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Biomedical subjects

M A Moreno

Publications and source records attributed to M A Moreno.

At least 19 recordsLinked to original sources
PubMed2005

Theoretical calculations of refractive indices and optical effects in spectra of nitric acid and nitric acid monohydrate crystals.

The theoretical infrared refractive indices of two systems related to atmospheric research, nitric acid (NA) and nitric acid monohydrate (NAM) crystals, have been computed using a methodology based on first-principles. The effects of lack of coherence in the infrared beam in RAIR and transmission spectra have also been treated using a model based on classical optics. The optical constants of NA crystals are presented for the first time; the results on NAM are compared to empirical values previously published with good general agreement. With the optical constants of NA, polarized reflection-absorption infrared spectra are predicted and compared to experimental spectra recorded also for the first time, for a set of varying film thickness. The global agreement is satisfactory. The effects of a number of experimental factors in transmission spectra of NAM are assessed, in an attempt to explain observed differences among experimental spectra. It is concluded that the spectral disparities are probably due to differences in the nature of the samples.

Journal Article↗
PubMed2005

Effects of age and physical activity on the autonomic control of heart rate in healthy men.

The effects of the aging process and an active life-style on the autonomic control of heart rate (HR) were investigated in nine young sedentary (YS, 23 +/- 2.4 years), 16 young active (YA, 22 +/- 2.1 years), 8 older sedentary (OS, 63 +/- 2.4 years) and 8 older active (OA, 61 +/- 1.1 years) healthy men. Electrocardiogram was continuously recorded for 15 min at rest and for 4 min in the deep breathing test, with a breath rate of 5 to 6 cycles/min in the supine position. Resting HR and RR intervals were analyzed by time (RMSSD index) and frequency domain methods. The power spectral components are reported in normalized units (nu) at low (LF) and high (HF) frequency, and as the LF/HF ratio. The deep breathing test was analyzed by the respiratory sinus arrhythmia indices: expiration/inspiration ratio (E/I) and inspiration-expiration difference (deltaIE). The active groups had lower HR and higher RMSSD index than the sedentary groups (life-style condition: sedentary vs active, P < 0.05). The older groups showed lower HFnu, higher LFnu and higher LF/HF ratio than the young groups (aging effect: young vs older, P < 0.05). The OS group had a lower E/I ratio (1.16) and deltaIE (9.7 bpm) than the other groups studied (YS: 1.38, 22.4 bpm; YA: 1.40, 21.3 bpm; OA: 1.38, 18.5 bpm). The interaction between aging and life-style effects had a P < 0.05. These results suggest that aging reduces HR variability. However, regular physical activity positively affects vagal activity on the heart and consequently attenuates the effects of aging in the autonomic control of HR.

Adult↗
PubMed2005

Non-heart-beating donors: an excellent choice to increase the donor pool.

A specific program was adopted to obtain organs, for transplant purposes from people who die at home or in the street from sudden or unexpected death (type I non-heart-beating donors [NHBD] according to the Maastricht classification). The objective of our program was to increase the donor pool by obtaining organs from well-selected potential donors who die at home, work, or in the street and are maintained on advanced life support (ALS) until hospital arrival. The great number of people who die in a previously healthy situation constitute an excellent source of organs for transplant purposes. Our program includes pre- and in-hospital attendance. Prehospital attendance is based on application of cardiopulmonary resuscitation in situ and ALS until arrival at hospital. In hospital, specific preservation maneuvers must be performed and family assessment and judge permission obtained. In the last 15 years, we developed a kidney transplant program with better results than transplants performed with organs obtained from encephalic death donors (EDD). A specific NHBD subprogram for lung transplant was developed with excellent results as well. We are now improving the liver transplant program. NHBD are an important source of human tissues, including pancreas islets. It is clear that NHBD are a great source of organs and tissues for transplant, and that this kind of program must be established in all countries in which legal regulations allow it.

Cadaver↗
PubMed2004

C4d DNA sequence of complement C4B93 and recombination mechanisms for its generation.

The present work reports the DNA sequence of the polymorphic region from the uncommon complement allele C4B93. It shows a new combination of Chido and Rodgers antigenicities and expresses reverse antigenicity because it carries Rodgers 1, 2, and 3. C4B93 could have arisen from an ancient, non-homologous recombination between C4A3 (or C4A6) and C4B1a or from a homologous recombination between C4B1a and C4B5. These events would be enhanced by the presence of recombination promoting Escherichia colichi-like signals in the fragment between positions 1157 and 1186. The generation of the C4 polymorphism by recombination would explain the concerted evolution of C4 genes in primates.

