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Biomedical subjects

K K Li

Publications and source records attributed to K K Li.

At least 37 records · Page 2Linked to original sources
PubMed2000

Morbidly obese patients with severe obstructive sleep apnea: is airway reconstructive surgery a viable treatment option?

OBJECTIVE: To evaluate the outcomes of airway reconstructive surgery for the treatment of severe obstructive sleep apnea in the morbidly obese patient. METHODS: Retrospective review of consecutively treated patients. Variables examined include age, sex, body mass index (BMI), respiratory disturbance index (RDI), lowest oxygen saturation (LSAT), cephalometric data, and complications. RESULTS: Twenty-one patients (13 men) with a mean age of 42.6 +/- 7.9 years and mean BMI of 45 +/- 5.4 kg/m2 were identified. The mean RDI improved from 83 +/- 30.1 to 10.6 +/- 10.8 events per hour with an improved mean apnea index from 38.4 +/- 31.3 to 1.2 +/- 1.8 events per hour. The mean LSAT improved from 63.9 +/- 17.7% to 86 +/- 7.9%. The mean BMI at the 6-month postoperative polysomnographic recording was 43 +/- 4.3 kg/m2 (P < .001). Seventeen patients (81%) were successfully treated (RDI < 20 and with minimal desaturation < 90%). The mean follow-up was 21.8 +/- 15.4 months (range, 7-66 mo). Coexisting obesity-hypoventilation syndrome was related to treatment failure in two patients. One patient noted recurrence of daytime fatigue after significant weight gain 4 years after surgery and the polysomnographic recordings demonstrated the recurrence of obstructive sleep apnea. CONCLUSION: Airway reconstruction is an effective treatment for severe obstructive sleep apnea in the morbidly obese patient. Careful patient selection and identifying potential coexisting obesity-hypoventilation syndrome, as well as counseling on weight reduction and avoiding continual weight gain will improve treatment outcomes. Key Words: Obstructive sleep apnea, sleep-disordered breathing, obstructive sleep apnea surgery, obesity, maxillomandibular advancement.

Adolescent↗
PubMed2000

Maxillomandibular advancement for persistent obstructive sleep apnea after phase I surgery in patients without maxillomandibular deficiency.

OBJECTIVE: To assess the outcomes of maxillomandibular advancement (MMA) for the treatment of persistent obstructive sleep apnea syndrome (OSA) after phase I reconstruction in patients who do not have maxillomandibular deficiency. METHODS: From January 1997 to September 1998, 25 patients previously treated with phase I reconstruction (uvulopalatoplasty, genioglossus advancement, and/or hyoid suspension) who did not have maxillary and mandibular deficiencies underwent MMA for persistent OSA. Variables examined include age, sex, body mass index (BMI), respiratory disturbance index (RDI), lowest oxygen saturation (LSAT), and cephalometric data. In addition, a minimum of 6 months after surgery, questionnaires containing a 10-cm visual analogue scale (0 = no change, 10 = drastic change) were mailed to the patients. The questionnaire subjectively assessed the patient's perception of the facial appearance after surgery, whether there was pain or discomfort of the temporomandibular joint, the overall satisfaction with the treatment outcomes, and whether the patient would recommend the operation to other patients. RESULTS: Nineteen (76%) questionnaires were completed and returned by 15 men and 4 women. The mean age was 45.3 +/- 6.6 years and the mean BMI was 33.1 +/- 7.1 kg/m2. The mean RDI improved from 63.6 +/- 20.8 to 8.1 +/- 5.9 events per hour, and the mean LSAT improved from 73.3 +/- 13.2% to 88.1 +/- 4.1%. One patient was defined as an incomplete responder (RDI >20). One patient reported transient pain and discomfort of the temporomandibular joint. Although all of the patients felt that there were changes in their facial appearance after surgery, 18 of the 19 patients gave either a neutral or a favorable response to their facial esthetic results. All of these patients were satisfied with the overall outcomes and would recommend the treatment to others. CONCLUSION: MMA is a highly effective treatment for persistent OSA after phase I surgery in patients who otherwise do not have maxillomandibular deficiency. The patient satisfaction is extremely high. Furthermore, previous concerns of unfavorable postoperative facial esthetics and temporomandibular joint dysfunction do not appear to be significant.

Body Mass Index↗
PubMed2000

Obstructive sleep apnea syndrome: a comparison between Far-East Asian and white men.

