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Biomedical subjects

I Blanco

Publications and source records attributed to I Blanco.

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

Higher colon cancer tumor proliferative index and lower tumor cell death rate in mice undergoing laparotomy versus insufflation.

BACKGROUND: Our laboratory has previously shown that tumors are established more easily and grow larger after laparotomy than after laparoscopy. To characterize these differences in tumor growth further, the tumor cell death rates and tumor proliferation rates were compared in vivo after full sham laparotomy versus carbon dioxide (CO2) insufflation. METHODS: Female Balb/C mice (n = 36) were inoculated intradermally in the dorsal skin with 106 C-26 colon adenocarcinoma cells in 0.1 ml of culture media no more than 1 h before interventions. The mice then were randomized to one of three groups: anesthesia control, CO2 insufflation, or sham laparotomy. The anesthesia control group underwent no procedure. The insufflation group underwent CO2 pneumoperitoneum (4-6 mmHg) for 20 min via a 20-gauge angiocatheter. The laparotomy group underwent a midline incision from xiphoid to pubis, which was closed after 20 min. Tumors were excised from half the mice in each group on postoperative day 7, and from the remaining mice on postoperative day 14. Sections of tumors were made then stained separately for free 3? hydroxyl ends of genomic deoxyribonucleic acid (DNA) using fluorescein-deoxyunidine triphosphate (dUTP), and immunohistochemically for proliferating cell nuclear antigen (PCNA). Apoptosis was measured by quantitating DNA strand breaks in individual cells using fluorescence microscopy. Fluorescein-positive cells in five random high-power fields (x200) were counted in a blinded fashion. The proliferative index of each tumor was determined by averaging PCNA positive cells in five high-power fields (x450) counted in a blinded fashion with the aid of an optical grid. RESULTS: On postoperative day 7, there was no significant difference in the proliferative index or apoptotic rates among the three groups. On postoperative day 14, the proliferative index in the laparotomy group was significantly higher than in either the insufflation or control group (p < 0.001). The proliferative index in the insufflation group also was significantly higher than in the control group (p < 0.05). Inverse differences in apoptotic rates were found. The apoptotic rate in the laparotomy group was significantly lower than in either the insufflation (p < 0.05) or control group (p < 0.001). The apoptotic rate in the insufflation group was significantly lower than in the control group (p < 0.001). CONCLUSIONS: We have demonstrated that there is a significantly higher rate of tumor cell proliferation and a significantly lower rate of tumor cell death with the C-26 colon adenocarcinoma tumor line after laparotomy than after insufflation or anesthesia alone on post-operative day 14. The mechanisms of these phenomena are unclear. It appears that certain factors postoperatively stimulate tumors to proliferate at a higher rate, causing tumor cells to die at a lower rate in the laparotomy group than in the insufflation group.

Adenocarcinoma↗
PubMed2001

Percutaneous endocardial transfer and expression of genes to the myocardium utilizing fluoroscopic guidance.

Experimental studies indicate that administration of angiogenic proteins or genes by the epicardial or intracoronary route can stimulate development of new collateral vessels and improve myocardial perfusion. An endocardial catheter-based approach to this therapy would obviate the need for surgery, while preserving the effectiveness of direct intramyocardial administration. Fluoroscopic guidance and prototype, preformed, coaxial catheters were used to examine the feasibility of percutaneous catheter-based adenovirus (Ad)-mediated gene transfer and expression in normal swine myocardium. The feasibility of intramyocardial administration (100 microl/injection) of a radiocontrast agent and black tissue dye to all regions of the left ventricle (septum, anterior, lateral, and inferior wall) was confirmed fluoroscopically and on postmortem examination. Injections of replication-deficient adenovirus (10 injections of 10(11) particle units/100 microl each) coding for beta-galactosidase (Adbetagal) or vascular endothelial growth factor (Ad(GV)VEGF121.10) were administered to the left ventricular free wall to examine endocardial based gene transfer and expression. beta-Galactosidase activity was detected by histochemical staining and quantitative assay in targeted regions of the myocardium. Regional VEGF expression was found to be significantly greater in targeted regions (1.3 +/- 0.4 ng/mg protein) as compared with non-targeted regions (0.3 +/- 0.1 ng/mg protein) or regions injected with control (Adbetagal) virus (0.2 +/- 0.03 ng/mg protein, P < 0.001). Catheter-based Ad mediated endocardial gene transfer and expression is feasible using percutaneous, fluoroscopically guided, preformed, coaxial catheters. This approach should be clinically useful to administer angiogenic genes to the ischemic myocardium.