Alleles↗
PubMed2003

Psychrobacter pulmonis sp. nov., isolated from the lungs of lambs.

Unusual Gram-negative, catalase- and oxidase-positive, coccus-shaped bacteria isolated from the lungs of two lambs were characterized by phenotypic and molecular-genetic methods. Comparative 16S rRNA gene sequencing studies demonstrated that the unknown isolates were genealogically highly related to each other (99.8% sequence similarity) and represent a novel subline within the genus Psychrobacter. The unknown bacterium was phylogenetically closely related to, but distinct from, Psychrobacter phenylpyruvicus, Psychrobacter immobilis, Psychrobacter glacincola and Psychrobacter urativorans. The novel Psychrobacter isolates were readily distinguished from all other Psychrobacter species and other Gram-negative, oxidase-positive bacteria usually responsible for lung infections in sheep by physiological and biochemical tests. Based on molecular-genetic and phenotypic evidence, it is proposed that the unknown Psychrobacter isolates from lambs be classified as Psychrobacter pulmonis sp. nov. The type strain is strain S-606T (=CECT 5989T =CCUG 46240T).

Animals↗
PubMed2001

Extracellular production of biologically active deacetoxycephalosporin C synthase from Streptomyces clavuligerus in Pichia pastoris.

We have successfully expressed and observed secretion of the Streptomyces clavuligerus deacetoxycephalosporin C synthase (DAOCS) using the Pichia pastoris expression system. Two clones having multiple copies of the expression cassette were selected and used for protein-expression analysis. SDS-PAGE showed efficient expression and secretion of the bacterial recombinant DAOCS. The highest yield (120 microg/mL) was obtained when expression was induced with 2% methanol. Free and immobilized protein were assayed for biological activity and found to expand penicillin N (its natural substrate) and penicillin G to deacetoxycephalosporin C (DAOC) and deacetoxycephalosporin G (DAOG), respectively.

Cephalosporins↗
PubMed2001

Recognition of carbohydrate epitopes specific for electron-dense granule antigens from Entamoeba histolytica by monoclonal antibodies in the cecal content of infected hamsters.

The pathogenic trophozoites of Entamoeba histolytica produce and secrete electron-dense granules (EDG) containing collagenase, considered a virulence factor. Two monoclonal antibodies (MAbs) (L7.1 and L1.1) anti-EDG antigens were raised. MAb L7.1 has been reported to recognize proteic EDG antigens and MAb L1.1 reacted with a carbohydrate epitope. These epitopes were present in axenic and xenic amoebas. To detect EDG antigens by a enzyme-linked immunosorbent assay (ELISA) in a experimental model of early intestinal amoebiasis, both MAbs were employed. E. histolytica HM1 axenic and monoxenic trophozoites were inoculated into the cecum according to the washed-closed cecal loop technique. The cecal content was recovered at 8, 24, and 48 h post-inoculation. Antigens from EDG in whole trophozoites and cell-free supernatants were detected. Our results indicate that it is possible to detect EDG antigens in the cecal content of hamsters in the early phase of the invasive amoebiasis.

Animals↗
PubMed2001

Autosomal STR genetic variation in negroid Chocó and Bogotá populations.

Genetic data for eight autosomal STRs were obtained from two different population samples from Colombia: the European Mestizo population of Bogotá and the African descent population of the Chocó region. The STRs were analysed in a multiplex system that includes the STR markers CSF1PO, TPOX, TH01, VWA, D13S317, D7S820, D16S539 and D5S818. Separation of the fragments and fluorescent detection was carried out in an ABI 310 DNA sequencer and the typing was made by comparison with sequenced allelic ladders. Exact tests were used for testing linkage between the loci and for Hardy-Weinberg equilibrium. Significant differences were found between both populations for all the loci.

Alleles↗
PubMed2001

First-derivative spectrophotometric and LC determination of nifedipine in Brij 96 based oil/water/oil multiple microemulsions on stability studies.

A first-derivative spectrophotometric (1D(387)) method was developed for the determination of nifedipine in oil/water/oil (O/W/O) multiple microemulsions during stability studies. The UV first-derivative spectra were recorded over the wavelength range 200-600 nm (Delta lambda=16). The derivative procedure was based on the linear relationship between nifedipine concentration and the first-derivative amplitude at 387 nm. This method was validated and compared with a liquid chromatography (LC) procedure used for the quantitative analysis of the drug. Both methods showed excellent precision and accuracy with values of 2.09 and 1.82%, respectively, for the LC method and of 1.53 and 1.64%, respectively, for the 1D(387) method. The established linearity range was 5-30 microg ml(-1) with r(2) values of 0.9980 and 0.9988 for LC and first-derivative procedures, respectively. Nifedipine recoveries from spiked placebos were >95% for both methods over the linear range analysed. These methods have been successfully used for determining of nifedipine content of multiple microemulsions during stability studies, since there was no interference with its decomposition products.

