Biomedical subjects
C Chen
Publications and source records attributed to C Chen.
Aberrant facial nerve regeneration (AFR): an under-recognized cause of ptosis.
INTRODUCTION: Aberrant facial nerve regeneration (AFR) following facial nerve palsy may give rise to ptosis because of increased orbicularis tone. We describe a series of patients presenting with ptosis where the underlying aetiology of AFR was often not recognized by the referring clinicians. METHODS: Retrospective case review. RESULTS: A total of 15 cases with ptosis, secondary to AFR, were seen at the Royal Adelaide Hospital Oculoplastic Clinic between 2000 and 2002. Of these, 10 (67%) were referred by general ophthalmologists. Ptosis was the only reason for referral in 11 patients (73%) and features of AFR or a past history of facial nerve palsy were not mentioned in seven referrals (overall 46%). All patients reported a previous facial palsy. The palpebral aperture was reduced on the affected side with reduction in both upper and lower margin reflex distance (MRD) by a mean of 1.5+/-0.7 mm (P<0.001) and 1.0+/-0.3 mm (P<0.001), respectively. The orbicularis tone was increased and strength reduced on the affected side in all patients. However, none had lagophthalmos. Signs of AFR were demonstrated in all patients with either an increase in ptosis or eyelid closure on the affected side during cheek puffing. CONCLUSION: Patients with AFR following facial nerve palsy may present with ptosis without recognition of the underlying aetiology. Signs of AFR ptosis include a decreased palpebral aperture with a reduced upper and lower MRD. The diagnosis can be established with demonstration of an increase in ptosis during cheek puffing. Recognition of AFR is important in these cases owing to the implications for management and post-operative patient satisfaction.
Recombinant adeno-associated virus-mediated kallikrein gene therapy reduces hypertension and attenuates its cardiovascular injuries.
Gene therapy of hypertension requires long-term expression of a therapeutic gene to achieve stable reduction of blood pressure. Human tissue kallikrein (HK) cleaves kininogen to produce a potent vasoactive peptide kinin, which plays an important role in the regulation of the cardiovascular and renal functions. In the present study, we have delivered human kallikrein cDNA with an rAAV vector to explore the potential therapeutic effects of kallikrein on hypertension and related secondary complications. A single tail vein injection of the rAAV-HK vector into the adult spontaneously hypertensive rats resulted in a significant reduction (12.0+/-2.55 mmHg, P<0.05, n=6, ANOVA) of the systolic blood pressure from 2 weeks after vector injection, when compared with the control rAAV-lacZ vector-injected rats. Weekly blood pressure monitoring showed stable hypertension-reduction effect throughout the course of the 20-week experiments. In addition, total urine microalbumin contents decreased as a result of rAAV-HK treatment. Histological analysis of various tissues showed remarkable amelioration of cardiovascular hypertrophy, renal injury and collagen depositions in the rAAV-treated group. Finally, persistent expression of the transgene product HK was confirmed by the enzyme-linked immunosorbent assay and reverse transcription-polymerase chain reaction. We conclude that rAAV-mediated HK delivery rendered a long-term and stable reduction of hypertension and protected against renal injury, cardiac remodeling in the spontaneously hypertensive rat model. Further studies are warranted for the development of a gene therapy strategy for human hypertension.
Clonal distribution of natural competence in Actinobacillus actinomycetemcomitans.
The competence for natural transformation was investigated in 67 Actinobacillus actinomycetemcomitans strains. The transformation assays were performed with both cloned DNA fragments and chromosomal markers of A. actinomycetemcomitans. Competence was found in 12 of 18 serotype a strains, 0 of 21 serotype b strains, 0 of 14 serotype c strains, 3 of 6 serotype d strains, 3 of 4 serotype e strains, 0 of 3 serotype f strains, and 0 of 1 nonserotypeable strain. The transformation frequencies varied from 5 x 10(-3) to 4 x 10(-6) (median 1.5 x 10(-4)). The distribution pattern of natural competence is concordant with the major clonal lineages of A. actinomycetemcomitans. Serotype a strains are predominantly competent for transformation, while serotypes b and c strains are apparently non-competent.
Presurgical intravenous parecoxib sodium and follow-up oral valdecoxib for pain management after laparoscopic cholecystectomy surgery reduces opioid requirements and opioid-related adverse effects.