Adenoviridae↗
PubMed2001

Alpha-1-antitrypsin PI phenotypes S and Z in Europe: an analysis of the published surveys.

The objective of the present study was to review published surveys on allelic frequencies S and Z in European populations to evaluate the validity of the reported data. More than a hundred studies on the topic, published since 1965 until 2000, were retrieved by Medline, Index Medicus and bibliographic references consultation. The criteria for studies selection were: 1) sample size> or =250 individuals; 2) alpha-1-antitrypsin phenotype determination performed by means of crossed antigen-antibody or isoelectric focusing in polyacrylamide gels; 3) PI type determination performed without any previous screening procedure; 4) S and Z 95% confidence interval (CI) of the reported outcomes with a calculated coefficient of variation <42.3 for S and <95.8 for Z; 5) S and Z 95% CI of the reported outcomes comprised within 95% CI limits of comparative hypothetical surveys designed with the same sample size of the questioned surveys and the highest/lowest frequencies accepted for a specific area, according to the figures of isogen boundary maps. Seventy studies comply with the five established criteria for analysis. According to the data of the selected studies, a geographical distribution on S and Z gene frequencies in Europe is proposed.

Alleles↗
PubMed2001

Distribution of alpha1-antitrypsin PI S and PI Z frequencies in countries outside Europe: a meta-analysis.

The objective of the present study was to review published surveys on allelic frequencies S and Z in countries outside Europe to evaluate the validity of the reported data. Studies on the topic, published from 1965 to May 2001, were retrieved using MEDLINE and bibliographic reference consultations. The criteria for the selection of the studies were the following: 1) sample size >or=250 individuals; 2) alpha1-antitrypsin phenotype determination performed by means of crossed antigen-antibody, isoelectric focusing in polyacrylamide gels, or polymerase chain reaction (PCR); 3) PI type determination performed without any previous screening procedure; 4) S and Z 95% CI of the reported outcomes within the limits of a calculated coefficient of variation. Forty-three out of 85 studies comply with the established criteria for being analysed. Worldwide maps of geographical distributions of PI S and PI Z frequencies have been designed by the authors by adding the data provided by these 43 selected studies to the 70 reported in a recent European meta-analysis.

Afghanistan↗
PubMed2001

A clinical case of canine mycotic pneumonia.

A bronchopneumonic process diagnosed as mycotic in origin is described. The dog fully recovered after 120 days of treatment with ketoconazole. Determination of the serological level of anti-IgG against Aspergillus was very useful in the follow-up, because the clinical improvement of the animal was evident long before the antibody level dropped significantly.

Animals↗
PubMed2001

Alpha1-antitrypsin Pi phenotypes S and Z in Spain: an analysis of the published surveys.

The aim of the present study was to review published surveys on allelic frequencies S and Z in Spanish populations to evaluate the validity of the reported data. Thirty-four studies published since 1965 were retrieved by MEDLINE, Index Medicus and consultations with experts. The criteria for studies selection were (i) sample size > or = 250 individuals; (ii) alpha-1-antitrypsin phenotyping determination performed by means of crossed antigen-antibody electrophoresis or isoelectrofocusing; (iii) S and Z reported outcomes with an upper 95% CI smaller than mean + 2 SD, a lower 95% CI smaller than mean - 2 SD, and the following ratio: 100 x (95%CI upper limit - 95%CI lower limit)/allelic frequency, for both S and Z, included in the mean +/- 2 SD interval. Thirteen out of 34 surveys retrieved complied with the proposed criteria for S gene frequency analysis and 11 fulfilled the criteria for Z. The greatest frequency for S type is in the north-west of the country (149 alleles per 1000 in Galicians natives), while frequencies in the rest of the country are approximately 100 alleles per 1000. The greatest frequency for Z type has been reported in newborn infants from Valladolid (20.8) and in a randomly selected general population of Asturias (19.7). In the rest of Spain, Z frequencies range from 1.5 to 15 alleles per 1000 genes.

