Multifunction endolaser probe.
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Equipment Design↗
Biomedical subjects
S Chang
Publications and source records attributed to S Chang.
Two gap junction genes, connexin 31.1 and 30.3, are closely linked on mouse chromosome 4 and preferentially expressed in skin.
Two new gap junction genes isolated from the mouse genome code for connexin homologues of 271 and 266 amino acids, designated here Cx31.1 and Cx30.3, respectively. The two open reading frames, oriented in the same direction, are only 3.4 kb apart on mouse chromosome 4. Within the connexin family, these two proteins are most closely related to one another (70% amino acid sequence identity) and to Cx31 (65 and 68% identity, respectively). Comparison of the Cx31.1 mouse gene with a Cx31.1 cDNA showed a similar genomic organization to that found with other members of the connexin gene family, i.e. the coding and 3'-untranslated regions are contained within a single exon, which is preceded by an intron, less than 25 bases upstream of the ATG start codon. Northern blot hybridization revealed highly tissue-specific coexpression of the 1.6-kb Cx31.1 mRNA and two Cx30.3 transcripts of 1.9- and 3.2-kb size, predominantly in skin and two related mouse keratinocyte cell lines. Minor levels of Cx31.1 mRNA were detected in testis. Microinjection of Cx30.3, but not Cx31.1 cRNA, into Xenopus oocyte pairs induced formation of functional gap junction channels with unique voltage-gated parameters compared to other connexins expressed similarly.
Amino Acid Sequence↗
Long-term results of vitrectomy and perfluorocarbon gas for the treatment of severe proliferative vitreoretinopathy.
The results of 87 patients who underwent vitrectomy, scleral buckling, and injection of perfluorocarbon gas in one eye each for proliferative vitreoretinopathy of grade C3 (marked, involving three quadrants) or worse were studied. The retinas of 60 of the 87 patients (69%) were attached posterior to the scleral buckle one month after disappearance of the gas, with the initial reattachment rate being inversely proportional to the severity of proliferative vitreoretinopathy. Follow-up data ranging from six to 106 months were available on 54 eyes with attached retinas. Final visual acuity in those patients ranged from light perception to 20/40 and was not related to severity of proliferative vitreoretinopathy or duration of reattachment. Thirty-eight of the 54 patients (70%) had a visual acuity of 20/400 or better. Twenty-nine of the 37 patients (78%) with retinas attached 24 months or longer had the same or better visual acuity than at six months postoperatively. Macular pucker was observed in 16 of the 54 eyes (30%) and was the most frequently seen long-term retinal complication affecting visual acuity.
Adolescent↗
Tractional elevations of the retina in patients with diabetes.
Tractional retinoschisis and tractional retinal detachment are both complications of proliferative diabetic retinopathy. The two conditions are frequently confused because they are similar in diagnostic features. We determined the respective incidence of tractional retinoschisis and tractional retinal detachment in 200 eyes with tractional elevations of the retina in patients with diabetes. In 39 eyes, the diagnosis was unequivocally tractional retinoschisis because the retinal elevation maintained its concave contour despite the development of retinal holes. In 65 eyes, tractional retinal detachment was diagnosed with equal certainty, either because pigment lines were present or because the elevation, after a retinal hole developed, rapidly became convex and extended to the ora serrata. The remaining 96 eyes, in which retinal holes or pigment lines were absent, were classified by other features that had been tested for significance in the already diagnosed eyes. On that basis, the diagnosis was retinoschisis in 46 eyes and retinal detachment in 50 eyes.
Diabetes Mellitus, Type 1↗
Genetic and molecular analysis of DNA43 and DNA52: two new cell-cycle genes in Saccharomyces cerevisiae.
Two Saccharomyces cerevisiae genes previously unknown to be required for DNA synthesis have been identified by screening a collection of temperature-sensitive mutants. The effects of mutations in DNA43 and DNA52 on the rate of S phase DNA synthesis were detected by monitoring DNA synthesis in synchronous populations that were obtained by isopycnic density centrifugation. dna43-1 and dna52-1 cells undergo cell-cycle arrest at the restrictive temperature (37 degrees C), exhibiting a large-budded terminal phenotype; the nuclei of arrested cells are located at the neck of the bud and have failed to undergo DNA replication. These phenotypes suggest that DNA43 and DNA52 are required for entry into or completion of S phase. DNA43 and DNA52 were cloned by their abilities to suppress the temperature-sensitive lethal phenotypes of dna43-1 and dna52-1 cells, respectively. DNA sequence analysis suggested that DNA43 and DNA52 encode proteins of 59.6 and 80.6 kDa, respectively. Both DNA43 and DNA52 are essential for viability and genetic mapping experiments indicate that they represent previously unidentified genes: DNA43 is located on chromosome IX, 32 cM distal from his5 and DNA52 is located on chromosome IV, 0.9 cM from cdc34.
