Polymorphisms of the angiotensinogen gene and the outcome of microalbuminuria in essential hypertension: a 3-year follow-up study

BACKGROUND

The objective of this study was to analyse the relationship of polymorphisms of the angiotensinogen (AGT) gene with the changes in microalbuminuria during 3 years of antihypertensive treatment in a group of young adults with essential hypertension.

METHODS

Essential hypertensives, less than 50 years old, never previously treated with antihypertensive drugs and in the absence of diabetes mellitus were included. After the initial evaluation, patients were treated using only nonpharmacological measures (n=23), only beta-blockers (n=26), only angiotensin-converting enzyme inhibitors (ACEi) (n=57) or a combination of treatments (n=25). The office blood pressure, biochemical profile and urinary albumin excretion (UAE) were measured at the beginning and then yearly. The polymorphism A-6G of the AGT gene located in the promoter region was analysed.

RESULTS

In total, 131 patients, 35 (27%) microalbuminurics, were included. Although no significant differences in systolic blood pressure (SBP), diastolic blood pressure (DBP), fasting glucose and UAE were observed among genotypes at the initial examination, during the 3 years of antihypertensive treatment the slope values for the DBP, fasting glucose and UAE differed significantly despite no differences in the distribution of treatments being present. The subjects carrying the AA-6 genotype had the largest DBP decrease, but the lowest UAE reduction and the highest slope of glucose. Out of 35 initially microalbuminuric patients, 24 became normoalbuminuric and the lowest reduction rates were observed in subjects who carried the allele A-6. No interaction between the type of treatment and genotype was observed on the changes in UAE, BP or glucose values. In the subset of 57 patients treated with ACEi, the changes in UAE, BP and glucose had the same trend as was observed in the total population.

CONCLUSIONS

Subjects carrying the AA genotype of the A-6G AGT gene polymorphism are resistant to a reduction of microalbuminuria. Whether this can be attributed to a predisposition to glucose metabolic disturbance or not needs to be confirmed in further studies.

[Cerebral palsy: prenatal risk factors]

Prenatal risk factors causing cerebral palsy (CP), here defined as a non-progressive motor abnormality of tone or posture, are much more numerous than once believed, when a great deal of brain injury was attributed to factors surrounding delivery. Scientific advances in genetics and biochemistry, as well as clinical technical advances in, for example, amniotic fluid examination or fetal neuroimaging, has permitted us to find a multiplicity of new etiologies causing neonatal encephalopathy, most of which were formerly attributed to perinatal hypoxia-ischemia. This article reviews an expanded list of etiologies, including asphyxia, which has been found to cause only 6-10% of CP in full term infants, and periventricular leukomalacia, which is associated with 30-50% of CP in premature births. We also review a few of the genetic causes of CP, which lead to metabolic encephalopathies in come cases, to congenital anomalies in others, and sometimes to both. We discuss maternal gestational or intrapartum infections which may affect the fetus by direct in utero contagion or by other less direct means. Inborn metabolic errors affecting the fetus, such as diabetes, are touched on, as are the effects of maternal medications or recreational drugs on the fetus. Finally, we briefly cite the curious phenomenon occurring in multiple births, namely the potential of CP in the surviving infant or infants were the others have died in utero.

[The role of the extra-intracranial anastomosis and interventionist endovascular therapy in the treatment of complex cerebral aneurysms]

Cerebral revascularization is an useful tool in the treatment of giant or complex cerebral aneurysms that can not be clipped directly by different causes. In turn, interventionist endovascular therapy, an emergent technique with very good results in the treatment of cerebral aneurysms during the last five years, is a new complementary tool to cerebral revascularization for the treatment of complex aneurysms. In the present manuscript we emphasize the beneficial effect of revascularization, followed in a short period of time by the endovascular technique in order to either occlude the parent vessel or to exclude the aneurysm from cerebral circulation. Advantages of this form of therapy, as well as the selection of patients and the present revascularization procedures, are commented.

[Anatomic and hemodynamic study of anterior communicating artery complex]

Anterior communicating artery complex accounts for the most frequent site of cerebral aneurysms and it is characterized by its great anatomical variability. The development of aneurysms in this complex has been associated with the asymmetry of its afferent vessels. An anatomical and hemodynamic study of the anterior communicating artery was performed. Twenty brain samples obtained from adult necropsies were studied by means of microsurgical dissection. Additionally; 118 cerebral angiographies from patients with spontaneous subarachnoid hemorrhage were studied. A high number of perforanting vessels originated at the anterior communicating artery complex was a relevant finding. The number, distribution and size of these vessels is reported accurately. Analysis of the angiographies showed the association between the existence of an anterior communicating artery aneurysm and the presence of a blood flow predominance through one of the two proximal anterior cerebral arterias.

