Range of antinuclear antibodies in "healthy" individuals

OBJECTIVE

To determine the range of antinuclear antibodies (ANA) in "healthy" individuals compared with that in patients with systemic lupus erythematosus (SLE), systemic sclerosis (SSc; scleroderma), Sjögren's syndrome (SS), rheumatoid arthritis (RA), or soft tissue rheumatism (STR).

METHODS

Fifteen international laboratories experienced in performing tests for ANA by indirect immunofluorescence participated in analyzing coded sera from healthy individuals and from patients in the 5 different disease groups described above. Except for the stipulation that HEp-2 cells should be used as substrate, each laboratory used its own in-house methodology so that the data might be expected to reflect the output of a cross-section of worldwide ANA reference laboratories. The sera were analyzed at 4 dilutions: 1:40, 1:80, 1:160, and 1:320.

RESULTS

In healthy individuals, the frequency of ANA did not differ significantly across the 4 age subgroups spanning 20-60 years of age. This putatively normal population was ANA positive in 31.7% of individuals at 1:40 serum dilution, 13.3% at 1:80, 5.0% at 1:160, and 3.3% at 1:320. In comparison with the findings among the disease groups, a low cutoff point at 1:40 serum dilution (high sensitivity, low specificity) could have diagnostic value, since it would classify virtually all patients with SLE, SSc, or SS as ANA positive. Conversely, a high positive cutoff at 1:160 serum dilution (high specificity, low sensitivity) would be useful to confirm the presence of disease in only a portion of cases, but would be likely to exclude 95% of normal individuals.

CONCLUSION

It is recommended that laboratories performing immunofluorescent ANA tests should report results at both the 1:40 and 1:160 dilutions, and should supply information on the percentage of normal individuals who are positive at these dilutions. A low-titer ANA is not necessarily insignificant and might depend on at least 4 specific factors. ANA assays can be a useful discriminant in recognizing certain disease conditions, but can create misunderstanding when the limitations are not fully appreciated.

A family exhibiting heteroplasmy in the human mitochondrial DNA control region reveals both somatic mosaicism and pronounced segregation of mitotypes

A family exhibiting heteroplasmy at position 16355 in hypervariable region I of the human mtDNA control region has been identified. This family consists of a mother, daughter, and son. DNA samples extracted from blood stains, buccal swabs, and hairs from these individuals were amplified by PCR and sequenced utilizing fluoresence-labeled dye terminator chemistry in an automated DNA sequencer. In both the daughter and mother, heteroplasmy was observed in DNA extracted from blood stains, buccal swabs, and hairs. In the blood stains, the proportion of cytosine was greater than thymine in both individuals. Buccal swab extracts showed a more balanced contribution from the two nucleotides. Telogenic hair root and hair shaft samples exhibited a wide range of nucleotide contributions at this position, from predominately cytosine in some samples to predominately thymine in others. The apparent stochastic segregation of mitotypes in hair samples is discussed from a forensic viewpoint, and the mechanism of mtDNA heteroplasmy is considered.

The effect of maternal protein deficiency during pregnancy and lactation on glucose tolerance and pancreatic islet function in adult rat offspring

To test the hypothesis that poor foetal-neonatal nutrition predisposes adult animals to impaired glucose tolerance or diabetes, pregnant and lactating rats were fed a low (5%) protein diet and glucose tolerance and pancreatic islet function then assessed in the adult offspring. To expose any underlying defects the offspring were allowed access to a sucrose supplement (35%) or fed a high fat diet. Offspring born to low protein-fed females had significantly lower body weights than controls. In islets from previously malnourished rats, insulin release in batch incubations or perifusion was not significantly different to controls. In islets from previously malnourished animals fed sucrose, glucose-stimulated insulin release was reduced in perifusion by 66% (P < 0.01) and batch incubations by 26-52% (6-16 mmol/l glucose, P < 0.01). Similarly, impaired secretory responses were found in islets from previously malnourished animals fed a high fat diet. These did not result from a reduced pool of releasable insulin, as arginine-stimulated secretion was not impaired. Rats previously malnourished showed a normal glucose tolerance. Glucose tolerance was impaired, however, in previously malnourished rats fed sucrose (area under the glucose tolerance test curve was increased by 42%, P < 0.05) but despite the reduced islet secretory responses was not significantly different to sucrose-fed controls (area increased by 54%, P < 0.05). Glucose tolerance was impaired in previously malnourished animals fed high fat diet (area increased by 48%, P < 0.05) more so than in high fat fed-controls (28% increase, NS). These data support the hypothesis that poor foetal-neonatal nutrition leads to impaired pancreatic beta-cell function which persists into adult life. Alone this is not sufficient to produce diabetes, but an inability to respond to a highly palatable fat diet may tip the balance towards impaired glucose tolerance.

