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Biomedical subjects

O González

Publications and source records attributed to O González.

At least 19 recordsLinked to original sources
PubMed2006

Single-stage revision of peri-prosthetic infection following total elbow replacement.

This study reviews the predisposing features, the clinical, and laboratory findings at the time of diagnosis and the results of single-stage revision of prosthetic replacement of the elbow for infection. Deep infection occurred in six of 305 (1.9%) primary total elbow replacements. The mean follow-up after revision was 6.8 years (6 months to 16 years) and the mean age at the time of revision was 62.7 years (56 to 74). All six cases with infection had rheumatoid arthritis and had received steroid therapy. The infective organism was Staphylococcus aureus. Four of the six elbows had a developed radiolucency around one component or the other. Successful single-stage exchange arthroplasty was carried out with antibiotic-loaded cement in five of the six cases. In one, the revision prosthesis had to be removed following recurrence of the infection. The functional result was good in three elbows, fair in one, poor in one and fair in the resection arthroplasty.

Aged↗
PubMed2005

The occurrence of mycoplasmas in the lungs of swine in Gran Canaria (Spain).

The study was conducted to investigate the mycoplasmal flora in the lungs of pigs with enzootic pneumonia at Gran Canaria (Spain). From 54 pneumonic lungs collected at an abattoir, 85 isolates were cultivated. On the basis of cultural and biochemical characteristics, the isolates were preliminarily identified as Mycoplasma species. Using different species-specific PCRs, 40, 27, 11 and 7 of the isolates were identified as M. hyorhinis, M. hyopneumoniae, M. hyosynoviae and M. flocculare, respectively. Nine of the M. hyopneumoniae cultures were found to be in mixed culture with M. flocculare as demonstrated by PCR. By use of a M. flocculare antiserum it was possible to eliminate M. flocculare from M. hyopneumoniae mixed cultures. This study is the first report on isolation of porcine mycoplasmas at Gran Canaria (Spain).

Animals↗
PubMed2002

Physiological response of freshwater microalga (Chlorella vulgaris) to triazine and phenylurea herbicides.

The effects of two herbicides used wide-spread, isoproturon (phenylurea) and terbutryn (triazine), on growth, dry weight, elemental composition, photosynthetic pigments and protein content, and cell volume assayed by flow cytometry in the freshwater microalgae Chlorella vulgaris were studied. Different parameters for algal activity show widely different sensitivities to these aquatic pollutants. After 96 h of herbicide exposure, terbutryn was the strongest inhibitor of growth, giving an EC50 value for growth twice lower than that for isoproturon cultures (EC50 terbutryn=0.097 microM; EC50 isoproturon=0.199 microM). However, lower concentrations of the triazine herbicide provoked an increase in the cellular density and growth rate of this microalga, not observed in the phenylurea-treated cultures. Cellular volume and dry weight of C. vulgaris cells were increased strongly in the presence of isoproturon and terbutryn. Other cellular parameters, such as pigment and protein content, were stimulated with both herbicides at higher concentrations.

Adaptation, Physiological↗
PubMed2001

Effect of low temperature on tracheal smooth muscle contractile and relaxing responses evoked by electrical field stimulation.

