Temperature effect on the zeta potential and fluoride adsorption at the alpha-Al2O3/aqueous solution interface.

The effect of temperature and pH on the zeta potential of alpha-Al2O3 and adsorption of fluoride ions at the alpha-Al2O3/aqueous solution interface has been investigated through electrophoretic mobility measurements and adsorption studies, to delineate mechanisms involved in the removal of fluoride ions from water using alumina as adsorbent. When the temperature increases from 10 to 40 degrees C, the pH of the point of zero charge (pH(pzc)) shifts to smaller values, indicating proton desorption from the alumina surface. The pH(pzc) increases linearly with 1/T, which allowed estimation of the standard enthalpy change for the surface-deprotonation process. Fluoride ion adsorption follows a Langmuir-type adsorption isotherm and is affected by the electric charge at the alpha-Al2O3/aqueous solution interface and the surface density of hydroxyl groups. Such adsorption occurs through an exchange between fluoride ions and surface-hydroxyl groups and it depends on temperature, pH, and initial fluoride ion concentration. At 25 and 40 degrees C, maximum fluoride adsorption density takes place between pH 5 and 6. Increasing the temperature from 25 to 40 degrees C lowers the adsorption density of fluoride.

Effect of telmisartan 80 mg once daily on 24-h blood pressure profile in patients with mild-to-moderate hypertension failing to respond to prior antihypertensive therapy.

Blood pressure is not adequately controlled in almost 50% of patients with hypertension who are in receipt of antihypertensive therapy. This multicentre, prospective, open-label trial was designed to determine whether or not once-daily telmisartan 80 mg reduced blood pressure during the last 6 h of the 24-h dosing interval in patients with mild-to-moderate hypertension who were unresponsive to previous antihypertensive therapy. The study comprised 100 patients (47 males, 53 females) who had failed to respond satisfactorily to prior treatment given for a minimum of 3 months. At screening, 24-h ambulatory blood pressure monitoring (ABPM) was conducted after the patient had been treated with the currently prescribed antihypertensive medication. Following 5 weeks of telmisartan 80 mg treatment, ABPM was repeated. Telmisartan significantly reduced mean systolic blood pressure, diastolic blood pressure (DBP) and pulse pressure compared with previous antihypertensive therapy over each time interval (24-h, morning, night-time and the last 6 h of the dosing interval [2.00 a.m.-8.00 a.m.]) analysed. In addition, more than 90% of patients responded successfully (clinic DBP <90 mmHg or a >10 mmHg reduction in clinic DBP) at the end of telmisartan treatment. In conclusion, telmisartan provides effective blood pressure control throughout the 24-h dosing interval in patients with mild-to-moderate hypertension who were unresponsive to previous antihypertensive medication.

Clinical efficacy and safety of telmisartan 80 mg once daily vs. atenolol 50 mg once daily in patients with mild-to-moderate hypertension.

The objective of this open-label, parallel-group comparative study was to assess the clinical efficacy and safety of once-daily treatment for 8 weeks with telmisartan 80 mg in comparison with atenolol 50 mg on systolic blood pressure (SBP) and diastolic blood pressure (DBP) in patients with mild-to-moderate hypertension (morning supine SBP 141-199 mmHg, DBP 95-114 mmHg). A total of 58 patients were enrolled. The comparability of the two treatment groups was statistically documented at the beginning of the study. Telmisartan was more effective than atenolol, with a decrease in SBP of 21.7 mmHg vs. 11.8 mmHg (p = 0.03) and a non-significant decrease in DBP of 14.7 mmHg vs. 10.1 mmHg. The safety profiles of both drugs were very similar; both drugs were well tolerated. In conclusion, once-daily telmisartan 80 mg is more effective than once-daily atenolol 50 mg in lowering SBP with no negative chronotropism. Furthermore, telmisartan was as well tolerated as atenolol in the treatment of mild-to-moderate essential hypertension in adults.

[Impact of the interval between surgery and radiotherapy in the initial phases of breast cancer in patients who did not receive systemic adjuvant therapy]. / Impacto del intervalo entre la cirugia y la radioterapia, en pacientes con cáncer mamario etapas iniciales, sin manejo sistémico adyuvante.