Amino Acid Sequence↗
Production of the cytostatic agent aeroplysinin by the sponge Verongia aerophoba in in vitro culture.
1. The marine sponge Verongia aerophoba contains two bioactive secondary metabolites from tyrosine, (+)-aeroplysinin-1 [3',5'-dibromo-1',2'-dihydroxy-4'- methoxycyclohexa-3',5'-dien-1'-yl-methyl-cyanide; abbreviated AP] and dibromoverongia-quinol [3',5'-dibromo-1'-hydroxy- 4'-oxocyclohexa-2',5'-dien-1'-yl-acetamide; abbreviated DV], which display strong cytostatic activity. 2. The concentrations causing 50% inhibition of cell growth are 0.47 microM (AP) and 1.21 microM (DV), resp. 3. Depending on depth regions from which the sponges were collected, differences in occurrence of metabolites were observed. 4. AP and DV were found to be present in sponges collected at a depth of 5-10 m, whereas only DV could be detected in material from deeper regions (20-30 m). 5. AP is present only in the surface layers (both the outer and oscular region) of the sponge, while in the centre of the sponge only DV is detected. 6. Cubes from sponges, collected at a depth of 30 m, were cultivated in seawater in vitro and were found to have the capacity (i) to synthesize AP, and (ii) to release this bioactive material into the medium under defined conditions. Under optimal conditions (light and aeration) 100 g of sponge synthesize and release 13.02 mg of AP during a 10-day incubation period. 7. In the dark and without aeration this synthesis was prevented. 8. These data show that also under in vitro conditions sponges retain the capability of producing bioactive compounds and can be induced to produce even substances which they did not secrete in their natural environment.
Acetamides↗
Iris neovascularization in proliferative vitreoretinopathy.
PURPOSE: The purpose of this study is to report on the prevalence, incidence, and associated risk factors of iris neovascularization in nondiabetic patients undergoing vitrectomy for retinal detachment complicated by proliferative vitreoretinopathy (PVR). METHODS: The authors conducted a retrospective review of 141 consecutive non-diabetic patients undergoing vitrectomy for recurrent retinal detachment resulting from PVR. Univariate and multivariate analyses were performed on all patients to determine which preoperative, intraoperative, and postoperative factors were associated with the development of postoperative iris neovascularization. RESULTS: Twenty-seven of the 141 (19%) patients were noted with preoperative and/or postoperative iris neovascularization. Four of eight patients presenting with preoperative iris neovascularization had complete regression after successful reattachment of the retina. Results of analysis of the remaining 133 patients without iris neovascularization preoperatively showed residual retinal detachment as the most significant risk factor for postoperative iris neovascularization. In the absence of panretinal photocoagulation, none of the 27 patients developed neovascular glaucoma. CONCLUSIONS: The development of iris neovascularization preoperatively or post-operatively is not necessarily a predictor of a poor anatomic and/or visual result. Iris neovascularization in PVR rarely if ever progresses to neovascular glaucoma. Panretinal photocoagulation is not indicated in these patients. Retinal reattachment is the most important factor in the prevention and/or resolution of postoperative iris neovascularization. The development of iris neovascularization in PVR appears to be a multifactorial process requiring multiple variables acting in concert.
Adolescent↗
CTL cross reactivity between HIV strains.
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Antigenic Variation↗
Perfluorocarbon liquids in vitreoretinal surgery.
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Eye Injuries, Penetrating↗
Experimental studies of the combined use of vitreous substitutes of high and low specific gravity.
