Biomedical subjects

S Ruiz

Publications and source records attributed to S Ruiz.

At least 73 records · Page 4Linked to original sources

PubMed1994

C3 binds with similar efficiency to Fab and Fc regions of IgG immune aggregates.

The covalent binding reaction of the third component of complement (C3) with rabbit IgG immune aggregates has been studied by enzymic digestion of C3b-IgG adducts. In these adducts C3b was radioactively labeled in the free thiol group generated during activation of the internal thioester of C3. Trypsin digestion of 14C-labeled C3b-IgG adducts degrades C3b to a small antibody-bound 14C-labeled C3 fragment (14C-C3frg), whereas the antibody remains unaltered. Papain digestion of trypsin-treated 14C-C3frg-IgG complexes generated Fc and Fab fragments bearing equivalent amounts of covalently bound 14C-C3frg (43% and 40%, of the total C3 present in the aggregates, respectively). Hydroxylamine treatment of the 14C-C3frg-Fab and 14C-C3frg-Fc complexes released a 14C-C3frg of similar size (about 3-4 kDa) in which the N-terminal residue was the radiolabeled Cys1010. A fragment with the same radioactive N terminus and characteristics was obtained by sequential trypsin and papain digestion of purified C3 labeled with iodo-[14C] acetamide. Affinity-purified 14C-C3frg-Fc complexes digested with pepsin generated a mixture of radioactive peptides, most probably complexes formed by 14C-C3frg and C gamma 2 or the hinge digestion products, and 14C-C3frg-pFc' complexes. The latter was also immunoprecipitated with anti-Fc-Sepharose from the pepsin digestion supernatants of 14C-labeled-C3b-IgG complexes. Taken together these data indicate that, during complement activation through the alternative pathway by IgG immune aggregates, C3 is not bound to a single site on the antibody molecule. Both Fab and Fc regions of IgG are equally efficient targets for C3 anchorage. In addition, the data confirm the pFc' as a region of C3 attachment within the Fc portion, and strongly suggest that C3b is bound either to the C gamma 2 domain or the hinge or both.

Animals↗

PubMed1994

Clonidine treatment during gestation prevents functional deficits induced by prenatal malnutrition in the rat visual cortex.

It has been shown that prenatal malnutrition results at birth in increased concentration of noradrenaline (NA) in the brain. Besides, it is known that NA is an important regulator of normal regressive processes occurring during synaptogenesis such as cell death, axonal pruning and synaptic elimination. The present study was designed to investigate (i) whether prenatal malnutrition enhances the NA release in the visual cortex and (ii) whether or not chronic administration of clonidine during gestation may prevent long-term deleterious effects of fetal malnutrition on functional properties of interhemispheric connections of the visual cortex and on the interhemispheric asymmetry of visual evoked responses. Prenatal malnutrition was induced by restricting food consumption to pregnant rats from Day 8 postconception to parturition. Results show that at birth, prenatally malnourished rats had higher NA release than normals. At 45-50 days of age, the malnourished group exhibited (a) reduced peak-to-peak amplitude and diminished extent of the projecting field of transcallosal evoked responses, and (b) abolished interhemispheric asymmetry of visual evoked responses. Clonidine administration to malnourished mothers from Day 14 postconception to parturition (10 g/kg/day s.c.), prevented in the offspring disorders induced by prenatal malnutrition on cortical NA release, on interhemispheric connectivity of visual areas and on interhemispheric bioelectrical asymmetry, probably by restoring the normal trophic role of NA during synaptogenesis. Results are discussed in relationship to normal regressive events occurring during early brain development.

Animals↗

PubMed1993

Arginine residues of the globular regions of human C1q involved in the interaction with immunoglobulin G.

The immunoglobulin G binding site in the globular regions of human complement subcomponent C1q has been investigated by chemical modification of histidine residues with diethylpyrocarbonate and arginine residues with phenylglyoxal and cyclohexane-1,2-dione (CHD). Only the modification of arginine residues with CHD fulfills the requirements of a specific modification without unwanted side reactions. Specific modification of arginine residues with CHD results in loss of immune complex recognition without affecting the binding of C1r2S2 to form C1. The gross structure of C1q is not changed by CHD treatment, and immune complex binding is restored to 82% of the control upon NH2OH treatment. Enzymic digestion and isolation of the modified peptides indicate that the modification by CHD of 4 to 5 arginine residues (A162, B114, B129, C156, and possibly B163) per C1q globular "head" abolishes the ability of C1q to interact with immune complexes. These residues define two areas (and possible binding sites for IgG) on the globular region of C1q: B114-B129 (site 1) and A162-(B163)-C156 (site 2). Sequence comparison and solvent exposure predictive studies favor site 2 as the immunoglobulin G binding site on the globular regions of C1q, although the participation of site 1 cannot be ruled out.

