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Biomedical subjects

F Rivera

Publications and source records attributed to F Rivera.

At least 91 records · Page 5Linked to original sources

Hartmannella vermiformis isolated from the cerebrospinal fluid of a young male patient with meningoencephalitis and bronchopneumonia.

Meningoencephalitis and bronchopneumonia were documented in a patient from Peubla, Mexico. The patient began with symptoms and signs of a common flu and 12 days after the onset of his disease he was admitted to the hospital presenting symptoms and signs of meningoencephalitis. The clinical course evolved into an endocraneal hypertension syndrome with bronchopneumonia, coma and death. Wide-spectrum antibiotics, immunosuppressive and anti-tuberculosis therapy were unsuccessfully administered. Important antecedents were degree I malnutrition and repeated contact with polluted water. Post-mortem autopsy was not performed. Gram-positive cocci were isolated from the spinal fluid 2 days after admission, and then active amebae were isolated from three different samples of the spinal fluid at days 16, 18 and 19 after admission. Such samples were concentrated and inoculated onto specific culture media. Identification of amebae was based on their morphology and biochemistry. All amebae were Hartmannella vermiformis. Amebae were apparently not the cause of the disease and might be considered as an opportunistic colonizer which may have caused the evolution of the disease to become worse.

Acid Phosphatase↗

Polymorphisms of the human alpha 2A-adrenergic receptor gene in a Catalan population: description of a new polymorphism in the promoter region.

Alpha 2A-adrenergic receptor polymorphisms were investigated in 55 unrelated Caucasian Catalan individuals. Phenotypes were expressed by alpha 2-adrenoreceptor density and affinity determined by radioligand binding. In addition to the two previously described biallelic restriction fragment length polymorphisms (RFLP) (DraI and Bsu36I) [Hoehe et al 1988; Sun et al 1992], a transition was located in the promoter region of the human alpha 2A-adrenergic receptor using a non-radioisotopic single-strand conformational polymorphism (SSCP) analysis. DNA sequence analysis of this region showed that this transition produces the loss of a HhaI site. In our sample, the estimates of the frequency of this allele was 11% and those of DraI alleles were similar to those reported for other Caucasian populations but different from those observed in Afro-Americans. In addition, frequencies of the Bsu36I alleles in the Catalan population differed from those of Japanese and American White populations. A slight linkage disequilibrium between Bsu36I-DraI was found in our population. No association between phenotypes and RFLP genotypes was observed.

Alleles↗

Improving treatment of chemotherapy-induced neutropenic fever by administration of colony-stimulating factors.

BACKGROUND: Several randomized trials have tested the use of granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor (GM-CSF) in relieving chemotherapy-induced bone marrow suppression. However, the use of CSFs in the treatment of neutropenic fever remains virtually unexplored. PURPOSE: This study evaluated the benefits of adding CSF therapy to the standard antibiotic treatments given to cancer patients for chemotherapy-induced neutropenic fever. The usefulness of CSFs was quantified in terms of reducing the following: (a) the duration of neutropenia, (b) the length of hospitalization, and (c) the overall cost of the treatment. METHODS: A randomized trial was conducted to test whether the administration of either G-CSF or GM-CSF improved the outcome of standard antibiotic therapy (ceftazidime plus amikacin) in nonleukemic cancer patients with fever (> 38 degrees C) and grade IV neutropenia (absolute neutrophil count [ANC] < 500/mm3) induced by standard-dose chemotherapy. Of 121 patients who entered the trial, 39 received G-CSF (5 micrograms/kg body weight per day), 39 received GM-CSF (5 micrograms/kg body weight per day), and 43 received a placebo beginning just after the first dose of antibiotics. Treatments were continued for at least 5 days (7 days with clinically or microbiologically documented infections) or until 2 days after fever subsided and ANCs rose above 1000/mm3. RESULTS: The median duration of grade IV neutropenia (ANC of < 500/mm3) was 2 days in both CSF arms and 3 days in the placebo arm (P < .001). The median duration of neutropenia with an ANC of less than 1000/mm3 was also significantly shorter in patients receiving G-CSF or GM-CSF (P < .001). The median duration of fever was similar in the three arms. The median hospital stay was 5 days (range, 5-14 days) in the G-CSF arm, 5 days (range, 5-10 days) in the GM-CSF arm, and 7 days (range, 5-34 days) in the placebo arm (P < .001). The median time on CSF was 4 days in both treatment arms. The mean cost of overall treatment was reduced by $1300-$1400 in the CSF arms compared with the placebo arm (P = .11 for G-CSF versus placebo; P = .06 for GM-CSF versus placebo; P = .7 for G-CSF versus GM-CSF). CONCLUSIONS: Adding G-CSF or GM-CSF therapy to antibiotic treatment shortens the duration of neutropenia and the duration of hospitalization in patients with neutropenic fever. A statistically nonsignificant trend toward lower cost was observed in the CSF arms as compared with the placebo arm. IMPLICATIONS: The benefits of CSFs to cancer patients with chemotherapy-induced neutropenic fever merit further evaluation in large randomized trials.