Primary hypothalamic-third ventricle lymphoma. Case report and review of the literature

Primary central nervous system lymphomas (PCNSL) are infrequent tumors and their presentation as a solitary hypothalamic-third ventricle mass can be considered exceptional. We report the case of a 57-year-old woman with progressive visual deterioration, diabetes insipidus and mental confusion. She had a diffuse and homogeneous tumoral lesion involving the third ventricle and the adjacent hypothalamic area with marked enhancement after contrast administration on both, competed tomography scan and magnetic resonance images. It was approached and partially resected by the translamina terminalis route. Histological diagnosis proved to be a diffuse non-Hodgkin lymphoma and the patient subsequently was treated with adjuvant radiotherapy and chemotherapy. Followup examination showed visual acuity recover but persistent confessional state. Eight similar well described cases reported in the literature are reviewed with a description of the major diffenciating features of this neurological entity. Treatment of PCNSL remains a challenge, and the topographical location within the hypothalamic-third ventricle area is even more complex.

[Neonatal myasthenic syndromes]

INTRODUCTION

In the newborn, myasthenia can present either as transient neonatal myasthenia or as a congenital syndrome. At present at least 8 syndromes involving neonatal neuromuscular junction (NMJ) malfunction have been described; one caused by the passage of transplacental antibodies from mother to child, while all but one of the rest are inherited. Inheritance in all but two syndromes is autosomal recessive. One is an autosomal dominantly inherited illness; in another the mode of inheritance is not clear. The deficit in function of the NMJ is presynaptic in 3 instances, at the junctional gap in 1, and postsynaptic in at least 3 other syndromes.

DEVELOPMENT

We will review the clinical symptoms, as well as neurophysiologic and genetic testing available for diagnosis. We explain how, at least, in some of the syndromes, one can begin appropriate therapy based on clinical, neurophysiological and simple pharmacological testing.

CONCLUSION

However, in many cases, it becomes necessary to refer the patient or a tissue sample, usually an intercostal nerve muscle preparation, to one of the very few centers in the world where in vitro neurophysiologic, microstructural and genetic procedures leading to a more precise diagnosis can be performed.

[Renin-angiotensin system genetic polymorphisms and essential hypertension in the Spanish population]

BACKGROUND

The goal of this study was to analyse the association between essential hypertension and the main genetic polymorphisms at the renin-angiotensin system in the Spanish population.

PATIENTS AND METHOD

Case-control study including 185 essential hypertensive subjects(age [SD] 39.6 [7.5] years, 52% women, systolic blood pressure 151.2 [17.4] mmHg, diastolic blood pressure 96.0 [9.4] mmHg) and 350 sex- and age-matched normotensive individuals selected from a sample of the general population of the Comunidad Valenciana, Spain (age 39.4 [8.0] years, 51.7% women, systolic blood pressure 116.0 [12.0] mmHg, diastolic blood pressure 69.6 [8.5] mmHg). A PCR was performed to determine I/D angiotensin converting enzyme (ACE) gene polymorphism, A-6G and M235T angiotensinogen gene polymorphism and A1166C polymorphism of the angiotensin II type 1 receptor.

RESULTS

There were no differences between cases and controls with regard to genotypic and allelic distributions. In hypertensive patients,there were no differences in genotypic or allelic distributions after considering the presence or absence of a familial history of hypertension or comparing tertiles of systolic and diastolic blood pressure values. Only in women, the combination of a C allele of A1166C polymorphism with an A-6G angiotensinogen polymorphism A allele (p = 0.007), or an M235T angiotensinogen polymorphism T allele (p = 0.007), was associated with a higher risk of hypertension.

CONCLUSIONS

We found no association between essential hypertension risk and I/D ACE gene, M235T and A-6G angiotensinogen gene, or A1166C angiotensin II type 1 receptor gene polymorphisms. An epistatic effect was observed in young women between angiotensin II type 1 receptor polymorphisms and angiotensinogen polymorphisms.

Autosomal dominant glut-1 deficiency syndrome and familial epilepsy

Glut-1 deficiency syndrome was first described in 1991 as a sporadic clinical condition, later shown to be the result of haploinsufficiency. We now report a family with Glut-1 deficiency syndrome affecting 5 members over 3 generations. The syndrome behaves as an autosomal dominant condition. Affected family members manifested mild to severe seizures, developmental delay, ataxia, hypoglycorrhachia, and decreased erythrocyte 3-O-methyl-D-glucose uptake. Seizure frequency and severity were aggravated by fasting, and responded to a carbohydrate load. Glut-1 immunoreactivity in erythrocyte membranes was normal. A heterozygous R126H missense mutation was identified in the 3 patients available for testing, 2 brothers (Generation 3) and their mother (Generation 2). The sister and her father were clinically and genotypically normal. In vitro mutagenesis studies in Xenopus laevis oocytes demonstrated significant decreases in the transport of 3-O-methyl-D-glucose and dehydroascorbic acid. Xenopus oocyte membranes expressed high amounts of the R126H mutant Glut-1. Kinetic analysis indicated that replacement of arginine-126 by histidine in the mutant Glut-1 resulted in a lower Vmax. These studies demonstrate the pathogenicity of the R126H missense mutation and transmission of Glut-1 deficiency syndrome as an autosomal dominant trait.

