The central roles of obesity-associated dyslipidaemia, endothelial activation and cytokines in the Metabolic Syndrome--an analysis by structural equation modelling.

HYPOTHESIS: The multi-faceted components of the metabolic syndrome now include markers of inflammation and endothelial activation. Despite this growing body of epidemiological data, standard statistical methods fail to evaluate the nature of these associations adequately. In this pilot study, we hypothesize that obesity may lead to endothelial activation which is in part mediated by dyslipidaemia and proinflammatory cytokines. These factors interact to give rise to hyperinsulinaemia, hypertension and an anti-fibrinolytic state. To test this hypothesis, we used confirmatory factor analysis and structural equation modelling to fit these data to a model designed on theoretical grounds. METHODS: Metabolic syndrome variables, cytokines (IL6 and TNFalpha), markers of inflammation and endothelial activation were measured in 107 Caucasian non-diabetic subjects aged 40-75 y. Using confirmatory factor analysis, we identified six factors to represent composite measurements of blood pressure, obesity, dyslipidaemia, hyperinsulinaemia, endothelial activation and the anti-fibrinolytic state. We fitted these variables to two separate models, one using IL-6 and the other TNFalpha as the cytokine, and examined the inter-relationships (path analysis) amongst these variables, based on the above hypothesis. RESULTS: Men were centrally more obese and had increased markers of endothelial activation, inflammation and the anti-fibrinolytic state as well as hyperinsulinaemia and dyslipidaemia, compared with women. Obesity indexes (both body mass index and waist-hip ratio) were strongly associated with multiple cardiovascular risk factors. Both IL6 and TNFalpha were correlated with age, male gender, obesity indexes and markers of endothelial activation. Only IL-6 was associated with smoking while TNFalpha was correlated with hyperinsulinaemia. In the TNFalpha model, 61% of the obesity variance was explained by male gender, 36% of TNFalpha variance by age and dyslipidaemia, 43% of dyslipidaemia variance by age and obesity, 33% of hyperinsulinaemia variance by dyslipidaemia and a non-smoking state, 29% of anti-fibrinolytic state variance by hyperinsulinaemia, 65% of endothelial activation variance by TNFalpha, dyslipidaemia and hyperinsulinaemia, 34% of blood pressure variance by hyperinsulinaemia and endothelial activation. In the IL-6 model, we observed similar relationships except that 23% of IL6 variance was explained by smoking and age. CONCLUSIONS: Using confirmatory factor analysis and structural equation modelling, we found that obesity, dyslipidemia and cytokines were the principal explanatory variables for the various components of the metabolic syndrome, with IL6 and TNFalpha having different explanatory variables and effects. These complex inter-relationships were in part mediated by hyperinsulinaemia and endothelial activation. While this hypothetical model was based on scientific evidence, supported by rigorous analysis, it requires further confirmation in large-scale prospective studies. Given the complexity of the biological system and its interactions with exogenous factors, structural equation modelling provides a useful scientific tool for hypothesis testing, complementary to the more traditional experimental and cohort studies.

N-acetyl-serotonin reduces copper (I) ion-induced lipid peroxidation in bovine retinal homogenates.

PURPOSE: Chalcosis is an ocular condition caused by penetration injury of copper or its alloy, which leads to extensive ocular inflammation. N-acetyl-serotonin has recently been identified as a potent antioxidant against free radical stress. In this study, we determined the efficacy of N-acetyl-serotonin against the copper (I)-induced retinal lipid peroxidation. METHODS: Copper (I)-treated (100 microM) bovine retinal homogenates were incubated with 6 different concentrations (i.e. 0.00, 0.25, 0.50, 1.00, 2.00 and 4.00 mM) of N-acetyl-serotonin or vitamin E. The malondialdehyde level was measured as an index of lipid peroxidation. RESULTS: Copper (I) ions induced a significant dose-dependent increase in malondialdehyde (p=0.007). Co-incubation with N-acetyl-serotonin or vitamin E significantly suppressed the copper (I)-induced malondialdehyde production (p<0.0001). The concentration to inhibit 50% of damage for N-acetyl-serotonin and vitamin E were found to be 1.54 mM and 0.45 mM, respectively. CONCLUSION: Although N-acetyl-serotonin is only 29% as effective as vitamin E in suppressing the copper (I)-induced lipid peroxidation, the present study supports a pharmacological potential of N-acetyl-serotonin combating free radical oxidative damages in the ocular tissues.