The purpose was to evaluate the effect of surgery-radiotherapy delay in the outcome of patients treated for early breast cancer, who did not receive adjuvant systemic therapy. We retrospectively analyzed data from 623 patients with breast cancer diagnosis stage I and II and with clinically negative axillary node, treated over a 18 year period. Patients were grouped in basis of the delay in the beginning of their radiation therapy, after surgery. Group 1 (270 patients) began radiation within 4 weeks of surgery, group 2 (285 patients) began 5-8 weeks after surgery and group 3 (68 patients) had a delay greater than 9 weeks. Median follow up in the total group was 64 months. Patients received a dose of 50-60 Gy to the tumor bed and/or 50 Gy to the nodes. Age, menopausal stage, clinical stage of disease, histological diagnosis, pathologic tumor size, and nodes metastasis, were similarly distributed among the 3 groups. Comparisons of local-control, overall 10-year survival and disease free survival curves between the three groups were done, no differences were observed among group 1 and 3, showed no significant differences in overall survival or local-control, however disease free survival was negatively affected by a delay in the administration of radiation (p = 0.05). It was concluded that delay in the beginning of radiation therapy longer than 8 weeks after surgery in breast cancer stage I and II patients treated without systemic therapy, decrease significantly disease free survival.

Spatial reproducibility of the ring and tandem high-dose rate cervix applicator.

PURPOSE: High-dose rate (HDR) applicators for uterine cervix brachytherapy are used with increasing frequency. Because multiple HDR fractions are required for treatment, the applicator position reproducibility is of most importance. To study this effect, the clinical data from patients with uterine cervix cancer were examined retrospectively to evaluate the interfraction geometric variation of the HDR applicator and its potential treatment impact. METHODS AND MATERIALS: Eighteen patients with invasive cervical cancer who were treated with definitive radiotherapy at William Beaumont Hospital were included in the study. Patients were treated with 45-50.4 Gy megavoltage external beam to the pelvis, and 35 Gy to the prescription point A from 7 fractions of HDR brachytherapy. The 3-dimensional (3D) interfraction geometrical variation of the ring and tandem (R & T) applicator was measured using predefined reference points in the 7 sets of orthogonal simulation films obtained prior to each HDR application. Spatial reproducibility of the R & T insertion and time-trend of the R & T position variation related to patient's anatomy during the treatment course were analyzed with respect to different groups of patients who had either early or advanced disease. RESULTS: The translational variation of the applicator position for all patients was 6.5, 5.9, and 7.7 mm (one standard deviation), respectively, in the patient's superior-to-inferior (SI), right-to-left lateral (RL), and anterior-to-posterior (AP) direction. The rotational variation was 3.4, 4.6, and 6.0 degrees (one standard deviation) in the patient's coronal, transverse, and sagittal planes. When the patients were grouped based on early disease or advanced disease, the latter demonstrated substantially larger variation (factor of 2) in the applicator position than the former. Furthermore, the time-trend of position variation was observable for both groups of patients. The variations occurred primarily during the first 3 fractions. CONCLUSIONS: Based on the good spatial reproducibility observed in our study, the current clinical procedure for the HDR R & T applicator placement is reliable. Positional reproducibility of the R & T applicator is highly dependent upon the size of tumor volume, which, in turn, deviates the applicator during the early course of HDR brachytherapy. Attention to the construction of the midline block is of paramount importance.

[Radiotherapy in vulvar cancer. Experience in the Hospital de Oncología, CMN, SXXI, IMSS]. / Radioterapia en el cáncer de vulva. Experiencia en el Hospital de Oncología, CMN, SXXI, IMSS.

Between 1986 and 1992, 42 patients with carcinoma of the vulva diagnosis, were treated at the Hospital de Oncologia, CMN, SXXI. Mean age was 63 years. There was 1 case stage I, 5 stage II, 25 stage III, 4 stage IV, 2 with recurrent disease and 5 patients could not be classified. Local control was reached in 60% of patients however, 12 patients developed local recurrence after surgery and/or radiation therapy, finally 43% of patients remained disease free after a mean of 19 months of followup. In the subset of advanced disease patients treated with radical or preoperative radiation therapy (27 patients), 41% of them remained without disease. Mean radiation doses for patients treated only with radiation therapy was 6500 cGy. Late vulvar fibrosis and acute desquamative dermatitis, were the morbidity more frequently observed. New directions in the management of vulvar cancer must be developed to improve treatment results, in patients with advanced disease.

