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Biomedical subjects

J Montero

Publications and source records attributed to J Montero.

At least 37 records · Page 2Linked to original sources
PubMed1999

[Hypertension and mineralocorticoids. Usefulness of renin and aldosterone measurements].

Recently, some genetic forms of hypertension have been well characterized. These forms can be globally called mineralocorticoid hypertension and are due to different alterations of the renin-angiotensin-aldosterone system (SRAA). Among these, classic primary hyperaldosteronism and its glucocorticoid remediable variety, in which hypertension is secondary to aldosterone production, must be considered. There are also conditions in which mineralocorticoid activity does not depend on aldosterone production. These conditions generate a hyporeninemic hyperaldosteronism, observed in Liddle syndrome, apparent mineralocorticoid hypertension, 11- and 17-hydroxylase deficiency, among others. The detection of these forms of hypertension is only feasible if the renin-angiotensin-aldosterone system is assessed, measuring renin and aldosterone levels. This article reviews these forms of hypertension, their clinical workup and their relevance in the usual hypertensive patients.

Aldosterone↗
PubMed1999

[Electrophysiological evaluation of level compression in elbow ulnar neuropathy].

OBJECTIVES: In order to establish the focal compression in the elbow, a study of 318 patients with clinical manifestations of ulnar neuropathy was carried out. We divided the patients in three groups: I) those who presented mechanical anomalies with background of fracture, elbow valgus...; II) those who did not present mechanical anomalies, but they have been in bed long time or they have been operated...; III) those who did not have evident cause for the compression. MATERIAL AND METHOD: Antidromic sensory conduction and segmentary motor conduction of the ulnar nerve were studied, and segmental motor conduction along the elbow with interval of 2 centimetres (technique of Kanakamedala). RESULTS: 83.6% of the 318 ulnar neuropathy had the focal compression in the ulnar sulcus. 8.2% had the focal compression distal to the ulnar sulcus. 0.94% had double focal compression. In 7.2% was not possible to determinate the focal compression. In group I, the focal compression was in the ulnar sulcus in 93.8% of the cases. In group II, the focal compression was in the ulnar sulcus in 94.3% of the cases. In group III, the focal compression was in the ulnar sulcus in 55.8% of the cases, and distal to the ulnar sulcus in 29.1% of the cases. CONCLUSION: It is possible to localize the focal compression of the ulnar neuropathy in the elbow, with high level of probability, with the nerve conductions. This allows the surgeon to be orientated about therapeutical attitude.

Adult↗
PubMed1999

[High prevalence of undiagnosed primary hyperaldosteronism among patients with essential hypertension].

BACKGROUND: Classically, primary hyperaldosteronism was diagnosed in no more than 1% of patients with hypertension, when hypokalemia was used as the screening test. However, numerous patients with primary hyperaldosteronism do not have hypokalemia and the disease remains undiagnosed. AIM: To assess the prevalence of normokalemic primary hyperaldosteronism among patients classified as having essential hypertension. PATIENTS AND METHODS: One hundred hypertensive patients with a blood pressure over 145/95 were studied. Plasma aldosterone and plasma renin activity were measured in all. A primary hyperaldosteronism was diagnosed when high aldosterone levels (over 16 ng/dl) and low plasma renin activity (below 0.5 ng/ml/h) coexisted in two blood tests or the aldosterone/plasma renin activity ratio was over 50. A probable primary hyperaldosteronism was diagnosed when the ratio was between 25 and 50 and these patients were subjected to a Fludrocortisone test to confirm the diagnosis. A dexametasone suppression test was done to discard glucocorticoid remediable aldosteronism. An adrenal TAC scan was done to all patients with primary hyperaldosteronism. RESULTS: A diagnosis of primary hyperaldosteronism was reached in ten patients. Seven had elevated aldosterone and low plasma renin activity. In three the diagnosis was confirmed with the fludrocortisone test. All ten patients had normal serum potassium levels. Dexametasone suppression test was positive in three patients, that normalized their blood pressure levels. Adrenal TAC scans showed an adenoma in one patient and hyperplasia in another. CONCLUSIONS: Primary hyperaldosteronism is more frequent than previously thought, it is overlooked when hypokalemia is used as the screening test and it can only be diagnosed measuring plasma aldosterone and renin activity.

