Biomedical subjects

A Alonso

Publications and source records attributed to A Alonso.

At least 325 records · Page 18Linked to original sources

PubMed1993

Characterization of foot-and-mouth disease virus by monoclonal antibodies.

Monoclonal antibodies (MAbs) were produced against foot-and-mouth disease (FMD) virus types O1 Campos Br1/58, A24 Cruzeiro Br1/55, and C3 Indaial Br1/71, which are the strains used for production of FMD vaccines in the majority of South American countries. Within the library of MAbs produced, a group was selected on the basis of their neutralizing titer in cell culture, protective titer in suckling mice, sensitivity to trypsin, and specificity for virus structural proteins. The MAbs were utilized in an ELISA test format to compare European and South American representative field isolates with vaccine production strains in their r1 relationship as obtained by 50% complement fixation (CF50) with polyclonal antibodies (PAb) and their virus neutralization (VN) relationship obtained with sera from one-time-vaccinated and from revaccinated cattle, respectively. The MAbs selected varied in their reactivity against the different strains and, therefore, enabled us to compare field FMDV strains to those against which the MAbs were produced, with definite advantages over the r1 and VN ratios. Thus, panels of MAb produced with the vaccine strains and appropriately selected are significantly useful for the FMD-control programs because they serve to provide guidance on the immunological coverage provided by the vaccines against FMDV strains circulating in the field. The MAbs are also useful for the differentiation of FMD virus strains.

Animals↗

PubMed1993

Specific expression in adult mice and post-implantation embryos of a transgene carrying the histone H1(0) regulatory region.

Histone H1(0), a variant of the H1 group, has been found associated with the repressed state of chromatin and its content is increased in terminally differentiated cells. We have cloned a mouse H1(0) histone gene and introduced the promoter region, ligated to the beta-galactosidase reporter gene, into transgenic mice. By histochemistry we demonstrated a strong expression of the transgene in adult kidney, testis and brain. Intestine, uterus and ovarium were also positive. This expression followed the same pattern as that of the endogenous H1(0) gene, as demonstrated by in situ hybridization with a non-coding fragment of the mRNA, by Northern analysis, and by immunofluorescence with specific antibodies. In post-implantation embryos, the expression was very low up to day ten p.c. At this time, most of the X-Gal staining was found in the brain, retina and some of the large blood vessels. Hence, expression of the transgene as well as of the endogenous H1(0) gene is not exclusively linked to a differentiated phenotype or to a reduced cell proliferation capacity.

Animals↗

PubMed1993

Differential electroresponsiveness of stellate and pyramidal-like cells of medial entorhinal cortex layer II.

1. The electroresponsive properties of neurons from layer II of the rat medial entorhinal cortex (MEC) were studied by intracellular recording under current clamp in an in vitro brain slice preparation. From a total of 184 cells that fulfilled our criteria for recording stability, two groups of projection neurons were distinguished on the basis of their intrinsic biophysical properties and morphological characteristics (demonstrated by intracellular biocytin injection; n = 34). 2. Stellate cells (SCs) were the most abundant (69%). They were highly electroresponsive, and minimal changes (1-3 mV) of membrane potential generated an active response. Subthreshold depolarizing or hyperpolarizing current pulse injection always caused the membrane potential to attain an early peak and then sag to a lower level. Depolarization-induced "sags" were larger and determined early firing in all cells. The voltage-current relationship of SCs was markedly non-linear, demonstrating robust inward rectification in the hyperpolarizing and depolarizing range. 3. SCs generated persistent rhythmic subthreshold voltage oscillations on DC depolarization positive to -60 mV. The mean frequency of the oscillations was 8.6 Hz (theta range) at a membrane potential of approximately -55 mV, at which level occasional single spiking also occurred. At slightly more positive potentials, a striking 1- to 3-Hz repetitive bursting pattern emerged. This consisted of nonadapting trains of spikes ("clusters") interspersed with subthreshold oscillations that had a mean frequency of 21.7 Hz (beta range). 4. Nonstellate cells (39%; mostly pyramidal-like) displayed time-dependent inward rectification that was less pronounced than that of SCs, and minimal depolarization-induced sags. On threshold depolarization, firing was always preceded by a slowly rising ramp depolarization and thus occurred with a long delay. Inward rectification in the depolarizing range was very pronounced. However, non-SCs did not generate persistent rhythmic subthreshold oscillatory activity or spike clusters. 5. Of the electrophysiological parameters quantified, spike threshold, spike duration, depolarizing afterpotential amplitude and apparent membrane time constant demonstrated statistically significant differences between SCs and non-SCs. 6. The repetitive hiring properties in response to square current pulses of short duration (< 500 ms) were also different between SCs and non-SCs. First, most SCs displayed a bilinear frequency-current (f-I) relationship for only the first interspike interval, whereas most non-SCs displayed a bilinear relationship for all intervals. Second, SCs had a much steeper primary f-I slope for early intervals than non-SCs. Finally, SCs displayed more pronounced and faster spike frequency adaptation than non-SCs.(ABSTRACT TRUNCATED AT 400 WORDS)

