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Biomedical subjects

R Villalobos

Publications and source records attributed to R Villalobos.

At least 19 recordsLinked to original sources
PubMed2003

Defective expression of FasL and Bax in human lung cancer.

The present studies investigated whether FasL and Bax genes are expressed in pleuro-pulmonary biopsies from patients with lung cancer. FasL, Bax, and TNFalpha mRNAs were detected in 19 biopsies of primary or metastasic lung cancer by fluorescent in situ hybridization assays. Fluorescent probes were produced by polymerase chain reaction using a human spleen lambda gt11 library and specific primers for FasL, Bax, and TNFalpha. Proteins were detected by immunohistochemistry using monoclonal anti- FasL, anti-Bax, and anti-TNFalpha antibodies. Chromatin fragmentation was detected by TUNEL. Seven negative samples from subjects without lung pathology were obtained during legal autopsies and 12 positive control biopsies from patients with lung infections were also included. Sixty-eight percent of lung cancer biopsies exhibited FasL; Bax was expressed in 68% and TNFalpha in 63%. FasL protein was detected in 21%, Bax protein in 26%, and TNFalpha was present in 31% of cancer biopsies. A low degree of apoptosis in lung cancer was demonstrated by TUNEL assays. A defect in FasL, Bax, and TNFalpha gene expression was found in lung cancer biopsies. Some tumors normally expressed the mRNA of FasL, Bax, or TNFalpha, but their proteins were absent, or were non-functional, since TUNEL assays were negative. Such a failure would contribute to cancer cell survival and dissemination.

Adult↗
PubMed2002

Evaluation of coeliac disease serological markers in Down syndrome patients.

BACKGROUND: The increased incidence of coeliac disease in patients with Down syndrome makes screening of coeliac disease in this population advisable. AIM: Evaluation of efficiency of different serological markers to detect coeliac disease in Down syndrome patients. PATIENTS: A total of 56 Down syndrome patients (aged: 1-17 years) were included in study. METHODS: Patients were evaluated for both IgG and IgA anti-transglutaminase antibodies and for anti-gliadin IgA and IgG antibodies using either purified omega-gliadin, wheat ethanol extract or commercial gliadin. Patients who had at least one positive result were evaluated for antiendomysium antibodies using either monkey oesophagus or human umbilical cord by indirect immunofluorescence. Coeliac disease was diagnosed by typical histological changes on duodenal mucosa. RESULTS: Increased levels of at least one anti-gliadin IgA and IgG antibody marker were found in 27 out of 56 cases (26 for IgG and 9 for IgA). 11/56 were positive for IgG anti-transglutaminase antibodies and two of them were also positive for IgA anti-transglutaminase antibodies and anti-endomysium antibodies. These two patients were finally diagnosed as coeliacs. Gliadin antigenic fractions employed produced differences in the performance of the anti-gliadin IgA and IgG antibody test. The use of commercial gliadin or wheat ethanol extract showed low sensitivity in IgA anti-gliadin IgA and IgG antibody determination, whereas good sensitivity and specificity were observed with omega-gliadins. IgG anti-transglutaminase antibodies showed a high proportion of false positive results (9 out of 56), whereas anti-endomysium antibodies and IgA anti-transglutaminase antibodies presented an excellent correlation with presence of active coeliac disease. CONCLUSIONS: Two out of 56 Down syndrome patients were diagnosed as coeliacs, corresponding to an incidence of 3.6%. The use of omega-gliadin presented the best efficiency in anti-gliadin IgA and IgG antibody determination whereas IgA anti-transglutaminase antibodies and anti-endomysium antibody determination showed an absolute correlation with presence of active coeliac disease.

Adolescent↗
PubMed2001

TNFalpha and IL-6 are mediators in the blistering process of pemphigus.

BACKGROUND: Pemphigus is an autoimmune disease characterized by intraepidermal blisters induced by pemphigus IgG. In addition to autoantibodies, molecular mechanisms involved in acantholysis remain largely unknown. For this reason, we address a possible role of the inflammatory cytokines IL-6 and TNFalpha in pemphigus lesions. METHODS: Sixteen biopsies from patients with different types of pemphigus were studied by in situ hybridization using DNA fluorescent probes for IL-6 and TNFalpha mRNA. RESULTS: Fifty-six percent of lesional biopsies exhibited cytokine gene expression, which was poorly expressed in noninvolved skin. Deposits of TNFalpha and IL-6 were products of in situ transcription at the epidermal level. CONCLUSIONS: Inflammatory cytokine expression around the blister could play a mediator role in pemphigus lesions by increasing epithelial damage.