Influence of glaucomatous visual field loss on health-related quality of life

We examined the influence of glaucomatous visual field defects on vision-targeted and generic health-related quality of life. Vision-targeted and generic health status were assessed across 5 glaucoma treatment categories and a normal reference group from 5 tertiary care ophthalmology practices during regularly scheduled eye care visits. The sample consisted of 147 patients who were members of specific glaucoma treatment categories and 44 reference group patients. For patients with glaucoma, eligibility included a diagnosis of glaucoma at least 1 year prior to enrollment and no evidence of other eye disease. Participants completed 2 vision-targeted surveys, the National Eye Institute Visual Functioning Questionnaire and the VF-14, and a generic health-related quality of life measure, the Medical Outcomes Study 36-Item Short Form. Data from automated perimetry (Humphrey Field Analyzer 24-2, Humphrey Instruments, San Leandro, Calif) were used to generate Advanced Glaucoma Intervention Study scores for all participants. The Medical Outcomes Study 36-Item Short Form scores from glaucoma and reference group participants collected on a random half of the sample were similar. However, comparisons of the vision-targeted surveys demonstrated significant mean differences on 7 of 11 National Eye Institute Visual Functioning Questionnaire scales, and a trend toward significant differences for the VF-14 (P < .07 by linear regression). Greater visual field defects in the better eye were significantly associated with poorer National Eye Institute Visual Functioning Questionnaire scores (P < .05), as well as with worse VF-14 scores. These findings were most dramatic for patients with the most severe field loss in the better eye. Vision-targeted questionnaires were more sensitive than a generic health-related quality of life measure to differences between glaucoma and normal reference participants. Our findings indicate that self-reports of vision-targeted health-related quality of life are sensitive to visual field loss and may be useful in tandem with the clinical examination to fully understand outcomes of treatment for glaucoma.

Spanish population data on seven loci: D1S80, D17S5, HUMTH01, HUMVWA, ACTBP2, D21S11 and HLA-DQA1

Blood samples from 120 Spanish Caucasian individuals were amplified and typed by electrophoresis at six loci, and by reverse dot-blot hybridization at one locus. Results demonstrate the assumption of independence within and between the seven loci analyzed. Therefore, a Spanish population database has been established and statistical analysis shows that a high degree of discrimination can be obtained when all seven (or fewer) loci are used to characterize forensic biological evidence.

Protection of herpes simplex virus thymidine kinase-transduced cells from ganciclovir-mediated cytotoxicity by bystander cells: the Good Samaritan effect

Although considerable attention has been directed in the field of gene therapy toward elucidating the mechanism by which a transduced cell could kill a bystander cell, little is known about how bystander cells may affect transduced cells. We hypothesized that bystander cells, particularly if they were capable of gap junctional communication, could protect cells transduced with the herpes simplex virus thymidine kinase (HSV-TK) from ganciclovir (GCV)-induced cytotoxicity. To test this hypothesis, we used a rat hepatocyte cell line (WB) that can carry out efficient gap junctional communication, a WB clone transduced with HSV-TK (WB-TK), and a communication-incompetent subclone of WB cells (aB1). We cocultured WB-TK cells with either WB or aB1 cells, treated them with GCV, and then plated the cells into selective media that permitted us to quantify independently the surviving fraction of WB-TK cells or bystander cells. We found that WB bystander cells conferred up to a 1000-fold protection on WB-TK cells treated with GCV. aB1 cells conferred detectable, but significantly less, protection. These findings demonstrate that herpes simplex virus thymidine kinase-transduced cells can be significantly protected by bystander cells, particularly those that can carry out gap junctional communication. Whether this "Good Samaritan" effect improves the overall efficacy of gene therapy, by prolonging the survival of the source of toxic metabolites, or decreases effectiveness by increasing the survival of transduced cells will need to be determined in vivo.

