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Biomedical subjects

C Calderón

Publications and source records attributed to C Calderón.

At least 19 recordsLinked to original sources
PubMed2006

Effect of different fermentation conditions on the kinetic parameters and production of volatile compounds during the elaboration of a prickly pear distilled beverage.

An experimental design considering thermal treatment of must, yeast strain, prickly pear variety and degree of ripeness was chosen to evaluate the fermentation behavior and generation of volatile compounds, during the elaboration of a distilled beverage from prickly pear. Four Mexican prickly pear varieties were characterized physically and two of them were selected for fermentation studies. The thermal treatment of the must showed the highest statistical influence on fermentation behavior and production of volatile compounds, followed by prickly pear variety, then yeast strain and finally the degree of ripeness was the least statistically significant factor. The growth rate increased when the thermal treatment was applied whereas the ethanol production rate and alcoholic efficiency were unaffected. The results also suggested that thermal treatment was effective for inhibition of microbial contamination. As regards volatile compounds production, acetic acid and methanol decreased while other volatiles increased when the thermal treatment was applied. Despite the influence of thermal treatment, prickly pear variety strongly influences the volatile profile of fermented musts.

Acetaldehyde↗
PubMed2001

[Qualitative approach to the attitudes and expectations of doctors during the process of computerising primary care].

OBJECTIVE: To find the attitudes and expectations of doctors during the process of computerising primary care (PC). DESIGN: Qualitative investigation through discussion groups. PARTICIPANTS: Thirty-one doctors from the two PC regions of Gipuzkoa. METHOD: Intentional stratified sampling by regions and by experience in using a computer in the consulting-room. Five discussion groups with recording and transcription of the contents with prior authorisation and guarantee of confidentiality. Qualitative analysis of the notes and transcriptions with the help of computer back-up. Validation through sending of results to participants and discussion between the authors. RESULTS: Introducing computers into PC consulting-rooms had repercussions both on the ordering and contents of the information recorded. The effort < > was not accompanied by subsequent evaluation. Notable deficiencies in management of the computerising process were perceived. Computer use created additional symbolic effects for both patients and doctors. CONCLUSIONS: Computerising PC is a process whose repercussions on medical care are far from neutral and so require rigorous discussion and evaluation. Defining step-by-step and measurable objectives, transparency in management and the promotion of evaluative research would all favour the effective development of projects to computerise PC.

Adult↗
PubMed2001

[Estimating the supply of medical specialists in Colombia by using the capture-recapture method].

OBJECTIVE: Given that it is not known how many medical doctors there are in Colombia and that, without that datum, studies of demand are simply theoretical exercises, we proposed to estimate the supply of 12 medical specialties in Colombia, using the capture-recapture technique, which was developed by zoologists to estimate wild-animal populations. METHODS: Three lists, or "captures," were used: 1) university degrees obtained abroad and graduates of postgraduate programs in Colombia, 2) members of medical societies, and 3) specialists in the principal health care enterprises. To estimate the total population we used the CAPTURE software program. RESULTS: A total of 24,910 records were obtained: 8,397 from the university records, 6,561 from the scientific societies, and 9,952 from the health care businesses. More than half of the physicians have entered the labor market during the last decade. The estimated number of physicians (with the 95% confidence interval) for each specialty was: anesthesiology, 1,753 (1,727 to 1,789); cardiology, 607 (598 to 624); dermatology, 517 (514 to 525); obstetrics and gynecology, 2,338 (2,290 to 2,400); pulmonary disease, 304 (297 to 320); neurosurgery, 324 (319 to 334); neurology, 321 (296 to 369); ophthalmology, 1,049 (1,042 to 1,061); orthopedics, 1,217 (1,212 to 1,227); otolaryngology, 634 (628 to 645); psychiatry, 855 (838 to 879); and urology, 452 (452 to 458). CONCLUSIONS: The capture-recapture technique is useful in the study of human resources. In Colombia the number of specialists doubled in less than a decade. There are specialties that are already oversupplied, such as neurosurgery. All the other specialties show growth rates that indicate a future over-supply for the health care system.

