Biomedical subjects

A Leiva

Publications and source records attributed to A Leiva.

At least 19 recordsLinked to original sources

PubMed2005

Poly(tetrahydropyranyl-2-methyl methacrylate): comparative study in solution and at the air/water interface.

In this work a comparative study of different molecular-weight fractions of the amphiphilic polymer poly(tetrahydropyranyl-2-methyl methacrylate) (PTHPMM) in solution and at the air/water interface is reported. The synthesis of the polymer was carried out in solution by radical polymerization. The polymer was fractionated and five fractions were studied in solution and at the air/water interface. The weight-average molecular weight M(w), the second virial coefficient A(2), and the radius of gyration R(g) were determined in toluene by static light scattering. Intrinsic viscosities [eta] of the polymer fractions in three solvents were obtained. The Kuhn-Mark-Houwink-Sakurada relationships were established. The Langmuir isotherms for different polymer fractions were obtained at the air/water interface by monolayer compression at constant temperature. The overlap surface concentrations were determined, and from these results the radius of gyration in two dimensions was calculated. The thermodynamic power of the toluene and the air/water interface for PTHPMM were estimated from the empirical relationship between the radius of gyration in two and three dimensions and the weight-average molecular weight.

Air↗

PubMed2001

Breathing pattern and gas exchange at peak exercise in COPD patients with and without tidal flow limitation at rest.

Expiratory flow limitation (FL) at rest is frequently present in chronic obstructive pulmonary disease (COPD) patients. It promotes dynamic hyperinflation with a consequent decrease in inspiratory capacity (IC). Since in COPD resting IC is strongly correlated with exercise tolerance, this study hypothesized that this is due to limitation of the maximal tidal volume (VT,max) during exercise by the reduced IC. The present study investigated the role of tidal FL at rest on: 1) the relationship of resting IC to VT,max; and 2) on gas exchange during peak exercise in COPD patients. Fifty-two stable COPD patients were studied at rest, using the negative expiratory pressure technique to assess the presence of FL, and during incremental symptom-limited cycling exercise to evaluate exercise performance. At rest, FL was present in 29 patients. In the 52 patients, a close relationship of VT,max to IC was found using non-normalized values (r=0.77; p < 0.0001), and stepwise regression analysis selected IC as the only significant predictor of VT,max. Subgroup analysis showed that this was also the case for patients both with and without FL (r=0.70 and 0.76, respectively). In addition, in FL patients there was an increase (p < 0.002) in arterial carbon dioxide partial pressure at peak exercise, mainly due to a relatively low VT,max and consequent increase in the physiological dead space (VD)/VT ratio. The arterial oxygen partial pressure also decreased at peak exercise in the FL patients (p < 0.05). In conclusion, in chronic obstructive pulmonary disease patients the maximal tidal volume, and hence maximal oxygen consumption, are closely related to the reduced inspiratory capacity. The flow limited patients also exhibit a significant increase in arterial carbon dioxide partial pressure and a decrease in arterial oxygen partial pressure during peak exercise.

Aged↗

PubMed2001

Management of sexually transmitted diseases in urban pharmacies in The Gambia.

This study aimed to describe the quality and costs of sexually transmitted disease (STD) case management in urban pharmacies in The Gambia, and explore pharmacy workers' (PWs) willingness to improve the STD care they provide. PWs from 24 registered pharmacies were interviewed in order to collect information on their knowledge and practices regarding management of STDs. The same pharmacies were visited by a male 'simulated client' (SC) to ascertain how urethral discharge syndrome (UDS) cases were managed in practice. Fifteen (63%) pharmacies were equipped for treatment of UDS, pelvic inflammatory disease (PID) and genital ulcer syndrome (GUS), according to national guidelines. Appropriate syndromic management for UDS was mentioned by 11% of PWs but actually given to 4.4% of the SC visits. None of the PID or GUS cases would be treated correctly. Forty-two per cent of PWs advised on partner notification, 38% on safe sex and 29% on treatment compliance in the SC visits. The reported costs for treatment of UDS, PID and GUS ranged from $2.5-$15.0. The cost of treatment actually purchased by the SC averaged $3.5 (range $1.5-$9.6) for UDS. Excluding the pharmacy sector from interventions will limit the impact of STD control measures. Regular training in syndromic management and rational drug use, with a concise manual for reference are recommended. Strategies to lower the cost of drugs should be explored.

