Genetic structure and first genome-wide insights into the adaptation of a wild relative of grapevine, Vitis berlandieri

In grafted plants, such as grapevine, increasing the diversity of rootstocks available to growers is an ideal strategy for helping plants to adapt to climate change. The rootstocks used for grapevine are hybrids of various American Vitis, including V. berlandieri. The rootstocks currently use in vineyards are derived from breeding programs involving very small numbers of parental individuals. We investigated the structure of a natural population of V. berlandieri and the association of genetic diversity with environmental variables. In this study, we collected seeds from 78 wild V. berlandieri plants in Texas after open fertilization. We genotyped 286 individuals to describe the structure of the population, and environmental information collected at the sampling site made it possible to perform genome-environment association analysis (GEA). De novo long-read whole-genome sequencing was performed on V. berlandieri and a STRUCTURE analysis was performed. We identified and filtered 104,378 SNPs. We found that there were two subpopulations associated with differences in elevation, temperature, and rainfall between sampling sites. GEA identified three QTL for elevation and 15 QTL for PCA coordinates based on environmental parameter variability. This original study is the first GEA study to be performed on a population of grapevines sampled in natural conditions. Our results shed new light on rootstock genetics and could open up possibilities for introducing greater diversity into genetic improvement programs for grapevine rootstocks.

Drought activates MYB41 orthologs and induces suberization of grapevine fine roots

The permeability of roots to water and nutrients is controlled through a variety of mechanisms and one of the most conspicuous is the presence of the Casparian strips and suberin lamellae. Roots actively regulate the creation of these structures developmentally, along the length of the root, and in response to the environment, including drought. In the current study, we characterized the suberin composition along the length of grapevine fine roots during development and in response to water deficit, and in the same root systems we quantified changes in expression of suberin biosynthesis- and deposition-related gene families (via RNAseq) allowing the identification of drought-responsive suberin-related genes. Grapevine suberin composition did not differ between primary and lateral roots, and was similar to that of other species. Under water deficit there was a global upregulation of suberin biosynthesis which resulted in an increase of suberin specific monomers, but without changes in their relative abundances, and this upregulation took place across all the developmental stages of fine roots. These changes corresponded to the upregulation of numerous suberin biosynthesis- and export-related genes which included orthologs of the previously characterized AtMYB41 transcriptional factor. Functional validation of two grapevine MYB41 orthologs, VriMYB41 and VriMYB41-like, confirmed their ability to globally upregulate suberin biosynthesis, export, and deposition. This study provides a detailed characterization of the developmental and water deficit induced suberization of grapevine fine roots and identifies important orthologs responsible for suberin biosynthesis, export, and its regulation in grape.

[Relationship of white matter lesions on brain computed tomography and cognitive function in elderly subjects with mild cognitive impairment]

White matter lesions (WML) are frequently disclosed on elderly people computed tomography (CT) brain scan.

OBJECTIVE

To evaluate the relationship between WML and cognitive functions of patients suffering from Mild Cognitive Impairment (MCI).

METHODS

We studied the association between WML on CT brain scan and cognitive functions in 136 consecutive elderly subjects attending a geriatric outpatient clinic, suffering from MCI. The global cognitive assessment was based on Mini Mental State Examination (MMSE), a validated comprehensive battery of neuropsychological tests, the Cognitive Efficiency Profile (CEP), a CT brain scan and a complete biological screening. WML on CT brain scan was evaluated by a blinded investigator.

RESULTS

In this population, 75 +/- 8 years of age, (women 60%, and hypertension 54%), 33% of subjects had WML on CT brain scan. Patients with WML were significantly older (OR=1.27; IC 95%=1.04 - 1.22), had more frequently a past history of hypertension (OR=2.71; IC 95%=1.06 - 6.96) and more frequently lacunae associated with WML (OR=4.48; IC 95%=1.18 - 16.99). Subjects with WML had significantly poorer cognitive functions than those without WML (CEP score/100=62.33 +/- 13.58 versus 71.87 +/- 14.19, p<0.01 and MMSE score/30=27.02 +/- 2.34 versus 27.97 +/- 1.89, p<0.01)

CONCLUSION

Our results showed a relationship between WML on CT brain scan and the depth of cognitive dysfunction among MCI patients. Further long term prospective studies have to be performed to determinate if WML are involved in transitions between MCI and Alzheimer' s disease.