Colombia↗
PubMed2000

[Guidelines of the Spanish Society of Cardiology for clinical practice in exercise testing].

Most exercise testing is performed in adults with known or suspected ischemic heart disease. In the last few years cardiac imaging techniques have been applied in this field, improving the information obtained with the procedure. However, the exceptions to this rule are emerging rapidly not only in healthy people (asymptomatic individuals, athletes, handicapped people) but also in cardiac patients (advanced congestive heart failure, hypertension, rhythm disorders, congenital heart disease, etc.). All the-se issues justify the need for a multidisciplinary consensus document in Spain. This paper reviews and updates the methodological aspects of the stress test, including those related to oxygen consumption measurements. The main aim of this review was to determine the role of exercise testing in the evaluation of ischemic heart disease as well as the applications of imaging stress testing. The usefulness of this test in other non-ischemic cardiac disorders and in selected subsets of healthy people is also reviewed.

Adult↗
PubMed2000

[Carcinoma hepatocellular. Description of verified clinical characteristics in a region of Southern Chile].

BACKGROUND: Hepatocellular carcinoma is the most frequent primary tumor of the liver. It is associated to chronic liver diseases and has a high prevalence in some regions of Africa and Asia. AIM: To describe the clinical characteristics of patients with hepatocellular carcinoma, admitted to two hospitals of the IX region of southern Chile. MATERIAL AND METHODS: Prospective study of 29 consecutive patients admitted to two hospitals in Temuco, Chile. Clinical features, laboratory values and viral markers were analyzed. RESULTS: Eighteen patients were male and ages ranged from 29 to 75 years old. The most frequent presenting symptom was abdominal pain in 21 patients. Seven subjects had a history of alcoholism. Serum bilirubin values ranged from 0.1 to 15.8 mg/dl, alkaline phosphatases ranged from 171 to 3476 U/l, ASAT from 24 to 5400 U/l and alpha feto protein from 1.4 to 350 ng/ml. Two patients had a positive hepatitis B surface antigen and all had negative hepatitis C virus antibodies. Mean tumoral diameter was 9.6 cm and the most common presentation was nodular. Mean survival after the diagnosis was 6.3 months. CONCLUSIONS: These patients with hepatocellular carcinoma have a low frequency of positive viral markers and tumors of large sizes on presentation.

Adult↗
PubMed2000

[Meloxican-induced cholestasis].

The cholestasis by meloxicam has not been often described. However, we present here the clinic, laboratory, histologic and follow up of a patient with cholestatic hepatitis produced by this drug.

Aged↗
PubMed1999

Respiratory disturbances during sleep in syringomyelia and syringobulbia.

OBJECTIVE: To determine the frequency and types of abnormalities of respiratory control during sleep in syringomyelia and syringobulbia and to provide a basis to predict patients at risk of sudden death. METHODS: Thirty patients (15 male and 15 female; mean age 39.0 +/- 12.6 years) with communicating syringomyelia were divided into two groups: those with evidence of syringobulbia (17 patients) and those without compromise of the medulla or syringomyelia (13 patients). Patients were studied with pulmonary function studies and polysomnography. Respiratory center sensitivity to CO2 (rebreathing technique) was measured in 9 patients. RESULTS: Severely affected patients had mild-to-moderate restriction and individual patients had bilateral diaphragmatic or vocal cord palsy, abnormal respiratory rhythm, prolonged inspiratory time, or an abnormal respiratory response to CO2. Very prolonged central, obstructive, and mixed sleep apneas with low O2 saturation values and a fixed heart rate were recorded in most patients with syringobulbia. Five patients developed severe respiratory complications and died during a follow-up period of 10 years. Respiratory abnormalities failed to correlate with syrinx size. CONCLUSIONS: Severe abnormalities in respiratory rhythm generation during sleep occur in patients with syringobulbia. The respiratory disturbances are not due to muscle weakness and they are not correlated with the size of the cavity. The combination of dysphagia and dysphonia in patients with longstanding syringomyelia and syringobulbia predicted likelihood of respiratory disturbances during sleep.