Confidence Intervals↗
PubMed2001

Serum concentrations of carotenoids and vitamins A, E, and C in control subjects from five European countries.

High intakes of fruits and vegetables, or high circulating levels of their biomarkers (carotenoids, vitamins C and E), have been associated with a relatively low incidence of cardiovascular disease, cataract and cancer. Exposure to a high fruit and vegetable diet increases antioxidant concentrations in blood and body tissues, and potentially protects against oxidative damage to cells and tissues. This paper describes blood concentrations of carotenoids, tocopherols, ascorbic acid and retinol in well-defined groups of healthy, non-smokers, aged 25-45 years, 175 men and 174 women from five European countries (France, UK (Northern Ireland), Republic of Ireland, The Netherlands and Spain). Analysis was centralised and performed within 18 months. Within-gender, vitamin C showed no significant differences between centres. Females in France, Republic of Ireland and Spain had significantly higher plasma vitamin C concentrations than their male counterparts. Serum retinol and alpha-tocopherol levels were similar between centres, but gamma-tocopherol showed a great variability being the lowest in Spain and France, and the highest in The Netherlands. The provitamin A: non-provitamin A carotenoid ratio was similar among countries, whereas the xanthophylls (lutein, zeaxanthin, beta-cryptoxanthin) to carotenes (alpha-carotene, beta-carotene, lycopene) ratio was double in southern (Spain) compared to the northern areas (Northern Ireland and Republic of Ireland). Serum concentrations of lutein and zeaxanthin were highest in France and Spain; beta-cryptoxanthin was highest in Spain and The Netherlands; trans-lycopene tended to be highest in Irish males and lowest in Spanish males; alpha-carotene and beta-carotene were higher in the French volunteers. Due to the study design, the concentrations of carotenoids and vitamins A, C and E represent physiological ranges achievable by dietary means and may be considered as 'reference values' in serum of healthy, non-smoking middle-aged subjects from five European countries. The results suggest that lutein (and zeaxanthin), beta-cryptoxanthin, total xanthophylls and gamma-tocopherol (and alpha- : gamma-tocopherol) may be important markers related to the healthy or protective effects of the Mediterranean-like diet.

Adult↗
PubMed2001

A European carotenoid database to assess carotenoid intakes and its use in a five-country comparative study.

A food frequency questionnaire (FFQ) and carotenoid database with information on alpha- and beta-carotene, lutein, lycopene and beta-cryptoxanthin was prepared and used to compare the carotenoid intakes in five European countries: UK, Republic of Ireland, Spain, France and The Netherlands. Eighty, age- (25-45 years) and sex-matched volunteers were recruited in each of the five countries. A FFQ and carotenoid database was prepared of the most commonly consumed carotenoid rich foods in the participating countries and the information was used to calculate frequency and intake of carotenoid-rich foods. The median total carotenoid intake based on the sum of the five carotenoids, was significantly higher (P < 0.05) in France (16.1 mg/day) and lower in Spain (9.5 mg/day,) than the other countries, where the average intake was approximately 14 mg/day. Comparison of dietary source of carotenoids showed that carrots were the major source of beta-carotene in all countries except Spain where spinach was most important. Likewise, carrots were also the main source of alpha-carotene. Tomato or tomato products, were the major source of lycopene. Lutein was mainly obtained from peas in Republic of Ireland and the UK, however, spinach was found to be the major source in other countries. In all countries, beta-cryptoxanthin was primarily obtained from citrus fruit. Comparing the data with that from specific European country studies suggests that the FFQ and carotenoid database described in the present paper can be used for comparative dietary intake studies within Europe. The results show that within Europe there are differences in the specific intake of some carotenoids which are related to different foods consumed by people in different countries.