Assessing vascular dementia

Vascular dementia is the most common cause of dementia in the elderly after Alzheimer's disease. Many forms of vascular dementia have been described: multi-infarct dementia, lacunar dementia, Binswanger's subcortical encephalopathy, cerebral amyloid angiopathy, white matter lesions associated with dementias, single infarct dementia, dementia linked to hypoperfusion and haemorrhagic dementia. The difficulty of diagnosing vascular dementia must not be underestimated and an international consensus is needed for epidemiological studies. The NINCDS-AIREN group has recently published diagnostic criteria. The State of California Alzheimer's Disease Diagnostic and Treatment Centers also proposed some which differ from the NINCDS-AIREN criteria in considering only ischaemic vascular dementia and not other mechanisms such as haemorrhagic or hypoxic lesions. Most studies stress hypertension as the most powerful risk factor for all forms of vascular dementia. The incidence rate ranges from 7 per 1000 person-years in normal volunteers to 16 per 1000 person-years in hypertensive patients. No therapeutic attempt has influenced the course of the disease once the dementing condition is established. The only effective approach is preventive treatment. The objective of the SYST-EUR Vascular Dementia project is to confirm that the treatment of isolated systolic hypertension is able to reduce its incidence.

Are calcium antagonists the best option in elderly hypertensives?

SUITABILITY OF CALCIUM ANTAGONISTS FOR THE ELDERLY: The efficacy and safety of calcium antagonists have been clearly demonstrated in elderly hypertensive patients. In a double-blind placebo-controlled study in 31 elderly hypertensives treated with nicardipine, we found no consistent electrocardiogram changes, nor in the heart rate, plasma levels of potassium, sodium or creatinine, or uric acid; nor did we find any postural hypotension. The mechanism of action of this class of drugs appears to be particularly appropriate in the treatment of elderly patients, in whom hypertension is characterized by an increase in peripheral resistance and a decrease in arterial compliance. Since vascular tone is ultimately controlled by the intracellular calcium concentration in smooth muscles, agents such as calcium inhibitors, which inhibit calcium influx and induce dilation of small and large arteries, are of particular interest. EXPERIMENTAL EVIDENCE: There is some experimental evidence in hypertensive rats and hypercholesterolaemic rabbits that calcium antagonists can provide some protection against atherosclerotic degeneration. However, the validity of extrapolating these findings to humans is still disputed. POSSIBLE CEREBRAL EFFECT: Calcium antagonists might also have a beneficial cerebral effect. The acute administration of these drugs has been shown to increase cerebral blood flow. Moreover, several studies have shown a protective action against cerebral ischaemia and this may be of particular importance in the very elderly.

[Treatment of arterial hypertension in elderly patients. Value and indications]

The prevalence of high blood pressure increases with age and, in elderly subjects, it is a major risk factor not only for cardiovascular diseases but also for other diseases including vascular dementia. Data concerning mortality are more controversial, but it is known that up to the age of 90, mortality is increased in hypertensive subjects. Two pathological conditions can be distinguished, systolo-diastolic hypertension with a systolic pressure above 160 mmHg and diastolic pressure above 95 mmHg and systolic hypertension alone when the systolic pressure is above 160 mmHg and diastolic below 95 (or 90) mmHg. The European working party on high blood pressure in the elderly (EWPHE) and the Medical Research Council trial of treatment of hypertension in older adults have demonstrated the beneficial effect of treating systolo-diastolic hypertension. Active therapy significantly reduces the risk of mortality due to cardiovascular disease, notably myocardial infarction, and in morbidity due to left ventricular failure and non-mortal cerebral vascular events. The current debate centers on the pressure level which should be attained, especially in patients with a history of ischaemic cardiopathy. Treatment of elderly patients with systolic hypertension alone is also probably beneficial, although only the systolic hypertension in the elderly program (SHEP) was able to demonstrate a significant reduction in cerebral vascular events and in the incidence of myocardial infarction, even in subjects over 80. A multicentric European study (Syst-Eur), which includes patients treated with calcium inhibiteurs and conversion enzyme inhibiteurs, is being conducted in order to confirm the beneficial effect of treating systolic hypertension in subjects over 60. In addition, this study also includes a complementary project specifically designed to evaluate the effect of treatment on vascular dementia.

Antihypertensive therapy in elderly patients with isolated systolic hypertension: third progress report of the Syst-Eur trial

The Syst-Eur trial is a randomised, double-blind, placebo-controlled trial that examines the hypothesis that antihypertensive treatment can prevent or delay cardiovascular complications in elderly patients (> 60 years) with isolated systolic hypertension. On March, 1st 1993 a total of 1395 patients with a sitting systolic blood pressure on placebo averaging 160-219 mmHg and a diastolic blood pressure < 95 mmHg were randomised into this trial. The placebo and active treatment groups were similar at randomisation with respect to age (72 +/- 7 years, mean +/- SD), percentage of women (68%), percentage of patients with cardiovascular complications (30%) and sitting blood pressures (175 +/- 12/85 +/- 6 mmHg). The fall in sitting systolic and diastolic blood pressures from baseline to 2 years was significantly more pronounced (p < 0.001) in the actively treated (-22 +/- 18/-6 +/- 9 mmHg) as compared with the placebo treated Syst-Eur patients (-10 +/- 20/-1 +/- 9 mmHg). Active treatment consists of nitrendipine if necessary associated with a converting-enzyme inhibitor and a thiazide. Whether treatment with these antihypertensive agents results in a clinically meaningful reduction of cardiovascular morbidity and mortality is the subject of investigation in this trial.

