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Biomedical subjects

G Ruiz

Publications and source records attributed to G Ruiz.

At least 37 records · Page 2Linked to original sources
PubMed2001

A search for natural bioactive compounds in Bolivia through a multidisciplinary approach. Part V. Evaluation of the antimalarial activity of plants used by the Tacana Indians.

One hundred and twenty-five extracts of 122 different plant species traditionally used by the Tacana, a native community living in lowland forest at the base of the last foothills of the Cordillera Oriental of the Bolivian Andes, were screened for antimalarial activity in vitro on Plasmodium falciparum chloroquine resistant (D2) and sensitive strains (F32), and were evaluated in vivo on rodent malaria Plasmodium berghei. Five ethanolic stembark extracts showed marked activity either in vitro or in vivo, and only one of them, Bowdichia virgilioides being traditionally used against malaria, was active in vitro (IC50=1 microg/ml on both strains) and in vivo (51% at 100 mg/kg). Other active extracts were from Caesalpinia pluviosa bark displaying activity in vitro against chloroquine resistant strain (IC50 8.3 microg/ml), traditionally used against dysentery; two Lauraceae bark extracts, Nectandra aff. hihua and Licaria canella respectively used for construction purposes and against stomach ache, both displaying activity in vitro against P. falciparum sensible and resistant strains (IC50 around 4 microg/ml); finally, the bark of a strongly aromatic Burseraceae, Protium glabrescens exuding an anti-inflammatory and analgesic resin, was active in vivo only (61% at 100 mg/kg). Results are discussed in relation with Tacana traditional medicine.

Animals↗
PubMed2001

An analysis of articles on neonatal pain published from 1965 to 1999.

OBJECTIVE: To analyze articles on neonatal pain indexed in MEDLINE from 1965 to 1999. METHODS: Papers published since 1965 and indexed in Medline (PubMed ) were considered. The search strategy was: 'pain' (MeSH terms) OR 'pain' (Title word) OR 'pain' (All Fields), AND 'infant, newborn' (MeSH terms). After the search was completed, a printed copy of the references was obtained, and each reference was reviewed to establish its pertinence to the study's objective. For each article, the year of publication, the journal of publication, the language of the journal, the country of the first author, the type of article and the subject were analyzed. RESULTS: Only 545 of 2490 references identified by the MEDLINE search were considered to deal with neonatal pain. Few articles on neonatal pain were published from 1965 to 1985, but the number of articles published on this topic increased sharply after 1985. Most of the papers were published in English (84.6%). The United States, Canada and the United Kingdom were the main countries that published neonatal pain articles (38.6%, 14.2% and 13.3%, respectively). Clinical research articles (31.7%) were published most frequently; the main subjects of all the articles were pain related to colic (20.4%), general neonatal pain issues (13.6%) and procedural pain (13.4%). Pediatrics and Archives of Diseases in Childhood were the journals that published the most articles on neonatal pain (27 and 22, respectively). CONCLUSIONS: Pain in neonates was a neglected subject of publication until the mid-1980s, and, currently, only a few countries seem interested in this type of pain. This lack of interest may be related to the undertreatment of pain in the neonatal period.

Demography↗
PubMed2001

Characterization of retinal injury using ERG measures obtained with both conventional and multifocal methods in chronic ocular hypertensive primates.

PURPOSE: To characterize, using both conventional and multifocal electroretinogram (ERG) recordings as well as histologic measures, retinal injury in the chronic ocular hypertensive primate model for experimental glaucoma. METHODS: Ocular hypertension was induced in the right eye of 7 cynomolgous monkeys, Macaca fascicularis, using laser injury to the aqueous outflow tissue at the anterior chamber angle. At 16 months after IOP elevation, ERG recordings were made from both eyes of all animals using both conventional and multifocal methods. After electrophysiological recording, animals were killed and retinal samples were radially sectioned for histologic analysis. RESULTS: Histologic measures showed that ocular hypertensive injury was largely or completely limited to a loss of retinal ganglion cells (RGCs). The degree of RGC loss was similar in central and peripheral retina. Amplitudes of conventional ERG responses were mostly unaffected in eyes having severe loss of RGCs, a finding that is consistent with limited injury to photoreceptors, bipolar cells, and amacrine cells. Peaks in both the first- and second-order multifocal ERG responses were attenuated in ocular hypertensive eyes, and amplitude of these peaks was highly correlated with the density of surviving RGCs. CONCLUSIONS: The results are consistent with a conclusion that both first- and second-order components of the multifocal ERG response from the monkey reflect a significant contribution from activity in RGCs and may provide a useful measure for the clinical diagnosis and management of glaucoma.

