Plasma renin activity: a risk factor for myocardial infarction in hypertensive patients

To determine whether pretreatment plasma renin activity (PRA), without accompanying 24-h urine sodium, can predict myocardial infarction (MI), the PRA levels of 2,902 hypertensive patients [white (38%), male (65%), median age 55 years], with mean entry blood pressure (BP) of 150/97 mm Hg were examined. During an average 3.6 years follow-up (87% > or = 9 months), there were 55 MIs, 21 strokes, and 16 other cardiovascular disease (CVD) deaths. Classification of PRA levels into 3 renin strata [high (H) PRA > or = 4.5 (n = 354), normal (N) 0.75 to 4.49 (n = 1,622), and low (L) < 0.75 (n = 926) ng/mL/h] yielded subgroups that did not differ in LVH (9% v 11%) or smoking prevalence (26% v 25%) but high versus low PRA subjects included more aged < 55 years (64% v 53%); white (49% v 25%); men (79% v 52%); cholesterol > or = 6.3 mmol/L (33% v 25%); all P values < .01. MI rates per 1,000/year were H: 9.3, N: 5.5, L: 2.5 (H v L, RR = 3.8, 95% CI: 1.7 to 8.4). A similar relationship was seen with total CVD (H: 12.5, N: 9.3, L: 5.2; RR = 2.4, 95% CI: 1.3 to 4.5) and all-cause mortality (H: 7.0, N: 6.2, L: 2.5; RR = 2.8, 95% CI: 1.2 to 6.8) but not CVA (H: 1.6, N: 2.0, L: 1.9). In a Cox survival analysis only renin, age, sex, smoking, LVH, and cholesterol were significantly (P < .02) related to MI occurrence. There was, for every 2 unit increase in PRA, an overall 25% increase in MI incidence. Among hypertensive subjects, PRA level (without urine sodium), is independently and directly associated with the incidence of MI.

The association between birthplace and mortality from cardiovascular causes among black and white residents of New York City

BACKGROUND

Life expectancy is shorter and mortality from cardiovascular disease higher among blacks than among whites in the United States. We studied whether place of birth was associated with mortality from cardiovascular causes among non-Hispanic black and white residents of New York City.

METHODS

We linked mortality records from 1988 through 1992 with 1990 U.S. census data for New York City. Mortality data for blacks born in the U.S. South and Northeast and in the Caribbean were compared with those for whites born in the Northeast.

RESULTS

Among blacks, the rates of overall mortality and mortality from cardiovascular causes exceeded those among whites. Among persons born in the Northeast, the rates of death from cardiovascular disease for white men (285 per 100,000), as compared with black men (299), and for white women (155), as compared with black women (165), were similar. However, Southern-born black men and women both had mortality from cardiovascular disease that was substantially higher than that of their counterparts born in the Northeast, and Caribbean-born blacks had rates substantially lower than their Northeastern-born counterparts. The differences among the groups in the rates of death from coronary heart disease were greater than those for death due to stroke or hypertension. In each category defined by age and sex, Caribbean-born blacks had significantly lower rates of death from coronary heart disease than did whites. Black men who were 25 to 44 years of age and were born in the South had a rate of death from coronary heart disease that was 30 percent higher than that of Northeastern-born blacks, and four times that of Caribbean-born blacks of the same sex and age.

CONCLUSIONS

The higher rate of mortality from cardiovascular causes among blacks, as compared with whites, in New York City masks substantial variation among blacks based on their place of birth.

Cancer mortality of Chinese in New York City 1988-1992

BACKGROUND

This study examines cancer mortality among Chinese migrants in New York City, and compares it with that of residents of China as well as New York City whites.

METHOD

Mortality records for 1988-1992 from the New York City Department of Health, and the 1990 US census data for New York City were used for the analysis. Age-specific deaths and the population of urban China reported by the World Health Organization were also used for comparison. Age-adjusted death rates by gender for Chinese and whites in New York City, as well as for Chinese in China were computed using the world standard population.

RESULTS

New York Chinese had lower mortality rates for all causes, total cancer, oesophageal and lung cancer deaths than did either New York whites or Chinese in China in both genders. However, they had lower death rates than New York whites, but similar to those in China, for colon cancer in both genders, and breast cancer in females. By contrast, New York Chinese had higher death rates for nasopharyngeal cancer than either New York City whites or Chinese in China. Stomach and liver cancer death rates in New York Chinese fell between those in China and New York City whites.