Adult↗

PubMed2001

[Strength of inspiratory muscles in chronic heart failure and chronic pulmonary obstructive disease].

BACKGROUND: The maximal pressure generated by inspiratory muscles (PIMax) is an index of their strength which is diminished in both chronic obstructive pulmonary disease (COPD) and chronic heart failure (CHF). Although inspiratory muscle power output (IMPO), which includes both strength and velocity of shortening, has been shown to be reduced in COPD, there is no information regarding IMPO in CHF. AIM: To measure IMPO in patients with CHF and COPD. PATIENTS AND METHODS: We studied 9 CHF patients with functional capacity II and III and 9 patients with severe COPD. Eight normal subjects of similar ages were included as controls. Power output was measured using the incremental threshold loading test. RESULTS: Maximal IMPO was significantly reduced in both groups of patients. Power output developed with each increasing load was also diminished, basically as a consequence of a reduction in Vinsp. The degree of dyspnea at the end of the test was greater in COPD than in CHF patients and normal subjects. For a given level of power, dyspnea was also greater in patients than in normals subjects. There was no decrease in SpO2 during the test. CONCLUSIONS: IMPO is equally reduced in COPD and CHF patients. Power output is better related to dyspnea than PIMax, probably because of the inclusion of shortening velocity.

Analysis of Variance↗

PubMed2001

[Selective training of respiratory muscles in patients with chronic heart failure].

BACKGROUND: Patients with chronic heart failure have a lower inspiratory muscle strength and fatigue endurance. AIM: To assess the effects of selective training of respiratory muscles in patients with heart failure. PATIENTS AND METHODS: Twenty patients with stable chronic heart failure, aged 58.3 +/- 3 years with an ejection fraction of 28 +/- 9%, were subjected to respiratory muscle training with threshold valves. The load was fixed in 30% of maximal inspiratory pressure (PImax) in 11 and in 10% of PImax in nine. Two sessions of 15 minutes, 6 days per week, during 6 weeks were done. Degree of dyspnea (Mahler score), maximal oxygen uptake, distance walked in 6 minutes, respiratory muscle function and left ventricular ejection fraction were measured before and after training. RESULTS: Both training loads were associated to an improvement in dyspnea (+2.7 +/- 1.8 and +2.8 +/- 1.8 score points with 30% PImax and 10% PImax respectively), maximal oxygen uptake (from 19 +/- 3 to 21.6 +/- 5 and from 16 +/- 5 to 18.6 +/- 7 ml/kg/min with 30% PImax and 10% PImax respectively, p < 0.05), PImax (from 78 +/- 22 to 99 +/- 22 and from 72 +/- 34 to 82.3 cm H20 with 30% PImax and 10% PImax respectively), sustained PImax (from 63 +/- 18 to 90 +/- 22 and from 58 +/- 3 to 69 +/- 3 cm H20 with 30% PImax and 10% PImax respectively), and maximal sustained load (from 120 +/- 67 to 195 +/- 47 and from 139 +/- 120 to 192 +/- 154 g with 30% PImax and 10% PImax respectively). The distance walked in 6 min only increased in subjects trained at 30% PImax (from 451 +/- 78 to 486 +/- 68 m). CONCLUSIONS: Selective training of respiratory muscles results in a functional improvement of patients with chronic heart failure.

Breathing Exercises↗

PubMed2001

[Quality of life in patients with chronic obstructive pulmonary disease and the impact of physical training].