The spectrum of circadian blood pressure changes in type I diabetic patients

BACKGROUND

The objective of the present study was to characterize the spectrum of circadian blood pressure changes in type I diabetes at different stages of nephropathy by using two monitorings in each patient in order to avoid intra-individual variability.

PATIENTS AND METHODS

A total of 80 type I diabetic subjects and the same number of age, sex and awake mean blood pressure (BP)-matched controls were included. According to urinary albumin excretion, there were 57 normoalbuminurics, 15 persistent microalbuminurics and eight proteinurics. Two 24 h ambulatory blood pressure monitorings were performed at the same urinary albumin excretion stage in absence of antihypertensive treatment for each diabetic subject and for their respective control. Blood pressure and heart rate averages during 24 h, awake, sleep, and day: night ratio were calculated.

RESULTS

Seven of the eight proteinuric subjects were hypertensives, whereas hypertension was absent in the normoalbuminuric and microalbuminuric groups. The intraindividual reproducibility in diabetics showed repeatability coefficients for the 24 h systolic and diastolic pressure of 33 and 42%, respectively. This reproducibility for the day: night ratio was generally worse, 57% for systolic and 59% for diastolic. A progressive increment in the mean ambulatory BP was observed across the three groups of diabetics and the differences in BP observed were most evident during the night-time period. Though no differences in the 24 h circadian pattern were present between the normoalbuminurics and their controls, nocturnal differences were observed, not only in microalbuminurics for systolic BP (P < 0.05), but also in proteinurics for both systolic BP (P < 0.01) as well as diastolic BP (P < 0.05). No differences were observed in heart rate among the diabetic groups. The non-dipping pattern in the two monitorings was observed in 80, 58, 18 and 10% of the proteinurics, microalbuminurics, normoalbuminurics and control groups, respectively.

CONCLUSIONS

Persistent abnormal circadian variability seems to be an early and frequent characteristic of type I diabetics with an increased urinary albumin excretion. Although present in some normalbuminuric subjects, the frequency of this abnormality increases as the incipient nephropathy progresses. By the time proteinuria is established, nearly all subjects present the abnormal pattern.

Poor school and cognitive functioning with silent cerebral infarcts and sickle cell disease

The authors evaluated education attainment and neuropsychological deficits in children with sickle cell disease (SCD) and silent cerebral infarcts. Children with silent infarcts had twice the rate of school difficulties as children without infarcts. Eighty percent of silent infarct cases had clinically significant cognitive deficits, whereas 35% had deficits in academic skills. Children with silent cerebral infarcts show high rates of poor educational attainment, cognitive deficits, and frontal lobe injury. Poor school performance in SCD is one indicator of silent infarcts.

Angiotensin II AT1 receptor gene polymorphism and microalbuminuria in essential hypertension

The objective of this study was to analyze the relationship of polymorphisms of the angiotensin II AT1 receptor gene with microalbuminuria in a group of young adults with essential hypertension. Essential hypertensives, less than 50 years old, never previously treated with antihypertensive drugs, and in absence of diabetes mellitus were included. Office blood pressure (BP), 24-h ambulatory BP monitoring, urinary albumin excretion (UAE) measurements, and DNA analysis were performed. Polymorphisms of the angiotensin II AT1-receptor gene (A1166C and C573T) were studied by polymerase chain reaction and single-strand conformation polymorphism techniques. One hundred eighty-three patients, 49 (27%) microalbuminurics, were included. Office and ambulatory BP values were significantly higher in the microalbuminuria group. No differences in the presence of microalbuminuria were observed among the genotypes of either A1166C or C573T polymorphisms of the angiotensin II receptor AT1 gene, or in the allele frequency of the A1166C or the C573T polymorphism. LogUAE was significantly different among genotypes of the C573T polymorphism [CC 1.30(1.15-1.45), CT 1.14(1.00-1.28), and TT 0.94(0.68-1.20), P < .05]. Both office and ambulatory blood pressure and the TT/C573T genotype were independently related to logUAE, and, at the same BP values, UAE was lower in subjects with this genotype. We have found that the C573T polymorphism is on linkage disequilibrium with A1166C, as the 573T allele is closely linked to the presence of the 1166A allele, but not vice versa. Haplotype analysis among subjects with the AA genotype for the A1166C polymorphism confirms the influence of the TT genotype of the C573T polymorphism on the UAE in hypertensives. The C573T polymorphism of the angiotensin II receptor AT1 gene seems to be a genetic protective factor for UAE in a population of essential hypertensives.