Adult↗
PubMed2000

Quantitative radioisotopic determination of histidine decarboxylase using high-performance liquid chromatography.

We have developed a procedure for the accurate measurement of histidine decarboxylase in tissues expressing low levels of enzymatic activity. Briefly, histamine is enzymatically synthesized from [3H]-labeled histidine, followed by purification using high-performance liquid chromatography (HPLC) and quantitation by liquid scintillation counting. This method presents three advantages over previous techniques. First, prior to HPLC purification, excess precursor [3H]histidine is removed on an anion-exchange resin. Second, purification by HPLC is considerably more selective than that of classical cation-exchange gravity columns or organic solvent extractions. Finally, the accuracy of this method is improved by including non-radiolabeled histamine as internal standard, which is quantified by ultraviolet detection. This simple procedure allows highly sensitive and accurate determinations of histamine synthesis.

Animals↗
PubMed2000

A serum-soluble factor(s) stimulates tumor growth following laparotomy in a murine model.

BACKGROUND: Our laboratory and others have previously demonstrated that tumors grow larger and are more easily established following laparotomy than after CO(2) pneumoperitoneum. The etiology of increased tumor growth after surgery is unknown. We hypothesized that, following laparotomy, a serum soluble factor(s) is generated that causes tumors to proliferate more rapidly. The purpose of the current study was to determine if in vitro tumor cells proliferate faster when incubated with serum from laparotomized mice than cells incubated with sera from mice who have undergone CO(2) pneumoperitoneum or anesthesia alone. METHODS: In the first experiment, female Balb/C mice (n = 84) were randomly divided into the following three groups: (a) control (AC), (b) CO(2) insufflation (INS), and (c) laparotomy (OPEN). The AC mice underwent no procedure. The INS group underwent CO(2) pneumoperitoneum at 4-6 mmHg for 20 min. The OPEN group had a midline incision from xiphoid to pubis. The serum of seven mice from each group were collected on postoperative days (POD) 1, 2, 4, and 7 via a cardiac puncture. The sera at each time point for each group were pooled. Twenty thousand C-26 colon cancer cells were incubated separately in growth media containing 10% mouse serum from each group (seven determinations/group) at each time point. In the second experiment, female Balb/C (n = 30) mice were divided into AC and OPEN groups. On POD4, sera were collected and pooled. Three separate studies were performed for the second experiment. In the first study, tumor cells were incubated with 10% AC sera or varying concentrations of OPEN mice sera (4-10%). In the second study, aliquots of sera from the OPEN group mice were then heated at 100 degrees C for 1 or 5 min. Tumors were then incubated separately in media with 10% AC, OPEN, or heated OPEN group sera. In the third study, aliquots of sera from the OPEN group mice were dialyzed against PBS through a 3.5-kD or an 8-kD dialysis membrane tubing for 24 h. Tumors were then incubated separately in media with 10% AC, OPEN, or dialyzed OPEN group sera. For both experiments, tumor proliferation was determined and compared between groups after 72 h of incubation. RESULTS: Tumor cells incubated with POD2 and POD4 sera from OPEN group mice proliferated twice as fast as those incubated with sera from either AC or INS group mice. The difference in proliferation was maximal on POD4 and started to decline by POD7. Proliferative activity from the OPEN group sera decreased significantly when heated for 1 min and was completely ablated after 5 min of heating. Proliferative activity from the OPEN group sera was completely ablated after dialysis. CONCLUSIONS: We conclude that there is a serum-soluble factor(s) present postoperatively that stimulates tumors to grow significantly faster after laparotomy. The mitogenic effect of laparotomized mice sera is dilutable. It is uncertain whether the factor is heat labile, since heating most likely destroys other necessary proteins in the sera. The size of the factor is undeterminable using the dialysis method. Further efforts to identify these factors are currently underway.