BACKGROUND: Opioids are associated with numerous adverse effects. It is unclear if reduced postoperative opioid consumption lowers the incidence and severity of opioid-related adverse effects. This analysis -- from a multicenter, randomized, double-blind trial -- tested if the reduction of opioid consumption among patients who received intravenous preoperative parecoxib 40 mg, followed by oral valdecoxib 40 mg qd postoperatively, in Days 1-4 after outpatient laparoscopic cholecystectomy surgery, reduced opioid-related symptoms. METHODS: Patients received intravenous fentanyl for pain before discharge, and oral acetaminophen 500 mg hydrocodone 5 mg q 4-6 h prn postdischarge for up to 7 days postsurgery. Patients also received intravenous parecoxib 40 mg administered 30-45 min preoperatively, and valdecoxib 40 mg qd up to Day 4 and prn Days 5-7 postsurgery, or placebo. Patients completed an opioid-related Symptoms Distress Scale (SDS) questionnaire every 24 h for 7 days. Opioid use was converted to morphine-equivalent doses (MEDs). Clinically meaningful events (CMEs) for 12 opioid-related symptoms were assessed by three ordinal measures: frequency, severity, and bothersomeness. Reduction of CMEs on Day 1 and number of patient-days with CMEs on Days 1-4 were examined. RESULTS: Cumulative MEDs on Day 0, Day 1, and Days 1-4 were significantly lower in the parecoxib/valdecoxib group compared with the placebo group (P < 0.001). At the end of Day 1, parecoxib/valdecoxib-treated patients had significantly lower SDS scores (P < 0.02), a significantly reduced incidence of CMEs (P < 0.05), and significantly fewer patient-days with CMEs in Days 1-4 than placebo patients (P < 0.05). Patients in the parecoxib/valdecoxib group were less likely to have CMEs for multiple symptoms than those in the placebo group (P < 0.001). CONCLUSIONS: Treatment with parecoxib and valdecoxib significantly reduced the cumulative MED requirements, the incidence of opioid-related adverse effects, and patient-days with CMEs.
Cell cycle arrest of human gingival fibroblasts and periodontal ligament cells by Actinobacillus actinomycetemcomitans: involvement of the cytolethal distending toxin.
The cytolethal distending toxin (Cdt) is produced by several Gram-negative bacterial species and causes growth arrest and morphological alterations in mammalian cells. Actinobacillus actinomycetemcomitans, which is involved in the pathogenesis of localized aggressive periodontitis, also produces a Cdt that affects periodontal connective tissue cells. The aim of this study was to investigate in which phase of the cell cycle these cells are arrested and enlarged when challenged with A. actinomycetemcomitans, and to evaluate the involvement of its Cdt. Human gingival fibroblasts and periodontal ligament cells were challenged with A. actinomycetemcomitans extract, or with purified Cdt, and cell cycle analysis was performed by propidium iodide staining and flow cytometry. Cells exposed to an A. actinomycetemcomitans wild-type strain, or to purified Cdt, were arrested in both G1 and G2/M phases, and appeared enlarged compared to the corresponding controls. The cellular enlargement occurred in both G1 and G2/M arrested cells. In contrast, cells exposed to an A. actinomycetemcomitans cdt-knockout mutant strain showed cell cycle phase distribution and size similar to the controls. In conclusion, A. actinomycetemcomitans causes a combined G1 and G2/M growth arrest and enlargement in periodontal connective tissue cells, which is attributed to its Cdt.
Particle-hemodynamics simulations and design options for surgical reconstruction of diseased carotid artery bifurcations.
Based on the hypothesis that aggravating hemodynamic factors play a key role in the onset of arterial diseases, the methodology of "virtual prototyping" of branching blood vessels was applied to diseased external carotid artery (ECA) segments. The goals were to understand the underlying particle-hemodynamics and to provide various geometric design options for improved surgical reconstruction based on the minimization of critical hemodynamic wall parameters (HWPs). First, a representative carotid artery bifurcation (CAB) and then CABs with stenosed ECAs, i.e., a distally occluded ECA and an ECA stump, were analyzed based on transient three-dimensional blood flow solutions, employing a user-enhanced commercial finite volume code. Specifically, the HWPs, i.e., oscillatory shear index, wall shear stress angle gradient, near-wall residence time of monocytes, and near-wall helicity angle difference were evaluated to compare the merits of each design option, including a reconstructed near-optimal junction which generates the lowest HWP-values. The results provide physical insight to the biofluid dynamics of branching blood vessels and guide vascular surgeons as well as stent manufacturers towards interventions leading to high sustained patency rates.