Antineoplastic Combined Chemotherapy Protocols↗

Effect of upright posture and physical exercise on endogenous neurohormonal systems in cirrhotic patients with sodium retention and normal supine plasma renin, aldosterone, and norepinephrine levels.

It is well known that sodium retention occurs in a significant proportion of patients with cirrhosis despite normal supine plasma levels of renin, aldosterone (ALDO), and norepinephrine (NE). The current study was performed to assess whether this subset of patients also present normal activity of the renin-aldosterone and sympathetic nervous systems during upright posture in sitting position and moderate physical exercise. Nine healthy controls, 14 patients with compensated cirrhosis and 10 patients with cirrhosis, ascites, sodium retention, and normal supine plasma renin activity (PRA) and ALDO and NE concentration were sequentially studied after 60 minutes in supine rest, 30 minutes in sitting position, and 30 minutes of cycloergometric exercise (3-METs). Sitting position and exercise were associated with similar stimulation of the renin-aldosterone and sympathetic nervous systems in the three groups of subjects. Consequently, cirrhotic patients with ascites showed values of PRA and plasma concentration of ALDO and NE similar to healthy subjects and patients with compensated cirrhosis during supine rest (renin: 1.4 +/- 0.3, 0.8 +/- 0.2, and 0.8 +/- 0.3 ng/mL; aldosterone: 24.3 +/- 4.7, 20.2 +/- 3.9 and 21.4 +/- 3.4 ng/dL; norepinephrine: 252 +/- 23, 250 +/- 16, and 255 +/- 23 pg/mL), sitting position (renin: 2.1 +/- 0.5, 1.1 +/- 0.3, and 1.6 +/- 0.4; aldosterone: 32.2 +/- 7.3, 23.7 +/- 5.3, and 26.2 +/- 4.5; norepinephrine: 356 +/- 38, 401 +/- 63, and 420 +/- 35), and exercise (renin: 2.9 +/- 0.8, 1.6 +/- 0.4, and 2.2 +/- 0.5; aldosterone: 43 +/- 6.4, 34.9 +/- 8.5, and 38.2 +/- 5.3; norepinephrine: 481 +/- 35, 499 +/- 54, and 534 +/- 48).(ABSTRACT TRUNCATED AT 250 WORDS)

Aldosterone↗

Endothelin 1 does not play a major role in the homeostasis of arterial pressure in cirrhotic rats with ascites.

BACKGROUND/AIMS: Patients with cirrhosis and ascites have increased plasma levels of endothelin, a powerful vasoconstrictor peptide. This study assessed the mechanisms underlying this phenomenon. METHODS: Plasma endothelin was measured in control rats and cirrhotic rats with and without ascites. In addition, the tissue concentration of endothelin and endothelin 1 messenger RNA (mRNA) and the effect of an endothelin A receptor antagonist on arterial and portal pressure were assessed in cirrhotic rats with ascites and control rats. RESULTS: Plasma endothelin levels were significantly higher in cirrhotic rats with ascites (24.5 +/- 2.8 pg/mL; P < 0.001) than in cirrhotic rats without ascites and control rats (7.9 +/- 2.0 and 5.8 +/- 0.9 pg/mL, respectively). In animals with ascites, endothelin and endothelin 1 mRNA content in the lung, kidney, and aorta was similar to that of the controls. In contrast, higher endothelin content (0.567 +/- 0.217 vs. 0.045 +/- 0.002 pg/mg protein; P < 0.05) and endothelin 1 mRNA was observed in hepatic tissue of rats with cirrhosis and ascites. Endothelin A receptor blockade was not associated with significant changes in arterial and portal pressure in any group of animals. CONCLUSIONS: Increased endothelin 1 mRNA and endothelin production occurs in the livers of cirrhotic rats with ascites. In addition, our findings suggest that endothelin is not involved with the homeostasis of arterial or portal pressure in cirrhosis with ascites.

