Are we satisfied with the follow-up of hypertensive and chronic kidney disease patients in outpatient clinics?

Hypertension and chronic kidney disease constitute major health problems as they are associated with increased morbidity and mortality. Large-scale clinical trials, have emphasized the need of a strict blood pressure and early recognition of kidney disease to reduce the complications. However, the rate of hypertension control seems to be low, the prevalence of hypertension and chronic kidney disease steadily increases, indicating a gap in the management of those patients. This is due either to a poor organization of the health care system or a defective patient-physician communication. This review will try to identify possible errors in the management of hypertensive and renal failure patients in outpatient clinics and to propose ways to improve prevention and control of hypertension and chronic kidney diseases in our population.

Desferrioxamine attenuates minor lung injury following surgical acute liver failure

Acute liver failure (ALF) can be complicated by lung dysfunction. The aim of this study was to test the hypothesis that inhibition of oxidative stress through iron chelation with desferrioxamine (DFX) attenuates pulmonary injury caused by ALF. 14 adult female domestic pigs were subjected to surgical devascularisation of the liver and were randomised to a study group (DFX group, n = 7), which received post-operative intravenous infusion of DFX (14.5 mg x kg(-1) x h(-1) for the first 6 h post-operatively and 2.4 mg x kg(-1) x h(-1) until completion of 24 h), and a control group (n = 7). Post-operative lung damage was evaluated by histological and bronchoalveolar lavage fluid (BALF) analysis. DFX resulted in reduced BALF protein levels and tissue phospholipase (PL)A(2) activity. Plasma malondialdehyde and BALF nitrate and nitrite concentrations were lower, while catalase activity in the lung was higher after DFX treatment. PLA(2), platelet-activating factor acetylhydrolase and total cell counts in BALF did not differ between groups. Histological examination revealed reduced alveolar collapse, pneumonocyte necrosis and total lung injury in the DFX-treated animals. DFX reduced systemic and pulmonary oxidative stress during ALF. The limited activity of PLA(2) and the attenuation of pneumonocyte necrosis could represent beneficial mechanisms by which DFX improves alveolar-capillary membrane permeability and prevents alveolar space collapse.

Basement membrane peptides: functional considerations and biomedical applications in autoimmunity

Basement membranes are specialized extracellular matrices that surround certain cell types (muscle cells, adipose cells, etc) and are present under the basal surface of cells exhibiting polarity (epithelial, endothelial and mesothelial cells). They have a unique macromolecular composition, consisting mainly of type IV collagen isoforms, laminin isoforms, entactin/nidogen, and perlecan. These components self associate and interact with each other to form networks. Other macromolecules may be found in specialized basement membranes. In this short review, the role of selected basement membrane proteins in autoimmune diseases will be highlighted. As an example, Goodpasture's syndrome will be presented and the relatively long quest for identification of the antigenic epitope on specific domains of the alpha3(IV)NC1 will be summarized. Chagas disease will be discussed as an example of laminin-mediated autoimmunity, with emphasis on the role of sugar-based antigenic epitope(s) will be presented. Immune-mediated tubulointerstitial nephritis will be introduced and the role of a synthetic peptide in detecting proximal tubule damage in acute renal failure will be discussed. Auto-immune diseases where other basement membrane macromolecules are involved will be mentioned. Finally, the importance of understanding the functions served by domains at close proximity to the antigenic epitope(s) will be highlighted.

Conformation and bioactivity. Design and discovery of novel antihypertensive drugs

Peptidomimitism is applied to the medicinal chemistry in order to synthesize drugs that devoid of the disadvantages of peptides. AT1 antagonists constitute a new generation of drugs for the treatment of hypertension designed and synthesized to mimic the C-terminal segment of Angiotensin II and to block its binding action on AT1 receptor. An effort was made to understand the molecular basis of hypertension by studying the conformational analysis of Ang II and its derivatives as well as the AT1 antagonists belonging to SARTANs class of molecules. Such studies offer the possibility to reveal the stereoelectronic factors responsible for bioactivity of AT1 antagonists and to design and synthesize new analogs. An example will be given which proves that drugs with better pharmacological and financial profiles may arise based on this rational design.

