Cannabis and Alcohol Use by U.S. Young Adults, 2008-2019: Changes in Prevalence After Recreational Cannabis Legalization

INTRODUCTION

Young adults' cannabis and alcohol use patterns have changed after state recreational cannabis legalization according to studies based on college samples but not nationally representative samples. Associations between recreational cannabis legalization and changes in cannabis and alcohol use outcomes among young adults were examined, including differences by college enrollment and minor status (ages 18-20 vs 21-23 years).

METHODS

Repeated cross-sectional data (2008-2019) were collected from college-eligible participants aged 18-23 years in the National Survey on Drug Use and Health. Self-reported past-month cannabis use and frequent use (≥20 days) and a proxy for past-year DSM-5 cannabis use disorder were primary outcomes; past-month frequent alcohol use and binge drinking were secondary outcomes. Multilevel logistic regression models quantified changes in outcome prevalence from the study years before to after recreational cannabis legalization, adjusting for secular trends. Analyses were conducted on March 22, 2022.

RESULTS

Prevalence increased from before to after recreational cannabis legalization for past-month cannabis use (from 21% to 25%) and past-year proxy cannabis use disorder (from 11% to 13%); the increases were statistically significant [adjusted odds ratio (95% CI) = 1.20 (1.08-1.32) and 1.14 (1.003-1.30), respectively]. Increases were detected for young adults who were not in college and who were aged 21-23 years. Recreational cannabis legalization impacts were not detected for secondary outcomes.

CONCLUSIONS

Some young adults appear sensitive to state recreational cannabis legalization, including in terms of cannabis use disorder risk. Additional prevention efforts should be directed to young adults who are not in college and timed to occur before age 21 years.

Causal Knowledge as a Prerequisite for Interrogating Bias: Reflections on Hernán et al. 20 Years Later

In their seminal 2002 paper, "Causal Knowledge as a Prerequisite for Confounding Evaluation: An Application to Birth Defects Epidemiology," Hernán et al. (Am J Epidemiol. 2002;155(2):176-184) emphasized the importance of using theory rather than data to guide confounding control, focusing on colliders as variables that share characteristics with confounders but whose control may actually introduce bias into analyses. In this commentary, we propose that the importance of this paper stems from the connection the authors made between nonexchangeability as the ultimate source of bias and structural representations of bias using directed acyclic graphs. This provided both a unified approach to conceptualizing bias and a means of distinguishing between different sources of bias, particularly confounding and selection bias. Drawing on examples from the paper, we also highlight unresolved questions about the relationship between collider bias, selection bias, and generalizability and argue that causal knowledge is a prerequisite not only for identifying confounders but also for developing any hypothesis about potential sources of bias.

Recreational cannabis legislation and binge drinking in U.S. adolescents and adults

BACKGROUND

Recreational cannabis laws (RCLs) may have spillover effects on binge drinking. Our aims were to investigate binge drinking time trends and the association between RCLs and changes in binge drinking in the United States (U.S.).

METHODS

We used restricted National Survey on Drug Use and Health data (2008-2019). We examined trends in the prevalence of past-month binge drinking by age groups (12-20, 21-30, 31-40, 41-50, 51+). Then, we compared model-based prevalences of past-month binge drinking before and after RCL by age group, using multi-level logistic regression with state random intercepts, an RCL by age group interaction term, and controlling for state alcohol policies.

RESULTS

Binge drinking declined overall from 2008 to 2019 among people aged 12-20 (17.54% to 11.08%), and those aged 21-30 (43.66% to 40.22%). However, binge drinking increased among people aged 31+ (ages 31-40: 28.11% to 33.34%, ages 41-50: 25.48% to 28.32%, ages 51+: 13.28% to 16.75%). When investigating model-based prevalences after versus before RCL, binge drinking decreased among people aged 12-20 (prevalence difference=-4.8%; adjusted odds ratio (aOR)=0.77, [95% confidence interval (CI) 0.70-0.85]), and increased among participants aged 31-40 (+1.7%; 1.09[1.01-1.26]), 41-50 (+2.5; 1.15[1.05-1.26]) and 51+ (+1.8%; 1.17[1.06-1.30]). No RCL-related changes were noted in respondents ages 21-30.

CONCLUSIONS

Implementation of RCLs was associated with increased past-month binge drinking in adults aged 31+ and decreased past-month binge drinking in those aged < 21. As the cannabis legislative landscape continues to change in the U.S., efforts to minimize harms related to binge drinking are critical.

Cannabis Recreational Legalization and Prevalence of Simultaneous Cannabis and Alcohol Use in the United States

BACKGROUND

Simultaneous cannabis/alcohol use, using both substances within a short time interval so that their effects overlap, has a greater risk of potential negative consequences than single-substance use and is more common in younger age. Relationships between recreational cannabis laws (RCLs) and changes in simultaneous cannabis/alcohol use prevalence remain untested.

OBJECTIVE

To examine trends in simultaneous cannabis/alcohol use from 2008 to 2019, and investigate associations between implementation of RCLs (i.e., presence of active legal dispensaries or legal home cultivation) and simultaneous cannabis/alcohol use in the United States (U.S.).

DESIGN

Repeated cross-sectional samples from the 2008-2019 U.S. National Survey on Drug Use and Health (NSDUH).

PARTICIPANTS

Respondents (51% female) aged 12 and older.

INTERVENTIONS

Changes in simultaneous cannabis/alcohol use before and after RCL implementation (controlling for medical cannabis law implementation) were compared in different age groups (12-20, 21-30, 31-40, 41-50, 51+), using adjusted multi-level logistic regression with state random intercepts and an RCL/age group interaction.

MEASUREMENTS

Self-reported simultaneous cannabis/alcohol use.

RESULTS

From 2008 to 2019, the overall prevalence of simultaneous cannabis/alcohol use declined among those aged 12-20 but increased in adults aged 21+. Model-based simultaneous cannabis/alcohol use prevalence increased after RCL implementation among respondents aged 21-30 years (+1.2%; aOR= 1.15 [95%CI = 1.04-1.27]), 31-40 years (+1.0; 1.15 [1.04-1.27]), and 41-50 years (+1.75; 1.63 [1.34-1.98]), but not in individuals aged <21 or 51+ years.

CONCLUSIONS

Implementation of recreational cannabis policies resulted in increased simultaneous use of cannabis and alcohol, supporting the complementarity hypothesis, but only among adults aged 21+. Efforts to minimize harms related to simultaneous cannabis/alcohol use are critical, especially in states with RCLs. Future studies should investigate cultural norms, perceived harm, and motives related to simultaneous use.

Prescription Drug Monitoring and Child Maltreatment in the United States, 2004-2018

OBJECTIVE

To test whether a policy approach aimed at decreasing prescription drug misuse, specifically, state monitoring of controlled substance prescriptions-prescription drug monitoring programs (PDMPs)-were associated with changes in Child Protective Services-reported maltreatment prevalence.

STUDY DESIGN

Using a difference-in-differences design and maltreatment data (2004-2018) from 50 states and the District of Columbia, we compared the prevalence of total maltreatment incidents and total victims, in states with and without PDMPs, before and after implementation. Exploratory analyses further examined models disaggregated by maltreatment type (neglect, physical abuse, sexual abuse, psychological abuse) and among different racial/ethnic groups. Quasi-Poisson models included state-level covariates, state- and year-fixed effects, and cluster-robust standard errors.

