Biomedical subjects

K Y Lin

Publications and source records attributed to K Y Lin.

At least 19 recordsLinked to original sources

PubMed1999

A cytosine analog that confers enhanced potency to antisense oligonucleotides.

Antisense technology is based on the ability to design potent, sequence-specific inhibitors. The G-clamp heterocycle modification, a cytosine analog that clamps on to guanine by forming an additional hydrogen bond, was rationally designed to enhance oligonucleotide/RNA hybrid affinity. A single, context-dependent substitution of a G-clamp heterocycle into a 15-mer phosphorothioate oligodeoxynucleotide (S-ON) targeting the cyclin-dependent kinase inhibitor, p27(kip1), enhanced antisense activity as compared with a previously optimized C5-propynyl-modified p27(kip1) S-ON and functionally replaced 11 C5-propynyl modifications. Dose-dependent, sequence-specific antisense inhibition was observed at nanomolar concentrations of the G-clamp S-ONs. A single nucleotide mismatch between the G-clamp S-ON and the p27(kip1) mRNA reduced the potency of the antisense ON by five-fold. A 2-base-mismatch S-ON eliminated antisense activity, confirming the sequence specificity of G-clamp-modified S-ONs. The G-clamp-substituted p27(kip1) S-ON activated RNase H-mediated cleavage and demonstrated increased in vitro binding affinity for its RNA target compared with conventional 15-mer S-ONs. Furthermore, incorporation of a single G-clamp modification into a previously optimized 20-mer phosphorothioate antisense S-ON targeting c-raf increased the potency of the S-ON 25-fold. The G-clamp heterocycle is a potent, mismatch-sensitive, automated synthesizer-compatible antisense S-ON modification that will have important applications in the elucidation of gene function, the validation of gene targets, and the development of more potent antisense-based pharmaceuticals.

Animals↗

PubMed1999

Cellular penetration and antisense activity by a phenoxazine-substituted heptanucleotide.

One of the major barriers to the development of antisense therapeutics has been their poor bioavailability. Numerous oligonucleotide modifications have been synthesized and evaluated for enhanced cellular permeation with limited success. Phenoxazine, a tricyclic 2' deoxycytidine analog, was designed to improve stacking interactions between heterocycles of oligonucleotide/RNA hybrids and to enhance cellular uptake. However, the bioactivity and cellular permeation properties of phenoxazine-modified oligonucleotides were unknown. Incorporation of four phenoxazine bases into a previously optimized C-5 propyne pyrimidine modified 7-mer phosphorothioate oligonucleotide targeting SV40 large T antigen enhanced in vitro binding affinity for its RNA target and redirected RNAse H-mediated cleavage as compared with the 7-mer C-5 propynyl phosphorothioate oligonucleotide (S-ON). The phenoxazine/C-5 propynyl U 7-mer S-ON showed dose-dependent, sequence-specific, and target-selective antisense activity following microinjection into cells. Incubation of the phenoxazine/C-5 propynyl U S-ON with a variety of tissue culture cells, in the absence of any cationic lipid, revealed unaided cellular penetration, nuclear accumulation, and subsequent antisense activity. The unique permeation properties and gene-specific antisense activity of the 7-mer phenoxazine/C-5 propynyl U S-ON paves the way for developing potent, cost-effective, self-permeable antisense therapeutics.

Animals↗

PubMed1999

Wound complications of abdominoplasty in obese patients.

The records of 90 patients who underwent an abdominoplasty at the University of Virginia Health Sciences Center were analyzed to determine the effect of obesity on the incidence of complications after this surgery. The study patients were divided into three groups-obese, borderline, and nonobese-based on the degree to which their preoperative weights varied from their ideal body weight. A history of previous bariatric surgery was also analyzed to determine what impact that might have on subsequent abdominoplasty. Results showed that 80% of obese patients had complications compared with the borderline and nonobese patients, who had complication rates of 33% and 32.5% respectively (p = 0.001). Previous gastric bypass surgery had no significant effect on the incidence of postabdominoplasty complications. Based on these findings the authors conclude that obesity at the time of abdominoplasty has a profound influence on the wound complication rate following surgery, regardless of any previous weight reduction surgery.

Adult↗

PubMed1999

Long-term outcome analysis of two treatment methods for cleft palate: combined levator retropositioning and pharyngeal flap versus double-opposing Z-plasty.