Conformational and biological studies for a pair of novel synthetic AT1 antagonists: stereoelectronic requirements for antihypertensive efficacy

One of the major systems which interferes with the disease of hypertension, is the Renin Angiotensin Aldosterone System (RAS). The octapeptide hormone angiotensin II is the active product of RAS which causes vasoconstriction when binds to the AT(1) receptor. In the last years, there has been a development of drugs which block the Angiotensin II from binding the AT(1) receptor and are called AT(1) antagonists. In an effort to comprehend their stereoelectronic features, a study has been initiated to compare the conformational properties of drugs already marketed for the treatment of hypertension and others which are designed and synthesized in our laboratory possessing structural characteristics necessary for antihypertensive activity. In this study, two synthetic non-peptide AT(1) antagonists, are structurally elucidated and their conformational properties and bioactivity are compared to the prototype and first approved drug of this category in the market; losartan (trade name: COZAAR).

Design and synthesis of thrombin receptor-derived nonpeptide mimetics utilizing a piperazine scaffold

Focal thrombus formation and vasoconstriction serve to defend vessels when vascular damage occurs, but may be detrimental when an atherosclerotic plaque is disrupted. Recently, the identification of the platelet thrombin receptor opened a new area in the development of agents that may selectively inhibit the effects of thrombin on cells, without affecting fibrin formation. In this regard, we have synthesized a number of 1,4-disubstituted piperazines which are designed to be analogues of thrombin receptor activating peptides (TRAP) and carry the pharmacophoric features of Phe and Arg residues present in the active pentapeptide SFLLR. These compounds were tested in the rat aorta relaxation assay and in platelet aggregation studies and their biological activity was consistent with a direct action on thrombin receptor. Furthermore, the structure activity relationships confirmed the importance of Phe and Arg for receptor activation and the molecular modeling revealed an intriguing relationship between their amphipathic similarity with SFLLR and their biological activity.

Murine monoclonal anti-DNA antibodies penetrate cells, bind to nuclei, and induce glomerular proliferation and proteinuria in vivo

The production of relatively high quantities of autoantibodies (autoAb) that react with DNA and other intranuclear antigens is characteristic of individuals with systemic lupus erythematosus and other autoimmune diseases. However, the capacity of these Ab to penetrate cells and induce functional perturbations in vivo is not well appreciated. To address this issue, monoclonal (m) anti-DNA Ab (mAb), derived from MRL-lpr/lpr and (NZB x SWR)F1 mice, were administered to normal mice, and the animals were examined for morphologic and functional abnormalities. A subset of five mAb produced intranuclear immunoglobulin deposits in multiple organs. Intranuclear immunoglobulin deposits were also observed after cross-linking the tissue before direct immunofluorescence and after i.v. injection of F(ab')2 fragments of one anti-DNA Ab. This phenomenon was reproducible and was only associated with this subset of autoAb. Furthermore, intranuclear deposits of anti-DNA Ab within glomeruli were associated with morphologic and functional abnormalities including: hypercellularity, epithelial foot process fusion, new fiber bundle formation within the mesangium suggestive of new collagen synthesis, and proteinuria. These results indicate that a subset of autoAb may penetrate cells in vivo to influence normal cellular and nuclear function and to contribute to functional and pathologic abnormalities in individuals with systemic lupus.

Central sympathetic stimulation produced by saline application into the nucleus tractus solitarii area of conscious rats

Hypertonic saline 4% was microinjected into the area of the nucleus tractus solitarii (NTS) of conscious rats. The experiments were designed to explore the systemic hormonal responses and the contribution of various hormones to the hypertensive effect elicited by this procedure. A mean blood pressure rise to 155 +/- 3 mmHg (as compared to 119 +/- 2 in rats receiving the same volume of equiosmolar dextrose solution, P less than 0.05) was accompanied by significant rises in plasma norepinephrine (0.556 +/- 0.128 ng/ml) and epinephrine (0.970 +/- 0.287 ng/ml) as compared to control rats receiving dextrose or control rats having only the cannula implanted, without microinjection. There was no significant change in plasma renin activity or plasma vasopressin levels, and the blood pressure rise could not be prevented or reversed by an angiotensin-converting enzyme inhibitor. The data are consistent with the hypothesis that the hypertensive response to this procedure is mainly due to an acute stimulation of central sympathetic neurons.

