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Genjiro Kimura - One of the best experts on this subject based on the ideXlab platform.

Graham A Macgregor - One of the best experts on this subject based on the ideXlab platform.

  • rarefaction of skin capillaries in normotensive offspring of individuals with Essential Hypertension
    Heart, 2003
    Co-Authors: Tarek F Antonios, Nirmala D Markandu, Donald R. J. Singer, Peter S. Mortimer, F Rattray, Graham A Macgregor
    Abstract:

    Background: Rarefaction of skin capillaries in people with intermittent borderline Essential Hypertension suggests a primary or an early abnormality that may antedate the onset of sustained Hypertension. Objective: To compare skin capillary density in subjects with and without a family history of Essential Hypertension. Subjects: 21 normotensive individuals, one or both of whose parents had Essential Hypertension (mean age 39.3 years; blood pressure 124/79 mm Hg); 21 normotensive controls with no family history of Hypertension (age 46.3 years; blood pressure 124/78 mm Hg). Methods: The skin of the dorsum of the fingers was examined by intravital capillary microscopy before and after venous congestion at 60 mm Hg for two minutes. Results: By analysis of variance, both baseline and maximum skin capillary density were lower in subjects with a family history of Essential Hypertension than in those with no family history (baseline: 67 v 79 capillaries per field, p = 0.008; maximum: 74 v 93 capillaries per field, p < 0.0005). Conclusions: Capillary rarefaction in Essential Hypertension may occur before the increase in blood pressure and could, at least in part, reflect a primary rather than a secondary abnormality.

  • rarefaction of skin capillaries in borderline Essential Hypertension suggests an early structural abnormality
    Hypertension, 1999
    Co-Authors: Tarek F Antonios, Nirmala D Markandu, Donald R. J. Singer, Peter S. Mortimer, Graham A Macgregor
    Abstract:

    Abstract —We recently showed that rarefaction of skin capillaries in the dorsum of the fingers of patients with Essential Hypertension is due to the structural (anatomic) absence of capillaries rather than functional nonperfusion. It is not known whether this rarefaction is primary (ie, antedates the onset of Hypertension) or secondary (ie, as a consequence of sustained and prolonged elevation of blood pressure [BP]). The aim of the present investigation was to study skin capillary density in a group of patients with mild borderline Hypertension to assess whether rarefaction antedates the onset of sustained elevation of BP. The study group included 18 patients with mild borderline Hypertension (mean supine BP, 136/83 mm Hg), 32 normotensive controls (mean BP, 126/77 mm Hg), and 45 patients with established Essential Hypertension (mean BP, 156/98 mm Hg). The skin of the dorsum of the fingers was examined by intravital capillary videomicroscopy before and after venous congestion at 60 mm Hg for 2 minutes. Patients with borderline Essential Hypertension had the lowest resting capillary density when compared with normotensive controls and patients with established Hypertension. Maximal capillary density with venous congestion in the borderline group remained the lowest. The study confirmed that patients with borderline Essential Hypertension have skin capillary densities that are equally low as or even lower than patients with established Hypertension. Both groups had significantly lower capillary densities than normal controls. One explanation for the results is that capillary rarefaction may be due to an early structural abnormality in Essential Hypertension.

  • Structural skin capillary rarefaction in Essential Hypertension.
    Hypertension (Dallas Tex. : 1979), 1999
    Co-Authors: Tarek F Antonios, Nirmala D Markandu, Donald R. J. Singer, Peter S. Mortimer, Graham A Macgregor
    Abstract:

    A reduction in the density of capillaries (rarefaction) is known to occur in many tissues in patients with Essential Hypertension. This rarefaction may play a role in increasing peripheral resistance. However, the mechanism underlying this capillary rarefaction is not understood. The aim of this study was to assess the extent of structural versus functional capillary rarefaction in the skin of dorsum of fingers in Essential Hypertension. The capillary microcirculation was examined with video microscopy before and after maximizing the number of perfused capillaries by venous congestion. The study group comprised 17 patients with Essential Hypertension (mean supine blood pressure, 155/96 mm Hg) and 17 closely matched normotensive controls (mean blood pressure, 127/77 mm Hg). We used intravital video microscopy with an epi-illuminated microscope to examine the skin of the dorsum of left middle phalanx before and after venous congestion at 60 mm Hg for 2 minutes. A significantly lower mean capillary density occurred at baseline in hypertensive subjects versus normotensive subjects. With venous occlusion, capillary density increased significantly in both groups; however, maximal capillary density remained significantly lower in the hypertensive subjects than in the normotensive subjects. The study strongly suggests that much of the reduction in capillary density in the hypertensive subjects is caused by structural (anatomic) absence of capillaries rather than functional nonperfusion.