Afferent Pathways↗

PubMed1993

Ionic mechanisms for the subthreshold oscillations and differential electroresponsiveness of medial entorhinal cortex layer II neurons.

1. Layer II of the medial entorhinal cortex is composed of two electrophysiologically and morphologically distinct types of projection neurons: stellate cells (SCs), which are distinguished by rhythmic subthreshold oscillatory activity, and non-SCs. The ionic mechanisms underlying their differential electroresponsiveness, particularly in the subthreshold range of membrane potentials, were investigated in an "in vitro" slice preparation. 2. In both SCs and non-SCs, the apparent membrane input resistance was markedly voltage dependent, respectively decreasing or increasing at hyperpolarized or subthreshold depolarized potential levels. Thus the neurons displayed inward rectification in the hyperpolarizing and depolarizing range. 3. In the depolarizing range, inward rectification was blocked by tetrodotoxin (TTX, 1 microM) in both types of neurons and thus shown to depend on the presence of a persistent low-threshold Na+ conductance (gNap). However, in the presence of TTX, pronounced outward rectification became manifest in the subthreshold depolarizing range of membrane potentials (positive to -60 mV) in the SCs but not in the non-SCs. 4. The rhythmic subthreshold membrane potential oscillations that were present only in the SCs were abolished by TTX and not by Ca2+ conductance block with Cd2+ or Co2+. Subthreshold oscillations thus rely on the activation of voltage-gated Na+, and not Ca2+, conductances. The Ca2+ conductance block also had no effect on the subthreshold outward rectification. 5. Prominent time-dependent inward rectification in the hyperpolarizing range in the SCs persisted after Na(+)- and Ca2+ conductance block. This rectification was not affected by Ba2+ (1 mM), but was blocked by Cs+ (1-4 mM). Therefore, it is most probably generated by a hyperpolarization-activated cationic current (Q-like current). However, the Q-like current appears to play no major role in the generation of subthreshold rhythmic membrane potential oscillations, because these persisted in the presence of Cs+. 6. On the other hand, in the SCs, the fast, sustained, outward rectification that strongly developed (after Na+ conductance block) at the oscillatory voltage level was not affected by Cs+ but was blocked by Ba2+ (1 mM). Barium was also effective in blocking the subthreshold membrane potential oscillations. 7. In the non-SCs, which do not generate subthreshold rhythmic membrane potential oscillations or manifest subthreshold outward rectification in TTX, Ca2+ conductance block abolished spike repolarization and caused the development of long-lasting Na(+)-dependent plateau potentials at a high suprathreshold voltage level. At this level, where prominent delayed rectification is present, the Na+ plateaus sustained rhythmic membrane potential oscillations.(ABSTRACT TRUNCATED AT 400 WORDS)

Afferent Pathways↗

PubMed1993

Erythrocyte anion exchanger activity and intracellular pH in essential hypertension.