Calcium Channel Blockers↗
PubMed2001

Antimicrobial susceptibility of Listeria monocytogenes isolated from meningoencephalitis in sheep.

The antimicrobial susceptibility to different antimicrobial agents of 41 Listeria monocytogenes strains isolated from sheep with meningoencephalitis and from feedstuff was tested by both microdilution and disk diffusion methods. Both sets of isolates of L. monocytogenes were susceptible to penicillin G, amoxicillin, cephalothin, erythromycin, vancomycin, rifampicin, gentamicin, kanamycin, trimethoprim, sulfisoxazole, chloramphenicol and ciprofloxacin, but resistant to tetracycline and doxycycline (7.3 and 4.9%, respectively). Tetracycline was the most frequent resistance trait in L. monocytogenes strains of animal origin. Four strains (9.8%) also exhibited reduced susceptibility (MIC 4 mg/l) to doxycycline suggesting the need of surveillance studies to monitor the antimicrobial resistance of Listeria strains of animal origin.

Amoxicillin↗
PubMed2001

Antimicrobial susceptibility of corynebacteria isolated from ewe's mastitis.

The antimicrobial susceptibility of 50 coryneform isolates from subclinical mastitis in sheep was evaluated. Arcanobacterium pyogenes (five isolates) had a susceptibility pattern distinct from the Corynebacterium species tested. The Corynebacterium isolates could be divided in two groups according to the MIC values for ciprofloxacin. Their antimicrobial susceptibility was usually unpredictable and consequently antimicrobial susceptibility tests are necessary for clinical and epidemiological purposes.

Animals↗
PubMed2001

Biotransformations catalyzed by multimeric enzymes: stabilization of tetrameric ampicillin acylase permits the optimization of ampicillin synthesis under dissociation conditions.

The importance of the stabilization of the quaternary structure of multimeric enzymes has been illustrated using a model reaction with great industrial relevance: the enzymatic synthesis of ampicillin from 6-amino penicillanic acid (6APA) and phenylglycine methyl ester (PGM) catalyzed by the tetrameric enzyme alpha-amino acid ester hydrolase from Acetobacter turbidans. The stabilization of the multimeric structure of the enzyme was achieved by multi-subunit immobilization of the enzyme followed by its further solid-phase chemical intersubunit cross-linking with polyfunctional macromolecules (dextran-aldehyde). This stabilized derivative has permitted the study of the reaction under conditions where nonstabilized enzyme molecules tended to dissociate (e.g., absence of phosphate ions). Synthetic yields improved from around 65%, under conditions where the nonstabilized derivative was stable, to around 85% in conditions where only the stabilized derivative could be utilized (40% methanol and absence of phosphate ions). When using high concentrations of PGM, a significant worsening of the reaction performance was detected with a significant decrease in the yields (below 55%, using 50 mM 6APA and PGM). This problem has been sorted out by using a fed-batch reaction system. By addition of PGM continuously to the reaction mixture (to maintain the concentration between 0.5 and 3 mM), 95% of 6-APA could be transformed to antibiotic (47.5 mM) by only using a 20% excess of acylating ester.

Acetobacter↗
PubMed2001

Lyophilized lecithin based oil-water microemulsions as a new and low toxic delivery system for amphotericin B.

PURPOSE: To develop and investigate lecithin based oil-water microemulsions as potential amphotericin B (AmB) delivery systems and to evaluate their in vivo acute toxicity. METHODS: AmB was added to the microemulsion and its location was evaluated by partitioning studies and UV-visible spectrophotometric analysis of the drug. Both, non-lyophilized and reconstituted microemulsions were characterised and assessed for their stability. Single-dose acute toxicity of the AmB microemulsion was studied on male albino Webster-derived CD-1 mice and compared with Fungizone. RESULTS: The studies performed showed that AmB was intercalated on the oil-water interface of the microemulsion as a complex formed with lecithin molecules. AmB addition did not seem to modify the rheological properties of the original system, but had an effect on its particle size distribution. Lyophilization of the microemulsion led to an oily cake, easily reconstituted and stable at the conditions studied. Single-dose acute toxicity studies proved that the LD50 of AmB microemulsions was of 4 mg kg(-1) of animal weight, compared with 1 mg kg(-1) found for Fungizone. CONCLUSIONS: Lyophilized lecithin based oil-water microemulsions appear to be valuable systems for the delivery of AmB in terms of easy and low-cost manufacturing, stability and safety compared with the formulations already in market.