Adolescent↗
PubMed1999

Neurological impairment in alpha-mannosidosis: a longitudinal clinical and MRI study of a brother and sister.

Neurological development over a period of 25 years and MRI findings are reported in two members of the same family affected by mannosidosis type II. Progressive axial and appendicular cerebellar syndrome, moderate hearing loss and deterioration of gait were present in both patients. Neuropsychological deficiency was severe, but progression over the years was not observed except in the woman's speech capacity. Neither of the patients showed clinical improvement. A progressive corticosubcortical atrophy stands out in the brain neuroimaging studies, especially at the vermian cerebellar level. The osseous cranial deformities are very characteristic and include brachycephaly, thickening of the calvaria at the expense of the diploe, and poor pneumatization of the sphenoid. Neither of our cases showed an empty sella turcica.

Adult↗
PubMed1999

[Application of advanced oxidant systems in the treatment of residual waters in the petroleum industry (Fenton system)].

Typical contaminants from the oil industry were treated with the Fenton system (H2O2/Fe2+) under normal conditions of pressure and temperature. The treated contaminants, in harzadous concentrations, were the following: m-cresol, 2-chlorophenol, and methyl-tertbutyl -ether (MTBE). Additionally, waters contaminated with reformulated gasoline were also treated and the degradation of MTBE and volatile aromatics (benzene, toluene, ethylbenzene and xylene) was followed. The system efficiency, in the contaminated water treatment of two different samples were also tested. One of the samples came from oil production operations and the other from a petrochemical plants complex. In all cases an advanced mineralization of the contaminants was observed in relatively short periods of time. The rate constants, at room temperature, for degradation of m-cresol, 2-chlorophenol and MTBE were measured.

Ferrous Compounds↗
PubMed1998

[Homeopathic and primary care doctors: how they see each other and how they see their patients: results of a qualitative investigation].

OBJECTIVE: To explore the views of Primary Care and homeopathic doctors in the same geographical and population catchment area towards Homeopathy as a discipline and the motives that bring patients to use its services. DESIGN: A qualitative study, using in-depth interviews and a focus group. SETTING: A community of 18,000 inhabitants with a Health Centre and four homeopathic physicians. PARTICIPANTS: The four homeopathic physicians and nine of the ten doctors from the Health Centre. METHOD: After face-to-face and later telephone interviews, each of the four homeopathic physicians was interviewed in depth and the author led a focus group with the 9 Health Centre doctors. MAIN RESULTS: a) From the homeopaths: they emphasised an integrated patient-centred approach. They insisted on their status as doctors and that their treatment was not iatrogenic, etc. b) From PC doctors: They were ignorant of Homeopathy. They identified it with a type of remedy of which they knew nothing, but for which they demanded scientific evidence, etc. CONCLUSIONS: PC doctors' ignorance of Homeopathy put them at risk of not understanding patients' expectations. It seems that the patient-centred, as against disease-centred, care model is, in practice, outside the scope of PC health delivery.

Catchment Area, Health↗
PubMed1998

Analysis of the relationships between environmental factors (aeroallergens, air pollution, and weather) and asthma emergency admissions to a hospital in Mexico City.

There have been several studies of the relationships between environmental factors, particularly air pollution, and attacks of asthma. Most of these studies have ignored the potential confounding effects of aeroallergens such as pollens and fungal spores. We report a statistical analysis of the relationships between emergency admissions for asthma to a hospital in Mexico City and daily average airborne concentrations of pollen, fungal spores, air pollutants (O3, NO2, SO2, and particulates) and weather factors. Asthma admissions had a seasonal pattern with more during the wet season (May-October) than the dry season (November-April). There were few statistical associations between asthma admissions and air pollutants for the three age groups studied (children under 15 years, adults, and seniors [adults over 59 years]) in either season. Grass pollen was associated with child and adult admissions for both the wet and dry seasons, and fungal spores were associated with child admissions during both the wet and dry seasons. The analysis was done with environmental data averaged over the day of admission and the 2 previous days. Our results suggest that aeroallergens may be statistically associated more strongly with asthma hospital admissions than air pollutants and may act as confounding factors in epidemiologic studies.