Intraspinal schwannoma presenting solely with rectal pain

A cauda equina schwannoma presented solely with rectal pain. The tumor was found to have infarcted and hemorrhaged. A discussion of rectal pain is included, and it is speculated that some forms of rectal pain, especially those classified as proctalgia fugax or rectal neuralgia, may be due to cauda equina tumors.

Enalaprilat in hypertensive emergencies

Enalaprilat (MK-422), an intravenously administered angiotensin-converting enzyme inhibitor, which is the parent compound of the oral angiotensin-converting enzyme inhibitor enalapril (MK-421), was studied in 11 patients with asymptomatic accelerated hypertension. Each patient received an initial intravenous dose of 1 mg, followed at one-hour intervals by enalaprilat 10 mg, furosemide 40 mg, and enalaprilat 40 mg. Six of 11 patients responded with a drop in mean arterial pressure greater than 15 mm Hg to diastolic levels below 110 mm Hg; there were four partial responders and one nonresponder. Pretreatment renins were not predictive of blood pressure response. No patient had any adverse reaction to the drug; there were no significant changes in posttreatment laboratory values. We conclude that enalaprilat is an effective, well-tolerated agent for the treatment of uncomplicated accelerated hypertension and its use does not imperil nonresponding uncomplicated patients.

alpha-Adrenoceptor agonists applied in the area of the nucleus tractus solitarii in the rat: effect of anesthesia on cardiovascular responses

We investigated the blood pressure and heart rate responses to unilateral local application of norepinephrine or clonidine in the area of the nucleus tractus solitarii (NTS) of conscious rats and rats anesthetized by 3 general anesthetics commonly used in cardiovascular research. In the conscious state, microinjection of either substance produced an immediate, sharp increase in blood pressure and decrease in heart rate with a gradual return to baseline over a period of more than 30 min. However, light ether anesthesia, nembutal, or urethane drastically reduced, abolished or even reversed the pressor effect of local microinjection of the same substance. Our results suggest that in conscious rats, the initial effect of alpha agonists in the NTS area is to modulate baroreceptor reflexes towards higher blood pressure levels and that general anesthesia may significantly alter or mask the cardiovascular responses to various experimental manipulations.

Hypertensive response to saline microinjection in the area of the nucleus tractus solitarii of the rat

We investigated the blood pressure response elicited by microinjection of various hypertonic solutions into the area of the nucleus tractus solitarii (NTS) of the brainstem, an area rich in catecholaminergic neurons. Equiosmolar solutions of NaCl, dextrose, LiCl and KCl were employed. NaCl produced a prolonged blood pressure rise; LiCl and normal saline produced a similar rise of short duration; and KCl produced epileptic-type seizures with postictal hypertension. Dextrose had no effect and neither had NaCl microinjection in areas relatively distant from the NTS. The rise in blood pressure was not reversed by a vasopressin antagonist injected systemically, but was totally abolished by systemic alpha-adrenergic blockade with phentolamine. These findings suggest that sodium can cause hypertension by direct stimulation of the central sympathetic nervous system without participation of peripheral mechanisms such as fluid volume expansion or alteration of the vascular wall.

Pilot study of the effects of the angiotensin-converting enzyme inhibitor CI-906 on patients with essential hypertension

The effects of two single doses of the new oral nonsulfhydryl angiotensin-converting enzyme (ACE) inhibitor CI-906 on blood pressure and hormone levels are described in eight subjects with essential hypertension. Starting at 0.625 mg, doses were separated by a placebo day and doubled in consecutive patients until the full effect (obtained with 5 and 10 mg) was reached, at which point the remaining patients received the same dosage. All doses, including the smallest, caused ACE suppression to less than 1 per cent of baseline lasting for least 12 hours and remaining below 30 per cent at 48 hours, accompanied by a rise in plasma renin activity (by 10.9 +/- 2.1 ng/ml/hr) and fall in aldosterone (by -12.6 +/- 2.5 ng/100 ml). However, a clinically significant, though partial and short-lived, effect on blood pressure was observed at 2.5 mg. The two highest doses produced similar effects in terms of magnitude of mean blood pressure lowering (by 26 +/- 5 and 25 +/- 2 mm Hg, respectively) and duration (varying from 12 to over 24 hours) regardless of pretreatment renin levels. There was no orthostatic hypotension, tachycardia, or other adverse reaction.