Amino Acid Sequence↗

PubMed1993

Functional alterations induced by prenatal malnutrition in callosal connections and interhemispheric asymmetry as revealed by transcallosal and visual evoked responses in the rat.

It is known that nutritional restriction during gestation affects the growth of the corpus callosum. The present study was designed to evaluate whether prenatal malnutrition may alter, in the rat, the normal pattern of functional callosal interhemispheric connections of the visual cortex. Since callosal development has been associated with brain lateralization, the effect of malnutrition during gestation on the normal asymmetry of visual cortical evoked responses was also studied. Prenatal malnutrition was induced by restricting food consumption by pregnant rats (10 g daily) from Day 8 post-conception to parturition. Results of experiments performed on 45- to 50-day-old offspring showed that the starvation treatment (i) reduced both the peak-to-peak amplitude and the extent of the projecting field of transcallosal evoked responses, and (ii) abolished the normal brain interhemispheric asymmetry of visual evoked responses. These effects are discussed in relationship to regressive events occurring during synaptogenesis, which are known to play key roles in establishing the adult structure and functional properties of the corpus callosum.

Animals↗

PubMed1993

In vitro fertilization of pig oocytes after different coincubation intervals.

The effects of gamete coincubation time on porcine in vitro fertilization for 4, 6 or 8 hours in Trial 1 or for 1, 2, 3 or 4 hours in Trial 2 were studied. The 876 oocytes were recovered from oviducts of prepubertal gilts. Ovulation was induced. Excessive spermatozoa attached to zona pellucida were removed by pippeting after coincubation (1 to 8 hours). Optimum results were obtained after 3 to 4 hours of coincubation, when 23 to 29% of the oocytes were fertilized by a single spermatozoa. Shorter intervals of coincubation were characterized by reduced percentages of fertilized oocytes and longer intervals of coincubation by increased rates of polyspermic fertilization. The employed sperm concentration was deliberately high (2 x 10(6) sperm/ml). The results show that a coincubation time of 4 hours may be optimal for pig in vitro fertilization. Under these assay conditions, modification of other factors such as sperm concentration, medium volume and physiological environment may increase the percentage of monospermic fertilization.

Journal Article↗

PubMed1993

Sperm concentration influences fertilization and male pronuclear formation in vitro in pigs.

To study the effect of sperm concentration on the results of pig in vitro fertilization (IVF), 313 oocytes recovered from oviducts of prepubertal gilts after induction of ovulation were used. After capacitation, the number of live spermatozoa in the fertilization dishes was adjusted to 3 x 10(5), 6 x 10(5) and 12 x 10(5) cell/ml. After 4 hours of co-culture in TCM-199, the oocytes were pippeted to remove cumulus cells and the excess spermatozoa around the zona pellucida, and were transferred to fresh TCM-199 for another 12/14 hours. The results showed that 6 x 10(5) spermatozoa/ml is the optimum concentration for this system; the percentage of fertilized ova (71.6%) was not different from the best (76.8%), that was obtained with the highest concentration, and the percentage of monospermy (62.3%) was not different from the best (68.1%), that was obtained with the lowest concentration. The percentage of spermatozoa that reached the pronuclear stage increased while sperm concentration was decreased. The percentage of spermatozoa at the decondensed stage was decreased when the sperm concentration increased.

Journal Article↗

PubMed1993

A tactile stimulator for studying motion processing in the somatic sensory system of primates.

A tactile stimulator was built for studying motion processing in the somatic sensory system of primates. This stimulator is used for assessing the responses of neurons of the somatic sensory system to stimuli moving in any traverse distance (range: 2-20 mm), with a variety of velocities (range: 4-120 mm/s), forces (range: 0-60 gf), and in any scanning direction. The stimulator is highly automated and can be used in combined psychophysical and neurophysiological studies in humans and in behaving monkeys.

Animals↗

PubMed1993

Long-term effects of neonatal capsaicin on C-fiber excitability and dorsal horn C-input processing in the rat.

The effects of neonatal capsaicin treatment (50 mg/kg, SC, at day 2 of postnatal life) on C-fiber excitability and dorsal horn C-input processing were studied through recording of a C-fiber-evoked spinal flexor reflex in 55-60-day-old rats, anesthetized with urethane (1.1 g/kg, IP) and spinalized at Th9-10. Neonatal capsaicin resulted in decreased C-fiber excitability, as revealed by increased chronaxie values determined in a strength-duration paradigm. Besides, capsaicin-treated rats exhibited a reduced potentiation of the C-reflex discharge in response to repetitive stimulation. The results indicate that capsaicin given to rats early in life leads to both functional disturbances of surviving C-fibers and altered temporal synaptic processing of the C-input in the spinal cord.

Afferent Pathways↗

PubMed1993

Environmental deprivation delays the maturation of motor pyramids during the early postnatal period.