Studies on common illnesses and medical care utilization patterns of adolescents in Hong Kong.

PURPOSE: To estimate the prevalences of common illnesses in Hong Kong adolescents, the sociodemographic and selected risk factors associated with these illnesses, and their health care utilization behavior and attitudes. METHODS: A cross-sectional questionnaire survey of 3355 participating secondary school students (response rate = 98%). RESULTS: Self-reported 3-month prevalences were obtained for cough/cold/influenza (55.2%), digestive disorders (34.6%), accidental injuries (29.5%), headache/dizziness (23.6%), chronic anxiety/insomnia (20.1%), skin problems (9.5%), asthma (3.8%), liver disease (1.3%), and menstrual pain (13.8% of female students). Self-perceived poor health, smoking, and alcohol consumption were associated with many of these illnesses. Treatment choice depended on the illness suffered (e.g., most students with respiratory problems consulted medical practitioners, whereas most with chronic anxiety/insomnia did not). Many students lacked trust in their doctors, doctor-shopped, relied heavily on self-medication, did not comply with prescribed treatments, would not seek help about medical problems, felt they had insufficient access to health information, and wanted confidential health care. CONCLUSIONS: This study examined for the first time the common illnesses and health care utilization patterns of Hong Kong adolescents. Students with chronic anxiety/insomnia were much less likely to seek care, indicating a need for better education on mental health. Efforts to prevent smoking and alcohol consumption among adolescents need to be strengthened. The students' attitudes, poor compliance and help-seeking behaviors suggest suboptimal use of the health care system. Our findings are useful for international comparisons by medical practitioners, health care managers, and researchers.

Strabismus examination by telemedicine.

OBJECTIVE: To evaluate the reliability of strabismus assessment using telemedicine (TM) technology. DESIGN: Two prospective interobserver agreement studies. One study compared the agreement between a standard and a TM examination, whereas the other assessed agreement between two independent standard examinations. PARTICIPANTS: Strabismus patients over 4 years of age examined at a remote community clinic and patients assessed in a strabismologist's urban practice. METHODS: Forty-two patients were examined in person by a pediatric ophthalmologist at the remote community and independently by a pediatric ophthalmology fellow by means of TM (TM-standard study). The TM examination was performed with the help of a qualified ophthalmic assistant at the remote telecommunication center using a Power Cam 100 camera, a Picture Tel Concorde 4500 teleconferencing system, and a 224 kilobyte bandwidth. For comparison, independent in person examinations were performed on 43 patients by both examiners (standard-standard study). Agreement was measured using unweighted kappa (k) for categorical data, the intraclass correlation coefficient (ICC) for continuous data, and percent agreement. The odds of disagreement with TM (comparing the TM-standard versus standard-standard studies) was assessed with logistic regression analysis. MAIN OUTCOME MEASURES: Three parameters were assessed: (1) category of strabismus, determined by observation without cover test; (2) angle of deviation at 0.33 and 6.0 m; and (3) ocular muscle action. RESULTS: Agreement on the category of strabismus was good (k > 0.61) other than for vertical deviations. However, there was good to excellent agreement between TM and standard examinations on the vertical (ICC = 0.78) and horizontal (ICC = 0.79) angles of deviation with 6-m fixation with the cover test. Muscle ratings agreed within one point for the lateral, superior, and inferior rectus muscle actions in more than 90% of the eyes examined. Although good agreement was observed in the TM-standard study, it was inferior to the agreement in the standard-standard study. Examination by TM increased the odds of disagreement compared with examination in person by twofold to threefold. CONCLUSIONS: Strabismus examination can be performed with a good level of reliability with the use of medium bandwidth video teleconferencing equipment. However, reduced reliability has been noted in the detection of small vertical deviations by inspection and in evaluating oblique muscle actions.

