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Biomedical subjects

M C Blanco

Publications and source records attributed to M C Blanco.

14 recordsLinked to original sources
PubMed2000

Heteropolynuclear phosphide complexes: phosphorus as unique atom bridging coinage metal centres.

In this paper we describe the synthesis and reactivity of the diphenylphosphine derivatives [Au(C6F5)(PPh2H)] and trans-[Au(C6F5)2(PPh2H)2]ClO4. Reactions of the latter or the neutral [Au(C6F5)3(PPh2H)] with the appropriate Group 11 metal reagents (M = Au, Ag, Cu) in the presence of acetylacetonate afford a series of novel Au(III)-M phosphido-bridged complexes, which have been scarcely represented to date. The crystal structure of the tetranuclear [(Au(C6F5)2(mu-PPh2)2Ag)2] and the dinuclear [Au(C6F5)3(mu-PPh2)M(PPh3)] (M = Au,Ag) complexes were established by X-ray diffraction methods. The synthesis and deprotonating activity of the anionic gold(III) complex PPN[Au(C6F5)3(acac)] (PNN = [N(PPh3)2]+) was studied.

Journal Article↗
PubMed1997

Effects of aspirin or basic amino acids on collagen cross-links and complications in NIDDM.

OBJECTIVE: To determine if long-term therapy with aspirin or basic amino acids for subjects with NIDDM reduces the severity of clinical complications and/or reduces tissue levels of markers of glycooxidative damage. RESEARCH DESIGN AND METHODS: Subjects with NIDDM were administered either aspirin (100 mg/day) or a combination of basic amino acids consisting of L-arginine (2 g/day) plus L-lysine (0.5 g/day) for 1 year. The study was double-blind and placebo-controlled. The presence and severity of retinopathy, nephropathy, and neuropathy were assessed in all subjects at 4-month intervals, as were serum blood glucose, glycohemoglobin levels, and presence of albuminuria. Collagen cross-linking and collagen glycation were measured in skin collagen obtained by biopsy at the beginning and the end of the study. Skin biopsies were also obtained from age-matched control subjects. RESULTS: Skin samples obtained from NIDDM subjects at the beginning of the study had significantly increased levels of glucitolyllysine, pentosidine, and hydroxypyridinium, as compared with age-matched control subjects. Pentosidine levels were significantly correlated with severity of retinopathy and neuropathy, but not nephropathy. Subjects receiving aspirin, but not amino acids or placebo, had significantly decreased levels of skin pentosidine after 1 year of therapy. CONCLUSIONS: It is concluded that 1) low-dose aspirin may reduce glycooxidative damage in people with NIDDM, and 2) treatment may need to continue for more than 1 year before clinical status improves.

Analysis of Variance↗
PubMed1996

Interregional foodborne salmonellosis outbreak due to powdered infant formula contaminated with lactose-fermenting Salmonella virchow.

Spain's Salmonella surveillance system backed by regionally-based epidemiologists around the country made it possible to detect and halt the spread of a foodborne salmonellosis outbreak due to powdered infant formula contaminated with a lactose-fermenting strain of Salmonella virchow. Forty-eight cases involving children, mostly under 7 months old, were detected in 14 out of Spain's 17 Regions. The outbreak started in January and ended in June 1994. All cases were microbiologically confirmed. The implicated strain had a 3.6 kb plasmid, was susceptible to all antimicrobials tested except nitrofurantoin and was phagetype 4a. Isolates from 8 of 24 Brand "A" milk samples tested had the same characteristics as case isolates. All affected/suspect batches of Brand "A" milk were destroyed and the product withdrawn from sale, which led to the end of the outbreak. This incident underscores the importance of maintaining surveillance systems able to detect and prevent foodborne outbreaks and alert to the possibility of isolating unusual lactose-fermenting Salmonella serotypes in especially sensitive food products.

Animals↗
PubMed1996

Introduction of human adenomatous polyposis coli gene into Min mice via cationic liposomes.

BACKGROUND: The adenomatous polyposis coli (APC) gene is a tumor-suppressor gene involved in familial polyposis coli (FAP), a hereditary disease heralded by the development of hundreds of colorectal adenomas. A mouse model for FAP, the multiple intestinal neoplasia (Min) mouse, develops multiple adenomatous polyps of the large and small intestine similar to their human counterparts. To test the feasibility of introducing normal human APC as a means of either preventing or reversing polyp formation, we describe a method of in vivo transfection of APC into colonic epithelium of the Min mouse. METHODS: Anesthetized young (4 weeks) Min mice were treated with enemas containing lipofectant and a normal human APC cDNA plasmid every 72 hours for 2 months and then euthanized at 24, 48, and 72 hours after the last treatment. Polymerase chain reaction (PCR) was used to detect the presence of the plasmid DNA. RESULTS: PCR on the extracted colonic epithelial DNA showed the presence of plasmid DNA up to 72 hours after the last treatment. Expression of the plasmid construct was confirmed by reverse transcriptase-PCR. CONCLUSIONS: We have demonstrated the repeated introduction and detection of normal human APC in the colonic epithelium of the Min Mouse in vivo during an extended period of time with no toxic side effects by means of our prolonged therapy.

