Assessing the impact of imidacloprid, glyphosate, and their mixtures on multiple biomarkers in Corbicula largillierti.

Pesticide mixtures are frequently utilized in agriculture, yet their cumulative effects on aquatic organisms remain poorly understood. Aquatic animals can be effective bioindicators and invasive bivalves, owing to their widespread distribution, provide an opportunity to assess these impacts. Glyphosate and imidacloprid, among the most prevalent pesticides globally, are frequently detected in freshwater systems in South America. This study aims to understand the cumulative effects of pesticide mixtures on aquatic organisms, using invasive Corbicula largillierti clams from a natural stream in northwestern Argentina. We conducted 48-hour exposure experiments using two concentrations of imidacloprid (20 and 200 µg L-1 a.i), two concentrations of glyphosate (0.3 and 3 mg L-1 a.i), and two combinations of these pesticides (both at low and high concentrations, respectively), simulating the direct contamination of both pesticides based on their agronomic recipe and observed values in Argentine aquatic environments. Clam metabolism was assessed through the examination of multiple oxidative stress parameters and measuring oxygen consumption rate as a proxy for standard metabolic rate (SMR). Our findings revealed that imidacloprid has a more pronounced effect compared to glyphosate. Imidacloprid significantly decreased clam SMR and cellular levels of reduced glutathione (GSH). However, when both pesticides were present, also cellular glycogen and thiobarbituric acid-reactive substances (TBARS) were affected. Proteins and glutathione S-Transferase (GST) activity were unaffected by either pesticide or their mixture at the assayed concentrations, highlighting the need to test several stress parameters to detect toxicological impacts. Our results indicated additive effects of imidacloprid and glyphosate across all measured parameters. The combination of multiple physiological and cytological biomarkers in invasive bivalves offers significant potential to enhance biomonitoring sensitivity and obtain insights into the origins and cellular mechanisms of chemical impacts. These studies can improve pollution regulatory policies and pesticide management.

A comparative evaluation of visual, refractive, and patient-reported outcomes of three diffractive trifocal intraocular lenses

@#OBJECTIVE: To compare the visual, refractive, and patient-reported outcomes of eyes implanted with one of 3 trifocal intraocular lenses (IOLs). METHODS: This is a cross-sectional, comparative, non-interventional study wherein subjects implanted with FineVision Micro F, AT LISA tri 839MP or AcrySof IQ PanOptix trifocal IOL after phacoemulsification were recruited. Manifest refraction, uncorrected and corrected visual acuity (VA) at distance, intermediate and near vision, contrast sensitivity, modulated transfer function (MTF) values and questionnaire answers were compared among the 3 groups using analysis of variance (ANOVA). RESULTS: Fifty-seven (57) eyes were included in the study: 21 eyes with FineVision (group A), 21 eyes with LISA tri (group B), and 15 eyes with PanOptix IOL (group C). The post-operative mean manifest spherical equivalent was -0.01D, -0.07D, and 0.05D, respectively (p=0.083). Uncorrected distance VA and best-corrected distance VA were similar among the groups. Groups A and C had better uncorrected and corrected intermediate VA at 80 cm and at 60 cm compared to group B. Group A had significantly better uncorrected near visual acuity than groups B and C (p=0.032). Mesopic contrast sensitivity testing showed group C had higher contrast sensitivities without glare in at the spatial frequency of 6 CPD (p=0.038) and with glare at 3 CPD (p=0.039) and at 12 CPD (p=0.009). MTF average height analysis showed that the group A had significantly superior resolution in far targets compared to groups B and C (p=0.001). At near targets, groups A and C had better resolutions compared to group B (p=0.017). There was no significant difference in patient satisfaction for far, intermediate and near VA among the groups. CONCLUSION: Eyes implanted with any of the 3 trifocal IOL designs achieved excellent uncorrected and bestcorrected distance, intermediate and near vision. FineVision and PanOptix provided significantly better intermediate vision than LISA tri at both 80 cm and 60 cm testing distance. FineVision had better near visual outcomes than PanOptix and LISA tri. Patient satisfaction was high in all 3 trifocal IOLS

Estableciendo protocolo de apoyo en microcirugía / Developing a protocol to support microsurgery

Microsurgery is a developing technique in our setting, and it’s success can be related to elements that are not related to the surgeon. Because of this, the Plastic Surgery Team in the Chilean Airforce Hospital has become aware of the need to develop a support protocol for microsurgery, which can be used in any setting throughout our country. It’s focus is set in optimizing and controlling physiological and anesthetic variables, and those not related to the technique itself, which can influence the microsurgery outcome and the patients perioperative morbi-mortality.