The combined use of high and low specific gravity liquid vitreous substitutes has been studied in the rabbit. Eyes having undergone 1) vitreous replacement with silicone liquid combined with a perfluoropolyether liquid of high viscosity; 2) replacement with the perfluoropolyether or silicone alone; or 3) vitrectomy only (control) were compared under conditions of a cell-injection model of traction retinal detachment. Some of the control eyes (3 out of 9) and silicone-filled eyes (2 out of 10) developed total retinal detachments involving all quadrants; in the silicone-filled eyes the detachments extended behind the silicone globule. Conversely, in the eyes undergoing replacement with the two liquids or with the perfluoropolyether liquid alone, retinal detachments never extended to the inferior quadrants underlying the perfluoropolyether globule. In other experiments, the tendency toward emulsification of a low-viscosity perfluorocarbon liquid was reduced when it was used in combination with silicone liquid, in comparison to when this liquid was used alone.
Animals↗
Treatment of dislocated crystalline lens and retinal detachment with perfluorocarbon liquids.
Removal of a crystalline lens dislocated into the vitreous cavity can be hazardous, particularly in the presence of a retinal detachment. Hard pieces of nuclear material may be difficult to extract and may repeatedly fall onto the retina when emulsification is attempted in the vitreous cavity. Cases involving four eyes with dislocated crystalline lens and rhegmatogenous retinal detachment, into which liquid perfluorocarbon was injected after vitrectomy to float the dislocated lens material off the retina and reattach the retina, are reported. The dislocated lens was removed while floating on the perfluorocarbon liquid, which also provided a cushion that prevented dropped fragments of lens from traumatizing the retina. In all four cases, surgery was not associated with complications and resulted in improvement in visual acuity and retinal reattachment.
Adult↗
Evaluation of the blood-aqueous barrier after vitreous replacement with perfluoropropane gas and liquid silicone.
Fluorophotometric measurements of blood-aqueous barrier permeability after intravitreal injection of perfluoropropane gas in rabbit eyes revealed fluorescein leakage immediately after injection; 3 days later, recovery of barrier integrity had begun to occur and 7 days and 14 days after gas injection, when the gas bubble was still in the eye, anterior chamber fluorescein concentrations were normal. Similarly, in eyes undergoing vitrectomy and injection of silicone liquid or vitrectomy only, anterior chamber fluorescein levels were elevated 3 days and 1 week after surgery. Nevertheless, normal barrier integrity was reestablished in both the silicone-filled eyes and the vitrectomized eyes after 1 week. Since there was no difference between the group injected with silicone and the group that underwent vitrectomy only with respect to anterior chamber fluorescein concentration at any of the times studied, it is concluded that the temporary disruption of the blood-aqueous barrier is associated with the surgical procedure rather than the presence of silicone liquid in the vitreous cavity.
Animals↗
A statistical model based fundamental frequency synthesizer for Mandarin speech.
A novel method based on a statistical model for the fundamental-frequency (F0) synthesis in Mandarin text-to-speech is proposed. Specifically, a statistical model is employed to determine the relationship between F0 contour patterns of syllables and linguistic features representing the context. Parameters of the model were empirically estimated from a large training set of sentential utterances. Phonologic rules are then automatically deduced through the training process and implicitly memorized in the model. In the synthesis process, contextual features are extracted from a given input text, and the best estimates of F0 contour patterns of syllable are then found by a Viterbi algorithm using the well-trained model. This method can be regarded as employing a stochastic grammar to reduce the number of candidates of F0 contour pattern at each decision point of synthesis. Although linguistic features on various levels of input text can be incorporated into the model, only some relevant contextual features extracted from neighboring syllables were used in this study. Performance of this method was examined by simulation using a database composed of nine repetitions of 112 declarative sentential utterances of the same text, all spoken by a single speaker. By closely examining the well-trained model, some evidence was found to show that the declination effect as well as several sandhi rules are implicitly contained in the model. Experimental results show that 77.56% of synthesized F0 contours coincide with the VQ-quantized counterpart of the original natural speech. Naturalness of the synthesized speech was confirmed by an informal listening test.
China↗
Pathfinding by cranial nerve VII (facial) motorneurons in the chick hindbrain.
Cranial nerve VII (facial) motorneurons begin extending axons through rhombomeres 4 and 5 (R4 and R5) in the chick hindbrain on the second day of incubation. Without crossing the midline, facial motorneuron axons extend laterally from a ventromedial cell body location. All facial motorneuron axons leave the hindbrain through a discrete exit site in R4. To examine the importance of the exit site in R4 on motorneuron pathfinding, we ablated R4 before motorneuron axonogenesis. We find that mechanisms intrinsic to R5 direct the initial lateral orientation of R5 motorneuron axons. Upon reaching a particular lateral position, all R5 motorneuron axons must turn. In normal embryos the axons all turn rostrally to reach the nerve exit in R4. In embryos with R4 ablated, sometimes the axons turn rostrally and sometimes they turn caudally. A model combining permissive fields and chemotropic cues is presented to account for our observations.