Clonal diversity and stability of subgingival Eikenella corrodens.
Eikenella corrodens is a commensal subgingival bacterium commonly found in both periodontally nondiseased and diseased subjects. The present study examined the clonal diversity and stability of subgingival E. corrodens over time. Ninety-five subjects were enrolled at the baseline examination, including 44 periodontally nondiseased subjects and 51 subjects with aggressive periodontitis. Twenty-two nondiseased subjects and 11 subjects with aggressive periodontitis were subsequently reexamined after an average interval of 14 months. Two subgingival plaque samples were obtained from each subject to determine the total cultivable bacteria. In addition, multiple E. corrodens isolates from each sample were recovered for clonal analysis by arbitrarily primed PCR. The mean numbers of distinct E. corrodens clones harbored by nondiseased subjects and subjects with aggressive periodontitis were 1.3 and 3.0, respectively. Thirty-nine percent of the nondiseased subjects and 63% of the subjects with aggressive periodontitis harbored multiple clones of E. corrodens. The numbers of distinct E. corrodens clones increased significantly (Mann-Whitney ranking test, P < 0.05) in sites from patients with aggressive periodontitis, in sites with pocket depths of 4 mm or greater, in sites with a clinical attachment loss of 2 mm or greater, and in sites coinfected with Porphyromonas gingivalis. Comparison of E. corrodens clones recovered at the baseline and those recovered at the follow-up examination showed that E. corrodens colonization was not stable. Thirty-eight of the 66 follow-up samples (58%) showed a complete change (including de novo colonization of the sites or complete elimination of the organism from the sites) of the subgingival E. corrodens clonal types between the baseline and the follow-up examinations. Our results suggest a complexity of subgingival microbiota not seen previously.
Mitomycin C as an adjunct in the treatment of localised ocular surface squamous neoplasia.
AIM: To report the outcome of topical mitomycin C (MMC) used as adjunctive treatment following primary excision of ocular surface squamous neoplasia (OSSN). METHOD: Prospective, non-comparative interventional case series of 27 primary OSSN lesions from 26 patients treated in a single ocular oncology centre over a 4 year period. RESULT: 27 cases of OSSN received a treatment regimen of surgical excision, followed by topical MMC. Mean follow up of 27 (SD 12) months (range 12-50, median 25 months) revealed zero recurrences. CONCLUSION: MMC treatment following surgical excision decreases the recurrence rate of primary ocular surface neoplasia and should be considered as adjunctive therapy in primary treatment.
Stress and dysmenorrhoea: a population based prospective study.
BACKGROUND: Dysmenorrhoea is the most common gynaecological disorder in women of reproductive age. Despite the association between stress and pregnancy outcomes, few studies have examined the possible link between stress and dysmenorrhoea. AIMS AND METHODS: Using a population based cohort of Chinese women, the independent effect of women's perceived stress in the preceding menstrual cycle on the incidence of dysmenorrhoea in the subsequent cycle was investigated prospectively. The analysis included 1160 prospectively observed menstrual cycles from 388 healthy, nulliparous, newly married women who intended to conceive. The perception of stress and the occurrence of dysmenorrhoea in each menstrual cycle were determined from daily diaries recorded by the women. RESULTS: After adjustment for important covariates, the risk of dysmenorrhoea was more than twice as great among women with high stress compared to those with low stress in the preceding cycle (OR = 2.4; 95% CI 1.4 to 4.3). The risk of dysmenorrhoea was greatest among women with both high stress and a history of dysmenorrhoea compared to women with low stress and no history of dysmenorrhoea (OR = 10.4, 95% CI 4.9 to 22.3). Stress in the follicular phase of the preceding cycles had a stronger association with dysmenorrhoea than stress in the luteal phase of the preceding cycles. CONCLUSION: This study shows a significant association between stress and the incidence of dysmenorrhoea, which is even stronger among women with a history of dysmenorrhoea.
[Stomatitis and ageusia induced by candesartan].
Cases of dysgeusia or ageusia have been reported in patients treated with angiotensin II receptor antagonist such as losartan (5 cases), valsartan (1 case), eprosartan (1 case). This is the first case-report of ageusia following candesartan. A 46-year-old-male patient, with a medical history of renal chronic reject allograft disease, started candesartan 4 mg once daily to treat high blood pressure. Six months later, a progressive ageusia occurred with a burning mouth syndrome. He also developed aphthous ulcers of the mouth, stomatitis and perleche, which led him to lose 8 kilos within 13 months. Thirteen months after the beginning of the treatment candesartan was stopped. The symptoms and lesions required 2 to 3 weeks to disappear. Subsequently, appetite was found again as well as the sense of taste. The temporal sequence of events suggests a causal relationship between ageusia and candesartan.