BACKGROUND: Health related quality of life (QoL) is severely impaired in COPD patients as a consequence of dyspnea and limited exercise tolerance, which lead to physical deconditioning and muscle atrophy resulting in weakness and fatigue. Psychosocial factors such as depression and anxiety also contribute to this impairment. AIM: To evaluate: a) the impact of COPD on quality of life, and b) the effect of 10 weeks of exercise training on exercise performance and on QoL. PATIENTS AND METHODS: The Spanish version of the Chronic Respiratory Questionnaire (CRQ) was applied to 55 COPD patients (FEV1 37 +/- 13% pred) for the assessment of QoL and in 30 of them submitted to exercise training for 10 weeks. Exercise performance was evaluated by measuring: six-minute walking distance, maximal workload (Wmax), maximal O2 consumption (VO2max) as well as endurance time, blood lactic acid, dyspnea and leg fatigue during a submaximal exercise. Trained patients were evaluated before and after training. RESULTS: COPD patients showed a reduction (mean +/- SD) in the four domains of the CRQ: dyspnea (3.1 +/- 0.9); fatigue (4.3 +/- 1.3); mastery (4.65 +/- 1.3), emotional function (4.1 +/- 0.97), and in Wmax and VO2max (52 +/- 16 Watt and 970 +/- 301 ml/min). No significant relationship between the impairment in exercise tolerance and in QoL was observed. Exercise training significantly improved the four domains of QoL (p < 0.0001), Wmax (p < 0.05), VO2max (p < 0.02) and endurance time (p < 0.001). Isotime exercise measurements of dyspnea, leg fatigue and lactic acid decreased after training (p < 0.001, each). No significant relation between changes in QoL and changes in exercise performance were observed. CONCLUSIONS: Our results demonstrate that QoL is seriously impaired in patients with COPD and confirm: (a) the lack of relationship of QoL to the usually measured physiological parameters, and (b) the beneficial effect of exercise training on QoL through the reduction of symptoms. These findings stresses the need of measuring quality of life in our patients if we want to evaluate the impact of therapeutic procedures on well-being from the patients' perspective.

Aged↗

PubMed2000

Role of inspiratory capacity on exercise tolerance in COPD patients with and without tidal expiratory flow limitation at rest.

Expiratory flow limitation promotes dynamic hyperinflation during exercise in chronic obstructive pulmonary disease (COPD) patients with a consequent reduction in inspiratory capacity (IC), limiting their exercise tolerance. Therefore, the exercise capacity of patients with tidal expiratory flow limitation (FL) at rest should depend on the magnitude of IC. The presented study was designed to evaluate the role of FL on the relationship between resting IC, other respiratory function variables and exercise performance in COPD patients. Fifty-two patients were included in the study. Negative expiratory pressure (NEP) uptake (VO2,max) were measured during an incremental symptom-limited cycle exercise. Twenty-nine patients were FL at rest. The IC was normal in all non-FL patients, while in most FL subjects it was decreased. Both WRmax and VO2,max were lower in FL patients (p<0.001, each). A close relationship of WRmax and O2,max to IC was found (r=0.73 and 0.75, respectively; p<0.0001, each). In the whole group, stepwise regression analysis selected IC and forced expiratory volume in one second (FEV1)/forced vital capacity (FVC) (% predicted) as the only significant contributors to exercise tolerance. Subgroup analysis showed that IC was the sole predictor in FL patients, and FEV1/FVC in non-FL patients. Detection of flow limitation provides useful information on the factors that influence exercise capacity in chronic obstructive pulmonary disease patients. Accordingly, in patients with flow limitation, inspiratory capacity appears as the best predictor of exercise tolerance, reflecting the presence of dynamic hyperinflation.

Aged↗

PubMed2000

Depletion of brain glutathione potentiates the effect of 6-hydroxydopamine in a rat model of Parkinson's disease.

In order to examine the possible role of rat brain glutathione depletion by diethyl maleate (DEM) in the potentiation of 6-hydroxydopamine (6-OHDA) neurotoxicity, the relationships between both effects were evaluated using the circling behavior test (CBT), and determining striatal glutathione S-transferase (GST)-specific activity. There were significant differences between the two studied groups: 6-OHDA and DEM + 6-OHDA lesioned animals in striatal glutathione (GSH) concentration at the moment of the lesion with 6-OHDA and also at the end of the experiment (30 d after 6-OHDA lesion). The circling behavior test following the administration of amphetamine was qualitatively different between both groups of simple- and double-damaged animals. In accordance with our results, DEM injury makes the animals more susceptible to brain-oxidative damage by 6-OHDA, which can indicate that in the double-damaged animal group, DEM could induce potentiation of the toxicity through striatal glutathione depletion.

Animals↗

PubMed1999

Adsorption Behavior of Amphiphilic Polymers.

