Biomedical subjects

H García

Publications and source records attributed to H García.

At least 37 records · Page 2Linked to original sources

PubMed2001

Laser flash photolysis study of Jacobsen catalyst and related manganese(III) salen complexes. Relevance to catalysis.

The laser flash photolysis and emission properties of a set of five-coordinate manganese(III) Schiff-base complexes have been examined. In contrast to the intramolecular electron transfer between Mn3+ and the equatorial salen ligand reported to occur in the absence of axial coordination, our laser flash photolysis study has shown that the reactivity of the respective excited states is appreciably influenced by the electron donor strength of the apical ligand at the metal center. In fact, homolytic and heterolytic photocleavage of the metal-ligand apical bond can be the most important processes upon laser excitation, their relative contribution being influenced by medium effects and the sigma-charge donation of the axial ligand. On the other hand, the detection of reactive intermediates such as the oxomanganese(V) salen complex (lambda(max) 530 nm) by laser flash photolysis opens the way to apply this fast detection technique to the study of reaction mechanisms in catalysis by metallic complexes. As a matter of fact, quenching of oxomanganese(V) salen by simple alkenes has been observed by laser flash.

Journal Article↗

PubMed2001

[Deciduosis of the appendix as cause of acute abdomen in pregnancy].

Ectopic decidua reaction or deciduosis is a physiological phenomenon of pregnancy due to a progesterone induced metaplasia of the pluripotential cells of the subcelomic mesenchyma. Usually it is an incidental finding that has not been associated with clinical symptoms. Isolated cases of ectopic decidua have been reported with symptoms simulating appendicitis. We are reporting a case of deciduosis localized in the appendix with abdominal pain during the last period of pregnancy.

Abdominal Pain↗

PubMed2001

[Multifocal motor neuropathy. Immediate response to intravenous immunoglobulin].

Multifocal motor neuropathy, a rare insidious immune-mediated disorder, features muscular weakness and atrophy, as well as areflexia, due to nerve conduction block and is often associated with the presence of anti-GM1 antibody. We report a patient with a nine-year history of progressive upper limb weakness, misdiagnosed as amyotrophic lateral sclerosis, who responded within hours to intravenous immunoglobulin treatment with full recovery of muscle strength. This case highlights the need to search for conduction block in patients with lower motor neuron involvement.

Amyotrophic Lateral Sclerosis↗

PubMed2001

[Clinical and molecular study of Chilean patients with McCune-Albright syndrome].

BACKGROUND: McCune-Albright Syndrome (MAS) is characterized by precocious puberty, "cafe au lait" skin lesions and polyostotic fibrous dysplasia. It is caused by 4 post-zygotic mutations of G alpha s protein with a mosaic distribution. AIM: To describe the clinical presentation and to investigate the presence of the Arg by his substitution (R201H) in 14 girls with MAS. PATIENTS AND METHODS: We performed a clinical analysis of the patients and specific allele PCR in DNA obtained from leukocytes. RESULTS: Twelve of 14 patients presented with precocious puberty, one with cyclical vaginal bleeding and one with pathological bone fractures. Eight girls had polyostotic fibrous dysplasia, one had hyperthyroidism, four had pathological fractures, ten had ovarian cysts, six had breast hyperpigmentation and ten had "cafe au lait" skin lesions. We detected the R2O1H mutation in 10 of 14 patients. We found no difference in the severity of symptoms or in the age of presentation between the patients with and without the mutation. CONCLUSIONS: The R201H mutation can be detected in white blood cells, in approximately 70% of cases. Patients exhibit wide clinical variability with the same molecular defect. This suggests that tissues have different proportions of mutant cells.

Adolescent↗

PubMed2000

Acute and oral subchronic toxicity of D-003 in rats.