Animals↗
PubMed2000

Optimum incubation conditions for the isolation of yeasts from canine otitis externa.

Samples from otitis externa in the dog were cultured on a variety of media under different conditions of incubation in order to assess the most suitable conditions, especially for the isolation of Malassezia pachydermatis. Columbia blood and MacConkey agar at 37 degrees C for 24 h with air and Sabouraud glucose agar under microaerophilic conditions for 48 h at 37 degrees C were considered the ideal combination.

Animals↗
PubMed2000

Polyamine uptake in cultured astrocytes: characterization and modulation by protein kinases.

The properties and regulation of the polyamine transport system in brain are still poorly understood. The present study shows, for the first time, the existence of a polyamine transport system in cerebellar astrocytes and suggests that polyamine uptake is mediated by a single and saturable high-affinity transport system for putrescine, spermine, and spermidine (K:(m) = 3.2, 1.2, and 1.8 microM:, respectively). Although substitution of NaCl by choline chloride produced a decrease in the putrescine, spermine, and spermidine uptake, it seems that polyamine transport in cerebellar astrocytes is not mediated by an Na(+) cotransport as in the presence of Na(+) and cholinium, polyamine uptake was much lower than when measured in a sucrose-based medium. On the other hand, ouabain, gramicidin (a Na(+) ionophore), and ionomycin (a Ca(2+) ionophore) produced a strong inhibition of polyamine uptake, suggesting that membrane potential could have an important role in the functioning of the astroglial polyamine uptake system. Moreover, protein kinase C inhibition produced an enhancement of polyamine uptake, whereas stimulation of protein kinase C with phorbol esters inhibited polyamine uptake. Alternatively, the tyrosine kinase inhibitor genistein caused a marked reduction in the uptake. No effects on polyamine uptake were observed with inhibitors and activators of cyclic AMP-dependent protein kinase or when Ca(2+)/calmodulin-dependent protein kinase II was inhibited with KN-62. These results suggest that the polyamine uptake system in cerebellar astrocytes could be modulated by protein kinase C and tyrosine kinase activities.

Animals↗
PubMed1999

[Allelic frequency of the gene of alpha-1-antitrypsin in the general population in a county in Asturias].

BACKGROUND: Severe alpha-1-antitrypsin (ATT) deficiency is an inherited disorder associated with a high risk of developing pulmonary emphysema and several liver diseases. Over 90 different variants of gene which expresses AAT have been described. The commonest defective variants are Z and S. Determination of gene frequencies of abnormal variants is important to estimate the number of subjects at risk of suffering from diseases related with severe AAT deficiency in any given population. POPULATION AND METHODS: In randomly selected general population, we determined the Pi phenotype to 1,116 subjects enrolled in the municipal population register from the high and middle Nalon basins. Mean age of the collective (male, 45%; female, 55%) was 46.2 (SD 29.9) years (range 4-91). AAT serum levels were determined by immunonephelometry. Pi phenotypes were determined by isoelectrofocusing in polyacrilamide gel. RESULTS: The phenotypes found were: PiMM, 857 subjects (22.5%); PiMS, 202 (18.1%); PiMZ, 31 (2.8%); PiSZ, 13 (1.2%); PiZZ, 0 (0.0%); PiMF, 5 (0.4%); Piss, 4 (0.4%); PiMN, 2 (0.2%); PiMB, 1 (0.08%); and PiMV, 1 (0.08%). The allelic frequencies were: PiM, 87.6%; PiS, 9.99%; PiZ, 1.97%; PiF, 0.2%; PiN, 0.09%; PiB, = 0.04%, and PiV, 0.04%. Therefore, the ZZ homozygote prevalence is 1 in 2,557, according to the Hardy-Weinberg principle. AAT serum levels (mg/dl) were: PiMM 147.7 (29.9) (89-296); PiMS 123.8 (22.5) (range 76-222); PiMZ 93.9 (18) (60-146); PiSS 107.5 (14.5) (87-121) and PiSZ 71.2 (12.6) (55-94). CONCLUSIONS: The frequency of Z allele in the analyzed population (19.7 per 1000) is one of the highest in Europe, and in the world. The allelic frequency of S allele (99.9 per 1000) is similar to others found in several regions in the Iberian Peninsula.