OBJECTIVES: To investigate the possible differences between Far-East Asian men and white men in obstructive sleep apnea syndrome (OSAS). STUDY DESIGN: Prospective nonrandomized controlled study. METHODS: This study compared consecutive Far-East Asian men with OSAS (n = 50) with two selected groups of White men with OSAS (n = 50 in each group). One group of white men was controlled for age, respiratory disturbance index (RDI), and minimum oxygenation saturation (LSAT). Another group was controlled for age and body mass index (BMI). Cephalometric analysis was performed on all subjects. RESULTS: The majority of the Far-East Asian men were found to be nonobese (mean BMI, 26.7 +/- 3.8) but had severe OSAS (mean RDI, 55.1 +/- 35.1). When controlled for age, RDI, and LSAT, the white men were substantially more obese (mean BMI, 29.7 +/- 5.8, P = .0055). When controlled for age and BMI, the white men had less severe illness (RDI, 34.1 +/- 17.9, P = .0001). Although the posterior airway space and the distance from the mandibular plane to hyoid bone were less abnormal in the Far-East Asian men, the cranial base dimensions were significantly decreased. CONCLUSIONS: The majority of the Far-East Asian men in this study were found to be nonobese, despite the presence of severe OSAS. When compared with white men, Far-East Asian men were less obese but had greater severity of OSAS. There may be differences in obesity and craniofacial anatomy as risk factors in these two groups.

Adult↗
PubMed2000

An unreported risk in the use of home nasal continuous positive airway pressure and home nasal ventilation in children: mid-face hypoplasia.

We report the case of a 15-year-old boy with obstructive sleep apnea and obesity who was treated since the age of 5 with nasal continuous positive airway pressure. Due to the long-term use of a nasal mask, the child developed a mid-face hypoplasia. Chronic use of a nasal mask for home ventilation in children should always be associated with regular evaluations of maxillomandibular growth.

Adolescent↗
PubMed1999

Hepatocyte nuclear factor 3 relieves chromatin-mediated repression of the alpha-fetoprotein gene.

The alpha-fetoprotein gene (AFP) is tightly regulated at the tissue-specific level, with expression confined to endoderm-derived cells. We have reconstituted AFP transcription on chromatin-assembled DNA templates in vitro. Our studies show that chromatin assembly is essential for hepatic-specific expression of the AFP gene. While nucleosome-free AFP DNA is robustly transcribed in vitro by both cervical (HeLa) and hepatocellular (HepG2) carcinoma extracts, the general transcription factors and transactivators present in HeLa extract cannot relieve chromatin-mediated repression of AFP. In contrast, preincubation with either HepG2 extract or HeLa extract supplemented with recombinant hepatocyte nuclear factor 3 alpha (HNF3alpha), a hepatic-enriched factor expressed very early during liver development, is sufficient to confer transcriptional activation on a chromatin-repressed AFP template. Transient transfection studies illustrate that HNF3alpha can activate AFP expression in a non-liver cellular environment, confirming a pivotal role for HNF3alpha in establishing hepatic-specific gene expression. Restriction enzyme accessibility assays reveal that HNF3alpha promotes the assembly of an open chromatin structure at the AFP promoter. Combined, these functional and structural data suggest that chromatin assembly establishes a barrier to block inappropriate expression of AFP in non-hepatic tissues and that tissue-specific factors, such as HNF3alpha, are required to alleviate the chromatin-mediated repression.

Animals↗
PubMed1999

Retinal complications after cataract extraction in patients with high myopia.

OBJECTIVE: To assess risk factors and incidence of retinal complications after cataract extraction in patients with high myopia. DESIGN: Retrospective, noncomparative case series. PARTICIPANTS: One hundred eighteen patients with highly myopic eyes who had an axial length of 26 mm or more (mean axial length, 30.13 +/- 2.08 mm) and who underwent cataract surgery over a period of 6 years were studied. INTERVENTION: Patients underwent cataract extraction either by extracapsular cataract extraction (ECCE) or phacoemulsification. Prophylactic argon laser photocoagulation was performed in 13 eyes for retinal tears recognized before surgery and in 13 eyes after surgery; neodymium:YAG (Nd:YAG) laser capsulotomy was performed for patients with posterior capsule opacification (PCO) that affected the vision. MAIN OUTCOME MEASURES: Incidence of retinal detachment and PCO and percentage of prophylactic argon laser or of Nd:YAG laser treatments. RESULTS: Of the 118 eyes, 73 (61.9%) underwent ECCE and 45 (38.1%) underwent phacoemulsification. Posterior capsule opacification was the most common complication and was found in 30 eyes (25.4%). Thirteen patients (11%) received prophylactic laser treatment for retinal tears before cataract operation, and 13 more patients (11%) had postoperative retinal tears requiring laser treatments. None of these patients developed retinal detachment. Two patients (1.69%) developed retinal detachment within 6 months after their operations. There were no intraoperative complications, and postoperative Nd:YAG capsulotomy was not performed in these two patients. CONCLUSIONS: Active searching and prophylactic laser treatments for retinal tears developed before and after cataract extraction in patients with high myopia are recommended. This may lower the incidence of postoperative retinal detachment.