OBJECTIVE: Two surgical techniques for repair of a cleft palate include levator retropositioning in combination with a pharyngeal flap and the Furlow double-opposing Z-plasty. This study compared morbidity and speech results from the use of these two methods in an effort to determine which was the superior technique. DESIGN: Patient records from 1986 to 1996 were retrospectively reviewed, and 10 patients with a cleft palate who underwent repair with a levator retropositioning and pharyngeal flap were compared to 14 patients who underwent a double-opposing Z-plasty repair. Postoperative complications including fistula formation, obstructive sleep apnea, and residual velopharyngeal insufficiency were recorded. Speech was assessed perceptually and through the use of nasometry. RESULTS: Both surgical techniques resulted in good speech in the majority of patients. Only two patients in the study, both in the Z-plasty group, had severe postoperative hypernasality. Two patients in the levator retropositioning and pharyngeal flap group developed severe postoperative obstructive sleep apnea, requiring additional surgery. CONCLUSION: The levator retropositioning and pharyngeal flap technique was successful in achieving good speech results, but it also caused more serious postoperative complications when compared to the double-opposing Z-plasty technique.

Cleft Palate↗

PubMed1998

Antigen-specific immunotherapy for murine lung metastatic tumors expressing human papillomavirus type 16 E7 oncoprotein.

An important goal of cancer immunotherapy is to prevent and treat tumor metastasis. We have previously reported a recombinant vaccinia-based vaccine (Sig/E7/LAMP-1) that demonstrated significant anti-tumor effect in a subcutaneous tumor challenge model. In this study, we investigated the potency of the Sig/E7/ LAMP-1 vaccine in preventing and treating metastatic tumors. A tumor metastasis model was generated by injecting human papillomavirus type 16 (HPV-16) E6/E7 expressing tumor cells, designated TC-1, into the tail vein of syngeneic C57BL/6 mice. All the naive mice injected with 1 x 10(6) TC-1 cells developed tumors confined exclusively to the lungs within 1 month. For in vivo tumor prevention experiments, mice were vaccinated with Sig/E7/ LAMP-1 followed by tumor challenge. While tumor growth was observed in all of the mice (10/10) in the control groups, 8 of 10 vaccinated mice (80%) remained tumor-free 2 months post-tumor challenge. For in vivo treatment experiments, mice were first inoculated with TC-1 cells and then vaccinated with Sig/E7/ LAMP-1. Treatment with Sig/E7/LAMP-1 was effective in eliminating preexisting tumor cells in 4 of 5 vaccinated mice. Most importantly, treatment with Sig/E7/LAMP-1 resulted in regression of fully established lung tumors in 10% (5/10) of vaccinated mice. Our data suggest that the Sig/E7/LAMP-1 vaccine is effective in controlling the hematogenous spread of TC-1 tumor cells. In addition, the TC-1 lung metastasis model can be used to test the efficacy of various E6/E7-specific vaccines and immunotherapeutic strategies.

Animals↗

PubMed1998

Correction of posterior sagittal craniosynostosis.

Craniosynostosis involving the posterior sagittal suture results in a characteristic skull deformity known as bathrocephaly. Surgical correction of this deformity using the reverse pi procedure has yielded inconsistent results. We present a new method for expanding the transverse posterior skull while simultaneously reducing the longitudinal dimension. An absorbable microplate-reinforced bone strut is used as a framework on which the remainder of the skull is reconfigured; its stability prevents relapse. The posterior skull squeeze is produced using absorbable mesh plates. Use of rigid fixation is limited to absorbable hardware in the growing craniofacial skeleton.

Biocompatible Materials↗

PubMed1998

Successful excision of a large immature teratoma involving the cranial base: report of a case with long-term follow-up.

OBJECTIVE AND IMPORTANCE: Massive congenital intracranial teratomas with extracranial extension are rare. The prognosis in these cases has been poor, with stillbirth or immediate postpartum death as the usual outcome. With recent advances in fetal monitoring, neonatal care, and surgical techniques used for the management of complex tumors of the cranial base, some of these lesions may now be amenable to radical surgical resection and then immediate craniofacial reconstruction. CLINICAL PRESENTATION: A neonate with a large congenital immature teratoma involving the entire left side of the cranium and face was evaluated at our institution 1 day after birth. INTERVENTION: Total resection of the mass and then immediate reconstruction of the deformed orbit, maxilla, and mandible were performed at 9 days of age. Additional operations on the midface and mandible to allow for a functional bite were subsequently required as the child developed during the next 2 years. Four years after resection, the patient exhibited a reasonable cosmetic result and only mild developmental delay. CONCLUSION: We conclude that acceptable functional and cosmetic outcomes can be achieved by early intervention, consisting of radical resection and immediate craniofacial reconstruction, in some neonates with massive congenital craniofacial teratomas.