Adolescent↗
PubMed1998

Soft salt-mannitol agar-cloxacillin test: a highly specific bedside screening test for detection of colonization with methicillin-resistant Staphylococcus aureus.

The early detection of colonization with methicillin-resistant Staphylococcus aureus (MRSA) of patients in intensive-care units is an essential step in the strategy for preventing MRSA epidemics. In this study, tubes containing soft salt-mannitol agar with cloxacillin (6 microg/ml) (SSMAC) were prepared for inoculation of clinical samples at patients' bedsides by personnel of an intensive-care unit. A total of 1,914 swabs from different sample sites of 81 patients were dipped into SSMAC tubes, and after 24 h of incubation (in an incubator located near the intensive-care unit), an evident color change was considered by the intensive-care-unit personnel to be an MRSA alarm. Sixty-three (3.3%) SSMAC tubes were considered positive for MRSA, 1,827 (95.4%) were considered negative, and 24 (1.2%) were considered intermediate. Compared with values for parallel conventional surveillance cultures for MRSA, excluding tubes with intermediate results, the SSMAC test had a sensitivity of 72.7%, a specificity of 99.2%, a positive predictive value of 76.2%, and a negative predictive value of 99.0%. When intermediate tubes were considered positive, the corresponding values were 75.3, 98.2, 63.2, and 99.0%, respectively. The sensitivity and specificity values of the test to identify MRSA-colonized patients were 89.4 and 100%, respectively. Oropharyngeal and naris specimens were the most reliable samples for MRSA detection. False-negative results were frequent in bronchial aspirates with low (< 10(3) to 10(6) CFU/ml) MRSA counts. False-positive results were mainly due to methicillin-resistant Staphylococcus haemolyticus. The SSMAC tube is a useful, rapid, and inexpensive tool for the early identification of MRSA-colonized patients and, consequently, for the implementation of measures to prevent the spread of MRSA.

Adult↗
PubMed1997

[in vitro activity of carbapenems against Enterobacteriaceae and Pseudomonas aeruginosa hyperproducers of group 1 chromosomal beta-lactamases].

Resistance to imipenem and meropenem, reported sporadically in Enterobacteriaceae and more frequently in Pseudomonas aeruginosa, can be caused, among other mechanisms, by the combination of changes in permeability and hyperproduction of inducible chromosomal beta-lactamases. In this study, the in vitro activity of imipenem and meropenem was analysed by the agar dilution method against cefotaxime, ceftazidime, and aztreonam resistant clinical strains of Enterobacteriaceae (n = 202) and P. aeruginosa (n = 90). This phenotype is consistent with the hyperproduction of group 1 chromosomal beta-lactamases and was previously determined in stably derepressed mutants in the same species, obtained from strains with inducible beta-lactamase expression by selection with cefotaxime and ceftazidime. Likewise, the activity of imipenem and meropenem against the same number of clinical isolates susceptible to cefotaxime, ceftazidime, and aztreonam was evaluated. In general, imipenem and meropenem showed an excellent activity, which was intrinsically greater for meropenem against Enterobacteriaceae and P. aeruginosa organisms. Nevertheless, imipenem and meropenem activity was slightly affected on cefotaxime, ceftazidime, and aztreonam resistant isolates of E. cloacae (MIC90, 1 and 0.2 microgram/ml, respectively), E. aerogenes (1 and 0.2 microgram/ml), C. freundii (1 and 0.1 microgram/ml), M. morganii (1 and 0.5 microgram/ml), and S. marcescens (4 and 0.5 micrograms/ml). On the other hand, the activity of imipenem and meropenem against ceftazidime and aztreonam resistant isolates of P. aeruginosa was more significantly affected, with MIC90 values of 64 and 16 micrograms/ml, respectively.

Enterobacteriaceae↗
PubMed1997

Usefulness of phage typing and "two-way ribotyping" to differentiate Salmonella enteritidis strains.