Animals↗
PubMed2001

Neuroprotection of retinal ganglion cells by brimonidine in rats with laser-induced chronic ocular hypertension.

PURPOSE: To examine the neuroprotective effect of the alpha(2)-adrenergic agonist brimonidine in a chronic ocular hypertension model. METHODS: Intraocular pressure (IOP) was elevated by laser photocoagulation of episcleral and limbal veins. Retinal ganglion cell loss was evaluated in wholemounted retinas. Brimonidine or timolol was administered, either at the time of or 10 days after IOP elevation and continued for 3 weeks. Drug-related immunohistochemical changes in glial fibrillary acidic protein (GFAP) were also determined after 3 weeks. RESULTS: Laser treatment caused a twofold IOP increase over baseline that was maintained for 2 months. A time-dependent loss of ganglion cells occurred with elevated IOP. Systemic administration of brimonidine or timolol caused little decrease in IOP. After 3 weeks of elevated IOP, ganglion cell loss in control rats was 33% +/- 3%. Brimonidine reduced the progressive loss of ganglion cells to 26% +/- 1% and 15% +/- 2% at doses of 0.5 and 1 mg/kg. d, respectively. Timolol had no effect. Ten days of high IOP resulted in 22% +/- 4% ganglion cell loss. Brimonidine administration initiated 10 days after IOP elevation prevented any further loss of ganglion cells. In vehicle- or timolol-treated rats, ganglion cell loss continued to 33%. The increase in immunoreactivity of GFAP in ocular hypertensive retinas was attenuated by brimonidine. CONCLUSIONS: Systemic application of brimonidine or timolol had little effect on IOP. Brimonidine, but not timolol, showed significant protection of retinal ganglion cells when applied at the time of IOP elevation and prevented further cell loss when applied after IOP was elevated. This indicates that brimonidine has a neuroprotective activity unrelated to its effect on ocular hypotension.

Adrenergic alpha-Agonists↗
PubMed2000

Aminothiol multidentate chelators against Chagas disease.

Three compounds of an aminothiol family of iron chelators were examined for activity against trypomastigote (human) and epimastigote (vector) forms of Trypanosoma cruzi: tetraethyl and tetramethyl derivatives of ethane-1,2-bis (N-1-amino-3-ethyl butyl-3-thiol) (BAT-TE and BAT-TM) and N',N',N'-tris-(2-methyl-2-mercaptopriopyl)- 1,4,7-triazacyclonane (TAT). BAT-TE at 270 microM completely arrested the growth of trypomastigote forms in mouse blood stored at 4 degrees C for 24 h (IC(50) 67.7+/-7 microM), while BAT-TM arrested growth at 630 microM (IC(50) 158+/-17 microM) and TAT at concentrations >800 microM (IC(50) 415+/-55 microM). In T. cruzi-infected mice, BAT-TE and BAT-TM had no anti-trypanosomal activity in doses up to 200 mg/kg, whether the route of administration was intraperitoneal or oral, and TAT was not tested due to insufficient quantity. TAT had an IC(50) of 52+/-7 microM against the epimastigote forms while BAT-TM and BAT-TE were inhibitory only at concentrations >250 microM. The trypanocidal activity of BAT derivatives in blood stored at 4 degrees C makes these compounds potential candidates for the purpose of clearing donated blood of trypomastigotes.

Animals↗
PubMed2000

Ex vivo bactericidal activity against group C Neisseria meningitidis in seronegative subjects.

