal canaliculus.

MATERIALS AND METHODS

Fluoroscopically guided balloon dilation was performed in 26 eyes of 21 consecutive patients with epiphora due to lacrimal canalicular obstruction confirmed at dacryocystography. Nine of 26 eyes had complete obstruction and 17 eyes had incomplete obstruction.

RESULTS

Technical failure occurred in one eye. Only one acute complication (punctal slitting) and no late complications occurred. At 7 days after balloon dilation, 14 of 17 eyes (82%) with incomplete obstruction and five of nine eyes (56%) with complete obstruction showed complete or partial resolution of epiphora with patency of the lacrimal drainage system. At 6-month follow-up, that improvement was maintained in seven of 17 eyes (41%) with incomplete obstruction and three of nine eyes (33%) with complete obstruction.

CONCLUSIONS

Although the 6-month recurrence rate is rather high, balloon dilation seems to be safe and valuable as an initial therapy for patients with obstruction of the lacrimal canaliculus.

Nonsurgical placement of a nasolacrimal polyurethane stent: long-term effectiveness

PURPOSE

To evaluate the long-term effectiveness of a polyurethane stent in the treatment of obstruction of the lacrimal sac and the nasolacrimal duct.

MATERIALS AND METHODS

Fluoroscopically guided placement of a polyurethane nasolacrimal stent was evaluated in 283 obstructed lacrimal systems of 236 patients, with a follow-up period of more than 1 year (range, 52-134 weeks). The obstruction was at the junction between the lacrimal sac and the nasolacrimal duct in 192 systems, at the lacrimal sac in 52, and at the nasolacrimal duct in 39. The causes of obstruction were traumatic in 34 and idiopathic in 249 systems.

RESULTS

Stent placement was technically successful in 270 systems (95%). At 7 days after stent placement, 235 (87%) of the 270 systems with successful placement demonstrated complete resolution of epiphora, 27 (10%) had partial resolution, and the remaining eight (3%) had no resolution. There was recurrence in 81 systems due to obstruction of the stent (n = 77) or obstruction of the common canaliculus (n = 4). The recurrence rate was much higher in the systems with obstruction at the lacrimal sac (64%) than in the systems with obstruction at the junction (26%) between the lacrimal sac and nasolacrimal duct or at the nasolacrimal duct (15%).

CONCLUSION

Stent placement in the obstructed lacrimal system below the junction between the lacrimal sac and the nasolacrimal duct is valuable as an initial therapy.

A novel MADS-box gene of potato (Solanum tuberosum L.) expressed during the early stages of tuberization

A potato MADS-box gene cDNA (POTM1-1) from an early tuber cDNA library has been isolated and characterized. The deduced amino acid sequence of POTM1-1 cDNA encodes 250 amino acids of a putative transcription factor containing a MADS-box domain and a K-box domain. These conserved domains share high homologies to those of flower-specific homeotic proteins, TM4 of tomato and AP1 of Arabidopsis, indicating that POTM1-1 gene is a homologue of the AP1 gene family. The levels of POTM1-1 transcripts were high in axillary buds, underground stolen tips, and newly formed tubers, but relatively low in mature tubers. During axillary bud development in a model petiole-leaf cutting system, the levels of POTM1-1 transcripts were abundant in actively growing shoots and during the early stages of microtuber development. It is possible that POTM1-1 functions as a transcription factor that regulates plant developmental processes in a number of tissue types.

Local expression of a POU family transcription factor, Pit-1, in the rat placenta

A pituitary-specific trans-acting factor, Pit-1 regulates transcriptional activity of growth hormone (GH) and prolactin (PRL) genes. Pit-1 can bind and activate the promoters of human chorionic somatomammotropin (hCS-A) and placental GH variants (hGH-V) as well. However, expression of Pit-1 in the rat placenta has not yet been elucidated. The present study aims to determine whether the Pit-1 gene is locally expressed in the rat placenta using reverse transcription-polymerase chain reaction (RT-PCR), Northern blot and Western blot hybridization, in situ hybridization and immunohistochemistry. PCR products were further analyzed by Southern hybridization and DNA sequencing. The estimated size of Pit-1 mRNA in placenta was very similar to that in anterior pituitary (AP). PCR products from placenta were exactly the same size with that from AP and confirmed as Pit-1-specific by Southern hybridization. The Pit-1 specific sequence was also confirmed by sequencing of partial amplification fragments. Immunoreactive 33 kDa Pit-1 was present in the placenta as well as in AP. Pit-1 specific mRNA and protein were localized in the trophoblast cells of placenta. These data suggest that Pit-1 is locally synthesized in the rat placenta and may be involved in the regulation of GH- and/or PRL-like gene expression in the placenta.