The work reported here involves a study of the adsorption behavior of some amphiphilic polymers containing alternating copolymers of stearyl methacrylate, mono-n-octylitaconate, styrene, and 1-octadecene with maleic anhydride. We have employed chromatographic and thermogravimetric measurements in order to characterize the adsorption process. Silica gel was the stationary phase in the case of the polar column, and a mixture of THF/toluene or chloroform/toluene as the mobile phase. Toluene content in the mobile phase affects the capacity to desorb the polymer from the interface. The adsorption of the polymers onto silica substrates from toluene between other solvents has been measured also with static experiments. The results are discussed in terms of the incorporation of hydrophilic groups as maleic-anhydride or hydrophobic groups as stearyl and n-octyl chains. The solvent effect was also considered. Comparison of the adsorption isotherms for PA-18 onto hydrophilic substrate (Aerosil 200) from two different solvents shows strong competition of THF with the surface functionality of the substrate by the PA-18. Copyright 1999 Academic Press.

Journal Article↗

PubMed1999

[Effects of inspiratory muscle training on the oxygen cost of breathing in patients with chronic obstructive pulmonary disease].

BACKGROUND: Patients with chronic obstructive pulmonary disease have an increased inspiratory work, since they must overcome high loads due to increased airway resistance. AIM: To determine if the reduction in the metabolic cost of exercise observed in patients with chronic obstructive pulmonary disease (COPD) after inspiratory muscle training, was due to a reduction in the oxygen cost of breathing. PATIENTS AND METHODS: Nine patients with COPD (FEV1 39 +/- 13%) subjected to inspiratory muscle training, using a training load of 30% of maximal inspiratory pressure, during 10 weeks; 5 patients with COPD (FEV1 44 +/- 18%) not subjected to training, and 7 healthy controls (FEV1 110 +/- 10%) were studied. The cost of breathing was calculated as the difference in VO2 measured at rest and after breathing a gas mixture containing air and 5% CO2. Exercise VO2 was measured at submaximal exercise. RESULTS: Oxygen cost of breathing was increased in patients with COPD and it was inversely correlated with FEV1 (r = -0.86 p < 0.001). Inspiratory muscle training increased maximal inspiratory pressure and decreased exercise VO2. Oxygen cost of breathing increased in six and decreased in three trained patients. Changes in this parameter after training did not correlate with the reduction in exercise VO2 or the increment in maximal inspiratory pressure. CONCLUSIONS: The reduction in exercise VO2 after inspiratory muscle training is not due to a reduction in the oxygen cost of breathing.

Aged↗

PubMed1999

[Experience with laparoscopic surgery for adnexal masses at the Regional Hospital of Temuco, Chile].

BACKGROUND: Laparoscopic surgery has clear advantages over open surgical procedures. In gynecology, laparoscopic surgery for adnexal masses in pre or post menopausal women has been used for several years. AIM: To report the experience with gynecologic laparoscopic surgery at the Temuco Regional Hospital. PATIENTS AND METHODS: Between 1996 and 1998, laparoscopic surgery was done in 96 patients aged 16 to 56 years and open surgery in 56 patients aged 15 to 74 years, with a clinical or ultrasound diagnosis of adnexal masses or ovarian dermoid cysts. RESULTS: The most frequent tumors excised were epithelial and germinal cell. Laparoscopic surgery required a mean operative time of 69.9 min and it had a 3.1% of complications. Women subjected to this type of surgery had a mean hospital stay of 3.1 days and the mean postoperative stay was 2 days. Open surgery required an operative time of 69 min and it had no postoperative complications. The mean hospital stay for women subjected to this type of procedure was 9.5 days. CONCLUSIONS: Women subjected to laparoscopic surgical procedures for adnexal masses had a shorter hospital stay than women subjected to open surgical procedures.

Adnexal Diseases↗

PubMed1998

Effect of inspiratory muscle training with an intermediate load on inspiratory power output in COPD.