The present study was designed to examine the activity of the sodium-independent chloride-bicarbonate anion exchanger and the sodium-proton exchanger in erythrocytes of 30 normotensive and 35 hypertensive subjects and its relation to the previously reported decrease in erythrocyte pH. Erythrocyte cytosolic pH was measured by the pH-sensitive fluorescent probe 2'-7'-bis(2-carboxyethyl)- 5(6)-carboxyfluorescein. The activity of the anion exchanger was determined by acidifying cell pH and measuring the initial rate of the net sodium-independent, 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid-sensitive, bicarbonate influx driven by an outward proton gradient. The activity of the sodium-proton exchanger was determined by acidifying cell pH and measuring the initial rate of the net sodium-dependent proton efflux driven by an outward proton gradient. The activity of the anion exchanger was higher in hypertensive than control individuals (18,863 +/- 1081 vs 15,629 +/- 897 mmol/L cells per hour, P < .05). The activity of the sodium-proton exchanger was higher in hypertensive than control individuals (301 +/- 45 vs 162 +/- 23 mmol/L cells per hour, P < .005). Basal erythrocyte pH was lower in hypertensive than control individuals (7.27 +/- 0.02 vs 7.33 +/- 0.01, mean +/- SEM, P < .05). With the 100% confidence (lower) limit of the normotensive population as a cutoff point, a subgroup of 11 hypertensive patients had an abnormally low erythrocyte pH (< 7.19).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1993

The ill therapist: therapists' reactions to personal illness and its impact on psychotherapy.

This paper examines the potential countertransference problems therapists face when they become ill. Personal illness creates conscious and unconscious dilemmas for therapists, and the psychotherapy relationship may be strongly affected by the ways in which the dilemmas are managed. Psychotherapy is a relationship based on trust. A therapist's illness does not necessarily damage the trust that has been developed; however, the handling of the illness and interruption can create a major rupture in the relationship. Alternatively, the therapist's illness can create a useful opportunity for therapeutic work. Successful management of countertransference is a crucial ingredient for the latter outcome. Relatively little has been written until recently on countertransference aspects of therapist illness. Available literature has noted such defenses as denial, omnipotent fantasies, and reaction formation against dependency and weakness. Illness has been seen as a problem for "older" therapists, but, in fact, illness can occur at any age. Illness may cause a defensive withdrawal from one's patients and in its most serious instance lead to total empathic failure. Clinical concerns for the ill therapist fall into two categories: how much (if any) information to give patients about the illness and how to work therapeutically with patients' reactions. While there are no clear guidelines, we recommend a flexible, common sense approach with the central focus always on the patient's reactions to information or to changes in the therapy. The foundation for decisions about information and for subsequent processing of reactions must be the therapist's own awareness of countertransference. We recommend consultation with trusted colleagues or supervisors. In addition, we emphasize the ethical responsibility every therapist has to provide for patients in the event of an emergency ahead of time. Finally, we surveyed a small number of experienced therapists who were known to have had personal experience with illness. The results indicated that decisions about giving information were not difficult. However, the countertransference reactions of anxiety, denial, sadness, and avoidance (of patient anger) were often troublesome. We recommend that psychotherapy training include management of therapist illness. We also recommend that supervisors be familiar with the countertransference aspects as they may be called on suddenly to give consultation. Our conclusion is that therapist illness is as big an event for the therapist as it is for the patient, and we hope that a body of literature will be developed on this important topic.

Adaptation, Psychological↗

PubMed1993

[The pediatric kidney transplant in recipients under 2 years old].

We report our experience with renal transplantation in 7 infants less than 2 years of age. The mean duration of follow-up was 32.4 m. except one who died in the immediate postoperative period. Immunosuppressive therapy consisted of methyl prednisolone, azathioprine, cyclosporin. No patient showed either vascular or lymphatic complications however the infections were frequent. All except one, have their graft functioning well. Graft and patient survival rates were 85% at 36 m. We conclude that renal transplantation in this age group is technically feasible although it needs a team with wide experience in the management of pediatric renal transplantation.

Combined Modality Therapy↗

PubMed1993

[Changes in the flow of the stable renal graft following cyclosporin administration].

To evaluate whether oral CyA may produce changes in the renal vascular bed of the graft, a prospective study was made in 16 children with kidney transplant and normal renal function. A exam with echo-Doppler was realized pre and post two hour after CyA was administered. The doses of CyA was 6.1 +/- 2.7 mg/kg/days (3 doses). The results show that CyA produced in the children with kidney transplant an increase of vascular resistance (renal and interlobar) and a decrease transient of urinary flow. The finding changes in relation to time of administration of the CyA.