CONCLUSIONS

Cancer mortality rates among Chinese migrants in New York City being the lowest for total cancer and some types of cancers, did not follow the usual pattern of migrants (an intermediate position between rates of native New Yorkers and Chinese in homeland China). However, substantial variations in certain cancer-specific mortality by geography were observed.

Antihypertensive Drug Therapy. The effect of JNC criteria on prescribing patterns and patient status through the first year

This study was designed to evaluate the impact of the protocol-driven antihypertensive therapy on outcomes guided by the Joint National Committee (JNC) on Detection, Evaluation, and Treatment of high blood pressure. In a systematic hypertension control program for union employees conducted in New York City, untreated patients who began treatment on monotherapy guided by JNC recommendations during three representative periods: I-pre-JNC IV (1986-1987); II-post-JNC IV (1990-1991); and III (JNC V)-period of application of what were later published as JNC-V guidelines (1992) were observed during 1 year of treatment. A total of 550 presumably untreated patients were prescribed either diuretics, beta-blockers, calcium channel blockers, or angiotensin converting enzyme inhibitors. There were 231 in period I, 213 in II, and 106 in III. The patient composition over time became more predominantly female and Hispanic (I to III: 28% to 34%, and 35% to 45%, respectively). The main outcome measures were type of drug first prescribed and the outcomes at the end of 1 year-changes in blood pressure, clinical chemistry measures and therapy, and clinic attendance are dropout rate. The pattern of first drug prescription changed from 85% to 90% of patients given diuretics or beta-blockers in I to 90% begun on calcium channel blockers or angiotensin converting enzyme inhibitors in II and finally, to an even distribution of drugs in III. Blood pressure response was similar across the three periods, 135/89 mm Hg (I), 138/89 (II), and 140/89 (III). Proportion of patients remaining on their initial drug in each period was fairly similar (60%, 67%, and 69%). Scheduled clinic visits fell significantly from 7.4 visits in I, 6.9 in II, and 6.4 in III (I upsilon III P = .004). Dropouts diminished significantly from 17% in I, to 10% in II, and 9% in III (I upsilon II or III P = .045). Modest positive changes in cholesterol and fasting blood sugar level occurred over time. In this general community setting, dramatic shifts in the choice of initial drug based upon application of JNC guidelines had little discernable impact on short term patient outcomes.

Angina pectoris by Rose questionnaire does not predict cardiovascular disease in treated hypertensive patients

OBJECTIVE

To determine the predictive value of angina pectoris diagnosed by Rose questionnaire for cardiovascular disease among treated hypertensives.

METHODS

The cardiovascular experience of 4093 patients who had no history of cardiovascular disease and had been administered the Rose questionnaire for angina in a worksite treatment program was evaluated.

RESULTS

Among 2659 men and 1434 women of similar age (53 versus 54 years), the race distribution was 44 versus 31% whites, 27 versus 41% blacks and 29 versus 28% Hispanics. Overall, the prevalence of angina by Rose questionnaire in women (15%) was twice that in men (7%) in all three races, with Hispanics having the highest (20 versus 10%) prevalence. Those with angina (Rose-plus) and those without (Rose-minus) had similar initial and final blood pressures. In 4.0 years of average follow-up study, the crude incidence rates (per 1000 person-years) of the recorded 120 myocardial infarctions and 35 strokes did not differ significantly between Rose-plus and Rose-minus patients, except for myocardial infarction in Hispanic men (20.5 versus 5.9). When myocardial infarction incidence was adjusted for age within each sex-race subgroup, only Rose-plus Hispanic men had a significantly greater relative risk with Rose-minus as referent (relative risk 3.13, 95% confidence interval 1.31-7.50). Overall, in the Cox proportional hazards regression model, angina by Rose questionnaire was not predictive of myocardial infarction after accounting for other recognized risk factors.

CONCLUSIONS

The present data suggest that the Rose questionnaire as a diagnostic tool for angina is not predictive of subsequent clinical events among treated hypertensive patients.