Lacrimal canaliculus obstruction: nonsurgical treatment with a newly designed polyurethane stent

A newly designed polyurethane stent was used to successfully treat 30 eyes (in 28 patients) with epiphora resulting from obstruction of the lacrimal canaliculus. After stent placement, epiphora resolved in all eyes. During follow-up, epiphora recurred in 20 eyes, but epiphora did not recur and the lacrimal canaliculus was patent in 12 eyes after the stent was removed. The stent appears to be valuable for nonsurgical treatment of obstruction of the lacrimal canaliculus.

Nucleotide sequences of novel potato (Solanum tuberosum L.) MADS-box cDNAs and their expression in vegetative organs

Two similar, apparently full-length potato cDNAs, POTM1-1 and POTM1-2, from an early tuber cDNA library have been identified and sequenced. These two cDNAs encode 250 identical amino acids (aa) including 56 aa of the MADS-box domain and 53 aa of the K-box domain, indicating that they may function as transcription factors. The transcripts of these cDNAs accumulate abundantly in vegetative organs, suggesting that these novel MADS genes may be involved in vegetative organ development of potato.

Upstream promoter elements are sufficient for selenocysteine tRNA[Ser]Sec gene transcription and to determine the transcription start point

The TATA box, located upstream at about nt -30, and the proximal sequence element, located at about nt -60, are both essential and sufficient for basal level transcription of the Xenopus laevis (Xl) selenocysteine (Sec) tRNA[Ser]Sec gene as demonstrated by its microinjection into Xl oocytes. Point mutations within either of these regions abolish transcription, while deletion of the internal boxA element or insertion of 13 nt within the internal boxB element does not impair transcription. The latter mutations (within the internal regions) affect processing of the 3'-trailer sequence. Replacement of the tRNA[Ser]Sec coding sequence with an Escherichia coli M1 RNA gene resulted in expression of the E. coli gene governed by the upstream tRNA[Ser]Sec promoter elements. These studies demonstrate unequivocally that the upstream promoter elements are sufficient for the basal level of tRNA[Ser]Sec gene transcription. Primer extension studies with spacer mutants show that the internal elements do not play a role in selecting the transcription start point (tsp), but that selection of the tsp is determined by the region upstream from the gene. Further, studies with spacer mutants show that the distance between the TATA box and the tsp is quite likely the critical factor in selecting the position of tsp.

Changes in mRNA levels of a pituitary-specific trans-acting factor, Pit-1, and prolactin during the rat estrous cycle

The present study examined the changes in mRNA levels of a pituitary-specific trans-acting factor, Pit-1, and prolactin during the rat estrous cycle. Total cytoplasmic RNA was analyzed by Northern blot and slot-blot hybridization to examine the prolactin mRNA level. Reverse transcription-polymerase chain reaction (RT-PCR) was performed to examine the Pit-1 mRNA level. Proestrous and estrous prolactin mRNA levels were significantly higher than the metestrous and diestrous levels, whereas Pit-1 mRNA levels of the estrous and metestrous stages were about two- to threefold higher than those of the proestrous and diestrous stages. Proestrous Pit-1 mRNA levels increased gradually from 10.00 h to 20.00 h, while prolactin mRNA levels slightly decreased until 14.00 h but increased later until 20.00 h. During the rat estrous cycle, especially in the afternoon of the proestrous day, changes of prolactin mRNA levels seem to follow a prior increase of Pit-1 mRNA. Therefore, Pit-1 may be partly involved in the regulation of prolactin gene expression according to the rat estrous cycle. Estradiol administration to ovariectomized rats significantly increased both the mRNA levels of prolactin and Pit-1, which suggests that the gene expression of Pit-1 is regulated by estrogen through indirect extracellular pathways.

Expression of a cDNA for chloroplast ribosomal protein S16 of potato (Solanum tuberosum L.)