There is very little information about the effect of inspiratory muscle training on inspiratory flow (V'I) and thus on power output (PO) in patients with chronic obstructive pulmonary disease (COPD). In this study we aimed to evaluate the changes induced by training on the determinants of PO. Thirty one patients with severe COPD were randomly divided into: Group 1, trained with 30% maximal inspiratory pressure (PI,max); Group 2, with 10% PI,max; and Group 3 also trained with 30% PI,max, but the breathing pattern was evaluated while performing the training manoeuvres along inspiratory muscle training (IMT). All groups used a threshold device for 10 weeks. The PO for each of the loads during an incremental threshold test was evaluated prior to and after training. Maximal PO (POmax) increased in all groups, but the increment was higher in groups trained with 30% PI,max (p<0.005), mainly due to an increase in V'I. Group 3 showed a progressive increase in V'I (p<0.001) during the training manoeuvres in spite of an increase in load along IMT. In addition, the load after IMT was overcome with a shorter inspiratory time (tI) (p<0.02), a smaller tI/total duration of the respiratory cycle (t(tot)), (p<0.001) with no change in tidal volume or t(tot). The increment in POmax in this group correlated with the V'I generated while training (r=0.85; p<0.0001). We conclude that in patients with chronic obstructive pulmonary disease, the use of an intermediate threshold load for training improves power output mainly by increasing inspiratory flow, an effect consistent with an increase in shortening velocity of inspiratory muscles.

Aged↗

PubMed1997

Lesion of nigrostriatal neurons by 6-hydroxydopamine induces changes in rat brain glutathione-S-transferase.

Wistar rats were lesioned into the nigrostriatal pathway with 6-OHDA. The D-amphetamine-induced circling behavior test was performed to evaluated lesion efficiency. Animals that showed more than 620 turns/90 min were named totally lesioned animals (TLA). The group of rats that performed less than 620 turns/90 min were named partially lesioned animals (PLA). The contents of DA and its catabolites in the striata of these groups, and in the same tissue of the untreated animals, were measured. Moreover, the striatal glutathione-S-transferase (GST) specific activity for all groups was tested, and the kinetics parameters for GST purified from the whole brain were evaluated from other three similar groups. The striatal DA depletion on TLA was greater than in PLA. Striatal GST activity showed a significantly bilateral increase in PLA, whereas TLA exhibited only and ipsilateral augment. There were also differences between groups about the kinetic parameters of the purified brain enzyme. The possible role of GST on the interindividual lesion response difference was analyzed.

3,4-Dihydroxyphenylacetic Acid↗

PubMed1997

Inspiratory muscle training in chronic airflow limitation: effect on exercise performance.

The effect of inspiratory muscle training (IMT) on exercise capacity in patients with chronic airflow limitation (CAL) has been debated. The present study was planned to further investigate the effects of IMT on exercise performance. Twenty patients (aged 62+/-1 yrs; forced expiratory volume in one second/forced vital capacity (FEV1/FVC) 36+/-2%) were trained 30 min daily for 6 days a week during 10 weeks, with either 30% (Group 1) or 10% (Group 2) of peak maximal inspiratory pressure (PI,max) as a training load. Exercise performance was evaluated by the distance walked in 6 min (6MWD) and by changes in oxygen consumption (V'O2) and minute ventilation (V'E) during a progressive exercise test. Changes in PI,max and dyspnoea were also measured. Results showed a significant increment in peak PI,max in both groups, whereas dyspnoea and 6MWD improved only in Group 1 (p<0.05 and p<0.01, respectively). No increment in maximal workload or in peak V'O2 was observed in either group. Patients in Group 1, however, showed a reduction in V'E and V'O2 for the same exercise. A correlation between changes in V'E and V'O2 during a workload of 75 kpm x min(-1) was observed in Group 1 (r=0.92; p<0.001). We conclude that inspiratory muscle training using a load of 30% peak maximal inspiratory pressure, improves dyspnoea, increases walking capacity and reduces the metabolic cost of exercise.

Breathing Exercises↗

PubMed1995

[Clinical effects of inspiratory muscle training in patients with chronic airflow limitation].