Isolated diastolic hypertension. A favorable finding among young and middle-aged hypertensive subjects

To identify pretreatment characteristics associated with subsequent myocardial infarction in young and middle-aged previously untreated hypertensive individuals, we examined the experience of 1560 participants in a work-site hypertension control program who were younger than 60 years. Subjects were categorized by initial blood pressure as having isolated diastolic hypertension (< 160/> or = 90 mm Hg, n = 965) or combined systolic and diastolic hypertension (> or = 160/> or = 90 mm Hg, n = 595). During 4.5 years of follow-up, there were 24 myocardial infarctions, yielding an overall incidence of 3.89 per 1000 person-years. Subjects with systolic/diastolic hypertension were older, had higher cholesterol and blood sugar levels, and included more smokers and people with left ventricular hypertrophy on electrocardiogram than those with isolated diastolic hypertension. Age-adjusted incidence rates for myocardial infarction were 5.20 and 2.21 per 1000 person-years in systolic/diastolic hypertension and isolated diastolic hypertension, respectively, and the relative risk of systolic/diastolic hypertension was 2.31 (95% confidence interval, 1.29-4.15). Among subjects with isolated diastolic hypertension, no myocardial infarction occurred in those with systolic pressure less than 140 mm Hg. Cox regression analysis including other known risk factors showed that pulse pressure, as a continuous variable (hazards ratio, 1.54; 95% confidence interval, 1.08-2.20), and type of hypertension, ie, systolic/diastolic hypertension versus isolated diastolic hypertension (hazards ratio, 2.11; 95% confidence interval, 1.08-4.13), were independently associated with myocardial infarction. These results suggest that young and middle-aged treated hypertensive individuals with normal pretreatment systolic pressure enjoy a more favorable prognosis than do those with systolic elevation.(ABSTRACT TRUNCATED AT 250 WORDS)

Low urinary sodium is associated with greater risk of myocardial infarction among treated hypertensive men

A sodium-reduced diet is frequently recommended for hypertensive individuals. To determine the relationship of sodium intake to subsequent cardiovascular disease, we assessed the experience of participants in a worksite-based cohort of hypertensive subjects. The 24-hour urinary excretion of sodium (UNaV), potassium, creatinine, and plasma renin activity was measured in 2937 mildly and moderately hypertensive subjects who were unmedicated for at least 3-4 weeks. Morbidity and mortality in these systematically treated subjects were ascertained. Men and women were stratified according to sex-specific quartiles of UNaV. Subjects in these strata were similar in race, cardiovascular status, and pretreatment and intreatment blood pressure. Subjects with lower UNaV were thinner, excreted less potassium, and had higher plasma renin activity. During an average 3.8 years of follow-up, a total of 55 myocardial infarctions occurred. Myocardial infarction and UNaV were inversely associated in the total population and in men but not in women, who sustained only nine events. In men, age- and race-adjusted myocardial infarction incidence in the lowest versus highest UNaV quartile was 11.5 versus 2.5 (relative risk, 4.3, 95% confidence interval, 1.7-10.6). No association was observed between non-cardiovascular disease mortality (n = 11) and UNaV. There was a significant linear trend in proportions of myocardial infarction by UNaV quartile, with a break point after the lowest UNaV quartile.(ABSTRACT TRUNCATED AT 250 WORDS)

Measures of blood pressure and myocardial infarction in treated hypertensive patients

OBJECTIVE

To identify entry characteristics associated with subsequent myocardial infarction in treated hypertensive patients.

DESIGN

Nested case-control study and cohort study.

SETTING AND PATIENTS

The 5730 participants (mean age 53 years; 61% male and 45% Caucasian) were selected from a worksite-based, union-sponsored, systematic hypertension control program from 1973 to 1992.

METHODS

In the case-control study myocardial infarction cases were matched by age, sex, year of entry to the program, years of follow-up and previous treatment status (treated or untreated) with non-event subjects. Baseline clinical and biochemical characteristics were analyzed with regard to the outcome of myocardial infarction, using univariate and multivariate analyses, respectively, in case-control and cohort studies.

RESULTS

During 5.43 years of follow-up the incidence of myocardial infarction was 6.75/1000 person-years. Univariate analysis indicated that myocardial infarction cases had higher cholesterol level and were more likely to have a previous history of diabetes than controls. The initial systolic blood pressure and pulse pressure of cases were significantly higher than in controls. Logistic regression models indicated that initial pulse pressure, either as a continuous or as a categorical variable, was the only measure of blood pressure independently associated with myocardial infarction after adjustment for other risk factors. Analysis of the experience of the total 5730 as well as 2445 previously untreated patients with a cohort study generated identical results.