RESULTS

Difference-in-differences models identified greater relative reductions in PDMP states relative to controls (total prevalence ratio, 0.87; 95% CI, 0.80, 0.940; victimization prevalence ratio, 0.92; 95% CI, 0.85-0.98) over the observation period. Decreases seemed to be driven by changes in neglect (prevalence ratio, 0.87; 95% CI, 0.80-0.93) and physical abuse (prevalence ratio, 0.78; 95% CI, 0.71-0.87) incidents, and may have been especially salient for American Indian/Alaskan Native children (prevalence ratio, 0.78; 95% CI, 0.65-0.94).

CONCLUSIONS

We found evidence supporting an association between prescription drug monitoring and reduced maltreatment prevalence at the state level. Policies aimed at restricting the prescribing and dispensing of controlled substances may have indirect implications for child welfare.

Perceptions of peer and parental attitudes toward substance use and actual adolescent substance use: The impact of adolescent-confidant relationships

Objective: While peer influence is a well-documented risk factor for adolescent substance use, it remains unclear whether peer or parental attitudes have greater impact, and if this relationship is moderated by having a confidant and the relationship between adolescents and their confidant. Method: Pooled (2015-2018) National Survey on Drug Use and Health (NSDUH) data on adolescents (12-17 years) were used. Perceived peer and parental disapproval of tobacco, alcohol, and marijuana use were dichotomized. We assessed associations between disapproval and past-month tobacco (N = 51,352), alcohol (N = 51,407), and marijuana use (N = 51,355) using separate multivariable logistic regression models. We explored effect modification by the presence of a confidant, parental vs. non-parental disapproval, and peer vs. non-peer confidant relationship. Results: Peer and parental disapproval, presence of any confidant, and identifying a parental confidant were consistently protective against substance use; identifying a peer confidant increased odds of use across substances. For marijuana use, peer disapproval (adjusted odds ratio [aOR]: 0.07, 95% confidence interval [CI]: 0.06, 0.08) was more protective than parental disapproval (aOR: 0.13, 95% CI: 0.12, 0.15). The joint presence of peer/parental disapproval and any confidant decreased the odds of substance use beyond the individual effects of peer/parental disapproval and having a confidant. However, having a peer confidant attenuated the protective association between peer/parental disapproval and tobacco, alcohol, and marijuana use. Conclusions: Both peer and parental relationships are salient when considering the social context of adolescent substance use and should be considered when studying the effects of perceived disapproval.

Cannabis use outcomes by past-month binge drinking status in the general United States population

Cannabis use and binge drinking are increasingly common in the United States, yet little is known about cannabis use patterns among people who engage in binge drinking. This study explored the relationship between several cannabis use outcomes and past-month binge drinking status. Pooled 2015-2018 National Surveys on Drug Use and Health data (N = 226,632) were used to explore the hypothesis that binge drinking is associated with higher prevalence of cannabis outcomes. Cannabis outcomes included past-month and past-year use, daily/almost daily use, and past-year DSM-IV/DSM-5 cannabis use disorder (CUD). Covariates included age, gender, race, total income, and study year. Separate weighted multivariable logistic regressions assessed associations between binge drinking and each cannabis outcome and provided adjusted prevalences of cannabis outcomes by binge drinking status. Past-month binge drinking was positively associated with past-month (OR: 3.72, 95 %CI: 3.56-3.93) and past-year (OR: 3.90, 95 %CI: 3.74-4.06) cannabis use in adjusted regressions. The adjusted odds of DSM-IV and DSM-5 CUD among people who used cannabis were 15 % and 12 % higher among people who engaged in binge drinking than those who did not, respectively (OR: 1.15, 95 %CI: 1.05, 1.26 and OR: 1.12, 95 %CI: 1.03, 1.21). Conversely, the odds of past-month daily cannabis use among people who used cannabis and reported binge drinking was 18 % lower than those who did not (OR: 0.82, 95 %CI: 0.74, 0.91). Our findings provide evidence of associations between binge drinking and cannabis use. Future studies should explore associations between cannabis and other alcohol use behaviors, including heavy drinking, and simultaneous alcohol and cannabis use.

Joint perceptions of the risk and availability of Cannabis in the United States, 2002-2018

BACKGROUND

Prior work suggests that perceived risk and perceived availability of cannabis independently affect cannabis use. However, perceived risk likely modifies the effect of perceived availability, and vice versa. This study explored trends in joint perceived risk and availability of cannabis from 2002 to 2018 and the relationship between combined perceptions and cannabis use, frequent use, and cannabis use disorder (CUD).

METHODS

National Surveys on Drug Use and Health data (n = 949,285, ages 12+) were used to create combined categories of perceived risk of weekly cannabis use and perceived cannabis availability. Descriptive analyses compared joint perceived risk/availability trends (pre/post-2015 due to survey redesign) overall and stratified by age, gender, past-year cannabis use, frequent use, and CUD. Regression analysis estimated associations between perceived risk/availability and cannabis outcomes.

RESULTS

From 2002 to 2018, the prevalence of perceiving cannabis as low-risk doubled while perceiving cannabis as available remained unchanged. The proportion of individuals perceiving cannabis as Low-risk/Available increased by 86% from 2002 to 2014 (16.8%-31.2%) and 19% from 2015 to 2018 (30.1%-35.8%) while High-risk/Available and High-risk/Unavailable proportions declined. Differing patterns were observed by age and gender. Compared with individuals perceiving cannabis as High-risk/Unavailable, people in all other perception categories had greater risk of all cannabis outcomes. Results were consistent with additive interaction between perceived risk and availability in their effects on cannabis use.

CONCLUSIONS

Trends and associations with cannabis outcomes differ when considering perceived risk and availability independently versus jointly. Longitudinal studies and cannabis policy evaluations would advance understanding of links between cannabis perceptions and use.

Racial and Ethnic Differences in Cannabis Use Following Legalization in US States With Medical Cannabis Laws

IMPORTANCE

Little is known about changes in cannabis use outcomes by race and ethnicity following the enactment of recreational cannabis laws (RCLs).

OBJECTIVES

To examine the association between enactment of state RCLs and changes in cannabis outcomes by race and ethnicity overall and by age groups in the US.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional study used restricted use file data from the National Surveys of Drug Use and Health between 2008 and 2017, which were analyzed between September 2019 and March 2020. National survey data included the entire US population older than 12 years.

MAIN OUTCOMES AND MEASURES

Self-reported past-year and past-month cannabis use and, among people that used cannabis, daily past-month cannabis use and past-year Diagnostic and Statistical Manual of Mental Disorders (Fifth Edition) cannabis use disorder. Multi-level logistic regressions were fit to estimates changes in cannabis use outcomes by race and ethnicity overall and by age between respondents in states with and without enacted RCLs, controlling for trends in states with medical cannabis laws or no cannabis laws.