Clinical acceptability of ACE inhibitor therapy in mild to moderate hypertension, a comparison between perindopril and enalapril.

The aim of this 3-month double-blind study was to assess the antihypertensive effect and acceptability of perindopril in comparison with enalapril in patients with mild to moderate essential hypertension. After a 4-week placebo run-in period, 161 patients with supine diastolic blood pressure (DBP) between 95 and 115 mmHg were randomized to receive perindopril 4 mg or enalapril 10 mg once daily. If supine DBP was higher than 90 mmHg, treatment was adjusted monthly, first by doubling the dose and then by addition of hydrochlorothiazide 12.5 mg. After 3 months of active treatment the decrease in supine and standing blood pressures was statistically significant within both groups but was not statistically different between groups. The percentage of patients (65%) who achieved supine DBP of < or = 90 mmHg in the perindopril group was not significantly different from the enalapril group (73%). Monotherapy resulted in control of supine DBP in 56% of the perindopril group and 58% of the enalapril group; the addition of hydrochlorothiazide resulted in control of supine DBP in 6% and 15% respectively. The number of withdrawals for adverse events was statistically significant between groups (0 in the perindopril group and 7 in the enalapril group, p = 0.01). During active treatment the most frequently reported complaints were headaches and cough; there was not statistically difference between groups. Changes in laboratory parameters were minor and not significantly different between the two groups except for serum glucose, potassium, and triglyceride levels. In conclusion, there was no significance between perindopril and enalapril in terms of efficacy. Clinical acceptability seems to be better in the perindopril group.(ABSTRACT TRUNCATED AT 250 WORDS)

[Lithopedion and cervico-uterine cancer. Presentation of a case]. / Litopedión y cáncer cervicouterino. Presentación de un caso.

One case of lithopedion incidentally diagnosis during diagnostic workup in a patient with invasive carcinoma of the cervix is described. Some aspects of carcinoma of the cervix and pregnancy are discussed.

[Dermatomyositis and adenosquamous carcinoma of the ovary. Report of a case]. / Dermatomiositis y carcinoma adenoescamoso del ovario. Informe de un caso.

A case of adenosquamous ovarian carcinoma in a 50 years old female is reported. The patient had marked improvement of her symptoms after resection of the tumor and chemotherapy. The knowledge of this association forces to rule out an ovarian carcinoma.

Quinapril versus atenolol in the treatment of mild to moderate essential hypertension.

A randomized, double-blind, parallel-group study was conducted to compare the safety and efficacy of the angiotensin-converting enzyme inhibitor quinapril with that of the beta-blocker atenolol. Fifty-six outpatients with mild to moderate hypertension were enrolled in the trial. After a 4-week washout period, 27 patients were treated with quinapril 20 mg once daily and 29 patients were treated with atenolol 50 mg once daily for 4 weeks. During a third 4-week period, the daily doses were adjusted on an individual basis. At the end of the 8-week treatment period, the systolic and diastolic blood pressures were significantly reduced in both groups of patients. Heart rate was significantly reduced only in the atenolol group. Adverse effects were inconsequential and comparable in both groups. Quinapril was shown to be a safe and effective treatment for patients with mild to moderate hypertension.

Differential effects of adrenergic agonists and phorbol esters on the alpha 1-adrenoceptors of hepatocytes and aorta.