BACKGROUND: To determine the anti-meningococcal C immunological activity by adding functional tests (opsonophagocytosis) to the classical serology techniques. SUBJECTS AND METHODS: 42 adult volunteers were screened using serological methods (determination of total and bactericidal antibodies). Seronegative subjects were tested by opsonophagocytosis. RESULTS: 24 subjects (57%) showed serological evidence of previous contact with Neisseria meningitidis group C antigens: 19 subjects had both total and bactericidal antibodies, two subjects had only total antibodies and three subjects had only bactericidal antibodies. Of the 18 seronegative subjects, five showed ex vivo activity in killing curves with or without polymorphonuclear cells: two subjects exhibited only complement-mediated bactericidal activity, one subject only opsonophagocytosis, and two subjects exhibited both activities. CONCLUSION: The addition of functional tests to the classical serological determination increases the evidence of previous contact with N. meningitidis antigens by 12%.

Adult↗
PubMed2000

A search for natural bioactive compounds in Bolivia through a multidisciplinary approach. Part III. Evaluation Of the antimalarial activity of plants used by Alteños Indians.

A total of 40 plant extracts traditionally used by the Alteños Indians, a native community living between the Andean block and the tropical valleys of Bolivia, were screened for antimalarial activity in vitro on Plasmodium falciparum chloroquine resistant (Indo) strain, and in vivo on rodent malaria Plasmodium vinckei petteri. Eleven extracts displayed good or moderate activity in vivo, and ten extracts good or very good antimalarial activity in vitro. Results of the screening are discussed here, in relation with the traditional use of plants.

Antimalarials↗
PubMed2000

Mycobacterium tuberculosis infection in pediatric liver transplant recipients.

OBJECTIVES: To study the incidence, clinical presentation, management, complications and outcome of tuberculosis in pediatric liver transplant recipients. METHODS: A retrospective review of the medical records of children who underwent liver transplantation between 1991 and 1998. RESULTS: Mycobacterium tuberculosis infection occurred in 6 of 254 (2.4%) children undergoing liver transplantation between 1991 and 1998. Cough, pyrexia and poor appetite were common presentations; one-half had normal chest radiographs. The median time to confirmation of diagnosis was 8 months (range, 1 to 17 months). Tests contributing to diagnosis included: Ziehl-Neelsen (ZN) stain (2 patients), M. tuberculosis polymerase chain reaction (1 patient), Mantoux test (1 patient) and histopathology (4 patients). Family health screening was productive for 4 patients. Duration of treatment varied from 9 to 18 months. Isoniazid-induced hepatitis was observed in 2 patients but resolved with dose reduction. Two patients died while receiving treatment, one of Klebsiella spp. septicemia and the other of pulmonary hemorrhage. CONCLUSIONS: Tuberculosis after liver transplantation has a significant morbidity and mortality. Pretransplantation a personal and family history of tuberculosis must be sought, and screening of patients and their families should be considered. Standard regimens incorporating isoniazid and rifampin are effective, but regular monitoring of liver function is essential to detect drug-induced hepatotoxicity.

Adolescent↗
PubMed1999

Influence of physician attitudes on willingness to perform abortion.

OBJECTIVE: To survey attitudes about abortion in a sample of physicians practicing in the Bronx, New York, identify factors associated with those attitudes, and investigate how attitudes about abortion influence willingness to do it. METHODS: A questionnaire mailed to obstetricians and gynecologists affiliated with a medical school in the Bronx elicited information on attitudes about abortion and the willingness to do it. Attitude scores were measured on a Likert scale ranging from 1 to 5, with 5 indicating a proponent attitude about abortion. The practice score ranged from 0 to 2, with 2 indicating proponent attitude about practicing abortion. RESULTS: The median attitude score was 3.8. Physicians were receptive to reasons for abortion that were medically indicated. A proponent attitude was found in non-Catholics and those who were trained in residency programs that required observing abortions. The median practice score was 1.2. The most important personal factors influencing a physician's decision not to perform abortions included lack of proper training and ethical and religious beliefs. There was a significant positive correlation between the attitude score and practice score (r = .42, P < .001). CONCLUSION: Personal beliefs and past experience with abortion are associated with attitudes about abortion that, besides competence doing them, influence physicians' willingness to do them. Offering training in abortion might benefit physicians who are proponents and willing to perform abortions.