D-003 is a mixture of higher aliphatic primary acids purified from sugar cane wax (Saccharum officinarum) with cholesterol-lowering and antiplatelet effects experimentally proven. The present work reports the results of two studies investigating the acute and subchronic oral toxicity of D-003 in rats. Oral acute toxicity of D-003 (2000 mg/kg) was investigated according to the Acute Toxic Class (ATC) method (an alternative for the classical LD(50) test), which was performed in Wistar rats. The results obtained in this study defined D-003 oral acute toxicity as unclassified. In the subchronic study, rats of both sexes were orally treated with D-003 at 50, 200 and 1250 mg/kg for 90 days. At this time, animals were sacrificed. No evidence of treatment-related toxicity was detected during the study. Thus, data analysis of body weight gain, food consumption, clinical observations, blood biochemical, haematology, organ weight ratios and histopathological findings did not show significant differences between control and treated groups. It is concluded that D-003 orally administered to rats was safe and that no drug-related toxicity was detected even at the highest doses investigated in both acute (2000 mg/kg) and subchronic (1250 mg/kg) studies.

Administration, Oral↗

PubMed2000

Simultaneous quantitation of intracellular zidovudine and lamivudine triphosphates in human immunodeficiency virus-infected individuals.

Highly active antiretroviral therapy (HAART) is the standard treatment for infection with human immunodeficiency virus (HIV). The most common HAART regimen consists of the combination of at least one protease inhibitor (PI) with two nucleoside reverse transcriptase inhibitors (NRTIs). Contrary to PIs, NRTIs require intracellular activation from the parent compound of their triphosphate moiety to suppress HIV replication. Simultaneous intracellular determination of two NRTI triphosphates is difficult to accomplish due to their relatively small concentrations in peripheral blood mononuclear cells (PBMCs), requiring large amounts of blood from HIV-positive patients. Recently, we described a method to determine intracellular zidovudine triphosphate (ZDV-TP) concentrations in HIV-infected patients by using solid-phase extraction and tandem mass spectrometry. The limit of quantitation (LOQ) for ZDV-TP was 0.10 pmol, and the method was successfully used for the determination of ZDV-TP in HIV-positive patients. In this study, we enhanced the aforementioned method by the simultaneous quantitation of ZDV-TP and lamivudine triphosphate (3TC-TP) in PBMCs from HIV-infected patients. The LOQ for 3TC-TP was 4.0 pmol, with an interassay coefficient of variation and an accuracy of 7 and 12%, respectively. This method was successfully applied to the simultaneous in vivo determination of the ZDV-TP and 3TC-TP pharmacokinetic profiles from HIV-infected patients receiving HAART.

Anti-HIV Agents↗

PubMed2000

[Chronic hereditary ataxic polyneuropathy].

Sensory ataxic polyneuropathies are characterised by the presence of sensory ataxia due to damage to large myelinated sensory fibres, with total or relative preservation of muscle strength, pain and temperature sensation. Hereditary ataxic polyneuropathies are exceptional and very few families with this disorder have been reported so far. We here describe the neurological, electrophysiological and sural nerve biopsy data of four siblings with an ataxic chronic polyneuropathy, starting after age 50. They had an ataxic gait which worsened in darkness, horizontal nystagmus, hypo or areflexia, and severe impairment of limbs' propriocaption. Nerve conduction studies showed absent sensory nerve action potentials in all nerves tested. Somatosensory evoked potentials showed reduced amplitude and prolonged latencies. Sural nerve biopsy showed a severe loss of myelinated and unmyelinated fibres. Symptoms slowly progressed over the years. The recognition of this syndrome is important in the search for the etiology of chronic ataxic neuropathies.

Aged↗

PubMed1999

Determination of zidovudine triphosphate intracellular concentrations in peripheral blood mononuclear cells from human immunodeficiency virus-infected individuals by tandem mass spectrometry.