Axenfeld-Rieger syndrome resulting from mutation of the FKHL7 gene on chromosome 6p25.

Mutations in the forkhead-like 7 (FKHL7) gene have been recently shown to cause juvenile glaucoma and anterior segment anomalies. We report on a three-generation family with Axenfeld-Rieger syndrome (ARS), harboring an alteration in the FKHL7 gene. Genetic linkage analyses excluded the ARS phenotype from chromosomes 4q25 and 13q14, the locations of the PITX2 and RIEG2 loci, respectively. Evidence of linkage was observed with markers at 6p25, near the FKHL7 gene. Direct sequencing of FKHL7 detected a C67T mutation that segregated with the ARS phenotype in this family, but was not detected in over 80 control chromosomes. This mutation is predicted to cause a nonsense mutation of the FKHL7 protein (Gln23Stop) upstream of the forkhead DNA-binding domain, and thus to generate a truncated FKHL7 protein product. This discovery broadly implicates FKHL7 in ocular, craniofacial, dental, and umbilical development.

Cellular phosphorylation of an acidic proline-rich protein, PRP1, a secreted salivary phosphoprotein.

Phosphorylation of many secreted salivary proteins is necessary for their biological functions. Identification of the kinase, which is responsible for in vivo phosphorylation, is complicated, because several of the protein phosphorylation sites conform both to the recognition sequence of casein kinase 2 (CK2) and Golgi kinase (G-CK), which both are found in the secretory pathway. This study was undertaken to determine the kinase recognition sequence in a secreted proline-rich salivary protein, PRP1, and thereby identify the responsible kinase. This was done by transfecting a human submandibular cell line, HSG, and a kidney cell line, HEK293, with expression vectors encoding wild-type or mutated PRP1. It was shown that phosphorylation occurred only at the same sites, Ser8 and 22, as in PRP1 purified from saliva. Phosphorylation at either site did not depend on the other site being phosphorylated. The sequence surrounding Ser8 has characteristics of both CK2 and G-CK recognition sequences, but destruction of the CK2 recognition site had no effect on phosphorylation, whereas no phosphorylation occurred if the G-CK recognition sequence was altered. The sequence surrounding Ser22 did not conform to any known kinase recognition sites. If Ser22 was mutated to Thr, no phosphorylation was seen, and a cluster of negatively charged residues at positions 27-29 was identified as part of the enzyme recognition site. Ser22 may be phosphorylated by a G-CK that recognizes an atypical substrate sequence or by a novel kinase. No difference in phosphorylation was seen between undifferentiated and differentiated HSG cells.

The mechanism of activation of NK-cell IFN-gamma production by ligation of CD28.

We have investigated the mechanism by which anti-CD28 antibodies activates IFN-gamma production by murine NK cells. These studies reveal that engagement of CD28 alone by this antibody is a poor activator of this cytokine response. Effective stimulation requires simultaneous ligation of the receptor for Fc (FcgammaRIII, CD16) which on its own is also a poor inducer of murine NK cells. The mechanism by which immobilized anti-CD28 increases IFN-gamma mRNA abundance involves both upregulation of transcription as well as induction of mRNA stabilization. However, the elevation of transcription is not as evident as that induced by IL-12 which, in contrast, does not induce message stabilization. Thus ligation of CD28 in the presence of IL-12 results in a synergistic increase in production of the cytokine. Using this assay we have also determined that immobilized anti-CD28 cannot induce resting NK cells to produce IFN-gamma. In contrast, the same cells can be induced by BCL1-C11 tumor cells that express high amounts of the CD28 ligand, B7-2. These studies provide important insights into the ability of cells bearing counter-receptor for CD28 to activate NK cell-cytokine production in vivo.

Prevalence and correlates of physical abuse in Hong Kong Chinese adolescents: a population-based approach.