La microcirugía es una técnica en pleno desarrollo en nuestro medio y su éxito puede estar condicionado a veces a elementos externos al cirujano. Es por esto que, en el Hospital de la Fuerza Aérea de Chile, el Equipo de Cirugía Plástica ha notado la necesidad de diseñar un protocolo de apoyo a la microcirugía, el cual sea posible implementar en cualquier medio nacional. Su enfoque está dirigido a optimizar y controlar las variables fisiológicas, anestésicas y externas a la técnica quirúrgica en si misma, que podrían incidir en el éxito de la microcirugía como en la morbimortalidad perioperatoria de los pacientes.

Endosonografía rectal en la evaluación de focos de cáncer en adenomas rectales / Rectal endosonography to detect occult carcinoma in villous adenoma

Introducción: Entre un 30-40 por ciento de los Adenomas Vellosos (AV) rectales pueden presentar cáncer, lo que clínicamente puede no ser evidente, e incluso la biopsia endoscópica puede resultar negativa. Comunicaciones recientes sugieren que la Endosonografía Rectal (ER) sería un método apropiado para detectar focos de carcinoma invasor en AV. Objetivo: Evaluar la utilidad de la ER en la detección de focos de carcinoma invasor en AV y su eventual compromiso ganglionar. Material y método: Se analizaron en forma consecutiva 1400 ER, realizadas entre Febrero del 2000 y Julio del 2006 en el Hospital U.C. Se seleccionaron aquellas ER informadas como AV rectal. El informe de ER en cuanto a la extensión del tumor en la pared y el compromiso ganglionar (uT, uN) fue comparado con el informe de anatomía patológica de la pieza quirúrgica (pT, pN). Resultados: En 28 de los 35 pacientes con ER informadas como AV rectal se pudo contar con el estudio anatomopatológico y son quienes constituyen esta serie. En 17 pacientes se encontró cáncer invasor en el estudio anatomopatológico (60,7 por ciento). La concordancia entre ER y el estudio patológico para identificar focos de cáncer en AV fue 82 por ciento. El VPP fue 100 por ciento, el VPN 69 por ciento, la sensibilidad 71 por ciento y la especificidad 100 por ciento. La concordancia para diferenciar lesiones T0-T1 de lesiones más profundas fue 75 por ciento, y para establecer invasión ganglionar fue 84 por ciento. Conclusión: La ER permite una adecuada detección de focos de cáncer en AV junto a una apropiada etapificación.

Background: Thirty to forty percent of villous adenomas can be an occult carcinoma. Even biopsy can miss the diagnosis. Rectal endosonography can be useful to detect these malignant tumors. Aim: To assess the usefulness of rectal endosonography to detect invasive carcinoma and eventual lymph node involvement in villous adenomas. Material and methods: Retrospective review of 1400 rectal endosonographies performed between years 2000 and 2006. Those cases in which a rectal villous adenoma was informed, that were subjected to surgical excision and that had a pathology report were included in the study. Results: Thirty five rectal endosonographies were informed as rectal villous adenoma and 28 had a pathology report. In 17 of the latter, an invasive carcinoma was detected on pathology. The concordance between pathology and rectal endosonography to detect the carcinoma was 82 percent. Positive and negative predictive values, sensitivity and specificity of endosonography to detect carcinoma were 100, 69, 71 and 100 percent respectively. The concordance to differentiate T0-T1 lesions from deeper lesions and to detect lymph node involvement was 75 and 84 percent respectively. Conclusions: Rectal endosonography is useful to detect carcinomas in villous adenoma and to determine the stage of such tumors.