Nucleoside reverse transcriptase inhibitors (NRTIs) used against the human immunodeficiency virus (HIV) need to be activated intracellularly to their triphosphate moiety to inhibit HIV replication. Intracellular concentrations of these NRTI triphosphates, especially zidovudine triphosphate (ZDV-TP), are relatively low (low numbers of femtomoles per 10(6) cells) in HIV-infected patient peripheral blood mononuclear cells. Recently, several methods have used either high-performance liquid chromatography (HPLC) or solid-phase extraction (SPE) coupled with radioimmunoassay to obtain in vivo measurements of ZDV-TP. The limit of detection (LOD) by these methods ranged from 20 to 200 fmol/10(6) cells. In this report, we describe the development of a method to determine intracellular ZDV-TP concentrations in HIV-infected patients using SPE and HPLC with tandem mass spectrometry for analysis. The LOD by this method is 4.0 fmol/10(6) cells with a linear concentration range of at least 4 orders of magnitude from 4. 0 to 10,000 fmol/10(6) cells. In hispanic HIV-infected patients, ZDV-TP was detectable even when the sampling time after drug administration was 15 h. Intracellular ZDV-TP concentrations in these patients ranged from 41 to 193 fmol/10(6) cells. The low LOD obtained with this method will provide the opportunity for further in vivo pharmacokinetic studies of intracellular ZDV-TP in different HIV-infected populations. Furthermore, this methodology could be used to perform simultaneous detection of two or more NRTIs, such as ZDV-TP and lamivudine triphosphate.

Adult↗

PubMed1999

Preliminary assessment of the safety and immunogenicity of a new CTXPhi-negative, hemagglutinin/protease-defective El Tor strain as a cholera vaccine candidate.

Vibrio cholerae 638 (El Tor, Ogawa), a new CTXPhi-negative hemagglutinin/protease-defective strain that is a cholera vaccine candidate, was examined for safety and immunogenicity in healthy adult volunteers. In a double-blind placebo-controlled study, no significant adverse reactions were observed in volunteers ingesting strain 638. Four volunteers of 42 who ingested strain 638 and 1 of 14 who received placebo experienced loose stools. The strain strongly colonized the human small bowel, as evidenced by its isolation from the stools of 37 of 42 volunteers. V. cholerae 638, at doses ranging from 4 x 10(7) to 2 x 10(9) vibrios, elicited significant serum vibriocidal antibody and anti-Ogawa immunoglobulin A antibody secreting cell responses.

Adult↗

PubMed1999

[Usefulness of the measurement of insulin-like growth factor (IGF-I) and IGF-1 binding protein-3 (IGFBP-3) for the diagnosis of growth hormone (GH) deficiency in children].

BACKGROUND: The diagnosis of GH deficiency (GHD) is based upon the results of GH stimulation tests, which have several drawbacks. AIM: To evaluate the usefulness of IGF-1 and IGFBP-3 for the diagnosis of GHD in prepuberal children. MATERIAL AND METHODS: We measured IGF-I and IGFBP-3 in three group of subjects: I. GHD (n: 24), height < -2SD for age (Z score, average +/- SD: -4.2 +/- 1.2), growth velocity < p10 (3.4 +/- 1.0 cm/year) and peak GH level on two GH stimulation tests < 7 ng/ml (1.2 +/- 0.6 ng/ml); II. Short non-GHD (NGHD, n: 32), height of -2.7 +/- 0.9 SD for age, growth velocity < p 25 (3.9 +/- 1.2 cm/year), and peak GH level on two GH stimulation tests > 7 ng/ml (15.3 +/- 6.9 ng/ml), y III. Normal school children (n: 35) with normal heights (-0.17 +/- 0.12 SD) were studied as controls. RESULTS: IGF-1 and IGFBP-3 were significantly lower in GHD than in NGHD and controls (p < 0.001), and in NGHD than in C (p < 0.001). We defined the normal range of both proteins as +/- 2 SD of the mean of the control group. Using this criteria, IGF-I was low in 21/24 GHD, and in 12/32 NGHD. IGFBP-3 was low in 22/24 GHD, and in 6/32 NGHD. Only 1 GHD patient had both exams in the normal range, suggesting that he is probably NGHD. 4/32 of the NGHD and both exams below normal range, suggesting that they are probably GHD. CONCLUSIONS: IGF-1 and IGFBP-3 are important tools for the diagnosis of GHD.