Amphotericin B↗
PubMed2001

Ectopic ACTH syndrome caused by pulmonary carcinoid tumourlets.

The differential diagnosis of Cushing's syndrome is a major challenge to clinical endocrinologists, especially those infrequent cases referred to as occult ectopic ACTH syndromes. Although bronchial carcinoids are well known to be a cause of Cushing's syndrome due to ectopic ACTH secretion, very few cases of carcinoid tumourlets causing an ACTH ectopic syndrome have been reported, and their origin remains controversial. For some authors, tumourlets and typical carcinoids represent distinct pathological entities, whilst others hold that tumourlets are merely microscopic carcinoid tumours. We report a patient with an aggressive Cushing's syndrome that required bilateral adrenalectomy, diagnosed 22 years before a 3-cm lung nodule became apparent on routine chest X-ray. The biopsy after lung surgery revealed a typical peripheral bronchial carcinoid surrounded by tumourlets. Both tumourlets and carcinoid tumour showed strongly positive ACTH immunostaining. Recently, Arioglu et al. (1998) reported a case of Cushing's syndrome caused by pulmonary carcinoid tumourlets, concluding that this entity should be considered in the differential diagnosis of occult ectopic ACTH syndrome. Furthermore, we consider that the carcinoid tumourlets found in our patient, were the initial source of ACTH, leading to Cushing's syndrome with a rapid onset, and that a loss of cell proliferation control in one of such tumourlets many years later, could have resulted in the development of a typical carcinoid tumour, reinforcing the theory of a common origin of these lesions.

ACTH Syndrome, Ectopic↗
PubMed2001

Two different pathways are involved in the beta-oxidation of n-alkanoic and n-phenylalkanoic acids in Pseudomonas putida U: genetic studies and biotechnological applications.

In Pseudomonas putida U, the degradation of n-alkanoic and n-phenylalkanoic acids is carried out by two sets of beta-oxidation enzymes (betaI and betaII). Whereas the first one (called betaI) is constitutive and catalyses the degradation of n-alkanoic and n-phenylalkanoic acids very efficiently, the other one (betaII), which is only expressed when some of the genes encoding betaI enzymes are mutated, catabolizes n-phenylalkanoates (n > 4) much more slowly. Genetic studies revealed that disruption or deletion of some of the betaI genes handicaps the growth of P. putida U in media containing n-alkanoic or n-phenylalkanoic acids with an acyl moiety longer than C4. However, all these mutants regained their ability to grow in media containing n-alkanoates as a result of the induction of betaII, but they were still unable to catabolize n-phenylalkanoates completely, as the betaI-FadBA enzymes are essential for the beta-oxidation of certain n-phenylalkanoyl-CoA derivatives when they reach a critical size. Owing to the existence of the betaII system, mutants lacking betaIfadB/A are able to synthesize new poly 3-OH-n-alkanoates (PHAs) and poly 3-OH-n-phenylalkanoates (PHPhAs) efficiently. However, they are unable to degrade these polymers, becoming bioplastic overproducer mutants. The genetic and biochemical importance of these results is reported and discussed.

Acids, Acyclic↗
PubMed2001

Cementless femoral revision arthroplasty of the hip: minimum 5 years followup.

Durable fixation of the femoral component to the bone in femoral revision arthroplasty of the hip is the main ingredient to a successful reconstruction. Because of poor durability of cemented fixation in revision, in 1984, one author began to use cementless fixation with extensively porous-coated chrome cobalt stems. The current authors report the durability of that fixation technique in 137 hips (134 patients) followed up 5 to 16 years. With a mean followup of 9.3 years, 10 (7%) of the stems have been removed. Five (4%) were removed for fixation problems and five (4%) were removed for infection. Using the radiographic criteria of Engh et al, 83% of the stems achieved bony ingrowth. No late failure of fixation was observed. Canal-filling prostheses were more likely to have bone ingrowth as were stems placed in femurs with lesser degrees of bone stock deficiency. Significant thigh pain was seen in 7% of bone ingrown stems, 16% of stable fibrous fixated stems, and 75% of unstable stems. Significant thigh pain in bone ingrown stems was observed more commonly in osteoporotic femurs and bone stock deficient femurs. Severe stress shielding correlated with preoperative osteoporosis and larger diameter stems but has not caused failure. Excellent durability of this fixation technique is evident.

Arthroplasty, Replacement, Hip↗