Adolescent↗

PubMed1993

[Nutritional status of vitamin D in mothers and neonates of Ushuaia and Buenos Aires].

Serum levels of calcium, phosphorus, total alkaline phosphatase (AP) and 25 hydroxyvitamin D (250HD) were measured at the end of the winter in Group 1 (Ushuaia, latitude 55 degrees S): 16 women (24-48 hs postpartum serum blood) and 20 neonates (cord blood) and in Group 2 (Buenos Aires, latitude 34 degrees S) 21 women (24-48 hs postpartum serum blood) and their 21 neonates (cord blood). The neonatal serum calcium and phosphorus were higher and the neonatal serum AP and 250HD level were lower than maternal levels in both groups (Table 1 and 2). Serum levels of 250HD were diminished (< 8 ng/ml) in 62% of the mothers and 81% of the neonates of Ushuaia and in 24% of the mothers and 16% of the neonates of Buenos Aires (figure 1). Neonatal serum 250HD levels correlate with maternal serum 250HD levels in the paired group of Buenos Aires (r = 0.65, p < 0.003) (Figure 2). In Ushuaia the serum 250HD levels (X +/- SD) in neonates (3.9 +/- 2.7 ng/ml) and in mothers (6.3 +/- 4.8 ng/ml) were lower than in Buenos Aires (neonates: 11.3 +/- 6.0 ng/ml and mothers: 14.4 +/- 8.4 ng/ml, p < 0.001). Maternal serum calcium levels were lower in Ushuaia (8.7 +/- 0.8 mg/dl) than in Buenos Aires (9.2 +/- 0.4 mg/dl) (p < 0.05). In conclusion, 1) In Ushuaia pregnant women and their neonates had a deficient nutritional state of vitamin D. Preventive administration of vitamin D would probably be beneficial.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1993

Molecular pathology of Alzheimer neurofibrillary degeneration.

The most characteristic brain lesion of Alzheimer disease is the accumulation of paired helical filaments (PHF) in the affected neurons. Based on solubility in detergents there are two general populations of PHF, the readily soluble (PHF I) and the sparingly soluble (PHF II) types. The major polypeptides of PHF are the microtubule associated protein tau. Tau in PHF is present in abnormally phosphorylated forms. In addition to the PHF, the abnormal tau is also present in unpolymerized form in the AD brain. Small amounts of ubiquitin (%) are associated with PHF II but neither with PHF I nor with the unpolymerized abnormally phosphorylated tau in AD brain. Furthermore, the pretangle neurons can readily be immunolabeled for abnormally phosphorylated tau but not for ubiquitin. The level of tau in neocortex is several-fold higher than in AD aged control cases, but this increase is in the form of the abnormally phosphorylated protein. The microtubule associated proteins from AD brain do not promote the assembly of microtubules in vitro, whereas the in vitro dephosphorylated PHF polypeptides stimulate the binding of GTP to the exchangeable site of tubulin and the assembly of microtubules. In vitro the phosphate groups in PHF are less accessible than those of tau to alkaline phosphatase. It is suggested that a defect in the protein phosphorylation/dephosphorylation system leads to hyperphosphory-lation of tau. The altered tau contributes to a microtubule assembly defect and consequently compromises the axoplasmic flow and leads to neuronal degeneration.

Alzheimer Disease↗

PubMed1993

Respiratory chain enzyme activities in lymphocytes from untreated patients with Parkinson disease.

Respiratory chain enzyme activities were studied in lymphocytes from patients with Parkinson disease (PD) (n = 16) and age-matched control subjects (n = 15). The patients had received no therapy before the study was conducted. Complex I, III, and IV activities were significantly lower (P < 0.05) in patients than in control subjects. A complex I defect was found in one patient, whereas complex IV was defective in another. Two patients had combined defects of both complexes. The use of lymphocytes for investigating the respiratory chain enzymes provides an easy, noninvasive method to assess mitochondrial function in patients with PD. Furthermore, our study supports the hypothesis that a biochemical defect in the respiratory chain may be involved in the pathogenesis of PD.