Adenoma↗
PubMed1995

Long-term supplementation of canthaxanthin does not inhibit gastric epithelial cell proliferation in Helicobacter mustelae-infected ferrets.

The effect of canthaxanthin (CX), a nonprovitamin A carotenoid, on gastric epithelial proliferation was studied in ferrets colonized with Helicobacter mustelae, which causes a chronic gastritis and an increased gastric epithelial cell proliferation. Seven spayed female ferrets were dosed by gavage with CX beadlets (50 mg/kg body wt, 5 d/wk) over 2 y, whereas seven control animals were given placebo beadlets. At the end of the 2-y-period, ferrets were killed, and gastric tissues were obtained from the antrum and body regions. A cell-proliferating biomarker, proliferating cell nuclear antigen (PCNA), was assayed by immunohistochemistry. The PCNA positivity was measured by a computer-based image analysis system. Serum concentrations of carotenoids, retinoids and tocopherols were analyzed by HPLC. Serum antioxidant status was measured by the oxygen radical absorbance capacity (ORAC) assay. The PCNA positivity in both antrum and body regions was not significantly different between CX-fed ferrets and controls. Serum CX concentrations were significantly higher in CX-fed ferrets vs. controls (P < 0.001), whereas levels of other carotenoids, retinoids and tocopherols were not significantly different. The ORAC values were not significant different between groups. This study does not suggest inhibitory effects of CX on gastric epithelial cell proliferation in H. mustelae infected ferrets.

Animals↗
PubMed1995

Supplementing ferrets with canthaxanthin affects the tissue distributions of canthaxanthin, other carotenoids, vitamin A and vitamin E.

To study the effects of canthaxanthin supplementation on the tissue distribution of canthaxanthin, other carotenoids, vitamin A and vitamin E, 26 spayed female ferrets (2 mo of age) were used. Ferrets were assigned to receive a commercial ferret diet and a gavage of canthaxanthin [50 mg/(kg body wt.d)] or a gavage of placebo beadlets (0 mg canthaxanthin) 5 d/wk. Serum canthaxanthin concentrations in the canthaxanthin-fed group increased from 0 at baseline to 37.76 +/- 5.34 nmol/L trans and 77.10 +/- 12.60 nmol/L cis canthaxanthin at 12 mo. Further accumulation of canthaxanthin did not occur with continuous dosing. After 2 y of receiving canthaxanthin beadlets by gavage, the ferrets did not show a detectable concentration of canthaxanthin in the eyes, nor did they have clinical signs of toxicity. Canthaxanthin concentrations were highest in liver, with high concentrations also seen in fat, lung and small intestine. The sum of alpha and beta-carotene concentrations detected in livers was significantly higher in the canthaxanthin-fed group than in the placebo-fed group, but not significantly higher when individual carotenes were compared. However, alpha-tocopherol concentrations in the livers and lungs and lutein/zeaxanthin in the fats of the ferrets fed canthaxanthin were significantly lower than in those fed the placebo. Retinoid concentrations in tissues of the ferrets fed canthaxanthin were not different from those of the placebo-fed group. The effects of canthaxanthin supplementation on other antioxidants and vitamin A nutrients demonstrate either a synergistic or antagonistic relationship, depending on the specific tissue assayed.

Adipose Tissue↗
PubMed1994

Megaesophagus in nine ferrets.

Megaesophagus was diagnosed in 9 adult ferrets. Clinical history of the ferrets included regurgitation, difficulty in swallowing, partial anorexia, and lethargy. Cachexia, dehydration, weakness, and ptyalism were observed on physical examination. Radiography revealed the esophagus of each ferret to be dilated in the thoracic and cervical regions. Of 4 ferrets that had lymphocytopenia, 2 had concurrent leukopenia. Serum biochemical analysis revealed high activity of alanine transaminase (4 ferrets) and aspartate transaminase (3), and hypoglycemia (4). Treatment included administration of fluid, antibiotics, and agents directed against possible primary causes of megaesophagus. Treatments were ineffective, and all of the ferrets died or were euthanatized. All 6 ferrets that were submitted for necropsy had bronchopneumonia, hepatic lipidosis, mild esophagitis, and gastritis. The etiopathogenesis of megaesophagus in the ferrets was not determined.

Animals↗
PubMed1994

High concentrations of vitamin A esters circulate primarily as retinyl stearate and are stored primarily as retinyl palmitate in ferret tissues.