High-salt diet impairs hypoxia-induced cAMP production and hyperpolarization in rat skeletal muscle arteries.

This study determined the effects of hypoxia on diameter, vascular smooth muscle (VSM) transmembrane potential (E(m)), and vascular cAMP levels for in vitro cannulated skeletal muscle resistance arteries (gracilis arteries) from Sprague-Dawley rats fed a low-salt (LS) or a high-salt (HS) diet. Arterial diameter and VSM E(m) were measured in response to hypoxia, iloprost, cholera toxin, forskolin, and aprikalim. In HS rats, arterial dilation and VSM hyperpolarization after hypoxia, iloprost, and cholera toxin were impaired versus responses in LS rats, whereas responses to forskolin and aprikalim were unaltered. Blockade of prostaglandin H(2) and thromboxane A(2) receptors had no effect on responses to hypoxia or iloprost in vessels from both rat groups, suggesting that inappropriate activation of these receptors does not contribute to the impaired hypoxic dilation with HS. Hypoxia, cholera toxin, and iloprost increased vascular cAMP levels in vessels of LS rats only, whereas forskolin increased cAMP levels in all vessels. These data suggest that reduced hypoxic dilation of skeletal muscle microvessels in rats on a HS diet may reflect an impaired ability of VSM to produce cAMP after exposure to prostacyclin.

Contribution of extrinsic factors and intrinsic vascular alterations to reduced arteriolar reactivity with high-salt diet and hypertension.

OBJECTIVE: To determine whether the impaired relaxation of skeletal muscle arterioles of rats on high-salt diet or with reduced renal mass hypertension (RRM-HT) represents intrinsic alterations to microvessels alone, or whether extravascular influences also contribute to reduced dilator responses. METHODS: Normotensive (NT) Sprague-Dawley rats were fed low-salt (LS) or high-salt (HS) diets, and RRM-HT rats were fed HS diet for 4-6 weeks. In situ and isolated cremaster muscle first-order arterioles (1A) were examined using television microscopy, and a video micrometer was used to measure diameter changes in response to acetylcholine (ACH), cholera toxin (CT), and sodium nitroprusside (SNP). RESULTS: Compared to normotensive low-salt (NT-LS) rats, responses of 1A to the agonists were reduced in normotensive high-salt (NT-HS) and RRM-HT rats. Arteriolar reactivity to the agonists in NT-LS rats aid in NT-HS rats was not different between in situ and in vitro environments. However, in RRM-HT rats, the reactivity of 1A to each agonist was greater in isolated arterioles than in in situ arterioles. CONCLUSIONS: These results suggest that the impaired response of skeletal muscle arterioles to vasodilator stimuli in normotensive rats on high-salt diet primarily reflects alterations to microvessels alone, while reduced dilator responses in RRM-HT rats represent a combination of extravascular influences and intrinsic alterations to arterioles themselves.

Longitudinal differences in vascular control mechanisms in isolated resistance arteries of the rat cremaster muscle.

The purpose of this study was to determine if there are intrinsic differences in resting tone, vascular reactivity, myogenic responses, and neurogenic vasoconstriction between the large and small feeder arteries and first order arterioles (1A) of the rat cremaster muscle. The pudic-epigastric artery (PEA), external spermatic artery (ESA), and 1A were isolated and changes in vessel diameter were recorded in response to: (1) increases in intralumenal pressure, (2) inhibition of nitric oxide synthase (NOS), (3) norepinephrine (NE), (4) acetylcholine (ACh), and (5) perivascular nerve stimulation. Vessel responses to Ca(2+)-free physiological salt solution were measured to assess resting tone, which was significantly greater in the ESA and 1A compared to the PEA. NE caused a significant constriction of all vessels, with 1A exhibiting the greatest sensitivity. NOS inhibition did not alter vascular sensitivity to NE, but enhanced resting tone in ESA and 1A. ACh induced significant dilation in ESA and 1A, with minimal effect on PEA. The myogenic response was not different between ESA and 1A, but was minimal in PEA. Perivascular nerve stimulation induced a significant vasoconstriction in all vessels tested. These results suggest that the relative importance of different vascular control mechanisms varies substantially at different levels of the cremasteric arterial network and that the ESA and 1A may be the major site of active vascular regulation upstream from the cremaster muscle microcirculation.