Aldosterone↗
PubMed1998

T235 variant of the angiotensinogen gene and blood pressure in the Chilean population.

BACKGROUND: The angiotensinogen gene has recently been linked to essential hypertension. A variant within this gene, encoding threonine rather than methionine at amino acid position 235, was associated with essential hypertension. However, results of new studies have not confirmed this association, suggesting that ethnic differences may explain the different results. OBJECTIVE: To evaluate whether the T235 variant is associated with a higher incidence of essential hypertension among Hispanics (a group that has scarcely been evaluated) and to determine whether T235 is associated with variations in the plasma renin activity or the serum aldosterone level. PATIENTS AND METHOD: We studied 64 patients with essential hypertension and 62 normotensives, matched for age and sex. We obtained samples for determinations of plasma renin activity, serum aldosterone level and genome DNA from all subjects. The genomic DNA was amplified using the polymerase chain reaction technique and digested by the restriction enzyme streptococcus faecalis (Sfa NI) which cuts M235 only, not T235. RESULTS: The patients with essential hypertension had a higher prevalence of the risk variant T235 (alleles 77/128 = 60.2%) than did the normotensive controls (alleles 65/124 = 52.4%), but the difference was not statistically significant (chi2=1.53, P=0.22). The plasma renin activity levels in hypertensives were not statistically different for homozygous T235, heterozygous and homozygous M235 (1.0 +/- 0.96, 2.0 +/- 2.25 and 1.55 +/- 1.49 ng/ml per h, respectively, P=0.5 1). However, when we considered those hypertensives with low plasma renin activity levels (< 1 ng/ml per h), we found a high prevalence (72.7%) of subjects homozygous for the T235 variant. We found no association between the T235 variant and the serum aldosterone levels in hypertensive and normotensive subjects. CONCLUSIONS: We demonstrated that there is a high prevalence of T235 variant in our Hispanic population. The slight difference between prevalences of T235 variant among hypertensive and normotensive subjects that we found was not statistically significant and did not permit us to establish an association between T235 variant and essential hypertension. We believe that only studying a larger cohort of subjects could show whether there is a quantitative effect of the T allele on plasma renin activity levels.

Aldosterone↗
PubMed1998

[Electrophysiological study of 921 cases of carpal tunnel syndrome: its application for prognosis and treatment].

A neurophysiological study of 921 hands with clinical manifestations of carpal tunnel syndrome (CTS), 88 of normal individuals and 588 of patients with disorders not related with median neuropathy was carried out to establish the diagnostic sensibility 130 non-operated on patients with slight CTS were controlled one year later. The same was achieved with 105 surgically treated patients in order to establish the electrophysiological changes related to therapeutic methods. Antidromic sensory conduction and segmentary motor conduction of the median nerve were studied along with the difference between median and ulnar sensory latencies. Only 84 of the 921 hands (5.2%) showed normal electrophysiological findings and 469 (50.9%) minimal changes. 343 hands (37.2%) showed signs suggestive of axonal degeneration in sensory fibers and 147 (16%) in motor ones. Of the 130 slight CTS not surgically treated, clinical manifestations persisted for one year in 118, 17 of which have normal electrophysiological parameters. Twenty six (20%) of these 130 hands got worse. Of the 105 CTS surgically treated hands, 58 continued with symptoms one year later in spite of the electrophysiological improvement in 88.6% of them. Among 588 patients hands without CTS symptoms, only 0.8% had electrophysiological signs suggesting CTS. A high yield of the electrophysiological diagnosis of the CTS is shown. Symptoms frequently persist in patients without definite nerve compression.