Epinephrine, norepinephrine and phenylephrine stimulate phosphatidylinositol labeling with [32P]Pi in both rat hepatocytes and rabbit aorta. Methoxamine was a full agonist for this effect in rabbit aorta whereas cirazoline and oxymetazoline were partial agonists. In contrast, these three agents (methoxamine, cirazoline and oxymetazoline) were unable to stimulate phosphatidylinositol labeling in rat hepatocytes. Furthermore, cirazoline and oxymetazoline were able to displace the dose-response curve to epinephrine in rat hepatocytes, i.e., they behaved as antagonists. Binding competition curves of these agents with labeled adrenergic ligands indicate that the affinity of alpha 1-adrenergic receptors in these two tissues (aorta and liver) for the different agents tested was very similar. In addition it was observed that phorbol myristate-acetate inhibited in a dose-dependent fashion the epinephrine-mediated stimulation of phosphatidylinositol labeling in hepatocytes but was without effect on the action of the amine in aorta. Our data suggest that stereochemical differences for alpha 1-adrenergic activation in liver and aorta may exist and indicate that the ability of phorbol esters to inhibit alpha 1-adrenergic effects is not universal.

Possible involvement of two mechanisms of signal transduction in alpha 1-adrenergic action. Selective effect of cycloheximide.

We have previously suggested that the effects of alpha 1-adrenergic agents on hepatocyte metabolism involve two pathways: (a) a calcium-independent, insulin-sensitive process which is modulated by glucocorticoids; and (b) a calcium-dependent, insulin-insensitive process which is modulated by thyroid hormones. Cycloheximide stimulated ureogenesis through a prazosin-sensitive mechanism in liver cells (alpha 1-adrenergic). The effect of cycloheximide was insulin-insensitive and calcium-dependent. Furthermore, a clear effect of cycloheximide was observed in hepatocytes obtained from adrenalectomized animals, whereas no effect was observed in cell from hypothyroid rats. The effects of epinephrine and cycloheximide were blocked by phorbol esters in all the conditions tested. Binding competition experiments indicated that cycloheximide interacts with only a fraction of the alpha 1-adrenergic sites labeled with [3H]prazosin. It is suggested that cycloheximide activates preferentially one of the pathways involved in the alpha 1-adrenergic action in liver cells.

Effect of inositol and tri-iodothyronine on the hormonal responsiveness of hepatocytes obtained from partially hepatectomized rats.

Hepatocytes obtained from animals partially hepatectomized (72 h before the experiment) have a diminished responsiveness to alpha 1-adrenergic amines, vasopressin, angiotensin and glucagon and an increased responsiveness to beta-adrenergic amines. Administration of inositol or tri-iodothyronine to the hepatectomized animals induced a recovery in the hepatocyte responsiveness to the Ca2+-dependent hormones and abolished that to beta-adrenergic amines; the response to glucagon was not improved.

Metabolic effects and cyclic AMP levels produced by glucagon, (1-N alpha-Trinitrophenylhistidine,12-homoarginine)glucagon and forskolin in isolated rat hepatocytes.

[1-N alpha-Trinitrophenylhistidine,12-homoarginine]glucagon (THG) is a potent antagonist of the effects of glucagon on liver membrane adenylate cyclase. In isolated hepatocytes, this glucagon analogue was an extremely weak partial agonist for cAMP accumulation, and it blocked the stimulation of cAMP accumulation produced by glucagon. However, THG was a full agonist for the stimulation of glycogenolysis, gluconeogenesis and urea synthesis in rat hepatocytes, and did not antagonize the metabolic effects of glucagon under most of the conditions examined. Forskolin potentiated the stimulation of cAMP accumulation produced by glucagon or THG, but did not potentiate their metabolic actions. A much larger increase in cAMP levels seemed to be required for the stimulation of hepatocyte metabolism by forskolin than by glucagon or THG. This may suggest the existence of a functional compartmentation of cAMP in rat hepatocytes. The possible existence of compartments in cAMP-mediated hormone actions and the involvement of factors, besides cAMP, in mediating the effects of THG and glucagon is suggested.

Inositol administration restores the sensitivity of liver cells formed during liver regeneration to alpha 1-adrenergic amines, vasopressin and angiotensin II.

Hepatocytes obtained from rats partially hepatectomized 72 h before experimentation are insensitive to alpha 1-adrenergic amines, vasopressin, angiotensin II and ionophore A23187. However, if inositol is administered to the rats 24 and 48 h after surgery, the above-mentioned hormones stimulate glycogenolysis, gluconeogenesis and ureogenesis in the newly formed hepatocytes. Furthermore, ionophore A23187 is able to stimulate glycogenolysis in these cells, the mechanism through which inositol produces this effect being unknown. A rôle for phosphatidylinositol is suggested.