RESULTS

A total of 838 600 participants were included for analysis (mean age, 43 years [range, 12-105 years]; 434 900 women [weighted percentage, 51.5%]; 511 900 participants (weighted percentage, 64.6%) identified as non-Hispanic White, 99 000 (11.9%) as non-Hispanic Black, 78 400 (15.8%) as Hispanic, and 149 200 (7.6%) as other (including either Native American, Pacific Islander, Asian, or more than 1 race or ethnicity). Compared with the period before RCL enactment, the odds of past-year cannabis use after RCL enactment increased among Hispanic (adjusted odds ratio [aOR], 1.33; 95% CI, 1.15-1.52), other (aOR, 1.31; 95% CI, 1.12-1.52), and non-Hispanic White (aOR, 1.21; 95% CI, 1.12-1.31) populations, particularly among those aged 21 years or more. Similarly, the odds of past-month cannabis use increased among Hispanic (aOR, 1.43; 95% CI, 1.22-1.69), other (aOR, 1.43; 95% CI, 1.20-1.70), and non-Hispanic White (aOR, 1.24; 95% CI, 1.13-1.35) populations after RCL enactment. No increases were found in the odds of past-year or past-month cannabis use post-RCL enactment among non-Hispanic Black individuals or among individuals aged 12 to 20 years for all race and ethnicity groups. In addition, among people who used cannabis, while no increases were found in past-month daily cannabis in any racial or ethnic group, the odds of cannabis use disorder increased post-RCL among individuals categorized as other overall (aOR, 1.45; 95% CI, 1.07-1.95), but no increases were found by age group.

CONCLUSIONS AND RELEVANCE

Changes in cannabis use by race and ethnicity that may be attributable to policy enactment and variations in recreational policy provisions should be monitored. To ensure that the enactment of recreational cannabis laws truly contributes to greater equity in outcomes and adheres to antiracist policies, monitoring unintended and intended consequences that may be attributable to recreational cannabis use and similar policies by race and ethnicity is needed.

Association Between Recreational Marijuana Legalization in the United States and Changes in Marijuana Use and Cannabis Use Disorder From 2008 to 2016

IMPORTANCE

Little is known about changes in marijuana use and cannabis use disorder (CUD) after recreational marijuana legalization (RML).

OBJECTIVES

To examine the associations between RML enactment and changes in marijuana use, frequent use, and CUD in the United States from 2008 to 2016.

DESIGN, SETTING, AND PARTICIPANTS

This survey study used repeated cross-sectional survey data from the National Survey on Drug Use and Health (2008-2016) conducted in the United States among participants in the age groups of 12 to 17, 18 to 25, and 26 years or older.

INTERVENTIONS

Multilevel logistic regression models were fit to obtain estimates of before-vs-after changes in marijuana use among respondents in states enacting RML compared to changes in other states.

MAIN OUTCOMES AND MEASURES

Self-reported past-month marijuana use, past-month frequent marijuana use, past-month frequent use among past-month users, past-year CUD, and past-year CUD among past-year users.

RESULTS

The study included 505 796 respondents consisting of 51.51% females and 77.24% participants 26 years or older. Among the total, 65.43% were white, 11.90% black, 15.36% Hispanic, and 7.31% of other race/ethnicity. Among respondents aged 12 to 17 years, past-year CUD increased from 2.18% to 2.72% after RML enactment, a 25% higher increase than that for the same age group in states that did not enact RML (odds ratio [OR], 1.25; 95% CI, 1.01-1.55). Among past-year marijuana users in this age group, CUD increased from 22.80% to 27.20% (OR, 1.27; 95% CI, 1.01-1.59). Unmeasured confounders would need to be more prevalent in RML states and increase the risk of cannabis use by 1.08 to 1.11 times to explain observed results, indicating results that are sensitive to omitted variables. No associations were found among the respondents aged 18 to 25 years. Among respondents 26 years or older, past-month marijuana use after RML enactment increased from 5.65% to 7.10% (OR, 1.28; 95% CI, 1.16-1.40), past-month frequent use from 2.13% to 2.62% (OR, 1.24; 95% CI, 1.08-1.41), and past-year CUD from 0.90% to 1.23% (OR, 1.36; 95% CI, 1.08-1.71); these results were more robust to unmeasured confounding. Among marijuana users in this age group, past-month frequent marijuana use and past-year CUD did not increase after RML enactment.

CONCLUSIONS AND RELEVANCE

This study's findings suggest that although marijuana legalization advanced social justice goals, the small post-RML increase in risk for CUD among respondents aged 12 to 17 years and increased frequent use and CUD among adults 26 years or older in this study are a potential public health concern. To undertake prevention efforts, further studies are warranted to assess how these increases occur and to identify subpopulations that may be especially vulnerable.

Cannabis use disorder among people using cannabis daily/almost daily in the United States, 2002-2016

BACKGROUND

Cannabis use disorder (CUD) prevalence among people reporting past-year cannabis use declined from 2002-2016. We examined whether similar reductions in CUD were observed among people reporting daily/almost daily cannabis use. We expected that CUD prevalence among people reporting daily/almost daily use would not decrease.

METHODS

We used 2002-2016 National Survey on Drug Use and Health (NSDUH) data, including 22,651 individuals using cannabis 300+ days in the past year. CUD was defined using DSM-IV criteria for cannabis abuse and/or dependence. Age categories included: 12-17, 18-25, and 26 + . Annual prevalence of CUD, cannabis dependence, cannabis abuse, and each individual abuse/dependence items accounted for the complex survey design. Differences in trends over time were examined by age group.

RESULTS

From 2002-2016, the prevalence of CUD among people reporting daily/almost daily cannabis use decreased by 26.8% in adolescents, by 29.7% in ages 18-25, and by 37.5% in ages 26 + . Prevalence of DSM-IV cannabis dependence decreased significantly among adolescents (-43.9%) and young adults (-26.8%) but remained stable in adults 26 + . Reductions in most dependence items were observed in young adults, with less consistent patterns in adolescents and adults 26 + . Prevalence of DSM-IV cannabis abuse decreased overall and for each abuse item across all age groups.

CONCLUSIONS

Contrary to expectations, CUD prevalence decreased significantly across all ages reporting daily/almost daily cannabis use between 2002-2016. Cannabis dependence prevalence decreased for adolescents and young adults and was stable only among adults ages 26+ reporting daily/almost daily cannabis use. Potential drivers of this decrease should be further explored.

The longitudinal effect of early-life sensation seeking on gambling and gambling problems among Puerto Rican young adults

Sensation seeking has been proposed as a risk factor for gambling and gambling problems; however, existing evidence for a relationship between sensation seeking and gambling behaviors is inconclusive and data are lacking for emerging adults and racial and ethnic minorities. In this longitudinal study, we explored the association between developmental trajectories of sensation seeking in childhood and adolescence and gambling and gambling problems in early adulthood in individuals of Puerto Rican origin. Gambling data were collected during 2014-2018 from a subsample of participants in the Boricua Youth Study who were recruited in the South Bronx of New York City and in San Juan and Caguas, Puerto Rico. Sensation seeking was measured using a 10-item instrument modified from the scale created by Russo et al. for use in children as young as 5 years old. Developmental trajectories of age-adjusted sensation seeking were created using growth mixture models. Gambling and gambling problems were assessed based on the Canadian Adolescent Gambling Inventory (CAGI) Version 1.09. Data were analyzed using descriptive methods and multivariable logistic regression. Individuals in the high sensation-seeking class had lower adjusted odds of past-year gambling (OR = .36; 95% confidence interval [.14, .92]) than did those in the normative sensation-seeking class, whereas no differences were observed for individuals in the low and accelerated classes. No relationship was found between sensation seeking and past-year gambling problems. Given the severe consequences of early initiation of gambling and gambling problems, other early life risk factors and alternative hypotheses for the elevated prevalence of gambling problems in young adults and racial and ethnic minority populations should be explored. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

Association of US Medical Marijuana Laws With Nonmedical Prescription Opioid Use and Prescription Opioid Use Disorder

IMPORTANCE

Between 1997 and 2017, the United States saw increases in nonmedical prescription opioid use and its consequences, as well as changes in marijuana policies. Ecological-level research hypothesized that medical marijuana legalization may reduce prescription opioid use by allowing medical marijuana as an alternative.

