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Biomedical subjects

A Guerrero

Publications and source records attributed to A Guerrero.

At least 199 records · Page 11Linked to original sources
PubMed1989

Egg jelly triggers a calcium influx which inactivates and is inhibited by calmodulin antagonists in the sea urchin sperm.

Sea urchin sperm must undergo the acrosome reaction to fertilize eggs. The natural inducer of this reaction is the most external coat of the egg, named 'jelly'. The ionic composition of the extracellular and intracellular media and the permeability properties of the sperm plasma membrane are fundamental in this reaction. As Ca2+ is required for the acrosome reaction to occur, its intracellular concentration ([Ca2+]i) was measured with fura-2. In 10 mM Ca2+, egg jelly induced the acrosome reaction and an increase in [Ca2+]i that lasted for several minutes. However, at 0.5 or 2 mM Ca2+, it became evident that the Ca2+-influx pathway activated by jelly opened only for a few seconds; this prevented both the full increase in [Ca2+]i and the acrosome reaction even after the concentration of Ca2+ was raised to 10 mM. In the presence of jelly, the time this permeability pathway remained open was inversely related to the extracellular concentration of Ca2+ ([ Ca2+]e). Using Bisoxonol (a permeant fluorescent membrane potential probe), it was found that the jelly-induced depolarization depended on [Ca2+]e and was proportional to the increase in [Ca2+]i. Since [Ca2+]i could affect the jelly-induced Ca2+ influx through calmodulin, two of its antagonists, trifluoperazine and W-7, were tested. Both compounds blocked the acrosome reaction by inhibiting the jelly-induced increase in [Ca2+]i. W-5 at the same concentration had no effect. The results suggest that one of the jelly-activated Ca2+-influx pathways, probably a channel, is the target of the calmodulin antagonists.

Acrosome↗
PubMed1989

Contact phase of blood coagulation in cardiogenic pulmonary oedema (CPO) and adult respiratory distress syndrome (ARDS).

In order to assess the role of the kallikreinkinin (k-k) system in the pathogenesis of pulmonary oedema, we studied the contact phase factors of blood coagulation, as well as the haemodynamics and blood gas changes in 34 patients with pulmonary oedema, 23 of them with Adult Respiratory Distress Syndrome (ARDS) and 11 with cardiogenic pulmonary oedema (CPO). We have verified significant differences in the haemodynamic pattern and blood gases between the two groups of patients, which corroborate the previously established differences between both types of pulmonary oedema. Our results reveal k-k system activation in ARDS patients, with a significant fall in factor XII (p less than 0.05), prekallikrein (p less than 0.01), alpha-2-macroglobulin (p less than 0.01) and high molecular - weight kininogens (p less than 0.005), with a rise in C1-esterase inhibitor (p less than 0.001) in comparison with patients with CPO. All of the CPO patients had normal prekallikrein levels, whereas 15 out 23 ARDS cases (65%) had decreased prekallikrein values. Our results suggest that the k-k system activation could play a role in the pathogenesis of ARDS. Estimation of prekallikrein levels may be helpful in the differential diagnosis of ARDS.

Adult↗
PubMed1989

Current findings in the pathological evaluation of breast reduction specimens.

A study of the histopathologic findings in the specimens of 100 consecutive cases of reduction mammoplasty was performed. The current classification of premalignant breast changes using the presence or absence of atypia in specimens with epithelial hyperplasia was employed. Of the group studied only 1% showed atypical ductal hyperplasia and no cases of lobular carcinoma in situ or ductal carcinoma in situ were found. Fifty percent of the specimens showed simply fibrosis of the stroma dominating the gross and microscopic picture. The other pathological findings in descending order of frequency were cysts (30%) epithelial hyperplasia without atypia (6%), adenosis (5%) and apocrine metaplasia (5%).

Adolescent↗
PubMed1988

Cerebral mucormycosis in two cases of acquired immunodeficiency syndrome.

We describe two patients with isolated cerebral mucormycosis and acquired immunodeficiency syndrome (AIDS). Their clinical course was rapid and fatal; early diagnosis and treatment with amphotericin B did not prevent a fatal outcome in both cases. Isolated cerebral mucormycosis has not (to our knowledge) been reported previously in patients with AIDS. Mucormycosis should be included in the differential diagnosis of central nervous system infections in intravenous drug abusers with AIDS. A brain biopsy is needed for the diagnosis of mucormycosis.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Single-channel activity in sea urchin sperm revealed by the patch-clamp technique.