Peter S. Mortimer - One of the best experts on this subject based on the ideXlab platform.

  • rarefaction of skin capillaries in normotensive offspring of individuals with Essential Hypertension
    Heart, 2003
    Co-Authors: Tarek F Antonios, Nirmala D Markandu, Donald R. J. Singer, Peter S. Mortimer, F Rattray, Graham A Macgregor
    Abstract:

    Background: Rarefaction of skin capillaries in people with intermittent borderline Essential Hypertension suggests a primary or an early abnormality that may antedate the onset of sustained Hypertension. Objective: To compare skin capillary density in subjects with and without a family history of Essential Hypertension. Subjects: 21 normotensive individuals, one or both of whose parents had Essential Hypertension (mean age 39.3 years; blood pressure 124/79 mm Hg); 21 normotensive controls with no family history of Hypertension (age 46.3 years; blood pressure 124/78 mm Hg). Methods: The skin of the dorsum of the fingers was examined by intravital capillary microscopy before and after venous congestion at 60 mm Hg for two minutes. Results: By analysis of variance, both baseline and maximum skin capillary density were lower in subjects with a family history of Essential Hypertension than in those with no family history (baseline: 67 v 79 capillaries per field, p = 0.008; maximum: 74 v 93 capillaries per field, p < 0.0005). Conclusions: Capillary rarefaction in Essential Hypertension may occur before the increase in blood pressure and could, at least in part, reflect a primary rather than a secondary abnormality.

  • rarefaction of skin capillaries in borderline Essential Hypertension suggests an early structural abnormality
    Hypertension, 1999
    Co-Authors: Tarek F Antonios, Nirmala D Markandu, Donald R. J. Singer, Peter S. Mortimer, Graham A Macgregor
    Abstract:

    Abstract —We recently showed that rarefaction of skin capillaries in the dorsum of the fingers of patients with Essential Hypertension is due to the structural (anatomic) absence of capillaries rather than functional nonperfusion. It is not known whether this rarefaction is primary (ie, antedates the onset of Hypertension) or secondary (ie, as a consequence of sustained and prolonged elevation of blood pressure [BP]). The aim of the present investigation was to study skin capillary density in a group of patients with mild borderline Hypertension to assess whether rarefaction antedates the onset of sustained elevation of BP. The study group included 18 patients with mild borderline Hypertension (mean supine BP, 136/83 mm Hg), 32 normotensive controls (mean BP, 126/77 mm Hg), and 45 patients with established Essential Hypertension (mean BP, 156/98 mm Hg). The skin of the dorsum of the fingers was examined by intravital capillary videomicroscopy before and after venous congestion at 60 mm Hg for 2 minutes. Patients with borderline Essential Hypertension had the lowest resting capillary density when compared with normotensive controls and patients with established Hypertension. Maximal capillary density with venous congestion in the borderline group remained the lowest. The study confirmed that patients with borderline Essential Hypertension have skin capillary densities that are equally low as or even lower than patients with established Hypertension. Both groups had significantly lower capillary densities than normal controls. One explanation for the results is that capillary rarefaction may be due to an early structural abnormality in Essential Hypertension.

  • Structural skin capillary rarefaction in Essential Hypertension.
    Hypertension (Dallas Tex. : 1979), 1999
    Co-Authors: Tarek F Antonios, Nirmala D Markandu, Donald R. J. Singer, Peter S. Mortimer, Graham A Macgregor
    Abstract:

    A reduction in the density of capillaries (rarefaction) is known to occur in many tissues in patients with Essential Hypertension. This rarefaction may play a role in increasing peripheral resistance. However, the mechanism underlying this capillary rarefaction is not understood. The aim of this study was to assess the extent of structural versus functional capillary rarefaction in the skin of dorsum of fingers in Essential Hypertension. The capillary microcirculation was examined with video microscopy before and after maximizing the number of perfused capillaries by venous congestion. The study group comprised 17 patients with Essential Hypertension (mean supine blood pressure, 155/96 mm Hg) and 17 closely matched normotensive controls (mean blood pressure, 127/77 mm Hg). We used intravital video microscopy with an epi-illuminated microscope to examine the skin of the dorsum of left middle phalanx before and after venous congestion at 60 mm Hg for 2 minutes. A significantly lower mean capillary density occurred at baseline in hypertensive subjects versus normotensive subjects. With venous occlusion, capillary density increased significantly in both groups; however, maximal capillary density remained significantly lower in the hypertensive subjects than in the normotensive subjects. The study strongly suggests that much of the reduction in capillary density in the hypertensive subjects is caused by structural (anatomic) absence of capillaries rather than functional nonperfusion.