Adolescent↗
PubMed1999

Delayed-type hypersensitivity response is better preserved in mice following insufflation than after laparotomy.

BACKGROUND: Our laboratory has previously used pig and rat models to demonstrate that delayed-type hypersensitivity (DTH) response to an antigen challenge is suppressed following laparotomy compared to insufflation. The purpose of this study was to develop a practical and reliable mouse DTH model that could be used in future studies to test immunomodulating drugs and therapies. METHODS: Female C3H/HeN mice (n = 100) were given three serial DTH challenges of 25 microl of 4 mg/ml phytohemagglutinin (PHA) 12 days before the test procedure, immediately following the test procedure, and on the 2nd postoperative day. All challenges were administered via subcutaneous injection in alternating footpads. The thickness of the footpad was determined with electronic calipers immediately prior to injection and 24 h following injection in a blinded fashion. The difference in thickness represents the response. On the day of the procedure, mice were randomized into the following three groups: (a) control (AC), (b) insufflation (INS), and (c) open (OPEN). AC mice underwent no procedure. INS mice underwent CO(2) insufflation at 2-4 mmHg for 20 min. OPEN mice underwent a midline incision from xiphoid to pubis that was closed after 20 min. Data were analyzed using ANOVA and Tukey-Kramer tests to determine differences between groups. RESULTS: Preoperatively, there were no significant differences among the three groups. On POD1, the OPEN group had significantly less response than both the AC and INS groups. On POD3, there were significant differences between the OPEN group and both the INS and AC groups. There was no significant difference between the AC and INS group at any time. CONCLUSIONS: In conclusion, a DTH mouse model has been established that allows serial assessment of cell-mediated immune function. This model can be used to study immune function after open and minimal access procedures in a simple and cost-effective manner.

Animals↗
PubMed1999

Renal function in compensated hepatic cirrhosis: effects of an amino acid infusion and relationship with nitric acid.

AIMS: In order to assess the possible participation of nitric oxide (NO) in renal function during compensated hepatic cirrhosis, we studied renal function, the plasma and urinary levels of cGMP and the concentration of nitrates and nitrites, as markers of NO synthesis in blood and urine, in 10 patients with Child A hepatic cirrhosis as compared with 10 control subjects, both under basal conditions and during stimulation (amino acid-induced glomerular hyperfiltration). METHODS: To study renal function, the glomerular filtration rate (GFR), effective renal plasma flow (ERPF), renal functional reserve (RFR), renal venous resistance (RVR) and the filtration fraction (FF) were measured. Renin and aldosterone levels were determined to assess the possible involvement of these compounds in the renin-angiotensin-aldosterone axis. RESULTS: GFR and ERPF were significantly lower in the patients with cirrhosis than in the controls (mean GFR: 82+/-12.3 vs. 105+/-15 ml/min, p = 0. 01; ERPF 452+/-86 vs. 543+/-56 ml/min, p = 0.002). The RFR value was similar in both groups. In the basal situation cGMP levels were higher in plasma and urine in patients with cirrhosis than in the controls (plasma cGMP in cirrhosis 8.4+/-2.4 vs. 4.2+/-3.5 pmol/ml; urine cGMP in cirrhosis 1.2+/-2.1 vs. 0.68+/-0.1 pmol/ml). The NO levels were also higher in plasma and urine in patients with cirrhosis vs. controls (plasma NO in cirrhosis 45.5+/-9.2 vs. 30. 3+/-1.2 micromol/l; urinary NO in cirrhosis 6.2+/-1.3 vs. 3.1+/-2.3 micromol/ml). In both groups the amino acid perfusion increased GFR, ERPF, cGMP and NO levels in plasma and urine. In the patients with cirrhosis the RVR decreased significantly during perfusion and no noteworthy changes in FF were observed. The GFR values observed during amino acid perfusion were similar in patients with cirrhosis and portal hypertension to those observed in the controls (27.2+/-12 vs. 25.3+/-16%). However, the changes induced the ERPF were more marked in patients with cirrhosis (cirrhosis 35.3+/-15 vs. 22. 2+/-13%, p = 0.02). CONCLUSIONS: The present findings point to certain alterations in renal function in patients with hepatic cirrhosis and portal hypertension without ascitis, a clear difference being visible between the ERPF and GFR following amino acid-induced stimulation. The significant elevation in cGMP and NO levels in plasma and urine implies a maintained vasodilatory action that may at least partly compensate the vasoconstrictor effects of angiotensin II.

