PubMed Health⌕ Search

Biomedical subjects

A Aguirre

Publications and source records attributed to A Aguirre.

At least 19 recordsLinked to original sources
PubMed1992

Heat-labile enterotoxin crystal forms with variable A/B5 orientation. Analysis of conformational flexibility.

A new native crystal form of heat-labile enterotoxin (LT) has two AB5 complexes in the asymmetric unit with different orientations of the A subunit with respect to the B pentamer. Comparison with other crystal forms of LT shows that there is considerable conformational freedom for orientating the A subunit with respect to the B pentamer. The rotations of A in different crystal forms do not follow one specific axis, but most of them share a hinge point, close to the main interaction area between A and B5. Analysis of the two high-resolution structures available shows that these rotations cause very little change in the actual interactions between A and B5.

Bacterial Toxins↗
PubMed1992

Levels of salivary cystatins in periodontally healthy and diseased older adults.

Cystatins are cysteine protease inhibitors present in a variety of tissues and body fluids, including saliva. One possible function of these molecules may be to modulate tissue destruction in periodontal diseases. To investigate the potential role of salivary cystatins in these events, the levels of cystatins in saliva from periodontally healthy and diseased individuals were measured by enzyme-linked immunosorbent assay. Flow rates and total protein content were determined in all the samples collected, while cysteine protease inhibitory activity was assessed in submandibular-sublingual secretions. Statistical analysis showed no significant differences in the levels and activity of salivary cystatins in periodontally healthy and diseased individuals. These findings suggest that comparing the levels of cystatins in glandular salivas may not be a suitable indicator of periodontal disease status.

Aged↗
PubMed1992

Effects of chronic ethanol consumption on the rat parotid gland.

Two-month-old Wistar rats ingested 10% ethanol for 12 months. Their parotid glands were then compared with those of normal controls by light microscopy. They had extensive ductal and acinar oncocytic transformation; numerous atypical acinar cells showed anisocytosis, polyploidism and hyperchromatism, features that were absent in controls. Oncocytosis and atypical acinar cells have been reported in 2-3-yr-old ('senile') Wistar rats. Thus, chronic alcohol ingestion may produce cellular features resembling those observed in the parotid gland of 'senile' Wistar rats.

Alcoholism↗
PubMed1992

Inotropic influence of macrocyclic polyethers on tracheal smooth muscle.

Incubated guinea pig tracheal smooth muscle exhibited both positive and negative inotropic responses to a variety of crown ether analogs that ranged in size from 12-crown-4 to 30-crown-10 and included molecules whose lipophilicity was modified by the addition of benzo- and cyclohexo-substituents on the basic molecular framework. The inotropic influence of crown ethers may not only be due to their ionophoretic capabilities but may result from their ability to affect alterations in membrane physiology.

Animals↗
PubMed1992

Phase delay of pulmonary acoustic transmission from trachea to chest wall.

The frequency-dependent propagation time, or phase delay tau (f), of sonic noise transmission from the trachea to the chest wall was estimated over the 100-600 Hz frequency range using a phase estimation technique from measurements performed on eight healthy subjects. Since tau (f) can be greater than one period of the input signal at frequencies greater than 100 Hz, the unambiguous phase estimate at 100 Hz was used as a starting-point to determine the phase angle H(f) and tau (f) at higher frequencies under the constraint that the spectra did not exhibit large point-to-point discontinuities. The resulting tau (f) range of 0.9-4.1 ms is consistent with sound propagation to the chest wall through both airways and surrounding parenchyma. The frequency and spatial dependence of tau (f) indicates that with increasing frequency more sonic energy travels further into the branching airway structure before coupling into the parenchyma. These results suggest that information concerning distinct regional lung structures may be obtained by probing the system acoustically over selected frequency bands.

Acoustics↗
PubMed1992

A monoclonal antibody for distinction of invasive and noninvasive clinical isolates of Entamoeba histolytica.

Approximately 10% of the world population is infected with Entamoeba histolytica, but only 10% of the carriers develop symptomatic amebiasis. This discrepancy could be explained by the genotypic differences between the morphologically indistinguishable invasive and noninvasive strains of E. histolytica currently identified by zymodeme analysis, a technique that is unsuitable for routine diagnostic laboratories. Here we report the production of a monoclonal antibody against E. histolytica and its use in an immunofluorescence assay to identify invasive isolates cultured from stool samples of infected patients in several regions where amebiasis is endemic: Bangladesh, Colombia, and Mexico. After testing a total of 88 E. histolytica isolates, the correlation between zymodeme characterization and the immunofluorescence assay with the invasive isolate-specific monoclonal antibody was 100%. The epitope detected by the invasive isolate-specific monoclonal antibody resides in a previously undescribed internal protein with molecular masses of 84 and 81 kDa in axenic and polyxenic E. histolytica strains, respectively.

Animals↗
PubMed1992

Effects of a two-hour early awakening and of bright light exposure on plasma patterns of cortisol, melatonin, prolactin and testosterone in man.