A cDNA encoding the potato (Solanum tuberosum L.) chloroplast ribosomal protein S16 (cp rps16) was isolated and characterized. The deduced amino acid sequence of the chloroplast rps16 coding sequence from potato shows 33% homology to the E.coli ribosomal protein S16 and 95% homology to the tobacco chloroplast ribosomal protein S16. The 13 amino acids encoded by exon-1 are highly conserved (100% identity) among higher plants. Two sizes of rps16 transcripts have been identified from northern blot analysis. The 1.5 kb transcript contains the 855 bp intron and represents an unprocessed RNA molecule, whereas the 0.7 kb transcript represents the mature form. The expression of rps16 is developmentally regulated, with transcript levels decreasing during tuber development and increasing during shoot development. The potato cp rps16 gene appears to be constitutively expressed in unswollen stolons and axillary buds, and its expression is enhanced by light.

The change of visual acuity and visual field by diminished illumination in eyes with multifocal intraocular lens

To investigate the effect of illumination on visual acuity and visual field in eyes with multifocal intraocular lens (IOL), the near and far visual acuity of the eyes with multifocal implants were compared to those of the eyes with monofocal implants in the diminished illumination, and the visual fields of two groups were also compared by the different target size and intensity. The near and far visual acuity of the eyes with multifocal implants were significantly decreased as compared to those of the eyes with monofocal implants under diminished illumination, and the visual field of the multifocal implanted eyes also significantly decreased as compared to that of the monofocal implanted eyes by the reduction of spot size and intensity. From the above results, it is assumed that the bifocal separation of incident light to two simultaneous focal points in the multifocal implants causes more decreased visual acuity and narrower visual field in the diminished illumination as compared to that of the eyes with monofocal implants.

Transcription of Xenopus selenocysteine tRNA Ser (formerly designated opal suppressor phosphoserine tRNA) gene is directed by multiple 5'-extragenic regulatory elements

A tRNA gene whose product is aminoacylated with serine and the serine moiety is then phosphorylated to form phosphoseryl-tRNA (see Hatfield, D. (1985) Trends Biochem. Sci. 10, 201-204 for review) has now been shown to form selenocysteyl-tRNA; hence the corresponding gene is designated as selenocysteine tRNA Ser (B. J. Lee, P. J. Worland, J. N. Davis, T. C. Stadtman, and D. Hatfield (1989) J. Biol. Chem. 264, in press). In the present study, we show that the expression of this unique tRNA gene is governed by at least three upstream regulatory elements. In initial studies, the relative efficiencies of transcription of the human, rabbit, chicken, and Xenopus selenocysteine tRNA genes were compared in vivo in Xenopus oocytes and in vitro in HeLa cell extracts. The Xenopus gene was severalfold more actively expressed, both in vivo and in vitro, than the human and rabbit genes, whereas the chicken gene was poorly expressed. Exchange of the 5'-flanking regions of the Xenopus and chicken genes, which have identical gene sequences, reversed their levels of transcription, demonstrating that a regulatory site or sites exist upstream of these genes. Deletion-substitution mutants in the Xenopus gene and its 5'-flanking sequence show in in vitro assays that 1) the level of transcription is reduced substantially when a GC-rich stretch that is immediately upstream of a TATA box in the -30 region is removed; 2) the level of transcription is virtually abolished when the TATA box is removed; and 3) deletions up to and further upstream of the GC-rich region do not affect the level of transcription. The same deletions, when used in in vivo assays, demonstrate a step-down in expression with the deletion removing the GC-rich region, a further step-down in expression with the deletion removing the TATA box, but the most pronounced reduction in expression was observed with a deletion removing an AT-rich region between nucleotides -62 and -76. Thus, a regulatory site was identified in vivo which was not detected in vitro, and transcription of the selenocysteine tRNA Ser gene is determined by multiple upstream regulatory elements.

The impedance of curved artery models

The impedance (pressure drop/flow rate) of four curved artery models has been determined experimentally for steady and periodic flows simulating conditions in the aortic arch. Steady flow results indicate that very short entry lengths are required for flow development in curved artery models, and impedance is elevated above straight tube values by a factor of 3-4 for mean flow conditions in the aortic arch. Results for periodic flow with a nonzero mean show a significant elevation of mean flow impedance relative to values for steady flow at the mean flow rate--a factor of 2-3 for aortic arch flow conditions. The impedance of the first harmonic of periodic flows follows straight tube theory at high values of the unsteadiness parameter in agreement with available theory for curved tubes. The implications of the impedance measurements for wall shear stress in the aortic arch are discussed.