Adult↗
PubMed1999

Traumatic optic neuropathy: result in 45 consecutive surgically treated patients.

The management of traumatic optic neuropathy remains controversial. In this report, we present the results of 45 patients treated with extracranial optic nerve decompression after at least 12 to 24 hours of corticosteroid therapy without improvement. Vision improved in 32 patients after surgery (71%), and the mean percentage of improvement from preoperative visual deficit was 40.7% +/- 6.9% (median improvement 41.2%). Worsening of vision occurred in none of the patients as a result of the surgery, and no intraoperative or postoperative complications were encountered. We present a treatment protocol for traumatic optic neuropathy with the use of megadose corticosteroids and optic nerve decompression.

Adolescent↗
PubMed1999

Squamous cell metastasis from the tongue to the myocardium presenting as pericardial effusion.

Cardiac metastasis from head and neck cancer is rarely encountered. We present a base-of-tongue squamous cell carcinoma with metastasis to the heart that was diagnosed antemortem. Autopsy series indicate that tongue cancer may metastasize more frequently to the heart than from other head and neck sites. However, none of these studies was controlled. Most importantly, cardiac metastasis should be suspected in any patient with cancer in whom new cardiac symptoms develop. The diagnosis is best confirmed with two-dimensional echocardiography or cardiac MRI. A myocardial or endocardial biopsy specimen can be obtained with angiographic guidance. Despite the improvement in diagnostic capability, available treatments are only palliative. All patients eventually die of their metastatic disease.

Biopsy, Needle↗
PubMed1999

A comparison of Asian and white patients with obstructive sleep apnea syndrome.

OBJECTIVE: To evaluate the possible differences between Asian and white patients with obstructive sleep apnea syndrome. METHODS: A retrospective review of Asian and white patients during a 12-month period was conducted. Patients with respiratory disturbance index (RDI) > or = 15 based on polysomnography were included in the study. Variables examined include age, sex, body mass index (BMI), RDI, lowest oxygen saturation (LSAT), and cephalometric analysis data. RESULTS: Fifty-eight Asian patients (53 men) and 293 white patients (260 men) were studied. The Asians were younger (44.1 +/- 9.8 vs. 47.5 +/- 11.6 y, P = .02), and the mean BMI (kg/m2) was 26.6 +/- 3.7 in the Asians and 30.7 +/- 5.9 in the whites (P < .001). The mean RDI was similar (56.6 +/- 34.9 vs. 55.6 +/- 26.9, P = NS), but the mean LSAT was lower in the whites (77.7 +/- 9.9% vs. 70.0 +/- 15.6%, P < .001). Based on the cephalometric data, the Asians have maxillomandibular protrusion, narrower cranial base angle, larger posterior airway space, and more superiorly positioned hyoid bone compared with the whites. CONCLUSIONS: Although male gender was found to be an important risk factor for obstructive sleep apnea syndrome in both Asian and white patients, obesity may be a less significant risk factor in the Asians because the majority of our Asian patients were nonobese. There was also variability in the craniomandibular factors that contributed to obstructive sleep apnea syndrome in the two groups.

Adolescent↗
PubMed1999

Overview of phase I surgery for obstructive sleep apnea syndrome.

It is well established that obstructive sleep apnea syndrome is associated with increased morbidity and mortality. Surgical therapy has been demonstrated to be a viable treatment option for cure. Thorough presurgical evaluation with the identification of the type of airway abnormality is mandatory to allow for the utilization of a surgical protocol that results in improved clinical outcomes. Phase I surgical protocol is designed to apply specific surgical procedures to alleviate the obstruction(s) present. Following a logical, stepwise surgical approach in airway reconstruction will minimize surgical interventions and avoid unnecessary operations. The incorporation of a risk-management protocol will minimize treatment complications while achieving cure.

Female↗
PubMed1999

Overview of phase II surgery for obstructive sleep apnea syndrome.