CONCLUSION

A large pulse pressure difference appears to be the most powerful measure available of initial blood pressure to identify, in advance, those hypertensive patients at greatest risk for a subsequent myocardial infarction.

Renal function during antihypertensive treatment

To determine the association of renal function and the course of blood pressure in antihypertensive therapy, we studied the changes in serum creatinine as a measure of renal function and in-treatment blood pressure in black and white hypertensive patients. We measured serum creatinine in 2125 mild and moderately hypertensive men during treatment over an average of 5 years. Both unadjusted mean initial and final serum creatinine of 758 blacks (113 and 117 mumol/L respectively) were significantly higher than those of 1367 whites (108 and 107 mumol/L), with a small increase of 4 mumol/L (p < 0.01) for blacks and a fall of 0.9 mumol/L (p > 0.05) for whites. Less than 2% of all patients attained or remained at a final serum creatinine of 177 mumol/L or more. Of this small group (3% blacks, 1.4% whites), 31% had proteinuria at entry. After stratification by in-treatment diastolic blood pressure (< 95 and > or = 95 mm Hg) in each race, mean slopes of reciprocal serum creatinine were estimated, adjusting for age at entry, initial serum creatinine, diastolic pressure, and body-mass index by analysis of covariance. The two adjusted mean slopes did not differ significantly within each race. Multiple regression analysis confirmed that in-treatment diastolic pressure was not independently associated with final serum creatinine. The change in renal function was most likely a reflection of regression towards the mean, and does not support the view that antihypertensive treatment is an important determinant of renal function in mild-to-moderate hypertensive patients. Patients with substantial renal insufficiency may have pre-existing intrinsic renal disease.

Consumer involvement in nonprescription medicine purchase decisions

As self-medication with nonprescription drugs becomes increasingly popular and important in this era of escalating health care costs and growing consumer sophistication, the degree of consumer involvement in the purchase decision becomes an important factor. High involvement suggests active information-seeking behavior and, therefore, a greater likelihood of appropriate nonprescription drug use. The authors assess consumer involvement in nonprescription medicine purchase decisions and the use of expert sources of information.

Differential mortality in New York City (1988-1992). Part Two: excess mortality in the south Bronx

To display the extent of variations in mortality according to geographic regions in New York City, we have compared mortality in New York City as a whole with that of the South Bronx. Mortality records for 1988 to 1992 and 1990 US census data for New York City were linked. The 471,000 residents of the South Bronx were younger, less educated, and more likely to lack health insurance than other New Yorkers. Using age- and gender-stratified populations and mortality in New York City as standards, age-adjusted death rates and excess mortality in the South Bronx were determined. All-cause mortality in the South Bronx was 26% higher than the city as a whole. Mortality for AIDS, injury and poisoning, drug and alcohol abuse, and cardiovascular diseases were 50% to 100% higher in the South Bronx than in New York City; years of potential life lost before age 65 in the South Bronx were 41.6% and 44.2% higher for men and women, respectively, than in New York City; AIDS accounted for the largest single share of excess premature deaths (21.8%). In summary, inequalities in health status, reflected by higher mortality rates in the South Bronx, are consistent with, and perhaps caused by, lower socioeconomic status and deficient medical care among residents of this inner-city community.

Rapid multiplication of wedelia chinensis (osbeck) merr - a valuable medicinal herb

Stem-cuttings of Wedelia chinensis (Osbeck.) Merr. Were treated with different concentrations of IBA and GA. The results indicate that 100 ppm IBA treatment greatly enhances root production and quick establishment of the stem-cuttings.

Differential mortality in New York City (1988-1992). Part One: excess mortality among non-Hispanic blacks

To determine the distribution of mortality for non-Hispanic blacks and non-Hispanic whites in New York City, death certificates issued in New York City during 1988 through 1992, and the relevant 1990 US census data for New York City, have been examined. Age-adjusted death rates for blacks and whites by gender and cause of death were computed based on the US population in 1940. Also, standard mortality ratios and excess mortality were calculated using the New York City mortality rate as reference. The results showed that New York City blacks had higher age-adjusted death rates than whites regardless of cause, including stroke, AIDS, homicide, and diabetes. The rate for New York City blacks was also higher than the US total for both genders. Using New York City mortality rates as a reference, more than 80% of excess deaths in blacks occurred before age 65. Injury/poisoning was the leading cause of excess death (20.1%) in black males, while in black females, cardiovascular disease was the largest single cause of excess deaths (24.8%). The higher death rates, especially premature death, of blacks in New York City are related to conditions such as violence, substance abuse, and AIDS, for which prevention rather than medical care is the more likely solution, as well as to cardiovascular diseases, where both prevention through behavioral change, and health and medical care, can influence outcome.