  • Capillary rarefaction in the forearm skin in Essential Hypertension
    Journal of hypertension, 1995
    Co-Authors: Abhiram Prasad, Giles S. Dunnill, Peter S. Mortimer
    Abstract:

    OBJECTIVE To determine whether there is a reduction in human forearm skin capillary density in Essential Hypertension. SUBJECTS AND METHODS We compared the number of capillary loops in the forearm skin of 12 patients with established, uncomplicated Essential Hypertension (mean blood pressure 180/109 mmHg) with that in carefully matched control subjects, using intravital capillaroscopy and fluorescein angiography. RESULTS There was a significant reduction in forearm skin capillary density in the hypertensive patients compared with the normotensive subjects. This represents a reduction by approximately 20% in capillary density. Capillary density was inversely correlated with blood pressure in the hypertensive patients alone (r = -0.4, P < 0.05) and in the whole group. CONCLUSION The present study demonstrates a reduction in capillary density in the forearm of patients with Essential Hypertension. If this rarefaction in the forearm is also present in other vascular beds, it could result in an approximately 20% increase in peripheral resistance, which might play an important additional role in determining blood pressure.

Xavier Jeunemaitre - One of the best experts on this subject based on the ideXlab platform.

  • seven lessons from two candidate genes in human Essential Hypertension angiotensinogen and epithelial sodium channel
    Hypertension, 1999
    Co-Authors: Pierre Corvol, Alexandre Persu, Annepaule Gimenezroqueplo, Xavier Jeunemaitre
    Abstract:

    Abstract —The candidate gene approach to understanding the genetics of human Essential Hypertension is discussed by analyzing the contribution of 2 genes, angiotensinogen (AGT) and epithelial amiloride-sensitive sodium channel (ENaC). From a large series of studies conducted in humans and animals, it appears that the AGT gene plays a significant but modest role in human blood pressure variance. Mutations of the β- and γ-ENaC subunits are responsible for Liddle’s syndrome, but the implication of the 3 ENaC subunits in Essential Hypertension is still questionable. Several lessons can be learned from these studies and applied to other candidate genes in Essential Hypertension: (1) Many linkage or association studies have a limited statistical power; (2) The genetic findings may vary greatly according to the populations studied; (3) There is a need for better phenotyping of the hypertensive population; (4) The causal relationship between molecular variants and Hypertension is and will be difficult to establish firmly; (5) The contribution of genetic studied in rodents to the molecular genetics of human Hypertension must be re-examined; (6) Most molecular variants lead to a low attributable risk in the population or a low individual effect at the individual level; and (7) It is too early to propose dietary recommendations and specific drug treatment according to patients’ genotypes.

  • seven lessons from two candidate genes in human Essential Hypertension angiotensinogen and epithelial sodium channel
    Hypertension, 1999
    Co-Authors: Pierre Corvol, Alexandre Persu, Annepaule Gimenezroqueplo, Xavier Jeunemaitre
    Abstract:

    Abstract —The candidate gene approach to understanding the genetics of human Essential Hypertension is discussed by analyzing the contribution of 2 genes, angiotensinogen (AGT) and epithelial amiloride-sensitive sodium channel (ENaC). From a large series of studies conducted in humans and animals, it appears that the AGT gene plays a significant but modest role in human blood pressure variance. Mutations of the β- and γ-ENaC subunits are responsible for Liddle’s syndrome, but the implication of the 3 ENaC subunits in Essential Hypertension is still questionable. Several lessons can be learned from these studies and applied to other candidate genes in Essential Hypertension: (1) Many linkage or association studies have a limited statistical power; (2) The genetic findings may vary greatly according to the populations studied; (3) There is a need for better phenotyping of the hypertensive population; (4) The causal relationship between molecular variants and Hypertension is and will be difficult to establish firmly; (5) The contribution of genetic studied in rodents to the molecular genetics of human Hypertension must be re-examined; (6) Most molecular variants lead to a low attributable risk in the population or a low individual effect at the individual level; and (7) It is too early to propose dietary recommendations and specific drug treatment according to patients’ genotypes.

Takashi Uzu - One of the best experts on this subject based on the ideXlab platform.