OBJECTIVE: The aim of this work was to evaluate the effect of low temperature (LT) on the contractile and relaxing responses of rat tracheas (RTs) after electrical field stimulation (EFS). METHODS: Voltage-dependent (10-60 V, 40 Hz) and frequency-dependent (0.1-60 Hz, 40 V) response curves were constructed at 37 and 18 degrees C after the activation of tracheal intramural nerves with a Grass S88 stimulator. The EFS that produced half of the maximum contractile response (ES50) at 37 or 18 degrees C was determined and considered as the dependent variable. The % relaxation of pre-contracted RTs (EFS; 5 Hz, 40 V) to sodium nitroprusside (SNP; 1 x 10(-7) - 1 x 10(-3) M) isoproterenol (ISP; 1 x 10(-9) - 1 x 10(-5) M) and to 20 mM potassium chloride (KCl) after low-K+ inhibition of the Na+/K+ pump at 18 and 37 degrees C were determined. RESULTS: We found that the tracheal responses elicited by EFS at 37 and 18 degrees C were completely blocked with 1 microM atropine. LT slightly increases the voltage-dependent ES50, from 33.7 +/- 4.0 to 37.8 +/- 4.8 V, n = 5 but decreases the frequency-dependent ES50 from 19.3 +/- 4.3 to 1.0 +/- 0.28 Hz, n = 5, p < 0.05. Relaxing responses to SNP, ISP and KCl at 37 degrees C correspond to 43.5 +/- 6, 36.7 +/- 12 and 12.1 +/- 1.5% respectively. No significant tracheal relaxations were elicited at 18 degrees C. Our results indicate that in RTs, LT enhances tracheal sensitivity to EFS and decreases it in response to bronchorelaxants. The LT-dependent enhanced contractile response is observed only after a low frequency stimulation range (0.1-20 Hz), that is very close to the frequency of vagal stimuli required for inducing bronchoconstriction in vivo. Furthermore, LT abolishes the sensitivity of RTs to exogenously added bronchorelaxants (NO and ISP). In addition, LT appears to decrease the Na(+)-K+ pump activity; this effect has been associated with increased tracheal hyperreactivity in vitro. ACH appears to be the main endogenous neurotransmitter involved on neurally mediated contractile responses at 37 and 18 degrees C. CONCLUSION: Low temperature enhances the contractile response of rat tracheas in response to endogenous ACH release. The effect of LT is limited to frequencies below 20 Hz, which are within the physiological range required for bronchoconstriction. Furthermore, LT severely impairs the sensitivity of RTs to relaxant stimuli, either of endogenous of exogenous origin.

Animals↗
PubMed2000

Effect of the airway epithelium on the contraction of rat isolated trachea under conditions of low temperature.

BACKGROUND: The exposure of the airways to low temperature (LT) is a well-known trigger of bronchoconstriction and asthma. However, the mechanisms involved in this response are not well understood. In particular, the specific role of the airway epithelium in the response to LT has not been well established. OBJECTIVE: The purpose of this work is to study the regulatory role of the airway epithelium in the contractile response of the rat trachea under conditions of LT. METHODS: Isolated rat tracheas were stimulated with acetylcholine (ACH) at 37 and 18 degrees C, and dose-response curves were generated in epithelium-intact or epithelium-denuded conditions. EC(50) and E(max) were determined under these conditions. RESULTS: Epithelium denudation at 37 degrees C, increases the tracheal sensitivity to ACH, (EC(50) from 5.9 to 2.6 microM, p = 0. 003). The effects of denudation were even more pronounced at 18 degrees C. E(max) was significantly decreased under these conditions. Exposure of intact tracheas to 18 degrees C also produced a significant increase in tracheal sensitivity (EC(50) from 5.9 to 1.5 microM, p = 0.0004), although no changes in E(max) were noted. CONCLUSIONS: These results strongly suggest that the airway epithelium diminishes the sensitivity of the airway smooth muscle to ACH at 37 and 18 degrees C, and that it is also needed to observe the maximal contractile response under LT conditions. Therefore, the spasmogenic effect of low temperature is significantly potentiated by the absence of airway epithelium.

Acetylcholine↗
PubMed1999

Multiple solitary leiomyomata of the esophagus.

The present report communicates a case of multiple solitary leiomyomata of the esophagus. This is an uncommon condition in which multiple, non-confluent, benign esophageal tumors arise in the same patient. The ideal treatment is enucleation of the lesions, but when these are--as in the case reported--huge and annular, or affect the gastroesophageal junction, resection of the gullet must be performed.

Adult↗
PubMed1999

Heterotopic gastric mucosa in the upper esophagus ("inlet patch"): a rare cause of esophageal perforation.