Child↗

PubMed1998

[The topographic diagnosis of the sympathetic nervous system lesions in Cuban epidemic neuropathy. The value of the sympathetic skin response].

The purpose of this study is to demonstrate from the electrophysiological point of view the existence of disorders of the autonomic nervous system (ANS) and to deepen in the probable topography of the lesions. The sympathetic skin response (SSR) was studied in 37 patients with Cuban epidemic neuropathy (CEN) and in 29 sound individuals. The response to electrical stimulation with simultaneous registry in the 4 limbs was assessed. The latencies and amplitudes of the SSR registered in the lower limbs of patients were significantly different from those of the controls (p < 0.05). This difference between both groups was not observed in the upper limbs. These results are an objective and reproducible evidence of the injury of the ANS in the Cuban epidemic neuropathy. The highest intensity of affectation of the amplitudes of the SSR of lower limbs, with relative indemnity of those of the upper limbs, suggests a predominance of the axonal injury of the peripheral efferent branch towards the lower limbs that is congruent with the greatest affectation of the peripheral nerves in this localization.

Adult↗

PubMed1998

[Vasculitis affecting the kidney: analysis of 18 patients].

OBJECTIVE: Eighteen patients who were judged to have systemic vasculitis (1990 American College of Reumathology criteria) affecting the kidney, from January 1988 to August 1996, were reviewed. METHOD: We analyzed characteristics of clinical, biochemical, histopathological features, the interval between the onset of the symptoms to a diagnosis of disease, treatment and overall outcome. RESULTS: The principal mode of presentation of the vasculitis is general, renal and pulmonary symptoms. The discovery of ANCA has improved the diagnostic procedure in patients with these diseases. Renal biopsy facilitates early diagnosis, prognosis and treatment. The renal lesion typically shows a segmental necrotizing glomerulonephritis and extracapillary proliferation forming crescent. CONCLUSIONS: The systemic vasculitis with renal involvement carries a poor prognosis and high mortality. A variety of treatment has been employed, but their precise role in the management of these vasculitis is still being elucidated.

Aged↗

PubMed1997

Multigeneration reproduction study of policosanol in rats.

The hypocholesterolaemic drug policosanol was administered to Sprague-Dawley rats of both sexes throughout three successive generations at concentrations of 0, 5, 50 and 500 mg/kg bw/day by gavage. For each generation two litters were reared until they were at least 3 weeks old. No clinical signs which could be related to the administration of the test substance were observed in the F0, F1b and F2b parents. There were no differences among groups in the number of animals that conceived, the number of pups born live or dead, the rate of male to female pups, the number of pups that survived until weaning and the pups' body weights through the lactancy. The following test showed no treatment-related effects on F3b offspring: righting on a surface, air righting, corneal, pirmal and pain reflexes, auditory startle and visual placing. The results of the present study did not demonstrate any deleterious effects on the fertility, reproductive performance or development of rats administered policosanol at levels of up to 500 mg/kg bw/day over three successive generations.

Animals↗

PubMed1997

Cell microchimerism in patients with recurrent spontaneous abortion: preliminary results.

The goal of this study was to determine the prevalence of non-host male cell microchimerism in a group of women with a history of recurrent spontaneous abortion (RSA). The detection of male cell microchimerism was based upon amplification of a fragment of Y chromosome DNA obtained from peripheral blood mononuclear cells from the mother. The amplification products were electrophoresed, transferred onto nylon membranes and hybridized with a specific 32P-labelled probe. The products were visualized by autoradiography. Seventy-seven patients with RSA were studied. Some patients (42.8%) had received immunotherapy for RSA using live mononuclear cells from male donors. Of the 77 patients 46 (59.7%) were positive for the selected Y chromosome sequence, 22 (28.6%) had no evidence of Y chromosome DNA and in nine (11.7%) cases the chimeric status could not be defined since the amplified band was too faint to be clearly assigned as positive. Twenty patients were pregnant at the time of sampling. There were no statistically significant differences among the different variables studied: age of the mother, number of previous pregnancies, number of previous immunotherapeutic inoculations or period of time between the last inoculation and sampling. Male cell microchimerism has been reported in some but not all women who have given birth to male children. The dynamics for the establishment of this chimeric status and its persistence have not been defined. We found that most patients with RSA (59.7%) were positive for microchimerism but that this could not be correlated with abortion, current pregnancy or leukocyte immunotherapy. A prospective study is being undertaken to determine if there is a subset of patients negative for chimerism who become positive after alloimmunotherapy with male lymphocytes and have an improved prognosis for successful pregnancy.