The effects of environmental deterioration upon the development of motor cortex was studied in 30 Sprague-Dawley albino rats during lactation (1st-18th postnatal days). The use of Golgi-Cox-Sholl methodology allowed qualitative and particularly quantitative evaluations since impregnation of neurons take place at random without any selectivity. Morphometric studies were assessed by measuring layers II-III pyramidal neurons, basal dendritic branching, under camera lucida. Early environmental impoverishment results in a highly significant decrease in the number and length of peripherical branches and terminal dendrites. These results extend previous observations made predominantly in non-motor cortices which indicate that during early postnatal life restrictions or enrichments of the environment may be associated with quantitative changes in the differentiation of cerebrocortical neurons. It is of upmost importance to consider that the potential effects of different types of epigenetic cues are highly selective since pyramids of pups subjected to mild nutritional manipulation during the same developmental period remained unaffected.

Animals↗

PubMed1993

Environment and medium volume influence in vitro fertilisation of pig oocytes.

Oviductal oocytes (n = 795) were obtained from ovulation-induced prepubertal gilts. In the first experiment, different parameters related to in vitro fertilisation (IVF) were compared in the presence and absence of cumulus matrix (which is shed with the oocytes at ovulation). The results show that the presence of this matrix is beneficial because the rates of fertilisation (69%) and monospermy (number of monospermic oocytes/total number of healthy mature oocytes; 42%), and the median number of spermatozoa per oocyte (1.52 +/- 0.06), were improved with respect to those obtained in its absence (54%, 22% and 2.33 +/- 0.08, respectively; p < 0.01). In the second experiment the effect of two different volumes of co-incubation medium (2 ml and 0.4 ml) on the same parameters of porcine IVF were compared. No significant differences between volumes were observed, except in the mean number of spermatozoa per oocyte and the percentage of dispermic oocytes.

Animals↗

PubMed1993

Treatment of cervical lymphangioma using fibrin adhesive.

We present a case of cervical lymphangioma operated on when one month old. Three weeks later he suffered a relapse which caused respiratory problems since it affected the retropharyngeal pouch, with movement and compression of the upper airway. Given the technical difficulty of operating again, the transoral injection of fibrin adhesive was used as a sclerotic agent, which resulted in remission of symptoms and acceptable reduction in tumor size. The use of fibrin adhesive may be highly useful for the treatment of lymphangiomata and their complications.

Fibrin Tissue Adhesive↗

PubMed1993

Representation of tactile signals in primate supplementary motor area.

1. We have studied the neuronal activity in the supplementary motor area (SMA) of two monkeys who categorized the speed of moving tactile stimuli delivered to the glabrous skin of the hand ipsilateral to the site of cortical recording and contralateral to the responding arm. 2. A large number of SMA neurons responded to the stimuli of all speeds (176 of 522) but only when those stimuli controlled behavior. 3. A second class of SMA neurons responded differentially in the categorization task (35 during the stimuli and 51 during the reaction time period) and predicted its outcome. 4. To dissociate the interrupt target switches presses from the tactile categorization responses, sixteen neurons, which responded to the stimuli in all speeds, and 11 neurons, which discharged differentially, were tested in a visual control task. None of these two classes of neurons responded in this situation. 5. It is concluded that the SMA ipsilateral to sensory input and contralateral to the responding arm is involved in the sensory decision process in this somesthetic categorization task.

Afferent Pathways↗

PubMed1992

CD20 and CD5 expression in B-chronic lymphocytic leukemia.

In order to quantitate a previously noted decrease in CD20 fluorescence intensity (FI) on B-CLL lymphocytes, binding capacities [BC x 10(3) +/- 1SD = number of antibodies bound per cell] were calculated. The mean (N = 5) BC x 10(3) +/- 1SD of CD20 reagents for normal B-PBL and B-CLL lymphocytes confirmed this observation. B-PBL and B-CLL were 56 +/- 11 and 61 +/- 14, and 19 +/- 15 and 18 +/- 16, respectively, for Leu 16 and B1. Although adequate compensation standards for the determination of CD5 and CD20 coexpression are not available, qualitatively, the density of CD5 on both normal B-PBL and B-CLL is less compared to the expression of CD5 by normal T cells. CD5 expression on B-CLL seems to be linked to the lower levels of CD20, whereas CD5 expression may appear to be absent on CLL lymphocytes expressing normal levels of CD20. Levels of CD20 in B-CLL suggest involvement of one or two genes (alleles) whose decreased expression may be linked to CD5 expression.

Antigens, CD↗

PubMed1992

Substance P depresses bioelectrical responses evoked in the nucleus tractus solitarii: interaction with gamma-aminobutyric acid-ergic neurons.