Animals↗

Aquaretic effect of the kappa-opioid agonist RU 51599 in cirrhotic rats with ascites and water retention.

BACKGROUND & AIMS: It has recently been described that kappa-opioid receptor agonists inhibit antidiuretic hormone secretion and promote water excretion in humans and experimental animals. The aim of this study was to evaluate the aquaretic efficacy of the kappa-opioid receptor agonist RU 51599 in conscious cirrhotic rats with ascites and water retention. METHODS: In protocol 1, arterial pressure, heart rate, and renal water metabolism were measured in basal conditions and then were measured for 120 minutes after the administration of Ringer's solution (n = 8; 0.4 mL) or RU 51599 (n = 7; 1 mg/kg). In protocol 2, plasma antidiuretic hormone concentration was measured (n = 6) before and 60 minutes after administration of RU 51599 (1 mg/kg). In protocol 3, the effect of RU 51599 (n = 9; 1 mg/kg) was compared with that of the V2-receptor antagonist SKF 100398 (n = 9; 30 micrograms/kg). RESULTS: RU 51599 administration induced a profound diuretic and aquaretic effect without altering arterial pressure and heart rate. In protocol 2, the kappa-opioid agonist reduced by about 50% plasma antidiuretic hormone levels (from 6.6 +/- 0.9 to 3.4 +/- 0.6 pg/mL; P < 0.05). Finally, the improvement in renal water metabolism induced by RU 51599 was similar to that produced by the V2-receptor antagonist. CONCLUSIONS: RU 51599 has a potent aquaretic effect in cirrhotic rats with water retention, suggesting that kappa-opioid receptor agonists may be useful for the treatment of water retention and dilutional hyponatremia in cirrhosis.

Analysis of Variance↗

Increased plasma endothelin in cirrhosis. Relationship with systemic endotoxemia and response to changes in effective blood volume.

BACKGROUND/AIMS: Patients with cirrhosis and ascites show high plasma concentrations of endothelin. The aim of the current study was to investigate whether this feature is a compensatory response to effective hypovolemia or a consequence of systemic endotoxemia. METHODS: Protocols 1 and 2 assess the effect of acute changes in effective blood volume on plasma endothelin, and protocol 3 investigates the relationship between plasma endotoxin and endothelin in patients with cirrhosis and ascites. Protocol 1 included nine healthy subjects and 26 patients with cirrhosis studied during supine rest, upright tilt (which decreases effective blood volume) and cycloergometric exercise (which activates vasoactive systems by a baroreceptor independent mechanism). Protocol 2 included six patients studied before and 1 and 3 h after the intravenous administration of a plasma expander. In protocol 3, the plasma levels of endothelin and endotoxin were measured in 17 non-infected patients with cirrhosis and also in four patients with spontaneous bacterial peritonitis at diagnosis and following resolution of infection. RESULTS: Plasma endothelin was 3-5 times higher in patients with cirrhosis than in healthy volunteers. In healthy subjects, upright tilt and exercise were associated with a significant activation of the renin-aldosterone and sympathetic nervous systems and an increase in plasma endothelin. In patients with cirrhosis, upright tilt and exercise were associated with a significant increase and plasma volume expansion with a marked suppression of the renin-aldosterone and sympathetic nervous systems. However, in these patients none of these maneuvers affected plasma endothelin levels. In the patients with cirrhosis in protocol 3, there was no correlation between plasma endotoxin and endothelin. Resolution of peritonitis was associated with a marked fall in plasma endotoxin and no changes in plasma endothelin. CONCLUSIONS: These findings suggest that mechanisms other than effective hypovolemia or systemic endotoxemia are involved in the increased plasma endothelin of cirrhosis with ascites.