Abortion, Induced↗
PubMed1999

Cellular and subcellular localization of 5-hydroxytryptamine1B receptors in the rat central nervous system: immunocytochemical, autoradiographic and lesion studies.

The localization of 5-hydroxytryptamine1B receptors in the rat central nervous system was investigated using anti-peptide antibodies that recognize a selective portion of the third intracytoplasmic loop of the receptor protein. At the light microscope level the densest 5-hydroxytryptamine1B receptor-like immunoreactivity was observed in ventral pallidum, globus pallidus, substantia nigra and dorsal subiculum. In addition, moderate immunoreactivity was found in the entopeduncular nucleus, the superficial gray layer of the superior colliculus, the caudate-putamen and the deep nuclei of the cerebellum. This distribution matched perfectly that previously described from radioligand binding studies. At the ultrastructural level, 5-hydroxytryptamine1B receptor-like immunoreactivity was associated with axons and axon terminals in the three areas examined: substantia nigra, globus pallidus and superficial gray layer of the superior colliculus. In all cases, immunostaining was located on the plasma membrane of unmyelinated axon terminals and in the cytoplasm close to the plasmalemma. Synaptic differentiations were never labelled but, in some cases, 5-hydroxytryptamine1B receptor-like immunoreactivity was found in their close vicinity. Injection of kainic acid into the neostriatum resulted in a marked decrease in receptor-like immunoreactivity in the globus pallidus and the substantia nigra, consistent with the location of 5-hydroxytryptamine1B receptors on terminals of striatopallidal and striatonigral fibres, respectively. A reduction in 5-hydroxytryptamine1B receptor-like immunoreactivity was also noted in the superficial gray layer of the superior colliculus after contralateral enucleation, as expected of the location of 5-hydroxytryptamine1B receptors on the terminals of retinocollicular fibres. In both lesion experiments, immunolabelled degenerating terminals were observed in the projection areas. Anterograde labelling experiments coupled with immunocytochemical detection further showed that 5-hydroxytryptamine1B receptors in the substantia nigra are located on axons of striatal neurons. These data provide anatomical support for the idea that 5-hydroxytryptamine1B receptors act as terminal receptors involved in presynaptic regulation of the release of various neurotransmitters, including 5-hydroxytryptamine itself.

Animals↗
PubMed1999

Plasticity of 5-hydroxytryptamine(1B) receptors during postnatal development in the rat visual cortex.

The distribution of 5-hydroxytryptamine1A and 5-hydroxytryptamine1B receptors in the visual cortex was studied by quantitative autoradiography during postnatal development. Overall, receptor densities increased throughout development, but exhibited regional rearrangements, particularly in the case of 5-hydroxytryptamine1B receptors. Neonatal treatment with 5,7-dihydroxytryptamine, which causes selective degeneration of serotoninergic neurons, had no effect on the density of 5-hydroxytryptamine1A receptors in the visual cortex. However, a transient increase in 5-hydroxytryptamine1B at postnatal days 10-12 was observed after this treatment, suggesting a regulation of postsynaptic receptors. Neonatal enucleation resulted in a marked increase in 5-hydroxytryptamine1B binding sites in all layers of the visual cortex by P16, whereas it had no effect upon 5-hydroxytryptamine1A binding sites. These results show that both receptor subtypes do not exhibit striking transient features in the visual cortex during postnatal development, but rather undergo discrete reorganizations. 5-Hydroxytryptamine1B receptors show changes in density after either neonatal degeneration of serotoninergic neurons or enucleation, indicating that the serotoninergic system involving this receptor subtype can exhibit some postnatal plasticity in the visual cortex.

5,7-Dihydroxytryptamine↗
PubMed1999

Homeopathic effect on heart rate variability.

We record ECGs from healthy human subjects during 24-h long intervals, using ambulatory equipment. We calculate from the data various parameters, searching for those that change in a clear and systematic way under a homeopathic stimulus, (Strophantus hispidus 30c). The energy fraction at high frequencies in the power spectrum of heart rate variability fulfills this condition, and we are able to interpret our results in a way consistent with the information on this medicine in the homeopathic Materia Medica.

