Transepithelial or intrastromal femtosecond laser arcuate keratotomy to manage corneal astigmatism at the time of cataract surgery

PURPOSE

The aim of this study was to compare the results of intrastromal arcuate incisions (AIs) and transepithelial AIs to treat corneal astigmatism during femtosecond laser-assisted cataract surgery (FLACS).

METHODS

This retrospective study included 20 patients with corneal astigmatism between 0.70 and 2.00 diopters (D) who underwent FLACS with concurrent intrastromal AIs in one eye and transepithelial AIs in the fellow eye. The main outcomes measures at 2-3 months of follow-up were the difference between pre-operative and postoperative keratometric corneal cylinder (Kcyl), the correction index (CI) and the percentage of overcorrection.

RESULTS

The mean difference between preoperative and postoperative Kcyl revealed a mean value of 0.36 ± 0.37 D in the transepithelial group and 0.53 ± 0.42 D in the intrastromal group (p < 0.001). The mean CI was 0.83 ± 0.71 in the transepithelial group and 0.68 ± 0.29 in intrastromal group (p = 0.17). Five eyes (25 %) had an astigmatism overcorrection in the transepithelial group and 1 eye (5%) in the intrastromal group.

CONCLUSIONS

Both intrastromal and transepithelial AIs showed potential for mild to moderate astigmatism correction and appeared to be a safe procedure. Despite transepithelial AIs presented a higher CI, the intrastromal AIs results were more predictable.

Atmospheric BTX and polyaromatic hydrocarbons in Rio de Janeiro, Brazil

Polycyclic aromatic and monoaromatic (benzene, toluene and xylene, or BTX) hydrocarbons were monitored in Rio de Janeiro, Brazil, during the summer of 1998/1999. The levels of these aromatic chemicals decreased with distance from main roads, indicating mobile sources are the main pollutant emitters in this Latin American city. Benzo[ghi]perylene/indeno[1,2,3-cd]pyrene and benzene/toluene ratios corroborate this idea. However, higher benzene/toluene ratios at one of the major access routes into the city suggest pollutant inputs from a nearby refinery. Literature data were reviewed in order to outline differences and similarities among sources and levels of aromatic pollutants in large urban agglomerations worldwide. Concentrations of benzo[a]pyrene and benzene, which are well-known carcinogenic chemicals, were relatively low in Rio de Janeiro. This fact was attributed to specific atmospheric conditions during the tropical summer and differences in vehicle fuel composition.

Further lipophilic flavonols in Vellozia graminifolia (Velloziaceae) by high temperature gas chromatography: quick detection of new compounds

Further lipophilic flavonols present in Vellozia graminifolia have been determined by high temperature high resolution gas chromatography (HTHRGC) and by HTHRGC coupled to mass spectrometry (MS). These methods resulted in the detection, isolation and characterisation of a monoisoprenylated flavonol 3,5,4'-trimethoxy-3'-hydroxy-6,7-(2"-isopropenyldihydrofurano)flavone from the ethyl acetate extract of the whole plant. The structural elucidation was accomplished using spectral data, including two-dimensional NMR, and on chemical transformations. Both HTHRGC and HTHRGC-MS were shown to be alternative and extremely valuable methods for the quick screening of flavonoid aglycones and other chemical metabolites of the Velloziaceae.

Rapid screening of polar compounds in Brazilian propolis by high-temperature high-resolution gas chromatography-mass spectrometry

Methanol extracts of propolis from six different places, five in Rio de Janeiro state and one in São Paulo state, both in the Southeast of Brazil, were investigated using high-temperature high-resolution gas chromatography (HT-HRGC) and HT-HRGC-mass spectometry. The main purpose of the study was to establish the applicability of HT-HRGC as an analytical method for systematic studies of polar propolis fractions. Several compounds, including carbohydrates, phenolic acid derivatives, and high molecular weight compounds (e.g., wax esters of long chain fatty alcohols) could be readily characterized in the crude extracts by HT-HRGC-MS. HT-HRGC and HT-HRGC-MS were shown to be quick and informative tools for rapid analysis of crude polar extracts without cleanup.

Rapid screening of natural products by high-resolution high-temperature gas chromatography

The crude ethanol extracts from the leaves of three Croton hemiargyrus hemiargyreus plants are fractionated by thin-layer chromatography, yielding five fractions. The fractions and the crude extract are analyzed by high-temperature high-resolution gas chromatography coupled with mass spectrometry (HT-HRGC-MS). Several natural products, including thermolabile components, can be characterized directly in the samples, such as alkaloids, terpenes, flavonoids, acids, alcohols, etc. The cold on-column technique proves to be appropriate for the injection of these thermolabile compounds. HT-HRGC-MS is shown to be a valuable tool and an alternative technique to classical phytochemical procedures for the simple and fast routine analysis of natural products in crude extracts.

Atmospheric carcinogens in Rio de Janeiro during the summer of 1998/99: benzo[a]pyrene and benzene

Rio de Janeiro, the second largest city in Brazil, is affected by severe pollution episodes and presents a high respiratory cancer incidence in comparison with the rest of the country. To monitor atmospheric pollution during the summer of 1998/1999 and to estimate the impact of organic pollution on public health, we determined the levels of two carcinogenic organic chemicals, benzo[a]pyrene and benzene, in four distinct sites throughout the city. A review of the levels recorded in other urban areas worldwide during the last ten years indicates that the benzo[a]pyrene (< or = 0.70 ng/m3) and benzene (< or = 11 micrograms/m3) concentrations found in Rio are relatively low. The highest levels were generally recorded in developing Asian countries, whereas the lowest values were found in North America. Unlike urban areas in temperate zones, pollution derived from domestic heating is minor in Rio de Janeiro, where most of the benzo[a]pyrene and benzene pollution originates from vehicular traffic. The quite distinct fuels used in light-duty vehicles in Brazil, combined with strong light incidence and increased rainfall during the summer, also contribute to diminish the levels of such pollutants.