A high observed substitution rate in the human mitochondrial DNA control region

The rate and pattern of sequence substitutions in the mitochondrial DNA (mtDNA) control region (CR) is of central importance to studies of human evolution and to forensic identity testing. Here, we report a direct measurement of the intergenerational substitution rate in the human CR. We compared DNA sequences of two CR hypervariable segments from close maternal relatives, from 134 independent mtDNA lineages spanning 327 generational events. Ten substitutions were observed, resulting in an empirical rate of 1/33 generations, or 2.5/site/Myr. This is roughly twenty-fold higher than estimates derived from phylogenetic analyses. This disparity cannot be accounted for simply by substitutions at mutational hot spots, suggesting additional factors that produce the discrepancy between very near-term and long-term apparent rates of sequence divergence. The data also indicate that extremely rapid segregation of CR sequence variants between generations is common in humans, with a very small mtDNA bottleneck. These results have implications for forensic applications and studies of human evolution.

Initial clinical experience with the Ahmed Glaucoma Valve implant in pediatric patients

OBJECTIVE

To evaluate the Ahmed Glaucoma Valve implant, an aqueous shunting device with a unidirectional valve mechanism, in patients younger than 18 years.

DESIGN

Prospective case series.

SETTING

Tertiary care hospital.

PATIENTS

Twenty-one consecutive patients younger than 18 years. The median age of patients was 4.8 years (range, 0.23-17.9 years)

INTERVENTION

Placement of an Ahmed Glaucoma Valve implant between April 1992 and April 1994.

MAIN OUTCOME MEASURE

Time after surgery without failure. Success was defined as an average intraocular pressure less than 22 mm Hg for the last 2 follow-ups in eyes with preoperative intraocular pressure greater than 22 mm Hg, or an intraocular pressure that was lowered by at least 20% from preoperative values in eyes with preoperative intraocular pressure less than 22 mm Hg, and no additional glaucoma surgeries or visually devastating complications.

RESULTS

Cumulative probabilities of success at 12 and 24 months were 77.9% +/- 8.8% and 60.6% +/- 13.7%, respectively. One eye had a flat anterior chamber and suprachoroidal hemorrhage on the first postoperative day. No other eyes had flat or shallow anterior chambers that required reformation. In 3 eyes the implant extruded from underneath the conjunctiva and was removed. In 2 other eyes the average intraocular pressure for the last 2 follow-ups was greater than 22 mm Hg. In 1 eye with an intraocular pressure less than 22 mm Hg preoperatively, the intraocular pressure was not reduced by at least 20%, although the number of antiglaucoma medications was reduced.

CONCLUSION

The 12-and 24-month success rates of the Ahmed Glaucoma Valve implant are similar to those of other implants when used in a pediatric population.

Melorheostosis

Melorheostosis is a rare, benign connective-tissue disorder characterized by a cortical thickening of bone with irregular dense hyperostosis that appears to flow along the cortex. We review the literature to date, etiology, clinical aspects, roentgenographic features, histology, and treatment of melorheostosis.

Clinical experience with the Ahmed Glaucoma Valve implant in eyes with prior or concurrent penetrating keratoplasties

PURPOSE

To evaluate the Ahmed Glaucoma Valve implant, an aqueous shunting device with a unidirectional valve mechanism, in eyes with concurrent or prior penetrating keratoplasties.