OBJECTIVE AND METHODOLOGY: We determined the kinds and amounts of vitamin A compounds (retinol and various retinyl esters) circulating in serum and stored in liver and other selected tissues of ferrets, using high-performance liquid chromatography. RESULTS: The concentration of total retinyl esters in serum (43 +/- 1 mumol/L, mean +/- SEM) was 25 times greater than that of retinol (1.7 +/- 0.2 mumol/L). In serum, 56% of retinyl esters was retinyl stearate, 33% was retinyl palmitate, and 5% was retinyl oleate. In contrast, in liver, vitamin A was stored primarily as retinyl palmitate (51%); smaller amounts of retinyl oleate (19%) and retinyl stearate (16%) were found. In kidneys, adrenals, small intestine, adipose tissue, skin, stomach, and eyes, retinyl palmitate was also the predominant retinyl ester, followed by retinyl stearate. In colon, lungs, and bladder, equal amounts of retinyl palmitate and retinyl stearate were observed. Other retinyl esters present in smaller amounts in most of these tissues were retinyl oleate, retinyl linoleate and/or -myristate, retinyl heptadecanoate, retinyl arachidonate, and retinyl laurate. CONCLUSIONS: Thus, the primary form of vitamin A that circulates in the blood of ferrets is retinyl stearate, whereas the primary storage form of the vitamin in tissues is retinyl palmitate. Concentrations of total vitamin A in ferret serum and other tissues were 3-73 times greater than those reported for their corresponding human tissues.

Animals↗
PubMed1993

Role of gastric pH in isolation of Helicobacter mustelae from the feces of ferrets.

BACKGROUND: Helicobacter mustelae colonizes the gastric mucosa of ferrets and causes persistent chronic gastritis. METHODS: Hypochlorhydria, as measured by gastric pH probe, was induced by administering oral omeprazole, a proton pump inhibitor of the parietal cell, to adult ferrets in two separate experiments. Feces of ferrets were cultured for H. mustelae before, during, and after omeprazole therapy. RESULTS: H. mustelae was isolated in 23 of 55 (41.8%) sequential fecal samples collected during omeprazole therapy. The same ferrets with acidic gastric pH had H. mustelae isolated in 6 of 62 (9.7%) of the fecal cultures (P < 0.01). A DNA species-specific H. mustelae probe confirmed the presence of the organism in both the stomach and feces of all 5 ferrets. In 4 of 5 ferrets restriction enzyme patterns of the gastric H. mustelae were identical to those of the fecal H. mustelae strains. CONCLUSIONS: Hypochlorhydria promotes fecal transmission of a gastric Helicobacter organism. The H. mustelae-colonized ferret provides an ideal model to study the epidemiology and pathogenesis of Helicobacter pylori-induced gastritis.

Animals↗
PubMed1992

Beta-carotene, retinol and retinyl ester concentrations in serum and selected tissues of ferrets fed beta-carotene.

The concentrations of beta-carotene, retinol and retinyl esters in serum and selected tissues of ferrets fed diets supplemented with beta-carotene (80 micrograms/g wet diet) for 3 wk were determined. The initial concentration of serum beta-carotene was 0.011 +/- 0.006 mumol/L (mean +/- SEM); at the end of the experimental period it was 5.75 +/- 1.60 mumol/L. No significant differences in serum retinol and total retinyl esters were observed between beta-carotene-fed and control ferrets that had been fed an unsupplemented diet. The predominant retinyl esters in serum were retinyl stearate (53%) and retinyl palmitate (35%). Of the tissues analyzed after beta-carotene feeding, the liver contained the highest concentration of beta-carotene (78.8 +/- 18.8 nmol/g). Other tissues that contained beta-carotene in amounts ranging from 17 to 20 nmol/g were adrenals, small intestine, stomach and colon; lesser amounts (6.9 nmol/g) were found in kidneys. Amounts ranging from 1.2 to 2.3 nmol/g were found in muscle, bladder, adipose tissue, lungs and skin; only 0.37 and 0.34 nmol/g were present in brain and eyes, respectively. Thus, like humans, ferrets have the capacity to absorb intact beta-carotene and to store this compound in tissues, especially the liver. However, compared with humans, ferrets have elevated concentrations of retinyl esters in serum, liver and other tissues.

Absorption↗
PubMedDate not supplied

Imaging cobalt nanoparticles by amplitude modulation atomic force microscopy: comparison between low and high amplitude solutions.

In many situations of interest amplitude modulation AFM is characterized by the coexistence of two solutions with different physical properties. Here, we compare the performance of those solutions in the imaging of cobalt nanoparticles. We show that imaging with the high amplitude solution implies an irreversible deformation of the nanoparticles while repeated imaging with the low solution does not produce noticeable changes in the nanoparticles. Theoretical simulations show that the maximum tip-surface force in the high amplitude solution is about 14nN while in the low amplitude solution is about -4nN. We attribute the differences in the high and low amplitude images to the differences in the exerted forces on the sample.

Journal Article↗