The effects of intracerebroventricular (i.c.v.) administration of substance P (SP) and gamma-aminobutyric acid (GABA) on responses evoked in the nucleus tractus solitarii (NTS) by electrical stimulation of the ipsilateral sinusal nerve were studied in alpha-chloralose-anesthetized rats. Both SP (0.01-10 micrograms) and GABA (100 micrograms) significantly depressed the presumably C-fiber mediated, late negative wave of the response. The effects were almost completely prevented by bicuculline (10 micrograms i.c.v.). It is concluded that i.c.v. administered SP induces dose-dependent depression of baro- and/or chemosensory transmission in the NTS, via a mechanism involving interactions with GABAergic neurons of the NTS.

Animals↗

PubMed1992

Use of triple stain technique for simultaneous assessment of vitality and acrosomal status in boar spermatozoa.

The object of this study was to adapt the triple stain technique to diluted and incubated boar spermatozoa. Freshly ejaculated semen was resuspended in MR-A diluent to contain 3 x 10(7) cells/ml (diluted spermatozoa) and was subsequently capacitated (incubated spermatozoa). Experiments were conducted to show the conditions required for optimal staining quality and validation of triple stain technique. The most satisfactory staining solutions for diluted spermatozoa were 2% Trypan blue at 37 degrees C for 15 minutes, 0.8% Bismarck brown in 30% ethyl alcohol (pH 2.8) at 40 degrees C for 10 minutes and 0.8% rose Bengal in 0.1 M of Tris (pH 4.3) at 21 degrees C for 20 minutes. Satisfactory results were obtained for incubated spermatozoa with rose Bengal when the staining time was 10 minutes. Triple stain technique seemed to be a useful method for the simultaneous assessment of sperm vitality and acrosomal status; consequently, it should be valuable tool, for use in porcine in vitro fertilization systems.

Journal Article↗

PubMed1992

Seasonal variations of semen quality in male goats: study of sperm abnormalities.

The type, frequency and seasonal variation of sperm abnormalities in male goats inhabiting in Mediterranean region were evaluated. Semen was collected twice a week with an artificial vagina from 9 10-month-old Murciano-Granadina male goats weighing 41 to 48 kg. Distal cytoplasmic droplets and acrosomal damage were the predominant abnormalities. Increase in age (10 to 27 months) did not reveal itself as a main effect on the occurrence of sperm abnormalities. All types of sperm abnormalities studied showed significant (P<0.01) seasonal variation. The poorest quality semen was collected during winter and spring. In spite of a seasonal variation in sperm quality, semen of Murciano-Granadina goats in the Mediterranean area is good all year long, since the proportion of abnormal spermatozoa was well within the accepted range for normal fertility.

Journal Article↗

PubMed1992

Organization of repetitive DNA sequences in the genome of the echinoderm Holothuria tubulosa.

The abundance of repetitive DNA in the haploid sea cucumber genome has been determined by screening a Holothuria genomic DNA library for clones containing repeated sequences using reverse genome hybridization. Analysis by in situ plaque hybridization of a set of 1132 clones has revealed the presence of repetitive DNA sequences in about 38.1% of the clones screened. The distribution of the reiterated DNA has been further analyzed by restriction endonuclease digestion of seven randomly selected repetitive clones. The repeated sequences have a fairly uniform distribution of lengths with an average length value of 7.3 kb. Analysis of the measurements suggests that the repetitive sequences are interspersed among longer single copy sequences with an average spacing interval of about 47.3 kb indicating that the repetitive and single copy DNA in the Holothuria genome are arranged in a long-period interspersion pattern.

Animals↗

PubMed1992

Effect of therapy with a new glucocorticoid, deflazacort, on linear growth and growth hormone secretion after renal transplantation.

Deflazacort is an oxazoline compound derived from prednisolone with similar antiinflammatory effects but fewer side effects. We studied changes in kidney function, growth velocity, weight/height ratio, and growth hormone secretion before and a year after substitution of deflazacort for methylprednisone in nine patients aged 9 to 15 years, 4 years after renal transplantation; all were in Tanner pubertal stage 1. Methylprednisone (mean +/- SEM: 0.2 +/- 0.02 mg/kg per day) was replaced by deflazacort (0.3 +/- 0.03 mg/kg per day) for a mean period of 15 months. Serum creatinine and calculated creatinine clearance did not change significantly during deflazacort treatment. Growth velocity increased from 1.5 +/- 0.3 to 3.2 +/- 0.5 cm/yr (p < 0.005) in the nine patients. Weight/height ratio decreased from 28.4% +/- 8.5% to 16% +/- 6.7% (p < 0.005). Cushingoid appearance decreased in all patients. Mean spontaneous growth hormone secretion increased from 2.5 +/- 0.4 to 4.4 +/- 1.2 ng/ml (p < 0.05). Our findings indicate that immunosuppressive treatment with deflazacort is as effective as methylprednisone and is associated with fewer side effects.

Body Height↗