METHODS

Thirty-one eyes of 31 consecutive patients had placement of an Ahmed Glaucoma Valve implant. Median patient age was 65.1 years (range, 17.2 to 103.4 years). The main outcome measure was time after surgery without failure. Success was defined as no additional glaucoma surgeries or devastating visual complications, no new corneal graft failure, an intraocular pressure greater than or equal to 5 mm Hg on the last two follow-up examinations, and reduction in intraocular pressure. For eyes with preoperative intraocular pressure greater than 22 mm Hg, an average intraocular pressure of less than 22 mm Hg on the last two follow-up examinations was required. For eyes with preoperative intraocular pressure of less than 22 mm Hg, an intraocular pressure lowered by at least 20% from preoperative values was required.

RESULTS

Cumulative probabilities of success at 12 and 20 months (mean +/- SD) were 75.4% +/- 8.2% and 51.5% +/- 11.4%, respectively. Eleven of 31 eyes were failures. The risk of failure in eyes with prior infectious keratitis or keratouveitis was estimated to be 5.8 times greater than that associated with eyes that underwent penetrating keratoplasties for other reasons (P = .009).

CONCLUSIONS

Twelve- and 20-month success rates of the implant in eyes with prior or concurrent penetrating keratoplasties were comparable to those of other drainage devices. Eyes with prior infectious keratitis or keratouveitis were at increased risk of failure.

MHC class II B genes in the channel catfish (Ictalurus punctatus)

Two different cDNA sequences for major histocompatibility complex (MHC) class II beta chains from the channel catfish (Ictalurus punctatus) have been identified. Homology between these sequences and those previously identified as MHC class II B genes in other teleosts suggests they represent alleles of the DAB locus. The inferred amino acid sequences show strong evidence for a functional polypeptide chain with a peptide binding region. Southern blot analysis reveals polymorphism in the MHC class II B gene(s) of the channel catfish and suggests the presence of two to four genes.

Dexfenfluramine as an adjunct to a reduced-fat, ad libitum diet: effects on body composition, nutrient intake and cardiovascular risk factors

OBJECTIVE

To investigate the specific effects of dexfenfluramine (dF) as an adjunct to a reduced-fat, ad libitum diet.

DESIGN

Double-blind, randomized, placebo-controlled study. Subjects were stabilized on the dietary program during a 12 w run-in period, and then were randomized to receive dF (15 mg) or placebo bd for an additional 12 w. One follow-up was conducted 12 w after cessation of treatment.

SUBJECTS

84 obese subjects (57 F; 27 M, mean body mass index = 34.7 +/- 3.2 kg/m2).

MEASUREMENTS

Body composition (by DEXA), fat distribution (by circumferences and DEXA), nutrient intake (by 7 d food diaries), blood lipids, blood glucose and blood pressure.

RESULTS

Mild side effects were reported by 19 dF subjects, and in seven subjects lethargy or dry mouth persisted for the 12 w of treatment. Relative to placebo, treatment with dF was associated with significantly greater reductions in body weight (-3.8 kg, 95% confidence interval [CI] = -4.9, -2.7), fat mass (-2.5 kg, 95% CI = -3.6, -1.4) and fat-free mass (-1.2 kg, 95% CI = 1.8, -0.7). Waist and hip circumferences also decreased (P < 0.01) but the waist:hip ratio remained unchanged. The ratio of waist:hip fat mass as measured by DEXA decreased more in the dF group (P < 0.01). Lower total energy intake (-439 kJ/d, 95% CI = -932, 54) and fat intake (-5.1 g/d, 95% CI = -10.8, 0.6) were also seen but were of borderline statistical significance. After adjusting for changes in fat intake, dF treatment was associated with lower cholesterol and triglyceride concentrations (P < 0.01). Twelve weeks following cessation of treatment, the rate of weight gain was not significantly different between the dF and the placebo groups (1.7 kg and 0.7 kg respectively), but the dF group remained significantly lighter than the placebo group (P < 0.01).

CONCLUSIONS

Dexfenfluramine treatment augments weight and fat loss on a reduced-fat, ad libitum diet, with some evidence for preferential loss of waist fat compared with hip fat. The decreases in total energy and fat intake with dF seem insufficient to explain the significant decreases in body weight and fat mass.