Polymorphism insertion/deletion of the ACE gene and ambulatory blood pressure circadian variability in essential hypertension

OBJECTIVE

The objective of the present study was to analyze the influence of the insertion/deletion (I/D) polymorphism of the angiotensin-converting enzyme on ambulatory blood pressure values and circadian variability in untreated patients with hypertension.

MATERIAL AND METHODS

Ninety-nine essential hypertensive patients, less than 50 years old (mean age 39.5+/-7.0 years), previously untreated with antihypertensive drugs were included. Twenty-four hour ambulatory blood pressure monitoring (ABPM) was performed with a Spacelabs (90202 and 90207) monitor, during a regular working day in unrestricted ambulatory conditions. The I/D polymorphism of the ACE was determined by PCR.

RESULTS

The distributions of genotypes were in Hardy-Weinberg equilibrium: I=17 (17%), ID=41 (41.5%), DD=41 (41.5%). No significant differences were present among the groups in terms of age, sex, and biochemical and lipid profiles. The average of 24-h ambulatory blood pressure was slightly higher in patients with the DD genotype as compared with patients with the II and ID genotypes. This was the result of higher nighttime blood pressure values, because no differences in blood pressure were observed during daytime. The systolic blood pressure (SBP) day:night ratio, as an estimate of circadian variability, was significantly lower in subjects homozygous for the D allele than it was in patients carrying the I allele (1.13+/-0.09 vs. 1.17+/-0.08, P=0.014). The subjects in the lowest tertile of the SBP day:night ratio, exhibited a higher frequency of the D allele when compared with those in the middle tertile (0.74 vs. 0.59, P<0.05) or with those in the highest tertile (0.74 vs. 0.54, P<0.01). By using two-way ANOVA with repeated measures, significant differences in SBP variation over time were observed when comparing homozygous for the D allele with subjects carrying the I allele (F=2.11, P=0.002).

CONCLUSIONS

Among the genotypes of the I/D polymorphism, subjects carrying DD genotype showed a blunted decline of the physiological nocturnal fall of blood pressure that was significant for SBP.

Nonhistological diagnosis of human cerebral tumors by 1H magnetic resonance spectroscopy and amino acid analysis

We describe a multivariate analysis procedure to classify human cerebral tumors nonhistologically in vitro, combining the use of 1H magnetic resonance spectroscopy (MRS) with automatic amino acid analysis of biopsy extracts. Eighty-one biopsies were obtained surgically and classified histologically in eight classes: high-grade astrocytomas (class 1, n = 19), low-grade astrocytomas (class 2, n = 10), normal brain (class 3, n = 9), medulloblastomas (class 4, n = 4), meningiomas (class 5, n = 18), metastases (class 6, n = 8), neurinomas (class 7, n = 9), and oligodendrogliomas (class 8, n = 4). Perchloric acid extracts were prepared from every biopsy and analyzed by high resolution 1H MRS and automatic amino acid analysis by ionic exchange chromatography. Intensities of 27 resonances and ratios of resonances were measured in the 1H MRS spectra, and 17 amino acid concentrations were determined in the chromatograms. Linear discriminant analysis provided the most adequate combination of these variables for binary classifications of a biopsy between any two possible classes and in multiple choice comparisons, involving the eight possible classes considered. Correct diagnosis was obtained when the class selected by the computer matched the histological diagnosis. In binary comparisons, consideration of the amino acid profile increased the percentage of correct classifications, being always higher than 75% and reaching 100% in many cases. In multilateral comparisons, scores were: high-grade astrocytomas, 80%; low-grade astrocytomas, 74%; normal brain, 100%; medulloblastomas, 100%; meningiomas, 94.5%; metastases, 86%; neurinomas, 100%; and oligodendrogliomas, 75%. These results indicate that statistical multivariate procedures, combining 1H MRS and amino acid analysis of tissue extracts, provide a valuable classifier for the nonhistological diagnosis of biopsies from brain tumors in vitro.

[Factors associated with changes in microalbuminuria during antihypertensive treatment]

BACKGROUND

The objective of the present study was to analyze the factors related with changes of microalbuminuria during antihypertensive treatment in patients with essential hypertension.