Sedimentary 4-desmethyl sterols and n-alkanols in an eutrophic urban estuary, Capibaribe River, Brazil

Sterols, n-alkanols, organic carbon (OC), C/N ratios and carbon isotope data (delta 13C) were investigated in sediments of the urban Capibaribe River estuary, NE Brazil, in order to assess allochthonous and autochthonous sources of organic matter (OM). Sedimentary OC values are high, but C/N ratios and delta 13C data generally fall within the range of values reported in other riverine systems, and suggest mixed inputs from aquatic and terrestrial matter. Mean values for total 4-desmethyl sterols and high molecular weight (HMW) n-alkanols are 11.0 micrograms/g and 2.8 micrograms/g, respectively. Sterols are found at highest levels in areas of enhanced urban outfalls. They can be related to major planktonic species growing in riverine waters. Stanol/stenol ratios suggest a high degree of alteration of the autochthonous OM as a result of elevated temperatures and microbiological proliferation. Even though sterols suggest the importance of autochthonous inputs to the river, HMW n-alkanols indicate major terrigenous accumulation at the mouth and 10 km upriver. Coprostanol and epicoprostanol levels are comparable to other sewage contaminated hydrosystems, but not as high as expected given the importance of sewage outfalls and low riverine water discharge. However, high (coprostanol)/(coprostanol + cholestanol) ratio values indicate that fecal contamination is significant.

Development and validation of a screening method for DES, zeranol, and beta-zearalanol in bovine urine by HRGC-MS and evaluation of robustness for routine survey of the Brazilian herd

A method and evaluated for screening and confirmation of diethylstilbestrol (DES), alpha- and beta-zearalanol in bovine urine was developed. The residues were extracted from urine by C18 cartridges and purified on alumina columns. For screening and confirmation purposes, the anabolic derivatives were analyzed by gas chromatography-mass spectrometry after derivatization with BSTFA + 1% TMCS or a solution of PFPA/acetone (1:2, v/v), respectively. The recovery of most analytes for the whole procedure was higher than 96%, with a detection limit of 0.5 ppb. This procedure is being routinely applied to the Brazilian National Program for the Control of Residues in Meat (PNCRBC).

Nutritional deficiencies in chronic alcoholics: relation to dietary intake and alcohol consumption

OBJECTIVES

Relationships of nutritional status with ethanol consumption and diet were studied in 33 chronic alcoholics with no clinical or laboratory evidence of liver disease.

METHODS

Nutritional assessment included subjective global assessment, weight-height index, body mass index, and serum albumin measurements. Dietary intake included estimates of daily intake of substrates, folic acid, vitamins B1, B5, B6, and B12. Circulating concentrations of folate, pyridoxal-phosphate and vitamin B12 were evaluated as well.

RESULTS

Only 18.1% of patients were considered malnourished, with body mass indices lower than those with an average or good nutritional status (p < 0.0001). Body weight was under 90% of the ideal in 8/33 (24%) patients. Serum albumin values were within normal range in all patients. In terms of calories provided by nonalcoholic substrates, protein, or vitamin intake, we observed no differences between well and poorly nourished individuals. However, malnourished alcoholics consumed significantly more ethanol (p = 0.01) and an inverse correlation was found between ethanol intake and weight-height index (r = -0.35; p = 0.03). Low circulating concentrations of pyridoxal-phosphate and red blood cell folate were found in 51.5% and 60.6% of alcoholics, respectively. These were not correlated with vitamin dietary intake or ethanol consumption, but there was a trend toward malnourished patients to present lower concentrations of red blood cell folate (p = 0.13).

CONCLUSIONS

Although over malnutrition is infrequent in this group of chronic alcoholics, specific vitamin deficiencies are present in a substantial proportion of patients and are more likely related to alcohol consumption.

Hyperhomocysteinemia in chronic alcoholism: correlation with folate, vitamin B-12, and vitamin B-6 status

Serum homocysteine concentrations have been shown to be a sensitive functional indicator of intracellular folate, vitamin B-12, and vitamin B-6 status. Chronic alcoholism is known to interfere with one-carbon metabolism, for which the above vitamins serve as coenzymes. In the present study, these vitamins were assessed in 32 chronic alcoholics and 31 healthy volunteers by measuring blood vitamin concentrations as well as serum homocysteine concentrations. In chronic alcoholics, serum pyridoxal 5'-phosphate and red blood cell folate concentrations were significantly lower than in the control subjects (P < 0.001 and P = 0.008, respectively). Mean serum homocysteine was twice as high in chronic alcoholics than in nondrinkers (P < 0.001). Beer consumers had significantly lower concentrations of homocysteine compared with drinkers of wine or spirits (P = 0.05). These results suggest that by interfering with folate or vitamin B-6 metabolism, chronic alcohol intake may impair the disposal of homocysteine through the transmethylation or transsulfuration pathways.