Facial Neoplasms↗

PubMed1998

Use of preoperative computed tomography-angiography in cranial remodeling: technical note.

UNLABELLED: OBJECTIVE/IMPORTANCE: One of the most severe complications of craniosynostosis repair is dural sinus laceration. Massive hemorrhage and air embolism are potentially life-threatening sequelae that can result from such an event. The aberrant anatomy of patients with craniosynostosis only accentuates this risk, because separation of the calvaria from the underlying dura is often performed without direct visualization of the sinuses. METHODS: Three-dimensional computed tomography was combined with computed tomographic angiography in the preoperative assessment of patients with craniofacial abnormalities. RESULTS: A clear understanding of the dural sinus anatomy in relation to the overlying bony landmarks became available to the operating surgeon. Six patients underwent this procedure, with excellent visualization of the bony and sinus anatomy achieved in all cases. CONCLUSION: It is thought, that the benefit of combining these procedures has been significant by allowing the visualization of the dural sinus anatomy and overlying bony landmarks. This procedure conveys minimal concomitant morbidity or expense to the patient, yet offers valuable insight toward operative planning and complication avoidance.

Cerebral Angiography↗

PubMed1998

Effect of group A streptococcal cysteine protease on invasion of epithelial cells.

Cysteine protease of group A streptococci (GAS) is considered an important virulence factor. However, its role in invasiveness of GAS has not been investigated. We demonstrated in this study that two strains of protease-producing GAS had the ability to invade A-549 human respiratory epithelial cells. Isogenic protease mutants were constructed by using integrational plasmids to disrupt the speB gene and confirmed by Southern hybridization and Western immunoblot analyses. No extracellular protease activity was produced by the mutants. The mutants had growth rates similar to those of the wild-type strains and produced normal levels of other extracellular proteins. When invading A-549 cells, the mutants had a two- to threefold decrease in activity compared to that of the wild-type strains. The invasion activity increased when the A-549 cells were incubated with purified cysteine protease and the mutant. However, blockage of the cysteine protease with a specific cysteine protease inhibitor, E-64, decreased the invasion activity of GAS. Intracellular growth of GAS was not found in A-549 cells. The presence or absence of protease activity did not affect the adhesive ability of GAS. These results suggested that streptococcal cysteine protease can enhance the invasion ability of GAS in human respiratory epithelial cells.

Bacterial Adhesion↗

PubMed1998

Role of streptococcal pyrogenic exotoxin B in the mouse model of group A streptococcal infection.

Streptococcal pyrogenic exotoxin B (SPE B) is a cysteine protease produced by Streptococcus pyogenes. In this study, the differences in virulence between protease-positive clinical isolates and their protease-negative mutants were examined in a mouse model. Isogenic protease-negative mutants were constructed by homologous recombination, using integrational plasmids to disrupt the speB gene. These mutants caused less mortality and tissue damage than protease-positive strains when inoculated into BALB/c mice via air pouch, suggesting that SPE B cysteine protease plays an important role in the pathogenesis of S. pyogenes infection. Reconstitution of SPE B in the air pouches increased the mortality of mice receiving the speB mutant strain. Infiltrated cell numbers in the exudates from the air pouches of mice infected with SPE B-producing S. pyogenes were higher than those from mice infected with protease-negative mutants at 12 h. However, despite pretreatment with vinblastine to deplete neutrophils, injection of protease-positive bacteria still resulted in severe tissue injury, indicating that neutrophil infiltration may not be the major factor involved in SPE B-enhanced tissue damage. The role of SPE B was further confirmed by demonstrating that SPE B immunization of mice conferred protection from challenge with a lethal dose of protease-positive bacteria.

Animals↗

PubMed1997

Coinfection of HPV-11 and HPV-16 in a case of laryngeal squamous papillomas with severe dysplasia.