Axons↗
PubMed1998

[Measurement of low levels of plasma renin activity. A methodological improvement].

BACKGROUND: The present method to measure plasma renin activity is cumbersome and imprecise, factors that limit its clinical application. AIM: To assess the importance of blood sampling conditions and the usefulness of increasing incubation time to measure plasma renin activity at low levels. PATIENTS AND METHODS: Twenty hypertensive patients, 14 female, aged 14 to 76 years old, were studied. Two blood samples were obtained after a 10 min rest in the sitting position and after a 30 min rest in supine position. One blood sample of each condition was sent to the laboratory at room temperature and the other sample was sent refrigerated. Angiotensin I concentration was determined after 3 h of enzymatic incubation at 37 degrees C and, in subjects with an activity of less than 1 ng/ml/h, after 18 h of incubation. RESULTS: No significant differences in plasma renin activity were observed between the samples obtained with different rest times or different transportation methods. In people with low plasma renin activity, the 18 h enzymatic incubation reduced the lower detection from 0.3 to 0.014 ng/ml/h and the coefficient of variation from 14.4 to 3.2%. CONCLUSIONS: A simplified blood sampling method does not change plasma renin activity values, and the longer enzymatic incubation in people with low plasma renin activity improves both the sensitivity and accuracy of the determination.

Adolescent↗
PubMed1998

[Neuropathy by n-hexanes: a generalized disorder of the intermediate filaments].

BACKGROUND: Chronic inhalation of glues containing n-hexanes produces neurofilament (NF) accumulation which induces sensory-motor polyneuropathy. In vitro assays have shown this toxic substance causes intermediate filaments (IF) aggregation in non-neuronal cells. OBJECTIVE: To describe intermediate filament changes in human pathology due to n-hexanes. PATIENTS AND METHODS: Sural nerve and skin biopsy samples from 2 patients who suffered from a severe sensory-motor polyneuropathy after prolonged inhalation of glue containing n-hexane were examined with electron microscopy and vimentin and phosphorylated NF immunocytochemistry. RESULTS: Abnormal accumulations of NF and NF-immunoreactive products occurred in nerve fibers and increased numbers of fibrils were observed in endoneurial endothelial cells of the sural nerve. In addition, abnormal vimentin-immunoreactive deposition was seen in fibroblasts and capillaries of the skin. The present results suggest that high doses of n-hexane cause a diffuse IF disorder in a similar form as occurs in giant axonal neuropathy. CONCLUSION: IF aggregation can occur in non-neuronal cells in humans, as has been previously proved in in vitro experiments. The presence of IF accumulations in Schwann cells, as seen in the ultrastructural examination, together with the electrophysiological findings showing an early decrease of sensory and motor nerve conduction velocities, suggests the existence of a primary myelinic disorder associated with axonal damage.

Adhesives↗
PubMed1997

Apoptosis is not the mechanism of cell death of muscle fibers in human muscular dystrophies and inflammatory myopathies.

Muscle biopsies from patients affected by muscular dystrophies and polymyositis were processed with the method of in situ labeling of nuclear DNA fragmentation in order to assess whether apoptosis occurs in these diseases. Apoptotic nuclei were seen in the mononuclear cell infiltrates in inflammatory myopathies but not in dying muscle fibers, thus confirming the general opinion that death of muscle fibers in human diseases is not produced by a mechanism of apoptosis.

Animals↗
PubMed1997

[Hypertension treatable with glucocorticoids: report of a case].