Ionic fluxes are deeply involved in the response of spermatozoa to the egg. Using the patch-clamp technique, we show for the first time single ion channel activity in sea urchin spermatozoa and spermatozoa heads. Due to their small size gigaseals were obtained in suspended cells by applying suction through the pipette. The rate of gigaseal formation was very low and improved to 6% (n = 1145) when flagella were detached from sperm. Current-voltage curves created from single-channel events showed conductances of approx. 65 and 170 pS, suggesting the presence of two types of channels. At least one appears to be a K+ channel.

Acrosome↗
PubMed1986

Behaviour of the contact phase of blood coagulation in the adult respiratory distress syndrome (ARDS).

In order to assess the role of the kallikrein-kinin (K-K) system in the pathogenesis of the adult respiratory distress syndrome (ARDS) we have prospectively determined coagulation contact phase, blood gas and hemodynamic parameters in patients with ARDS at 0, 36 and 72 h from diagnosis. Compared to normal values, significantly lower mean levels of factor XII (71.4 +/- 9.8%, p less than 0.0005), prekallikrein (PPK) (52 +/- 5.7%, p less than 0.0005), high molecular weight kininogen (HMWK) (73 +/- 2%, p less than 0.0005) and alpha 2-macroglobulin (alpha 2-M) (51 +/- 7.1%, p less than 0.0005) were found in ARDS patients. The functional kallikrein inhibitory activity (KKI) and C1-esterase inhibitor antigenic (CIINH) were significantly higher in these patients (113.2 +/- 5, p less than 0.005 and 124.7 +/- 7.6, p less than 0.0005 respectively) compared with normal values during the entire study period. The KKI/CIINH ratio decreased significantly in our ARDS patients at 0, 36 and 72 h (p less than 0.025; p less than 0.05 and p less than 0.005 respectively). We found a significant correlation between PPK levels and oxygenation index (r = 0.69, p less than 0.001), PPK and the static thoracic compliance values (r = 0.64, p less than 0.001). There was also a significant correlation between PPK levels and Qs/Qt (r = -0.89, p less than 0.001). ARDS patients that survived presented a stability in the PPK values in successive tests. Nevertheless non-survivors showed a progressive decrease in PPK levels during the follow-up period.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Mannose incorporation and lectin recognition of pronase-sensitive components in Micrococcus lysodeikticus (M. luteus) membranes.

Isolated cytoplasmic membranes from Micrococcus lysodeikticus were able to incorporate [14C]mannose from GDP-[14C]mannose. Labelled mannose remained in the membrane fraction after its repeated washing and lipid extraction. Sodium dodecyl sulfate gel electrophoresis in 12% acrylamide showed a set of bands with molecular weights ranging from 230 000 to 19 000 which stained for protein and carbohydrate, and incorporated [14C]mannose. Some of these bands reacted with different lectins (concanavalin A, wheat germ agglutinin and ricin). Furthermore, the mannose was incorporated via a glycosylation pathway similar to that followed in eukaryotic system as shown by the preliminary identification of a lipid intermediate transferring the sugar to proteins and by the differential sensitivity to bacitracin and tunicamycin. These complex membrane components were sensitive to digestion with pronase. All the results presented suggest their glycoprotein nature.

Bacitracin↗
PubMed1986

Epilepsy and brain tumors in infancy and adolescence.

Four boys and four girls with brain tumors who were admitted to our department in the last 8 years are herein described. They presented with epileptic fits, which began before the age of 14 years, with neither intracranial hypertension nor localizing signs during the first 6 months of the illness. The length of time between the first fit and the diagnosis of a tumor ranged from 2 months to 11 years (median of 3 years), during which period all patients but one received anticonvulsant therapy. The nontreated patient was under psychiatric treatment for 1 year. The electroencephalographic evolution was disconcerting, showing asymmetry of the recording with association of slow polymorphic waves and acute irregular waves, suggesting encephalitis. The neuroradiological diagnosis was made by cerebral arteriography in one patient and in the others by angiography and CT scans (which revealed hypodense cerebral areas in five cases and hyperdense areas in the other two). The histology of the tumor was that of a grade I astrocytoma in six cases; a grade III oligondendroglioma in one case, and a meningioma in the other. All patients underwent surgical treatment. Four also received radiation therapy, two for a partially excised astrocytoma and one each for an oligodendroglioma and a meningioma. Postoperatively, all patients were put on anticonvulsant drug therapy. There were no mortalities. To date, only one astrocytoma has recurred. The sequellae observed were hemiparesis in one case and marked psychomotor deficit in another. These two patients also still have epileptic fits. The others are all psychologically and neurologically normal, and two are now off antiepileptic drugs.

Adolescent↗