The determinants of hypertension awareness, treatment, and control in an insured population

OBJECTIVES

The purpose of the study was to identify the determinants of awareness, treatment, and control of hypertension in a population with full access to medical care.

METHODS

Unionized New York City health care workers (n = 1394) with comprehensive medical insurance were screened for hypertension. Union records documenting all physician visits and prescription medications for the year before screening provided the opportunity to relate patterns of treatment to blood pressure outcomes.

RESULTS

Of the 409 employees found to have hypertension, 289 (71%) were aware of their condition and 201 (49%) had been treated, but only 51 (12%) had their blood pressure controlled at the recommended level (< 140/90 mm Hg). In a logistic regression model, the only variable of treatment associated with control was days of antihypertensive medication. The total number of physician visits was not associated with control.

CONCLUSIONS

These findings demonstrate that in conventional community settings, even in the absence of financial barriers, treatment for hypertension continues to be characterized by poor outcomes. Improving access to primary care, without changes in the nature of that care, may not substantially improve blood pressure control.

Spatial and temporal variation in carbon isotope discrimination in prairie graminoids

We present the results of a 5-year examination of variation in the stable carbon isotope composition (δ) of three C₃ graminoid species from a Sandhills prairie: Agropyron smithii, Carex heliophila and Stipa comata. Although consistent species-specific patterns for mean δ were seen, there was also significant and substantial among-year and within-season variation in δ. A smaller contribution to variation in δ came from topographic variation among sampling sites. Effects of species, year, season and topography contribute to variation in δ in an additive manner. An association between climate and δ exists that is consistent with previous work suggesting that δ reflects the interplay between photosynthetic gas exchange and plant water relations. Within the growing season, the time over which δ integrates plant response to the environment ranges from days to months.

Relation of pulse pressure and blood pressure reduction to the incidence of myocardial infarction

The prognostic value of pretreatment pulse pressure as a predictor of myocardial infarction and the relation of pulse pressure and in-treatment diastolic blood pressure reduction to myocardial infarction were investigated in a union-sponsored systematic hypertension control program. In a prospective study, 2207 hypertensive patients with a pretreatment systolic blood pressure greater than or equal to 160 mm Hg and/or diastolic pressure greater than or equal to 95 mm Hg grouped according to tertile of pulse pressure (PP1, < or = 46; PP2, 47 to 62; PP3, > or = 63 mm Hg) were further stratified by the degree of diastolic fall: large (L), > or = 18; moderate (M), 7 to 17; small (S), < or = 6 mm Hg. During an average follow-up of 5 years, 132 cardiovascular events (50 myocardial infarctions, 23 strokes) were observed. Myocardial infarction rates per 1000 person-years were positively related to pulse pressure (PP1, 3.5; PP2, 2.9; PP3, 7.5; PP3 versus PP1, P = .02). Wide pulse pressure was identified as a predictor of myocardial infarction (PP3 versus [PP1 + PP2]: relative risk [RR] = 2.2, 95% confidence interval [CI] = 1.2-4.1), controlling for other known risk factors by Cox regression. A curvilinear relation (resembling a J shape) between diastolic fall and myocardial infarction was observed in patients with the widest pulse pressure, PP3 (L, 9.5; M, 3.9; S, 11.2; L versus M: RR = 2.5, 95% CI = 1.0-6.2; S versus M: RR = 2.9, 95% CI = 1.1-8.0).(ABSTRACT TRUNCATED AT 250 WORDS)

Consumers' preference and willingness to pay for pharmacist counselling for non-prescription medicines