OBJECTIVES

To investigate the association of state-level medical marijuana law enactment with individual-level nonmedical prescription opioid use and prescription opioid use disorder among prescription opioid users and to determine whether these outcomes varied by age and racial/ethnic groups.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional study used restricted data on 627 000 individuals aged 12 years and older from the 2004 to 2014 National Survey on Drug Use and Health, a population-based survey representative of the civilian population of the United States. Analyses were completed from March 2018 to May 2018.

EXPOSURES

Time-varying indicator of state-level medical marijuana law enactment (0 = never law enactment, 1 = before law enactment, and 2 = after law enactment).

MAIN OUTCOMES AND MEASURES

Past-year nonmedical prescription opioid use and prescription opioid use disorder among prescription opioid users. Odds ratios of nonmedical prescription opioid use and prescription opioid use disorder comparing the period before and after law enactment were presented overall, by age and racial/ethnic group, and adjusted for individual- and state-level confounders.

RESULTS

The study sample included 627 000 participants (51.51% female; 9.88% aged 12-17 years, 13.30% aged 18-25 years, 14.30% aged 26-34 years, 25.02% aged 35-49 years, and 37.50% aged ≥50 years; the racial/ethnic distribution was 66.97% non-Hispanic white, 11.83% non-Hispanic black, 14.47% Hispanic, and 6.73% other). Screening and interview response rates were 82% to 91% and 71% to 77%, respectively. Overall, there were small changes in nonmedical prescription opioid use prevalence after medical marijuana law enactment (4.32% to 4.86%; adjusted odds ratio, 1.13; 95% CI, 1.06-1.20). Prescription opioid use disorder prevalence among prescription opioid users decreased slightly after law enactment, but the change was not statistically significant (15.41% to 14.76%; adjusted odds ratio, 0.95; 95% CI, 0.81-1.11). Outcomes were similar when stratified by age and race/ethnicity.

CONCLUSIONS AND RELEVANCE

This study found little evidence of an association between medical marijuana law enactment and nonmedical prescription opioid use or prescription opioid use disorder among prescription opioid users. Further research should disentangle the potential mechanisms through which medical marijuana laws may reduce opioid-related harm.

Factors Associated With Sputum Culture-Negative vs Culture-Positive Diagnosis of Pulmonary Tuberculosis

IMPORTANCE

Recognition of active tuberculosis (TB) in its earliest stages could reduce morbidity and prevent advancement to transmissible disease. Little is published about the occurrence and presentation of sputum culture-negative pulmonary TB (PTB), an early paucibacillary but often underrecognized disease state.

OBJECTIVE

To assess differences between culture-negative and culture-positive PTB regarding occurrence, clinical presentation, radiographic findings, demographics, and comorbidities.

DESIGN, SETTING, AND PARTICIPANTS

Cross-sectional study in which surveillance data of adult patients with PTB reported to the New York City Department of Health in New York, New York, from 2011 through 2013, ie, years for which demographic, clinical, and radiographic data were collected. Patients were aged 18 years or older, had signs of pulmonary disease, and had mycobacterial sputum culture results; those with HIV coinfection or a TB diagnosis within 2 years prior to presentation were excluded. Culture-negative PTB was defined as clinical and radiographic presentation consistent with TB, 3 negative results on sputum culture, and improvement with antituberculous treatment. The analyses were performed between 2015 and 2016; notably, the proportion of reported patients with culture-negative PTB has remained consistent during the past 2 decades.

MAIN OUTCOMES AND MEASURES

The occurrence of culture-negative PTB among all patients with PTB was calculated, and demographics, comorbidities, symptoms, and radiographic findings were compared between culture-negative and culture-positive PTB.

RESULTS

Of the 796 patients with PTB (median [interquartile range] age, 41 [29-54] years; 499 [63%] men) who met criteria for analysis, 116 (15%) had negative results on sputum culture. Patients with culture-negative PTB compared with culture-positive PTB were less frequently male (53% vs 64%; P = .03) and presented with a significantly lower frequency of cough (68% vs 89%; P < .001), weight loss (39% vs 51%; P = .03), and cavitation on both chest radiograph (7% vs 28%; P < .001) and chest computed tomographic scan (26% vs 59%; P < .001).

CONCLUSIONS AND RELEVANCE

Given the lack of criterion-standard test confirmation and the relative paucity of symptoms and radiological abnormalities, culture-negative PTB is likely underdiagnosed and its occurrence underestimated globally. Awareness of these findings, enhanced diagnostic approaches, and, ideally, better biomarkers could improve detection and treatment of this early disease and reduce the development of transmissible TB.

Accuracy of GDx variable corneal compensation polarization measurements in normal human eyes: effect of accommodation, cycloplegia, focus, pupil size, and eye selection on reproducibility

PURPOSE

To evaluate the reproducibility of variable corneal compensation (VCC) and the effect of accommodation, cycloplegia, eye selection, focus, and pupil size on this measurement of polarization.

METHODS

Using a GDx scanning laser polarimeter, multiple measurements of the VCC were obtained from each eye of 33 healthy, young adults under differing conditions. Pupil size and refraction were independently measured with a pupillometer and an autorefractometer. The effects of eye, instrument focus, pupil diameter, cycloplegia, and accommodation were statistically assessed.

RESULTS

The reproducibility of a single retardation measurement and its axis, as determined by the standard deviations (SD) of repeated measurements, is +/-1.58 nm and 2.10 degrees , respectively. There is a difference in retardation between right and left eyes, of 5.26+/-9 nm, P=0.002. Increasing pupil size increases retardation. Cycloplegia or defocusing decreases retardation, and pharmacologically induced accommodation has no effect on retardation.

CONCLUSIONS

The retardation and its axis are highly reproducible measurements when the pupil is of physiologic size and the GDx is properly focused. There is a consistent difference in VCC retardation between the paired right and left eyes. This difference may reflect equipment-induced measurement artefact and/or an anatomic asymmetry between the paired eyes of the subjects studied. Clinicians should be cautious when comparing interocular VCC measurements between paired right and left eyes and using data pooled from both eyes for age-adjusted, normalized standards.