Dyspepsia in children and adolescents: a prospective study.

BACKGROUND: Dyspepsia is poorly characterized in the pediatric population. The goal of the current study was to describe the clinical constellation and natural history of dyspepsia in children and adolescents seen in a pediatric gastroenterology practice. METHODS: A standardized questionnaire was administered by a pediatric gastroenterologist to all subjects 5 or more years of age (and their parents or guardians) treated in a referral pediatric gastroenterology practice for 1 month or more of abdominal pain or discomfort, nausea, or vomiting. Subjects with dyspepsia and dyspepsia subtypes (ulcer-like, dysmotility-like) were identified by using previously defined adult criteria. Evaluation and treatment were performed at the discretion of the attending pediatric gastroenterologist. RESULTS: During a 1-year period, 257 patients were screened with 127 subjects fulfilling criteria for dyspepsia (59% girls, 85% white; median age, 11.7 years; median duration of symptoms, 8 months). Symptoms were ulcer-like in 26% and dysmotility-like (nausea predominance) in 15% of subjects. In those with dyspepsia, irritable bowel syndrome and gastroesophageal reflux were noted in 24% and 43%, respectively. Esophagogastroduodenoscopy and biopsy were performed in 56 subjects with 21 (38%) having mucosal inflammation (Helicobacter pylori in 5). The remaining 35 subjects (62%) were considered to have functional dyspepsia. Duration of symptoms less than 1 year and vomiting were risk factors for mucosal inflammation. Follow-up at 6 months to 2 years revealed 70% of subjects were either asymptomatic or much improved regardless of the cause of dyspepsia. CONCLUSION: Most children and adolescents with dyspepsia do not have serious disease. In our referral population H. pylori infection was unusual, and no peptic ulceration was found. Most subjects with functional dyspepsia have improvement of symptoms over time.

Cable-piliated Burkholderia cepacia binds to cytokeratin 13 of epithelial cells.

Although the Burkholderia cepacia complex consists of several genomovars, one highly transmissible strain of B. cepacia has been isolated from the sputa of cystic fibrosis (CF) patients throughout the United Kingdom and Canada. This strain expresses surface cable (Cbl) pili and is thought to be the major strain associated with the fatal "cepacia syndrome." In the present report we characterize the specific 55-kDa buccal epithelial cell (BEC) protein that binds cable pilus-positive B. cepacia. N-terminal sequences of CNBr-generated internal peptides identified the protein as cytokeratin 13 (CK13). Western blots of BEC extracts probed with a specific monoclonal antibody to CK13 confirmed the identification. Mixed epidermal cytokeratins (which contain CK13), cytokeratin extract from BEC (which consists essentially of CK13 and CK4), and a polyclonal antibody to mixed cytokeratins inhibited B. cepacia binding to CK13 blots and to normal human bronchial epithelial (NHBE) cells. Preabsorption of the antikeratin antibody with the BEC cytokeratin fraction reversed the inhibitory effect of the antibody. A cytokeratin mixture lacking CK13 was ineffective as an inhibitor of binding. Colocalization of CK13 and B. cepacia by confocal microscopy demonstrated that intact nonpermeabilized NHBE cells express small amounts of surface CK13 and bind Cbl-positive B. cepacia in the same location. Binding to intact NHBE cells was dependent on bacterial concentration and was saturable, whereas a Cbl-negative isolate exhibited negligible binding. These findings raise the possibility that surface-accessible CK13 in respiratory epithelia may be a biologically relevant target for the binding of cable piliated B. cepacia.

Bone abnormalities in gastrointestinal and hepatic disease.