Nitrendipine in older patients with isolated systolic hypertension: second progress report on the SYST-EUR trial

This report from the double-blind placebo-controlled SYST-EUR trial investigated whether modern antihypertensive drugs are suitable for maintaining long-term BP control in older (> or = 60 years of age) subjects with isolated systolic hypertension (SBP 160-219 mmHg and DBP < 95 mmHg). Active treatment consisted of nitredipine (10-40 mg/day) with the possible addition of enalapril (5-20 mg/day) and hydrochlorothiazide (12.5-25 mg/day), if necessary to reduce SBP to < 150 mmHg and by > or = 20 mmHg. Matching placebos were used in the control group. This analysis was restricted to 18 months of follow-up. The placebo (n = 456) and active treatment (n = 485) groups had similar characteristics at randomisation (sitting pressure 176/85 mmHg; age 73 years). SBP fell (P < 0.001) on average 10 mmHg more on active treatment than on placebo and DBP 4 mmHg more. Fewer patients remained on monotherapy in the placebo than in the active treatment group (P < 0.001); on placebo the second and third line medications were started earlier (P < 0.001). Nitrendipine tablets were discontinued in nine patients on placebo and in 29 patients assigned to active treatment (P < 0.001). In conclusion, a significant BP reduction can be achieved and maintained in older patients with isolated systolic hypertension treated with a calcium antagonist (associated with a converting-enzyme inhibitor and a thiazide, where necessary). Whether this BP reduction results in a clinically meaningful decrease of cardiovascular complications is under investigation.

[Prevention of pathological aging. The arterial hypertension example]

Studies conducted during the last decade have made it increasingly easier to distinguish between normal and pathological ageing. Previous studies on general populations had established a dogma: most of the major body functions, such as cardiac output, glomerular clearance, muscular strength, visual acuity and so forth, were supposed to decline with age. However, in recent studies on the effects of age on cardiac output all subjects with heart disease were excluded and as a result the negative correlation found between cardiac output and age disappeared, which shows that a phenomenon attributed to ageing was in fact caused by disease. This does not mean that there is no such thing as fundamental ageing, and indeed the mechanisms that maintain cardiac output are different in young and elderly subjects. These data are of more than theoretical interest, since it may be presumed that prevention, the instruments of which are already available in some fields, will modify the profile of ageing. The risk of arterial hypertension is not restricted to the classical cardiovascular diseases: it extends to other diseases, such as vascular dementia, which are potent factors of pathological ageing. Most of the controlled trials carried out in arterial hypertension have demonstrated that treating certain types of hypertension significantly reduces the morbidity and/or mortality of cardiovascular diseases. The specific properties of new antihypertensive drugs, such as angiotensin-converting enzyme inhibitors, open stimulating vistas on arterial ageing.

Is prevention of vascular dementia possible? The Syst-Eur Vascular Dementia Project

Vascular dementia (VD) is the second most common cause of dementia in the elderly after Alzheimer's disease (AD). Prevalence estimates from community surveys indicate that, on average, 5% of persons over 65 and 15 to 20% of people over 80 suffer from "severe dementia". Clinico-pathological studies have shown that AD accounts for 50 to 60% of the cases and VD for about 10 to 20%; 20% of the patients have both disorders. The incidence rate of VD ranges from 7 per 1,000 person-years in normal volunteers to 16 per 1,000 person-years in subjects with risk factors for strokes, particularly high blood pressure. The only effective therapeutic approach to VD is the prevention of strokes, mainly through the treatment of hypertension; however, none of the therapeutic trials has included VD prevention as one of its treatment goals. Syst-Eur Study is a European placebo controlled trial which aims to determine whether morbidity and mortality are changed when elderly patients (60 years and over) with isolated systolic hypertension are treated. In this trial, the incidence of VD will be carefully recorded during the five year follow-up of the expected 3,000 patients. The present side project to the Syst-Eur trial will specifically address the following questions: does antihypertensive treatment reduce the incidence of VD?, and how do the cognitive functions of elderly patients change when treated with active or placebo treatment? The protocol is based on the administration of the MMS (Folstein) once a year to all patients. If the MMS score is 23 or less, a set of criteria will be used to establish the diagnosis of vascular dementia. A pilot study has demonstrated the feasibility of the trial. The main study is in progress.