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Biomedical subjects

C Montoya

Publications and source records attributed to C Montoya.

16 recordsLinked to original sources
PubMed2005

Fenton's oxidation of food processing wastewater components. Kinetic modeling of protocatechuic acid degradation.

The oxidation of protocatechuic acid (PA), a typical phenol-type compound present in food processing wastewater, has been carried out by means of Fenton's reagent. Both the H2O2 and Fe(II) initial concentrations increase the PA degradation rate. Temperature also enhances the PA conversion when raised from 283 to 313 K, a further increase to 323 K results in a lower PA removal. Increasing the PA initial concentration leads to a decrease of conversion values but an opposite effect in terms of removal rate. pH values in the range 3-4 resulted in the total inhibition of the oxidation process. Similar PA depletion rates were experienced regardless of the oxidation state of the catalyst (ferrous or ferric iron). Additionally, an attempt based on the classic Fenton's chemistry plus some other stages accounting for the Fe(II) regeneration from Fe(III) and the inefficient H2O2 decomposition was conducted to model the process.

Catalysis↗
PubMed2000

Air bag-induced corneal flap folds after laser in situ keratomileusis.

PURPOSE: We describe a case of air bag-induced ocular trauma resulting in folds in the corneal flap 3 weeks after laser in situ keratomileusis. METHODS: Case report. Three weeks after laser in situ keratomileusis, a 20-year-old man was involved in a motor vehicle accident and sustained blunt trauma to the right eye, which caused corneal flap folds, corneal edema, anterior chamber cellular reaction, and Berlin retinal edema. RESULTS: Six weeks after laser in situ keratomileusis, persistent flap folds necessitated re-operation with lifting of the flap and repositioning. One week after the procedure, the visual acuity improved to 20/20-2, and the folds had cleared. CONCLUSION: Trauma after laser in situ keratomileusis may produce folds in the corneal flap. With persistence of these folds, management by lifting and repositioning the corneal flap may be necessary to permit recovery of visual acuity.

Accidents, Traffic↗
PubMed1997

[The health care system reform in The Netherlands].

In the sixties, The Netherlands advanced from a voluntary health insurance system, that had an incomplete covering and was unfair, towards a still partial obligatory and solidary insurance system. The insurance paid the hospitals and specialists per action and there was a great rise in cost of the system. A committee, presided by W Dekker, proposed a reform to reduce costs and increase equity. It abolished the difference between private and obligatory insurance systems (that covered 60% of the population) and made possible the competence between both types of insurance. It also created a negotiation margin between insurance companies and providers and replaced the payment per action by more efficient resource allowances. The debate originated by the reform hindered its full application. Meanwhile, the government took steps to reduce costs. Social and private insurance systems continue to exist. This article summarizes the special context of Dutch health care system problems.

Health Care Reform↗
PubMed1995

Comparison of three keratometry instruments.

We compared the reliability of measurements of three keratometers and keratometry readings from a corneal topography system to determine if they were as accurate as the "gold standard" Javal-Schiotz keratometer. Same-day measurement of the steepest and flattest powers of the central 3 mm of the corneas of 200 eyes (100 patients) revealed no statistically significant difference in reliability between the newer keratometers and the Javal-Schiotz. In addition, the newer machines are more convenient and efficient in some clinical settings.

Cornea↗
PubMed1979

Drinking behavior of children in Santiago, Chile.

Eighty per cent of the 9-year-old children studied had consumed alcohol, usually a beverage that was sweet and of low alcohol content; 28% drank once a week, 23% twice a week and 9% every day.

Alcohol Drinking↗
PubMedDate not supplied

Acute effects of soft drink intake on calcium and phosphate metabolism in immature and adult rats.

OBJECTIVE: To test the acute effects of the intake of a phosphoric acid containing soft drink on acid-base balance and on calcium and phosphate metabolism. MATERIAL AND METHODS: We studied 14 young adult male Sprague-Dawley rats aged 90 days, and 14 immature animals aged 30 days. Half of the animals in each group were randomly assigned to receive either tap water (controls), or Coca-Cola ad libitum for seven days. After this period, the rats were individually placed in metabolic cages to collect 24 hours urine, and they were exsanguinated by aortic puncture. Immediately, pH and ionized calcium were measured in whole blood. Creatinine, phosphate and total calcium were determined in the urine and plasma. Plasma levels of PTH, 1 alpha, 25 (OH)2 D3 and 25 OH D3 were measured by IRMA and RIA commercial kits. RESULTS: The animals receiving the soft drink, both adults and immature, developed significant hypercalciuria and hyperphosphaturia. In immature animals, the plasma pH dropped from 7.45 +/- 0.04 to 7.33 +/- 0.02 (p < 0.05) but did not change in adult animals. Ionized calcium dropped significantly from 1.06 +/- 0.04 to 0.80 +/- 0.06 meq/L (p < 0.05) in immature animals but not in the adult animals. Only immature rats developed significant reduction of 1 alpha, 25 (OH)2 D3 and 25 OH D3, whereas only the adult rats developed significant hyperparathyroidism. Immature animals showed more severe derangement of calcium and phosphate metabolism related to soft drink intake.

Acid-Base Equilibrium↗