Adult↗
PubMed1999

High glycemic index foods, overeating, and obesity.

OBJECTIVE: The prevalence of obesity has increased dramatically in recent years. However, the role of dietary composition in body weight regulation remains unclear. The purpose of this work was to investigate the acute effects of dietary glycemic index (GI) on energy metabolism and voluntary food intake in obese subjects. METHODS: Twelve obese teenage boys were evaluated on three separate occasions using a crossover study protocol. During each evaluation, subjects consumed identical test meals at breakfast and lunch that had a low, medium, or high GI. The high- and medium-GI meals were designed to have similar macronutrient composition, fiber content, and palatability, and all meals for each subject had equal energy content. After breakfast, plasma and serum concentrations of metabolic fuels and hormones were measured. Ad libitum food intake was determined in the 5-hour period after lunch. RESULTS: Voluntary energy intake after the high-GI meal (5.8 megajoule [mJ]) was 53% greater than after the medium-GI meal (3.8 mJ), and 81% greater than after the low-GI meal (3.2 mJ). In addition, compared with the low-GI meal, the high-GI meal resulted in higher serum insulin levels, lower plasma glucagon levels, lower postabsorptive plasma glucose and serum fatty acids levels, and elevation in plasma epinephrine. The area under the glycemic response curve for each test meal accounted for 53% of the variance in food intake within subjects. CONCLUSIONS: The rapid absorption of glucose after consumption of high-GI meals induces a sequence of hormonal and metabolic changes that promote excessive food intake in obese subjects. Additional studies are needed to examine the relationship between dietary GI and long-term body weight regulation.

Adolescent↗
PubMed1998

Extracellular acidification modifies Ca2+ fluxes in rat brain synaptosomes.

We examined the influence of external acidification on Ca2+ fluxes (45Ca2+ influx and 45Ca2+ efflux) in rat brain synaptosomes. A change on external pH (pHe) from 7.5 to 6.5 linearly decreased the 45Ca2+ uptake (5nmoles/mg protein/pHunit) and increased the 45Ca2+ efflux (1.5 fold/pH unit). These changes were both Na+ dependent and amiloride sensitive suggesting that the Na+/Ca2+ exchanger could be involved. The addition of the Ca2+ channel blockers (diltiazem, verapamil, nifedipine) did not prevent the decrease of the 45Ca2+ uptake evoked by acid pHe and so the involvement of the voltage-sensitive Ca2+ channels could be discarded. In order to determine whether the Na+/Ca2+ exchanger was directly activated by H+ or was indirectly activated by an internal mobilization of Ca2+ from intrasynaptosomal stores we examined the effect of pHe variation on phophoinositide hydrolisis. An increase on phosphoinositide hydrolisis was observed at acid pHe values (7 and 6.5). The hydrolisis was amiloride insensitive. On the other hand 1mM neomycin did inhibit the effect of acidic pHe on Ca2+ fluxes. Taken together, the results of our study provide evidence that external acidification stimulates phospholipase C leading to an increase in phosphoinositide hydrolisis and Ca2+ mobilization. The increase in intracellular Ca2+ would stimulate the Na+/Ca2+ exchanger, increasing Ca2+ efflux and reducing the global Ca2+ influx.

Animals↗