Clusterin, a putative complement regulator, binds to the cell surface of Staphylococcus aureus clinical isolates

The ability of Staphylococcus aureus Cowan I strain and a number of S. aureus clinical isolates to bind to the human blood glycoprotein clusterin was investigated. Binding of clusterin to these strains was tested by both enzyme-linked immunosorbent assay and flow cytometry. All of the S. aureus strains examined appeared to bind clusterin to some extent, while nonpathogenic control strains Bacillus subtilis BR151 and Escherichia coli JM109 did not. Three S. aureus isolates were selected for more detailed study; binding of labeled clusterin was saturable, inhibited in the presence of excess unlabeled clusterin, and prevented by pretreatment of bacteria with proteases. From the saturation binding studies, estimates of the affinity constants for the binding of clusterin to the bacteria ranged from 31 to 57 nM. Addition of clusterin to S. aureus cultures was also found to result in aggregation of the bacterial cells; aggregation was not detected when clusterin was added to B. subtilis BR151 or E. coli JM109 cultures. These results suggest that at least some S. aureus strains possess specific proteinaceous receptors for clusterin. Such receptors may be an important new bacterial virulence determinant for S. aureus, as clusterin has been proposed to have a role in the regulation of complement activity.

Membrane immunoglobulin-associated molecules on channel catfish B lymphocytes

Membrane immunoglobulin (mIgM) on the surface of channel catfish B lymphocytes is non-covalently associated with 64 and 70 kDa molecules which are composed of covalent 32 kDa dimers and covalent 45/25 kDa subunits, respectively. Cross-linking of mIgM on catfish B cells leads to rapid phosphorylation of tyrosine residues in these presumed accessory as well as numerous other cytoplasmic molecules. These data indicate that fish likely use a signal transduction system containing elements similar to those of mammalian B cells.

Selection of highly metastatic variants of different human prostatic carcinomas using orthotopic implantation in nude mice

The purpose of this study was to determine whether the implantation of human prostate cancer cells into the prostates of nude mice and their subsequent growth there can be used to select variants with increasing metastatic potential. PC-3M and LNCaP cells were injected into the prostates of athymic mice. Tumors from the prostate or lymph nodes were harvested, and cells were reinjected into the prostate. This cycle was repeated three to five times to yield cell lines PC-3M-Pro4, PC-3M-LN4, LNCaP-Pro3-5, and LNCaP-LN3-4. Parental and variant cells were injected into the prostates of nude mice. PC-3M-LN4 cells produced enhanced regional lymph node and distant organ metastasis as compared to PC-3M-Pro4 or PC-3M cells. After i.v. or intracardiac inoculation, PC-3M-LN4 cells produced a higher incidence of lung metastasis and bone metastasis, respectively, than PC-3M or PC-3M-Pro4 cells. Subsequent to implantation into the prostate, LNCaP-LN3 cells produced a higher incidence of regional lymph node metastases than LNCaP-Pro5 or LNCaP cells. After intrasplenic implantation, LNCaP-LN3 cells also yielded experimental liver metastases. The metastatic LNCaP-LN3 cells exhibited clonal karyotypic abnormalities, were less sensitive to androgen (in vitro and in vivo), and produced high levels of prostate-specific antigen. Collectively, the data show that the orthotopic implantation of human prostate cancer cell lines in nude mice is a relevant model with which to study the biology of prostate cancer metastasis and to select variant cell lines with enhanced metastatic potential.

Demographic factors in a population-based survey of hospitalized, work-related, ocular injury

PURPOSE

To obtain population-based estimates of the incidence of severe work-related ocular trauma and to identify demographic factors related to increased risk of this type of injury.

METHODS

A statewide population-based survey of severe work-related ocular injury was performed using hospital discharge data. These data were derived from all inpatient admissions to nonfederal, acute-care hospital facilities in the state of California during 1988. Worker's compensation was used as the principal payor code to establish the work-relatedness of a given ocular injury. Census data for the state of California were used to obtain population denominators.