Structure-function analysis of the antioxidant properties of haptoglobin

Haptoglobin serves as an antioxidant by virtue of its ability to prevent hemoglobin-driven oxidative tissue damage. It was recently demonstrated that an allelic polymorphism in the haptoglobin gene is predictive of the risk for numerous microvascular and macrovascular diabetic complications. Because these complications are attributed in large part to an increase in oxidative stress, a study was conducted to determine whether the different protein products of the 2 haptoglobin alleles differed in the antioxidant protection they provided. A statistically significant difference was found in the antioxidant capacity of purified haptoglobin protein produced from the 2 different alleles, consistent with the hypothesis that differences in genetically determined antioxidant status may explain differential susceptibility to diabetic vascular complications. These differences may be amplified in the vessel wall because of differences in the sieving capacity of the haptoglobin types. Therefore, an attempt was made to identify the minimal haptoglobin sequences necessary to inhibit oxidation by hemoglobin in vitro, and 2 independent haptoglobin peptides that function in this fashion as efficiently as native haptoglobin were identified. Identification of the biochemical basis for differences among haptoglobin types may lead to the rational development of new pharmacologic agents, such as the mini-haptoglobin described here, to avert the development of diabetic vascular complications.

Hypoxic induction of vascular endothelial growth factor is markedly decreased in diabetic individuals who do not develop retinopathy

OBJECTIVE

A small percentage of patients do not develop any evidence of diabetic retinopathy (DR) even after many years of diabetes. Vascular endothelial growth factor (VEGF) has been implicated in the development of DR. Therefore, we sought to determine if the regulation of VEGF differs in those patients who develop DR after many years of diabetes compared with those who do not develop DR.

RESEARCH DESIGN AND METHODS

We performed standard 7-field stereoscopic fundus photography on 95 consecutive patients with type 1 and type 2 diabetes. Patients were categorized into 3 groups according to the presence or absence of DR and the duration of diabetes: group 1 was defined by presence of DR, group 2 was defined by absence of DR after >10 years duration of diabetes, and group 3 was defined by absence of DR with long-standing diabetes (> or =20 years for type 1 diabetes and > or =15 years for type 2 diabetes). Monocytes from 40 ml peripheral blood were isolated from all patients, and the hypoxic induction of VEGF was determined in vitro.

RESULTS

We found no significant difference in the basal level of VEGF in patients with and without DR. However, we did find a markedly significant difference in the hypoxic induction of VEGF between patients from group 1 and group 3 (4.35+/-0.55 vs. 1.87+/-0.3, P<0.00013).

CONCLUSIONS

This study suggests that 1 mechanism for the absence of DR in patients with long-standing diabetes is a decreased hypoxic induction of VEGF.

Hypoxic stabilization of vascular endothelial growth factor mRNA by the RNA-binding protein HuR

Vascular endothelial growth factor (VEGF) is a potent angiogenic factor whose expression is dramatically induced by hypoxia due in large part to an increase in the stability of its mRNA. Here we show that HuR binds with high affinity and specificity to the element that regulates VEGF mRNA stability by hypoxia. Inhibition of HuR expression abrogates the hypoxia-mediated increase in VEGF mRNA stability. Overexpression of HuR increases the stability of VEGF mRNA. However, this only occurs efficiently in hypoxic cells. We further show that the stabilization of VEGF mRNA can be recapitulated in vitro. Using an S-100 extract, we show that the addition of recombinant HuR stabilizes VEGF mRNA markedly. These data support the critical role of HuR in mediating the hypoxic stabilization of VEGF mRNA by hypoxia.

Regulation of vascular endothelial growth factor expression by insulin-like growth factor I

Insulin-like growth factor I (IGF-I) and vascular endothelial growth factor (VEGF) levels are correlated with retinal ischemia-associated intraocular neovascularization in humans. Since VEGF is required for iris and retinal neovascularization in animal models of retinal ischemia, we tested whether IGF-I could act as an indirect angiogenic factor by increasing VEGF gene expression. IGF-I increased retinal pigment epithelial (RPE) cell VEGF mRNA in a concentration-dependent manner with an EC50 of 7 nmol/1 (53.6 ng/ml). RPE and bovine smooth muscle cells exposed to 50 nmol/l (383 ng/m1) IGF-I achieved peak VEGF mRNA expression within 2 h. IGF-I-treated RPE cells increased VEGF protein levels in conditioned media and stimulated capillary endothelial cell proliferation. Blockade of the IGF-I receptor with a neutralizing antibody abrogated the VEGF increases in RPE cells. Further, hypoxia-mediated and IGF-I-mediated increases in VEGF mRNA and protein levels were additive in RPE cells, and the hypoxia-induced VEGF increases were independent of endogenous IGF-I. VEGF promoter activity was enhanced by IGF-I in RPE cells, but VEGF transcript half-life was unaltered. In summary, the supplementation of RPE and smooth muscle cell cultures with IGF-I at 5-100 nmol/l increased VEGF mRNA and secreted protein levels. The VEGF increases in RPE cells occurred primarily through enhanced transcription of the VEGF gene and via the IGF-I receptor. Elevated IGF-I levels may promote neovascularization through increased retinal VEGF gene expression.

Sequencing of the human vascular endothelial growth factor (VEGF) 3' untranslated region (UTR): conservation of five hypoxia-inducible RNA-protein binding sites

Vascular endothelial growth factor (VEGF) is a potent angiogenic factor whose mRNA expression is induced by hypoxia. This induction is due in large part to an increase in the stability of its mRNA. The RNA sequences and cognate proteins responsible for this increased stability with hypoxia are not well understood. In order to identify regions of functional importance in the 3'UTR of VEGF mRNA, we have sequenced the human VEGF 3'UTR and compared it to the rat sequence. Overall sequence homology was 82% with complete conservation of all four potential polyadenylation signals and both nonameric instability elements. Five hypoxia-inducible RNA protein-binding (HI-RPB) sites were identified by RNA electromobility shift assay (EMSA) in the human and rat genes. EMSA and competition studies suggest that these sites bind a similar or related protein complex. On average, the five sites were 95% conserved at the nucleotide level between the rat and corresponding human sequence. This conservation taken together with several previously described, independent correlations between the presence of these RNA-protein complexes and an increase in VEGF mRNA stability suggest an important functional role for these sites in mediating hypoxia-inducible VEGF mRNA stability.

Regulation of vascular endothelial growth factor by hypoxia and its modulation by the von Hippel-Lindau tumor suppressor gene

The regulation of VEGF production is mediated by both transcriptional and post-transcriptional mechanisms. A schematic model of elements involved in hypoxic regulation of VEGF is shown in Figure 1.

Ocular absorption, blood levels, and excretion of dorzolamide, a topically active carbonic anhydrase inhibitor

Dorzolamide is a powerful inhibitor of carbonic anhydrase (CA) II that penetrates the sclera and cornea to reach the ciliary process and lowers formation of HCO3 and aqueous humor. The usual dose applied to the eye in treatment of glaucoma is 1 drop (30 microL of 2% solution) every 8 hr to each eye, or a total daily dose of 4 mg. On this regime, the red cells accumulated drug over a period of 8 days, reaching a value of 20-25 microM, which corresponds to the concentration of CA II in human red cells. This drug concentration persisted throughout the 18 months of application. The plasma concentration was 0.034 microM, or 1/700 that of the red cells. This plasma concentration corresponds to that calculated from the dilution of administered drug into body water. The data are well fitted into the equilibrium expression for KI of dorzolamide against CA II at 37 degrees C, as 8 x 10(-9) M. The red cells also contain a small amount (5 microM) of the N-des-ethyl metabolite, probably reflecting its modest binding to CA I. In the initial 8-day drug period, virtually none appeared in the urine since CA II sites were being filled. At steady state, renal excretion was 1.3 mg/day and the renal clearance 90 ml/min. These excretion numbers include the small (20%) amount of the des-ethyl metabolite of dorzolamide. The relation of these data to lowering of intraocular pressure is clear. By the systemic route, an inhibitor such as acetazolamide is effective when free drug concentration in plasma is 2.5 microM. In the case of topical drugs, as shown here, the plasma concentration is some 100 x lower, but the concentration in ciliary process is 2-10 microM, comparable to that following systemic drugs (1). In conclusion, the concentration in plasma (reflecting free drug) of dorzolamide is about 1/200 of that needed for systemic effects as seen following acetazolamide or methazolamide. Thus, there is a clear pharmacological basis for the lack of any physiological effects of ocular dorzolamide, except on the eye itself.