We report the case of a 21-yr-old woman who presented with a perforation of an upper esophageal ulcer on a patch of gastric-type mucosa. Despite surgical closure of the perforation and reinforcement with a pleuro-muscular flap the patient developed an esophageal leakage and died in the postoperative period. Heterotopic gastric mucosa in the upper esophagus is usually an asymptomatic abnormality, discovered incidentally during endoscopic studies carried out for some other reason; however, complications secondary to the inlet patch acid secreting capacity can arise, and this has to be kept in mind to elude life-threatening conditions.

Adult↗
PubMed1999

[High-frequency jet ventilation with a proximal injector in a case of surgery of the tracheal carina].

A 44-year-old man underwent surgery requiring medial sternotomy of resection of a tracheal carcina tumor. High frequency jet ventilation was used during tumor resection and reconstruction of the carina in order to shorten the time of surgery and to provide a nearly immobile and unobstructed surgical field. The only noteworthy complication was a tendency to respiratory acidosis that resolved without sequelae in the operating room once the trachea was closed. The anesthetic challenges presented by the various techniques used throughout history for such an interesting and complex type of surgery are briefly summarized. We also discuss the role of high frequency jet ventilation on surgery involving the major airways.

Adult↗
PubMed1998

Prospective biochemical and scintigraphic evaluation of autografted normal parathyroid glands in patients undergoing thyroid operations.

BACKGROUND: Parathyroid autotransplantation has been widely used in thyroid operations. Few studies have assessed the function of the autotransplanted glands. The aim of this study was to evaluate the success rate, pattern of biochemical function, and scintigraphic appearance of parathyroid autografts in patients undergoing thyroid operations. METHODS: Twelve patients in whom 1 parathyroid gland was removed during thyroid operation were included. Glands were fragmented and autografted into individual pockets in the brachioradialis muscle of the nondominant forearm. Parathyroid hormone levels were measured in both arms the day of autotransplantation and 2 weeks and 1, 2, 3, and 6 months after operation. Serum calcium levels were also measured at each interval. Sestamibi scanning was performed 6 months after operation in 7 patients. RESULTS: All patients were women with a mean age of 50 +/- 15 years. Serum calcium levels were normal during follow-up. A gradient of parathyroid hormone level of 1.5 or greater between the autotransplanted and nontransplanted arm was found in 10 patients. Isotope uptake at the site of the parathyroid autotransplant was demonstrated in the 7 patients evaluated. CONCLUSIONS: Biochemical function of autotransplanted normal parathyroid tissue was documented in 83% of the patients. Sestamibi scintiscans were able to identify the autotransplanted tissue.

Adult↗
PubMed1998

Effect of exercise on erythrocyte beta-adrenergic receptors and plasma concentrations of catecholamines and thyroid hormones in Thoroughbred horses.

The effects of exercise stress on erythrocyte beta-adrenergic receptor characteristics and plasma concentrations of adrenaline, noradrenaline and thyroid hormones were studied in Thoroughbred racehorses during rest and after exercise. Five minutes after a maximal speed race of 1200 +/- 200 m (mean +/- s.d.), both plasma adrenaline and noradrenaline concentrations increased with respect to basal values (from 2.48 +/- 0.15 to 3.83 +/- 0.27 and from 2.13 +/- 0.11 to 3.53 +/- 0.27 nmol/l respectively). The increment of adrenaline was greater in high performance (HP) as compared to low performance (LP) horses (76.9 vs. 43.5%), in accordance with the contribution of the adrenal medulla in the sympathoadrenal response to exercise. Triiodothyronine (T3), but not thyroxine (T4) levels increased 5 min after exercise (from 55.6 +/- 2.9 to 81 +/- 3.7 ng/dl and from 0.67 +/- 0.04 to 0.70 +/- 0.05 micrograms/dl respectively). No differences were observed in basal values of thyroid hormones or in the percentage of T3 increment, when comparing HP vs. LP horses. Erythrocyte membranes obtained 5 min after racing showed decreased concentrations of beta-adrenergic receptors (beta-AR) and dissociation constant as compared to basal values (50.1 +/- 7.0 vs. 95.7 +/- 12.0 fmol/mg protein and 0.97 +/- 0.24 vs. 2.04 +/- 0.3 nmol/l respectively). This temporal pattern suggest that the observed changes in beta-AR characteristics could be mediated by catecholamines, but not by thyroid hormones, in this model. This down regulation of beta-AR may act as a protecting mechanism preventing the erythrocytes from the decrease in membrane fluidity known to be provoked by adrenergic agonists. The accomplished study showed that, in the Thoroughbred horse, there is a homeostatic response to race stress, characterised by a sudden increase in plasma catecholamines and T3 and a parallel decrease in beta-AR concentration on the erythrocyte membrane. In this way the racing horse could rapidly adjust its metabolism to the exercise stress, but at the same time override one possible undesirable side-effect caused by these hormonal changes. Further studies will be required to establish performance-related differences occurring in endocrine changes.