Blood Volume↗

Androgen receptors in hepatocellular carcinoma and surrounding liver: relationship with tumor size and recurrence rate after surgical resection.

BACKGROUND/AIMS: This study aimed to evaluate the parameters associated with the presence of androgen receptors in hepatocellular carcinoma and surrounding non-tumoral liver. Furthermore, we have assessed whether androgen receptor positivity influences disease recurrence after surgical resection. METHODS: Androgen receptor concentration was calculated by receptor binding assay in tumoral and non-tumoral liver in 43 patients (40 of them with cirrhosis) with hepatocellular carcinoma who underwent surgical resection. RESULTS: Androgen receptors were found in 28 of the tumoral and in 30 of the non-tumoral samples, at concentrations ranging between 5 and 211 fmol/mg protein. The presence of androgen receptors within the tumor was significantly related to a smaller tumor size. Thereby, 22 of the 29 nodules < or = 3 cm contained androgen receptors, while this occurred in only six of the 14 tumors larger than 3 cm (p < 0.05). In contrast, the only parameter associated with the presence of androgen receptors in the non-tumoral liver was a lower gamma-glutamyltranspeptidase concentration. Disease recurrence after surgical resection was not only related to some tumor characteristics (increased alfa-fetoprotein concentration, presence of satellites, differentiation degree), but also to the presence of androgen receptors in the surrounding liver. Thus, the probability of recurrence after 1- and 2-year follow up in patients with androgen-positive livers was 33% and 50%, respectively, while it was 0% and 20% in those with androgen-negative livers (p < 0.05). In contrast, the presence of androgen receptors within the tumor was not associated with a higher recurrence rate. CONCLUSIONS: These results show that only two thirds of hepatocellular carcinomas contained androgen receptors and that this feature was more frequent in small tumors. In addition, our data indicate that the presence of androgen receptors within the tumor does not imply a different outcome after surgical resection. In contrast, the presence of these receptors in the surrounding non-tumoral liver may be considered a risk factor for a higher incidence of disease recurrence.

Carcinoma, Hepatocellular↗

Effect of antihypertensive treatment on the increased beta 2-adrenoceptor density in patients with essential hypertension.

The effect of different antihypertensive drugs on the increased surface beta 2-adrenoceptor density in essential hypertension was evaluated to elucidate whether the possible effect of the treatment on these receptors was secondary to blood pressure decreases or a specific effect of the drugs. Thirty-nine untreated essential hypertensive patients and 28 normotensive control subjects were studied in basal conditions. Hypertensive patients were randomly assigned to three treatment groups: bisoprolol (10 mg/day, n = 15), enalapril (20 mg/day, n = 12), and verapamil SR (240 mg/day, n = 12), and were studied before and after 1 month of treatment. Plasma catecholamines were determined by a radioenzymatic assay. Surface beta 2-adrenoceptors were measured in intact lymphocytes by radioligand binding assay using the hydrophilic ligand [3H]-CGP12177. beta 2-adrenoceptor density was increased in hypertensive patients (P < .01). After treatment, mean blood pressure decreased similarly in the three groups, while plasma catecholamines showed no significant changes in any group. beta 2-adrenoceptor number decreased only in bisoprolol-treated patients (P < .05). Mean blood pressure decreases correlated with beta 2-adrenoceptor decrements only in bisoprolol-treated patients (r = 0.65, P < .05). beta 2-adrenoceptor density correlated with plasma epinephrine levels in the control group (r = -0.50, P < .01), but not in hypertensive patients before treatment. This correlation was also observed in hypertensive patients treated with bisoprolol (r = -0.52, P < .05), but not in those treated with verapamil or enalapril. Our results suggest that bisoprolol treatment reduces the increased surface beta 2-adrenoceptor density and restores its regulation by epinephrine in essential hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

[Corneal reinnervation after keratomileusis in situ and keratomileusis myopica--a comparison].

BACKGROUND: In a retrospective study corneal sensitivity after keratomileusis in situ and keratomileusis myopica was measured. METHOD: 5 points on the cornea were measured with the Draeger aesthesiometer at 18 eyes after keratomileusis myopica and at 66 eyes after keratomileusis in situ. RESULTS: The ingrowth of corneal nerve fibres is delayed after keratomileusis myopica compared to keratomileusis in situ because of delayed stromal repopulation of keratocytes and disturbances of stromal metabolism due to toxic effects of the cryopreservation solution.