Hypoxia-inducible protein binding to vascular endothelial growth factor mRNA and its modulation by the von Hippel-Lindau protein

Hypoxia induces an increase in the stability of the mRNA encoding vascular endothelial growth factor (VEGF). We have previously demonstrated that a 500-base region of the 3'-untranslated region of VEGF mRNA that is critical for stabilization of VEGF mRNA in an in vitro degradation assay forms a RNA-protein complex in a hypoxia-inducible fashion. We report here the identification of three adenylate-uridylate-rich RNA elements within this region that form an identical or closely related hypoxia-inducible RNA-protein complex. This complex is constitutively elevated in a tumor cell line lacking the wild type von Hippel-Lindau tumor suppressor gene and in which VEGF mRNA is constitutively stabilized. Furthermore, the glucose transporter-1 mRNA, which is also stabilized by hypoxia, forms a hypoxia-inducible RNA-protein complex with similar sequence and protein binding characteristics to that described for VEGF mRNA. Finally, RNA affinity purification and UV cross-linking were used to identify three proteins of 32, 28, and 17 kDa that are derived from this hypoxia-inducible RNA-protein complex.

Post-transcriptional regulation of vascular endothelial growth factor by hypoxia

The major control point for the hypoxic induction of the vascular endothelial growth factor (VEGF) gene is the regulation of the steady-state level of the mRNA. We previously demonstrated a discrepancy between the transcription rate and the steady-state mRNA level induced by hypoxia. This led us to examine the post-transcriptional regulation of VEGF expression. Actinomycin D experiments revealed that hypoxia increased VEGF mRNA half-life from 43 +/- 6 min to 106 +/- 9 min. Using an in vitro mRNA degradation assay, the half-life of VEGF mRNA 3'-untranslated region (UTR) transcripts were also found to be increased when incubated with hypoxic versus normoxic extracts. Both cis-regulatory elements involved in VEGF mRNA degradation under normoxic conditions and in increased stabilization under hypoxic conditions were mapped using this degradation assay. A hypoxia-induced protein(s) was found that bound to the sequences in the VEGF 3'-UTR which mediated increased stability in the degradation assay. Furthermore, genistein, a tyrosine kinase inhibitor, blocked the hypoxia-induced stabilization of VEGF 3'-UTR transcripts and inhibited hypoxia-induced protein binding to the VEGF 3'-UTR. These findings demonstrate a significant post-transcriptional component to the regulation of VEGF.

Transcriptional regulation of the rat vascular endothelial growth factor gene by hypoxia

Vascular endothelial growth factor (VEGF), a potent angiogenic factor and endothelial cell-specific mitogen, is up-regulated by hypoxia. However, the mechanism(s) responsible for hypoxic induction of VEGF has not been clearly delineated. We report that the steady state VEGF mRNA levels are increased 12 +/- 0.6-fold, but the transcriptional rate for VEGF is increased only 3.1 +/- 0.6-fold by hypoxia in PC12 cells. In order to investigate cis-regulatory sequences which mediate this response to hypoxia, we cloned the rat genomic sequences encoding VEGF and identified a 28-base pair element in the 5' promoter that mediates hypoxia-inducible transcription in transient expression assays. This element has sequence and protein binding similarities to the hypoxia-inducible factor 1 binding site within the erythropoietin 3' enhancer. Post-transcriptional mechanisms have also been suggested to play a role in the hypoxic induction of VEGF. Evidence is provided that a frequently used polyadenylation site is 1.9 kilobases downstream from the translation termination codon for rat VEGF. This site is 1.5 kilobases further downstream from the polyadenylation site previously reported for VEGF. This new finding reveals sequence motifs in the 3'-untranslated region that may mediate VEGF mRNA stability.

Regulation of vascular endothelial growth factor in cardiac myocytes

Collateral blood vessels supplement normal coronary blood flow and coronary blood flow compromised by coronary artery disease, thereby protecting the myocardium from ischemia. Collateral vessel formation is the result of angiogenesis. Vascular endothelial growth factor (VEGF), also known as vascular permeability factor (VPF), is a secreted mitogen specific for endothelial cells and an extremely potent angiogenic factor. In the present study, VPF/VEGF mRNA and protein were demonstrated to be markedly stimulated in primary rat cardiac myocytes in vitro in response to reduction of the oxygen tension to 1% or inhibition of the electron transport chain. Four isoforms of VPF/VEGF were coordinately regulated by hypoxia, including a novel isoform not previously described. Phorbol ester and the depolarizing agent veratridine, stimulators of protein kinase C and calcium influx, respectively, were found to markedly increase VPF/VEGF mRNA expression in cardiac myocytes. Forskolin, a potent stimulator of adenylate cyclase, produced a small but significant increase in VPF/VEGF mRNA expression in the cardiac myocytes. However, only H7, an inhibitor of protein kinase C, inhibited the hypoxic induction of VPF/VEGF mRNA; inhibitors of calcium influx and the calcium-calmodulin-dependent protein kinase II as well as inhibition of protein kinase A did not block the hypoxic induction of VPF/VEGF mRNA. This suggests that more than one signal transduction pathway is involved in regulating VPF/VEGF expression. The sensor that regulates the expression of hypoxia-responsive genes has been proposed to be a heme protein. Consistent with this model, transition metals initiate a genetic program similar to hypoxia.(ABSTRACT TRUNCATED AT 250 WORDS)

The molecular basis of signal transduction in olfactory sensory neurons

Contributions from a wide spectrum of experimental systems have resulted in a dramatic increase in our understanding of this old and most enigmatic of the sensory systems. Many of the components of the odorant-induced transduction cascade have now been cloned, and the biochemistry, pharmacology, and regulatory mechanisms are being addressed in a logical fashion. One of the first priorities is to establish that the large family of putative receptor proteins described by Buck and Axel (1991) do, in fact, bind odorants. The ability to express members of this receptor family at high levels in the mammalian expression system is a first step in this direction. Determining specific ligand-receptor relationships is an extremely challenging task given the diversity of odorants able to be perceived and the potentially large size of the family of receptors. The role of other proteins in odorant presentation and processing, such as odorant binding protein produced in the lateral nasal gland (Pevsner et al., 1988), can be explored. A fascinating issue to be resolved is that of the distribution of receptor molecules within the population of olfactory sensory neurons. Does one cell express only one receptor, a small repertoire of receptors, or indeed the entire family? These questions can now be answered using a combined approach with in situ hybridization, immunocytochemistry, and single cell PCR techniques. One model of receptor distribution would provide for discrimination of a particular odorant by higher order analysis of the pattern of receptor neuron firing within the neuroepithelium.(ABSTRACT TRUNCATED AT 250 WORDS)

Signal transduction in olfactory neurons

Recent efforts in our laboratory have focused on cloning the molecular components involved in the cAMP-mediated pathway of olfactory signal transduction. These efforts have resulted in the isolation of olfactory-specific forms of a G protein, an adenylyl cyclase, and a cyclic nucleotide-gated cation channel. Functional expression of each of these proteins in vitro confirms their ability to carry out the function ascribed to them as part of a second-messenger cascade. Putative odorant-receptor molecules which constitute the first step in odorant signal transduction have now been cloned. We have generated oligonucleotide probes which recognize a population of olfactory receptors apparently more heterogeneous than those previously reported. These probes should enable us to answer questions regarding the number of different receptors expressed per cell as well as the nature of receptor-ligand specificity.