Bright light is a synchronizing agent that entrains human circadian rhythms and modifies various endocrine and neuroendocrine functions. The aim of the present study was to determine whether and how the exposure to a bright light stimulus during the 2 h following a 2 h earlier awakening could modify the disturbance induced by the the sleep deprivation on the plasma patterns of hormones whose secretion is sensitive to light and/or sleep, namely melatonin, prolactin, cortisol and testosterone. Six healthy and synchronized (lights on: 07.00-23.00) male students (22.5 +/- 1.1 years) with normal psychological profiles volunteered for the study in winter. The protocol consisted of a baseline control night (customary sleep schedule) followed by three shortened nights with a rising at 05.00 and a 2 h exposure to either dim light (50 lux; one week) or bright light (2000 lux; other week). Our study showed a phase advance of the circadian rhythm of plasma cortisol without significant modifications of the hormone mean or peak concentration. Plasma melatonin concentration decreased following bright light exposure, whereas no obvious modifications of plasma testosterone or prolactin patterns could be observed in this protocol.

Adult↗
PubMed1992

Multiple focal pigmented lesions in the maxillary tuberosity and hard palate: a unique display of intraoral junctional nevi.

The pigmented conditions located in the oral cavity have a diverse genesis ranging from vascular lesions to exogenous and endogenous pigmentations. In this report we have documented the unusual occurrence of multiple intraoral junctional nevi in a patient. A review of the patient's past dental records revealed that 2 of these lesions were first noticed 8 years earlier; however, no efforts were made to identify the nature of the pigmentations. Removal of 4 lesions and subsequent histopathological analysis revealed the presence of junctional nevi. This case illustrates the importance of a thorough clinical and histological work-up when dealing with pigmented lesions in the oral cavity. The excision of all suspected oral nevi is warranted because they cannot be clinically differentiated from other pigmented lesions, including oral melanoma. In addition, the potential of junctional nevi to undergo malignant transformation in the oral cavity is undetermined.

Aged↗
PubMed1992

Further diagnostic use of an invasive-specific monoclonal antibody against Entamoeba histolytica.

Genotypic differences between invasive and non-invasive E. histolytica could explain the 1:10 ratio of symptomatic/asymptomatic infection worldwide. Currently, zymodeme analysis is used to differentiate invasive from non-invasive E. histolytica strains but the technique is cumbersome and expensive. In accordance with the WHO research priorities for amebiasis we report here the further use of an invasive-specific monoclonal antibody against E. histolytica in immunofluorescence, to identify isolates cultured from stool samples of patients from three geographically distant endemic regions: Bangladesh, Colombia and Mexico. We tested 107 E. histolytica isolates and the correlation between zymodeme characterization and the immunofluorescence assay was 100%.

Animals↗
PubMed1992

The MEDLINE Button.

We have developed a computerized method for performing bibliographic searches directly from patient data involving five steps: 1) identifying specific patient data which raises a question in the mind of the user, 2) selection (from a list of generic questions) of a small number of questions which fit the selected patient data, 3) automated translation of the patient data into appropriate terms used for bibliographic indexing, 4) conversion of the question selected by the user into a search strategy, and 5) transfer of the search strategy to a search engine for a bibliographic database. We have modified the Columbia-Presbyterian Clinical Information System to experiment with this method. The first implementation converts patient diagnoses and procedures coded in ICD9-CM into Medical Subject Headings (MeSH) and searches Medline using BRS/Onsite. Challenges include development of a useful set of generic questions and translation from ICD9-CM to MeSH using the Unified Medical Language System (UMLS).

Diagnosis, Computer-Assisted↗
PubMed1991

Human salivary cystatin S. Cloning, sequence analysis, hybridization in situ and immunocytochemistry.

A human submandibular-gland (SMG) cDNA library was constructed in a lambda was constructed in a lambda gt11 Sfi-Not orientation-specific expression vector and then screened with antibody generated against human salivary cystatins. The clone C4-4 encoded an N-terminally truncated cystatin S, whereas the others encoded cystatin SN. The library was then rescreened with the C4-4, and the inserts of several positive clones were directly amplified from the eluted plaques by linear PCR and the PCR products analysed by Southern blotting and direct DNA sequencing. Two clones (C3 and C12) encoded a full-length secreted cystatin S and its leader peptide and included 5'- and 3'-untranslated regions. These clones showed a high degree of sequence similarity to cDNA clones encoding human salivary cystatin SN and genomic clones encoding cystatin SN and SA. Hybridization in situ of normal human SMG and parotid-gland (PG) tissue sections localized the cystatin-gene transcripts to the cytoplasm of serous acinar cells of both glands, with a much higher concentration of cystatin mRNA in the SMG. Immunocytochemistry localized the salivary cystatin gene products also to the serous cells, and the levels of cystatin protein correlated with the amount of cystatin mRNA, with a much stronger signal in the SMG than in the PG.

Aged↗