Pharmacist counselling for non-prescription medicine purchases is one way of ensuring that these medicines are used in a safe and effective manner. Data collected as part of a larger study of information sources on non-prescription medicines were used to determine consumers' preference for pharmacist counselling for non-prescription medicine purchases, their willingness to pay for the service, and the amount they were willing to pay. A total of 458 (15.2%) consumers from six contiguous states in the U.S.A. responded to the mailed questionnaire. Of the consumers who responded, 63.4% indicated a preference for such a counselling service and, of these consumers, 20.4% indicated a willingness to pay for the service. Of the consumers who indicated a willingness to pay for pharmacist counselling for non-prescription medicines, 56.5% were willing to pay between 50 cents and $1.50, 28.2% between $1.51 and $3, and about 15.3% were willing to pay more than $3. Significant differences were noted in consumers' preference for pharmacist counselling when compared on the basis of certain consumer characteristics. Consumers who indicated a preference for pharmacist counselling for non-prescription medicines showed a significantly higher involvement in non-prescription medicine purchase decision, perceived pharmacists to be more credible, and indicated more favourable previous encounters with pharmacists than consumers who did not prefer pharmacist counselling. Consumers who consulted pharmacists and usually accepted their recommendations were also more likely to prefer pharmacist counselling for non-prescription medicines.

Ethnicity and the relationship of sodium intake to blood pressure

OBJECTIVE

To examine the impact of race on the relationship between sodium intake and blood pressure.

METHODS

We examined the blood pressure levels and 24-h urinary sodium excretion of 808 (355 Black, 453 Caucasian) union members who participated in a workplace hypertension control program. The 808 study subjects, who met the criterion for accuracy of urine collection, included 627 untreated hypertensives (systolic blood pressure > or = 160 mmHg or diastolic blood pressure > or = 95 mmHg, or both) and 181 normotensives (blood pressure < 160/95 mmHg).

RESULTS

In univariate analysis, the age-adjusted mean diastolic blood pressure levels of the Black subjects exceeded those of the Caucasian subjects at a significance level that was marginal for the male and very high for the female subjects. No differences were observed in mean systolic blood pressure between the Black and Caucasian subjects. Within each racial grouping, the subjects were grouped by sex-specific tertile of urinary sodium excretion in order to compare baseline characteristics and blood pressure levels. Small differences between the Black and Caucasian males in age-adjusted blood pressure within each urinary sodium excretion category were further diminished after adjusting for confounding factors. Significant differences between the Black and Caucasian females in age-adjusted diastolic blood pressure within each urinary sodium excretion group became non-significant when further adjusted for weight or body mass index, or both. These findings are in agreement with those observed in multiple linear regression models.

CONCLUSION

In this socio-economically homogeneous group, when confounding factors are considered, Black and Caucasian subjects have similar blood pressure levels at the same level of 24-h urinary sodium excretion. Ethnicity itself was not found to influence the relationship between sodium intake and blood pressure.

Two Sweetclover (Melilotus alba Desr.) Mutants Temperature Sensitive for Chlorophyll Expression

The nonallelic sweetclover (Melilotus alba Desr.) mutants U371 (ch10/ch10 genotype) and U372 (ch11/ch11 genotype) are derived from the U389 (+/+ genotype) parental strain. Growth of the U389 strain at a temperature of 17 or 26[deg]C results in plants normally green in appearance. The U371 and U372 mutant plants grown at 26[deg]C are slightly to moderately chlorophyll (Chl) deficient and have decreased Chl b/a ratios. Growth of the mutants at 17[deg]C results in plants severely deficient in Chl a, with markedly reduced levels of carotenoids except for violaxanthin, and with negligible amounts of Chl b or apoproteins for the light-harvesting complex of photosystem II. If mutant plants grown at 17[deg]C are transferred to 26[deg]C, during the next 20 d the amount of Chl per fresh weight will increase 5-fold and both the Chl b/a ratio and the expression of the light-harvesting complex apoproteins will progressively increase. Studies of the U371 mutant during the temperature-induced greening demonstrate progressive changes in chloroplast ultra-structure and leaf carbon isotope fractionation that parallel the increases in Chl. Changes observed in the leaf carbon isotope fractionation in the mutant suggest that, in addition to the already known effects of various abiotic factors, structural and metabolic internal factors can also influence whether the limitation in CO2 fixation is at the level of diffusion or carboxylation. Such temperature-initiated progressive greening in these and similar mutants may make them useful tools to elucidate not only the biosynthesis and assembly of the photosynthetic apparatus, but also physiological phenomena such as the influence of light-driven energy production on the overall carbon isotope fractionation during photosynthesis.