Biopsy↗
PubMed1999

Opioid peptide systems following a subconvulsant dose of pentylenetetrazol in rats.

The development of epilepsy and a progressive increase in susceptibility to seizures may involve changes in inhibitory and excitatory systems from the beginning of the process. The present study was focused to analyze the opioid peptide changes induced by a chemical sub-convulsant stimulation. Experiments were carried out to determine opioid peptide release, mu receptor binding and proenkephalin expression in rat brain, as well as nociceptive responses, following the administration of a sub-convulsant dose of pentylenetetrazol (PTZ) (30 mg/kg, i.p.). Membrane binding experiments revealed reduced number of mu binding sites (Bmax) in cortex and amygdala, but not in striatum and hippocampus, an effect that was evident only 24 h, but not 28 days, after PTZ treatment. In situ hybridization experiments suggested a significant enhancement of proenkephalin mRNA expression in specific brain regions 24 h after PTZ treatment. Microdialysis combined with a universal opioid peptide radioimmunoassay revealed extracellular opioid peptide levels to be elevated in the amygdala (137%) 90 min after PTZ administration. Evaluation of nociceptive responses using the Randall-Selitto test showed an analgesic effect short term (30-90 min) after PTZ injection. Collectively, these data provide evidence for a significant activation of opioid peptide systems as a consequence of the administration of a sub-convulsant dose of PTZ. These neurochemical changes may play an important role in the progression of epileptogenesis.

Animals↗
PubMed1998

Similar brain SPECT findings in subclinical and clinical seizures in two neonates with hemimegalencephaly.

Brain single-photon emission computed tomography (SPECT) findings during clinical and subclinical seizures were compared in two neonates with hemimegalencephaly. Interictal and ictal brain SPECT were performed in two neonates. The ictal studies were performed during a clinical seizure in one neonate and during a subclinical seizure in another neonate. They revealed similar focal hemispheric hyperperfusion at the electroencephalographic seizure foci in both cases. The similar perfusion patterns imply that clinical and subclinical seizures place similar metabolic demands on the cerebral tissue involved in the generation of electroencephalographic seizures in neonates with cerebral dysgenesis and suggest that clinical and subclinical seizures should be treated similarly in this population.

Brain↗
PubMed1991

Serum ferritin deficiency in Huntington's disease patients.

This study was designed to investigate serum levels of iron, ferritin, vitamin B12 and folic acid in 18 Huntington's disease patients and 86 healthy control subjects. Serum iron, vitamin B12 and folic acid levels were normal. Ferritin concentrations were significantly diminished in the choreic patients. The importance of this finding in our attempt to understand the underlying biochemical defect and the chemical nature of the iron deposits found in several brain nuclei in Huntington's disease patients is unknown.

Adolescent↗
PubMed1990

The macular photostress test in diabetic retinopathy and age-related macular degeneration.

We propose the macular photostress test for the evaluation of macular function in the office setting. Eighty eyes were tested and divided into four diagnostic categories: background diabetic retinopathy, diabetic macular edema, age-related macular degeneration, and normal. The recovery times for the eyes with age-related macular degeneration were longer than for eyes with macular edema (P = .03). Age-matched patients with age-related macular degeneration had longer recovery times than did those without age-related macular degeneration (P = .0001). A possible explanation is that the prolonged recovery time in the eyes with age-related macular degeneration reflects that the anatomic lesion is located in the retinal pigment epithelium-photoreceptor complex. In comparison, the eyes with macular edema, whose lesion is in the inner retina and not the retinal pigment epithelium, show a less-prolonged recovery time than the eyes with age-related macular degeneration.

Adolescent↗
PubMed1990

Systemic group B streptococcal disease in the neonate: characterization of an oral colonization model using the suckling rat.

Aspiration or ingestion of contaminated amniotic fluid or vaginal secretions has been suggested as a cause of systemic group B streptococcal (GBS) infection in the neonate. Suckling rat studies disagree on whether systemic disease will develop after an oral challenge of GBS. Our goal was to determine if systemic GBS disease would occur following oral colonization in the suckling rat and the effect of bacterial, host and environmental factors. Suckling rat littermates received oral inoculation on one of the first four days of life with varying doses and strains of GBS. Studies confirmed gastric inoculation without aspiration. Mortality and bacteremia decreased with age, increased with dose, varied with strain, and increased with asphyxia. Autopsy confirmed sepsis, intestinal colonization, meningitis, and pneumonia. Bacteremia was associated with an abnormal immature: total neutrophil ratio at 24 hr, thrombocytopenia at 48 hr, and neutropenia at 72 hr after inoculation. GBS can cause systemic infection in the host after oral colonization which appears age-, dose, strain-, and environment-dependent. Evaluation of GBS entry in the susceptible host may facilitate therapies directed toward preventing mucosal invasion.