Mutation in a reporter gene depends on proximity to and transcription of immunoglobulin variable transgenes

Somatic mutation in immunoglobulin genes is localized to a 2-kilobase region of DNA surrounding and including rearranged variable (V), diversity, and joining (J) gene segments encoding heavy and light chains. To examine the structural basis for targeted mutation, we developed an assay to score mutation on plasmid substrates by using a reporter gene: a bacterial gene encoding an amber-suppressor tRNA molecule was placed 3' of a rearranged kappa VJ gene within the boundaries of mutation. The reporter gene is exquisitely suited for mutational analysis because it is only 200 base pairs (bp), which should not greatly disrupt structure of the immunoglobulin locus, and gene function depends on secondary structure, which means mutation can be scored in many different nucleotide positions. The plasmid was used to make transgenic mice, which were then immunized. The shuttle vector was retrieved by plasmid rescue into an indicator strain of Escherichia coli that contained an amber mutation in its beta-galactosidase gene. Integrity of the tRNA molecule was monitored by colony color, which permitted many transformants to be screened visually. Mutations were not seen in DNA from a transfected B-cell line grown in vitro or in DNA from nonlymphoid tissue of transgenic mice, indicating that the reporter gene was stable during cell division and DNA manipulations. However, when the transgenic mice were immunized, DNA from splenic B cells contained point mutations in the reporter gene at a frequency of 10(-3) per transformant. Sequence analysis of 17 mutated transgenes revealed that the mutations were 1- and 2-bp deletions in the tRNA gene, and one plasmid had an additional 2-bp deletion in the V gene. In contrast, previous studies have shown that mutations in endogenous VJ genes are predominantly nucleotide substitutions and have only 6% deletions. Two other plasmid constructs were analyzed in transgenic lines: no mutations were found when the tRNA gene was placed distal to the VJ gene, and no mutations were seen when the immunoglobulin promoter was deleted. Although we lack direct evidence that the deletions in the tRNA gene are caused by the same mechanism that acts on VJ genes, we have shown that mutations in this assay occur in a manner consistent with immunoglobulin-specific mutation in that they are found in splenic B cells and not in tail tissue, depend on position next to the VJ gene, and require transcription of the VJ gene.

Transscleral YAG cyclocoagulation of the ciliary body for persistently high intraocular pressure following penetrating keratoplasty

Nine postkeratoplasty eyes with persistent intraocular pressure (IOP) elevation were treated under an investigational protocol by transscleral YAG cyclocoagulation (TSYCC). All eyes were using the maximally tolerated antiglaucomatous medical therapy. Some eyes also had prior antiglaucomatous surgery, including cyclocryotherapy. All of these eyes were considered poor candidates for filtration. Laser applications were applied in a single session at 32 to 36 equally spaced locations throughout 360 degrees, 2.5 mm posterior to the limbus. The energy employed was between 7 and 10 joules at each site. Total energy varied between 256 and 352 joules per eye. The results and complications associated with this procedure are described in nine eyes with a minimum follow-up of 3 months and a median follow-up of over 6 months. Pressure control was achieved in all eyes. At the energy levels employed, hypotony (IOP less than 3 mm Hg) developed in two of the nine eyes, both of which had prior cyclocryotherapy. IOP was between 5 and 19 mm Hg in the remaining eyes. One of these required further medication (betaxolol) to obtain IOP less than 20 mm Hg, and one other developed a late pressure elevation due to pupillary block. Although these results confirm the efficacy of TSYCC, our outcomes suggest that total energy should be limited to less than 256 joules at the time of initial treatment in order to reduce the incidence of hypotony. Eyes with prior cyclodestructive therapy appear most likely to develop hypotony and should, accordingly, be treated with reduced total energy. Patent iridotomies are required in pseudophakic eyes, as pupillary block can develop due to fibrinous iridocyclitis.

Early onset of somatic mutation in immunoglobulin VH genes during the primary immune response

The dynamics of somatic mutation in Ig variable genes was investigated in order to define a population of B cells undergoing mutation. BALB/cJ mice were injected with PC-KLH, and splenic RNA was prepared 5, 7, and 13 d later. The mRNA was annealed to gamma constant region primers to make cDNA transcripts encoding VH genes. 103 cDNA clones corresponding to 18 different genes from the VH7183, VH3660, and VHS107 subfamilies were sequenced to identify mutation. VH genes had a low level of mutation on day 5 after immunization and accumulated more mutation by day 7 at a rate of 10(-3) mutations per nucleotide per generation. However, by day 13, the number of mutations per gene did not increase, and most of the substitutions encoded replacement amino acid changes that were clustered in the hypervariable regions, indicating that the mutational process was less active during the second week and that antigen selection had occurred. The data are consistent with a developmentally regulated mechanism in which mutation is activated during the first week of the primary immune response for a limited time period, after which selection acts to preserve the beneficial mutants.

Impaired immunity in vitamin A-deficient mice

Vitamin A deficiency was produced in mice and was used to investigate the role of vitamin A in immune function. Cellular immunity, as measured by delayed-type hypersensitivity, diminished in early deficiency before weight and appetite changes occurred and declined further as the deficiency progressed. Humoral immunity, as measured by serum immunoglobulin M (IgM) responses to a protein antigen (hemocyanin), also declined. The kinetics of antibody production were unaffected by the deficiency. The T-cell number remained unchanged, but B-cell and macrophage numbers were increased in vitamin A--deficient mice. Surface expression of membrane glycoproteins (Thy-1, Lyt-1, Lyt-2, L3T4, IgM, Mac-1) was unchanged by the deficiency, as were lymphocyte numbers and distribution. The results suggest that vitamin A deficiency is associated with a functional immune system defect.

Somatic mutation in anti-phosphorylcholine antibodies

A detailed analysis of the genes and proteins that participate in the murine immune response to PC has provided key insights at the structural level into the phenomenon of somatic mutation in B cells. Most anti-PC antibodies are encoded by 1 VH gene of the S107 subfamily, and 3 VK genes, VKT15 of the VK22 subfamily, VKM3 from the VK8 subfamily, and VK167 from the VK24 subfamily. No mutation was detected in these genes until the 2nd wk after immunization, indicating that mutation is under developmental control. The protein sequences of 73 heavy and light chains derived from the secondary response support the concept of developmental activation of mutation after antigen stimulation. No mutation was found in the IgM antibodies, whereas half of the IgG and IgA antibodies had mutation. Most of the mutated antibodies had higher affinity for antigen than their germline counterparts, which suggests that the major role of somatic mutation is to increase affinity rather than to create new specificities. Nucleotide sequencing established two hallmarks of mutation in immunoglobulin genes: mutations are targeted to a 1 kilobase region surrounding and including the rearranged variable gene, and they occur at an extraordinary frequency of 10(-2) nucleotide substitutions. Mutation is probably caused by DNA repair, and may occur during error-prone repair of nicked DNA around the variable gene or during mismatch repair of misaligned structural intermediates. The elucidation of this remarkable mechanism clearly requires studies of a more dynamic character. Two major questions that need to be answered are: what targets mutation to the variable gene, and what enzymes are involved?

