Heavy Traffic Ahead: Car Culture Accelerates

As the world’s largest nation, China is drawing a lot of attention for its increased motorization rates. Although China’s rate of automobile ownership is low by the standards of the developed world, it is increasing at a very fast rate. Between the late 1970s and 2001, China’s overall fleet of motor vehicles other than two-wheelers increased 10-fold, according to an article in the 3 December 2003 issue of Energy for Sustainable Development. 
 
Along the way, the Chinese government decided it wanted to develop its own auto industry. In 2001 China identified auto manufacturing as one of seven “pillar industries” of the Chinese economy and announced a five-year plan to implement a primarily domestic industry that could offer a Chinese family car at a price that would encourage widespread ownership. Between 2000 and 2004, production of passenger cars in China jumped from 605,000 to 2.33 million. On 5 February 2005, the China Federation of Machinery Industry, an industry association, forecast 20% growth for 2005 to a level that would move China past Germany into third place globally for motor vehicle production. Most industry analysts believe that the industry will continue to expand in the 15% range annually for years to come. The government has also encouraged private investments in highways to fuel a highway-building program that was already well under way. In October 2004, China’s Ministry of Communication announced that the nation’s freeways had reached 30,000 kilometers, placing it behind only the United States. Up till now, a large portion of these roads had been toll roads. 
 
China may be getting the lion’s share of the attention, but people who follow international transportation issues say the trend in motorization is global. According to Daniel Sperling, a professor of engineering and environmental science and policy at the University of California, Davis, and director of its Institute of Transportation Studies, motorization is soaring everywhere, with the fastest growth occurring in Asia and Latin America. He says that the number of motor vehicles other than two-wheelers in the world is expected to double in the next 15 years to 1.3 billion. 
 
“The reason motorization is spreading so rapidly is that people value mobility,” Sperling says. “But it’s also happening because a lot of regions are growing economically. We use the rule of thumb that motorization takes off when per capita incomes reach about $5,000. And many parts of the world—many cities in China, for instance—have reached that level.” 
 
Michael P. Walsh, a transportation and environmental consultant to governments in China and other developing countries, and author of the Energy for Sustainable Development article, believes there’s another explanation. “Everybody, it seems to me, wants to follow the American model,” he says. “We’re held up as the country to emulate. It’s an image that people have. If you’re a modern country, you need to have lots of privately owned motor vehicles.” 
 
Nobody doubts that there are benefits to increased mobility. But as Walsh points out, increasing numbers of automobiles and other motor vehicles in developing countries will result in deteriorating air quality, greater congestion, and poorer quality of life. It also means greater energy consumption—and for an enormously populated nation like China, which is moving rapidly and steadily toward a position of international power, the implications of growing reliance on foreign oil sources can’t be ignored.


Background
Age-related Macular Degeneration (AMD) is a progressive disorder associated with central vision loss and is the leading cause of visual impairment and blindness in people over the age of 60. More than 15 million Americans over the age of 60 have AMD with an additional 50 million Americans at risk for developing the disorder [1]. Dry, atrophic, or non-exudative, AMD is the most common form and is characterized by progressive devitalization of retinal pigment epithelium (RPE) and the formation of fatty deposits under the RPE known as soft drusen [1]. Although the underlying cause of AMD is unknown, risk factors have been defined and include age greater than 50, Caucasian race, nutrition, smoking, atherosclerotic vascu-lar disease, genetics, and sunlight exposure [1][2][3][4]. At this time, there is no known cure for AMD. Patients not receiving treatment have demonstrated a loss of VA at 6 months of at least 0.8 lines and up to 1.5 lines [5][6][7].
Multiple studies have suggested that manipulation of nutritional factors can play a significant role in slowing the onset or limiting the effects of AMD [8][9][10][11][12][13]. In 1996, Richer et al found that a broad-spectrum antioxidant and mineral supplement was effective in delaying AMDrelated vision loss, but was unable to reverse existing vision loss [14,15]. The Age-Related Eye Disease Study (AREDS), sponsored by the National Eye Institute, demonstrated that high levels of antioxidants and zinc were able to reduced the risk of development of advanced AMD by approximately 25% [16]. In 2004, the Lutein Antioxidant Supplementation Trial (LAST) demonstrated that nutritional supplementation with lutein or lutein together with antioxidants, vitamins, and minerals improved visual function and symptoms in patients with atrophic agerelated macular degeneration [13].
Nutritional supplements have become the first line of defense for clinicians in battling dry AMD. Vitamin and mineral formulations are a valid therapeutic tool and are many orders of magnitude less toxic than aspirin and acetaminophen [17].
The Taurine, Omega-3 Fatty Acids, Zinc, Antioxidant, Lutein (TOZAL) study sought to identify the potential benefits of a novel supplement designed to limit the risk of AMD and progressive vision loss while also reducing or eliminating the risk of adverse events.