METHODS

One hundred and six patients (57 men, mean age 40.8 [SD 6.6] years) never treated with antihypertensive treatment were included. At the beginning and after one year, blood pressure biochemical profile and urinary albumin excretion (UAE) were measured. After the initial evaluation, 53 patients received angiotensin converting enzyme inhibitors (ACEi) and 53 beta-blockers (BB). Hydrochlorothiazide was added to achieve the blood pressure target < 140/90 mmHg.

RESULTS

The average of UAE was 32.1 (43.1) mg/24 h, and 41 (39%) patients had microalbuminuretics. After 12 months of treatment, a significative fall of systolic BP (-20.6 [8.03] mmHg, p < 0.001), and diastolic BP (-14.18 [10.34] mmHg, p < 0.001) were observed, whereas baseline glucose increases (3.08 [11.07] mg/dl, p = 0.006). The changes of UAE were only related with the baseline UAE values. Neither, age, sex, baseline diastolic BP and changes in diastolic BP were significantly related with the changes in UAE. In spite of similar mean BP reduction (medial BP 17.4 [10.9] vs 14.8 [10.4] mmHg), UAE only was reduced in patients treated with ACEi (LogUAE: 0.203 [0.872] mg/24 h; p < 0.04). In addition, in patients treated with BB a significative increase in baseline glucose (4.4 [12.3] mg/dl; p = 0.013) and uric acid (1.18 [4.18]; p = 0.031) were observed.

CONCLUSIONS

In patients with essential hypertension, changes in microalbuminuria depends of the initial UAE values and the kind of antihypertensive treatment. ACEi produced higher UAE reduction and lower derangement of the glucose metabolism than BB.

Influence of the I/D polymorphism of the angiotensin-converting enzyme gene on the outcome of microalbuminuria in essential hypertension

The objective of the present study was to analyze the influence of the I/D polymorphism of the ACE gene on the outcome of microalbuminuria in essential hypertensive patients who were receiving antihypertensive treatment. One hundred thirty-six essential hypertensive patients who were <50 years old and had never previously received treatment with antihypertensive drugs were included in the study. During a 3-year period, patients received nonpharmacological treatment consisting of moderate salt restriction and a low-calorie diet they were obese, with or without a regimen of antihypertensive drugs based on beta-blockers or ACE inhibitors. Hydrochlorothiazide was added when necessary to maintain the blood pressure goal of <135/85 mm Hg. At the beginning of the study and at yearly intervals, systolic and diastolic blood pressures (SBP and DBP, respectively), 24-hour urinary albumin excretion (UAE), renal function, and biochemical profile measurements were made. The insertion/deletion (I/D) polymorphism of the ACE gene was determined through the use of polymerase chain reaction. The variables used in the statistical analysis were the measurements at the start of the study and the increase or decrease detected during the follow-up, estimated as individual specific regression line slope values. At baseline, no differences in blood pressure or UAE values were observed among genotypes. Likewise, the genotype or allele frequency was not significantly different between normoalbuminurics and microalbuminurics. After the 3 treatment years, significant reductions in SBP, DBP, and UAE were found (SBP 151.6+/-17.3 reduced to 137.2+/-14.3 mm Hg, P<0.001; DBP 96.6+/-8.9 reduced to 84.5+/-9.8 mm Hg, P<0.001; UAE 36.7+/-71.5 reduced to 28.3+/-78.6 mg/24 h, P<0. 05). The slopes of these parameters over time did not differ significantly among genotypes. The slope of SBP was the main factor related to the slope of logUAE (P<0.003). A significant positive correlation coefficient between the SBP and logUAE slopes was observed for the DD patients (r=0.57, P<0.0001) but was absent in patients carrying the I allele (II r=-0.03, P=NS; I/D r=0.01, P=NS). Follow-up studies should be used to achieve a better understanding of the impact of candidate gene polymorphisms on the development of hypertension-induced organ damage. Assessment of the I/D polymorphism of the ACE gene may identify subjects who require a greatly lowered blood pressure to prevent organ damage and to reduce hypertension-associated complications and death.

Treatment of community-acquired pneumonia in outpatients: randomized study of clarithromycin alone versus clarithromycin and cefuroxime

OBJECTIVE

To evaluate the efficacy of clarithromycin alone in comparison with the combination of clarithromycin and cefuroxime in the treatment of nonhospitalized patients with community-acquired pneumonia (CAP) in a Mediterranean population.

METHODS

CAP was defined as the acute onset of fever (>38 degrees C) with pulmonary opacity on chest roentgenogram. The American Thoracic Society (ATS) criteria (1993) were used to decide on patient hospitalization. Ninety subjects, of whom 53 (59%) were men, with a mean age (+/-SD) of 38+/-15 years, were randomized: 45 received clarithromycin 500 mg b.i.d. orally for 14 days (CL group), and 45 received clarithromycin plus cefuroxime 500 mg b.i.d. orally for 7 days (CLCE group). Patients were monitored with clinical, radiological, and laboratory controls at 3 and 21 days. There were no significant differences between the two groups with regard to demographic, clinical, physical and laboratory data.