Roles of alpha 1- and beta-adrenergic receptors in adrenergic responsiveness of liver cells formed after partial hepatectomy.

The adrenergic receptor involved in the action of epinephrine changed dramatically during the process of active proliferation which follows partial hepatectomy. In control or sham-operated animals, the stimulation of glycogenolysis, gluconeogenesis and ureogenesis by epinephrine was mediated through alpha 1-adrenergic receptors. In contrast, in hepatocytes obtained from animals partially hepatectomized 3 days before experimentation, the receptor involved in the stimulation of these metabolic pathways by epinephrine was of the beta-adrenergic type. Interestingly, the adrenergic receptor involved in the metabolic actions of epinephrine, in hepatocytes from rats partially hepatectomized 7 days before experimentation was again of the alpha 1-subtype. Thus, it appears that during the process of liver regeneration which follows partial hepatectomy there is a transition in the type of adrenergic receptor involved in the hepatic actions of catecholamines from beta in the initial stages to later alpha 1. A similar transition seems to occur as the animal ages. Cyclic AMP accumulation in response to beta-adrenergic stimulation was significantly enhanced in hepatocytes obtained from rats partially hepatectomized 3 days before the experiment, as compared to control hepatocytes or cells obtained from animals operated 7 days before experimentation. This enhanced beta-adrenergic sensitivity is probably related to the increased number of beta-adrenergic receptors observed at this stage. However, a clear dissociation between cyclic AMP levels and metabolic effects was evidenced when the different conditions were compared. The number and affinity (for epinephrine or prazosin) of alpha 1-adrenergic receptors did not change at any stage of the process, which indicates that the markedly diminished alpha 1-adrenergic sensitivity observed in hepatocytes obtained from rats partially hepatectomized 3 days before experimentation is probably due to defective generation or intracellular processing of the alpha 1-adrenergic signal, rather than to changes at the receptor level.

Sensitivity of liver cells formed after partial hepatectomy to glucagon, vasopressin and angiotensin II.

During the active proliferation which follows partial hepatectomy, the sensitivity of liver cells to glucagon is markedly diminished. In hepatocytes obtained from rats partially hepatectomized 3 days before experiments were performed, the dose-response curves to glucagon were shifted to the right by about two orders of magnitude as compared to those of the control cells. Later on (7 days after surgery) the dose-response to glucagon was still shifted to the right but by only one order of magnitude. These data are consistent with the diminution in the number of glucagon receptors in liver plasma membrane during liver regeneration reported by other authors. No stimulation of glycogenolysis, gluconeogenesis or ureogenesis was produced by vasopressin or angiotensin II in hepatocytes from rats partially hepatectomized 3 days before experimentation. However, phosphatidylinositol labeling was stimulated in these cells to a similar extent as in the controls. The ionophore A23187 was also ineffective in stimulating glycogenolysis in these cells. Later, 7 days after surgery, the hepatic responsiveness to vasopressin and angiotensin II was restored. The data suggest that, during the initial stages of liver regeneration, the enzymatic machinery of the hepatocyte is not sensitive to calcium-signalling.

Trifluoperazine and chlorpromazine antagonize alpha 1- but not alpha2- adrenergic effects.

Trifluoperazine and chlorpromazine inhibited in a dose-dependent manner the stimulation of glycogenolysis, gluconeogenesis, and ureogenesis due to alpha 1-adrenergic stimulation in rat hepatocytes. In contrast, the antipsychotic agents were unable to block the inhibition of adenylate cyclase due to alpha 2-adrenergic activation in hamster adipocytes. Binding experiments showed that trifluoperazine and chlorpromazine at low concentrations displaced tritiated dihydroergocryptine binding from rat liver membranes (alpha 1-adrenergic sites), whereas very large concentrations of the phenothiazine derivatives were required to displace dihydroergocryptine from hamster adipocyte membranes (alpha 2-adrenergic sites). It is concluded that chlorpromazine and trifluoperazine are much more potent at alpha 1- than at alpha 2-adrenergic receptors. The use of rat hepatocytes and hamster adipocytes to study the alpha-adrenergic subtype selectivity of drugs is proposed.