The clinical role of inspiratory muscle training (IMT) in chronic obstructive pulmonary disease (COPD) has not been established, because data on its clinical effect is scarce and controversial. To further investigate these aspects we studied 20 COPD patients (FEV1 37 +/- 3% P) who were randomly and double blindly trained for 30 minutes a day during 10 weeks using a threshold inspiratory trainer with either 30% (group 1) or 10% (group 2) of PIMax as a training load. The training load was crossed after each patient completed 10 weeks of training. Effects were assessed through changes in PIMax, dyspnea through the transition dyspnea index (ITD) and the respiratory effort with Borg's score. Walking capacity was measured with the six minutes walking distance test (6WD) and depression symptoms with Beck's score. Daily life activities were also assessed. Results showed that after 10 weeks of IMT, PIMax increased in both groups (p < 0.05), dyspnea improved in group 1 as compared to group 2 (p < 0.04), 6WD increased significantly in patients of group 1, who also complained of less dyspnea (p < 0.05). Depression scores fell significantly in group 2. Daily activities improved more in group 1. After the crossover patients in group 1 disclosed a significant deterioration in PIMax whereas group 2 disclosed significant improvements in PIMax, dyspnea and 6WD. We conclude that IMT using a threshold device with 30% PIMax is a useful procedure for the treatment of severe COPD patients.

Activities of Daily Living↗

PubMed1994

High-performance liquid chromatographic determination of norepinephrine, epinephrine and dopamine in human foetal adrenal gland.

The purpose of this work was to characterize the human foetal adrenal gland (HFAG) by studying norepinephrine (NE), epinephrine (E), and dopamine (DA) levels in foetuses with ages ranging from 10 to 18 weeks, as a source of chromaffin cells for basic and clinical research, in the treatment of Parkinson's disease. The HFAGs were obtained from ten abortions with foetal ages ranging from 10-12 (n = 7) to 13-18 (n = 3) weeks. For the simultaneous detection of NE, E, and DA a high-performance liquid chromatographic (HPLC) procedure with electrochemical detection was employed. The concentrations found (ng/mg wet weight) were 24.24 +/- 7.06 for NE, 3.56 +/- 2.97 for E and 0.45 +/- 0.27 for DA at 10-12 weeks and 14.91 +/- 9.94 for NE, 8.18 +/- 8.79 for E and 0.16 +/- 0.05 for DA at 13-18 weeks. The DA:E ratio present in HFAG between 10 and 12 weeks was 100 times higher than that reported by other authors in adult adrenal medulla.

Adrenal Glands↗

PubMed1994

Inspiratory muscle training in chronic airflow limitation: comparison of two different training loads with a threshold device.

The usefulness of inspiratory muscle training (IMT) in chronic airflow limitation (CAL) patients is a controversial issue, mainly due to differences in the training load. To further evaluate this aspect, we studied the effect of the magnitude of the load using a threshold pressure trainer. Ten CAL patients (5 males, 5 females) 67 +/- 2 yrs (mean +/- SEM) and forced expiratory volume in one second (FEV1) 36 +/- 2% pred, were trained for 30 min a day using a load of 30% of their maximal inspiratory mouth pressure (PImax) (Group 1). Another 10 CAL patients (5 males, 5 females), 73 +/- 2 yrs and FEV1 37 +/- 2% pred), were trained using only 12% of their PImax (Group 2). Training was assessed by PImax, inspiratory muscle power output (IMPO), sustainable inspiratory pressure (SIP), maximal inspiratory flow rate (VImax), pattern of breathing during loaded breathing, Mahler's dyspnoea score, and the 6 min walking distance (6MWD). After 5 weeks of training, Group 1 exhibited significant increments in: PImax (34 +/- 11%); IMPO (92 +/- 16%); SIP (36 +/- 9%); and VImax (34 +/- 13%). Dyspnoea was also reduced, and the 6MWD increased by 48 +/- 22 m. We observed no significant changes in Group 2. During loaded breathing, Group 1 showed a significant increment in tidal volume (VT) and mean inspiratory flow (VT/TI), and a reduction in inspiratory time (TI). In Group 2, VT and VT/TI also increased significantly, but the breathing frequency increased with a reduction of expiratory time.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

PubMed1990

[Intestinal obstruction caused by a pacifier].

The case of an infant who developed intestinal obstruction following ingestion of a pacifier is reported. Progression of this foreign body in the intestinal lumen was extremely slow because of the deformability of the material and laparotomy was required. The authors point out that this is a difficult diagnosis and that regulations on manufacturing standards should be enforced in order to avoid such accidents.

Foreign Bodies↗