Adult↗

PubMed1993

[Renal leiomyosarcoma].

Presentation of one case of a large, rapidly growing and highly aggressive renal leiomyosarcoma. The diagnostic and therapeutical possibilities of this infrequent tumour are analyzed.

Aged↗

PubMed1992

Multiple cis-acting elements of the proximal promoter region are required for basal level transcription of the H1(0) histone gene.

Basal level transcription of the mouse histone H1(0) gene is mediated by 531 base pairs of the promoter region. Deletion of the most distal upstream 80 bp of this fragment reduces transcription to very low values. By in vitro footprinting we demonstrate now that multiple factors bind to the DNA fragment localized between the 80 bp and the cap nucleotide. In addition to the presence of motifs for the binding of SP1, H1-box, H4TF-2 and TATA-box-factors, other not yet described protein-binding elements were identified. Internal deletions in the wild type promoter enclosing these motifs strongly restrict transcription. Furthermore, when one of these motifs was modified by site-directed mutagenesis a strong impairment of transcription followed. Thus for basal level transcription, in addition to the 80 bp distal fragment, cis-acting elements localized in the 450 bp proximal promoter region are required.

Animals↗

PubMed1992

Afferent projections to the mammillary complex of the rat, with special reference to those from surrounding hypothalamic regions.

To better understand the functional organization of the mammillary nuclei, we investigated the afferents to this nuclear complex in the rat with iontophoretically injected wheat germ agglutinin conjugated to horseradish peroxidase. Particular attention was paid to tracing local hypothalamic afferents to these nuclei. Injections into the medial mammillary nucleus (MMN) revealed strong projections from the subicular region, and weaker projections from the prefrontal cortex, medial septum, and the nucleus of the diagonal band of Broca. Other descending subcortical projections to the MMN arise from the anterior and the lateral hypothalamic area, the medial preoptic area, and the bed nucleus of the stria terminalis. Ascending afferents to the MMN were found to originate in the raphe and various tegmental nuclei. Following all injections into the MMN, labelled neurons were found in nuclei surrounding the mammillary body. The lateral and posterior subdivisions of the tuberomammillary nucleus projected mainly to the pars medianus and pars medialis of the MMN. The dorsal and ventral premammillary nuclei projected to the pars lateralis of the MMN. The supramammillary nucleus at rostral level had a small projection to the pars medialis and lateralis of the MMN. However, the most obvious projection from this nucleus was to the pars posterior of the MMN, chiefly from the lateral part of the caudal supramammillary nucleus. Injections into the lateral mammillary nucleus revealed inputs from the presubiculum, parasubiculum, septal region, dorsal tegmental nucleus, dorsal raphe nucleus, and periaqueductal gray. In addition, the lateral mammillary nucleus was found to receive a moderate projection from the medial part of the supramammillary nucleus and stronger projections from the lateral part of the caudal supramammillary nucleus. A very light projection was also seen from the lateral and posterior subdivisions of the tuberomammillary nucleus. These findings add to our knowledge of the extensive and complex connectivity of the mammillary nuclei. In particular, the local connections we have demonstrated with the supramammillary and tuberomammillary nuclei indicate the existence of significant local circuits as well as circuits involving more distant brain regions such as the septal nuclei, subiculum, prefrontal cortex, and brain stem tegmentum.

Afferent Pathways↗

PubMed1992

A dopaminergic projection to the rat mammillary nuclei demonstrated by retrograde transport of wheat germ agglutinin-horseradish peroxidase and tyrosine hydroxylase immunohistochemistry.