Human papillomavirus (HPV) types 6 and 11 have been associated with benign laryngeal papilloma, while HPV-16 is occasionally associated with laryngeal carcinoma. In this study, a case of laryngeal squamous papillomas with severe dysplasia was evaluated for the presence of HPV infection. The biopsy specimens were taken from a 58-year-old female patient at two different time points 3 months apart. Architecturally, the tumor showed papillary configuration reminiscent of squamous papilloma. Cytologically, the lesion showed morphologic features characteristic of severe squamous epithelial dysplasia. HPV infection was determined by DNA in situ hybridization using type-specific HPV-DNA probes. HPV-11 probes demonstrated homogeneous nuclear staining, suggesting productive viral replication. In contrast, HPV-16 probe produced a speckled pattern, suggesting HPV-16 DNA integration. Normal laryngeal epithelium did not yield specific hybridization. The presence of HPV-11 and HPV-16 was confirmed by PCR using HPV type-specific primers. Immunocytochemical staining was performed to detect Ki-67, a proliferation marker, and p53. Ki-67 expression was demonstrated throughout the whole thickness of epithelium. Staining for p53 was negative. This study suggests that multiple HPV infections can occur in the same lesion and that HPV-16 infection and its DNA integration may contribute to the occurrence of severe dysplasia in the lesion described.

Cell Nucleus↗

PubMed1997

In vitro synergism between cefotaxime and minocycline against Vibrio vulnificus.

We conducted time-kill studies to evaluate the inhibitory activities of either cefotaxime or minocycline alone and the two drugs in combination against a clinical strain of Vibrio vulnificus. The MICs of cefotaxime and minocycline were 0.03 and 0.06 microg/ml, respectively. When approximately 5 x 10(5) CFU of V. vulnificus per ml was incubated with cefotaxime at 0.03 or 0.05 microg/ml, the bacterial growth was inhibited during the initial 2 and 8 h, respectively. Thereafter, V. vulnificus regrew and the level of growth reached that of the control. Within the dose range of less than five times the MIC, the duration of the inhibitory effect of cefotaxime was proportional to its concentration. When minocycline at 0.015, 0.03, 0.045, and 0.06 microg/ml was used to evaluate the inhibitory effect, a similar trend was observed. Either antibiotic at a concentration of five times the MIC or greater prevented the regrowth of V. vulnificus for at least 48 h. When cefotaxime at 0.05 microg/ml and minocycline at 0.045 microg/ml were combined in the same culture, the inhibitory effect against V. vulnificus persisted for more than 48 h, with no regrowth noted. The use of a combination of these two antibiotics resulted in the reduction of growth by 6 orders of magnitude compared to the use of either of the two antibiotics alone, and the number of surviving organisms in the presence of the antibiotics combined was approximately 3 orders of magnitude less than that in the starting inoculum. We conclude that cefotaxime and minocycline acted synergistically in inhibiting V. vulnificus in vitro.

Anti-Bacterial Agents↗

PubMed1997

High incidence of erythromycin-resistant streptococci in Taiwan.

The activities of nine antimicrobial agents against 247 isolates of group B, C, F, and G streptococci and viridans group streptococci were studied by the broth microdilution method. Erythromycin resistance was found in 29.7, 41.7, 81.8, 23.5, and 53.3% of the strains of group B, C, F, and G streptococci and viridans group streptococci tested, respectively. Macrolides are not considered an optimal alternative to penicillin in the treatment of streptococcal infections, at least empirically, in Taiwan.

Anti-Bacterial Agents↗

PubMed1997

Elevated levels of transforming growth factors beta 2 and beta 3 in lambdoid sutures from children with persistent plagiocephaly.

OBJECTIVE: To analyze the pertinent history and physical findings specific to the subset of patients with a progressive posterior skull deformity, requiring surgery to correct their deformity. PATIENTS: Since the Academy of Pediatrics issued its recommendation on supine positioning of infants to prevent sudden infant death syndrome (SIDS) in 1992, 73 children have presented to the University of Virginia Craniofacial Anomalies Clinic with posterior-skull deformities. The majority were successfully managed with conservative therapy, but in six patients, the deformity was severe and persistent, requiring surgical correction. All six children were older (7.5-12 mo), presenting with more severe morphologic appearances and a higher incidence of associated neurodevelopmental delay. Three had family backgrounds of isolated craniosynostosis. METHODS: Characteristics of these patients were examined to determine why they may have differed from those that responded to conservative management. Immunohistochemical staining of their lambdoid sutures was performed. RESULTS: Significantly increased staining for TGF-beta 2 and TGF-beta 3, potent stimulators of bone cell growth and differentiation, was seen in all 'affected' sutures from the flattened side of the skull, compared to unaffected sutures from the protruding side of the skull-a pattern similar to that seen during normal bony obliteration of calvarial sutures. CONCLUSION: The majority of patients with posterior plagiocephaly associated with positioning responded to conservative management, while a small subset of patients with persistent posterior skull deformation required surgical intervention. A genetic basis for the latter patients' persistent plagiocephaly, rather than positioning, cannot be ruled out. Genetics, prolonged external pressure against the sutures, or a combination of these factors may lead to permanently raised levels of growth factors in 'affected' sutures.