The capacity to differentiate Salmonella enteritidis strains by phage typing and "two-way ribotyping" performed with PstI and SphI was evaluated. The typeability was 96.8% in phage typing and 100% in ribotyping. The series was differentiated into 13 phage types, 19 combined ribotypes, and 39 subtypes or clonal lines by combining results from both methods (of which 11, 13, and 35, respectively, were represented by natural strains). Ribotyping differentiated strains ascribed to PTs 1, 4, 6a, 7, 8, RDNC and UPT. Conversely, some strains of PTs 1, 4, 5a, 6, 6a, 7, 34, RDNC and UPT fall into the most frequent combined ribotype. A dendrogram of genetic similarity generated from the combined ribotypes was traced, and, at a 0.82 similarity level, it showed a major cluster (including 17 combined ribotypes, 88.4% strains ascribed to all PTs tested except PT11), a minor cluster, and four additional lines more loosely related.

Bacterial Typing Techniques↗
PubMed1996

[Specialized care of neurological diseases in Colombia].

This study sought to reveal the patterns of medical care given to patients with neurologic diseases in Colombia. To that end, it tracked the daily activities of 30 neurologists chosen from a representative sample of 119 neurologists registered in Colombia in 1993. The information was requested by means of a previously standardized questionnaire and was complemented by demographic and epidemiologic data. The results showed that demand for specialized neurologic care depended more on cultural perceptions than on objective measures of prevalence. Moreover, it was found that education in neurology should place greater emphasis on ambulatory treatment as an alternative to hospital treatment. The survey also offered preliminary information on the prevalence and incidence of the primary neurologic diseases in the country. The prevalence of these diseases far exceeds the supply of specialized neurologic care. Finally, the results point out the advantages and deficiencies of this type of care, findings that might guide future efforts in this field in other countries and under different circumstances.

Adult↗
PubMed1995

Decreased macrophage-mediated cytotoxicity in mammary-tumor-bearing mice is related to alteration of nitric-oxide production and/or release.

Peritoneal-exudate macrophages (PEM) from mammary-tumor-bearing mice have impaired cytotoxic activity against syngeneic and allogeneic tumor targets. The ability of PEM from normal and tumor-bearing mice to bind tumor targets was found to be similar in the presence or the absence of surrogate receptors, which enhanced the binding but not the killing of tumor targets by PEM from tumor-bearing mice, suggesting that other mechanisms are involved in their impaired cytolytic activity. Soluble and membrane-bound TNF-alpha, as well as H2O2, were found in higher amounts in PEM from tumor bearers upon stimulation with LPS, as compared with PEM from normal mice. However, tumor-bearers' macrophages displayed decreased capacity to produce and/or release nitric oxide, which could be reversed by the addition of increasing levels of IFN-gamma. These results indicate that the lack of macrophage cytotoxicity in mammary-tumor-bearing mice is related to impaired production and/or release of NO by these effector cells, possibly aggravated by the insufficient IFN-gamma production previously reported in these animals. Moreover, mammary-tumor progression results in dis-regulation of synthesis of macrophage-mediators, with over-production of molecules to which mammary-tumor cells are insensitive and deficient production of NO, the crucial molecule to which these cells appear to be highly sensitive.

Animals↗
PubMed1995

Resistance of veillonella to hydrosoluble pristinamycins: a possible outer membrane barrier effect.

An in vitro study on 25 Veillonella strains showed a consistent clindamycin susceptibility with resistance to erythromycin and to the hydrosoluble pristinamycins, quinupristin and dalfopristin and its 30:70 combination, the synergistin RP59500. Double erythromycin-clindamycin disk tests did not show any inducible resistance pattern. The addition of 10 or 50 mug/mL of polymyxin B nonapeptide, an outer membrane permeabilizing agent, consistently reduced quinupristin and dalfopristin MICs in most strains. This result suggests that the Veillonella outer membrane may act as a permeability barrier to these antibiotics, as in the case of other Gram-negative bacteria.

Journal Article↗