Lately, a series of hypertensive syndromes of unknown etiology that respond to new forms of therapy, have been described. One of these is glucocorticoid remediable hypertension, that evolves with suppressed plasma renin activity and normal or high serum aldosterone levels, that lead to an aldosterone/plasma renin activity ratio over 30. We report a 45 years old woman with a severe hypertension, despite the use of antihypertensive medications. She had a plasma renin activity of less than 0.3 ng/ml/h, normal serum aldosterone levels (10 ng/ml) and thus a high aldosterone/plasma renin activity ratio. She had normal serum potassium and sodium levels. Due to the bad results of conventional antihypertensive medications, a treatment with dexamethasone was started, that normalized blood pressure and allowed to discontinue other antihypertensive medications. This type of hypertension must be sought since non conventional treatments could be used for refractory hypertensive syndromes.

Aldosterone↗
PubMed1996

Axon reflexes or ephaptic responses simulating blink reflex R1 after XII-VII nerve anastomosis.

It has been claimed that functional recovery of the blink reflex occurs after hypoglossal-facial nerve anastomosis. This has been explained through central nervous system plasticity and reorganization of neuronal connections. In 5 patients with reinnervated facial muscles after hypoglossal-facial nerve anastomosis we observed "R1-like" responses that fulfilled criteria for facial nerve axon reflexes or ephapses. First, displacement of the stimulating electrode from the supraorbital to zygomatic area shortened the latency of the evoked response. Second, these responses were stable (jitter mean consecutive difference < 25 microsec) and they had complex potential shapes unmodified by high-frequency stimulation. Finally, collision techniques demonstrated antidromic conduction of impulses in the facial nerve from supraorbital to zygomatic points. Therefore, these "R1-like" responses are not the early component of a functionally recovered blink reflex but motor axon reflexes or ephaptic responses similar to the short latency responses observed following facial nerve regeneration or from sutured nerves in human forearms.

Adolescent↗
PubMed1996

Genetic variation in P450c11AS in Chilean patients with low renin hypertension.

Low renin hypertension (LRH), which accounts for 10-20% of patients with idiopathic "essential" hypertension, bears hormonal similarities to mineralocorticoid-induced hypertension, but elevated mineralocorticoid concentrations have not been found. Some patients with LRH have normal, rather than suppressed, plasma aldosterone concentrations, so that the ratio of aldosterone concentration to PRA (Aldo/PRA) is high, suggesting inappropriately increased aldosterone biosynthesis. We characterized the CYP11B2 gene that encodes the aldosterone synthase, P450c11AS, in hypertensive and control populations in a single clinic in Santiago, Chile. We directly sequenced the entire CYP11B2 gene in 12 patients with LRH, 2 high renin hypertensive controls, and 2 normotensive controls. All sequences were identical, except that 8 of 24 LRH alleles encoded arginine rather than lysine at position 173. The Arg173 and Lys173 variants were expressed in transfected MA-10 cells, and their ability to convert deoxycorticosterone to aldosterone was measured; the apparent Michaelis constant (Km) for Lys173 was 2.73 mumol/L; the Km for Arg173 was 2.53 mumol/L. The apparent maximal velocity (Vmax) for Lys173 was 6.5 x 10(-3) micrograms/mL.24 h; the Vmax for Arg173 was 7.8 x 10(-3) micrograms/mL.24 h. The first order rate constant, Vmax/Km was 2.38 for Lys173 and 3.08 for Arg173. As these values were not significantly different, we sought to determine whether Arg173 is a polymorphism linked to LRH. We examined position 173 in 52 unselected patients with idiopathic hypertension and 55 normotensive controls by PCR amplification of CYP11B2 exons 3-5 followed by digestion with Bsu361, which digests the Arg173 sequence, but not the Lys173 sequence. More of the hypertensive alleles (39 of 104, 37.5%) than normotensive alleles (25 of 110, 22.5%) carried Arg173 (chi 2 = 5.57; P < 0.02). Most of the Arg173 alleles (31 of 72, 43.1%) were from hypertensive patients with Aldo/PRA below 30, whereas only 5 of 24 (20.8%) Arg173 alleles were found in patients with Aldo/PRA greater than 30 (chi 2 = 3.79; P = 0.05) Thus, the ARg173 variant of CYP11B2 may be linked to LRH in Chilean patients.