Bone is a dynamic tissue that undergoes constant remodeling in response to local and environmental stimuli. Bone mass is maintained by this delicate equilibrium between bone formation and bone resorption. In growing children, the balance is tilted toward bone formation until peak bone mass is achieved in the second decade of life. Alterations in bone metabolism can result in decreased bone mass (osteopenia and osteoporosis) or impaired mineralization of the bone protein matrix (rickets and osteomalacia). Diseases of the alimentary tract such as celiac disease, inflammatory bowel diseases, gastrectomy, cholestatic liver diseases, liver transplantation, and hepatitis C can affect bone mineralization, remodeling, or bone mass. This article presents a summary of recent reports concerning bone disorders associated with disorders of the liver and gastrointestinal tract.

Management of fibrosing pancreatitis in children presenting with obstructive jaundice.

BACKGROUND: Children with fibrosing pancreatitis are conventionally treated surgically to relieve common bile duct (CBD) obstruction caused by pancreatic compression. Residual pancreatic function has not been formally tested in these patients. AIMS: To evaluate the usefulness of non-surgical temporary drainage in children with fibrosing pancreatitis and to assess pancreatic function after resolution of their CBD obstruction. PATIENTS: Four children (1.5-13 years; three girls). METHODS AND RESULTS: Abdominal sonography and computed tomography revealed diffuse enlargement of the pancreas, predominantly the head. The CBD was dilated due to compression by the head of the pancreas. Pancreatic biopsy specimens obtained in three patients showed notable acinar cell atrophy and extensive fibrosis. Cystic fibrosis was excluded. No other cause of pancreatitis was identified. Pancreatic tissue from one patient contained viral DNA sequences for parvovirus B19 detected by polymerase chain reaction; serum IgM to parvovirus was positive. Three patients had temporary drainage of the CBD and one patient underwent a choledochojejunostomy. Serial imaging studies revealed resolution of the CBD obstruction with reduction in pancreatic size. Exocrine pancreatic function deteriorated. Three patients developed pancreatic insufficiency within two to four months of presentation. The fourth patient has notably diminished pancreatic function, but remains pancreatic sufficient. None has diabetes mellitus. CONCLUSIONS: Temporary drainage of the CBD obstruction is recommended in fibrosing pancreatitis in children along with close monitoring of the clinical course, before considering surgery.

Caffeine-induced apoptosis reveals a persistent lesion after treatment with bromodeoxyuridine and ultraviolet-B light.

Ultraviolet-B (UVB) light treatment of synchronized V79 Chinese hamster cells after pulse-labeling with bromodeoxyuridine (BrdUrd) reveals a marked age response for cell killing. Incubation after treatment in growth medium containing caffeine increases cell killing during the resistant portions of the cell cycle, resulting in a much less marked age response to UVB irradiation. Examination of the split-dose survival curves for BrdUrd and UVB light in the presence or absence of caffeine indicates that sensitization by caffeine is completely independent of the sparing effect of dose fractionation. Further, sensitization by caffeine is nearly complete after the first mitosis after the UVB exposure. With delayed addition of caffeine, however, nearly full sensitization can be elicited as late as two cell cycles after the treatment with BrdUrd and UVB light. Also, synchronized cells exposed to caffeine after treatment with BrdUrd and UVB in the S phase cease to incorporate radiolabeled thymidine and undergo apoptosis after the second mitosis. Thus exposure to caffeine reveals a persistent sensitivity lasting for at least two cell cycles, after the injury induced by treatment with BrdUrd and UVB.

Adherence to lipids and intestinal mucin by a recently recognized human pathogen, Campylobacter upsaliensis.

Campylobacter upsaliensis is a recently recognized human enteric pathogen associated with enteritis, colitis, bacteremia, and sepsis. Very little is known about the mechanisms of pathogenesis of this organism. The goals of this study were to determine whether C. upsaliensis binds to epithelial cells and whether there are specific lipid molecules that might serve as cell membrane receptors. In addition, we also explored C. upsaliensis binding to purified human small-intestinal mucin, since the mucus gel overlying the epithelium provides an initial contact surface for the bacteria and must be penetrated for the organisms to reach their cell receptors. Binding of C. upsaliensis to model epithelial cells was shown by microscopy adhesion assays, and binding to lipids was detected by thin-layer chromatography-overlay assays. Bacteria bound to phosphatidylethanolamine (PE), gangliotetraosylceramide (Gg4), and, more weakly, to phosphatidylserine (PS). There was no binding to ceramide, cholesterol, phosphatidylcholine, and globosides. Using receptor-based microtiter well immunoassays, we observed binding to be equal, specific, and saturable for PE and Gg 4 but low and nonspecific for PS. At least five bacterial surface proteins (50 to 90 kDa) capable of PE binding were identified by a lipid-silica affinity column technique. In slot blot overlay assays, biotin-labeled C. upsaliensis also bound in a concentration-dependent fashion to purified human small-intestinal mucin, implying that these microorganisms also express an adhesin(s) recognizing a specific mucin epitope(s). We speculate that binding to mucins may influence access of the bacteria to cell membrane receptors and thereby influence host resistance to infection.