Adolescent↗

Effects of long-term antiepileptic therapy on the catabolism of testosterone.

The serum levels of testosterone, sex hormone binding globulin, and free testosterone index were measured in 51 epileptic men (age 18-45) in order to assess the possible effects of antiepileptic drugs on sexual dysfunction. An analytical gas chromatography-mass spectrometry method was developed to assess the urinary excretion of testosterone, epitestosterone, androsterone, etiocholanolone, 11-OH androsterone and 11-OH etiocholanolone and to evaluate if the catabolism of testosterone had been increased. Twenty normal healthy males of similar age, 18-45 years, served as control group. Patients receiving polytherapy (n = 34) or monotherapy with carbamazepine (n = 8) or phenytoin (n = 9) showed higher levels of sex hormone binding globulin and testosterone, and lower levels of free testosterone than did the controls (P < 0.03). Urinary excretion of the metabolites androsterone and 11-OH androsterone was significantly reduced (P < 0.02) in the polytherapy group, while the monotherapy group showed only significant differences (P < 0.02) in the elimination of 11-OH androsterone. Our results suggest that an induction of the hepatic synthesis of sex hormone binding globulin may be the mechanism by which the antiepileptic drugs lower the levels of free testosterone in serum. However, the reduced excretion of androsterone and the normal levels of etiocholanolone show that the antiepileptic drugs do not produce an increase in the main catabolism pathway of testosterone.

Adolescent↗

The role of antiphospholipid antibodies in lupus nephropathy.

Although several clinical and morphological changes observed in overt systemic lupus erythematosus have been associated with the presence of antiphospholipid antibodies (aPL), the relation between these antibodies and lupus nephropathy (LN) is not clear. Twenty-three patients with biopsyproved LN were retrospectively studied (average age 28.5 +/- 12.3 years, all women) in order to investigate the relationship between the presence of aPL and clinical and immunobiological data. The average follow-up period was 55 +/- 42 months. The presence of aPL (IgG and IgM) was detected at least once in all patients by ELISA and/or lupus anticoagulant (kaolin time). Seven patients (30.4%) were aPL+, and the remainder aPL-. We did not find differences related to age, period of follow-up, blood pressure and livedo reticularis. However the prevalence of thrombosis, strokes and hemolysis was slightly higher in the aPL+ patients. The levels of antinuclear antibodies or anti-DNA antibodies, immunoglobulins and complement serum levels (C3, C4) were also similar in both groups. In the aPL+ group, proteinuria was significantly higher than in aPL- cases (2.21 +/- 1.5 and 0.91 +/- 1.07 g/24 h, respectively; p = 0.029). The renal histological pattern in both series was similar. However, microthrombosis in the glomerular capillary lumens was more frequent in the aPL+ group. The evolution of renal function was less favorable in aPL+ patients when compared with aPL- patients. We conclude that the presence of aPL in patients with LN is associated with several characteristics of renal impairment which may contribute to its evolution.

Adult↗

Increased plasma endothelin concentration in atherosclerotic renovascular hypertension.

The aim was to investigate circulating levels of immunoreactive endothelin (ir-ET) in atherosclerotic renovascular hypertension (RVH), and to assess the role of the kidneys in its overall plasma concentration. We studied 16 hypertensive patients with renal artery stenosis evidenced by angiography and admitted to hospital for the diagnostic evaluation of RVH by renal vein plasma renin activity (PRA) determinations. The right femoral vein was catheterized to simultaneously measure PRA and ir-ET in both renal veins and inferior vena cava below the origin of the renal veins. RVH was present in 9 patients as indicated by diagnostic PRA renal vein ratios and the remaining 7 patients were considered to have essential hypertension (EH). Patients with RVH showed a marked increase in systemic plasma ir-ET concentration (10.3 +/- 0.9 pg/ml). Despite a significant increase of PRA in the vein of the ischemic (IK) versus the contralateral (CK) kidney in patients with RVH, no significant differences in ir-ET concentration were observed between both kidneys. These results indicate that patients with RVH have increased circulating levels of ir-ET. However, the higher systemic plasma ir-ET do not arise from the renal circulation, since plasma ir-ET is significantly higher in systemic circulation than in renal veins.