Adult↗
PubMed1996

[Familial transmission of hepatitis C virus].

OBJECTIVE: To establish the prevalence of antibodies to hepatitis C virus (HCV) among relatives and other persons cohabiting with HCV carriers, as an indication of the risk of intradomestic transmission. EXPERIMENTAL DESIGN: A transversal study of series of clinical cases. A questionnaire was applied to the index cases (IC) and contact cases (CC), differentiating sexual contacts (SC) from non sexual contacts (NSC). PATIENTS: One hundred and sixty four IC and 533 CC were included. Information on parenteral risk factors, type of sexual relationship, period of exposure, and other epidemiological variables was obtained. Antibodies to HCV (HCV-Ab) were determined by 2nd generation ELISA. RESULTS: In eighty eight IC (53.6%) no parenteral risk factors were found. In 99 IC (62.8%) a liver biopsy showed chronic hepatitis or cirrhosis. Twelve CC (2.25%) turned out to be HCV-Ab (+), a ratio above that found in our city (0.3%, p < 0.001), however the comparison should be taken with caution. No significant differences were found with respect to several epidemiological variables, including type of sexual relationship, and socioeconomic indicators, between CC HCV-Ab (+) and (-). Stage of liver disease in the IC and relationship between IC and CC did not increase the risk of being HCV-Ab positive. In HCVAb positive CC a higher proportion of parenteral risk factors (p < 0.001), elevated ALT (p < 0.001) and sharing of personal tools (p < 0.01) were observed. CONCLUSIONS: Intrafamiliar transmission of HCV is poorly documented and it is related to the presence of parenteral risk factors. The actual prevalence of HCVAb in a general population is unknown, rendering difficult to make definite conclusions.

Adolescent↗
PubMed1995

[A low prevalence of antibodies to the hepatitis C virus in stable heterosexual couples].

The prevalence of antibodies against the hepatitis C virus (HCV Ab) was studied in a group of 126 stable heterosexual couples of HCV Ab carriers. Only 1.59% of the couples was positive with no significant differences observed with regard to the prevalences seen in donors from the same area. The HCV Ab positive couples had shared toiletry articles but no other risk factors were detected. The authors conclude that the sexual transmission of the HCV is scarce.

Adolescent↗
PubMed1995

[Evaluation of the cervical factor in ovulation induction].

Post coital sperm penetration tests performed in 66 women under study for infertility, the purpose was to evaluate the ovulation induction effect over mucus quality and over sperm penetration. They were divided in three groups: 1) 28 women with evidence of spontaneous ovulation (control group), 2) 26 patients in which ovulation was induced with comiphene citrate and 3) 12 patients in which ovulation was induced with menotropins. The results showed that CC had an adverse effect over cervical mucus (p < 0.001), while in patients treated with menotropins the cervical mucus quality was not modified. Sperm penetration in patients under CC had a tendency to lower values than those in women of the control group, but these were statistically lower than those in patients under menotropins (p < 0.05). These results show the adverse effect of CC and the benefit of menotropins over cervical mucus and sperm penetration.

Adult↗
PubMed1994

Dome-shaped lesion on chest radiograph: retroperitoneal abscess dissecting through the posterior chest wall.

A 50-year-old man with an 8 x 4 cm mass on the posterior chest was found to have a large retroperitoneal abscess due to Klebsiella pneumoniae. The abscess dissected through the right lower lobe of the lung and the posterior chest wall to produce a subcutaneous mass. The source of the posterior chest wall mass appeared to be a perinephric abscess. A dome-shaped lesion above the right hemidiaphragm on chest radiograph resolved immediately with surgical drainage, suggesting that an abscess should be a prime consideration when one observes such a lesion on a chest film.

Abscess↗