Animals↗
Posterior chamber IOL implantation in traumatic cataract with injured complications.
Twenty-five cases of posterior chamber IOL implantation in traumatic cataract with complications associated with primary injury were reported. The operating methods were described and the post-operative complications were discussed. Seventy-two percent of patients have the correct vision over 20/40. It is suggested that the posterior chamber IOL can be implanted in traumatic cataract with some injured complications.
Adolescent↗
The effects of lipid lowering on diabetic retinopathy.
The effect of lipid lowering on hard exudates was determined in six consecutive patients with insulin-dependent diabetes mellitus. Diet and hypolipidemic drug therapy including the use of pravastatin, a new inhibitor of 3-hydroxy-3-methylglutaryl coenzyme-A reductase, were used to treat patients for one year. The total cholesterol concentration decreased from a mean baseline value of 231 mg/dl to a treatment mean value of 165 mg/dl. The mean low-density lipoprotein cholesterol concentration decreased from 157 mg/dl to 93 mg/dl. Masked grading of fundus photographs indicated an improvement in hard exudates in all six patients and a decrease in microaneurysms in four patients. Visual acuity improved in one patient and did not change (one line or less change) in five patients. No remarkable side effects resulting from treatment were observed. Our pilot study suggests that aggressive therapy of diabetic patients with hyperlipidemia may have a beneficial effect on background retinopathy.
Adult↗
Efficient immortalization of luminal epithelial cells from human mammary gland by introduction of simian virus 40 large tumor antigen with a recombinant retrovirus.
When defined in terms of markers for normal cell lineages, most invasive breast cancer cells correspond to the phenotype of the common luminal epithelial cell found in the terminal ductal lobular units. Luminal epithelial cells cultured from milk, which have limited proliferative potential, have now been immortalized by introducing the gene encoding simian virus 40 large tumor (T) antigen. Infection with a recombinant retrovirus proved to be 50-100 times more efficient than calcium phosphate transfection, and of the 17 cell lines isolated, only 5 passed through a crisis period as characterized by cessation of growth. When characterized by immunohistochemical staining with monoclonal antibodies, 14 lines showed features of luminal epithelial cells and of these, 7 resembled the common luminal epithelial cell type in the profile of keratins expressed. These cells express keratins 7, 8, 18, and 19 homogeneously and do not express keratin 14 or vimentin; a polymorphic epithelial mucin produced in vivo by luminal cells is expressed heterogeneously and the pattern of fibronectin staining is punctate. Although the cell lines have a reduced requirement for added growth factors, they do not grow in agar or produce tumors in the nude mouse. When the v-Ha-ras oncogene was introduced into two of the cell lines by using a recombinant retrovirus, most of the selected clones senesced, but one entered crisis and emerged after 3 months as a tumorigenic cell line.
Animals↗
Molecular characterization of erythrocyte glycophorin C variants.
Human erythrocyte glycophorin C plays a functionally important role in maintaining erythrocyte shape and regulating membrane mechanical stability. Immunochemical and serologic studies have identified a number of glycophorin C variants that include the Yus, Gerbich, and Webb phenotypes. We report here the molecular characterization of these variants. Amplification of glycophorin C mRNA from the Yus phenotype, using two oligonucleotide primers that span the coding domain, generated a 338-bp fragment compared with a 395-bp fragment generated by amplification of normal glycophorin C mRNA. Sequencing of the mutant 338-bp fragment identified a 57-bp deletion that corresponds to exon 2 of the glycophorin C gene. Similar analysis showed deletion of 84-bp exon 3 in the Gerbich phenotype. In contrast to the generation of shorter than normal DNA fragments from mRNA amplification in the Yus and Gerbich phenotypes, amplification of mRNA from the Webb phenotype generated a normal-sized fragment. Sequencing of this DNA fragment showed an A----G substitution at nucleotide 23 of the coding sequence, resulting in the substitution of asparagine by serine. This modification accounts for the altered glycosylation of glycophorin C seen in this phenotype. These results have enabled us to characterize glycophorin C variants in three different phenotypes that involve deletions of exons 2 and 3 of the glycophorin C gene, as well as a point mutation in exon 1 that results in altered glycosylation of this protein.
Amino Acid Sequence↗