Abortion, Habitual↗

PubMed1996

Quantified electroencephalographic correlates of relative frontal or parietal hypoperfusion in dementia.

The authors examined the presence of specific quantified electroencephalographic (qEEG) changes in dementia patients with relatively lower frontal or parietal blood perfusion as demonstrated by SPECT. Over all brain regions, patients with relatively lower parietal perfusion showed significantly higher theta relative power than demented patients with relatively lower frontal perfusion or normal control subjects. Dementia patients with relatively lower frontal perfusion showed no differences from age-comparable normal control subjects in qEEG variables. These findings 1) suggest that usefulness of qEEG for the diagnosis of dementia is restricted to a subgroup of patients with the typical SPECT pattern of parietal blood hypoperfusion and 2) demonstrate that the qEEG changes typical of dementia are not related to perfusion deficits in frontal brain areas.

Aged↗

PubMed1996

Genetic manipulation of Vibrio cholerae for vaccine development: construction of live attenuated El Tor candidate vaccine strains.

The recent spread of El Tor cholera to America augments the need for an effective, safe and economical vaccine. In the present paper we describe the construction of live attenuated V. Cholerae strains by specifically deleting the genes encoding cholera toxin and other putative toxins from the bacterial chromosome. To maximize the likelihood of exposing protective antigens relevant to currently circulating vibrios we selected for genetic manipulation recent epidemic V. cholerae isolates from Peru. The mutant strains did not produce cholera toxin in vitro and in vivo. Deletion of the virulence cassette was accompanied by marked attenuation in the infant mouse cholera model. A selected El Tor Ogawa candidate vaccine strain was refractory to acquisition of foreign genes by conjugation with toxigenic vibrios.

Animals↗

PubMed1995

Quantified electroencephalographic changes in depressed patients with and without dementia.

We carried out quantified electroencephalograms (qEEG) in 17 patients with probable Alzheimer's disease (AD), who also met the DSM-III-R criteria for either dysthymia or major depression, and 18 AD patients with comparable intellectual impairment but no depression, 13 patients with depression but no AD, and 10 age-matched normal controls. There was a significant effect for depression in alpha relative power: depressed patients (with or without AD) showed a significantly lower alpha relative power in the right posterior region as compared to nondepressed patients; however, this change was observed over the right hemisphere in depressed non-AD patients, and in left, medial, and right posterior regions in depressed-AD patients. Depressed patients without AD showed a significant global decrease in delta power, whereas depressed patients with AD showed significant increments in delta power in posterior brain areas. In conclusion, AD patients with depression showed qEEG changes that were significantly different from qEEG changes in depressed non-AD patients.

Aged↗

PubMed1995

Quantified electroencephalographic correlates of neuropsychological deficits in Alzheimer's disease.

The authors examined relationships between quantified EEG (qEEG) variables and neuropsychological performance in 54 consecutive patients with probable Alzheimer's disease (AD). Patients were studied with qEEG and a neuropsychological battery that assessed memory, attention, verbal functions, set-shifting abilities, and procedural learning. More severe memory, attention, and verbal deficits were significantly correlated with lower alpha relative power, and increased theta relative power was significantly correlated with poor set-shifting abilities. No qEEG variables were significantly correlated with the procedural learning task. These correlations between deficits in specific cognitive domains and qEEG bands suggest that qEEG may have an important role in the investigation of the cognitive deficits in AD.

Aged↗