Creatinine↗

Hormonal profiles in successful and unsuccessful implantation in IVF-ET after combined GnRH agonist/gonadotropin treatment for superovulation and hCG luteal support.

The luteal phase of in vitro fertilization-embryo transfer (IVF-ET) cycles has come under great scrutiny as the cause for the discrepancy between fertilization rates (> 70%) and pregnancy rates (around 20%) in most IVF programs is sought. The effects of the various stimulation protocols on the subsequent hormonal events of the luteal phase are both important and controversial but information regarding cycles where ovarian stimulation has been carried out with gonadotropins under pituitary suppression is scanty. The effect of high levels of estrogen in the late follicular phase and around the time of implantation is a matter of concern. As combined gonadotropin-releasing hormone analog (GnRH-a) gonadotropin treatment for superovulation is associated with supraphysiological ovarian steroid levels, both in the follicular and luteal phase of IVF cycles, we compared preovulatory (estradiol), midluteal (estradiol, progesterone and prolactin) and late luteal (estradiol and progesterone) hormone levels in on-going pregnancies, abortions and non-conception cycles in 222 patients accomplishing their first IVF-ET attempt who received such ovarian stimulation therapy. For both successful and unsuccessful implantation cycles, estradiol on the day of human chorionic gonadotropin (hCG) administration correlated positively with progesterone and estradiol levels and negatively with the progesterone/estradiol ratio in the midluteal phase. Mean peak follicular estradiol, midluteal estradiol and progesterone levels, mean mid- and late luteal progesterone/estradiol ratio, and mean midluteal prolactin concentration, were similar in the three groups studied. The mean late luteal estradiol and progesterone in the on-going pregnancy group were significantly higher than in non-conception cycles (p < 0.005 and p < 0.001, respectively) as a reflection of trophoblastic hCG production. Forty-eight patients (21.6%) had hyperprolactinemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Reversible decrease of surface beta 2-adrenoceptor number and response in lymphocytes of patients with pheochromocytoma.

To study the effect of chronic exposure to elevated plasma catecholamines on surface beta 2-adrenoceptor density, we measured these receptors in the lymphocytes of 9 patients with pheochromocytoma as well as in 27 healthy control subjects. Binding experiments were performed on intact lymphocytes using the hydrophilic ligand [3H]-CGP12177. Lymphocyte beta 2-adrenergic response was also measured in three patients. beta 2-adrenoceptor density (p < 0.01), and isoproterenol-stimulated increase in cAMP were reduced in patients with pheochromocytoma. Both parameters normalized (p < 0.05) when patients were reevaluated 4 weeks after tumor removal, coinciding with normalization of plasma epinephrine (r = -0.95, p < 0.01) and to log of plasma norepinephrine (r = -0.58, p < 0.05) in patients. We conclude that chronic catecholamine excess induces a decrease of lymphocyte beta 2-adrenoceptor surface number and response that is reversible upon normalization of plasma catecholamine levels. This regulation is mainly dependent on plasma levels of the hormone epinephrine, but norepinephrine may also play a regulatory role at supraphysiological levels.

Adrenal Gland Neoplasms↗

[Corneal reinnervation after lamellar refractive corneal surgery].

In a retrospective study corneal sensitivity after refractive autokeratoplasty for correction of myopia was measured. Thirty-eight patients operated on for keratomileusis in situ and 18 patients for keratomileusis myopica were examined with the Draeger esthesiometer between 1 and 23 months after surgery. Three measurements points were on the refractive disc, two others on the untouched cornea. After keratomileusis myopica, the corneal reinnervation is significantly delayed compared to keratomileusis in situ. In the first group sensitivity is normal after 2 years and in the second group after 1 year. Even refraction and visual acuity depend on metabolism and reorganization of the tissue after surgery. Besides retarded cell repopulation and disturbed stromal metabolism--caused by toxic and cryopreservation effects--the dissection depth of the refractive ablation is responsible for these phenomena.

Adolescent↗