Methods
This study was approved by an independent ethics committee and an independent review board and was conducted at five independent clinical sites. The study was conducted from 2004 through 2005.
In 1998, Allen et al reported that patients with dry AMD treated with a combination of nutrients and microcurrent electricity showed slowing or reversing of the progress of AMD for most subjects [18].
The microcurrent in this study was self-administered by the patient, 2 treatments each day, using an automated microcurrent stimulator with a preset current of 800 micro-amps at frequency settings of 292 Hz (6 minutes), 30 Hz (3 minutes), 9.1 Hz (2 minutes), and 0.3 Hz (1 minute) for a total of 12 minutes. The sham device was identical to the treatment device, including LED indicators and audible tones; however, there was no electrical current output. Electrical current administered at levels below 1 milliamp (1,000 micro-amps) has no detectable sensation.
MCS treatment was found to have little significant effect on any of the efficacy endpoints and thus was abandoned. Only the nutritional supplement aspect of the study is reported and discussed here (ie, patients receiving sham MCS and nutritional supplement, n = 37).
Each subject was scheduled for 5 visits (Figure 1). During the first visit, subjects who met the inclusion and exclusion criteria (Table 1) and signed a consent to participate underwent a comprehensive eye examination including medical and ophthalmic history, refraction, BCVA measured by ETDRS (logMAR) at 4 m, biomicroscopy, intraocular lens evaluation, intraocular pressure, dilated fundus exam, fluorescein angiogram and retinal photographs, contrast sensitivity, full threshold visual fields, and macular testing (central 10° threshold visual filed). Additionally, each subject completed the Visual Function Questionanaire-25 (VFQ-25).
During the second visit at week 1, BCVA (logMAR) and contrast sensitivity were measured and the nutritional supplement was dispensed. The TOZAL nutritional supplement formulation used in this study is outlined in Table 2. This is a novel supplement formulation and is currently patent pending. Subjects were instructed to selfadminister the oral supplements at 2 capsules 3 times per day concurrent with food intake. Treatment compliance was assessed at each subsequent visit via a daily patient log.
During the third visit at week 2, BCVA (logMAR) and contrast sensitivity were measured.
During the fourth visit at week 11, BCVA (logMAR) and contrast sensitivity were measured. In addition, retinal photographs, fluorescein angiogram, macular testing, and full threshold visual fields were conducted.
The final and exit visit was at week 24 and was a repeat of the first visit in addition to a compliance assessment.

Objective Measures
The primary objective was to measure the change in BCVA from baseline to 6 months in subjects with non-exudative macular degeneration treated with a nutritional supplement. The secondary efficacy variable was objective signs of improved macular function.
The primary safety variables were unexpected ocular or systemic findings, adverse event rate, and temporary and permanent discontinuation. Investigators were required to report any treatment-related adverse events or serious non-treatment-related adverse events and severe adverse events requiring hospitalization.  • Subjects must not have conditions that limit the view to the fundus (eg vitreous hemorrhage, cataracts, an epiretinal membrane). All subjects with = 2+ nuclear opacities and/or significant central opacity (PSC or ASC) > 1+ will undergo Potential Acuity Meter (PAM) testing. If the vision is = 2 lines improved on PAM over standard acuity measurement then the subject will not be eligible for the trial • Subjects must be available for a minimum trial duration of approximately 6 months • Subjects must agree to take only the nutritional supplement that is provided during this study • Subjects or eyes must not meet any of the exclusion criteria Exclusion Criteria Any of the following excluded a subject from the trial: Adverse events included any undesirable clinical occurrence in a subject whether considered related to treatment or not. Serious adverse events included those in which information suggested that treatment caused or may have caused or contributed to death or serious injury including, but not limited to, permanent decrease in BCVA (≥ 2 lines) or hospitalization. Significant adverse events included those that required medical intervention or warranted discontinuation (temporary or permanent) from the clinical trial. These events were non-sight-threatening conditions that were determined to be device-related. Non-significant adverse events were events that did not warrant discontinuation from the clinical trial.
Subjects could discontinue or withdraw from the trial for any reason. Investigators could discontinue a subject if, in his/her opinion, it was in the best interest of the patient, if there was non-compliance with study visits, if there was more that 25% non-compliance with self-administration of treatment, or if there was protocol deviation.