RESULTS

The mean time to defervescence was 2.4+/-1.4 and 2.4+/-1.5 days, respectively. Chest roentgenogram clearance was complete in all cases, without statistically significant differences in the time to resolution between both arms. Side effects were mild (no significant differences between groups): 5 patients in the CL group and 3 in the CLCE group showed gastrointestinal symptoms. Two patients (2.2%), both in the CLCE group, needed hospital admission during follow-up, but all 90 patients showed an excellent outcome. A causative agent was determined in 25 cases (28%). Legionella pneumophila, Streptococcus pneumoniae, and Mycoplasma pneumoniae were the most frequent pathogens.

CONCLUSION

Empirical treatment of outpatient CAP with clarithromycin can be considered adequate in the Mediterranean area, independently of the microbiological etiology. ATS criteria for admitting patients with CAP are appropriate in this population.

[Insertion/deletion polymorphism of the gene encoding for angiotensin-converting enzyme and microalbuminuria in essential arterial hypertension]

BACKGROUND

To assess the influence of insertion/deletion polymorphism in the ACE gene on the microalbuminuria in essential hypertension.

PATIENTS AND METHODS

Seventy-nine patients with essential hypertension (37 males and 42 females) (mean age 39 [7] years, body mass index 28 [4] kg/m2), never treated with antihypertensive drugs were included in the study. Urinary albumin excretion (UAE) was assessed in two different days. Ambulatory blood pressure (BP) was assessed during 24 h period. Genotype ACE gene and gene frequencies were determined by an assay based on the polymerase chain reaction (PCR).

RESULTS

The distribution of phenotypes was: II = 14 (17%), ID = 32 (40%) and DD = 33 (43%). The mean for UAE tended to be higher in the DD group (53.82 [88.4] mg/24 h) than ID (27.8 [39.6] mg/24 h) and II (23.8 [16.7] mg/24 h). Likewise, the average for UAE were higher in the DD group than in the II + ID group (26.6 [34.0] mg/24 h) (p = 0.06), although the differences did not achieved statistical significance. The relationship between log UAE and 24-hour mean BP was significantly higher in the DD group (r2 = 0.232; p = 0.005) than that observed in the other groups (r2 = 0.060; p = 0.101).

CONCLUSIONS

In the present study with young patients with essential hypertension, in DD genotype, UAE seems to be higher and more dependent of BP levels than in the other hypertensives.

[Ambulatory arterial pressure and left ventricular hypertrophy in untreated hypertensive patients]

BACKGROUND

The study was designed to evaluate blood pressure (BP) values related to left ventricular hypertrophy (LVH) in a group of never treated middle-aged hypertensive subjects.

PATIENTS AND METHOD

Non-invasive ambulatory blood pressure monitoring (ABPM) and echocardiography were performed in 149 hypertensive patients (25-50 years old) with diastolic blood pressure (DBP) 90-114 mmHg. LVH was considered when left ventricular mass (LVM) was > 134 g/m2 in males and > 110 g/m2 in females.

RESULTS

43% of patients had LVH. Patients with LVH had higher clinic and ambulatory BP values. The greatest differences were in mean 24-h SBP (p = 0.001) and in 24-h DBP (p = 0.006). With respect to LVH, there were no differences between dippers and non-dippers, males or females, and circadian or BP variability. LVM was positively correlated with clinical DBP (p = 0.24), 24 h SBP (p = 0.41), pulse pressure (PP) (p = 0.36) and absolute BP variability (p = 0.23). Multiple regression analysis confirmed that 24-h SBP and sex where positively associated with LVH independent of others factors. The existence of 24-h SBP > 150 mmHg dramatically increased the risk of LVH (odds ratio [OR] = 9.2; CI 95%: 2.8-29.3; p = 0.002).

CONCLUSIONS

The present study indicates that in never treated middle-aged essential hypertensive patients the principal factor related to the presence of LVH is the value of systolic blood pressure throughout a 24-h period.