Nano silica removal from IC wastewater by pre-coagulation and microfiltration.
Microfiltration (MF) coupled with pretreatment by coagulation was adopted in the treatment of chemical mechanical polishing (CMP) wastewater from IC manufacturing plants, containing high concentrations of silica. Poly-aluminium chloride (PACl) was the coagulant, while the cationic polyacrylamide (PAA) was the flocculant aid. Preliminary tests were performed with the raw CMP wastewater in order to determine the optimal coagulation condition for subsequent microfiltration. Analysis of the particle size distribution shows that nearly all silica particles were enlarged from nano scale to at least 4 microm in diameter after the pre-treatment. The pre-treated wastewater was then filtered through a polytetrafluoroethylene (PTFE) membrane with a pore size 0.5 microm at a constant vacuum pressure. Trace amounts of PAA in addition to the PACl coagulation can effectively increases the permeate flux.
Measurement of prompt charm meson production cross sections in pp collisions at square root s = 1.96 TeV.
We report on measurements of differential cross sections dsigma/dp(T) for prompt charm meson production in ppmacr; collisions at sqrt[s]=1.96 TeV using 5.8+/-0.3 pb(-1) of data from the CDF II detector at the Fermilab Tevatron. The data are collected with a new trigger that is sensitive to the long lifetime of hadrons containing heavy flavor. The charm meson cross sections are measured in the central rapidity region |y|</=1 in four fully reconstructed decay modes: D0-->K-pi(+), D(*+)-->D0pi(+), D+-->K-pi(+)pi(+), D(+)(s)-->phipi(+), and their charge conjugates. The measured cross sections are compared to theoretical calculations.
Search for lepton flavor violating decays of a heavy neutral particle in p(-)p collisions at sqrt[s]=1.8 TeV.
We report on a search for a high mass, narrow width particle that decays directly to emu, etau, or microtau. We use approximately 110 pb(-1) of data collected with the Collider Detector at Fermilab from 1992 to 1995. No evidence of lepton flavor violating decays is found. Limits are set on the production and decay of sneutrinos with R-parity violating interactions.
Central pseudorapidity gaps in events with a leading antiproton at the fermilab tevatron pp collider.
We report a measurement of the fraction of events with a large pseudorapidity gap deltaeta within the pseudorapidity region available to the proton dissociation products X in p+p-->p+X. For a final state p of fractional momentum loss xi(p) and 4-momentum transfer squared t(p) within 0.06 3 is found to be 0.246+/-0.001 (stat)+/-0.042 (syst) [0.184+/-0.001 (stat)+/-0.043 (syst)]. Our results are compared with gap fractions measured in minimum bias pp collisions and with theoretical expectations.
Search for the supersymmetric partner of the top quark in dilepton events from pp collisions at square root of s=1.8 TeV.
We have searched for pair production of the supersymmetric partner of the top quark (stop) in 107 pb(-1) of pp collisions at square root of s=1.8 TeV collected by the Collider Detector at Fermilab (CDF). Each stop is assumed to decay into a lepton, bottom quark, and supersymmetric neutrino. Such a scenario would give rise to events with two leptons, two hadronic jets, and a substantial imbalance of transverse energy. No evidence of such a stop signal has been found. We exclude stop masses in the region (80</=m(t)</=135 GeV/c(2)) in the mass plane of stop versus sneutrino.
Search for associated production of Upsilon and vector boson in pp collisions at sqrt[s]=1.8 TeV.
We present a search for associated production of the Upsilon(1S) and a vector boson in 83 pb(-1) of ppmacr; collisions at sqrt[s]=1.8 TeV collected by the CDF experiment in 1994-1995. We find no evidence of the searched signal in the data, and set upper limits to the production cross sections.
Search for long-lived charged massive particles in pp collisions at square root s = 1.8 TeV.
We report a search for the production of long-lived charged massive particles in a data sample of 90 pb(-1) of square root[s]=1.8 TeV pp collisions recorded by the Collider Detector at Fermilab. The search uses the muonlike penetration and anomalously high ionization energy loss signature expected for such a particle to discriminate it from backgrounds. The data are found to agree with background expectations, and cross section limits of O(1) pb are derived using two reference models, a stable quark and a stable scalar lepton.