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R Benítez

Publications and source records attributed to R Benítez.

24 records · Page 2Linked to original sources
PubMed1998

Investigations on the in vitro metacyclogenesis of a visceral and a cutaneous human strain of Leishmania infantum.

The in vitro metacyclogenesis of a visceral (VL) and cutaneous (CL) human strain of Leishmania infantum was monitored in order to find out the kinetics of this process and the in vitro infective capacity for macrophages of the metacyclic promastigotes developed. To identify, enumerate, and separate the metacyclic population, the complement-dependent lysis by normal serum and the agglutination by peanut agglutinin (PNA) were used, as they were shown to be useful for the purpose of this study. Maximum percentage of metacyclics was detected by both techniques on the 4th day of growth for VL and the 6th day for CL, and was higher for the VL strain. The in vitro infectivity for macrophages of two strains was assayed, and the high parasitization data obtained were transformed in order to determine the increase of the parasite burden for macrophages throughout the incubation time of the experiments (2-72 h post-infection (p.i.)). This parameter is denominated the infectivity ratio (%I) and calculated as follows: (number of intracellular parasites per infected macrophage at 'x' time p.i./number of intracellular parasites per infected macrophage at 2 h p.i.) x 100. When %I was calculated for promastigotes unagglutinated by PNA (PNA-)--metacyclic or infective promastigotes--at any time of culture, the %I at 72 h p.i. was always much higher than for agglutinated promastigotes (2.1-12.5 times)--non-infective promastigotes--and unfractionated promastigotes from culture (1.7-9.5 times), especially with VL parasites. Likewise, the %I for VL PNA- promastigotes from the 4th day of culture was 1.9 times higher than for CL PNA- promastigotes from the 6th day of culture. The higher resistance to lysis by serum, percentage of metacyclics (PNA-), and infectivity ratio of VL than CL could be related to a higher spreading capability into the host body associated with higher pathogenic effects of the visceral strain than the cutaneous one.

Agglutination Tests↗
PubMed1998

Glutamate-like immunoreactivity in ascending spinofugal afferents to the rat periaqueductal grey.

The midbrain periaqueductal gray is a key structure for the mediation of an integrated defence behaviour. Although a prominent role for glutamate in PAG mechanisms is supported by both behavioural and morphological studies, whether PAG afferents conveying somatosensory information constitute a source of glutamatergic input to the PAG remains unknown. Here, we have compared the projection pattern of orthogradely-labelled spinoannular fibres with the distribution of glutamate-like immunoreactivity in the PAG at the light microscopic level. Transaxonal labelling was observed throughout the whole rostrocaudal axis of the PAG except for the dorsolateral regions. Cell-processes and terminal-reminiscent puncta were strongly immunoreactive in all PAG regions, including the dorsolateral areas. To ascertain whether glutamate-immunoreactive puncta observed at light microscopy indeed constituted axon terminals of the spinoannular system, glutamate-like immunoreactivity was assessed in orthogradely-labelled synaptic terminals using a post-embedding immunogold procedure for electron microscopy. Quantitative analysis of gold particle densities revealed over twice as strong an immunoreactivity in anatomically-identified spinoannular axon terminals as in dendrites postsynaptic to them, perikarya and inhibitory Gray II synapses, as well as an over 5-fold heavier immunolabelling than in glial profiles. These findings reveal that glutamate is accumulated in synaptic terminals of the spinoannular system, supporting a neurotransmitter role for this acidic amino acid in spinofugal afferents to the PAG.

Animals↗
PubMed1998

Immunocytochemical localization of the mGluR1b metabotropic glutamate receptor in the rat hypothalamus.

The mGluR1 metabotropic glutamate receptor is a G-protein-coupled receptor that exists as different C-terminal splice variants. When expressed in mammalian cells, the mGluR1 splice variants exhibit diverse transduction mechanisms and also slightly differ in their apparent agonist affinities. In the present study, we used an affinity-purified antiserum, specifically reactive to the mGluRlb splice variant, in combination with a highly sensitive preembedding immunocytochemical method for light microscopy to investigate the distribution of this receptor in the rat hypothalamus. An intense immunoreactivity for mGluRlb was observed in distinct hypothalamic nuclei. Thus, neuronal cell bodies and dendrites were stained in the preoptic area, suprachiasmatic nucleus, dorsal hypothalamus, lateral hypothalamus, dorsomedial nucleus, tuberomammilary nucleus, and lateral mammilary body. The ventromedial nucleus exhibited neuropil immunostaining but neuronal cell bodies were not labeled. Strong mGluRlb immunoreactivity was observed in magnocellular neurons of the neuroendocrine supraoptic, paraventricular, and arcuate nuclei. Also, neuronal cell bodies were heavily labeled in the retrochiasmatic nucleus, anterior commissural nucleus, and periventricular nucleus. These immunocytochemical observations, together with previous studies, suggest that mGluRlb is coexpressed with other class I mGluRs in some nuclei throughout the hypothalamus. However, mGluRlb is so far the only receptor of this class strongly expressed in the supraoptic, paraventricular, and arcuate nuclei, which might have relevant implications in the physiological control of the neuroendocrine hypothalamic-pituitary system.

Amino Acid Sequence↗
PubMed1993

[Molecular genetic study of a severe growth hormone deficiency in a Chilean family].

The first and so far the only form of isolated growth hormone deficiency to accede to molecular genetic analysis is IGHD 1A, which has an autosomal recessive mode of inheritance. Several sizes of growth hormone gene deletions, ranging from 6.7 to 8.5 Kb are responsible for IGHD 1A. It has been reported that children with IGHD 1A have an initial good response to growth hormone treatment, followed by growth failure associated with the development of blocking antibodies against growth hormone. The effectiveness of treatment has been associated to the size of the gene deletion. We performed a molecular genetic analysis of the growth hormone locus, using Southern Blot and PCR techniques, to a 12 years old girl who fulfilled the criteria for IGHD 1A and her closer relatives. The results showed a 7 Kb deletion for the growth hormone gene in the girl and one of her brothers.

Child↗
PubMedDate not supplied

[Cigarette smoking and its relation to pregnancy and lactation in Arica (Chile)].

Cigarette smoker and non smoker mothers from Africa, Chile, were followed along pregnancy and lactation and the influence of cigarette smoking on infant's birth weight and length of lactation was assessed from a sample of 240 pregnant women, 87 (36.3%) of them were actively smoking mothers and 33 among these (37.9%) smoked throughout all pregnancy and lactation. Mothers who smoked along lactation showed significantly shorter exclusive breast feeding time (2.6 month) in comparison with non smokers (3.5 month, p < 0.05) and their total lactation time was also reduced (4.2 vs. 5.3 months respectively, p < 0.01).

Adult↗