Placebo Arm
The IRB for this study determined that standard of care for age-related macular degeneration must include an Age-Related Eye Disease Study (AREDS)-type nutritional supplement and that no true placebo arm would be permissible. A placebo arm was constructed from a review of the literature. The exclusion and inclusion criteria used for the Multicenter Investigation of Rheopheresis for AMD (MIRA-1) trial were followed for the TOZAL study. Patient demographics between subjects enrolled in the MIRA-1 study and the TOZAL study were similar. All subjects in the MIRA-1 study received an oral supplement consisting of 400 mg vitamin C, 200 IU vitamin E, 40 mg zinc, and 3,000 IU beta-carotene [7]. The results from the placebo arm of the MIRA-1 study are used as a comparator in this report.

Statistical Analysis
Sample size and power calculations were based on the primary efficacy endpoint. Results from two rheopheresis studies (Brunner and MIRA-1) were used to estimate the mean change expected [7,19]. Thirty-four patients were included in the per-protocol analysis.
Statistical analyses were performed using SPSS for Windows (SPSS 14.0, SPSS Inc., Chicago, IL). A paired t-test was used to test the null hypothesis, with the average VA score the same at baseline and follow-up. A two-sided alpha level of 0.05 was used to determine statistical significance.
Primary efficacy endpoint analysis consisted of all randomized and dispensed subjects with baseline and at least 1 post-treatment VA recorded. Baseline was equated to VA measured as visit 2 (week 1). Change from baseline was evaluated at weeks 11 and 24. Repeated measures mixed model (Proc Mixed, SAS, 8.2) was fitted to compare mean change in VA from baseline between the groups, with Visit and Treatment-by-Visit interaction included as main effects, baseline VA as covariate, and Eye as the withinpatient random effect.
A secondary analysis set was also constructed, comprised of 1 eye per patient meeting the 20/32-20/125 entrance VA criteria. If both the left and the right eye met the criteria, the "best" eye was used.
The safety analysis set consisted of all randomized subjects who received at least 1 dose of treatment. Incidence of unexpected ocular or systemic findings, adverse events, and temporary/permanent discontinuation were tabulated and evaluated using Fisher's exact test. All tests were carried out at α = 0.05, 2-sided.

Demographics and Baseline Characteristics
Demographics and baseline characteristics of the 37 patients receiving the nutritional supplement are outlined in Table 3. Subjects enrolled in the TOZAL study were matched for inclusion and exclusion criteria with the MIRA-1 study. Subjects in both cohorts were similar across age, gender, ethnicity, and mean baseline BCVA [7].

Visual Acuity Outcomes
In the per-protocol analysis, the mean change from baseline in ETDRS BCVA (logMAR) was calculated at 3 and 6 months ( Figure 2). While the placebo arm experienced a negative mean ETDRS line change of 1.49 lines at 6 months (loss of VA), the treatment group demonstrated a positive mean ETDRS line change of 0.54 lines at 6 months (gain in VA). The mean logMAR line difference between the treatment and placebo-control groups was 2.03 lines at 6 months postbaseline. A continual improvement in BCVA (logMAR) over time was demonstrated in the treatment group, while overall, the placebo arm continued to lose VA over time.

Secondary Outcomes
Fluorescein angiogram, retinal photographs, contrast sensitivity, full-threshold visual fields, macular testing (central 10° threshold visual field), and the Visual Function Questionanaire-25 (VFQ-25) were found to have little significant change at 6 months.

Statistical Analyses
The average (SD) VA score was 0.409 (0.196) versus 0.355 (0.184) for baseline and follow-up respectively, t = -2.09; df = 33; P = .045. Figure 4 demonstrates the average (and 95% confidence interval [CI] for the average) VA score at baseline and at follow-up. Tables 4 and 5 show a statistically significant increase in the VA score from baseline to follow-up. Thus, the null hypothesis, the average VA score is the same at baseline and follow-up, was rejected and it was concluded that there was a statistically significant improvement in VA from baseline to follow-up. Table 5 shows that the average increase in VA was 0.0541 and the 95% CI for the average increase was (-0.107, -0.0013).
A post-hoc power analysis reveals that a sample size of 34 achieves 80% power to detect a difference of 0.062 between the baseline and follow-up average acuity score assuming a standard deviation of the differences (followup minus baseline) of 0.126 and with a significance level (alpha) of 0.05 using a two-sided paired t-test. If the true population change (follow-up minus baseline) was -0.062 with a standard deviation of 0.126, then this study would have had an 80% chance of detecting this difference at the 0.05 level of significance.

Adverse Effects
There were no significant systemic or ocular adverse events related to the nutritional supplement. The most fre-quent events were systemic gastrointestinal (GI) reactions, including gastric upset, reflux, nausea, and taste perversion. The majority of these events occurred in patients who had not followed the prescribed procedure of taking the supplement concurrent food intake. After adjusting their treatment schedule to always administering the nutritional supplement with food, the majority of GI issues resolved. Overall, there does not appear to be any significant adverse events related to the nutritional supplement.