OBJECTIVE: The objectives were to estimate the prevalence and correlates of physical abuse-related outcomes in the family setting in Hong Kong's adolescent population. METHOD: A cross-sectional study design was used. A randomly selected sample of 3,355 secondary school students in Kwai Tsing District of Hong Kong was surveyed. The response rate was 98%. RESULTS: The prevalence rates of corporal punishment, being beaten by parents for no apparent reason, being beaten to injury by family members in the past 3 months and any one of the above three were 4.9% (95% CI, 4.2% to 5.6%), 2.0% (95% CI, 1.5% to 2.5%), 1.1% (95% CI, .98% to 1.2%) and 6.6% (95% CI, 5.7% to 7.5%), respectively. Students who had experienced the above physical abuse-related outcomes were at a significant disadvantage for a wide range of morbidity indicators, including self-perceived bad health, anxiety and stress, somatic illnesses (such as asthma and epigastric pain), injuries and accidents, and hospitalization. They were more likely to have poor familial relations and coping skills, and to take up habits which potentially put their health at risk, such as smoking, alcohol consumption, and fighting with others. CONCLUSIONS: Our prevalence estimates of physical abuse in the family setting for a student population in Hong Kong is an improvement over previous local estimates of physical abuse occurrence, which were mainly based on case notifications and clinical samples. The results also show that the abused adolescents are growing up in an environment filled with physical, psychological, and familial adversities.

Myopia predicts better outcome in persistent hyperplastic primary vitreous.

PURPOSE: Persistent hyperplastic primary vitreous (PHPV) is a congenital disorder that presents with a spectrum of ocular anomalies, including cataracts, microphthalmia, and hyaloid vessel remnants. Severe visual loss due to secondary glaucoma and retinal detachment is common. This report evaluates the visual outcome of a variant of PHPV with myopia not associated with glaucoma. METHODS: The records of 23 consecutive patients with the diagnosis of PHPV (all unilateral) from October 1992 to August 1995 were reviewed. All but three patients had a cataract extraction procedure and all underwent amblyopia therapy. Eyes with a phakic myopic refractive error (Rx) or aphakic refractive correction < or = 8.5 diopters (D) in the immediate postoperative period were designated as myopic. RESULTS: Six patients were in the myopic group (Group 1) and 17 in were the nonmyopic group (Group 2). The mean age of diagnosis was 21.1 months in Group 1 versus 2.0 months in Group 2, with a comparable follow-up period of 36 months. The mean preoperative Rx of Group 1 was -7.78 D. The mean aphakic Rx of Group 2 was +18.29 D. Average axial length measurement determined by echography was 22.46 mm in Group 1 and 14.03 mm in Group 2. The mean corneal diameter was 11.3 mm in Group 1 vs 8.9 mm in Group 2. In Group 2, seven eyes developed retinal detachment and four developed glaucoma. These complications did not develop in Group 1 during the follow-up period. Overall functional visual acuity was better in Group 1, with a median visual acuity at final follow up of 20/160, as compared with light perception for Group 2. CONCLUSIONS: PHPV eyes with myopia were not detected as early as the typical PHPV eyes, primarily because of less media opacification and near-normal corneal diameters. These eyes showed a more favorable visual outcome as they were less likely to develop typical PHPV-related postoperative complications. Myopic PHPV eyes may require a different management approach.

Intermediate-term outcome of variable dose mitomycin C filtering surgery.

PURPOSE: Trabeculectomy with adjunctive mitomycin C is associated with high success rates in studies with follow-up of less than 1 year. This report evaluates the visual and intraocular pressure (IOP) outcome in eyes after trabeculectomy with adjunctive mitomycin C 1 to 3 years after surgery in a predominantly white group (98.1%). METHODS: The records of 157 eyes of 157 consecutive patients, aged 18 or older, who underwent mitomycin C trabeculectomies for uncontrolled glaucoma of various causes were reviewed. All surgeries were performed between April 1991 and June 1993. The concentration of mitomycin C varied from 0.2 to 0.5 mg/ml and was applied for 30 seconds to 5 minutes (only one patient received 0.2 mg/ml). Of the 157 eyes, 110 eyes were at high risk for failure (previous surgeries or inflammatory glaucoma). Thirty-nine eyes had preoperative IOP < or = 21 mmHg. RESULTS: The mean preoperative IOP was 29.4 +/- 10.3 mmHg. This was reduced to 13.0 +/- 7.6 mmHg at 1 year, 11.5 +/- 6.4 mmHg at 2 years, and 13.4 +/- 7.3 mmHg at 3 years. Cumulative survival rate by life-table analysis was 94.2% +/- 1.9% at 1 year, 92.1% +/- 2.4% at 2 years, and 88.7% +/- 4.0% at 3 years, where failure was defined as reoperation for control of IOP. Complications included cataract formation-progression (n = 31), hyphema (n = 26), choroidal detachment (n = 21), hypotony maculopathy (n = 5), and endophthalmitis (n = 2). Vision deteriorated in 29 eyes and improved by 2 or more Snellen visual acuity lines in 29 eyes. CONCLUSION: The IOP reduction after mitomycin C filtering surgery is sustained in the intermediate-term, 1 to 3 years, follow-up period.