Cell Differentiation↗

PubMed1996

Abnormal head MRI in a neurologically normal boy with hypomelanosis of Ito.

We report on an 8.5-year-old boy with hypomelanosis of Ito (HI) who has an abnormal MRI of the brain but is neurologically normal. There have been many reports of abnormal brain imaging studies in patients with HI, but all reported patients have had abnormal neurologic findings or symptoms. Our patient has had serial, stable head MRI white matter changes and has remained neurologically normal without any neurologic sequelae.

Brain↗

PubMed1996

A serum-resistant cytofectin for cellular delivery of antisense oligodeoxynucleotides and plasmid DNA.

Development of antisense technology has focused in part on creating improved methods for delivering oligodeoxynucleotides (ODNs) to cells. In this report, we describe a cationic lipid that, when formulated with the fusogenic lipid dioleoylphosphatidyliethanolamine, greatly improves the cellular uptake properties of antisense ODNs, as well as plasmid DNA. This lipid formulation, termed GS 2888 cytofectin, (i) efficiently transfects ODNs and plasmids into many cell types in the presence or absence of 10% serum in the medium, (ii) uses a 4- to 10-fold lower concentration of the agent as compared to the commercially available Lipofectin liposome, and (iii) is > or = 20-fold more effective at eliciting antisense effects in the presence of serum when compared to Lipofectin. Here we show antisense effects using GS 2888 cytofectin together with C-5 propynyl pyrimidine phosphorothioate ODNs in which we achieve inhibition of gene expression using low nanomolar concentrations of ODN. This agent expands the utility of antisense ODNs for their use in understanding gene function and offers the potential for its use in DNA delivery applications in vivo.

Base Sequence↗

PubMed1996

Chromosome 22q11.2 deletion in a boy with Opitz (G/BBB) syndrome.

This report is on a 14-month-old boy with manifestations of Opitz (G/BBB) syndrome in whom a 22q11.2 deletion was found. Deletion analysis was requested because of some findings in this patient reminiscent of velocardiofacial (VCF) syndrome. The extent of aspiration and of respiratory symptoms in this child is not usually seen in VCF syndrome. Opitz syndrome maps to at least two loci, one on Xp, the other on 22q11.2.

Adult↗

PubMed1996

Treatment of established tumors with a novel vaccine that enhances major histocompatibility class II presentation of tumor antigen.

Presentation of antigenic peptides by MHC class II molecules to CD4+ T cells is critical to the generation of antitumor immunity. In an attempt to enhance MHC class II antigen processing, we linked the sorting signals of the lysosome-associated membrane protein (LAMP-1) to the cytoplasmic/nuclear human papilloma virus (HPV-16) E7 antigen, creating a chimera (Sig/E7/LAMP-1). Previously, we found that expression of this chimera in vitro and in vivo with a recombinant vaccinia vector targeted E7 to endosomal and lysosomal compartments and enhanced MHC class II presentation to CD4+ T cells compared to vaccinia expressing wild-type E7. In the current study, we tested these recombinant vaccinia for in vivo protection against an E7+ tumor, TC-1, which was derived from primary epithelial cells of C57BL/6 mice cotransformed with HPV-16 E6 and E7 and c-Ha-ras oncogenes. All mice vaccinated with 1 x 10(7) plaque-forming units of wild-type E7-vaccinia showed progressive tumor growth when challenged with a tumorigenic dose of TC-1 tumor cells; in contrast, 80% of mice vaccinated with the chimeric Sig/E7/LAMP1 vaccinia remained tumor free 3 months after tumor injection. Furthermore, treatment with the Sig/E7/LAMP-1 vaccinia vaccine cured mice with small established TC-1 tumors, whereas the wild-type E7-vaccinia showed no effect on this established tumor burden. These findings point out the therapeutic limitations of recombinant vaccinia expressing unmodified tumor antigens. Further, they demonstrate that modifications that reroute a cytosolic tumor antigen to the endosomal/lysosomal compartment can profoundly improve the in vivo therapeutic potency of recombinant vaccines.

Animals↗