The presence and distribution of dopaminergic neurons and terminals in the hypothalamus of the rat were studied by tyrosine hydroxylase (TH) immunohistochemistry. Strongly labelled TH-immunoreactive neurons were seen in the dorsomedial hypothalamic nucleus, periventricular region, zona incerta, arcuate nucleus, and supramammillary nucleus. A few TH-positive neurons were also identified in the dorsal and ventral premammillary nucleus, as well as the lateral hypothalamic area. TH-immunoreactive fibres and terminals were unevenly distributed in the mammillary nuclei; small, weakly labelled terminals were scattered in the medial mammillary nucleus, while large, strongly labelled, varicose terminals were densely concentrated in the internal part of the lateral mammillary nucleus. A few dorsoventrally oriented TH-positive axon bundles were also identified in the lateral mammillary nucleus. A dopaminergic projection to the mammillary nuclei from the supramammillary nucleus and lateral hypothalamic area was identified by double labelling with retrograde transport of wheat germ agglutinin-horseradish peroxidase and TH-immunohistochemistry. The lateral mammillary nucleus receives a weak dopaminergic projection from the medial, and stronger projections from the lateral, caudal supramammillary nucleus. The double-labelled neurons in the lateral supramammillary nucleus appear to encapsulate the caudal end of the mammillary nuclei. The medial mammillary nucleus receives a very light dopaminergic projection from the caudal lateral hypothalamic area. These results suggest that the supramammillary nucleus is the principal source of the dopaminergic input to the mammillary nuclei, establishing a local TH-pathway in the mammillary complex. The supramammillary cell groups are able to modulate the limbic system through its dopaminergic input to the mammillary nuclei as well as through its extensive dopaminergic projection to the lateral septal nucleus.

Animals↗

PubMed1992

The physical state of ubiquinone-10, in pure form and incorporated into phospholipid bilayers. A Fourier-transform infrared spectroscopic study.

Long-chain quinones are essential components of both bacterial and eukaryotic respiratory chains, and some of the main unsolved questions on energy transduction in membranes are complicated by the lack of consistent information on the physical state of the quinones in membrane bilayers. We have recorded, at various temperatures and under different conditions, the infrared spectra of ubiquinone-10 (the main species in mitochondria) and several analogues. The C = O stretching vibration band located at 1663-1670 cm-1 has been identified as the most sensitive one to phase and environmental changes. Three distinct phases have been characterized in which pure ubiquinone-10 may exist: crystalline (LC1), isotropic liquid (IL) and liquid crystalline (Lc). The only allowed thermotropic transitions are LC1----IL, IL----Lc and Lc----LC1. Our investigations with pure quinones provide a simpler and more detailed description of their phase changes than any of the previous studies and shed light on their behaviour in membranes. When incorporated into phospholipid bilayers, ubiquinone-10 appears to be removed from the aqueous environment and is found to exist, in the 4-70 degrees C range, in an isotropic liquid phase, in the form of small aggregates.

Fourier Analysis↗

PubMed1992

Partial dehydration of phosphatidylethanolamine phosphate groups during hexagonal phase formation, as seen by i.r. spectroscopy.

The gel-to-fluid and lamellar-to-HII-hexagonal thermotropic phase transitions of egg-yolk phosphatidylethanolamine have been examined by Fourier-transform infrared spectroscopy under a variety of conditions, namely excess water at pH 5.0, excess water at pH 9.5 and low hydration. The various lamellar and hexagonal phases have been characterized by X-ray diffraction. At pH 5.0, gel-fluid and lamellar-hexagonal transitions were detected at 10 and 32 degrees C respectively, in accordance with previous data. At pH 9.5, only the first of these two transitions was detected. In the partially hydrated sample a single phenomenon was observed, probably encompassing both transitions, so that, in practice, a gel-HII-hexagonal transition appears to occur. The region of the i.r. spectrum corresponding to the phospholipid phosphate group reveals that the lamellar-hexagonal, but not the gel-fluid, transition is accompanied by a weakening in the shell of hydrogen-bonded water, thus providing direct evidence that, in a pure lipid/water system, hexagonal phase formation requires partial dehydration of the phospholipid phosphate group. X-ray diffraction data support this conclusion, since, at least in the low-hydration system, the average surface area per lipid polar group decreases with the thermotropic lamellar-hexagonal transition.

Fourier Analysis↗

PubMed1992

Systemic lupus erythematosus: a case report with unusual manifestations and favourable outcome after plasmapheresis.

We report a case of systemic lupus erythematosus (SLE) in a 15-year-old girl with severe neurological disease, platelet function disorder and pulmonary haemorrhage, which remitted after plasmapheresis. The patient developed protein-losing enteropathy shrinking lung, and acute pancreatitis with pseudocyst formation. These infrequent complication of SLE are discussed.

Adolescent↗