Palpebral conjunctival transient amplifying cells originate at the mucocutaneous junction and their progeny migrate toward the fornix.

PURPOSE: The conjunctival epithelium performs an important role in the homeostasis and integrity of the eye. These cells need to be replaced in order to protect the integrity of the ocular surface. Epithelial cells are replaced from slow cycling stem cells which in turn produce transient amplifying cells that undergo further divisions before becoming mature conjunctival epithelial cells. The natural history of the bulbar palpebral conjunctival cells has not been previously described. METHODS: A single injection of bromodeoxyuridine (brdU), a thymidine analogue, was administered intraperitoneally to adult rabbits at a concentration of 50 mg/kg body weight. The rabbits were sacrificed at 1, 3, 5, and 7 days following the injections. The orbital contents including the eyelids were exenerated en bloc, frozen in a manner that maintained the orientation and continuity between the eyelids and globe and sectioned in a parasagittal plane. The tissue was stained immunohistochemically to detect brdU labeled conjunctival epithelial cells. The brdU-positive epithelial cells were counted in a series of 0.4 mm zones starting at the mucocutaneous junction of the eyelid and progressing through the fornix and bulbar conjunctiva. Rabbit eyelids and human eyelid surgical specimens were stained for cyclin D1, a marker for cells that are in the G1 phase of the cell cycle. RESULTS: In both the upper and lower eyelids, the peak number of brdU labeled cells/0.4 mm zone was located at progressively greater distances from the mucocutaneous junction in the animals sacrificed at 1, 3 and 5 days respectively, and gone by 7 days. A focus of brdU-labeled conjunctival cells remained within 1-2 mm of the mucocutaneous junction at all post-injection intervals. Foci of cyclin 1-positive cells were found almost exclusively near the mucocutaneous junction, but not in the fornix. CONCLUSIONS: The mucocutaneous junction of the conjunctival epithelium is a source of actively dividing transient amplifying cells that migrate toward the fornix at a rate of about 1.7 mm/day as replacement conjunctiva so that at least some conjunctival epithelial stem cells must be located near the mucocutaneous junction. The presence of cyclin D1 staining cells at the mucocutaneous junction supports this view. These results are not necessarily at variance with previous studies, but they do diminish the relative importance assigned the forniceal region in palpabral conjunctival homeostasis. Moreover, the mucocutaneous junction might provide a therapeutically significant source of replacement conjunctival cells. The transit time of conjunctival epithelial cells is about 6 days.

The metabolic syndrome in Hong Kong Chinese. The interrelationships among its components analyzed by structural equation modeling.