Maxillomandibular advancement is an extremely effective surgical procedure for the treatment of obstructive sleep apnea syndrome. When properly executed, it is associated with minimal morbidity and is well accepted by patients. It is a treatment option that achieves long-term care.

Aged↗
PubMed1999

Extracranial optic nerve decompression: a 10-year review of 92 patients.

Over a 10-year period the authors have performed 92 transethmoidal optic nerve decompressions for the treatment of visual loss due to various pathological processes, including 45 cases of trauma, 32 cases of neoplasm, 2 cases of bacterial pansinusitis, 5 cases of sphenoethmoidal mucocele, 4 cases of aspergillosis (all were immunocompetent patients), 2 cases of Wegener's granulomatosis, and 2 cases of sarcoidosis. Forty-eight patients (52%) had preoperative visual acuity of light perception or better, and in 44 patients (48%) the preoperative vision was no light perception. Sixty-five patients (71%) achieved improvement of vision postoperatively. Twenty-four patients (26%) had no change in vision and 3 patients (3%) had deterioration of vision after surgery. The mean percentage of improvement was 40.7% +/- 6.9% in the trauma group, 61.6% +/- 23.2% in the neoplasm group, 66.4% +/- 25.2% in the infectious/mucocele group, and only one patient in the inflammatory group had slight visual improvement from no light perception to counting fingers. Extracranial optic nerve decompression can result in the improvement of visual function in some patients with optic nerve injury from various causes.

Adolescent↗
PubMed1998

The EWS/ATF1 fusion protein contains a dispersed activation domain that functions directly.

Naturally occurring chromosomal fusion of the Ewings Sarcoma Oncogene (EWS) to distinct cellular transcription factors, produces aberrant transcriptional activators that function as dominant oncogenes. In Malignant Melanoma of Soft Parts the N-terminal region of EWS is fused to C-terminal region of the cAMP-inducible transcription factor ATF1. The EWS/ATF1 fusion protein binds to ATF sites present in cAMP-responsive promoters via the ATF1 bZIP domain and activates transcription constitutively in a manner that is dependent on an activation domain (EAD) present in EWS. To further define the requirements for trans-activation we have performed mutational analysis of EWS/ATF1 in mammalian cells and report several new findings. First, trans-activation by EWS/ATF1 does not require dimerisation with other ATF family members present in mammalian cells. Second, in contrast to the earlier suggestion of an allosteric role, the EAD can act directly. Third, determinants of trans-activation are dispersed throughout the EAD and cooperate synergistically to produce potent trans-activation. We also report that the region of EWS containing the EAD can activate transcription in Yeast. This latter finding might enable a genetic approach to understanding the mechanism of transcriptional activation by EWS and development of high-throughput screens for EWS inhibitors.

Amino Acid Sequence↗
PubMed1998

MMSP tumor cells expressing the EWS/ATF1 oncogene do not support cAMP-inducible transcription.

Malignant Melanoma of Soft Parts (MMSP) is associated with the EWS/ATF1 fusion protein that arises due to chromosomal fusion of the Ewings Sarcoma oncogene (EWS) and the cellular transcription factor ATF1. EWS/ATF1 can activate several cAMP-inducible promoters, suggesting that cellular transformation in MMSP might involve constitutive activation of cAMP-inducible promoters. To assess this possibility we have examined the status of the cAMP-signaling pathway in the available MMSP-derived cell lines (DTC1 and Su-ccs-1) and find that both cell lines share several features. First, in contrast to previous effects observed in transient assays, three chromosomal promoters containing ATF binding sites are not constitutively activated by endogenous EWS/ATF1 in MMSP cells. Second, all the components that are known to be required for cAMP-inducible transcription are present. Third, phosphorylation of the cAMP-response-element-binding protein (CREB) can be efficiently induced by cAMP. Fourth, cAMP is unable to activate transcription, as assessed by a GAL4/ATF1 reporter assay and analysis of the c-fos and adenovirus early promoters. Thus, cell lines derived from MMSP have a block to cAMP-signaling that lies downstream of CREB phosphorylation. In light of the cAMP-responsiveness of almost all mammalian cell types, our findings suggest that the inability to respond to cAMP might be an important feature of MMSP cells.

Activating Transcription Factor 1↗
PubMed1998

Pharyngoesophageal reconstruction with the ulnar forearm flap.