RESULTS

Two hundred sixty-nine (approximately 14.3%) of all admissions for which ocular trauma was the principal diagnosis (1,876) were work related. Annual incidence for severe work-related ocular injury was 1.76 per 100,000 employed persons when ocular trauma was the principal diagnosis and 2.98 per 100,000 employed persons when ocular trauma was a principal or secondary diagnosis. Projected to the working-age United States population (128 million) these annual rates correspond to an estimated 2,165 acute hospitalizations for work-related ocular trauma as the principal diagnosis, and an estimated 3,745 acute hospitalizations for work-related ocular trauma as a principal or secondary diagnosis. Incidence of severe work-related ocular injury was highest among men, Hispanics, and individuals 20 to 24 years of age (5.02, 3.72, and 4.64 per 100,000 employed per year, respectively).

CONCLUSIONS

The workplace accounts for a substantial proportion of severe ocular injury. Demographic groups at highest risk for this type of injury are men, Hispanics, and young adults.

Epithelial cell-derived transforming growth factor-beta in bleomycin-induced pulmonary injury

We have investigated whether enhanced secretion of transforming growth factor-beta (TGF-beta) by distal respiratory epithelial cells was associated with the development of bleomycin-induced pulmonary fibrosis. Type 2 pneumocyte-enriched preparations of bronchioloalveolar epithelial cells from normal mouse lung tissue released latent TGF-beta when cultured in serum-free medium. TGF-beta in culture supernatants could be detected using a sensitive enzyme immunoassay which employed enzyme complex amplification as a reporter system, as well as by a radiolabelled receptor competition assay. Exposure to bleomycin and other potentially fibrogenic stimuli in vitro did not stimulate production of TGF-beta by the epithelial cells but release was enhanced by treatment of the cells with interferon-gamma. Type 2 pneumocyte-enriched cell preparations obtained following induction of a pulmonary inflammatory response by administration of intratracheal bleomycin to susceptible C57BL/6 mice did not demonstrate increased release of TGF-beta in culture. However, the concentration of TGF-beta in bronchoalveolar lavage (BAL) fluids was significantly elevated compared to controls at 1 and 2 weeks after bleomycin-induced injury in these mice. No such increase was detected in BAL fluids from BALB/c mice, which are resistant to the effects of bleomycin. These results provide no support for a pathogenetic role of alveolar epithelial cell-derived TGF-beta in bleomycin-induced pulmonary fibrosis. Nevertheless, elevated levels of TGF-beta in BAL fluids may provide a marker of the progression of pulmonary injury to fibrosis.

A population-based study of xerophthalmia in the extreme North Province of Cameroon, West Africa

OBJECTIVE

To obtain cross-sectional data on clinical and nutritional vitamin A deficiency from which to design appropriate intervention strategies.

DESIGN

A population-based survey using multistage, cluster sampling.

SETTING

Extreme North Province of Cameroon, West Africa.

PARTICIPANTS

Children aged 0 to 5 years.

MAIN OUTCOME MEASURES

Clinical signs of active xerophthalmia and dietary vitamin A intake.

RESULTS

Of 5352 children examined, signs of active xerophthalmia were noted in 0.62%. Bitot's spots, corneal xerosis, and corneal ulceration were noted in 0.47%, 0.06%, and 0.12% of the subjects, respectively. Children with xerophthalmia had lower vitamin A intake scores when compared with age-matched controls and with a 20% systematic subsample of children.

CONCLUSION

Xerophthalmia is a major public health problem in this region.

Translating research into practice: controlled clinical trials and their influence on glaucoma management