OBJECTIVE: To examine the pattern of the metabolic syndrome in Chinese and the causal relationships among its components, including aging, obesity, hyperglycemia, hypertension, hypertriglyceridemia, and hyperinsulinemia in these subjects. RESEARCH DESIGN AND METHODS: Based on a 75-g oral glucose tolerance test, the World Health Organization criteria were used for the diagnosis of glucose intolerance in a population-based study involving 1.513 Chinese subjects in two work sites. Demographic data including age, family history of diabetes, BMI, waist-to-hip ratio (WHR), and sitting blood pressure (BP) were documented. Fasting plasma glucose, triglyceride (TG) and insulin concentrations, and spot urinary albumin concentration (Ualb) were also measured. Structural equation modeling incorporating factor analysis and path analysis was performed to examine the causal relationships among these variables and their interactions. RESULTS: Subjects who were treated with antidiabetic and/or antihypertensive drugs or who had a plasma creatinine level > or = 150 mumol/l were excluded (n = 52). The prevalence of diabetes and impaired glucose tolerance (IGT) were 3.9% (n = 34) and 7.2% (n = 63) in men (n = 881) and 3.1% (n = 18) and 6.7% (n = 39) in women (n = 580), respectively. In both groups, glucose intolerance was associated with increasing age, higher BMI, WHR, BP, Ualb, serum TG, and insulin levels as well as higher prevalence rates of positive family history of diabetes. Structural equation modeling showed that age was a significant determinant for both BMI and WHR. Age and obesity accounted for most of the variance of BP, Ualb, plasma glucose, insulin and TG levels either directly or indirectly. Plasma glucose was determined by a positive family history of diabetes, age, and BMI while TG was dependent on BMI and WHR. Serum insulin was mainly determined by a positive family history of diabetes, obesity, plasma glucose, and TG levels. Apart from age and obesity, BP was also determined by serum insulin, both of which had causal effects on Ualb. CONCLUSIONS: This model emphasizes the centrality of aging and obesity as well as a positive family history of diabetes as major determinants of the components of the metabolic syndrome. These components in turn had causal effects upon one another. Apart from a familial tendency, a central neurohormonal mechanism may account for these abnormalities mediated primarily through obesity and in close association with aging.

Targeted and natural (piebald-lethal) mutations of endothelin-B receptor gene produce megacolon associated with spotted coat color in mice.

Endothelins act on two subtypes of G protein-coupled receptors, termed endothelin-A and endothelin-B receptors. We report a targeted disruption of the mouse endothelin-B receptor (EDNRB) gene that results in aganglionic megacolon associated with coat color spotting, resembling a hereditary syndrome of mice, humans, and other mammalian species. Piebald-lethal (sl) mice exhibit a recessive phenotype identical to that of the EDNRB knockout mice. In crossbreeding studies, the two mutations show no complementation. Southern blotting revealed a deletion encompassing the entire EDNRB gene in the sl chromosome. A milder allele, piebald (s), which produces coat color spotting only, expresses low levels of structurally intact EDNRB mRNA and protein. These findings indicate an essential role for EDNRB in the development of two neural crest-derived cell lineages, myenteric ganglion neurons and epidermal melanocytes. We postulate that defects in the human EDNRB gene cause a hereditary form of Hirschsprung's disease that has recently been mapped to human chromosome 13, in which EDNRB is located.

Age-dependent decrease of process formation by cultured oligodendrocytes is augmented by protein kinase C stimulation.

The proportion of cultured rat oligodendrocytes (OL) that extended processes of over three soma diameter in length is dependent on the age of the animals from which the brains were derived; up to 70% of neonatal OL attained this criterion within 3 days, and this proportion progressively decreased with advancing ages of the animals (1, 3, and 6 months). The lower extent of process formation from older rat OL could be augmented, and indeed to equal neonatal levels, by treatment of cells with phorbol esters that stimulate protein kinase C: 4 beta-phorbol-12,13-dibutyrate (PDB) and phorbol-12-myristate-13-acetate (PMA). Enhancement of process formation by PDB and PMA was also observed for cultured adult human and bovine OL. For adult OL from all three species, a phorbol ester that binds but that does not activate protein kinase C, 4 alpha-phorbol-12,13-didecanoate, did not result in enhancement of process formation. Selectively to biologically active phorbol esters was shown by the inability of a wide range of growth factors to promote process extension. Immunohistochemical analyses indicate that the type III isozyme of protein kinase C predominates in cultured OL; the apparent intensity of immunoreactive PKC was not different between controls or cultures treated for 12 days with PDB, suggesting that the persistent presence of PDB might not have down-regulated the enzyme, in contrast to other cell types. We propose that stimulation of protein kinase C is critical to the triggering of process formation by cultured OL in vitro.