Delimiting the binding site for quaternary ammonium lidocaine derivatives in the acetylcholine receptor channel

The triethylammonium QX-314 and the trimethylammonium QX-222 are lidocaine derivatives that act as open-channel blockers of the acetylcholine (ACh) receptor. When bound, these blockers should occlude some of the residues lining the channel. Eight residues in the second membrane-spanning segment (M2) of the mouse-muscle alpha subunit were mutated one at a time to cysteine and expressed together with wild-type beta, gamma, and delta subunits in Xenopus oocytes. The rate constant for the reaction of each substituted cysteine with 2-aminoethyl methanethiosulfonate (MTSEA) was determined from the time course of the irreversible effect of MTSEA on the ACh-induced current. The reactions were carried out in the presence and absence of ACh and in the presence and absence of QX-314 and QX-222. These blockers had no effect on the reactions in the absence of ACh. In the presence of ACh, both blockers retarded the reaction of extracellularly applied MTSEA with cysteine substituted for residues from alphaVal255, one third of the distance in from the extracellular end of M2, to alphaGlu241, flanking the intracellular end of M2, but not with cysteine substituted for alphaLeu258 or alphaGlu262, at the extracellular end of M2. The reactions of MTSEA with cysteines substituted for alphaLeu258 and alphaGlu262 were considerably faster in the presence of ACh than in its absence. That QX-314 and QX-222 did not protect alphaL258C and alphaE262C against reaction with MTSEA in the presence of ACh implies that protection of the other residues was due to occlusion of the channel and not to the promotion of a less reactive state from a remote site. Given the 12-A overall length of the blockers and the alpha-helical conformation of M2 in the open state, the binding site for both blockers extends from alphaVal255 down to alphaSer248.

Epoxygenase metabolites of arachidonic acid affect electrophysiologic properties of rat tracheal epithelial cells1

Epoxyeicosatrienoic acids (EETs) and dihydroxyeicosatrienoic acids, products of the cytochrome P450 arachidonic acid epoxygenase pathway, have been shown to affect electrolyte transport in the kidney; however, the effects of these compounds on airway epithelial ion transport have not been investigated. Intact rat tracheas and primary cultures of rat tracheal epithelial cells were mounted in Ussing chambers to monitor changes in transepithelial voltage (Vt), short circuit current (Isc) and electrical resistance (Rt), with or without the addition of increasing concentrations (10(-9)-10(-6) M) of arachidonic acid, each of the four regioisomeric EETs and each of the corresponding dihydroxyeicosatrienoic acids. In intact tracheas, 11,12-EET caused dose-dependent decreases in Vt and Isc (DeltaVt = 0. 4 +/- 0.1 mV, DeltaIsc = -16.9 +/- 5.4 microA/cm2 at 10(-6) M, P < . 05 vs. vehicle), whereas changes in Rt were not significantly different than vehicle alone. 11,12-dihydroxyeicosatrienoic acid caused less impressive decreases in Vt and Isc, although arachidonic acid and the other compounds tested were without significant effects. 11,12-EET induced similar changes in cultured tracheal epithelial cell electrical parameters at concentrations as low as 10(-9) M. The effects of 11,12-EET were highly stereoselective, with activity limited to 11(R),12(S)-EET, the least abundant rat lung enantiomer. Pretreatment with amiloride or mucosal exposure to sodium free media did not significantly alter the 11,12-EET-induced changes in Vt. In contrast, pretreatment with bumetanide abolished the 11,12-EET electrophysiologic effects, suggesting that these effects may be mediated through inhibition of a chloride conductive pathway. We conclude that arachidonic acid epoxygenase metabolites cause significant changes in rat airway electrical parameters and may be involved in the control of lung fluid and electrolyte transport.

Pattern recognition analysis of 1H NMR spectra from perchloric acid extracts of human brain tumor biopsies

Pattern recognition techniques (factor analysis and neural networks) were used to investigate and classify human brain tumors based on the 1H NMR spectra of chemically extracted biopsies (n = 118). After removing information from lactate (because of variable ischemia times), unsupervised learning suggested that the spectra separated naturally into two groups: meningiomas and other tumors. Principal component analysis reduced the dimensionality of the data. A back-propagation neural network using the first 30 principal components gave 85% correct classification of meningiomas and nonmeningiomas. Simplification by vector rotation gave vectors that could be assigned to various metabolites, making it possible to use or to reject their information for neural network classification. Using scores calculated from the four rotated vectors due to creatine and glutamine gave the best classification into meningiomas and nonmeningiomas (89% correct). Classification of gliomas (n = 47) gave 62% correct within one grade. Only inositol showed a significant correlation with glioma grade.