Role of Fenton chemistry in thiol-induced toxicity and apoptosis.

Under certain conditions, many radioprotective thiols can be toxic, causing loss of colony-forming ability in cultured mammalian cells in a biphasic fashion whereby the thiols are not toxic at high or low concentrations of the drug, but cause decreased clonogenicity at intermediate (0.2-1.0 mM) drug levels. This symposium paper summarizes our studies using dithiothreitol (DTT) as a model thiol to demonstrate the role of Fenton chemistry in thiol toxicity. The toxicity of DTT in V79 cells has several characteristics: it is dependent on the medium used during exposure of cells to the drug; the toxicity is decreased or prevented by addition of catalase exogenously, but superoxide dismutase has no effect; the toxicity is increased by addition of copper, either free or derived from ceruloplasmin in serum; and the toxicity can be modified intracellularly by altering glucose availability or pentose cycle activity. Thus the data are consistent with a mechanism whereby DTT oxidation produces H2O2 in a reaction catalyzed by metals, predominantly copper, followed by reaction of H2O2 in a metal-catalyzed Fenton reaction to produce the ultimate toxic species, .OH. Studies comparing 12 thiols have shown that the magnitude of cell killing and pattern of dependence on thiol concentration vary among the different agents, with the toxicity depending on the interplay between the rates of two reactions: thiol oxidation and the reaction between the thiol and the H2O2 produced during the thiol oxidation. The addition of other metals, e.g. Zn2+, and metal chelators, e.g. EDTA, can also alter DTT toxicity by altering the rates of thiol oxidation or the Fenton reaction. Recent studies have shown that in certain cell lines thiols can also cause apoptosis in a biphasic pattern, with little apoptosis at low or high drug concentrations but greatly increased apoptosis levels at intermediate (approximately 3 mM) thiol concentrations. There appears to be a good correlation between those thiols that cause loss of clonogenicity and those that induce apoptosis, suggesting similar mechanisms may be involved in both end points. However, thiol-induced apoptosis is not prevented by addition of exogenous catalase. These observations are discussed in relation to the possible role of Fenton chemistry in induction of apoptosis by thiols.

Burkholderia (basonym Pseudomonas) cepacia binding to lipid receptors.

Piliated Burkholderia (formerly Pseudomonas) cepacia from sputa of cys tic fibrosis patients in Toronto, Canada, were shown earlier to bind to purified mucins and to a protein receptor on epithelial cells via a 22-kDa adhesin located on unique cable pili. However, a second receptor, thought to be lipid in nature, was also identified on cells and appeared to serve as the major cell receptor for poorly piliated or nonpiliated isolates. In the present study in vitro approaches were used to identify putative lipid receptors for B. cepacia and to explore the nature of the binding interaction. As judged by thin-layer chromatography overlay assays, the best receptors were digalactosylceramide and globotriosylceramide (Gb(3)). Both contain and unsubstituted terminal Gal alpha 1-4Gal sequence. B cepacia also bound moderately to galactosylceramide, gangliotriosylceramide, and gangliotetraosylceramide. Binding to glycolipids was not affected by tetramethylurea, a hydrophobic-bond-breaking adhesin for GB(3). Binding to glycolipids was not affected by tetramethylurea, a hydrophobic-bond-breaking agent. Binding was influenced by the structure of the ceramide, which probably affects the presentation of the agent. Binding was influenced by the structure of the ceramide, which probably affects the presentation of the carbohydrate epitope to the bacteria. Gb(3) was also the major receptor in lipid extracts of human erythrocytes, human buccal epithelial cells and HEp-2 laryngeal epithelial cells. In a receptor-based enzyme-linked immunosorbent assay, binding to Gb(3) within a phospholipid-cholesterol mixture (a membrane-like environment) increased and then approached saturation as a direct function of increasing bacterial concentration. The calculated value of K(a) (3.06 X 10(-8) ml/CFU), the affinity constant, was almost identical to the K(a) calculated earlier for B. cepacia binding to a set of lipid receptors in buccal epithelial cells (1.5 X 10(-8) to 2.0 X 10(-8) ml/CFU). Our findings suggest that within cell membranes, galactose-containing glycolipids, particularly Gb(3) are good candidates for receptors for B. cepacia, particularly for isolates in which cable pili are poorly expressed.