OBJECTIVE: To evaluate the use of a generous fasciocutaneous ulnar forearm free flap in pharyngoesophageal reconstruction. DESIGN: Tertiary referral center. SETTING: Private practice. PATIENTS: From September 1, 1991, to October 30, 1996, 20 ulnar forearm free flaps were used to reconstruct the pharyngoesophagus in 19 patients after surgery for squamous cell carcinoma. There were 13 circumferential defects and 7 near-circumferential defects (<2 cm of mucosa remaining). The reconstructions were performed primarily (at the time of tumor resection) in 16 cases and secondarily in 4 cases. INTERVENTION: A generous fasciocutaneous ulnar forearm flap with a minimum dimension of 9 x 22 cm was harvested to reconstruct the pharyngoesophagus. A 2-layer closure was performed in flap tailoring and proximal (pharynx to flap) and distal (flap to esophagus) anastomoses to minimize the risk of leakage. Also, portions of the flap were used to monitor flap viability, to cover cervical vessels, to obliterate dead space, and as skin coverage when the skin flaps were deficient. RESULTS: Nineteen of the 20 flaps transferred were successful. Swallow function was restored in 18 cases, and voice was rehabilitated in all the patients using either tracheoesophageal puncture and a voice device or an electrolarynx device. There was 1 perioperative mortality. Three fistulas occurred, all of which healed with nonsurgical treatment. One stricture developed that required intermittent dilatation. The donor site morbidity was minor. CONCLUSIONS: This versatile technique achieves excellent results with a decreased complication rate compared with other methods currently available in pharyngoesophageal reconstruction.

Adult↗
PubMed1998

Radiofrequency volumetric tissue reduction for treatment of turbinate hypertrophy: a pilot study.

OBJECTIVES: Ideal treatment for nasal obstruction caused by turbinate hypertrophy remains in question. Medical therapy is often ineffective. Surgical procedures have associated morbidity including pain, bleeding, crusting, adhesion, infection, and dryness. Radiofrequency has recently been shown to be safe and effective in volumetric tissue reduction of the tongue in the animal model and of the palate in human beings. We prospectively evaluate the safety and effectiveness of radiofrequency volumetric tissue reduction (RFVTR) for the treatment of nasal obstruction caused by inferior turbinate hypertrophy. METHODS: Twenty-two consecutive patients with nasal obstruction and associated inferior turbinate hypertrophy refractory to medical therapy were evaluated for RFVTR. The study design limited the region of treatment to the anterior third of the inferior turbinate. The procedures were performed in an ambulatory facility with patients under local anesthesia. Clinical examinations, patient questionnaires, and visual analog scales were used to assess treatment outcomes. RESULTS: No adverse effects were encountered, including bleeding, crusting, dryness, infection, adhesion, or a worsening of obstruction. Mild edema was noted in all patients but was of short duration (24 to 48 hours). Posttreatment discomfort was well controlled with acetaminophen. Eight weeks after treatment, nasal breathing improved in 21 of 22 patients, with a 58.5% reduction in severity and a 56.5% decrease in the frequency of nasal obstruction. CONCLUSION: The results of this study demonstrate that RFVTR of the hypertrophic inferior turbinate is associated with minimal adverse effects. Furthermore, this new treatment modality achieves subjective improvement in patients with symptoms of nasal obstruction. However, because of the small sample size and short follow-up, future investigations are needed to fully evaluate the use of RFVTR in the treatment of nasal obstruction caused by turbinate hypertrophy.

Adolescent↗
PubMed1998

The odontogenic keratocyst: a 20-year clinicopathologic review.

The odontogenic keratocyst (OKC) is a jaw cyst with a proclivity for local invasion and recurrence. This 20-year retrospective study was conducted to evaluate methods of treatment and recurrence rates. Forty-nine patients were identified with an average age at presentation of 39.5 years. The molar region of either the mandible or maxilla was the principal primary location; the maxillary antrum was also a common site. The majority of cysts were unilocular and associated with adjacent dentition. Initial therapy was typically enucleation with or without extraction of associated teeth; seven cases of recurrent or second primary odontogenic keratocysts required more extensive surgery. Follow-up ranged from 1 to 15 years with an average duration of 4.3 years. The overall recurrence rate was 35%, and the average time to recurrence 4 years. A recurrence rate of 60% was documented for patients with basal cell nevus syndrome or a family history thereof. Long-term follow-up is necessary following initial OKC treatment. The high rate of recurrence in patients with documented or suspected basal cell nevus syndrome suggests the need for more aggressive initial surgical management in this selected patient population.

Adult↗