State-dependent accessibility and electrostatic potential in the channel of the acetylcholine receptor. Inferences from rates of reaction of thiosulfonates with substituted cysteines in the M2 segment of the alpha subunit

Ion channel function depends on the chemical and physical properties and spatial arrangement of the residues that line the channel lumen and on the electrostatic potential within the lumen. We have used small, sulfhydryl-specific thiosulfonate reagents, both positively charged and neutral, to probe the environment within the acetylcholine (ACh) receptor channel. Rate constants were determined for their reactions with cysteines substituted for nine exposed residues in the second membrane-spanning segment (M2) of the alpha subunit. The largest rate constants, both in the presence and absence of ACh, were for the reactions with the cysteine substituted for alpha Thr244, near the intracellular end of the channel. In the open state of the channel, but not in the closed state, the rate constants for the reactions of the charged reagents with several substituted cysteines depended on the transmembrane electrostatic potential, and the electrical distance of these cysteines increased from the extracellular to the intracellular end of M2. Even at zero transmembrane potential, the ratios of the rate constants for the reactions of three positively charged reagents with alpha T244C, alpha L251C, and alpha L258C to the rate constant for the reaction of an uncharged reagent were much greater in the open than in the closed state. This dependence of the rate constants on reagent charge is consistent with an intrinsic electrostatic potential in the channel that is considerably more negative in the open state than in the closed state. The effects of ACh on the rate constants for the reactions of substituted Cys along the length of alpha M2, on the dependence of the rate constants on the transmembrane potential, and on the intrinsic potential support a location of a gate more intracellular than alpha Thr244.

Glutamate, glutamine, and GABA as substrates for the neuronal and glial compartments after focal cerebral ischemia in rats

BACKGROUND AND PURPOSE

Even though the utilization of substrates alternative to glucose may play an important role in the survival of brain cells under ischemic conditions, evidence on changes in substrate selection by the adult brain in vivo during ischemic episodes remains very limited. This study investigates the utilization of glutamate, glutamine, and GABA as fuel by the neuronal and glial tricarboxylic acid cycles of both cerebral hemispheres after partially reversible focal cerebral ischemia (FCI).

METHODS

Right hemisphere infarct was induced in adult Long-Evans rats by permanent occlusion of the right middle cerebral artery and transitory occlusion of both common carotid arteries. (1,2-13C2) acetate was infused for 60 minutes in the right carotid artery immediately after carotid recirculation had been re-established (1-hour group) or 23 hours later (24-hour group). Extracts from both cerebral hemispheres were prepared and analyzed separately by 13C nuclear magnetic resonance and computer-assisted metabolic modeling.

RESULTS

FCI decreased the oxidative metabolism of glucose in the brain in a time-dependent manner. Reduced glucose oxidation was compensated for by increased oxidations of (13C) glutamate and (13C) GABA in the astrocytes of the ipsilateral hemispheres of both groups. Increased oxidative metabolism of (13C) glutamine in the neurons was favored by increased activity of the neuronal pyruvate recycling system in the 24-hour group.

CONCLUSIONS

Data were obtained consistent with time-dependent changes in the utilization of glutamate and GABA or glutamine as metabolic substrates for the glial or neuronal compartments of rat brain after FCI.

Prognostic value of ambulatory blood pressure monitoring in refractory hypertension: a prospective study

The objective of this study was to establish whether ambulatory blood pressure offers a better estimate of cardiovascular risk than does its clinical blood pressure counterpart in refractory hypertension. This prospective study assessed the incidence of cardiovascular events over time during an average follow-up of 49 months (range, 6 to 96). Patients were referred to specialized hypertension clinics (86 essential hypertension patients who had diastolic blood pressure > 100 mm Hg during antihypertensive treatment that included three or more antihypertensive drugs, one being a diuretic). Twenty-four-hour ambulatory blood pressure monitoring (ABPM) was performed at the time of entrance. End-organ damage was monitored yearly, and the incidence of cardiovascular events was recorded. Patients were divided into tertiles of average diastolic blood pressure during activity according to the ABPM, with the lowest tertile <88 mm Hg (LT, n=29), the middle tertile 88 to 97 mm Hg (MT, n=29), and the highest tertile >97 mm Hg (HT, n=28). While significant differences in systolic and diastolic ambulatory blood pressures were observed among groups, no differences were observed at either the beginning or at the time of the last evaluation for office blood pressure. During the last evaluation, a progression in the end-organ damage score was observed for the HT group but not for the two other groups. Twenty-one of the patients had a new cardiovascular event; the incidence of events was significantly lower for the LT group (2.2 per 100 patient-years) than it was for the MT group (9.5 per 100 patient-years) or for the HT group (13.6 per 100 patient-years). The probability of event-free survival was also significantly different when comparing the LT group with the other two groups (LT versus MT log-rank, P<.04; LT versus HT log-rank, P<.006). The HT group was an independent risk factor for the incidence of cardiovascular events (relative risk, 6.20; 95% confidence interval, 1.38 to 28.1, P<.02). Higher values of ambulatory blood pressure result in a worse prognosis in patients with refractory hypertension, supporting the recommendation that ABPM is useful in stratifying the cardiovascular risk in patients with refractory hypertension.