Radiation-induced apoptosis in HL60 cells: oxygen effect, relationship between apoptosis and loss of clonogenicity, and dependence of time to apoptosis on radiation dose.

Apoptosis in HL60 human leukemia cells irradiated in vitro was quantified using a DNA fragmentation assay. Dose-response curves for induction of apoptosis in HL60 cells 6 h after irradiation with 280 kVp X rays in air and hypoxia give an oxygen enhancement ratio (OER) of 2.7. This is similar to the OER of 2.8 obtained from survival curves for HL60 cells using a soft agar clonogenic assay. However, HL60 cells are much more sensitive to radiation-induced loss of clonogenicity than to induction of apoptosis at 6 h. For example, 12 Gy in air reduces the surviving fraction to about 0.002 in a clonogenic assay, but 12 Gy does not cause any significant increase in the percentage of apoptosis-like DNA fragmentation 6 h after irradiation compared to unirradiated controls. However, if apoptosis is assayed 2-4 days after irradiation, the HL60 cells show greater sensitivity, with 5 Gy in air causing 45-50% apoptosis at 3 days. When apoptosis is measured 3 days after irradiation, the OER is similar to that obtained for survival and for apoptosis at 6 h. Although the HL60 cells exhibit radiation-induced apoptosis if one waits 2-4 days after low doses of radiation, rather than just 6 h, to conduct the assay, the amount of cells undergoing apoptosis is still not sufficient to account for all the loss of clonogenicity seen when HL60 cells are exposed to ionizing radiation.

Slow-release 5-aminosalicylic acid therapy in children with small intestinal Crohn's disease.

Pharmacologic agents effective in the treatment of Crohn's disease confined to the small intestine are limited. The therapeutic efficacy of oral mesalazine in small bowel inflammation, although theoretically promising, remains unproven. In an open-labeled initial trial, timed-release 5-aminosalicylic acid (5-ASA), administered at a daily dosage of 30.6 +/- 9.0 mg/kg (mean +/- SEM) to children with active Crohn's disease involving the small intestine, was associated with improvement on the Harvey index in six of 12 patients treated for 8.1 +/- 3.9 weeks. In a subsequent prospective, double-blind study 14 children, ages 9.3 to 16.1 years, with active Crohn's disease limited radiologically in the small intestine were randomized to receive either timed-release 5-ASA [50 mg/kg/day (maximum 3 g/day)] or placebo for 8 weeks. Following a 4-week washout period, patients crossed over to receive the other study drug for a further 8 weeks. Six children completed the entire 20-week trial. The van Hees index improved among patients receiving 5-ASA for 8 weeks (delta = -18 +/- 6.4) but deteriorated among patients given placebo (delta = +14 +/- 4.1) (p < 0.05). Mean Crohn's Disease Activity Index (CDAI) decreased marginally after 8 weeks of 5-ASA treatment (delta = -48 +/- 38.2) but not with placebo (delta = -3.0 +/- 7.9) (p = 0.31). Of the eight noncompleters, more patients dropped out of the study because of lack of therapeutic response to placebo (n = 5) than to 5-ASA (n = 2).(ABSTRACT TRUNCATED AT 250 WORDS)