Historically, management strategies for glaucoma have stressed reduction of IOP as the primary goal. Yet, if we question this principle, we find a deficiency of information to support it as the optimal strategy for managing glaucoma patients and those at risk of developing glaucoma. Thus, the practice of lowering IOP in glaucoma management was placed on trial by the 1987 Eddy and Billings report (D. M. Eddy and J. Billings, 1987). Although generally denounced by clinicians, this report nonetheless alerted the ophthalmologic community that success of glaucoma treatment must be measured by endpoints unrelated to IOP and that a controlled trial to demonstrate glaucoma treatment efficacy was necessary. A clinical trial is an experiment. As such, it is the best study design for inferring causality between an exposure (e.g., IOP) and an outcome (e.g., glaucoma), and it is the best methodology for demonstrating treatment efficacy. However, it is important to understand that efficacy is not the same as effectiveness. Whereas "efficacy" is the extent to which a specific intervention produces a beneficial result under ideal conditions, "effectiveness" is the extent to which a specific intervention, when deployed in the field, does what it is intended to do. The influence of study results on the practice of medicine is more a function of demonstrated effectiveness than efficacy of an intervention. All of the completed glaucoma clinica trials reviewed were well performed, and many have had a substantial influence on the philosophy and practice of glaucoma management. The glaucoma clinical trials currently being performed represent the highest standards of clinical trial methodology. This is an exciting time for clinical research on glaucoma. Well accepted dogmas are being challenged, and the ophthalmic community is aggressively addressing difficult issues. Questions being asked are of fundamental importance and addressing them is essential. Particularly exciting in these trials is the fact that IOP is not being considered as an endpoint and that consideration is being given to the previously ignored but extremely important issue of overall patient well-being. Only with time will the ultimate impact of these trials on the philosophy and practice of glaucoma management become evident.

Prevalence and causes of low vision and blindness in the Extreme North Province of Cameroon, West Africa

A survey to determine the prevalence and causes of blindness and visual impairment in the Extreme North Province of Cameroon was conducted in the Spring of 1992. A total of 10,647 people age 6 years and older was selected from a multi-stage, clustered sample stratified by ecological zone. The subjects were examined by ophthalmologist-led teams for visual acuity and ocular diseases. Approximately 1.2% of the sample was bilaterally blind by the World Health Organization classification (Category 3) of vision less than the ability to count fingers at 3 meters. Similarly to results found in other developing countries, senile cataract was the most common diagnosis encountered and the most frequent principal cause of low vision and blindness.

Inhibition of gap junctional intercellular communication in normal human breast epithelial cells after treatment with pesticides, PCBs, and PBBs, alone or in mixtures

Chemical pollutants in the Great Lakes have found their way through the food chain into humans because of their environmental persistence and lipophilicity. Some epidemiological studies have claimed an association between metabolites of 2,2-bis(p-chlorophenyl)-1,1,1-trichloroethane (DDT), polychlorinated biphenyls (PCBs), and polybrominated biphenyls (PBBs) and breast cancer, but others have reported no such association. We examined various halogenated hydrocarbons for their capacity to inhibit gap junctional intercellular communication (GJIC) in normal human breast epithelial cells (HBEC) when given as single compounds or as mixtures. The scrape-loading/dye transfer and fluorescent redistribution after photobleaching techniques were used to measure GJIC; immunostaining and Western and Northern analyses were performed on connexin 43 (Cx43) gap junction protein and message to determine how halogenated hydrocarbons might affect GJIC. DDT, dieldrin, and toxaphene inhibited GJIC in a dose-responsive manner after 90 min treatments. Dieldrin suppressed GJIC within 30 min with no recovery after 24 hr. Inhibition of GJIC by DDT and toxaphene was partially restored after 12 hr and fully restored after 24 hr. Several PCB and PBB congeners inhibited GJIC in a dose-responsive and time-dependent manner, but GJIC was almost restored to control values 24 hr after exposure. The highest concentrations of the individual chemicals that did not inhibit GJIC was determined, and mixtures containing two of these chemicals were tested for their ability to inhibit GJIC. Significant inhibition of GJIC was observed when cells were treated with a mixture of DDT and 2,4,5-hexachlorobiphenyl (2,4,5-HCB), dieldrin and 2,4,5-HCB, or dieldrin and 2,4,5-hexabromobiphenyl (2,4,5-HBB). These results indicate that halogenated hydrocarbons, alone or in specific combinations, can alter GJIC at the post-translational level. These results are consistent with the hypothesis that DDT, dieldrin, toxaphene, 2,3,4-HCB, 2,4,5-HCB, and 2,4,5-HBB could have tumor-promoting potential in human breast tissue.