Visual Acuity
Left untreated, patients with AMD are at risk for substantial vision loss. The literature suggests that without intervention, patients with AMD will experience a loss in VA of at least 0.8 lines and up to 1.5 lines at 6 months [5][6][7].
The AREDS formula does not address the vast majority of patients who want to improve visual function while preventing advanced AMD. The targeted nutritional supple-ment prescribed in the TOZAL trial allowed for 76.7% of subjects to improve or maintain their VA, with up to 0.5 lines of VA improvement at 6 months.

Nutritional Supplements
Countless studies support the use of high-dose vitamins, antioxidants, omega-3 fatty acids, zinc, and carotenoids in the treatment of AMD. In addition, studies on the serum levels of compounds including vitamins A, C, and E, carotenoids, zinc, selenium, and fibroblast growth factor in subjects with AMD suggest that low levels of these compounds put patients at greater risk for the development of AMD [8][9][10][11][12][13]. However, recent reports of adverse events associated with specific supplement components emphasize the need for improved supplement formulation.  Results of several large studies suggest that supplemental beta-carotene increases the risk of developing lung cancer in heavy smokers [22][23][24]. Thus, it has been recommended that subjects with a history of smoking avoid supplemental beta-carotene as part of an AMD prevention program. However, an increased intake of foods rich in beta-carotene has not been found to pose a heightened risk for the development of lung cancer among current and non-smokers [25]. Other carotenoids derived from whole foods (lutein, zeaxanthin, and lycopene) are also not associated with increased risk for lung cancer [25].

Mean ETDRS line change at 3 and 6 months
The supplement prescribed in the TOZAL study was designed to address the risk of lung cancer among smokers receiving supplemental beta-carotene by focusing on beta-carotene derived from whole foods. The TOZAL supplement contained 18,640 IU of natural beta-carotene and 10,000 IU of vitamin A.
Recent data link high doses of vitamin E to a 13% increase in the risk for heart failure [26]. In addition, a separate study found that doses of 400 IU or more of vitamin E increased the chance of early death or, according to the [23,24] authors, "all-cause mortality" and should be avoided [27]. In an attempt to address these potential risk factors, the TOZAL supplement was designed with 200 IU vitamin E.
Supplemental zinc has been found to decrease the rate of loss of VA associated with AMD [16]. High doses of zinc were included in the AREDS supplement (80 mg as zinc oxide), as well as copper (2 mg) to help prevent copper deficiency associated with zinc supplementation. In the AREDS study, 7.5% of participants receiving a zinc-containing nutritional supplements vs 5.0% of participants receiving no zinc in their nutritional supplement reported urinary tract problems that required hospitalization, as well as increased rates of anemia (anemia results were found not to be statistically significant) [16]. In an effort to limit the adverse effects associated with high-dose zinc, the TOZAL supplement was designed with 69.6 mg zinc and 1.6 mg copper. No urinary tract adverse events or anemia were reported during the TOZAL trial.  Average (and 95% CI for average) visual acuity at baseline and at follow-up.
In 1998, van den Berg et al found that lutein negatively affected beta-carotene absorption when the two were given simultaneously [28]. This decrease in absorption may affect the amount of beta-carotene available for conversion to retinol. In the AREDS study, lutein was not a constituent of the formula, thereby circumventing the issue. As newer formulas are developed that contain lutein, consideration must be given to administering vitamin A in addition to beta-carotene. In the TOZAL study, this adjustment was made by administering 18,640 IU of natural beta-carotene and 10,000 IU of vitamin A.
While toxicity has occurred at dosages of vitamin A of up to 50,000 IU/day for a period of 18 to 24 months, [29][30][31][32] an intake of 10,000 IU/day has not been associated with toxicity and is considered safe.

Conclusion
The present study confirms previously published reports on the direction and magnitude of improved visual acuity in dry AMD [13,20,21]. That we did not find improvements in other visual function parameters such as the contrast sensitivity function, is likely related to the short duration of this study. The National Eye Institute's AREDS II trial will follow a qualitatively similar supplement (i.e., the AREDS II formula has lower zinc, higher omega-3, lutein and zeaxanthin in some of its treatment arms) as TOZAL (without the addition of taurine). The results of the TOZAL study reported here support the potential for positive visual outcomes in the AREDS II trial.
We can not completely dismiss microcurrent stimulation (with or without supplementation) as we did not evaluate all available methods of stimulation.
Treatment based on dietary manipulation should continue to be pursued and refined as a simple, low-cost, effective therapy for AMD.