Administration, Oral↗
PubMed1990

[Prevalence of Entamoeba histolytica and other intestinal parasites in a neighborhood of the Mara Municipality, Zulia State, Venezuela].

A parasitologic survey of a low socioeconomic level community from Mara County, Zulia State, Venezuela was done. A single stool specimen per person from 327 individuals was obtained and examined by hematoxylin stained fecal smears and formol-ether concentrates. The overall parasitic infection rate was 92%. Multiple infections were present in 89% of the population. The amebic prevalence rate (APR) was 41.5%. Entamoeba histolytica was found in 9.2% of the individuals, most of them being asymptomatic. Haematophagous trophozoites were observed in two symptomatic cases. Entamoeba coli was the most frequent protozoan (23.5%). The APR was high in all groups. In males it was higher in 7-12 year old children and adolescents, and in females it was higher in adults. Giardia lamblia was the most frequent flagellate (18%) and among the helminths, Trichuris trichiura (82.8%) and Ascaris lumbricoides (74.6%). The high rates of parasitic infection, multiple parasitosis and amebic prevalence reflect the low socioeconomic conditions in the population.

Adolescent↗
PubMed1989

Nutritional evaluation of Huntington disease patients.

A nutritional survey and evaluation was made in Huntington disease patients by the 24-h-recall method. Control subjects and choreic patients consumed a diet that supplied all the essential amino acids. The diet was hypocaloric, rich in animal protein, and low in fat and carbohydrates. The ratio of calcium to phosphorus in the groups studied was less than 1. High vitamin A and low vitamin C and niacin intakes were observed in Huntington disease patients. Only 17% of control subjects showed weight deficiency; 55% of the patients at stages III and IV of the disease were malnourished despite receiving the same food intake as controls. Although iron intake was deficient in all groups studied, it was enough to maintain normal serum levels of this metal. The deficiencies found in some nutrients do not explain the clinical manifestations observed in Huntington disease patients.

Adolescent↗
PubMed1986

Lactogenic response of cultured mouse mammary epithelial cells to mouse placental lactogen.

The ability of mouse placental lactogen (mPL), mouse prolactin (mPRL), mouse GH (mGH) and ovine prolactin (oPRL) to stimulate synthesis of alpha-lactalbumin was tested in a primary culture of mouse mammary gland epithelial cells. Mammary tissue was obtained from 10-day pregnant Swiss Webster mice, enzymatically dissociated and the cells were cultured on floating collagen gels for 5 days. The basic culture medium consisted of Nutrient Mixture F12/Dulbecco's Modified Eagle's Medium (1:1, v/v), containing 10 mg insulin/1, 5 mg cortisol/l, 10 micrograms epidermal growth factor/l, 5 g bovine serum albumin/l and 50 mg gentamycin/l. Mouse PL, mPRL, mGH and oPRL were added to the basic medium in concentrations from 1 microgram/l to 1 mg/l. Accumulation of alpha-lactalbumin in the culture medium was measured. For that purpose, mouse alpha-lactalbumin was purified from mammary tissue obtained from lactating Swiss Webster mice and a radioimmunoassay was developed. Mouse PL, mPRL and oPRL stimulated a dose-dependent increase in alpha-lactalbumin secretion. Mouse GH also caused a significant, but dose-independent, increase in alpha-lactalbumin secretion. Mouse PL showed the greatest activity in stimulating alpha-lactalbumin secretion. It was concluded that mPL is an important lactogenic hormone in the latter half of pregnancy in the mouse, when circulating mPRL concentrations are low.

Animals↗
PubMed1984

Copper distribution in the normal human brain.

Copper concentration was determined in samples from 38 areas of 7 normal human brains. The grey matter contained higher concentrations of copper than the white matter. Identical areas of the grey and white matter of the cerebral cortex showed significant differences between individuals. In the caudate nucleus the highest concentrations of copper were found in the tail followed by the body and the head, respectively. A negative linear regression between age and brain copper levels was demonstrated.

Adolescent↗