Matched comparison of Goldmann perimetry and automated two-zone suprathreshold Dicon perimetry in open-angle glaucoma

Goldmann kinetic perimetry is a commonly used measurement of visual field defects in open-angle glaucoma. The many new automated perimeters should be assessed against this common standard with a view to comparing their sensitivity in making clinical judgments of the presence and extent of a visual field defect. This study compares the Coopervision Dicon 2000 perimeter and its automated two-zone suprathreshold program with Goldmann kinetic perimetry in 26 patients with open-angle glaucoma. The two-zone suprathreshold testing program on the Coopervision Dicon perimeter was found to be at least as sensitive as the Goldmann kinetic perimeter in identifying the presence and extent of visual field defects in open-angle glaucoma.

Displacement of optic nerve head in response to short-term intraocular pressure elevation in human eyes

Mechanical movement, reflecting compression within the lamina cribrosa, has been suggested as an initiating event in the production of damage in glaucoma. Reversible movements within the lamina cribrosa were sought and studied by characterizing the displacement of fine platinum wire following short-term elevation of intraocular pressure in 13 enucleated human eyes. With IOP elevation, maximum movement in the optic nerve occurred near its center, with minimum movement at its periphery. The difference in movement between these two locations increased with increases in IOP. However, the greatest displacement per unit of IOP elevation occurred at the lowest IOP. Resistance to further displacement occurred as higher IOP was reached. The differential mechanical displacement observed may initiate damage in open-angle glaucoma by causing compression of the vessels and/or shearing of axons within the lamina cribrosa.

Displacement of the optic nerve head. Response to acute intraocular pressure elevation in primate eyes

Mechanical compression of axons within the lamina scleralis has been suggested as a mechanism of damage in glaucoma. Movement within the optic nerve head was studied after acute intraocular pressure elevation in the enucleated primate eye. Fine platinum wire was positioned with the lamina scleralis and displacement characterized after IOP elevation. These studies demonstrate the following: (1) retrodisplacement increases significantly with increasing pressure, (2) maximum retrodisplacement occurs at the center and minimum retrodisplacement occurs at the periphery of the optic nerve, (3) retrodisplacement at the position of minimum movement in the optic nerve is indistinguishable from that in the sclera, (4) 67% of the net retrodisplacement occurs after a 15-mm Hg increase in IOP, and (5) tangential displacements within the lamina scleralis also increase with increasing pressure but are only 50% of the magnitude of retrodisplacements.

Accuracy of intraocular lens powers calculated from A-scan biometry with the Echo-Oculometer

Our study indicates that by using data obtained from the Model 3000 Echo-Oculometer, 93% of eyes receiving intraocular lenses will have an optimal visual acuity which will differ by less than three diopters from that calculated. With oscilloscopic control of the end points, the Echo-Oculometer provided good inter-observer reproducibility and low variability.

Non-diabetic retinal abnormalities in chronic pancreatitis

To determine whether retinal abnormalities occur in patients with chronic pancreatitis, ophthalmoscopic and retinal-function evaluation was performed in 28 patients with chronic pancreatitis and 19 healthy subjects. The final threshold of dark adaptation was significantly increased 40 per cent (P less than 0.001) in patients with pancreatitis, whether or not they had steatorrhea. Patients with steatorrhea had a significant decrease of about 42 per cent (P less than 0.001) in the b-wave of the electroretinogram, a measure of both rod and cone function. Seven of the 28 patients complained of difficulty with hight vision; six of these seven had morphologic lesions on ophthalmoscopic examination, confirmed by fluorescein angiography. No correlation was found between any of the retinal abnormalities and the serum vitamin A or zinc levels or glucose tolerance. Non-diabetic retinal lesions and retinal-function abnormalities are common in patients with chronic pancreatitis, even in the absence of steatorrhea.

Infantile glaucoma associated with contralateral esotropia

A 20-month-old white male was first seen with an esotropia at four months of age by his pediatrician. The esotropia had been present by history since early in life. After pediatric evaluation, which demonstrated delayed motor development, he was referred for ophthalmic consultation. A comprehensive ophthalmic evaluation established the diagnoses of infantile glaucoma and myopia of the preferred eye, and esotropia and amblyopia of the emmetropic eye. The infantile glaucoma was surgically treated and amblyopia reversed following patching of the glaucomatous eye. Orthophoria was achieved. Esotropia may be the presenting manifestation of unilateral infantile glaucoma of the contralateral eye. Comprehensive appraisal should include pediatric, neurologic, and ophthalmic evaluation.

Early diagnosis and evolution of dominant retinitis pigmentosa

A 5-month-old girl with retinitis pigmentosa was the healthy offspring of a family with progressive autosomal dominant retinitis pigmentosa. Serial evaluation by both electroretinograph and ophthalmoscopy over a four-year period confirmed the diagnosis and indicated that as early as 5 months of age, electroretinographic abnormalities were present in the patient. These consisted of a reduction in the dark-adapted b-wave amplitude, prominent X-wave, and no suppression of the second b-wave response to paired light stimuli at 75 msec. Progressive reduction in the scotopic electroretinography amplitude has occurred over the ensuing four years, although light-adapted (cone) function still appears normal. Clinical evidence of retinitis pigmentosa became apparent only late in the patient's third year when fine peripheral pigment clumping and vessel attentuation could be seen.

The monocularly elicited visual evoked response in chronic glaucoma

The monocularly elicited transscleral visual evoked cortical response was measured in a group of patients with asymmetric visual field loss due to chronic open-angle glaucoma. It was established that the visual field loss in the 2 eyes was statistically different in the patients. In addition, the peak amplitude of the visual evoked response obtained from a common occipital cortical position was statistically different when the 2 eyes were separately stimulated. A good linear correlation was found between the amplitude of the monocular transscleral visual evoked response and the amount of visual field remaining on tangent screen perimetry. The best correlation was found when a red stimulus was used to elicit the VER. The monocularly elicited visual evoked response provides an objective measurement of visual field in chronic open-angle glaucoma. It has value in those patients who have asymmetric disease and who are unable to provide reliable subjective responses. It may be useful in such patients to follow progression of the glaucomatous process.

The effect of systemic hypotension during cardiopulmonary bypass on intraocular pressure and visual function in humans

The effect of controlled systemic hypotension on intraocular pressure (IOP) and visual function was measured in a group of 12 patients undergoing extracorporeal perfusion during cardiovascular surgery. When venous pressure was controlled, intraocular pressure was noted to fall following a fall in the systemic blood pressure. There was a return of IOP toward normal levels with recovery of the systemic blood pressure. Systemic hypotension of 25 to 100 mm Hg for up to 201 minutes in the presence of hemodilution and hypothermia was not associated with any functional or morphologic change in ocular function.