Animals↗
PubMed1997

Chronic intraventricular infusion with NGF improves LTP in old cognitively-impaired rats.

Aged (21 months) cognitively-impaired male Sprague-Dawley rats received intraventricular infusion of nerve growth factor (NGF) or cytochrome C (Cit C) for 14 or 28 days using miniosmotic pumps and were evaluated either 1 week or 3 months after treatment. Groups of untreated young, aged-impaired and aged non-impaired rats were also evaluated. Under narcose recording and stimulating electrodes were stereotactically implanted in the dentate gyrus and the perforant path. The stimulation intensity was individually adjusted to obtain a half-maximal population spike (P) for test stimuli and a quarter-maximal for tetanization. The amplitude and latency of P and the slope (S) of the field EPSP were determined before and at 2, 5, 15, 30 and 60 min after tetanization at 400 Hz. Paired stimuli at 30 ms interval were also applied before and after tetanization. Aged, cognitively impaired rats showed an absent S potentiation and a delayed P potentiation, both in amplitude and latency, while non-impaired rats behaved like the young controls. Paired pulse inhibition showed no difference among groups before or after tetanization suggesting that the impaired potentiation is not due to an increased retroactive inhibition. NGF treatment ameliorates LTP deficits to levels equivalent to non-impaired rats, while Cit C controls showed no improvement. No differences appear among NGF treated groups, but evidence suggest that the animals evaluated 3 months after treatment developed a stronger potentiation.

Aging↗
PubMed1997

Comparative effects of beta2-adrenergic agonists on muscle waste associated with tumour growth.

The implantation of the Yoshida AH-130 ascites hepatoma (a fast growing tumour) to rats resulted in a dramatic loss of both white adipose tissue and muscle (skeletal and cardiac) mass. Administration of beta2-adrenergic agonists to tumour-bearing rats resulted in a partial recovery of skeletal muscle and heart mass. Treatment of the tumour-bearing animals with the different drugs (salbutamol, salmeterol and clenbuterol) did not influence tumour growth or food intake so it can be suggested that the effects were solely due to metabolic changes. In addition, while the three drugs had clear effects on gastrocnemius muscles, clenbuterol and salbutamol had also an effect on soleus, and salbutamol had a clear effect on cardiac muscle. It is suggested that any of the studied beta2-adrenergic agonists (but perhaps, particularly salmeterol) could be used clinically in the treatment of cancer cachexia.

Adipose Tissue↗
PubMed1997

Reversibility of parathyroid gland suppression in CAPD patients with low i-PTH levels.

The i-PTH response to changes in the peritoneal calcium balance was studied prospectively in a group of 13 stable CAPD patients, who presumably had adynamic bone disease, with low or normal i-PTH values and low aluminum in plasma. Five days after the reduction of dialysate calcium concentration from 1.75 mmol/l to 1 mmol/l, there was a significant elevation in the serum i-PTH. These increased PTH levels returned to baseline values when patients were changed to the 1.75 mmol/l Ca solution (p = 0.004). The changes in i-PTH mirrored the changes in peritoneal calcium balances. These results support the notion that the low or normal levels of i-PTH frequently seen in peritoneal dialysis patients are due to the hypercalcemic effects of the standard peritoneal dialysis solutions; in these patients, the parathyroid hormone production is normal since negative peritoneal balances of calcium are associated with an increase in serum i-PTH.

Adult↗