Adolescent↗
PubMed1998

Acquisition of basic concepts by children with intellectual disabilities using a computer-assisted learning approach.

Computer-assisted learning can be an efficient learning-teaching procedure. Although there is an extensive educational software tradition for this approach, few have better performance than standard drill-and-practice methods. In this work, the specific software "Let's Play With..." was designed to teach concepts of colours, shapes, and body position to children with intellectual disabilities. The software structure follows the Gagné instructional design and applied behaviour analysis. The program was carried out with 39 boys and 21 girls who were special education students in the Cadiz School District. Statistically significant differences were found between groups taught with and without the software.

Achievement↗
PubMed1996

Presence and release of immunoreactive atrial natriuretic peptide (ANP) in Bufo arenarum spermatozoa after HCG treatment.

Atrial natriuretic peptide (ANP)-like immunoreactivity has been demonstrated in mature spermatozoa of Bufo arenarum. However, after spermiation induced by Gonadotropin Releasing Hormone (GnRH), no ANP immunoreactivity was detected in testicular spermatozoa. Recently, the presence of GnRH and GnRH receptors in amphibian testes has been demonstrated. To clarify if the loss of ANP-like immunoreactivity in spermatozoa is a direct effect of GnRH or pituitary gonadotropins, a study on Bufo arenarum adult males, has been performed. The in vivo treatment with Human Chorionic Gonadotropin (HCG) induced spermiation and loss of ANP-like immunoreactivity. The in vitro treatment with HCG showed the same results. However, in vitro GnRH treatment failed to cause spermiation and loss of ANP-like immunoreactivity. The present results indicate that ANP from mature spermatozoa is regulated via gonadotropic hormones and may be involved in the spermiation process.

Animals↗
PubMed1995

Birth weight and special educational needs: effects of an increase in the survival of very low birthweight infants in London.

OBJECTIVES: To assess the contribution of children with different birth weights to special educational needs within a single health district, and to determine whether this pattern changed over the time when the survival of very low birthweight (VLBW) infants was increasing. SETTING: An inner London health district. STUDY DESIGN: A cohort of children born to local parents between January 1974 and December 1980 was selected from birth notifications, including only those infants who survived for more than one month. Community child health records were then inspected to identify children from the cohort who had been formally assessed for special educational needs before their 8th birthday. The risk of special educational needs was compared for the years 1974-77 and 1977-80 (the first and second halves of the period studied). SUBJECTS: The infant cohort consisted of 31,846 children. Altogether 260 (0.8%) of these were later assessed formally. RESULTS: VLBW infants were 4.4 times more likely to be assessed than normal birthweight infants. Formal assessment within the district occurred in three of 68 VLBW infants from the first half of the period studied, and three of 120 from the second half. CONCLUSION: Although VLBW infants are at higher risk, an increase in their survival was not associated with any increase in their contribution to the group with special educational needs within our district. Their contribution, as a group, to the total number of children with special educational needs is very small.

Birth Weight↗
PubMed1994

[Duffy blood group in malformed newborns and their mothers].

The aim of this work is to analyze the distribution of Duffy blood group and the reproductive history of 148 malformed newborns and their mothers compared to 131 control pairs. The mother-child segregation of the system is analyzed using ITO matrixes. A higher frequency of heterozygote mothers for the system was found among the malformed group compared to controls. No differences in the reproductive history was found between Duffy system homozygote or heterozygote mothers.

Case-Control Studies↗
PubMed1994

[Maternal age as a risk factor for congenital malformations].

We studied 131,899 consecutive births at the Maternity of the University of Chile Clinical Hospital, finding 4887 newborns with congenital malformations (representing a rate of 37.05 per 1000 alive newborns). Between January 1982 and December 1992 there were 41,344 births and 295 stillbirths (0.7%). Among the latter, 41 were malformed (13.9%). A graphic comparing the mean annual rates of malformations and maternal ages, shows a sustained increase in malformations form 1972 to 1988, that decreases thereafter and stabilizes since 1982. There is a marked parallelism between the curves of malformation rates and maternal age (t21 = 1.057, p < 0.1). It is concluded that the risk of congenital malformations increases along with maternal ages.

Adult↗